JPH08226092A - Production of paper - Google Patents

Abstract

PURPOSE: To obtain a paper good in filterability and paper force by adding the mixture dilution solution of an acrylamide polymer with a water-soluble aluminum compound to a pulp slurry and subsequently producing the paper from the diluted mixture. CONSTITUTION: This method for producing a paper comprises diluting at least one of amphoteric, cationic and anionic polyacrylamide polymers into a 0.1-8wt.% solution, preferably a 0.2-3wt.% solution, adding a water-soluble aluminum compound such as a sulfate band in an amount of 0.1-200mol% (in terms of aluminum ions) to the polymer to prepare a mixture solution, sufficiently stirring a pulp slurry, adding a prescribed amount of the sulfate band to the pulp slurry, adding the above-described mixture solution to the mixture and subsequently producing the paper from the mixture.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a papermaking method in a papermaking system in which the effect cannot be sufficiently exerted even if a sulfuric acid band is used.

[0002]

2. Description of the Related Art In recent years, in the paper manufacturing industry, reliance on used paper has increased due to the circumstances of raw materials, and on the other hand, there is a tendency to close wastewater for treatment due to social demands for environmental protection. Under such circumstances, the paper strength of paper tends to decrease, and various papermaking additives are indispensable for suppressing the decrease in paper strength and maintaining the quality of paper. At present, an acrylamide polymer (PAM) is the mainstream as a paper-strengthening agent, and various improvements have been made so far in terms of composition and polymer structure. In terms of composition, they are classified into anion type, cation type, and amphoteric type. The method of introducing an ionic group into PAM includes a copolymerization type obtained by copolymerizing various ionic monomers with acrylamide, and a modified type obtained by a Hoffmann degradation product or Mannich modified product of PAM. Among them, varieties having an ionic composition suitable for each papermaking condition such as pH and band usage amount are selected and applied.

[0003]

However, the amount of bands used in neutral papermaking systems, which has been increasing recently, is at a low level, and at high pH conditions, the bands lose their ionicity and are inactivated to have a fixing effect. It cannot be fully exhibited, and its additive chemical effect is generally lower than that of an acidic system. Further, due to deterioration of water quality due to an increase in salts, anion trash, etc. of water used for paper production, there are increasing cases where the band effect cannot be sufficiently exhibited even in an acidic pH range.
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 exhibited even if the band is used.

[0004]

According to the present invention, when a water-soluble aluminum compound is added to a pre-diluted acrylamide polymer solution without adding the water-soluble aluminum compound separately to cause ionic crosslinking, the water-soluble aluminum compound is dissolved. The aluminum compound does not lose its ionicity by ion-crosslinking with the acrylamide-based polymer, and at the same time, the fixing property is improved, and at the same time, the yield is improved due to the structural change of the acrylamide-based polymer, and the excellent paper strength is enhanced. It has been found that it exhibits its effect, and when it is completed, it is added to the pulp slurry by adding at least one selected from the group consisting of amphoteric, cationic and anionic polyacrylamide-based polymers, and then added to the pulp slurry. Amphoteric, cationic and anionic polyacrylamide-based poly A papermaking process comprising: a step of previously mixing an aqueous solution in which a water-soluble aluminum compound is diluted with at least one diluting solution selected from the group consisting of the following; and a step of adding the mixed diluting solution to a pulp slurry. It provides a method.

Particularly, a solution obtained by diluting the above acrylamide polymer to 0.1 to 8% by weight, preferably 0.2 to 3% by weight, and an aluminum compound in terms of aluminum ion, is used in an amount of 0.1 to 200 with respect to the polymer. It is good to add mol%, more preferably 10 to 100 mol%.

Examples of acrylamides used for obtaining the copolymer type polyacrylamide polymer used in the present invention include N-methyl acrylamide, N-ethyl acrylamide, N, N-dimethyl acrylamide, in addition to acrylamide and methacrylamide. Examples thereof include water-soluble N-substituted lower alkyl acrylamides such as N-isopropyl acrylamide and diacetone acrylamide, and these may be used alone or in combination of two or more. Further, as a monomer to be copolymerized with acrylamides, a nonionic monomer as well as an ionic monomer having an anion and / or a cation can be applied.

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, 2-acrylamido-2-methylpropane sulfonic acid, and salts thereof can be used, but a carboxylic acid system having a strong interaction with an aluminum compound. It is preferably used in combination with a monomer.

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. Alternatively, salts of inorganic or organic acids such as hydrochloric acid, sulfuric acid, acetic acid, etc., or tertiary amine type monomers with methyl chloride, benzyl chloride, dimethyl sulfate,
Examples thereof include ammonium salt-based monomers quaternized by a reaction with epichlorohydrin and the like. These ionic monomers may be used alone or in combination of two or more.

The nonionic monomer can be used in an amount that does not impair the water solubility of the polymer, and examples thereof include (meth) acrylonitrile, styrene and vinyl acetate.

It is also possible to use small amounts of crosslinking agents, such as 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,
Examples thereof include trivinyl monomer crosslinking agents such as N, N-diallyl acrylamide, 1,2,3-triacroylhexahydro-S-triazine and triallyl isocyanurate. The addition amount of these crosslinking agents is 0.005
The optimum amount is ˜1 mol%, preferably 0.01 to 0.2 mol%.

The polymer can be polymerized by various conventionally known methods. For example, a predetermined reaction vessel is charged with the above-mentioned various monomers and water, potassium persulfate,
A persulfate such as ammonium persulfate, or an ordinary radical polymerization initiator such as a redox polymerization initiator in which these are combined with a reducing agent such as ammonium hydrogen sulfite or an azo polymerization initiator is added, and isopropyl is added as necessary. The desired polymer can be obtained by appropriately using a chain transfer agent such as alcohol or allyl alcohol and heating with stirring. A 15% aqueous solution of the polyacrylamide polymer thus obtained has a temperature of 25 ° C.
The viscosity measured by a Brookfield viscometer is 100 to 40,000 cps, but usually 5
It is preferably from 00 to 20,000 cps.

As the aluminum compound which can be used in the present invention, any of them can be used if they are water-soluble, although there are differences in the content ratio. Examples of the aluminum compound include polyaluminum chloride, alumina sol, polyaluminum sulfate, polysulfate aluminum silicate, aluminum chloride, aluminum sulfate and the like. These aluminum compounds may be used alone or in combination of two or more. Particularly, a sulfuric acid band (aluminum sulfate) often used in the paper manufacturing process is preferable in terms of handling and cost.

The mixing of the aluminum compound with the polymer is preferably carried out by diluting the polymer to such an extent that it does not hinder workability due to the thickening of the polymer. The diluted concentration of the polymer differs depending on the composition and cannot be generally stated, but it 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, and more preferably within 1 hour before addition. However, in actual use, a method of mixing an aluminum compound with a chemical diluted immediately before addition and using it is most preferable. The addition amount of the aluminum compound is 0.1 mol% to 200 mol%, which can be mixed up to a high concentration range as compared with the case where it is mixed with the polymer stock solution.
More preferably, it is 10 to 100 mol%.

[0014]

INDUSTRIAL APPLICABILITY According to the present invention, any acrylamide polymer thickens or gels when an aluminum compound is mixed with the undiluted stock solution, so that ionic cross-linking via aluminum ion proceeds. It seems to be out. It is presumed that this crosslinked structure caused the polymer to spread and the molecular weight to change, thereby improving the structural factor. Furthermore, since the mixed solution is acidic in pH and many aluminum ions coexist as active cation species with the polymer, ionic action works effectively with the polymer without being significantly affected by papermaking conditions. It seems that the yield of pulp is increased, and that it exerts excellent effects on paper strength and drainage. Since the diluted aluminum compound is added to a solution obtained by diluting the acrylamide polymer to a certain extent, there is no inappropriate thickening or gelation as an additive, and there is no restriction on the composition of the polymer. In this case, any of amphoteric, cationic and anionic can be used. Moreover, since the addition amount of the aluminum compound can be changed in a wide range according to the conditions, it can be adapted to a wide range of papermaking conditions.

[0015]

EXAMPLES Examples of the present invention will be shown below, but the present invention is by no means limited to these examples. Various polyacrylamide-based copolymers used as paper strengthening agents in Examples and Comparative Examples were prepared as follows. In the following,% is all% by weight unless otherwise specified.

Production Example of Polyacrylamide Polymer-
1 530 g of water, 334.2 g of 40% acrylamide, and 10.8 of 80% acrylic acid were placed in a 1-liter four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas inlet tube.
g and isopropyl alcohol 3.0 g were charged, p
Adjust with acid or alkali so that H becomes around 3.5. Nitrogen gas was passed through the reaction system to remove oxygen. Then, the temperature was raised to 55 ° C. with stirring, and 15 g of a 5% ammonium persulfate solution and 10 g of 5% sodium sulfite were added as a polymerization initiator to initiate polymerization. Then 8
Polymerization was terminated by holding at 5 ° C for 2 hours. Nonvolatile matter 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 Example by changing the monomer composition corresponding to the composition shown in Table 1 and the amounts of the appropriate catalyst and chain transfer agent used. Obtained.

Production Example of Polyacrylamide Polymer-
2 To a 1-liter four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas inlet tube, 730 g of water, 298.6 g of 40% acrylamide, and 60% acryloylaminobrovir trimethylammonium chloride 82.8.
g, fumaric acid 9.2 g and isopropyl alcohol 3
Charge g and adjust with acid or alkali to adjust the pH to around 3.0. Nitrogen gas was passed through the reaction system to remove oxygen. Then, the temperature was raised to 55 ° C. with 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. Then, the temperature was maintained at 85 ° C. for 2 hours to complete the polymerization.
Nonvolatile content 15.8%, viscosity 4200 cps, pH 4.2
This polymer having a constant of is abbreviated as S-10A.

In a 1-liter four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas inlet tube, water 580
g, 402.8% acrylamide 312.8 g, dimethylaminopropyl acrylamide 12.5 g, 80% acrylic acid 14.4 g and isopropyl alcohol 3 g are charged, and the pH is adjusted to around 3.0 with acid or alkali. Nitrogen gas was passed through the reaction system to remove oxygen. Then, the temperature was raised to 55 ° C. with stirring, and 10 g of a 5% ammonium persulfate solution and 5% were used as a polymerization initiator.
Polymerization was initiated by adding 5 g of sodium sulfite. Then, the temperature was maintained at 85 ° C. for 2 hours to complete 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 polymers obtained (S-10A,
B) was mixed in a weight ratio of 1: 2 to obtain a nonvolatile content of 1
This polymer having a constant of 5.4%, viscosity of 6800 cps and pH 4.2 is abbreviated as S-10.

Hereinafter, Table 1 is prepared by the same method as the above-mentioned manufacturing example.
The base polymers S-11 to S-12 were obtained by changing the monomer composition corresponding to the composition shown in (1) and the amounts of the appropriate catalyst and chain transfer agent used. The polymer constants obtained are shown in Table 1.

[0021]

[Table 1]

Abbreviations of 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: DM chloride quaternary DM-BQ: DM benzyl chloride quaternary DMAPAA: dimethylaminopropyl acrylamide DMAPAA Q: dimethyl chloride quaternary of DMAPAA DMAPAA-BQ: benzyl chloride quaternary of DAMPAA

Example 1 WP was beaten with a Niagara type beater to obtain 380 ml of Canadian Standard Freeness (CSF).
It was 1600 μs / cm ² when the electric conductivity of the pulp prepared as above was adjusted to 3% slurry. After thoroughly stirring the pulp slurry, the amount of sulfuric acid band shown in Table 2 was added. Subsequently, the 2% diluted solutions of the polyacrylamide polymers S-1 to S-4 obtained above were mixed with the addition amounts of aluminum compounds shown in Table 2 and added to the pulp slurry. The obtained pulp slurry was made into a paper having a basis weight of 100 g / m ² with a square sheet machine, pressed at 5 kg / m ² for 1 minute, and further dried at 105 ° C. for 3 minutes to prepare a test paper. Furthermore, at 20 ° C. and 65% R. 2 under the condition of H
After conditioned for 4 hours, the specific burst strength was measured according to JIS P 8112. Table 2 shows the results.

[0024]

[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 3% of sulfuric acid band (based on pulp weight) was added to the same pulp slurry as in Example, and subsequently, polyacrylamide type polymers S-1 to S-4 obtained above were added. Hereinafter, handmade paper was prepared under the same conditions as in the examples, and measurements were carried out.

Example 2 WP was beaten with a Niagara type beater to obtain 360 ml of Canadian Standard Freeness (CSF).
It was 1200 μs / cm ² when the electric conductivity was measured by using the pulp prepared as described above in 3% slurry. After thoroughly stirring the pulp slurry, the amount of sulfuric acid band shown in Table 3 was added. Subsequently, the 2% diluted solutions of the polyacrylamide polymers S-4 to S-6 and S-10 and 11 obtained above were mixed with the addition amount of the aluminum compound shown in Table 3 and added to the pulp slurry. The obtained pulp slurry was made into a sheet having a basis weight of 100 g / m ² using a square sheet machine, and 5
A test paper was prepared by pressing at 1 kg / m ² for 1 minute and further drying at 105 ° C. for 3 minutes. Furthermore, 20 ℃, 65%
R. After conditioning the humidity for 24 hours under the condition of H, JIS P 8
According to 112, the specific burst strength was measured. The results are shown in Table 3.

[0027]

[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 Example.
(Vs. pulp weight), and subsequently to the polyacrylamide polymers S-4 to 6 and S-10, 11 obtained above. Hereinafter, a handmade paper is prepared under the same conditions as in Example 2,
The measurement was carried out.

Example 3 BKP was beaten with a Niagara type beater to obtain Canadian Standard Freeness (CSF) 400 m.
The pulp adjusted to 1 was made into a 3% slurry, and 15% of light calcium carbonate (based on the weight of pulp) was mixed, and the electric conductivity was measured to be 1500 μs / cm ² . After sufficiently stirring the pulp slurry, the 2% diluted liquids of the polyacrylamide polymers S-7 to 9 and S-12 obtained above were mixed with the addition amount of the aluminum compound shown in Table 4 and added to the pulp slurry. Furthermore, after stirring, the pulp slurry concentration is diluted to 1.5% and the retention agent is added to 200 ppm.
Was added. The obtained pulp slurry was made into paper having a basis weight of 80 g / m ² with a square sheet machine and 5 kg /
A test paper was prepared by pressing at m ² for 1 minute and further drying at 105 ° C. for 3 minutes. Furthermore, at 20 ° C. and 65% R. H
After conditioning the humidity for 24 hours under the conditions of JIS P 8112
The specific burst strength was measured according to. The results are shown in Table 4. *
Retention agent: NR IILH (made by Hymo)

[0030]

[Table 4] * 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 = 200ppm

Comparative Example 3 0.5% of sulfuric acid band was added to the same pulp slurry as in Example.
(Pulp weight) was added, and then the polyacrylamide-based polymers S-7 to S-9 and S-12 obtained above were added. Hereinafter, handmade paper was prepared under the same conditions as in Example 3 and measured.

The abbreviations of 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 Kagaku Co., Ltd.) PASS: Aluminum polysulfate silicate (manufactured by Nippon Light Metal Co., Ltd.)

Claims (2)

[Claims] 1. A diluted amphoteric, cationic and anionic additive to be added to a pulp slurry when at least one selected from the group consisting of amphoteric, cationic and anionic polyacrylamide polymers is added to the pulp slurry for papermaking. Comprising a step of previously mixing an aqueous solution in which a water-soluble aluminum compound is diluted with at least one diluent selected from the group consisting of a water-soluble polyacrylamide polymer, and a step of adding the mixed diluent to a pulp slurry. Characterizing paper manufacturing method. 2. The acrylamide polymer 0.1 to 0.1
The paper manufacturing method according to claim 1, wherein the aluminum compound is added to the 8% by weight dilution liquid in an amount of 0.1 to 200 mol% based on the polymer in terms of aluminum ion.