JPH10131085A - Additive for papermaking and production of paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an additive for papermaking, comprising an aqueous mixture containing an ionic polyacrylic amide composed of N-substituted (meth) acrylamide monomers and an ionic polyacrylic amide and utilizable as a drainage agent for papermaking, a paper-strengthening agent or filler-retaining agent, etc. SOLUTION: This additive for papermaking comprises an aqueous mixture of (A) an ionic polyacrylic amide composed of N-substituted (meth)acrylic amide monomers of the formula CH2 =C(R<1> )-CINR<2> (R<3> ) (R<1> is H or methyl; R<2> is H or a 1-4C alkyl; R<3> is a 1-4C alkyl), having 0 to <1 equivalent ratio (cationic group/anionic group) of ionic functional group and 300,000 to 4,000,000 weight- average molecular weight and (B) an ionic polyacrylic amide having 0 to <1 equivalent ratio (anionic group/cationic group) of ionic functional group and 100,000 to 5,000,000 weight-average molecular weight.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a papermaking additive which can be used as a papermaking filter, a paper strength enhancer, a filler retention agent, a size fixing agent, and the like, and a paper-making additive using the papermaking additive. It relates to a manufacturing method. In particular, the papermaking additive of the present invention is useful as a papermaking filtration agent and paper strength enhancer.

[0002]

2. Description of the Related Art Conventionally, anionic polyacrylamide, cationic polyacrylamide or amphoteric polyacrylamide has been known as a papermaking additive. As a method for producing paper using these papermaking additives,
A formulation using one kind of papermaking additive alone or a combination formulation using two or more kinds separately is adopted. Also,
It is known that polyacrylamide generally has a higher molecular weight and exhibits a better water-filtration and paper-strengthening effect such as a paper-strengthening effect. However, a papermaking additive using a high molecular weight type polyacrylamide has an extremely high viscosity, and thus is inferior in workability as compared with a low molecular weight type polyacrylamide. On the other hand, the low molecular weight type has no problem in terms of work efficiency, but is not sufficient in terms of the effect as a papermaking additive as compared with the high molecular weight type.

[0003] Formulation with a stable aqueous mixture obtained by previously mixing a relatively low molecular weight anionic polyacrylamide and a cationic polyacrylamide is also being studied. According to such a mixed formulation, the effect as a papermaking additive can be exhibited to some extent without lowering the working efficiency in the pH range of 4.5 to 5.5.

[0004]

However, even with such a mixed formulation, the effect as a papermaking additive, in particular, drainage and paper strength were not sufficient. In addition, when the molecular weight of polyacrylamide is increased to improve the effect as a papermaking additive by such a mixed formulation, drainage is improved, but formation disorder is induced, and a sufficient paper strength effect cannot be obtained. . Furthermore, in recent years, the ratio of used paper has been increasing, and the papermaking pH has tended to increase due to the closure of the paper manufacturing process as part of environmental measures. It was difficult to operate stably with the mixed formulation.

The present invention provides a papermaking additive which is excellent in various effects as a papermaking additive such as drainage and paper strength, has a wide range of papermaking pH, and is excellent in operability. It is an object of the present invention to provide a method for producing a wrapped paper.

[0006]

Means for Solving the Problems In order to solve the above problems, the present inventors have intensively studied a mixed formulation using anionic polyacrylamide and cationic polyacrylamide. As a result, an ionic polyacrylamide of a specific molecular weight containing a specific N-substituted (meth) acrylamide as a constituent monomer and having a relatively large number of anionic groups, and a ratio of an ionic functional group Found that the above object can be achieved by a papermaking additive obtained by previously mixing with a specific molecular weight ionic polyacrylamide having a relatively large number of cationic groups, and the present invention has been achieved.

That is, the present invention relates to (A) general formula (1): CH ₂ ＣC (R ¹ ) -CONR ² (R ³ ) (R ¹
) Is a hydrogen atom or a methyl group, R ² represents a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, R ³
Is an ionic polyacrylamide containing, as a constituent monomer, an N-substituted (meth) acrylamide represented by a linear or branched alkyl group having 1 to 4 carbon atoms, and the equivalent ratio of the ionic functional group (cation Group / anionic group)
Is in the range of 0 to less than 1 and has a weight average molecular weight of 300,000 to 40.
100,000 ionic polyacrylamide and (B) ionic polyacrylamide, wherein the equivalent ratio of an ionic functional group (anionic group / cationic group) is in a range of 0 to less than 1 and a weight average molecular weight of 100,000 To a papermaking additive consisting of an aqueous mixture containing 万 5 million ionic polyacrylamide, and further to a pulp slurry having a pH of 4.5 to 7.0,
The present invention relates to a method for producing paper, wherein the papermaking additive is added and papermaking is performed.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The ionic polyacrylamide (A) used in the present invention is, for example, (a) (meth)
Acrylamide, the equivalent ratio of the ionic functional group (cationic group / anionic group) is in the range of 0 to less than 1 (b) the ionic vinyl monomer and (c) the general formula (1): CH
₂ ＣC (R ¹ ) -CONR ² (R ³ ) (R ¹ is a hydrogen atom or a methyl group, R ² is a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, and R ³ is a carbon atom number. 1-4
Is obtained by copolymerizing an N-substituted (meth) acrylamide represented by the following formula:

(A) (meth) acrylamide means acrylamide or methacrylamide, which can be used alone or in combination. From the viewpoint of economy, acrylamide is preferably used alone. Hereinafter, in the present invention, (meta) has the same meaning. The amount of the component (a) to be used is generally about 50 to 98.9 mol%, preferably 50 to 96.5 mol%, more preferably 50 to 98.9 mol%, based on the total mol of the monomers constituting the ionic polyacrylamide (A). Is 65 to 96.5 mol%. If the amount of the component (a) is less than 50 mol%, it is difficult to obtain a sufficient paper strength effect as a papermaking additive.

(B) The ionic vinyl monomer means an anionic vinyl monomer and a cationic vinyl monomer.

Examples of the anionic vinyl monomer include monocarboxylic acids such as (meth) acrylic acid, crotonic acid and (meth) allyl carboxylic acid; dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid and muconic acid; vinyl sulfone Acid, styrenesulfonic acid, 2-acrylamide-
Organic sulfonic acids such as 2-methylpropanesulfonic acid and (meth) allylsulfonic acid; and alkali metal salts such as sodium salt and potassium salt of these various organic acids, and ammonium salts. One or two or more of these anionic vinyl monomers can be used without any particular limitation.
Use of a monomer having an allyl group, in particular, (meth) allylsulfonic acid or a salt thereof is preferred in that the obtained ionic polyacrylamide has a high molecular weight. Especially,
It is preferable to combine (meth) acrylic acid and / or itaconic acid with (meth) allylsulfonic acid or a salt thereof.

As the cationic vinyl monomer, for example, vinyl having a tertiary amino group such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, diethylaminopropyl (meth) acrylamide, etc. By reacting monomers or their salts of inorganic or organic acids such as hydrochloric acid, sulfuric acid and acetic acid, or the tertiary amino group-containing vinyl monomer with quaternizing agents such as methyl chloride, benzyl chloride, dimethyl sulfate and epichlorohydrin; Examples of the obtained quaternary ammonium salt-containing vinyl monomer include:

The amount of (b) the ionic vinyl monomer (total of the anionic vinyl monomer and the cationic vinyl monomer) used is usually from 1 to 1 based on the total molar amount of the monomers constituting (A) the ionic polyacrylamide. It is about 40 mol%, preferably 3 to 40 mol%, more preferably 3 to 30 mol%. However, (b) the ionic vinyl monomer is the equivalent ratio of the ionic functional groups in the (A) ionic polyacrylamide (cationic group / anionic group).
Is used in such a ratio as to be 0 to less than 1. That is, (A) the ionic polyacrylamide of the present invention is an anionic polyacrylamide using only an anionic vinyl monomer as the ionic vinyl monomer, or an anionic vinyl monomer and a cation having a relatively large number of anionic groups. It is an anion-rich amphoteric polyacrylamide using a hydrophilic vinyl monomer. In particular, the ionic vinyl monomer used for (A) the ionic polyacrylamide is preferably used in such a ratio that the equivalent ratio of the ionic functional group (cationic group / anionic group) is in the range of 0 to 0.8. .

The means for imparting a cationic group to (A) the ionic polyacrylamide can be obtained by copolymerizing a cationic vinyl monomer as described above.
Cationic groups can also be introduced by Mannich modification by reacting polyacrylamide or anionic acrylamide with formalin and a secondary amine, or by the Hoffman reaction of reacting hypohalite. Even when introducing a cationic group by such modification,
(A) In the ionic polyacrylamide, the amount of the ionic vinyl monomer containing a cationic monomer unit based on Mannich modification or the like and the equivalent ratio of the ionic functional group (cationic group / anionic group) are as described above. The same is true.

In the above, when the equivalent ratio of the ionic functional group (cationic group / anionic group) is not in the above range,
Since the obtained ionic polyacrylamide becomes cation-rich, the effect as a papermaking additive, which is the main object of the present invention, is not exhibited even if an aqueous mixture with the ionic polyacrylamide (B) described below is prepared.

(C) General formula (1): CH ₂ ＣC (R ¹ )
—CONR ² (R ³ ) (R ¹ is a hydrogen atom or a methyl group, R ² is a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, and R ³ is a linear or N-substituted (meth) acrylamides represented by a (branched alkyl group) have many branches in a polymer by utilizing the fact that a methyl group or a methylene group in the N-alkyl group acts as a chain transfer point. Used to introduce a structure and obtain a branched polymer without gelation. Examples of the linear or branched alkyl group having 1 to 4 carbon atoms for R ² or R ³ in the general formula (1) include a methyl group, an ethyl group, an isopropyl group, and a t-butyl group. Examples of N-substituted (meth) acrylamides include N, N-dimethyl (meth) acrylamide, N-
Isopropyl (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-isopropyl (meth) acrylamide and N
-T-butyl (meth) acrylamide. Among these, N, N-dimethylacrylamide is preferred in terms of copolymerizability and chain transfer.

(C) The amount of the N-substituted (meth) acrylamides represented by the general formula (1) is usually 0.1 to 0.1% of the total moles of the monomers constituting the ionic polyacrylamide (A). About 1 to 10 mol%, preferably 0.5
-10 mol%, more preferably 0.5-5 mol%.

In order to impart hydrophobicity to (A) the ionic polyacrylamide, an alkyl ester of the above-described anionic vinyl monomer (having an alkyl group having 1 to 1 carbon atoms).
8) Nonionic vinyl monomers such as acrylonitrile, styrenes, vinyl acetate, and methyl vinyl ether can also be used. When a nonionic vinyl monomer is used, the amount of the nonionic vinyl monomer is usually based on the total molar amount of the monomers constituting the ionic polyacrylamide (A).
It is about 30 mol% or less, preferably 20 mol% or less.

The synthesis of (A) the ionic polyacrylamide can be carried out by various conventionally known methods. For example, the desired water-soluble (A) ionic polyacrylamide can be obtained by charging the above various monomers and water into a predetermined reaction vessel, adding a radical polymerization initiator, and heating under stirring. The reaction temperature is usually 50 to 1
The reaction time is about 00 ° C. and the reaction time is about 1 to 5 hours. The reaction concentration (monomer concentration) can be usually performed at about 10 to 40% by weight, and polymerization can be performed even at a high concentration. The obtained aqueous solution of ionic polyacrylamide can be used and stored without dilution even in the case of high concentration. In addition, the monomer can be charged by various conventionally known methods such as simultaneous polymerization and continuous drop polymerization. As the radical polymerization initiator, a normal radical polymerization initiator such as a persulfate such as potassium persulfate or ammonium persulfate, or a redox polymerization initiator in the form of a combination thereof with a reducing agent such as sodium bisulfite is used. it can. Further, an azo-based initiator may be used as the radical polymerization initiator. The amount of the radical polymerization initiator used is about 0.05 to 2.0% by weight, preferably 0.1 to 0.5% by weight of the total weight of the monomers. The Mannich modification, the Hoffman reaction, and the like are performed by known means after producing polyacrylamide or anionic polyacrylamide.

(A) The weight average molecular weight of the ionic polyacrylamide ranges from 300,000 to 4 in consideration of workability and economy.
One million. Preferably, it is 1,000,000 to 4,000,000. If the weight average molecular weight is less than 500,000, the drainage and paper strength effects are insufficient. On the other hand, if the weight average molecular weight exceeds 4,000,000, it is not preferable from the viewpoint of workability. The viscosity of (A) the ionic polyacrylamide is usually 100 from the viewpoint of handleability.
It is preferable to use it with a property of about 00 cps or less (25 ° C.). The papermaking additive of the present invention has a solid concentration of 10 to 10.
It is adjusted to 40% by weight. Even when the solid content concentration is 40% by weight, the viscosity is about 10,000 cps (25%).
° C) or lower. Normally, the solid content concentration is preferably set to 30% by weight or less. Such (A) of the present invention
Ionic polyacrylamide, despite its high molecular weight, has low viscosity and can be used at high solids concentrations.

On the other hand, the (B) ionic polyacrylamide used in the present invention is, for example, (a) (meth) acrylamide and an equivalent ratio of an ionic functional group (anionic group / cationic group) of 0 to less than 1. (B) is obtained by copolymerizing an ionic vinyl monomer having the following range:

(A) The (meth) acrylamide is the same as described above, and the amount of the (meth) acrylamide used is usually 3 moles based on the total molar amount of the monomers constituting the (B) ionic polyacrylamide.
It is about 0-99 mol%, preferably 30-97 mol%, more preferably 40-97 mol%. When the amount of the component (a) is less than 30 mol%, it is difficult to obtain a sufficient paper strength effect as a papermaking additive.

(B) The same ionic vinyl monomer can be used as described above. The amount of the (b) ionic vinyl monomer (total of anionic vinyl monomer and cationic vinyl monomer) used is usually based on the total mole sum of the monomers constituting (B) the ionic polyacrylamide.
It is about 1 to 70 mol%, preferably 3 to 70 mol%, more preferably 3 to 60 mol%. However, (b) the ionic vinyl monomer is used in such a ratio that the equivalent ratio (anionic group / cationic group) of the ionic functional group in the (B) ionic polyacrylamide becomes 0 to less than 1. That is, (B) the ionic polyacrylamide of the present invention is a cationic polyacrylamide using only a cationic vinyl monomer as the ionic vinyl monomer, or an anionic vinyl monomer and a cation having a relatively large number of cationic groups. It is a cation-rich amphoteric polyacrylamide using a hydrophilic vinyl monomer. In particular, the ionic vinyl monomer used for (B) the ionic polyacrylamide is preferably used in such a ratio that the equivalent ratio of the ionic functional group (anionic group / cationic group) is in the range of 0 to 0.8. .

The means for imparting a cationic group to the ionic polyacrylamide (B) can be obtained by copolymerizing a cationic vinyl monomer as described above.
Cationic groups can be introduced by Mannich modification in which polyacrylamide or anionic polyacrylamide is reacted with formalin and a secondary amine, or by Hoffmann reaction in which hypohalite is reacted. Even when introducing a cationic group by such modification,
(B) The amount of the ionic vinyl monomer containing the cationic monomer unit based on the Mannich modification or the like in the ionic polyacrylamide and the range of the equivalent ratio of the ionic functional group (anionic group / cationic group) are the same as described above. It is.

In the above, when the equivalent ratio of the ionic functional group (anionic group / cationic group) is not in the above range,
Since the obtained ionic polyacrylamide becomes an anion-rich polymer, even if the aqueous mixture with the above-mentioned (A) ionic polyacrylamide is prepared, the effect as a papermaking additive which is the main object of the present invention is not exhibited. .

As the ionic polyacrylamide (B), a linear polymer obtained by copolymerizing the above-mentioned monomer can be used. In addition to the above-mentioned monomer, the ionic polyacrylamide further comprises an N-ion represented by the above-mentioned general formula (1). Those obtained by copolymerizing substituted (meth) acrylamides or the above-mentioned nonionic vinyl monomers, and those obtained by copolymerizing polyfunctional monomers can also be used. The amounts of the N-substituted (meth) acrylamides represented by the general formula (1) and the nonionic vinyl monomer are the same as those described above, and the amount of the polyfunctional monomer is the same as that of the general formula (1). It is the same as the N-substituted (meth) acrylamides represented. As the polyfunctional monomer, di (meth) acrylates such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, and triethylene glycol di (meth) acrylate, methylenebis (meth) acrylamide, ethylenebis ( Bis (meth) acrylamides such as meth) acrylamide and hexamethylenebis (meth) acrylamide, divinyl esters such as divinyl adipate and divinyl sebacate, allyl methacrylate, diallylamine, diallyldimethylammonium, diallyl phthalate, diallyl chlorendate, Bifunctional vinyl monomers such as divinylbenzene, N, N-diallylacrylamide, 1,3,5-triacryloylhexahydro-S-triazine, triallylisocyanur Chromatography, triallyl amine, trifunctional vinyl monomers such as triallyl trimellitate, tetra methylol methane tetraacrylate, tetraallyl pyromellitate,
Examples include tetrafunctional vinyl monomers such as N, N, N ', N'-tetraallyl-1,4-diaminobutane, tetraallylamine salt, tetraallyloxyethane, and N-methylolacrylamide. Among these polyfunctional monomers, 1,3,5-triacryloylhexahydro-S-triazine, triallyl isocyanurate and the like are preferable.

For the synthesis of (B) the ionic polyacrylamide, the same method as in the synthesis of the (A) ionic polyacrylamide can be employed. In addition, the weight average molecular weight of (B) the ionic polyacryl is 10 in consideration of workability and economy.
10,000 to 5 million. Preferably it is 500,000 to 3,000,000. When the weight-average molecular weight is less than 100,000, the drainage and paper strength effects are insufficient. The viscosity of (B) the ionic polyacrylamide is usually 1 from the viewpoint of handleability.
It is preferable to use it under the condition of about 0000 cps (25 ° C.) or less.

The papermaking additive of the present invention is characterized in that the ratio of the specific ionic functional group is relatively large in the anionic group (A), and the ratio of the ionic polyacrylamide to the ionic functional group is relatively the cationic group. An aqueous mixture containing a large amount of (B) ionic polyacrylamide, which is premixed and used, does not reduce workability, and has the effect as a papermaking additive such as drainage and paper strength. Can be improved. Such an effect cannot be obtained when only one of these is used or when both are separately added to the pulp slurry. Although the reason is not clear, the use of a branched polymer as the (A) ionic polyacrylamide improves the fixability to pulp, and (A) the ionic polyacrylamide and (B) the ionic polyacrylamide. By pre-mixing polyacrylamide,
It is probable that both of them caused some interaction and exhibited higher drainage and paper strength effects.

The preparation of the aqueous mixture containing (A) the ionic polyacrylamide and (B) the ionic polyacrylamide is carried out by previously mixing them. If necessary, it may be appropriately diluted with water, alcohols or the like. The mixing may be performed immediately before the addition to the papermaking system, or the separately mixed one may be added to the papermaking system. In addition, the prepared aqueous mixture may be used as it is in the distribution process.

The mixing ratio of (A) the ionic polyacrylamide and (B) the ionic polyacrylamide can be selected from a wide range, and usually, (A) /
(B) is 95/5 to 5/95, preferably 90/10
It is better to be in the range of 30/70.

The papermaking additive comprising the aqueous mixture is as follows:
It is added to the pulp slurry and paper-made to produce paper according to the usual method of use. The preferred timing of the addition is after the addition of the sulfuric acid band to the pulp slurry, and it is more preferable to add the sulfuric acid band at some time after the addition of the sulfuric acid band.
In addition, since it is desirable to form the paper immediately without applying unnecessary shear to the generated floc, it is preferable to add the floc at a location close to the papermaking wire portion. In particular, the addition at the fan pump suction port is preferable because the drainage and paper strength are improved. Pulp slurry pH
Can be selected from a wide range of 4.5 to 7.0.

The amount of the papermaking additive to be used may be the same as usual, and is 0.005 to 3 in terms of solids weight ratio to pulp.
% By weight, preferably about 0.01 to 1% by weight. The sulfate band is usually 0.5 to 10% by weight based on the pulp solid content.

[0033]

Industrial Applicability The papermaking additive of the present invention is excellent in various effects as a papermaking additive such as drainage and paper strength, has a wide range of papermaking pH, and is excellent in operability.

[0034]

The present invention will be described below in detail with reference to examples and comparative examples, but the present invention is not limited to these examples. In each example, all parts and percentages are by weight unless otherwise specified.

Production Example 1 271.5 powdered acrylamide was placed in a four-necked flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube.
Parts (83 mol% based on the total moles of monomers, the same applies hereinafter), 9.7 parts of 62.5% sulfuric acid, 21.7 parts (3 mol%) of dimethylaminoethyl methacrylate, 42.6 of 80% aqueous acrylic acid solution Parts (10 mol%), 14.6 parts (2 mol%) of sodium methallyl sulfonate, 9.1 parts (2 mol%) of dimethylacrylamide and 13 parts of ion-exchanged water
Then, 00 parts (monomer concentration: 21%) were charged, and oxygen in the reaction system was removed through nitrogen gas. The temperature in the system was adjusted to 40 ° C., and while stirring, 0.35 part of ammonium persulfate and 0.15 part of sodium bisulfite were charged as a polymerization initiator. 90 ° C
Then, the temperature was kept for 2 hours. After completion of the polymerization, 110 parts of ion-exchanged water (adjusted to a solid content concentration of 20%) was added,
pH 4.1, solid content 20.1%, viscosity (25 ° C) 85
A copolymer aqueous solution having a weight average molecular weight of 2.8 million was obtained at 00 cps. Hereinafter, this aqueous solution is referred to as “A-1”. The weight-average molecular weight is measured by a low angle light scattering method (GPC).
PH 4.2 by LALLS (manufactured by Tosoh Corporation)
Using an aqueous solution containing acetic acid and sodium acetate as a moving bed,
It was measured at a sample concentration of 0.0125%.

Production Example 2 283.6 powdered acrylamide was placed in a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube.
Parts (87.5 mol%, based on the total moles of monomers, the same applies hereinafter), 6.4 parts of 62.5% sulfuric acid, 14.3 parts (2 mol%) of dimethylaminoethyl methacrylate, 16% aqueous solution of acrylic acid 16 0.4 parts (4 mol%) itaconic acid
9 parts (2 mol%), sodium methallyl sulfonate 18 parts (2.5 mol%), dimethylacrylamide 9 parts (2 mol%), and ion-exchanged water 1300 parts (monomer concentration 2
1%), and oxygen in the reaction system was removed through nitrogen gas. The temperature of the system was adjusted to 40 ° C., and 0.49 part of ammonium persulfate and 0.2 part of sodium hydrogen sulfite were added as a polymerization initiator with stirring. After the temperature was raised to 90 ° C., the temperature was kept for 2 hours. After the completion of the polymerization, 110 parts of ion-exchanged water (adjusted to a solid content of 20%) was added, and the pH was 3.9 and the solid content was 20.
A 1% aqueous solution of the copolymer having a viscosity (25 ° C.) of 7100 cps and a weight average molecular weight of 3,000,000 was obtained. Hereinafter, this aqueous solution is referred to as “A-2”.

Production Example 3 Powdered acrylamide 291.2 was placed in a four-necked flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube.
Parts (86 mol%, based on the total moles of monomers, the same applies hereinafter), 42.9 parts (10 mol%) of an 80% aqueous solution of acrylic acid, 15.1 parts (2 mol%) of sodium methallyl sulfonate, dimethylacrylamide 9.4 parts (2 mol%) and 1300 parts of ion-exchanged water (monomer concentration: 21%) were charged, and oxygen in the reaction system was removed through nitrogen gas. The temperature of the system was adjusted to 40 ° C., and while stirring, 0.35 parts of ammonium persulfate and 0.15% of sodium bisulfite were used as polymerization initiators.
Part. After the temperature was raised to 90 ° C., the temperature was kept for 2 hours. After completion of the polymerization, 80 parts of ion-exchanged water (solids concentration 20
%), PH 4.0, solid content 20.2%,
The viscosity (25 ° C.) is 9800 cps and the weight average molecular weight is 2
900,000 aqueous copolymer solutions were obtained. Hereinafter, this aqueous solution is referred to as “A-3”.

Production Example 4 A four-necked flask equipped with a stirrer, thermometer, reflux condenser and nitrogen gas inlet tube was charged with 162 parts of 50% acrylamide (95 mol%, based on the total mol of monomers, the same hereinafter). 5.4 parts (5 mol%) of an 80% aqueous solution of acrylic acid,
Charge 737 parts of ion-exchanged water and 2.5 parts of isopropyl alcohol, and adjust the pH to 5 with 48% sodium hydroxide.
It was adjusted to 5.5 and oxygen in the reaction system was removed through nitrogen gas. After 2.6 parts of a 5% aqueous ammonium persulfate solution and 1.1 parts of a 5% aqueous sodium bisulfite solution were added as a polymerization initiator under stirring, the temperature was raised from room temperature to 80 ° C.
It was kept warm for 3 hours. After cooling this to 50 ° C, 50%
25.9 parts of dimethylamine aqueous solution and 37% formalin 1
9.5 parts (20 mol% of 95 mol% of acrylamide denatured by Mannich) are sequentially added, and the mixture is kept at the same temperature for 1 hour, pH 10.8, solid content 10.5%, viscosity (25 ° C.)
Of 5300 cps and an aqueous solution of an amphoteric Mannich-modified copolymer having a weight average molecular weight of 1,000,000. Hereinafter, this aqueous solution is referred to as “B-1”.

Production Example 5 In a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube, 75.8 parts of powdered acrylamide (85 mol% based on the total mol of monomers, hereinafter the same) ), 5 parts of 62.5% sulfuric acid, 19.7 parts (10 mol%) of dimethylaminoethyl methacrylate, 5.6 parts (5 mol%) of an 80% aqueous solution of acrylic acid, and 56 parts of ion-exchanged water.
Five parts were charged, and oxygen in the system was removed through nitrogen gas. The temperature in the system is brought to 50 ° C, and 5%
After adding 2.5 parts of an aqueous ammonium persulfate solution and 1.1 parts of a 5% aqueous sodium bisulfite solution, the mixture
The temperature was raised to 0 ° C. and kept for 3 hours. Thereafter, 333 parts of ion-exchanged water was added, the pH was 4.4, the solid content was 10.0%, the viscosity (25 ° C.) was 6300 cps, and the weight average molecular weight was 11
There were obtained 100,000 amphoteric copolymer aqueous solutions. Hereinafter, this aqueous solution is referred to as “B-2”.

Production Example 6 A 50% acrylamide 240 was placed in a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube.
And 357 parts of ion-exchanged water, and oxygen in the reaction system was removed through nitrogen gas. After the temperature of the system was raised to 35 ° C., 6.8 parts of a 5% aqueous ammonium persulfate solution and 2.8 parts of a 5% aqueous sodium bisulfite solution were used as polymerization initiators.
Then, the temperature was raised from room temperature to 80 ° C., and the temperature was kept for 3 hours. Thereafter, 397 parts of ion-exchanged water was added, and a solid content of 1
A polymer having a viscosity of 3.0% and a viscosity (25 ° C.) of 4300 cps was obtained.

Next, 670 parts of the above polymer was charged into a four-necked flask equipped with a stirrer, a thermometer, and a reflux condenser.
126 parts of sodium hypochlorite of 12.5% of active ingredient and 24
A mixed aqueous solution of 19 parts of sodium hydroxide was added. Then, the reaction was completed at 25 ° C. for 1 hour.
7.7 parts of an aqueous solution, adjusted to pH 4.5 with hydrochloric acid, and added with water to give a solid content of 13% and a viscosity of 1400 cps
(25 ° C.), an amphoteric polymer having a weight average molecular weight of 70 (12.5 mol% of the Hoffman transition product of polyacrylamide based on the total mol of the monomers, and 3 mol% by hydrolysis)
An aqueous solution of the following carboxylic acid) was obtained. Hereinafter, this aqueous solution is referred to as “B-3”.

Production Example 7 Powdered acrylamide 219.8 was placed in a four-necked flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube.
62.5% sulfuric acid, 68.2% sulfuric acid, 58.2 parts dimethylaminoethyl methacrylate (10 mol%), 80%
13.4 parts (4 mol%) of an aqueous solution of acrylic acid, 5.9 parts (1 mol%) of sodium methallyl sulfonate, 5.5 parts (1.5 mol%) of dimethylacrylamide, and 1540 parts of ion-exchanged water (monomer (Concentration: 16%), and oxygen in the reaction system was removed through nitrogen gas. The temperature of the system was adjusted to 40 ° C., and ammonium persulfate (0.3%) was used as a polymerization initiator with stirring.
6 parts and 0.15 part of sodium bisulfite were charged. After the temperature was raised to 90 ° C., the temperature was kept for 2 hours. After polymerization is completed, 240 parts of ion-exchanged water (adjusted to a solid concentration of 15%)
, PH 4.8, solid content 15.1%, viscosity (25
C.) and an aqueous solution of a copolymer having a weight average molecular weight of 2.6 million. Hereinafter, this aqueous solution is referred to as “B-4”.
And

Comparative Production Example 1 In a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas inlet tube, 128 parts of powdered acrylamide (90 mol% based on the total mol of monomers, the same hereinafter) , 18 parts of an 80% acrylic acid aqueous solution (10 mol%),
Charge 440 parts of ion-exchanged water and 4 parts of isopropyl alcohol, and adjust the pH to 5 to 5.5 with 48% sodium hydroxide.
, And oxygen in the reaction system was removed with nitrogen gas. Next, 11 parts of a 5% aqueous solution of ammonium persulfate and 4.5 parts of 5% sodium bisulfite were added as a polymerization initiator under stirring, and then the temperature was raised from room temperature to 80 ° C., and kept for 3 hours. Thereafter, 230 parts of ion-exchanged water was added, and
0, solid content 15.2%, viscosity (25 ° C) 5500 cp
Thus, an aqueous solution of the anionic copolymer s was obtained. Hereinafter, this aqueous solution is referred to as “C-1”.

Example 1 A cardboard waste paper was beaten with a Niagara beater, and Canadian Standard Freeness (CSF) 4 was used.
Sulfuric acid band (A) was added to the pulp slurry adjusted to 00 ml.
lum) was added at a ratio of 1.5% to the pulp solid content, and pH5.
The polymer mixture shown in Table 1 was then added (0.4% solids to pulp ratio). The pulp slurry thus obtained is weighed 150 g with a tappy sheet machine.
/ M ² and press dewatered at 4 kg / cm ² for 4 minutes. Then, it is dried at 105 ° C. for 3 minutes in a rotary dryer, and is dried at 20 ° C. and 65% R.C. H. 24 under the conditions of
After humidifying for time, JIS P8121, JIS P8
According to 131, drainage and burst strength were measured. Further, in order to confirm formation, light transmitted through the sheet is converted into luminance, and the OBS image processing system Hyper700 is used.
(Manufactured by OBS) and statistically analyzed the luminance. Table 1 shows the results.

[0045]

[Table 1]

The polymer mixtures in Table 1 were prepared by previously mixing diluents (1% in this case) of each polymer. The coefficient of variation in Table 1 indicates the degree of variation in luminance (the difference in the density of the pulp fibers in the sheet). Based on the data obtained by the above-described formation measurement method,
(Formula): Value calculated by deviation / average luminance × 100,
The smaller the numerical value, the better the formation can be determined (hereinafter the same).

Example 2 L-UKP was beaten with a Niagara beater, and (C.
S. F) Al is added to the pulp slurry adjusted to 500 ml.
um to pulp solid content ratio 1% (pH 6.2) or 2%
(PH 5.2) and then the polymer mixture described in Table 2 (0.2% or 0.4% pulp solids ratio). The same operation as in Example 1 was performed on the pulp slurry thus obtained, and drainage, burst strength, and formation were measured. Table 2 shows the results.

[0048]

[Table 2]

Claims (6)

[Claims] (A) General formula (1): CH ₂ ＣC (R
¹ ) -CONR ² (R ³ ) (R ¹ is a hydrogen atom or a methyl group, R ² is a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, and R ³ is a straight chain having 1 to 4 carbon atoms. An ionic polyacrylamide containing, as a constituent monomer, an N-substituted (meth) acrylamide represented by a chain or a branched chain alkyl group, wherein the equivalent ratio of the ionic functional group (cationic group / anionic group) is (B) an ionic polyacrylamide having a weight average molecular weight of 300,000 to 4,000,000 and an equivalent ratio of ionic functional groups (anionic group / cationic group) A papermaking additive comprising an aqueous mixture containing an ionic polyacrylamide having a weight average molecular weight of 100,000 to 5,000,000 in a range of 0 to less than 1. 2. (A) Equivalent ratio of ionic functional groups of ionic polyacrylamide (cationic group / anionic group)
Is in the range of 0 to 0.8. 3. The method according to claim 1, wherein (A) the ionic polyacrylamide is
3. The papermaking additive according to claim 1, which comprises (meth) allylsulfonic acid or a salt thereof as an anionic component. 4. The equivalent ratio of the ionic functional group of the ionic polyacrylamide (B) (anionic group / cationic group)
Is in the range of 0 to 0.8. 5. The method of claim 1, wherein (B) the ionic polyacrylamide is
General formula (1): CH ₂ ＣC (R ¹ ) -CONR ²
(R ³ ) (R ¹ is a hydrogen atom or a methyl group, R ² is a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, and R ³ is a linear or branched alkyl group having 1 to 4 carbon atoms. 5. The papermaking additive according to claim 1, which comprises an N-substituted (meth) acrylamide represented by the formula (1) and / or a polyfunctional monomer. 6. A method for producing paper, comprising adding the papermaking additive according to any one of claims 1 to 5 to a pulp slurry having a pH of 4.5 to 7.0 to form a paper.