JPS628443B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a copolymer latex with good adhesive properties. Specifically, in polymerizing the copolymer latex, 20 to 80% by weight of aliphatic conjugated diene monomer, 0.5 to 10% by weight of ethylenically unsaturated carboxylic acid monomer,
Alkenyl aromatic monomer 0-60% by weight, ethylenically unsaturated carboxylic acid alkyl ester monomer 0-60% by weight
30% by weight, 0 to 6% by weight of monomers containing hydroxyalkyl groups, and 0 vinyl cyanide monomers
In the method of producing a copolymer latex by polymerizing ~50% by weight, (a) the total amount of aliphatic conjugated diene monomer and ethylenically unsaturated carboxylic acid monomer and other monomers is Polymerize using a polymerization chain transfer agent (x) selected to be 45 to 99% by weight of the total, and when the polymerization conversion rate is 70% or more (b) Remaining monomer corresponding to 1 to 55% by weight (c) When polymerizing using a polymerization chain transfer agent (y), the weights (x) and (y) of the polymerization chain transfer agent used in (a) and (b) are used within the range expressed by the following formula: y≧ 1.2x＋0.01 0≦x≦0.1 0.01≦y≦0.3 (x is parts by weight per part by weight of monomer (a), and (y) is weight per part by weight of monomer (b) The present invention provides a method for producing a copolymer latex with excellent adhesive properties. In recent years, attempts have been made to reduce the amount of synthetic copolymer latex used as a binder in paper coating and carpet packing for the purpose of cost reduction. However, if the amount of synthetic copolymer latex used is reduced, the adhesive force will inevitably decrease, making it impossible to obtain the desired adhesive strength. The present inventors completed the present invention as a result of research aimed at improving the above-mentioned drawbacks. The monomer composition of the copolymer constituting the synthetic copolymer latex of the present invention is 20 to 80% by weight of aliphatic conjugated diene monomer and 0.5 to 10% by weight of ethylenically unsaturated carboxylic acid monomer. , 0 to 60% by weight of alkenyl aromatic monomers, 0 to 30% by weight of ethylenically unsaturated carboxylic acid alkyl ester monomers, 0 to 6% by weight of monomers containing hydroxyalkyl groups, and vinyl cyanide monomers. The monomer polymerized in the first stage accounts for 45-99% by weight of the total.
Therefore, it is necessary to use the entire amount of aliphatic conjugated diene monomer and the entire amount of unsaturated carboxylic acid as the monomers to be polymerized in the first stage. Further, other monomers are appropriately selected so as to fall within the range of amounts used in the first stage. These monomers are polymerized by commonly used emulsion polymerization methods, but the polymerization conversion rate is 70%.
Polymerization is carried out until the Polymerization conversion rate is 70%
In this state, the second stage monomer is added and polymerized. The amount of the polymer chain transfer agent, which is one of the characteristics of the present invention, must fall within the range expressed by the following formula. y ≧ 1.2 It represents the amount of chain transfer agent used in parts by weight per part by weight of the monomer in the first stage.)
The amount of polymerization chain transfer agent used in the first stage is 0 to 0.1
(parts by weight), and that of the second stage is 0.01 to 0.3 (parts by weight) per 1 part by weight of the second stage monomer.
It must be used within the range of y≧1.2x+0.01. To describe the present invention in more detail, the aliphatic conjugated diene monomers include 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-
1,3-butadiene, 2-neopentyl-1,3
-butadiene, 2-chloro-1,3-butadiene, 2-cyano-1,3-butadiene, substituted linear conjugated pentadienes, conjugated hexadiene with linear and side chains, etc. used. These monomers are used in amounts of 20 to 80% by weight, but if less than 20% by weight the adhesive strength is poor;
Exceeding this is not desirable as it becomes too soft. As an ethylenically unsaturated carboxylic acid monomer,
Examples include anhydrides or monoalkyl esters of acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, and dicarboxylic acids, which may be used singly or in combination of two or more. These monomers are 0.5
It is used in amounts up to 10% by weight, but if it is less than 0.5% by weight, the adhesive strength will be poor, and if it exceeds 10% by weight, the viscosity will become high and it will be difficult to handle. Ethylenically unsaturated carboxylic acid alkyl ester monomers include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate, glycidyl methacrylate,
Examples include dimethyl fumarate, diethyl fumarate, dimethyl maleate, diethyl maleate, dimethyl itaconate, monomethyl fumarate, and monoethyl fumarate, which may be used alone or in combination of two or more. These monomers are used in an amount of 0 to 30% by weight, but the adhesive strength does not increase even if the amount exceeds 30% by weight. Examples of the alkenyl aromatic monomer include styrene, alphamethylstyrene, methylalphamethylstyrene, divinylbenzene, and vinyltoluene, which may be used alone or in combination of two or more. These monomers are used in an amount of 0 to 60% by weight, but if the amount exceeds 60% by weight, the adhesive strength decreases. Examples of the unsaturated monomer containing a hydroxyalkyl group include β-hydroxyethyl acrylate,
β-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate,
Hydroxybutyl methacrylate, 3-chloro-
Examples include 2-hydroxybutyl methacrylate, di-(ethylene glycol) maleate, di-(ethylene glycol) itaconate, 2-hydroxyethyl maleate, bis(2-hydroxyethyl) maleate, and 2-hydroxyethylmethyl fumarate. Used alone or in combination of two or more. These monomers are used in an amount of 0 to 6% by weight in order to improve the stability of the latex, but even if it exceeds 6% by weight, the effect of improving the stability of the copolymer latex is small and it is economically undesirable. Examples of vinyl cyanide monomers include aliphatic unsaturated nitriles such as acrylonitrile, α-chloroacrylonitrile, methacrylonitrile, and α-ethyl acrylonitrile, which may be used singly or in combination of two or more. These monomers are used in an amount of 0 to 50 parts by weight, but if the amount exceeds 50 weight %, the adhesive strength decreases. 1st
The monomer that polymerizes in the step is used in an amount of 45 to 99% by weight of the total, but if it is outside this range, excellent adhesive strength cannot be obtained. As the polymerization chain transfer agent, octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, t-hexadecyl mercaptan, n
-tetradecylmercaptan, t-tetradecylmercaptan, n-hexadecylmercaptan,
Mercaptans such as mixed t-mercaptan, thiuram sulfides such as tetraethylthiuram sulfide and dipentamethylenethiuram hexasulfide, chlorides such as carbon tetrachloride and methylene chloride, and tetrabromide. Examples include carbon, bromides such as ethylene bromide, and hydrocarbons such as pentaphenylethane, as well as acrolein, methacrolein, allyl alcohol, 2-ethylhexylthioglycolate, and 1-thioglycerol.
These polymerization chain transfer agents may be used alone or in combination of two or more. These polymerization chain transfer agents are used in the range of 0 to 0.1 parts by weight (relative to 1 part by weight of the monomer in the first stage) in the first stage, and 0.01 to 0.3 parts by weight in the second stage (relative to 1 part by weight of the monomer in the second stage). (based on 1 part by weight of the monomer) and is used within the range expressed by the following formula. If more than 0.1 part by weight is used in the first stage, the adhesive strength will be poor, and in the second stage, if it is less than 0.01 part by weight or more than 0.3 part by weight, the adhesive strength will be decreased. Furthermore, in order to achieve the present invention, it is not sufficient that the amounts used in the first stage and the second stage are within respective ranges, and it is necessary to always satisfy the following formula. Outside this range, adhesive strength sufficient to satisfy the present invention cannot be obtained. y ≧ 1.2 It represents the amount of chain transfer agent used in parts by weight per 1 part by weight of polymer. Anionic emulsifiers are suitable, including higher alcohol sulfate ester salts, alkylaryl sulfonates, alkylnaphthalene sulfonates and their derivatives, alkyl sulfonates,
Examples include sulfonate salts of alkyl succinates, sulfate esters and phosphate ester salts of nonionic surfactants, and nonionic emulsifiers such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenol ether, fatty acid ester of polyethylene glycol, etc. Can also be used together. As a polymerization initiator, inorganic peroxides such as persulfates and hydrogen peroxide, organic peroxides such as cumene hydroperoxide, lauroyl peroxide, and diisobutylbenzoyl peroxide, or the above oxidation catalysts and hyposulfite are used. Examples include so-called redox type catalysts that are used in combination with reducing agents such as sodium and formaldehyde sulfonates. During the polymerization of the synthetic copolymer latex, the above-mentioned emulsifiers and polymerization initiators, as well as various electrolytes, polymerization accelerators, chelating agents, etc., may be used as necessary. Further, the type of reaction may be so-called high-temperature polymerization or low-temperature polymerization using a redox type polymerization initiator. Examples are shown below, but the present invention is not limited in any way. Note that all parts and % in the examples mean parts by weight and % by weight unless otherwise specified. Example 1 Each monomer and polymerization chain transfer agent used in the first stage shown in Tables 1 and 2, 1.2 parts by weight of sodium alkylbenzenesulfonate, and sodium hydrogen carbonate
A mixture of 0.5 parts by weight, 0.8 parts by weight of potassium persulfate, and 100 parts by weight of water was placed in an autoclave and polymerized at 70°C with stirring until the polymerization conversion reached the values listed in the first row of Tables 1 and 2. When the temperature was reached, a second stage monomer and a polymerization chain transfer agent were added to carry out polymerization. The polymerization conversion rate of the obtained copolymer latex was 99
% or more. After removing unreacted monomers from these latexes by stripping, they were passed through a 200-mesh wire gauze to obtain copolymer latexes.

【table】

[Table] Example 2 Using the copolymer latex obtained in Example 1, a coating liquid was prepared according to the following formulation. Composition of coating liquid Kaolin clay 70 parts (solid content) Calcium carbonate 30 parts (〃) Modified starch 6 parts (〃) Emulsion copolymer latex 10 parts (〃) (Total solid content 60%) Obtained coating liquid A high-quality base paper for coated paper was coated on one and both sides using a blade coater and dried. (Coating amount is 10g/m ² on one side)
Humidity was controlled day and night at a relative humidity of 65% and a temperature of 20°C, then a linear pressure of 80 kg/cm, a temperature of 60°C, and a speed of 5 m/cm.
The sample was subjected to supercalender treatment under the conditions of min and 2 nip. The performance of the obtained coated paper is shown in Tables 3 to 4. The performance of the coated paper was measured using the following test method. ΓRI Dry Picking: The degree of picking when printed with an RI printing machine was visually judged and evaluated on a five-point scale from grade 1 (best) to grade 5 (worst).
The average value of 6 times is shown. ΓRI wet pick: The degree of picking when printing with dampening water on an RI printing machine is judged visually and evaluated on a five-point scale from grade 1 (best) to grade 5 (worst). did. The average value of 6 times is shown.

【table】

[Table] Example 3 450 parts of ground calcium carbonate is added to a mixture consisting of 100 parts of latex (solid content), 1 part of anti-aging agent and 0.5 part of dispersant and uniformly dispersed. Next, add 0.1 part of an antifoaming agent to remove air bubbles, and then add a thickener and water to a viscosity of 13,500 to 14,500 centipoise (BM rotational viscometer, 12 rpm #4 rotor, 20
℃) and an adhesive composition with a solid content concentration of 80% was prepared. The obtained adhesive composition was applied to the back side of a tufted carpet gray fabric whose base fabric was polypropylene split yarn and whose pile was nylon, with an apparent weight of 1000 gr.
m ² was applied uniformly and a jute woven backing was applied thereon to obtain a wet carpet. This carpet was dried at 120°C for 20 minutes and the peel strength of the backing material was measured according to JIS L-1021-1974 "Rug Test Method". The results are shown in Table 5.

【table】

Claims (1)

[Scope of Claims] 1. 20 to 80% by weight of aliphatic conjugated diene monomer, 0.5 to 10% by weight of ethylenically unsaturated carboxylic acid monomer, 0 to 60% by weight of alkenyl aromatic monomer, ethylene-based monomer A copolymer latex is obtained by polymerizing 0 to 30% by weight of an unsaturated carboxylic acid alkyl ester monomer, 0 to 6% by weight of a monomer containing a hydroxyalkyl group, and 0 to 50% by weight of a vinyl cyanide monomer. (a) The total amount of aliphatic conjugated diene monomer and ethylenically unsaturated carboxylic acid monomer and other monomers are selected such that the total amount is 45 to 99% by weight of the total. Polymerize using a polymerization chain transfer agent (x), and when the polymerization conversion rate reaches 70% or more (b) Polymerize the remaining monomer equivalent to 1 to 55% by weight using a polymerization chain transfer agent (y) (c) Use the polymer chain transfer agent used in (a) and (b) in the range where x and y are expressed by the following formula: y≧1.2x+0.01 0≦x≦0.1 0.01≦y≦0.3 (x represents parts by weight per 1 part by weight of monomer (a), and y represents parts by weight per 1 part by weight of monomer (b).) A copolymer with excellent adhesive properties. Method of manufacturing latex.