JPH11217479A - Polastisol composition and molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plastisol being an acrylic resin plastisol and having good properties such as dispersibility in a plasticizer, excellent compatibility, storage stability, low viscosity, and application properties, being excellent in the ability to form a film within a short time upon being heated, and being capable of forming a cured film excellent in hardness, strengths, etc., and to provide a molded product thereof. SOLUTION: There are provided a plastisol composition being an acrylic resin plastisol comprising (A) a powdery or particulate acrylic resin and (B) a plasticizer, wherein component A is a resin obtained by passing a mixture comprising an acrylic polymerizable comonomr, a radical polymerization initiator, an emulsifier, an aqueous medium, etc., to a film emulsifier and subjecting the obtained emulsion to microsuspension polymerization and a molded product prepared therefrom.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to molding methods such as spread coating, dip molding, slash molding and spray painting which are excellent in viscosity stability, molding processability and compatibility. The present invention relates to an acrylic resin-based plastisol composition and a molded product widely used in the fields of toys, toys, automobile undercoating, and the like.

[0002]

2. Description of the Related Art Conventionally, a plastisol composition of a vinyl chloride resin type is known, and is used for wall coverings, floor coverings, dolls, and the like.
Although widely used in the fields of toys, automobile undercoating, PVC coated steel sheets, etc., in recent years, conversion to other resins has been required due to environmental problems.

[0003] For this reason, a plasticizer is blended into the acrylic resin particles and, if necessary, a filler and other additives are blended to form an acrylic resin plastisol.
Processing methods have been proposed. However, unlike the case of the vinyl chloride resin, when the acrylic resin uses a general-purpose plasticizer such as dioctyl phthalate, the compatibility with the resin is poor, so that the plasticizer easily bleeds out on the surface of the cured coating film. It has problems and cannot be used practically. Therefore, as a means for improving the compatibility with a plasticizer, a copolymer of a methyl methacrylate polymer with a long-chain alkyl ester monomer or a butadiene component has been proposed (Japanese Patent Publication No. 55-16177).
JP, JP-B-58-22043, JP-B-63-
66861, JP-B-4-24378). However, when the compatibility between the resin and the plasticizer is improved, the plastisol is thickened in inverse proportion to the viscosity stability, and the viscosity stability is reduced.Moreover, when a comonomer as described above is copolymerized with a homopolymer of methyl methacrylate. There is a new problem that the polymer is softened and the mechanical strength is lowered.

[0004] As a basic property of plastisol, when a resin and a plasticizer are mixed at room temperature, a dispersion (sol) that can flow is obtained.
That the sol viscosity does not increase significantly even after storage at room temperature for about one week, and furthermore, the resin and the plasticizer are quickly integrated after heating (gelling property), and after solidification, the plasticizer bleeds. It is necessary not to do. The plastisol of the polyvinyl chloride type has a condition that sufficiently satisfies the above-mentioned performance owing to the presence of an appropriate plasticizer, and has been used for many years in the field of plastisol processing. In the case of an acrylic resin, a conventional plasticizer may not always be appropriate, and a precise design of the resin is required to satisfy the above conditions.

[0005] In order to achieve the fluidity condition of the plastisol, it is preferable that the specific surface area of spherical resin particles is minimum, that is, large particles are used. In addition, the condition of storage stability depends on how the swelling of the resin particles by the plasticizer is reduced, so that large particles are preferred as in condition 1) if the polymer composition is the same. However, in order to stabilize the resin particles without suspending them in the plastisol, the smaller the resin particles, the better the resin particles are. Even under the gelling condition, the smaller the resin particles, the better. Thus, the conditions required for plastisols are inconsistent with the resin particle size. In particular, in the case of an acrylic monomer having no polarization such as vinyl chloride, this reciprocity becomes more remarkable. In order to balance these conflicting properties, it is necessary to control the particle size of the resin to a high degree, and particles having a size of 2 to 5 μm are optimal in consideration of the viscosity and stability of the sol and the sedimentation property.

Conventionally, acrylic resins for sols have been produced by obtaining a latex by emulsion polymerization and spray drying it. Generally, the acrylic resin produced by emulsion polymerization has a primary particle size of 0.5 μm or less, which is too small for a sol.
μm resin was obtained. Seed emulsion polymerization is preferable for sols because it has a relatively narrow particle size distribution and gives uniform resin particles, but particles larger than this are difficult to produce even if seed polymerization is repeated, and it is necessary to repeat the polymerization operation. There was a problem that productivity was poor.

As a method of simply increasing the average particle size of the resin and lowering the viscosity of the plastisol, 20 to 40% by weight of the resin for the plastisol is replaced with a resin for blending by suspension polymerization having a resin particle size of about 50 μm. A method of increasing the average resin particle size by using the method has been proposed. This method
It can be applied to applications where the surface of the molded product such as slush molding or rotational molding is finished in contact with the mold, but in the case of spread coating, the coating thickness is usually as thin as tens of μm. It cannot be used because the resin for blending protrudes from the surface and impairs the appearance.

On the other hand, a resin produced by a general suspension polymerization is 5
Although the particle size is 0 μm or more, after a monomer mixture is refined by mechanical shearing such as a homogenizer, a resin having a particle size of 2 to 5 μm is obtained by a single polymerization by subjecting the mixture to suspension polymerization. A method has been proposed.
-225748). However, when the monomer mixture is refined by such mechanical shearing, the particle size distribution is wide, and inevitably fine particles are produced in a certain ratio more than necessary, which increases the sol viscosity and stabilizes storage. There is a problem that lowers the performance.

[0009]

DISCLOSURE OF THE INVENTION The present invention is an acrylic resin-based sol having excellent dispersibility and compatibility with a plasticizer, good sol physical properties such as storage stability, low viscosity and coating properties, and An object of the present invention is to provide a plastisol composition and a molded product, which are excellent in heat film forming property in a short time and can form a cured coating film excellent in hardness, strength and the like.

[0010]

The present inventors have conducted detailed studies on the particle size distribution and sol properties of an acrylic resin in order to solve the above-mentioned problems. Acrylic resin with low viscosity, excellent storage stability, and excellent physical properties after heat gelation, when resin particles having a particle size are obtained by one polymerization and made into a sol by using the acrylic resin. The inventors have found that a plastisol composition of the present invention can be obtained, and have completed the present invention.

That is, the present invention relates to an acrylic resin-based plastisol composition comprising a granular acrylic resin (A) and a plasticizer (B), wherein the granular acrylic resin (A)
Is a resin obtained by passing a mixed solution comprising an acrylic polymerizable monomer, a radical initiator, a surfactant, an aqueous medium, and the like through a membrane emulsification apparatus, and then subjecting it to fine suspension polymerization. The plastisol composition, preferably the membrane emulsifier, consists of a porous glass membrane with uniform pores of 0.1-5 μm, preferably the average droplet size of the mixture droplets through the membrane emulsifier is 0 0.5-5 μm, 0.5 μm
m or less, preferably when the granular acrylic resin (A) has an average primary particle size of 0.5 to
10 μm and substantially no primary particles having a particle size of less than 0.5 μm, preferably, the plasticizer (B) is a benzoate ester, and any plastisol composition is used. A molded article is provided.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The mixture passed through the membrane emulsifying apparatus of the present invention is a mixture comprising an acrylic polymerizable monomer, a radical polymerization initiator, a surfactant and an aqueous medium. The liquid is a polymerizable monomer composition mixture having a uniform droplet diameter, and preferably has an average droplet diameter of 0.5 to 5 μm.
m and substantially no droplet diameter of less than 0.5 μm. This is subjected to fine suspension polymerization, and the average particle size of the primary particles of the resulting product particles is preferably 0.5 to 10 μm.
And substantially no primary particles having a particle size of less than 0.5 μm.

[0013] The membrane emulsifying apparatus referred to herein is "an apparatus for preparing a monodispersed emulsion by injecting and dispersing a dispersed phase into a continuous phase through an apparatus having a porous membrane having uniform pores". The porous membrane must have pores that are as uniform and tough as possible, and should preferentially wet the continuous phase of the aqueous medium and hardly wet the dispersed phase. CaO-Al2O3-B2 is a film material that satisfies these conditions.
There is a porous glass film made from O3-SiO2 glass,
For example, “MPG membrane” provided by Ise Chemical Co., Ltd. has a product having a pore diameter of 0.1 to 20 μm. In order to obtain a polymerizable monomer composition (mixture) having a uniform droplet diameter by a film emulsifying apparatus, a polymerizable monomer composition to be a dispersed phase is press-fitted from around a tubular porous glass membrane, and the inside of the tube is introduced. "Proceedings of the 1991 Reaction Engineering Lecture Meeting, 5 pages, 5 pages, Polymer Society (1991)" obtained by dispersing and emulsifying in an aqueous medium containing a surfactant to be a continuous phase.

The aqueous medium mentioned here is generally water that can be used industrially, preferably deionized water and pure water.

The acrylic monomer serving as the main component of the particulate acrylic resin (A) of the present invention is preferably a homopolymer or copolymer of methyl methacrylate, that is, a polymer containing methyl methacrylate as a main component. A methyl methacrylate monomer alone, or a vinyl ester such as vinyl acetate, a vinyl acrylate such as styrene, a vinyl cyanide such as acrylonitrile, methyl acrylate, ethyl methacrylate, or a methyl methacrylate monomer.
The main component is methyl methacrylate in which unsaturated compounds such as acrylic acid, methacrylic acid, and alkyl esters thereof are mixed, such as butyl methacrylate, cyclohexyl methacrylate, hydroxylethyl methacrylate, and glycidyl methacrylate.

The molecular weight of the particulate acrylic resin (A) of the present invention varies depending on the use of the acrylic sol of the present invention, but is 30,000 to 3,000,000 in terms of weight average molecular weight.
0 is preferred. When the weight average molecular weight is less than 30,000, the obtained acrylic polymer particles tend to be easily dissolved in a plasticizer, and the weight average molecular weight becomes 3,000.
If it is larger than 000, the resulting acrylic sol is not preferable because the film forming property of the resulting sol by heating is reduced.

The particulate acrylic resin (A) used in the present invention is produced by fine suspension polymerization. In fine suspension polymerization, an oil-soluble polymerization initiator and a dispersing agent are added to an acrylic polymerizable monomer, and the monomer is dispersed uniformly as fine droplets in an aqueous medium using a surfactant. Then, by heating, the oil-soluble polymerization initiator dissolved in the monomer droplet is decomposed to generate radicals, and radical polymerization proceeds in the monomer droplets. Specifically, a polymerizable monomer having a uniform droplet size is obtained by first passing a mixed solution comprising an acrylic polymerizable monomer, a radical initiator, a dispersant, and an aqueous medium through a film emulsifying apparatus. An aqueous resin dispersion is obtained by obtaining a composition and subjecting it to fine suspension polymerization. It is manufactured by spray-drying the obtained resin aqueous dispersion by a spray drying method, a pulse drying method, or the like.

The volume average particle diameter (hereinafter referred to as particle diameter) of the particulate acrylic resin (A) is determined from the particle diameter of the primary particles (resin emulsion particles) in view of the balance between heat-forming properties and storage stability. Is preferably in the range of 0.5 to 10 μm. The secondary particles in which the primary particles are aggregated during spray drying are preferably in the range of 0.1 to 100 μm. If the primary particle size is too large, the sol obtained will have adverse effects such as poor coating properties. In addition, the diffusion of the plasticizer during film formation by heating becomes poor, and complete gelation does not occur,
A cured coating film with extremely poor flexibility is obtained. If the primary particle size is too small, the viscosity of the acrylic sol tends to increase, the thixotropy tends to increase, and the storage stability tends to be insufficient. Therefore, it is preferable to optimize the particle size according to the required performance according to the application.

The radical initiator of the present invention is preferably an oil-soluble radical polymerization initiator. Such oil-soluble polymerization initiators include, for example, diacyl peroxides such as dibenzoyl peroxide, di-3,5,5-trimethylhexanoyl peroxide, dilauroyl peroxide, diisopropyl peroxydicarbonate, diisopropyl peroxide and the like. -Sec-butyl peroxydicarbonate, peroxydicarbonates such as di-2-ethylhexylperoxydicarbonate, peroxyesters such as t-butylperoxypivalate, t-butylperoxyneodecanoate, Alternatively, organic peroxides such as acetylcyclohexylsulfonyl peroxide and disuccinic acid peroxide, and 2,2 ′
-Azobisisobutyronitrile, 2,2'-azobis-2
An azo compound such as -methylbutyronitrile, 2,2'-azobisdimethylvaleronitrile and the like can be used. These polymerization initiators can be used alone or in combination of two or more. The amount of the polymerization initiator is appropriately selected depending on the type and amount of the monomer, the charging method, and the like. Per part, preferably 0.01 to
It can be selected in the range of 5.0 parts by weight.

In the present invention, prior to polymerization, monomers,
When homogenizing with water in which a surfactant is dissolved to form emulsified droplets, a dispersing aid is preferably used to improve the stability of the emulsified droplets. Examples of such a dispersing aid include higher alcohols and fatty acids having 10 to 24 carbon atoms, sorbitan mono-, di- or trialkyl esters having an alkyl group having 12 to 20 carbon atoms, and 12 to 20 carbon atoms.
Glycerol monoalkyl ester of 10 to 2 carbon atoms
And oil-soluble polar substances such as chlorinated paraffins of No. 4. The addition amount of the dispersing agent is preferably 0.2 to 5.0 parts by weight, and more preferably 0.2 to 5.0 parts by weight per 100 parts by weight of the monomer.
More preferably, it is 5 to 2.0 parts by weight. If the amount of the dispersing aid is less than 0.2 parts by weight per 100 parts by weight of the monomer, the emulsified droplets become unstable and may coagulate during the polymerization reaction to generate coagulum or scale. If the amount of the dispersing agent exceeds 5.0 parts by weight per 100 parts by weight of the monomer, bleeding or bloom may appear on the molded product, and the appearance may be impaired.

The surfactant used in the present invention includes, for example, alkyl sulfates such as sodium lauryl sulfate and sodium myristyl sulfate, and alkylaryl sulfonates such as sodium dodecylbenzenesulfonate and potassium dodecylbenzenesulfonate. , Sodium dioctyl sulfosuccinate,
Anionic surfactants such as sulfosuccinate salts such as sodium dihexyl sulfosuccinate, fatty acid salts such as ammonium laurate and potassium stearate, anionic surfactants such as polyoxyethylene alkyl sulfate salts and polyoxyethylene alkyl aryl sulfate salts, sorbitan mono Oleates, sorbitan esters such as polyoxyethylene sorbitan monostearate,
Hydrophilic nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl esters, and cationic surfactants such as cetyl pyridinium chloride and cetyl trimethyl ammonium bromide Among them, particularly preferred are polyoxyethylene alkylaryl sulfate salts. These surfactants may be used alone or in combination of two or more, and the amount of the surfactant may be 0.05 to 5.0 parts by weight per 100 parts by weight of the monomer. More preferably, the amount is 0.2 to 4.0 parts by weight per 100 parts by weight of the monomer. Although a dispersant such as polyvinyl alcohol, carboxymethyl cellulose, gelatin, and sodium polyacrylate may be used in combination with the surfactant, the secondary cohesion of the resin powder obtained at the time of spray drying is large and tends to become hard. There may be a problem depending on the application.

The plasticizer (B) of the present invention can be used as a plasticizer as long as it does not impair the effects of the present invention.
For example, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, di- (2-ethylhexyl) phthalate, di-n-octyl phthalate, diisobutyl phthalate, diheptyl phthalate, diphenyl phthalate, diisodecyl phthalate, ditridecyl phthalate, diundecyl phthalate, di ( Heptyl, nonyl,
Undecyl) phthalate, butylbenzyl phthalate,
Phthalic acid derivatives such as dinonyl phthalate and dicyclohexyl phthalate; di-n-butyl adipate;
Adipic acid derivatives such as (2-ethylhexyl) adipate, diisodecyl adipate, diisononyl adipate, azelaic acid derivatives such as di- (2-ethylhexyl) azelate, diisooctyl azelate, di-n-hexyl azelate, di-n- Butyl sebacate, di-
Sebacic acid derivatives such as (2-ethylhexyl) sebacate, di-n-butyl maleate, dimethyl maleate, diethyl maleate, di- (2-ethylhexyl)
Maleic acid derivatives such as maleate, tri- (2-ethylhexyl) trimellitate, tri-n-octyl trimellitate, triisodecyl trimellitate, triisooctyl trimellitate, and tri-n-hexyl trimellitate; Pyromellitic acid derivatives such as melitic acid derivative, tetra- (2-ethylhexyl) pyromellitate, tetra-n-octyl pyromellitate, triethyl citrate, tri-n-butyl citrate, acetyl triethyl citrate, acetyl tri- (2 -Ethylhexyl) citrate and other citric acid derivatives, triethyl phosphate, tributyl phosphate, tri- (2-
Ethylhexyl) phosphate, tributoxyethyl phosphate, triphenyl phosphate, cresyl diphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, tris (chloroethyl) phosphate and other phosphoric acid derivatives, triethylene glycol di- (2-ethylhexanoate) Ethyl), glycol derivatives such as dibutylmethylenebisthioglycolate, glycerol monoacetate, glycerol triacetate,
Glycerin derivatives such as glycerol tributyrate,
Epoxidized soybean oil, epoxy derivatives such as epoxybutyl stearate, epoxy triglyceride, epoxidized octyl oleate, polyester plasticizers such as adipic acid-based polyester, sebacic acid-based polyester, and phthalic acid-based polyester, and further diallyl phthalate, acrylic Polymerizable plasticizers such as monomers and oligomers, etc., but alkyl phthalate plasticizers and phosphate ester plasticizers are preferably benzoate esters because their compatibility with the acrylic resin may be insufficient depending on the application. It is a system plasticizer.

The benzoic acid ester is an ester compound of benzoic acid and a diol. Benzoic acid used in the synthesis of the ester includes toluic acid, dimethylbenzoic acid,
Also included are benzoic acid derivatives such as ethylbenzoic acid, cumic acid, tetramethylbenzoic acid, and the like. The number of carbon atoms in the alkyl group of the diol used for the synthesis of the ester compound is preferably 3 to 12 in view of the initial viscosity and viscosity stability of the plastisol composition.

Examples of the diol include 1,3 butanediol, 3,5 methylpentanediol, 2methyl 1,8 octane diol, 1,9 nonane diol,
10 decanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol (molecular weight 200 to 600), propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, polypropylene glycol (molecular weight 300 to 800) and the like. These may be used in combination. In order to improve the viscosity stability of the plastisol composition while maintaining the compatibility between the benzoic acid ester and the particulate acrylic resin, the diol component of the ester is particularly preferably an alkylene ether glycol.

In this method for producing a benzoic acid ester, benzoic acid, a diol and an esterification reaction catalyst are charged, and can be easily synthesized by a usual esterification reaction. Esterification of benzoic acid and diol is at least benzoic acid,
Since it is necessary to form an ester bond with one of the diols, the charging ratio of benzoic acid to diol is preferably 1 to 2.5 mol of benzoic acid per 1 mol of diol. Therefore, the benzoic acid ester of the present invention refers to a mixed or single compound in which benzoic acid is ester-bonded to both terminals of a diol and / or one terminal of the diol. Further, a small amount of a solvent may be added to facilitate the esterification reaction.

One of these plasticizers may be used or 2
A combination of two or more species may be used, and a plasticizer in which a high molecular compound such as rubber or resin is dissolved may be used arbitrarily.

The plasticizer (B) of the present invention is preferably used in an amount of 50 to 150 parts by weight based on 100 parts by weight of the particulate acrylic resin (A).
Parts by weight, particularly preferably 80 to 120 parts by weight.

The plastisol composition contains other additives conventionally used in vinyl chloride resin plastisols, for example, heat stabilizers, fillers, foaming agents, foaming accelerators, surfactants, thickeners, and adhesion-imparting agents. Agents, pigments, diluents, ultraviolet absorbers, antioxidants, reinforcing agents, and other resins.

Examples of the filler include calcium carbonate, mica, talc, kaolin clay, celite, asbestos, perlite, baryta, silica, silica sand, flaky graphite, dolomite limestone, gypsum, aluminum fine powder, hollow balloon and the like. No.

Examples of the foaming agent used to obtain the foam include azo foaming agents such as azodicarbonamide and azobisformamide, dinitrosopentamethylenetetramine, benzenesulfonylhydrazide, toluenesulfonylhydrazide, p, p'-Hydroxybenzenesulfonyl hydrazide and the like, as the foaming accelerator, for example, zinc oxide, lead stearate, cadmium stearate, zinc stearate, barium stearate, sodium-based, potassium-based compounds, urea and the like . In order to obtain a fine foam having a uniform cell diameter and a rigid cell thickness, the smaller the particle diameter of the foaming agent, the more preferable. In order to efficiently obtain an optimum bubble diameter of 0.1 to 0.6 mm, preferably about 0.3 mm, particularly against the back pressure in the matrix polymer, it is 20 μm or less, preferably 10 μm or less.
Those having a homogeneous particle size of less than μm are advantageous. Further, in order to obtain a good cell structure, a surfactant can be used in combination.

Examples of the thickener include silicic acids such as silicic anhydride and hydrous silicic acid, inorganic fine particles such as calcium carbonate, organic / inorganic composite thixotroping agents, bentonites such as organic bentonite, and silodex. Organic thixotropic agents such as asbestos and dibenzylidene sorbitol are exemplified.

As the ultraviolet absorber, a benzotriazole type is preferable, for example, 2- (2′-hydroxy-5 ′).
-Methylphenyl) benzotriazole, 2- (2'-
(Hydroxy-3′-tert-butyl-5′-methylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′, 5′-ditert-butylphenyl) -5
-Chloro-benzotriazole, 2- (2'-hydroxy-4'-octoxyphenyl) benzotriazole and the like, and hindered amine light stabilizers and the like can also be suitably used.

The antioxidant is preferably a phenolic antioxidant, for example, 2,6-ditert-butyl-
p-cresol, 2,2′-methylenebis (4-methyl-
6-tert-butylphenol), 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), 4,4′-thiobis (3-methyl-6-tert-butylphenol) and the like can be used.

The method for preparing the plastisol composition is not particularly limited, and a method conventionally used for preparing a plastisol can be used. For example, the plastisol composition of the present invention is obtained by sufficiently mixing and stirring the resin particles, the plasticizer and other optional components used as desired using a known mixer such as a planetary mixer, a kneader, or a roll. Can be prepared. The plastisol composition thus obtained can be made to have a low viscosity because resin particles having a large particle diameter are used as compared with conventional plastisols, and the number of plasticizer parts is reduced, thereby obtaining a harder molded product. For example, it can be suitably used as a material such as a floor material, a wall covering material, a toy, an automobile interior material, a coated steel plate, a vibration damping steel plate, a laminated glass, a sealing material, and a foam.

[0035]

According to the present invention, a resin emulsion having a large particle size and a uniform particle size can be formed by one polymerization by forming the polymerizable monomer composition into uniform droplets using a film emulsifying apparatus. A sol molded article which can be produced and has excellent properties such as low viscosity, viscosity storage stability and mechanical strength of a plastisol in which a resin after spray drying is dispersed with a plasticizer, particularly excellent in viscosity storage stability is obtained.

[0036]

Next, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. In the following, all parts and percentages are by weight unless otherwise specified.

Reference Example 1 <Production of Polymerizable Monomer Composition by Membrane Emulsion Apparatus> 450 parts of deionized water and a polyoxyethylene alkylaryl sulfate (Revenol WZ:
8 parts of a surfactant-containing aqueous medium was circulated, and 100 parts of methyl methacrylate, 0.5 part of lauroyl peroxide, and 3 parts of lauryl alcohol were circulated.
The dispersed phase was pressed through a tubular porous glass membrane (MPG membrane) with 0.3 micron pores. A polymerizable monomer composition having a uniform droplet diameter and an average particle diameter of 2.8 μm was obtained.

<Production of Aqueous Polymer Dispersion (A)> The polymerizable monomer composition obtained above was placed in a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen inlet, a thermometer, and a dropping funnel. 560 parts of the dispersion liquid was charged, and the temperature was raised to 80 ° C. while blowing nitrogen. While maintaining the temperature inside the reaction vessel at 70 ± 2 ° C, 8
The polymerization took place over time. Thereafter, the content was cooled, adjusted to PH6 with ammonia water, and the solid component concentration was adjusted to 17.
The mixture was adjusted to 0% with deionized water, and filtered with a 100 mesh wire mesh. In order to evaluate the resin particle size in the obtained latex, the average particle size was measured by a laser type particle size distribution analyzer (manufactured by HORIBA, Ltd .: HORIBA LA-910). The deviation is 1.
It was 035 μm, and the resin particles of 1 μm or less were 0.1% or less and were not substantially present.

Subsequently, the reaction liquid thus obtained was
It was dried with an atomizer type spray dryer to obtain a powdery acrylic resin [S1]. The obtained acrylic resin [S
1] has a molecular weight of 800,000 and an electron microscope (JEOL Ltd.)
The particle size of the resin after spray drying, as observed in (1): 20 to 40 μm
m.

Reference Example 2 <Production of Acrylic Resin by Conventional Emulsion Polymerization Method> 450 parts of deionized water, 8 parts of polyoxyethylene alkylaryl sulfate (Levenol WZ), 100 parts of methyl methacrylate, 0 parts of lauroyl peroxide .5 copies,
A polymerizable monomer composition comprising 3 parts of lauryl alcohol was homogenized (TK homomixer: Tokushu Kiki Co., Ltd.)
Was stirred at 5000 rpm for 10 minutes. Subsequently, the aqueous dispersion 5 of the polymerizable monomer composition thus obtained was prepared.
60 parts, stirrer, reflux cooling pipe, nitrogen introduction pipe, thermometer,
The mixture was placed in a reaction vessel equipped with a dropping funnel and heated to 80 ° C. while blowing nitrogen. The polymerization was carried out for 8 hours while maintaining the temperature inside the reaction vessel at 70 ± 2 ° C. Thereafter, the content was cooled, adjusted to PH6 with ammonia water, and further adjusted with deionized water so that the solid concentration became 17.0%.
The mixture was filtered through a 0 mesh wire mesh. In order to evaluate the resin particle size in the obtained latex, a laser type particle size distribution measuring device (HORIBALA-910, manufactured by Horiba, Ltd.)
As a result, the average particle size was 7.4 μm, the standard deviation was 15.05 μm, and 3.1% of resin particles having a size of 1 μm or less were present.

Subsequently, the reaction liquid thus obtained was
The powder was dried with an atomizer type spray dryer to obtain a powdery acrylic resin [S2]. The obtained acrylic resin [S
2] has a molecular weight of 550,000 and an electron microscope (JEOL Ltd.)
The particle size of the resin after spray drying, as observed in :), is 15 to 50 μm.
m.

Example 1 Resin [S1] 10 of Reference Example 1
To 0 parts, 80 parts by weight of tripropylene glycol dibenzoate was added, and the mixture was kneaded at room temperature for 10 minutes with a crusher. Then, the mixture was transferred to a 1000 ml beaker, and air mixed under reduced pressure was defoamed and removed. An acrylic resin-based plastisol composition was prepared.

With respect to the obtained acrylic resin-based plastisol composition, an initial viscosity measurement, a viscosity stability test, a sheeting test, and a compatibility test were performed to evaluate performance, and the results are shown in Table 1. The test method is as follows. First, a part of the obtained plastisol composition was transferred to a 200 ml beaker and used for initial viscosity measurement and viscosity stability test, and the rest was used for sheeting test and compatibility test.

<Viscosity measurement> (A) Initial viscosity: 2 hours after the preparation of the plastisol composition
After being left in a constant temperature room at 25 ° C., measurement was performed with a BM type viscometer. The unit was expressed in poise. If the plastisol has a viscosity of 500 poise or more, molding is difficult.

(B) Viscosity stability test: The plastisol composition whose initial viscosity was measured was left in a constant temperature room at 20 ° C., and the viscosity after 7 days was measured in the same manner as in (a) above. The viscosity increase ratio (referred to as AI) of the viscosity after standing for a day was determined. It should be noted that the closer the AI is to 1, the more excellent the plastisol is the viscosity stability, and the more the AI is 2.5.
These have problems in stable molding.

Sheeting test: The plastisol composition was cast on a glass plate to a thickness of 0.5 mm, melt-gelled under the conditions of 180 ° C. × 10 minutes to form a sheet, and then obtained after cooling. The sheet was removed from the glass plate and used as a measurement sample.

(Sheet Strength Test) A test piece was punched out from the sheet prepared in the sheeting test into a JIS No. 3 dumbbell mold, and the breaking strength in a tensile test was measured under the following conditions.

Tensile tester: Autograph A manufactured by Shimadzu Corporation
G-5000C Tensile speed (crosshead speed); 200 mm / min. Distance between chucks; 50 mm

(Evaluation Criteria for Sheeting Test) A: A sheet having sufficient strength and elongation was obtained. Δ: A sheet was obtained, but either strength or elongation was insufficient.

×: No sheet was obtained.

Example 2 Reference Example 1 in Example 1
Instead of mixing 80 parts by weight of tripropylene glycol dibenzoate with 100 parts of the resin [S1],
An acrylic resin-based plastisol composition was prepared in the same manner as in Example 1 except that 0 part was blended. Performance of the obtained acrylic resin-based plastisol composition was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 2 Reference Example 1 in Example 1
100 parts of resin [S1] of Reference Example 2
An acrylic resin-based plastisol composition was prepared in the same manner as in Example 1, except that 0 part was used. Performance of the obtained acrylic resin-based plastisol composition was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[0053]

[Table 1] In the examples, the storage stability of the sol was better and the balance of physical properties after heating and gelation was better than in the comparative example.

[0054]

The synthetic resin for plastisol of the present invention can be produced by a single fine suspension polymerization after the droplet diameter of the polymerizable monomer composition is homogenized using a film emulsifying apparatus. Or repeated polymerization of the seed, or using a homogenizer to reduce the droplet diameter of the polymerizable monomer composition, and then compared to the synthetic resin for plastisol produced by fine suspension polymerization, the resin particle size Since the distribution is narrow and there are no extremely fine particles, various properties such as low viscosity, viscosity storage stability and mechanical strength of plastisol in which the resin after spray drying is dispersed with a plasticizer, especially viscosity storage stability A sol molded product excellent in quality can be obtained.

Claims (6)

[Claims] 1. An acrylic resin-based plastisol composition comprising a particulate acrylic resin (A) and a plasticizer (B), wherein the particulate acrylic resin (A) is an acrylic polymerizable monomer, A plastisol composition, which is a resin obtained by passing a mixed solution comprising a radical polymerization initiator, a surfactant, an aqueous medium, and the like through a membrane emulsification apparatus and subjecting the mixture to fine suspension polymerization. 2. The plastisol composition according to claim 1, wherein the membrane emulsifier comprises a porous glass membrane having uniform pores of 0.1 to 5 μm. 3. The method according to claim 1, wherein the average droplet diameter of the mixture droplets passed through the membrane emulsifying device is 0.5 to 5 μm, and substantially no droplets of 0.5 μm or less are present. A plastisol composition as described. 4. The powdery acrylic resin (A) has an average primary particle size of 0.5 to 10 μm and a particle size of 0.5 μm.
The plastisol composition of claim 1, wherein the composition is substantially free of primary particles less than m. 5. The plastisol composition according to claim 1, wherein the plasticizer (B) is a benzoate. 6. A molded article using the plastisol composition according to claim 1.