JPH01223170A - Coating composition and cast-coated paper coated therewith - Google Patents

Abstract

PURPOSE:To obtain the title composition outstanding in releasability in the high-speed production of coated paper, free from developing pits, capable of imparting the cast-coated paper with high gloss and high surface strength, by incorporating a pigment with a latex and an acrylic emulsion each in specified proportion. CONSTITUTION:The objective composition can be obtained by incorporating (A) 100pts.wt. of a pigment with (B) 6-18pts.wt. on a solid basis, of a latex with a mean particle size of 0.1-0.3mm and (C) 3-12pts.wt. of an acrylic emulsion with a mean particle size of 0.5-1.5mum so as to total 9-30pts.wt. of the components B and C. The other objective cast-coated paper can be obtained by application of said composition.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a paint composition for cast-coated paper that can be produced at high speed, and to cast-coated paper coated with the composition.

(Prior Art) There are various methods for producing cast coated paper, such as a direct method, a coagulation method, and a rewetting method. The direct method is a method in which a water-based paint containing pigments and adhesive is applied to a base paper, and then dried by adhering it to a high-temperature specular drum (hereinafter referred to as a middle cast drum) in a wet state.The coagulation method is a method in which a coagulant is applied to the water-based paint. There are two methods: a method in which a water-based paint is applied to a base paper and then dried in close contact on a cast drum in a wet state, or a method in which a water-based paint is applied to a base paper, a coagulant is applied, and a coagulant is applied in a wet state and then dried in a close contact on a cast drum in a wet state. The rewetting method is a method in which a water-based paint is applied to base paper, once dried, rewetted, and then dried in close contact with a cast drum.

Therefore, whereas high-gloss art paper is supercalendered in a dry state, cast-coated paper is smoothed in a wet state, that is, in a state where the coating layer is highly layered, no matter which method is used. A coated surface with high smoothness and high gloss can be obtained.

However, it is necessary to bring the coated surface containing a large amount of water into close contact with the cast drum surface, dry it, and then release the coated surface from the cast drum surface without any resistance to obtain a coated surface with high gloss and no defects. This is an important requirement. Conventionally, good adhesion to the cast drum to give high gloss has the opposite effect of significantly reducing mold releasability. Producing cast-coated paper required advanced technology. In particular, when the mold release speed of the coated surface from the cast drum is increased for high-speed production, the mold release resistance also increases, and sometimes the paint film adheres to the drum and is partially picked up (hereinafter, defects on the coated surface that occur as a result of this will be investigated). A coated surface without defects (referred to as pits) and uniform gloss could not be obtained. Another point of interest during high-speed production is that the residence time of cast paper on the drum is shortened, and therefore, in the rewetting method, it is placed under high pressure on the cast drum to form a surface. At times, moisture forms a reservoir between the drum surface and the paint film, resulting in the formation of pits in the paint film that are different from the pits caused by pickup, which causes significant defects on the cast-coated paper. .

(Problem to be solved by the invention) Therefore, in order to solve the above-mentioned problems of cast coated paper and to enable high-speed production while maintaining coated surface quality.
Sulfates, nitrates, formates, acetates, etc. of zinc, aluminum, magnesium, etc. are added as coagulants to paints whose main components are pigments and adhesives such as latex and casein, which contain pigments and unsaturated cardenes as monomer components. A method has been proposed (Special Publication No. 6O-146097), but
Even if this method is used, the production rate is still low and insufficient9.

The present invention provides a coating composition and a product coated with the composition, which makes it possible to obtain cast-coated paper with excellent mold release properties, no pitting, high gloss, and good surface strength even through unprecedented high-speed production. Our goal is to provide cast coated paper.

(Means for Solving the Problem) As a solution to the above problem, in a paint for cast coat paper containing a pigment and an adhesive as main components, an average amount of the adhesive is added to 100 parts by weight of the pigment. The solid content of latex particles with a particle size of 0.1-0.3 μm is 6
-18 parts by weight of acrylic emulsion with an average particle size of 0.5-1.5 pm] in solid content of 3-12 parts by weight,
Furthermore, a coating composition for cast coated paper containing 9 to 30 parts by weight of latex (1) and acrylic dimarc, 7@ as a solid content, and a medium cast coated paper coated with the composition are provided.

In the present invention, for 100 parts by weight of pigment,
) The reason for specifying the use of a total of 9 to 30 parts by weight of two types of synthetic binders in terms of solid content is that the cast-coated paper of the paint obtained by using less than 9 parts by weight of the total amount of synthetic binders. The surface strength is so low that it cannot withstand practical printing, and if the total amount of Synthetic/4 Ingu is used in excess of 30 parts by weight, this may result in poor separation of the paint from the drum surface of the cast coated paper. This is because high-speed production, which is the object of the present invention, becomes difficult. The total amount of preferred synthetic binder used is 10-25 parts by weight.

In addition, in the present invention, the reason why the amount of latex particles used for 100 parts by weight of pigment is limited to 6-18 parts by weight in terms of solid content is that if the latex (1) is less than 6 parts by weight, The surface strength of the coated cast coated paper is low, and if the amount of latex (4) exceeds 18 parts by weight, the release properties of the coated paper from the cast drum surface are poor, and the air permeability is also low. This is because there will be more pits on the construction surface. The amount used in the preferred latex is 7-16 parts by weight.

Furthermore, in the present invention, the reason why the amount of acrylic emulsion 0) used is limited to 3-12 parts by weight in terms of solid content per 100 parts by weight of the pigment is that the amount of acrylic emulsion 0) used is less than 3 parts by weight. In this case, the adhesion of the coated paper to the cast drum surface is poor, the gloss is reduced, and there are many pits.If the amount of acrylic emulsion 0) used exceeds 12 parts by weight, the release property from the cast drum is poor. Then, the obtained cast coat W pits are generated. The preferred amount of acrylic emulsion (B) used is 4-10 parts by weight.

In the present invention, the average particle size of latex) is 0.1
The reason for limiting the value to −0.3 μm is that the average particle diameter is 0.1 μm.
If it is less than m, even if the average particle diameter of acrylic emulsion ω) is 0.5-1.5 μm, the viscosity of the resulting paint will be high and the releasability of the coated paper from the cast drum surface will be poor. It is difficult to obtain a smooth coated surface with no sivit. On the other hand, if the average particle size of latex (4) exceeds 0.3 μm, cast-coated paper coated with paint using latex (4) will have low surface strength and will have many pits, making it difficult to achieve high-speed production, which is the objective of the present invention. It becomes atrocious.

In addition, in the present invention, the reason why the average particle size of acrylic emulsion 0) is limited to 0.5-1.5 μm is that if the average particle size of acrylic emulsion (B) is less than 0.5 μm, it cannot be used. The cast-coated paper used as the paint had low air permeability and many pits occurred, making high-speed production difficult.Also, the average particle size of acrylic emulsion (8) was 1.5 μm.
If it exceeds 9 m, the surface strength of the cast-coated paper coated with the paint using this material will be extremely low, making practical printing impossible. Latex prisoner and acrylic emulsion here 0
It is important that the average particle size of ) is the same as described above in the step after preparing the paint composition, and the synthetic binder alone before being added to the paint does not necessarily have to have this particle size. For example, latex ■ is synthesized to have a particle size of 0.1-0.3 μm with excellent chemical stability, and separately 0.1-0.3 μm.
After synthesizing acrylic acid with a particle size of 0.3 μm, agglomeration is performed by adding a small amount of polyvalent metal cations such as calcium ions and aluminum ions so that the average particle size becomes 0.5-1.5 μm. The acrylic emulsion prepared and then stabilized by adding a surfactant or a protective colloid is designated as (B), and is treated in this way with [! When we observed the state of the paint using the synthetic binder 111 at each adjustment stage using a transmission electron microscope, we found that the synthetic binders 1 and 2 each independently maintained the particle size at the time of adjustment. This was confirmed by the difference in particle density. In other words, latex ■ exists as a dark image and stands alone, and acrylic emulsion (B)
) were present in a state where they were aggregated in large numbers with a faint image. This adjustment method is just one example, and it is also possible to control the particle size during the paint mixing process. The acrylic emulsion converted into the acrylic emulsion V11) (A) of the present invention by the agglomeration operation is referred to as the acrylic emulsion precursor). Ti
Although acrylic emulsion (acrylic emulsion carbonate) can be manufactured to have a particle size within the claimed range of the present invention during synthesis, it is not economical.

In the present invention, latex is a general term for rubber-based emulsions, and in that sense, the components contained in latex include diene monomers such as putazoene, isogren, and 2-butadiene as essential components. , acrylic acid resin is a general term for polymer emulsions that do not contain these diene monomers and are mainly composed of the monomers described below. In latex, aromatic alkenyls such as styrene, α-methylstyrene, chlorostyrene, dimethylstyrene, etc. are used as copolymerized monomer components other than diene monomers, and as main monomer components in acrylic emulsion. Compounds and methyl acrylate, ethyl acrylate, tutyl acrylate, 2-ethylhexyl acrylate, glycidyl acrylate, methyl methacrylate, ethyl methacrylate, methyl methacrylate, 2-ethylhexyl methacrylate, hydroxyethyl methacrylate, hydroxy methacrylate Globil, glycidyl methacrylate, ethyl acrylate, N-methylolacrylamide, N-methoxymethylacrylamide, methacrylamide, N-methylolmethacrylamide, N-methoxymethylmethacrylamide, acrylic acid, methacrylic acid, crotonic acid, fumaric acid in alcohol Monoolefinic unsaturated compounds such as polyester, itaconic acid alkyl ester, acrylonitrile, methacrylonitrile, and vinyl acetate are used as monomers, but two or more of these monomer components can also be used in combination.

In the production of the synthetic binder of the present invention, the above-mentioned monomers are used, and as a polymerization initiation catalyst, a common initiator such as a water-soluble peroxide such as potassium persulfate, sodium persulfate, ammonium persulfate, etc., or these and bisulfite are used. It is also possible to use it in combination with a water-soluble reducing agent such as soda, sodium sulfite, and sodium thiosulfate. The polymerization temperature of the monomers is usually 50-100°C, and the pressure is in the range of O-10Kf/II'' in Guzo pressure.All the monomers used can be added at once, in parts, or continuously. In addition, to stabilize the particles during polymerization, emulsifiers such as alkylbenzene sulfone sodium sulfate, alkyl sodium sulfate, and alkyl alcohol sodium sulfate, diethyl cellulose in hydrochloride, carboxymethyl cellulose, and vinyl alcohol, etc. can be used. It is also possible to add a protective colloidal agent.At this time, if the amount of the emulsifier added to the total monomers is increased, the particle size becomes smaller, and as the amount is reduced, the particle size becomes larger.Also, as a molecular weight regulator, an alkyl This can be carried out using mercaptans such as mercaptan and tertiary mercagutan, carbon tetrachloride, higher alcohols, etc. Therefore, with the above structure and production method, the particle size of the present invention is o, io, 3 μm.
and 0.5-1.5 μm synthetic binder compositions can be freely prepared.

The latex and acrylic emulsion used in the present invention preferably contain at least a certain amount of toluene-insoluble content (usually referred to as the R content) of the dry film, which is related to the molecular weight and degree of crosslinking of the remer. In order to ensure high-speed productivity for the purpose of this, it is preferable that the content is 15% by weight or more. Pigments used in paints include clay, calcium carbonate, titanium white, black/white, aluminum hydroxide, barium sulfate, zinc oxide, magnesium oxide, and other inorganic pigments and glass pigments that are normally used in coated paper. , white urea resin pigments, etc., can all be used, and for the purposes of the present invention, there are no particular restrictions on the selection of pigments.

In addition to the above-mentioned synthetic binders ① and 0), the adhesive contains water-soluble polymers such as casein and modified starch as pigments 1 in the paint.
2-15 parts by weight can be used for 00 parts by weight.

In addition, known coagulants such as calcium formate, magnesium formate, zinc formate, calcium acetate, magnesium acetate, zinc acetate, etc., or known mold release agents such as magnesium stearate, zinc stearate, etc. may be appropriately used in the coating composition of the present invention. You can. In order to stably maintain the agglomerated state of the particles of acrylic resin in the paint, anionic surfactants, nonionic surfactants, etc. are added to the paint composition in addition to the pre-contained stabilizers. You can also do that.

The medium coated paper of the present invention is prepared by applying the coating composition of the present invention obtained by K. to the base paper with an air knife, once drying it, and then rewetting it with humidifying water at 60'C (function) as described in the above detailed explanation. In the paint composition obtained according to the present invention, that is, the paint for cast coat paper containing pigment and adhesive as main components, the total amount of two types of latex (4) and acrylic emulsion 01) in the paint is pigment 100
9-30 parts by weight are used, and the particle size of each synthetic binder is 0.1-0.3 am.
01) is 0°5-1.5μm, latex prisoner is 6-1
8 parts by weight, 3 to 12 parts by weight of acrylic emulsion (A) Ti was coated by a known method and dried in close contact with a cast drum. Cast-coated paper has excellent surface gloss and uniform surface quality with no bits, and also has excellent air permeability and mold release properties, making high-speed production possible. The coating composition of the present invention is also useful as a paint for cast-coated paper by a direct method, a coagulation method, or the like other than the rewetting method.

It will be explained in more detail below by giving Examples and Comparative Examples, etc.
The present invention is not limited in any way by these Examples. In addition, parts and weights in these are based on 9 weight unless otherwise specified.

Example 1 First, an example of manufacturing the latex (4) and acrylic emulsion resin (B) used in this example will be shown, and then an example of preparing the paint will be shown.

Production example of latex (A-1)> 120 parts of deionized water in a nitrogen-substituted autoclave,
Sodium dodecylbenzenesulfonate 0.2 part, potassium persulfate 0.8 part, tertiary dodecyl mercaptan 0.
6 parts, monomer composition: butadiene 40 parts, styrene 4 parts
5 parts, 8 parts of methyl methacrylate, and 2 parts of acrylic acid, 2 parts of acrylamide, and 3 parts of hydroxyethyl methacrylate as functional group monomers, for a total of 100 parts.
Polymerization was carried out at 01, and the polymerization rate was 98 15 hours after the start of polymerization.
When the temperature exceeds 9, the reaction is stopped, cooled, and then hydroxylated) 17
The - value was adjusted to 7 using a microcentrifuge to obtain latex (A-1).

The particle size was 0.15 μm.

<Production example of precursor of acrylic emulsion (B)> In a nitrogen-substituted tri-glass reactor, 120 parts of deionized water, 0.1 part of sodium dodecylbenzenesulfonate, and 0.8 part of ammonium persulfate were added. A total of 100 parts of monomer composition: 40 parts of butyl acrylate, 50 parts of styrene, 7 parts of methyl methacrylate, and 3 parts of methacrylic acid was prepared at 70°C.
8 hours after the start of polymerization, the polymerization rate exceeded 97%, so the reaction was stopped, and after cooling, - was adjusted to 7 with an ammonia aqueous solution to obtain a precursor of acrylic emulsion (B). .

The particle size was 0.18 μm.

<Preparation of paint> 53.3 parts of casein/aqueous solution obtained by heating and dissolving 28 parts of ammonia water, 8 parts of milk casein, and 44.5 parts of water (equivalent to 8 parts in terms of solid content) ) and water 100
1 part was put into a colorless mixer, and while stirring, 40 parts of calcium carbonate (manufactured by Okutama Kogyo: TP-222H8) and 60 parts of Oyohikaoriy (manufactured by EMC: UW-90) were added and mixed and dispersed. (equivalent to 0.7 parts in terms of solid content) and then add latex (A
12 parts of solid content of -1) and 7 parts of a precursor of acrylic emulsion C) were added.

Finally, the solid content of the coating material was adjusted to 40% to obtain a coating composition-1 for cast coated paper of the present invention. The viscosity of the paint was measured using a Brookfield viscometer at 25°C, 60r, and p4, and the result was 30 eps.

In addition, as a result of checking the particle size of the synthetic binder in the paint using a transmission electron microscope, the particle size of the latex (Mu-1) was 0.
．． The particle size of the acrylic emulsion resin was 0.85-1.0 μsK, whereas the particle size of the acrylic emulsion resin was 15 μm. Table-IK shows the raw material blending ratio and physical properties of these coating compositions-1.
Indicated.

Example 2-7 Casein amount and latex (A-
The process and conditions were exactly the same as in Example 1, except for the addition amount and total amount of the precursors of 1) and acrylic dimark 1n Φ), and the addition amount of calcium acetate as shown in Table IK. Each coating composition from coating composition-2 to coating composition-71 was obtained. Solid content concentration of these compositions, Brookfield viscosity, latex in paint (A-1)
The particle diameter of the acrylic emulsion and the acrylic emulsion (ω) were also measured and observed in the same manner as in Example 1, and the results are shown in Table IK.

Example 8 An example of manufacturing the latex (A-2) used in this example will be shown, followed by an example of preparing the paint.

<Production example of latex (A-2)> 120 parts of deionized water in a nitrogen-substituted autoclave,
Sodium dodecylbenzenesulfonate 0.3 parts, potassium persulfate 0.8 parts, tert-dodecyl/ni-hftan 0
．． 6 parts, 21,740 parts of ivy as a monomer composition, 45 parts of styrene, 8 parts of methyl methacrylate, and 2 parts of acrylic acid, 2 parts of acrylamide, and 3 parts of hydroxyethyl methacrylate as functional group monomers, a total of 100 parts, and polymerized at 70 ° C. 14 hours after the start of polymerization, the polymerization rate was 9.
Since it exceeded 8%, the reaction was stopped, and after cooling, the temperature was adjusted to 7 with sodium hydroxide to obtain latex (A-2). The particle size was 0.1 μm.

<Preparation of paint> 53.3 parts of casein aqueous solution obtained by heating and dissolving 0.8 parts of 28% ammonia water, 8 parts of milk casein, and 44.5 parts of water (equivalent to 8 parts in solid content) and water 100
1 part was put into a colorless mixer, and while stirring, 40 parts of calcium carbonate (manufactured by Okutama Kogyo: TP-222H8) and 60 parts of kaolin (manufactured by EMC: sales-90) were added and mixed and dispersed, and then 1.5 parts of a 20% calcium acetate aqueous solution was added. (equivalent to 0.3 parts in terms of solid content) and then add latex (A-
12 parts (solid content) of 2) and 7 parts (solid content) of the precursor of acrylic emulsion 0) were added. Finally, increase the paint solids content to 40%.
The coating composition for cast coated paper of the present invention is adjusted to -
I got 8.

The viscosity of the paint was measured using a Brookfield viscometer at 25°C and 60°C.
The result of measurement under r, pen conditions was 115 cp-. When the particle size of the latex in the paint was confirmed using a transmission electron microscope, the particle size of the latex (A-2) was 0.1 μm, whereas the particle size of the acrylic emulsion (B) was was 0.5-0.7 μm.

The raw material blending ratio and physical properties of these coating compositions-8 are listed below.
Showed IK.

Example 9 A coating composition-9 was obtained in exactly the same manner and under the same conditions as in Example-8, except that the amount of calcium acetate added was changed as shown in Table-1. The solid content concentration, Brookfield viscosity, and particle size of latex (A-2) and acrylic emulsion 0) in the paint of these compositions were also measured and observed in the same manner as in Example-8. The results are also shown in Table-1.

Example 10 An example of manufacturing the latex (A-3) used in this example will be shown, and then an example of preparing the paint will be shown.

゛Production example of latex (A-3)〉 120 m of deionized water in a nitrogen-substituted autoclave
, 0.15 parts of dodecylbenzene sulfo/acid soda, 0.8 parts of potassium persulfate, 0.6 parts of tertiary dodecyl mercagutan, and the monomer composition of 40 parts of Tutageno, 45 parts of styrene, 8 parts of methyl methacrylate, and functional A total of 100 parts of 2 parts of acrylic acid, 2 parts of acrylamide and 3 parts of hydroxyethyl methacrylate were charged as base monomers and polymerized at 701.The polymerization rate exceeded 98% 16 hours after the start of polymerization, so the reaction was stopped and after cooling. The - was adjusted to 7 with sodium hydroxide to obtain latex (A-3).

The particle size was 0.3 μm.

Preparation of paint> 53.3 parts of casein aqueous solution obtained by heating and dissolving 0.8 parts of 28% ammonia water, 8 parts of milk casein, and 44 parts of water (equivalent to 8 parts in terms of solid content) and water 100
1 part was put into a colorless mixer, and while stirring, 40 parts of calcium carbonate (manufactured by Okutama Kogyo: TP-222H8) and 60 parts of kaolin (manufactured by EMC H-90) were added and mixed and dispersed, followed by 1.5 parts of a 20% aqueous calcium acetate solution. (equivalent to 0.3 parts in terms of solid content) and then add latex (A-3
) was added in a solid content of 12 parts and a precursor of acrylic emulsion resin (A) was added in a solid content of 7 parts. Finally, the coating composition for medium coated paper of the present invention was prepared by adjusting the coating solid content to 40%.
Got 10.

The viscosity of the paint was measured using a Brookfield viscometer at 25°C and 60°C.
The result measured under the conditions of r, p, and m was 35 cps. In addition, as a result of checking the particle size of latex in the paint using a transmission electron microscope, the particle size of latex (A-3) was 0.3μ, whereas acrylic emulsion 1 was 0.3μ.
) had a particle size of 0.5-0.7 μmnK.

Table 1 shows the blending ratio of raw materials, physical properties, etc. of these coating compositions-10.

Example 11 Coating composition-11 was obtained in exactly the same manner and under the same conditions as in Example-10, except that the amount of calcium acetate added was changed as shown in Table-1. The solid content concentration, the viscosity of pulsing feet/l', and the particle diameter of the latex (A-3) and acrylic emulsion in the paint of these compositions were also measured in the same manner as in Example 10. The results were also shown in Table 1.

Comparative Example 1-6 In Example-1, the amount of casein and calcium acetate used were changed, and the amount or total amount of the precursor of latex (A-1) and acrylic emulsion (B) was changed. As shown in Table 1, each comparative coating composition from Comparative Coating Composition-1 to Comparative Coating Composition-61 was prepared in exactly the same manner and under the same conditions as in Example 1, except that these were outside the scope of the present invention. The solid content concentration, Brookfield viscosity, and particle size of latex (A-1) and acrylic emulsion carbon 0) in the paints are also shown in Table 1.

Comparative Examples 7 and 8 In this comparative example, in order to further clarify the usefulness of the combination of latex (A-1) and acrylic emulsion (B), latex (A-1) and acrylic emulsion (B) were combined. A case where each of B) is used alone will be exemplified.

That is, as shown in Table 1, the procedure was the same as Example 1, except that the amount of calcium acetate used in Example 1 was changed, and the latex and acrylic emulsion used were each used in the same amount as the total amount. Comparative coating compositions according to procedures and conditions
7 and comparative coating composition-8 were obtained. Table 1 also shows the solid content concentration, Brookfield viscosity, and particle size of the latex and acrylic emulsion in the paint.

Comparative Example 9 An example of manufacturing the latex (A-4) used in this comparative example will be shown, followed by an example of preparing the paint. Example of manufacturing latex (A-4)> 120 ml of deionized water was placed in an autoclave purged with nitrogen.
S, 0.4 parts of dodecylbenzenesulfonated soda, 0.8 parts of potassium persulfate, 0.6 parts of tertiary dodecyl mercaptan, and monomer composition of 40 parts of butadiene, 45 parts of styrene, 8 parts of methyl methacrylate, and functional group monomers. A total of 100 parts of 2 parts of acrylic acid, 2 parts of acrylamide and 3 parts of hydroxyethyl methacrylate were charged and polymerized at 70°C. The polymerization rate exceeded 99% 13 hours after the start of polymerization, so the reaction was stopped and after cooling, hydroxide)
The latex (A-4) was adjusted to 7 using an IJ rim, and the particle size was 0.08 μm.

Preparation of paint> Using 0.8 parts of ammonia water, 8 parts of milk casein, and 44.5 parts of water, 53.3 parts of an aqueous casein solution was obtained by heating and dissolving 28 parts of ammonia water (equivalent to 8 parts in terms of solid content). and water 100
1 part was put into a cuffless mixer, and while stirring, 40 parts of calcium carbonate (manufactured by Okutama Gyo: TP-22218) and 60 parts of Kao IJ 7 (manufactured by KMC: tJW-90) were added, mixed and dispersed, and latex (A-4) was added. ) was added in a solid content of 12 parts and a precursor of acrylic emulsion (A) was added in a solid content of 7 parts. Finally, the solid content of the paint was adjusted to 40% to obtain Comparative Paint Composition-9. The result of measurement using a paint viscosity Brookfield viscometer under the conditions of 25° C. s 60 r*p*m was 460 apl. In addition, as a result of checking the particle size of latex in the paint using a transmission electron microscope, it was found that latex (
The particle diameter of the acrylic emulsion (Mo-4) was 0.08 μm, and the needle diameter of the acrylic emulsion (N-4) was 0.18 μm. The blending ratio of raw materials, physical properties, etc. of these comparative coating compositions-9 are shown in Table-IK.

Comparative Example 10 An example of manufacturing the latex (A-5) used in this comparative example will be shown, followed by an example of preparing the paint. <Example of manufacturing latex (A-5)> 120 parts of deionized water was placed in an autoclave purged with nitrogen. ,
Dodecylbenzenesulfonated soda 0.1 part, potassium persulfate 0.8 part, tertiary dodecyl mercaptan 0.1 part.
6 parts and monomer composition: 40 parts of butanoef, 4 parts of styrene.
5 parts, 8 parts of methyl methacrylate, and 2 parts of acrylic acid, 2 parts of acrylamide, and 3 parts of hydroxyethyl methacrylate as functional group monomers, for a total of 100 parts.
Polymerization was carried out at 0°C and the polymerization rate was 97 18 hours after the start of polymerization.
%, the reaction was stopped and after cooling, the pH was adjusted to -7Kg with sodium hydroxide! *L, latex (A-5) was obtained, and the particle size was 0.35 μm.

<Preparation of paint> 53.3 parts of casein aqueous solution obtained by heating and dissolving 0.8 parts of 28% ammonia water, 8 parts of milk casein, and 44.5 parts of water (equivalent to 8 parts in terms of solid content) and water 100
of calcium carbonate (manufactured by Okutama Kogyo: TP-222Ha) and 60 parts of Kaori Y (EMCM: UW-90) were mixed and dispersed.
(equivalent to 1.4 parts in terms of solid content), then add 12 parts of latex (A-5) in terms of solid content and 1 part of acrylic emulsion (equivalent to 1.4 parts in terms of solid content).
7 parts solids of the precursor of B) were added.

Finally, the solid content of the paint was adjusted to 40'16 to obtain comparative paint composition-1O. The viscosity of the coating material was measured using a Brookfield viscometer at 25° C.% 60 r, p, m and was found to be 25 cps. In addition, the particle size of latex in the paint can be measured using transmission electronics! 11 The particle size of the latex (A-5) was 0.35 μm, while the particle size of the acrylic emulsion (B) was 1.08-2 μm.
．． It became 16 μm. These comparative coating compositions-1O
The raw material blending ratio, physical properties, etc. are shown in Table IK.

Application Example The coating compositions obtained in the above Examples and Comparative Examples were
．． Using an air knife coater, each coating composition was coated to a dry weight of 25 t/m"K using a base paper of 250 m/m", and after drying, a rewetting solution was applied and the coating was passed through a casting drum. Casting diameter 12000゜press pressure 50Kt
/α and a drum with a surface temperature of 95 to 100° C., the maximum casting speed at which mold release was good and no pits were observed on the coated paper surface was determined. In addition, the air permeability of the coated paper before casting was measured, and the glossiness and surface strength of the cast coated paper were evaluated, and these results are tabulated.
9 shown in 2. The air permeability was measured using an Oken air permeability tester, and the gloss was measured according to JIS P-8142. The surface strength was evaluated by printing with an RI printing tester (manufactured by Mei Seisakusho) and visually observing the picking state of the surface (10 being the best with no picking on the surface, 1 being the best with no picking on the entire surface). occurred and was the worst, and this period was divided into 10 levels for evaluation).

Table - (Effects of the Invention) As shown by the numerical values in Table 2, the coating composition of the Example within the limited range of the present invention was manufactured at high speed, but the cast-coated paper made from this K layer had a high gloss and surface strength. It has an excellent balance of quality and air permeability. From this, it is clear that the present invention is an unprecedented and extremely useful coating composition for cast coated paper.

Claims (2)

[Claims] (1) In a paint for cast coat paper containing a pigment and an adhesive as main components, the adhesive has an average particle diameter of 0.1-0.3 μm per 100 parts by weight of the pigment.
Latex (A) is mixed into an acrylic emulsion (solid content: 6-18 parts by weight and an average particle size of 0.5-1.5 μm).
3-12 parts by weight of B) as solid content, and latex (A)
and acrylic emulsion (B) with a solid content of 9-30
A coating composition for cast coated paper containing parts by weight. (2) Cast coated paper coated with the composition according to claim 1.