JPS61271339A - Copolymer latex - Google Patents

Abstract

PURPOSE:To improve water resistance and adhesion, by forming the titled latex from a copolymer composed of a conjugated diene monomer, an arom. vinyl monomer and an ethylenically unsaturated monomer copolymerizable therewith and a surfactant. CONSTITUTION:0.5-10pts.wt. surfactant (A) is incorporated in 100pts.wt. copolymer. Said copolymer is composed of 40-90wt% conjugated diene monomer, 10-60wt% arom. vinyl monomer and 0-50wt% ethylenically unsaturated monomer copolymerizable therewith, wherein a toluene-soluble has an intrinsic viscosity [eta] of 1.0-3.5dl/g. Component A is at least one surfactant selected from among sulfated fatty acid, esters, sulfated fatty acids and/or their alkali metal salts. Examples of the conjugated diene monomers are butadiene and isoprene. Examples of the arom. vinyl monomers are styrene and alpha-methylstyrene.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a rubber latex for adhesives having excellent water resistance and adhesive properties.

Background Art Rubber latex adhesives have rubber elasticity, flexibility, and low-temperature properties not found in other resin emulsion adhesives, and are used for various adhesive applications. However, it has the drawback of lacking water resistance, which is common to water-based adhesives, and is currently used for limited purposes as an adhesive. This is not due to a defect in the polymer itself obtained by emulsion polymerization, but rather due to the various stabilizers used to make it exist stably as a rubber latex.
In other words, emulsifiers and dispersants used during polymerization.

Electrolytes and the like remain in the adhesive even after drying and reduce the water resistance of the adhesive. For this reason, attempts have been made to reduce the amount of emulsifier, dispersant, electrolyte, etc. as a method for improving water resistance, but no results have yet been obtained that lead to an improvement in water resistance.

Problems to be Solved by the Invention An object of the present invention is to provide a rubber latex adhesive that has both water resistance and adhesive properties.

A further object of the present invention is to provide a copolymer latex with low gel content, high molecular weight, and good water resistance.

Means for Solving the Problems In order to achieve the above object, the present inventors have conducted repeated research on the composition of latex, its proportion, and the emulsifier for polymerization in order to obtain the desired physical properties as an adhesive, and have developed the present invention. completed.

That is, in the present invention, (a) [1] The amount of conjugated diene monomer bonded is 40 to 90% by weight.

■ The amount of aromatic vinyl monomers bound is 10 to 60% by weight, [3] The amount of ethylenically unsaturated monomers that can be copolymerized with these is 0 to 50% by weight, ■ The intrinsic viscosity of the toluene soluble portion ([η]) is 1.0 to 3.
For 100 parts by weight of copolymer which is 5 dl/g.

(b) A copolymer latex characterized by containing 0.5 to 10 parts by weight of at least one surfactant selected from sulfated fatty acid esters, sulfated fatty acids, and/or alkali metal salts thereof. .

Components of the present invention will be described in detail below.

(Conjugated diene monomer) Examples of the conjugated diene monomer that can be used in the present invention include butadiene, isoprene, and the like. When forming an adhesive or pressure-sensitive adhesive by using a conjugated diene monomer, natural rubber, or a tackifier in combination, butadiene is advantageous in terms of compatibility with them.

The amount of the conjugated diene monomer is preferably 40 to 90% by weight as an adhesive, more preferably 45 to 80% by weight. If the content of the conjugated diene monomer is less than 40% by weight, the adhesive force will be significantly reduced, and if it exceeds 90% by weight, the cohesive force as an adhesive will be significantly reduced.

(Aromatic Vinyl Monomer) Examples of the aromatic vinyl monomer that can be used in the present invention include styrene, α-methylstyrene, p-methylstyrene, and halogenated styrene.

The bonding amount of the aromatic vinyl monomer is preferably 10 to 60% by weight as an adhesive, and more preferably 15 to 50% by weight. If the aromatic vinyl monomer content is less than 10% by weight, the cohesive force will be significantly reduced, and if it exceeds 60% by weight, the adhesive force will be insufficient.

(Ethylenically unsaturated monomer) In the present invention, one or more monomers that can be copolymerized with the above conjugated diene monomer and aromatic vinyl monomer may be used in combination. It is possible. When such monomers are used in combination, their combined amount must be 50% by weight or less.

Examples of such monomers include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, and fumaric acid.

Examples of monoesters of ethylenically unsaturated dicarboxylic acids include monomethyl itaconate and monoethyl maleate.

All of these contribute to improving the stability, adhesive strength, and cohesive strength of latex.

In addition, as ethylenically unsaturated carboxylic acid alkyl esters, there are methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, etc. The difference in transition point contributes to improving adhesive strength and cohesive strength.

Furthermore, copolymerizable monomers that are effective in increasing adhesive strength and cohesive strength include (meth)acrylamide, glycidyl (meth)acrylamide, N-methylol (meth)acrylamide, and 2-hydroxyethyl (meth)acrylate. , divinylbenzene, diallyl phthalate, allyl (meth)acrylate, acryloni)+lyl, and vinyl acetate.

In this specification, "(meth)acrylate" means both acrylate and methacrylate, and "(meth)acrylic j" means both "acrylic" and "methacrylic".

(Emulsifier) In the present invention, the selection of an emulsifier for emulsion polymerization is important.1 In the emulsion copolymerization of a normal conjugated diene monomer-aromatic vinyl monomer, as an anionic surfactant, Disproportionated rosin acids, fatty acids, dodecylbenzenesulfonic acid, sulfuric esters of higher alcohols such as theuryl alcohol, sodium salts, potassium salts, ammonium salts, etc. are used, and polyoxyethylene is used as a nonionic surfactant. Nonylphenyl ether, polyoxyethylene dodecyl ether, etc. are used.

When adhesives are manufactured using latexes manufactured using the above-mentioned emulsifiers, they are inferior in water resistance and moisture resistance, which is a practical obstacle.

As a result of research on copolymer latex for use in adhesives with excellent water and moisture resistance, the inventors discovered that sulfated fatty acid ester (a), sulfated fatty acid (b) and/or their emulsifiers were used as emulsifiers. The present invention was completed based on the discovery that the object can be achieved by using at least one surfactant selected from alkali metal salts.

Sulfated fatty acid ester (a) usually has 8 carbon atoms.
~24 unsaturated fatty acids and 1 to 8 carbon atoms. Preferably, it is a sulfated unsaturated fatty acid ester consisting of 1 to 6 lower alcohols, such as sulfated butyl oleate [CH3-(CH2)7CH(0303Na)CH
2-(CH) C00C4H9), sulfated lysine butyl oleate, and alkali metal salts such as sodium and potassium are usually used.

Sulfated fatty acids (b) are usually oxidized unsaturated fatty acids having J to 24 carbon atoms, and are usually
Alkali metal salts such as sodium and potassium are used.

The unsaturated fatty acids used as raw materials for the above (a) and (b) include:
Examples include oleic acid (018), lysyllic acid (C), linoleic acid (C18, containing two C=C double bonds), lylunic acid (C8, containing three C=C double bonds), etc. 1. The emulsifier used in the present invention is particularly preferably a sulfated fatty acid ester (salt).

The amount of the emulsifier of the present invention to be used is 0.5 to 10 parts by weight, preferably 1 to 7 parts by weight, based on 100 parts by weight of the copolymer. If the emulsifier of the present invention is used within the above range, It is possible to produce a latex for adhesives that has good water resistance and good polymerization stability.

If the amount of the emulsifier of the present invention used is less than 0.5 parts by weight, stability during emulsion polymerization will not be sufficient, and if it exceeds 10 parts by weight,
When the resulting latex is used as an adhesive, water resistance and moisture resistance are reduced, which is undesirable.

(Intrinsic viscosity) The intrinsic viscosity of the copolymer in the present invention is also important. Here, the limiting viscosity refers to the toluene collected as oral fluid during the above Ge/6i measurement. refers to the intrinsic viscosity of a copolymer in liquid
It is measured using the 5-point dilution method at a temperature of 31 degrees Celsius. .

In the present invention, the intrinsic viscosity of the copolymer is 1.

O~3.5ddan/g. 1. Below Od/g,
The copolymer has insufficient cohesive force as an adhesive, and if it exceeds 3.5 dl/g, the adhesive force is insufficient, and in any case it cannot be used as an adhesive.The intrinsic viscosity of the copolymer can be adjusted using a molecular weight regulator, but 1 This is also possible by changing the polymerization conversion rate.

(Gel Content) The gel content of the copolymer usable in the present invention is preferably 30% by weight or less. If it exceeds this range, the adhesive force as an adhesive will be insufficient.

The gel content of the copolymer is controlled by using a molecular weight regulator and a crosslinking polyfunctional monomer, but the gel content can also be increased by increasing the polymerization conversion rate.

The gel content in this specification is determined by the second method.

The copolymer latex adjusted to pH 8 is coagulated with indulobil alcohol, washed twice with methanol, and vacuum dried at room temperature. Precisely weigh 0.5 g of the solidified material (its weight is A), add it to 100 ml of toluene, and add 3.
Leave at 0'O for 24 hours. This is subjected to reduced pressure using a No. 3 glass filter, and the separated solid content is vacuum dried at room temperature and weighed accurately (the weight is designated as B). The gel content is determined by the following formula.

Gel content = -x i o o (wt%) (Polymerization method) The copolymer latex of the present invention can be produced by a normal emulsion polymerization method. That is, in a polymerization reactor, certain monomers, water,
An emulsifier, a molecular weight regulator, a polymerization initiator, etc. are charged, and polymerization is carried out under stirring, usually at 5 to 90°C for 1 to 60 hours. When a predetermined polymerization conversion rate is reached, a polymerization terminator is injected and the reaction is started. to stop. If unreacted monomers remain, they are removed by reduced pressure or steam stripping.

Here, as the emulsifier, sulfated fatty acid ester, IL
E At least one surfactant selected from oxidized fatty acids and/or alkali metal salts thereof is used in an amount of 0.5 to 10 parts by weight per 100 parts of monomers. The monomers may be charged in their entirety from the beginning, divided into portions, or continuously.

The pH of the obtained latex can be adjusted as necessary, it can be concentrated, and an anti-aging agent can be added thereto.

As the one-coin initiator that can be used in the present invention, there are used polymerization catalysts made by combining persulfates or reducing agents such as sulfites or bisulfites, redox catalysts using organic hydrocarbons, etc. be done. in this case,
It is desirable that the amount of water-soluble electrolyte be as small as possible in order to maintain water resistance.

As the molecular weight regulator, known chain transfer agents such as mercaptans and carbon tetrachloride can be used.

As the polymerization terminator, sodium N,N-dimethylcarbamate, diethylhydroxylamine, etc. can be used.

Fillers such as calcium carbonate, titanium oxide, and clay can also be used to modify the adhesive.

Furthermore, it is also possible to add or use in combination various crosslinking agents, dispersants, tackifiers, and plasticizers.

Applications The copolymer latex obtained in the present invention has excellent adhesion and water resistance, and can be applied to all uses of latex that require such performance. For example, adhesive compositions for carpet backing, paper, etc. Coating composition 1 Adhesive composition for plywood, paint composition, sealant composition, fiber treatment agent, general-purpose adhesive composition, coating agent 1 can Sealing composition, adhesive composition, cement admixture Examples include latex compositions.

EXAMPLES Below, Examples and Comparative Examples are given to provide a detailed explanation of the present invention. Naturally, the present invention is not limited only to the following examples. In the examples and comparative examples, unless otherwise specified, "%" means % by weight, "
"Parts" means parts by weight.

[Example 1] Amounts of butadiene and styrene such that the copolymer composition at a monomer polymerization conversion rate of 80% is 55 parts of butadiene and 45 parts of styrene, and 5 parts of sulfated butyl oleate sodium salt.
1 part, 0.3 parts of t-dodecylmercaptan, and 200 parts of water were placed in an autoclave, and after purging with nitrogen, the temperature was raised to 65°C.Next, a 5% aqueous solution of 0.5 parts of potassium persulfate was added to start polymerization. The monomer conversion rate reached 80% in about 15 hours.
%, a 5% aqueous solution of 0.5 parts of sodium N,N-dimethyldithiocarbamate was added to stop the polymerization, and a highly stable latex was obtained.

The latex was brought to pH 8 with ammonia, and steam stripped and concentrated under reduced pressure.

A latex with a solid content concentration of 4896 and a viscosity of 120 cps was obtained. When the gel content and intrinsic viscosity of this copolymer were measured using the method described above, they were 5% and 2.0%, respectively. Od sentence/g
Met. The solid content of the latex thus obtained is 10
Sodium tripolyphosphate A 0 , 5 parts per 0 parts,
1.0 part of anti-aging agent.

Silicone antifoaming agent 0.05 parts 5 heavy calcium carbonate 45
0 parts was added thereto, and sodium polyacrylate was added thereto to give a viscosity of 30°000 cps to prepare a carpet lengthening agent. Table 1 shows the polymer physical properties and evaluation results.

[Example 2] Butadiene, styrene, and acrylic acid were charged into an autoclave in proportions such that the copolymer composition was 80 parts of butadiene, 18 parts of styrene, and 2 parts of acrylic acid, and in addition, 3 parts of Wt oxidized butyl sodium salt of oleate were charged. part and t-
All the operations were the same as in Example 1, except that 0.1 part of dodecyl mercaptan was charged into the autoclave, and a latex with a solid content concentration of 48% and a viscosity of 250 cps was obtained.

Polymer physical properties and evaluation results are shown in Table 1.

[Example 3] Imbrene, styrene, and acrylic acid were charged into an autoclave in such proportions that the copolymer composition at a monomer polymerization conversion rate of 70% was 85 parts of isoprene, 14 parts of styrene, and 1 part of acrylic acid, and in addition, All operations were carried out in the same manner as in Example 1, except that 1 part of sulfated butyl sodium oleate was also charged into the autoclave, and the solid content concentration was 48% and the viscosity was 180 cp! Latex of i was obtained.

Table 1 shows the physical properties and evaluation results of the obtained copolymer latex.

[Example 4] All procedures were carried out except that butadiene, styrene, and acrylamide were charged into an autoclave in proportions such that the copolymer composition at a monomer polymerization conversion rate of 60% was 65 parts of butadiene, 34 parts of styrene, and 1 part of acrylamide. Example 1
Perform the same operation as above to obtain a solid concentration of 48% and a viscosity of 20%.
A latex of 0 CPS was obtained. Table 1 shows the physical properties and evaluation results of the obtained copolymer latex.

[Examples 5.6.7 and 8] Instead of the sulfated butyl oleate sodium salt of Example 1, the emulsifiers of the invention shown in Examples 5.6.7 and 8 of Table 2 were used, The rest was carried out in the same manner as in Example 1 to obtain each copolymer latex of Examples 5, 6.7 and 8.

The physical properties and evaluation results of the obtained copolymer latex were
Shown in the table.

Table 2 (Part 1) Table 2 (Part 2) [Comparative Example 1] Butadiene and styrene were added in such proportions that the copolymer composition at a polymerization conversion rate of 80% was 35 parts of butadiene and 65 parts of styrene. All operations were performed in the same manner as in Example 1 except for charging the autoclave, and the solid content concentration was 4.
A latex of 8% and viscosity of 140 cps was obtained. Table 3 shows the physical properties and evaluation results of the obtained copolymer.

[Comparative Example 2] All operations were performed in the same manner as in Comparative Example 1, except that butadiene was changed to 95 parts and styrene was changed to 5 parts, and the solid content concentration was 48%.
, a latex with a viscosity of 170 cps was obtained. Table 3 shows the physical properties and evaluation results of the obtained copolymer latex.

[Comparative Example 3] The same operations as in Example 1 were performed except that 5 parts of sodium dodecylbenzenesulfonate was used as the emulsifier for emulsion polymerization, to obtain a latex with a solid content concentration of 48% and a viscosity of 200 cp's. Table 3 shows the physical properties and evaluation results of this copolymer latex.

[Comparative Example 4] The same operations as in Example 1 were performed except that the amount of sulfated butyl sodium oleate was changed to 11 parts to obtain a latex having a solid content concentration of 48% and a viscosity of 350 cps. Table 3 shows the physical properties and evaluation results of this copolymer latex.

Table 3 (Part 2) Table 4 (Part 2) Effects of the Invention According to the present invention, a copolymer latex with low gel content, high molecular weight, and good water resistance can be produced. Furthermore, according to the present invention, a rubber latex adhesive having both water resistance and adhesive properties can be obtained.

Claims (2)

[Claims] (1) (a) [1] Conjugated diene monomer bond amount is 40~
90% by weight, [2] the amount of aromatic vinyl monomers bound is 10 to 60% by weight, [3] the amount of ethylenically unsaturated monomers that can be copolymerized with these is 0 to 50% by weight, [4] ] For 100 parts by weight of a copolymer whose toluene-soluble portion has an intrinsic viscosity ([η]) of 1.0 to 3.5 dl/g, (b) sulfated fatty acid ester, sulfated fatty acid and/or its A copolymer latex containing 0.5 to 10 parts by weight of at least one surfactant selected from alkali metal salts. (2) The copolymer latex according to claim 1, which has a gel content of 30% by weight or less.