JPH0753727A - Blocking-resistant synthetic vinyl resin emulsion powder - Google Patents

Abstract

PURPOSE:To obtain the powder improved in blocking resistance by mixing an aq. charged synthetic resin emulsion particles with oppositely charged fine inorg. particles at a ratio satisfying a given formula, then mixing the resulting mixture with an aq. synthetic vinyl resin emulsion, and then spraying the resulting mixture. CONSTITUTION:An aq. emulsion of a synthetic resin, such as a polyacrylic ester, having positively or negatively charged surfaces of the particles thereof having an average particle size of 0.01 to 50mum is mixed with a dispersion of fine inorg. particles, such as silica, having an opposite charge to that of the emulsion particles and an average particle size of at most 1/2 of that of the emulsion particles at a ratio satisfying the formula (wherein (a) is the average radius of the emulsion particles; (b) is the average radius of the fine inorg. particles; and R is the number of the fine inorg. particles/the number of the emulsion particles) to prepare an emulsion A. The emulsion A is mixed with an aq. emulsion B of a synthetic vinyl resin having a glass transition point of at most 20 deg.C and obtd. by polymn. using a water-soluble polymer as a protective colloid or by copolymn. with an unsatd. carboxylic acid at an A/B solid wt. ratio of 50 to 5/50 to 95. The resulting mixture is sprayed to obtain a blocking-resistant synthetic vinyl resin emulsion powder.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to powdered emulsions. The powdery emulsion has excellent blocking resistance and good re-emulsification property, and is very useful as an admixture for cement and the like.

[0002]

2. Description of the Related Art Synthetic resin emulsion powders are easier to prepare in the field and have better handling and workability than synthetic resin aqueous emulsions, they can be prepared accurately, and they cannot be mixed with other powders. Because of its ease of use, it is used as an admixture for cement-based or gypsum-based compositions, a paint, or a component of various adhesives. The synthetic resin emulsion powder must be re-emulsified and used at room temperature so that the glass transition point of the synthetic resin must be 20 ° C. or lower.
Since such a synthetic resin is soft, the emulsion powder has a property of easily sticking to each other. Therefore, there has been a problem that powder particles are coagulated and blocked during the production of the synthetic resin emulsion powder or during storage and storage. Conventionally, as a means for preventing blocking, synthetic resin powder particles formed by adding inorganic fine powder having an average particle diameter of 0.01 to 0.5 μm, such as silica, calcium carbonate, and aluminum silicate, at the time of producing a synthetic resin emulsion powder. There is known a method of coating a powder with an inorganic fine powder. (Japanese Patent Publication No. 55-50971, Japanese Patent Publication No. 46-129)
07) However, the inorganic fine powder as an anti-blocking agent cannot obtain a sufficient effect unless a large amount of 3 to 30% by weight based on the synthetic resin is used. The water / cement ratio is increased due to the water absorption of the powder, and the final strength is inferior to the original synthetic resin aqueous emulsion. In addition, during production, specifically, when coating with inorganic fine particles before and after spray drying, the emulsion particles are not coated in the state of primary particles, so that the glass transition point is -40 ° C., in which the caking is particularly remarkable.
The powdering of the following synthetic resin aqueous emulsion was difficult due to the problem of blocking. (JP-A-4-2557
60) The present inventor has completed the invention of JP-A-62-213839, and in a liquid state, coats emulsion particles with an inorganic powder to obtain a uniform mixture of the inorganic powder and the emulsion. Provided the liquid. However, the powder of the emulsion is not yet known. The inventor is PH
Complete the invention No. 00005-68, give a charge to the surface of an aqueous emulsion particle, mix with an inorganic powder aqueous dispersion of opposite charge, electrically adsorb the inorganic powder on the surface of the emulsion particle, and spray dry this dispersion. And succeeded in producing a blocking resistant emulsion powder. Although this emulsion powder has a very excellent effect, it has a drawback that the selection range of the emulsion is limited because an emulsion having a charge is used.

[0003]

DISCLOSURE OF THE INVENTION In the present invention, since the emulsion A, which has been blocked by using an inorganic powder, has the effect of preventing the blocking of the emulsion B, the amount of the inorganic powder used is small in the whole emulsion.
The object of the present invention is to provide an emulsion powder in which the surface is coated with a necessary minimum amount of inorganic powder, blocking is prevented, and the performance of the re-emulsified emulsion is almost the same as that of the original emulsion.

[0004]

Means for Solving the Problems According to the present invention, "1. A. (a) a synthetic resin aqueous emulsion particle having a + or-charge on the surface of the particle and (b) an opposite charge to the emulsion particle. A dispersion liquid of inorganic fine particles having an average radius of 1/2 or less of the average radius of emulsion particles is represented by the following formula. (Where a is the average radius of the emulsion particles, b is the average radius of the inorganic particles, and R is the number of particles of the inorganic powder / the number of the emulsion particles), and the emulsion mixed with B. A vinyl-based aqueous synthetic resin emulsion obtained by polymerizing a water-soluble polymer as a protective colloid and / or a vinyl-based aqueous synthetic resin emulsion obtained by copolymerizing an unsaturated carboxylic acid, which is re-emulsifiable powder by spray drying. Blocking resistance obtained by uniformly mixing and spraying a vinyl-based synthetic resin aqueous emulsion having a point of 20 ° C. or less at a solid content ratio of A: B = 50 to 5 parts by weight: 50 to 95 parts by weight. Vinyl synthetic resin emulsion powder. 2. A. described in item 1. Emulsion and B.I. Blocking-resistant vinyl synthetic resin emulsion powder obtained by separately spraying and mixing the emulsions in a ratio of A: B = 50 to 5 parts by weight: 50 to 95 parts by weight, and simultaneously drying. 3. The synthetic resin emulsion with electric charge of (a)
Emulsion obtained by emulsion polymerization using one or more selected from a cationic or anionic monomer, a polymerization initiator giving a positive or negative terminal and a cationic or anionic polymerizable emulsifier. The blocking resistant vinyl-based synthetic resin emulsion powder according to item 1 or 2. 4. The blocking resistant vinyl system according to item 1 or 2, which is obtained by emulsion-polymerizing a cationic monomer or anionic monomer in an amount of 0.01 part by weight or more based on 100 parts by weight of the nonionic monomer. Synthetic resin emulsion powder. 5. The blocking resistant vinyl system according to item 1 or 2, which is obtained by emulsion polymerization using a polymerization initiator that gives a positive or negative terminal in an amount of 0.01 to 20 parts by weight based on 100 parts by weight of the polymerizable monomer. Synthetic resin emulsion powder. 6. Item (b), wherein the charged inorganic powder fine particles are inorganic powders whose charge is adjusted by adding an acid or an alkali to the aqueous dispersion to adjust the pH. Blocking-resistant vinyl synthetic resin emulsion powder. Regarding

[0005]

The present invention relates to a synthetic resin emulsion powder in which the surface of powder particles is uniformly coated with an inorganic fine powder, and the present invention relating to such an emulsion powder has some features. The present invention relates to the A. B. Two emulsions are used.

The first feature of the present invention is to mix an aqueous emulsion of synthetic resin having an electric charge on the surface of a particle with an aqueous dispersion of an inorganic fine powder having an opposite charge to form an inorganic fine particle on the surface of the emulsion particle. The use of Emulsion A coated with a powder that is electrically adsorbed. Since the particles are electrically adsorbed, other inorganic particles adhere to the surface on which the inorganic particles are not adhered and the surface of the emulsion particles is uniformly covered with the inorganic particles.

The second feature of the present invention is that the average radius of particles of the inorganic fine powder of emulsion A is 1/2 or less of the average radius of emulsion particles. If it is larger than 1/2, the inorganic particles are too large, so that the amount of the inorganic powder necessary for preventing blocking cannot cover the emulsion particles, and exposed portions tend to occur.

The third feature of the present invention is that the ratio of the number of emulsion particles mixed with emulsion A and the number of inorganic particles is set to a special range. The most important requirement for uniform coating is the ratio of the number of inorganic particles to the number of emulsion particles, that is, the number ratio (R) of the number of inorganic particles divided by the number of synthetic resin emulsion particles satisfies the following equation. That is. (R)> N × 0.5 N: Number of inorganic particles required to cover the surface of one synthetic resin emulsion particle most closely.

P: Surface area of one synthetic resin emulsion particle coated with inorganic particles = radius (a + b)
Spherical surface of = 4π (a + b) ² This P is a spherical surface area whose radius is the length of the emulsion particles and the radius of the coated inorganic particles, that is, of the inorganic particles coated in the closest packed state on the emulsion particle surface. It represents the surface area of the spherical surface connecting the points of contact with each other.

Q: Inorganic particles when the inorganic particles cover the surface of the synthetic resin emulsion particles most closely. (A = average radius of synthetic resin emulsion particles, b = average radius of inorganic particles)} Q is a surface including the interparticle gap per inorganic particle covering the surface of the emulsion particles in the closest packed state. Is represented. That is, two arbitrary particles A, which are adjacent to each other, are formed by taking three arbitrary particles of the inorganic particles which cover the emulsion particle surface in the closest packing state and contacting each other, and cutting the inorganic particles by a plane passing through the center of each particle. A line connecting the centers of B,
It is the area enclosed by a line connecting the centers of the above-mentioned two particles from the contact point with another particle C that contacts the two particles on the cut surface and a straight line passing through the center of the C particles.
This area is the distance b that connects the centers of particles A and B to b = 2b
And C particles and other particles The distance between the contact point between the C particle and another particle and the A or B particle is 2bsin6 because the center distance between the C particle and the A particle is 2b and the angle with the straight line passing through the center of the C particle is 60 °.
It becomes 0 °.

[0011] N is the area of a square per unit when the inorganic particles are closest packed, and the area of the square is the spherical surface (radius a +
How many are on the surface of b). In the present invention, the uniform coating does not need to be the densest coating, and it is important that the coating is uniform without unevenness. For that purpose, (R) must be 50% or more, preferably 70% or more of N. When (R) is less than 50% of N,
There will be more exposed areas and therefore larger aggregates will form. That is, other synthetic resin emulsion particles adhere to each other via the positive particles sparsely covered by the negative ionicity of the exposed synthetic resin emulsion particles, and agglomerate into large aggregates. The upper limit of (R) is not particularly limited, but since the excess inorganic particles are merely floating unnecessarily, about 150% is suitable for practical use.

The fourth feature of the present invention is that a water-soluble polymer compound is polymerized as a protective colloid and a vinyl synthetic resin emulsion B having a glass transition point of 20 ° C. or lower is used in combination.

The fifth feature of the present invention is to spray-dry the mixture A of the specific emulsion and the aqueous dispersion of the inorganic fine powder and the vinyl resin emulsion B having a glass transition temperature of 20 ° C. or lower. As described above, the present invention was carried out by coating the emulsion particles by mixing a liquid synthetic resin emulsion having an electric charge and an inorganic fine powder dispersion having an opposite electric charge. It was thought that blocking occurs during spray drying because the charge is lost at the time of separation and the two are separated.However, according to the research of the present inventor, particles of a specific particle size are combined at a specific number ratio and heat during drying is reduced. It was clarified that the particles do not separate even when spray-dried.

A: B = 50-5 parts by weight: 50-95 parts by weight of a synthetic resin emulsion A in which inorganic fine powder is electrically adsorbed on the surface of the particles and a vinyl-based synthetic resin emulsion B having a glass transition point of 20 ° C. or lower. Can be produced by uniformly mixing and spray-drying at a ratio of 1, or spraying separately and mixing and drying at the same time. A. B. When both emulsion fog droplets are dried in a mixed state, the emulsion A powder having the inorganic fine powder adsorbed on the surface coats the surface of the emulsion B powder to prevent blocking.

As the synthetic resin forming the emulsion A, polyvinyl acetate, polyacrylic acid ester, polyethylene, polypropylene, polystyrene, vinyl acetate-
Thermoplastic polymer particles such as ethylene copolymers, vinyl acetate- (meth) acrylic acid ester copolymers, styrene- (meth) acrylic acid ester copolymers, vinyl acetate-Veova (vinyl ester manufactured by Shell Chemical Co.) copolymers, and the like. It is suitable that these polymer particles have an average particle diameter of 0.01 to 50 μm. The dispersion liquid of polymer particles can be prepared by an emulsion polymerization method or a suspension polymerization method. It can also be made by post-emulsifying the polymer. In this way, the average particle size is 0.01 to
A dispersion of polymer particles in the range of 50 μm is obtained.

The resulting dispersion can be positively or negatively charged depending on the composition and manufacturing method. As a method for charging, either a cationic or anionic monomer, a polymerization initiator which gives a positive or negative polymer terminal, and a cationic or anionic polymerizable emulsifier are selectively used alone or in combination. A radical polymerization method may be used together with a nonionic monomer and other emulsifiers if necessary.

Examples of the cationic monomer include diethylaminoethyl methacrylate and dimethylaminoethyl methacrylate, and examples of the anionic monomer include acrylic acid and methacrylic acid. These ionic monomers may be polymerized individually, or may be used in combination with other nonionic monomers. In order to charge only the ionic monomer, 100 parts by weight of the nonionic monomer should be added to the ionic monomer of 0.
It is preferred to use at least 01 parts by weight, especially at least 0.2 parts by weight. If the amount is less than 0.01 parts by weight, the amount of charge of the obtained particles is insufficient and the particles cannot be used for the purpose of the present invention.

Examples of the polymerization initiator which gives a positive polymer terminal include 2,2'-azobis (2-amidinopropane) hydrochloride. Examples of the polymerization initiator which gives a negative polymer terminal include sodium persulfate, potassium persulfate, ammonium persulfate and the like. These polymerization initiators are preferably used in an amount of 0.01 to 20 parts by weight, especially 0.2 to 10 parts by weight, based on 100 parts by weight of the radically polymerizable monomer. Further, a polymerization initiator which does not give a positive or negative polymer terminal such as benzoyl peroxide or lauroyl peroxide may be used in combination.

Cationic polymerizable emulsifiers include synthetic compounds of alkyldimethylammonium chloride and an allyl ether compound, and anionic polymerizable emulsifiers include alkali salts of alkylallyl sulfosuccinate and vinyl sulfonic acid. There are alkali salts and the like. Of course, you may use together with another emulsifier. However, the emulsion polymer obtained by the so-called soap-free polymerization method polymerized using a polymerizable emulsifier or using no emulsifier at all,
It is particularly suitable for producing uniformly coated composite particles.

The inorganic particles used in the present invention include metal oxides such as silica, alumina, iron oxide, titanium oxide and zinc oxide, salts such as calcium carbonate, calcium oxalate and barium sulfate, and hydroxides such as magnesium hydroxide. Etc. are suitable. Therefore, it is suitable that these inorganic particles have an average particle size of 0.005 to 25 μm. In order to prepare a dispersion liquid of inorganic particles, the above-mentioned inorganic substance is crushed and dispersed in water or a non-aqueous solvent containing water by a known method such as three-roll, bevel mill, ultrasonic separation, or a colloid sol synthesis method. It may be synthesized by. In this way, a dispersion liquid of inorganic particles having a particle diameter in the range of 0.005 to 25 μm is obtained. The obtained dispersion is positively or negatively charged depending on the type of the inorganic substance, but in some cases, the ζ potential is changed by changing the pH, so that it changes to negative or positive. Such charges are provided by hydrogen ions, hydroxide ions, potential determining ions, or counterions having a high valence.

The electric charge strength of the emulsion particles and the inorganic powder can be measured as ζ potential. An example of producing the emulsion powder of the present invention will be described. For example, particles which are dispersed in water and are coated with inorganic particles such as colloidal silica particles having an average particle diameter of 0.02 μm are selected, and an acid is added and mixed by stirring to adjust pH. Adjust and charge negatively. next,
For example, emulsion-polymerized acrylic emulsion having an average particle size of 0.1 μm, which is positively charged at the same pH, is selected as a particle to be coated. In this case, N is 130, and thus the number of particles is 130 with respect to emulsion particles. × 0.5 = 65
If both dispersions are adjusted and mixed as described above and gently stirred for 10 minutes to 2 hours, the inorganic particles adhere to the synthetic resin emulsion particles extremely uniformly and firmly, and the synthetic resin emulsion particles are A dispersion is obtained which is uniformly coated with particles. When both dispersions are mixed, if an inorganic electrolyte such as potassium sulfate, magnesium chloride or aluminum chloride is added, more uniform and dense coating can be achieved. It is considered that this is because the inorganic electrolyte reduces the shadow effect of the inorganic particles, resulting in an increase in coverage.

Low glass transition temperature 20 ° C. used in the present invention
The following vinyl-based synthetic resin aqueous emulsion B, which is a re-emulsifiable powder, is obtained by emulsion-polymerizing a vinyl-based monomer with a water-soluble polymer compound as a protective colloid, or copolymerizing a hydrophilic unsaturated carboxylic acid or the like. Thus, the aqueous emulsion obtained by increasing the hydrophilicity of the vinyl synthetic resin particles in the vinyl synthetic resin aqueous emulsion is used. The vinyl-based monomer is not particularly limited, but examples thereof include polymers and copolymers of vinyl acetate, vinyl versatate, acrylic acid ester, methacrylic acid ester, styrene, vinyl chloride and the like. In particular, ethylene-vinyl acetate copolymer and vinyl acetate-vinyl versatate vinyl ester copolymer are preferable. When alkali resistance is required, acrylic acid ester,
Copolymers of methacrylic acid esters are preferred.

[0023]

【Example】

Production Example 1 Volume 2 equipped with stirrer, reflux condenser, dropping funnel, thermometer
In an L four-necked flask, 1512 g of water, 14 g of acrylamide, 168 g of dimethylformamide, 4 g of sodium chloride and 6 g of potassium persulfate were put, and after nitrogen substitution, 70
The temperature was raised to ° C and the polymerization reaction was performed for 1 hour. Then, 165 g of butyl acrylate and 115 g of methyl methacrylate are added, a polymerization reaction is performed at 70 ° C. for 4 hours, 14 g of diethylaminoethyl methacrylate is added, and a polymerization reaction is further performed for 1 hour to obtain a synthetic resin emulsion having an average particle diameter of 1.3 μm. It was

Production Example 2 In the four-necked flask used in Production Example 1, 1512 g of water, 14 g of acrylamide, 168 g of dimethylformamide, 4 g of sodium chloride and 6 g of potassium persulfate were placed, and after nitrogen substitution, the temperature was raised to 70 ° C. and polymerization was carried out for 1 hour. The reaction was carried out. Then, 280 g of styrene was added and the polymerization reaction was carried out at 70 ° C. for 4 hours, then 14 g of diethylaminoethyl methacrylate was added, and the polymerization reaction was carried out for another 1 hour to obtain an average particle diameter of 1.8 μm.
A synthetic resin emulsion of was obtained.

Example 1 The emulsion obtained in Production Example 1 was diluted to 10% with water and the pH was adjusted to 5 with hydrochloric acid. The diluted emulsion was positively charged. Separately, 1 of Snowtex O (silica sol manufactured by Nissan Chemical Industries, Ltd.) having an average particle diameter of 0.015 μm
The 0% dispersion was adjusted to pH 5. This Snowtex dispersion was negatively charged. 10 g of this dispersion was added to 100 g of the diluted emulsion and gently stirred,
A dispersion was obtained in which the emulsion particles were uniformly coated with silica sol particles. At this time, the particle number ratio R corresponds to about 100% of N. Observation with a scanning electron microscope confirmed that the surfaces of the emulsion particles were sufficiently uniformly covered with silica particles. 200 parts by weight of the above composite emulsion (20 parts by weight of solid content) An ethylene-vinyl acetate copolymer (glass transition point 0 ° C.) aqueous emulsion (solid content of 20% by weight) containing polyvinyl alcohol as a protective colloid in the solid content of the emulsion. Concentration 50%: Particle diameter 1 μm) 100 parts by weight (solid content 50 parts by weight) are uniformly mixed, and spray-dried under conditions of spray drying atmosphere temperature 100 ° C. and accumulated resin particle temperature 60 ° C. to be re-emulsifiable synthetic resin. An emulsion powder was obtained.

Example 2 The emulsion obtained in Production Example 2 was diluted to 10% with water and the pH was adjusted to 5 with hydrochloric acid. The diluted emulsion was positively charged. Separately, 1 of Snowtex O (silica sol manufactured by Nissan Chemical Industries, Ltd.) having an average particle diameter of 0.015 μm
The 0% dispersion was adjusted to pH 5. This Snowtex dispersion was negatively charged. 4.2 g of this dispersion was added to 100 g of the diluted emulsion and gently stirred to obtain a dispersion in which emulsion particles were uniformly coated with silica sol particles. At this time, the particle number ratio R is about 60% of N
Hit Observation with a scanning electron microscope confirmed that the surfaces of the emulsion particles were sufficiently uniformly covered with silica particles. 100 parts by weight of the above composite emulsion (solid content: 10 parts by weight) A water-based emulsion (solid content: ethylene-vinyl acetate copolymer (glass transition point: 0 ° C.)) containing polyvinyl alcohol as a protective colloid in an emulsion solid content of 10% by weight. Concentration 50%: Particle diameter 1 μm) 100 parts by weight (solid content 50 parts by weight) 50 parts by weight of water are uniformly mixed, and spray-dried again under conditions of a spray drying atmosphere temperature of 100 ° C. and a deposition resin particle temperature of 60 ° C. An emulsifiable synthetic resin emulsion powder was obtained.

Example 3 The emulsion obtained in Production Example 2 was diluted to 10% with water and the pH was adjusted to 5 with hydrochloric acid. The diluted emulsion was positively charged. Separately, 1 of Snowtex O (silica sol manufactured by Nissan Chemical Industries, Ltd.) having an average particle diameter of 0.015 μm
The 0% dispersion was adjusted to pH 5. This Snowtex dispersion was negatively charged. 8 g of this dispersion was added to 100 g of the diluted emulsion and gently stirred to obtain a dispersion in which emulsion particles were uniformly coated with silica sol particles. At this time, the particle number ratio R corresponds to about 125% of N. Observation with a scanning electron microscope confirmed that the surfaces of the emulsion particles were sufficiently uniformly covered with silica particles. The composite emulsion (A) polyvinyl alcohol as a protective colloid is added to the emulsion solids in an amount of 1
Ethylene-vinyl acetate copolymer containing 0% by weight (glass transition point 0 ° C.) aqueous emulsion (solid content concentration 50%:
(Particle size 1 μm) was diluted with water to 30% by weight (B)
(A) and (B) from separate nozzles (A) :( B) =
The mixture was sprayed at a ratio of 1: 1 and spray-dried under the conditions of a spray drying atmosphere temperature of 100 ° C. and a deposited resin particle temperature of 60 ° C. to obtain a re-emulsifiable synthetic resin emulsion.

Example 4 The emulsion obtained in Production Example 1 was diluted to 10% with water and the pH was adjusted to 5 with hydrochloric acid. The diluted emulsion was positively charged. Separately, 1 of Snowtex O (silica sol manufactured by Nissan Chemical Industries, Ltd.) having an average particle diameter of 0.015 μm
The 0% dispersion was adjusted to pH 5. This Snowtex dispersion was negatively charged. 10 g of this dispersion was added to 100 g of the diluted emulsion and gently stirred,
A dispersion was obtained in which the emulsion particles were uniformly coated with silica sol particles. At this time, the particle number ratio R corresponds to about 100% of N. Observation with a scanning electron microscope confirmed that the surfaces of the emulsion particles were sufficiently uniformly covered with silica particles. The above-mentioned composite emulsion (A) polyvinyl acetate-vinyl versatate (glass transition point 10 ° C.) aqueous emulsion containing polyvinyl alcohol as a protective colloid in an amount of 10% by weight in the solid content of the emulsion (solid content concentration 50%: particle diameter 1 μm). (B) (A) and (B) diluted with water to 30% by weight from separate nozzles (A):
(B) = 1: 1 spraying, spray drying atmosphere temperature 10
The re-emulsifiable synthetic resin emulsion was obtained by spray drying under conditions of 0 ° C. and a temperature of the deposited resin particles of 60 ° C.

Comparative Example 1 The emulsion obtained in Preparation Example 1 was diluted to 10% with water and the pH was adjusted to 5 with hydrochloric acid. (A) This diluted emulsion was positively charged. Separately, Snowtex O with an average particle diameter of 0.015 μm (Silica sol manufactured by Nissan Chemical Industries, Ltd.)
The pH of the 10% dispersion liquid of (1) was adjusted to (b), and this Snowtex dispersion liquid was negatively charged. Polyvinyl alcohol as protective colloid in emulsion solids 10
Ethylene-vinyl acetate copolymer (glass transition point 0 ° C.) aqueous emulsion containing 50% by weight (solid concentration 50%: particle size 1 μm) (B) (a) and (B) (a): (B)
= 2: 1 and mixed (a) and (B) mixed emulsion and (b) mixed emulsion: (b) = 90: 1
Spraying was carried out at a ratio of 0, and spray drying was carried out under the conditions of a spray drying atmosphere temperature of 100 ° C. and a deposited resin particle temperature of 60 ° C. The obtained product was blocked. The compositions of Examples and Comparative Examples are shown in Table 1.
And the results are also shown.

[0030]

[Table 1]

[Note] * 1 Powder state: It was observed whether a uniform powder was obtained. * 2 Blocking resistance: 200g at 50 ° C for 24 hours
After storing under a load of / cm ² , it was confirmed that the granules were easily disintegrated. * 3 Re-emulsification property: 100 parts by weight of powder was added to 100 parts by weight of water, and after sufficiently stirring with a stirrer, the state was allowed to stand and the state was observed, and the viscosity of the most emulsified liquid was measured. Numerical value: Viscosity (cps) of re-emulsified liquid x: Resin powder was settled without re-emulsification. It becomes an emulsion of.

[0032]

EFFECTS OF THE INVENTION According to the present invention, emulsion particles obtained by electrically adsorbing inorganic powder particles on the surface prevent blocking of emulsion particles emulsion-polymerized by using a protective colloid during spray drying, so that a good emulsion powder is obtained. You can Further, as a whole, there is an effect that the amount of the inorganic powder particles can be reduced. Further, since the emulsion using the protective colloid has no restriction on the surface charge, there is an advantage that many kinds of synthetic resins can be used.

Claims (6)

[Claims] 1. A. (A) a synthetic resin aqueous emulsion particle having a positive or negative charge on the particle surface and (b) an average radius of 1/2 or less of the average radius of the emulsion particle having a charge opposite to that of the emulsion particle, The dispersion of inorganic fine particles is (Where a is the average radius of the emulsion particles, b is the average radius of the inorganic particles, and R is the number of particles of the inorganic powder / the number of the emulsion particles), and the emulsion mixed with B. A vinyl-based aqueous synthetic resin emulsion obtained by polymerizing a water-soluble polymer as a protective colloid and / or a vinyl-based aqueous synthetic resin emulsion obtained by copolymerizing an unsaturated carboxylic acid, which is re-emulsifiable powder by spray drying. Blocking resistance obtained by uniformly mixing and spraying a vinyl-based synthetic resin aqueous emulsion having a point of 20 ° C. or less at a solid content ratio of A: B = 50 to 5 parts by weight: 50 to 95 parts by weight. Vinyl synthetic resin emulsion powder. 2. The A.I. Emulsion and B.I. Emulsion A: B = 50-5 parts by weight: 50-
Blocking-resistant vinyl-based synthetic resin emulsion powder obtained by separately spraying and mixing at a ratio of 95 parts by weight, and simultaneously drying. 3. The charged synthetic resin emulsion of (a) is either a cationic or anionic monomer, a polymerization initiator giving a positive or negative terminal, and a cationic or anionic polymerizable emulsifier. The blocking resistant vinyl synthetic resin emulsion powder according to claim 1 or 2, which is an emulsion obtained by emulsion polymerization using one or more selected from the above. 4. The emulsion polymerization according to claim 1, wherein the cationic monomer or the anionic monomer is used in an amount of 0.01 part by weight or more based on 100 parts by weight of the nonionic monomer, and emulsion polymerization is performed. Blocking-resistant vinyl synthetic resin emulsion powder. 5. A polymerization initiator which gives a positive or negative terminal is added in an amount of 0.01 to 20 relative to 100 parts by weight of the polymerizable monomer.
The blocking-resistant vinyl-based synthetic resin emulsion powder according to claim 1, which is emulsion-polymerized using parts by weight. 6. The charged inorganic powder fine particles of (b),
An inorganic powder, the charge of which is adjusted by adding an acid or an alkali to the aqueous dispersion to adjust the pH.
Blocking-resistant vinyl-based synthetic resin emulsion powder described in any one of 1.