JP3225150B2 - Redispersible synthetic resin emulsion powder containing acetoacetyl group and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a redispersible synthetic resin emulsion powder obtained by pulverizing a synthetic resin emulsion produced using acetoacetylated polyvinyl alcohol as a protective colloid, and a method for producing the same. An object of the present invention is to provide a synthetic resin emulsion powder having excellent water resistance.

[0002]

2. Description of the Related Art A redispersible synthetic resin emulsion powder is
It is produced by spray-drying a synthetic resin emulsion. Compared to a synthetic resin emulsion, the powder is easier to handle and convenient to transport because it is a powder. When used, it has the property of being redispersed in water by adding the powder to water and stirring, so it can be used in a wide range of applications such as mixing in cement products such as adhesives, putties, paint binders, concrete structures, mortar, etc. It is used. However, many of the known synthetic resin emulsion powders that can be redispersed in water use a water-soluble polymer as a protective colloid for emulsion polymerization for redispersion.
There is a major drawback that the water resistance of the coating is inferior, and it has been desired to improve applied physical properties when wet.

[0003]

SUMMARY OF THE INVENTION The present invention provides an emulsion powder which is redispersed in water, exhibits almost the same properties as the original emulsion, and has excellent water resistance, and a process for producing the same.

[0004]

The redispersible synthetic resin emulsion powder containing an acetoacetyl group according to the present invention is produced by emulsion polymerization of an ethylenically unsaturated monomer using acetoacetylated polyvinyl alcohol as a protective colloid. It is obtained by spray drying the emulsion. According to a preferred embodiment of the present invention, it is preferable that a powdery curing agent that reacts with an acetoacetyl group is mixed with the emulsion powder obtained by spray drying. According to a more preferred embodiment of the present invention, the powdery curing agent that reacts with an acetoacetyl group is a powder of an aldehyde compound or a hydrazine compound. According to another preferred embodiment of the present invention,
The emulsion powder is a powder obtained by spray-drying the emulsion in the presence of an anti-binding agent. According to another more preferred aspect of the present invention, the anti-caking agent is a powder of calcium carbonate, silica, talc, and / or aluminum silicate. The method for producing a redispersible synthetic resin emulsion containing an acetoacetyl group according to the present invention comprises subjecting one or more ethylenically unsaturated monomers to emulsion polymerization using acetoacetylated polyvinyl alcohol as a protective colloid. It is characterized by spray-drying the obtained emulsion.

[0005]

A first feature of the present invention is to use an emulsion obtained by emulsion polymerization of an ethylenically unsaturated monomer using acetoacetylated polyvinyl alcohol as a protective colloid. When an emulsion using a surfactant is spray-dried into a powder, the particles aggregate to form secondary particles, and it is difficult to redisperse the particles in water. When a protective colloid is used, generation of secondary particles is small. By re-emulsification, an emulsion almost identical to the original emulsion is obtained.

A second feature of the present invention is to use a curing agent which reacts with an acetoacetyl group. Since acetoacetylated polyvinyl alcohol has a higher melting point than ordinary polyvinyl alcohol, it does not become tacky at the time of spray drying and has an excellent action with almost no generation of secondary particles. Further, when the film is formed, the acetoacetyl groups form hydrogen bonds with each other, so that the water resistance is excellent. However,
The present inventors have experimented with using a curing agent that reacts with an acetoacetyl group to improve the water resistance, since it may be used in places with high humidity and there is a demand for higher water resistance. Then, it was clarified that when a curing agent selected from an aldehyde compound or a hydrazine compound was used, crosslinking was carried out, so that the water resistance was significantly improved.

This is because the acetoacetyl group of the acetoacetylated polyvinyl alcohol and the aldehyde group of the aldehyde compound as a curing agent cause a dehydration condensation reaction, and the protective colloid becomes insoluble in water. Also, the hydrazine compound is insoluble in water due to a dehydration condensation reaction of an amino group with an acetoacetyl group. These hardeners need to be in powder form. When mixed with a liquid, the reaction proceeds, so that a powdery composition cannot be obtained. The powdery curing agent must be mixed with the spray-dried powder emulsion. This is because a reaction occurs if the mixture is spray-dried before the spray-drying. Similarly, even when spraying and drying independently from two nozzles, the reaction must be avoided because the reaction occurs.

A third feature of the present invention is that an anti-binder can be used in combination, for example, by spraying from another nozzle during spray drying. Further, ordinary protective colloids such as polyvinyl alcohol, methylcellulose, and hydroxyethylcellulose, and surfactants may be used in combination as long as no adverse effects are caused. The following are examples of the ethylenically unsaturated monomer used in the production of the emulsion in the present invention.

The ethylenic monomer capable of undergoing radical polymerization used in the present invention includes acrylates such as ethylene, methyl acrylate, ethyl acrylate, butyl acrylate and 2-ethylhexyl acrylate, and methyl methacrylate. Ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, stearyl methacrylate, etc., alkyl (meth) acrylates such as methacrylates, styrene, α-methylstyrene, vinyl toluene, etc. Styrene monomers, vinyl acetate, vinyl propionate, vinyl versatate, vinyl laurate, vinyl carboxylate such as vinyl stearylate,
Acrylonitrile, methacrylonitrile and the like.

The following curing agents are used in the present invention. Dialdehydes such as phthalaldehyde, polyaldehydes such as starch, diamines such as hexamethylenetetramine, ethylenediamine, phenylenediamine,
Polyamide amine resin, polyethylene imine, hydrazide compounds such as carbodihydrazide, β-naphthyl isocyanate, triphenylmethane triisocyanate, alkylated methylol urea, alkylated methylol melamine, acetoguanamine, condensate of benzoguanamine and formaldehyde, Amino-formaldehyde resins such as zirconium, zinc, magnesium, calcium, and aluminum; and polyvalent metal salts of alkaline earth metals and oxides thereof. Examples of the anti-binder used in the present invention include silica, calcium carbonate, and aluminum silicate having an average particle diameter of 0.01 to 0.1.
An inorganic fine powder of 5 μm can be used.

[0011]

EXAMPLES The present invention will be specifically described with reference to examples.

Example 1 A separable flask equipped with a stirrer and a reflux condenser was charged with 110 parts by weight of water, acetoacetyl having an average degree of polymerization of 2,000, a saponification value of 99%, and a degree of acetoacetylation of 2.5 mol%. And 10 parts by weight of chlorinated polyvinyl alcohol (Gosefimer Z100 manufactured by Nippon Synthetic Chemical Industry Co., Ltd.). Next, 100 parts by weight of vinyl acetate was charged and an emulsion having a concentration of 50% was obtained by ordinary emulsion polymerization. The concentration of this emulsion was adjusted and an anti-caking agent (trade name: Hydrocarb (Plus-Stauffer (PLU)
It was spray-dried in the presence of (SS-STAUFER) (Switzerland, calcium carbonate)) to obtain an emulsion powder. To this, 2 parts by weight of dialdehyde starch (trade name: Caldas (manufactured by Nippon Carlit Co., Ltd.)) was added, and the powder was sufficiently mixed.

Example 2 A separable frazco equipped with a stirrer and a reflux condenser was charged with 110 parts by weight of water, an acetate having an average degree of polymerization of 2,000, a saponification value of 99%, and a degree of acetoacetylation of 2.5 mol%. 10 parts by weight of acetylated polyvinyl alcohol is charged and dissolved. Next, 70 parts by weight of vinyl acetate and Veoba 1
0 (vinyl ester of Shell Chemical Co., Ltd.) was charged, and an emulsion having a concentration of 50% was obtained by ordinary emulsion polymerization. The concentration of this emulsion was adjusted and spray-dried in the presence of an anti-binder (trade name: hydrocarb) to obtain an emulsion powder.

Example 3 In a separable flask equipped with a stirrer and a reflux condenser, 110 parts by weight of water, acetoacetyl having an average degree of polymerization of 2,000, a saponification value of 99%, and a degree of acetoacetylation of 2.5 mol% were added. And 10 parts by weight of polyvinyl chloride. Next, 50 parts by weight of vinyl acetate, 30 parts by weight of Beova, and 20 parts by weight of butyl acrylate were charged, and an emulsion having a concentration of 50% was obtained by ordinary emulsion polymerization. The concentration of this emulsion was adjusted and spray-dried in the presence of an anti-binder (trade name: Zeoseal 1100V (manufactured by Taki Kagaku Co., Ltd., silica)) to obtain an emulsion powder. To this, 2 parts by weight of carbodihydrazide was added, and the powder was sufficiently mixed.

Example 4 A separable flask equipped with a stirrer and a reflux condenser was charged with 110 parts by weight of water, acetoacetyl having an average degree of polymerization of 2,000, a saponification value of 99%, and a degree of acetoacetylation of 2.5 mol%. And 10 parts of chlorinated polyvinyl alcohol. Next, 70 parts by weight of vinyl acetate and 30 parts by weight of butyl acrylate were charged, and an emulsion having a concentration of 50% was obtained by ordinary emulsion polymerization. The concentration of this emulsion was adjusted and spray-dried in the presence of an anti-binder (trade name: NN Kaolin Clay (Tsuchiya Kaolin Co., Ltd., aluminum silicate)) to obtain an emulsion powder. To this was added 2 parts by weight of dialdehyde starch, and the powder was sufficiently mixed.

Comparative Example 1 In a separable flask equipped with a stirrer and a reflux condenser, 110 parts by weight of water and 10 parts by weight of polyvinyl alcohol having an average degree of polymerization of 2,000 and a saponification value of 89% are charged and dissolved. Next, 100 parts by weight of vinyl acetate was charged and an emulsion having a concentration of 50% was obtained by ordinary emulsion polymerization.
By adjusting the concentration of this emulsion, an anti-binder (trade name:
It was spray-dried in the presence of hydrocarb) to obtain an emulsion powder. To this was added 2 parts by weight of dialdehyde starch, and the powder was sufficiently mixed.

Comparative Example 2 In a separable flask equipped with a stirrer and a reflux condenser, 110 parts by weight of water and 10 parts by weight of polyvinyl alcohol having an average degree of polymerization of 2,000 and a saponification value of 89% were charged and dissolved. Next, 50 parts by weight of vinyl acetate and Veoba 10
30 parts by weight and 20 parts by weight of butyl acrylate were charged, and an emulsion having a concentration of 50% was obtained by ordinary emulsion polymerization. The concentration of this emulsion was adjusted and spray-dried in the presence of an anti-binder (trade name: hydrocarb) to obtain an emulsion powder. Carboji hydrazide 2
By weight, the powder was sufficiently mixed.

Comparative Example 3 In a separable flask equipped with a stirrer and a reflux condenser, 110 parts by weight of water and 10 parts by weight of polyvinyl alcohol having an average degree of polymerization of 2,000 and a saponification value of 89% were charged and dissolved. Next, 50 parts by weight of vinyl acetate and Veoba 10
30 parts by weight and 20 parts by weight of butyl acrylate were charged, and an emulsion having a concentration of 50% was obtained by ordinary emulsion polymerization. The concentration of this emulsion was adjusted and spray-dried in the presence of an anti-binder (trade name: hydrocarb) to obtain an emulsion powder.

Evaluation (1) Redispersibility The obtained emulsion powder is added to water and stirred, and the state of the redispersed liquid is observed. A: A white uniform emulsion is obtained in a short time (3 minutes). : A white uniform emulsion is obtained after sufficient stirring (for 20 minutes). (2) Water resistance of the film The redispersion liquid is dried to form a film, and the film is immersed in water to observe the state of the film. A: Does not redisperse. : Slight re-dispersion. ×: Redistributed. Table 1 shows the evaluation results.

[0020]

[Table 1]

[0021]

The redispersible emulsion powder of the present invention has an excellent effect that redispersibility is easy and water resistance is good because secondary particles are not formed.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C08J 3/12 101

Claims (6)

(57) [Claims] An acetoacetyl group-containing redispersible synthetic resin emulsion powder obtained by spray drying an emulsion produced by emulsion polymerization of an ethylenically unsaturated monomer using acetoacetylated polyvinyl alcohol as a protective colloid. . 2. The redispersible synthetic resin emulsion powder containing an acetoacetyl group according to claim 1, wherein a powdery curing agent that reacts with an acetoacetyl group is mixed with the spray-dried emulsion powder. 3. The acetoacetyl group-containing redispersible synthetic resin emulsion powder according to claim 1, wherein the powdery curing agent that reacts with the acetoacetyl group is a powder of an aldehyde compound or a hydrazine compound. . 4. An acetoacetyl group-containing redispersible synthetic resin according to claim 1, wherein the emulsion powder is a powder obtained by spray-drying the emulsion in the presence of an anti-binding agent. Emulsion powder. 5. The acetoacetyl group-containing redispersible synthetic resin emulsion according to claim 1, wherein the anti-binder is a powder of calcium carbonate, silica, talc or aluminum silicate. Powder. 6. One or two ethylenically unsaturated monomers
A method for producing a redispersible synthetic resin emulsion containing an acetoacetyl group, comprising subjecting at least one species to emulsion polymerization using acetoacetylated polyvinyl alcohol as a protective colloid, and then spray-drying the obtained emulsion.