JP2001040169A - Preparation of re-emulsifiable emulsion powder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a re-emulsifiable powder excellent in re-emulsifiability in water, capable of being dispersed as a primary particle and not exhibiting acidity by drying an aqueous emulsion obtained by subjecting a water-soluble polymer, which is obtained by copolymerization of an unsaturated amide compound with a monomer and gels at a specific temperature or above, to mixing with a vinylic synthetic resin emulsion or to copolymerization with a vinyl monomer. SOLUTION: An unsaturated amide compound is represented by the formula (wherein, R1 is H or methyl; R2 is H or ethyl; and R3 is ethyl or propyl), and N,-N-diethylacrylamide is exemplified. As a monomer to be copolymerized, is employed a hydrophilic monomer (e.g. acrylamide), an ionic monomer (e.g. acrylic acid) or a lipophilic monomer (e.g. N,N-diethylmethacrylamide). A gelation temperature is at least 30 deg.C. The water-soluble polymer is employed in an amount of 2-50 pts.wt. based on 100 pts.wt. of the solids constituents of a vinylic synthetic resin (e.g. polyvinyl acetate) emulsion. As the vinyl monomer is employed styrene or the like. The method for drying is spray drying or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a re-emulsifiable emulsion powder. The emulsion powder obtained by the production method of the present invention has excellent water re-emulsifiability, and is useful for applications such as adhesives, binders for paints, and cement admixtures.

[0002]

2. Description of the Related Art Generally, re-emulsifiable emulsion powders are produced by spray-drying and pulverizing a synthetic resin emulsion. Re-emulsifiable emulsion powders have the advantage that they are easy to handle because they are powders, and that they are easy to transport because they do not contain water. Such an emulsion powder can be redispersed in water by adding the powder to water and stirring, and can be used in the same manner as a synthetic resin emulsion, such as an adhesive, a binder for a paint, a binder for an aqueous ink, and a fiber finish. In addition, it is used for a wide range of applications, such as incorporation into cement such as concrete structure blocks, piles, mortars, and slate.

However, conventional re-emulsifiable emulsion powders are secondary particles having an average particle diameter of 15 μm or more (primary particles have an average particle diameter of 0.05 to 3 μm).
For example, JP-A-4-185606 discloses that a protective colloid-based acrylic emulsion (primary particles) having an average particle diameter of 20 to 100 nm (0.02 to 0.1 μm) is used as an anti-binding agent (silicic anhydride, aluminum silicate). And dried with a synthetic resin emulsion powder having an average particle diameter of 50 to 70 μm (2
Secondary particles). When this synthetic resin emulsion powder (secondary particles) is dispersed in water, it is dispersed as secondary particles, so that it does not become a stable emulsion, and the particles settle out after a while. In addition, a uniform film is not obtained. JP-A-59-193903 discloses that a monomer having a radical polymerizable unsaturated bond is emulsion-polymerized in the presence of a water-soluble copolymer of methacrylamide and an unsaturated carboxylic acid. A method for producing a powder composition in which the system is lowered to pH 4 or lower, the polymer is separated, dehydrated and dried. However, as described in Example 1 of the publication, the polymer after emulsion polymerization was treated with a G2 glass filter (40 to 50 μm).
As can be seen from the above, the powder obtained is secondary particles, and only a small part of the powder becomes primary particles during re-emulsification with water. Further, since the obtained powder is acidic, when used as an admixture for cement, the cement mixture may become neutral or acidic, which may cause corrosion of steel in concrete.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an excellent water re-emulsifiability, particles are dispersed as primary particles at the time of re-emulsification, and the obtained powder does not exhibit acidity. Useful for applications such as agents, adhesives, paint binders, fiber wall binders,
An object of the present invention is to provide a method for producing a re-emulsifiable emulsion powder which can be effectively used in various fields such as a sand wall binder.

[0005]

Means for Solving the Problems As a result of intensive studies, the present inventors were able to solve the above-mentioned conventional problems. That is, the present invention has the following general formula:

[0006]

Embedded image

(Where R¹Is a hydrogen or methyl group
R^TwoIs hydrogen or an ethyl group; ^ThreeIs an ethyl group
Or a propyl group;¹Is hydrogen, R^TwoIs
Hydrogen and R^ThreeIs a propyl group or R¹
Is hydrogen, R^TwoAnd R^ThreeBoth are ethyl groups; R¹
Is a methyl group,^TwoIs hydrogen and R^ThreeIs propyl
And at least one unsaturated amide compound represented by the formula:
Temperature 30 consisting of a copolymer with other copolymerizable monomers
Water-soluble polymer that gels above ℃ and vinyl synthetic resin
Fat emulsion or mixed with vinyl monomer
To give an aqueous emulsion, followed by the aqueous emulsion
Re-emulsifiable emulsion characterized by drying the emulsion
The present invention provides a method for producing a solution powder.

The present invention also relates to a water-soluble polymer 2 to 100 parts by weight of a solid content of a vinyl-based synthetic resin emulsion.
It is intended to provide the above-mentioned production method using 50 parts by weight.

Further, the present invention provides the above-mentioned production method, wherein an anti-binder containing fine inorganic powder as a main component is dried together with an aqueous emulsion in a drying step.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention, in the drying step of an aqueous emulsion, the surface of the primary particles of the vinyl-based synthetic resin is gelled before the water evaporates. (Copolymer). Then, when the water evaporates, it becomes apparently a dried emulsion powder of secondary particles of 15 μm or more. When the emulsion powder of the secondary particles is redispersed in water, the gelled substance covering the surface of the primary particles is removed. Below the gel point, the polymer becomes a water-soluble polymer, and thus becomes an original emulsion (primary particles). The water-soluble polymer (thermosensitive copolymer) which gels at a temperature of 30 ° C. or more used in the present invention is represented by the following general formula:

[0011]

Embedded image

(Where R¹Is a hydrogen or methyl group
R^TwoIs hydrogen or an ethyl group; ^ThreeIs an ethyl group
Or a propyl group;¹Is hydrogen, R^TwoIs
Hydrogen and R^ThreeIs a propyl group or R¹
Is hydrogen, R^TwoAnd R^ThreeBoth are ethyl groups; R¹
Is a methyl group,^TwoIs hydrogen and R^ThreeIs propyl
And at least one unsaturated amide compound represented by the formula:
It is a copolymer with another copolymerizable monomer.

The unsaturated amide compound represented by the above general formula includes N, N-diethylacrylamide, Nn-
Propylacrylamide, N-isopropylacrylamide, Nn-propylmethacrylamide, N-isopropylmethacrylamide are exemplified. Among them, N, N-diethylacrylamide and N-isopropylacrylamide are preferred. If necessary, two or more kinds of the unsaturated amide compounds can be used simultaneously.

On the other hand, the monomer copolymerizable with at least one of the unsaturated amide compounds represented by the above-mentioned general formula includes hydrophilic monomers, ionic monomers and lipophilic monomers. Species or more. Examples of the above hydrophilic monomer, in other words, a hydrophilic monomer that does not insolubilize (gel) the homopolymer in an aqueous solution by heating, include, for example, acrylamide, methacrylamide, N-methylacrylamide, N, N- Dimethyl acrylamide, N, N-dimethyl methacrylamide, N-ethyl acrylamide, diacetone acrylamide, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, various methoxypolyethylene glycol methacrylates, various methoxypolyethylene glycol acrylates, N-vinyl-
2-pyrrolidone and the like can be mentioned. In addition, vinyl acetate, glycidyl methacrylate, or the like can be introduced by copolymerization and hydrolyzed to impart hydrophilicity.

Examples of the ionic monomer include acrylic acid, methacrylic acid, vinyl sulfonic acid, allyl sulfonic acid, metharyl sulfonic acid, styrene sulfonic acid,
Acrylamide-2-phenylpropanesulfonic acid, 2
Acids such as acrylamide-2-methylpropanesulfonic acid and salts thereof, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl Acrylate, N,
N-dimethylaminopropyl methacrylamide, N, N
Amides such as dimethylaminopropylacrylamide and salts thereof. In addition, various acrylates, methacrylates, acrylamides, methacrylamides, acrylonitriles, and the like can be introduced by copolymerization and hydrolyzed to impart ionicity.

On the other hand, examples of the lipophilic monomer, in other words, the lipophilic monomer in which the homopolymer is insoluble (gelled) in water, include, for example, N, N-diethyl methacrylamide, N, N
N-di-n-propylacrylamide, Nn-butylacrylamide, Nn-butylmethacrylamide, N
-Tert-butylacrylamide, N-tert-butylmethacrylamide, Nn-hexylacrylamide, N-
n-hexyl methacrylamide, Nn-octyl acrylamide, Nn-octyl methacrylamide, N-
N such as tert-octylacrylamide, Nn-dodecylacrylamide, Nn-dodecylmethacrylamide, etc.
-Alkyl (meth) acrylamide derivatives, ethyl acrylate, methyl acrylate, butyl acrylate,
Examples thereof include (meth) acrylate derivatives such as butyl methacrylate, lauryl acrylate, 2-ethylhexyl methacrylate, and glycidyl methacrylate, acrylonitrile, vinyl acetate, vinyl chloride, styrene, and α-methylstyrene.

The proportion of the unsaturated amide compound represented by the above general formula and other copolymerizable monomers varies depending on the monomers to be copolymerized, but is adjusted so that the gelling temperature is 30 ° C. to 100 ° C. Is good. Preferably, 30 ° C to 80 ° C is good.

In the present invention, the vinyl-based synthetic resin to be mixed is not particularly limited. For example, polyvinyl acetate, poly (meth) acrylate, polystyrene, vinyl acetate-ethylene copolymer, vinyl acetate- ( Examples include (meth) acrylate copolymers, styrene- (meth) acrylate copolymers, vinyl acetate-vinyl versatate copolymers, and vinyl acetate-ethylene-vinyl versatate terpolymers. Specific examples of the vinyl monomer to be polymerized include, for example, acrylates; methyl-, ethyl-, isopropyl-, n-butyl-, isobutyl-,
n-amyl-, isoamyl-, n-hexyl-, 2-ethylhexyl-, octyl-, decyl-, dodecyl-,
Methacrylic esters such as octadecyl-, cyclohexyl-, phenyl-, benzyl-, 2-hydroxyethyl- and hydroxypropyl-acrylate; methyl-, ethyl-, isopropyl-, n-butyl-, isobutyl-, n-amyl- , Isoamyl-, n-hexyl-, 2-ethylhexyl-, octyl-, decyl-, dodecyl-, octadecyl-, cyclohexyl-, phenyl-, benzyl-, 2-hydroxyethyl-, hydroxypropyl-methacrylate, etc. 1 atom
To 12 alkyl acrylates, other methacrylates having 1 to 12 carbon atoms, 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, acrylonitrile, methacrylonitrile, glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, unsaturated carboxylic acids Amino group-containing monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, acrylic acid anhydride, methacrylic anhydride, maleic anhydride, itaconic anhydride, fumaric anhydride;
-Methylaminoethyl acrylate, N-methylaminoethyl methacrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, etc .; aromatic vinyls; styrene, 2-methylstyrene, t-butylstyrene, chlorostyrene, vinylanisole, vinylnaphthalene Vinyl acetate, vinyl propionate, vinyl esters of fatty acids (eg, VeoVa of Shell Chemical Co., Ltd.), vinyl halides; vinyl chloride, vinylidene halides; vinylidene chloride, fluoride Olefins such as vinylidene; ethylene, propylene, dienes; isoprene, butadiene, chloroprene, and others; vinylpyrrolidone,
Acrylonitrile, methacrylonitrile, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, neopentyl glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,6-hexane Diol dimethacrylate, neopentyl glycol dimethacrylate, polyethylene glycol diacrylate, 1,6-
Hexanediol diacrylate, neopentyl glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate,
Trimethylolpropane trimethacrylate, tetramethylolmethane triacrylate, tetramethylolmethanetetraacrylate, allyl methacrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, isopropenyl-α, α-dimethylbenzyl isocyanate, allyl mercaptan,
Amides: acrylamide, methacrylamide, N-methylol methacrylamide, N-methylol acrylamide, diacetone acrylamide, maleic amide, etc., and can be used alone or in combination of two or more. Among them, preferred are aromatic vinyl compounds, dienes, olefins, (meth) acrylates, and vinyl esters, and specifically, styrene, butyl acrylate, 2-ethylhexyl acrylate,
Butadiene, methyl methacrylate, vinyl acetate, vinyl esters of fatty acids (eg VeoV of Shell Chemical Co., Ltd.)
a), ethylene and the like. When compounding with cement,
Monomers having excellent alkali resistance are preferred.

The drying step in the present invention is not particularly limited. Preferably, it is spray dried. The drying temperature may be appropriately determined depending on the material used, and is, for example, about 50 to 150 ° C.

The ratio of the water-soluble polymer (temperature-sensitive copolymer) to the vinyl-based synthetic resin is 2 to 100 parts by weight of the solid content of the vinyl-based synthetic resin. It is preferred to use 50 parts by weight. If the amount is less than 2 parts by weight, particles having a particle size of 1 μm or more at the time of re-emulsification with water will increase. Also,
If the amount exceeds 50 parts by weight, the water resistance of the film after film formation becomes poor. Preferably it is 5 to 40 parts by weight.

In the drying, for example, spray drying, an anti-binder may be used in combination. In this case, as the anti-binder, fine inorganic powders are preferable, and calcium carbonate, clay,
Silicic anhydride, aluminum silicate, white carbon, talc, alumina white, and the like are used. Silicic anhydride, aluminum silicate, calcium carbonate, and the like having an average particle diameter of about 0.01 to 0.5 μm are particularly preferable. The amount of the anti-binder used is not particularly limited, but is preferably used in a range of 20% by weight or less based on the emulsion powder to be produced. 2
If the content exceeds 0% by weight, the content of the inorganic powder becomes too large, and the characteristics of the emulsion powder are lost. The anti-binder may be added to the emulsion powder after drying and uniformly mixed.However, when the aqueous emulsion is dried, spraying the aqueous emulsion in the presence of the anti-binder results in uniform mixing. It can be carried out and is effective from the viewpoint of preventing caking. It is particularly preferable to spray and dry both at the same time.

[0022]

The present invention will be further described below with reference to examples and comparative examples. Synthesis Example 1 513.6 g of distilled water, 20 g of Nn-propylacrylamide and 16 g of 40% acrylamide were added to a 1500 ml four-necked round-bottomed flask while stirring under a nitrogen gas flow. Thereafter, 2.8 g of ammonium persulfate and 1.2 g of sodium bisulfite were added, and the mixture was synthesized at 10 ° C. for 3.5 hours. The obtained aqueous solution of the temperature-sensitive copolymer was filled with an inner diameter of 15 m.
m, into which a standard thermometer was inserted, and the mixture was gradually heated while stirring with a thermometer in a constant temperature water. At 63 ° C., cloudiness (gelation) started, and at 70 ° C., the mercury bulb of the thermometer became invisible. Even when this aqueous solution was further heated, the aqueous solution maintained a stable cloudy (gelled) state.

Example 1 199 g of the aqueous solution of the temperature-sensitive copolymer obtained in Synthesis Example 1 was
Vinyl acetate-ethylene copolymer emulsion using polyvinyl alcohol as a protective colloid (vinyl acetate content 83
Wt%, ethylene content 17 wt%, average particle size 0.8
μm, 10% concentration). This mixed emulsion was sprayed into hot air at 120 ° C. and dried to obtain a resin powder. When this resin powder was re-emulsified in water, primary particles having an average particle diameter of 1 μm or less were obtained. When the stability of the obtained emulsion after 24 hours was examined, it was confirmed that the emulsion was good. Table 1 shows the results.

Synthesis Example 2 Synthetic Example 1 was completely the same as Synthetic Example 1 except that 24.5 g of Nn-propylacrylamide was used and 1.9 g of sodium 2-acrylamido-2-phenylpropanesulfonate was used instead of acrylamide. Synthesized similarly. At this time, the onset temperature of the turbidity (gelation) of the gelling agent is 3
6 ° C. and the cloudiness (gelling) temperature is 59 ° C.

Example 2 The same experiment as in Example 1 was conducted using the aqueous solution of the temperature-sensitive copolymer obtained in Synthesis Example 2. Table 1 shows the results.

Example 3 In Example 1, Nn-propylacrylamide.
The same experiment as in Example 1 was performed using 207 g of a 5% aqueous solution of N, N-diethylacrylamide instead of the acrylamide copolymer. Table 1 shows the results.

Example 4 The same experiment as in Example 1 was performed, except that 414 g of a 5% aqueous solution of a thermosensitive resin was used in Example 3. Table 1 shows the results.

Example 5 In Example 1, 200 g of N, N-diethylacrylamide and 250 g of 40% acrylamide were used instead of Nn-propylacrylamide, and 400 g of distilled water and 5.3% of tert-butylhydroxylamide were used. Same as Example 1 except that 75 g of a peroxide aqueous solution and 75 g of a 5.3% Rongalite aqueous solution were used, and each was uniformly added at 30 ° C. for 3.5 hours, and the obtained temperature-sensitive copolymer aqueous solution was used. Was conducted. Table 1 shows the results.

Example 6 The mixed emulsion used in Example 5 and the silicic acid fine powder in an amount of 10% by weight based on the solid content of the emulsion were separately sprayed simultaneously in hot air at 120 ° C. and dried. The same experiment as in Example 1 was performed except that powder was obtained. Table 1 shows the results.

Example 7 In a 1 liter pressurized reactor equipped with a stirrer, several feed ports, cooling and heating equipment, a pressure gauge and a thermometer,
32 parts of the aqueous solution of the temperature-sensitive copolymer obtained in Example 4 was 365.
After dissolving and charging in 6 parts of water, 1.2 parts of Rongalite was further added to the pressurized reactor, the inside of the pressurized reactor was pressurized to 50 kg / cm ² with ethylene, and the temperature was raised to 60 ° C. When the temperature of the pressure reactor reached 60 ° C., 80 parts of a 0.44% hydrogen peroxide solution and 320 parts of vinyl acetate were uniformly added into the pressure reactor over 3 hours. Thereafter, the mixture was aged at 60 ° C. for 2 hours to obtain a vinyl acetate / ethylene copolymer emulsion using a temperature-sensitive copolymer resin as a protective colloid. The gelation temperature of this emulsion was 52 ° C. This emulsion and fine silica powder in an amount of 10% by weight based on the solid content of the emulsion were separately sprayed simultaneously in hot air at 120 ° C. and dried to obtain a resin powder. When this resin powder was re-emulsified in water, primary particles having an average particle size of 1.0 μm were obtained. Table 1 shows the results.

COMPARATIVE EXAMPLE 1 A vinyl acetate / ethylene copolymer emulsion not using a temperature-sensitive copolymer resin as a protective colloid, and a silicic anhydride fine powder in an amount of 10% by weight based on the solid content thereof were separately prepared at 120 ° C. Simultaneous spraying in hot air and drying, 2 particles with an average particle size of 20 μm
Secondary particles were obtained. This was dispersed in water, but did not become an emulsion of the primary particles and settled out after 2 hours. Table 2 shows the results.

Comparative Example 2 Colloidal silica in an amount of 10% by weight (solid content) based on the solid content was added to the vinyl acetate / ethylene copolymer emulsion used in Comparative Example 1, and sprayed in hot air at 120 ° C. It dried and became a large agglomerate. Further, water re-emulsifiability was not obtained. Table 2 shows the results.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

According to the present invention, water re-emulsifiability is excellent, particles are dispersed as primary particles at the time of re-emulsification, and the obtained powder does not exhibit acidity. There is provided a method for producing a re-emulsifiable emulsion powder which is useful and can be effectively used in various fields such as an adhesive, a paint binder, a fiber wall binder and a sand wall binder.

Continued on the front page F-term (reference) 4F070 AA17 AA18 AA19 AA20 AA22 AA23 AA28 AA29 AA32 AA36 AA37 AA40 AB13 AC11 AC15 AC16 AC22 AE30 DA34 DB07 DC05 DC11 DC12 DC13 4J002 AA01X BC07X BC12W BF02W BG03W04BG03W BG02W EB026 EF076 EF126 EH036 EH076 EL036 EL146 EP016 ER006 ET006 FD206 HA07 HA09

Claims (3)

[Claims] [Claim 1] The following general formula:(Where R¹Is hydrogen or a methyl group;^TwoIs hydrogen
Or an ethyl group, and R ^ThreeIs an ethyl or propyl group
Where R¹Is hydrogen, R^TwoIs hydrogen and
R^ThreeIs a propyl group or R¹Is hydrogen
R^TwoAnd R^ThreeBoth are ethyl groups; R¹Is a methyl group
If R^TwoIs hydrogen and R^ThreeIs a propyl group)
Copolymerizable with one or more unsaturated amide compounds
Gelation at a temperature of 30 ° C or higher consisting of a copolymer with a monomer
Water-soluble polymer and vinyl-based synthetic resin emulsion
With water or polymerize with vinyl monomer to form an aqueous emulsion.
To obtain the emulsion and subsequently drying the aqueous emulsion
Production of re-emulsifiable emulsion powder characterized by the following:
Method. 2. The method according to claim 1, wherein the water-soluble polymer is used in an amount of 2 to 50 parts by weight based on 100 parts by weight of the solid content of the vinyl synthetic resin emulsion. 3. The production method according to claim 1, wherein an anti-binder containing fine-grain inorganic powder as a main component is also dried together with the aqueous emulsion during the drying step.