JPH0776324B2 - Composition for coating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a coating composition for use in the production of coated paper and a carpet backing material, preferably a good coating composition used at a high solid content. The present invention relates to a coating composition suitable as a paper coating composition capable of producing a coated paper excellent in physical properties of coated paper and particularly suitable for printing.

[Prior Art] Coating with a composition having a high solid content for paper coating has advantages such as reducing a drying load and increasing productivity of the coating.
Various attempts have been made to develop the technology. Simply increasing the solid content of the coating material that has been conventionally used for paper coating significantly increases the viscosity of the coating material and deteriorates the fluidity, making it unsuitable for coating. As a performance to be provided as a coating material for paper coating, the viscosity at a high shear rate at the time of coating should be appropriate, the fluidity should be good, and the viscosity at a low shear rate should be appropriate.

In order to obtain such a paper coating composition, it is said that it is effective to use a large amount of calcium carbonate as a pigment and a small amount of kaolinite clay or satin white, but if a large amount of calcium carbonate is used, It causes a decrease in gloss and rigidity of the obtained coated paper.

Further, in recent years, there is a tendency to increase the printing speed in order to improve the productivity at the time of printing, and the requirements for the surface strength and the blister resistance of the coated paper are becoming more and more severe.

[Problems to be Solved by the Invention] As described above, in the conventionally known coating technique, it is possible to obtain a coated paper which is a coating material using a large amount of calcium carbonate and having excellent coatability and which has excellent gloss. It is extremely difficult to meet the recent strict requirements regarding blister resistance and adhesive strength.

The object of the present invention is to provide a coating composition that can be used for various purposes, including a paper coating composition having a high solid content and good coating properties, and having excellent coated paper physical properties. The present invention provides a composition for use.

[Means for Solving the Problems] The first aspect of the present invention provides calcium carbonate of at least 30
100 parts by weight of pigment containing 100% by weight and water-soluble polymer compound 0 to 1
The present invention relates to a coating composition comprising 0 part by weight and 5 to 50 parts by weight of the following copolymer latex (calculated as solid content) and having a solid content concentration of 58% by weight or more.

Copolymer latex; (a) 15 to 60% by weight of conjugated diene monomer, (b) 30 to 84.5% by weight of ethylenically unsaturated monomer, (c) 0 to 30% by weight of vinyl cyan compound monomer. A copolymer latex obtained by emulsion-polymerizing a monomer containing (d) 0.5 to 10% by weight of an ethylenically unsaturated carboxylic acid monomer in the presence of α-methylstyrene dimer.

The second invention of the present invention comprises at least 30 parts of calcium carbonate.
100 parts by weight of pigment containing 100% by weight and water-soluble polymer compound 0 to 1
The present invention relates to a coating composition comprising 0 part by weight and 5 to 50 parts by weight of the following copolymer latex (calculated as solid content) and having a solid content concentration of 58% by weight or more.

Copolymer latex; (a) 15 to 60% by weight of conjugated diene monomer, (b) 30 to 84.5% by weight of ethylenically unsaturated monomer, (c) 0 to 30% by weight of vinyl cyan compound monomer. , (D) 0.5 to 10% by weight of an ethylenically unsaturated carboxylic acid monomer, a monomer containing terpinolene, α-terpinene, γ
A copolymer latex obtained by emulsion polymerization in the presence of at least one compound selected from terpinene and dipentene.

Hereinafter, the present invention will be described in detail.

Calcium carbonate, which accounts for at least 30% by weight, preferably 50 to 90% by weight, of the pigment used in the present invention has a mean particle diameter of 5 μm or less, preferably 0.5 to 2 μm, and a heavy calcium carbonate having an average particle diameter of 1 μm. Below, light calcium carbonate of 0.2 to 0.8 μm is preferable.

As the pigment other than calcium carbonate, various clays generally used for coating, titanium dioxide, aluminum hydroxide, satin white, talc, calcium sulfite and other pigments can be blended.

When the content of calcium carbonate in the pigment is less than 30% by weight, the viscosity of the coating composition is increased and the fluidity is significantly reduced, resulting in extremely low coating workability.

Examples of the water-soluble polymer compound used in the present invention include modified starch such as oxidized starch, starch, casein, polyvinyl alcohol, sodium alginate,
Examples thereof include natural or synthetic water-soluble polymer compounds such as carboxymethyl cellulose, methyl cellulose, and hydrooxycellulose, and modified starch is particularly preferable. These water-soluble polymer compounds can be used alone or in combination of two or more.

The amount of the water-soluble polymer compound used is 0 to 10 parts by weight, preferably 0.1 to 10 parts by weight, and particularly preferably 1 to 5 parts by weight, based on 100 parts by weight of the pigment. If the amount used exceeds 10 parts by weight, the viscosity becomes too high to be suitable for coating. Further, since the water-soluble polymer compound is added as an aqueous solution, if the amount of addition is large, a coating composition having a high solid content cannot necessarily be obtained.

Specific examples of the (a) conjugated diene-based monomer used for producing the copolymer latex of the present invention include, for example, butadiene, isoprene, 2-chloro-1,3-butadiene, and 2-methyl-1,3- Butadiene etc. can be mentioned. These may be used alone or in combination of two or more. Of these, butadiene is particularly preferable.

This monomer (a) is used for imparting appropriate elasticity and film hardness to the resulting copolymer, and the amount used is 15 to 60% by weight based on the total monomers, Preferably 20-55
It is selected from the range of weight%. If this amount is less than 15% by weight, sufficient adhesive strength cannot be obtained, while 60% by weight
If it exceeds, the water resistance and the adhesive strength are lowered, which is not preferable.

(B) Specific examples of the ethylenically unsaturated monomer include aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, p-methylstyrene, methyl acrylate, ethyl acrylate, butyl acrylate, and acrylic. 2-hydroxyethyl acid, 2-hydroxyethyl methacrylate, glycidyl methacrylate, acrylic acid or methacrylic acid alkyl ester compounds, acrylamide, methacrylamide, N, N-dimethylacrylamide, N-methylolacrylamide, and other ethylenically unsaturated compounds Examples thereof include acrylamide or methacrylamide compounds of carboxylic acids, carboxylic acid vinyl esters such as vinyl acetate, and the like, and ethylenically unsaturated monomers other than the components (c) and (d) described later. These may be used alone or in combination of two or more. Of these, styrene is preferably used as the aromatic vinyl compound, and methyl methacrylate is preferably used as the alkyl ester compound.

This monomer (b) has an appropriate hardness for the resulting copolymer,
It is used to impart elasticity and water resistance, and the amount used is selected from the range of 30 to 84.5% by weight, preferably 30 to 73.5% by weight. If the amount used is less than 30% by weight, the water resistance of the coating composition is poor, whereas if it exceeds 84.5% by weight, the copolymer becomes too hard and the adhesive strength decreases, which is not preferable.

Specific examples of the vinyl cyan compound monomer (c) include 2
Examples thereof include vinyl cyanide compounds such as cyanoethyl acrylate, acrylonitrile, methacrylonitrile and α-chloroacrylonitrile. These may be used alone or in combination of two or more. Acrylonitrile is preferably used as the monomer (c). The monomer (c) has a function of improving gloss. The amount of the monomer (c) used is 0 to 30% by weight, preferably 1 to 25% by weight, and when the amount used exceeds 30% by weight, the adhesive strength decreases.

Specific examples of the (d) ethylenically unsaturated carboxylic acid monomer include monocarboxylic acids such as acrylic acid, methacrylic acid and crotonic acid, dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid, and methyl maleate. Examples thereof include half esters such as methyl itaconate and β-methacryloxyethyl acid hexahydrophthalate. Also, an anhydride of dicarboxylic acid can be used. These may be used alone or in combination of two or more. As the monomer (d), it is preferable to essentially include at least one selected from dicarboxylic acids, half esters thereof and dicarboxylic acid anhydrides, and it is particularly preferable to use dicarboxylic acids. Then, the weight ratio (α) / of at least one kind (α) selected from dicarboxylic acids, half esters and dicarboxylic acid anhydrides to the monocarboxylic acid (β)
(Β) is 5/59 to 100/0, more preferably 10/90 to 95/5
Is. When used in this ratio range, the adhesive strength, the latex and the mechanical stability of the coating composition are excellent.

The amount of the monomer (d) used is selected from the range of 0.5 to 10% by weight, preferably 1 to 7% by weight, based on all the monomers. If the amount used is less than 0.5% by weight, not only the adhesive strength but also the mechanical stability of the copolymer latex will decrease, while if it exceeds 10% by weight, the viscosity of the copolymer latex will increase and the handling will be difficult. It becomes difficult and the operability is deteriorated, which is not preferable.

The copolymer latex in the present invention can be obtained by emulsion-polymerizing the above-mentioned monomer in an aqueous medium. The feature of the present invention lies in that this emulsion-polymerization is carried out in the presence of a specific polymerization chain transfer agent. . That is, in the first aspect of the present invention, a polymerization chain comprising 2 to 100% by weight of α-methylstyrene dimer and 98 to 0% by weight of another weight chain transfer agent in the presence of α-methylstyrene dimer is preferable. In the presence of a transfer agent, and in the second invention of the present invention,
In the presence of at least one compound selected from terpinolene, α-terpinene, γ-terpinene and dipentene, preferably (A) at least one compound 2-100 selected from terpinolene, α-terpinene, γ-terpinene and dipentene The emulsion polymerization is carried out in the presence of a polymerization chain transfer agent comprising (B) an alkyl mercaptan, carbon tetrachloride, carbon tetrachloride, xanthogen disulfides and at least one compound (98 to 0% by weight) selected from thiuram disulfides. To do.

The coating composition of the present invention using the copolymer latex obtained by polymerization in the presence of the above-mentioned polymerization chain transfer agent, without reducing the coatability, as a paper coating composition When used, it has excellent adhesive strength, blister resistance, and printing gloss, and particularly excellent printing gloss.

The polymerization chain transfer agent used in the first invention (hereinafter referred to as the polymerization chain transfer agent (I)) is composed of α-methylstyrene dimer and another polymerization chain transfer agent used as necessary.

As the α-methylstyrene dimer, (i) 2-4-diphenyl-4-methyl-1-pentene, (b) 2-4-diphenyl-4-methyl-2-pentene, and (c) There is 1-1-3-trimethyl-3-phenylindane. The preferable composition of the α-methylstyrene dimer is that the component (a) is 40% by weight or more, the component (b) and /
Or (C) component is 60% by weight or less, more preferably,
Component (a) is 50% by weight or more, component (b) and / or component (c) is 50% by weight or less, particularly preferably component (a) is 70% by weight or more, component (b) and / or component (c). ) The component is 30% by weight or less. The higher the composition ratio of the component (a), the more excellent the chain transfer effect.

The α-methylstyrene dimer is an impurity such as unreacted α-methylstyrene, α-methylstyrene oligomer other than the above-mentioned components (a), (b) and (c), α-methylstyrene dimer, and α within a range not impairing the object of the present invention. -Methylstyrene polymer may be included.

When α-methylstyrene dimer is used, it can be used in an unpurified state after the synthesis of α-methylstyrene dimer as long as it does not impair the purpose.

As the other polymerization chain transfer agent used in combination with the α-methylstyrene dimer, a known polymerization chain transfer agent used in general emulsion polymerization can be used. In particular,
For example, mercaptans such as octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-hexadecyl mercaptan, n-tetradecyl mercaptan, t-tetradecyl mercaptan; dimethylxanthogen disulfide, diethylxanthogen disulfide, diisopropylxanthogen disulfide and the like. Xanthogen disulfides; tetramethyl thiuram disulfide, tetraethyl thiuram disulfide,
Thiuram disulfides such as tetrabutyl thiuram disulfide; halogenated hydrocarbons such as carbon tetrachloride and ethylene bromide; hydrocarbons such as pentaphenylethane; and acrolein, methacrolein, allyl alcohol, 2-ethylhexyl thioglycolate, Examples include terpinolene, α-terpinene, γ-terpinene, and dipentene. These may be used alone or in combination of two or more. Among these, mercaptans, xanthogen disulfides, thiuram disulfides, carbon tetrachloride and the like are preferably used.

The proportion of α-methylstyrene dimer in the polymerization chain transfer agent (I) is preferably 2 to 100% by weight, more preferably 3 to 100% by weight, and further preferably 5 to 95% by weight.

If the proportion of the α-methylstyrene dimer is less than 2% by weight, a copolymer latex having excellent adhesive strength, blister resistance and gloss cannot be obtained. Further, the combined use of α-methylstyrene dimer and another polymerization chain transfer agent can enhance the reactivity during polymerization.

The amount of the polymerization chain transfer agent (I) used is usually 0.05 to 20 parts by weight, preferably 0.1 to 10 parts by weight, and more preferably 0.3 to 7 parts by weight, based on 100 parts by weight of all the monomers. If the amount of the polymerization chain transfer agent (I) used is less than 0.05 parts by weight, the blister resistance will be poor, while if it exceeds 20 parts by weight, the adhesive strength will be decreased, which is not preferable.

The amount of α-methylstyrene dimer used is preferably in the range of 0.1 to 5 parts by weight per 100 parts by weight of all monomers.

Next, the polymerization chain transfer agent used in the second invention (hereinafter referred to as the polymerization chain transfer agent (II)) is at least one compound selected from (A) terpinolene, α-terpinene, γ-terpinene and dipentene. (Hereinafter referred to as “component (A)”) and other polymerization chain transfer agent used as necessary in (B), preferably selected from alkyl mercaptans, carbon tetrachloride, xanthogen disulfides and thiuram disulfides. And at least one compound (hereinafter referred to as “component (B)”).

Specific examples of the alkyl mercaptans of the component (B) include compounds similar to the above-mentioned alkyl mercaptans, and of these, t-dodecyl mercaptan is preferably used.

In addition, specific examples of the xanthogen disulfides and thiuram disulfides include the same compounds as the above-mentioned xanthogen disulfides and thiuram disulfides.

The proportion of the component (A) in the polymerization chain transfer agent (II) is preferably 2 to 100% by weight, more preferably 3 to 100% by weight, and particularly preferably 5 to 95% by weight. By using the component (A) and the component (B) together, the reactivity during polymerization can be increased.

The amount of the polymerization chain transfer agent (II) used is usually 0.05 to 2 parts by weight, preferably 0.1 to 10 parts by weight, and more preferably 0.3 to 7 parts by weight, based on 100 parts by weight of all the monomers. If the amount of the polymerization chain transfer agent (II) used is less than 0.05 parts by weight, the blister resistance will be poor, while if it exceeds 20 parts by weight, the adhesive strength will be decreased, which is not preferable.

The component (A) is preferably used in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of all monomers.

The copolymer latex in the present invention can be produced by a conventionally known emulsion polymerization method except that the above-mentioned monomer and polymerization chain transfer agent are used. That is,
It is obtained by adding a monomer, a polymerization initiator, an emulsifier, a polymerization chain transfer agent and the like to an aqueous medium (usually water) and carrying out emulsion polymerization.

There is no particular limitation on the polymerization initiator used in the emulsion polymerization in the present invention, for example, cumene hydroperoxide, diisopropylbenzene hydroperoxide,
Hydroperoxides such as paramenthane hydroperoxide, peroxides such as benzoyl peroxide and lauroyl peroxide, and organic polymerization initiators such as azo compounds such as azobisisobutyronitrile, potassium persulfate, and peroxides. Inorganic polymerization initiators such as persulfates such as sodium sulfate and ammonium persulfate can be used.

In the present invention, the copolymer latex obtained by using the organic polymerization initiator alone has poor mechanical stability,
Further, since a large amount of coagulated product is generated during the polymerization, it is preferable to use the inorganic polymerization initiator alone or in combination with the organic polymerization initiator.

The above polymerization initiator can also be used as a so-called redox polymerization initiator in combination with a reducing agent such as sodium bisulfite.

Among these polymerization initiators, persulfates such as potassium persulfate and ammonium persulfate, or a combination thereof with azobisisobutyronitrile or benzoyl peroxide, and a combination of these and a reducing agent are preferably used. To be done.

The amount of the polymerization initiator used in the present invention is usually 0.1-5 parts by weight, preferably 0.5-
2 parts by weight. When an inorganic polymerization initiator and an organic polymerization initiator are used in combination, the proportion of the organic polymerization initiator is preferably 70% by weight or less, more preferably 50% by weight or less, based on the total polymerization initiator. When the proportion of the organic polymerization initiator exceeds 70% by weight, there is a problem such as when the organic polymerization initiator is used alone, which is not preferable.

The emulsifier used for emulsion polymerization in the present invention is not particularly limited, and any of anionic, nonionic and amphoteric surfactants can be used. These may be used alone or in combination of two or more. For example, sulfate ester salts of higher alcohols such as sodium lauryl sulfate, alkylbenzene sulfonates such as sodium dodecylbenzene sulfonate, anionic surfactants such as sulfonates of aliphatic carboxylic acid esters such as sodium dioctylsulfosuccinate, polyethylene Nonionic surfactants such as alkyl ester type of glycol, alkyl phenyl ether type, and alkyl ether type can be used. Further, as the amphoteric surfactant, carboxylate, sulfate ester, sulfonate, phosphate as an anion moiety,
Examples thereof include phosphoric acid ester salts, and those having an amine salt or a quaternary ammonium salt as a cation moiety. Specifically, salts of lauryl betaine, stearyl betaine, cocoamidopropyl betaine, 2-undecyl hydroxyethyl imidazolium betaine as salts of alkyl betaines, and lauryl-β-alanine, stearyl-β as amino acid types. There may be mentioned salts of alanine, lauryldi (aminoethyl) glycine, octyldi (aminoethyl) glycine and dioctyldi (aminoethyl) glycine.

Of these emulsifiers, alkylbenzene sulfonate is particularly preferably used. More specifically, sodium dodecylbenzene sulfonate and the like are particularly preferably used. This alkylbenzene sulfonate is an anionic surfactant such as a sulfate of a higher alcohol, a sulfonate of an aliphatic carboxylic acid ester, or an alkyl ester type, an alkyl ether type, or an alkyl type of polyethylene glycol. You may use together with nonionic surfactants, such as a phenyl ether type.

The amount of emulsifier used is usually 0.05 per 100 parts by weight of all monomers.
To 2 parts by weight, preferably 0.05 to 1 part by weight.
If the amount of emulsifier used exceeds 2 parts by weight, the water resistance will deteriorate,
Foaming of the coating composition becomes remarkable, which causes a problem during coating. When alkylbenzene sulfonate is used in combination with other anionic or nonionic surfactants, the proportion of alkylbenzene sulfonate used is 50% of the total emulsifier.
It is preferable that the content is not less than wt%.

The emulsion polymerization method and conditions therefor in the present invention are not particularly limited, and can be carried out under conventionally known methods and conditions.

For example, the addition method of the polymerization chain transfer agent may be a batch addition method, a divided addition method, a continuous addition method, or a combination thereof.

The method of adding the monomer may be a batch addition method, a divided addition method, a continuous addition method, or a combination thereof. Among these methods, the divided addition method or the continuous addition method is preferable from the viewpoints of reducing the production of coagulated substances and removing reaction heat.

Furthermore, 10 to 50% by weight of the total amount of monomers, including all or part of the ethylenically unsaturated carboxylic acid monomer, is polymerized in the first stage, and the remaining monomer is 50 to 90% by weight in the second stage. According to the two-step polymerization method of continuously adding and emulsion-polymerizing, the production of coagulates in the polymerization step can be further reduced, and the coating composition intended by the present invention can be effectively obtained. It is preferable to carry out the emulsion polymerization of the present invention by this two-step polymerization method. In this method, the polymerization chain transfer agent may be added to either the first stage or the second stage, or to both. When the polymerization chain transfer agent is used in the second stage, it is preferably added continuously.

The gel content of the obtained copolymer latex is preferably 5% or more, more preferably 10 to 98%. If the gel content is less than 5%, the adhesive strength and the mechanical stability are greatly reduced, and further, the tackiness of the latex film is increased, which causes problems such as backing roll stains. Further, if the gel content exceeds 98%, the adhesive strength tends to decrease, which is not preferable.

The coating composition of the present invention has a solid content concentration of 58% by weight or more,
It is preferably 60% by weight or more, more preferably 65% by weight or more, and particularly preferably 67% by weight or more.

Although the coating composition of the present invention has a solid content concentration of 60% by weight or more, the coating composition has an appropriate viscosity, good fluidity, and adhesive strength and resistance. Excellent physical properties of coated paper such as blister and printing gloss. In the conventional technology, when the solid content concentration is set to 58% by weight or more to maintain good fluidity, sufficient coated paper properties cannot be obtained.For example, in the case of a paper coating composition, the solid content concentration is generally
Preparations have been made in the area of less than 58% by weight.

Since the coating composition of the present invention can have a high solid content concentration, it greatly contributes to improvement of productivity in the coating step and reduction of drying energy.

Furthermore, when calcium carbonate is used in the conventional coating composition, the finish and printability of the coated paper are inferior as compared with the case of using other pigments such as clay, whereas in the present invention, Even if a large amount of calcium carbonate is used, the same physical properties of coated paper as with clay can be obtained.
The use of inexpensive calcium carbonate can reduce the cost of the coating composition.

The coating composition of the present invention exerts the greatest effect when it is used for blade coating, but even if it is used in other coating methods, it exerts its effect sufficiently.

[Examples] The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples. In addition,
"Parts" and "%" shown in Examples mean parts by weight and% by weight unless otherwise specified.

(Manufacture of Copolymer Latex) As shown in Table 1, 100 parts of a pressure resistant reactor was used as the first-stage monomer mixture, 2 parts of itaconic acid, 1 part of acrylic acid,
Butadiene 10 parts, Styrene 18 parts, Methyl methacrylate 10
And 5 parts of acrylonitrile are charged, and water is added to 150 parts.
Parts, α-methylstyrene dimer 1.5 parts, sodium dodecylbenzene sulfonate 0.3 parts and potassium persulfate
After charging 1.0 part, polymerization was carried out at a temperature of 70 ° C. for 2 hours in a nitrogen atmosphere. Next, as a second-stage monomer mixture, 25 parts of butadiene, 21 parts of styrene, 3 parts of acrylonitrile and 5 parts of methyl methacrylate, and 1.5 parts of α-methylstyrene dimer were continuously added over 8 hours. Polymerization was carried out. Then, in order to complete the polymerization, the reaction was further continued for 3 hours, and the polymerization was completed at a polymerization conversion rate of 98%.

After adjusting the pH of the obtained copolymer latex to 7.5 with sodium hydroxide, steam is blown to remove unreacted monomers, and the solid content concentration is further reduced by heating under reduced pressure to 50%.
% Copolymer latex (a) was obtained.

The α-methylstyrene dimer used here and the α-methylstyrene dimer used below are as follows.

Product name: NOFMER MSD (Nippon Yushi Co., Ltd.) Composition Composition name Composition (wt%) 2-4-diphenyl-4-methyl-1-pentene 92.0% or more 2-4-diphenyl-4-methyl-2-pentene 5.0 % Or less 1-1-3-Trimethyl-3-phenylindane 1.5% or less α-methylstyrene 1.0% or less The polymerization formulation shown in Table 1 was used, except that the copolymer was prepared in the same manner as the copolymer latex (a). Latex (b)
(Wo) and (a) to (e) were manufactured. However, the copolymer latex (nu) is different from the copolymer latex (ii) in that the first-stage polymerization was carried out for 6 hours and the second-stage polymerization was carried out for 2 hours.

The copolymer latexes (a) to (wo) are copolymer latexes within the scope of the present invention, while the copolymer latexes (a) to (e) are copolymers outside the scope of the present invention. It is latex.

Examples 1 to 22, Comparative Examples 1 to 7 Pigments, water-soluble polymer compounds, dispersants, copolymer latexes of coating composition components shown in Tables 2 and 3 and respective coating solid content concentrations Water for the purpose was put into a Choles disperser and mixed to obtain a paper coating composition.

These paper coating compositions, so as to form a coating layer of 16 g / m ² , after coating and drying with a blade coater, finish with a super calender, coated paper for measuring the physical properties of coated paper. Obtained.

The coating composition physical properties (coating physical properties) and the coated paper physical properties were measured by the following test methods. The test results are shown in Tables 2 and 3.

Test method (1) Viscosity The initial viscosity was measured with a BM type viscometer (60 rpm, No. 4 spindle).

(2) High shear viscosity Hercules high shear viscometer (8800 rpm,
F Bob).

(3) Print glossiness 75 ° Measured with a Murakami glossmeter.

(4) Dry pick Using an RI printing tester, perform overprinting several times with a tack value of 15 inks, and visually check the picking state of the printing surface using the 5-point method. The higher the number, the better.

(5) Using a wet pick RI printer, water is applied on the test piece with a molton roll, and immediately after that, tack No. 16 is printed, and the picking degree is visually judged by the 5-point method. The higher the number, the better.

(6) Blister resistance After controlling the humidity of a double-sided coated paper (about 6%), it was thrown into a heating oil bath and the minimum temperature at which blister occurs was shown.

(7) Coating property Coating was performed with a blade coater manufactured by Kumagai Riki Kogyo Co., Ltd. at a speed of 600 m / min, and the control of the coating amount was difficult and the degree of streak was visually determined.

The judgment result was evaluated according to the following four grades.

⊚: Very good, ◯: Good, Δ: Inferior, ×: Very inferior Examples 1 to 22 are paper coating compositions within the scope of the present invention. The shear viscosity is within a range suitable for coating operability, and the effects of the present invention are obtained in terms of coating properties and coated paper physical properties.

Comparative Example 1 is an example in which the content of calcium carbonate in the pigment is less than the range of the present invention, and the physical properties of the coating are poor.

Comparative Example 2 is an example in which the content ratio of the water-soluble polymer compound exceeds the range of the present invention, and the physical properties of the coating are poor.

Comparative Example 3 is an example in which the ratio of butadiene in the copolymer latex is less than the range of the present invention, and the dry pick and the printing gloss are inferior.

Comparative Example 4 is an example in which the ratio of butadiene in the copolymer latex exceeds the range of the present invention, and the wet pick and printing glossiness are poor.

Comparative Example 5 is an example in which the proportion of ethylenically unsaturated carboxylic acid in the copolymer latex is less than the range of the present invention,
Poor coatability, dry pick, and printing gloss.

Comparative Example 6 is an example in which only t-dodecyl mercaptan was used as the polymerization chain transfer agent during the production of the copolymer latex, and the dry pick, wet pick, and print gloss were inferior.

Comparative Example 7 is an example in which only carbon tetrachloride was used as the polymerization chain transfer agent during the production of the copolymer latex, and the wet pick, print gloss and blister resistance were poor.

[Effect of the Invention] According to the coating composition of the present invention, good coating can be performed by using at a high solid content, and when used as a paper coating composition, adhesive strength, blister resistance, printing gloss, etc. It is possible to obtain a coated paper having further excellent physical properties, and it is also suitable as a carpet backing material and the like.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Masaaki Yada 2-11-24 Tsukiji, Chuo-ku, Tokyo Within Nippon Synthetic Rubber Co., Ltd. (72) Inventor Kazumi Yamawaki 2-11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd.

Claims (2)

[Claims] 1. Containing 100 parts by weight of a pigment containing at least 30% by weight of calcium carbonate, 0 to 10 parts by weight of a water-soluble polymer compound, and 5 to 50 parts by weight of the following copolymer latex (as solid content). A coating composition having a solid content concentration of 58% by weight or more. Copolymer latex; (a) 15 to 60% by weight of conjugated diene monomer, (b) 30 to 84.5% by weight of ethylenically unsaturated monomer, (c) 0 to 30% by weight of vinyl cyan compound monomer. A copolymer latex obtained by emulsion-polymerizing a monomer containing (d) 0.5 to 10% by weight of an ethylenically unsaturated carboxylic acid monomer in the presence of α-methylstyrene dimer. 2. Containing 100 parts by weight of a pigment containing at least 30% by weight of calcium carbonate, 0 to 10 parts by weight of a water-soluble polymer compound, and 5 to 50 parts by weight of the following copolymer latex (as solid content). A coating composition having a solid content concentration of 58% by weight or more. Copolymer latex; (a) 15 to 60% by weight of conjugated diene monomer, (b) 30 to 84.5% by weight of ethylenically unsaturated monomer, (c) 0 to 30% by weight of vinyl cyan compound monomer. , (D) 0.5 to 10% by weight of an ethylenically unsaturated carboxylic acid monomer, a monomer containing terpinolene, α-terpinene, γ
At least one selected from terpinene and dipentene
A copolymer latex obtained by emulsion polymerization in the presence of a seed compound.