JPH06145251A - Coating composition and substrate for printing using the same - Google Patents

Abstract

(57) [Summary] [Structure] Styrene-based monomers 100 to 6 using maleated polybutadiene having an acid value of 20 to 350 as an emulsifier.
0% by weight and other copolymerizable vinyl group-containing monomer 0
To 40% by weight of the polymer is obtained by emulsion polymerization, and an aqueous emulsion composed of a polymer is contained as a binder resin, and the above-mentioned coating composition is applied to a material to be printed. A printing substrate obtained by drying. [Effect] The coating composition of the present invention has high transparency. By applying this composition to a printing medium, good gloss and offset ink can be obtained without impairing the gloss and color of the printing medium. It is possible to obtain a printing substrate having settability.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a coating composition and a printing substrate obtained by coating the same, and more specifically,
By applying a coating composition comprising the material specified in the present invention to a printing material having a colored or high-gloss surface such as colored paper, a plastic film or a metal foil,
An object of the present invention is to provide a printing substrate which has good printability such as ink acceptability and settability and is capable of printing cosmetic printed matter without impairing the color and gloss of the printing medium. .

[0002]

2. Description of the Related Art Conventionally, in the field of offset printing, the material to be printed has been mainly paper. Among them, the coated paper has a smooth printing surface, good printability such as ink acceptability and settability, and the advantage that a glossy and clear printed matter can be efficiently produced. Have been widely used for manufacturing.

The coating agents used for producing this coated paper are generally inorganic pigments such as kaolin clay, calcium carbonate and titanium dioxide, and casein, starch, SBR,
It is obtained by mixing with an aqueous binder resin such as alkali-soluble latex, and these coating agents are coated on the paper surface by various coating means such as a roll coater, a blade coater, or an air knife coater, Further, it is hot-pressed to form coated paper.

Here, the pigments are arranged in layers on the surface of the paper,
It has the effects of imparting gloss and smoothness and absorbing fluid components in the offset ink to improve the ink settability. Further, the aqueous binder resin has the effects of maintaining the fluidity of the coating agent, and preventing the pigment from falling off from the printing medium and cracking of the coating agent layer. Therefore, in this type of coating agent, by increasing the pigment concentration, offset printing suitability, gloss and sharpness of the printed matter are imparted,
Most of the coating agents used were those containing about 80% or more of pigment in the solid content.

On the other hand, in recent years, the demand for the beauty of printed matter has been increasing more and more, and a material having high gloss and vivid colors other than paper has been used as a material to be printed. One of the most prominent examples thereof is the fact that plastic films and metal foil laminated paper such as aluminum foil have been used very much in recent years for printed materials. When offset ink is printed on these printed materials, the characteristics of the surface of the printed materials are well reflected, and crystal gloss for plastic films and metallic luster for metal foil laminated paper are excellent, which cannot be obtained with ordinary paper prints. It is possible to obtain printed materials with a very high texture, which have gloss and vivid colors.

[0006] However, since both of these materials to be printed are impermeable surfaces, there is a problem that the settability of the offset ink is remarkably slowed. For example, when using a normal offset ink, the ink setting time is about 10 minutes in coated paper printing, but in the case of plastic film or metal foil printing, it is rare that it is not set even if left for one day. In addition, workability and manufacturing efficiency are significantly reduced.

As a method for solving this problem, it is conceivable to apply a coating agent having the effect of improving the setting property on the surface of the printing medium. However, the conventional coating material containing a pigment hides the surface of the printing medium, and therefore the gloss and hue of the printing medium cannot be reflected in the printed matter. Therefore, there is a strong demand for a coating agent that imparts good ink setting properties and has high transparency.

In order to solve this problem, a coating composed of a mixture of a diene polymer which absorbs a fluid component of the offset ink without containing a pigment in the system and a styrene polymer which fixes the offset ink. The agents are described in, for example, JP-A-49-37705. But,
Since both styrene and the diene-based monomer are lipophilic, this coating agent is an organic solvent type, which is not preferable from the viewpoint of safety or occupational hygiene. Further, from the viewpoint of performance, it is difficult to obtain a coating agent that is flexible enough to prevent cracking even when bent, has good ink setting properties, and has high transparency.

On the other hand, in an aqueous coating agent, an aqueous dispersion of a copolymer (SBR) of styrene and a butadiene-based monomer is used, and its effect and the like are described in, for example, JP-A-2-107305. There is. However, SBR has a problem that the blocking resistance and the effect of improving the ink settability are low.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to develop a coating composition having high transparency and good offset ink acceptability and settability in order to solve the above problems. is there. Further, an excellent ink for printing offset ink by previously applying the coating composition to a printing medium such as colored paper, metal vapor deposition paper, metal foil laminated paper, plastic film or metal foil. Another object of the present invention is to provide a printing substrate which has printability such as acceptability and settability and is capable of obtaining a printed material with a high texture without impairing the gloss and color of the printing medium.

[0011]

That is, the present invention is
(1) Styrene-based monomer 100 to 60 using maleated polybutadiene having an acid value of 20 to 350 as an emulsifier
% By weight, and other copolymerizable vinyl group-containing monomer 0 to
40% by weight and an aqueous emulsion comprising a polymer obtained by emulsion polymerization as a binder resin, and (2) a material to be printed,
The present invention relates to a printing substrate obtained by coating and drying the above coating composition. Hereinafter, the present invention will be described in detail.

As the binder resin contained in the coating composition of the present invention, maleated polybutadiene having an acid value of 20 to 350 is used as an emulsifier, and 100 to 60% by weight of a styrene monomer can be copolymerized with another. The main binder resin is an aqueous emulsion composed of a polymer obtained by emulsion polymerization of 0 to 40% by weight of a vinyl group-containing monomer. That is, this aqueous emulsion comprises the polymer obtained as described above and an emulsifier, and is used as an aqueous binder resin.

The maleated polybutadiene used as an emulsifier has an acid value of 20 to 350, more preferably 50 to 350.
The range is 250. When the acid value is less than 20, the emulsifying ability of maleated polybutadiene with respect to water is lowered and uniform emulsion polymerization becomes difficult. On the other hand, when the acid value exceeds 350, the water resistance of the obtained coating composition decreases, which is not preferable. Here, the acid value can be set in the following production method, for example, by adjusting the use ratio of polybutadiene and maleic acid or maleic anhydride.

The above maleated polybutadiene has a number average molecular weight of 200 to 20,000, more preferably 500.
It can be obtained by addition-polymerizing polybutadiene of 10,000 to maleic acid or maleic anhydride. Here, when the number average molecular weight of the polybutadiene used is less than 200, the obtained maleated polybutadiene hardly functions as a polymer emulsifier, and the blocking resistance is deteriorated, which is not preferable. On the other hand, when the number average molecular weight of polybutadiene exceeds 20,000, the emulsifying ability of the obtained maleated polybutadiene with respect to water is lowered, and uniform emulsion polymerization becomes difficult.

The polybutadiene may have a structure of 1,2-vinyl type, 1,4-trans type or 1,4-cis type, or may be a mixture thereof. .

Further, a basic compound can be used for emulsifying the maleated polybutadiene in water. Examples of such a basic compound include organic amines,
Examples thereof include alkali metal hydroxides and ammonia.
Here, as the organic amines, in addition to alkanolamines such as monoethanolamine and triethanolamine, diamines and triamines can also be used, and as the alkali metal hydroxides, sodium hydroxide, potassium hydroxide, etc. Can be used. Among them, ammonia or organic amines are preferable from the viewpoint of water resistance of the coating composition.

As the monomer which is emulsion-polymerized in the presence of the above-mentioned maleated polybutadiene, a styrene-based monomer may be used alone, or a styrene-based monomer and another copolymerizable vinyl group-containing monomer may be used. You may use together.

Here, styrene, α-methylstyrene, vinyltoluene and the like can be used as the styrene-based monomer. The amount used is usually 100 to 60% by weight, preferably 100 to 80% by weight. When the content of the styrene-based monomer is less than 60% by weight, the settability of the coating composition intended by the present invention cannot be obtained, which is not preferable.

Other copolymerizable vinyl group-containing monomers include, for example, (meth) acrylic acid and its alkyl (C1-8) esters, hydroxyalkyl (meth) acrylate (C2-4). ) Ester, (meth)
Acrylamide, crotonic acid, maleic acid, fumaric acid,
Citraconic acid, itaconic acid and its alkyl (C1-C1
8) Ester, ether compound having unsaturated double bond, etc. can be used. The amount used is usually 0 to 40% by weight, preferably 0 to 20% by weight.

The glass transition temperature of the polymer obtained by the emulsion polymerization is preferably 60 ° C. or higher. When the temperature is lower than 60 ° C, the obtained coating agent composition becomes flexible, and the blocking resistance is apt to decrease, which is not preferable.

In the above aqueous binder resin comprising an aqueous emulsion comprising an emulsifier and a polymer, the weight ratio of the emulsifier to the polymer is usually 10:90 to 50:50,
The range is more preferably 20:80 to 35:65.
When the weight ratio of the emulsifier is lower than the range of 10:90,
The obtained coating composition becomes opaque, and the abrasion resistance and the like decrease. On the other hand, when the weight ratio of the emulsifier is higher than the range of 50:50, blocking resistance becomes poor.

As a polymerization method for obtaining the aqueous emulsion in the present invention, a conventionally known method can be used. For example, a method of emulsifying the above maleated polybutadiene in water in the presence of a basic compound, and then heating and reacting under stirring with dropping a polymerizable monomer and an initiator if necessary. Etc. can be used.

The coating composition of the present invention has a sufficient effect only with the aqueous binder resin consisting of the above-mentioned aqueous emulsion, but further improves abrasion resistance, adhesiveness, drying property, sharpness of printed matter and the like. In order to allow the transparency, blocking resistance, and ink settability of the coating composition, other aqueous binder resins, colorants, water-miscible solvents, release agents, waxes, defoamers, etc. Various additives such as agents and preservatives can be mixed.

Here, as the other aqueous binder resin,
Water-soluble resins, alkali-soluble resins, and water-dispersible resins that are generally used in paper coating agents can be used. In particular,
Examples of the water-soluble resin include polyvinyl alcohol and water-soluble celluloses, and examples of the alkali-soluble resin include rosin-modified maleic acid resin, styrene-maleic acid resin, styrene-acrylic acid resin, acrylic acid, and methacrylic acid. Examples thereof include acrylic resins obtained by copolymerizing an unsaturated carboxylic acid monomer such as an acid and its ester or amide compound. Examples of the water-dispersible resin include casein, SBR resin, acrylic acid and methacrylic acid. A resin obtained by emulsion polymerization of a saturated carboxylic acid and its ester or amide compound, a resin obtained by emulsion polymerization of a fatty acid vinyl ester type compound such as vinyl acetate, and the like can be used. These resins can be used in the content range of 0 to 20% by weight in the coating composition.

As the colorant, various dyes and highly transparent organic pigments can be used within the content range of 1 to 50% by weight in the coating composition. The water-miscible solvent includes lower alcohols, polyhydric alcohols and alkyl ethers or alkyl esters thereof, and specifically, lower alcohols such as methanol, ethanol, normal propanol and isopropanol.
Polyhydric alcohols such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, glycerin, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol acetate, diethylene glycol monomethyl ether, Dipropylene glycol monomethyl ether or the like can be used. The coating composition having the above composition can be produced by stirring and mixing a predetermined amount of each material using a stirrer such as a high speed mixer.

Next, the printing base material of the present invention will be described. The printing base material is produced by applying the above-mentioned coating agent composition to a substrate and then drying it.

First, various printing papers, plastic films or metal foils can be used as the printing medium used in the present invention. Here, as the printing paper, especially colored paper, metal vapor deposition paper, metal foil laminated paper, etc., as the plastic film, polyethylene, polypropylene, polyester, nylon, cellophane, etc., as the metal foil,
Aluminum foil, copper foil, etc. can be used. In addition, it is possible to apply the coating composition of the present invention to ordinary printing papers other than the above, and it is possible to improve the printability such as the acceptability and setting property of the offset ink.

As a method for applying the coating composition of the present invention, any of ordinary roll coaters, doctor blade coaters, knife edge coaters, curtain coaters, gravure coaters, bar coaters and the like can be used.
Further, it can be applied to one side or both sides of the printing medium, and the application amount is usually 0.5 to 10 g / m ² (dry weight) in one or a plurality of applications. To be done.

As the method for drying after the coating composition is applied to the printing medium, various heaters such as hot air heating and infrared heaters can be used. Further, it is possible to perform press working by using the drum surface under heating / pressurization within a range in which the printing medium does not cause dimensional change or thermal deterioration.

The printing substrate of the present invention produced as described above is printed by a usual offset printing method,
It is a substrate for printing which has excellent printability such as ink acceptability and settability, and further gives excellent printed matter without impairing the gloss and color of the material to be printed.

[0031]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. In the following, "parts" and "%" mean "parts by weight" and "% by weight" unless otherwise specified.

Synthesis Example 1 Maleated polybutadiene A (BN-) was placed in a four-necked flask equipped with a stirrer, a thermometer, a cooling pipe, and a nitrogen gas introducing pipe.
1010, manufactured by Nippon Soda Co., Ltd., acid value 110) 60 parts, and 600 parts of water in which an equivalent amount of ammonia is dissolved are charged, and 80-
It was heated at 85 ° C. to dissolve the maleated polybutadiene. Furthermore, while maintaining the same temperature, while stirring well,
A mixture of 340 parts of styrene and 3 parts of ditert-butyl oxide was added dropwise over 2 hours, and the mixture was further reacted for 2 hours to carry out emulsion polymerization. By the above operation, the solid content 40
%, Glass transition temperature of polymer 100 ° C., viscosity 650 cp
s (25 ° C.) sample emulsion No. 1 (weight ratio of emulsifier to polymer, 10:57) was obtained.

Synthesis Example 2 The same operation as in Synthesis Example 1 was repeated except that the charged amount was changed to 120 parts of maleated polybutadiene A and 280 parts of styrene.
Sample emulsion No. 2 having a solid content of 40%, a glass transition temperature of the polymer of 100 ° C., and a viscosity of 1040 cps (25 ° C.)
(Weight ratio of emulsifier to polymer, 12:28) was obtained.

Synthetic Example 3 The same operation as in Synthetic Example 1 was repeated except that the charged amount was changed to 160 parts of maleated polybutadiene A and 240 parts of styrene.
Sample emulsion No. 3 having a solid content of 40%, a glass transition temperature of the polymer of 100 ° C and a viscosity of 1500 cps (25 ° C)
(Weight ratio of emulsifier to polymer, 16:24) was obtained.

Synthetic Example 4 The solid content was the same as in Synthetic Example 1 except that the charged amount of maleated polybutadiene A was changed to 120 parts and a mixture of 240 parts of styrene and 40 parts of methyl methacrylate was used as the monomer to be dropped. 40%, polymer glass transition temperature 101 ° C., viscosity 400 cps (25 ° C.), sample emulsion No. 4 (weight ratio of emulsifier to polymer, 12: 2)
8) was obtained.

Synthetic Example 5 except that the charged amount of maleated polybutadiene A was changed to 120 parts and a mixture of 180 parts of styrene and 100 parts of isobutyl methacrylate was used as a monomer to be dropped.
By the same operation as in Synthesis Example 1, sample emulsion No. 5 having a solid content of 40%, a glass transition temperature of the polymer of 88 ° C. and a viscosity of 200 cps (25 ° C.) (weight ratio of emulsifier to polymer, 12:
28) was obtained.

Synthesis Example 6 The same operation as in Synthesis Example 1 except that 120 parts of maleated polybutadiene B (M-1000-80, manufactured by Nippon Petrochemical Co., Ltd., acid value 160) was used and the amount of styrene charged was changed to 280 parts. At a solid content of 40% and a polymer glass transition temperature of 100.
℃, viscosity 1100cps (25 ℃) sample emulsion
No. 6 (weight ratio of emulsifier to polymer, 12:28) was obtained.

Synthesis Example 7 The same operation as in Synthesis Example 1 was repeated except that the charged amount was changed to 20 parts of maleated polybutadiene A and 380 parts of styrene, the solid content was 40%, the glass transition temperature of the polymer was 100 ° C., and the viscosity was 1
A sample emulsion No. 7 (weight ratio of emulsifier to polymer, 2:38) of 000 cps (25 ° C.) was obtained.

Synthetic Example 8 The same operation as in Synthetic Example 1 was repeated except that the charged amount was changed to 240 parts of maleated polybutadiene A and 160 parts of styrene.
Sample emulsion No. 8 having a solid content of 40%, a glass transition temperature of the polymer of 100 ° C., and a viscosity of 2000 cps (25 ° C.)
(Weight ratio of emulsifier to polymer, 24:16) was obtained.

Synthesis Example 9 except that the amount of maleated polybutadiene A charged was changed to 120 parts and a mixture of 140 parts of styrene and 140 parts of isobutyl methacrylate was used as the monomer to be dropped.
By the same operation as in Synthesis Example 1, a sample emulsion No. 9 (solid content 40%, polymer glass transition temperature 83 ° C., viscosity 130 cps (25 ° C.) (weight ratio of emulsifier to polymer, 12:
28) was obtained.

Examples 1 to 9 Sample emulsion Nos. 1 to 6 obtained in Synthesis Examples 1 to 6,
The SBR resin dispersion, styrene-acrylic acid emulsion, 3% aqueous solution of polyvinyl alcohol, polyethylene wax dispersion, and water were mixed and stirred according to the composition of Table 1 to obtain a coating composition of the present invention. Here, as an SBR resin dispersion, JSR-0624 (N.V .: 47.5)
%, Made by Japan Synthetic Rubber), as a styrene-acrylic acid type emulsion, Jonkryl 74J (N.V.:45)
%, Made by Johnson Polymer), as polyvinyl alcohol, Gohsesize P-7000 (made by Nippon Synthetic Chemical Industry Co., Ltd.),
High-tech E-68A as polyethylene wax
(N.V .: 50%, manufactured by Toho Chemical Industry) was used.

Comparative Examples 1-5 Sample emulsion Nos. 7-9 obtained in Synthesis Examples 7-9,
A coating composition having the composition shown in Table 1 was obtained in the same manner as in Example except that the SBR resin dispersion or the styrene-acrylic acid emulsion was used as the main component.

[0043]

[Table 1]

Test Example 1 Surface gloss and offset of a printing substrate obtained by applying the coating composition of Examples 1 to 9 and Comparative Examples 1 to 5 using coated paper as a material to be printed. An evaluation test was conducted on the ink settability, blocking resistance, and transparency according to the methods described below, and the results are shown in Table 2.

[0045]

[Table 2]

As the coated paper, Rengo CRC is used.
(Made by Rengo), as offset ink, Diatone Calton Master GA indigo (made by Sakata Inx)
It was used.

(1) Evaluation of Gloss The sample coating agent was applied to coated paper with a 0.15 mmΦ mere bar, and the gloss was visually evaluated. Evaluation Criteria A: A material having a gloss equal to or higher than that of a printing material not coated with a coating agent B: A material having lower gloss than that of a printing material not coated with a coating material

(2) Evaluation of Setting Property of Offset Ink A sample coating agent was applied to a coated paper with a 0.15 mmΦ mere bar, and the offset ink was applied to the coated surface at 0.1 cc / using a RI tester. Print on a 200 cm ² heap,
A set test was performed using an offset ink set tester. The settability of the offset ink was evaluated from the set time. Evaluation criteria A: Set time is less than 5 minutes B: Set time is 5 minutes or more and less than 20 minutes C: Set time is 20 minutes or more

(3) Evaluation of Blocking Resistance A sample coating agent was applied to coated paper with a 0.15 mmΦ mere bar, and after drying, the coated surfaces were put together and 1 kg / cm ²
24 in a 40 ° C, 90% humidity environment
After standing for a period of time, the blocking resistance was evaluated from the state of peeling. Evaluation Criteria A: Peeling without any resistance B: Peeling resistance but peeling C: Rupture of printed material during peeling

(4) Evaluation of Transparency The sample coating agent was applied to black colored paper with a 0.15 mm Φ mere bar, and the cloudiness of the coated surface was visually evaluated to evaluate the transparency. Evaluation criteria A: Completely transparent B: Slightly cloudy C: Completely opaque

Test Example 2 Surface gloss and offset ink of a printing substrate obtained by applying the coating composition of Examples 1 to 4 and Comparative Examples 1 to 5 using an aluminum foil as a material to be printed. The settability, blocking resistance, and transparency were evaluated by the same method as in Test Example 1, and the results are shown in Table 3.

[0052]

[Table 3]

As the aluminum foil, A1N30H-
H18 (20 μm, made by Nippon Foil) was used.

As described above in detail with reference to Examples and the like, all the printing substrates obtained by using the coating composition of the present invention have gloss, offset ink setting property, It was excellent in blocking resistance and transparency. In contrast, when a resin emulsion of a type different from that of the present invention is used (Comparative Examples 1 and 2), when the weight ratio of the emulsifier is different (Comparative Examples 3 and 4), and when the monomer usage ratio is different (Comparative Example 5). ), The performance of any of gloss, offset ink setting property, blocking resistance, and transparency was insufficient.

[0055]

EFFECT OF THE INVENTION The coating composition of the present invention has high transparency, and by applying the composition to a substrate to be printed, good gloss and offset can be obtained without impairing the gloss and color of the substrate. It is possible to obtain a printing substrate having ink setting properties.

Claims (5)

[Claims] 1. A styrenic monomer 10 using maleic polybutadiene having an acid value of 20 to 350 as an emulsifier.
0-60% by weight and 0-40% by weight of another copolymerizable vinyl group-containing monomer, an aqueous emulsion comprising a polymer obtained by emulsion polymerization is contained as a binder resin. Composition. 2. The weight ratio of emulsifier to polymer is 10:90.
The coating composition according to claim 1, wherein the coating composition is about 50:50. 3. The coating composition according to claim 1, wherein the glass transition temperature of the polymer is 60 ° C. or higher. 4. A printing substrate obtained by applying the coating composition according to any one of claims 1 to 3 to a material to be printed and drying it. 5. The printing substrate according to claim 4, wherein the material to be printed is colored paper, metallized paper, metal foil laminated paper, plastic film or metal foil.