JPH0672397B2 - How to give gloss to the surface of paper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a method for imparting excellent gloss to the surface of paper and further improving various properties such as abrasion resistance, scratch resistance and water resistance. .

[Prior Art] In cosmetic boxes, book covers, match covers, calendars, etc., it is widely performed to apply gloss and deluxe by applying a resin solution on the printing surface and drying. . Recently, an aqueous solution of a styrene-acrylic copolymer has been used as a resin used for the purpose of such a gloss coating, but it is rarely used as a binary copolymer as it is, for example, JP-A-50-119031. It has been devised to improve the physical properties of the copolymer, for example, by introducing a vinyl monomer having a hydroxyl group into the copolymer as proposed in the publications and the like.

[Problems to be Solved by the Invention] However, with the recent rapid development of printing technology, on the other hand, various kinds of colors can be freely and finely expressed on paper. It is the current situation that it is no longer possible to adequately deal with glossiness imparted by using. In other words, in the printing industry 1) Higher and more uniform gloss is required 2) Excellent adhesion to printing inks of all kinds of colors on the printing paper surface 3) During transportation Therefore, further improvement of various physical properties such as having excellent abrasion resistance that does not impair gloss even by friction such as is required.

[Means for Solving Problems] However, as a result of the inventors of the present invention having been engaged in intensive research to satisfy more recent high requirements, (a) styrene and / or (meth) acrylic ester
50 to 89.9% by weight, (b) 0.1 to 6.0% by weight of an amide monomer containing a hydroxyl group or an alkoxy group (c) 10 to 20% by weight of an acidic monomer (d) 0 to 39.9% by weight of another copolymerizable monomer It has been found that the physical properties of 1), 2) and 3) described above are remarkably improved by applying an aqueous solution of the copolymer to the printed surface and then drying the solution, and completed the present invention.

(B) an essential component of the copolymer used in the present invention
As for the component and the component (c), the monomer species themselves are those disclosed in JP-A-50-119031, as described below, but in the present invention, it is not necessary to simply use the essential component. Not using a specific quantity range, ie (b)
Not only when each of them is used alone, but also by using a small amount of 0.1 to 6.0% by weight in the component and a large amount of 10 to 20% by weight in the component (c), the above-mentioned JP-A-50 is used. It is possible to obtain a synergistic effect that cannot be imagined from the effect disclosed in Japanese Patent Laid-Open No. 119031.

Hereinafter, each of the (a) to the copolymer used in the present invention
The component (b) will be described separately.

In the present invention, at least one of (a) styrene and (meth) acrylic acid ester is the main component of the copolymer.
When the amount of component (a) is less than the above range, the softening temperature of the copolymer is lowered, workability during coating tends to be poor, and the gloss of the coated surface tends to be unfavorable. As the (meth) acrylic acid ester, an alkyl ester having 1 to 8 carbon atoms is desirable, typically, methyl acrylate,
Ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, and the like, but especially methyl methacrylate Preferably used.

(B) The amide monomer having a hydroxyl group or an alkoxy group should be 0.1 to 6.0% by weight, preferably 0.5 to 6.0% by weight in the copolymer. Other than this range, even if other copolymer components are within the scope of the present invention, the balance of physical properties, glossiness, adhesion, abrasion resistance, water resistance, solvent resistance and the like is lost, It is impossible to achieve the purpose of. Further, as a monomer species, the effect cannot be recognized with a monomer having only a hydroxyl group such as 2-hydroxyethyl acrylic acid ester, and it must always contain an amide group. Specific examples of the component (b) include N-methylol acrylamide and N-
Methylol methacrylamide, N-ethylol acrylamide, N-ethylol methacrylamide, N, N-dimethylol acrylamide, N, N-diethyl methacrylamide, N-methoxymethyl acrylamide, N-methoxymethyl methacrylamide, N-ethoxy Methyl acrylamide, N-ethoxymethyl methacrylamide,
N- (n-propoxy) methylacrylamide, N-
(N-propoxy) methylmethacrylamide, N- (n
-Butoxy) methyl acrylamide, N- (n-butoxy) methyl methacrylamide, etc. are mentioned, but mainly N-methylol acrylamide, N-methylol methacrylamide, N- (n-butoxy) methyl acrylamide, N- (n-butoxy). ) The use of methylmethacrylamide is preferred.

The amount of the acidic monomer (c) in the copolymer is 10 to 20% by weight, more preferably 10 to 15% by weight. Only within this range and when it is used in combination with the component (b), the remarkable effect of the present invention can be obtained. If it is less than 10% by weight, gloss and adhesion are deteriorated, and if it is more than 20% by weight, water resistance, It causes deterioration of physical properties such as solvent resistance. Examples of the component (c) include acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, icotanic acid, aconitic acid and their anhydrides, alkali metal salts, ammonium salts and the like.

(D) Other copolymerizable monomers are 39.9% in the copolymer.
Any amount can be used as long as it is less than the weight%, but if it is used in such a range or more, not only the effect but also the practical use cannot be obtained. Examples of the component (d) include dimethylaminoethyl acrylate, diethylaminoethyl acrylate, butylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, dibutylaminoethyl methacrylate, 2-
Vinyl pyridine, 4-vinyl pyridine, N-vinyl imidazole, 2-methyl-N-vinyl imidazole, 2-
Ethyl-5-vinylpyridine, dimethylallylamine,
Other than diallylamine, vinyl acetate, vinyltoluene,
Vinyl versatate, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, glycidyl acrylate, glycidyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxylethyl acrylate, hydroxylpropyl acrylate and the like can be used, but among them, dimethylaminoethyl Methacrylate and diethylaminoethyl methacrylate used in an amount of 10% by weight or less, more preferably 0.5 to 8.0% by weight are useful for improving the balance of various performances and stability of the aqueous solution.

The copolymer is a bulk polymerization method, a solution polymerization method, an emulsion polymerization method,
Although it can be produced by any method such as a suspension polymerization method, a solution polymerization method is generally used in which heating is performed in a solvent such as toluene, xylene or ethyl acetate in the presence of a polymerization initiator under the introduction of an inert gas.

As the polymerization initiator, an azo-based polymerization initiator, for example, azobisisobutyronitrile, a peroxide-based polymerization initiator such as azobismethylvaleronitrile, for example, acetyl peroxide, butyl peroxide, benzoyl peroxide or the like is optionally used. Can be used.

The obtained copolymer is neutralized or water-solubilized as it is or if necessary with an aqueous alkali solution or an aqueous ammonia solution, and then usually applied on the paper surface as an aqueous solution having a resin solid content concentration of 30 to 60% by weight. As a coating means, any means such as a roll coating method, a brush coating method, a curtain flow coating, a spray coating and a doctor coating can be adopted. The coating amount is usually appropriately adjusted so that the film thickness after drying is 3 to 20 μ, but is not particularly limited as long as the printed surface is beautifully and completely protected.

After coating, it is dried at a temperature of 50 to 100 ° C. A known method is appropriately adopted as the drying means.

According to the method of the present invention, a transparent coating film having excellent adhesiveness and gloss can be obtained at such a stage, but when a coating film having a further excellent gloss is desired, hot pressing is applied to the coated surface after drying. Give. The hot press is to apply a mirror surface plate made of stainless steel, aluminum, etc. to the resin surface obtained by applying it on printing paper,
An appropriate number of sheets are alternately stacked and hot pressed at about 70 to 150 ° C., or a mirror-finished plate is formed into an endless belt shape and passed between hot rollers for continuous processing.

According to the method of the present invention, there is also an operational advantage that the peeling of the paper from the mirror plate, which has been a problem during such hot pressing, can be carried out very smoothly.

When the method of the present invention is adopted, the copolymer used in the present invention is used by blending it with another resin as long as it does not deteriorate the excellent physical properties such as adhesion, gloss and abrasion resistance. You can do anything. As such a resin, vinyl chloride-vinyl acetate copolymer, vinyl chloride resin, acrylic resin or the like is used in an amount of 0 to 50 relative to the copolymer.
It is blended in a weight percentage.

[Examples] Next, the method of the present invention will be further described with reference to Examples. Hereinafter, "part" and "%" are based on weight unless otherwise specified.

Example 1 Aqueous ammonia solution was added to 100 parts of a copolymer consisting of 60% styrene, 25% methyl methacrylate, 5% N-methylolacrylamide and 10% acrylic acid to dissolve and neutralize, and then the resin solid content concentration was 50. % Aqueous solution was prepared. Using a hand applicator, apply this to a 1 mm thick printed cardboard (concentrically printed in three colors of red, yellow and black) to a film thickness of 10μ, and dry with hot air at 80 ° C for 10 seconds. did. The obtained coating was tested as described below to evaluate its performance.

The results are shown in Table 1.

Example 2 In Example 1, styrene, methylmethacrylate, N
-Performance was evaluated in the same manner except that the copolymerization ratios of methylol acrylamide and acrylic acid were changed to 10%, 72%, 3% and 15%, respectively.

The results are shown in Table 1.

Example 3 The same as Example 1 except that a copolymer having a composition of 60% styrene, 25% methyl methacrylate, 0.5% N-methylolacrylamide, 4.5% dimethylaminoethyl methacrylate and 10% acrylic acid was used. Performance evaluation was performed.

The results are shown in Table 1.

Example 4 An aqueous ammonia solution was added to a copolymer having a composition of 62% styrene, 25% methyl methacrylate, 3% N-butoxyacrylamide and 10% maleic anhydride to dissolve it, and the resin concentration was adjusted to 35%. did.

This aqueous solution was applied to the printed surface according to Example 1 to evaluate the performance of the coating film.

The results are shown in Table 1.

Examples 5-7 Instead of the N-methylol acrylamide used in Example 1, N-methylol methacrylamide (Example 5), N-butoxy acrylamide (Example 6), N-
An experiment was conducted in the same manner as in the example except that butoxymethacrylamide (Example 7) was used.

The results are shown in Table 1.

Comparative Examples 1 and 2 The same experiment as in Example 1 was performed without using N-methylolacrylamide as a copolymerization component (Control Example 1) and without using acrylic acid (Control Example 2).

The results are shown in Table 1.

Control Examples 3 to 5 Copolymer composition: styrene 65%, methyl methacrylate 20
%, N-methylolacrylamide 15% (control example 3),
Styrene 60%, methyl methacrylate 23%, N-methylol acrylamide 12%, acrylic acid 5% (Control Example 4),
Styrene 61%, methyl methacrylate 30%, N-methylolacrylamide 5%, acrylic acid 4% (Comparative Example 5) In Example 1, N-methylolacrylamide was replaced by 2-hydroxyethylmethacrylate 5% instead of N-methylolacrylamide. The same experiment was carried out in the same manner as in Example 1 except that the one used (Control Example 6) was used.

The results are shown in Table 1.

The performance was evaluated by the following method.

Scratch adhesion: The degree of peeling of the coating film when the coated surface is rubbed with a clip 5: no change, 4: almost no change,
3: There is a little peeling: 2: There is noticeable peeling, 1: It is shown with peeling entirely.

・ Tape adhesion: A cellophane tape is applied on the coated surface, and the degree of peeling of the coating film when rapidly peeled off is 5: the entire base material (paper layer)
Peeling off, 4: Most peeled off the substrate, 3: Part peeled off the substrate, 2: Most peeled off the coated surface, 1: Total peeling off the coated surface.

-Gloss: Five-level evaluation was performed by visual inspection.

Gloss: Gloss meter 60 ° -60 ° by reflection.

-Abrasion resistance: The results are shown as a value of abrasion weight (g) x 1,000 under the conditions of a Taber abrasion tester and a load of 500 g x 100 rotations.

・ Blocking resistance: 400g at 50 ℃ and 90% relative humidity
After being left under a load of / cm ² for 6 hours, the coated surfaces are overlapped, and the degree of blocking when rapidly peeled by hand is 5: very good peeling, 4: easy peeling, 3: slightly blocking, 2: There is a lot of blocking, 1: Completely blocked.

Claims (1)

[Claims] (A) 50 to 89.9% by weight of styrene and / or (meth) acrylic acid ester, (b) 0.1 to 6.0% by weight of an amide monomer containing a hydroxyl group or an alkoxy group, and (c) 10 to 20% of an acidic monomer. % (D) A method for imparting gloss to the surface of paper, which comprises applying an aqueous solution of a copolymer consisting of 0 to 39.9% by weight of other copolymerizable monomer to a printing surface and then drying.