Method of bleaching of pulp (option), biodegradable helatoobrazovatel for the bleaching of pulp with hydrogen peroxide and method of removing printing ink from pulp

 

(57) Abstract:

Method and biodegradable helatoobrazovatel affect the bleaching of pulp. The pulp mass is bleached with hydrogen peroxide in the presence of an effective amount of at least one biodegradable 1-aminoalkyl-1,1-diphosphonate chelating agent of General formula I

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where R1denotes a hydrogen atom; each of R2and R3choose from a hydrogen atom, a C1-C22alkyl, C5-C6-cycloalkyl, C1-C10balkanologie radical, carboxialkilnuyu radical containing up to 10 carbon atoms, and together with the nitrogen atom they can form piperidine, pyrolidine or morpholino group; and X is selected from a hydrogen atom, alkali metal and ammonium. The connection I used as a biodegradable chelating agent for the bleaching of pulp with hydrogen peroxide. Pulp mass can be pushed a sufficient amount of chelating agent of formula I, and then peroxide conduit. Printing ink is removed from the pulp composition containing helatoobrazovatel, which is used to connect lichnogo solution. 4 C. and 6 C.p. f-crystals, 17 tab., table 4.

The present invention relates to a method of bleaching pulp with hydrogen peroxide in the presence of aminoalkylphosphonic acid, as well as the pre-treatment of pulp aminoalkylphosphonic acid before bleaching with hydrogen peroxide. The present invention relates also to the use of aminoalkylphosphonic acid in the pre-treatment of pulp, the bleaching of pulp with hydrogen peroxide and removing printing ink from the pulp.

Depending on the type of wood, method of processing and other factors after transformation into a fibrous mass coloration pulp can vary over a wide range. When receiving pulp having the desired degree of whiteness for the pulp mass many types needed bleaching. Whiteness is measured by measuring the reflectance in the blue band (457 nm), using as a standard magnesium oxide (100% white).

Due to its low cost and effectiveness in bleaching, the most widely used bleach for pulp mass is hydrogen peroxide. There are many s such methods can be found in U.S. patents 4798652 and 4732650. When studying these patents can be noted that the method of bleaching wood pulp often includes a stage pre-treatment and the stage of bleaching.

From U.S. patent 4798652 known application diethylenetriaminepentaacetic acid (DTPC) in the pre-treatment of the pulp mass before bleaching with hydrogen peroxide. Such pre-processing is usually carried out at a consistency of pulp of less than 5%, and the preferred helatoobrazouatelem is relatively strong complexing agents.

From U.S. patent 4 732 650 known application of chelating agents on the pre-processing stage before the bleaching of pulp with hydrogen peroxide. A number of typical chelating agents used at the stage of pre-processing comprises ethylenediaminetetraacetic acid (edtc), DTPC, Triethylenetetramine acid (TGC) and N-hydroxyethylenediaminetriacetate acid (GATC).

In the application for the European patent EP-A-0141355 proposes a method of bleaching pulp, in the exercise of which is provided the use of a combination of phosphonic acids with polyhydroxyalkanoate acids and FOSFA is fairly contribute (or even a negative impact) stabilization of the peroxide solution. Specifically mentioned the following aminoalkylphosphonic acid: N,N-dicarboxyethyl-1-aminoethane-1,1-diphosphonic acid, N-2-carboxyethyl-1-aminoethane-1,1-diphosphonic acid and N,N-dihydroxymethyl-1-aminoethane-1,1-diphosphonic acid. Moreover, in comparative example 2, a European patent application EP-A-0141355 referred to the application of the whitening composition containing 1.9% of hydrogen peroxide, 1.7% sodium hydroxide and 1% N,N-dicarboxyethyl-1-aminoethane-1,1-diphosphonic acid.

In the article "Chelating Agents in the Pulp and Paper Industry", Hart. J. Roger, Tappi Journal, vol 64, No. 3, SS. 43 - 44 (March 1981), the author discusses the role of chelating agents in the bleaching of the pulp mass. This article indicates that the chelating agents can be used for pre-treatment of pulp at the stage of bleaching, and as an additive to otborochnom the solution at the implementation stage bleaching to stabilize hydrogen peroxide. Add and DTPC mentioned as preferred chelates.

Another link related to this subject is the article "The Effect of DTPA on Reducing Peroxide Decomposition", Bambrick, D. R., Tappi Journal, vol 66, No. 6, SS. 96 - 100 (June 1985), which provides a detailed discussion of the role DTPC when bleaching with hydrogen peroxide of drives the Paper Canada, volume 86, No. 12, SS. 182 - 189 (1985) provides a detailed summary of the wide variety of compounds, which are used to stabilize hydrogen peroxide otborochnyh solutions and, thus, achieve a high degree of whiteness of pulp. Mentioned several different chelates, including add, DTPC and nitryltriacetic acid (NTC).

Finally, in the article "Improving Hydrogen Peroxide Bleaching of Mechanical Pulp: The Essect of Silicate Dose and Other Additives", Burton. J. T., and others, Pulp & Paper Canada, vol 86, No. 6, SS. 144 - 147 (1987), presents some additional information about the influence of different additives on the bleaching of pulp with hydrogen peroxide. Among the applied chelates specified DTPC and diethylenetriaminepentaacetate acid (DMFC), also named as (DTPMP). The ultimate goal of these additives in ambulacrum solution is to replace the silicate additives.

From the study of these last two articles it is obvious that in modern systems for the bleaching of pulp, it is desirable to reduce the content of silicates. Moreover, the chelates used in the bleaching of pulp, suffer from the disadvantage that they are almost nonbiodegradable. One of the goals of modern investigating systems for example, by reducing the amount of silicates, creating a more biodegradable bleaching additives and/or enhancing the activity obalochnogo solution in order to use less obalochnogo solution to achieve the same level of whiteness.

Another article, which emphasizes the desirability of reducing the amount of silicate used in the processing of pulp, called "Chelant Optimisation in De-Inking Formulation", Matur, I., Pulp & Paper Canada 94:10, SS. 55 - 60 (1993). This article says that when removing printing ink from the pulp using add, GADD, DTPC and DTPMP. For carrying out the process of removing printing ink as chelate choose DTPC.

A known method of removing printing ink from the pulp by treatment with hydrogen peroxide in the presence of a chelating agent diethylenetriaminepentaacetic acid. However, the use of a different number of chelating agent reduces the activity of obalochnogo solution and reduces the environmental safety of the proposed method (application DE 1951709A, class D 21 C 9/16, 1974).

Thus, the first aim of the present invention is the creation of an effective system for the bleaching of pulp, which is the number of chelating agents are used add and/or TPC together with silicates or without them.

This and other objectives and advantages of the invention are evident from the following summary of its essence and its detailed description.

The present invention relates to a method for bleaching pulp, comprising a stage of this bleaching wood pulp with hydrogen peroxide as the main bleach, characterized in that in order to improve the bleaching wood pulp specified stage bleaching is carried out in the presence of an effective amount of at least one biodegradable 1-aminoalkyl-1,1-diphosphonate chelating agent of the formula I

< / BR>
where R1denotes a hydrogen atom; each of R2and R3choose from the hydrogen atom. C1-C22alkyl, C5-C6-cycloalkyl, such a C1-C10balkanologie radical, CH2CH3OH, such carboxialkilnuyu radical containing up to 10 carbon atoms, such as COCH3and together with the nitrogen atom they can form piperidine, pyrolidine or morpholino group; and X is selected from a hydrogen atom, alkali metal and ammonium. A second object of the present invention relates to the use of the chelating agent of the formula I in which Tadeu preliminary processing of wood pulp in the presence of a chelating agent of formula I, as well as the application of chelating agent of formula I in the process of removing printing ink.

In Fig. 1 shows a graph of the estimated conditional stability constants of 4-morpholinobutyrophenone acid for the complexation of various metal ions.

In Fig. 2 presents a graph of calculated conditions of stability constants etc for complexation of metal ions.

In Fig. 3 presents a graph of calculated conditions of stability constants DTPC for complexation of metal ions.

In Fig. 4 - 17 presents graphs illustrating examples 5 through 9. Notes to them are presented in the relevant examples.

The chelating agents of the above formula I and methods for their production are known from several publications, including "Synthesis of 1-Dialkylaminoalkylidene diphosphonic Acids and Their Properties for Complex Formation", Fukuda, M. , et al., Yukagaku, vol 25, N 6, SS. 362-64 (1976); United States patents 3899496 and 3979385 and article Acidity and Complex-Formation Properties of Some (Aminomethylene Bisphosphonic Acids", gross, H. and others, Journal of General chemistry, volume 48, No. 9, SS. 1914-16 (September, 1978) (hereinafter referred to as a link "gross").

In these publications talks about several applications chelatable from fabrics during washing, application in dye baths and use as an active additives in detergent preparations. However, none of these publications do not assume the use of chelates of formula I in the process of bleaching of pulp or otborochnyh solutions for pulp or the fact that these materials are potentially biodegradable.

Furthermore, the stability constants of the complexes of some compounds of formula I are known from the work of gross. Using these constants the resistance, you can calculate the complexing ability of chelating agents. However, in this respect, the stability constants are not the best indicator, since complex formation is strongly dependent upon the pH of the system. Thus, a better basis for comparison is the conditional stability constant of which is a constant resistance, adjusted for variations in pH, as explained in Akzo Technical Leaflet 217.

If we refer to Fig. 1 to 3, it can be noted that the conditional stability constants for 4-morpholinomethyl-1,1-diphosphonic acid, the compounds of the above formula I, is significantly less than comparable constants for add and DTPC. From ethobromide, than or EDTA, or TPC. Therefore, based on these data it can be expected that 4-morpholinomethyl-1,1-diphosphonic acid in the processes of bleaching of pulp could work noticeably worse.

However, the authors of the present invention unexpectedly found that compounds in accordance with the present invention in the process of bleaching of pulp are at least as good as add or DTPC, thus stimulating the important improvements to the bleaching of pulp due biodegradable replacement known chelates, which is more friendly to the environment. It is known that EDTA and DTPC do not show virtually no Biodegradability.

The term "biodegradable" as used in the description of this patent application, means that a significant percentage of the material decomposes during the 28-day period during the test in semi-continuous activated sludge (PNAI-test) and during the test in a closed vial. Further details on the experimental methods used to determine the Biodegradability can be found in accompanying the description of the examples.

Tipichnyi and the stage of bleaching. At the stage of pre-treatment to reduce the content of impurities in the pulp mass, in particular the concentration of metal ions in the pulp mass in front of the stage bleaching. In accordance with the purposes of the present invention for pre-treatment of pulp can be used the compounds of formula I.

If based on conditional stability constants, then one would expect that such compounds could be ineffective in the pre-treatment of pulp. However, the authors of the present invention found that the compounds of formula I represent a viable alternative to chelation add and DTPC commonly used for pre-treatment of pulp, and have the additional advantage of Biodegradability. This is an important advantage, because the pulp and paper industry became notorious intensive waste producer who invests a huge amount of investment in waste treatment.

On a typical pre-processing of a large amount of pulp is washed with water, which contains a compound of the formula I, optionally in Ia to the compound of formula I can significantly reduce the content in the pulp mass metal ions. Such processing in accordance with the present invention is applicable to both chemical (unbleached sulfate and sulfite) pulp and wood mass, in particular SGW, PGW, TMM and CTMP.

More specifically, pre-processing can be performed with the use of 0.1 - 2.0 wt.% chelate of formula I in the period from just 5 minutes before, if desirable, the whole night. In the course of carrying out the preferred process for pre-processing divert from 5 minutes to one hour at a temperature of 40 - 90oC and pH 5 to 9. Typically, the consistency of the pulp in the pre-treatment is 1 to 5%, preferably 1 to 3%. In addition, at the stage of preliminary processing, you can apply the same optional additives that mentioned for the stage of bleaching, described below.

The object of the present invention is also a stage in the bleaching of pulp. The proposed method is applicable for the bleaching of chemical pulp and wood mass, and return the pulp mass. Thus, in particular, these include wood pulp SGW, PGW, TMM and CTMP, and obtained by chemical unbleached sulphate and sulphite pulp. In a preferred embodiment, the proposed method at a temperature of 40 95oC, more preferably 50 to 75oC. Typical pulp mass is characterized by dry weight of the material is 5 to 40% by weight of cellulose pulp before bleaching it is subjected to pre-treatment. The duration of the bleaching, as a rule, is 10 to 120 minutes, more preferably 40 to 90 minutes. Bleaching is usually carried out at a pH value of 9 to 12, and more preferred pH is 10 to 12.

In the implementation of the proposed method as bleach, hydrogen peroxide is used in an amount of 0.1 to 3.0 wt.% the total weight of pulp. In it add one or more biodegradable compounds of formula I in an amount of 0.01 - 2.0 wt% the total weight of pulp. The optimum amount used of the compounds of formula I to a certain extent depends on the content of heavy metals in bleach the pulp mass. The higher the metal content, the more you want to add chelating agent of formula I.

Besides bleach and chelating agent in the bleaching process can be used with other standard additives. For example, in addition to helatoobrazovatel you can use 0 - 3 wt.% conventional silicate additive to the total weight of the Zell is% of the total weight of pulp magnesium sulfate. Silicate and maniculatus components typically add in solutions as a buffer in order to maintain a relatively constant pH in the implementation of all stages of bleaching.

Other additives that can be applied in the implementation of the method of the present invention, in addition to helatoobrazovateli formula I, include products such as citric acid, DTPC, DTPMP, etc, gluconate and lignosulfonates, which can also have a certain chelating action. In this embodiment, together with optional additives chelates of formula I is used instead of known chelating agents with the aim to make the process of bleaching of pulp more friendly to the environment. They are optional components that you can apply or not to apply when implementing the proposed method. If such components are used, they are usually added in quantities of about 0.01 to 2.0 wt% the total weight of pulp.

From Kirk-Othmer Encyclopedia of Chemucal Technology, volume 19, S. 419 (third edition, 1982), it is known that wood pulp generally take the initial whiteness of 50 - 65% (LR white). It is also known that the increase of the degree of whiteness on every not too much.

Despite the fact that the conditional stability constants of the proposed chelating agents suggests that they could be worse technically used bleach for pulp DTPC, tests showed that the proposed chelating agents will increase the degree of whiteness of the same order as DTPC. This result is completely unexpected. Moreover, the proposed chelating agents have the added value of having an unexpected advantage, which is to show them a significant degree of Biodegradability.

Preferred chelating agents of formula I for use in implementing the method of the present invention are 4-morpholinomethyl-1,1-diphosphonic acid (MDC), dimethylaminomethylphenol acid (GMLDFK), 1-aminomethylphosphonate acid (AMDC) and 1-aminoethylphosphonic acid (AEDC). The most preferred chelating agents are the compounds of formula I, which Express the highest degree of Biodegradability. These include the compounds of formula I, in which R1denotes a hydrogen atom.

In another embodiment, a subject of the present invention is the use of seediest the same as described above, in the way that the bleaching of pulp.

Another object of the present invention is the use of chelates of formula I when removing printing ink from recyclable products from the pulp. Remove printing ink is usually done with the use of hydrogen peroxide, so the chelates can also be used to remove ink from paper. Usually downloadable recovered paper includes Newspapers, magazines and the like.

The operation of removing printing ink is carried out with the use of hydrogen peroxide in an alkaline medium in the usual way except that such removal of printing ink used chelates of formula I. typically, you should use from 0.1 to 2.0 wt.% chelate. It is obvious that the scope of this invention covers also the possibility of using mixtures of two or more chelates. Moreover, if necessary or desirable, you can use these optional removal of printing ink additives, as silicates.

The essence of the present invention is further illustrated with the following examples, which are not agencymanagement in a closed vial.

Weekly on a clearing facility for wastewater treatment WWTP Niewgraaf in Divine (the Netherlands) was selected secondary activated sludge and primary attorney waste water and kept at -20oC as long as she was not required to test. These samples were used for testing in a closed bottle, held in vials 250-300 ml for determination of biological oxygen demand (BOD), with glass stoppers, and for PAI-tests, which were carried out in 150-ml PNA devices.

The basic aqueous solution was prepared using 1.0 g/l MDC and buffer, including 155 g/l K2HPO4and 85 g/l NaH2PO4H2O. the Aqueous nutrient medium for testing in a closed vial was prepared from water, 8.5 mg/l KH2PO4, a 21.75 mg/l K2HPO4, 33.3 mg/l Na2HPO42H2O, 22,5 mg/l of Mg2SO47H2O, 27,5 mg/l CaCl2and 0.25 mg/l FeCl36H2O. to avoid nitrification from the culture medium was removed ammonium chloride.

Test closed bottle conducted in accordance with the Instructions in the OECD for testing of chemicals, section 2: the Decomposition and accumulation of N 302 A, the Characteristic Biodegradability, modified PAI-the barb. Modified PAI-test on Biodegradability and water quality ISO/TC/SC 5 - evaluation of the aerobic Biodegradability of organic compounds in the aquatic environment. Method with semi-continuous activated sludge (PNAI-test, 1991). This test is conducted with diffused light at 20 - 25oC (ISO - international organization for standardization (approx. recently.

Used 3 bottles containing only inoculum, and 3 vials containing the test substance and inoculum. Concentrations of test compounds and sodium acetate vial were respectively 2.0 and 6,7 mg/l Inoculum was diluted in closed vials up to 2 mg/l with deionized water. Each prepared solution was distributed in the appropriate group for BOD bottles so that all the bottles were filled to the top, without air bubbles. Using an oxygen electrode vials zero time immediately analyzed for dissolved oxygen, and the remaining bottles were closed and incubated at 21oC in the dark. The oxygen content was determined on the 7th, 14th, 21st and 28th days.

Made one change to the standard test in a closed bottle, namely to measure the content of citlali, measured during the reduction of oxygen content in the bottle using the same special funnel, which was exactly fitted to the bottles for BOD. Further in the bottle for BOD inserted oxygen electrode for measuring the concentration of oxygen in this funnel was collected Wednesday, scattered electrode. After the extraction electrode of the collected medium was poured from the funnel back into the vial with the subsequent removal of the funnel and re-closure of the vial.

Theoretical oxygen demand (TLC) was calculated using the molecular weight MDC. Biochemical oxygen demand (BOD) was calculated by dividing the amount actually spent on the oxygen concentration of the test substance in a closed vial. Percentage biodegradation represents the amount of correlation between BOD and TLC. The results obtained are given in table. 1 (PL. 1-4, see the end of the description).

Example 2. PAI-test Biodegradability 4-morpholinomethyl-1,1-diphosphonic acid (MDC).

During PNAI-test used the same materials as in experiment example 1. The basic aqueous solution was prepared using 1.0 g/l MDC and supertuesday with the same instructions, as indicated in example 1. Testing was carried out in diffuse light at 20 - 25oC.

Each PNA device was filled with 150 ml of activated sludge and began aeration. After 23 aeration was stopped and the sludge was allowed to settle for 45 minutes. Before defending the walls of the devices was purified in order to avoid the accumulation of solid material above the liquid level using a separate brush for each device, to prevent cross contamination. The tube was opened and removed 100 ml of the upper layer liquid. After that, the sludge that remained in each PNA device, was added to 99 ml of original attorney waste water and 1 ml of concentrated phosphate buffer and once again began aeration. In these devices daily was added initially attorney wastewater.

0-day individually otstoinyi the sludge was mixed and in each of PNA devices were added to 50 ml of the resulting composite sludge. In the control device was added 94 ml initially ustanova silt, 5 ml of deionized water and 1 ml of concentrated phosphate buffer and 94 ml initially ustanova silt, 5 ml of basic solution MDC and 1 ml of concentrated phosphate buffer was added in each test log and removal was repeated for 6 times a week.

The course of this test was slightly deviated from the standard PNA procedures that the operations of filling and deleting held 6 times a week, not daily, to maintain a constant pH in PNA devices 6 times a week was added 1 ml of concentrated phosphate buffer, and samples of the removed material was filtered using membrane Schleicher and Sulla (cellulose nitrate) with a pore size of 8 μm.

Acidification of the filtered samples and their introduction into the machine of Dormann DC-190 NPOC content was determined not removed by the purification of organic carbon (NOO). The pH value of the upper layer liquid was determined using the microcomputer pH meter Consort P207, and dissolved oxygen were determined by electrochemical using an oxygen electrode (WTW Trioxmatic EO 200) and the measuring instrument (WTW OXI 530). The temperature was measured using a test device (for example, IBT, Rotterdam). The weight of the dry material (BC) of the inoculum was determined by filtering 100 ml of activated sludge through a pre-weighted filter, Schleicher and Sulla, drying filter for 1.5 h at 104oC and weighing the filter after cooling.

Remove the percentage number in the test PNAI-ol is(Ct- Cc)]/Ct,

where Ctdenotes the contents of the test compounds in terms of quantity not removed by the purification of organic carbon added to amsterdamu DRS at the beginning of the period of aeration;

Ct- the content is not removed by the purification of organic carbon in the upper layer of the test fluid after a period of aeration;

Cc- the content is not removed by the purification of organic carbon that is defined in the upper layer of the control fluid.

The results are given in table. 2.

Example 3. Thermo-mechanical wood pulp (TMP), which was characterized by 20% consistency pulp, the initial degree of whiteness 57,7% and the metal content of 1.9 mmol/kg (iron, copper, manganese, zinc), bleached at 60oC for 120 minutes using 10 and 30 kg/t100hydrogen peroxide (control experiment) and combined with equimolar amounts of 0.97 kg TPC-H5/t100(technically accessible whitening additive) or 0.72 kg MDC/t100(additive in accordance with the invention) in the presence of 30 kg/t100silicate and 1 kg/t100magnesium sulfate. The initial pH value obalochnogo solution, measured at 25ooC and the pH value of 6.2.

Example 4. Dimethylaminomethylphenol acid (GMLDFK) and 1-aminoethylphosphonic acid (AEDC) was synthesized by known methods and tested to stabilize hydrogen peroxide.

A. Measurement of concentrations of hydrogen peroxide 0-1%.

Using the solvent of the device for diluting 96 ál 15 ml were collected 96-Microlitre a sample of hydrogen peroxide solution. This solution was placed in a chemical beaker with a stirrer together with a coloring reagent, which was obtained by dilution of 173 g of sulfuric acid and 45 ml of 15% (weight per volume) solution of disulfate titanium 500-ml volume by adding demineralized water, which formed the main solution, and then 58,5 ml of this basic solution was further diluted to 1 l with demineralized water. Received 15 ml yellow coloured mixture. Then this mixture was removed through the cell, and for determining the content of hydrogen peroxide was measured by optical density.

B. Test the stabilization of hydrogen peroxide.

Fourteen plastic bottles were filled with 5.0 ml of the solution with the metal bottle was filled with water. All these bottles, but one was added 5.0 ml of a solution of complexing agents containing 0.5 wt.% GMLDFK or AADC in demineralized water and 10.0 ml of 0.1 M solution of n-phenolsulfonate sodium. The total weight of the solution by adding demineralized water was brought to 30, Then add as needed either sodium hydroxide or hydrochloric acid the pH value was brought to 9.5. Next, the total weight of the aqueous solution by adding demineralized water was brought to 45, In such solutions was added 5.0 ml of a 10% aqueous solution of hydrogen peroxide.

In the prepared solutions containing 2 parts per million of Cu(II), 4 parts per million Fe(III), 5 ppm Mn(II), 0.05% complexing agents, 0.02 M n-phenolsulfonate sodium and 1 wt.% the hydrogen peroxide.

The vials were placed in a heating bath, and was subjected to shaking at 50oC (120 rpm). Every half an hour fast, a sample was taken from the numbered backup bottle. Using the above method in such samples was determined by the content of hydrogen peroxide. The results are given in table. 4.

This example shows the effectiveness of GMLDFK and AEDC for stabilizing hydrogen peroxide. Stabilization of hydrogen peroxide is a good indicator of complexing SPO is positive purpose, but it is not intended to limit in any way the framework of the invention, which is defined to be attached to the description of claims.

Example 5.

A. The experimental part.

Used in the following tests the pulp in all cases, except as specifically stated, was a thermomechanical wood pulp from Scandinavian factory. This wood pulp was taken from the storage tank before bleaching and obezvozhivani before testing in the following circumstances:

Characteristics of raw pulp:

White - 60,2% ISO

Metals - Ca: 590 ppm Cu 3 parts/million - Fe 2 parts/million - Mg 75 ppm - Mn 34 parts per million)

Wood pulp was subjected to pre-treatment (Q-phase) various chelating agents in the following conditions:

DTPC

Consistency wood pulp - 5%

Temperature - 50oC

Time - 30 min

Consumption TPC - 2 kg/t pulp

MDK

Consistency wood pulp - 5%

Temperature - 50 and 90oC

Time - 30 and 60 min

Consumption MDC - 2-6 kg/t pulp

GMLDFK

Consistency wood pulp - 5%

Temperatural so, as shown below:

Consistency wood pulp - 15%

Temperature - 60oC

Time - 2 and 4 h for MDC as a substitute for liquid glass

The consumption of peroxide - 10-40 kg/t pulp

The total consumption of alkali optimized for each portion of hydrogen peroxide.

B. MDC as complexing agents (Q-phase).

MDC felt as complexing agents at a preliminary processing stage of thermomechanical pulp. After the processing of wood pulp was obezvozhivani and washed demonizirovannyj water, and then again obezvozhivani, and then analyzed for metal content. The benchmark was the material pretreated DTPC.

In Fig. 4 and 5 show the content of manganese and magnesium in wood mass at the stage of pre-treatment at different pH values. MDC worked effectively at pH values near to 8.5. These results show that MDC effectively reduces the manganese content in the wood mass. Manganese has an unwanted effect on the peroxide at the stage of bleaching. However, it also reduces the magnesium content. Magnesium exerts a favorable effect on stages of bleaching, in particular for bleaching Kraft a is 0 mg/kg This is enough to achieve a positive responsiveness to the stage of bleaching. Low content of metals at pH values between 2 and 3 due to the acidic effect. Experiments with pre-treatment for 30 and 60 minutes show that 30 minutes is sufficient to achieve low manganese content in the wood lot.

century stage bleaching (P-stage).

After processing MDC wood pulp bleached 40 kg./ton pulp. In Fig.6 shows degree of whiteness after the implementation of the P-stage using different quantities MDC and 2 kg DTPC on the Q-phase. In the implementation of P-stage applied peroxide, liquid glass and alkali (Eka-standard). A similar degree of whiteness was given 2 kg DTPC and 6 kg MDC. However MMDC more sensitive to changes in alkalinity, and unable to regulate the content of manganese as well as DTPC.

, Adding magnesium to the stage of bleaching.

When TCF bleaching of Kraft pulp at the stage of bleaching is often necessary to add additional amounts of magnesium. Test with additional amount of magnesium for this pulp after pre-processing using MMTK/TPC showed no egen white may be due to the addition of liquid glass at the stage of bleaching. In this case, the molten glass does, apparently, the same function as the magnesium in respect of Kraft pulp.

Example 6. MDC as a substitute of liquid glass.

To conduct these tests used the pulp mass, which is pre-processed DTPC. The samples were bleached 40 kg./ton of pulp, optimized alkalinity. For comparison with the bleaching used 40 kg of liquid glass/t pulp. During the test liquid glass was gradually replaced MMDC thus, as shown in Fig. 7. The results show that the liquid glass provides the highest degree of whiteness. It is possible that the high content of MDC causes the hydrogen peroxide in the resistant state, which thus causes a low degree of whiteness. The impression that in these samples the residual amount of hydrogen peroxide is very large.

Conducted additional testing with MDC as a substitute for liquid glass, this time its flow rate was, respectively, 2 to 6 kg/t of pulp. Previous tests have shown that when using MDC on stage bleaching more than the duration of the bleaching, the higher the degree of whiteness. Therefore, when using liquid glass duration of bleaching in accordance with the standard procedure was 2 o'clock Fig. 8 shows that the consumption MDC 4 kg/t pulp gives the same degree of whiteness, and 40 kg of liquid glass/t pulp. Also did tests on pulp weight, pre-treated DTPC and TPC as a substitute of liquid glass. The results show that TPC does not give a higher degree of whiteness than MDC or liquid glass.

Example 7. Another helatoobrazovatel, GMLDFK also felt as complexing agents at the stage of pre-treatment (Q-phase) and substitute liquid glass on stage bleaching (P-stage). The tests were carried out with a flow rate of 6 kg GMLDFK/t pulp.

A. Stage complexation (Q-phase).

After pre-treatment of the pulp mass was obezvozhivani and washed demonizirovannyj water, and then again obezvozhivani before analysis of pulp on the metal content. The content of manganese and magnesium in the pulp mass upon completion of the Q-phase is shown in Fig. 9 and 10. The optimum pH value, when the manganese content was minimal, was approximately 8. GMLDFK apparently less sensitive to changes in alkalinity than MDC.

B. Stage bleaching (P-stage).

Alloy procedure (Eka-standard), that is, using 40 kg peroxide, 40 kg of liquid glass/ton pulp and optimization of alkalinity. In Fig. 11 and 12 presents the results corresponding to the degree of brightness and residual peroxide content. As shown in the comparative experiment (2 kg TPK/t of pulp) was achieved slightly higher degree of whiteness than when using GMLDFK.

Example 8. GMLDFK as Deputy liquid glass.

Used pulp mass is processed to the Q-phase 2 kg TPK/t pulp or 6 kg GMLDFK/t pulp. Used 40 kg./ton of pulp and optimized alkalinity. In Fig. 13 and 14 presents the results corresponding to the degree of brightness and residual peroxide content. It is seen that the implementation of the sequence using a 2 kg TPK/t pulp (Q-phase) and 6 kg GMLDFK/t pulp gives the best results according to the degree of whiteness. White 0.2 units higher than in the case of TPC together with liquid glass.

Example 9. Bleaching peroxide and MDC.

During testing for the bleaching used a mixed office waste paper with the Scandinavian factory. Conducted two tests with the bleaching with the alkalinity, as shown in Fig. 15 and 16. The optimal consumption of alkali in both tests were almost the same, but adding MDC whiteness increased by approximately 2% ISO (see Fig. 17). Adding MDC residual peroxide content increased. Obviously, the peroxide stabilized MDC, which led to more selective bleaching and reduction of peroxide decomposition.

1. Method of bleaching pulp, comprising a stage of this bleaching pulp with hydrogen peroxide as the main bleach, characterized in that the specified stage bleaching is carried out in the presence of an effective amount of at least one biodegradable 1-aminoalkyl-1,1-diphosphonate chelating agent of the formula I

< / BR>
where R1denotes a hydrogen atom, the values of each of R2and R3choose from a hydrogen atom, a C1- C22alkyl, C5- C6-cycloalkyl, C1- C10balkanologie radical, carboxialkilnuyu radical containing up to 10 carbon atoms, and together with the nitrogen atom they can form piperidine, pyrolidine or morpholino group, and the value X is chosen from a hydrogen atom, an alkali metal and s is databreaches from the total amount of pulp.

3. The method according to any of paragraphs.1 and 2, characterized in that the use of 0.01 - 2.0 wt. % of additional additives selected from citric acid, diethylenetriaminopentaacetic acid, ethylenediaminotetraacetic acid, Triethylenetetramine acid, gluconate and lignosulfate with chelat forming action, from the total amount of pulp.

4. The method according to any of paragraphs.1 to 3, characterized in that the said stage of the bleaching is carried out with the additional presence of 0.1 to 3.0 wt.% at least one silicate and up to 0.2 wt.% magnesium sulfate to the total weight of pulp.

5. The method according to any of paragraphs.1 to 4, characterized in that the said stage of the bleaching is carried out at a temperature of 40 - 95oWith, within a period of 10 to 120 min and at pH 9 to 12, and that the amount of hydrogen peroxide is 0.1 to 3.0 wt.% from the total amount of pulp.

6. The method according to any of paragraphs.1 to 5, characterized in that the said helatoobrazovatel is a 4-morpholinomethyl-1,1-diphosphonic acid.

7. Application 1-aminoalkyl-1,1-diphosphonate formula I

< / BR>
as a biodegradable chelating agent for the bleaching of the pulp mass is biodegradable chelating agent for the bleaching of mechanical pulp with hydrogen peroxide.

9. Method of bleaching pulp with hydrogen peroxide, involving pre-treatment of pulp helatoobrazouatelem with subsequent treatment with hydrogen peroxide, wherein the preliminary treatment is carried out is sufficient to reduce the content in the pulp mass of the metal ions by the amount of chelating agent of the formula I

< / BR>
where R1denotes a hydrogen atom, the values of each of R2and R3choose from a hydrogen atom, a C1- C22alkyl, C5- C6-cycloalkyl, C1- C10balkanologie radical, carboxialkilnuyu radical containing up to 10 carbon atoms, and together with the nitrogen atom they can form piperidine, pyrolidine or morpholino group, and the value X is chosen from a hydrogen atom, alkali metal and ammonium.

10. Method of removing printing ink from the pulp by means of its processing composition containing helatoobrazovatel, characterized in that as a chelating agent used is 0.1 - 2.0 wt.% from the total amount of the composition for removing ink 1-aminoalkyl-1,1-diphosphonate formula I

< / BR>
where R1means vodorodno5- C6-cycloalkyl, C1- C10balkanologie radical, carboxialkilnuyu radical containing up to 10 carbon atoms, and together with the nitrogen atom they can form piperidine, pyrolidine or morpholino group, and the value X is chosen from a hydrogen atom, alkali metal and ammonium.

Priority points:

26.10.93 on PP.1 - 8;

22.03.94 on PP.9 and 10.

 

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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

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