JP2000281858A - Acrylic resin plastisol composition for injection molding and injection molding using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acrylic resin plastisol composition for injection molding capable of molding without cooling a mold in injection molding and injection molding method using it. SOLUTION: This composition includes (A) an acrylic resin having glass transition temperature >=60 deg.C comprising (a) 5-96 wt.% of parts soluble in tetrahydrofuran and 95-4 wt.% of the parts insoluble in tetrahydrofuran and the weight average molecular weight of the part soluble in tetrahydrofuran is 50,000-9,000,000, or (b) comprising tetrahydrofuran soluble polymer having weight average molecular weight of 300,000-9,000,000 and (B) a plasticizer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an acrylic resin plastisol composition for injection molding and an injection molding method using the same.

[0002]

2. Description of the Related Art Injection molding of a thermoplastic resin is usually performed by using a pellet, which is heated and melted, followed by injection molding. An exception is the use of a blastisol which is a liquid material other than the pellet as a raw material. Exceptions [For example, foam injection molding technology using vinyl chloride resin plastisol
No. 110113)]]. In such cases, the material is not allowed to warm in the injection molding steps and must be injected at room temperature. This is because when heated, the plasticizer is absorbed by the resin and loses fluidity. The molding cycle involves first injecting a liquid plastisol into the mold at room temperature, heating the mold rapidly after injection, promoting gelation and molding of the liquid material, and molding after molding to prevent deformation. The article must be demolded after cooling to below the glass transition temperature (Tg) of the material.

[0003] Before and after such a rapid injection process,
There is a problem that high productivity is not utilized because cooling needs to be repeated.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a novel acrylic resin plastisol composition for injection molding which can be removed without cooling the mold in injection molding of plastisol, and an injection using the same. It is to provide a molding method.

[0005]

Means for Solving the Problems The first aspect of the present invention is that (A)
A glass transition temperature of 60 ° C. or higher, (a) a tetrahydrofuran-soluble component of 5 to 96% by weight and a tetrahydrofuran-insoluble component of 95 to 4% by weight, and a weight average molecular weight of the tetrahydrofuran-soluble component of 50,000 to 9 , 00
An acrylic resin having a weight-average molecular weight of 300,000 to 9,000,000, and (B) a plasticizer. And an acrylic resin plastisol composition for injection molding.

A second aspect of the present invention is to provide the acrylic resin plastisol composition for injection molding according to claim 1 at room temperature and at a temperature of 10%.
Injection molding of an acrylic resin plastisol composition for injection molding, characterized by injecting into a mold at 100 to 100 ° C., molding by heating to 150 to 250 ° C., and then removing the molded product without cooling from the mold. About the method.

The acrylic resin in the present invention is a resin comprising a polymer having an ester of an alkyl alcohol having 1 to 8 carbon atoms and acrylic acid or methacrylic acid as a main constituent monomer, and has a glass transition temperature. Is 60 ° C
It is higher and specific examples of the monomer include methyl methacrylate (glass transition temperature in the case of a homopolymer (the same applies hereinafter): 105 ° C.), ethyl methacrylate (65 ° C.), and isopropyl methacrylate (81 ° C.) ,
t-butyl methacrylate (107 ° C.) and the like. These monomers should account for 50% by weight or more based on all monomers forming the polymer. If it is less than 50% by weight, the type of plasticizer that can be used is limited, and the plastisol composition of the present invention is heated,
It causes the strength of the molded product obtained by molding to be greatly reduced.

The acrylic resin which is the component (A) of the present invention has a glass transition temperature of 60 ° C. or higher, preferably 70 ° C. or higher, particularly preferably 80 ° C. or higher. If the glass transition temperature is below 60 ° C,
Demoldability during heating and mold stain resistance tend to deteriorate. In the case where the resin particles have a core-shell structure, if the glass transition temperature of the polymer constituting the shell satisfies the condition of 60 ° C. or higher, the glass transition temperature of the core polymer is, for example, −20.
It may be as low as ° C.

In the case of an acrylic resin which is one of the components (A) and comprises 5 to 96% by weight of a tetrahydrofuran-soluble component and 95 to 4% by weight of a tetrahydrofuran-insoluble component, the weight-average molecular weight of the tetrahydrofuran-soluble component Is 5
000-9,000,000, preferably 100,
000 to 6,000,000, particularly preferably 50
It needs to be in the range of 000 to 4,000,000. When the weight average molecular weight is 50,000 or less, the demolding property is deteriorated, which is not preferable. If it is more than 9,000,000, the gelling property tends to be poor. Further, when the tetrahydrofuran-soluble component is out of the predetermined range, it is difficult to achieve both mold release without cooling the mold and strength of the final molded product.

In the case of an acrylic resin consisting only of a tetrahydrofuran-soluble component, which is one of the components (A),
Its weight average molecular weight is 300,000-9,000,000.
00, preferably 500,000 to 9,000,000.
0, particularly preferably 1,000,000 to 6,000
It needs to be 0000. When the weight average molecular weight is smaller than the predetermined range, the releasability tends to deteriorate, and when the weight average molecular weight is larger than the predetermined range, the gelling property tends to deteriorate.

95-4% by weight of tetrahydrofuran insoluble matter
In order to obtain the acrylic resin (a), it is necessary to copolymerize the polyfunctional monomer with the acrylic acid or methacrylic acid ester. In this case, the polyfunctional monomer may be used in an amount sufficient to form a necessary amount of a tetrahydrofuran-insoluble component. Preferably 0.5 to 15% by weight
(For all monomers).

Examples of the polyfunctional monomer include diallyl phthalate, diallyl malate, diallyl adipate,
Allyl glycidyl ether, triallyl cyanurate,
Ethylene glycol divinyl ether, ethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, trimethylolpropane di (meth)
Examples include acrylate, trimethylolpropane tri (meth) acrylate, hexanediol di (meth) acrylate, oligoethylene di (meth) acrylate, and glycidyl (meth) acrylate.

In order to obtain the acrylic resin of the present invention, if necessary, 50% by weight of the constituent monomer unit may be used.
Less than the third monomer can also be used. Examples of these monomers include (meth) acrylate compounds such as 2-ethylhexyl methacrylate, butyl acrylate, cyclohexyl methacrylate, and phenyl methacrylate; aromatic vinyl compounds such as styrene, vinyl toluene, and α-methyl styrene; Vinyl cyanide compounds such as (meth) acrylonitrile and vinylidene cyanide; vinyl ester compounds such as vinyl acetate and vinyl propionate; vinyl ether compounds such as ethyl vinyl ether, cetyl vinyl ether and hydroxybutyl vinyl ether; α-hydroxyethyl (meth) acrylate; Examples include 3-hydroxybutyl (meth) acrylate, 2-hydroxyethyl fumarate, monobutyl malate, butoxyethyl (meth) acrylate, and vinyl chloride. I can do it.

Among these acrylic resins, methacrylate resins containing at least 50% by weight of methyl methacrylate are preferred.

The acrylic resin of the present invention preferably has an average single particle size of 0.05 to 5.0 μm, more preferably 0.3 to 3.0 μm. The method for measuring the average single particle diameter is as follows: a resin powder is dispersed in water, and the resultant is applied to an ultrasonic shaker having an oscillation frequency of 50 kHz for 1 minute. The particle diameter at which the cumulative value becomes 50% is determined as the average single particle diameter. The reason why the average single particle diameter in the above range is preferable is that a low viscosity is obtained in forming a plastisol by suspending in a plasticizer, and the degree of freedom in practical formulation is widened.

In order to produce the above-mentioned polymer particles, an emulsion polymerization method including seeded emulsion polymerization or a fine suspension polymerization method including seeded fine suspension polymerization is preferred.

In the emulsion polymerization, water is used as a dispersion medium, an anionic or nonionic surfactant is used as an emulsifier, and a water-soluble peroxide is used as a polymerization initiator. While performing, the monomer is emulsified into fine droplets by the action of the surfactant, and polymerization is advanced in the surfactant micelle layer surrounding the monomer, and the particle size is 0.05 to 0.5.
A microsphere resin of about μm is obtained as latex. In order to obtain particles from the latex, spray drying is usually performed.

In order to obtain a latex of particles having a particle size even larger than that of the emulsion polymerization method, the prepolymerized latex is used as a seed, and the amount of the emulsifier is adjusted to the theoretical amount of 20 to cover the entire surface area of the polymer particles. Seed emulsion polymerization is performed in which the polymerization is carried out while maintaining the content at 〜60% to prevent the formation of new microparticles and perform the coating polymerization for thickening only the seed particles.

As another method for obtaining a paste resin latex, water is used as a dispersion medium, and a monomer, an emulsifier,
A mixture of an oil-soluble polymerization initiator and the like is dispersed in fine droplets using a homogenizer or the like, and then polymerized and then subjected to fine suspension polymerization or a suspension of the polymer obtained by the fine suspension polymerization. Seeding fine suspension polymerization, which further performs coating polymerization, has also been performed.

In these emulsion polymerization, seeded emulsion polymerization, fine suspension polymerization or seeded fine suspension polymerization, a stirrer is used to remove heat of reaction accompanying the polymerization reaction and to supply monomers to the reaction site. Is performed. If the stirring is too weak, heat cannot be removed and the reaction temperature rises, causing quality and safety problems, and the reaction is delayed because monomers are not effectively supplied to the polymerization reaction site. And conversely,
If it is too strong, it will aggregate the growing and growing polymer particles to form scales and coarse particles, or impair the mechanical stability of the latex, and sometimes the cream-like content tends to accumulate heat. Raises safety and safety concerns.

Examples of the emulsifier used for emulsion polymerization include alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate; alkyl sulfates such as sodium lauryl sulfate and sodium tetradecyl sulfate; sulfosuccinates such as sodium dioctyl sulfosuccinate and sodium dihexyl sulfosuccinate. Acid salts; fatty acid salts such as sodium laurate and semi-hardened tallow fatty acid potassium; ethoxy sulfate salts such as sodium polyoxyethylene lauryl ether sulfate and sodium polyoxyethylene nonylphenyl ether sulfate; alkane sulfonates; alkyl ether phosphates Sodium salt; nonionic interface such as polyoxyethylene nonylphenyl ether, polyoxyethylene sorbitan lauryl ester Mention may be made of the gender agents, and the like. The emulsifier may be added only at the initial stage, or may be additionally added in accordance with the progress of polymerization in order to enlarge the particle size.The amount used is 0.05 to 100 parts by weight of the monomer. It is preferably 5 parts by weight, more preferably 0.1 to 3 parts by weight. Examples of the water-soluble polymerization initiator include, for example, water-soluble peroxides such as potassium persulfate, ammonium persulfate, and hydrogen peroxide; these initiators; cumene hydroperoxide; and hydroperoxides such as t-butyl hydroperoxide. Redox initiators, which are combined with reducing agents such as sodium acid sulfite, ammonium sulfite, ascorbic acid, 2,2 '
Water-soluble azo compounds such as -azobis (2-methylpropionamidine) dihydrochloride.

In the seed emulsion polymerization, pure water is added to a polymerization vessel.
A seed polymer, a water-soluble polymerization initiator, etc. are charged and deaeration in the polymerization vessel or, if necessary, replacement with an inert gas such as nitrogen is carried out. A mixture of monomers that can be polymerized is charged, and the temperature in the polymerization vessel is increased while gently stirring to initiate polymerization. The polymerization temperature is preferably from 30 to 80C.
Stabilization of the polymer particles is achieved by adding an emulsifier in an aqueous solution in such an amount that does not cover the surface of the particles that enlarge as the reaction progresses after the initiation of the polymerization. Examples of the water-soluble polymerization initiator and the emulsifier include the same ones as those used in the emulsion polymerization.

In the fine suspension polymerization, an acrylic monomer or a mixture of an acrylic monomer and an unsaturated monomer copolymerizable therewith, an oil-soluble polymerization initiator, an emulsifier, If necessary, a polymerization aid such as a higher fatty acid and other additives are added and premixed, and the mixture is homogenized with a homogenizer to adjust the particle diameter of oil droplets. As the homogenizer, for example, a colloid mill, a vibration stirrer, a two-stage high-pressure pump, or the like can be used. The homogenized solution is sent to a polymerization vessel, the temperature inside the polymerization vessel is increased while gently stirring to start a polymerization reaction, and thereafter polymerization is performed until a predetermined conversion is reached. The polymerization temperature is preferably from 30 to 80C.

Examples of the oil-soluble polymerization initiator include diacyl peroxides such as acetyl peroxide, 3,5,5-trimethylhexanoyl peroxide, lauroyl peroxide and benzoyl peroxide; ketone peroxides such as methyl ethyl ketone peroxide. Benzoyl hydroperoxide, cumene hydroperoxide, p
Hydroperoxides such as cumene hydroperoxide, diisopropylbenzene hydroperoxide and p-cymene hydroperoxide; peroxyesters such as t-butylperoxybivalate; diisopropylperoxydicarbonate, diethylhexylperoxydicarbonate and the like Peroxydicarbonate; organic peroxides such as sulfonyl peroxides such as acetylcyclohexylsulfonyl peroxide; redox polymerization initiators obtained by combining these organic peroxides with reducing agents such as Rongalite; 2,2′- Azobisisobutyronitrile, 2,
2'-azobis (2-methylbutyronitrile), 2,
2'-azobis (2,4-dimethylvaleronitrile),
Azo compounds such as 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile) can be mentioned. Examples of the emulsifier include those similar to the emulsifier used in the emulsion polymerization.

In the seeded fine suspension polymerization, pure water and a seed polymer or the like in which a polymerization initiator remains in particles are charged into a polymerization vessel, and degassed in the polymerization vessel or an inert gas such as nitrogen if necessary. And a mixture of an emulsifier and an acrylic monomer or an acrylic monomer and a monomer copolymerizable therewith is charged, and the temperature in the polymerization vessel is increased with gentle stirring to initiate polymerization. . The polymerization temperature is preferably from 30 to 80C. Examples of the emulsifier include those similar to the emulsifier used in the emulsion polymerization. In the case of seeded fine suspension polymerization, it is not necessary to newly add a polymerization initiator.

The latex containing acrylic polymer particles produced by emulsion polymerization, fine suspension polymerization or the like is usually dried by spray drying using an inert gas such as nitrogen to obtain an acrylic resin.

The plasticizer used in the present invention is a plasticizer corresponding to the resin used in the present invention. Therefore, it is a plasticizer suitable for plasticizing the acrylic resin, specifically,
Dimethyl phthalate, diethyl phthalate, dibutyl phthalate, di- (2-ethylhexyl) phthalate, di-n-octyl phthalate, diisobutyl phthalate,
Phthalic acid derivatives such as dihexyl phthalate, diheptyl phthalate, diisononyl phthalate, diphenyl phthalate, diisodecyl phthalate, ditridecyl phthalate, diundecyl phthalate, dibenzyl phthalate, butyl benzyl phthalate, octyl benzyl phthalate, dinonyl phthalate, and dicyclohexyl phthalate; Isophthalic acid derivatives such as phthalate, di- (2-ethylhexyl) isophthalate and diisooctyl isophthalate; tetrahydrophthalic acid derivatives such as di-2-ethylhexyl tetrahydrophthalate, di-n-octyl tetrahydrophthalate and diisodecyl tetrahydrophthalate; -N-butyl adipate, di- (2-ethylhexyl) adipate, diisodecyl adipate Adipic acid derivatives such as diisononyl adipate, azelaic acid derivatives such as di- (2-ethylhexyl) azelate, diisooctyl azelate, di-n-hexyl azelate, di-n-butyl sebacate, di- (2-ethylhexyl) sebacate Maleic acid derivatives such as sebacic acid derivatives such as di-n-butylmalate, dimethylmalate, diethylmalate and di- (2-ethylhexyl) malate; di-n-butylmalate and di- (2-ethylhexyl) fumarate; Fumaric acid derivative, tri- (2-ethylhexyl) trimellitate, tri-n-octyl trimellitate, triisodecyl trimellitate, triisooctyl trimellitate, tri-n-hexyl trimellitate, triisononyl trimellitate Trimelli such as tate Acid derivatives, pyro-mellitic acid derivatives such as tetra- (2-ethylhexyl) pyromellitate, tetra-n-octyl pyromellitate, triethyl citrate, tri-n-butyl citrate, acetyl triethyl citrate, acetyl tributyl citrate, Citric acid derivatives such as acetyl tri- (2-ethylhexyl) citrate, monomethyl itaconate, monobutyl itaconate, dimethyl itaconate, diethyl itaconate, dibutyl itaconate,
Itaconic acid derivatives such as di- (2-ethylhexyl) itaconate, oleic acid derivatives such as butyl oleate, glyceryl monooleate and diethylene glycol monooleate, methyl acetyl ricinolate, butyl acetyl ricinolate, glyceryl monoricinolate and diethylene glycol monoricinolate Ricinoleic acid derivatives, n-butyl stearate, glycerin monostearate, stearic acid derivatives such as diethylene glycol distearate, diethylene glycol monolaurate, diethylene glycol diperargonate, other fatty acid derivatives such as pentaerythritol fatty acid ester, triethyl phosphate, Tributyl phosphate, tri- (2-ethylhexyl) phosphate, tributoxyethyl phosphate Chromatography, triphenyl phosphate, cresyl diphenyl phosphate, tricresyl phosphate, phosphoric acid derivatives such as diphenyl decyl phosphate, trixylenyl phosphate, tris (chloroethyl) phosphate, diethylene glycol dibenzoate, dipropylene glycol dibenzoate,
Glycol derivatives such as triethylene glycol dibenzoate, triethylene glycol di- (2-ethylbutyrate), triethylene glycol di- (2-ethylhexoate), dibutylmethylenebisthioglycolate, glycerol monoacetate, glycerol triacetate Glycerol derivatives such as glycerol tributyrate, epoxidized soybean oil, epoxybutyl stearate, di-2-ethylhexyl epoxyhexahydrophthalate, diisodecyl epoxyhexahydrophthalate,
Epoxy derivatives such as epoxy triglyceride, epoxidized octyl oleate, epoxidized decyl oleate, polyester plasticizers such as adipic acid polyester, sebacic polyester, and phthalic polyester, or partially hydrogenated terphenyl, adhesive plastic Agent,
Further, polymerizable plasticizers such as diallyl phthalate and acrylic monomers and oligomers may be mentioned. Among them, benzyl phthalate such as butyl benzyl phthalate and octyl benzyl phthalate, tricresyl phosphate, diphenyl decyl phosphate Phosphate-based phosphate esters, acetyl tributyl citrate, citrate esters such as tributyl citrate, dipropyl dibenzoate, dibenzoate esters such as diethyl dibenzoate, sebacate esters, polyesters, and the like are preferable. is there. One of these plasticizers may be used, or two or more thereof may be used in combination. A plasticizer in which a high molecular compound such as a rubber or a resin is dissolved can also be used arbitrarily. The amount used is usually from 60 to 140 parts by weight based on 100 parts by weight of the acrylic resin.
Parts by weight, preferably 70 to 120 parts by weight.

The acrylic resin plastisol composition of the present invention is prepared by dispersing and mixing the (A) component acrylic resin with the (B) component plasticizer. The mixer is not particularly limited, and a crusher, a kneader, a planetary mixer, a horizontal paddle mixer, a butterfly mixer, a dissolver, an intensive mixer, or the like is used. At this time, a pigment, a filler, a foaming agent, an antistatic agent, a diluent, and the like are added as necessary.

The injection molding method of the present invention comprises the steps of: heating the acrylic resin plastisol composition of the present invention at room temperature without heating;
Injected into a mold at 0-100 ° C. and heated to 150-250 ° C. for a time sufficient for the plastisol composition to gel,
Usually, molding is performed by keeping the same state for about 40 to 120 seconds, and then without cooling the mold, that is, at a temperature of 1
The molded product is released from the mold at 00 to 180 ° C. Conventionally, in the case of a plastisol composition of a vinyl chloride resin, the mold is always cooled and then removed from the mold, so this point is a great difference, which is an extremely great advantage industrially.

The main application of the molding method of the present invention is injection insert molding. In particular, when the object to be inserted has low heat resistance, a complicated shape, a fine shape (for example, porous), a low strength, and the like,
The present method of injecting a plastisol at room temperature and at low pressure is advantageous because it is difficult or impossible to integrate a melt of high viscosity at high temperatures.

[0031]

The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples. Methyl methacrylate resins a to j and a styrene resin k were prepared by the method of the following production example.

<Production Example of Methacrylate Polymer (Resin a)> A stainless steel container was charged with 150 parts by weight of deionized water and deaerated, and 100 parts by weight of methyl methacrylate as a methacrylate monomer and dodecylbenzene sulfone as an emulsifier. After adding 1.0 part by weight of acid soda, 1.5 parts by weight of a higher alcohol having 18 carbon atoms as a dispersant and 0.3 part by weight of benzoyl peroxide as a polymerization initiator, and stirring and mixing at room temperature for 30 minutes, The mixture was homogenized under high shear by a homomixer and transferred to a stainless steel polymerization vessel to prepare a fine suspension having a droplet diameter of an oil phase of 1 to 5 μm. Subsequently, polymerization was carried out with stirring at a polymerization temperature of 65 ° C. for 5 hours, and after confirming a polymerization rate of 92% based on the solid content of the reaction solution sampled in a small amount, the reaction was terminated to obtain a latex. The latex was dried with a spray dryer in a nitrogen stream at 170 ° C. The average single particle diameter of the polymer resin particles thus obtained was 1.8 μm. The glass transition temperature determined by a differential thermal analyzer was 105 ° C.
Other polymer properties are shown in Table 1.

<Production Example of Methacrylate Polymer (Resin b)> 150 parts by weight of deionized water was put into a stainless steel container and degassed, and 1.2 parts by weight of sodium alkyl sulfate having an alkyl group having 12 carbon atoms was prepared. 0.8 parts by weight of lauryl alcohol, 0.3 parts by weight of lauroyl peroxide, 100 parts by weight of methyl methacrylate and 0.6 part by weight of t-dodecyl mercaptan were charged at room temperature to give 30 parts.
After minute mixing, the mixture was homogenized with a homogenizer and transferred to a stainless steel reactor. The reactor was heated to maintain the reaction temperature at 65 ° C. to carry out a polymerization reaction. After confirming a polymerization rate of 92% based on the solid concentration of the reaction liquid sampled in a small amount, the reaction was terminated to obtain a latex. The latex was dried with a spray dryer in a nitrogen stream at 170 ° C. The average single particle diameter of the polymer resin particles thus obtained was 0.7 μm. Other polymer properties are shown in Table 1.

<Production Example of Methacrylate Polymer (Resin c)> A stainless steel reactor capable of using a refrigerant was charged with 200 parts by weight of deionized water and degassed, and 100 parts by weight of methyl methacrylate and 0.5 part by weight of potassium oleate were added. Parts, sodium pyrophosphate 0.05 parts by weight, ferrous sulfate 0.00
1 part by weight, 0.002 parts by weight of ethylenediaminetetraacetic acid,
Formaldehyde sodium sulfoxylate 0.05
Parts by weight and 0.15 parts by weight of cumene hydroperoxide were added, and polymerization was carried out at 0 ° C. for 18 hours with stirring. Was completed to obtain a latex. The latex was dried by a spray dryer with a nitrogen stream at 170 ° C. The average single particle diameter of the polymer resin particles thus obtained was 0.1 μm. Other polymer properties are shown in Table 1.

<Production Example of Methacrylate Polymer (Resin d)> Except that 96 parts by weight of methyl methacrylate and 4 parts by weight of tetraethylene glycol dimethacrylate were used as the methacrylate monomer, Performed similarly. The average single particle diameter of the polymer resin particles was 1.7 μm. Other polymer properties are shown in Table 1.

<Production example of methacrylate-based polymer (resin e)> The same procedure as in the production example of methacrylate-based polymer (resin a) was carried out except that 93 parts by weight of methyl methacrylate and 7 parts by weight of glycidyl methacrylate were used as the methacrylate-based monomer. Was. The average single particle diameter of the polymer resin particles was 2.4 μm. Other polymer properties are shown in Table 1.

<Production Example of Methacrylate Polymer (Resin f)> In addition to 98 parts by weight of methyl methacrylate, 2 parts by weight of glycidyl methacrylate and 1.0 part by weight of a chain transfer agent t-dodecyl mercaptan as methacrylate monomers. Was carried out in the same manner as in the methacrylate polymer production example (resin a). The average single particle diameter of the polymer resin particles was 1.4 μm. Other polymer properties are shown in Table 1.

<Production Example of Methacrylate Polymer (Resin g)> In addition to 98 parts by weight of methyl methacrylate, 2 parts by weight of methacrylic acid, and 0.1 part by weight of a chain transfer agent t-dodecylmercaptan as monomers for polymerization. Was polymerized in the same manner as in the methacrylate-based polymer production example (resin a). 5% of potassium hydroxide is added to the obtained polymer latex.
After adding 0.5 parts by weight of the solution, the solution was dried by spray drying in a nitrogen stream at 170 ° C. The average single particle diameter of the polymer resin particles was 1.0 μm. Other polymer properties are shown in Table 1.
Shown in

<Production Example of Methacrylate Polymer (Resin h)> In addition to 98 parts by weight of methyl methacrylate, 2 parts by weight of methacrylic acid, and 1.0 part by weight of a chain transfer agent t-dodecyl mercaptan were added as monomers for polymerization. Was polymerized in the same manner as in the methacrylate-based polymer production example (resin a). After 0.5 parts by weight of a 5% aqueous solution of potassium hydroxide was added to the obtained polymerized latex, it was dried by spray drying in a nitrogen stream at 170 ° C. The average single particle diameter of the polymer resin particles was 0.6 μm. Other polymer properties are shown in Table 1.
Shown in

<Production Example of Methacrylate-Based Polymer (Resin i)> A methacrylate-based polymer was produced in the same manner as in the production example of a methacrylate-based polymer (resin a) except that 88 parts by weight of methyl methacrylate and 12 parts by weight of trimethylolpropane trimethacrylate were used. Performed similarly. The average single particle diameter of the polymer resin particles was 1.4 μm. Other polymer properties are shown in Table 1.

<Example of Production of Methacrylate Polymer (Resin j)> In a stainless steel polymerization vessel, 0.5% by weight of polyvinyl alcohol having a degree of saponification of 80% and a degree of polymerization of 2,000, a methoxy group content of about 29%, and a thermal gel temperature of about 29% were used. 200 parts by weight of water in which 0.5% by weight of methylcellulose at 52 ° C. is dissolved are added, and while stirring at room temperature, 100 parts by weight of methyl methacrylate as a methacrylate monomer and 0.2 parts by weight of benzoyl peroxide as a polymerization initiator. Was further added, followed by polymerization at a polymerization temperature of 65 ° C. for 5 hours with stirring. After confirming a conversion of 91% based on the solid content of a small amount of the reaction solution, the reaction was terminated to obtain a slurry. . After the slurry was separated by filtration with a centrifugal dehydrator, it was dried in a hot-air circulation oven at 60 ° C. for 24 hours. The polymer resin particles thus obtained were subjected to a sieve classification method to determine a cumulative particle size distribution curve, and the average single particle diameter determined as a sieve opening giving a cumulative value of 50% was 34 μm. Other polymer properties are shown in Table 1.

<Styrene-based polymer production example (resin k)> 150 parts by weight of deionized water was put into a stainless steel container and degassed, and 65 parts by weight of styrene, 32 parts by weight of acrylonitrile, and methacrylic acid were used as monomers for polymerization. 3 parts by weight, 0.8 parts by weight of sodium dodecylbenzenesulfonate as an emulsifier,
1.5 parts by weight of a higher alcohol having 18 carbon atoms as a dispersant and 0.1 part of benzoyl peroxide as a polymerization initiator.
3 parts by weight, and the mixture was stirred and mixed at room temperature for 30 minutes. The mixture was homogenized under high shear of a homomixer, transferred to a stainless steel polymerization vessel, and the oil phase droplet diameter was 1 to 5 μm. The suspension was adjusted as a suspension. Subsequently, at a polymerization temperature of 75 ° C., 5
The polymerization was carried out under stirring for a period of time, and after confirming a polymerization rate of 92% based on the solid content concentration of the reaction solution sampled in a small amount, the reaction was terminated to obtain a latex. After adding 0.5 parts by weight of a 5% solution of potassium hydroxide to the latex,
It dried with the spray dryer of nitrogen stream of ° C. The average single particle diameter of the polymer resin particles thus obtained was 2.2 μm.
m. Other polymer properties are shown in Table 1.

<Production Example of Styrenic Polymer (Resin 1)> As a monomer for polymerization, 65 parts by weight of methyl methacrylate, n
The procedure was the same as in the methacrylate polymer production example (resin a) except that 35 parts by weight of -butyl acrylate was used. The average single particle diameter of the polymer resin particles was 2.3 μm.
Other polymer properties are shown in Table 1.

The polymers, plasticizers and other additives used in Examples and Comparative Examples of the present invention are shown in Tables 1 and 2 below.
Shown in

Examples 1 to 8, Comparative Examples 1 to 11 Types and amounts shown in Tables 3 and 5 (parts by weight × 100 g)
Was mixed with a 50-liter simultaneous defoaming planetary mixer for 15 minutes to prepare a plastisol. Using a vertical injection molding machine, the size of the molded product is 150 × 20
Inject into a 0 × 5 mm split mold at room temperature, then heat the mold at 180 ° C. for 60 seconds with electroheating, and then remove from the mold at a temperature of 130-180 ° C. without any particular cooling. Thus, a molded product was obtained. The compositions of the examples are shown in Table 3, the performance evaluations thereof are shown in Table 4, the compositions of the comparative examples are shown in Table 5, and the performance evaluations thereof are shown in Table 6.

The performance evaluation method in the present invention is as follows.

Method for Measuring Molecular Weight A resin sample (500 mg) subjected to vacuum drying at 40 ° C. and a degree of vacuum of −755 mmHg for 3 hours was added to 100 ml of tetrahydrofuran as a reagent, and dissolved at room temperature for 24 hours. GPC (Gel P
The measurement was carried out by measurement chromatography.

Measurement of THF-insoluble content 500 mg of a resin sample which had been subjected to vacuum drying at 40 ° C. and a vacuum of −755 mmHg for 3 hours was added to 50 ml of reagent tetrahydrofuran, dissolved at room temperature for 24 hours, and then centrifuged at 8,000 rpm. After being filtered for 10 minutes and dried by filtration at 60 ° C. for 24 hours, the weight was measured.

(3) Initial viscosity of sol (unit: poise) Each component (unit: g) used in the plastisol composition for injection molding described in the table of the examples was mixed at room temperature for 10 minutes with a crusher, and continuously mixed. Then, a plastisol was prepared by performing a defoaming treatment for 15 minutes using a vacuum stirring defoaming machine having a vacuum of -755 mmHg. After the defoaming, the sample was collected in a closed container, left at 23 ° C. for 1 hour, and then subjected to a viscosity measurement in a room at 23 ° C. and a humidity of 60%. Viscosity measurement is BROOKFI
M type of ELD viscometer, rotor No. 4 and 6 rp
m. 500 poise or less can be processed, 100 poise or less is desirable, and 50 poise or less is particularly desirable.

(4) Time of sol (no unit) The plastisol whose initial viscosity was measured was sealed and sealed at 23 ° C. for 1 hour.
After storing for a week, the viscosity was measured in a room at 23 ° C. and 60% humidity under the same conditions as the initial viscosity. The value obtained by dividing the viscosity measurement value after one week by the initial measurement value was used as an index of the sol viscosity change with time. In practice, 2.0 or less is a necessary condition, and 1.3 or less is particularly desirable.

(5) Gelling property The plastisol prepared under the same conditions as in (3) was 1 m thick.
m was applied to a 1 mm thick steel plate using a doctor knife. The sample was placed in a hot air circulating oven at 180 ° C for 6 minutes.
After heat-treated for 0 seconds and allowed to cool at room temperature, the gelled film was peeled off from the steel plate to a width of 25 mm, and the obtained film strength was regarded as gelling. ：: It is difficult to cut the film with human power, Δ: It can be easily cut with human power, ×: The film cannot be formed.

(6) Demoldability during heating A plastisol prepared under the same conditions as in (3) was 30 × 1
After flowing down into the groove of a 4 mm thick aluminum plate having a depth of engraving of 00 × 2 mm, the excess was scraped off with a knife. Immediately after the plate was heat-treated in a hot air circulating oven at 180 ° C. for 90 seconds, the mold release was examined using a paint knife, and the demolding property during heating was evaluated. ○: easy to remove, △: difficult to remove immediately after, but removable after 60 seconds, ×: impossible after 300 seconds

(7) Mold Contamination In the evaluation of (6), the mold contamination was evaluated by substitution based on the amount of the residual molded product adhered in the groove of the plate after the molded product was released from the mold. ：: No residual deposits, Δ: Very small residual deposits, ×:
High residual deposits

(8) Dimensional stability The molded product released from the mold in the evaluation of (6) was allowed to stand at room temperature for 4 hours, and a dimensional error from the mold size was measured. ○: dimensional error 0.2 mm or less, Δ: dimensional error 0.2 to
0.5 mm, x: dimensional error 0.5 mm or more

(9) Molding cycle (unit: seconds) The time required from the replenishment of the plastisol to the injection molding machine to the replenishment of the next batch of plastisol after injection, heat molding and demolding was measured in units of 10 seconds.

(10) Bleed A plastisol adjusted under the same conditions as in (3) was applied with a thickness of 2 m.
m was applied on a glass plate having a thickness of 0.5 mm using a doctor knife, and heat-treated in a hot air circulating oven at 180 ° C. for 10 minutes to produce a sheet. After leaving this sheet at room temperature for one week, the plasticizer oozing out on the sheet surface was visually inspected, and evaluated as bleed of the sheet.

(11) Sheet tensile strength (unit: kg / c)
m ² ) JIS K-67 using the sheet prepared in (10).
The tensile strength at 23 ° C. was measured by the method according to No. 23.

(12) Sheet elongation (unit:%) Simultaneously with the measurement of (11), the elongation at break was measured.

[0059]

[Table 1] Fine particles of thermoplastic resin MMA: methyl methacrylate BA: n-butyl acrylate 4EGMA: tetraethylene glycol dimethacrylate GMA: glycidyl methacrylate MAA: methacrylic acid TMPT: trimethylolpropane trimethacrylate ST: styrene AN: acrylonitrile VC: vinyl chloride VAc: vinyl acetate * 1 Vinyl resin, ZEST P21, manufactured by Shin-Daiichi PVC Co., Ltd. * 2: Vinyl chloride-vinyl acetate copolymer resin, ZE
ST P35J, Shin Daiichi PVC Co., Ltd.

[0060]

[Table 2] Plasticizers and additives

[0061]

[Table 3]

[0062]

[Table 4]

[0063]

[Table 5]

[0064]

[Table 6]

<Evaluation> Examples 1 to 8 Acryl resin plastisol compositions satisfying the requirements of the present invention, all of which exhibited excellent sol properties and molded article properties and realized a short molding cycle. Comparative Example 1 When a resin b consisting of only a tetrahydrofuran-soluble component and having a weight-average molecular weight smaller than that of the specification of the present invention is used, the mold release property under heat requires about 80 seconds after molding to release from the mold,
In addition, there were many residual deposits on the mold. Comparative Example 2 When a resin e consisting of only a tetrahydrofuran-soluble component and having a weight average molecular weight larger than the stipulation of the present invention was used, in the evaluation of gelling properties, the obtained sheet was insufficiently gelled and easily cut by hand. I was ready to do it. Comparative Example 3 When a resin f containing a tetrahydrofuran-insoluble content of 9% by weight but having a tetrahydrofuran-soluble component having a weight-average molecular weight smaller than the specification of the present invention is used, the resin is hot-detachable. It took seconds, there was a small amount of residual deposits on the mold, and the dimensional stability was slightly reduced. Comparative Example 4 When the resin h containing a small amount of the tetrahydrofuran-insoluble matter of 2% by weight and the weight average molecular weight of the tetrahydrofuran-soluble matter being smaller than the stipulation of the present invention is used, the resin can be demolded by heating and at room temperature for 5 minutes or more. Even if left alone, it could not be completely removed from the mold. Comparative Example 5 When the resin i consisting only of the tetrahydrofuran-soluble component was used, in the evaluation of the gelling property, the obtained sheet was insufficiently gelled and could be easily cut manually, and the molding cycle test exceeded 200 seconds. Comparative Examples 6 and 7 When the vinyl chloride resin was used, even if two types of plasticizers were tested, as a result of the gelling test, the formed film was in such a fragile state that it could not be peeled off from the steel plate. Comparative Example 8 When a vinyl chloride-vinyl acetate copolymer resin was used, in a gelling test, the formed film was brittle and could be easily cut by human power. Comparative Example 9 The resin powder used in Comparative Example 1 was replaced with the resin of Example 1 by 50%, but the result was almost the same as that of Comparative Example 1. Comparative Example 10 The substitution ratio of Comparative Example 9 was changed to 80% of the resin used in Example 1, but the mold contamination was equivalent to that of Comparative Example 1. Comparative Example 11 When the styrene-based resin k was used, the mold release property under heat and mold stain resistance were poor, and the tensile strength of the molded sheet was also low. Comparative Example 12 When a resin 1 consisting of only the tetrahydrofuran-soluble component and having a weight average molecular weight within the range specified in the present invention and having a glass transition temperature lower than the specified range was used, the formed film was fragile in the gelling test. Was not able to be peeled off from the steel sheet.

[0066]

As described above, the provision of the composition of the present invention improves the conventional disadvantage that the mold cannot be removed until the mold is cooled in plastisol molding, and the mold can be removed without cooling the mold. Since it can be molded, the productivity is extremely improved, and the effect on the industry is extremely remarkable.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masao Shigeno 3-17-3 Higashitateishi, Katsushika-ku, Tokyo Inside Kobayashi Katsushika Factory Co., Ltd. No. Kobayashi Katsushika Factory Co., Ltd. No. 2 F-term in ZEON Kasei Co., Ltd. Kawasaki Laboratory (reference) 4F206 AA21 AC06 AR064 JA07 JN43 JQ81 4J002 BG05W BG06W CD01X CD08X CD10X CD16X CF03X EH016 EH026 EH046 EH096 EH106 EH136 EH146 EW046 FA080 HA08

Claims (2)

[Claims] (A) having a glass transition temperature of 60 ° C. or more,
(A) a tetrahydrofuran-soluble content of 5 to 96% by weight and a tetrahydrofuran-insoluble content of 95 to 4% by weight,
In addition, the weight average molecular weight of the tetrahydrofuran-soluble component is 5
Acrylic resin which is from 000 to 9,000,000,
Alternatively, (b) it consists only of a tetrahydrofuran-soluble component and has a weight average molecular weight of 300,000 to 9000.
Acrylic resin which is 0.000, and (B) a plasticizer,
An acrylic resin plastisol composition for injection molding comprising: 2. The acrylic resin plastisol composition for injection molding according to claim 1 is injected at room temperature into a mold at a temperature of 10 to 100 ° C., and heated to 150 to 250 ° C. to form a molded product. An injection molding method of an acrylic resin plastisol composition for injection molding, which comprises removing the mold without cooling.