JPH0195107A - Manufacture of synthetic resin emulsion - Google Patents

Abstract

PURPOSE:To produce the title emulsion which does not contain an emulsifying agent and is good in stability, by adding a vinyl acetate/acrylamide copolymer to a specific monomer (s), and then polymerizing them. CONSTITUTION:1-20wt.% vinyl acetate/acrylamide copolymer having a vinyl acetate content of 1-70wt.% and a number-average molecular weight of 500-100,000 is added to one or more monomers selected from the group consisting of olefins (e.g., ethylene), vinyl esters (e.g., vinyl acetate), vinyl halides (e.g., vinyl chloride), and esters of alpha, beta-unsaturated carboxylic acids (e.g., methyl acrylate), and they are polymerized in the presence of a polymerization initiator (e.g., benzoyl peroxide) in an amount of 0.1-2wt.% based on the monomers in an aqueous medium having a pH of 3-7 at 30-100 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for producing a synthetic resin emulsion containing no emulsifier and having good stability.

<Prior Art> Conventionally, synthetic resin emulsions have been prepared using anionic, nonionic, cationic or amphoteric surfactants as emulsifiers, or
It has usually been manufactured by emulsion polymerization using protective colloids such as polyvinyl alcohol, cellulose ether, and polyvinylpyrrolidone, but various surfactants are used to improve the strength, water resistance, weather resistance, and This had the disadvantage of reducing adhesive properties.

<Problems to be Solved by the Invention> In view of the current situation, the present invention aims to produce a stable synthetic resin emulsion that does not contain an emulsifier, as a method for improving the coating performance of synthetic resin emulsions, which have been considered to be disadvantageous in the past. The purpose is to If a stable synthetic resin emulsion containing no emulsifier is prepared, it can be expected that the strength, water resistance, weather resistance, and adhesion of the coating film obtained by drying will be improved.

Means for Solving the Problems> The present invention is directed to a synthesis method using as a main component one or more selected from the group of olefins, vinyl esters, vinyl halides, and α,β-unsaturated carboxylic acid esters. The present invention relates to a method for producing a synthetic resin emulsion, which comprises adding and polymerizing a vinyl acetate/acrylamide copolymer in the production of the resin emulsion.

The vinyl acetate/acrylamide copolymer used in the present invention has a ratio of vinyl acetate to acrylamide of 1 to 70.
% by weight, preferably 10-40% by weight. 1% by weight
If the amount is less than 70% by weight or more than 70% by weight, the emulsion obtained using the vinyl acetate/acrylamide copolymer will be unstable, and the emulsion may coagulate during polymerization, or the resulting emulsion may contain many coarse particles, resulting in poor mechanical stability. It tends to be inferior and is not desirable.

Examples of polymerization initiators used in this polymerization include water-soluble oxidizing agents such as hydrogen peroxide, potassium persulfate, and ammonium persulfate, and azobisisobutyronitrile and 2,2°-azobis(2-amidinopropane) hydrochloride. There are redox catalysts consisting of azobis compounds or combinations of the above water-soluble oxidizing agents and water-soluble reducing agents such as sodium bisulfite, sodium pyrosulfite, sodium formaldehyde sulfoxylate, triethanolamine, and dimethylaminopropionitrile. is also available. In addition, the number average molecular weight of the copolymer can be adjusted to 500 to 100,000 using a molecular weight regulator such as sodium hypophosphite.
, preferably 800 to 50,000.

The polymerization temperature is usually 40 to 90°C, but when a redox catalyst is used, polymerization can be carried out at a temperature lower than this.

Vinyl acetate and acrylamide may be polymerized by adding their entire amounts first, or may be added in portions or continuously for polymerization.

The synthetic resin emulsion is made by combining the vinyl acetate/acrylamide copolymer obtained by the above method with olefin, vinyl ester, vinyl halide, and α.

1 to 30% of the solid content of the resin whose main component is one or more selected from the group of esters of β-unsaturated carboxylic acids.
It is obtained by carrying out the polymerization using 20% by weight, preferably 3 to 10% by weight.

The olefin preferably has 2 to 4 carbon atoms, and specific examples thereof include ethylene, propylene, butene, and the like.

Examples of vinyl esters include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl laurate, and vinyl versatate, with vinyl acetate or a mixture of vinyl acetate and other vinyl esters being particularly preferred. .

Vinyl halides include vinyl chloride, vinyl bromide,
Examples include vinylidene chloride.

Esters of α,β-unsaturated carboxylic acids include methyl acrylate, ethyl acrylate, propyl acrylate,
Isopropyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate, lauryl acrylate, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, hexyl methacrylate, methacrylic acid Alkyl esters of CI''cps of acrylic or methacrylic acid such as octyl, lauryl methacrylate, cyclohexyl methacrylate.

or cycloalkyl ester methoxybutyl acrylate, methoxybutyl methacrylate, methoxyethyl acrylate, methoxyethyl methacrylate, ethoxybutyl acrylate, ethoxybutyl methacrylate, etc. alkoxyalkyl ester of acrylic or methacrylic acid hydroxyethyl acrylate, hydroxyethyl 02-C8 hydroxyalkyl esters of acrylic acid or methacrylic acid such as methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate.

Monoester of acrylic acid or methacrylic acid and polyethylene glycol or polypropylene glycol such as polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, polypropylene glycol monoacrylate, polyethylene glycol monoacrylate, glycidyl acrylate or glycidyl methacrylate and C2-C, monocarboxylic acid Examples include adducts with compounds.

Particularly preferred combinations of monomer groups in synthetic resin emulsions include vinyl acetate, vinyl acetate/ethylene,
Examples include vinyl chloride/vinyl acetate/ethylene, vinyl chloride/ethylene, vinyl chloride/vinyl acetate, vinyl chloride/acrylic acid ester, and the like.

As the polymerization initiator used in the polymerization of the synthetic resin emulsion, any polymerization initiator used in -S emulsion polymerization can be used. That is, various free radical forming catalysts are used, such as peroxides and cerium ions.

A particularly suitable polymerization initiator that is often used is a so-called redox catalyst consisting of a combination of an oxidizing agent and a reducing agent. Suitable oxidizing agents include hydrogen peroxide, organic peroxides such as benzoyl peroxide, lauroyl peroxide, t-butyl hydroperoxide, and similar salts of ammonium persulfate, potassium persulfate, sodium persulfate and perboric acid. etc.

In addition, examples of reducing agents include bisulfites, sulfoxylates, ferrous salts, sugars, Rongalite, oxalic acid, and the like.

The amount of the initiator used is not particularly limited, but is preferably 0.1 to 2% by weight based on the monomer.

The pH of the aqueous dispersion is maintained between 3 and 7 by suitable pH regulators. Examples of PH9Jl modifiers include ammonium bicarbonate, sodium or disodium F:acid, sodium acetate, aqueous ammonia, acetic acid, and hydrochloric acid, which may be used alone or in combination of two or more.

There is no particular restriction on the polymerization temperature, but a suitable polymerization temperature is 30~
lOO<0>C, preferably 40-80<0>C. A temperature lower than 30°C is undesirable because the polymerization rate of the monomer tends to decrease.

There are no restrictions on the polymerization pressure. Further, there is no particular restriction on the method of adding the monomer, and the entire amount thereof may be added at the beginning for polymerization, or may be added in portions or continuously for polymerization.

The vinyl acetate/acrylamide copolymer aqueous solution is produced, for example, as follows.

Water and ammonium persulfate are placed in a 2N separable flask equipped with a reflux condenser, thermometer, and stirrer, and the mixture is heated and stirred to completely dissolve. After purging the inside of the reaction system with nitrogen gas, an aqueous acrylamide solution in which sodium hypophosphite is dissolved and vinyl acetate are fed into the reaction system at a constant rate for a certain period of time and allowed to react.

A conventional polymerization method can be used to produce a synthetic resin emulsion using the vinyl acetate/acrylamide copolymer thus obtained. For example, reflux condenser, thermometer,
A vinyl acetate/acrylamide copolymer aqueous solution and a ferrous sulfate aqueous solution are put into a 21 separable flask equipped with a stirrer, and after raising the temperature, the inside of the reaction system is purged with nitrogen gas.
Next, ammonium persulfate aqueous solution and Rongalite aqueous solution in which vinyl acetate and sodium acetate are dissolved are fed into the reaction system at a constant rate for a certain period of time to cause a reaction.

In addition, when polymerizing olefins, put vinyl acetate/acrylamide copolymer aqueous solution, water, and ferrous sulfate aqueous solution into a 5N pressure-resistant reactor equipped with a reaction temperature controller, raise the temperature, and then release the olefin into the reaction system. purge to remove oxygen,
After adding the olefin to a predetermined pressure, vinyl acetate is fed into the reaction system at a constant rate together with a catalyst and a PH3Ji moderator for a predetermined period of time to react.

<Examples> The present invention will be described in detail with reference to Examples below, but these are merely illustrative and do not limit the content of the present invention.

The analysis method is as follows.

(1) Solid content Compliant with JIS X6839 4.2.

Accurately weigh the emulsion onto an aluminum foil plate 1
After drying for 3 hours in a dryer kept at 05°C, it was allowed to cool in a desiccator. Weigh the mass, and calculate the solid content (wt
χ) was calculated.

Solid content (wtχ) = -X100 (2) Viscosity Compliant with JIS X6838-4.

Pour the emulsion into a container and make the emulsion temperature 25±0.
．． The temperature was adjusted by placing it in a constant temperature bath until the temperature reached 5°C, and the temperature was measured using a BL type rotational viscometer (manufactured by Tokyo Keiki Seisakusho@Sun).

The rotation speed of the viscometer was set to 60 rotations/win, and the viscosity was calculated by reading the scale shown on the indicator after rotating for 1 minute and multiplying by a specified conversion multiplier.

(3) Particle size (μ) After adding water to the emulsion to adjust the concentration to 0.01%, the particle size was determined by the turbidity method using a UV spectrophotometer (manufactured by Hitachi ■).

(4) Whitening time (water drop test) Compliant with JIS X6828 4.10.

Spread the emulsion all over a slide glass and dry it to form a continuous film with a thickness of about 0.2 mm.
After leaving it for more than 4 hours, place the glass slide horizontally on a newspaper with the coating facing up, and soak it with 1 cup of room temperature water.
Drop onto the film. The time until 8-point type becomes unreadable (hereinafter referred to as whitening time) is measured.

Example-1 750 g of water - 11.4 ammonium persulfate in 21 separable flasks equipped with a reflux condenser, thermometer, and stirrer
g was added, the temperature was raised to 50°C, and the mixture was stirred to completely dissolve. After purging the reaction system with nitrogen gas, 750 g of a 40% acrylamide aqueous solution in which 9.6 g of sodium hypophosphite was dissolved.
g and 75 g of vinyl acetate were fed into the reaction system at a constant rate for 4 hours at 50° C. to react. After 4 hours, the mixture was cooled to complete the polymerization.

The reaction product has a solid content of 25χ (resin content of 24χ) and a viscosity of 22
cps (25°C).

The vinyl acetate/acrylamide copolymer aqueous solution obtained here was used to polymerize various synthetic resin emulsions in the following examples.

Example-2 110 g of the vinyl acetate/acrylamide copolymer aqueous solution obtained in Example-1 (26 g of copolymer) and 360 g of water were placed in 21 separable flasks equipped with a reflux condenser, a thermometer, and a stirrer. .Add 9g of 2% ferrous sulfate aqueous solution,
After raising the temperature to 50°C, the inside of the reaction system was purged with nitrogen gas.

Next, a 2% ammonium persulfate aqueous solution and a 2% Rongalite aqueous solution in which 400 g of vinyl acetate and 2 g of sodium acetate were dissolved were fed into the reaction system at a constant rate for 6 hours to cause a reaction. After 6 hours, when the vinyl acetate monomer content decreased to 0.27%, it was cooled to complete the polymerization.

The evaluation results of the obtained vinyl acetate emulsion are shown in Table 1.

Example-3 Example-3 was applied to 51 pressure-resistant reactor equipped with a reaction temperature controller.
400 g of vinyl acetate/acrylamide copolymer aqueous solution obtained in step 1 (96 g of copolymer), 700 g of water, 0.2
After adding 24 g of % ferrous sulfate aqueous solution and raising the temperature to 50°C,
The inside of the reaction system was purged with ethylene to remove oxygen, and ethylene was added to bring the pressure to 20 kg/ctA. Next, 1200 g of vinyl acetate was added at a constant rate for 5 hours, and 3% ammonium persulfate aqueous solution in which 6 g of sodium acetate was dissolved, 3
% Rongalit aqueous solution was supplied into the reaction system at a constant rate for 6 hours to react. The ethylene pressure during polymerization was kept constant at 20 kg/d. After 6 hours, when the vinyl acetate monomer content decreased to 0.50%, the polymerization was completed by cooling.

The evaluation results of the obtained vinyl acetate emulsion are shown in Table 1.

Example-4 5! equipped with a reaction temperature controller and a stirrer. 340 g of vinyl acetate/acrylamide copolymer aqueous solution (80 g of copolymer) obtained in Pressure-resistant reactor Example-1 and 830 g of water, 0
．． After adding 20 g of a 2% ferrous sulfate aqueous solution and raising the temperature to 50°C, the inside of the reaction system was purged with ethylene to remove oxygen.
Ethylene was added to bring the pressure to 20 kg/cIIl. Next, 450 g of vinyl acetate and 550 g of vinyl chloride were fed into the reaction system at a constant rate for 5 hours, and 3% ammonium persulfate aqueous solution and 3% longalisotho aqueous solution in which 6 g of sodium acetate were dissolved were each fed into the reaction system at a constant rate for 6 hours to react. Ta.

The ethylene pressure during polymerization was kept constant at 20 kg/cot.

After 6 hours, when the vinyl acid monomer content decreased to 0.38%, the mixture was cooled and the polymerization was completed.

The evaluation results of the emulsion are shown in Table 1.

Example-5 340 g of the vinyl acetate/acrylamide copolymer aqueous solution obtained in Example-1 (80 g of copolymer) and 830 g of water were placed in a 51 pressure-resistant reactor equipped with a reaction temperature controller and a stirrer.
．． After adding 20 g of a 2% ferrous sulfate aqueous solution and raising the temperature to 50°C, the inside of the reaction system was purged with ethylene to remove oxygen, and ethylene was added to bring the pressure to 50 kg/cal. Next, 1000 g of vinyl chloride was fed into the reaction system at a constant rate for 5 hours, and a 3% ammonium persulfate aqueous solution and a 3% longalisotho aqueous solution in which 6 g of sodium acetate were dissolved were each fed into the reaction system at a constant rate for 6 hours to cause a reaction. No ethylene was fed during the polymerization. After 6 hours, the mixture was cooled to complete the polymerization.

The evaluation results of the emulsions are shown in Table 1.

Comparative Example-1 Polymerization initiation 4 was performed in the same manner as in Example-3 obtained in Example-1, except that 96 g of polyacrylamide was used instead of 96 g of vinyl acetate/acrylamide copolymer.
After some time the emulsion solidified.

Comparative Example-2 Polymerization was carried out in the same manner as in Example-3, except that 96 g of polyvinyl alcohol (saponification degree 88 mo Iχ, polymerization degree 500) was used instead of 96 g of the vinyl acetate/acrylamide copolymer obtained in Example-1. did.

The evaluation results of the emulsions are shown in Table 1.

Table 1 Evaluation results of emulsions (effects of the invention) As described above, by implementing the method of the present invention,
It is now possible to produce a stable synthetic resin emulsion that does not contain an emulsifier, and the film has particularly excellent water resistance, making it extremely valuable industrially.

Claims (4)

[Claims] (1) In the production of synthetic resin emulsions whose main components are one or more selected from the group of olefins, vinyl esters, vinyl halides, and α, β-unsaturated carboxylic acid esters, vinyl acetate/acrylamide and A method for producing a synthetic resin emulsion, which comprises adding a polymer and polymerizing it. (2) The method for producing a synthetic resin emulsion according to claim 1, wherein the vinyl acetate/acrylamide copolymer has a ratio of vinyl acetate to acrylamide of 1 to 70% by weight. (3) The method for producing a synthetic resin emulsion according to claim 1, wherein the vinyl acetate/acrylamide copolymer is used in an amount of 1 to 20% by weight based on the resin solid content of the synthetic resin emulsion. (4) The method for producing a synthetic resin emulsion according to claim 1, wherein the vinyl acetate/acrylamide copolymer has a number average molecular weight of 500 to 100,000.