JPS6037239B2 - Water-based gloss coating composition for printing paper - Google Patents

Description

[Detailed description of the invention] The present invention relates to an aqueous polish coating composition for printing paper.

More specifically, the present invention relates to a water-based gloss coating composition for printing paper that is excellent in gloss, blocking resistance, scratch resistance, abrasion resistance, and various types of resistance. For book covers, paper cartons, calendars, picture postcards, etc., a resin solvent solution is applied to the printed surface of the printed paper and dried for the purpose of adding gloss, protecting the printed surface, and improving the printing effect. Hot pressing is widely performed using methods such as endless pressing and flat pressing. For this purpose,
Resins such as vinyl chloride/vinyl acetate copolymers dissolved in organic solvents such as toluene and ethyl acetate have been used. However, during the processing process, these solvents volatilize, harming the health of workers and posing a high risk of fire, and regulations on emitted solvents are becoming stricter, so safer water-based solvents are needed. A glossy paint is requested. However, water-based polishing paints are generally inferior to solvent-based paints in physical properties such as gloss, blocking resistance, and abrasion resistance, and are only used in a few limited applications. In order to improve the above-mentioned physical properties, which have hitherto been regarded as drawbacks of water-based gloss paints, the present inventors conducted various studies and as a result arrived at the present invention. That is, the present invention provides 70 to 90% by weight of m methyl methacrylate units, (
5 to 2 weight % of meth)acrylic acid alkyl ester (however, the number of carbon atoms in the alkyl group is 10 to 20) units, 2 to 1 weight % of Q,3 unsaturated carboxylic acid units, and 0 other vinyl monomer units -2% by weight of a water tower salt A of a volatile base of a copolymer with a melting point of 110-150 oC and (2) 1-1 parts by weight of a saturated or unsaturated higher carbon number 18-22 per part by weight of AIOO This is an aqueous gloss coating composition for printing paper, characterized in that it contains an alkali metal salt B of a fatty acid as an essential component.

In the present invention, the (meth)acrylic acid alkyl ester unit refers to a methacrylic acid alkyl ester and/or acrylic ester unit, and the same expression will be used hereinafter.

In the water-soluble salt A of the volatile base of the copolymer, which is an essential component of the aqueous gloss coating composition for printing paper of the present invention, the alkyl (meth)acrylic acid ester constituting the copolymer (provided that the alkyl group Examples of monomers having carbon atoms (10 to 20) include decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, Straight chain or side chain such as pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, eicosanyl (meth)acrylate, etc. Examples include (meth)acrylic acid esters having an alkyl group, and esters made of (meth)acrylic acid and synthetic alcohols having 10 to 20 carbon atoms produced by the oxo method etc. can also be used.

Among these, preferred are alkyl esters of methacrylic acid (provided that the alkyl group is carbon number 12-18). Examples of monomers of Q,8-unsaturated carboxylic acid units include Q,8-unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid, and Q,8-unsaturated dicarboxylic acids such as itaconic acid and maleic anhydride. can be given. Among these, preferred are acrylic acid and methacrylic acid. Examples of vinyl monomer units other than those listed above include methyl acrylate, (meth)
Acrylic acid alkyl esters having a direct mirror or side chain alkyl group having 1 to 8 carbon atoms, such as ethyl acrylate, propyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate; / Or methacrylic acid alkyl ester having a linear or side chain alkyl group having 2 to 8 carbon atoms: vinyl acetate, vinyl propionate, styrene, (meth)acrylonitrile,
Examples include acrylamide and vinyl chloride.

Among these, preferred are ethyl acrylate, butyl acrylate, butyl methacrylate, and vinyl acetate. Volatile bases for forming the water-soluble salt of the volatile base of the copolymer include, for example, ammonia; volatile amines such as trimethylamine, monoethylamine, diethylamine, triethylamine, n-propylamine, n
-butylamine; examples include monoether/butylamine and morpholine. Ammonia is preferred because it volatilizes from the coating film at a relatively low temperature during drying and provides water resistance to the coating film.
The methyl methacrylate unit, which is the main component in the water-soluble salt of the volatile base of the copolymer in the present invention, is necessary to impart gloss and anti-blocking properties to the coating film, and the amount thereof is determined based on the total vinyl monomer units. 70-9 based on weight (before salt formation)
A weight percent of 80 to 9 weight percent is appropriate, but especially when blocking resistance is required, a weight percent of 80 to 9 weight percent is preferable. If the amount of methyl methacrylate units is less than 7% by weight, the melting point of the resin will be less than 11,000, resulting in poor peelability during press working. On the other hand, if it exceeds 90% by weight, the resin will not be crushed easily during pressing and sufficient gloss will not be obtained. The (meth)acrylic acid alkyl ester (alkyl group has 10 to 20 carbon atoms) unit gives the coating film flexibility and smoothness.
The amount is suitably between 5 and 2% by weight, preferably between 10 and 15% by weight, based on the weight of the total vinyl monomer units (before salt formation).
%wt%. When the amount exceeds 2% by weight, the coating film becomes soft and the blocking resistance deteriorates.

Moreover, if it is less than 5% by weight, sufficient maneuverability will not be obtained. Q,6-unsaturated carboxylic acid units are required for the formation of water-soluble salts of the volatile bases of the copolymer, and their amount is 2 based on the weight of the total vinyl monomer units (before salt formation). ~1
% by weight is suitable, preferably from 4 to 1% by weight.

If the amount is more than 1% by weight, the water resistance of the coating film and the peelability during press processing tend to decrease, and if it is less than 2% by weight, the water solubility will not be sufficient when made into a water lacquer salt with a volatile base. .

Vinyl monomer units other than those mentioned above can be used if necessary for the purpose of adjusting the melting point of the copolymer. The amount is usually from 0 to 2% by weight, preferably from 0 to 1% by weight, based on the weight of total vinyl monomer units. If the amount of vinyl monomers other than those mentioned above is more than 2% by weight, sufficient gloss may not be obtained or blocking resistance tends to decrease. The water-soluble salt of the volatile base of the copolymer in the present invention can be produced by a known method. For example, various organic solvents (such as methyl alcohol, ethyl alcohol, n-propyl alcohol, imbropyl alcohol, isobutyl alcohol, etc.; various cellosolves such as methyl alcohol, ethyl alcohol, etc.) ; Hydrocarbon solvents such as benzene, toluene, xylene, hexane, heptane, petroleum naphtha; ethyl acetate,
The monomers are polymerized in solution polymerization, emulsion polymerization, suspension polymerization, etc. in various esters such as butyl acetate; cyclic ethers such as tetrahydrofuran; (re-precipitation method in a non-solvent, solvent distillation method, salt folding method, furnace separation method, etc.), and if an emulsifier is used, remove the emulsifier by washing with water, etc., and neutralize with a volatile base. After that, water can be added to the solution to produce an aqueous solution of the water-soluble salt of the volatile base of the copolymer. Also [2] Water-soluble alcohols (methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, and various cellosolves, etc.)
After solution polymerizing the monomer alone or in a mixed solvent with water, the copolymer is not isolated but neutralized with a volatile base and water is added to reduce the volatility of the copolymer containing a water-soluble alcohol. Aqueous solutions of water-soluble salts of bases can be prepared. A radical initiator is usually used as a polymerization initiator for copolymerization.

Examples of such radical initiators include oil-soluble initiators such as peroxide initiators such as penzoyl peroxide, lauroyl/g-oxide, dicumyl peroxide, and di-t-butyl peroxide; Azo initiators such as nitrile, azobisdimethyl/gereronitrile, etc. are used. As the water-soluble initiator, a redox initiator consisting of a persulfate such as sodium persulfate, potassium persulfate, ammonium persulfate, hydrogen peroxide, and a combination of hydrogen peroxide and ferric chloride or the like is used. The amount of polymerization initiator used is usually 0.01 to 5% by weight based on the weight of total monomers. The polymerization temperature must be selected depending on the difficulty of decomposing the polymerization initiator, and is usually 0 to 15
It is selected and polymerized within the range of 0CO. Polymerization time is usually 1
~2 Cape hours. In addition, for adjusting the degree of polymerization of the copolymer, known chain transfer agents (such as dodecyl mercaptan, n
-Mercaptans such as butyl mercaptan; halogen compounds such as carbon tetrachloride) can also be used if necessary. The weight average molecular weight of the copolymer (before salt formation) in the aqueous solution of the water-soluble salt of the volatile base of the copolymer thus obtained is usually 3,000 to 500,000.

The preferred molecular weight for the gloss paint component is 6000-2.
It is 0000. If the molecular weight is less than 3,000, the resin film forming property is insufficient, and if it exceeds 500,000, handling is difficult. The melting point of the obtained copolymer is usually 110
-15000, preferably 120-1400○.

If the melting point is less than 110 qo, the releasability during press processing will be low, and if it is higher than 150 qo, the resin will not be crushed well during press processing and the gloss will not be sufficient. The water-soluble salt of the volatile base of the copolymer in the resin aqueous solution is produced so that the solid content concentration is usually 20 to 40% by weight, and diluted with water and/or water-soluble alcohol as appropriate depending on the purpose. be done. Also, the pH of the aqueous solution is usually 7.
-10 preferably 8-9. Carbon number 1 which is the other essential component of the aqueous gloss coating composition for printing paper of the present invention
Examples of the higher fatty acids that can be used in the alkali metal salts B of 8 to 22 saturated or unsaturated higher fatty acids include oleic acid, ellaidic acid, stearic acid, isostearic acid, and erucic acid. Among these, preferred are stearic acid and erucic acid. Examples of the alkali metals constituting the alkali metal salts of higher fatty acids include L.
i, Na, K can be given. Among these, preferred are Na and K. Alkali metal salts of higher fatty acids are
It not only improves peelability during press working, but also gives the coating film good anti-flocking properties.

The higher fatty acid has 18 to 22 carbon atoms. Salts of fatty acids with 18 or more carbon atoms tend to reduce peelability and blocking resistance during pressing, while salts of fatty acids with more than 22 carbon atoms do not have sufficient solubility. The aqueous gloss coating composition of the present invention is an aqueous composition containing A and B as essential components.

The ratio of A and B is usually 2 to 2 parts by weight of AIOO.
The amount is 10 parts by weight, preferably 3 to 7 parts by weight. If B is used in an amount greater than 1 part by weight, it tends to reduce the gloss of the coating film. In addition, if it is less than 2 parts by weight, the peelability during pressing may deteriorate.
Blocking resistance is not sufficient. A+B in aqueous composition
It is manufactured so that the solid content concentration is usually 30 to 4% by weight, but when used during processing, it is used after being diluted with water and/or water-soluble alcohol as appropriate.

The method for producing the composition of the present invention is not particularly limited.

For example, there is a method in which a copolymer is produced, neutralized with a basic substance, and then the salt of the higher fatty acid is blended therein, or a method is produced in which a copolymer is produced, a salt of a higher fatty acid is blended, and then neutralized with a basic substance. can give. The former method is preferred. Further, the composition of the present invention may contain optional components in addition to the above-mentioned essential components.

As such an optional component, a low-boiling water-removal solvent can be used in combination to adjust the viscosity or improve drying properties.
Examples of these solvents that can be used include alcoholic solvents such as methyl alcohol, ethyl alcohol, n-propyl alcohol, inpropyl alcohol, n-butyl alcohol, isobutyl alcohol, and t-butyl alcohol; acetone; and tetrahydrofuran; It may also be the one used during the production of the combined salt. The amount of the low-boiling water-soluble solvent used is generally 3% by weight or less, preferably 96% by weight or less of the total composition. The volatile base salt of the English polymer in the present invention is soluble in water itself, but
A high-boiling water-soluble solvent can be used to increase solubility or improve stiffness during application.

Examples of such solvents include glycols such as ethylene glycol, diethylene glycol, and propylene glycol; ether alcohols such as ethylene glycol;
monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether;
Ether esters such as ethylene alcohol/lemonomethyl ether acetate; alcohols such as diacetone alcohol, tetrahydrofurfuryl alcohol, 2-ethylhexanol, octanol, 3-methyl-3-methoxybutanol; others such as dioxane and dimethylformamide are effective. It is. The amount of the high-boiling water-soluble solvent used is usually 1% by weight or less, preferably 5% by weight or less based on the total composition. It is also optional to add a wax, such as a polyethylene wax, particularly for the purpose of improving the abrasion resistance of the coating film.

The amount used is usually 5% by weight or less, preferably 1% by weight or less, based on the total composition. In order to further improve the releasability, a nonionic or anionic surfactant, a water-soluble silicone compound, a silicone emulsion, or the like may be used in combination. The amount of surfactant or silicone emulsion used is usually 5% by weight or less, preferably 1% by weight or less, based on the total composition. Examples of printing paper to which the composition of the present invention is applied include papers printed by gravure, offset, etc. (art paper, coated paper, cardboard), and offset printing paper is usually applied.

Examples of the forms of printed paper include book covers, calendars, and postcards. The composition of the present invention is applied to paper, dried, and then processed using a hot press.

Coating can be carried out using known coating equipment such as a gravure coater or a roll coater. The coating amount is usually 3 to 1 spot/preferably 5 to 10 g in terms of total solid weight.
Nome desu. If the coating amount is less than 15g/force, sufficient gloss will not be obtained, and if it exceeds 15g/force, the gloss will not be particularly improved. Drying is performed using an infrared ray or steam-heated circulating air dryer. Hot press processing can be performed using a flat press, an endless press, a cylinder press, or the like.
The temperature of the press is usually 90 to 140°C, preferably 110 to 130°C. The film formed by applying the composition of the present invention to an offset printed matter using a roll coater or gravure coater and hot pressing after drying is
Compared to those processed with conventional organic solvent-based paints, there is no inferiority in gloss or other physical properties of the paint film.

Furthermore, it has excellent blocking resistance, abrasion resistance, and scratch resistance compared to acrylic resin-based aqueous compositions other than the composition of the present invention. The composition of the present invention is an aqueous composition and does not substantially require the use of organic solvents, and even if used, only a small amount is required. Therefore, compared to conventional compositions of hydrophobic resins containing organic solvents, there is no need to use organic solvents. There is no risk of explosion, little toxicity to the human body, and no problems such as air pollution.

Next, embodiments of the present invention will be described.

"%" in the examples is "% by weight". Examples-1 to 3
, Comparative Examples 1 to 3 The polymerization method was carried out using a 4-inch solo reactor equipped with a dropping funnel, a cooler, a dropper, and a nitrogen gas introduction tube.

To a predetermined amount of the monomer mixture shown in Table 1, predetermined amounts of azobisisobutyronitrile, lauryl mercaptan, and 20% of ethanol based on the total monomer components are charged into a dropping funnel. Ethanol containing 70% of the total monomer components was charged into a container, and after purging with nitrogen, the temperature was raised to 76 oo, and the mixture in the dropping funnel was added dropwise over 3 hours while refluxing, and was further aged for 4 hours. After the reaction is completed, 25% aqueous ammonia and water are added to adjust the pH to 8-9. To this aqueous copolymer solution, the amounts shown in Table 2 of alkali metal salts of higher fatty acids, wax fine dispersion, and ethylene glycol monobutyl ether were added and mixed uniformly, and ethanol and water were added to make the solid content approximately 3.
A 0% paint was created. This paint was then mixed with ethanol/
Dilute with a mixed solvent having a water ratio of 40/60 so that the solid content is about 25%. This was applied to an offset printed material in a coating amount of about 6 g/solid content, dried in a hot air circulation dryer for 8,000 x 5 seconds, and using an endless press at a temperature of 13,000 and a press pressure of 250 k9/ground. Press speed 2
When press working was carried out under the conditions of 2 h/min, the peeling from the press plate was extremely good and a smooth glossy surface was obtained. In Examples 2 to 3 and Comparative Examples 1 to 3, paints were manufactured using the same polymerization method and blending method, and were applied, dried, and pressed under the same conditions. Table 3 shows Examples and Comparative Examples of the composition of the present invention, and comparative test results with conventional organic solvent-based gloss paints.

Table-1: Copolymer aqueous liquid formulation Note) Numbers other than melting point indicate parts by weight.

Table-2: Composition formulation Note child fable ho o Table-3: Coating film physical properties note)

Claims (1)

[Claims] 1 70-90% by weight of methyl methacrylate units, 5-20% by weight of (meth)acrylic acid alkyl ester (however, the number of carbon atoms in the alkyl group is 10-20) units, 2-10% by weight of α,β-unsaturated carboxylic acid units %, and 1 to 10 parts by weight of a water-soluble salt of a volatile base of a copolymer with a melting point of 110 to 150°C containing 0 to 20% by weight of vinyl monomer units other than those mentioned above, based on 100 parts by weight of A and (2) A. An aqueous gloss coating composition for printing paper, characterized in that it contains as an essential component an alkali metal salt B of a saturated or unsaturated higher fatty acid having 18 to 22 carbon atoms.