JP6654841B2 - Method for producing coagulated latex particles - Google Patents

Description

  The present invention relates to a method for producing coagulated latex particles.

  Conventionally, emulsion polymerization latex particles have been used as a resin modifier such as an impact resistance modifier, and as a means for recovering the same, for example, a granulation operation such as coagulation of the emulsion polymerization latex to form particles is used. Required (hereinafter, the obtained particles are also referred to as coagulated latex particles).

  As a method for producing coagulated latex particles, there is known a method in which a polymer latex and a coagulant solution are brought into contact in a mist state in a gas phase to coagulate the polymer latex (Patent Documents 1 and 2). .

In Patent Document 1, by spraying or dropping a polymer latex into a gas phase containing a coagulant solution in the form of an aerosol, fine particles are reduced as compared with a method in which the polymer latex is added to a coagulant and coagulated, The bulk specific gravity is increased.
In Patent Document 2, fine particles are reduced by spraying or dropping an emulsion polymerization latex containing a water-soluble polymer compound into a gas phase containing a coagulant solution in the form of an aerosol.

JP-A-53-30647 WO 2006/092897 pamphlet

  However, in Patent Document 1, the bulk specific gravity is low and the number of microparticles is large in Patent Document 1, and in Patent Document 2, the water-soluble polymer compound Na alginate is used in an amount of about 0.4 part of the example amount. Then, the bulk specific gravity was found to be low, and it was still desired to increase the bulk specific gravity of the coagulated latex particles and reduce the fine particles.

  Therefore, an object of the present invention is to provide a method for producing coagulated latex particles having a small amount of fine particles and a high bulk specific gravity.

  The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and as a result, when solidifying droplets of the emulsion polymerization latex having increased viscosity in a gas phase containing a coagulant solution in the form of an aerosol, fine particles The present invention has been found that coagulated latex particles having a low bulk and a high bulk specific gravity can be obtained.

That is, the gist of the present invention is as follows.
[1] An emulsion polymerization latex containing a thickener comprising a nonionic water-soluble polymer is sprayed or dropped into a gas phase containing a coagulant solution in the form of an aerosol, and the droplets of the emulsion polymerization latex are added to an aqueous phase. A method for producing coagulated latex particles, wherein the method is carried out by dropping or pouring into the inside.
[2] The production method according to [1], wherein the viscosity at 25 ° C. of the emulsion polymerization latex is 10 mPa · s or more.
[3] An emulsion polymerization latex having a viscosity of 10 mPa · s or more at 25 ° C. is sprayed or dropped into a gas phase containing a coagulant solution in the form of an aerosol, and drops of the emulsion polymerization latex are dropped into an aqueous phase. Or a method for producing coagulated latex particles.
[4] The emulsion polymerization latex according to any one of [1] to [3], wherein a thickener of 0.001 to 3.0 parts by weight is contained in the emulsion polymerization latex with respect to 100 parts by weight of the polymer solid content of the emulsion polymerization latex. The manufacturing method as described.
[5] The production method according to any one of [1] to [4], wherein the volume average particle diameter of the polymer in the emulsion polymerization latex is 0.05 to 0.5 μm.
[6] The production method according to any one of [1] to [5], wherein a polymer solid content concentration of the emulsion polymerization latex is 10 to 55% by weight.
[7] The production method according to any one of [1] to [6], wherein the thickener has a viscosity average molecular weight of 600,000 to 8,000,000.
[8] The coagulant solution comprises a monovalent inorganic acid, a monovalent inorganic acid salt, a divalent inorganic acid, a divalent inorganic acid salt, a trivalent inorganic acid, and a trivalent inorganic acid. The production method according to any one of [1] to [7], which is an aqueous solution containing one or more substances selected from salts.
[9] The thickener is one selected from the group consisting of polyalkylene oxide, polyvinyl alcohol, methyl cellulose, hydroxyethyl methyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, polyvinyl pyrrolidone, polyacrylamide, and polydimethylaminoethyl methacrylate. The production method according to any one of [1] to [8].
[10] The emulsion polymerization latex,
Polymerized from 50 to 100% by weight of butadiene, 0 to 40% by weight of an aromatic vinyl monomer, 0 to 10% by weight of a vinyl monomer copolymerizable with butadiene and an aromatic vinyl monomer, and 0 to 5% by weight of a polyfunctional monomer. A rubber latex having a glass transition temperature of 0 ° C. or less, a solid content of 50 to 95 parts by weight, a methacrylate ester 10 to 100% by weight, an aromatic vinyl monomer 0 to 90% by weight, a vinyl cyanide monomer 0 to 25% by weight; [1] to [9] obtained by graft-polymerizing 5 to 50 parts by weight of a monomer mixture composed of 0 to 20% by weight of a vinyl monomer copolymerizable with a methacrylate, an aromatic vinyl monomer and a vinyl cyanide monomer. ] The manufacturing method according to any one of the above.
[11] The production method according to any one of [1] to [10], wherein the volume average droplet diameter of the emulsion polymerization latex sprayed or dropped into the gas phase is 50 μm to 5 mm.
[12] An emulsion polymerization latex and 10 to 10000 parts by weight of water are flowed down along the inner wall surface of a container for spraying a coagulant solution with respect to 100 parts by weight of a polymer solid content in the emulsion polymerization latex. The production method according to any one of [1] to [11].

  According to the present invention, it is possible to provide coagulated latex particles having a small amount of fine particles and a high bulk specific gravity.

In the present invention, an emulsion polymerization latex containing a thickener or an emulsion polymerization latex having a predetermined viscosity is sprayed or dropped into a gas phase containing a coagulant solution in the form of an aerosol, and the droplets of the emulsion polymerization latex are added to water. This is a method for producing coagulated latex particles that are dropped or put into a phase. The production method is to prepare a coagulated latex particle having a small number of fine particles and a high bulk specific gravity by coagulating an emulsion polymerization latex having a higher viscosity than conventionally, in a gas phase and preferably in an aqueous phase. is there. The haze shape indicates that the object is in a mist state.
In the present invention, for example, the emulsion polymerization latex may be a polymerization reaction solution prepared by preparing a core-shell graft copolymer or the like by emulsion polymerization as it is and adding a thickener thereto.

The coagulated latex particles (coagulated emulsion polymerization latex particles, polymer particles) in the present invention are not particularly limited, but (1) butadiene 50 to 100% by weight, aromatic vinyl monomer 0 to 40% by weight, butadiene and 0 to 10% by weight of a vinyl monomer copolymerizable with an aromatic vinyl monomer and 0 to 5% by weight of a polyfunctional monomer, and a solid content of 50 to 95 parts by weight of a rubber latex having a glass transition temperature of 0 ° C. or less. 10 to 100% by weight of methacrylate, 0 to 90% by weight of aromatic vinyl monomer, 0 to 25% by weight of vinyl cyanide monomer and vinyl copolymerizable with methacrylate, aromatic vinyl monomer and vinyl cyanide monomer. Graft polymerizing 5 to 50 parts by weight of a monomer mixture consisting of 0 to 20% by weight of monomers Polymer latex, (2) acrylic acid ester 50 to 100% by weight, aromatic vinyl monomer 0 to 40% by weight, vinyl monomer copolymerizable therewith 0 to 10% by weight and polyfunctional monomer 0 to 5 % By weight of a rubber latex having a glass transition temperature of 0 ° C. or less, 50 to 95 parts by weight of solid content, 10 to 100% by weight of methacrylate ester, 0 to 90% by weight of aromatic vinyl monomer, and vinyl cyanide. It is obtained by graft polymerization of 0 to 25% by weight of a monomer and 5 to 50% by weight of a monomer mixture comprising 0 to 20% by weight of a vinyl monomer copolymerizable with a methacrylic acid ester, an aromatic vinyl monomer and a vinyl cyanide monomer. Polymer latex, (3) 50-95% by weight of methyl methacrylate, alkyl group having 2-8 carbon atoms 60 to 95 parts by weight of a mixture of 5 to 50% by weight of a methacrylic acid ester and 0 to 20% by weight of a vinyl monomer copolymerizable therewith are first subjected to emulsion polymerization, and the methacrylic acid is added in the presence of the resulting polymer latex. 20 to 80% by weight of methyl, 20 to 80% by weight of at least one monomer selected from methacrylates other than acrylate and methyl methacrylate, and 0 to 20% by weight of a vinyl monomer copolymerizable therewith. Any of the polymer latexes obtained by polymerizing 5 to 40 parts by weight of the mixture of the above to a total amount of 100 parts by weight can be suitably used for the reasons described below.
General methods for producing the polymer particles of the emulsion polymerization latex described in the above (1) to (3) are described in detail, for example, in JP-A-2-269755 and JP-A-8-217817. . However, the manufacturing method is not limited to this.

  The polymer particles (1) to (3) are widely used as a quality improving agent (particularly, an impact resistance improving agent) of a thermoplastic resin, and the high quality solidified particles are compared by the production method of the present invention. Can be easily obtained. However, the polymer particles of the emulsion polymerization latex that can be used in the present invention are not limited to these, and for example, a single particle mainly containing one or more monomers selected from the following monomer group: It is also possible to use latex polymer particles composed of a single or a mixture of polymer particles obtained by copolymerizing or graft-polymerizing the monomer composition.

  Examples of the monomer group include: 1) alkyl acrylates (acrylates) having an alkyl group having 1 to 10 carbon atoms such as methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate; 2) methyl methacrylate Alkyl methacrylates having an alkyl group having 1 to 10 carbon atoms such as ethyl methacrylate, butyl methacrylate, and 2-ethylhexyl methacrylate (methacrylic acid esters); 3) styrene, α-methylstyrene, monochlorostyrene, dichlorostyrene, etc. Vinyl arenes (aromatic vinyl monomers), 4) vinyl carboxylic acids such as acrylic acid and methacrylic acid, 5) vinyl cyanes such as acrylonitrile and methacrylonitrile (vinyl cyanide monomer) , 6) vinyl halides such as vinyl chloride, vinyl bromide and chloroprene; 7) vinyl acetate; 8) alkenes such as ethylene, propylene, butylene, butadiene and isobutylene; 9) allyl methacrylate, diallyl phthalate and triallyl cyanide Examples include polyfunctional monomers such as nurate, monoethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, divinylbenzene, and glycidyl methacrylate.

  The volume average particle size of the polymer particles is not particularly limited, but the volume average particle size of the polymer in the emulsion polymerization latex obtained by ordinary emulsion polymerization is preferably 0.05 to 0.5 μm, Preferably it is 0.1-0.3 micrometers, More preferably, it is 0.1-0.25 micrometers. The volume average particle size of the polymer particles can be measured, for example, by using MICROTRAC UPA (manufactured by Nikkiso Co., Ltd.).

  The polymer solid content concentration of the emulsion polymerization latex used in the present invention is not particularly limited as long as the object of the present invention is achieved, but is usually preferably 10 to 55% by weight, more preferably 10 to 45% by weight, and more preferably 25 to 40% by weight. % By weight is more preferred. When the polymer solid content concentration of the emulsion polymerization latex is lower than 10% by weight, the bulk specific gravity of the coagulated latex particles decreases. If the polymer solids concentration exceeds 55% by weight, it may be difficult to spray or drop the emulsion polymerization latex smoothly from a nozzle. The concentration of the polymer solid content of the emulsion polymerization latex was measured by placing 0.5 g of the latex in a hot air convection dryer at 120 ° C. for 3 hours to evaporate water, and emulsifying the latex weight before drying and the polymer weight after drying. It can be performed by calculating the polymer solid content concentration of the polymerization latex. In the present specification, the polymer solid content concentration corresponds to the solid content concentration of the emulsion polymer in the emulsion polymerization latex.

The viscosity of the emulsion polymerization latex at 25 ° C. is preferably 10 mPa · s or more, more preferably 15 mPa · s or more, further preferably 20 mPa · s or more, and preferably 100 mPa · s or less. Preferably it is 50 mPa · s or less, more preferably 30 mPa · s or less. When the viscosity at 25 ° C. is less than 10 mPa · s, the emulsion polymerization latex becomes fine and non-uniform, and is easily sprayed or dropped into the gas phase, resulting in an increase in fine particles. On the other hand, when the viscosity at 25 ° C. is more than 100 mPa · s, the emulsion polymerization latex becomes difficult to be sprayed or dropped, the nozzle used is easily clogged, and it is difficult to continuously spray or drop in the gas phase. Become.
The viscosity can be calculated for the target emulsion polymerization latex at 25 ° C. by using a viscometer such as a Canon Fenske, a Cannon-Fenske reverse flow type, Ubbelohde, or a rotational viscometer. For reference, the viscosity of distilled water at 25 ° C. is 0.8899 mPa · s.

  In the present invention, the thickener can be added to the emulsion polymerization latex in the form of an aqueous solution or a powder. The concentration of the aqueous solution of the thickener is not particularly limited, but is usually preferably 0.01 to 10% by weight. When the concentration of the aqueous solution is lower than 0.01% by weight, it is necessary to use a large amount of the aqueous solution to add a predetermined amount of the thickener. Conversely, when the concentration of the aqueous solution is higher than 10% by weight, Since the viscosity of the aqueous solution of the agent is high, handling tends to be difficult.

The thickener used in the present invention is composed of a nonionic water-soluble polymer, specifically, polyethylene oxide, polyalkylene oxide such as polypropylene oxide, polyvinyl alcohol, methylcellulose, hydroxyethylmethylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, Examples include polyvinylpyrrolidone, polyacrylamide, polydimethylaminoethyl methacrylate, and the like. The nonionic water-soluble polymer used in the present invention is, for example, a nonionic water-soluble polymer having water-solubility and thermoplasticity. Polyalkylene oxide is particularly preferred, and polyethylene oxide is most preferred.
The nonionic water-soluble polymer may be used alone or in a plurality of thickeners.

The emulsion polymerization latex may contain a predetermined amount of a thickener having a viscosity average molecular weight of 600,000 to 8,000,000.
The molecular weight of the thickener (for example, polyethylene oxide) is not particularly limited, but the viscosity average molecular weight is preferably from 600,000 to 8,000,000, and more preferably from 1,500,000 to 5,000,000. When the viscosity average molecular weight is lower than 600,000, even if polyethylene oxide is added to the emulsion polymerization latex, many fine particles are formed, and the object of the present invention may not be achieved. On the other hand, when the viscosity average molecular weight is higher than 8,000,000, the viscosity increase when polyethylene oxide is added to the emulsion polymerization latex becomes severe, and the stirring and mixing operation may become difficult. The viscosity average molecular weight of polyethylene oxide can be measured in a benzene solvent at 20 ° C.

  Polyethylene oxide may be a polymer compound having an ethylene oxide unit obtained by polymerizing ethylene oxide, and examples thereof include polyethylene oxide, higher alcohol ethylene oxide adduct, alkylphenol ethylene oxide adduct, fatty acid ethylene oxide adduct, and Polyhydric alcohol fatty acid ester ethylene oxide adduct, higher alkylamine ethylene oxide adduct, fatty acid amide ethylene oxide adduct, ethylene oxide adduct of fats and oils, polypropylene glycol ethylene oxide adduct and the like can be used.

  There is no particular limitation on the method of adding the thickener, and a predetermined amount of the thickener can be added to the latex at once, can be added separately, or can be added continuously. Can be.

  When the thickener is used as a solution, the concentration of the thickener in the solution is not particularly limited as long as the emulsion polymerization latex exhibits the above viscosity, but for example, about 0.1% by weight or more and about 10% by weight or less. It is.

The amount of the thickener (solids basis) is preferably 0.001 to 3.0 parts by weight (10 to 30,000 ppm), and preferably 0.01 to 0.05 parts by weight, per 100 parts by weight of the polymer solids of the emulsion polymerization latex. Part by weight (100 to 500 ppm) is more preferred.
If the amount of the thickener is less than 0.001 part by weight, the amount of the fine particles tends to increase. On the other hand, when the addition amount of the thickener is more than 3.0 parts by weight, the viscosity of the emulsion polymerization latex becomes high, and it becomes difficult to spray or drop from the nozzle.

  The coagulant solution that can be used in the present invention may be an aqueous solution of an inorganic acid or a salt thereof, or an organic acid or a salt thereof having a property of coagulating and coagulating the emulsion polymerization latex.

  The coagulant solution is selected from monovalent inorganic acids, salts of monovalent inorganic acids, divalent inorganic acids, salts of divalent inorganic acids, trivalent inorganic acids, salts of trivalent inorganic acids, and the like. It is preferably an aqueous solution containing one or more substances. Examples of the monovalent inorganic acid include halogen acids such as chloric acid, bromic acid and iodic acid, and nitric acid. Examples of the divalent inorganic acid include sulfuric acid. Examples of the trivalent inorganic acid include phosphoric acid. Examples of the cationic element or molecule capable of forming a salt with an acid include alkali metals, alkaline earth metals, transition metals (particularly, iron and zinc), Group 13 metals such as aluminum, and ammonium.

  The organic acid solution or the salt solution of the organic acid is an aqueous solution containing at least one substance selected from a monovalent organic acid, a monovalent organic acid salt, a divalent organic acid, a divalent organic acid salt, and the like. It is preferred that Monovalent organic acids include formic acid, acetic acid and the like. Examples of the monovalent organic acid salt include salts of formic acid, acetic acid, and the like with alkali metals. The divalent organic acids include oxalic acid, malic acid, maleic acid, malonic acid, tartaric acid and the like. Examples of the divalent organic acid salt include salts of acetic acid, formic acid and the like with alkaline earth metals and the like.

Specific examples of the inorganic acid solution, inorganic acid salt solution, organic acid solution or organic acid salt solution include sodium chloride, potassium chloride, lithium chloride, sodium bromide, potassium bromide, lithium bromide, and iodine. Alkali metal halides such as potassium iodide and sodium iodide; alkali metal sulfides such as potassium sulfate and sodium sulfate; ammonium sulfate; ammonium chloride; alkali metal nitrates such as sodium nitrate and potassium nitrate; calcium chloride, ferrous sulfate, and sulfuric acid Aqueous solution of inorganic salts such as magnesium, zinc sulfate, copper sulfate, barium chloride, ferrous chloride, ferric chloride, magnesium chloride, ferric sulfate, aluminum sulfate, potassium alum, iron alum, hydrochloric acid, sulfuric acid, nitric acid, Aqueous solutions of inorganic acids such as phosphoric acid, and organic acids such as acetic acid and formic acid. Aqueous solutions thereof, sodium acetate, calcium acetate, sodium formate, may be mentioned those alone or in combination with an aqueous solution of organic acid salts such as calcium formate. Among these, sodium chloride, potassium chloride, sodium sulfate, ammonium chloride, calcium chloride, magnesium chloride, magnesium sulfate, aqueous solutions of salts of monovalent or divalent inorganic acids such as barium chloride, hydrochloric acid, monovalent such as sulfuric acid or An aqueous solution of a divalent inorganic acid can be suitably used. The method of adding the inorganic salt or acid is not particularly limited, and batch addition, divided addition, or continuous addition can be used.
Among them, aqueous solutions of inorganic acids are preferred, aqueous solutions of hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid are more preferred, and aqueous solutions of hydrochloric acid are even more preferred.

The coagulant concentration in the coagulant solution is, for example, 1 to 45% by weight, preferably 5 to 40% by weight, and more preferably 10 to 35% by weight.
The coagulant solution may be added, for example, in an amount of 1 to 30 parts by weight, preferably 5 to 20 parts by weight, based on 100 parts by weight of the polymer solids.

Hereinafter, a method of spraying or dripping the emulsion polymerization latex or the coagulant solution will be described.
In order to spray or drop the emulsion polymerization latex, the latex may be sprayed or dropped from a nozzle. The nozzle is preferably a pressure nozzle, a two-fluid nozzle, an ultrasonic nozzle, a high-frequency device or a dropping nozzle, more preferably a pressure nozzle, and even more preferably a swirling flow nozzle. When the emulsion polymerization latex is sprayed or dropped from the nozzle, it can be coagulated in a gas phase containing a coagulant solution in the form of an aerosol. Therefore, the droplets of the emulsion polymerization latex can be made smaller, and the fine particles can be further reduced.

The diameter of the nozzle is, for example, 0.01 mm to 2.0 mm, preferably 0.05 mm to 1.5 mm, and more preferably 0.1 mm to 1.0 mm. If the diameter is more than 2.0 mm, the sprayed or dropped emulsion polymerization latex may not be sufficiently coagulated in the gas phase containing the sprayed form of the coagulant solution, and the bulk specific gravity of the coagulated latex particles may be low. is there. On the other hand, when the diameter is small, continuous spraying or dripping becomes difficult, and there is a possibility that productivity may decrease.
The spray pressure of the nozzle is, for example, 0.5 to 10 kg / cm ² , preferably 1.0 to 5.0 kg / cm ² .
The volume average droplet diameter of the emulsion polymerization latex sprayed or dropped in the gas phase is preferably 50 μm to 5 mm, preferably 100 μm to 800 μm, more preferably 150 μm to 600 μm.

Spraying or dripping of the coagulant solution may be performed in the same manner as described above, but it is preferable to spray using a two-fluid nozzle. When a two-fluid nozzle is used, a gas such as air, nitrogen, or carbon dioxide may be sprayed simultaneously with the coagulant solution.
When a two-fluid nozzle is used, the mixing ratio of the coagulant solution and the gas may be a predetermined coagulant solution amount with respect to 100% by weight of the polymer solid content as described above. In this way, the coagulant solution can be contained in the gas phase in the form of an aerosol.
The droplet diameter of the coagulant solution sprayed from the two-fluid nozzle is, for example, 0.01 to 500 μm, preferably 0.05 to 100 μm, and more preferably 0.1 to 50 μm.

  In the present invention, the emulsion polymerization latex and the coagulant solution are preferably sprayed or dropped into the gas phase at the same time, and the emulsion polymerization latex is sprayed or dropped into the gas phase and the coagulation agent solution may be sprayed at the same time. More preferably, the emulsion polymerization latex is sprayed into the gas phase while the coagulant solution is sprayed at the same time.

  The method of the present invention may be performed in a container having a substantially vertical inner wall, and an aqueous phase may be provided on the bottom surface of the container to collect the coagulated latex particles.

The container is not particularly limited as long as it can spray or drip the emulsion polymerization latex and the coagulant solution, but may be any shape such as a cylindrical shape or a rectangular parallelepiped shape.
The container preferably has a cylindrical shape, and may have a diameter of, for example, 30 to 500 cm.
In the container, the height from the top to the bottom liquid surface (aqueous phase surface) of the emulsion polymerization latex and the coagulant solution sprayed or dropped is such that the emulsion polymerization latex and the coagulant solution come into contact, and the emulsion polymerization latex coagulates. The height may be any height, for example, 50 cm to 10 m, and preferably 1 m to 5 m.

In the container, water may flow down along the inner wall surface while the emulsion polymerization latex and the coagulant solution are sprayed or dropped. This makes it possible to suppress the emulsion polymerization latex, the coagulant solution, and the coagulated latex particles sprayed or dropped into the gas phase from adhering to the inner wall surface. The amount of water flowing down along the inner wall surface is preferably, for example, 10 to 10000 parts by weight based on 100 parts by weight of the polymer solid content in the emulsion polymerization latex. If the amount of water flowing down along the wall surface is less than 10 parts by weight, adhesion of the emulsion polymerization latex, the coagulant solution, and the coagulated latex particles may not be suppressed. On the other hand, when the amount of water flowing down along the wall surface is more than 10,000 parts by weight, the suppression of adhesion of the emulsion polymerization latex, the coagulating agent solution, and the coagulated latex particles is improved, but the water in the aqueous suspension of the coagulated latex particles is improved. Since the polymer solids concentration of the polymer decreases, the load of the wastewater treatment may increase.
The temperature of the water flowing down along the inner wall surface is, for example, 0 to 100 ° C, preferably 10 to 60 ° C in terms of simple operation.

  Under the above conditions, when the emulsion polymerization latex and the coagulant solution are sprayed or dropped, the coagulation of the emulsion polymerization latex can proceed in the gas phase, and the latex liquid due to the impact when entering the liquid phase from the gas phase (Coagulated latex particles) can also be suppressed from being irregularly shaped and generating fine powder.

The coagulated latex particles falling in the gas phase are then recovered in the aqueous phase. The aqueous phase may be an ordinary aqueous medium, and the aqueous phase may have the same composition as the coagulant solution in order to surely coagulate latex particles with insufficient coagulation.
The concentration of the coagulant in the aqueous phase may be lower than the concentration that forms a mist in the gas phase, for example, 0.01 to 15% by weight, preferably 0.05 to 10% by weight, more preferably 0.1 to 10% by weight. 1 to 5% by weight.

  In the present invention, heat treatment of the coagulated latex particles preferably promotes fusion between the polymer particles in the coagulated particles. The temperature of the heat treatment is not particularly limited, but is usually 120 ° C or lower, preferably 60 to 100 ° C, more preferably 65 to 95 ° C, and further preferably 70 to 90 ° C. The heat treatment time is, for example, 1 to 60 minutes, and preferably 5 to 50 minutes. Under these conditions, the mechanical strength of the coagulated latex particles increases and the water content of the polymer particles decreases. Further, in performing the heat treatment, in order to suppress agglomeration between particles during heating and during (after) the drying, before the heat treatment, a hard inelastic polymer latex (based on solid content) is used with respect to 100 parts by weight of the aggregate. It is preferable to add 0.5 to 3 parts by weight. After the inter-particle fusion prevention treatment, the coagulated emulsion polymerization latex particles according to the present invention can be recovered by performing dehydration and drying operations according to a conventional method.

  As the hard inelastic polymer, for example, the amount of a monomer capable of forming a rubber elastic body such as butadiene is small (for example, 30% by weight or less, preferably 20% by weight or less, more preferably 10% by weight of the whole polymer). Hereinafter, particularly 0% by weight), and those obtained by polymerizing other monomers can be used. Examples of the monomer that does not form a rubber elastic body include 1) an alkyl group having 10 or less carbon atoms such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. Alkyl (meth) acrylates, 2) vinylarenes such as styrene, α-methylstyrene, monochlorostyrene and dichlorostyrene, vinylcyanides such as acrylonitrile, 3) 1,3-butylene glycol di (meth) acrylate, allyl Examples include polyfunctional monomers such as (meth) acrylate, diallyl phthalate, triallyl cyanurate, monoethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, divinylbenzene, and glycidyl (meth) acrylate. It is. These monomers can be used alone or in appropriate combination.

The bulk specific gravity of the coagulated latex particles is, for example, 0.38 g / cm ³ or more, preferably 0.39 g / cm ³ or more, and more preferably 0.40 g / cm ³ or more. The upper limit of the bulk specific gravity is, for example, about 1.0 g / cm ³ .

The volume cumulative frequency of 50 μm or less in the volume particle size distribution of the coagulated latex particles is preferably 10% or less, more preferably 5% or less, even more preferably 4.5% or less, and even more preferably 4.0. %, Particularly preferably not more than 3.5%, most preferably not more than 3.0%.
The lower limit of the volume accumulation frequency of 50 μm or less is, for example, about 0% or about 0.1%.
The volume cumulative frequency of 1000 μm or more in the volume particle size distribution of the coagulated latex particles is preferably 3% or less, more preferably 1% or less. The lower limit of the volume accumulation frequency of 1000 μm or less is, for example, about 0% or about 0.1%.

  The volume average particle diameter of the coagulated latex particles is, for example, 50 to 500 μm, preferably 100 to 400 μm, and more preferably 200 to 350 μm.

  In the method for producing the coagulated latex particles of the present invention, if necessary, additives such as an antioxidant, a heat stabilizer, an ultraviolet absorber, a pigment, an antistatic agent, a lubricant, for example, an emulsion polymerization latex, or after completion of the coagulation operation May be added to the aqueous suspension of the coagulated latex particles.

  The coagulated latex particles produced according to the present invention may be used as a modifier such as an impact resistance improver, for example, a vinyl chloride resin, a (meth) acrylic resin, a polystyrene resin, a polycarbonate resin, a polyamide resin, a polyester resin. It can be suitably used as a thermoplastic resin such as a resin, or a thermosetting resin such as a phenolic resin, an epoxy resin, an unsaturated ester resin, a urea resin, and a melamine resin.

  Next, the present invention will be described in more detail based on examples, but the present invention is not limited to only the following examples. In the following, “parts” means “parts by weight” and “%” means “% by weight” unless otherwise specified.

(Measurement of particle size distribution based on volume cumulative frequency)
The particle size distribution of the coagulated latex particle suspensions obtained in the examples and comparative examples was measured with a laser diffraction / scattering type particle size distribution measuring device LA-950 (manufactured by HORIBA, Ltd.), and the volume average particle size was measured. The particle size distribution was determined from the volume cumulative frequency% of the particles of 1 μm or more and 3 mm or less (Table 1 shows the particle size distribution of 50 μm or less).

(Measurement of bulk specific gravity)
The bulk specific gravity of the obtained coagulated latex particles was measured using a bulk specific gravity measuring device (JIS K-6720 manufactured by Kuramochi Kagaku Kikai Seisakusho).

(Measurement of viscosity of emulsion polymerization latex at 25 ° C.)
The viscosity of the obtained emulsion polymerization latex at 25 ° C. was measured with a Brookfield viscometer (BL2 type, manufactured by Toki Sangyo; B-type viscometer, rotor diameter: 19 mm, rotation speed: 50 rpm).

(Example 1)
Manufacture of emulsion polymerization latex Manufacture of diene rubber polymer (R-1) 200 parts of deionized water was charged into a 100 L polymerization machine (pressure-resistant reaction vessel equipped with a stirrer), the inside of the polymerization machine was degassed, and the mixture was purged with nitrogen and stirred. the start, sodium 2.5 parts of oleic acid, ferrous _{(FeSO 4 · 7H 2 O)} 0.002 parts of sulfuric acid, ethylenediaminetetraacetic acid (hereinafter, EDTA referred) · 2Na salt 0.01 part of formaldehyde sulfoxylate 0.2 part of sodium acid, 0.2 part of tripotassium phosphate, 100 parts of butadiene, 0.5 part of divinylbenzene and 0.1 part of diisopropylbenzene hydroperoxide were charged.
After polymerizing at 40 ° C. for 10 hours and then maintaining at 60 ° C. for 4 hours, a diene rubber latex (R-1) having a polymerization conversion of 98%, an average particle diameter of 0.08 μm and a solid concentration of 32.5% was obtained. Was.

Production of Graft Polymer (G-1) In a glass reactor having a thermometer, a stirrer, a reflux condenser, a nitrogen inlet, a device for adding a monomer and an emulsifier, 70 parts of the diene rubber latex solid content, 50 parts of water parts, ferrous _{(FeSO 4 · 7H 2 O)} 0.004 parts of sulfuric acid, 0.005 parts of EDTA · 2Na salt, were mixed with 0.1 parts of formaldehyde sulfoxylate, sodium hexyl acid, among heated to mixture The temperature was brought to 60 ° C. Thereafter, a mixed solution of 22 parts of methyl methacrylate (MMA), 3 parts of styrene, 5 parts of butyl acrylate and 0.1 part of cumene hydroperoxide was continuously added over 4 hours, and polymerization was further continued for 1 hour. An emulsion polymerization latex (G-1) having a particle diameter of 0.23 μm was obtained.

200 parts of manufacturing of deionized water rigid non-elastic polymer latex (P-1), 0.3 parts of sodium oleate, ferrous _{(FeSO 4 · 7H 2 O)} 0.002 parts, ethylenediamine tetraacetic acid · 2Na sulfate 0.005 parts and 0.2 parts of sodium formaldehyde sulfoxylate were placed in a 100 L polymerization machine (pressure-resistant reaction vessel equipped with a stirrer), and the temperature was raised to 70 ° C. while stirring. Then, 45 parts of methyl methacrylate, 45 parts of styrene were added. A mixed solution of 10 parts of 1,3-butylene glycol dimethacrylate and 0.3 part of cumene hydroperoxide was continuously added over 7 hours. During this time, 0.3 parts each of sodium oleate was added at the second, fourth and sixth hours. After the continuous addition of the monomer mixture, stirring was continued for another 2 hours to obtain a rigid inelastic polymer latex (P-1) having a polymerization conversion of 99%.

Coagulation process-heat treatment process (manufacture of coagulated latex particles)
1000 g of emulsion polymerization latex (G-1) (350 g based on 100 parts of polymer solid content) was taken and adjusted to 25 ° C. (polymer solid content concentration was 35%). Under stirring, 17.5 g of a 1% polyethylene oxide (PEO-8Z, manufactured by Sumitomo Seika Co., Ltd., viscosity average molecular weight 1.7 million to 2.2 million) aqueous solution was added under stirring with a polyethylene oxide solid content of 0 to 100 parts of the polymer solid content of the emulsion polymerization latex. .05 parts) (viscosity of emulsion polymerization latex at 25 ° C. 22 mPa · s). The emulsion polymerization latex containing this polyethylene oxide was swirled from a liquid level at the bottom of the column at a spray pressure of 3.7 kg / cm ² using a swirl type conical nozzle having a nozzle diameter of 0.6 mm, which is a kind of pressure nozzle. Was sprayed as droplets having a volume average droplet diameter of 200 μm into a cylindrical device having a height of 5 m and a diameter of 50 cm. At the same time, a 30% strength aqueous hydrochloric acid solution was mixed with air using a two-fluid nozzle so as to give 5 to 10 parts with respect to 100 parts of the polymer solid content, and sprayed with a droplet diameter of 0.1 to 30 μm. The mixed latex droplets dropped in the column were put into a receiving tank containing a 0.1% hydrochloric acid aqueous solution at the bottom, and collected (they were emulsified along the inner wall surface of the cylindrical device. Water of 10 to 10000 parts was flowed down with respect to 100 parts of the polymer solid content in the polymerization latex.) In order to prevent fusion between the coagulated latex particles, 1 part of the hard inelastic polymer latex (P-1) was added to 100 parts of the polymer solid content to the hydrochloric acid aqueous solution in the receiving tank. Thereafter, a 10% concentration aqueous sodium hydroxide solution was further added to adjust the pH to 4 to 5, and then heated to 85 ° C. to perform a heat treatment for 5 minutes. Table 1 shows the results of the particle size distribution and bulk specific gravity of the obtained coagulated latex particles.

(Comparative Example 1)
In the same manner as in Example 1, an emulsion polymerization latex (average particle size 0.23 μm, polymer solid content concentration 35%) was obtained. 1000 g of the emulsion polymerization latex (350 g based on 100 parts of polymer solid content) was taken and adjusted to 25 ° C. (viscosity of the emulsion polymerization latex at 25 ° C. 7 mPa · s). Emulsion polymerization latex to which polyethylene oxide was not added was used as a pressurized nozzle with a swirling flow conical nozzle having a nozzle diameter of 0.6 mm at a spray pressure of 3.7 kg / cm ² from the liquid level at the bottom of the tower. The liquid was sprayed into a cylindrical device having a height of 5 m and a diameter of 50 cm as droplets having a volume average droplet diameter of 200 μm. At the same time, a 30% hydrochloric acid aqueous solution was mixed with air by a two-fluid nozzle so as to be 5 to 10 parts with respect to 100 parts of the polymer solid content, and sprayed with a droplet diameter of 0.1 to 30 μm. Drops of the mixed latex dropped in the tower were introduced into a receiving tank containing a 0.1% hydrochloric acid aqueous solution at the bottom thereof, and were collected (emulsified along the inner wall surface of the cylindrical device. Water of 10 to 10000 parts was flowed down with respect to 100 parts of the polymer solid content in the polymerization latex.) In order to prevent fusion between the coagulated latex particles, 1 part of the hard inelastic polymer latex (P-1) was added to 100 parts of the polymer solid content. Thereafter, a 10% concentration aqueous sodium hydroxide solution was added to adjust the pH to 4 to 5, and then heated to 85 ° C. to perform a heat treatment for 5 minutes. Table 1 shows the results of the particle size distribution and bulk specific gravity of the obtained coagulated latex particles.

  The amount of coarse particles having a size of 1000 μm or more obtained in Example 1 was 0.2%.

Claims (13)

An emulsion polymerization latex containing a thickener comprising a nonionic water-soluble polymer is sprayed or dropped into a gas phase containing a coagulant solution in the form of an aerosol, and a drop of the emulsion polymerization latex is dropped into an aqueous phase. Alternatively, the coagulated particles are heat-treated in the presence of a latex of a hard inelastic polymer in which a component derived from a monomer capable of forming a rubber elastic body is not more than 30% by weight of the whole polymer. For producing coagulated latex particles.   The method according to claim 1, wherein the viscosity at 25 ° C of the emulsion polymerization latex is 10 mPa · s or more. The coagulant solution into the gas phase containing at fume-like, emulsion polymerization latex viscosity at 25 ° C. is 10 mPa · s or more spraying or dropwise, dropwise or charged droplets of emulsified polymer latex in the aqueous phase Heat-treating the coagulated particles in the presence of a hard inelastic polymer latex in which a component derived from a monomer capable of forming a rubber elastic body is 30% by weight or less of the entire polymer. A method for producing latex particles. The method for producing coagulated latex particles according to any one of claims 1 to 3, wherein the aqueous phase is water or a coagulant solution. The method according to any one of claims 1 to 4 , wherein the emulsion polymerization latex contains 0.001 to 3.0 parts by weight of a thickener based on 100 parts by weight of the polymer solid content of the emulsion polymerization latex. The method according to any one of claims 1 to 5 , wherein a volume average particle diameter of the polymer in the emulsion polymerization latex is 0.05 to 0.5 µm. The method according to any one of claims 1 to 6 , wherein a polymer solid content concentration of the emulsion polymerization latex is 10 to 55% by weight. The method according to any one of claims 1 to 7 , wherein the thickener has a viscosity average molecular weight of 600,000 to 8,000,000. The coagulant solution is selected from monovalent inorganic acids, salts of monovalent inorganic acids, divalent inorganic acids, salts of divalent inorganic acids, trivalent inorganic acids, and salts of trivalent inorganic acids. The production method according to any one of claims 1 to 8 , which is an aqueous solution containing one or more kinds of substances to be produced. The thickener is at least one selected from the group consisting of polyalkylene oxide, polyvinyl alcohol, methylcellulose, hydroxyethylmethylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, polyvinylpyrrolidone, polyacrylamide, and polydimethylaminoethyl methacrylate. the method according to any one of claims 1-9. The emulsion polymerization latex,
Polymerized from 50 to 100% by weight of butadiene, 0 to 40% by weight of an aromatic vinyl monomer, 0 to 10% by weight of a vinyl monomer copolymerizable with butadiene and an aromatic vinyl monomer, and 0 to 5% by weight of a polyfunctional monomer. A rubber latex having a glass transition temperature of 0 ° C. or less, a solid content of 50 to 95 parts by weight, a methacrylate ester 10 to 100% by weight, an aromatic vinyl monomer 0 to 90% by weight, a vinyl cyanide monomer 0 to 25% by weight; methacrylic acid esters, according to claim 1-10 which is obtained by graft-polymerizing a monomer mixture 5-50 parts by weight of an aromatic vinyl monomer and vinyl cyanide monomer and copolymerizable vinyl monomer 0-20% by weight The production method according to any one of the preceding claims. The process according to any one of the emulsion polymerization latex having a volume average droplet diameter 請 Motomeko 1-11 Ru 50μm~5mm der spraying or dripping into the gas phase. Emulsion polymerization latex, and along the inner wall surface of the container for spraying the coagulant solution, emulsion polymerization latex of the polymer with respect to 100 parts by weight of the solid content 請 Motomeko 1-12 of Ru passed down water 10-10000 parts by weight The production method according to any one of the preceding claims.