JPH1036606A - Vinyl chloride resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vinyl chloride resin composition which can give a molding having a uniform fine foamed cellular structure and a smooth skin and having high mechanical strengths, good woody texture and suitability as a further material. SOLUTION: This composition is prepared by mixing 100 pts.wt. vinyl chloride resin with 5-30 pts.wt. methacrylic ester resin comprising 65-88wt.% methyl methacrytlate, 35-12wt.% (meth)acrylate which can give a homopolymer having a glass transition point of -20 deg.C or below and optionally 0-10wt.% monomers copolymerizable therewith (the total is 100wt.%) and having a specific viscosity of 1.5-4.0, 0.1-3.0 pts.wt. heat-decomposable blowing agent and 5-150 pts.wt. wood flour having a mean particle diameter of 50-500μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vinyl chloride resin composition containing wood flour, and more particularly to a building material and a furniture material having a uniform and fine foamed cell structure and a smooth skin, and being rich in a wooden texture. The present invention relates to a vinyl chloride-based resin composition capable of providing a molded article suitable for a resin.

[0002]

2. Description of the Related Art Wood can be repeatedly produced by photosynthesis, and is therefore being reviewed as a promising resource that is different from petroleum-based resins. Attempts are being made to grow forests with fast-growing species and reduce the concentration of carbon dioxide in the atmosphere to restore a healthy global environment, while at the same time planning to cut down and use wood as a resource for human life. It is taking place.
Under these circumstances, we developed a vinyl chloride resin composition that is frequently used in building materials by blending wood flour with vinyl chloride resin, a general-purpose resin that has high mechanical strength and is easy to mold. If possible, a harmonious way to use earth resources will be greatly pioneered. 2. Description of the Related Art Conventionally, it is often practiced to mix wood powder with a vinyl chloride resin to form a wood-like appearance and tactile sensation. However, since a considerable amount of wood flour must be blended, there is a problem that mechanical strength such as tensile strength is greatly reduced, and a natural wood texture cannot be realized yet.

[0003] In order to improve the clarity of grain and the ease of processing, a vinyl chloride resin composition in which a urea resin is added in addition to wood flour has been proposed (JP-A-60-42007, JP-A-60-73807, JP-A-60-73
808). In addition, an inorganic filler such as mica in addition to wood flour, polyethylene, ethylene-vinyl acetate copolymer or a vinyl chloride resin composition to which an ABS resin is added,
It has been disclosed that the coefficient of linear expansion is small and the impact resistance and moldability are excellent (JP-A-60-192746 and JP-A-60-192747). However, these also lack the uniform mixing property of wood flour and the appearance of the woody texture of the molded product is insufficient. Dispersion uniformity was greatly improved by blending wood powder to which inorganic powder or plastic powder was attached during plastic processing (Japanese Patent Laid-Open No. 5-177).
No. 610, JP-A-5-261708), a resin molded product rich in woody feeling has not yet been obtained simply by blending such a wood powder with a vinyl chloride resin.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, the present invention provides a window having a uniform and fine foam cell structure and a smooth skin, and having a low mechanical strength, a rich woody feeling, and a window. An object of the present invention is to provide a vinyl chloride resin composition capable of providing a molded product suitable for building materials such as frames and furniture materials.

[0005]

Means for Solving the Problems The present inventors have solved the above-mentioned problems by blending wood powder with a vinyl chloride resin in the presence of a methacrylic ester resin having a specific composition as a processing aid. It has been found that the above object can be achieved by foam molding, and the present invention has been completed based on this finding. That is, the present invention relates to (A) vinyl chloride resin 10
0 parts by weight, (B) 65 to 88% by weight of methyl methacrylate and 35 to 12% by weight of (meth) acrylate having a glass transition point of -20 ° C or lower and a copolymer copolymerizable therewith as required. It is composed of a total of 100% by weight of monomer units of 0 to 10% by weight, and has a specific viscosity of 1.5.
5 to 30 parts by weight of a methacrylic acid ester-based resin having an average particle size of 50 to 500 μm, and (D) 0.1 to 3.0 parts by weight of a pyrolytic foaming agent. An object of the present invention is to provide a vinyl chloride resin composition containing parts by weight.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The vinyl chloride-based resin used as the component (A) in the composition of the present invention includes, in addition to a homopolymer of vinyl chloride, a copolymer containing 50% by weight or more of vinyl chloride as a main component. Examples of the comonomer in the case of the vinyl chloride copolymer include olefins such as ethylene and propylene; halogenated olefins such as allyl chloride, vinylidene chloride, vinyl fluoride, and ethylene trifluoride chloride; vinyl acetate; Carboxylic acid vinyl esters such as vinyl propionate; vinyl ethers such as isobutyl vinyl ether and cetyl vinyl ether; allyl-3-
Allyl ethers such as chloro-2-oxypropyl ether, allyl glycidyl ether; acrylic acid, maleic acid, itaconic acid, 2-hydroxyethyl acrylate, methyl methacrylate, monomethyl maleate, diethyl maleate, maleic anhydride, etc. Unsaturated carboxylic acids, esters or acid anhydrides thereof; unsaturated nitriles such as acrylonitrile and methacrylonitrile; acrylamide, N-methylolacrylamide, acrylamide-2-methylpropanesulfonic acid, (meth) acrylamidopropyltrimethylammonium chloride Acrylamides such as; allylamine benzoate;
Examples include allylamine such as diallyldimethylammonium chloride and derivatives thereof. The monomers exemplified above are only a part of the copolymerizable monomers, and are exemplified in “Polyvinyl Chloride” edited by Kinki Chemical Association Vinyl Subcommittee, Nikkan Kogyo Shimbun (1988), pp. 75-104. Various monomers can be used. Further, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl acrylate copolymer, resins such as chlorinated polyethylene, vinyl chloride or vinyl chloride and the copolymerizable monomer described above. And resins obtained by graft polymerization of These vinyl chloride resins may be produced by any conventionally known production method such as suspension polymerization, emulsion polymerization, solution polymerization, or bulk polymerization. The average polymerization degree is preferably from 400 to 1500, more preferably from 600 to 1600 according to the measurement method specified in JIS K6721.
Those in the range of ~ 1100 can be suitably used. If the average degree of polymerization of the vinyl chloride resin is smaller than 400, the expansion ratio tends to be difficult to increase, and
If it is larger than 0, many coarse cells may be mixed in the foam cells.

In the present invention, as the component (B), 65-88% by weight of methyl methacrylate, and a (meth) acrylate 35 having a glass transition point of a homopolymer of -20 ° C. or lower.
１２12% by weight and, if necessary, from 0 to 10% by weight of a comonomer copolymerizable therewith, comprising a total of 100% by weight of monomer units, and having a specific viscosity of 1.5 to 4.0. A methacrylic ester resin is used. Here, (meth) acrylate means acrylate or methacrylate. Examples of the (meth) acrylate that gives a homopolymer having a glass transition point of −20 ° C. or lower include, for example, ethyl acrylate (glass transition point of homopolymer of −22 ° C.), n-
Propyl acrylate (-52 ° C), n-butyl acrylate (-54 ° C), isobutyl acrylate (-24 ° C), n-octyl acrylate (-65 ° C)
C), 2-ethylhexyl acrylate (-85
C), methoxyethyl acrylate (-85C), ethoxyethyl acrylate (-50C), n-octyl methacrylate (-20C), n-decyl methacrylate (-65C), n-lauryl methacrylate ( -65 ° C), and these may be used alone or in combination of two or more. Especially,
n-Butyl acrylate is preferred. Examples of the monomer copolymerizable with methyl methacrylate or (meth) acrylate which gives a homopolymer having a glass transition point of −20 ° C. or lower include aromatic vinyl compounds such as styrene, vinyltoluene and α-methylstyrene. Vinyl cyanide compounds such as (meth) acrylonitrile and vinylidene cyanide; and 2-hydroxyethyl fumarate, hydroxybutyl vinyl ether, monobutyl maleate, glycidyl methacrylate, butoxyethyl methacrylate and the like.

[0008] The particle structure of the methacrylic acid ester resin as the component (B) may be a polymer composition obtained by a one-stage polymerization reaction and having a substantially uniform polymer composition inside the particles, or a so-called core-shell structure or the like. The polymer composition may be different for each layer. However, the monomer composition of the particles as a whole is from 65 to 88% by weight of methyl methacrylate units, preferably 70 to 88% by weight.
８５85% by weight, the glass transition point of the homopolymer is -20 ° C.
Hereinafter, 35 to 12% by weight, preferably 30 to 15% by weight, of (meth) acrylate units having a temperature of preferably -30 ° C or lower, and if necessary, a comonomer unit copolymerizable therewith with 0 to 0%. Contains 10% by weight, for a total of 100% by weight. When the content of the methyl methacrylate unit is less than 65% by weight, the expansion ratio of the foamed molded article does not increase, and conversely 88%.
If the content is more than 10% by weight, the compatibility with the wood powder of the methacrylic acid ester resin becomes poor, and the wood powder is agglomerated, and the size of the foam cells is not uniform, so that the molded article has an uneven composition. The particle structure of the methacrylate ester resin (B) is
Particles having a shell structure, wherein the core layer is a methyl methacrylate homopolymer or a (meth) acrylate unit having a methyl methacrylate unit content of 70% by weight or more and a glass transition point of the homopolymer of -20 ° C or less. The shell layer is composed of a copolymer containing 20 to 50% by weight of a (meth) acrylate unit having a glass transition point of −20 ° C. or less of a homopolymer. It is preferable that the amount of the (meth) acrylate unit in the copolymer constituting the layer is larger than the amount of the (meth) acrylate in the copolymer constituting the core layer. That is, in the production of the methacrylate resin as the component (B), the latex coagulation after polymerization is, for example, 55%.
In addition to the advantage of being able to be carried out at a relatively low temperature of up to 80 ° C., the core-shell particles are easy to adjust to wood flour and the uniformity of mixing and dispersion is improved during the preparation of the composition, so that the uniformity of the foam molded article is further improved. be able to.

When the particle structure of the component (B) methacrylate resin is a core-shell particle, the weight ratio of the core to the shell is preferably from 1/1 to 15/1.
The methacrylic acid ester resin used as the component (B) is a chloroform solution 10 in which 0.2 gr is dissolved.
The specific viscosity of 0 ml at 25 ° C. needs to be 1.5 to 4.0, and preferably 2.0 to 3.0. When the specific viscosity is less than 1.5, the surface of the molded article becomes rough, and when it exceeds 4.0, time is required for uniform melting. For adjusting the specific viscosity, a general method such as selection of a polymerization reaction temperature and use of a chain transfer agent such as t-dodecyl mercaptan and carbon tetrachloride can be adopted. The methacrylate ester resin as the component (B) improves the melt viscosity characteristics of the vinyl chloride resin, uniformly disperses the wood flour in the vinyl chloride resin, maintains the film strength of the foam cell, and makes it hard to break. Has an action. The amount of the component (B) in the present invention is preferably 5 to 30 parts by weight, more preferably 10 to 2 parts by weight, per 100 parts by weight of the vinyl chloride resin of the component (A).
0 parts by weight. When the blending amount of the component (B) is less than 5 parts by weight, the holding strength of the film strength at the time of foaming becomes weak, and the foam cells are easily broken. On the other hand, if the amount exceeds 30 parts by weight, the melt viscosity increases, the heat generation increases, and the resin tends to be thermally degraded, and the size of the foam cells tends to be uneven.

As the thermal decomposition type foaming agent which is the component (C) of the composition of the present invention, a thermal decomposition type organic foaming agent and / or a thermal decomposition type inorganic foaming agent are used. Examples of the former are N,
N'-dinitrosopentamethylenetetramine, N, N '
-Nitroso compounds such as -dimethyl-N, N'-dinitrosoterephthalamide; azo compounds such as azodicarbonamide, azobisisobutyronitrile, benzenesulfonylhydrazide, p, p'-oxybis (benzenesulfonylhydrazide), and toluenesulfonylhydrazide And the like. Examples of the latter include sodium bicarbonate, ammonium bicarbonate, ammonium carbonate and the like. In the present invention, one or more kinds selected from the group of the organic or / and inorganic pyrolytic foaming agents described above can be used. In the present invention, it is inappropriate to heat and volatilize low-boiling organic compounds such as trifluoromethane and petroleum ether for use as a blowing agent. This is because the foam cells become coarse, and it becomes difficult for the molded product to be nailed or screwed, and may not be suitable for building materials. In the present invention, the compounding amount of the thermal decomposition type foaming agent of the component (C) is 100 parts of the vinyl chloride resin of the component (A).
It is preferably 0.1 to 3.0 parts by weight, more preferably 0.5 to 1.5 parts by weight per part by weight. If the amount of the component (C) is less than 0.1 part by weight, the resulting molded article tends to lack a woody feeling due to a low expansion ratio, and if it is more than 3.0 parts by weight, the molded article surface will be poor. Tends to be rough and the surface hardness tends to decrease.

In the present invention, as the component (D), wood powder having an average particle size of 50 to 500 μm is contained in an amount of 5 to 150 parts by weight, preferably 22 to 120 parts by weight, per 100 parts by weight of the vinyl chloride resin (A). More preferably, 25 to 100 parts by weight are used. If the amount of the wood flour is less than 5 parts by weight, it is difficult for the molded article to exhibit a woody feeling, and if it exceeds 150 parts by weight, the molded article becomes brittle. In the present invention, by mixing the component (B), wood flour can be reduced to 20%.
Even if blended in a high number of parts exceeding the weight part, it has good familiarity with the vinyl chloride resin and can be dispersed uniformly, so it has a uniform fine foam cell and a smooth skin by foam molding, and also has a strong wooden texture It can be expressed. The species of wood flour used in the present invention is not particularly limited, and coniferous or hardwood timber pieces such as cedar, hemlock and lauan, and wood such as planing and sawdust can be used. In order to obtain the component (D) of the present invention from such wood, for example, the wood is preferably made into a relatively round wood powder having an average particle diameter of 500 μm or less by a pulverizer. The wood flour used in the present invention may be one in which hard small particles are adhered to the surface disclosed in JP-A-5-177610 and JP-A-5-261708. Hard small particles are particles whose hardness is greater than wood flour and whose average particle size is smaller than the average particle size of wood flour, such as metals, metal oxides and metal salts, inorganic oxides and plastic particles. Is mentioned. Preferred component (D) is wood flour having metal or inorganic particles such as titanium oxide, nickel, calcium carbonate, silica, and mica adhered to the surface. The mode in which the hard small particles adhere to the surface of the wood flour includes hard small particles such as an entanglement bond including biting of the hard small particles into the wood flour, and a pinch bond between a plurality of hard small particles that are bite-bonded. Adhesion by pressing against the surface of the wood powder may be applied, or hard small particles may be attached to the wood powder by an adhesive. In this case, the wood powder is charged together with 1 to 50% by weight of hard small particles in a ball mill or the like, and subjected to a treatment for preventing dust explosion such as in a nitrogen atmosphere.

The average particle size of the component (D) used in the present invention is 50 to 500 μm, preferably 30 to 100 μm. Here, the average particle size refers to a reading of the value of the mesh corresponding to 50% by weight by obtaining a cumulative weight% curve with respect to the mesh by sieve analysis of the powder. (D) The average particle size of the component is 50μ.
If it is less than m, the bulk specific gravity becomes small and the mixing operability for preparing the composition becomes poor, and if it is more than 500 μm, the molded article surface becomes rough and the foaming ratio decreases. The water content of the component (D) is preferably 10% by weight or less, more preferably 5% by weight or less. In the composition of the present invention,
In addition to the above components, in addition to heat stabilizers and lubricants used during the processing of ordinary vinyl chloride resin, ultraviolet absorbers,
An impact resistance enhancer, a pigment, a plasticizer, an antistatic agent and the like are appropriately added.

In order to prepare the composition of the present invention, first, components (A), (B) and (D) excluding the pyrolytic foaming agent of component (C) are mixed together by a Henschel mixer or the like. The temperature is increased to 120 to 160 ° C. with vigorous stirring and mixing. In this mixing process, the moisture absorbed in the wood flour is volatilized. When the above temperature is reached, the mixture is transferred to a cooling mixer, and the temperature is reduced to 50 to 60 ° C. after adding the pyrolytic foaming agent of the component (C). The removed powdery mixture can be used as a molding compound as it is, but is usually then pelletized. As a preferable method for producing pellets, a twin-screw extruder is used,
A method of producing pellets at a temperature of about 170 ° C. and discharging residual moisture in wood flour through a vent hole. In the above method for preparing the composition of the present invention, the bulk components are large and the additives such as pigments are uniformly dispersed by adding and mixing all components except the foaming agent at the time of initial mixing with a Henschel mixer or the like. A mixture can be obtained. A molding method for obtaining a vinyl chloride resin molded product similar to natural wood using the composition of the present invention is not particularly limited, but usually an extrusion molding method is employed.

The embodiments of the present invention are described below. (1) (A) 100 parts by weight of a vinyl chloride resin, (B) 65 to 88% by weight of methyl methacrylate, 35 to 12% by weight of a (meth) acrylate having a glass transition point of a homopolymer of −20 ° C. or less. Methacrylic acid ester resin 5 comprising a total of 100% by weight of monomer units of 0 to 10% by weight of comonomers copolymerizable therewith and having a specific viscosity of 1.5 to 4.0 To 25 parts by weight, (C) 0.1 to 3.0 parts by weight of a pyrolytic foaming agent, and (D) an average particle size of 50 to 50 parts by weight.
A vinyl chloride resin composition containing 5-150 parts by weight of wood powder of 500 μm. (2) The average degree of polymerization of the vinyl chloride resin is 400 to 150.
The vinyl chloride resin composition according to the above (1), wherein 0 is 0. (3) The methacrylic ester-based resin is 0.2 gr
(1) or (2) above, wherein the specific viscosity at 25 ° C. of 100 ml of a chloroform solution in which is dissolved is 2.0 to 3.0.
Vinyl chloride resin composition. (4) The methacrylate resin is a particle having a core-shell structure, wherein the core layer is a homopolymer of methyl methacrylate or 70% by weight or more of a methyl methacrylate unit, and a glass transition point of the homopolymer. Is -20
The shell layer is composed of a copolymer containing 30% by weight or less of a (meth) acrylate unit having a glass transition point of -20 ° C or less of 20 to 50% by weight. % Of the (meth) acrylate unit in the copolymer constituting the shell layer, wherein the amount of the (meth) acrylate unit in the copolymer constituting the shell layer is larger than the amount of the (meth) acrylate in the copolymer constituting the core layer. Certain of the above (1)-
The vinyl chloride resin composition according to any one of (3). (5) The vinyl chloride resin composition according to any one of the above (1) to (4), wherein the weight ratio of the core to the shell is 1/1 to 15/1. (6) The compounding amount of wood powder having an average particle size of 50 to 500 μm is 22
The vinyl chloride resin composition according to any one of the above (1) to (5), wherein the composition is １２０120 parts by weight.

[0015]

EXAMPLES Next, the resin composition of the present invention will be specifically described with reference to examples and comparative examples, but the present invention is not limited to these examples. In addition, the number of parts and% are based on weight. Methacrylic ester resins A to G were prepared as follows. The specific viscosity of each resin was determined by taking a sample from 100 ml of a chloroform solution in which 0.2 gr of the resin was dissolved.
It was measured at 25 ° C.

Production Example 1 of Methacrylic Ester Resin 1 60 parts of methyl methacrylate were placed in a stainless steel reactor.
-15 parts of butyl acrylate, 1 part of sodium alkyl sulfate having 12 to 18 carbon atoms, 0.1 part of potassium persulfate
And 150 parts of water, and the mixture was stirred at a polymerization temperature of 55 ° C.
Was used to carry out emulsion polymerization. After confirming the completion of the reaction based on the solid content concentration of the sampled reaction solution, 15 parts of methacrylate and 10 parts of n-butyl acrylate were added to the obtained latex (using polymer particles as seeds), and then the mixture was heated at 55 ° C. The polymerization is completed to complete the reaction.
0.2% latex was obtained. The resulting latex was salted out by adding aluminum sulfate under heating, dehydrated, washed, and dried to obtain resin A. Table 1 shows the composition and specific viscosity of the resin A.

Preparation Example 2 of Methacrylic Ester Resin A total of 30 parts of ethyl acrylate was used in place of 25 parts of n-butyl acrylate, and 55 parts of methyl methacrylate and 20 parts of ethyl acrylate were used as monomers to be added during the first stage polymerization. Parts, and 0.1 parts of a chain transfer agent t-dodecylmercaptan was added, and 15 parts of methyl methacrylate and 10 parts of ethyl acrylate were used as monomers to be added at the time of the second polymerization. Was carried out in the same manner as in Production Example 1 of methacrylic acid ester resin, to obtain resin B. Table 1 shows the composition and specific viscosity of the resin B.

Production Example 3 of Methacrylate Resin 3 In place of 25 parts of n-butyl acrylate, 20 parts of n-butyl methacrylate (glass transition point of homopolymer: 20 ° C.)
Parts, and 65 parts of methyl methacrylate and 10 parts of n-butyl methacrylate were used as monomers to be added during the first polymerization, and 0.03 part of t-dodecyl mercaptan was added. 15 parts of methyl methacrylate and n-
Resin C was obtained in the same manner as in Production Example 1 of the methacrylate resin except that 10 parts of butyl methacrylate was used. Table 1 shows the composition and specific viscosity of the resin C.

Production Example 4 of Methacrylic Ester Resin In a stainless steel reactor, 93 parts of methyl methacrylate, 7 parts of ethyl acrylate, and 0.1 part of t-dodecyl mercaptan were added.
Addition of 05 parts, 1 part of sodium alkyl sulfate having 12 to 18 carbon atoms, 0.1 part of potassium persulfate and 150 parts of water, emulsion polymerization at 70 ° C. with stirring, and solid content of the sampled reaction solution Completion of the reaction was confirmed by the concentration. The resulting latex is added with aluminum sulfate under heating, salted out, dehydrated, washed and dried to obtain resin D
I got Table 1 shows the composition and specific viscosity of Resin D.

Production Example 5 of Methacrylic Ester Resin Resin 60 parts of methyl methacrylate and 40 parts of n-butyl acrylate were used as monomers for the polymerization reaction, and t-
Resin E was obtained in the same manner as in Production Example 4 of the methacrylate resin except that the amount of dodecyl mercaptan was changed to 0.07 part. Table 1 shows the composition and specific viscosity of the resin E.

Production Example 6 of methacrylic acid ester resin 75 parts of methyl methacrylate as a monomer for polymerization reaction,
Resin F was prepared in the same manner as in Production Example 4 of the methacrylate resin except that 25 parts of n-butyl acrylate was used and the amount of t-dodecyl mercaptan was 0.20 part.
I got Table 1 shows the composition and specific viscosity of the resin F.

Production Example 7 of Methacrylic Ester Resin No t-dodecylmercaptan was added, and instead of 0.1 part of potassium persulfate as a radical initiator, 0.20 part of cumene hydroperoxide and sodium formaldehyde sulfoxy were used. The procedure was the same as in Production Example 6 of the methacrylic ester resin except that the reaction temperature was 5 ° C., and the reaction temperature was 5 ° C., using 0.1 part of a rate, 0.02 part of ethylenediaminetetraacetic acid iron and 0.01 part of ethylenediaminetetraacetate. Thus, a resin G was obtained. Table 1 shows the composition and specific viscosity of the resin G.

The properties of the foam molded article were examined by the following methods. 1) Foam Cell State The cut surface of the molded product is observed with an optical microscope and evaluated according to the following rank. A: The cell is fine and uniform with a cell diameter of 100 μm or less. B: Some cells are broken and coarse. C: Many cells are broken and coarse. D: Most of the broken and coarse cells. 2) Molded product surface properties The surface of the molded product is visually observed and touched, and evaluated according to the following rank. A: Smooth B: Some shark skin C: Shark skin D: Many granular protrusions. 3) True specific gravity and molded product specific gravity Measured by the underwater substitution method according to JIS K 7112. 4) Molding product expansion ratio Using the specific gravity value obtained by the above measurement, the expansion ratio is determined by the following equation. Expansion ratio = true specific gravity / specific gravity of molded product 5) Tensile strength Tensile speed of 10 mm with JIS K 7113 No. 1 test piece
/ Min.

Examples 1 to 3 and Comparative Examples 1 to 8 The components and types shown in Table 2 were blended in a Henschel mixer in the following manner. Water vapor was volatilized while charging and mixing a vinyl chloride resin, a methacrylate resin (except for Comparative Example 1), wood flour, a heat stabilizer, a lubricant, a filler, and a pigment. When the temperature rose to 140 ° C., the mixture was transferred to a cooling mixer, a foaming agent was added while mixing, and the temperature was lowered to 60 ° C. The obtained powdery mixture was formed into pellets under the following conditions using a single screw extruder having a cylinder diameter of 65 mm. In addition, the moisture remaining in the wood powder was volatilized from the vent hole. Screw: L / D = 24, compression ratio 2.5, rotation speed 30
rpm Set temperature: C ₁ = 130 ° C., C ₂ = 140 ° C., C ₃ =
150 ° C. C ₄ = 160 ° C., head 160 ° C., die 160 ° C. Dice: 3 mmφ pellet × 12 holes Land length: 10 mm The pellet thus obtained was extruded and foamed by a uniaxial extruder having a cylinder diameter of 40 mm under the following conditions. . Table 1 shows the characteristics of the molded product. Screw: L / D = 22, compression ratio 2.5, rotation speed 25
rpm Set temperature: C ₁ = 140 ° C., C ₂ = 160 ° C., C ₃ =
170 ° C. C ₄ = 180 ° C., head 160 ° C., D ₁ = 160 ° C. D ₂ = 160 ° C. Dice: thickness 4 mm width × 50 mm belt land length: 5 mm

[0025]

[Table 1]

Note MMA methyl methacrylate nBA n-butyl acrylate EA ethyl acrylate nBMA n-butyl methacrylate

[0027]

[Table 2]

Note * 1 ZEST700L, manufactured by Shin-Daiichi PVC Co., Ltd., vinyl chloride resin, average degree of polymerization 680 * 2 Selund, manufactured by Shimada Shokai, wood flour, average particle size 80 μm, moisture 5% by weight * 3 Wood powder with titanium oxide particles, manufactured by Misawa Techno Co., Ltd.
E60-T5-3, titanium oxide content 5% by weight, average particle size 60 μm, water content 5% * 4 Tribasic lead sulfate / lead stearate composite heat stabilizer * 5 Polyethylene wax * 6 Calcium carbonate CCR, Shiraishi calcium (stock)
* 7 Carbon black (TPH0012, manufactured by Toyo Ink Mfg. Co., Ltd.) / Condensed azo red (TXH4360,
Company pigment) / Bisazo Yellow (TXH2110, Company) composite pigment

In Examples 1 to 3, which were molded using the composition having the requirements of the present invention, molded articles having satisfactory foam cell conditions and surface properties, sufficient foaming ratio, and satisfactory tensile strength was gotten. In Comparative Example 1 in which the methacrylic acid ester-based resin was not blended, the foam cell state, the surface properties, and the expansion ratio were all poor.

As a methacrylate resin, a resin C containing a comonomer unit having a glass transition point higher than a specified range or a copolymer having a glass transition point within a specified range has a small content. In Comparative Example 2 or 3 using Resin D, the foam cells became coarse, the expansion ratio did not increase, and the surface of the molded product was shark-skinned. When a methacrylate resin E containing a comonomer having a glass transition point in a specified range in a larger amount than a specified ratio is used, the expansion ratio is high but the expanded cells are rough, the surface properties are rough, and the tensile strength is poor. (Comparative Example 4). Even if the specific viscosity is out of the specified range, even if it is a methacrylic acid ester-based resin containing a specified amount of a comonomer having a specified glass transition temperature, even if it is small or large, the foamed cell state and the molded product surface are rough. Molded articles were obtained (Comparative Examples 5 and 6). If the amount of the methacrylic acid ester-based resin was too small or too large, foamed cells or molded articles having significantly rough surfaces were obtained (Comparative Examples 7 and 8).

[0031]

EFFECT OF THE INVENTION By using the composition of the present invention, a molding suitable for building materials and furniture materials having a uniform and fine foamed cell structure and a smooth skin, and having a sufficient wooden strength and sufficient mechanical strength. Goods are obtained.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Shinichi Akaya 1-2-1 Kawasaki-ku, Kawasaki-ku, Kawasaki, Kanagawa Prefecture Inside the ZEON Kasei Co., Ltd.Kawasaki Research Laboratories (72) Inventor Toshiya Kobayashi, Kanagawa No. 2 ZEON Kasei Co., Ltd. Kawasaki Laboratory

Claims (1)

[Claims] (A) 100 parts by weight of a vinyl chloride resin,
(B) 65 to 88% by weight of methyl methacrylate, 35 to 12% by weight of (meth) acrylate having a glass transition point of a homopolymer of -20 ° C. or less, and a comonomer 0 copolymerizable therewith if necessary. 100% by weight in total of 10% by weight
5 to 30 parts by weight of a methacrylic acid ester resin having a specific viscosity of 1.5 to 4.0, comprising (C)
A vinyl chloride resin composition comprising 0.1 to 3.0 parts by weight of a pyrolytic foaming agent and 5 to 150 parts by weight of wood powder (D) having an average particle size of 50 to 500 μm.