JPS60209094A - Paper coating composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a paper coating composition that has excellent printing gloss, adhesive strength and water resistance on naval paper.

[Technology background]

Coated paper is made by coating human blood on the base paper with a paper coating composition such as a pigment and a binder F, such as latex to which the pigment is attached, to form a coating layer.

The characteristics of iA coated paper are that it has a printing gloss that is superior to the aesthetics of printed matter, and as printing speeds increase, the coating layer has a sufficiently high adhesive strength t- and a large adhesive strength to the base paper. Water resistance is important.

Incidentally, in recent years, for the purpose of improving productivity and reducing manufacturing costs, there has been a trend to improve the solidity of paper wing compositions to save labor in the process of drying the coated layer. Generally, a large amount of calcium carbonate is used as a pigment in order to improve the decrease in fluidity due to high solidification of paper coating compositions. However, paper coating compositions containing a large amount of calcium carbonate may result in coated paper with insufficient printing gloss, and depending on the particle size of the calcium carbonate used, may have insufficient adhesive strength and water resistance. There is a problem that it cannot be obtained.

Techniques aimed at solving such problems through the t-latex reform IXIIL include, for example,
191392 and JP-A-50-94034, which use a carboxy-modified styrene-butadiene copolymer latex using a vinyl cyanide compound as one of the vinyl monomer components, are known. Even with these methods, it is not possible to obtain sufficiently satisfactory printing gloss, adhesive strength, and water resistance.

[Purpose of the invention]

The present invention was made against the above background, and its purpose is to provide a paper coating composition that forms coated paper with excellent printing gloss, adhesive strength, and water resistance. We aim to provide the following.

[Structure of the invention]

The feature of the present invention is that it contains a pigment and a comonomerized 2tex that satisfies the following conditions.

Condition (a): The copolymer latex meets the following conditions (a):
It must be obtained from the monomer composition of (bl and ←).

(a) Vinyl cyanide monomer 10 to 40% by weight Φ-ethylene thread unsaturated carbon ester monomer 52 to 89% by weight - (C) Ethylenically unsaturated carboxylic monomer
It% Conditions (Ron; Glue content must be 70% or more; Saturation f
The idy lath transition temperature is -30 to 10°C.

Conditions): The average particle size of the latex particles should be 600 to 2000A.

The present invention will be explained in detail below.

The copolymer latex constituting the paper coating composition of the present invention contains (a) vinyl cyanide monomer, Φ) ethylenically unsaturated carboxylic acid ester monomer and (C ) Examples of the ethylenically unsaturated carbonated vinyl monomer include aliphatic unsaturated nitrile a such as acrylonidine, methacrylonitrile% a-chloroacrylotrile, and 4-ethyl acrylonitrile.

Among these, acrylonitrile is particularly preferred.

The amount of vinyl cyanide monomer used is 10 to 40% by weight, preferably 15 to 30% by weight based on the total amount of the monomer composition.
It is. If the amount used exceeds 40M1tIb, the adhesive strength on coated paper will decrease significantly; on the other hand, the amount used will be 10!
If it is less than 196, sufficient printing gloss cannot be obtained.

(b) Examples of the ethylenically unsaturated carboxylic acid ester monomer include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, and acrylic acid. Diuryl methacrylate, methyl methacrylate, diuryl methacrylate, etc. can be given as ff16. These monomers can be used alone or in combination of 2 [i or more.

The amount of the ethylenically unsaturated carboxylic acid ester monomer used is 52 to 89% by weight based on the total amount of the monomer composition. If the amount used exceeds 89% by weight, the printing gloss on the coated paper will be insufficient, while if the amount used is less than 52% by weight, the adhesive strength will be insufficient.

Examples of the ethylenically unsaturated carboxylic acid monomer (C) include acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, and bovine ester of dicarboxylic acid. These monomers #1 single 8
A combination of 6 or 2a or more can be used.

The amount of the ethylenically unsaturated carboxylic acid monomer used is 1 to 8 weight, preferably 2 to 5 weight, based on the total amount of the monomer composition. If the amount used exceeds 8 parts by weight, the water resistance of the coated paper will be insufficient, while if the amount used is less than 1 part weight, the coated paper will have insufficient adhesive strength and mechanical stability.

The gel content of the copolymer latex constituting the paper coating composition of the present invention is 70 Ts or more, preferably 5 Ots or more. If the gel content is less than 70, the adhesive strength and print gloss on coated paper will be insufficient.

Here, "gel content" means that after adjusting the obtained copolymer latex to pH 8.5, coagulating it with methanol, washing and drying, a predetermined amount of sample j1 (approximately 0.3 f) ( After immersing the sample in 100 mg of benzene for 20 hours, the benzene insoluble content was measured and expressed as a weight relative to the sample.

The gel content of the copolymer latex can be adjusted by using a chain transfer agent that is commonly used in emulsion polymerization. These chain transfer agents include, for example, p-roform,
Halogenated hydrocarbons such as bromoform, carbon tetrachloride, carbon tetrabromide, mercaptans such as n-hexylmercaptan, n-octylmercaptan, t-octylmercaptan, n-dodecylmercaptan, t-dodecylmercaptan, dimethylxanthogen All xanthogens that can be used in normal emulsion polymerization, such as disulfide and birxanthogen disulfide, can be used in CC.
use These can be used alone or in combination of two or more. The addition method may be one-time addition, multi-part addition, or continuous addition.

Paper m-working composition f of the present invention: The glass transition temperature range of the constituting copolymer latex is -30 to 10°C, preferably -25 to 10°C. If the glass transition temperature exceeds 10°C, the adhesive strength of the coated paper will be affected;
If the temperature is less than 0.degree. C., printing gloss and water resistance will be insufficient.

Here &C1, the "glass transition temperature" refers to the temperature of the copolymer latex dried and the resulting dry matter measured using a differential scanning calorimeter "D".
Calculate with the value obtained by measuring with 8C910IIJ (manufactured by DuPont).

The glass transition temperature can be adjusted by appropriately selecting the type or amount ft of the ethylenically unsaturated carboxylic acid ester monomer used in the production of the copolymer latex.

The average particle diameter of latex particles in the copolymer latex constituting the paper coating composition of the present invention is 600 to zoo
oX, tL< is 800-1600X; b. If the average particle size exceeds 2000K, the printing gloss and adhesive strength on coated paper will be insufficient9, and if the average particle size is less than 800A, the adhesive strength will be insufficient0Here, "average particle size of latex particles" is a value obtained by diluting the copolymer latex with distilled water and measuring the diluted solution using a dynamic light scattering device "Coulter Nanosizer" (manufactured by Coulter Inc.).

The average particle size of the latex particles can be adjusted by adjusting the amount of water or emulsifier used during packaging of the copolymer latex. In addition, as an emulsifier, alkyl sulfate,
Anionic surfactants such as alkyl sulfonates and alkylaryl sulfonates, polyethylene glycol,
Nonionic surfactants such as alkylphenyl ethers and polyoxyethylene alkyl esters can be used, and one or more of these may be used in combination.

The paper coating composition of the present invention comprises mineral pigments commonly used for paper coating such as clay, barium sulfate, titanium oxide, calcium carbonate, satin white, etc., and the above-mentioned copolymer as a pigment binder. The amount of the copolymer latex used as the binder is based on 100 parts by weight of the pigment. Preferably 5-40
Parts by weight. If the amount used exceeds 40 parts by weight, the ink receptivity will be low and the appearance of printed matter will be seriously impaired. On the other hand, if the amount used is less than 5 parts by weight, the adhesive strength will be insufficient.

The mineral pigment also preferably contains at least 3031 amounts of calcium carbonate. As the charcoal calcium, heavy calcium carbonate, light calcium carbonate, or a mixture of both can be used. The pigment used in combination with calcium carbonate is not particularly limited, and the pigments mentioned above can be used.

Furthermore, various commonly used compounding agents such as water resistance improvers, water resistance reaction accelerators, pigment dispersants, viscosity modifiers, coloring pigments, fluorescent dyes, or pH adjusters can also be optionally added. . [Effects of the Invention] The paper coating composition of the present invention contains a vinyl cyanide monomer,
A special copolymer latex obtained by copolymerizing an ethylenically unsaturated carboxylic acid ester monomer and an ethylenically unsaturated carboxylic acid monomer is used, and as is clear from the examples described below. , excellent printing gloss on coated paper, adhesive strength, and water resistance.

Moreover, the paper coating composition of the present invention maintains excellent properties even when the content ratio of calcium carbonate in the pigment is low, and is particularly useful as a paper coating composition with a high isomorphic content.

〔Example〕

Examples of the present invention will be described below. Note that "part" and "chi" represent parts by weight and weight S, respectively.

Examples 1-6. Comparative Examples 1 to 9 Production of copolymer latex Each of the monomer components and additives (all composition ratios are parts) shown in Table 1 (Examples) and Table 2 (Comparative Examples) and 150 parts of water parts (200 parts only in Comparative Example 2) were placed in an autoclave and heated to 60 parts under a nitrogen gas atmosphere.
The reaction was carried out for 2 hours at a temperature of 70°C, and the reaction was continued for 2 hours at a temperature of 70°C. A copolymer latex of If was obtained. The polymerization conversion rates of these copolymer latexes were all 99% or more. In addition, the gel content, glass transition temperature, and average particle size of each copolymer latex obtained were determined by the methods described above. So(
The results of D@ are also shown in Table 1 and Section 2. In addition, the second
The under 2 in attached to the numerical value in the table indicates that this numerical value is outside the scope of the present invention. A composition for coating υ paper was prepared according to the following recipe. Part ratio: 70 parts clay (contains 0.5% sodium bitetraphosphate as a dispersant) 30 parts calcium carbonate 10 parts copolymer latex (solid) (as minute) oxidized starch
5 parts water: Added a sufficient amount to make the total solids content 60%. Each of the obtained paper coating compositions was coated by the blade coating method, and the coated paper obtained was subjected to the following % property test. I did this.

Characteristic Trial Sales (1) Dry pick (determination of adhesive strength) test was performed using an RI printing trial machine. Test piece t) Fixed at 2 mm, continued printing repeatedly at a speed of 30 rpm, stopped printing after a certain period of time, and judged by the naked eye. 5 points were determined as 0 for those that were completely printed, and 5 points were for those that were barely printed. The t-1 point is taken as the point, and the intermediate point is given a score according to its degree, and the t-arithmetic average of the five data obtained from each sample is calculated.

Q) Wet Vic (determination of water resistance) The test was conducted using a Riko Printing Test M machine. Water is applied once to a test piece fixed on a drum, and after a certain period of time, printing is performed once, and the test piece is judged by the same method as in the case of dry pick described above.

(3) The printing gloss test was performed using a Le1 printing test machine. The test piece is fixed to a drum and printed once at a speed of 39 rpm, then left for 24 hours, and the gloss of the printed surface of the test piece is measured using a Murakami gloss meter.

The results of each test are shown in Table 2.

In addition, the under 2 in attached to the numerical value in the second garment is
This indicates that the physical property values have not reached the target values for the peak period.

From the above results, regarding the examples of the present invention.

It has been found that both dry and wet printing are generally excellent in terms of printing gloss. On the other hand, in the comparative examples, it was found that all the properties were generally inferior to those of the examples of the present invention, and in each comparative example, some of the properties were significantly lower.

Example 7.8. Comparative Example 10.11 A paper coating composition t-a was prepared in the same manner as the above-mentioned formulation except that the content ratio of calcium carbonate in the pigment was as shown in Table 3. The copolymer latex used in Example 7 and Example 8 was the same as that used in Example 1, and the copolymer latex used in Comparative Example 10 and Comparative Example 11 was the same as that used in Example 1.
In , styrene-butadiene copolymer latex (
Polymerization ratio of styrene and butadiene 60:40) Deru 0
Next, the coated paper obtained using these paper coating compositions was coated and the properties of dry pick, wet pick, and printing gloss were examined using the methods described above. The results are also shown in Table 3.

No. 3 The above results show that in this example, there was no major change in the properties of the coated paper even with IT, Dry Vic, Wet Pick, and printing gloss, and it was confirmed that good properties would be maintained. It was done. On the other hand, in the comparative example, % of total 1
It was found that the properties of the coated paper were generally inferior to those of the examples of the present invention.

Claims (1)

[Scope of Claims] 1) A paper coating composition characterized by containing a copolymer latex that satisfies the following conditions (a) to conditions) and a pigment. Condition 0): The copolymer latex is below @il! (a
), Φ) and <c>. (a) Vinyl cyanide monomer IO to 40 weight (b) x f v unsaturated carboxylic ester monomer 52 to 89 N (C) ethylenically unsaturated carboxylic acid monomer 1 to 89 N 8]
L certificate - Conditions ←); Gel content must be 70% or more. Article fFet: Glass transition temperature must be -30 to IOC. In the row f+); the average particle diameter of the latex particles is 600 h
L 200 oX-c; bb. 2) The paper coating composition according to item 1, wherein the pigment contains 30% by weight or more of calcium carbonate.