JPH10266095A - Paper surface treatment agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject agent that is excellent in sizing effect and can improve the printability and defibrillability the paper by forming a polyionic complex comprising a specific grafted starch polymer and a specific hydrophobic group-bearing anionic copolymer. SOLUTION: In an aqueous solution countering 20-80 pts.wt. of cationic starch, 20-80 pts.wt. of a monomer mixture comprising 50-98 mol% of (meth)acrylamide, 1-30 mol% of an anionic vinyl monomer such as acrylic acid and 1-20 mol% of a cationic vinyl monomer such as N,N-dialkylamino-alkyl (meth)acrylamide are polymerized as the essential components to prepare shaft starch polymer A. In the meantime, a hydrohobic vinyl monomer such as styrene and an anionic vinyl monomer such as acrylic acid are used as essential components to prepare a hydrohobic group-bearing anionic copolymer B. These copolymers A and B are used as main components to prepare a polyionic complex containing the component A and B at a ratio of 70/30-30/70 thereby giving the objective surface treatment agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper surface treating agent, and more particularly, to a paper comprising a polyion complex comprising a specific graft starch polymer and a hydrophobic group-containing anionic copolymer. Related to the surface treatment agent of, while imparting an excellent size effect on paper,
An object of the present invention is to provide a paper surface treating agent which greatly improves printability and is excellent in paper disintegration and is suitable for recycling waste paper and waste paper.

[0002]

2. Description of the Related Art As is well known, surface treatment agents for paper include:
Oxidized starch, hydroxyethyl etherified starch, thermochemically modified starch, polyvinyl alcohol, acrylamide polymer, cellulose polymer such as carboxymethyl cellulose, styrene-maleic acid copolymer, latex, vinyl acetate polymer, etc. are used. Among them, oxidized starch, polyvinyl alcohol, and acrylamide-based polymers are frequently used. However, oxidized starch and polyvinyl alcohol require a cooking step when used, and thus have problems in workability, and also have problems such as foaming and dirt during coating and starch rot. Acrylamide-based polymers have an excellent paper strength effect, and their usage tends to increase, but their use is economically restricted due to their high cost, and paper coated with acrylamide-based polymers is also used. However, there is a problem from the viewpoint of paper recycling, because the disintegration of waste paper and waste paper tends to deteriorate.

[0003]

In recent years, paper raw materials have been required to increase the mixing ratio of recycled paper due to environmental problems, to close papermaking machines due to drainage regulations, and to increase the speed of papermaking machines to improve productivity. In addition, the development of printing technology has been remarkable, and with the increase in printing speed, offset printing, water-based gravure ink, multi-color printing, diversification of printing methods and high quality, the printing suitability of paper There is a strong demand for quality improvement such as surface strength. Particularly in printability, there is a strong demand for paper of a strong size corresponding to dampening water in offset printing, and in aqueous gravure printing, there is a strong improvement in ink coloring properties of printing due to the permeability of aqueous gravure ink. Has been requested.

[0004] In order to solve the above problems, the present inventor has been able to impart excellent sizing effects to paper, greatly improve printability, and has excellent paper disintegration properties, so that waste paper and waste paper can be used. The inventors of the present invention have made the following inventions as a result of intensive studies as a technical problem of providing a paper surface treatment agent most suitable for recycling.

[0005]

That is, the present invention relates to a method for preparing a (meth) acrylamide (a ₁ ), an anionic vinyl monomer (a ₂ ) and a cationic vinyl monomer in an aqueous solution containing a cationic starch. A graft starch polymer (A) obtained by polymerizing a monomer mixture consisting of (a ₃ ) as an essential component, a hydrophobic vinyl monomer (b ₁ ) and an anionic vinyl monomer (b ₂ ) The main component is a hydrophobic group-containing anionic copolymer (B) obtained by polymerizing a monomer mixture as an essential component, and a polyion complex of the component (A) and the component (B). Characteristic paper surface treatment agent.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The cationic starch used in the graft starch polymer (A) in the present invention is one obtained by introducing a cationic group according to a conventional method for starch and / or modified starch. Specifically, corn, wheat, potato, tapioca, rice, and various starches as raw materials and etherified, denatured thereof such as etherification, oxidation, enzyme-modified starch and the like are introduced cationic groups, and these One type or two or more types may be used in combination.

[0007] The viscosity of the cationic starch used in the present invention is preferably in the range of 50 to 1000 cps (30 ° C) at a concentration of 30%.

The cationic starch is prepared by adding at least one basic nitrogen selected from primary, secondary and tertiary amino groups and quaternary ammonium groups to the starch and / or modified starch. Let it. The content of the basic nitrogen is desirably 0.1% by weight or more. Specifically, the starch and / or modified starch may be reacted with a cationizing agent formed from a reaction product of dialkylamine or trialkylamine with epichlorohydrin.

In particular, the above-mentioned various starches are degraded with an enzyme such as amylase, and the modified starch is cationized, or the starch and / or the modified starch is cationized with a cationizing agent, and the cationic starch is degraded with an enzyme such as amylase. The low viscosity prepared by the above is preferable.

The graft starch polymer (A) in the present invention
The (meth) acrylamide (a ₁ ) used for the above is acrylamide and methacrylamide, either of which may be used alone or both may be used in combination.

The graft starch polymer (A) in the present invention
Examples of the anionic vinyl monomer (a ₂ ) used for
Acrylic acid, methacrylic acid, itaconic acid, maleic anhydride, fumaric acid, vinylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, and the like, and sodium, potassium, ammonium salts thereof, and the like. They may be used alone or in combination of two or more.

The cationic vinyl monomer (a ₃ ) used in the graft starch polymer (A) of the present invention includes N.I. N
Dimethylaminoethyl (meth) acrylate, N.P. N
-Diethylaminoethyl (meth) acrylate, N.I. N
Dialkylaminoalkyl (meth) acrylates such as dimethylaminopropyl (meth) acrylate; N
Dimethylaminoethyl (meth) acrylamide, N.P.
N. dimethylaminopropyl (meth) acrylamide and the like. Vinyl monomers having a tertiary amino group such as N-dialkylamino (meth) alkylacrylamide, vinylpyridine, vinylimidazole, arylamine, diarylamine, or their hydrochloride, sulfate, formate, acetate, sulfamic acid Salts, and a vinyl monomer containing a tertiary amino group and an arylalkyl halide such as an alkyl halide such as methyl chloride;
Dimethyl sulfate, diethyl sulfate, epichlorohydrin, 3
A quaternary ammonium salt obtained by a reaction with a quaternizing agent such as -chloro-2-hydroxypropyltrimethylammonium chloride and glycidylalkylammonium chloride can also be used. One of these may be used alone, or two of them may be used. The above may be used in combination. In particular, dialkylaminoalkyl (meth) acrylamide or salts thereof are preferable when they are formed into a polyion complex because they have excellent stability over time in products.

The graft starch polymer (A) of the present invention is used together with (meth) acrylamide (a ₁ ), an anionic vinyl monomer (a ₂ ) and a cationic vinyl monomer (a ₃ ). 10 mol% of other polymerizable vinyl monomers
Can be contained in a range not exceeding. This type of monomer includes various crosslinkable vinyl monomers such as methylol (meth) acrylamide, dimethylacrylamide, bifunctional, trifunctional, and tetrafunctional, diisopropylacrylamide, (meth) acrylic esters, acrylonitrile , Vinyl acetate, hydroxyl group-containing (meth) acrylic acid, esters, vinylpyrrolidone, and the like.

The grafted starch polymer (A) in the present invention
Can be produced according to a conventional method. For example, an aqueous solution of the cationic starch and the monomer components (a ₁ ) and (a ₂ ) are placed in a reaction vessel equipped with a stirring and nitrogen gas inlet tube.
And (a ₃ ) and water, and as a polymerization initiator, peroxide such as hydrogen peroxide, ammonium persulfate, potassium persulfate, ammonium hydroperoxide, or a reducing agent such as peroxide and bisulfite. Using a redox initiator or a water-soluble azo polymerization initiator such as 2-2 'azobis (2-aminodipropane) hydrochloride at a reaction temperature of 40 to 80 ° C for 1 to 5 hours. Then, the desired graft starch polymer (A) can be obtained.

The graft starch polymer (A) in the present invention
In the production of methacrylate, 50 to 99 mol% of (meth) acrylamide (a ₁ ), 1 to 30 mol% of anionic vinyl monomer (a ₂ ) and cation in an aqueous solution containing 20 to 80 parts by weight of cationic starch It is preferable to polymerize a monomer mixture composed of 1 to 20 mol% of the functional vinyl monomer (a ₃ ). In addition, when the cationic starch is 20
If the amount is less than 10 parts by weight, there is a problem in the disintegration of paper,
Exceeding parts by weight is another factor of printability.

The hydrophobic vinyl monomer (b ₁ ) used for the hydrophobic group-containing anionic copolymer (B) in the present invention includes styrene, alkylstyrene, alkyl (meth) acrylates, vinyl acetate , Olefins,
Α. Such as maleic anhydride; β-unsaturated polybasic acid alkyl (semi) esters and the like may be mentioned, and one kind of these may be used alone or two or more kinds may be used in combination.

The anionic vinyl monomer (b ₂ ) used in the hydrophobic group-containing anionic copolymer (B) in the present invention includes acrylic acid, methacrylic acid, itaconic acid, maleic anhydride, maleic acid, Fumaric acid, vinylsulfonic acid, styrenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid and the like, or sodium, potassium and ammonium salts thereof, and the like.
One of these may be used alone, or two or more may be used in combination.

As long as the effects of the present invention are not impaired, other component monomers such as vinyl chloride, vinylidene chloride, acrylamide and derivatives thereof, vinylpyrrolidone, allyl alcohol, acrylonitrile, and other various monomers May be copolymerized at all.

The hydrophobic group-containing anionic copolymer (B) in the present invention comprises a styrene-maleic acid-based strong polymer salt,
Styrene- (meth) acrylic acid ester- (meth) acrylic acid copolymer salt, olefin-maleic anhydride copolymer and a derivative salt such as the partial ester or partial amide,
Vinyl acetate-maleic acid copolymer salts are preferred.

The styrene-maleic acid copolymer salt is a copolymer salt of styrene and maleic anhydride or a copolymer salt of styrene and maleic ester. The maleic acid ester is a half ester composed of maleic anhydride and a linear or branched alkyl alcohol or alkylphenyl alcohol having 1 to 30 carbon atoms, and can be used alone or in combination depending on the required physical properties. The composition ratio when copolymerizing styrene with maleic anhydride or maleic acid half ester is usually performed in equimolar amounts, but any one of them may be larger.

The styrene- (meth) acrylic acid copolymer salt is obtained by copolymerizing styrene with acrylic acid, styrene with methacrylic acid, styrene with acrylic acid and methacrylic acid. The composition ratio of the styrene and (meth) acrylic acid is 30 to 90 mol% of styrene.
And (meth) acrylic acid 10 to 70 mol%, preferably,
Styrene 40-60 mol% and (meth) acrylic acid 40-
60 mol%.

The styrene- (meth) acrylate- (meth) acrylic acid copolymer salt is obtained by copolymerizing styrene with (meth) acrylic acid ester and (meth) acrylic acid. obtain. The composition ratio is styrene 0
２０20 mol%, (meth) acrylate 30-90
Mol%, and 10 to 70 mol% of (meth) acrylic acid are preferred.

The olefin-maleic anhydride copolymer preferably has a composition ratio of ethylene, diisobutylene, α-olefins of 40 to 60 mol% and maleic anhydride of 40 to 60 mol%. Incidentally, a partial alcohol ester or a partial amide of the copolymer may be used.

The production of the hydrophobic group-containing anionic copolymer (B) in the present invention can be carried out by a conventional method such as solution polymerization, bulk polymerization, or emulsion polymerization, and the solution polymerization is preferred. Examples of the polymerization catalyst include a peroxide such as benzoyl peroxide and an azo compound such as azopisisobutyrone tolyl. The copolymer obtained after the polymerization is neutralized with an alkali such as caustic soda, alkali metal such as caustic potash, ammonium, alkylamines, alkanolamines, morpholines, and polyamines such as ethylenediamine to form a salt, which is hydrophobic. To obtain an aqueous solution of the anionic copolymer (B) having a functional group. These alkalis may be used alone or in combination, and the degree of neutralization is 50 to 1
It is 20 mol%, preferably 90 to 110 mol%.

The molecular weight of the hydrophobic group-containing anionic copolymer (B) in the present invention is from 2,000 to 200,000.
Degree, preferably 5,000 to 100,000.
If the molecular weight is low, a sufficient size effect cannot be obtained. If the molecular weight exceeds 200,000, the viscosity increases and the workability deteriorates.

The aqueous solution of the hydrophobic group-containing anionic copolymer (B) in the present invention may contain, if necessary, alcohols, glycols, and the like for the purpose of improving viscosity stability and volatility.
A water-soluble solvent such as cellosolves may be blended.

The graft starch polymer (A) in the present invention
The mixing ratio of (A) :( B) = 70: 30 to 30:70 with the anionic copolymer (B) having a hydrophobic group. When the amount of the grafted starch polymer is less than 30 parts by weight, there is a problem in printability and disintegration, and when the amount exceeds 70 parts by weight, the paper size effect is deteriorated.

The graft starch polymer (A) in the present invention
The polyion complex of the polymer and the hydrophobic group-containing anionic copolymer (B) must be mixed in advance to form a single system mixture. Since the balance changes depending on the pH of the mixture, depending on the mixing ratio and ion ratio of both,
It is prepared with an organic acid, an inorganic acid or an alkali to a suitable pH that does not precipitate.

The ion complex of the present invention includes a positively charged amphoteric grafted starch polymer (A) (polymer electrolyte) and a negatively charged anionic copolymer having a hydrophobic group. B) (polymer electrolyte). By forming a polyion complex of the component (A) having the surface strength and printability and the component (B) having the sizing property, a form similar to a high molecular weight polymer is formed, and a strong film is formed on the paper surface. It is considered that the desired effect of the present invention can be obtained in order to form.

The coating concentration of the surface treating agent according to the present invention is determined by the amount of liquid absorbed (adhered amount) to the base paper for coating and the quality required for the paper. weight%,
The coating amount is 0.01 to 5 g / m ² of solid content.

The coating solution containing the surface treating agent according to the present invention comprises:
According to an ordinary method, the paper can be coated on the surface of the paper by various coating equipment such as a size press, a gate roll, a calendar, an air knife coater, and a blade coater. In addition,
A spray method, an impregnation method and the like are also arbitrarily adopted.

The surface treating agent according to the present invention comprises a graft starch polymer (A) and a hydrophobic group-containing anionic copolymer (B).
As essential components, as long as the effects of these components are not impaired, if necessary, other compounding agents such as starch derivatives, water-soluble cellulose derivatives, polyvinyl alcohol, vegetable gums, alginic acid Salts, acrylamide-based polymers and the like can be appropriately blended.

The base paper on which the surface treating agent according to the present invention is applied is not particularly limited, and is not limited to the pulp, filler, internal sizing agent, paper strength enhancer, retention agent and the like used.
Further, it can be used for any neutral to acidic papermaking. For example, high quality paper, medium paper, newsprint, coated paper, special paper, processed base paper, liner, core base paper, PPC paper, inkjet or toner printer paper, information paper such as thermal paper, gypsum board base paper, building material paper, etc. Applicable.

[0033]

EXAMPLES Hereinafter, the present invention will be described in more detail based on examples, comparative examples, and applied examples, but the present invention is not limited to these examples.

Example 1 190 parts of cationic tapioca starch (20% by weight aqueous solution, viscosity at 25 ° C., 100 cps, degree of substitution (DS) 0.05), 190 parts of 40% acrylamide, 80% of acrylic acid 1.2 And 4.5 parts of dimethylaminopropylacrylamide, and water was added to bring the total amount to 440 parts.
H was adjusted to 5.0. The whole amount was put in a flask equipped with a stirrer, heated, and 0.5 parts each of ammonium persulfate and sodium bisulfite were added at an internal temperature of 55 ° C., and a polymerization reaction was performed at 65 to 70 ° C. for 3 hours. Cool, add water to add 6
0 parts, viscosity 2500 cps (25 ° C), solid content 15
% Of an aqueous solution of a graft starch polymer (A-1). Separately, 50 parts by weight of styrene and 50 parts by weight of methacrylic acid are subjected to solution polymerization under reflux using azobisisobutylnitrile (AIBN) in the presence of an isopropyl alcohol solvent, and after polymerization, predetermined ammonia water is added for neutralization. did. Thereafter, the solvent was removed by distillation under reduced pressure, and predetermined water was added.
An aqueous solution of 9.0 hydrophobic group-containing anionic copolymer (B-1) was obtained. The two aqueous solutions are mixed to form the (A-1)
A surface treating agent comprising a polyion complex of the component and the component (B-1) was obtained. The properties are shown in Table 1.

[Examples 2 to 4] Cationic starch of graft starch polymer (A), acrylamides (a ₁ ), anionic vinyl monomer (a ₂ ), cationic vinyl monomer (a ₃ ), Kinds and amounts of other monomers, the hydrophobic group vinyl monomer (b) of the hydrophobic group-containing anionic copolymer (B)
₁ ) The type and amount of the anionic vinyl monomer (b ₂ ) and the amount used, and the weight ratio of the grafted starch polymer (A) to the hydrophobic group-containing anionic copolymer (B) were appropriately changed as shown in Table 1. Examples 2 to 7, Comparative Example 1
To 4 were obtained. The properties are shown in Table 1.

[0036]

[Table 1]

The abbreviations in Table 1 are as follows. CS: cationic starch. AAM: acrylamide. AA: acrylic acid. IA: itaconic acid. DMAPAA: N. N-dimethylaminopropylacrylamide MBAA: methylenebisacrylamide

[Evaluation of Performance of Surface Treatment Agent]
7, and the surface treatment agents shown in Comparative Examples 1 to 4 and Reference Examples 1 and 2 were evaluated for performance.

(1) Base paper of surface treating agent: uncoated white liner, basis weight 180 g / m ² . -Uncoated high-quality paper, basis weight 60 g / m ² . (2) Surface Coating Method (a) Evaluation with Liner Each of the surface treatment agents of Examples 1 to 7, Comparative Examples 1 to 4, and Reference Examples 1 and 2 has a solid content of 0.3 g / m ² in terms of solid content. The coating liquid diluted with water was coated on both sides of a white liner using a roll coater, and dried at 90 ° C. for 1 minute with a rotary dryer to perform surface coating. Table 2 shows the amount of the surface treatment agent applied to the test paper and the evaluation of the paper quality.

[0040]

[Table 2]

(B) Evaluation on high quality paper. A coating solution obtained by diluting each of the surface treatment agents of Examples 1 to 7, Comparative Examples 1 to 4, and Reference Examples 1 and ² with water so that the adhesion amount becomes 0.2 g / m ² in solid content, The paper was coated on both sides using a roll coater and dried at 90 ° C. for 1 minute with a rotary dryer. Table 3 shows the amount of the surface treatment agent applied to the test paper and the evaluation of the paper quality.

[0042]

[Table 3]

(3) Paper Quality Evaluation Method of Surface Treatment Agent (1) Size Effect: Steckigt Method, JIS P-8122-1976. Cobb water absorption method, JIS P-8140.

(2) Printability test: IGT test: Printed with an IGT print tester, indicated by the acceleration that causes paper peeling. Testing machine used: IGT printing adequacy testing machine manufactured by Kumagai Riki Kogyo Co., Ltd. Ink used: Toyo Ink Co., Ltd., black ink TV1
5. Conditions: printing pressure 50 kg / m ² , tension A. -RI test: A print test was performed with an RI tester (manufactured by Akira Seisakusho), and the peeling state was evaluated on a five-point scale from 5 excellent to 1 poor. -Color development test of water-based gravure printing: water-based gravure ink is applied to paper coated with a surface treatment agent using a bar coater (No. 1), air-dried, and gloss of the ink is measured with a gloss meter (model: Horiba TG310). Measure.

(3) Disintegration test: surface-coated paper of 5 mm
Put 1g of paper cut into corners into 100g of water at 30 ° C,
The mixture was stirred and disintegrated with a high-speed stirrer (2000 rpm) for 5 minutes.
The disintegrated slurry is paper-made using a hand-sheeting tester, and the disintegration state is 5
Evaluated in 5 grades of excellent to poor 1.

[0046]

The surface treating agent according to the present invention comprises a polyion complex of a graft starch polymer (A) and a hydrophobic group-containing anionic copolymer (B). It is used in gate rolls, calendar coating, etc., and provides a strong sizing effect and greatly improves printability, etc., and also has excellent paper disintegration properties and is ideal for recycling waste paper and waste paper.

Claims (4)

[Claims] 1. A monomer comprising (meth) acrylamide (a ₁ ), an anionic vinyl monomer (a ₂ ) and a cationic vinyl monomer (a ₃ ) in an aqueous solution containing a cationic starch. A graft starch polymer (A) obtained by polymerizing a mixture as an essential component, a hydrophobic copolymer vinyl monomer (b ₁ ) and an anionic vinyl monomer (b ₂ )
And a hydrophobic group-containing anionic copolymer (B) obtained by polymerizing a monomer mixture of the following as an essential component, and a polyion complex of the component (A) and the component (B). A surface treatment agent for paper. 2. The compounding ratio of the graft starch polymer (A) and the hydrophobic group-containing anionic copolymer (B) is (A):
(B) = 70: 30 to 30:70 parts by weight.
The surface treating agent for paper according to the above. 3. The graft starch polymer (A) contains 50 to 98 mol% of (meth) acrylamide (a ₁ ) in an aqueous solution containing 20 to 80 parts by weight of a cationic starch, and an anionic vinyl monomer (a). ₂ ) A graft starch polymer obtained by polymerizing 20 to 80 parts by weight of a vinyl monomer mixture consisting of 1 to 30 mol% and 1 to 20 mol% of a cationic vinyl monomer (a ₃ ). The paper surface treating agent according to claim 1 or 2. 4. The method according to claim 1, wherein the cationic vinyl monomer (a ₃ ) of the graft starch polymer (A) is N.I. 4. An N-dialkylaminoalkyl (meth) acrylamide.
A surface treating agent for paper according to any one of the above.