JP2764061B2 - Coating composition for coated paper - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a coating composition for cast coated paper, and more particularly to a coating composition for cast paper capable of producing cast coated paper having excellent glossy surface and printability. And a method for producing cast coated paper using the same.

[Conventional technology]

As a method for producing a cast-coated paper, a direct method in which a coating composition for coated paper is applied to a base paper and pressed in a wet state while being pressed against a heated mirror drum, and a wet-coated paper coated on the base paper After the coating composition for coagulation is coagulated, a coagulation method of pressing and drying with a heated mirror-surface drum, and coating the coating composition for coated paper on base paper, once drying or semi-drying, and then re-wetting, There is a rewet method or the like in which pressure drying is performed using a heating mirror drum.

In any of these three methods of producing a cast-coated paper, the coating composition for coated paper containing a pigment and an adhesive as main components is pressed and dried on a heating drum in a wet state and peeled from a mirror surface. They are common in that they provide a high-gloss, uniform cast surface.

For the purpose of improving the quality and productivity of the cast cast paper to be obtained, a coating composition for a coated paper containing a pigment and an adhesive as a main component in advance as a base paper is coated and dried, such as a general coated paper and a lightweight coated paper. There is also a method in which a small amount of a coating composition for cast-coated paper is applied to the surface of a processed paper, dried under pressure on a heating drum, and peeled off from the mirror surface to obtain a high-gloss and uniform cast surface.

[Problems to be solved by the invention]

The present invention relates to a cast-coated paper that can produce a high-gloss cast paper having a uniform cast surface without producing defects such as pinholes, blisters and drum picks. And a method for producing a cast-coated paper using the same.

[Means for solving the problem]

The present invention is directed to a cast-coated paper coating material containing a pigment and an adhesive as a main component, wherein the adhesive is an aqueous urethane resin and a cast rubber coated with a synthetic rubber latex containing an aliphatic conjugated diolefin-based monomer. By using the coating composition, a coat layer having excellent surface gloss can be obtained, and pinholes and blisters can be eliminated, and at the same time, a strong adhesive strength can be imparted. This makes it possible to produce cast paper having high gloss and excellent printability and abrasion resistance.

That is, the present invention provides a synthetic rubber latex comprising 70 to 95% of an aliphatic conjugated diolefin-based monomer, an olefin-based aromatic monomer, and / or an olefin-based monomer as an adhesive, and 5 to 30% by weight of an aqueous urethane resin. A method for producing a coating composition for cast-coated paper, characterized by using:

Further, the present invention will be described in detail. As the aqueous urethane resin used in combination with the synthetic rubber latex used as an adhesive, an emulsion, a colloidal dispersion, a polyurethane resin stably present in water in the form of an aqueous solution or the like is used. Is done.

Aqueous urethane resins include, for example, isocyanates such as toluene diisocyanate, 4,4'-phenylmethane diisocyanate, xylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and neopentyl glycol, 1,4-butanediol, 1,6- Nonionic type obtained by urethane reaction with polyols such as hexanediol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyester polyol, polycarbonate polyol, polyethylene glycol, etc .; and tertiary such as N-methyldiethanolamine Suitable are those of the cationic type using an amine and the anionic type using, for example, dimethylolpropionic acid.

Furthermore, polymerizing with amines such as triethylamine, dimethylethanolamine, etc., or crosslinking using a water-soluble amino resin such as methylated melamine resin, aziridine, epoxy resin or zinc complex, etc. You may.

The synthetic rubber latex used in the present invention is usually composed of a latex commonly called SBR latex, MBR latex or SMBR latex, which is used as an adhesive in a paper pigment coating composition.

That is, the aliphatic conjugated diolefin-based monomer accounts for 30 to 60% by weight, preferably 35 to 55% by weight of all constituent polymer components.
Wherein the olefin-based aromatic monomer and / or the mono-olefin-based monomer comprises 70% of all constituent polymer components.
-40% by weight, preferably 65-45% by weight.

When the amount of the aliphatic conjugated diolefin-based monomer is 30% by weight or less, the surface of the cast paper obtained by the present invention is reduced,
On the other hand, when the content is 60% by weight or more, the releasability of the obtained binder for coated paper paint is lowered and the gloss is insufficient.

As the constituent polymer component, a monomer such as butadiene and styrene or / and methyl methacrylate is used as a main component, and if necessary, another monomer copolymerizable therewith is used.

Examples of the copolymerizable monomer include aliphatic conjugated diolefin monomers such as isoprene and 2-chlorobutadiene, olefin aromatic monomers such as α-methylstyrene, chlorostyrene and dimethylstyrene,
Methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylic acid 2
-Ethylhexyl, glycidyl (meth) acrylate,
There are monoolefin monomers such as (meth) acrylonitrile and monomers such as vinyl acetate.

Also, if necessary, for example, olefinic unsaturated hydroxy monomers such as hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, acrylamide, methacrylamide, N-methylolacrylamide, N -Monomers of olefinically unsaturated amide monomers such as methylol methacrylamide, N-methoxymethyl acrylamide, N-methoxymethyl methacrylamide and the like can be used alone or in combination of two or more.

These monomers are only examples, and any other copolymerizable monomers can be used.

In the present invention, the pigments used in the coating composition for cast-coated paper include clay, light calcium carbonate, heavy calcium carbonate, titanium oxide, aluminum hydroxide, satin white, barium sulfate, oxidized oxide used in ordinary coated paper. Inorganic pigments such as magnesium, talc and colloidal silica, and organic pigments such as plastic pigment and white urea resin pigment can all be used, and usually two or more kinds are used in combination.

The aqueous urethane resin and latex as the adhesive are preferably used in an amount of 10 to 30 parts by weight based on 100 parts by weight of the pigment, similarly to the amount of the adhesive usually used in cast coated paper.

The aqueous urethane resin and latex of the present invention are water-soluble polymers having adhesive properties, such as casein, oxidized starch,
Phosphorylated starch, soybean protein, carboxymethylcellulose, hydroxyethylcellulose and the like are added in an amount of at least 5 parts by weight, preferably 5 parts by weight, per 100 parts by weight of the pigment.
It is effective to use up to 10 parts by weight.

In addition, it is also effective to add auxiliary agents such as an antifoaming agent, a dispersant, a water-proofing agent, a preservative, a coloring agent, a coagulant, and a release agent as necessary.

The coating composition for coated paper thus obtained is coated in the same manner as general coated paper production, for example, by a coating apparatus such as an air knife coater, a blade coater, a roll coater, and a bar coater. At this time, the solid content concentration of the coating composition for coated paper is 40 to 65% by weight.

As the base paper, generally for coated printing paper and cast-coated paper, high quality paper having a basis weight 40~300g / m ^2, medium-grade paper, paperboard or the like and, to, in advance one or both sides, Coated paper or the like obtained by applying and drying a coating composition is used as a base paper.

The amount of the base paper to be coated with the coating paper composition is usually 10 to 25 g / m ^{2 on} one side by dry weight.

After being coated in this manner, a mirror surface is formed by a direct casting method, a solidification casting method, a rewetting casting method, or a combination thereof.

As described above, in the coating composition for coated paper obtained by the present invention, that is, the coating composition for cast-coated paper containing pigments and adhesives as main components, 5-30% by weight of an aqueous urethane resin is used as the adhesive. A coating composition for cast-coated paper, in which 70 to 95% of a synthetic rubber latex containing an aliphatic conjugated diolefin-based monomer and the like is used in combination, is coated by a known method and dried by close contact with a mirror drum. The cast-coated paper has high surface gloss, strength and abrasion resistance, and can be manufactured with a uniform surface quality without pinholes or blisters.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

The parts and percentages used in the examples below are based on weight unless otherwise specified.

Example 1 50 parts of kaolin (manufactured by EMC: UW90), 50 parts of calcium carbonate (manufactured by Okutama Kogyo: Tamapearl TP222HS), and 0.2 parts of sodium pyrophosphate as a dispersant were added, and dispersed in water using a Cowles disperser to give a concentration of 70. % Pigment slurry was prepared.

Next, 0.2 part of tributyl phosphate and 0.1 part of Pluronic L-61 (manufactured by Asahi Denka) as antifoaming agents, 1.0 part of calcium stearate as a releasing agent, and 5 parts of casein heated and dissolved by adding ammonia water as an adhesive, Aqueous urethane resin (Mitsui Toatsu Chemical: Orestar UD100N) 2
Part, SBR latex (Mitsui Toatsu Chemical: Polylac 51
5) Add 13 parts, and finally add water, solid content concentration 50%
To obtain a coating composition for a cast coat of the present invention (hereinafter referred to as a coating composition of Example 1).

In addition, the viscosity of the obtained coating composition was measured by a BM type viscometer (manufactured by Tokyo Keiki Co., Ltd.) at 25 ° C. and 60 rpm, and the results are shown in Table 1.

Examples 2 to 4 The aqueous urethane resin (Mitsui Toatsu Chemical: Orestar UD100N) used in Example 1 and an SBR-based latex (Mitsui Toatsu Chemical: Polylac 515) were added, and the amount of water added last. Except for adjusting the solids concentration to 50%,
In the same manner as in Example 1, four types of coating compositions for cast-coated paper of the present invention (hereinafter referred to as Examples 2 to 4) were obtained.

Comparative Example 1 Comparative Example 1 50 parts of kaolin (manufactured by EMC: UW90), 50 parts of calcium carbonate (manufactured by Okutama Industries: Tamapearl TP222HS), and 0.2 part of sodium pyrophosphate as a dispersant were added and dispersed in water using a Cowles dispersing machine. A 70% pigment slurry was prepared.

Next, 0.2 part of tributyl phosphate and 0.1 part of Pluronic L-61 (manufactured by Asahi Denka) as an antifoaming agent, 1.0 part of calcium stearate as a release agent, and 5 parts of casein heated and dissolved by adding ammonia water as an adhesive, Aqueous urethane resin (Mitsui Toatsu Chemical: Orestar UD100N) 0.5
Part, SBR latex (Mitsui Toatsu Chemical: Polylac 51
5) Add 14.5 parts, and finally add water, solid content concentration 50%
To obtain a coating composition for Comparative Example 1 as a coating composition for cast coat.

The viscosity of the obtained coating composition was measured using a BM type viscometer (manufactured by Tokyo Keiki) at 25 ° C. and 60 rpm, and the results are shown in Table 1.

Comparative Example 2 Comparative Example 2 50 parts of kaolin (manufactured by EMC: UW90), 50 parts of calcium carbonate (manufactured by Okutama Kogyo: Tamapearl TP222HS), and 0.2 part of sodium pyrophosphate as a dispersant were added and dispersed in water using a Cowles dispersing machine. A 70% pigment slurry was prepared.

Next, 0.2 part of tributyl phosphate and 0.1 part of Pluronic L-61 (manufactured by Asahi Denka) as antifoaming agents, 1.0 part of calcium stearate as a releasing agent, and 5 parts of casein heated and dissolved by adding ammonia water as an adhesive, Aqueous urethane resin (Mitsui Toatsu Chemical: Orestar UD100N) 6
Part, SBR latex (Mitsui Toatsu Chemical: Polylac 51
5) 9 parts were added, and finally water was added to adjust the solid content concentration to 50%.
A coating composition was obtained.

In addition, the viscosity of the obtained coating composition was measured by a BM type viscometer (manufactured by Tokyo Keiki Co., Ltd.) at 25 ° C. and 60 rpm, and the results are shown in Table 1.

Comparative Example 3 In Comparative Example 3, in order to clarify the combined effect of the aqueous urethane resin of the present invention and the total rubber latex, an example of a coating composition for cast-coated paper obtained by using synthetic rubber latex alone is shown.

50 parts of kaolin (manufactured by EMC: UW90), 50 parts of calcium carbonate (manufactured by Okutama Kogyo: Tamapearl TP222HS) and 0.2 parts of sodium pyrophosphate as a dispersing agent are dispersed in water using a Cowles dispersing machine, and a pigment having a concentration of 70% is added. The slurry was prepared.

Next, 0.2 part of tributyl phosphate and 0.1 part of Pluronic L-61 (manufactured by Asahi Denka) as antifoaming agents, 1.0 part of calcium stearate as a releasing agent, and 5 parts of casein heated and dissolved by adding ammonia water as an adhesive, 15 parts of SBR latex (manufactured by Mitsui Toatsu Chemical: Polylac 515) were added, and finally water was added to adjust the solid content to 50%.
Comparative Example 3 A coating composition for a cast coat was obtained.

The viscosity of the obtained coating composition was measured using a BM type viscometer (manufactured by Tokyo Keiki Co., Ltd.) at 25 ° C. and 60 rpm.
1 is shown.

Production Example of Cast Coated Paper The coating composition for cast coated paper obtained in the above Examples and Comparative Examples was coated on a base paper having a basis weight of 64 g / m ² with an air knife coater, and the coating amount of each coating composition was used. But by dry weight
After coating to 23 g / m ² and drying, a re-wet solution was applied and passed through a cast drum.

The diameter of the cast drum is 1800mm and the press pressure is 100kg /
cm, surface temperature 96-98 ° C.

The coated paper properties of the obtained cast coated paper were measured, and the results are shown in Table 1.

The gloss was measured according to JIS P-8142. The surface strength is printed with an RI printing tester (made by Mei Seisakusho),
The surface picking was evaluated on a 10-point scale (10: good without surface picking-1: poor picking occurred on the whole surface) by observing picking on the surface.

The gloss after printing was measured by an RI printer using 0.4 cc of a commercially available offset ink, and measured according to JIS P-8142.

The wear resistance was determined by a gakushin type friction fastness tester (manufactured by Daiei Kagaku Seiki Seisaku-sho, Ltd.) by observing the surface after a load test of 500 g / 20 times.

Next, an example in which an MBR system is used as a synthetic rubber latex will be described.

Example 5 50 parts of kaolin (manufactured by EMC: UW90), 50 parts of calcium carbonate (manufactured by Okutama Kogyo: Tamapearl TP222HS) and 0.2 part of sodium pyrophosphate as a dispersant were added, and dispersed in water using a Cowles disperser to give a concentration of 70. % Pigment slurry was prepared.

Next, 0.2 part of tributyl phosphate and 0.1 part of Pluronic L-61 (manufactured by Asahi Denka) as antifoaming agents, 1.0 part of calcium stearate as a releasing agent, and 5 parts of casein heated and dissolved by adding ammonia water as an adhesive, Aqueous urethane resin (Mitsui Toatsu Chemical: Orestar UD100N) 2
Part, MBR latex (Mitsui Toatsu Chemical: Polylac 50
3) 13 parts were added, and finally, water was added to adjust the solid content to 50% to obtain a coating composition for cast coating of the present invention (hereinafter referred to as a coating composition of Example 5).

The viscosity of the obtained coating composition was measured at 25 ° C. and 60 rpm using a BM type viscometer (manufactured by Tokyo Keiki).
It was shown to.

Examples 6 to 8 The aqueous urethane resin (Mitsui Toatsu Chemical: Orestar UD100N) and MBR-based latex (Mitsui Toatsu Chemical: Polylac 503) used in Example 5 were added. Four kinds of coating compositions for cast-coated paper of the present invention (hereinafter referred to as coating compositions in Examples 6 to 8) by the same operation as in Example 5 except that the solid content concentration is adjusted to 50%.
I got

Comparative Example 4 Comparative Example 4 50 parts of kaolin (manufactured by EMC: UW90), 50 parts of calcium carbonate (manufactured by Okutama Industries: Tamapearl TP222HS), and 0.2 part of sodium pyrophosphate as a dispersant were added, and dispersed in water using a Cowles dispersing machine. A 70% pigment slurry was prepared.

Next, 0.2 part of tributyl phosphate and 0.1 part of Pluronic L-61 (manufactured by Asahi Denka) as antifoaming agents, 1.0 part of calcium stearate as a releasing agent, and 5 parts of casein heated and dissolved by adding ammonia water as an adhesive, Aqueous urethane resin (Mitsui Toatsu Chemical: Orestar UD100N) 0.5
Part, MBR latex (Mitsui Toatsu Chemical: Polylac 50
3) Add 14.5 parts, and finally add water, solid content concentration 50%
To obtain a coating composition for cast coat and a coating composition for Comparative Example 4.

The viscosity of the obtained coating composition was measured at 25 ° C. and 60 rpm using a BM type viscometer (manufactured by Tokyo Keiki).
It was shown to.

Comparative Example 5 Comparative Example 5 50 parts of kaolin (manufactured by EMC: UW90), 50 parts of calcium carbonate (manufactured by Okutama Kogyo: Tamapearl TP222HS), and 0.2 parts of sodium pyrophosphate as a dispersant were added and dispersed in water using a Cowles dispersing machine. A 70% pigment slurry was prepared.

Next, 0.2 part of tributyl phosphate and 0.1 part of Pluronic L-61 (manufactured by Asahi Denka) as antifoaming agents, 1.0 part of calcium stearate as a releasing agent, and 5 parts of casein heated and dissolved by adding ammonia water as an adhesive, Aqueous urethane resin (Mitsui Toatsu Chemical: Orestar UD100N) 6
Part, MBR latex (Mitsui Toatsu Chemical: Polylac 50
3) Add 9 parts, add water at the end, solid content concentration 50%
To obtain a coating composition for Comparative Example 5 of the coating composition for cast coat of the present invention.

The viscosity of the obtained coating composition was measured at 25 ° C. and 60 rpm using a BM type viscometer (manufactured by Tokyo Keiki).
It was shown to.

Comparative Example 6 In Comparative Example 6, in order to clarify the combined effect of the aqueous urethane resin of the present invention and a synthetic rubber latex, an example of a coating composition for cast-coated paper obtained by using synthetic rubber latex alone is shown. 50 parts kaolin (EMC: UW90), 50 parts calcium carbonate (Okutama Kogyo: Tamapearl TP222HS),
0.2 parts of sodium pyrophosphate was added as a dispersant and dispersed in water using a Cowles disperser to prepare a 70% pigment slurry. Next, 0.2 part of tributyl phosphate and 0.1 part of Pluronic L-61 (manufactured by Asahi Denka) as an antifoaming agent, 1.0 part of calcium stearate as a releasing agent, 5 parts of casein heated and dissolved by adding aqueous ammonia as an adhesive, and MBR latex (Polylac 503, manufactured by Mitsui Toatsu Chemicals Co., Ltd.) (15 parts) was added, and finally, water was added to adjust the solid content concentration to 50% to obtain a paint composition for cast coat comparative example 6. The viscosity of the obtained coating composition was measured using a BM type viscometer (manufactured by Tokyo Keiki).
The measurement was performed at 25 ° C. and 60 rpm, and the results are shown in Table 2.

The cast-coated paper of Preparation Example and Comparative cast coated paper for coating compositions obtained in Examples, the coating amount of each coating composition a base paper having a basis weight of 64 g / m ² by an air knife coater, 23g / dry weight
After coating and drying so as to obtain m ² , a re-wet liquid was given and passed through a cast drum. Cast drum diameter is 1800m
m, the press pressure was 100 kg / cm, and the surface temperature was 96-98 ° C. Further, the coated paper properties of the obtained cast-coated paper were measured, and the results are shown in Table-2.

The gloss was measured according to JIS P-8142. The surface strength is printed with an RI printing tester (made by Mei Seisakusho),
The surface picking was evaluated on a 10-point scale by observing the surface picking (10: no surface picking, -1: poor picking occurred on the entire surface).

After printing, use a commercially available offset ink with an RI printing machine.
Printing was performed using 0.4 cc, and the measurement was performed according to JIS P-8142. The wear resistance was determined by a gakushin type friction fastness tester (manufactured by Daiei Kagaku Seiki Seisaku-Sho, Ltd.) by surface observation after a load of 500 g / 20 times wear test.

[Effects of the Invention] The numerical values in Tables 1 and 2 indicate that the cast paper obtained by the coating composition for cast-coated paper according to the examples of the present invention has a cast surface excellent in gloss, surface strength and abrasion resistance. This shows that the present invention can be manufactured, and it is clear that the present invention is a very useful coating composition which has not been hitherto used as a coating composition for cast-coated paper.

Claims (2)

(57) [Claims] 1. A paint for a cast-coated paper mainly comprising a pigment and an adhesive, wherein the adhesive comprises an aliphatic conjugated diolefin-based monomer, an olefin-based aromatic monomer and / or a monoolefin-based monomer as a main component. 70-95% by weight of synthetic rubber latex and aqueous urethane resin 30
A coating composition for cast-coated paper, wherein the coating composition is used in an amount of from 5 to 5% by weight. 2. A method for producing a cast-coated paper obtained by applying the composition according to claim 1.