JP2001192996A - Method for producing binder for paper coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a binder for paper coating excellent in admixture stability as a binder and providing a coated paper excellent in aptitude for a high-speed coating and printing strength and especially in waterproof printing strength and ink receptivity. SOLUTION: This method for producing a binder for paper coating is characterized by adding a non-formaldehyde-based crosslinked amine compound (solid) in an amount of 0.1-5.0 pts.wt. based on 100 pts.wt. of a copolymeric latex (solid) obtained by carrying out a emulsion polymerization of a monomer composed of 20-80 wt.% of an aliphatic conjugated diene-based monomer, 0.5-10 wt.% of an ethylene-based unsaturated carboxylate monomer and 10-79.5 wt.% of other monomer copolymerizable with the monomers and having 0.05-0.15 μm weight-average particle diameter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a paper coating binder. More specifically, the present invention relates to a method for producing a binder for paper coating, which provides a coated paper having excellent mixing stability as a binder and excellent in high-speed coating suitability and printing strength, particularly, water-proof printing strength and ink adhesion. It is.

[0002]

2. Description of the Related Art Butadiene-based copolymer latex containing butadiene as a main component is widely used as various kinds of binders in the field of paper coating and the like. Various copolymer latexes have been used. The copolymer latex used as these paper coating binders is usually prepared as a paper coating composition together with pigments such as calcium carbonate, kaolin clay and talc and other additives as necessary. Coated on base paper.

[0003] In recent years, as the production of coated paper has increased,
High-speed coating for the purpose of improving coated paper production is progressing. In addition, a high concentration of a paper coating composition for the purpose of coping with a decrease in drying ability accompanying such high-speed coating and improving production efficiency has been promoted. Therefore, in order to cope with these, the paper coating composition is required to have high performance that can withstand high-speed coating and high-concentration coating. For example, in high-speed coating or high-concentration coating in blade coating, excellent high-speed fluidity and water retention are required. If these are inferior, deposits accumulate on the blade edge of the blade, and bleeding (coating on coated paper) Troubles such as residue adhesion and streaks (striations on the coated paper) occur, which greatly affects the coating workability. On the other hand, printing speed has also been increased, and coated paper used for printing is required to have high performance. That is, coated paper is required to have excellent printing strength and water-proof printing strength that can withstand high-speed printing, and particularly in offset printing, ink adhesion under the influence of dampening water is required.

[0004] In order to impart these various properties at the time of printing, a method has been proposed in which, for example, a polyalkylene polyamine-urea-formaldehyde resin or a polyamide-urea-formaldehyde resin is added to a paper coating composition (Japanese Patent Application Laid-Open No. H11-157572). JP-B-44-116677, JP-A-51-1210
No. 41, JP-A-61-281127, JP-A-6-22
No. 8899). Japanese Patent Publication No. 3-4680 proposes a method for preparing a paper coating composition in which an aqueous solution of a specific thermosetting resin is added to a copolymer latex in advance and then mixed with a pigment.

[0005] However, although these methods are expected to improve to some extent, at present, they have not been able to sufficiently cope with further improvement requests, and in particular, Japanese Patent Publication No. 3-4680 discloses a specific method. The method of adding an aqueous solution of a thermosetting resin to the copolymer latex in advance has a problem that the mixing stability with the copolymer latex used as the binder is inferior, so that the preparation of the binder is considerably restricted. .

[0006]

DISCLOSURE OF THE INVENTION In view of the above-mentioned circumstances, the present inventors have conducted intensive studies to solve the current problems, and as a result, have found that a specific compound is By adding at a ratio, the coated latex is excellent in mixing stability of the copolymer latex and the compound, and has high-speed coating suitability and printing strength, especially water-resistant printing strength, and excellent ink adhesion. The present invention was found to be a paper coating binder to be provided, and the present invention was completed.

[0007]

That is, the present invention provides:
(1) 20 to 80% by weight of an aliphatic conjugated diene monomer, 0.5 to 10% by weight of an ethylenically unsaturated carboxylic acid monomer, and 10 to 79.5 of another monomer copolymerizable therewith. % By weight of a copolymer latex (solid content) having a weight-average particle diameter of 0.05 to 0.15 μm obtained by emulsion polymerization of a monomer consisting of a non-formaldehyde-based crosslinked amine compound (solid (2) a method for producing a binder for paper coating, characterized by adding 0.1 to 5.0 parts by weight; (2) an aliphatic conjugated diene-based monomer as a first step; After 10 to 50% by weight of the monomer containing the polymer is added and emulsion polymerization is carried out, the second step is the addition of the remaining monomer and emulsion polymerization is carried out. An object of the present invention is to provide a method for producing an industrial binder.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
As the aliphatic conjugated diene monomer in the present invention,
1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, substituted linear conjugated pentadienes, substituted and side chain conjugated Hexadienes and the like can be used, and one kind or two or more kinds can be used. Especially 1,
3-Butadiene is preferred.

Examples of the ethylenically unsaturated carboxylic acid monomer include mono- or dicarboxylic acids (anhydrides) such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid and itaconic acid. One or more of these can be used.

Other monomers copolymerizable with the aliphatic conjugated diene monomer and the ethylenically unsaturated carboxylic acid monomer include alkenyl aromatic monomers and unsaturated carboxylic acid alkyl ester monomers. And unsaturated monomers containing a hydroxyalkyl group, vinyl cyanide monomers, unsaturated carboxylic acid amide monomers and the like.

The alkenyl aromatic monomers include styrene, α-methylstyrene, methyl α-methylstyrene,
Vinyl toluene and divinyl benzene, and the like,
One or more kinds can be used. Particularly, styrene is preferred.

Examples of unsaturated carboxylic acid alkyl ester monomers include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, glycidyl methacrylate, dimethyl fumarate, diethyl fumarate, dimethyl maleate, diethyl maleate, dimethyl dimethyl Examples include itaconate, monomethyl fumarate, monoethyl fumarate, 2-ethylhexyl acrylate, and the like, and one or more kinds can be used. Particularly, methyl methacrylate is preferred.

Examples of unsaturated monomers containing a hydroxyalkyl group include β-hydroxyethyl acrylate and β-hydroxyethyl acrylate.
-Hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate,
Hydroxybutyl acrylate, hydroxybutyl methacrylate, 3-chloro-2-hydroxypropyl methacrylate, di- (ethylene glycol) maleate,
Di- (ethylene glycol) itaconate, 2-hydroxyethyl maleate, bis (2-hydroxyethyl)
Maleate, 2-hydroxyethyl methyl fumarate and the like can be mentioned, and one kind or two or more kinds can be used. Particularly, β-hydroxyethyl acrylate is preferable.

Examples of the vinyl cyanide monomer include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethylacrylonitrile and the like.
One or more kinds can be used. Particularly, acrylonitrile and methacrylonitrile are preferred.

The unsaturated carboxylic acid amide monomers include:
Acrylamide, methacrylamide, N, N-dimethylacrylamide and the like can be mentioned, and one or more kinds can be used. Particularly, acrylamide and methacrylamide are preferred.

The above monomer composition is composed of 20 to 80% by weight of an aliphatic conjugated diene monomer, 0.5 to 10% by weight of an ethylenically unsaturated carboxylic acid monomer and other copolymerizable with them. The amount of the monomer is 10 to 79.5% by weight.

When the amount of the aliphatic conjugated diene monomer is less than 20% by weight, the printing strength tends to be poor.

When the amount of the ethylenically unsaturated carboxylic acid monomer is 0.
If it is less than 5% by weight, mechanical stability is poor, and 10% by weight
If it exceeds 300, the viscosity of the latex tends to increase, which is not preferable.

If the amount of the other copolymerizable monomer is less than 10% by weight, the waterproof printing strength tends to be low, and if it exceeds 79.5% by weight, the printing strength tends to be inferior.

The weight average particle diameter of the copolymer latex in the present invention is required to be 0.05 to 0.15 μm from the viewpoint of high speed coating suitability and water resistant printing strength.

The gel content of the copolymer latex is not particularly limited, but is preferably from 10 to 95% by weight.

In the present invention, a copolymer latex is obtained by emulsion-polymerizing the above-mentioned monomer, and the polymerization method is not particularly limited, but the miscibility with the non-formaldehyde-based crosslinked amine compound. ,
Further, from the viewpoint of printability, it is preferable to carry out the polymerization method by the following two-stage polymerization. That is, as a first step, 10 to 50% by weight of a monomer containing an aliphatic conjugated diene monomer is added to carry out emulsion polymerization, and as a second step, the remaining monomer is added to carry out emulsion polymerization. It is a step polymerization. At this time, 2
The remaining monomer to be added as a stage is preferably added after the polymerization addition ratio of the monomer to be added to the first stage becomes 10% by weight, preferably 20% by weight. Here, the monomer composition added in the first stage and the second stage is usually preferably a different monomer composition,
It does not prevent the same monomer composition.
However, in the case of having exactly the same monomer composition, the monomers to be added in the first stage are added by the collective addition method described below, and then the monomers in the second and subsequent stages are added. . Also,
With respect to the monomer to be added in the second and subsequent stages, it does not hinder that the monomer composition is changed intermittently or continuously thereafter.

The method of adding the various components in the emulsion polymerization of the above monomers in the present invention is not particularly limited, and any of a batch addition method, a division addition method, and a continuous addition method can be employed. Further, in the emulsion polymerization, commonly used emulsifiers, chain transfer agents, polymerization initiators, hydrocarbon compounds, electrolytes, polymerization accelerators, chelating agents and the like can be used.

Examples of the emulsifier include higher alcohols such as sulfates, alkylbenzene sulfonates, alkyl diphenyl ether sulfonates, aliphatic sulfonates, aliphatic carboxylates, and nonionic surfactants such as sulfates. A surfactant or a nonionic surfactant such as an alkyl ester type, an alkyl phenyl ether type or an alkyl ether type of polyethylene glycol is used alone or in combination of two or more.

Examples of the chain transfer agent include alkyl mercaptans such as α-methylstyrene dimer, n-hexyl mercaptan, n-octyl mercaptan, t-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-stearyl mercaptan, and dimethyl. Xanthogen compounds such as xanthogen disulfide and diisopropylxanthogen disulfide; terpinolene; thiuram-based compounds such as tetramethylthiuram disulfide, tetraethylthiuram disulfide and tetramethylthiuram monosulfide; and 2,6-di-t-butyl-4-methylphenol , Phenolic compounds such as styrenated phenols, allyl compounds such as allyl alcohol, halogenated carbons such as dichloromethane, dibromomethane, carbon tetrabromide, etc. Containing compounds, alpha-benzyloxy styrene, alpha-benzyloxy acrylonitrile, alpha-benzyloxy ethers such as acrylamide, triphenyl ethane, pentaphenylethane, acrolein,
Methacrolein, thioglycolic acid, thiomalic acid,
Examples thereof include 2-ethylhexyl thioglycolate, and one or more of these can be used.

As the polymerization initiator, a water-soluble polymerization initiator such as potassium persulfate, sodium persulfate and ammonium persulfate, a redox-based polymerization initiator, and an oil-soluble polymerization initiator such as benzoyl peroxide can be appropriately used.

The hydrocarbon compounds include pentane, hexane, heptane, octane, cyclohexane,
Saturated hydrocarbons such as cycloheptane, unsaturated hydrocarbons such as pentene, hexene, heptene, cyclopentene, cyclohexene, cycloheptene, 4-methylcyclohexene and 1-methylcyclohexene; and aromatic hydrocarbons such as benzene, toluene and xylene. . In particular, cyclohexene, which has a moderately low boiling point and which can be used to recover and reuse components remaining as unreacted substances after polymerization by steam distillation or the like, is preferred.

In the present invention, based on 100 parts by weight of the copolymer latex (solid content) obtained by the above method,
Non-formaldehyde crosslinked amine compound (solid content)
By adding 0.1 to 5.0 parts by weight, a paper coating binder excellent in mixing stability can be obtained. The use ratio of the non-formaldehyde crosslinked amine compound is 0.
If the amount is less than 1 part by weight, the effect of the present invention is insufficient, and if it exceeds 5.0 parts by weight, the printing strength is remarkably reduced. Preferably it is 0.1 to 3.0 parts by weight. As described above, by adding a non-formaldehyde-based crosslinked amine compound to the copolymer latex of the present invention, a paper coating binder that has excellent mixing stability and exhibits excellent coated paper performance is obtained. For example, a method in which the copolymer latex and the non-formaldehyde-based crosslinked amine compound of the present invention are simultaneously mixed with the pigment can be expected to have some effects, but exhibit the effects expected in the present invention. Can not do it.

Examples of the non-formaldehyde-based crosslinked amine compound used in the present invention include, for example, a reaction product of a heterocyclic amine and a glycidyl compound (Japanese Unexamined Patent Publication No.
140792), a reaction product of a polyalkylene polyamine and a glycidyl compound (JP-A-11-107195).
), A reaction product of a polyalkylene polyamine, an alicyclic compound and a urea (JP-A-11-36188); a reaction product of a polyalkylene polyamine with an α, β-unsaturated monomer and a urea JP-A-11-124794), JP-A-10-195799 and JP-A-11-2377.
Examples thereof include, but are not limited to, crosslinked amine compounds described in No. 96 and the like.

The paper coating binder obtained in the present invention is usually mixed at a ratio of 5 to 30 parts by weight in terms of solid content with respect to 100 parts by weight of the pigment to obtain a paper coating composition. Prepared. Examples of the pigment used here include kaolin clay, talc, barium sulfate, titanium oxide, calcium carbonate, aluminum hydroxide, zinc oxide,
Examples thereof include inorganic pigments such as satin white and organic pigments such as polystyrene latex, and these are used alone or in combination.

In preparing the paper coating composition,
Starch, oxidized starch, modified starch such as esterified starch, soy protein, natural binders such as casein, or polyvinyl alcohol, polyvinyl acetate latex, synthetic latex such as acrylic latex, etc. Furthermore, other auxiliaries, such as dispersants (sodium pyrophosphate, sodium polyacrylate, sodium hexametaphosphate, etc.), defoamers (polyglycols, fatty acid esters, phosphate esters, silicone oils, etc.), leveling agents (funnel oil, Dicyandiamide, urea, etc.), preservatives, mold release agents (calcium stearate, paraffin emulsion, etc.), fluorescent dyes, color water retention improvers (carboxymethyl cellulose, sodium alginate, etc.) are added as required.

Further, the method for applying the paper coating composition to the coated paper may be a known technique, for example, an air knife coater,
It is performed by a coating machine such as a blade coater, a roll coater, and a bar coater. After the application, the surface is dried and finished with a calender ring or the like.

[0033]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples unless it exceeds the gist. In the examples, parts and% indicating percentages are based on weight unless otherwise specified. The evaluation of various physical properties in the examples was based on the following methods.

[0034]Evaluation of flowability of paper coating composition  Double cylindrical Hercules high shear viscometer (Osamu Kumagai
(Manufactured by Kiki Kogyo). Using the inner cylinder bob F
Composition for each paper coating at 4000 rpm to give a cutting speed
The apparent viscosity (cps) of the object was measured. The lower number is
It has low apparent viscosity and good fluidity.

[0035]Evaluation of dry pick strength of coated paper  Picking when simultaneously printing each coated paper sample with an RI printing machine
The degree of aging is judged with the naked eye, and it is grade 5 (best) to grade 1.
(Worst) was relatively evaluated.

[0036]Evaluation of wet pick strength of coated paper  Each coated paper sample by Molton roll using RI printing machine
Fountain solution at the same time
Picking when printing each coated paper sample at the same time
The degree is judged with the naked eye, and the level is 5 (best) to 1 (worst
Relatively).

[0037]Evaluation of ink deposition on coated paper  Print while mixing water with ink using RI printing machine
To determine the ink inking property with the naked eye
) To 1st grade (worst).

[0038]Measurement of gel content of copolymer latex  A latex film is prepared at room temperature. afterwards
About 1 g of a latex film is weighed and 400 cc
In toluene for 48 hours to dissolve. Then
This was filtered through a 300 mesh wire mesh and captured by the wire mesh.
After the toluene-insoluble portion is dried and weighed,
The percentage of the weight of the tex film as the gel content
% By weight.

[0039]Preparation of copolymer latex  In a pressure-resistant polymerization reactor, 150 parts of polymerization water, as an emulsifier
Sodium dodecylbenzenesulfonate (parts shown in Table 1)
Number), 0.2 parts of sodium carbonate and 1 part of potassium persulfate
After charging and stirring sufficiently, the first stage (left /) shown in Table 1
After adding each monomer and other compounds,
When the polymerization conversion of the first stage reaches 70%
For 2 hours (/ right) monomer and other compounds for 6 hours
After the addition, the polymerization is continued for 3 hours,
Has ended. What is the polymerization addition rate of the copolymer latex
Was also 96% or more. Next, the copolymer latex
After adjusting the pH to 7 with aqueous sodium hydroxide solution,
Unreacted monomers and other low-boiling compounds are removed by gas distillation.
Then, copolymer latexes a to c were obtained.

[0040]Copolymer latex composition (paper coating
Preparation)  100 weight of the above copolymer latex a to c (solid content)
Non-formaldehyde cross-linked amine compound
(SPI-100: manufactured by Sumitomo Chemical Co., Ltd., SPI-1
01: Sumitomo Chemical Co., Ltd., PA-640NF: Japan
SMC-S-PA-179: Nippon Pi
-MC Corporation) or formaldehyde compound
(SR-636: manufactured by Sumitomo Chemical Co., Ltd.)
The copolymer was added at the ratio shown in Table 2 in terms of solid content,
Tex compositions I-IV and i-iv were prepared.

[0041]Preparation of composition for paper coating  According to the formulation shown below, the copolymer latex
No compound I-IV, i-iv or cross-linked amine compound
Composition for paper coating shown in Table using copolymer latex a
Products 1-9 were prepared. In addition, about the composition 9 for paper coating
Is a non-formaldehyde crosslinked amine
Compound (SPI-100: manufactured by Sumitomo Chemical Co., Ltd.)
It was prepared by adding 0.05 parts (solid content). (Formulation of paper coating composition) Kaolin clay 80 parts Heavy calcium carbonate 20 parts Starch oxide 4 parts Copolymer latex composition or 10 parts Copolymer latex・ ・ ・ Solid content 63%

[0042]Production of coated paper  Using a commercially available hot air coating dryer MLC-100S,
The obtained paper coating composition was applied to a base paper (basis weight 80 g / m2).
Each of the objects 1 to 9 was coated to prepare each coated paper. What
In addition, each coated paper was produced under the same conditions shown below. Coating conditions: Coating of the above composition with the hot air coating dryer described above.
Use a wire bar so that the work volume is 13 g / m2 on one side
And applied. The coating speed is 50 m / min. Set to
Was. Drying condition: about 0.5 seconds after coating, drying oven at 150 ° C
Within 5 seconds with hot air at a temperature of 210 ° C and a wind speed of 33m / s
While drying. Each coated paper obtained was subjected to a relative humidity of 65% and a temperature of 65%.
After conditioning for 24 hours at a temperature of 20 ° C, the linear pressure was 70 kg /
cm, temperature 50 ° C, paper passing speed 7m / min,
Super calender processing under a total of 4 paper passing conditions, each coating
I got the paper. The coated paper thus obtained was subjected to each test and evaluated.
Table 3 shows the results.

[0043]

[Table 1]

[0044]

[Table 2]

[0045]

[Table 3]

[0046]

According to the present invention, by adding a specific compound to the copolymer latex of the specific composition of the present invention at a specific ratio, the mixing stability between the copolymer latex and the compound is excellent, and An object of the present invention is to provide a paper coating binder which provides a coated paper having excellent high-speed coating suitability and printing strength, particularly water-proof printing strength and ink adhesion.

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Claims (2)

[Claims] 1. An aliphatic conjugated diene monomer of 20 to 80% by weight, an ethylenically unsaturated carboxylic acid monomer of 0.5 to 10%.
% By weight and other monomers copolymerizable therewith.
100 parts by weight of a copolymer latex (solid content) having a weight-average particle diameter of 0.05 to 0.15 μm obtained by emulsion polymerization of a monomer consisting of 9.5% by weight is added to a non-formaldehyde-based crosslinked amine. Compound (solid content) 0.1-5.
A method for producing a binder for paper coating, comprising adding 0 parts by weight. 2. A copolymer latex comprising, as a first stage, a monomer containing an aliphatic conjugated diene monomer in an amount of 10 to 50% by weight.
The method for producing a paper coating binder according to claim 1, wherein the copolymer latex is a copolymer latex obtained by adding the remaining monomer to the emulsion and adding the remaining monomer as the second stage.