JP3256001B2 - Substrate for offset printing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate for offset printing, and more particularly, to a method for coating a coating composition comprising the material specified in the present invention with a colored or colored paper, plastic film or metal foil. By printing on a printing material having a high gloss surface, it has good ink acceptability and printability such as setability, and prints cosmetic prints without impairing the color and gloss of the printing material. It is an object of the present invention to provide a printing substrate capable of performing offset .

[0002]

2. Description of the Related Art Heretofore, in the field of offset printing, a printing medium has been mainly paper. Among them, coated paper has the advantages that the printing surface is smooth, the printability such as ink acceptability and setability is good, and glossy and clear printed matter can be efficiently produced. It has been widely used to manufacture.

[0003] Coating agents used for producing this coated paper generally include inorganic pigments such as kaolin clay, calcium carbonate and titanium dioxide, casein, starch, SBR, and the like.
It is obtained by mixing with an aqueous binder resin such as an 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, It is further hot-pressed into coated paper.

Here, the pigments are arranged in layers on the surface of the paper,
In addition to imparting gloss and smoothness, the offset ink has an effect of absorbing a fluid component to improve the setting property of the ink. In addition, the aqueous binder resin has an effect of maintaining the fluidity of the coating agent and preventing the pigment from falling off the printing medium and preventing the coating agent layer from cracking. Therefore, in this type of coating agent, by increasing the pigment concentration, the offset printing suitability, gloss and sharpness of the printed matter are imparted,
Many of the coating agents used had a pigment content of about 80% or more in the solid content.

On the other hand, recently, there has been an increasing demand for the aesthetics of printed materials, and materials having high gloss and vivid colors other than paper have been used as printing materials. One of the most prominent examples is that plastic films and metal foil laminated papers such as aluminum foils have been used very frequently in prints. When these printing materials are printed with offset ink, the characteristics of the surface of the printing material are well reflected, and the excellent glossiness that cannot be obtained with ordinary paper prints, such as crystal gloss on plastic films and metal gloss on metal foil laminated paper. Very high quality printed matter with gloss and vivid colors can be obtained.

[0006] However, since these printing materials are both non-permeable surfaces, there is a problem that the setting property of the offset ink becomes extremely slow. For example, when a normal offset ink is used, in ink-coated paper printing, the ink setting time is about 10 minutes, whereas in plastic film or metal foil printing, the ink setting time is often less than one day. Therefore, workability and manufacturing efficiency are significantly reduced.

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

In order to solve this problem, a coating comprising a mixture of a diene polymer which absorbs the flow components of the offset ink and a styrene polymer which fixes the offset ink without containing a pigment in the system. Agents are described, for example, in JP-A-49-37705. But,
Since both styrene and diene-based monomers are lipophilic, this coating agent is an organic solvent-based, which is not preferable in terms of safety or occupational health. Further, from the viewpoint of performance, it is difficult to obtain a coating agent which is flexible enough to cause no crack even when bent, has good ink setting properties, and has high transparency.

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

[0010]

SUMMARY OF THE INVENTION The object of the present invention is to provide a coating composition having high transparency, good offset ink acceptability and good settability , on colored paper, By pre-coating on the printing material such as metallized paper, metal foil laminated paper, plastic film or metal foil, it has excellent ink acceptability and printability when printing offset ink, such as ink setting. Another object of the present invention is to provide a base material for offset printing that can obtain a high-quality printed matter without impairing the gloss or color of a printing medium.

[0011]

That is, the present invention provides:
" A 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 and 0 to 40 of another copolymerizable vinyl group-containing monomer are used.
An aqueous emulsion comprising a polymer obtained by emulsion polymerization of a percent by weight was coated a coating composition you containing as a binder resin to the printing material, dried Na Ru offset printing substrate "relates It is. 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 is copolymerized with another copolymerizable polymer. An aqueous emulsion composed of a polymer obtained by emulsion polymerization of a vinyl group-containing monomer with 0 to 40% by weight is used as a main binder resin. 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 from 20 to 350, more preferably from 50 to 350.
It is in the range of 250. If the acid value is less than 20, the emulsifying ability of maleated polybutadiene in water decreases, and uniform emulsion polymerization becomes difficult. On the other hand, when the acid value exceeds 350, the water resistance of the obtained coating composition is undesirably reduced. 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 maleated polybutadiene has a number average molecular weight of 200 to 20,000, preferably 500.
It can be obtained by addition polymerization of 10,000 to 10,000 polybutadiene with 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 and the like are undesirably reduced. On the other hand, when the number average molecular weight of the polybutadiene exceeds 20,000, the emulsifying ability of the resulting maleated polybutadiene in water decreases, and uniform emulsion polymerization becomes difficult.

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

Further, a basic compound can be used to emulsify the maleated polybutadiene in water, and examples of such a basic compound include organic amines,
Examples include alkali metal hydroxides and ammonia.
Here, as the organic amines, in addition to alkanolamines such as monoethanolamine and triethanolamine, diamines and triamines can be used, and as hydroxides of alkali metals, sodium hydroxide, potassium hydroxide and the like can be used. Can be used. Among them, ammonia and organic amines are preferred from the viewpoint of water resistance of the coating composition.

In the presence of the above-mentioned maleated polybutadiene emulsifier, the monomer to be emulsion-polymerized may be a styrene monomer alone, or a styrene monomer and another copolymerizable vinyl group-containing monomer. You may use together.

Here, as the styrene monomer, styrene, α-methylstyrene, vinyltoluene and the like can be used. The amount used is usually 100 to 60% by weight, preferably 100 to 80% by weight. If the content of the styrene monomer is less than 60% by weight, the setting property of the coating composition intended for 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) ester, hydroxyalkyl (meth) acrylate (C2-4) ) Ester, (meth)
Acrylamide, crotonic acid, maleic acid, fumaric acid,
Citraconic acid, itaconic acid and its alkyl (1 to 1 carbon atoms)
8) Esters and ether compounds having an unsaturated double bond 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 above emulsion polymerization is preferably 60 ° C. or higher. If the temperature is lower than 60 ° C., the obtained coating composition becomes flexible, and the blocking resistance is likely to be lowered, 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 from 10:90 to 50:50,
More preferably, it is in the range of 20:80 to 35:65.
When the weight ratio of the emulsifier becomes lower than the range of 10:90,
The resulting coating composition becomes opaque and the rub resistance and the like are reduced. On the other hand, when the weight ratio of the emulsifier is higher than the range of 50:50, the blocking resistance becomes poor.

As a polymerization method for obtaining an aqueous emulsion in the present invention, a conventionally known method can be used. For example, a method in which the above-mentioned maleated polybutadiene is emulsified in water in the presence of a basic compound and then heated and reacted while stirring, while dropping a polymerizable monomer and an initiator as necessary. Etc. can be used.

The coating composition of the present invention has a sufficient effect even with the aqueous binder resin composed of the above-mentioned aqueous emulsion alone, but further improves the abrasion resistance, adhesiveness, drying property, sharpness of printed matter, and the like. Other aqueous binder resins, coloring agents, water-miscible solvents, release agents, waxes, defoamers, as long as the transparency, blocking resistance, and ink setting properties of the coating composition are not reduced. Various additives such as a preservative and a preservative can be mixed.

Here, other aqueous binder resins include:
Water-soluble resins, alkali-soluble resins, and water-dispersible resins generally used in paper coating agents can be used. In particular,
Examples of the water-soluble resin include polyvinyl alcohol and water-soluble celluloses. Examples of the alkali-soluble resin include a rosin-modified maleic resin, a styrene-maleic resin, a styrene-acrylic resin, acrylic acid, and methacrylic resin. An acrylic resin obtained by copolymerizing an unsaturated carboxylic acid monomer such as an acid and an ester or an amide compound thereof, and the like, and examples of the water-dispersible resin include casein, an SBR resin, acrylic acid, methacrylic acid, and the like. 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 coloring agent, various dyes and highly transparent organic pigments can be used in the content range of 1 to 50% by weight in the coating composition. Examples of the water-miscible solvent include 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 and the like can be used. Regarding the production of a coating composition having the above composition, a predetermined amount of each material can be stirred and mixed using a stirrer such as a high-speed mixer.

Next, the substrate for printing of the present invention will be described. The substrate for printing is produced by applying the above-mentioned coating composition on a substrate and drying it.

First, as the printing medium used in the present invention, various printing papers, plastic films or metal foils can be used. Here, as printing paper, especially colored paper, metallized paper, metal foil laminated paper, etc., as plastic film, polyethylene, polypropylene, polyester, nylon, cellophane, etc., as metal foil,
Aluminum foil, copper foil, etc. can be used. It should be noted that application of the present coating composition to ordinary printing paper other than those described above may be performed without any problem, and printability such as acceptability and setting property of the offset ink can be improved.

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.
Furthermore, it can be applied to one or both sides of the printing medium, and the coating amount is usually used in the range of 0.5 to 10 g / m ² (dry weight) in one or more coatings. Is done.

Further, as a drying method after the coating composition is applied to the printing medium, various heaters such as hot air heating and infrared heaters can be used. Furthermore, press working can be performed using a drum surface under heating and pressurization to the extent that the printing medium does not undergo 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 printing substrate that has good print acceptability such as good ink receptivity and setability, and that gives excellent printed matter without impairing the gloss and color of the printing medium.

[0031]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. Hereinafter, “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, thermometer, cooling tube, and nitrogen gas inlet tube.
1010, manufactured by Nippon Soda, acid value 110) 60 parts, and 600 parts of water in which an equivalent amount of ammonia is dissolved, 80-
Heating at 85 ° C. dissolved the maleated polybutadiene. Furthermore, while maintaining the same temperature, with good stirring,
After a mixture of 340 parts of styrene and 3 parts of ditert-butyl oxide was added dropwise over 2 hours, the mixture was further reacted for 2 hours to carry out emulsion polymerization. By the above operation, solid content 40
%, Glass transition temperature of polymer 100 ° C., viscosity 650 cp
A sample emulsion No. 1 (weight ratio of emulsifier to polymer, 10:57) of s (25 ° C.) was obtained.

Synthesis Example 2 The same operation as in Synthesis Example 1 was carried out except that the charged amounts were 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.

Synthesis Example 3 The same operation as in Synthesis Example 1 was carried out except that the charged amounts were 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.

Synthesis Example 4 The same operation as in Synthesis Example 1 was carried out 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 a monomer to be dropped. Sample emulsion No. 4 (weight ratio of emulsifier to polymer, 12: 2, 40%, glass transition temperature of polymer 101 ° C., viscosity 400 cps (25 ° C.)
8) was obtained.

Synthesis Example 5 The 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 the monomer to be dropped.
In the same manner 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, acid number 160) was used, and the amount of styrene was changed to 280 parts. With a solid content of 40% and a 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 carried out except that the charged amounts were 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) at 000 cps (25 ° C.) was obtained.

Synthesis Example 8 The same operation as in Synthesis Example 1 was carried out except that the charged amounts were 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 The amount of maleated polybutadiene A was changed to 120 parts, and a mixture of 140 parts of styrene and 140 parts of isobutyl methacrylate was used as a monomer to be dropped.
In the same manner as in Synthesis Example 1, a sample emulsion No. 9 having a solid content of 40%, a glass transition temperature of the polymer of 83 ° C., and a viscosity of 130 cps (25 ° C.) (weight ratio of emulsifier and polymer, 12:
28) was obtained.

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

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

[0043]

[Table 1]

Test Example 1 The surface gloss and offset of the printing substrate obtained by applying the coating composition of Examples 1 to 9 and Comparative Examples 1 to 5 using coated paper as a printing medium An evaluation test was performed according to the following methods for setting properties, blocking resistance, and transparency of the ink, and the results are shown in Table 2.

[0045]

[Table 2]

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

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

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

(3) Evaluation of blocking resistance A sample coating agent was applied to a coated paper with a 0.15 mmΦ mean bar, dried, and the coated surfaces were put together to obtain 1 kg / cm ^2.
Under a 40 ° C, 90% humidity environment.
After standing for a time, the anti-blocking property was evaluated from the state at the time of peeling. Evaluation criteria A: Peeling without any resistance B: Peeling with peeling resistance, C: Peeling of printed material upon peeling

(4) Evaluation of Transparency A sample coating agent was applied to black colored paper using a 0.15 mm Φ mean bar, and the transparency of the coated surface was evaluated by visually judging the haze of the coated surface. 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 printing substrate An evaluation test was conducted in the same manner as in Test Example 1 for the settability, blocking resistance, and transparency, and the results are shown in Table 3.

[0052]

[Table 3]

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

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

[0055]

The coating composition of the present invention has high transparency. By applying this composition to a printing medium, good gloss and offset can be obtained without impairing the gloss and color of the printing medium. A printing substrate having ink setting properties can be obtained.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-48-73488 (JP, A) JP-A-61-63794 (JP, A) JP-A-4-107186 (JP, A) 43381 (JP, B1) (58) Field surveyed (Int. Cl. ⁷ , DB name) D21H 19/58 B41M 1/30 C08F 2/26 C08F 212/06-212/12 C09D 125/02-125/16

Claims (4)

(57) [Claims] 1. A styrene-based monomer comprising a maleated polybutadiene having an acid value of 20 to 350 as an emulsifier.
0-60% by weight, other copolymerizable vinyl group-containing monomer 0 to 40% by weight coating agent you containing <br/> as an aqueous emulsion of a binder resin comprising a polymer obtained by emulsion polymerization Apply the composition to the substrate and dry it.
Substrate for fset printing . 2. The weight ratio of emulsifier to polymer is 10:90.
The base for offset printing according to claim 1, wherein the ratio is from 50 to 50:50.
Wood . Wherein the glass transition temperature of the polymer, 60 ° C. or higher der Ru請 Motomeko 1 or 2 for offset printing substrate according. (4) The substrate for offset printing according to any one of claims 1 to 3 , wherein the substrate is a colored paper, a metallized paper, a metal foil laminated paper, a plastic film or a metal foil.