JPH05132899A - Composition for coated paper - Google Patents

Abstract

(57) [Summary] [Structure] A composition for coated paper, comprising a copolymer latex obtained by emulsion-polymerizing an aliphatic conjugated diene monomer and another copolymerizable monomer. The copolymer latex contains 1 to 2 or more organic solvents selected from the group of ketone compounds, aromatic compounds, organic acid ester compounds and alcohol compounds in all reaction systems.
A composition for coated paper, which is a copolymer latex obtained by emulsion polymerization of 0% by weight of a monomer and simultaneous addition thereof. [Effect] A coated paper for offset rotary printing having a property of excellent balance between adhesive strength and blister resistance can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated paper composition having excellent adhesive strength and blister resistance.
More specifically, the present invention relates to a coated paper composition containing a pigment and a copolymer latex obtained by polymerizing an organic solvent such as a ketone compound at the same time as a monomer.

[0002]

2. Description of the Related Art In recent years, an offset rotary printing press has become remarkably popular in the printing industry as printing speed increases. Compared with sheet-fed offset printing, this printing method requires high-temperature, high-speed drying immediately after printing, so it is necessary to prevent blistering due to water evaporation in the paper during drying. For paper (also referred to as coated paper),
Blister resistance is one of the extremely important required characteristics.
Conventionally, various proposals have been made to satisfy this. For example, Japanese Examined Patent Publication No. 57-10237 discloses a means for adjusting the gel content of a latex as a binder by the amount of a chain transfer agent. However, the blister resistance and the other required quality characteristic, adhesive strength, have a negative correlation, and it is extremely difficult to obtain these well-balanced characteristics.

[0003]

SUMMARY OF THE INVENTION Based on the above background, the present invention provides a composition for coated paper, which has excellent balance between adhesive strength and blister resistance.

[0004]

Means for Solving the Problems As a result of intensive research to solve these problems, the present inventors have found that in the production of an aliphatic conjugated diene-based monomer copolymer latex, a ketone-based compound, etc. It was found that a latex having an excellent balance of adhesive strength and blister resistance can be obtained by simultaneously adding the organic solvent of 1) with the monomer, and completed the present invention. That is, the present invention is as follows. (A) A composition for coated paper, comprising a copolymer latex obtained by emulsion-polymerizing an aliphatic conjugated diene-based monomer and another copolymerizable monomer, the copolymer comprising: The latex contains 1 to 30% by weight of one or more organic solvents selected from the group of ketone compounds, aromatic compounds, organic acid ester compounds and alcohol compounds in the total reaction system, and monomers. A composition for coated paper having excellent adhesive strength and blister resistance, which is a copolymer latex obtained by emulsion polymerization at the same time as. (B) The aliphatic conjugated diene-based monomer is the total monomer mixture 1
The composition for coated paper according to (a) above, which is contained in an amount of 20 to 60 parts by weight with respect to 00 parts by weight. (C) The aliphatic conjugated diene-based monomer is 1,3-butadiene,
2-Methyl-1,3-butadiene, 2-chloro-1,3-butadiene (the above-mentioned composition for coated paper of (A). (D) Other copolymerizable monomers are all monomer mixtures. 1
Aromatic vinyl monomer 15 to 70 parts by weight based on 00 parts by weight
Parts by weight, ethylenically unsaturated carboxylic acid alkyl ester monomer 5 to 50 parts by weight, ethylenically unsaturated acid monomer 1 to
The composition for coated paper according to (a) above, which comprises 10 parts by weight, 0 to 40 parts by weight of a vinyl cyanide monomer, and 1 to 5 parts by weight of another monomer. (E) The composition for coated paper according to the above (D), wherein the aromatic vinyl-based monomer is styrene, α-methylstyrene, or vinyltoluene. (F) The ethylenically unsaturated carboxylic acid alkyl ester monomer is characterized by being acrylic acid esters such as methyl acrylate and ethyl acrylate, methacrylic acid esters such as methyl methacrylate, and diethyl fumarate and dimethyl itaconate. The composition for coated paper according to (d) above. (G) ethylenically unsaturated acid monomer is acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid and maleic acid, itaconic acid monoethyl ester, fumaric acid monobutyl ester, maleic acid monopropyl ester,
The composition for coated paper according to the above (d), which is 2-sulfoethyl acrylate, styrene sulfonic acid, or acrylamide propane sulfonic acid. (H) vinyl cyanide monomer is acrylonitrile,
The composition for coated paper according to (d) above, which is α-chloroacrylonitrile or methacrylonitrile. (I) The other monomer is acrylamide, methacrylamide, N-methylolacrylamide, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate, vinyl acetate The coated paper composition of.

The present invention will be described in more detail below.
The copolymer latex used in the present invention is obtained by simultaneously adding the aliphatic conjugated diene-based monomer and the following monomer copolymerizable therewith with the following organic solvent and emulsion-polymerizing them.
As a method of adding an organic solvent, it is essential to add it together with a monomer or to add it together with a monomer in the case of non-mixing addition, and as long as it complies with this, batch addition, intermittent addition, or continuous addition is possible. Is. However, the object of the present invention cannot be achieved by completely dissolving it in a polymerization medium at the initial stage of polymerization or in an aqueous phase such as monomer emulsified water and adding it. Examples of the organic solvent used in the present invention include ketone compounds such as methyl ethyl ketone, methyl isopropyl ketone,
Aromatic compounds such as methyl isobutyl ketone, toluene, ethylbenzene, cumene and the like, organic acid esters such as ethyl acetate and methyl acetate, and alcohol compounds such as iso-propanol, n- (iso-, sec-, t
-) Butanol and the like can be mentioned. Further, the amount used is appropriately in the range of 1 to 30% by weight, preferably ◯ to XX% by weight in the reaction system. If it is less than 1%, the object of the present invention cannot be achieved. On the other hand, if it exceeds 30%, the stability during polymerization is impaired, which causes coagulum.

The copolymerized latex used in the present invention is characterized in that an organic solvent is added to a reaction vessel under the above-mentioned conditions to carry out emulsion polymerization. Others are not particularly limited according to a known emulsion polymerization method. .. Among the monomers constituting the copolymer latex used in the coated paper composition of the present invention, the aliphatic conjugated diene-based monomer is 1,3-butadiene, 2-methyl-1,3-butadiene , 2-chloro-1,3-butadiene, etc., and these can be used alone or in combination of two or more kinds. These monomers impart appropriate elasticity to the copolymer, and the amount thereof used is 20 to 60 parts by weight based on 100 parts by weight of the total monomer mixture.
If it is less than 20 parts by weight, the glass transition temperature of the copolymer latex becomes high and the adhesive strength is lowered, and if it exceeds 60 parts by weight, the rigidity and water resistance are lowered. It is preferably 25 to 50 parts by weight. Other copolymerizable monomers include aromatic vinyl monomers, ethylenically unsaturated carboxylic acid alkyl ester monomers, ethylenically unsaturated acid monomers, vinyl cyanide monomers and the like. Be done. Examples of the aromatic vinyl-based monomer include styrene, α-methylstyrene, vinyltoluene, and the like, which impart appropriate hardness and water resistance to the copolymer. The amount used is 100
It is 15 to 70 parts by weight in the parts by weight. If it is less than 15 parts by weight, the rigidity and water resistance are insufficient, and if it exceeds 70 parts by weight, the adhesive strength is lowered. It is preferably 25 to 50 parts by weight. Examples of the ethylenically unsaturated carboxylic acid alkyl ester monomer include acrylic acid esters such as methyl acrylate and ethyl acrylate, methacrylic acid esters such as methyl methacrylate and diethyl fumarate, and dimethyl itaconate. Two or more kinds can be used in combination. These monomers are necessary for improving the ink transfer property, and are used in the range of 5 to 50 parts by weight based on 100 parts by weight of the total monomer mixture. If it is less than 5 parts by weight, the ink transfer property is insufficient, and if it exceeds 50 parts by weight, the water resistance and the adhesive strength are lowered. It is preferably 10 to 40 parts by weight.

Examples of the ethylenically unsaturated acid monomer include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid and maleic acid, and further itaconic acid monoethyl ester and fumaric acid monobutyl. Esters and monoalkyl esters of unsaturated dicarboxylic acids such as maleic acid monopropyl ester, and unsaturated sulfonic acids such as 2-sulfoethyl acrylate, styrene sulfonic acid, acrylamido propane sulfonic acid, etc. may be mentioned alone or in combination of two or more. Can be used in combination. These monomers enhance the adhesion of the copolymer latex to the pigment and the base paper, and at the same time improve the mechanical stability of the copolymer latex. The amount of the monomer used is 100% by weight of the total monomer mixture. It is 1 to 10 parts by weight in the parts.
If it is less than 1 part by weight, it is difficult to achieve the purpose, and if it exceeds 10 parts by weight, not only the viscosity of the copolymer latex becomes high and the workability is deteriorated but also the water resistance is deteriorated. It is preferably 1 to 6 parts by weight. Examples of vinyl cyanide-based monomers include acrylonitrile, α-chloroacrylonitrile, and methacrylonitrile.
They can be used alone or in combination of two or more. These monomers are used to improve the gloss at the time of printing coated paper, and are 0% in 100 parts by weight of the total monomer mixture.
Used in the range of up to 40 parts by weight. If it exceeds 40 parts by weight, the adhesive strength and the ink transfer property will be significantly reduced. It is preferably 2 to 20 parts by weight. Other copolymerizable monomers include acrylamide, methacrylamide, N-methylolacrylamide and other ethylenically unsaturated carboxylic acid amides and N-substituted compounds thereof, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, Examples thereof include functional alkyl ester compounds such as glycidyl methacrylate and vinyl esters such as vinyl acetate.
It can be used in the range of 1 to 5 parts by weight in 0 parts by weight.

Examples of the emulsifier include anionic surfactants such as higher alcohol sulfates, alkylbenzene sulfonates and aliphatic sulfonates, nonionic surfactants such as alkyl ester type of polyethylene glycol, alkyl phenyl ether type and alkyl ether type. An active agent and an amphoteric surfactant such as betaine type are used alone or in combination of two or more kinds. Considering the water resistance of the resulting copolymer latex, the amount of these surfactants used is
It is preferably 1 part by weight or less per 100 parts by weight of the total monomer mixture. As the polymerization initiator, potassium persulfate,
Water-soluble initiators such as ammonium persulfate and sodium persulfate,
Oil-soluble initiators such as benzoyl peroxide and azobisisobutyronitrile, or redox initiators can be used. Examples of the chain transfer agent include mercaptans such as octyl mercaptan, n-dodecyl mercaptan and t-dodecyl mercaptan, and sulfides such as tetraethyl thiuram sulfide, which may be used alone or in combination of two or more kinds. The coated paper composition of the present invention may contain various additives such as a dispersant, a water resistance agent, a viscosity modifier, and an antifoaming agent, in addition to the copolymer latex and the pigment. Examples of pigments that can be used in the present invention include clay, calcium carbonate, aluminum hydroxide, titanium white, satin white, inorganic pigments such as talc, and organic pigments such as polystyrene and phenolic resin, but among them kaolinite clay. desirable. Further, as the binder, in addition to the copolymer latex of the present invention, a water-soluble polymer such as starch, casein, polyvinyl alcohol, etc., a latex such as polyvinyl acetate, an acrylate copolymer may be used in combination, if necessary. I can. The copolymer latex of the present invention is
Usually 5 to 30 parts by weight (solid content) based on the pigment (solid content)
Used in the range of. The present invention will be specifically described below with reference to examples. The parts and% in the examples and comparative examples mean parts by weight and% by weight, unless otherwise specified.

[0009]

【Example】

(Production of Copolymer Latex A) Production Example 1 An autoclave equipped with a stirrer and having an internal volume of 100 liters was charged with the following composition and sufficiently mixed, and deoxidation was performed by nitrogen substitution. Water 100 parts by weight Sodium bicarbonate 0.1 parts by weight Sodium lauryl sulfate 0.1 parts by weight Potassium persulfate 1 part by weight Itaconic acid 1 part by weight Table 1 shows the monomer composition and the organic solvent used. In this composition, a hydrophobic monomer (butadiene, styrene, methylmethacrylate, acrylonitrile), t-DM, and an ethylbenzene mixture which is an organic solvent are put in a tank 1, and a water-soluble monomer, pure water and a sodium lauryl sulfate mixture are mixed. The tank 2
And added them to the autoclave at a constant rate for 6 hours. After the addition of the raw materials was completed, the reaction was further continued for 3 hours, and the reaction was completed within 9 hours in total. The internal temperature of the autoclave was kept at 75 ° C. from the start of the addition of the raw materials to the end of the polymerization. After completion of the polymerization, the pH was adjusted to 8.0 with sodium hydroxide, and then unreacted monomers and residual organic solvent were removed by steam stripping, and this copolymer latex was designated as Latex A of the present invention. (Production of Copolymer Latex B to Q) Production Examples 2 to 17 Copolymer latices B to Q were produced in the same manner as in Production Example 1 with the monomer composition and organic solvent shown in Table 1.
Latex B to J are used as the latex for the examples of the present invention,
K to Q are used in the latex for the comparative example. The copolymer latex produced as described above was adjusted to pH 8.0 with sodium hydroxide after completion of the polymerization, and then unreacted monomers and residual container solvent were removed by steam stripping. I went to

Examples 1 to 10 Copolymer latices A to J produced in Production Examples 1 to 10 were used to prepare coated paper compositions having the following formulation, and then coated by the following method. Paper was manufactured and an evaluation test was conducted. The results are shown in Table 2. A test coated paper was further prepared from the above composition under the following conditions. (1) Preparation of Coated Paper for Strength Test The above coated composition was applied to wood free paper with a one-sided coating amount of 1 on a dry weight basis.
It is hand-painted with an appropriate wire bar so that it becomes 5 g / m ^2, and immediately at 120 ° C with a box-type hot air dryer.
Dry for / 20 seconds. The coated paper obtained is further 20 ° C.
Seasoning is performed overnight under the condition of relative humidity of 65%.
Then, the super calender treatment was performed twice under the conditions of a linear pressure of 100 kg / cm 2 at 60 ° C., and the coated paper thus obtained was subjected to a strength test. (2) Preparation of Coated Paper for Blister Test The above coating composition was applied to wood free paper with a single-sided coating amount of 1 on a dry weight basis.
It is hand-painted with an appropriate wire bar so that it becomes 5 g / m ^2, and immediately at 120 ° C with a box-type hot air dryer.
Dry for / 20 seconds. Both sides are coated in the same manner, and the coated paper obtained is further seasoned under conditions of 20 ° C. and 65% relative humidity for one day. 60 ℃ linear pressure after that 10
The super calender treatment was performed twice under the condition of 0 kg / cm 2, and the coated paper thus obtained was subjected to a blister test. The coated paper obtained was evaluated according to the test methods shown below, and the results are shown in Table 2. 1) Dry pick strength test Using a RI printing aptitude tester (manufactured by Akira Seisakusho Co., Ltd.), the printing condition of the tack ink (Toyo Ink SMX Tack 15) was visually judged and the 10-point method (10 points were excellent 1 point was inferior). 2) Blister test The oil-bath-coated paper at 150 ° C to 200 ° C is dipped into the blister and scored according to the number of blister (no blister =
5) The average of 20 test pieces was evaluated.

Comparative Examples 1 to 7 The compositions for coated papers were prepared in the same manner as in Examples using K to Q produced in Production Examples 11 to 17, and then coated papers were produced in the same manner as in Examples and evaluated. The test was conducted. The results are shown in Table 2 together with the examples.

[0012]

[Table 1]

[0013]

[Table 2]

[0014]

The coated paper obtained from the coated paper composition of the present invention exhibits excellent adhesive strength and blister resistance, and the present invention is useful as a coated paper composition which has never been used before. It is clear from Table 2 that this is the case.

Claims (9)

[Claims] 1. A composition for coated paper, comprising a copolymer latex obtained by emulsion-polymerizing an aliphatic conjugated diene-based monomer and another copolymerizable monomer, which comprises: The polymer latex contains one or more organic solvents selected from the group of ketone compounds, aromatic compounds, organic acid ester compounds and alcohol compounds in an amount of 1 to 30% by weight in the whole reaction system. A composition for coated paper, characterized in that it is a copolymer latex obtained by emulsion polymerization with simultaneous addition of a monomer. 2. The composition for coated paper according to claim 1, wherein the aliphatic conjugated diene monomer is contained in an amount of 20 to 60 parts by weight based on 100 parts by weight of the total monomer mixture. .. 3. The aliphatic conjugated diene-based monomer is 1,3-butadiene, 2-methyl-1,3-butadiene, 2-chloro-1,3
-The composition for coated paper according to claim 1, which is butadiene. 4. Aromatic vinyl monomer 1 based on 100 parts by weight of the total monomer mixture.
5 to 70 parts by weight, ethylenically unsaturated carboxylic acid alkyl ester monomer 5 to 50 parts by weight, ethylenically unsaturated acid monomer 1 to 10 parts by weight, vinyl cyanide monomer 0 to 40
2. 1 part by weight and 1 to 5 parts by weight of another monomer.
A coated paper composition as described above. 5. The aromatic vinyl monomer is styrene or α
A composition for coated paper according to claim 4, characterized in that it is methylstyrene and vinyltoluene. 6. The ethylenically unsaturated carboxylic acid alkyl ester monomer is acrylic acid ester such as methyl acrylate and ethyl acrylate, methacrylic acid ester such as methyl methacrylate and diethyl fumarate and dimethyl itaconate. The composition for coated paper according to claim 4, characterized in that. 7. The ethylenically unsaturated acid monomer is acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid and maleic acid, itaconic acid monoethyl ester,
The coated paper composition according to claim 4, wherein the composition is fumaric acid monobutyl ester, maleic acid monopropyl ester, 2-sulfoethyl acrylate, styrene sulfonic acid, and acrylamido propane sulfonic acid. 8. The composition for coated paper according to claim 4, wherein the vinyl cyanide-based monomer is acrylonitrile, α-chloroacrylonitrile, or methacrylonitrile. 9. The other monomer is acrylamide, methacrylamide, N-methylolacrylamide, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate, vinyl acetate. The coated paper composition according to 1.