Method for paper sizing and sizing composition

FIELD: pulp-and-paper industry, in particular, sizing of paper with the use of aqueous composition.

SUBSTANCE: method involves producing aqueous composition of cellulose filaments and dehydrating paper web; adding aqueous composition to cellulose suspension, said aqueous composition comprising sizing substance aggregates; producing aqueous composition by mixing in any order before adding into aqueous suspension of aqueous solution containing at least one coagulant and aqueous dispersion containing sizing substance. Zeta-potential of composition is below 20 mV.

EFFECT: increased efficiency and simplified method.

26 cl, 5 tbl, 3 ex

 

The present invention relates to a method of sizing paper comprising adding to the suspension of cellulose aqueous compositions containing units comprising a sizing substance, and a composition obtained by mixing, in any order of an aqueous solution of coagulant and water dispersion containing a sizing substance, while the Zeta potential of the composition is less than 20 mV. The invention also covers the water composition for sizing.

Background of the invention

To obtain a paper suitable for printing and other industrial applications, pulp paper mills add different types of agents to improve performance properties. One type of compounds that add, is to give the paper a greater resistance to the penetration of liquids such as aqueous solutions, and they are called sizing agent. The aforementioned sizing agent often contain hydrophobic fragments, these connections are connected with pulp ruffles or a covalent bond, or only associated with the fibers. On the operational properties of the sizing substances that are usually added to the suspension with the formation of a dispersion or emulsion, a variety of factors, such as the type of pulp in suspension, such as chemical pulp, mechanical is the second slurry, fiber recycling, additives to improve performance properties, such as retention agents, and, above all, the amount of pollutants present in the suspension. Pollutants present in the suspension, which affect the retention sizing substances are themselves ionic compounds from salts, to polymers having large molecular weight. The presence of charged polymeric compounds of the type Xylenol suspension is often determined by measuring the cation load suspension. A higher value cationic load indicates a higher concentration of charged polymer compounds in suspension. Suspensions with high values of cationic load can occur from the type of pulp, such as paper, water used for dilution and the degree of recirculation of white water in paper-pulp plant. Paper and pulp mills, which is widely used recirculating white water, provides a suspension having a high cationic load. Accordingly one purpose of the present invention is to develop a method of sizing paper, which paper is formed from a suspension containing cellulosic fibers having high cationic load and/or high electrop the water content. Another objective of the present invention is to improve retention sizing agents, especially the so-called holding on the first pass. Using the composition for sizing according to the present invention can even get a paper which is glued even without the addition of sizing agents. Other objectives will become clear later in the text.

Sizing the substance, as it is a combination of a hydrophobic type, so it is usually impossible dispersing/emulsify a sizing substance in aqueous solution in the absence of compounds that provide or facilitate the formation of the dispersion. In addition, you may need other compounds to stabilize the variance. Education variance for sizing before adding a sizing agent to the suspension in principle is a prerequisite for the receipt of paper which is glued. Typically, the particle size or srednevekovoi particle size, containing a sizing substance, affects the efficiency of the sizing. In accordance with common practice the best sizing is achieved if the particles containing a sizing substance, are small as possible, preferably less than 1 μm. However, the present invention is the creation of the composition is, comprising units containing a sizing substance, which is significantly greater than the particle sizing agent in conventional dispersions. Unexpectedly found that the method and composition according to the present invention provides a receiving paper which is glued, i.e. with the number of Cobb below 30, even without the use of retaining substances. Furthermore, the method and composition significantly improves the sizing applied to suspensions of cellulose having a high cationic load and/or high conductivity.

In WO 00/34583 disclosed sizing dispersion, which is stable cationic colloidal koatservatnyh stabilizer, and koatservata contains an anionic component and a cationic component. Anionic and cationic components must be present in such a ratio at which the Zeta-potential of the dispersion is at least 20 mV, although the Zeta-potential of at least 40 mV is more preferable. The purpose koatservata is to stabilize the emulsified or dispersed sizing agent.

U.S. patent 6159339 relates to the composition for sizing paper consisting essentially of ASA/AKD and destruktivnogo liquid cationic starch.

WO 9833979 relates to aqueous dispersions containing reactive about the relative cellulose sizing substance, including low molecular weight cationic organic compound having a molecular weight less than 10000, and anionic stabilizer.

Invention

The present invention relates to a method for sizing paper and composition for sizing according to the invention. In particular, the present invention relates to a method of sizing paper comprising obtaining aqueous suspension comprising cellulosic fibres, dehydration specified water suspension with the formation of the paper web, and the method includes adding to a pulp slurry water compositions comprising the units, including a sizing substance, and a mixture in any order before the introduction of the aqueous suspension of (i) an aqueous solution comprising at least one coagulant, and (ii) water dispersion comprising a sizing substance, and Zeta-potential of the composition is less than 20 mV. In addition, the invention also relates to an aqueous composition for sizing as defined in the claims related to water compositions for sizing containing units comprising a sizing substance, when this composition was prepared by mixing in any order (i) a solution comprising at least one coagulant, and (ii) water dispersion comprising a sizing substance, and jet the potential of the composition is less than 20 mV.

According to a preferred variant implementation of the present invention the aqueous composition, comprising units containing a sizing substance, obtained by mixing in any order before introduction into the aqueous suspension of (i) an aqueous solution comprising at least one bearing the charge coagulant, and (ii) carrying charge aqueous dispersion comprising a sizing substance, and the charge coagulant opposite to the charge dispersion.

According to another preferred variant implementation of the present invention relates to a method of sizing paper comprising adding a composition containing units comprising a sizing substance to the suspension without the addition of retention agent or retention of the agents to the suspension.

The coagulant solution may be any compound or mixture of compounds, provided that the coagulant provides flocculation/agglomeration of particles sizing agent by the mixing of coagulant solution and the dispersion of a sizing agent. Preferably, the coagulant is selected from the group comprising non-ionic polymers, polyelectrolytes, surfactants, particles based on silica, inorganic-containing aluminum compounds and mixtures thereof. If carrying a charge coagulants obtained in the form of aqueous solution or water dispersion for sizing should preferably have opposite charge.

Examples of preferred non-ionic polymers are polyalkylene, also known as polyalkylene glycols, especially polyethylene oxides and phenol resin. Phenolic resins that can be selected are the polycondensation products of phenols and aldehydes, preferably formaldehyde, commonly called Resolume and nowelcome, and phenolic resins, modified natural resins such as rosin acids from, for example, rosin, wood rosin and rosin tall oil. Usually as a coagulant is a mixture of polyalkyleneglycol and phenolic resins. Predominantly non-ionic polymers are water-soluble or water-dispersible.

According to the above preferred variant, the present invention relates to a method for sizing paper and water compositions for sizing, and the aqueous composition is prepared, receiving the carrier charge aqueous dispersion or emulsion sizing agent (depending on the physical condition of a sizing agent at ambient temperature) and an aqueous solution comprising carrying charge coagulant, and carrying charge coagulant is opposite in charge dispersion, and mixing the dispersion solution with obtaining thus the water composition, comprising units containing a sizing substance having the General Zeta-potential of less than 20 mV. Under the phrase "carrying charge aqueous dispersion" in the claims also means carrying charge water emulsion, depending on the type of sizing agent present in the dispersion. If, for example, there is a sizing agent which is solid or substantially solid at ambient temperature, the dispersion is formed, however, if the sizing agent is liquid at ambient temperature, the emulsion is formed. The phrase "carrying charge dispersion" refers to the total charge of dispersing/stabilizing system dispersion. Accordingly, if the carrying charge coagulant solution is anionic (total anionic), then the dispersion comprising a sizing substance, must be cationic, on the other hand, if the carrying charge coagulant is a cationic (total cation), then the variance must be anionic.

About carrying the charge of the coagulant solution, the charge is either positive or negative, depending on the charge dispersion. In accordance with this coagulant must not contain an equal number of negative or positive charges. Thus, the carrying charge coagulant is anionic or cationic, i.e., the coagulant may be anionic or cationic total charge, and coagul the NT can only have anionic groups, fully cationic group or an anionic, and cationic groups, the latter relate to the amphoteric coagulants.

When receiving water composition, the order of mixing of the solution with the dispersion does not seem important. However, preferably the solution containing the coagulant to be added to the water dispersion. Can be used with any method of mixing the dispersion and the solution, although it is advisable to add a solution to fulfill so that the Zeta potential of the resulting aqueous composition was less than about 20 mV in the process of mixing, thereby obtaining aggregates containing a sizing substance, which has a diameter considerably greater than the diameter of conventional particle sizing agent in the dispersion. Even the best flocculation sizing agent is achieved if the Zeta-potential in the process of mixing is near the isoelectric point of the composition, for example less than about 18 mV (i.e. between -18 mV and 18 mV), more preferably less than about 15 mV (i.e. between -5 mV and +5 mV).

According to the present invention, the Zeta potential of the resulting composition after mixing should be less than about 20 mV. The term is less than approximately 20 mV covers the composition having a Zeta potential of less than 20 mV and -20 mV. The Zeta potential of the composition is preferably less than about 18 mV, more predpochtitel what about - less than about 15 mV, even more preferably less than about 10 mV or even less than 5 mV. The Zeta potential of the composition after mixing can be even as low as approximately the isoelectric point of the composition.

The charge aqueous composition, i.e. dispersing/stabilizing system is usually determined by measuring the Zeta-potential. A positive value of the Zeta potential indicates the cationic dispersion, whereas a negative Zeta potential indicates the anionic dispersion. The Zeta-potential can be measured using microelectrophoresis particles, as described in the textbook "Introduction to colloid and surface chemistry", D.Shaw, Butterworths.

Aggregates containing a sizing substance, are loosely Packed agglomerates relative sizing agent and a sizing substance uniformly distributed inside the unit. Preferably the units contain from about 1 to about 40 vol.% a sizing agent, more preferably from about 3 to about 30 vol.% and most preferably from about 5 to about 20 vol.%. While the rest of the volume of the aggregates is mostly water and small amounts of coagulant and optionally a dispersing/stabilizing agents in aqueous dispersion for sizing. According to the common practice of particle sizing agent in which Isperih, greater than or much greater than the particle sizing agent in the micron range, of the order of 1 μm, cause poor distribution of the sizing agent in paper cloth, inevitably leading to the deterioration in the sizing of paper. However, it is assumed that the units comprising the composition according to the invention, containing a sizing substance, uniformly distributed in aggregates, provide effective distribution of a sizing agent with a reasonable dosage of the composition on the fiber surface during the stage of drying.

By mixing an aqueous solution containing a coagulant and water dispersion containing a sizing substance, flocculation occurs sizing agent, forming a composition comprising aggregates of a sizing agent, preferably having srednevekovoi diameter of at least about 5 μm, more preferably at least about 10 μm, even more preferably at least about 15 microns, optionally at least about 22 microns. Top value srednevekovogo diameter of the aggregates can vary significantly depending on the process parameters, such as the type of the pulp suspension, and other chemicals for control of operational properties added to the suspensions, such as agents for the behavior of the solutions of strength in the dry state, agents to increase strength in the wet state, etc. for practical reasons, srednevekovoi diameter of the aggregates is preferably a value of less than 250 μm, preferably less than 100 μm, more preferably less than 80 μm. The preferred spacing values srednevekovogo diameter units comprise from about 10 microns to about 100 microns, preferably from about 15 μm to about 60 μm, more preferably from about 22 μm to about 50 μm.

Srednevekovoi diameter of the aggregates was measured using a Malvem Mastersizer Microplus (Malvem Instruments Ltd.) with the top cell of small volume. Under srednevekovym diameter in the claims refers to the distribution of particle sizes, presented in the form of PSDD (v.0,5) and represents the volume-weighted particle size for which 50% of particles have a value below this value.

Carrying charge coagulant is preferably selected from the group comprising polyelectrolytes, the particles on the basis of silicon dioxide, aluminium-containing inorganic compounds and mixtures thereof.

According to a preferred variant implementation of the composition carrier charge aqueous dispersion comprising a sizing substance, it is not crucial, provided that the total charge is cationic or anionic. The dispersion preferably includes the t connection, which accelerate the formation of dispersed sizing particles and stabilizes the sizing particles. Mentioned dispersing/stabilizing agents preferably are natural polymers such as polysaccharides type cellulose derivatives and starch, and synthetic polymers such as polymers of vinyl accession and condensation polymers. The particle size of a sizing agent dispersion may be in the range from about 0.1 μm to about 2 μm. In addition, the carrying charge aqueous dispersion may in addition to the above-mentioned stabilizing/dispersing agents or instead of such agents contain any of the agents related to the coagulants according to the present application. The type and amount of dispersing/stabilizing agents and/or coagulants variance chosen so that the variance becomes anionic or cationic. The charge dispersion is preferably measured by a method of microelectrophoresis particles.

Preferred carriers charge coagulants are polyelectrolytes, which can be cationic or anionic, i.e. with the total anionic or cationic charge. The polyelectrolyte included in the composition of the aqueous solution is preferably srednevekovoi molecular weight of at least about 6000, preferably at least prima is but 10000, it is usually water-dispersible or water-soluble. Usually srednevekovoi molecular weight is a value below about 10000000 and more preferably from about 100,000 to about 1000000. The polyelectrolyte may have a charge density of at least about 0.1 mEq/g Regular interval of values of the charge density is from about 0.1 to about 18 mEq/g, more preferably from about 0.1 to about 12 mEq/g, usually from about 0.5 to about 6 mEq/g of Cationic or anionic polyelectrolyte may also have charged groups of opposite charge, usually related to the amphoteric polyelectrolytes. Carrying the charge of the polyelectrolyte is preferably chosen from the group comprising polysaccharides, polymers of vinyl accession, condensation polymers, and mixtures thereof.

If cationic polyelectrolytes are present in solution, including coagulant, they must be of the same type or a mixture of different cationic polyelectrolytes. The cationic polyelectrolyte is preferably chosen from the group comprising polysaccharides, such as starches, which can be obtained, for example, potatoes, corn, preferably containing groups of the tertiary amine, Quaternary ammonium group or the reaction products of trimethylamine and epichlorohydrin, such condensation polymers, as is alepisauridae, polyamidoamine, polyethyleneamine etc., chain reaction polymers, examples of which include polymers of vinyl accession, i.e. polyacrylamide, copolymers of acrylate and acrylamide, polymers of diallyldimethylammoniumchloride called poly-DADMAC.

Preferred anionic coagulants selected from the group including polyelectrolytes, the particles based on silica and mixtures thereof.

If anionic polyelectrolytes are part of coagulant solution, the anionic polyelectrolytes may consist of a mixture of anionic polyelectrolytes or only a specific anionic polyelectrolyte. Anionic polyelectrolyte is preferably chosen from the group comprising polysaccharides, condensation polymers and chain reaction polymers, preferably from the group comprising polysaccharides, polysulfate, polysulfone and mixtures thereof. Preferred anionic polyelectrolytes are carbauxilirovanny cellulose, such as carboxymethyl cellulose; modified phosphate polysaccharides, for example starch, polyacrylates such as polyacrylamides; polysulfate, examples of which include polyvinyl sulphate, polietilensorbit, etc.; polysulphonate type polyphenylsulfone, lignin sulfonate, sulfonate condensed naphthalene.

Coagulants from the group of particles on the basis of dioxi is and silicon, i.e. particles based on SiO2,include colloidal silicon dioxide such as, colloidal borosilicate modified with aluminium silicon dioxide or an aluminum silicate, microgels of polyaluminosilicate and mixtures thereof. Particles on the basis of silicon dioxide is often called a colloidal solution of silicon dioxide. Particles may be colloidal, i.e. in the range of the size of colloidal particles, or preferably amorphous or essentially amorphous. Sols on the basis of silicon dioxide can also be modified and can contain other elements, such as aluminum and/or boron, which may be present in the aqueous phase and/or particles on the basis of silicon dioxide. Preferred particles based on silica of this type include modified colloidal aluminium silicon dioxide and aluminum silicate. Can also be used mixtures of such preferred particles on the basis of silicon dioxide. Anionic particles based on silicon dioxide are preferably structured anionic colloidal solution of silicon dioxide, and particles of silicon dioxide may have a specific surface area in the range from 30 to 1200 m2/g and S-value is usually in the range from 8 to 45 percent, preferably from 10 to 35 percent and more preferably from 10 to 30 percent. Specific surface area can be measured by titration of NaOH Izv the local way for example, as described by Sears in Analytical Chemistry 2B (1956); 12, 1981-1983 and in U.S. patent No. 5176891, and given S-value can be measured and calculated as described Iler, R.K. & Dalton, R.L. in J.Phys. Chem. 60(1956), 955-957. We can say that the S-value is a measure of the degree of aggregation or formation of microgel, and lower S-values indicate a higher content of microgel and can be considered as a measure of the amount of SiO2in percent by weight in the dispersed phase. Particles of silicon dioxide structured sols usually are surface modified aluminum to the extent of from 2 to 25 percent, preferably from 3 to 20 percent. Under the degree of surface modification of aluminium means the number of atoms of aluminum, which can replace the silicon atoms on the surface of the particles. The degree of modification is given in percent and is calculated on the basis of 8 silanol groups at nm2. This is described by Iler, R.K. in the Journal of Colloidal and Interface Science, 55(1976): 1, 25-34. S-the value given for the sols, largely correlates with the distribution of particle sizes.

Cationic particles on the basis of silicon dioxide, i.e. sols cationic particles on the basis of silicon dioxide, which are usually positively charged particles with a dense core of silicon dioxide coated/modified one or a variety of polyvalent metallogaloidnye and connections, includes metal oxides, metal hydroxides and hydrated oxides of metals. Preferably, the particles of silicon dioxide covered by one polyvalent metallogaloidnym connection, preferably three -, and tetravalent metallogaloidnym connection, such as connection of aluminum, chromium, gallium, titanium and zirconium, and particularly preferred is a compound of aluminum. Preferred anionic counterions include halides such as chloride, acetate or nitrate. Preferably positively charged colloidal particles of silicon dioxide are inorganic particles of silicon dioxide, which can be surface modified, preferably a compound of aluminum, such as various oxides and hydroxides of aluminum. Positively charged particles of silica may have a particle size less than about 500 nm, and typically more than 1.0 nm. The specific surface of particles of silicon dioxide may be in the range of from about 5 to about 1800 m2/g, preferably in the range of from about 30 to about 1200 m2/g and more preferably from 50 to 1000 m2/, Positively charged colloidal particles of silicon dioxide, modified aluminum, preferably have a mass ratio of Al2O3for SiO2in the range of from 1:20 to 4:1, more preferred is equipment - from 1:10 to 2:1 and most preferably in the range from 1:5 to 1:1.

Preferred inorganic aluminium-containing compounds which act as coagulants, are salts, including aluminum, such as aluminum sulfate, commonly called alum, aluminium chloride and various inorganic semi-aluminum connection type chloride polyaluminum, compounds of chloride of polyalanine containing sulphate, and compounds sulfate hydrosilicate of polyalanine. Connection polyaluminum based on aluminum, the hydroxy groups and the anions, they are the main and in aqueous solutions they are polynuclear complexes.

Examples of compounds of polyaluminum can have a General formula

Aln(OH)mX3n-m,

where X is a negative ion such as chlorine or acetate, and both n and m are positive integers such that 3n-mgreater than 0. Preferably X=Cl-and such compounds of polyaluminum known as the chlorides of polyalanine (GROIN). Chlorides of polyaluminum can also contain anions of sulfuric acid, phosphoric acid, polyphosphoric acid, chromic acid, dichromasy acid, silicic acid, citric acid, carboxylic acids or sulphonic acids. Examples of sulfates of polyaluminum are compounds of the formula [Al(OH)x(SO4 y(H2O)z]nwhere x has a value from 1.5 to 2.0, y has a value from 0.5 to 0.75, x+2y=3 and z=1.5 to 4, preferably from 1.5 to 3.0. Commercially available inorganic aluminium-containing compounds are, for example, Ekoflock produced and delivered by the company Eka Chemicals AB, Sachtokfar®manufactured by Sachtleben Chimie in Germany, solfataras WAC, manufactured by Atochem, France, high primary connection chloride of polyaluminum Locron, manufactured by Hoechst AG in Germany, sulfate poly(hydroxylamine) Omniklir produced OmniKem, USA, Niaproof, which represents hydroxyacetate aluminum produced Niacet in the United States, and Alzofix, which is based on the chloride and dicyandiamide of polyaluminum manufactured by SKW Trostberg, Germany.

If inorganic aluminium-containing compounds present in the water dispersion of a sizing agent, the sizing substance can be flocculated by changing the pH of the dispersion by adding a suitable acid or base. Traditionally, a sizing dispersion containing aluminium-containing compounds are acidic, i.e. dispersions have a pH in the range of 2-5. Respectively, raising the pH of the acidic dispersion preferably to neutral values (pH 8 to 10), it is possible to induce flocculation of a sizing agent.

Type sizing agent included in the aqueous dispersion, is definitely the shining factor thus, there may be used any known specialists sizing substance, such as directionspanel relatively cellulose substances, including rosin, such as protected and/or esterified rosin, waxes, fatty acids and derivatives of rosin acids, such as fatty amides and fatty esters, such as complex truefire glycerol and natural fatty acids, and reactive relative to the cellulose agents. However, the preferred sizing agent included in the aqueous dispersion, are to the cellulose reactive sizing agent. Preferred reactive with respect to the cellulose sizing agent selected from the group including dimers hydrophobic ketene, multimer dimer of ketene, acid anhydrides, organic isocyanates, carbamylcholine and mixtures thereof, more preferably the ketene dimer. Preferred ketene dimers have the General formula (I)below, where R1and R2represent a saturated or unsaturated hydrocarbon group, typically saturated hydrocarbons, hydrocarbon groups preferably have from 8 to 36 carbon atoms, are typically linear or branched alkyl groups containing from 12 to 20 carbon atoms, such as hexadecyl the traveler and octadecyl group. The ketene dimer can be liquid at ambient temperature, i.e. at 25°C, preferably at 20°C. Typically, the anhydrides of acids may be characterized by the General formula (I)below, where R3and R4may be the same or different and represent saturated or unsaturated hydrocarbon group, preferably containing from 8 to 30 carbon atoms, or R3and R4together with the fragment-C-O-C - can form a 5 - or 6-membered ring, optionally additionally substituted hydrocarbon groups containing up to 30 carbon atoms. Examples of anhydrides of acids that are used commercially include anhydrides, alkyl - and alkenylamine acid and especially anhydride isooctylphenol acid.

Preferred ketene dimers, acid anhydrides, organic isocyanates include compounds disclosed in U.S. patent No. 4522686, which is included in the present description as a reference. Examples of preferred carbamoylation include that disclosed in U.S. patent No. 3887427, which is also included in the present description as a reference.

Another preferred implementation of the present invention relates to a method of sizing paper comprising receiving water suspension comprising cellulose in the window, dehydration specified aqueous suspension to obtain paper web, and the method includes adding to a pulp slurry of aqueous compositions containing units comprising a sizing substance, and this composition was prepared by mixing in any order before adding to the aqueous suspension (i) an aqueous solution containing at least an anionic coagulant, and (ii) a cationic aqueous dispersion containing a sizing substance, and Zeta-potential of the composition is less than 20 mV.

Thus, the preferred aqueous composition for sizing according to the present invention is an aqueous composition for sizing containing units comprising a sizing substance, and a composition obtained by mixing in any order (i) an aqueous solution comprising at least an anionic coagulant, and (ii) a cationic aqueous dispersion comprising a sizing substance, and Zeta-potential of the composition is less than 20 mV.

Preferably anionic coagulant is an anionic polysaccharide, i.e. anionic derivative of cellulose, such as carboxymethylcellulose, having a charge density is typically from about 0.5 to about 18 mEq/g, more preferably from about 1.0 to 6 mEq/g of the Cationic aqueous dispersion preferably includes nationalpolitical, preferably the cationic condensation polymers, examples of which include polymers of the type epichlohydrin (for example, polyamine), polymers amiguinho type and polymers etieleniminne type. Depending on the use of monomers of the cationic polymers can be branched or unbranched. Preferably the cationic polyelectrolyte has a charge density in the range of from about 0.5 to about 20 mEq/g, usually from about 1.0 to about 12 mEq/g, and preferably from about 1.0 to about 6 mech. Preferred cationic condensation polymers include polyamides, similar to those formed from aliphatic amines and aliphatic dicarboxylic acids, for example, by the condensation of adipic acid, ethylene diamine or diamine and Diethylenetriamine; polyamidoamine epichlorhydrine resin, polyethylenimine, polymers vinylamine type. Usually formed larger particles containing a sizing agent (the best flocculation), if the charge density cationic polymers present in the dispersion, and/or the charge density of the coagulant is increased.

The aqueous composition comprising units containing a sizing substance, preparing, receiving the carrier charge aqueous dispersion comprising a sizing substance, and an aqueous solution comprising a coagulant, and carried the mix. The water dispersion of get known methods of dispersion/emulsification. The dispersion preferably is formed by melting a sizing agent and the dispersing liquid sizing agent in an aqueous solution containing a dispersing agent, using high-pressure equipment. If you use a sizing agent, which are solid at ambient temperature, before emulsification them melt.

As for the aqueous solution containing a coagulant, you are simply mixing water-dispersible or water-soluble substances, if necessary with suitable dispersing agents in aqueous solution. The amount of coagulant contained in the solution is not critical. Preferably the amount of coagulant contained in the solution is from about 0.01 to about 15 wt.%.

Aqueous dispersion which is mixed with a water solution containing a coagulant, typically has a content of the sizing agent from about 0.1 to about 50 wt.%, preferably from about 1.0 to 20 wt.%.

Sizing substance is preferably contained in the composition according to all variants of realization of the invention in an amount of from about 0.01 to about 20 wt.% calculated on the total weight of the composition, preferably from p is IMEMO 0.07 to about 5 wt.%, more preferably from about 0.1 to about 2 wt.%, while the coagulant is usually contained in the composition in a quantity lying in the range of values from about 0.1 to about 10 wt.% per the sizing agent, preferably from 0.1 to 5 wt.%.

The method according to the invention is used to produce paper. The term "paper"used in this description, of course includes not only paper and its production, but also other sheet or leaf-shaped products, such as, for example, heavy and light cardboard, and their production. The method can be used in the production of paper from different types of suspensions of cellulose fibers, and such suspension should preferably contain at least 25 wt.% and preferably at least 50 wt.% the above-mentioned fibers, based on dry substance. The suspension can be formed by fibers from chemical pulp, such as sulphate, sulphite and organosilica cellulose, wood pulp, such as thermo-mechanical pulp, chemical-mechanical pulp, wood pulp from wood pulp and groundwood pulp from coniferous and deciduous wood, and also can be obtained from fiber recycling, not washed from printing inks cellulose, and mixtures thereof. The invention is particularly well suited for use is increased in the production of paper from a suspension on the basis of mass, including fiber recycling and washed from printing ink weight, and the content of cellulose fibers such an origin can be up to 100%, preferably from 20 to 100%.

It is established that the method according to the invention can be used for sizing of paper from a suspension containing cellulosic fibres, and optional fiber having a high cationic demand and/or high conductivity. Adequate sizing of the paper is achieved if the cationic demand of the suspension is more than 1000 mkaku/l, and even if the cationic demand of suspension exceeds 2000 mkaku/l, preferably from about 3,000 mkaku/l, preferably more than about 4000 mkaku/L. in Addition, the conductivity of the mass must be at least 0,20 MS/cm, preferably at least a 3.5 MSM/see Very good results sizing was observed when the level of electrical conductivity over a 5.0 MS/cm, and even above 7.5 MSM/see Cationic load can be measured by titrating polyelectrolytes (Mütek PG 02). The conductivity can be measured by such standard equipment as, for example, WTW LF 539 shipped Christian Berner. The values mentioned above, is preferably determined by measuring the cation load or the electrical conductivity of the pulp suspension supplied or present in the pressure professional manufacturer of the e paper machine, or, on the contrary, measurement of cationic load or the electrical conductivity of the white water formed by the dehydration of the suspension. High levels of conductivity mean high content of salts (electrolytes), when various salts can give one-, two - and polyvalent cations of the type of alkali metals such as Na+and K+, alkaline earth metals such as Ca2+and Mg2+the ions of aluminum, such as Al3+, Al(OH)2+and ions of polyalanine, and one-, two - and polyvalent anions such as halogen, for example Cl-, sulfates, for example SO42-and HSO4-, carbonates, such as CO32-and the HCO3-, silicates and lower organic acid, whereas high cationic load means a high amount of anionic polyelectrolytes such as Xilai. The invention is particularly suitable for use in the manufacture of paper from the masses, having a high content of salts of two - and polyvalent cations, and usually the cations is at least 200 machine hours, preferably at least 300 M.Ch. and more preferably at least 400 M.Ch. Source of salts can be cellulose fibers and fillers used to obtain the mass, in particular, combined factories, when a concentrated aqueous suspension in the window with the pulp mill is usually mixed with water with the formation of the diluted suspension, suitable for the production of paper at a paper mill. Sources of salts can also be different additives introduced into the mass of fresh water input to the process, or may be added intentionally, etc. in Addition, the salt content is usually higher in areas where white water is extensively circulated, which can lead to significant accumulation of salts in the water circulating in the process.

The present invention further includes processes for the production of paper, which is widely circulated white water (recycle), i.e. with a high degree of closure of the white water, for example, when used from 0 to 30 tons of fresh water per ton of dry received the paper, usually less than 20, preferably less than 15 and more preferably less than 10 and even more preferably 5 tons of fresh water per tonne of paper. Recirculation of white water generated in the process, preferably includes a mixture of white water and cellulose fibers and/or optional fillers with getting to be sizing suspension; preferably it includes a mixture of white water suspension containing cellulosic fibres, and optional fillers, before applying the slurry on the forming grid for sizing.

The invention is additionally illustrated by the following examples, which, however, are not about what raycity amount of his claim. % refers to % by weight unless otherwise indicated.

All of the examples srednevekovoi particle diameter, comprising a sizing substance, measured using a device Malvem Mastersizer Microplus (Malven Instruments Ltd.) with the top cell of small volume. The relative refractive index of particle to particle dimer of ketene (AKD) amounted to 1.15, the imaginary refractive index was 0.1, and the refractive index for dispersing medium (water) was 1.33. The results were analysed by polydisperse model 50HD. Srednevekovoi particle diameter, i.e. the distribution of particle size, represented as PSD D (v.0,5), and reflects the volume weighted particle size for which 50% of particles are below the specified value. The number of particles, comprising a sizing agent (flakes), calculated using the Coulter Counter Multisizer II, Coulter International Corporation, USA.

Example 1

Preflowering composition for sizing according to the invention is produced by mixing 100 ml of a solution of potassium sulfate (0.3 g/l of potassium sulfate) with (a) an aqueous solution containing 0,092 mg/l carboxymethylcellulose (CMC)having a charge density of 3.6 mEq/g and srednevekovoi molecular weight of 250000, and (b) cationic dispersion for sizing containing standard dimer of ketene (AKD), cationic polyamine and naphthalene sulfonate. The CMC solution is added to the dispersion in the amount obespechivaya the neutralization of the charge composition. The charge of the composition is measured using PCD (Detector charge particle - Particle Charge Detector, Mütek PC 02). The obtained composition for sizing contained 0.025% dimer of ketene. Average diameter of particles of a composition comprising a sizing substance dimer of ketene, amounted to about 30 microns. The units of the composition contained about 10% vol. a sizing agent. Vol.% calculated as follows: weighted-average particle diameter is 30 μm, which gives the volume of particles of 1.4 E-14 m3. The weight of the unit is determined by dividing the total number of sizing agent in the specific volume by the total number of particles in unit volume. The number of particles determined with the use of a Colter counter (Coulter Counter). The mass of one particle are calculated according to 1.45 E-12 kg, which gives the density of the unit (the mass of particles/volume of particles) to about 100 kg/m3. The density used for the AKD is 960 kg/m3. Vol.% the quotient of the density unit density AKD, i.e. about 10%vol.

For comparison prepared nelokalizovannaya cationic dispersion for sizing based on dimer of ketene using the same dispersion for sizing, which was prevlocation, but without mixing the dispersion for sizing or CMC solution or with a solution of potassium sulfate. Weighted-average particle diameter of the dimer of ketene is left of 0.77 μm.

The effectiveness of the sizing preflowering composition and nelokalizovannaya dispersion appreciate the addition of the composition and dispersion to the paper pulp in amounts that are presented in tables 1 and 2, containing sulphate pulp of hardwood (PL) and softwood (CP) in the weight ratio 60:40, with pH 8.0, conductivity 480 µs/cm, concentration 0,511% (W/V) dry fiber and 0.3 g/l of potassium sulfate. The suspensions did not add any retaining agents. Formed paper sheets having a weight of 70 g/m2using formulates Finnish Sheet former.

Table 1

Evaluation of the sizing properties preflowering compositions for sizing
Sheet noAdded preprocurement AKD, (kg/ton of dry fiber)SOW-60
10,2109
20,2590
30,359
40,3551
50,433
60,528
70,824

Sheet noAdded nelokalizovannaya AKD, (kg/ton of dry fiber)SHOW60
10,4105
20,885
31,232
41,627
52,025

Example 2

The same variance for sizing based on dimer of ketene, which was used in example 1 is subjected to flocculation by the addition of a solution of anionic Zola on the basis of modified aluminium silicon dioxide (NP590). Preflowering composition is prepared according to the method described in example 1. Use a similar suspension of paper as in example 1.

Table 3

Evaluation of the sizing dispersion for sizing, preflowering NP590
Sheet noAdded preprocurement AKD, (kg/ton of dry fiber)SHOW60
10,490
20,578
30,654
40,746
50,832

Example 3

Cationic dispersion for sizing containing 8.9% of standard sizing agent based on dimer of ketene and 1.1% of polyamidoamine and having a charge density of 640 mkaku/g, localroot adding 0,120 g CMC/g all of the variance in Britt Dynamic Drainage Jar (BDDJ), Paper Research Materials Inc. The resulting composition is stirred at a speed of 1000 rpm for 3 minutes. The same cationic dispersion containing polyamidoamine, but not preflowering, used for comparative purposes. Srednevekovoi particle diameter, containing a sizing substance, amounted to 20 μm (preprocurement composition) and 0.8 μm (nelokalizovannaya variance).

The effectiveness of the sizing preflowering composition and cationic dispersion is evaluated by measuring the Cobb60(SCAN-P 12-64) laboratory sheets made on a Formette Dynamique (Centre Technique du Papler, France). The sheets formed by adding preflowering composition and nelokalizovannaya respectively to the mass of the quantities listed in tables 4 and 5. Paper pulp contained TCF (totally chlorine-free) birch pulp and has a concentration of 0.15% (V/V), pH 7.5 to 7.7 and the electrical conductivity in the range of 1000-1200 µs/see

The table is a 4

Evaluation of sizing preflowering composition
Sheet noAdded preprocurement AKD, (kg/ton of dry fiber)SHOW60
11,626
24,825

Table 5

Evaluation of sizing nelokalizovannaya composition
Sheet noAdded nelokalizovannaya AKD, (kg/ton of dry fiber)SHOW60
11,6193
24,8119

1. The method of sizing paper comprising obtaining aqueous suspension comprising cellulosic fibres, dehydration specified water suspension with the formation of the paper web, and the method includes adding to a pulp slurry water compositions comprising the units, including a sizing substance, when this composition was prepared by mixing in any order before adding to the aqueous suspension (i) an aqueous solution comprising at least one coagulant, and (ii) water dispersion comprising a sizing substance, and Zeta-potential of the composition is less than 20 mV.

2. The method according to claim 1, in which the PR Zeta potential of the composition is less than 18 mV.

3. The method according to claim 2, in which the Zeta potential of the composition is less than 15 mV.

4. The method according to any one of claims 1 to 3, in which the average diameter of the aggregates is at least about 5 microns.

5. The method according to claim 4, in which the average diameter of the aggregates is from about 22 to 250 microns.

6. The method according to any one of claims 1 to 3, in which a sizing substance is relatively reactive cellulose sizing agent.

7. The method according to claim 6, in which reactive with respect to the cellulose sizing substance selected from the group comprising a ketene dimer, multimer dimer of ketene, acid anhydrides, organic isocyanates, carbamoylated and mixtures thereof.

8. The method according to claim 6, in which reactive with respect to the cellulose sizing substance selected from the group comprising a ketene dimer and the anhydrides of the acids.

9. The method according to any one of claims 1 to 3, in which the coagulant is a carrying charge coagulant having a charge opposite to the charge of the aqueous dispersion.

10. The method according to claim 9, in which the bearing charge coagulant is anionic, and the carrying charge aqueous dispersion is cationic.

11. The method according to claim 10, in which the anionic coagulant selected from the group comprising polyelectrolytes, the particles based on silica and mixtures thereof.

12. The method according to claim 10, in which the bearing for the venom coagulant is an anionic polyelectrolyte.

13. The method according to item 12, in which the anionic polyelectrolyte selected from the group comprising polysaccharides, polysulfate, polysulfone and mixtures thereof.

14. The method according to item 12, in which the anionic polyelectrolyte is srednevekovoi molecular weight of at least about 6000.

15. The method according to claim 9, in which the bearing charge the coagulant is a cationic and charge carrier aqueous dispersion is anionic.

16. Aqueous composition for sizing containing units comprising a sizing substance, and a composition obtained by mixing, in any order,

(i) a solution containing at least one coagulant, and

(ii) aqueous dispersion comprising a sizing substance, while the Zeta potential of the composition is less than 20 mV.

17. Aqueous composition for sizing according to clause 16, in which the Zeta potential of the composition is less than 18 mV.

18. Aqueous composition for sizing according to clause 16, in which the Zeta potential of the composition is less than 15 mV.

19. Aqueous composition for sizing according to clause 16, in which the average diameter of the aggregates is at least about 5 microns.

20. Aqueous composition for sizing according to clause 16, in which the average diameter of the aggregates is from about 22 to 250 microns.

21. Aqueous composition for sizing according to clause 16, in which a sizing substance presented yet a reactive relative to the cellulose sizing agent.

22. Aqueous composition for sizing according to item 21, which is reactive with respect to the cellulose sizing substance selected from the group comprising a ketene dimer, multimer dimer of ketene, acid anhydrides, organic isocyanates, carbamoylated and mixtures thereof.

23. Aqueous composition for sizing according to item 21, which is reactive with respect to the cellulose sizing substance selected from the group comprising a ketene dimer and the anhydrides of the acids.

24. Aqueous composition for sizing according to clause 16, in which the coagulant is a carrying charge coagulant having a charge opposite to the charge of the aqueous dispersion.

25. Aqueous composition for sizing according to paragraph 24, which carries the charge of the coagulant is anionic, and the carrying charge aqueous dispersion is cationic.

26. Aqueous composition for sizing according to paragraph 24, which carries the charge of the coagulant is a cationic and charge carrier aqueous dispersion is anionic.



 

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