JP2001279599A - Paper-making method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a paper-making method in a paper-making system where the effect of aluminum sulfate can sufficiently be exhibited even by using aluminum sulfate. SOLUTION: The effect of an acrylamide-based polymer is brought out by associating a method where various kinds of acrylamide-based polymers in a mixed condition with an aluminum compound are added to pulp slurry or an aluminum compound is further added in a divided condition to the resultant mixture with a process where colloidal silicic acid is added to the pulp slurry.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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 the effect cannot be sufficiently exerted even when a sulfate band is used.

[0002]

2. Description of the Related Art Conventionally, in the papermaking industry, acrylamide polymers have been used for various purposes such as paper strength enhancers, drainage improvers, retention improvers, and flocculants.

[0003] In recent years, as part of energy saving measures and environmental measures, the papermaking process has been closed, and papermaking conditions have been changed to higher electric conductivity, higher pH, and higher temperature than before. Furthermore, the speed of the machine has been increased and the addition rate of the sulfuric acid band has been limited for the purpose of improving productivity, and the effect of improving the paper strength has been insufficient with conventional chemicals. There is a need for paper strength agents.

[0004] In order to meet such a demand, for example, an improvement in terms of ionic composition (Japanese Patent Laid-Open No.
JP-A-4-30913, JP-A-60-94697, etc.), those which are improved by introducing a cross-linked or branched structure into the polymer structure (JP-A-63-50597, JP-A-4-18190, JP-A-3-227489, JP-A-6-41898, JP-A-5-272092, JP-A-5-287693, JP-A-5-140892,
Japanese Patent Application Laid-Open Nos. 7-97790 and 8-67715 have been proposed.

[0005] However, the improvement effect obtained by these chemicals themselves is not sufficient, and there is a demand for the development of a method that provides a further improvement effect.

[0006]

Recently, papermaking in a neutral to weakly acidic region is increasing, but the amount of sulfate band used in such a papermaking system is at a relatively low level, and under high pH conditions. The sulfate band loses its ionicity and is inactivated and cannot exert a sufficient fixing effect. In general, the effect of adding a chemical is lower than that of an acidic system.

[0007] Furthermore, due to the deterioration of water quality due to the increase of salts and anion trash in the water used for the production of paper, the situation in which the band effect cannot be sufficiently exerted even in an acidic pH region is increasing.

It is an object of the present invention to provide a papermaking method in which the effect of the band can be effectively exhibited in a papermaking system in which the effect is not sufficient even when a sulfate band is used.

[0009]

Means for Solving the Problems The present inventors added a mixed diluent of a polyacrylamide-based polymer and a water-soluble aluminum compound to a pulp slurry, or prepared a mixture of a polyacrylamide-based polymer and a water-soluble aluminum compound. It has already been clarified that a further improvement effect can be obtained by mixing and adding the liquid in advance and separately adding the aluminum compound separately (Japanese Patent Application Laid-Open No. Hei 8-226092 and Japanese Patent Application No. Hei 11-179457). issue).

As a result of further studies, the present inventors have found that a method of adding a diluted mixture of the above-mentioned polyacrylamide polymer and a water-soluble aluminum compound to a pulp slurry, or a method of adding a water-soluble aluminum compound and a polyacrylamide polymer to a pulp slurry. It has been found that a further improved effect can be obtained by combining the method of adding colloidal silicic acid to the method of adding a diluted mixed solution of Reached.

[0011] A papermaking method in which an acrylamide polymer and colloidal silicic acid are added to a pulp slurry for papermaking (Japanese Patent Application Laid-Open Nos. Sho 62-15391 and Sho 64)
No. 45899, etc.), an aluminum compound, a cation retention improver and a polymer silicic acid are added to a pulp slurry to make paper.
No. 593) is already known.

Therefore, the papermaking method according to the present invention provides an amphoteric,
In adding at least one selected from the group consisting of cationic and anionic polyacrylamide-based polymers to the pulp slurry for papermaking, at least one kind selected from the group consisting of amphoteric, cationic and anionic polyacrylamide-based polymers A step of adding a mixed diluent obtained by mixing a diluent and an aqueous solution obtained by diluting a water-soluble aluminum compound to a pulp slurry; anda step of adding colloidal silicic acid to the pulp slurry to which the mixed diluent has been added. It is characterized by the following.

Further, the papermaking method according to the present invention is characterized in that at least one selected from the group consisting of amphoteric, cationic and anionic polyacrylamide-based polymers is added to a pulp slurry to make paper, and the amphoteric, cationic and anionic Mixing an aqueous solution obtained by diluting a water-soluble aluminum compound with at least one diluent selected from the group consisting of hydrophilic polyacrylamide-based polymers, adding the mixed diluent to a pulp slurry, And adding a colloidal silicic acid to the pulp slurry to which the pulp slurry is added.

Further, the papermaking method according to the present invention provides an amphoteric,
In adding at least one selected from the group consisting of cationic and anionic polyacrylamide polymers to the pulp slurry and making paper, at least one selected from the group consisting of amphoteric, cationic and anionic polyacrylamide polymers A mixed diluent obtained by mixing a diluent of the above and an aqueous solution obtained by diluting a water-soluble aluminum compound,
A step of adding a water-soluble aluminum compound to the pulp slurry, a step of adding colloidal silicic acid to the pulp slurry to which the mixed diluent and the water-soluble aluminum compound are added, and It is characterized by having.

Further, the papermaking method according to the present invention is characterized in that at least one selected from the group consisting of amphoteric, cationic and anionic polyacrylamide-based polymers is added to a pulp slurry to make paper. A step of mixing an aqueous solution obtained by diluting a water-soluble aluminum compound with at least one diluent selected from the group consisting of anionic polyacrylamide polymers, a step of adding the mixed diluent to a pulp slurry, It is characterized by comprising a step of dividing the compound and adding it to the pulp slurry, and a step of adding colloidal silicic acid to the pulp slurry to which the mixed diluent and the water-soluble aluminum compound have been added.

When the polyacrylamide polymer and the water-soluble aluminum compound are mixed, at least one selected from the group consisting of amphoteric, cationic and anionic polyacrylamide polymers is 0.1 to 10% by weight,
A water-soluble aluminum compound is preferably added in an amount of 0.1 to 200 mol%, preferably 10 to 100 mol%, based on aluminum ion, based on a solution diluted to 0.2 to 3% by weight.
It is preferable to add mol%.

The acrylamides used for producing the copolymer type polyacrylamide polymer used in the present invention include, for example, acrylamide, methacrylamide, N-methylacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide. , N-isopropylacrylamide, diacetone acrylamide and the like, which are water-soluble N-substituted lower alkylacrylamides, etc., and these can be used alone or in combination of two or more.

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, it is also possible to use organic sulfonic acids such as vinyl sulfonic acid, styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid and salts thereof, and these may be used alone or in combination of two or more. May be used in combination. Further, it is preferable to use a carboxylic acid monomer having a strong interaction with the aluminum compound.

Examples of the cationic monomer include (meth) acrylate derivatives such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, diethylaminopropyl (meth) acrylamide and the like. (Meth) acrylamide derivatives, tertiary amine monomers such as allylamine and diallylamine and salts of tertiary amine monomers with inorganic or organic acids such as hydrochloric acid, sulfuric acid and acetic acid, or tertiary amine monomers with methyl chloride and chloride Examples thereof include ammonium salt monomers quaternized by reaction with benzyl, dimethyl sulfate, epichlorohydrin, and the like. These ionic monomers can be used alone or in combination of two or more.

Examples of the nonionic monomer include (meth) acrylonitrile, alkyl acrylate, hydroxy acrylate, vinyl acetate, styrene, α-methylstyrene and the like. These are used as long as the water solubility of the polyacrylamide polymer is not impaired. It is possible to

It is also possible to use a small amount of a crosslinking agent in the copolymerization, for example, methylenebis (meth) acrylamide, ethylenebis (meth) acrylamide,
Bis (meth) acrylamide-methylol ethylene urea condensate, bis (meth) acrylamide-methylol urea, bis (meth) acrylic acid such as ethylene glycol di (meth) acrylamide, diethylene glycol di (meth) acrylamide, and triethylene glycol di (meth) acrylamide Acrylamides, di (meth) acrylates such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, divinyl esters such as divinyl adipate and divinyl sebacate, N, N-diallylacrylamide, 1,2,2 Trivinyl monomer-based crosslinking agents such as 3-triacroylhexahydro-S-triazine, triallyl isocyanurate,
Bifunctional crosslinking agents such as divinylbenzene and diallyl acrylamide; and 1,3,5-triacryloyl hexahydro-S-triazine, triallyl isocyanurate, pentaerythritol triacrylate, trimethylolpropane acrylate, and diacryloyl imide. Examples of the functional crosslinking agent include N-substituted acrylamide monomers such as dimethylacrylamide, diacetone acrylamide, and isopropylacrylamide. These crosslinking agents can be used alone or in combination of two or more. The amount of the crosslinking agent added is 0.005 to 1 mol%, preferably 0.01 to 1 mol%, based on the total amount of the monomers.
0.2 mol%.

The polymer can be polymerized by various known methods. For example, the above-mentioned various monomers and water are charged into a predetermined reaction vessel, and a persulfate such as potassium persulfate or ammonium persulfate or a redox polymerization initiator obtained by combining these with a reducing agent such as ammonium bisulfite is used. The desired polymer can be obtained by adding a radical polymerization initiator or an azo-based polymerization initiator, and optionally using a chain transfer agent such as isopropyl alcohol or allyl alcohol, and heating under stirring. . Further, the polymerization may be carried out while part or all of the monomer is dropped into the reaction vessel. The catalyst can be charged even once, but it is also possible to add a catalyst. The reaction temperature is usually about 40 to 100 ° C, and the reaction time is about 0.5 to 8 hours. A 15% aqueous solution of the polyacrylamide-based polymer thus obtained is
The viscosity measured at 5 ° C. by a Brookfield viscometer is 100 to 40,000 mPa · s, but usually preferably 500 to 20,000 mPa · s.

The polymerization initiator is not particularly limited as long as it is a radical polymerization initiator usually used in an aqueous solution, and examples thereof include peroxide catalysts such as hydrogen peroxide, benzoyl peroxide and t-butyl peroxide; Persulfate catalysts such as ammonium persulfate, sodium persulfate and potassium persulfate; bromate catalysts such as sodium bromate and potassium bromate; and perborate catalysts such as sodium perborate. Also, as these reducing agents, redox catalysts or azo catalysts obtained by combining a sulfite, a hydrogen sulfite, a transition metal salt, an organic amine, or the like can be used. These may be used alone or in combination of two or more. The amount of the polymerization initiator used is 0.01 to 10% by weight based on the total weight of the monomers,
Preferably it is 0.05 to 3% by weight.

The chain transfer agent is not always necessary, but may be optionally added as long as the object of the present invention is not impaired.
It is possible to use. Examples of chain transfer agents include:
Other than isopropyl alcohol, mercapto ethanol, thiourea, thioglycolic acid, mercaptopropionic acid, thiosalicylic acid, thiolactic acid, mercapto compounds such as aminoethanethiol, thioglycerol, thiomalic acid, allyl alcohol, sodium allyl sulfonate, methallyl sulfone Allyls such as sodium acid, methacrylonitrile and the like can be mentioned. One or more of these chain transfer agents can be used in combination. The addition amount of these chain transfer agents is 0.01 to 1 with respect to the total amount of the monomers.
0 mol%, preferably 0.02 to 4 mol%.

The polyacrylamide-based polymer can be applied irrespective of the polymer structure such as linear or branched, and can be generally used in the range of 5-40% by weight of the solid content which can be synthesized. However, when used as a papermaking additive, it is preferably used in a state of 15000 mPa · s or less, and the solid content concentration is preferably in the range of 5 to 30% by weight. 1 also selected from the group consisting of amphoteric, cationic and anionic polyacrylamide polymers in terms of composition
Species as well as mixtures of two or more are also applicable. Therefore, a product having a polymer concentration in the above-mentioned range may be obtained by adjusting the amount of a solvent or a reaction component during the polymerization reaction. In the present invention, such a low-concentration polymer solution also includes such a solution.

It is also possible to apply a modified Mannich polymer or a Hoffman-decomposed polymer which introduces ionicity by modification after polymerization.

As the aluminum compound to be mixed with the polyacrylamide-based polymer or separately added separately, any mixing ratio may be used 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. In particular, a sulfuric acid band (aluminum sulfate) used in the papermaking process is preferable in terms of handling and cost.

When the aluminum compound is mixed with the polymer diluent, the mixture is diluted to such a concentration that the viscosity of the polymer is not increased by mixing and the workability is not impaired. Therefore, the concentration of the diluting solution of the water-soluble aluminum compound varies depending on the polymer composition and cannot be specified unconditionally, but it is within 0.05% of the undiluted solution, preferably about 0.2% of the undiluted solution.

The mixing time of the two diluents is preferably immediately before the addition to the pulp slurry or within 10 hours, more preferably within 1 hour before the 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 mixing amount of the aluminum compound can be increased to a high concentration range as compared with the case of mixing with the stock polymer solution, and is 0.1 to 200 mol%, more preferably 5 mol%, based on the polymer in terms of aluminum ions. % To 1
00 mol%.

When the aluminum compound is added separately, the aluminum compound is added in divided portions. The addition method is a two-stage process prior to the step of adding the mixed dilution of the polyacrylamide polymer and the aluminum compound to the pulp slurry. Any method of adding, adding in two stages at a stage after the process of adding the mixed diluent, and adding at each stage before and after the process of adding the mixed diluent is possible. The method is most preferable from the viewpoint of improvement of the above.

Specifically, when it is assumed that the aluminum compound is added to the seed box of the polyacrylamide-based polymer, the addition position of the first stage of the aluminum compound may be near the machine chest and the second stage may be near the fan pump. Can be

When the aluminum compound is separately divided and added, the division ratio of the aluminum compound is 95: 5 to 5: 5.
It is in the range of 5:95, preferably in the range of 80:20 to 20:80.

The addition of colloidal silicic acid is one of the features of the present invention.
The particle diameter of the colloidal silicic acid is 30 μm or less, preferably 1 to 20 μm. If it exceeds 30 μm, it is difficult to obtain a sufficient effect as compared with particles having a particle diameter smaller than 30 μm. The amount of the colloidal silicic acid added is 0.005% by weight to 2% by weight, preferably 0.01% by weight, based on the weight of dry pulp in the pulp slurry.
% By weight to 1% by weight. Since the colloidal silicic acid exhibits an effect by interaction with the polyacrylamide-based polymer used in combination, if it exceeds 2% by weight, the yield effect is good, but there is a problem that the cost increases, and if it is less than 0.005% by weight, there is a problem. This is because a special effect cannot be obtained.

The anionicity of the colloidal silicic acid decreases in the low pH range, but the anionicity can be kept high even in the low pH range by modifying the surface with aluminum ions. The colloidal silicic acid of the present invention also includes this aluminum-modified colloidal silicic acid.

When the colloidal silicic acid is added to the pulp slurry, it is desirable to add it separately from the polyacrylamide-based polymer or the aluminum compound, and if it is mixed and added, a sufficient yield improving effect cannot be obtained.

As for the addition position, it is desirable to add colloidal silicic acid after the addition of the polyacrylamide-based polymer or the aluminum compound, and when added first, the yield and paper strength are not as improved as the former.

[0039]

According to the present invention, any acrylamide-based polymer thickens or gels when an aluminum compound is mixed with a stock solution before dilution, so that ionic cross-linking via aluminum ions proceeds. Seems to be. On the other hand, when the acrylamide-based polymer and the colloidal silicic acid are simply added to the pulp slurry, the acrylamide-based polymer is not sufficiently agglomerated, and the colloidal silicic acid does not affect the aggregation of the polymer. When colloidal silicic acid is added in a state where ionic cross-linking has progressed, aggregation of the acrylamide polymer is further promoted via colloidal silicate ions, and aluminum ions via excess colloidal silicate ions existing on the pulp surface It seems that ionic cross-linking has progressed. It is presumed that this crosslinked structure caused the expansion of the polymer and a change in the molecular weight, and improved the structural factors of the pulp.

Furthermore, the mixed solution is acidic in pH, and many aluminum ions coexist with the polymer as an active cationic species. It is thought that the action works effectively, the yield to pulp is increased, and excellent effects on paper strength and drainage are exhibited.

Since the aluminum compound is added to a solution obtained by diluting the acrylamide-based polymer to some extent, an inappropriate thickening or gelling as an additive is prevented.
In addition, since there is no restriction on the composition of the polymer, any amphoteric, cationic, or anionic acrylamide-based polymer 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.

[0042]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below based on examples, but the present invention is by no means limited to these examples. Various polyacrylamide-based copolymers used as a paper strength agent in Examples and Comparative Examples were prepared as follows. In the following, “%” means “% by weight” unless otherwise specified.

[0043]

[Production Example 1 of Polyacrylamide Polymer] In a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube, 530 g of water and 40% acrylamide 3 were added.
34.2 g, 10.8 g of 80% acrylic acid, and 3.0 g of isopropyl alcohol are charged, and adjusted with an acid or an alkali so that the pH 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% aqueous solution of ammonium persulfate and 10 g of a 5% aqueous solution of sodium sulfite were used as polymerization initiators.
And polymerization was started. Thereafter, the temperature was maintained at 85 ° C. for 2 hours to terminate the polymerization. Non-volatile content 15.6%, viscosity 10
This polymer having a constant of 800 mPa · s and a pH of 4.1 is abbreviated as S-1.

Hereinafter, Table 1 was prepared in the same manner as in the above-mentioned production example.
The base polymers S-2 to S-9 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.

[0045]

[Production Example 2 of Polyacrylamide Polymer] In a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube, 730 g of water, 40% acrylamide 2 were added.
98.6 g, 60% acryloylaminopropyl trimethylammonium chloride 82.8 g, fumaric acid 9.
2 g and 3 g of isopropyl alcohol are charged, and the mixture is adjusted with an acid or an alkali so that the pH becomes about 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% aqueous solution of ammonium persulfate and 5 g of a 5% aqueous solution of sodium sulfite were added as polymerization initiators to initiate polymerization. After that, 85 ° C
For 2 hours to complete the polymerization. Non-volatile content 15.8
%, A viscosity of 4200 mPa · s and a constant number of pH 4.2 are 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 was added.
g, 402.8% acrylamide, 312.8 g, dimethylaminopropylacrylamide, 12.5 g, 80% acrylic acid, 14.4 g, and isopropyl alcohol, 3 g, and adjust with acid or alkali so that the pH becomes about 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% aqueous solution of ammonium persulfate and 5 g of a 5% aqueous solution of sodium sulfite were added as polymerization initiators to initiate polymerization. Thereafter, the temperature was maintained at 85 ° C. for 2 hours to terminate the polymerization. This polymer having a nonvolatile content of 15.1%, a viscosity of 3700 mPa · s and a constant of pH 4.3 is abbreviated as S-10B.

The obtained two kinds of polymers (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 mPa · s 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.

[0049]

[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 quaternary DM-BQ: DM benzyl quaternary Compound DMAPAA: dimethylaminopropylacrylamide DMAPAA-Q: Methyl quaternary chloride of DMAPAA DMAPAA-BQ: Benzyl chloride quaternary of DAMPAA

The colloidal silicic acid used was manufactured by Nippon Chemical Industry Co., Ltd., and its composition and physical properties are as follows. SiO ₂ : 8.2%, Na ₂ O: 0.23%, Al ₂ O ₃ :
0.29% pH: 8.8 Particle size: 4.6 nm

[0052]

Example 1 Cardboard waste paper (WP) was beaten with a Niagara beater, and pulp adjusted to 380 ml of Canadian Standard Freeness (CSF) was 3%.
1600 μs /
cm ² . After thoroughly stirring the pulp slurry, Table 2
The amount of sulfuric acid band indicated in (1) was added. Subsequently, the aluminum compound of the addition amount shown in Table 2 was mixed with the 2% diluent of the polyacrylamide-based polymers S-1 to S-4 obtained above, and added to the pulp slurry. Silicic acid was added.

The obtained pulp slurry was made into paper having a basis weight of 100 g / m ² using a square sheet machine,
The paper was pressed at g / 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 2 shows the results.

[0054]

[Table 2]

* PH 4.7, Alum 3.0%, electric conductivity 1600 μs / cm ² WP, basis weight: 100 g / cm ²

[0056]

Comparative Example 1 Sulfuric acid bands were added to the same pulp slurry as in Example 1 in an amount of 3% (based on pulp weight), and subsequently added to the polyacrylamide-based polymers S-1 to S-4 obtained above. Hereinafter, hand-made paper was prepared under the same conditions as in Example 1, and the measurement was performed.

[0057]

Comparative Example 2 Polyacrylamide-based polymers S-1 to S-4 were added to a pulp slurry under the same conditions as in Comparative Example 1, and then the addition amount of colloidal silicic acid shown in Table 2 was added. Hereinafter, hand-made paper was prepared under the same conditions as in Example 1, and the measurement was performed.

[0058]

Comparative Example 3 A hand-made paper was prepared and measured under the same conditions as in Example 1 without adding colloidal silicic acid.

[0059]

Example 2 Waste cardboard (WP) was beaten with a Niagara beater, and pulp adjusted to 360 ml of Canadian Standard Freeness (CSF) was 3%.
When the electric conductivity is measured as a slurry of 1200 μs /
cm ² . After thoroughly stirring the pulp slurry, Table 3
The amount of sulfuric acid band indicated in (1) was added. Subsequently, the polyacrylamide-based polymers S-4 to 6 and S-1 obtained above were obtained.
The aluminum compounds in the amounts shown in Table 3 were mixed with the 2% dilutions of 0 and 11 and added to the pulp slurry.
The addition amount of colloidal silicic acid shown in (1) was added.

The obtained pulp slurry was made into a paper having a basis weight of 100 g / m ² by using a square sheet machine.
The paper was pressed at g / 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.

[0061]

[Table 3]

* PH 6.0, Alum 1.5%, electric conductivity 1200 μs / cm ² WP basis weight: 100 g / cm ²

[0063]

Comparative Example 4 A sulfuric acid band was added to the same pulp slurry as in the example by 1.5% (based on pulp weight), followed by the polyacrylamide-based polymers S-4 to 6 and S-1 obtained above.
0 and 11 were added. Hereinafter, hand-made paper was prepared under the same conditions as in Example 2, and the measurement was performed.

[0064]

Comparative Example 5 Polyacrylamide-based polymers S-4 to S-6 and S-10 and 11 were added to a pulp slurry under the same conditions as in Comparative Example 4, and then colloidal silicic acid in an amount shown in Table 3 was added. Hereinafter, hand-made paper was prepared under the same conditions as in Example 2, and the measurement was performed.

[0065]

Comparative Example 6 A hand-made paper was prepared under the same conditions as in Example 2 without adding colloidal silicic acid, and the measurement was performed.

[0066]

Example 3 Bleached kraft pulp (BKP) was beaten with a Niagara beater to obtain Canadian Standard
The pulp adjusted to 400 ml of freeness (CSF) was made into a 3% slurry, 15% of light calcium carbonate (with respect to pulp weight) was mixed, and the electric conductivity was measured.
It was 00 μs / cm ² . After sufficiently stirring the pulp slurry, the polyacrylamide-based polymer S-7 obtained above was obtained.
The aluminum compounds in the addition amounts shown in Table 4 were mixed with the 2% diluents of Nos. To 9 and S-12, added to the pulp slurry, and then the colloidal silicic acid in the addition amounts shown in Table 4 was added. Further, after stirring, the pulp slurry concentration was diluted to 1.5%, and a retention agent of 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 of paper was obtained.
/ M ² for 1 minute, and further dried at 105 ° C. for 3 minutes to prepare a test paper. Furthermore, at 20 ° C., 65% R.F.
After conditioning for 24 hours under the conditions of H, JIS P 811
The specific burst strength was measured according to 2. Table 4 shows the results.
* Retention agent: NR-11LH (manufactured by Hymo)

[0068]

[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 = 200 ppm

[0070]

Comparative Example 7 To the same pulp slurry as in Example 3, 0.5% (by weight of pulp) of a sulfuric acid band was added, followed by the polyacrylamide polymers S-7 to 9 and S-1 obtained above.
2 was added. Hereinafter, a hand-made paper was prepared under the same conditions as in Example 3 and the measurement was performed.

[0071]

Comparative Example 8 Polyacrylamide-based polymers S-7 to S-9 and S-12 were added to a pulp slurry under the same conditions as in Comparative Example 7, and then colloidal silicic acid in an amount shown in Table 4 was added. Hereinafter, hand paper was prepared under the same conditions as in Example 3,
The measurement was performed.

[0072]

Comparative Example 9 A hand-made paper was prepared under the same conditions as in Example 2 without adding colloidal silicic acid, 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 polysulfate silicate (manufactured by Nippon Light Metal Co., Ltd.)

[0074]

[Production Example 3 of Polyacrylamide Polymer] A 40% acrylamide aqueous solution 331 was placed in a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet pipe.
Parts, 80% acrylic acid 13 parts and water 450 parts,
The pH was adjusted to 3.2 with sulfuric acid, and oxygen in the reaction system was removed through nitrogen gas. The system was heated to 44 ° C., and 24 parts of a 10% aqueous solution of ammonium persulfate and 15 parts of a 5% aqueous solution of sodium bisulfite were charged as a polymerization initiator with stirring. After the temperature was raised to 90 ° C., 5 parts of a 10% ammonium persulfate aqueous solution was further added, and the temperature was maintained for 2 hours. After the completion of the polymerization reaction, 150 parts of water was charged to obtain a polymer aqueous solution S-21 having a pH of 3.7, a solid content of 15.4%, and a viscosity (25 ° C) of 4600 mPa · s.

[0075]

[Production Example 4 of Polyacrylamide Polymer] The same operation as in Production Example 3 was carried out except that the kind of the monomer or the ratio of the monomer used in Production Example 3 was changed as shown in Table 1, and various polymer aqueous solutions S-22 were used. ~ 29 was obtained. Table 6 shows the property values of the obtained aqueous polymer solutions.

[0076]

[Table 5]

In Table 5, as acrylamide monomers, AM: acrylamide, as anionic monomers, AA: acrylic acid, IA: itaconic acid, FA: fumaric acid, MA: maleic acid, and as cationic monomers,
DM: dimethylaminoethyl methacrylate, DMAP
AA: dimethylaminopropylacrylamide, DMB
Q: quaternized product of DM with benzyl chloride, MBAM: methylenebisacrylamide, D
MAM: dimethylacrylamide, as a chain transfer agent
IPA: isopropyl alcohol, MAS: sodium methallyl sulfonate, AS: sodium allyl sulfonate, respectively.

[0078]

[Table 6]

[0079]

Example 4 Waste cardboard was beaten with a Niagara beater, and a total of 3.0% of a sulfuric acid band was added to pulp adjusted to 410 ml of Canadian Standard Freeness (CSF) to reach pH 5.4. The conditions were set to make a pulp slurry. After sufficiently stirring the pulp slurry, a predetermined amount of the aluminum compound and a mixture of the aluminum compound and the polyacrylamide polymer was added at the addition positions shown in Table 8 and the addition amounts shown in Table 7 under stirring conditions, and then the colloid was added. Silicic acid was added to the pulp slurry at the times shown in Table 8 in the amounts shown in Table 7.

[0080]

[Table 7]

* Papermaking conditions: Total Alum amount = 3.
0%, pH 5.4 Addition amount of acrylamide-based polymer (PAM) = 0.4% * Mixed Alum: Amount of Alum mixed and added to PAM

Each addition step (addition position) shown in Table 8 was carried out at the addition time intervals shown in Table 7.

[0083]

[Table 8]

The initial pulp concentration was 2.8%, and after 3.5 minutes, it was diluted to 1% with pH-adjusted water. Are assumed to be near the mixing chest, machine chest, seed box, and fan pump of a standard actual machine. Next, the pulp slurry concentration was diluted to 0.07%, and papermaking was performed with a tappy sheet machine to a basis weight of 100 g / m ² to obtain a wet sheet. 5 kg /
Press dewatering for 1 minute at ² cm ² and drying at 105 ° C. for 3 minutes with a rotary drum dryer. Furthermore, at 20 ° C, 6
5% R. H. After conditioning for 24 hours under the conditions of JIS
The specific burst strength was measured according to P 8112. Table 7 shows the results. In this study, mixing 1% of Alum with 0.4% of polyacrylamide-based polymer corresponds to an addition amount of 28 mol% to the polymer in terms of aluminum ions.

[0085]

Comparative Example 10 After the pulp slurry of Example 4 was sufficiently stirred, the aluminum compound and the mixture of the aluminum compound and the polyacrylamide polymer were added under stirring conditions at the addition positions shown in Table 8 and the addition amounts shown in Table 7. A predetermined amount of the liquid was added.

[0086]

Comparative Example 11 After the same operation as in Comparative Example 10 was performed, colloidal silicic acid was added to the pulp slurry at the timing shown in Table 8 in the amount shown in Table 7.

[0087]

Comparative Example 12 The same operation as in Example 4 was performed, but
The difference is that no colloidal silicic acid was added.

[0088]

Comparative Examples 13 to 15 The same operation as in Example 4 was carried out, but the addition time of the colloidal silicic acid was set between Table 8 in Comparative Example 13, Table 8 in Comparative Example 14, and Comparative Example 15
In Table 8, specific burst strength and drainage were examined in the same manner as in Example 4. Table 9 shows the results.

[0089]

[Table 9]

[0090]

Example 5 Cardboard waste paper was beaten with a Niagara beater, and 2.5% of a sulfuric acid band was added to the pulp adjusted to 410 ml of Canadian Standard Freeness (CSF) to reach pH 6.2. The conditions were set to make a pulp slurry. After sufficiently stirring the pulp slurry, a predetermined amount of each of the aluminum compound and the mixture of the aluminum compound and the polyacrylamide polymer was added at the addition positions and amounts shown in Table 10 under stirring conditions, and the colloidal silicic acid was added to Table 8 At the time indicated by, the amount of addition shown in Table 10 was added to the pulp slurry. Table 1
The addition positions indicated by 0 are the same as the addition positions in Example 4.

Next, the pulp slurry concentration was reduced to 0.07%.
Diluted with tappy sheet machine, basis weight 100g /
The paper was made so as to obtain a wet sheet. The sheet was press dewatered at 5 kg / cm @ 2 for 1 minute and dried on a rotary drum dryer at 105 DEG C. for 3 minutes. further,
20 ° C., 65% R.C. H. After conditioning for 24 hours under the above conditions, the specific burst strength was measured according to JIS P8112. Table 10 shows the results.

[0092]

[Table 10]

* Papermaking conditions: Total Alum amount = 2.
5%, pH 6.2 Acrylamide-based polymer (PAM) addition amount = 0.4% * Mixed Alum: amount of Alum mixed and added to PAM

[0094]

Comparative Example 16 After sufficiently stirring the pulp slurry of Example 5, under the stirring conditions, the aluminum compound and the mixing of the aluminum compound and the polyacrylamide-based polymer were performed at the addition positions shown in Table 8 and the addition amounts shown in Table 10. A predetermined amount of the liquid was added.

[0095]

Comparative Example 17 After the same operation as in Comparative Example 16 was performed, colloidal silicic acid was added to the pulp slurry at the timing shown in Table 8 in the amount shown in Table 10.

[0096]

Comparative Example 18 The same operation as in Example 5 was performed, but
The difference is that no colloidal silicic acid was added.

[0097]

Example 6 Hardwood bleached kraft pulp (LBKP) was beaten with a Niagara beater and adjusted to 390 ml of Canadian Standard Freeness (CSF). The band was added to 1.5% and the conditions were adjusted to pH 7.8 to obtain a pulp slurry. After sufficiently stirring the pulp slurry and the calcium carbonate mixture, a predetermined amount of each of the aluminum compound and the mixture of the aluminum compound and the polymacrilamide polymer was added at the addition positions shown in Table 11 under stirring conditions, and then the colloidal silica was added. Was added to the pulp slurry at the times shown in Table 8 in the amounts shown in Table 10. Each addition position shown in Table 10 is the same as the addition position in Example 1.

Next, the pulp slurry concentration was reduced to 0.07%.
To 70 g / m ² with tappy sheet machine
Paper was obtained to obtain a wet sheet. 5 sheets
Press dewatering was performed at 1 kg / cm ² for 1 minute, followed by drying at 105 ° C. for 3 minutes with a rotary drum dryer. In addition, 20
° C, 65% R.C. H. After conditioning for 24 hours under the conditions of
The specific burst strength was measured according to JIS P8112.
Table 11 shows the results.

[0099]

[Table 11]

* Papermaking conditions: Total Alum amount = 1.
5%, pH 7.8 Addition amount of acrylamide polymer (PAM) = 0.4% * Mixed Alum: Amount of Alum mixed and added to PAM

[0101]

Comparative Example 19 After sufficiently stirring the pulp slurry of Example 6, under the stirring conditions, the aluminum compound and the mixing of the aluminum compound and the polyacrylamide polymer were performed at the addition positions shown in Table 8 and the addition amounts shown in Table 11. A predetermined amount of the liquid was added.

[0102]

Comparative Example 20 After the same operation as in Comparative Example 19 was performed, colloidal silicic acid was added to the pulp slurry at the timing shown in Table 8 in the amount shown in Table 11.

[0103]

Comparative Example 21 The same operation as in Example 6 was performed, but
The difference is that no colloidal silicic acid was added.

Under the condition that the pH was as high as 7 or more and the amount of the sulfuric acid band used was small, as shown in Table 11, the examples exhibited excellent effects in improving drainage and paper strength as compared with the comparative example.

The abbreviations of the aluminum compounds in each table are as follows. Alum: liquid sulfuric acid band PAC: polyaluminum chloride (LOCRONS, manufactured by Hoechst Japan) AS: alumina sol (alumina sol 100, manufactured by Nissan Chemical Co., Ltd.) PASS: aluminum polysilicate silicate (manufactured by Nippon Light Metal Co., Ltd.)

Claims (8)

[Claims] Claims: 1. An amphoteric, cationic and anionic polyacrylamide-based polymer, wherein at least one selected from the group consisting of amphoteric, cationic and anionic polyacrylamide-based polymers is added to a pulp slurry to make paper. Adding a mixed diluent obtained by mixing at least one diluent selected from the above and an aqueous solution of a water-soluble aluminum compound to a pulp slurry; and adding colloidal silicic acid to the pulp slurry to which the mixed diluent has been added. And a papermaking method comprising: 2. A paper made of amphoteric, cationic and anionic polyacrylamide-based polymers, in which at least one selected from the group consisting of amphoteric, cationic and anionic polyacrylamide-based polymers is added to a pulp slurry for papermaking. Mixing an aqueous solution of a water-soluble aluminum compound with at least one diluent selected from the group consisting of: a step of adding the mixed diluent to a pulp slurry; and a step of adding colloidal silica to the pulp slurry to which the mixed diluent has been added. And a step of adding. 3. An amphoteric, cationic, and anionic polyacrylamide-based polymer, which is used for adding at least one selected from the group consisting of amphoteric, cationic, and anionic polyacrylamide-based polymers to a pulp slurry for papermaking. Adding a mixed diluent obtained by mixing at least one diluent selected from the group and an aqueous solution of a water-soluble aluminum compound to a pulp slurry; dividing the water-soluble aluminum compound into a pulp slurry; A step of adding colloidal silicic acid to a pulp slurry to which a mixed diluent and a water-soluble aluminum compound have been added. 4. An amphoteric, cationic, and anionic polyacrylamide-based polymer is added to at least one selected from the group consisting of amphoteric, cationic, and anionic polyacrylamide-based polymers to a pulp slurry for papermaking. Mixing an aqueous solution of a water-soluble aluminum compound with at least one diluent selected from the group; adding the mixed diluent to a pulp slurry; dividing the water-soluble aluminum compound into pulp slurry; A step of adding colloidal silicic acid to the pulp slurry to which the mixed diluent and the water-soluble aluminum compound have been added,
A papermaking method comprising: 5. A water-soluble aluminum compound is added to at least one diluent of 0.1 to 10% by weight selected from the group consisting of amphoteric, cationic and anionic polyacrylamide-based polymers with respect to the polymer in terms of aluminum ions. The papermaking method according to any one of claims 1 to 4, wherein 0.1 to 200 mol% is added. 6. The method according to claim 3, wherein the water-soluble aluminum compound is added separately before and after the step of adding the mixed dilution of the polyacrylamide polymer and the water-soluble aluminum compound to the pulp slurry. Papermaking method. 7. A pulp slurry containing colloidal silicic acid having a particle diameter of 1 to 30 μm.
The papermaking method according to any one of the above. 8. The papermaking paper according to claim 1, wherein the colloidal silicic acid is added in an amount of 0.005% by weight to 2% by weight in terms of silicic anhydride based on the weight of the dry pulp in the pulp slurry. Method.