JPS62268897A - 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 A1.Object of the invention [Field of industrial application] The present invention relates to a composition for coating paper. More specifically, by using a base copolymer latex obtained by using a specific emulsifier, coated paper with good printability such as wet pick strength, dry pick strength, ink receptivity, and blister resistance is produced. The present invention relates to an improved paper coating composition which provides the following properties.

[Conventional technology]

Anionic surfactants such as alkyl sulfates and alkylbenzenesulfonates have been conventionally used as emulsifiers for synthetic copolymer latexes used in paper coating compositions.

[Problem to be Solved by the Present Invention No. 3] The development of coating technology and printing technology in recent years has been remarkable. In addition, in order to cope with the increase in the number of printed materials, as well as to streamline and save labor, efforts are being made to speed up the processing of coating and printing processes.

In order to speed up printing, rotary offset printing (hereinafter referred to as "off-wheel") printing has been adopted in recent years, and its spread is remarkable today. With the spread of off-wheel printing, coated paper is required to have various performances such as wet pick strength, dry pick strength, ink receptivity, and blister resistance to withstand high-speed off-wheel printing. These performances are
It is known that this is influenced by the properties of the synthetic copolymer latex contained as the main binder component in the paper coating composition. However, it is also known that there is a reciprocal relationship between the properties of the coated paper (i.e., improving the dry pick strength and wet pick strength will result in a decrease in blister resistance). However, even if the 1fc ink receptivity is completely improved, there is a problem in that the dry shock strength and wet shock strength decrease, and it is currently not possible to obtain a paper coating composition that satisfies all printability requirements. Therefore, this improvement is desired.

As a result of intensive studies to solve these problems, the inventors of the present invention have developed a paper coating mainly containing a synthetic copolymer latex obtained by emulsion polymerization using a specific anionic surfactant, and a mineral pigment. Wet pick strength of the coated paper obtained by performing paper coating treatment with the composition for
It was discovered that the properties such as dry pick strength, ink receptivity, and blister resistance were significantly improved, and the present invention was completed.

Structure of the Invention [Tth Means for Solving Problems] That is, the present invention provides an aliphatic conjugated diene-based simple substance 19.
5-39% by weight, 0 ethylenically unsaturated carboxylic acid monomers
．． For 100 parts by weight of a monomer mixture consisting of 5-10% by weight and 51-8ON monoolefin monomers copolymerizable with these, a compound represented by the following general formula (a) and/or (b) is used. A copolymer latex obtained by molding the monomer mixture in the presence of 0.1 to 5 parts by weight of an anionic surfactant, a mineral pigment, and a gold main ingredient. All paper coating compositions are provided.

General formula: Here, R is an alkyl group having 4 to 20 carbon atoms or a hydrocarbon group containing an aromatic ring, n is an integer of 2 to 70, and M is N
a, K or NH4.

Here, R' is an alkyl group having 4 to 20 carbon atoms, and n' is 2
-70 integer and M' is Na5Klt is NH.

The present invention will be explained in more detail below.

Examples of the aliphatic conjugated diene monomer used in θ# in the present invention include 1,3-butadiene, 2-methyl-1,3-phtadiene, 2-chloro-1,3-methylbutadiene, etc. However, 1,3-butadiene is particularly preferred.

Aliphatic conjugated diene monomers are used in 19.5 to 39 heavy molecules, but if it is less than 19.5 weight percent, the dry and big strength will decrease, and if it exceeds 39 weight percent, the wet pink strength will decrease. 0 Examples of the ethylenically unsaturated carboxylic acid monomer used in the present invention include acrylic acid, meccrylic acid, fumaric acid, maleic acid, and itaconic acid. can be used in combination of two or more types. The ethylenically unsaturated carboxylic acid monomer is used in an amount of 0.5 to 10% by weight, but if it is less than 0.5% by weight, the dry viscoelastic strength and mechanical stability of the latex will decrease;
If the viscosity of the latex exceeds 1, the viscosity of the latex will become too high.
It's not right.

The copolymerizable monoolefin monomers used in the present invention include alkenyl aromatic monomers, unsaturated carboxylic acid alkyl ester monomers, unsaturated monomers containing hydroxyalkyl groups, and cyanide monomers. Examples include vinyl monomers, ethylenically unsaturated carboxyl, acid amide monomers, and the like.

Examples of the alkenyl aromatic monomer include styrene, alpha methyl styrene, methyl alpha methyl styrene, vinyl toluene, etc., with styrene being particularly preferred.

Examples of unsaturated carboxylic acid alkyl ester monomers include methyl acrylate, methyl methacrylate, ethyl acrylate A%, 7L/7;
Examples include 2-ethylhexyl acrylate, chrycidyl methacrylate, dimethyl fumarate, dimethyl maleate, diethyl maleate, dimethyl itaconate, monomethyl fumarate, monoethyl fumarate, etc.
Particularly preferred is methyl methacrylate.

Examples of unsaturated monomers containing a hydroxyalkyl group include β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxybutyl methacrylate, 3-chloro-2
-Hydroxybutyl methacrylate, di(ethylene glycol) maleate, di(ethylene glycol) itaconate, 2-hydroxyethyl maleate, bis-
(2-hydroxyethyl) maleate, 2-hydroxyethyl fumarate, and the like.

Examples of vinyl cyanide monomers include aliphatic unsaturated nitriles such as acrylonitrile, alpha chloroacrylonitrile, methacrylaterile, and alpha ethyl acrylonitrile.

These monoolefin monomers can be used alone or in combination of two or more.

17ic, monoolefin monomer is used in an amount of 51 to 80% by weight, but if it is less than 51% by weight, the wet-bick strength decreases, and if it exceeds 80% by weight, the dry-bick strength decreases, which is not preferable. .

The anionic surfactant used in the present invention is a compound represented by the following general formula (a) and/'' or (b) in an amount of 01 to 5 parts by weight based on 100 parts by weight of the monomer mixture. However, if it is less than 0.1 part by weight, the stability of the latex decreases, and if it exceeds 5 parts by weight, the wet pink strength decreases, which is not preferable.

General formula: Here, R is an alkyl group having 4 to 20 carbon atoms or a carbon arsenide group containing an aromatic ring, n is an integer of 2 to 70, and M is N
a, ni'jfcUNH4.

Cocote, R' is an alkyl group having 4 to 20 carbon atoms, n'U
An integer from 2 to 70 and M9iNa, Kl or NH4.

Further, the number of moles of ethylene oxide added in the anionic surfactants (a) and (b) is an integer of 2 to 70, but if it deviates from this range, the wet pick strength will decrease, which is not preferable.

The method of adding various components in the emulsion polymerization of the present invention is not particularly limited, and may be any of a batch addition method, a divided addition method, and a continuous addition method. Alternatively, a so-called two-stage polymerization method or a power feed polymerization method may be used, in which the monomer composition is changed during the polymerization process. Furthermore, in emulsion polymerization,
Commonly used polymerization initiators, electrolytes, polymerization accelerators, chain transfer agents,
A chelating agent or the like may be used.The copolymer latex obtained by the present invention preferably has a Kel content t in the range of 10 to 60 weight when used for off-wheel printing.

Examples of mineral pigments used in the present invention include titanium dioxide, satin white, kaolin, aluminum hydroxide, and calcium carbonate.
may be used in combination of two or more.

Furthermore, the paper coating composition of the present invention contains commonly used binders such as starch, casein, and polyvinyl alcohol, as well as thickeners, crosslinking agents, water retention agents, alkaline stabilizers, antifoaming agents, and surfactants. There is no problem in using various additives such as additives as necessary.

〔Example〕

The present invention will be specifically explained below with reference to Examples.
The present invention is not limited to Example V7-Eri in any way. Incidentally, unless otherwise specified, all terms "chi" and "part" used in the examples mean percent by weight and parts by weight.

0 Example-1 In a pressure-resistant container of 1 (M?), the number of monomers shown in Table-1 VC,
Anionic surfactants and chain transfer agents, 0.8 parts of potassium persulfate, 0.4 parts of sodium bicarbonate, and 100 parts of pure water were charged, and emulsion polymerization was carried out at 65° C. with stirring. The polymerization conversion rate of the obtained copolymer latex is:
All of them had more than 97 attacks. Next, after adjusting the PR of the copolymer latex to 7 with an aqueous sodium hydroxide solution, unreacted monomers were removed by steam distillation to obtain copolymer latexes A-D.

Using the copolymer latexes A to D, paper coating compositions were prepared based on the following formulations, and coated papers 1 to 0 were obtained. The resulting processed papers 1 to 0 were tested for RI wet pick strength, RI dry pick strength, ink receptivity, and blister resistance. The results are shown in Table-2.

(Formulation) Kaolin V - 80 parts Calcium carbonate 20 parts Modified starch 8 parts Copolymer latex 12 parts (Solid content) (Measurement method) ・RI Wet-Pick strength When printed using dampening water on an RII printing machine Judging the degree of picking with the naked eye, it ranges from grade 7.1 (best) to grade 5.
Evaluation was made on a five-point scale (worst). The average value of 6 times is shown.

- RI Dry-Pick Strength: Evaluated using the same method as the RI Wet-Pick strength measurement method described above, except that dampening water was not used. When the ink was supplied and printed, the acceptability of the ink was judged visually.

- Blister resistance After adjusting the humidity of double-sided printed coated paper to about 6%, it was placed in a heated oil path, and the lowest temperature at which blisters occurred was shown.

0 ratio soft example-1 All tests were conducted in the same manner as in Example-1 except that sodium dodecylbenzenesulfonate or lauryl sulfate in the number of parts shown in Table-1 was used as an emulsifier.
A copolymer latex (a) was obtained. Next, the coated paper (2) was prepared and tested in the same manner as in Example-1. The results are shown in Table-2.

Margin table below-1 Rice 1 to Rice 3: Sodium polyoxyethylene octylphenol ether sulfate. However, the number of moles of ethylene oxide added is as follows: 1:3, 2:25, 3:60, 4 to 5: Sodium polyoxyethylene nonyl sulfate. However, the number of moles of ethylene oxide added is 4:4 and 5:60, and the method for measuring the gel content in the copolymer latex is as follows.

a) A film of copolymer latex is prepared by drying at room temperature, and the film is placed in benzene of about 200 to 800 times its strength, and is allowed to stand for 48 hours, after which time it is filtered using A 2 lp paper.

b) Dry solution F under reduced pressure at 70°C, weigh it, and calculate the benzene soluble content of the copolymer latex film (semi-considered %).
seek.

c) Subtract the above benzene soluble content (7%) from 1004=ft% to obtain a constant value, i.e. benzene insoluble content (7%)
is calculated as Kel content.

Table 2 0 Example 2 A test was conducted in the same manner as in Example 1 using the monomers, anionic surfactant and chain transfer agent in the parts shown in Table 3, and copolymer latex E -I got J. Next, coated papers [F] to ■ were prepared in the same manner as in Example-1,
The results of the test are shown in Table 4.

0 Comparative Example-2 A copolymer latex c = f was obtained by conducting a test in the same manner as in Example-1 using the monomers, anionic surfactant and chain transfer agent in the parts shown in Table-3. Ta. however,
Copolymer latex e lacked stability and agglomerated during emulsion polymerization, making it impossible to obtain latex samples.Next, coated papers ■ and ■ were prepared in the same manner as in Example-1.
I released the work and conducted a test.

The results are shown in Table 4.

1. Effects of the Invention [Effects of the Invention] As described above, by using the paper coating composition of the present invention, wet-bick strength, dry-bick strength, in-φ receptivity, and blister resistance can be improved. It is possible to obtain a coated paper with excellent printability such as a method.

Claims (1)

[Claims] 1. 19.5 to 39% by weight of aliphatic conjugated diene monomer;
The following general formula ( A copolymer latex obtained by emulsion polymerization of the monomer mixture in the presence of 0.1 to 5 parts by weight of an anionic surfactant represented by a) and/or (b), and a mineral pigment. A paper coating composition comprising: General formula: (a) ▲ Numerical formula, chemical formula, table, etc. ▼ Here, R is an alkyl group having 4 to 20 carbon atoms or a hydrocarbon group containing an aromatic ring, n is an integer of 2 to 70, and M is Na, K or NH_4. (b) R'-O-(CH_2CH_2O)-_n'SO
_3M' Here, R' is an alkyl group having 4 to 20 carbon atoms, n' is an integer of 2 to 70, and M' is Na, K or NH_4. 2. The paper coating composition according to claim 1, wherein the aliphatic conjugated diene monomer is 1,3-butadiene. 3. The paper coating composition according to claim 1 or 2, wherein the monoolefin monomer is an alkenyl aromatic monomer alone or a mixture with an unsaturated carboxylic acid alkyl ester monomer. 4. The paper coating composition according to claim 3, wherein the alkenyl aromatic monomer is styrene and the unsaturated carboxylic acid alkyl ester is methyl methacrylate. 5. Claims in which the monoolefin monomer is an alkenyl aromatic monomer, an unsaturated carboxylic acid alkyl ester monomer, a vinyl cyanide monomer, and an unsaturated monomer containing a hydroxyalkyl group The paper coating composition according to item 1 or 2.