JP3453624B2 - Papermaking method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a papermaking method in a papermaking system in which even if a sulfate band is used, its effect cannot be sufficiently exerted. [0002] In recent years, the papermaking industry has become increasingly dependent on waste paper due to raw material circumstances, while on the other hand, there has been a tendency to treat wastewater in a closed manner due to social demands for environmental conservation. Under such circumstances, the paper strength of paper tends to decrease, and various papermaking additives are indispensable in order to suppress the decrease in paper strength and maintain the quality of paper. At present, acrylamide-based polymers (PAM) are the mainstream as paper strength agents, and various improvements have been made in terms of composition and polymer structure. In terms of composition, it is classified into an anionic type, a cationic type, and an amphoteric type. Methods for introducing ionic groups into PAM include a copolymerization type obtained by copolymerizing various ionic monomers with acrylamide, and a modification type obtained by decomposing PAM by Hoffman decomposition or Mannich modification. Among them, varieties having an ionic composition suitable for each papermaking condition such as pH and band usage are selected and applied. [0003] However, in the recently increasing neutral papermaking system, the amount of bands used is at a low level, and under high pH conditions, the bands lose ionicity and become inactive. The fixing effect cannot be sufficiently exhibited, and the effect of the added chemical is generally lower than that of the acidic system. In addition, due to the deterioration of water quality due to an increase in salts of water used for paper production, anion trash, etc., the band effect cannot be sufficiently exerted even in an acidic pH region.
Therefore, an object of the present invention is to provide a papermaking method capable of improving the band effect in a papermaking system in which the effect cannot be sufficiently exerted even when a band is used. SUMMARY OF THE INVENTION [0004] The present invention provides a method for adding a water-soluble aluminum compound to a previously diluted acrylamide-based polymer solution without separately adding it to the acrylamide-based polymer so as to perform ionic crosslinking. The water-soluble aluminum compound ionically crosslinks with the acrylamide-based polymer to improve its fixability without losing its ionicity, and at the same time, with the structural change of the acrylamide-based polymer, improve the yield and improve the paper strength. It has been found that the pulp slurry exhibits an enhancing effect and is completed. At least one selected from the group consisting of amphoteric, cationic and anionic polyacrylamide-based polymers is added to the pulp slurry, and the pulp slurry is added to the pulp slurry. Diluted amphoteric, cationic and anionic polyacrylic A step of previously mixing an aqueous solution obtained by diluting a water-soluble aluminum compound with at least one diluent selected from the group consisting of amide-based polymers, and a step of adding the mixed diluent to a pulp slurry. To provide a papermaking method. [0005] In particular, an aluminum compound is added to a solution obtained by diluting the acrylamide-based polymer to 0.1 to 8% by weight, preferably to about 0.2 to 3% by weight, and the aluminum compound is added to the polymer in an amount of 0.1 to 200% in terms of aluminum ion. Mol%, more preferably 10 to 100 mol%. The acrylamides used for obtaining the copolymer type polyacrylamide polymer used in the present invention include, for example, acrylamide, methacrylamide, N-methylacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide, Water-soluble N-substituted lower alkyl acrylamides such as N-isopropyl acrylamide and diacetone acrylamide, and the like can be used alone or in combination of two or more. In addition, as a monomer copolymerized with acrylamides, a nonionic monomer can be used in addition to an ionic monomer having an anion and / or a cation. Examples of the anionic monomer include monocarboxylic acids such as acrylic acid, methacrylic acid and crotonic acid, dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, citraconic acid and muconic acid, and salts thereof. In addition, organic sulfonic acids such as vinyl sulfonic acid, styrene sulfonic acid, and 2-acrylamido-2-methylpropane sulfonic acid, and salts thereof can be used. However, carboxylic acids having strong interaction with aluminum compounds can be used. Use in combination with a monomer is preferred. Examples of the cationic monomer include tertiary amine monomers such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, diethylaminopropyl (meth) acrylamide, allylamine and diallylamine. Or salts of inorganic or organic acids such as hydrochloric acid, sulfuric acid, acetic acid, or tertiary amine monomers with methyl chloride, benzyl chloride, dimethyl sulfate,
Examples thereof include ammonium salt monomers quaternized by reaction with epichlorohydrin and the like. These ionic monomers can be used alone or in combination of two or more. The nonionic monomer can be used to such an extent that the water solubility of the polymer is not impaired, and examples thereof include (meth) acrylonitrile, styrene and vinyl acetate. It is also possible to use a small amount of a crosslinking agent, for example, methylenebis (meth) acrylamide,
Bis (meth) acrylamides such as ethylene bis (meth) acrylamide, bis (meth) acrylamide-methylol ethylene urea condensate, bis (meth) acrylamide-methylol urea, and ethylene glycol di (meth)
Di (meth) acrylates such as acrylate and diethylene glycol di (meth) acrylate; divinyl esters such as divinyl adipate and divinyl sebacate;
Trivinyl monomer-based crosslinking agents such as N, N-diallylacrylamide, 1,2,3-triacroylhexahydro-S-triazine, triallyl isocyanurate and the like can be mentioned. The amount of these crosslinking agents added is 0.005
〜1 mol%, preferably 0.01-0.2 mol% is optimal. The polymer can be polymerized by various known methods. For example, the above various monomers and water are charged into a predetermined reaction vessel, and potassium persulfate,
Add a normal radical polymerization initiator such as a redox polymerization initiator or an azo polymerization initiator such as a redox polymerization initiator in which a persulfate such as ammonium persulfate or a combination thereof with a reducing agent such as ammonium hydrogen sulfite, and add isopropyl as needed. The desired polymer can be obtained by appropriately using a chain transfer agent such as alcohol or allyl alcohol and heating the mixture under stirring. A 15% aqueous solution of the polyacrylamide-based polymer obtained in this manner is
Is 100 to 40,000 cps as measured by a Brookfield viscometer in
It is preferably from 00 to 20,000 cps. The aluminum compound that can be used in the present invention has a different content ratio as long as it is water-soluble, but any of them can be used. Examples of the aluminum compound include polyaluminum chloride, alumina sol, polyaluminum sulfate, polyaluminum silicate, aluminum chloride, and aluminum sulfate. These aluminum compounds can be used alone or in combination of two or more. Particularly, a sulfate band (aluminum sulfate) often used in a paper making process is preferable in terms of handling and cost. The mixing of the aluminum compound with the polymer is desirably diluted and mixed to such an extent that the mixing does not increase the viscosity of the polymer and impair the workability. The dilution concentration of the polymer varies depending on the composition and cannot be unconditionally determined, but is within 0.1 to 8%, preferably about 0.2 to 3%. The timing of mixing is preferably from immediately before addition to 10 hours before addition, more preferably within 1 hour before addition. However, in actual use, it is most preferable to use a method in which an aluminum compound is mixed with a chemical diluted immediately before addition and used. The addition amount of the aluminum compound can be mixed up to a high concentration range as compared with the case of mixing with the polymer stock solution, and is 0.1 mol% to 200 mol%.
More preferably, it is 10 mol% to 100 mol%. According to the present invention, according to the present invention, any acrylamide-based polymer thickens or gels when an aluminum compound is mixed with the undiluted stock solution. The crosslinking seems to be progressing. It is presumed that this cross-linked structure caused the expansion of the polymer and a change in the molecular weight to improve the structural factors. Furthermore, the mixed solution is acidic in terms of pH, and many aluminum ions coexist with the polymer as active cationic species. Therefore, ionic action works effectively with the polymer without being greatly affected by papermaking conditions. It is thought that the yield to pulp is increased, and the effect on paper strength and drainage is excellent. Since the diluted aluminum compound is added to a solution obtained by diluting the acrylamide-based polymer to a certain extent, an inappropriate thickening or gelling does not occur as an additive, and there is no restriction on the composition of the polymer. If so, any of amphoteric, cationic and anionic types can be used. Further, since the amount of the aluminum compound added can be changed in a wide range according to the conditions, it can be adapted to a wide range of papermaking conditions. Examples of the present invention will be described below, but the present invention is by no means limited to these examples. Various polyacrylamide-based copolymers used as paper strength agents in Examples and Comparative Examples were prepared as follows. In the following, “%” means “% by weight” unless otherwise specified. Production Example of Polyacrylamide Polymer-
1 In a 1 l four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas inlet tube, 530 g of water, 334.2 g of 40% acrylamide and 10.8% of 80% acrylic acid were placed.
g and isopropyl alcohol 3.0 g, p
Adjust with an acid or alkali so that H is around 3.5. Nitrogen gas was passed through the reaction system to remove oxygen. Next, the temperature was raised to 55 ° C. while stirring, and 15 g of a 5% ammonium persulfate solution and 10 g of 5% sodium sulfite were added as polymerization initiators to initiate polymerization. Then 8
It was kept at 5 ° C. for 2 hours to terminate the polymerization. Non-volatile content 15.
This polymer having a constant of 6%, a viscosity of 10800 cps and a pH of 4.1 is abbreviated as S-1. Hereinafter, the base polymers S-2 to S-9 were prepared in the same manner as in the above Production Examples by changing the amounts of the monomers corresponding to the compositions shown in Table 1 and the amounts of the appropriate catalysts and chain transfer agents. Obtained. Production example of polyacrylamide-based polymer
2 In a 1 l four-necked flask equipped with a stirrer, thermometer, reflux condenser and nitrogen gas inlet tube, 730 g of water, 298.6 g of 40% acrylamide and 82.8 g of 60% acryloylaminobromotrimethylammonium chloride were added.
g, fumaric acid 9.2 g and isopropyl alcohol 3
g, and adjust with an acid or alkali to adjust the pH to around 3.0. Nitrogen gas was passed through the reaction system to remove oxygen. Next, the temperature was raised to 55 ° C. while stirring, and 10 g of a 5% ammonium persulfate solution and 5 g of 5% sodium sulfite were added as a polymerization initiator to initiate polymerization. Thereafter, the temperature was maintained at 85 ° C. for 2 hours to terminate the polymerization.
Non-volatile content 15.8%, viscosity 4200 cps, pH 4.2
Is abbreviated as S-10A. Water 580 was added to a 1-liter four-necked flask equipped with a stirrer, thermometer, reflux condenser and nitrogen gas inlet.
g, 312.8 g of 40% acrylamide, 12.5 g of dimethylaminopropylacrylamide, 14.4 g of 80% acrylic acid, and 3 g of isopropyl alcohol, and the mixture is adjusted with acid or alkali so that the pH becomes about 3.0. Nitrogen gas was passed through the reaction system to remove oxygen. Then, the temperature was increased to 55 ° C. while stirring, and 10 g of a 5% ammonium persulfate solution and 5%
5 g of sodium sulfite was charged to initiate polymerization. Thereafter, the temperature was maintained at 85 ° C. for 2 hours to terminate the polymerization. This polymer having a non-volatile content of 15.1%, a viscosity of 3700 cps and a constant of pH 4.3 is abbreviated as S-10B. The two types of polymers obtained (S-10A,
B) was mixed at a weight ratio of 1: 2 to obtain a nonvolatile component 1
This polymer having a constant of 5.4%, a viscosity of 6800 cps and a pH of 4.2 is abbreviated as S-10. Hereinafter, Table 1 was prepared in the same manner as in the above-mentioned production example.
The base polymers S-11 to S-12 were obtained by changing the amounts of the monomers corresponding to the compositions shown in (1) and the amounts of the appropriate catalysts and chain transfer agents. The constants of the obtained polymer are shown in Table 1. [Table 1] The abbreviations of the monomers in Table 1 are as follows. AM: acrylamide MAM: methacrylamide AA: acrylic acid IA: itaconic acid FA: fumaric acid MA: maleic acid DM: dimethylaminoethyl methacrylate DM Q: methyl chloride quaternized DM-BQ: benzyl chloride quaternized DM DMAPAA: dimethylaminopropyl acrylamide DMAPAA Q: Methyl quaternary chloride of DMAPAA DMAPAA-BQ: benzyl quaternary chloride of DAMPAA Example 1 WP was beaten with a Niagara beater to obtain Canadian Standard Freeness (C .SF) 380 ml
The pulp was adjusted to a 3% slurry, and the electric conductivity was measured to be 1600 μs / cm ² . After sufficiently stirring the pulp slurry, the amount of sulfuric acid band shown in Table 2 was added. Subsequently, an aluminum compound in an amount shown in Table 2 was mixed with a 2% dilution of the polyacrylamide-based polymers S-1 to S-4 obtained above, and added to the pulp slurry. A paper having a basis weight of 100 g / m ² was prepared from the obtained pulp slurry using a square sheet machine, pressed at 5 kg / m ² for 1 minute, and dried at 105 ° C. for 3 minutes to prepare a test paper. Furthermore, at 20 ° C., 65% R.F. 2 under the condition of H
After conditioning for 4 hours, the specific burst strength was measured according to JIS P8112. Table 2 shows the results. [Table 2] * PH 4.7, Alum 3.0%, electric conductivity 160
0 μs / cm ² WP, basis weight: 100 g / cm ² Comparative Example 1 To the same pulp slurry as in the example, 3% (by weight of pulp) of a sulfuric acid band was added, followed by the polyacrylamide-based polymer S obtained above. -1 to 4. Hereinafter, hand-made paper was prepared under the same conditions as in the examples, and measurements were performed. Example 2 WP was beaten with a Niagara beater and 360 ml of Canadian Standard Freeness (CSF) was used.
The pulp was adjusted to a 3% slurry, and the electric conductivity was measured to be 1200 μs / cm ² . After sufficiently stirring the pulp slurry, the amount of sulfuric acid band shown in Table 3 was added. Subsequently, the aluminum compounds in the amounts shown in Table 3 were mixed with the 2% diluents of the polyacrylamide-based polymers S-4 to S-6 and S-10 and 11 obtained above, and added to the pulp slurry. The obtained pulp slurry is made into a paper having a basis weight of 100 g / m ² using a square sheet machine,
It was pressed at kg / m ² for 1 minute and dried at 105 ° C. for 3 minutes to prepare a test paper. In addition, 20 ° C, 65%
R. After conditioning for 24 hours under the conditions of H, JIS P 8
The specific burst strength was measured according to 112. Table 3 shows the results. [Table 3] * PH 6.0, Alum 1.5%, electric conductivity 120
0 μs / cm ² WP, basis weight: 100 g / cm ² Comparative Example 2 1.5% sulfuric acid band was added to the same pulp slurry as in the example.
(Weight to pulp) and subsequently to the polyacrylamide-based polymers S-4 to S6 and S-10 and 11 obtained above. Hereinafter, a hand paper was prepared under the same conditions as in Example 2,
The measurement was performed. Example 3 BKP was beaten with a Niagara beater, and the Canadian Standard Freeness (CSF) 400 m was used.
The pulp adjusted to 1 liter was made into a 3% slurry, mixed with 15% of light calcium carbonate (based on the weight of pulp), and measured for electrical conductivity to be 1500 μs / cm ² . After sufficiently stirring the pulp slurry, the aluminum compounds in the amounts shown in Table 4 were mixed with the 2% dilutions of the polyacrylamide-based polymers S-7 to S-9 and S-12 obtained above and added to the pulp slurry. Furthermore, after stirring, the pulp slurry concentration was diluted to 1.5%, and the retention agent was added at 200 ppm.
Was added. The obtained pulp slurry was made into paper having a basis weight of 80 g / m ² by a square sheet machine, and 5 kg /
It was pressed at m ² for 1 minute and dried at 105 ° C. for 3 minutes to prepare a test paper. Furthermore, at 20 ° C., 65% R.F. H
After conditioning for 24 hours under the conditions described in JIS P 8112
The specific burst strength was measured according to. Table 4 shows the results. *
Retention agent: NR IILH (manufactured by Hymo) * PH 8.0, Alum 0.5%, electric conductivity 1500
μs / cm ² BKP, basis weight: 80 g / cm ² , CaCO ₃ = 15 wt
%, Retention agent = 200 ppm Comparative Example 3 0.5% sulfuric acid band was added to the same pulp slurry as in Example.
Then, the polyacrylamide-based polymers S-7 to 9 and S-12 obtained above were added. Hereinafter, a hand-made paper was prepared under the same conditions as in Example 3 and the measurement was performed. The abbreviations of the aluminum compounds in Tables 2 to 4 are as follows. Alum: liquid sulfuric acid band PAC: polyaluminum chloride (LOCRON S, manufactured by Hoechst Japan) AS: alumina sol (alumina sol 100, manufactured by Nissan Chemical Co., Ltd.) PASS: aluminum polysilicate aluminum sulfate (manufactured by Nippon Light Metal Co., Ltd.)

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-55-1308 (JP, A) JP-A-5-93393 (JP, A) JP-A-7-189194 (JP, A) JP-A 53-193 14823 (JP, A) JP-A-53-90405 (JP, A) JP-A-50-35406 (JP, A) JP-A-60-9995 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) D21H 11/00-27/42

Claims (1)

(57) [Claim 1] At least one selected from the group consisting of amphoteric, cationic and anionic polyacrylamide-based polymers is added to a pulp slurry, and the pulp slurry is added to the pulp slurry. An aqueous solution obtained by diluting a water-soluble aluminum compound is added to at least one diluted solution of 0.2 to 3% by weight selected from the group consisting of diluted amphoteric, cationic and anionic polyacrylamide-based polymers. 10 to polymer in terms of aluminum ion
Adding 100 mol% and mixing;
Adding to the pulp slurry within 10 hours after mixing .