JP2625812B2 - Production method of synthetic resin emulsion - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a highly stable synthetic resin emulsion containing no emulsifier.

<Prior Art> Conventionally, synthetic resin emulsions are produced by emulsion polymerization using an anionic, nonionic, cationic or amphoteric surfactant as an emulsifier, or a protective colloid such as polyvinyl alcohol, cellulose ether, or polyvinylpyrrolidone. However, there was a drawback that various surfactants reduced the strength, water resistance, weather resistance, adhesiveness, and the like of the coating film (film).

To solve these problems, various emulsions using a water-soluble polymer as a dispersion stabilizer have been proposed. For example, as disclosed in JP-B-57-8129, acrylamide is copolymerized for stabilization, or JP-B-62-4400.
No. 2 using polyacrylamide and polyethylene glycol as dispersion stabilizers, or JP-B-46
There is one using poly-N-methylolacrylamide as in -27244. However, these dispersion stabilizers are inferior in emulsifying power to conventional emulsifiers and have a possibility of coagulating during polymerization.

<Problems to be solved by the invention> In view of the present situation, the present invention provides a method for improving the coating performance of a synthetic resin emulsion, which has been regarded as a disadvantage in the related art,
Emulsifier-free, and intended to produce a stable synthetic resin emulsion, if a stable synthetic resin emulsion containing no emulsifier is prepared, the strength of the coating film obtained by drying, It can be expected that the water resistance, weather resistance and adhesive will be improved.

<Means for Solving the Problems> The present invention relates to a polymer obtained by polymerizing one or more selected from the group consisting of olefins, vinyl esters, vinyl halides and α, β-unsaturated carboxylic esters. Acrylic acid, methacrylic acid, itaconic acid, acrylamide,
Methacrylamide, 2-aminoethyl vinyl ether,
It is at least one selected from the group consisting of dimethylaminoethyl methacrylate, t-butylaminoethyl methacrylate, N-methylolacrylamide, N-methylolmethacrylamide, glycidyl acrylate, glycidyl methacrylate, 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate. A copolymer of a hydrophilic monomer having a functional group and vinyl acetate is added and polymerized, and the ratio of the hydrophilic monomer having a functional group and the vinyl acetate copolymer to the hydrophilic monomer of vinyl acetate is 1 to 70. The present invention relates to a method for producing a synthetic resin emulsion which is a weight%.

The ratio of the copolymer of the hydrophilic monomer containing a functional group and vinyl acetate used in the present invention to the hydrophilic monomer containing the functional group of vinyl acetate is 1 to 70% by weight, preferably
It is 10 to 40% by weight.

When the content is 1% by weight or less or 70% by weight or more, the emulsion obtained by using a vinyl acetate copolymer with a hydrophilic monomer having a functional group is unstable, and during the polymerization, the emulsion solidifies, Many coarse particles,
Mechanical stability tends to be inferior, which is not preferable.

Hydrophilic monomers containing a functional group include acrylic acid, methacrylic acid, itaconic acid, acrylamide, methacrylamide, 2-aminoethyl vinyl ether, dimethylaminoethyl methacrylate, t-butylaminoethyl methacrylate, N-methylol acrylamide, N-methylol Methacrylamide, glycidyl acrylate,
It is at least one selected from the group consisting of glycidyl methacrylate, 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate.

Particularly preferred hydrophilic monomers are acrylamide and acrylamide derivatives, and acrylamide derivatives include methacrylamide, N-methylolacrylamide, N-methylolmethacrylamide,
-Methoxymethylacrylamide, N-ethoxymethylacrylamide, N-butoxymethylacrylamide,
Examples include acetyloxymethyl acrylamide and 2-methylpropanesulfonic acid acrylamide.

Further, two or more kinds of hydrophilic monomers used in the present invention may be used.

Examples of the polymerization initiator 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. A redox catalyst comprising an azobis compound or a combination of the above water-soluble oxidizing agent and a water-soluble reducing agent such as sodium bisulfite, sodium pyrosulfite, sodium formaldehyde sulfoxylate (Rongalit), triethanolamine, dimethylaminopropionitrile and the like. There is
Both can be used. Further, the number average molecular weight of the copolymer by a molecular weight modifier such as sodium hypophosphite is 500 to 1
000,000, preferably 800-500,000. The polymerization temperature is usually 40 to 90 ° C, but when a redox catalyst is used, the polymerization can be carried out at a temperature lower than this.

The synthetic resin emulsion is obtained by mixing the acrylamide / vinyl acetate copolymer obtained by the above method with one or two selected from the group consisting of olefin, vinyl ester, vinyl halide, and ester of α, β-unsaturated carboxylic acid. It is obtained by performing polymerization using 1 to 20% by weight, preferably 3 to 10% by weight, based on the solid content of the resin containing the above as a main component. The olefin preferably has 2 to 4 carbon atoms, and specific examples thereof include ethylene, propylene, and butene.

Examples of the vinyl ester include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl laurate, vinyl versatate, and the like, and particularly preferably vinyl acetate or a mixture of vinyl acetate and another vinyl ester. .

Examples of the vinyl halide include vinyl chloride, vinyl bromide, and vinylidene chloride.

As esters of α, β-unsaturated carboxylic acids, methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate, lauryl acrylate, cyclohexyl acrylate, methacryl methyl, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, hexyl methacrylate, octyl, lauryl methacrylate, alkyl esters of C ₁ -C ₁₈ acrylic or methacrylic acid such as cyclohexyl methacrylate Or
Alkoxyalkyl esters of acrylic acid or methacrylic acid such as cycloalkyl ester methoxybutyl acrylate, methoxybutyl methacrylate, methoxyethyl acrylate, methoxyethyl methacrylate, ethoxybutyl acrylate, ethoxybutyl methacrylate, etc.Hydroxyethyl acrylate, hydroxyethyl methacrylate Acrylic or methacrylic acid such as hydroxypropyl acrylate and hydroxypropyl methacrylate
C ₂ -C ₈ hydroxyalkyl esters, polyethylene glycol monoacrylate, monoesters of polyethylene glycol monomethacrylate, polypropylene glycol monoacrylate, acrylic acid or methacrylic acid with polyethylene glycidyl roll or polypropylene glycol and polypropylene glycol monomethacrylate,
An adduct of glycidyl acrylate or glycidyl methacrylate with a C ₂ -C ₈ monocarboxylic acid compound, and the like can be mentioned.

Particularly preferred combinations of the monomer groups in the synthetic resin emulsion include vinyl acetate, vinyl acetate / ethylene, vinyl chloride / vinyl acetate / ethylene, vinyl chloride /
Ethylene, vinyl chloride / vinyl acetate, vinyl chloride / acrylate, and the like.

As the polymerization initiator used for the polymerization of the synthetic resin emulsion, any polymerization initiator generally used for emulsion polymerization can be used. That is, various free radical forming catalysts such as peroxides and cerium ions are used. Particularly suitable as a polymerization initiator that is frequently used is a so-called redox catalyst comprising two combinations 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 the like, ammonium persulfate, potassium persulfate, sodium persulfate and similar salts of perboric acid. Etc. Examples of the reducing agent include bisulfite, sulfoxylate, ferrous salt, saccharide, Rongalit, and oxalic acid.

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

The aqueous dispersion maintains the pH at 3 to 7 with a suitable pH modifier. Examples of the pH adjuster include ammonium bicarbonate and sodium or disodium phosphate, sodium acetate, aqueous ammonia, acetic acid, and hydrochloric acid. These may be used alone or in combination of two or more.

The polymerization temperature is not particularly limited, but an appropriate polymerization temperature is 30 to
The temperature is 100 ° C, preferably 40 to 80 ° C. If the temperature is lower than 30 ° C., the polymerization rate of the monomer tends to decrease, which is not preferable.

There is no restriction on the polymerization pressure. Also, there is no particular limitation on the method of adding the monomer, and the entire amount thereof may be added first and then polymerized, or may be added in portions or continuously added to carry out the polymerization.

Production of a hydrophilic monomer having a functional group and an aqueous solution of a vinyl acetate copolymer is carried out, for example, as follows.

Water and ammonium persulfate are put into two separable flasks equipped with a reflux condenser, a thermometer, and a stirrer, and heated and stirred to completely dissolve. After replacing the inside of the reaction system with nitrogen gas, a hydrophilic monomer aqueous solution in which sodium hypophosphite is dissolved and vinyl acetate are supplied into the reaction system at a constant rate for a certain period of time to cause a reaction.

As a method for producing a synthetic resin emulsion using the hydrophilic monomer / vinyl acetate copolymer thus obtained, a usual polymerization method is used. For example, a hydrophilic monomer / vinyl acetate copolymer aqueous solution and a ferrous sulfate aqueous solution are placed in two separable flasks equipped with a reflux condenser, a thermometer, and a stirrer, and heated, and then the reaction system is filled with nitrogen gas. Replace. Next, an aqueous solution of ammonium persulfate and an aqueous solution of Rongalite in which vinyl acetate and sodium acetate are dissolved are supplied into the reaction system at a constant rate for a certain period of time to cause a reaction.

When polymerizing olefins, the hydrophilic monomer / vinyl acetate copolymer aqueous solution, water, and ferrous sulfate aqueous solution are placed in a pressure-resistant reactor 5 equipped with a reaction temperature controller, and the temperature is raised. Is purged with olefin to remove oxygen, olefin is added to bring the pressure to a predetermined value, and vinyl acetate is fed into the reaction system for a predetermined time at a constant rate together with a catalyst and a pH regulator to cause a reaction.

<Examples> Hereinafter, the contents of the present invention will be described with reference to Examples.
These are all examples and do not limit the content of the present invention.

 The analysis method is as follows.

(1) Solids This was based on JIS K6839 4.2.

Accurately weigh the emulsion on an aluminum foil dish
After drying in a dryer kept at 105 ° C. for 3 hours, the mixture was allowed to cool in a desiccator. The mass is weighed and the solid content (wt
%).

D: Mass of sample after drying (g) S: Mass of emulsion (g) (2) Viscosity It conformed to JIS K6838-4.

Take the emulsion in a container and set the emulsion temperature to 25 ± 0.
It was placed in a thermostat until the temperature reached 5 ° C., adjusted, and measured with a BL type rotational viscometer (manufactured by Tokyo Keiki Seisakusho Co., Ltd.).

The rotation speed of the viscometer was set to 60 rotations / min, and the scale was read on the indicator after one minute of rotation, and the viscosity was calculated by multiplying by a specified conversion multiplier.

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

Example 1 750 g of water and 11.4 g of ammonium persulfate were placed in two separable flasks equipped with a reflux condenser, a thermometer, and a stirrer, heated to 60 ° C., stirred and completely dissolved. After replacing the inside of the reaction system with nitrogen gas, 750 g of a 40% aqueous solution of acrylamide dissolved with 9.6 g of sodium hypophosphite and 75 g of vinyl acetate
Was supplied into the reaction system at a constant rate at 60 ° C. for 4 hours to cause a reaction. After 4 hours, the mixture was cooled to complete the polymerization.

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

Example 2 The same operation as in Example 1 was carried out, except that 750 g of a 40% aqueous acrylamide solution was replaced with 30% acrylamide, 10%.
The reaction was carried out using 750 g of an aqueous solution of% N-methylolacrylamide.

The reaction product has a solid content of 25% (resin content of 24%) and a viscosity of 23 cps (2
5 ° C.).

Example 3 The same operation as in Example 1 was carried out, except that 750 g of a 40% aqueous acrylamide solution was replaced with 30% acrylamide, 10%.
The reaction was carried out using 750 g of an aqueous solution of acrylic acid.

The reaction product has a solid content of 25% (resin content of 24%) and a viscosity of 20 cps (2
5 ° C.).

Example 4 The same operation as in Example 1 was carried out except that 750 g of a 40% aqueous acrylamide solution was replaced with 30% acrylamide, 10%.
% 2-methylpropanesulfonic acid acrylamide aqueous solution
The reaction was carried out using 750 g.

The reaction product has a solid content of 25% (resin content of 24%) and a viscosity of 50 cps (2
5 ° C.).

Example-5 The same operation as in Example-1 was carried out, except that 750 g of a 40% aqueous acrylamide solution was replaced with 18.8% acrylamide and 7.
The reaction was carried out using 1000 g of an aqueous solution of 5% N-methylolacrylamide and 3.8% of 2-methylpropanesulfonic acid acrylamide.

The reaction product has a fixed content of 21% (resin content 20%) and a viscosity of 26 cps (2
5 ° C.).

Example 6 The same operation as in Example 1 was carried out, except that 1000 g of a 30% aqueous solution of N-methylolacrylamide was used instead of 750 g of a 40% aqueous acrylamide solution.

The reaction product has a solid content of 21% (resin content 20%) and a viscosity of 15 cps (2
5 ° C.).

Example 7 The same operation as in Example 1 was carried out in a three separable flask equipped with a reflux condenser, a thermometer and a stirrer, except that 750 g of a 40% aqueous acrylamide solution was replaced with 17.5% N-methylolacrylamide, 2.5% The reaction was carried out using 1500 g of an aqueous solution of 2-methylpropanesulfonic acid acrylamide.

The reaction product has a solid content of 17% (resin content 16%) and a viscosity of 20 cps (2
5 ° C.).

In the following Examples, various synthetic resin emulsions were polymerized using the various copolymer aqueous solutions obtained in Examples 1 to 7.

Example-8 110 g (26 g of copolymer) of the aqueous solution of the acrylamide / vinyl acetate copolymer obtained in Example 1 and 360 g of water were placed in two separable flasks equipped with a reflux condenser, a thermometer, and a stirrer.
g and 9 g of a 0.2% ferrous sulfate aqueous solution were added, and the temperature was raised to 50 ° C., and then the inside of the reaction system was replaced with nitrogen gas. Next, vinyl acetate 40
A 2% aqueous solution of ammonium persulfate in which 2 g of 0 g sodium acetate was dissolved was supplied into the reaction system at a constant rate for 6 hours to cause a reaction. Six hours later, when the vinyl acetate monomer decreased to 0.27%, the mixture was cooled to terminate the polymerization.

The reaction product has a solid content of 39%, a viscosity of 9 cps (25 ° C), and a particle size of 0,0.
It was a stable dispersion of 50μ.

Example-9 The same operation as in Example-8 was performed, except that 110 g of the aqueous acrylamide / vinyl acetate copolymer solution was used.
Polymerization was carried out using 130 g (26 g of copolymer) of the aqueous solution of N-methylolacrylamide / vinyl acetate copolymer obtained in 6 above.

The reaction product has a solid content of 34%, a viscosity of 9 cps (25 ° C), and a particle size of 0,0.
It was a stable dispersion of 43μ.

Example-10 400 g of the aqueous solution of the acrylamide / vinyl acetate copolymer obtained in Example 1 (96 g of the copolymer), 700 g of water, and 0.2% sulfuric acid in a 5 pressure-resistant reactor equipped with a reaction temperature controller. After adding 24 g of an aqueous iron solution and raising the temperature to 50 ° C., the reaction system was purged with ethylene to remove oxygen, and ethylene was added to increase the pressure to 20 ° C.
kg / cm ² . Then, 1200 g of vinyl acetate was supplied at a constant rate for 5 hours, and a 3% aqueous solution of ammonium persulfate in which 6 g of sodium acetate was dissolved and a 3% aqueous solution of Rongalite were supplied into the reaction system at a constant rate for 6 hours to cause a reaction. The pressure of ethylene during the polymerization was kept constant at 20 kg / cm ² . Six hours later, when the vinyl acetate monomer decreased to 0.50%, the mixture was cooled to terminate the polymerization.

Reaction product is 50% solids, viscosity 26 cps (25 ° C), particle size
It was a stable dispersion of 0.45μ.

Example-11 The same operation as in Example-10 was performed, except that acrylamide /
Example 2 was replaced with 400 g of the vinyl acetate copolymer aqueous solution.
Polymerization was carried out using 400 g of the aqueous solution of acrylamide / N-methylolacrylamide / vinyl acetate copolymer (96 g of copolymer) obtained in the above.

The reaction product is 51% solids, viscosity 36 cps (25 ° C), particle size
It was a stable dispersion of 0.41μ.

Example-12 The same operation as in Example-10, except that acrylamide /
Example 3 was replaced with 400 g of the vinyl acetate copolymer aqueous solution.
Polymerization was carried out using 400 g of the acrylamide / acrylic acid / vinyl acetate copolymer (96 g of the copolymer) obtained in the above.

Reaction product is 50% solids, viscosity 23 cps (25 ° C), particle size
It was a stable dispersion of 0.50μ.

Example 13 The same operation as in Example 10 was carried out except that acrylamide /
Instead of using 400 g of the vinyl acetate copolymer aqueous solution, Example-7 was used.
N-methylolacrylamide / 2-methylpropanesulfonic acid acrylamide / vinyl acetate copolymer obtained by
Polymerization was carried out using 600 g (96 g of copolymer).

Reaction product 46% solids, viscosity 80 cps (25 ° C), particle size
It was a stable dispersion of 0.31μ.

Example -14 340 g of the aqueous solution of acrylamide / 2-methylpropanesulfonic acid acrylamide / vinyl acetate copolymer (80 g of copolymer) obtained in Example 4 was placed in a pressure-resistant reactor equipped with a reaction temperature controller and a stirrer. ), 830 g of water and 20 g of 0.2% ferrous sulfate aqueous solution, and the temperature was raised to 50 ° C. Then, the reaction system was purged with ethylene to remove oxygen, and ethylene was added to increase the pressure to 50%.
kg / cm ² . Next, 1000 g of vinyl chloride was supplied at a constant speed for 5 hours, and a 3% aqueous solution of ammonium persulfate in which 6 g of sodium acetate was dissolved and a 3% aqueous solution of Rongalite were supplied into the reaction system at a constant speed for 6 hours to cause a reaction. No ethylene was supplied during the polymerization. After 6 hours, the mixture was cooled to complete the polymerization.

Reaction product is 48% solids, viscosity 120cps (25 ℃), particle size
It was a stable dispersion of 0.31μ.

Example -15 400 g of the acrylamide / 2-methylpropanesulfonic acid acrylamide / vinyl acetate copolymer obtained in Example -5 in 5 pressure-resistant reactors equipped with a reaction temperature controller and a stirrer.
(Copolymer 96 g), water 700 and 0.2 g of 0.2% ferrous sulfate aqueous solution were added, the temperature was raised to 50 ° C., the reaction system was purged with ethylene to remove oxygen, ethylene was added, and the pressure was increased to 20 kg / kg. It was to cm ^2. Then, 450 g of vinyl acetate and 550 g of vinyl chloride were supplied at a constant rate for 5 hours, and a 3% aqueous solution of ammonium persulfate in which 6 g of sodium acetate was dissolved and a 3% aqueous solution of Rongalite were supplied into the reaction system at a constant rate for 6 hours to cause a reaction. Was. The pressure of ethylene during the polymerization was kept constant at 20 kg / cm ² . Six hours later, when the vinyl acetate monomer decreased to 0.50%, the mixture was cooled to terminate the polymerization. Reaction product is 50% solids, viscosity 32 cps
(25 ° C.) A stable dispersion having a particle size of 0.41 μm.

Example 16 The same operation as in Example 11 was performed, except that 1200 g of vinyl acetate was used.
Instead, 500 g of vinyl acetate and 500 g of 2-ethylhexyl acrylate were supplied at a constant rate for 5 hours to carry out polymerization.

The reaction product has a solid content of 40% and a viscosity of 14 cps (25 ° C).
It was a stable dispersion of 2μ.

Example-17 750 g of water, 3.3 g of ammonium persulfate and 22 g of 0.2% ferrous sulfate aqueous solution were placed in a pressure-resistant reactor equipped with a reaction temperature controller and a stirrer and heated to 60 ° C., stirred and completely dissolved. Let me
After replacing the inside of the reaction system with nitrogen gas, 230 g of a 29% acrylamide and 9.6% N-methylolacrylamide aqueous solution in which 0.72 g of sodium hypophosphite was dissolved and 22 g of vinyl acetate were added to 60 g of the reaction mixture.
After the reaction was carried out by supplying the reaction system at a constant rate at 1 ° C. for 1 hour, the temperature was raised to 50 ° C., ethylene was added, and the pressure was raised to 20 kg / cm ² . Then, 450 g of vinyl acetate and 550 g of vinyl chloride were supplied at a constant rate for 5 hours, and a 3% aqueous solution of ammonium persulfate in which 6 g of sodium acetate was dissolved and a 3% aqueous solution of Rongalite were supplied into the reaction system at a constant rate for 6 hours to cause a reaction. Was. The pressure of ethylene during the polymerization was kept constant at 20 kg / cm ² . Six hours later, when the vinyl acetate monomer decreased to 0.50%, the mixture was cooled to terminate the polymerization.

The reaction product has a solid content of 50%, a viscosity of 296 cps (25 ° C) and a particle size of 0,0.
It was a 45 μ stable dispersion.

<Effect of the Invention> As described above, by performing the method of the present invention, it has become possible to produce a stable synthetic resin emulsion containing no emulsifier.

Claims (2)

(57) [Claims] 1. A synthetic resin emulsion comprising a polymer obtained by polymerizing one or more selected from the group consisting of olefins, vinyl esters, vinyl halides and α, β-unsaturated carboxylic esters. In the production, acrylic acid, methacrylic acid, itaconic acid, acrylamide,
Methacrylamide, 2-aminoethyl vinyl ether,
Dimethylaminoethyl methacrylate, t-butylaminoethyl methacrylate, N-methylol acrylamide, N-methylol methacrylamide, glycidyl acrylate, glycidyl methacrylate, 2-hydroxyethyl acrylate and at least one selected from the group consisting of 2-hydroxypropyl acrylate A copolymer of a hydrophilic monomer having a functional group and vinyl acetate is added and polymerized, and the ratio of the hydrophilic monomer having a functional group and the vinyl acetate copolymer to the hydrophilic monomer of vinyl acetate is 1 to 70. A method for producing a synthetic resin emulsion which is a percentage by weight. 2. The process for producing a synthetic resin emulsion according to claim 1, wherein a copolymer of a hydrophilic monomer having a functional group and vinyl acetate is used in an amount of 1 to 20% by weight based on the resin solid content of the synthetic resin emulsion.