KR840001832B1 - Process for producing copolymer latex - Google Patents

Abstract

Copolymer latex is prepd. by emulsion-polymerizing (A) a conjugated diolefin (20-60 wt.%), (B) an aromatic vinyl monomer (20-60 wt.%), (C) a vinyl cyanide (1-20 wt.%), (D) an unsatd. carboxylic acid alkyl ester (1-40 wt.%), (E) an ethylenically unsatd. carboxylic acid (1-10 wt.%), and (F) an unsatd. monomer contg. hydroxyalkyl gp. (1-5 wt.%), so that a portion of at least one of (A), (B) and (D), a portion or all of (C), and all of (E) and (F) (45-99 pts. wt.) are initially emulsion- polymerized. The residual monomers (55-1 pts. wt.) are then copolymerized with the initially formed copolymer. The latex gives copolymer-coated paper improved ink gloss, high adhesion, and resistance to water.

Description

Method for producing copolymer latex

TECHNICAL FIELD This invention relates to the manufacturing method of the copolymer latex which provides the coated paper improved ink gloss.

More specifically, 20-60 wt% of conjugated diene monomer, 20-60 wt% of aromatic vinyl monomer, 1-20 wt% of vinyl cyanide monomer, 3-40 wt% of α, β-ethylenically unsaturated carboxylic acid alkyl ester monomer In preparing a copolymer latex by emulsion polymerizing 1-10% by weight of an α, β-ethylenically unsaturated carboxylic acid monomer and 1-5% by weight of an α, β-ethylenically unsaturated carboxylic acid hydroxyalkyl ester monomer,

(a) the total amount of the α, β-ethylenically unsaturated carboxylic acid monomer and the α, β-ethylenically unsaturated carbon hydroxyalkyl ester monomer corresponding to 45-96 parts by weight of all monomers, part or all of the vinyl cyanide monomer, and Emulsion polymerization of a portion of one or two or more monomers selected from conjugated diene monomers, α, β-ethylenically unsaturated carboxylic acid alkyl ester monomers and aromatic vinyl monomers,

(b) The present invention relates to a method for producing a copolymer latex, characterized in that the remaining monomers corresponding to 1-55 parts by weight of the total monomers are emulsion polymerized. In recent years, with the rapid increase in printed matter, the printing speed has increased, and the printing technology has been rapidly developed even at high speed and high temperature of ink drying. Along with this, the performance required for coated paper is of course strict, and adhesive strength, water resistance, blister resistance, and heat set roughening resistance have been required to withstand high-speed printing. In order to meet such demands, a method of reducing the gel content of the copolymer has been proposed as a method for improving the adhesive strength and water resistance as a method for changing the components of the copolymer monomer or improving the blister resistance. However, even when the copolymerization and the gel content of the copolymer were changed, the main characteristics were improved, such as improving the adhesive strength, the water resistance, or the blister resistance, so that all the characteristic requirements could not be satisfied. On the other hand, a method of introducing acrylonitrile to a copolymer monomer has been proposed for the purpose of improving the ink gloss on the printing surface. However, the conventional manufacturing method could not sufficiently satisfy the needs of current printing. The present inventors have made the present invention as a result of research for the purpose of obtaining a copolymer latex for coating paper having excellent ink gloss on the printing surface, adhesive strength of coated paper, water resistance, blister resistance, and heat set roughening resistance. 20-60 wt% of conjugated diene monomer, 20-60 wt% of aromatic vinyl monomer, 1-20 wt% of vinyl cyanide monomer, 3-40 wt% of α, β-ethylenically unsaturated carboxylic acid alkyl ester monomer, α, β- In preparing a copolymer latex by emulsion polymerization of 1-10% by weight of an ethylenically unsaturated carboxylic acid monomer and 1-5% by weight of an α, β-ethylenically unsaturated carboxylic acid hydroxy alkyl ester monomer,

(a) the total amount of the α, β-ethylenically unsaturated carboxylic acid monomer and the α, β-ethylenically unsaturated carboxylic acid hydroxy alkyl ester monomer corresponding to 45-99 parts by weight of all monomers, part or all of the vinyl cyanide monomer, and Emulsion emulsion polymerization of one or two or more monomers selected from conjugated diene monomers α, β-ethylenically unsaturated carboxylic acid alkyl ester monomers and aromatic vinyl monomers,

(b) then providing a method for producing a copolymer latex by emulsion polymerization of the remaining monomers corresponding to 1 to 55 parts by weight of the shearing material, thereby providing adhesion strength, water resistance, and blister resistance of the ink gloss coated paper on the printing surface. The copolymer latex for coating paper which is excellent in heat-set roughening resistance is obtained.

The conjugated diene monomers in the monomer mixture used in the preparation of the synthetic copolymer latex of the present invention include 1,3-butadiene, 2-methyl-1,3-butadiene 2-chloro-1,3-butadiene and the like. Usually these monomers are used in the range of 20-60% by weight in order to impart moderate elasticity to the copolymer, but at 20% by weight or less, sufficient elasticity cannot be obtained, resulting in poor adhesive strength. Moreover, in 60 weight% or more, it becomes soft and its water resistance is inferior. Examples of the aromatic vinyl monomers include styrene, α-methylstyrene vinyltoluene, and α, β-dimethylstyrene. Although these monomers use 20-60 weight%, when less than 20 weight%, the adhesive force and water resistance of a coated paper fall, and when it exceeds 60 weight%, the film formability of a copolymer falls, As a result, the adhesive force of a coated paper falls. Examples of vinyl cyanide monomers include aliphatic unsaturated nitriles such as acrylonitrile, α-chloroacrylonitrile, methacrylonitrile, and α-ethylacrylonitrile. These nitriles range from 1 to 20% by weight to provide good ink gloss by using some or all of them in the first step. Even if it increases to 20 weight% or more, the ink gloss does not improve further, but rather the adhesive force of a coated paper falls. In addition, even if the whole amount of these monomers are used in the second step, a sufficient effect on the ink gloss cannot be obtained.

As the α, β-ethylenically unsaturated carboxylic acid alkyl ester monomer, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate, glycidyl methacrylate Acrylate, dimethyl fumarate, diethyl fumarate, dimethyl maleate, diethyl maleate, dimethyl itaconate, monomethyl fumarate and monoethyl fumarate. 3-40% by weight of these monomers is used, but less than 3% by weight of the coated paper is poor light resistance.

Moreover, when it exceeds 40 weight%, the water resistance of a coated paper will become bad.

Examples of the α, β-ethylenically unsaturated carboxylic acid monomers include acrylic acid, methacrylic acid, maleic acid, fumaric acid and itaconic acid.

These monomers are used in the range of 1 to 10% by weight, but less than 1% by weight, the adhesion of the coated paper is insufficient, and when it exceeds 10% by weight, the viscosity of the copolymer Latox is increased. In addition, since the water resistance greatly deteriorates when used in the second step, all of these monomers are polymerized in the first step. Examples of the α, β-ethylenically unsaturated carboxylic acid hydroxy alkyl ester monomers include β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate and hydroxybutyl acryl. Latex, hydroxybutyl methacrylate, 3-chloro-2-hydroxybutyl methacrylate, di- (ethyleneglycol) maleate, di- (ethyleneglycol) itaconate, 2-hydroxyethylmaleate, bis (2-hydroxyethyl) maleate, 2-hydroxyethyl methyl fumarate, and the like. These monomers are used in the first step in 1-5% by weight, but less than 1% by weight, the stability of the copolymer latex and the water resistance of the coated paper is reduced.

Moreover, when it exceeds 5 weight%, the water resistance of a coated paper will fall. In addition, when used in the second step, the water resistance of the coated paper is reduced. In the first step of the method of the present invention, the total amount of each of the α, β-ethylenically unsaturated carboxylic acid monomer and the α, β-ethylenically unsaturated carboxylic acid hydroxy alkyl ester monomer, a part of the vinyl cyanide monomer or conjugated diene monomer, α, β It consists of a part of 1 type, or 2 or more types of monomers chosen from the ethylenically unsaturated carboxylic acid alkylester monomer and the aromatic vinyl monomer, and polymerizes the monomer mixture corresponded to 45-99 weight part of all monomers. If it is less than 45 weight part, water resistance and adhesiveness are inferior, and when it exceeds 99 weight part, blister resistance and hit set roughening resistance are inferior.

It is preferably used at 70-95 parts by weight. In addition, the conversion of the monomer polymerized in the first step is preferably 70% or more, and less than 70% is inferior in water resistance adhesiveness as compared with 70% or more. Of the monomers used in the first stage polymerization, the α, β-ethylenically unsaturated carboxylic acid and the α, β-ethylenically unsaturated carboxylic acid hydroxy alkyl ester monomer must be used in the first step in the whole amount. When these monomers are used in the second step, the water resistance and the adhesion decrease. In addition, it is necessary to use part or all of the vinyl cyanide monomer in the first step, and the ink gloss does not improve when only the second step is used. When the first stage reaction is completely completed at the start of the second stage emulsion co-polymerization, that is, when the polymerizable radical has completely disappeared, it is necessary to start a new reaction by adding a reaction initiator or the like. There is no restriction | limiting in particular about the addition method of various components in a 1st step emulsion copolymerization, Any of the batch addition method, the division addition method, and the continuous addition method may be sufficient. As for the method of adding the monomer in the second step emulsion copolymerization, any of the batch addition method, the split addition method, and the continuous addition method can be used without any limitation as in the case of the first step. In addition, a well-known emulsifier, a polymerization initiator, a chain transfer agent, etc. are used at the time of superposition | polymerization. As the emulsifier, anionic surfactants such as sulfuric acid esters of higher alcohols, alkylbenzene sulfonates, aliphatic sulfonates, or nonionic surfactants such as alkyl esters of alkyl glycols, alkylphenyl ethers, and alkyl ethers are used. It is used over. In consideration of the water resistance of the obtained copolymer latex, it is preferable to use 2 parts by weight or less based on the total amount of monomers. As the initiator, water-soluble initiators such as potassium persulfate, ammonium persulfate, sodium persulfate, or oil-soluble initiators such as redox initiators or benzoyl peroxide can be used. As the chain transfer agent, mercaptans, halogen hydrocarbons and the like can be used.

As is apparent from the foregoing description, the present invention is excellent in the manufacture of coated paper having excellent physical properties, in particular, adhesive strength, water resistance, blister resistance, and heat set roughening resistance, and good ink gloss on a printing surface. To provide suitable copolymer latex. In the prior art, it was not very difficult to improve certain properties among the various physical properties described above, but in this case, deterioration of other physical properties was inevitable. In other words, it was impossible to produce coated paper having all the above-described physical properties. However, the copolymer latex according to the present invention has made it possible to provide coated paper having all the above-described physical properties. In the following, the present invention will be described in more detail with reference to examples, which are not intended to limit the present invention in any form.

Example 1

Each monomer used in the first step shown in Table 1 to Table 4 and 1.2 parts by weight of sodium alkylbenzenesulfonate, 0.8 parts by weight of sodium bicarbonate, 0.8 parts by weight of ammonium persulfate, 0.5 parts by weight of tertiary dodecyl mercaptan, The mixture of 100 parts by weight of water was put in a 101 autoclave and polymerized at 65 DEG C while stirring, and further adding each monomer shown in Table 1 to Table 4 in the second step to complete the polymerization. The polymerization conversion ratio at the time of adding the monomer of the second step was shown in Table 1-Table 4. As for the polymerization conversion rate of the obtained latex, all were 99% or more. After removal of these latex unreacted monomers by stripping, copolymer latex A-O was obtained through a 200 mesh gold mesh. However, comparative example T (this example is an example of what was industrially performed conventionally) superposed | polymerized by the following method. A mixture of the monomers shown in Table 3, 1.3 parts by weight of sodium alkylbenzenesulfonate, 0.8 parts by weight of sodium bicarbonate, 0.8 parts by weight of potassium persulfate, and 100 parts by weight of water was added to a 101 autoclave and stirred at 65 ° C. for 13 hours. Immediately after the addition of reaction stopper.

TABLE 1

TABLE 2

TABLE 3

TABLE 4

Example 2

Using the copolymer latex obtained in Example 1, a coating agent was prepared according to the following formulation.

Composition of coating solution

Kaolin clay 70 parts (solid)

30 parts of calcium carbonate (")

Denatured starch, part 8 (")

Emulsified copolymer latex 12 parts (") (62% total solids)

Using the coating solution obtained, coat the coarse paper for one side and both sides with a plate coater, and dry it (coating amount: 10 g / m2 on one side) Adjustment was carried out under the condition of 65 ° C and a temperature of 20 ° C, followed by a super calender treatment under the condition of a linear pressure of 80 kg / cm, a temperature of 60 ° C, and a speed of 5 m / min. 2 nip to obtain a sample. The performance of the coated paper obtained is shown in Tables 5 to 8. In addition, the performance measurement of the coated paper was performed by the following test method.

RI dry peak (adhesive strength test)

The picking degree at the time of printing by RI printing machine was visually judged, and it evaluated by the 5-step method of 1st grade (the best thing) to 5th grade (the worst thing). Six average values were displayed.

RI wet peak (water resistance test)

The picking degree when printed using the dampened product by RI printing machine was visually judged and evaluated by the 5-step method of 1st grade (best) to 5th grade (best). Six average values were displayed.

Blister Resistance:

Humidification (approximately 6%) of double-sided printing coated paper is added to a heated oil bath, and the lowest temperature at the time of blister generation is displayed. A blister is a swelling phenomenon that occurs on both sides of high-quality paper (chemical pulp 100%) and heavy paper (mechanical pulp mixture).

Ink gloss

Using an RI printing press, 0.4cc of commercially available offset printing ink is used for one-time printing and left at room temperature overnight. Test paper left for 1 day and night is measured with a glossmeter.

TABLE 5

TABLE 6

TABLE 7

TABLE 8

As can be clearly seen from the examples in Table 5 and Table 8, the physical properties of the examples are equal to or slightly smaller than those of the comparative examples, and are smaller or smaller (preferably smaller values). The blister resistance shows the same or large value (the larger the value is good), and the ink gloss is the same or the larger value (the larger the value is the better).

The only exception is that Comparative Example Q shows a good value in the blister resistance, but the RI dry peak value is too bad and is not practically suitable.

Example 3

Using the copolymer latex obtained by Example 1, the coating liquid was produced according to the combination shown next.

70 parts of composition kaolin clay (solid content) of coating liquid

30 parts of heavy calcium carbonate (solid content)

0.2 part dispersant (solid content)

Denatured starch, 7 parts (solid)

12 parts of copolymer latex (solid content)

The coating solution was adjusted so that the solid content was 60%, and the coating solution was coated on the one side and both sides using a # 17 wire rod on a heavy paper (15% mechanical pulp mixing ratio). After drying, it was treated by hanging on a super calendar. Table 9 shows the results of various physical properties of the obtained coated paper.

TABLE 9

ㆍ Heat resistance roughening

A double-sided coated specimen was printed on both sides using an RI printing tester, and the specimen was placed in 140 ° C. for 5 seconds. Then, the appearance of heatset roughening was visually measured. It was evaluated by the 5-step method. Table 9 shows the average of six times.

Hit set lapping refers to the phenomenon of paper fiber protrusion on heavy paper. As can be clearly seen when comparing the Example and the Comparative Example in Table 9, when comparing the physical properties of the Example and the physical properties of the Comparative Example, RI wet peak and RI dry peak is equivalent or somewhat smaller (smaller value) Is good), and shows a better value of the heat set roughening resistance and the blister resistance (the small value of the heat set roughening resistance is good and the large value of the blister resistance is good), and also in the ink gloss. Equivalent or large values are shown (the larger the value is the better).

Claims (1)

20-60% conjugated diene monomer, 20-60% by weight aromatic vinyl monomer, 1-20% by weight vinyl cyanide monomer, 3-40% by weight of α, β-ethylenically unsaturated carboxylic acid alkyl ester monomer, α, β- 45-99 parts by weight of shear monomer in emulsion copolymerization of 1-10% by weight of an ethylenically unsaturated carboxylic acid monomer and 1-5% by weight of an α, β-ethylenically unsaturated carboxylic acid hydroxy alkyl ester monomer Α, β-ethylenically unsaturated carboxylic acid monomer corresponding to the α, β-ethylenically unsaturated carboxylic acid hydroxy alkyl ester monomer and the whole amount, part or all of the vinyl cyanide monomer and conjugated diene monomer, α, β-ethylene type A part of one or two or more monomers selected from unsaturated carboxylic acid alkyl ester monomers and aromatic vinyl monomers is emulsion-polymerized, and then the remainder corresponding to 1-55 parts by weight of the shearing monomer at the time when the conversion of the monomer proceeds to 70% or more. A painting process for producing a copolymer latex which comprises polymerizing dimer.