JPH11292978A - Production of resin powder and resin powder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently producing a resin powder excellent in water redispersibility and useful as a film surface-treating agent or the like while preventing fusion of particles with each other and adhesion of the resin to a wall surface of a drying room by drying a synthetic resin aqueous emulsion by a pulse shock wave dryer. SOLUTION: A synthetic resin aqueous emulsion [e.g. the one containing 1-30 wt.% protection colloid which is a formalin-condensate of a polyvinyl alcohol or a melaminesulfonic acid salt in the solid amount of the resin and obtained by emulsion polymerization, concretely an aqueous emulsion of an acrylic (styrene) resin, a vinyl acetate resin or an ethylene-vinyl acetate resin, a styrene-butadiene rubber latex or the like] is dried by a pulse shock wave dryer, preferably while controlling the temperature in the drying room so as to be 40-80 deg.C to dry and powder the emulsion, in the method for producing a resin powder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for producing a resin powder having no fusion of powder resin particles, no adhesion to a wall surface, and excellent water redispersibility. The present invention relates to a method for producing a resin powder by drying an emulsion with a pulse shock wave dryer.

[0002]

2. Description of the Related Art In recent years, as measures for protecting the global environment, synthetic resins used for coating materials and various additives have been developed.
From the viewpoints of pollution-free, resource saving, workability, and the like, there is a shift from solvent-based resins to aqueous dispersions of synthetic resins such as water-dispersible resins and water-soluble resins. Of these synthetic resin aqueous dispersions, those powdered resins that are easily dispersed in water by adding water and stirring and mixing are called water redispersible resin powders. Since this water redispersible resin powder is added immediately before use, it has lower transport costs, is easier to package and is easier to transport, has better storage stability and is less likely to freeze than conventional synthetic resin aqueous dispersions. No, it is easy to dispose of the packaging container after use.

[0003] Usually, the water-redispersible resin powder is produced by dry-pulverizing an aqueous synthetic resin emulsion (hence the name of the water-redispersible resin powder). There are various drying resin powdering methods, for example, a spray drying method, a freeze drying method, a reduced pressure drying method and the like. In general, from the viewpoint of productivity and the like, a synthetic resin aqueous emulsion is spray-dispersed in hot air and conveyed by the hot air. The spray drying method of rapidly drying to obtain a powder while being dried is widely used. The spray drying method is characterized in that moisture is evaporated by hot air to dry it. If the hot air temperature of the spray drying device is lowered (100 ° C. or less), the evaporation efficiency of moisture is reduced and productivity is remarkably deteriorated. For this purpose, the hot air temperature should be at least 100 ° C (preferably 12 ° C).
0 ° C.) or higher. Therefore, this method has disadvantages such as that a resin having a low glass transition temperature easily adheres to the wall surface of the drying chamber and powder cannot be obtained, and properties such as water redispersibility are extremely poor due to melting and fusion of resin particles. Was.

As a method for preventing such fusion of resin particles due to heat during spray drying, a method of adding a water-soluble natural or synthetic polymer compound called a protective colloid is known. For example, Japanese Patent Publication No. 46-12907 proposes a method in which polyvinyl alcohol is added as a protective colloid to an aqueous synthetic resin emulsion, followed by spray drying. Also, a method using a formalin condensate of melamine sulfonate as a protective colloid (Patent No. 2)
666406), a number of methods for adding a water-soluble polymer such as polyvinylpyrrolidone, a cellulose derivative, and polyacrylic acid, followed by drying have been proposed. However, since it is necessary to add a large amount of these water-soluble polymers in order to prevent fusion between resin particles and to exhibit good water redispersibility, the properties of the original synthetic resin aqueous emulsion are impaired, In particular, it had the disadvantage that the water resistance was poor.

Further, JP-A-5-194681 and JP-A-7-187741 disclose a polymer having a core-shell particle structure comprising a shell of an alkali-soluble emulsion polymer and a core of a water-insoluble emulsion polymer. Although a method for producing a coalesced powder has been proposed, even a polymer powder having such a specific particle structure has a disadvantage that it is difficult to powder a polymer having a particularly low glass transition temperature.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for efficiently drying a synthetic resin aqueous emulsion which does not adhere resin particles and which does not adhere to the wall of a drying chamber to produce a resin powder, and a method for reusing water. An object of the present invention is to provide a resin powder having excellent dispersibility.

[0007]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, the synthetic resin aqueous emulsion was dried with a pulse shock wave drying device to fuse the resin particles or to form a drying chamber. The present inventors have found that a resin powder having little resin adhesion to the wall surface and good redispersibility in water can be obtained, and the present invention has been completed.

That is, the present invention provides a method for producing a resin powder characterized in that a synthetic resin aqueous emulsion is dried with a pulse shock wave drying device to obtain a powdered resin. To 80 ° C., preferably the aqueous synthetic resin emulsion contains 1 to 30% by weight of the resin solid content of at least one kind of protective colloid selected from polyvinyl alcohol or a formalin condensate of melamine sulfonate. Preferably, the synthetic resin aqueous emulsion is produced by emulsion polymerization, so-called acrylic (styrene) synthetic resin aqueous emulsion, vinyl acetate synthetic resin aqueous emulsion, ethylene vinyl acetate synthetic resin aqueous emulsion and SBR
And a resin powder obtained by the method for producing the resin powder. Hereinafter, the present invention will be described in detail.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The pulse shock wave drying device used in the present invention is a drying device described in, for example, Japanese Patent Publication No. 6-33939 or U.S. Pat. No. 4,708,159. A drying device characterized by the above-mentioned.

The apparatus includes a metering pump device for supplying a material to be dried into the dryer, a pulse combustor device as a heat source,
Atomizer (sprayer) device, compressor device for (secondary) air supplied to cool combustion gas, drying room device for drying the material to be dried, cyclone device for collecting dry powder, back filter device, etc. It is also possible to equip an ancillary device that suppresses the adhesion of the dried material to the wall surface by blowing dry air on the wall surface, for example, called an air sweeper, if necessary. It is also possible to equip a device for introducing cooling cold air into a drying room or the like for further lowering the room temperature.

The pulse combustor device is a combustor device having extremely high combustion efficiency by pulsatingly exploding (generating a pulse) several tens to thousands of times per second in a combustor, and merely generating heat. In addition, pulse shock waves (sound waves, pressure waves) can be generated. This pulse shock wave impacts the air layer around the object to be dried, thereby drawing out the internal moisture to the surface, and water evaporates instantaneously on the surface due to thermal energy. Thus the pulse shock wave,
Drying with a pulse combustor that can combine the functions of sound waves, pressure waves, and heat energy can be dried and powdered instantaneously and efficiently at a lower temperature than conventional spray drying methods that rely only on heat energy. is there.

The synthetic resin aqueous emulsion of the present invention is:
It is a synthetic resin aqueous dispersion obtained by subjecting a group of polymerizable unsaturated monomers to emulsion polymerization in water. The resin solids content is preferably 20-70% by weight.

The synthetic resin aqueous emulsion of the present invention is not particularly limited, and known and commonly used resins produced by emulsion polymerization can be used. So-called acrylic (styrene) synthetic resin aqueous emulsion, vinyl acetate synthetic resin aqueous Examples include emulsions, aqueous emulsions of ethylene-vinyl acetate synthetic resins, and latexes such as SBR. Needless to say, a resin obtained by compounding an aqueous resin other than the synthetic resin aqueous emulsion by a known method such as blending or forming composite particles can also be used.

The method for producing the synthetic resin aqueous emulsion used in the present invention is not particularly limited, and it can be produced by a known and commonly used method. For example, a method of dropping a polymerizable unsaturated monomer group into an aqueous phase containing an emulsifier, a method of polymerizing with a polymerization initiator, a method of preparing an aqueous dispersion of a polymerizable unsaturated monomer with an emulsifier or the like in advance and a polymerization initiator A method of using a synthetic or natural water-soluble polymer in place of the emulsifier, pre-polymerizing a group of polymerizable unsaturated monomers containing a carboxylic acid group, neutralizing the acid group, and then polymerizing the remaining polymer. And a so-called soap-free emulsion polymerization method for polymerizing a group of unsaturated monomers. Further, for example, JP-A-5-194681 and JP-A-7-18
The method for producing an emulsion having a core-shell particle structure described in JP-A-7741 can also be used.

The polymerizable unsaturated monomer having a hydrophilic functional group among the polymerizable unsaturated monomers used in the present invention has both a polymerizable unsaturated group and a hydrophilic group in one molecule. Although it is not particularly limited as long as it is a compound, for example, (meth) acrylic acid, itaconic acid, maleic acid or its monoester, fumaric acid or its monoester,
Itaconic acid or its monoester, crotonic acid, p-
Carboxylic acid group-containing polymerizable unsaturated monomers such as vinylbenzoic acid and salts thereof; 2- (meth) acrylamide-
2-methylpropanesulfonic acid, vinylsulfonic acid, styrenesulfonic acid, (meth) allylsulfonic acid, sulfoethyl (meth) acrylate, sulfopropyl (meth)
Sulfonic acid group-containing polymerizable unsaturated monomers such as acrylates and salts thereof; dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, vinylpyrrolidone, N-methylvinylpyridium chloride, (meth) allyltriethyl Examples include tertiary or quaternary amino group-containing polymerizable unsaturated monomers such as ammonium chloride and 2-hydroxy-3- (meth) acryloxypropyltrimethylammonium chloride. These hydrophilic functional group-containing polymerizable unsaturated monomers may be used alone or in combination of two or more.

The auxiliary polymerizable unsaturated monomer having a hydrophilic functional group other than the above polymerizable unsaturated monomer having a hydrophilic functional group includes, for example, hydroxyethyl (meth) acrylate, hydroxypropyl Examples include hydroxyl group-containing polymerizable unsaturated monomers such as (meth) acrylate and polyethylene glycol mono (meth) acrylate, and amide group-containing polymerizable unsaturated monomers such as (meth) acrylamide and n-methylol (meth) acrylamide. It can be used to improve the water redispersibility of the water redispersible resin powder.

Other polymerizable unsaturated monomers other than those described above include:
The compound is not particularly limited as long as it is a compound having a polymerizable unsaturated group in the molecule. For example, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth)
(Meth) such as acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, lauryl (meth) acrylate, and stearyl (meth) acrylate Acrylic unsaturated monomers such as acrylic esters; diesters of unsaturated dibasic acids such as maleic acid, fumaric acid, itaconic acid, styrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, chloromethyl Aromatic unsaturated monomers such as styrene and vinyl toluene, nitrile unsaturated monomers such as acrylonitrile and methacrylonitrile, conjugated diolefin unsaturated monomers such as butadiene and isoprene, divinylbenzene, ethylene glycol diacrylate , Ethi Glycol dimethacrylate, diethylene glycol dimethacrylate, allyl methacrylate, diallyl phthalate, trimethylolpropane triacrylate, glycerin diallyl ether, polyethylene glycol dimethacrylate, polyfunctional unsaturated monomers such as polyethylene glycol diacrylate, ethylene, propylene, Vinyl unsaturated monomers such as isobutylene and the like; vinyl acetate unsaturated monomers such as vinyl acetate, vinyl propionate, octyl vinyl ester, veova 9, veova 10, and veova 11 (veova: trademark of Shell Chemical Company); Vinyl ether unsaturated monomers such as ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, and cyclohexyl vinyl ether; allyl ethers such as ethyl allyl ether Unsaturated monomers, vinyl chloride, vinyl bromide, vinylidene chloride, vinylidene fluoride, chlorotrifluoroethylene, tetrafluoroethylene, hexafluoropropylene, pentafluoropropylene, perfluoro (propyl vinyl ether), perfluoroalkyl acrylate, Examples include halogen-containing unsaturated monomers such as perfluoroalkyl methacrylate.

Examples of other polymerizable unsaturated monomers having a reactive functional group include epoxy group-containing unsaturated monomers such as glycidyl (meth) acrylate and glycidyl methacrylate, vinyltrichlorosilane, vinyltrichlorosilane, and the like. Vinylsilane unsaturated monomers such as ethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, acrolein, diacetoneacrylamide, vinylmethylketone, vinylbutylketone, diacetoneacrylate, acetonitrileacrylate And carbonyl group-containing unsaturated monomers such as acetoacetoxyethyl (meth) acrylate, vinyl acetophenone and vinyl benzophenone.

If necessary, the polymerizable unsaturated monomer 10
A surfactant (emulsifier) can be used in an amount of 0 to 20 parts by weight with respect to 0 parts by weight. To exemplify representative emulsifiers, for example, alkyl sulfates, alkane sulfonates, alkyl benzene sulfonates, alkyl aryl polyether sulfates,
(Di) Anionic emulsifiers such as alkyl sulfosuccinates, polyoxyethylene alkyl sulfates, polyoxyethylene alkyl phenyl sulfates, etc .: Polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene-polyoxypropylene block Nonionic emulsifiers such as polymers: cetyltrimethylammonium bromide,
Cationic emulsifiers such as lauryl pyridinium chloride: (meth) acrylic acid polyoxyethylene ammonium sulfate, (meth) acrylic acid polyoxyethylene sodium sulfonate, polyoxyethylene alkenyl phenyl sulfonate ammonium, polyoxyethylene alkenyl phenyl sodium sulfate, Sodium allyl alkyl sulfosuccinate, sodium (meth) acrylate polyoxypropylene sulfonate, 2-hydroxyethyl (meth)
Anionic reactive emulsifiers such as acryloyl phosphate: polyoxyethylene alkenyl phenyl ether,
Nonionic reactive emulsifiers such as polyoxyethylene (meth) acryloyl ether: generally commercially available reactive emulsifiers, for example, Aqualon HS-10, New Frontier A-229E (all manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Adecaria Soap SE-3N, SE-5N, SE-10
N, SE-20N, SE-30N (all manufactured by Asahi Denka Kogyo Co., Ltd.), Antox MS-60, MS-2N, RA
-1120, RA-2614 (Nippon Emulsifier Co., Ltd.)
), Eleminol JS-2, RS-30 (all manufactured by Sanyo Chemical Industries, Ltd.), Latemul S-120A, S-180
A, S-180 (all manufactured by Kao Corporation) and other anionic reactive emulsifiers, Aqualon RN-20, RN-30, RN
-50, New Frontier N-177E (all manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Adecaria Soap NE-10, NE
-20, NE-30, NE-40 (all manufactured by Asahi Denka Kogyo KK), RMA-564, RMA-568, RMA
-1114 (all manufactured by Nippon Emulsifier Co., Ltd.), NK ester M-20G, M-40G, M-90G, M-230G
(Made by Shin-Nakamura Chemical Co., Ltd.) and the like.

Of these emulsifiers, anionic and cationic reactive emulsifiers can be used as the above-mentioned unsaturated monomers containing a hydrophilic group. Of course, commercially available emulsifiers other than these can also be used, and two or more of these can be used in combination.

Other dispersion stabilizers other than emulsifiers include, for example, polyvinyl alcohol and its derivatives (eg, polyvinyl alcohol having a mercapto group), cellulose and its derivatives, starch and its derivatives, styrene maleic acid resin, maleated polybutadiene. And synthetic or natural water-soluble polymers such as maleic alkyd resin, polyacrylic acid (salt), polyacrylamide, water-soluble acrylic resin, formalin condensate of melamine sulfonate, and polyvinylpyrrolidone. Alternatively, a mixture of two or more can be used. Among them, polyvinyl alcohol and its derivatives (for example, polyvinyl alcohol having a mercapto group, etc.) and formalin condensate of melamine sulfonate are preferable because re-dispersibility in water of dried resin powder and water resistance can be obtained. These dispersion stabilizers are described in, for example, Japanese Patent Publication No. 1-57066 and JP-A-6-1284.
No. 43, it may be used as a dispersion stabilizer during polymerization, or may be added to an aqueous synthetic resin emulsion by a method such as post-adding an aqueous solution of these dispersion stabilizers to an aqueous synthetic resin emulsion. it can.

The polymerization initiator is not particularly limited. For example, various polymerization initiators such as azo compounds and organic peroxides, and electromagnetic waves such as ultraviolet rays can be used. Specifically, potassium persulfate, ammonium persulfate, sodium persulfate, hydrogen peroxide, azobisisobutyronitrile and its hydrochloride, cumene hydroperoxide,
tert-butyl hydroperoxide and the like. Further, a known redox initiator using a combination of these persulfates or peroxides, metal ions such as iron ions, and reducing agents such as sodium sulfoxylate formaldehyde, sodium sulfite, and L-ascorbic acid is also used. be able to.

The reaction temperature is not particularly limited, and may be in a temperature range sufficient to cause the polymerization initiator described in the preceding section to be efficiently decomposed or dissociated and to cause a polymerization reaction. A polymerization reaction takes place.

The synthetic resin aqueous emulsion of the present invention is introduced into a pulse shock wave drying device by a synthetic resin aqueous emulsion transport pump such as a rotary pump, a diaphragm pump, and a vane pump, and a pressure nozzle is provided near a combustion gas outlet of a pulse combustor. The droplets are usually made into fine droplets of 0.1 to 100 μm by an atomizer (sprayer) device such as a two-fluid nozzle or a rotating disk atomizer, and dried and powdered by a pulse combustion wave.

The bulk density or particle size of the obtained resin powder can be appropriately adjusted depending on the form of the atomizer, the pressure and the rotation speed, the concentration and the viscosity of the supplied synthetic resin aqueous emulsion, and the like. The particle size of the resin powder is preferably 0.1 μm or more from the viewpoint of handling of the obtained resin powder.
Further, in order to redisperse and use in water, the thickness is preferably 10 μm or less.

The temperature in the drying chamber is determined by the amount of heat of combustion in the pulse combustor, the amount and temperature of water contained in the aqueous synthetic resin emulsion supplied to the dryer, and the resin gas introduced into the drying chamber separately from the combustion gas to convey the resin powder. The temperature can be appropriately adjusted and controlled by the temperature of air (called secondary air) and the amount of air introduced, and the temperature is preferably 40 to 80 ° C. The temperature in the drying room is 80
If the temperature exceeds ℃, the adhesion of the resin to the wall of the drying chamber or the cyclone device and the pipes connecting them becomes remarkable, so that not only the collection of the target resin powder becomes difficult but also the melting of the resin particles. Adhesion becomes remarkable and water redispersibility cannot be obtained. If the temperature in the drying chamber is less than 40 ° C., it is difficult to sufficiently dry the aqueous synthetic resin emulsion.

The dried resin powder is sent to a powder collecting device such as a cyclone device or a bag filter device together with the combustion gas and the secondary air, and the resin powder is collected to obtain a product.

An anti-binder may be used in the synthetic resin powder obtained in the present invention in order to improve storage stability. In a resin having a relatively low glass transition point, powders are sometimes caustic, aggregated and blocked due to loading during storage, and a method of adding an anti-caking agent to prevent this phenomenon is known. . A method of uniformly adding and mixing the resin powder after drying and powdering, and a method of simultaneously spraying an anti-binding agent when the synthetic resin aqueous emulsion is dried, may be employed.
The latter method is preferred because uniform mixing and selective surface adhesion are obtained, and the effect of preventing caking is obtained with a smaller amount.

As such an anti-binder, fine inorganic powders are preferable. For example, calcium carbonate, clay, silicic anhydride, aluminum silicate, silica, talc, alumina white and the like can be used. The amount of the anti-binder is not particularly limited, but is preferably in the range of 0.1 to 20 parts by weight based on 100 parts by weight of the resin powder.

The synthetic resin powder obtained in the present invention is, for example, PET, nylon, PEN, PVA, PP, PE,
ST and other film surface treatment agents, fiber, paper, plastic, building materials, wallpaper, heat insulating materials, etc.
Mortar modifier applications, artificial leather, textile finishing, textile processing agents applications such as back coating agents for sheets and carpets,
It can be used for plastisols such as wallpaper, vehicles for aqueous paints and aqueous inks, and the like.

Various additives can be added to the synthetic resin powder obtained in the present invention. For example, viscosity improvers, water retention agents, tackifiers, thickeners, etc. for adhesives, viscosity improvers, thickeners, pigment dispersants, stabilizers, defoamers for paint binders and aqueous ink binders Etc. Leveling agent, antistatic agent, fiber softener, thickener, defoamer, etc. for fiber finishing applications, AE agent for cement and mortar modifier, water reducing agent, water retention agent, thickener, fluidizer ,
Waterproofing agents and the like. Depending on the form of the additive, these additives may be added to the synthetic resin aqueous emulsion before drying, a method of spraying simultaneously with drying, or a method of adding to the synthetic resin powder after drying. is there.

Next, the present invention will be described specifically with reference to examples.

[0033]

The present invention will be described in detail with reference to the following examples.
The present invention is not limited to only these examples. In the description, “parts” and “%” are based on weight unless otherwise specified.

Synthesis Example 1 (Production of Synthetic Resin Aqueous Emulsion 1) In a reaction vessel equipped with a stirrer, a thermometer and a reflux condenser, 81 parts of ion-exchanged water and Neoperex F-25 (manufactured by Kao Corporation) 2 parts of anionic emulsifier: sodium dodecylbenzenesulfonate) and 1.5 parts of Emulgen 940 (nonionic emulsifier: polyoxyethylene nonyl phenyl ether manufactured by Kao Corporation) were charged in a nitrogen stream at 75 to 8 parts.
While warming to 0 ° C. and stirring, 0.5 part of ammonium persulfate was charged.

Next, Gohsenol GL-05 (partially saponified polyvinyl alcohol manufactured by Nippon Synthetic Chemical Industry Co., Ltd .:
15% of saponification degree 88mol%, polymerization degree 1000 or less)
A mixture consisting of 60 parts of an aqueous solution, 55 parts of butyl acrylate, 42 parts of methyl methacrylate and 3 parts of methacrylic acid was added dropwise over 180 minutes to copolymerize the mixture, and was further kept at the same temperature for 30 minutes to complete the polymerization. Was. Then, the mixture was cooled to 30 ° C. and adjusted to pH 8.0 and solid content 45% with 28% aqueous ammonia and ion exchanged water.

Synthesis Example 2 (Production of Synthetic Resin Aqueous Emulsion 2) In a reaction vessel equipped with a stirrer, a thermometer and a reflux condenser, 100 parts of ion-exchanged water and Emal 10 (an anionic emulsifier manufactured by Kao Corporation) : Sodium lauryl sulfate) 1
And Emulgen 940 (Nonionic emulsifier manufactured by Kao Corporation: polyoxyethylene nonylphenyl ether) 4
Then, 0.5 parts of potassium persulfate was charged while heating and stirring at 80 ° C. under a nitrogen stream. Next, a monomer mixture consisting of 50 parts of 2-ethylhexyl acrylate, 48 parts of methyl methacrylate and 2 parts of methacrylic acid was added dropwise over 3 hours.

After the completion of the dropwise addition, potassium persulfate was further added to 0.1%.
Then, the mixture was kept at 80 ° C. for 2 hours, cooled to room temperature, and adjusted to pH 8. with 14% ammonia water and ion-exchanged water.
At 7, the solids content was adjusted to 45%.

Synthesis Example 3 (Production of formalin condensate of melamine sulfonate) In a reaction vessel equipped with a stirrer, a thermometer and a reflux condenser, 49 parts of ion-exchanged water, 42 parts of melamine, and 81 parts of 37% formalin were used. , 26 parts of sodium hydrogen sulfite and 4.4 parts of sodium hydroxide were charged, the pH of the reaction system was raised to 13.0, the temperature was raised to 75 ° C., and the temperature was maintained for 2.5 hours.

Next, the temperature in the reaction system was set to 55 ° C.
A solution obtained by diluting 7.1 parts of concentrated sulfuric acid with 100 parts of water was added dropwise over 1 hour to adjust the pH to 4.4.

Further, when the same temperature was maintained for 1 hour,
The reaction mixture became viscous, that is, the Brookfield viscosity at 25 ° C. was 15000 mPa · s. At this point, 150 parts of water were added and the temperature was maintained for another 3 hours.

Thereafter, 5 parts of sodium hydroxide and 70 parts of water were added and cooled to room temperature.

Solid content 20%, viscosity 180 mPa · s, p
A colorless, translucent liquid melamine sulfonate formalin condensate was obtained with H11.2, a weight average molecular weight of 300,000.

Synthesis Example 4 (Production of an aqueous emulsion of an ethylene-vinyl acetate copolymer synthetic resin) In a stainless steel pressure-resistant reactor, 123.5 parts of ion-exchanged water were added.
2 parts of Neoperex F-25 (anionic emulsifier manufactured by Kao Corporation: sodium dodecylbenzenesulfonate), 1.5 parts of emulgen 940 (1.5% of Kao Corporation seinonion-based emulsifier: polyoxyethylene nonylphenyl ether), Gohsenol GL- 05 (Nippon Synthetic Chemical Industry Co., Ltd., partially saponified polyvinyl alcohol: saponification degree 88 mol%, polymerization degree 1000 or less) 4.0 parts, Gohsenol GH-17
(Saponified polyvinyl alcohol manufactured by Nippon Synthetic Chemical Industry Co., Ltd .: saponification degree 88 mol%, polymerization degree 1500 or more)
4.0 parts were charged, heated and stirred at 75 to 80 ° C. to dissolve sufficiently, cooled to 40 ° C., and 85 parts of vinyl acetate was added and stirred to emulsify.

Further, 0.5 part of sodium pyrosulfite and 0.01 part of ferric sulfate were added, the pressure-resistant reactor was sealed, the system was replaced with nitrogen, and the system was pressurized with ethylene to 15 atm. did. A solution obtained by dissolving 0.5 part of ammonium persulfate and 0.5 part of 28% aqueous ammonia in 10 parts of water was added dropwise over 4 hours while stirring and maintaining the temperature of the system at 40 ° C., and further 3 hours at the same temperature. This was maintained to complete the polymerization.

The obtained synthetic resin aqueous emulsion 3 had a solid content of 44.6%, pH 5.5, and vinyl acetate: ethylene (copolymerization ratio) = 85: 15 (the ester groups of the obtained synthetic resin aqueous emulsion were 80 ° C. Is hydrolyzed with a 1 mol / dm ³ aqueous sodium hydroxide solution, and calculated from the amount of base consumed.)

Example 1 The synthetic resin aqueous emulsion 1 obtained in Synthesis Example 1 was diluted with ion-exchanged water to a solid content of 20%, and a pulse shock wave dryer equipped with a two-fluid nozzle as a sprayer (Osaka Fuji Kogyo Co., Ltd.) ) Pulcom 25 type: Rated combustion amount: 8
(3.7 MJ / h), and dried under the following conditions to obtain a resin powder. Although very slight accumulation of the resin powder on the inside of the drying chamber, pipes, cyclones and the like was observed, it could be easily removed from the wall surface with a broom or the like. Table 1 shows the results of tests on the water content, particle diameter, and redispersibility of the obtained resin powder in water.

Drying condition Burning amount: 51.1 MJ / h Secondary air amount: 750 m ³ / h Spray pressure: 600 kPa Drying room temperature: 50 ° C. Raw material supply amount: 15 kg / h

Example 2 The aqueous synthetic resin emulsion 2 obtained in Synthesis Example 2 was diluted with ion-exchanged water to a solid content of 20% and dried to a powder. The drying apparatus and the drying conditions were the same as in Example 1. Deposition of the resin powder on the inside of the drying chamber, piping, cyclone, etc. was observed, but it could be easily removed from the wall with a broom or the like. The results are shown in Table 1.

Example 3 10 of the synthetic resin aqueous emulsion 2 obtained in Synthesis Example 2
Gosenol GL-05 (partially saponified polyvinyl alcohol manufactured by Nippon Synthetic Chemical Industry Co., Ltd .: saponification degree 8)
8 mol%, degree of polymerization 1000 or less) 15% aqueous solution 30
Parts were added and mixed well. Further, the solid content was diluted to 20% with ion-exchanged water and dried and powdered. The drying apparatus and the drying conditions were the same as in Example 1. Although very slight accumulation of the resin powder on the inside of the drying chamber, pipes, cyclones and the like was observed, it could be easily removed from the wall surface with a broom or the like. The results are shown in Table 1.

Example 4 10 of the synthetic resin aqueous emulsion 2 obtained in Synthesis Example 2
To 0 parts, 22.5 parts of a formalin condensate of the melamine sulfonate obtained in Synthesis Example 3 were added and mixed well. The solid content was further diluted to 20% with ion-exchanged water, and dried and powdered.
The drying apparatus and the drying conditions were the same as in Example 1. Although very slight accumulation of the resin powder on the inside of the drying chamber, pipes, cyclones and the like was observed, it could be easily removed from the wall surface with a broom or the like. The results are shown in Table 1.

Example 5 The synthetic resin aqueous emulsion 3 obtained in Synthesis Example 4 was diluted with ion-exchanged water to a solid content of 20% and dried to a powder. The drying apparatus and the drying conditions were the same as in Example 1. Deposition of the resin powder on the inside of the drying chamber, piping, cyclone, etc. was observed, but it could be easily removed from the wall with a broom or the like. The results are shown in Table 1.

Example 6 The synthetic resin aqueous solution obtained in Synthesis Example 1 was produced in the same manner as in Example 1 except that the drying room temperature was set at 75 ° C. and the drying was performed by adjusting the amount of combustion and the amount of secondary air. Emulsion 1 was dried to obtain a resin powder. The results are shown in Table 1.

Example 7 The synthetic resin aqueous emulsion 1 obtained in Synthesis Example 1 was subjected to pulse shock wave drying (Pull manufactured by J. Jireh Corporation (USA)).
Using a se dryer, drying was performed at a drying room temperature of 75 ° C. and a raw material supply amount of 8 kg / h to obtain a resin powder. The results are shown in Table 1.

Drying condition Burning amount: 46.4 MJ / h Secondary air amount: 280 m ³ / h Drying room temperature: 75 ° C. Raw material supply amount: 8 kg / h

Example 8 The synthetic resin aqueous solution obtained in Synthesis Example 1 was produced in the same manner as in Example 1 except that the drying room temperature was set to 90 ° C. by adjusting the amount of combustion and the amount of secondary air, followed by drying. Emulsion 1 was dried to obtain a resin powder. The results are shown in Table 1.

Comparative Example 1 The synthetic resin aqueous emulsion 1 obtained in Synthesis Example 1 was diluted with ion-exchanged water to a solid content of 30%, and a spray dryer equipped with a disk type sprayer (manufactured by Okawara Kakoki Co., Ltd.
Using OC-16), drying and resin powdering were performed under the following conditions. Although a small amount of resin powder was obtained, melting adhesion of the resin was observed on the wall surface, and cleaning with a solvent was required.
The results are shown in Table 1.

Drying conditions Sprayer disk rotation speed: 20000 rpm Hot air drying chamber inlet temperature: 100 ° C. Hot air drying chamber outlet temperature: 65 ° C. Raw material supply amount: 5.0 kg / h

[Evaluation method of moisture content] About 4 g of a resin powder is sampled in a tin plate, and the sample weight is measured with a precision balance. The weight after drying under reduced pressure for 4 hours in a vacuum dryer kept at 50 ° C. was measured, and the loss on heating was used as the moisture content.

[Evaluation Method of Particle Diameter] The appearance and fusion state of the powder particles were observed by SEM (scanning electron microscope).

[Method of Evaluating Redispersibility in Water] Method A: 20 g of resin powder and 80 g in a 200 ml beaker
Of distilled water, and the mixture was stirred for 5 minutes at 5000 rpm using a stirrer to evaluate redispersibility. Method B: The redispersibility was evaluated by the same blending method as in Method A except that the mixture was manually stirred for 5 minutes using a glass rod.

Redispersibility: A: A dispersion similar to the dispersion before drying is obtained. ：: Most of the resin powder was dispersed in water, the dispersion was uniform, and the sedimentation of the resin was slight. Δ: The resin powder is dispersed in water, but there are many resin sediments with time. ×: Immediately after the stirring was stopped, the redispersion liquid was separated into two layers, a transparent layer and a precipitated resin powder.

[0062]

[Table 1]

[0063]

[Table 2]

[0064]

As is evident from the above results, according to the method of drying a synthetic resin aqueous emulsion of the present invention with a pulse shock wave drier to obtain a powdered resin, there is no adhesion of the resin to the wall of the drying chamber, It can be seen that a resin powder can be obtained without thermal fusion of the particles. Further, it can be seen that the obtained resin powder is extremely excellent in redispersibility in water.

[0065]

[Brief description of the drawings]

FIG. 1 is a flowchart including a schematic diagram of a pulse shock wave drying device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Constant-quantity pump apparatus 2 ... Pulse combustor apparatus 3 ... Atomizer apparatus 4 ... Compressor for secondary air 5 ... Drying room apparatus 6 ... Cyclone apparatus 7 ... Back filter apparatus

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 61:32) 101: 00

Claims (5)

[Claims] 1. A method for producing a resin powder, comprising drying an aqueous synthetic resin emulsion with a pulse shock wave dryer to form a powder. 2. The method for producing a resin powder according to claim 1, wherein the temperature in the drying chamber of the pulse shock wave drying device is 40 to 80 ° C. 3. The synthetic resin aqueous emulsion contains 1 to 30% by weight of a resin solid content of at least one kind of protective colloid selected from polyvinyl alcohol and a formalin condensate of melamine sulfonate. 3. The method for producing a resin powder according to 2. 4. A resin powder obtained by drying and pulverizing an aqueous synthetic resin emulsion with a pulse shock wave drier. 5. The synthetic resin aqueous emulsion contains 1 to 30% by weight of a resin solid content of at least one kind of protective colloid selected from polyvinyl alcohol or a formalin condensate of melamine sulfonate. Resin powder.