Method for improving optical properties of paper

FIELD: textiles, paper.

SUBSTANCE: in one of the aspects, the invention is directed to a method which enables mainly to maintain (or even increase) the brightness and/or whiteness of paper with increased degree of grinding the cellulose pulp, where the said method comprises grinding of the cellulose pulp till the freeness value of about 100 CSF and adding the composition OVA and a polymeric carrier to the paper surface in the size press in amounts sufficient to increase brightness and/or whiteness of the paper obtained. In another aspect, the invention is directed to a method of making paper from grinded cellulose pulp, which comprises grinding the suspension of cellulosic fiber to reduce the freeness up to about 100 CSF and mixing the cellulosic fiber with at least one optical bleaching agent (OBA) during or after the grinding stage and prior to adding any additional chemical ingredients of the wet stage of production.

EFFECT: effective maintenance or increase of brightness and whiteness of paper from the grinded cellulose pulp.

13 cl, 14 tbl, 34 dwg

 

This application claims the priority of provisional patent application U.S. No. 60/922057 filed April 5, 2007, and provisional application for U.S. patent No. 61/032588, filed February 20, 2008, which is incorporated into the present application by reference in their entirety.

The technical FIELD TO WHICH the INVENTION RELATES.

The present invention relates to methods of producing paper, intended to improve the brightness and whiteness of the paper. More specifically, the invention relates to a method of maintaining or increasing the brightness and whiteness of the paper produced from the pulp subjected to more severe grinding.

BACKGROUND of the INVENTION

Company for the production of paper are continually looking for ways to improve the brightness and whiteness of the different varieties of their paper, in particular paper for printing and mailing. Currently, the most common way to improve the brightness is to increase the number of optical bleaching agents (OBA's) or fluorescent agents to enhance the brightness/white or on the wet stage of production or in the sizing press. In many cases require the addition of significant quantities of OBA's. However, there are disadvantages associated with adding large quantities of OBA's, as for example, the staining of the water (recycled water) in white color and change the boot is paper production. In addition, the problem is the cost and availability OBA''s because OBA''s not only roads, but there is a significant demand with limited supply.

Paper mill mainly follow the General, and not specifically adapted to the methods of introducing chemical compounds which often leads to the use of factories too large amounts of OBA, because they are the main means of improving the brightness and whiteness of the paper. In addition, to compete with the new paper grades with improved brightness and/or whiteness of the paper mill, as a rule, consider maintaining a high content of OBA as the only means of improving the brightness and whiteness. Therefore, there is a need to find alternative ways to improve the brightness and whiteness of the paper without increasing and, preferably, even with a decrease in the number of used OBA.

Methods of paper production include a large number of variables that can affect the optical quality of the final product. The choice of the type of wood will have a huge impact on the grade of the produced paper, including the final brightness and whiteness. It is well known that excessive grinding paper pulp causes loss of its brightness. However, among other operations, the grinding is necessary to increase p is echnosti paper, the connection between the fibers, smoothness and improved molding. Factories for the production of high-grade paper is a thorough grinding of pulp to obtain properties such as opacity, porosity and strength. Some factories have to bring the weight up to a certain fineness, to match the key parameters of the processing, and there is only a very small space for change. The brightness of the pulp also affects the brightness of the resulting paper, i.e. the brighter the mass, the brighter the paper. Therefore, the loss of brightness of the pulp mass due to grinding has a significant negative effect on the brightness of the final product.

Despite the considerable effort that has been made to solve this problem in the development of existing products, there is still a need to preserve the brightness and whiteness during grinding of pulp and increase the brightness and whiteness of the paper in the most efficient way without increasing the use of OBA.

The INVENTION

The present invention is directed to a method of producing higher brightness and whiteness of the paper. The invention relates to increasing the brightness and whiteness with optimized chemical additives, and to preserve the brightness and whiteness when chopping cellulose mass.

In the first aspect of the invention relates to a method allowing to mainly preserve (or even increase) the brightness and/or whiteness of the paper with the strengthening of grinding pulp, where the method includes grinding paper pulp to reduce sagasti up to about 100 CSF and the introduction of combination OBA and the polymer carrier to the surface of the paper in a size press in an amount sufficient to increase the brightness and/or whiteness of paper.

The polymeric carrier is preferably polyvinyl alcohol (PVOH). The mass ratio of PVOH:OBA preferably is in the range from about 1:1 to about 16:1, more preferably from about 1.5:1 to about 12:1 and most preferably from about 2:1 to about 8:1.

Pulp is preferably crushed to a predetermined size sagasti. In one embodiment, the implementation level of sagasti is in accordance with the increase in brightness and/or whiteness compared with a higher level of sagasti. Preferably the mass clean up of sagasti, which basically corresponds to the point of the bundle of fibers.

Preferably OBA and PVOH pre-mixed before adding to the size press. OBA preferably added in an amount of from about 0.5 to about 15 lb/ton of pulp, more predpochtitel is about from about 5 to about 14 lb/ton of pulp, and most preferably from about 8 to about 12 lbs/ton pulp. PVOH is preferably added in an amount of from about 50 to about 150 pounds of raw product/ton of pulp, more preferably from about 70 to about 130 lb/ton of pulp, and most preferably from about 80 to about 120 lb/ton of pulp.

In the second aspect, the invention relates to a method allowing to mainly preserve (or even increase) the brightness and/or whiteness of the paper with the strengthening of grinding pulp. For example, the present invention is directed to a method of producing paper from shredded pulp, which comprises grinding a suspension of cellulose fibers to reduce sagasti up to level 100 CSF and mixing these cellulose fibers with at least one optical brightening agent (OBA) during or after the grinding stage and to add any additional ingredients to the wet stage of production. Preferably the grinding reduces sagasti to values from about 100 to about 400 CSF, more preferably from about 150 to about 350 CSF and most preferably from about 200 to about 325 CSF.

In one embodiment, the implementation of the method according to the present invention includes a grinding pulp to a preset value sagasti, adding OBA to the Zell is Osney weight on the wet stage of production, and adding to the pulp mass on a wet stage production of one or more additives wet phase selected from the group consisting of dyes, precipitated calcium carbonate (PCC) and anhydride alkenylamine acid (ASA); where OBA add additives to the wet stage, and where OBA and supplements wet phase is injected in amounts sufficient to increase the brightness and/or whiteness when a predetermined level of sagasti. Preferably, the pulp is a bleached pulp mass. Preferably PCC and/or dye added to the wet stage of production after the OBA and to any additional chemicals wet stage of production.

In one embodiment, the implementation of all of the above supplements wet stage of production add to the wet stage of the method of production of paper. Preferably, the dye and PCC add to the ASA. Preferably ASA is mixed with starch before adding to the pulp mass in the wet stage of production. Preferably, the starch is potato starch. ASA and starch are preferably mixed in a weight ratio of from about 1:1 to about 1:5, more preferably from about 1:2 to about 1:4 and most preferably from about 1:3 to about 1:4.

In another embodiment, the method according to the present invention additionally includes the em introduction to the wet stage of the paper production additional additives, selected from the group consisting of anionic polymer (PL), nanoparticles of silicon oxide (NP) and combinations of these substances. Preferably, additional additives/additive wet stage of production enter after adding other additives wet stage listed above, in the form of a restraint system. Nanoparticles (NP) are preferably used in the form of a microgel or at least partially aggregated Zola anionic nanoparticles of silicon oxide.

In one of the preferred embodiments, the additive wet phase is injected after OBA in the following sequence: PCC, dye, ASA and PL. In another preferred embodiment, the additive wet phase is injected after OBA in the following sequence: a dye, PCC, ASA, PL and NP. In another preferred embodiment, the additive wet phase is injected after OBA in the following sequence: PCC, dye, ASA, PL and NP. Preferably in each of the preferred sequences ASA before the introduction mixed with starch. The starch is preferably potato starch.

OBA preferably add the wet phase in an amount of from about 5 to about 35 lbs/ton of pulp, more preferably from about 10 to about 30 lbs/ton of pulp, and most preferably from about 15 to about 25 tuntutan pulp. The dye is preferably added in an amount of from about 0.01 to about of 0.25 lb/ton of pulp, more preferably from about 0.02 to approximately 0.2 lb/ton of pulp, and most preferably from approximately 0.05 to approximately 0.15 lb/ton of pulp. PCC is preferably added in an amount of from about 100 to about 600 pounds/ton of pulp, more preferably from about 300 to about 500 pounds/ton of pulp, and most preferably from about 350 to about 450 pounds/ton of pulp.

ASA preferably added in an amount of from about 0.5 to about 4 lbs/ton of pulp, more preferably from about 1 to about 3 lb/ton of pulp, and most preferably from about 1.5 to about 2.5 lbs/ton of pulp. In the embodiment where the ASA pre-mixed with starch, the mixture of ASA/starch is preferably added in an amount of from about 2 to about 14 lb/ton of pulp, more preferably from about 4 to about 12 lbs/ton pulp and most preferably from about 6 to about 10 lbs/ton of pulp.

In the embodiment, where PL and/or NP type on the wet stage, PL is preferably added in an amount of from approx the RNO 0.1 to about 2.5 lbs/ton of pulp, more preferably from about 0.3 to about 2 lbs/ton of pulp, and most preferably from about 0.5 to about 1.5 lb/ton of pulp. NP preferably added in an amount of from about 0.1 to about 2.5 lbs/ton of pulp, more preferably from about 0.3 to about 2 lbs/ton of pulp, and most preferably from about 0.5 to about 1.5 lb/ton of pulp.

In a preferred embodiment, in addition to adding OBA and additives wet phase, which was discussed above, the method according to the present invention includes a step of introducing a combination of OBA and PVOH on the surface of the paper in a size press in quantities sufficient to increase the brightness and/or whiteness of the resulting paper, as mentioned above.

Additional objectives, advantages and new features of the present invention will become clear to a person skilled in the field of technology in the study of the following description of the invention.

A BRIEF description of the ILLUSTRATIVE MATERIAL

Figure 1 is a schematic illustration of the nanoparticles of the first generation BMA-0.

Figure 2 is a schematic representation of nanoparticles third generation NP.

Figure 3 is a graph showing the effect of grinding on the brightness of the pulp from Dreux is ezine soft rocks and paper.

Figure 4 is a graph showing the effect of grinding on the brightness of the pulp from hardwoods and paper.

Figure 5 is a graph showing the effect of grinding on the brightness of the pulp from softwood and paper.

6 is a graph showing the effect of grinding, adding OBA and content of hardwoods on the brightness of the paper.

Fig.7 is a graph showing the effect of grinding, adding OBA and content of hardwoods on white paper.

Fig is a graph showing the effect of pH of the pulp in the brightness and whiteness.

Fig.9 is a graph showing the effect of grinding on the brightness of the paper when processing the surface of the OBA.

Figure 10 is a graph showing the effect of grinding on white paper with surface treatment OBA.

11 is a graph showing the effect of various chemical additives on the brightness of the paper.

Fig is a graph showing the effect of various combinations of chemical additives (2 chemical system) on the brightness of the paper.

Fig is a graph showing the effect of various combinations of chemical additives (3 chemical system) on the brightness of the securities is.

Fig is a graph showing the effect of additives on wet phase and surface additives OBA on the brightness of the paper.

Fig is a graph showing the effect of various combinations of chemical additives (4 chemical systems) on the brightness of the paper.

Fig is a graph showing the effect of various combinations of chemical additives (4 chemical systems) on white paper.

Fig is a graph showing the effect of various combinations of chemical additives (5 chemical systems) on the brightness of the paper.

Fig is a graph showing the effect of various combinations of chemical additives (5 chemical systems) on white paper.

Fig is a graph showing the effect of various combinations of chemical additives (6 chemical systems) on the brightness of the paper.

Fig is a graph showing the effect on the brightness of the paper chemical additives wet phase in combination with additives OBA on the wet stage and surface additives OBA.

Fig is a graph showing the effect on the brightness of the paper various chemical additives wet phase in combination with additives OBA on the wet stage and surface additives OBA.

Fig is a graph showing the effect on the white boom of the GI of various chemical additives wet phase in combination with additives OBA on the wet stage and surface additives OBA.

Fig is a graph showing the effect of the number of OBA on the brightness.

Fig is a graph showing the influence of the type of OBA for brightness and whiteness.

Fig is a graph showing the influence of the content of solids in PVOH on the brightness.

Fig is a graph showing the influence of the types/amount of PVOH on the brightness of the paper.

Fig is a graph showing the influence of the percentage of solids in PVOH 24-203 on the brightness of the paper.

Fig is a graph showing the influence of the percentage of solids in PVOH 24-203 on white paper.

Fig is a graph showing the comparison of efficiency of influence of the two OBA's on the brightness of the paper.

Fig is a graph showing the effect of surface additives OBA and correlation with PVOH on the brightness of the paper.

Fig is a graph showing the effect of surface additives OBA and correlation with PVOH on the brightness of the paper.

Fig is a graph showing the effect of pH of the pulp at various OBA's added for brightness of pulp.

Fig is a graph showing the effect of pH of the pulp at various OBA's added to the white pulp.

Fig PR is dstanley a graph demonstrating the influence of OBA and PVOH on the brightness of the paper for different levels of sagasti pulp.

DETAILED description of the INVENTION

The present invention is directed to a method of effective conservation and preferably increase the brightness and whiteness of the paper with the increased grinding pulp.

In one aspect of the present invention involves mixing the cellulose fibers in the pulp mass with at least one optical brightening agent (OBA) during or after the grinding stage before the introduction of any additional chemical additives wet stage. In one embodiment, implementation, OBA enter into contact with the fibers after a stage of grinding in the wet stage of production.

In the method according to the present invention can be applied to a wide range of OBA's and during implementation of the method according to the present invention can be applied to any traditional OBA, used, or which can be used to increase the brightness of wood or Kraft pulp. Optical brighteners are fluorescent compounds, similar to dyes which absorb short-wave ultraviolet light, invisible to the human eye, and emit it in the form of longer-wavelength blue color, resulting in the human eye perceives a higher degree of whiteness, and with the secret of this increases the whiteness of the finished product. This provides additional brightness and can compensate for the natural yellowish hue of the substrate, for example paper. In the present invention can be applied to a wide range of optical brighteners, and you can apply any suitable optical Brightener. The review of these brighteners should be sought, for example, in the book Ullmann''s Encyclopedia of Industrial Chemistry, Sixth Edition, 2000 Electronic Release, OPTICAL BRIGHTENERS--Chemistry of Technical Products, which is incorporated into the present application in its entirety by reference. Other applicable optical brighteners are described in U.S. patents№№ 5902454; 6723846; 6890454; 5482514; 6893473; 6723846; 6890454; 6426382; 4169819 and 5902454, all of these sources is incorporated into the present application by reference. Other applicable optical brighteners are described in published applications US patent No. US 2004/014910 and US 2003/0013628; and WO 96/00221, all of these sources are incorporated into the present application by reference. Typical examples of applicable optical brighteners are 4,4'-bis(creatininemia)stilbene-2,2'-disulfonate acid, 4,4'-bis(triazole-2-yl)stilbene-2,2'-disulfonate acid, 4,4'-dibenzobarrelenes, 4,4'-(diphenyl)stilbene, 4,4'-distributively, 4-phenyl-4'-benzoxazolinone, libuninameslist, 4-steelstyle, bis(benzoxazol-2-yl) derivatives, bis(benzimidazole-2-yl) derivatives, coumarins, pyrazoline, naphthalimide, Tr asinilyty, 2-tirelessly or naftoxate, benzimidazole-benzofuran or oxanilide.

Most commercially available optical bleaching agents are derivatives of stilbene, coumarin and pyrazoline, and these derivatives are preferred for use in the practical implementation of the present invention. Preferred optical brighteners for use in the present invention are used in the paper industry optical brighteners based on stilbene, for example, 1,3,5-triazinyl derivatives of 4,4'-diaminostilbene-2,2'-disulfonic acid and its salts, which may contain additional sulfopropyl, for example, 2,4-and/or 6 positions. Most preferred are the commercially available derivatives of stilbene, such as derivatives, available from Ciba Geigy under the trade name "Tinopal", from Clariant under the trade name "Leucophor", Lanxess under the trade name "Blankophor" and 3V under the trade name "Optiblanc", for example, optical whitening agents on the basis of disulfonate, tetrasulfonated and hexadentate stilbene. Of these the most preferred commercially available optical bleaching agents, preferred are optical whitening agents on the basis of disulfonate and tetrasulfonic the stilbene, moreover, commercially available optical whitening agents on the basis of disulfonated stilbene are the most preferred. Although the authors of the present invention, preferred methods and systems of the fiber-OBA, which use the above OBA, the present invention is in no way limited to those shown in the example, variants of implementation, and the invention can be applied to any OBA.

In another embodiment, the method according to the present invention includes the introduction of a filler and/or dye on the wet stage after OBA and to add any additional chemical components wet stage. Suitable mineral fillers of conventional types can be added to the aqueous suspension of cellulose according to the present invention. Examples of suitable fillers include kaolin, kaolin, titanium dioxide, gypsum, talc and natural or synthetic calcium carbonates such as chalk, ground marble and precipitated calcium carbonate (PCC). The preferred filler is PCC. Can be used any dyes normally used on wet stage of paper production. In one preferred embodiment, can be used this dye, as Premier Blue 2GS-MT, which can be purchased from Royal Pigments.

In yet another embodiment, after addition of PCC and/or CRAs is Italia on the wet stage of production type restraint system, where restraint system includes an anionic polymer and a microgel or at least partially aggregated colloidal solution of anionic nanoparticles of silicon oxide. Depending on the charge and the need to balance the charges on the pulp weight, it may be worthwhile adding a cationic polymer and/or adhesive agent before adding the restraint system. In one variant of implementation before adding restraint system type in combination ASA and cationic potato starch.

Restraint system may include any of several types of anionic polymers used as dewatering and retention means, for example, anionic organic polymers. Anionic organic polymers, which can be used according to the present invention may include one or more negatively charged (anionic) groups. Examples of groups that may be present in the polymer and the monomers used for the polymer include group bearing an anionic charge and acid groups, which occurs anionic charge when dissolved or dispersed in water, where these groups are collectively referred to as anionic groups, for example, phosphates, phosphonates, sulfates, group, sulfonic acids, sulfonates, the group of carboxylic acids, carboxylates, alkoxides and feelin the e group, i.e. the replacement family and nattily. Groups that carry a anionic charge, as a rule, are salts of alkali metals, alkaline earth metals or ammonium.

Anionic organic particles, which can be used in the present invention include cross-linked anionic vinyl additive polymers, respectively, copolymers comprising anionic monomer such as acrylic acid, methacrylic acid and from sulphonated or Vospominanie vinyl additive monomers, usually copolymerizable with nonionic monomers such as (meth)acrylamide, alkyl(meth)acrylates, etc. Applicable anionic organic particles include anionic polymers obtained by condensation of, for example, sols melamine-sulfonic acid.

Other anionic polymers, which may be part of dehydrating and restraint systems include vinyl additive polymers containing anionic monomer having a carboxylate group such as acrylic acid, methacrylic acid, ethylacrylate acid, crotonic acid, taconova acid, maleic acid, and salts of all of these acids, anhydrides of decislon, and from sulphonated additive vinyl monomers, for example, from sulphonated styrene, usually copolymerizable with nonionic monomers such as acrylamide, and kilakila etc., for example, disclosed in U.S. patent No. 5098520 and 5185062, the contents of which are incorporated into the present application by reference. Anionic vinyl additive polymers respectively have a mass-average molecular weight of from about 50,000 to about 5000000, usually from about 75,000 to about 1250000.

Examples of suitable anionic organic polymers further include the products of step polymerization products of increasing chains, polysaccharides, natural aromatic polymers and their modification. The term "product of step polymerization" in this application refers to a polymer obtained by stepwise polymerization, also called the product of step response or step-reaction polymerization, respectively. Anionic organic polymers can be linear, branched or cross-linked. Preferably the anionic polymer is soluble or dispersible in water. In one embodiment, the implementation of the anionic organic polymer may contain one or more aromatic groups.

Anionic organic polymer comprising organic groups may contain one or more aromatic groups, the same or different types. Aromatic groups of the anionic polymer can enter into the frame of the polymer or in the replacement group, which is connec the us to the skeleton of the polymer (main chain). Examples of suitable aromatic groups include aryl, kalkilya and alkaline groups and their derivatives, for example, phenyl, tolyl, naphthyl, phenylene, xylylene, benzyl, phenylethyl, and derivatives of these groups.

Examples of suitable anionic aromatic products of step polymerization include polycondensation products, i.e. polymers obtained by stepwise polycondensation, for example, condensates of an aldehyde, such as formaldehyde, with one or more aromatic compounds containing one or more anionic groups, and optionally other comonomers used in the polycondensation, for example, urea and melamine. Examples of suitable aromatic compounds containing anionic groups include benzene and naphthalene compounds containing anionic groups, for example, phenolic and naftalie compound, such as phenol, naphthol, resorcinol and derivatives thereof, aromatic acids and their salts, for example, phenyl, phenol, raftiline and naftalie acid and salts, as a rule, sulfonic acids and sulfonates, for example, benzolsulfonat acid and sulfonates, cellsurvival acid and sulfonates, naphthalenesulfonate acid and sulfonates, phenolsulfonic acid and sulfonates. Examples of suitable anionic products of step polymerization according to the present invention include anionic polycondensation products, including benzene and naphthalene fragments, preferably polymers containing fragments naphtalenesulfonic acid and naphthalenesulfonate.

Examples of other suitable anionic polycondensation products containing aromatic groups include an additive polymers, i.e. polymers obtained by stepwise additive polymerization, for example, anionic polyurethanes, which can be obtained from a mixture of monomers comprising aromatic isocyanates and/or aromatic alcohols. Examples of suitable aromatic isocyanates include diisocyanates such as toluene-2,4 - and 2,6-diisocyanate and difenilmetana-4,4'-diisocyanate. Examples of suitable aromatic alcohols include diatomic alcohols, i.e. diols, such as bisphenol a, phenyldiethanolamine, glycerol Montereale and trimethylolpropane Montereale. Can also be used monohydroxy aromatic alcohols such as phenol and its derivatives. The mixture of monomers may also include non-aromatic isocyanates and/or alcohols, usually diisocyanates and diols, for example, any of these compounds are known that they are used in obtaining polyurethanes. Examples of suitable monomers containing anionic groups include products monoesterification of triolo, for example, trimethanolamine, trimethylolpropane and glycerol under the action of di is Urbanovich acids or their anhydrides, for example succinic acid and its anhydride, terephthalic acid and its anhydride, for example, monocalcium glycerin, Montereale glycerin, monocalcium of trimethylolpropane, Montereale of trimethylolpropane, N,N-bis(hydroxyethyl)glycine, di(hydroxymethyl)propionic acid, N,N-bis-(hydroxyethyl)-2-aminoetansulfonovaya acid and the like, optional and usually in combination with a reaction with a base, for example, hydroxides of alkali and alkaline earth metals, e.g. sodium hydroxide, ammonia or an amine, such as triethylamine, with the formation of alkali metal counterion, alkaline earth metal or ammonium.

Examples of suitable anionic products increasing chain containing an aromatic group include anionic vinyl additive polymers obtained from a mixture of ethylene vinyl or unsaturated monomers comprising at least one monomer containing an aromatic group and at least one monomer containing an anionic group, usually copolymerizable with non-ionic monomers, such as acrylates and acrylamide monomers. Examples of suitable anionic monomers include (meth)acrylic acid and para-vinylphenol (hydroxytrol).

Examples of suitable anionic polysaccharides containing aromatic groups include starches, guar gums, cellulose, chitina,chitosans, glikana, galactanes, glucans, xanthan gums, pectins, mannans, dextrins, preferably starches, guar gums and cellulose derivatives, suitable starches, including potato, corn, wheat, cassava, rice, waxy maize and barley, preferably potato. Anionic groups of the polysaccharide can be natural and/or introduced by chemical treatment. Aromatic groups of the polysaccharide can be introduced by chemical methods known in the technique.

Natural aromatic anionic polymers and products of their modification, i.e. modified natural aromatic anionic polymers of the present invention include natural polyphenolic compounds present in wood and organic extracts of the bark of some tree species, and their chemical modification, as a rule, from sulphonated modification. The modified polymers can be obtained by chemical methods, such as sulfite cooking of pulp and sulphate cooking pulp. Examples of suitable anionic polymers of this type include polymers based on lignin, preferably, from sulphonated lignins, e.g. ligno-sulfonates, Kraft lignin, from sulphonated Kraft-lignin and tannin extracts.

Srednevekovaja molecular weight anionic polymer, including arene is political group, may vary within wide limits depending on, among other things, the type of the applied polymer, and is usually specified weight is at least about 500, more than about 2000, and preferably more than about 5000. The upper limit does not play a critical value; it can be about 200000000, usually about 150000000, often about 100000000 and preferably about 10000000.

Anionic polymer comprising aromatic groups may have a degree of anionic substitution (DSAvarying within wide limits depending on, among other things, the type of the applied polymer; DSAis usually from 0.01 to 2.0, more often from 0.02 to 1.8 and preferably from 0.025 to 1.5; and the degree of aromatic substitution (DSQmay be from 0.001 to 1.0, usually from 0.01 to 0.8, more often from 0.02 to 0.7 and preferably from 0.025 to 0.5. If the anionic polymer contains cationic groups, the degree of cationic substitution (DSC) may be, for example, from 0 to 0.2, more often from 0 to 0.1 and preferably from 0 to 0.05, and the anionic polymer has a total negative charge. Usually the density of the negative charge of the anionic polymer is in the range from 0.1 to 6.0 mEq/g dry polymer, usually from 0.5 to 5.0 and preferably from 1.0 to 4.0.

Examples of suitable aromatic anionic organic polymers that can be used for this is obreteniyu, include polymers described in U.S. patent No. 4070236 and 5755930; and published international patent applications nos WO 95/21295, WO 95/21296, WO 99/67310, WO 00/49227 and WO 02/12626, which is incorporated into the present application by reference.

In addition to the above-mentioned cationic and anionic dewatering and retention means as dewatering and retention means can be used cationic organic polymers of low molecular weight and/or inorganic compounds of aluminum.

Cationic organic polymers of low molecular weight (hereinafter referred to as LMW), which can be used in combination with drying and retaining means include polymers, which are usually referred to and used as traps anionic contaminants (ATC). ATC's known in the art as a neutralizing and/or capture agents for preventing/harmful anionic substances present in the pulp mass, and their use in combination with dewatering and retention means often allows you to make additional improvements to drainage and/or retention. LMW cationic organic polymers can be obtained from natural or synthetic sources, and preferably they are synthetic polymers LMW. Suitable organic polymers of this type include cationic organic polymers LMW, carry a significant charge, such as polyamine, polyamidoamine, polyethyleneamine, Homo - and copolymers based on diallyldimethylammonium chloride, (meth)acrylamide and (meth)acrylates, polymers based vinylamide and polysaccharides. As for the molecular weight retention and dewatering polymers, srednevekovaja molecular weight LMW cationic organic polymer preferably is low; it is usually at least about 2000, and preferably at least about 10,000. The upper limit of molecular weight is usually from about to about 2000000 3000000. Suitable polymers LMw may have srednevekovoy molecular weight of from about 2000 to about 2000000.

Aluminum compounds that can be used as ATC's of the present invention include aluminum alum, aluminates, aluminium chloride, aluminum nitrate and semi-aluminum compounds such as polyaluminosilicate, polyaluminium sulfates, semi-aluminum compounds containing chloride and sulfate ions, polyaluminosilicate-sulfates and mixtures thereof. Semi-aluminum compounds can also contain other anions other than chloride ions, for example, anions of sulfuric acid, phosphoric acid, and organic acids such as citric acid and oxalic acid.

Preferred anionic polymers include anionic polymers having the designation PL that mo is ut to be purchased from Eka Chemicals, for example, PL 1610, PL 1710 and PL 8430. In addition, cationic polymers production Eka Chemicals, for example, PL 2510, can also be used in the present invention.

In one of the preferred embodiments, the restraint system includes anionic particles based on silica. Examples of suitable particles on the basis of silicon oxide include particles having an average size less than about 100 nm, for example, less than about 20 nm or in the range of from about 1 to about 10 nm. Preferably, the average particle size is from about 1 to about 5 nm. As considered in the chemistry of silica, the particle size refers to the average size of the primary particles, which can be aggregated or not aggregated. According to one embodiments, the anionic particles on the basis of silicon oxide are aggregated anionic particles of oxide silicon. Specific surface area of particles of oxide silicon is usually not less than 50 m2/g, for example, not less than 100 m2/, As a rule, the specific surface area can reach about 1700 m2/g, more often up to about 1000 m2/g Specific surface area measured by titration with NaOH as described G.W.Sears in Analytical Chemistry 28(1956): 12, 1981-1983 and in U.S. patent No. 5176891 after removing the appropriate way or amendment to any connection the care, present in the sample that may interfere with the titration as, for example, aluminum compounds and boron. Thus obtained square represents the average specific surface area of particles.

In one of the embodiments of the present invention the anionic particles on the basis of silicon oxide have a specific surface area in the range from 50 to 100 m2/g, for example, from 100 to 950 m2/, Particles on the basis of silicon oxide may be present in the ashes, having an S-value in the range from 8 to 50%, for example, from 10 to 40%, containing particles based on silica with a specific surface area in the range from 300 to 1000 m2/g, usually from 500 to 950 m2/g, for example, from 750 to 950 m2/g, and these sols can be modified, as described above. S-value is measured and calculated as described Iler & Dalton in J.Phys.Chem. 60(1956), 955-957. S-value indicates the degree of aggregation or formation of microgel and a lower S-value indicates a higher degree of aggregation.

In yet another embodiment of the present invention, particles of oxide silicon have a high specific surface area, for example, above about 1000 m2/g Specific surface area can be in the range from 1000 to 1700 m2/g, for example, from 1050 to 1600 m2/year

Preferred particles on oslovakia silicon, which can be used in the method according to the present invention include particles of oxide silicon, marked NP, available from Eka Chemicals, for example, NP 320 and NP 442.

EXAMPLES

The following describes the materials, equipment and techniques of research used in the examples:

Materials

The Kraft pulp was obtained from Southern U.S. mill. Used a lot with bleaching stages D1 and D2. Samples of pulp from hardwoods (HW) and softwood (SW) with stage D2 was decolorized to obtain a higher brightness level by adding phase oxidation by the peroxide (P) (D0-Eop-D1-D2-P). Samples of the pulp separately crushed in a roll Valley. Levels of sagasti pulp after treatment (CSF) is given in table 1, along with values of sagasti pulp, consisting of a mixture of 60% solid wood/40% softwood, after cleaning.

Table 1
Sagasti pulp before and after treatment for the three stages of bleaching and the ratio of 60%HWY/40%SW
The ISO brightness of pulp to clean
Designation sampleSagasti (CSF)
HW D1625
HW D2550
HW P625
The ISO brightness of pulp after treatment
Designation sampleSagasti (CSF)
HW D1300
HW D2310
HW P295
The ISO brightness of pulp after cleaning and mixing
Designation sampleSagasti (CSF)
D1 60% HW345
D2 60% HW350
P 60% HW350

Chemical reagents used for the manual production of batches of the paper included a filler, adhesive, cationic starch, means for holding Zola silicon oxide, ionic polymers, optical whitening agents, carriers and colorants.

The equipment and techniques of research

For the manufacture of the paper samples manually and VC measurement is controlled properties used the following tools, equipment and testing methods:

equipment used included: roll valley for grinding pulp; 2) form for making paper by hand; 3) wet press and drum dyeing apparatus for drying sheets of paper; 4) automatic table feed for coating sheets of paper; 5) measuring the Technidyne brightness to determine the brightness, whiteness, coefficients of scattering and absorption; 6) the tester DDA for turbidity and dehydration.

The method of measuring the brightness D65 was developed Technidyne in accordance with ISO 2470:1999. Calibrating the amount of UV is described in ISO 11475:2002 and whiteness CIE/10° according to ISO 1475:2002.

The research method used for measuring sagasti treated and untreated pulp, was a canadian Standard test to determine sagasti (TAPPI method T227).

Nanotechnology

Used two methodologies associated with nanoparticles. One of them refers to particles of anionic colloidal Sol of silicon oxide of the third generation, manufactured by Eka Chemicals (NP), and other existing technologies, the first generation (BMA-0). Nanoparticles NP is smaller in size, have a modified surface suitable for acid and alkaline systems and are able to form long chains of approximately 25 nm. The primary particles of silicon oxide are not aristida and spherical, they can have a surface area in the range of 500-3000 m2/g, while the surface area of the swollen fibers of the wood is approximately 200 m2/year Surface of silicon oxide is acidic, and the protons are released from silanol groups. Differences between particles BMA-0 and NP are shown in figure 1 and 2.

COMPARATIVE EXAMPLE 1

Carried out experiments to evaluate the impact of grinding on some properties of paper. Pulp mass of soft and hard wood, respectively, were selected at the stage of bleaching D2 at a paper mill (i.e. the second stage of bleaching ClO2). Some samples of pulp were left without treatment, and some samples were crushed in a roll Valley to various degrees of sagasti. Pulp mass of soft and hard wood crushed to 380 CSF and 340 CSF, respectively. Of ground and unground pulp produced pads for measuring the brightness (5 g) and measured the brightness of the instrument Technidyne Color Lab, likewise, both types of paper pulp manually produced sheets of paper (1.6 g) to assess the loss of brightness due to grinding.

Figure 3 and 4 shows the effect of grinding on the brightness of the paper and pulp. Figure 3 shows that the brightness of the pulp of soft wood after grinding decreased by 9%, while brightness is paper decreased more significantly namely 25%. Figure 4 shows that the brightness of the pulp of hardwood decreased by 3.4%, while the brightness of the paper after grinding has been reduced by 17%. Both of these pictures show the difference in the loss of brightness not only between hard and soft wood, but most importantly, they demonstrate that the paper is largely lose brightness in the grinding pulp. For white paper characterized by the same trend as for the brightness, i.e. the grinding was also observed a decrease in white. The pulp from the stage bleaching D1 (i.e. after the first stage of bleaching ClO2) showed the same trend, as can be seen in figure 5.

EXAMPLE 1

Carried out experiments to determine the impact that the ratio of the woods (HW SW) in the pulp mass, optical whitening agent, the pH of the pulp and grinding on the brightness and/or whiteness. Pulp mass from the stage bleaching D1 grinds up to 5 different levels of sagasti to assess the impact of grinding on the brightness. The evaluation was carried out for three different ratios of wood in the pulp weight of 100% solid wood (100% HW), 60% of solid wood in a mixture with 40% of soft wood (60% HW) and 100% soft wood pulp weight (0% HW). Research produced for the two levels of the she pH, moreover, the pH of the pulp was brought to 5.5 and 7. As optical whitening agent (OBA) was used Optiblanc Disulfonate production 3V. OBA for surface treatment was mixed with PVOH Celvol 24-203 with a solids content of 8.3%, which played the role of existing media. In some experiments did not use OBA, in some added 20 pounds/ton wet phase (WE), others have added 10 lbs/ton at the stage size press (SP) and some OBA was added as a wet stage, and was applied to the surface (WE & SP).

In the described experiments, unground the pulp from wood durum had sagasti 625 CSF, and soft varieties sagasti was 730 CSF. Pulp mass from solid wood crushed when consistency of 1.5% to 510, 425, 355, 250 CSF and pulp weight of soft wood was crushed to 570, 490, 410, 300 CSF. The crushed pulp mass was mixed in the ratio of 60% by weight of durum and 40% by weight of the soft varieties. The resulting mass is manually produced sheets of paper and added OBA or on the wet stage, or in the sizing press. In the manufacture of sheets did not apply any other chemical additives in order to observe the interaction of OBA with the fibers. Consideration of Figure 5 and 6 shows the effect of grinding pulp without addition of any OBA (basic sample papers is for comparison). For samples made with the addition of 20 lb/ton OBA, the introduction of bleach was carried out directly on the cleaned pulp mass to the manufacture of the paper samples to simulate the introduction of OBA on the wet stage. In the case of samples produced with the addition of 10 pounds/tonne OBA, OBA was introduced on the surface of the paper, using automatic unit to simulate the addition of OBA in the sizing press. In addition, the produced samples with the addition of OBA on the wet stage, and in the sizing press.

Figure 6 and 7 shows the results of a study of the impact grinding, adding OBA and the ratio of wood in the pulp mass in the brightness and whiteness of the resulting paper. Review 6 demonstrates the following:

1. Grinding reduces the brightness of the paper under all conditions, regardless of added OBA or not. There is a significant decrease in brightness at lower CSF from non-crushed crushed samples.

2. Samples of paper made from 100% soft wood, have a more significant loss of brightness.

3. Superficial introduction of OBA in the amount of 10 pounds/ton significantly increases the brightness compared to the baseline sample.

4. The introduction of OBA in the amount of 20 lb/ton of wet stage results in a similar brightness when additionally the m adding 10 pounds/ton in the sizing press.

5. Soft wood when chopping is also losing a lot of white in comparison with the solid wood.

Fig.7 shows that the trends for white similar to the trends for brightness, with the difference that the surface adding OBA in the amount of 10 pounds/ton results in a level of white, similar to adding 20 pounds/ton on the wet stage of production and 30 pounds/ton in the combined addition of OBA.

Consideration pig allows to detect that the value of pH, apparently, does not have any effect neither for brightness or white paper.

The introduction of the mixture OBA and PVOH in the amount of £ 10/tonne on the surface of the paper allows you to achieve unusual high brightness and whiteness, as can be seen in figures 9 and 10. These maximums, it seems, are near the point of separation of the fibers for hard wood, soft wood, and combinations thereof. For 100% fiber hardwood maxima of brightness and whiteness are about 355 CSF; 100% fiber soft rock (0% HW) maximum brightness and whiteness are near 410 CSF; and for a combination of 60% hardwood and 40% soft wood maximum is near 409 CSF. Unexpected increased brightness means that it is possible to grind the pulp mass to smaller values sagasti (to improve molding and smoothness of the paper, in the ocher is ü improves printing on paper) and at the same time to get the brightness, as if grinding was carried out to a value of 510 for 100% HW, 570 CSF for 100% soft wood (0% HW) and 534 CSF mixture 60/40 HW/SW. The above figures indicate, moreover, that further grinding, beyond the maximum will decrease the brightness and whiteness.

6 and 7 show that the control curves for the samples without the addition of OBA" have a rather small maximum, but in the case of adding OBA, mixed media PVOH on the surface of the paper, there is a sharp maximum brightness and whiteness of the paper (which is shown in figures 9 and 10).

Describes a series of experiments shows that the growth of grinding, the brightness and whiteness of paper is reduced, but there is a point with a certain degree of grinding, in which the brightness and whiteness increase. The observed peaks probably correspond to the level grinding near the point of the bundle of fibers.

COMPARATIVE EXAMPLE 2

Conducted a study of over 800 commercially available varieties of white paper without coating with respect to their brightness and whiteness, to determine their industrial classification and measurement of levels of brightness and whiteness, typical for the industry. The results of these evaluations showed that the sheet of paper without coating have higher brightness and whiteness. 10 paper grades with the highest brightness and whiteness is shown below in tables 1 and 2. Of all grades tested in terms of brightness and whiteness (excluding coated paper, coated and LWC), 10 of the best grades of uncoated paper with high brightness and whiteness are shown in tables 2 and 3. These data were considered as the target in experiments on the introduction of combinations of chemical additives.

Table 2
Ten varieties of paper with the highest brightness
OrderManufacturerPurpose/name gradeBrightness (D65)
1XeroxPremium Laser116,84
2WeyerhaeuserCougar Text Vellum116,21
3WeyerhaeuserCougar Text Vellum116,21
4WeyerhaeuserCougar Text Vellum116,00
5Mohawk Neon White115,70
6WeyerhaeuserCougar Smooth Text115,59
7MohawkUltrawhite Smooth Text115,36
8WeyerhaeuserCougar Smooth Text115,29
9KodakBright White115,08
10MohawkUltrawhite Eggshell Text114,97

Table 3
Ten varieties of paper with the highest whiteness
OrderManufacturerPurpose/name gradeWhite CIE
1XeroxPremium Laser170,64
2DataM-real Data Copy 164,69
3KodakBright White163,71
4EpsonBright White160,67
5StaplesMultiuse Paper Bright White159,71
6HPBright White Inkjet158,7
7WeyerhaeuserCougar Text Vellum158,21
8WeyerhaeuserCougar Text Vellum158,18
9WeyerhaeuserCougar Smooth Text158,14
10WeyerhaeuserCougar Smooth Text157,9

The brightness levels from the lowest to the highest values for 223 commercial grades of uncoated paper, selected for the study ranged from 103,48 to 116,84 by the method of measuring the brightness D65. Similarly, the range of variation of brightness CIE C is encompassed within 90,54 to 170,64 units.

EXAMPLE 2

Experiments on the introduction of sequences of chemical additives: carried out several series of experiments in an attempt to optimize the brightness and whiteness of bleached uncoated paper. The main parameters, which were thought to affect the brightness and whiteness, were:

1. the brightness of the pulp,

2. selected chemicals (bleaching, wet phase and surface),

3. optimized dosage of chemical additives and the introduction of sequences of additives to increase the brightness and whiteness of the paper.

Samples of pulp from hard and soft wood, selected on the stage bleaching D2 was a paper mill. Samples of pulp solid (HW) and soft (SW) rocks from the stage bleaching D2 was decolorized to a higher brightness values by introducing a phase oxidation by the peroxide (P) (D0-Eop-D1-D2-P). Pulp mass, obtained from the factory, were subjected to initial discoloration ClO2, extraction (including treatment with caustic soda, O2under pressure and peroxide), and the first and second bleaching ClO2. Then the mass was further decolorized by the addition of hydrogen peroxide. The brightness values and sagasti pulp (CSF) are shown in tables 4 and 5, respectively. A lot of SW-P used for the experiments on the introduction of placentas is Teleostei from 1 to 3 chemical additives. A lot of SW-D2 used for the experiments on the introduction of sequences from the 4 to the full set of chemical additives. The pH of the mass SW-P was 7,07, and the pH of the mass SW-D2 was 5,63.

Table 4
The brightness levels achieved by bleaching
Description sampleThe ISO brightness
Factory sample pulp stage D2, D0/Eop/D1/D2HW90,52
SW89,95
Bleached sample pulp stage D2, D0/Eop/D1/D2/PHW92,73
SW92,31

Table 5
Values sagasti pulp before and after grinding
Description sampleCSF before grindingCSF after grinding
D2HW550355
SW730490
PHW625330
SW730470

Used chemical additives and their number is shown below in table 6. The experiments consisted of adding chemical ingredients wet stage one by one, to monitor the impact they have on cellulose fibers. Table 7 describes the OBA, dye and PVOH used in this series of experiments.

Table 6
Chemical additives used in the experiments on the introduction of sequences additives
Experiments on introduction 1-3 additives
AdditiveDescription
OBA-DiOptiblanc
OBA-TetraOptiblanc
Dye
ASA
PL (polymer)8430
NP (silicon oxide)442
ATC5432
PCC

Cevol 24203 solution of polyvinyl alcohol :
Table 7
Description OBA, dye and PVOH used in the study
Chemical additiveName of productCompanyDate/no party
OBA (wet stage)Optiblanc NL3V Inc.1505F36T
OBA (surface)Optiblanc NF 20003V Inc.1505N240T
DyePremier Blue 2GS-MTRoyal Pigments and Chemical Inc.06/12/06
PVOHCelanese ChemicalsW0 40416639

Chemical ingredients of table 6 was added to the fiber one simulating the wet stage of production in a paper mill. Additional additives were introduced on the surface after drying handmade sheets of paper. Surface application of OBA and PVOH (table 7) was carried out on the surface of the sheets of paper in the amount of from 0.1 ml to 1 ml OBA 15 ml of a solution of PVOH with a solids content of 8.3%.

Figure 11 shows that of all chemical additives introduced, OBA provides the greatest increase in brightness and therefore the greatest affinity to the fiber, and the increase in brightness is 19 points, compared with PCC (the second largest increase), which increased only by 2 points. The dye had no effect on the brightness, and the addition of other chemical ingredients caused dimming.

On Fig shows the effect of combining the OBA with the above chemical ingredients to the wet stage on the brightness of the paper made by hand. Best brightness is achieved through combined use of OBA with PCC. This combination increases the brightness from 108 to 112 points.

The addition of a third chemical ingredient does not improve the brightness of the paper compared with the case when the added two ingredients. The brightness was on the same level as the most effective combination OBA and PCC adding to the fiber of the two chemical components. The most effective sequences of the three chemical ingredients were sequence OBA+PCC+ASA and OBA+PCC+dye. However, adding both ASA and dye to the mixture OBA+PCC has not increased brightness above 112 points, indicating that in this series of experiments to study sequences of chemical additives on the wet stage will reach the possible maximum.

Table 8 shows that some sequences of chemical additives lead to a more favorable outcome than the other, at a superficial introduction of OBA. From table 8 one can see that at the surface the introduction of the same amount of OBA sequence OBA+PCC+ASA more effectively increases the brightness (which reaches 115,9 points) compared with the sequence OBA+PCC+PL (brightness reaches only 110,75). Similarly, the sequence OBA+dye+PCC was even more effective combination, because they are produced with the use of sheets of paper had the brightness 116,53 point. The table also shows that, with the exception OBA, no chemical additives and wet phase, which could increase the brightness more than the reasonable value of 1.5 points. Described the above data show, what chemical additives wet stage and their sequences are very important to increase the brightness of paper.

Table 8
Properties handmade paper with the addition of OBA on the wet stage and surface addition of OBA
The sequence of chemical additivesWithout coatingCoated
Brightness wet stageWhite wet stageThe brightness of the wet stage and size pressWhite wet stage and size press
Supplements no88,6486,70106,61145,82
PCC91,2686,43110,63145,04
OBA108,23139,72109,94149,69
OBA+PCC 111,97143,88116,53156,63
OBA+dye+PCC112,49146,54116,96157,67
OBA+PCC+ASA112,44141,46115,9152,61
OBA+PCC+ATC110,45138,54USD 114.9150,79
OBA+PCC+NP110,3138,04112,76147,21
OBA+PCC+PL111,06137,94110,75141,91

Examination of the table 8 and Fig, can detect that the sequence of OBA+dye and OBA+dye+PCC lead to higher brightness, and the sequence OBA+PCC+PL provides the lowest brightness, indicating that the addition of PCC shall be accompanied by the addition of PL.

In another experiment, the starch in the mixture with ASA was replaced by potato starch Stalok and polymer PL8430 replaced p is limera PL2510, giving the system more cationic in nature (table 9).

Table 9
A brief summary of the charge used chemical additives
Experiments 1-3 chemical additivesExperiments with 4-complete set of chemical additives
Chemical additiveno additivesChargeno additivesCharge
OBA-DiOptiblancAnionic (1740-1750)
OBA-TetraOptiblancAnionic (1444)
DyeAnionic
ASAcationic (.3)w/ka is totalny starch
PL8430very sticky (anionic)2510cation
10
NP (silicon oxide)442Anionic (1765-1780)
ATC5432Cationic (10)
PCCAnionic (1351)

Potato starch Stalok 400 and PL2510 used in sequences of 4 chemical additives (and subsequent).

As seen on Fig and 16, the best sequence of 4 chemical additives "OBA+PCC+dye+ASA enables you to achieve the brightness of the coating and brightness level characteristic sequence 3 chemical additives OBA+dye+PCC. In other experiments failed to reach the same level of brightness or whiteness.

The best sequence of 4 chemical additives from what is shown on Fig and 16 was selected as the control and in the control mixture were added other chemical the ski ingredients for impact assessment, which have these chemical additives to improve the brightness and whiteness, provide control combination. Consideration pig and 18 can detect that the sequence "OBA+PCC+dye+ASA+PL8430" is the best 5-component sequence, which allows us to achieve higher brightness and whiteness compared with the control sequence of the 4 chemical components.

Similarly, the best sequence 5-and chemical components of the on Fig and 18, is selected as a reference, and to chemical ingredients of this sequence were added other chemical ingredients. On Fig shows a different sequence of chemical additives with high brightness and whiteness. Sequence 6 components and their dosage are listed below in table 10.

Table 10
Dosage in sequence 6-components
OBA on the wet stage lb/tDye lb/tPCC lb/tASA/Stalok lb/tPL 8430
lb/t
NP442
lb/t
A surface. OBA
lb/t
200,140021110

This series of experiments showed that the interaction between the sequence of chemical additives and addition of OBA on the wet stage, as well as the surface the introduction of OBA is very important to get the highest brightness and whiteness of paper.

EXAMPLE 3

The weight used for this series of experiments had a low source brightness. The brightness of the pulp from hardwoods was 86,16, and the brightness of the pulp from softwood was 87,42 point. White was 71,83 and 80,31, respectively. OBA added to the wet stage, represented Leucophor T-100; the ratio of hard to soft wood was 70:30; and level grinding is shown in table 11. We used the sequence of chemical additives, are given in table 10.

Table 11
Values sagasti obtained by grinding
ContentR1 neizbalc.R2R3-IP R4R5
SW640540460450350305
HW623573430330320240
70% HW628563439366329260

This series of experiments showed that adding chemical ingredients to the wet stage in the correct sequence and dosage, there is no loss of brightness due to grinding. On Fig shows the comparison of the two different sets of samples of paper made by hand. Both sets include the same number of OBA added to the wet stage and at the stage size press. In one of the sets of sheets of paper in addition to the OBA on the wet stage were injected chemical additives. Applied chemical ingredients and combinations adding are given in table 10. As OBA used Leucophor T-100, and starch, mixed the th with ASA, substituted starch Stalok 400.

Consideration pig can detect the following:

1. There is reduction in brightness due to grinding, if on a wet stage and in the sizing press add only OBA.

2. There is practically no loss of brightness due to grinding when adding the wet stage of the chemical ingredients in the order listed on Fig.

3. Is a modest increase in brightness, if the number of OBA on the wet stage increases from 0 lb/ton up to 20 pounds/ton, for the paper samples in which it was implemented internal and superficial introduction OBA (WE & SP OBA) and was not introduced chemical additives on the wet stage.

However, the application of different methods and sequences of chemical additives, there is a significant decrease in brightness, as shown Fig. On Fig demonstrated the influence on the brightness of the other methods and chemical additives on the wet stage. Samples of paper from the set shown on the left side Fig were made with chemical additives, their sequences and doses shown above in table 10. Samples of paper shown on the right side, were made of weight, which was basically downloaded PCC, i.e. the PCC was added to the chemical ingredients and OBA. The sequence of administration and dosage of additives Pref is found in table 12:

Table 12
The sequence of administration and dosage of chemical additives on the wet stage to mass, which was added to the base
OBA on the wet stage lb/tdye
lb/t
Alum
lb/t
Amylofax
3300
lb/t
PL 1610
lb/t
NP320
lb/t
BMA-0
lb/t
Surface.
OBA
lb/t
200,12100,31,251,2510

Consideration Fig reveals that although the samples of paper from the crushed mass on the right side of the figure show a significant loss of brightness due to grinding, samples, paper presented on the left side of the picture, keep the brightness at the lowest values of sagasti.

A similar trend is observed in relation to whiteness. On Fig shown that white in the case of adding the sequence Henichesk the x ingredients circled the oval on Fig (Chem WE 1)compared with white for consistency with the initial introduction of the PCC (WE Chem 2). Consideration Fig reveals that the samples of paper on the left side of the figure have significantly higher total white at any level grinding, and the difference is 5 points at 628 CSF to 12 points at 260 CSF.

In General, the above examples show:

1. Unusual maximum increase in brightness near the point of separation of the fibers adding OBA (mixed with PVOH) in the surface layer of paper. This means that the paper mill can grind the mass to lower values sagasti (or close respective point of separation of the fibers) without reducing brightness or white paper.

2. Found several sequences the introduction of chemical additives (shown in Fig) and dosages (table 10), which increases the brightness and whiteness of the paper to the highest industry standards using fewer OBA compared with current practice paper mills.

3. The combination of adding OBA with some sequences of chemical additives and surface introduction OBA, mixed with starch or PVOH, instead of the loss of brightness in the grinding (which is convincingly confirmed in the literature) allows you to save the brightness even at very nescasary sagasti.

4. Similarly, white is not only preserved in the samples of paper received in a specified sequence, the introduction of chemical additives, but is higher than in the samples of paper, which introduced the main PCC.

EXAMPLE 4

Carried out experiments to assess the impact surface of the introduction of OBA in the sizing press for brightness and whiteness of paper.

On Fig shows the influence of OBA on the brightness D65. Samples of the paper were received from pulp containing softwood 100%, selected at the stage P with brightness 92,31 and pH 7,07. Upon receipt of sample introduced no chemical additives on the wet stage. As the surface OBA used Optiblanc 3V, which was introduced in varying amounts in the sizing press. OBA was mixed with PVOH solution containing 8.3% of solids. The above figure shows the effect of dosage OBA on the brightness of the paper. Dosage OBA and PVOH in milliliters given in table I and in pounds of solution per tonne in Fig 23.

Table I
Dosage OBA and PVOH
No. of experimentDosage OBA and PVOHThe number of OBA (ml) in 15 ml of PVOH
0Control of the capacity experiment 0
110.1 ml of OBA in 240 ml of PVOH0,00625
100.1 ml of OBA in 120 ml of PVOHof 0.0125
90.1 ml of OBA in 60 ml of PVOH0,025
80.1 ml of OBA in 30 ml of PVOH0,05
70.1 ml of OBA in 15 ml of PVOH0,1
60.25 ml of OBA in 15 ml of PVOH0,25
10.5 ml of OBA in 15 ml of PVOH0,5
21.0 ml OBA in 15 ml of PVOH1
31.5 ml OBA in 15 ml of PVOH1,5
42.0 ml OBA in 15 ml of PVOH2
52.5 ml OBA in 15 ml of PVOH2,5

On Fig shows the effect of different types of OBA on the brightness of the surface of the copy paper. 1 ml OBA was mixed with 15 ml PVOH. paper had brightness D65/10, 85 and white, equal to 89. The graph shows that the Brightener Tinopal allowed to get slightly better brightness and whiteness than other OBA products.

Table II shows the ion charges and the types of products OBA. The solids content of all OBA is in the range of 40-60%.

Table II
OBA, ionic charges and types
NameIon batteryType OBA
Blankophor UW liquid-50Hexa
OptiBlanc XLN-57Hexa
Leucophor T4-58Tetra
Tinopal ABP-A-85Tetra
Blancophor P150% liquid-97Tetra
Leucophor T100-107Tetra
Leucophor CE-132Tetra/media
Tinopal PT-1490Tetra
Blankophor DS-224Di
Tinopal HW-156Di
OptiBlanc NL-245Di

Tinopal ABP-A is tetrasulfonated optical whitening agent, and the same applies to Tinopal PT. Tetrasulfonated OBA can be used as the wet stage, and the stage size press. Tinopal PT was investigated in combination with non-ionic PVOH Celvol 09-325 with different percent solids content. The percentage of solids in PVOH, apparently, affects the brightness of the surface of the treated paper D65/10. In this series of experiments used PVOH Celvol 09-325 and 24-203 with different percent solids content and OBA Tinopal PT in different levels of dosage. Used offset paper with brightness 102. Observed incompatibility Tinopal PT (Tetra) with PVOH 09-325 with 9% solids. Therefore, the experiments continued with Celvol 24-203 with a higher solids content (12%). On Fig shows that if the percentage solids content increases from 3% to 6%, the brightness of the paper increases.

On Fig shows the results when using PVOH Celvol 24-203 with a solids content of 12%. The graph shows that the application of the specified PVOH, higher brightness can be achieved at higher dosage OBA, but at a low dose (0.25 ml), the brightness of the paper was better when using PVOH 09-325. The brightness was comparable with the content of OBA 0.5 ml for both species PVOH 09-324 and 24-203.

Fig and 28 show that Tinopal affect the brightness and whiteness of the paper, depending on the percentage of solids in PVOH Celvol 24-203 and dosage OBA. On Fig it is shown that with increase in the content of OBA, the brightness decreases at a 6% solids content in PVOH and increases with 12% solids content. On Fig it is shown that with increase in the number OBA white paper is reduced from 6% and 12% PVOH.

According pig and 28 to achieve the best brightness and whiteness in the application of Tinopal the best conditions are low dosage OBA (0.25 ml in 20 ml of PVOH) and the use of PVOH Celvol 24-203 with a solids content of 6%.

Because there could be some compatibility issues PVOH and OBA Tinopal and because of the narrow operating window of the solids content in PVOH and dosage OBA, additionally investigated the following three best agents described Fig (optical whitening agents Optiblank, Blankophor and Leucophor).

Pulp mass of hard and soft wood (60:40), selected from three different stages of the of belevalia (D1, D2 and P), with a brightness of 83.9, 86,6 and 89,46 respectively, used to obtain samples of paper. Then the samples were covered with a mixture of OBA and PVOH. The results shown Fig show that Optiblanc was more effective than Blankophor, from the point of view of brightness and whiteness.

OBA Leucophor CE with a solids content of 50% was mixed with PVOH Celvol 310 with a solids content of 9.9%. On Fig and 31 shows the effects of the ratio of Leucophor CE and PVOH 310 on the brightness and whiteness of paper.

In accordance with the results shown Fig and 31, to obtain the best brightness and whiteness of the paper should apply a mixture of PVOH and OBA in the ratio of 10 ml of PVOH to 0.25 ml OBA. Coating weight, consisting of PVOH:OBA is in the range from 4 to 6 g/sqm

Evaluated the influence of the pH of the pulp in the brightness and whiteness. On Fig shown that in the case of Leucophor and Optiblank Di, pH 7,1 leads to better brightness. For other OBA no significant influence of pH on the brightness. Similarly, Fig shows that Optiblanc Di provides the best white at a pH of 7.1.

On Fig shows the effect of superficial introduction OBA Leucophor CE and PVOH (Celvol 310 or 325) for brightness. This graph shows the results for the brightness of the images of the paper, which were made manually 1) with chemical additives wet stage and OBA, but surface without the introduction of OBA (without cover); 2) with the use of the chemical is such additives and OBA on the wet stage and superficial introduction of OBA and PVOH and 3) samples for comparison, manufactured without the use of chemical additives and OBA on the wet stage, and surface introduction of OBA and PVOH.

Samples of the paper were made by hand with a ratio of HW to SW 70:30 and at three levels of grinding pulp (470, 324 and 250 CSF). The ratio of PVOH to Leucophor was 10 ml to a 0.25 ml. of the sequence of the introduction of chemical additives was similar sequence of chemical additives wet phase 1 (see table 10 above), and OBA were applied to the fiber as the first component. The surface was covered with a mixture of PVOH and Leucophor, and the coating weight was approximately 4 g/sqm On Fig shown that when the coating process is a very significant increase in brightness. Samples of paper with no additives, made for comparison, demonstrated a significant increase in brightness when the surface is covered with a mixture of PVOH/Leucophor CE. Similar results were obtained for white.

1. The method of producing paper from shredded pulp, including grinding the suspension of cellulose fibers to reduce the level of sagasti to a value in the range from 100 to 400 CSF and the interaction of these cellulose fibers with at least one optical whitening agent (OVA) based on disulfonate or tetrasulfonated stilbene by introducing OVA crushed to a suspension of fibers on the stud and wet stage of production prior to the introduction of any additional chemical additives wet stage of production and then the introduction of the filler and dye on stage wet stage of production after the introduction of OVA and before the introduction of any additional chemical additives wet stage of production.

2. The method according to claim 1, further comprising introducing the composition containing OVA, in the size press on the surface of the paper where the specified composition OVA includes at least one OVA based on disulfonate or tetrasulfonated stilbene and at least one polymeric carrier in amounts sufficient to increase the brightness and/or whiteness of the paper.

3. The method according to claim 2, where OVA added to the size press in an amount of from 0.5 to 15 pounds/ton (0.25 to 7.5 kg/t) pulp.

4. The method according to claim 3, where the specified polymeric carrier is a polyvinyl alcohol (PVOH) and a mass ratio of PVOH:OBA is in the range from 1:1 to 16:1.

5. The method according to claim 4, where the mass ratio of PVOH:OBA is in the range from 2:1 to 8:1.

6. The method according to claim 1, where the filler is a calcium carbonate PCC.

7. The method according to claim 6, where the RCC is added in an amount of from 100 to 600 lb/ton (50-300 kg/t) pulp and the dye is added in an amount of from 0.01 to 0.25 lb/ton (0,005-0,125 kg/t) pulp.

8. The method according to claim 6, further including placing a restraint system on the wet stage of production after adding the RCC and dye, where restraint system includes an anionic polymer and a microgel or at least partially aggregated Sol nano is ASTIC anionic silica.

9. The method of claim 8, where the anionic polymer is added in amounts of from 0.1 to 2.5 lb/ton (0.05 to 1.25 kg/t) pulp and Sol of silicon oxide is added in amounts from 0.1 to 2.5 lb/ton (0.05 to 1.25 kg/t) pulp.

10. The method of claim 8, further comprising adding a cationic polymer to wet the stage of production after the RCC and dye and to add a restraint system.

11. The method according to claim 10, where the cationic polymer is alkenyl succinic anhydride, mixed with the starch prior to the introduction of on-stage wet stage of production and where the mass ratio of ASA and starch is in the range from 1:1 to 1:5.

12. The method according to claim 11, where the specified suspension of cellulose fibers pulverized to reduce the level of sagasti to a value in the range from 150 to 350 CSF.

13. The method according to item 12, where the specified suspension of cellulose fibers pulverized to sagasti, which basically corresponds to the point of separation of the fibers.



 

Same patents:

FIELD: textiles, paper.

SUBSTANCE: method comprises the following steps: a) adding a known amount of one or more surface additives to a papermaking process in a known proportion with a known amount of one or more inert fluorescent markers, and the inert fluorescent markers are selected from the group consisting of fluorescein or derivatives of fluorescein and rhodamine, or derivatives of rhodamine, b) measuring the fluorescence of one or more inert fluorescent markers in the point after adding the surface additives and after the web formation, at that fluorescence is measured with a fluorometer of reflective type, c) establishing the correlation between the fluorescence value of the inert fluorescent markers on the web and the concentration of surface additives in the coating on the web and/or coating thickness on the web.

EFFECT: use of the proposed method enables paper machine to control the rate of adding at very low levels, with ability to assess quickly and regulate statically rate of adding beyond the technical specifications.

17 cl, 1 ex, 2 dwg

FIELD: chemistry.

SUBSTANCE: described is an aqueous solution of an optical brightener, containing (a) 10-50 wt % optical brightener of formula (I): where: M is hydrogen, an alkali metal atom, ammonia or an amine cation; R1 is hydrogen, C1-C4-alkyl or C2-C4-hydroxyalkyl; R2 - C1-C4-alkyl which can be substituted with -CN- or -CONH2-group or C2-C4-hydroxyalkyl; or R1 and R2 together with a nitrogen atom close a morpholine ring; (b) 0.5-9 wt % polyvinyl alcohol, having degree of hydrolysis 71-85.2% and Brookfield viscosity 3-5.4 mPa·s; and (c) water. The invention also describes use of said solution in a coating composition for paper and a method of obtaining paper coated with said coating composition.

EFFECT: disclosed aqueous solutions of optical brighteners have low viscosity, can be used directly by paper manufacturers and can be fed by a pump directly into the coating composition to provide a coating on paper with high whiteness.

10 cl, 2 tbl, 5 ex

FIELD: chemistry.

SUBSTANCE: water-soluble composition contains a) at least one water-soluble optical bleaching agent, b) a polymer obtained from an ethylenically unsaturated monomer or a monomer mixture, characterised by that at least one monomer is an acrylamide and the water-soluble polymer has average (weight-average) molecular weight between 500 and 49000, optionally c) polyethylene glycol with weight-average molecular weight between 500 and 6000, and d) water. Said composition is used to optically bleach paper.

EFFECT: high degree of bleaching while preserving rheological properties.

7 cl, 7 tbl, 70 ex

FIELD: textile, paper.

SUBSTANCE: full bleaching/extraction of craft cellulose fibres is carried out with a chorine agent. Afterwards fibres are washed and exposed to contact in solution with at least one optical bleach (OB) upstream the mixing box and the discharge box of the machine. Fibres in solution have consistency from 7 to 15%, pH of solution in process of contact of fibres with OB makes from 3.5 to 5.5, temperature of contact makes from 60 to 80°C, and time of contact is from 0.5 to 6 hours. Additional contact of OB with fibres is carried out in the device for coating application or in the gluing press. Contact may be carried out at the stage of storage, both at high density and low density of the craft-cellulose fibres, and also at the stage of refinement.

EFFECT: improved whiteness and brightness of fibres when using lower quantity of OB.

19 cl, 11 dwg, 12 tbl, 6 ex

FIELD: textile, paper.

SUBSTANCE: method concerns reducing speed of photoyellowing of paper containing mechanical pulp. The method includes coating the surface of a paper sheet during papermaking of aqueous solution containing an effective amount of one or more salts of thiocyanic acid.

EFFECT: improvement of stability to photoyellowing of paper and cost-effective way while reducing its toxicity.

16 cl, 10 tbl

FIELD: textile, paper.

SUBSTANCE: method includes formation of composition, containing water, raw starch and powder optical refining agent. Boiling of composition. Application of finished composition, at least on one surface of paper or cardboard base in coating press. Then base is dried. In another version of method composition is boiled at the temperature up to 299°F inclusive.

EFFECT: improved brightness of paper and cardboard.

7 cl, 4 dwg, 8 tbl, 1 ex

FIELD: chemistry.

SUBSTANCE: invention describes an aqueous dispersion of an optical bleaching agent which is stable during storage, does not contain dispersants and stabilisers and contains 20-40% active substance in form of one or more optical bleaching agents obtained through successive reaction of cyanuric chloride with 4,4'-diamino-2,2'- stilbene sulphonic acid, amine and a product of reacting monoethanol amine with acrylamide.

EFFECT: disclosed dispersion of optical bleaching agent does not require dispersants or other stabilising additives to prevent settling during storage and has excellent properties for bleaching paper and other cellulose materials.

8 cl, 2 tbl, 4 ex

FIELD: paper industry.

SUBSTANCE: methods refer to manufacturing of bleached cellulose material, prevention of yellowing and loss of whiteness in bleached craft-cellulose, and manufacturing of paper goods. In process of bleached cellulose material manufacturing, bleached craft-cellulose is produced and exposed to contact with sufficient amount of more or several reducing agents. Additionally bleached craft-cellulose is exposed to contact with one or several optical bleach, with one or more chelating agent. Method for prevention of yellowing and loss of whiteness of bleached craft-cellulose in storage includes addition of efficient amount of one or more reducing agent into bleached cellulose and possibly one or more chelating agent, one or more polycarboxylate or their combinations. Method for production of paper goods includes production of bleached craft-cellulose, formation of initial water suspension from it, water drainage with formation of sheet and sheet drying. Besides efficient amount of one or more reducing agent is added into bleached craft-cellulose, initial suspension or sheet. Additionally one or more chelating agent is added there, one or more optical bleach, one or more polycarboxylate, or their combination.

EFFECT: improved quality of paper goods, increased stabilisation of whiteness and increased resistance to yellowing in process of paper production and to thermal yellowing, improved colour pattern.

17 cl, 33 tbl

FIELD: textile, paper.

SUBSTANCE: procedure refers to production of wood pulp and can be implemented in pulp-and-paper industry. The procedure consists in whitening fibres of sulphate pulp with a whitening agent on base of chlorine and in washing whitened fibres of sulphate pulp. Upon washing fibres of sulphate pulp are subject to interaction with at least one optic whitener before mixing ponds. Interacting is carried out in solution at pH from 3.5 to 8.0 and temperature from 60 to 80°C during 0.5-6 hours. The invention also refers to wood pulp produced by the said procedure.

EFFECT: increased whiteness and optic brightness of paper at decreased utilisation of optic whitener.

22 cl, 11 dwg, 11 tbl, 7 ex

FIELD: chemistry.

SUBSTANCE: invention relates to concentrated aqueous solutions of hexa-sulfonated stilbene used optical brighteners. Description is given of an aqueous solution of hexa-sulfonated stilbene optical brightener which is stable during storage with over 0.214 mol/kg content thereof in the solution. The solution does not contain a soluble agent, for example urea. By removing salts formed during synthesis of the optical brightener, its concentration of up to 0.35 mol/kg can be achieved without losing stability during storage. Also described is a method of preparing an aqueous solution of the said optical brightener and its use for bleaching paper or cellulose materials.

EFFECT: high concentration solutions of the said optical brightener do not show crystallisation signs after 2 weeks at 5°C and enables formation of coating compositions with low water content, which reduces energy consumption on drying and reduces penetration of water and adhesive into the paper layer.

10 cl, 1 dwg, 1 tbl, 3 ex

FIELD: paper-and-pulp industry.

SUBSTANCE: formulation includes optic bleacher and low-viscosity water-soluble nonionic polysaccharide derivative, whose 5% aqueous solution exhibits at ambient temperature Brookfield viscosity below about 1500 cP.

EFFECT: increased brightness of coated paper.

34 cl, 9 tbl, 2 ex

FIELD: organic chemistry, paper industry.

SUBSTANCE: invention relates to compositions used for coating paper covers. Invention describes a composition for coating paper cover comprising whitening pigment comprising: (a) product of melamine formaldehyde or phenol-formaldehyde polycondensation, and (b) water-soluble fluorescent whitening agent of the formula:

wherein R1 and R2 represent independently of one another -OH, -Cl, -NH2, -O-(C1-C4)-alkyl, -O-aryl, -NH-(C1-C4)-alkyl, -N-(C1-C4-alkyl)2, -N-(C1-C4)-alkyl-(C1-C4-hydroxyalkyl)- -N-(C1-C4-hydroxyalkyl)2 or -NH-aryl, for example, anilino-, anilinemono- or disulfonic acid or aniline sulfone amide, morpholino-, -S-(C1-C4)-alkyl(aryl) or radical of amino acid, for example, aspartic acid or iminoacetic acid that is replaced with radical in amino-group; M means hydrogen, sodium, potassium, calcium, magnesium atom or ammonium, mono-, di-, tri- or tetra-(C1-C4)-alkylammonium, mono-, di- or tri-(C1-C4)-hydroxyalkylammonium, or ammonium di- or tri-substituted with a mixture of (C1-C4)-alkyl and (C1-C4)-hydroxyalkyl groups. Covers prepared on coating paper elicit high photostability and enhanced whiteness degree.

EFFECT: improved method for preparing, improved properties of covers.

7 cl, 1 tbl, 3 ex

FIELD: chemistry.

SUBSTANCE: invention concerns fluorescent bleach containing a mix of two asymmetrically substituted and one symmetrically substituted triazinylaminostilbene disulfone acid, a new symmetrically substituted derivative, method of their obtaining, and application of the mix in synthetic or natural organic material (especially paper) bleaching and in fluorescent bleaching and sun resistance boost of textile.

EFFECT: high substantivity and light resistance of the claimed fluorescent bleaches and their mixes, and better water solubility of the claimed mixes in comparison to the solubility of each individual bleach.

15 cl, 2 tbl, 12 ex

FIELD: chemistry, textiles, paper.

SUBSTANCE: present invention relates to new amphoteric bis-triazinylaminostilbene fluorescent whitening agents for fluorescent whitening of organic materials, particularly paper. Description is given of use of compounds with formula (5) for fluorescent whitening of paper.

EFFECT: compounds have high bleaching power; fluorescence is not prevented by cation-active polymers or anion-active fluorescent whitening agents contained in the paper.

2 cl, 2 tbl, 48 ex

FIELD: chemistry.

SUBSTANCE: described is a composition, containing (A) 2 to 30 wt % composition of amino alcohol - 2-amino-2-methyl-1-propanol with formula (1), and (B) 70 to 98 wt % composition of fluorescent optical bleaching agent with formula (2) , where X - is hydrogen, ion of alkali metal or ammonium, or hydroxyalkylammonium radical, derived from amino alcohol (1); R7, R8, R9 and R10 - -OR11, -NR11R12 or , where R11 and R12 - is hydrogen, alkyl, hydroxyalkyl, alkoxyalkyl, carboxyalkyl, dicarboxyalkyl, H2N-CO-alkyl or alkylthio group.

EFFECT: high solubility in water and increased stability when storing its aqueous solutions.

4 cl, 3 tbl, 3 ex

FIELD: textile fabrics, paper.

SUBSTANCE: aqueous solutions are related to toluylene optical bleaches and may be used in production of chalk overlay paper of high whiteness. Aqueous solutions contain at least one optical bleach, polyvinyl alcohol, having extent of hydrolysis over 75% and Brookfield viscosity of 2-40 mPa·s, and water. This composition may be used for paper coating. It may be applied on paper after its moulding to produce chalk overlay paper.

EFFECT: provision of stability in storage of aqueous solutions of toluylene optical bleaches and simplified method for production of chalk overlay paper.

9 cl, 3 tbl, 3 ex

FIELD: chemistry.

SUBSTANCE: invention relates to concentrated aqueous solutions of hexa-sulfonated stilbene used optical brighteners. Description is given of an aqueous solution of hexa-sulfonated stilbene optical brightener which is stable during storage with over 0.214 mol/kg content thereof in the solution. The solution does not contain a soluble agent, for example urea. By removing salts formed during synthesis of the optical brightener, its concentration of up to 0.35 mol/kg can be achieved without losing stability during storage. Also described is a method of preparing an aqueous solution of the said optical brightener and its use for bleaching paper or cellulose materials.

EFFECT: high concentration solutions of the said optical brightener do not show crystallisation signs after 2 weeks at 5°C and enables formation of coating compositions with low water content, which reduces energy consumption on drying and reduces penetration of water and adhesive into the paper layer.

10 cl, 1 dwg, 1 tbl, 3 ex

FIELD: textile, paper.

SUBSTANCE: procedure refers to production of wood pulp and can be implemented in pulp-and-paper industry. The procedure consists in whitening fibres of sulphate pulp with a whitening agent on base of chlorine and in washing whitened fibres of sulphate pulp. Upon washing fibres of sulphate pulp are subject to interaction with at least one optic whitener before mixing ponds. Interacting is carried out in solution at pH from 3.5 to 8.0 and temperature from 60 to 80°C during 0.5-6 hours. The invention also refers to wood pulp produced by the said procedure.

EFFECT: increased whiteness and optic brightness of paper at decreased utilisation of optic whitener.

22 cl, 11 dwg, 11 tbl, 7 ex

FIELD: paper industry.

SUBSTANCE: methods refer to manufacturing of bleached cellulose material, prevention of yellowing and loss of whiteness in bleached craft-cellulose, and manufacturing of paper goods. In process of bleached cellulose material manufacturing, bleached craft-cellulose is produced and exposed to contact with sufficient amount of more or several reducing agents. Additionally bleached craft-cellulose is exposed to contact with one or several optical bleach, with one or more chelating agent. Method for prevention of yellowing and loss of whiteness of bleached craft-cellulose in storage includes addition of efficient amount of one or more reducing agent into bleached cellulose and possibly one or more chelating agent, one or more polycarboxylate or their combinations. Method for production of paper goods includes production of bleached craft-cellulose, formation of initial water suspension from it, water drainage with formation of sheet and sheet drying. Besides efficient amount of one or more reducing agent is added into bleached craft-cellulose, initial suspension or sheet. Additionally one or more chelating agent is added there, one or more optical bleach, one or more polycarboxylate, or their combination.

EFFECT: improved quality of paper goods, increased stabilisation of whiteness and increased resistance to yellowing in process of paper production and to thermal yellowing, improved colour pattern.

17 cl, 33 tbl

FIELD: chemistry.

SUBSTANCE: invention describes an aqueous dispersion of an optical bleaching agent which is stable during storage, does not contain dispersants and stabilisers and contains 20-40% active substance in form of one or more optical bleaching agents obtained through successive reaction of cyanuric chloride with 4,4'-diamino-2,2'- stilbene sulphonic acid, amine and a product of reacting monoethanol amine with acrylamide.

EFFECT: disclosed dispersion of optical bleaching agent does not require dispersants or other stabilising additives to prevent settling during storage and has excellent properties for bleaching paper and other cellulose materials.

8 cl, 2 tbl, 4 ex

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