WO2000060168A1

WO2000060168A1 - Binder for papermaking, method of papermaking, and paper

Info

Publication number: WO2000060168A1
Application number: PCT/JP2000/002150
Authority: WO
Inventors: Shigeru Tanabe; Youji Wada; Takanori Nakazato
Original assignee: Dia-Nitrix Co., Ltd.
Priority date: 1999-04-02
Filing date: 2000-04-03
Publication date: 2000-10-12
Also published as: JP2000290892A; JP3452505B2; KR20020011378A; CN1345391A

Abstract

A binder for papermaking which comprises a copolymer comprising (meth)acrylamide monomer units and N-vinylcarboxamide monomer units. The binder can impart dispersibility to stock fibers without causing flocculation even when used simultaneously with a cationic chemical. Thus, paper having a satisfactory formation and an excellent texture can be efficiently formed stably.

Description

Specification

Papermaking adhesive, papermaking method and paper

The present invention relates to a papermaking adhesive, a papermaking method, and a papermaking method for imparting dispersibility to raw material stock fibers and producing stable papermaking when manufacturing Japanese paper, tissue paper, toilet paper, paperboard, and the like. About paper.

This application is based on a patent application to Japan (Japanese Patent Application No. 11-197509), and the contents of the Japanese application are incorporated herein as a part. Background art

2. Description of the Related Art When making paper such as Japanese paper, tissue paper, toilet paper, and paperboard, a papermaking method using a dispersing adhesive to sufficiently disperse the stock fibers in water has been used for a long time.

As the dispersant used for this dispersion, for example, natural products such as the extracted mucus of the trolloa root are known. Other examples include polyethylene oxide, polyacrylamide, a copolymer of acrylamide and acrylate (Japanese Patent Publication No. 57-12038), and a copolymer of acrylamide and 2-acrylamide-2-methylpropanesulfonic acid salt. Compounds such as coalescence (Japanese Patent Publication No. Sho 56-47997) and blends thereof (Japanese Patent Publication No. Sho 52-1981) are known.

The natural product Troroaoi has few drawbacks such as unstable price, easy deterioration and poor quality stability, and it is hardly used industrially at present.

Polyacrylamide is produced by polymerizing acrylamide. When acrylamide is polymerized, part of acrylamide is hydrolyzed to generate carboxyl groups. Therefore, polyacrylamide contains a carboxyl group. However, since the carboxyl group is an anionic group, if polyacrylamide having a carboxyl group is used together with a cationic wet strength agent, a sizing agent, a dye, or a facial agent, the paper fiber will aggregate. As a result, papermaking may not be possible. Also, even if papermaking is possible, the paper quality of the obtained paper becomes hard and the texture becomes poor. There are many sources. In addition, polyacrylamide has a very slow dissolution rate. As a result, the adhesive does not dissolve sufficiently and exists as a solid, which may cause trouble in the paper making process.

Also, acrylamide and acrylate copolymers and acrylamide and 2-acrylamide-2-methylpropanesulfonate copolymers are widely used because they exhibit excellent papermaking performance with a small amount of use. However, these include the anionic monomeric units acrylate and 2-acrylamido-2-methylpropanesulfonate. For this reason, if chemical agents such as cationic wet strength agents, softeners, sizing agents, dyes, and pigments are used in combination, the paper fibers often aggregate and cannot be made.

As described above, the conventional polyacrylamide-based papermaking adhesives often cannot be used in combination with agents such as cationic wet paper strength agents and sizing agents.

On the other hand, even when nonionic polyethylene oxide is used in combination with an agent such as a cationic wet paper strength agent during papermaking, the paper fiber hardly aggregates. However, polyethylene oxide foams during papermaking, so it is necessary to add an antifoaming agent to suppress foaming. In addition, since the viscosity of polyethylene oxide significantly decreases depending on the water temperature and dissolution conditions, stable papermaking is not easy. In addition, polyethenoxide is expensive.

A papermaking method using a blend of polyethylene oxide and polyacrylamide as a papermaking adhesive has also been proposed. However, when this blend is used in combination with a chemical agent such as a force-wetting agent such as a wet strength agent, a sizing agent, a dye, or a pigment, paper fibers may coagulate as in the case of using polyacrylamide. is there. SUMMARY OF THE INVENTION An object of the present invention is to provide a papermaking adhesive which can impart dispersibility to paper fibers without coagulation of the paper fibers even when used simultaneously with a cationic agent. It is an object of the present invention to efficiently and stably produce waste paper. Disclosure of the invention

The present invention is a papermaking adhesive comprising a copolymer containing (meth) acrylamide monomer units and N-vinylcarboxylic acid amide monomer units. Using the papermaking adhesive of the present invention In this case, even when used in combination with a cationic agent, the dispersibility of the stock fiber is good and stable papermaking can be performed. And a paper with good texture and texture can be obtained. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail.

The papermaking adhesive of the present invention comprises a copolymer containing (meth) acrylamide monomer units and N-vinylcarbonamide monomer units.

Usually, a homopolymer of N-vinylcarboxylic acid amide has a low molecular weight and a low viscosity, so that it is difficult to use it as a papermaking adhesive. However, the copolymer of N-vinyl carboxylic acid amide and (meth) acrylamide has a high molecular weight and has the viscosity required for a papermaking adhesive.

That is, the (meth) acrylamide is for increasing the molecular weight of the copolymer and increasing the viscosity of the copolymer.

On the other hand, the N-vinylcarboxylic acid amide monomer unit imparts a high stock fiber dispersibility to a copolymer as a papermaking adhesive. A copolymer of (meth) acrylamide and N-vinylcarboxylic acid amide is less likely to be hydrolyzed than a (meth) acrylamide homopolymer. For this reason, even if this copolymer is used in combination with a cationic drug, it is considered that the stock fibers hardly aggregate.

Examples of such an N-vinylcarboxylic acid amide monomer include N-vinylacetamide, N-methyl-N-vinylacetamide, N-vinylformamide, N-methyl-N-vinylformamide and the like. Of these, N-vinylacetamide is preferred. One of these N-vinylcarboxylic acid amide monomer units constituting the copolymer may be used alone, or two or more thereof may be used together.

In addition to the (meth) acrylamide monomer unit and the N-vinylcarboxylic acid amide monomer unit, the copolymer as the papermaking adhesive of the present invention further comprises a nonionic monomer unit and a nonionic monomer. There is no particular limitation as long as it is copolymerizable with (meth) acrylamide monomer and N-vinylcarbonamide monomer and is soluble in the polymerization system. „

Absent. Such nonionic monomers include, for example, (meth) ac

(Meth) acrylic esters such as ethyl (meth) acrylate, (meth) acrylamide derivatives such as N-methyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, vinyl acetate, aryl Alcohol and the like. Of these, N, N-dimethyl (meth) acrylamide is preferred. These nonionic monomer units to be introduced into the copolymer may be used alone or in combination of two or more.

The proportion of the (meth) acrylamide monomer unit in the copolymer is preferably 30 to 98% by weight, particularly preferably 50 to 95% by weight, and further preferably 60 to 90% by weight. is there. When the proportion of (meth) acrylamide monomer units in the copolymer increases, the molecular weight of the copolymer generally tends to increase and the viscosity tends to increase. On the other hand, a copolymer containing a low proportion of (meth) acrylamide monomer units is used as a papermaking adhesive, a paper stock containing a large amount of a cationic wet paper strength enhancer, or a stock stock containing a sizing agent. When used in combination, the dispersibility of the stock fiber tends to be improved.

The proportion of the N-vinylcarboxylic acid amide monomer unit in the copolymer is preferably 2 to 70% by weight, particularly preferably 5 to 50% by weight, and more preferably 10 to 40% by weight. is there. Use a copolymer with a high proportion of N-vinylcarboxylic acid amide monomer units as a papermaking adhesive, a paper stock containing a large amount of cationic wet paper strength enhancer, or a stock stock containing a sizing agent. When used together, the dispersibility of the stock fiber tends to be improved. In addition, when the proportion of the N-pinylcarboxylic acid amide monomer unit in the copolymer decreases, the molecular weight of the copolymer generally increases and the viscosity tends to increase. Furthermore, the production cost of the copolymer is reduced because the amount of the expensive N-vinylcarboxylic acid amide monomer used is reduced, so that a papermaking adhesive can be produced at low cost.

The nonionic monomer unit can be introduced in the copolymer in an amount of 0 to 40% by weight.

The polymerization method for producing the copolymer as the papermaking adhesive of the present invention is not particularly limited. For example, it can be produced by an aqueous solution polymerization method, a reverse phase emulsion polymerization method, a suspension polymerization method, or the like. Further, it may be produced by a known photopolymerization method (Japanese Patent Application Laid-Open No. Hei 9-59309). During the polymerization, it is possible to use a polymerization initiator and various additives as necessary. it can.

As the polymerization initiator, a redox initiator, a photopolymerization initiator, or the like can be used. The redox initiator is obtained by combining an azo compound or an organic peroxide with a sulfite, a sulfite, a thiosulfate, sodium formaldehyde sulfoxylate, glucose, or the like. Examples of the azo compound include azobisisobutyronitrile, azobisisovaleronitrile, 2,2-azobis (2-amidinop mouth pan) dihydride mouth chloride, and the like. Examples of the organic peroxides include persulfate, t-butylhydroxide peroxide, cumenehydride peroxide, benzoyl peroxide, lauroyl peroxide, and the like. Examples of the photopolymerization initiator include benzoin, benzoinethyl ether, and benzophenone.

The copolymer obtained after the completion of the polymerization reaction is usually used in the form of a powder as a papermaking adhesive. The method of pulverizing the copolymer is not particularly limited.For example, when the copolymer is produced by aqueous solution polymerization, the obtained copolymer is shredded, dried with a hot-air dryer or the like, and then, The powder can be further pulverized by a pulverizer or the like to obtain a powder. When a copolymer as the papermaking adhesive of the present invention is used during papermaking, the copolymer may be used alone or may be used in combination with other papermaking adhesives. Good. When used in combination with other papermaking adhesives, the ratio of the papermaking adhesive comprising the copolymer of the present invention to the total amount of the papermaking adhesive is preferably 15% by weight or more. . Particularly preferably, it is at least 40% by weight. A papermaking adhesive containing 15% by weight or more of the papermaking adhesive of the present invention has the same effect as when the papermaking adhesive of the present invention is used alone.

The papermaking method using the papermaking adhesive of the present invention is not particularly limited, and any known papermaking method can be used. By making the paper in this way, paper with excellent formation and texture can be produced. Example

Hereinafter, the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[Example 1] (Preparation of papermaking adhesive)

3000 g of an aqueous solution containing 22.8% by weight of acrylamide and 1.2% by weight of N-vinylacetamide was put into a 5-liter bottle, and the temperature was adjusted to 5 ° C by purging with nitrogen gas. Then, as a polymerization initiator, 2,2-azobis (2-amidinopropane) dihydride chloride at 150 ppm, t-butylhydride peroxide at 8 ppm, and sodium bisulfite at 80 ppm. In addition, adiabatic polymerization was performed.

The obtained gel was chopped with a meat grinder and dried at 60 ° C. to obtain pellets. The pellets were pulverized with a pulverizer to form a powdery polymer, and a papermaking adhesive comprising 95% by weight of an acrylamide monomer unit and 5% by weight of an N-vinylacetamide monomer unit was obtained. Was.

The obtained powdery papermaking adhesive was dissolved in ion-exchanged water to obtain a 0.1% by weight aqueous solution of papermaking adhesive.

Separately, the powdery papermaking adhesive obtained above was dissolved in ion-exchanged water to obtain a 1% by weight aqueous solution of papermaking adhesive, and the viscosity of the solution was measured. The results are shown in Table 1.

(Preparation of stock slurry)

A 0.2% by weight pulp slurry was prepared using NBKP having a beating degree of 650 mICSF (Canadian standard freeness) as a stock. Further, as an additive agent, 0.2% by weight of a cationic amine wet strength agent, polyamidoamine / epichlorhydrin, was added to the pulp, and the mixture was sufficiently stirred to obtain a pulp slurry.

[Measurement of various characteristics]

To the pulp slurry, the above 0.1% by weight aqueous solution of papermaking adhesive was added so as to be 2 ppm as a pure component of the papermaking adhesive, followed by stirring and mixing to obtain a slurry solution. . Then, the stock solution coagulation property and stock setting property of the slurry solution were measured. The results are shown in Table 1.

[Evaluation of paper formation and texture]

The pulp slurry containing the above papermaking adhesive at 2 Dpm was made into a paper made by a circular net Yankee type paper machine to evaluate the formation and texture. Each performance evaluation method is shown below.

(Viscosity)

It was measured at 25 ° C with a B-type viscometer. The rotor used was No. 2 and the rotation speed was 6 rpm.

(Paper cohesion)

The state of the stock when the slurry solution was stirred with a jar tester was visually determined. The evaluation criteria are shown below.

:: There is no cohesion, and it can be used without any problem.

〇: Slightly aggregates, but can be used without any problem.

Δ: There is a possibility that a little coagulation occurs and formation of the paper-made product is disturbed.

X: Agglomerated, papermaking not possible.

(Paper stock sedimentation)

After injecting 500 ml of the slurry solution into a commercially available 500 ml measuring cylinder (inner diameter 50 mm), the time t (second) required for the stock interface to settle to 100 ml was determined. Separately from this, the stock sedimentation time t "(second) of the pulp slurry to which no papermaking adhesive was added was determined, and the stock sedimentation property D was calculated from t and t by the following formula.

D = t Z t »X 1 00

Paper settling property D is an index that indicates papermaking performance. The larger D is, the better the papermaking performance is.

[Paper formation]

It was determined visually by using a paper tissue base one per order of the paper with basis weight 13. O gZm ² (about 20 CMX 20 cm) by circular network Yankee type paper machine. The evaluation criteria are shown below. '

A: Uniform and excellent.

〇: Good.

Δ: Non-uniform.

X: Poor and papermaking impossible.

[Texture of paper]

Tactile sensation was determined using the same paper as for the formation evaluation. The evaluation criteria are shown below. A: Soft and tactile.

〇: Slightly hard, but no problem as a product.

Δ: Hard and unusable as a product.

X: There is a hard and stiff feeling.

[Examples 2 to 7 and Comparative Examples 1 to 2]

Example 1 except that the acrylamide monomer unit and the N-vinylacetamide monomer unit were in the proportions shown in Table 1, and the addition amounts of t-butyl hydroperoxide and sodium bisulfite were in the concentrations shown in Table 1. In the same manner as in 1, a papermaking adhesive was prepared. The viscosity of the papermaking adhesive, the stock cohesion of the slurry solution, the stock sedimentation property, the formation of the paper, and the texture were evaluated in the same manner as in Example 1. The results are shown in Table 1. table 1

As shown in Table 1, a papermaking adhesive consisting of a copolymer containing acrylamide monomer units and N-vinylcarboxylic acid amide monomer units can be used simultaneously with the cationic wet paper strength enhancer. The paper stock cohesion was small, and the stock sedimentation property D was large, showing excellent performance as a papermaking adhesive. In addition, paper obtained by papermaking Was excellent.

Further, a papermaking adhesive comprising a copolymer having 2 to 70% by weight of an N-vinylcarboxylic acid amide monomer unit showed particularly excellent performance.

[Examples 8 to 9]

Acrylamide and N-vinylacetamide were used in the proportions shown in Table 2, and N, N-dimethylacrylamide was used as a nonionic monomer copolymerizable with them in the proportions shown in Table 2. Examples 1 and 2 except that 2,2-azobis (2-amidinopropane) dihydride chloride was used as a polymerization initiator at 150 ppm, t-butyl hydride peroxide was 5 ppm, and sodium hydrogen sulfite was 50 ppm. Similarly, a papermaking adhesive was prepared.

The viscosity of the papermaking adhesive, the stock cohesion of the slurry solution, and the stock sedimentation property were evaluated in the same manner as in Example 1. The results are shown in Table 2.

[Example 10]

A papermaking adhesive was prepared in the same manner as in Example 8, except that methyl acrylate was used instead of N, N-dimethylacrylamide. The viscosity of the papermaking adhesive, the stock cohesion of the slurry solution, and the stock settling property of the slurry solution were evaluated in the same manner as in Example 1. The results are shown in Table 2.

[Comparative Example 3]

A papermaking adhesive was prepared in the same manner as in Example 8, except that sodium acrylate was used instead of N, N-dimethylacrylamide. Using the obtained papermaking adhesive, the viscosity of the adhesive, the paper stock cohesiveness of the slurry solution, and the paper stock settling property were measured in the same manner as in Example 1. The results are shown in Table 2. Table 2

Abbreviations in the table indicate the following.

A A: Acrylamide

NVA: N-vinylacetamide

tBHP: t-butyl hydroperoxide

SHS: Sodium bisulfite

DMAA: N, N-dimethylacrylamide

M A: Methyl acrylate

AaN: Sodium acrylate As shown in Table 2, those containing nonionic monomers copolymerizable with acrylamide and N-vinylcarbonamide in papermaking adhesives are cationic wet paper strength agents. Even when used at the same time, the paper stock cohesiveness was small and the stock sedimentation property D was large, showing particularly excellent performance as a papermaking adhesive.

In addition, those containing anionic sodium acrylate monomer units had a large stock agglomeration property and a small stock sedimentation property D, and were not suitable for use as a papermaking adhesive.

[Examples 11 to 13 and Comparative Example 4]

The same procedure as in Example 1 was repeated, except that the papermaking adhesive obtained in Example 2 was blended with polyethylene oxide using a ribbon mixer at the ratio shown in Table 3 as a papermaking adhesive. The viscosity of the agent, the stock cohesiveness of the slurry solution, and the stock sedimentation of the stock were measured. The results are shown in Table 3. Further, air was blown into an aqueous solution in which the papermaking adhesive was dissolved at a concentration of 0.1% by weight, and the presence or absence of foaming was visually evaluated. The results are shown in Table 3. The evaluation criteria are shown below.

〇: No problem.

Δ: Some foaming, but not enough to cause trouble.

X: Foaming was confirmed, and it was necessary to add an antifoaming agent.

X X: Foaming causes trouble unless handled with care. Table 3

The blend of papermaking adhesive and polyethylene oxide obtained in Example 2 could be used simultaneously with the cationic wet strength agent. In particular, those containing the papermaking adhesive obtained in Example 2 in a proportion of 15% by weight or more have the same viscosity, paper stock cohesiveness and viscosity as those of the papermaking adhesive obtained in Example 2 alone. The stock was sedimentable and the papermaking performance was excellent. In addition, the foaming was small and the handling was easy. Industrial applicability

As described above, the papermaking adhesive of the present invention is a papermaking adhesive comprising a copolymer containing a (meth) acrylamide monomer unit and an N-vinylcarboxylic acid amide monomer unit. When making paper such as tissue paper, toilet paper, paperboard, etc., it dissolves quickly and imparts dispersibility to paper fiber without foaming. it can. Also, even when used together with a cationic agent, it does not cause agglomeration of the stock fibers and is a very excellent papermaking adhesive.

When this papermaking adhesive is used, papermaking can be performed stably, and a paper having a good texture and excellent texture can be obtained.

Claims

The scope of the claims

1. A papermaking adhesive consisting of a copolymer containing (meth) acrylamide monomer units and N-vinylcarboxylic acid amide monomer units.

2. The papermaking adhesive according to claim 1, wherein the copolymer further contains a nonionic monomer unit.

3. The copolymer has 30 to 98% by weight of (meth) acrylamide monomer units, 2 to 70% by weight of N-vinylcarboxylic acid amide monomer units, and 30 to 90% by weight of nonionic monomer units. 2. The papermaking adhesive according to claim 1, wherein the amount is 0 to 40% by weight.

4. The papermaking adhesive according to claim 1, wherein the N-vinylcarboxylic acid amide is N-vinylacetamide.

5. The papermaking adhesive according to claim 2, wherein the N-vinylcarboxylic acid amide is N-vinylacetamide.

6. The papermaking adhesive according to claim 3, wherein the N-vinylcarboxylic acid amide is N-vinylacetamide.

7. A papermaking adhesive comprising 15% by weight or more of the papermaking adhesive according to any one of claims 1 to 6.

8. A papermaking method using the papermaking adhesive according to any one of claims 1 to 6.

9. A papermaking method comprising using the papermaking adhesive according to claim 7.

10. A paper made by the paper making method according to claim 8.

11. A paper made by the paper making method according to claim 9.