JP3778651B2 - Vinyl chloride resin composition - Google Patents

Description

こうして得られたペレットを、シリンダー径４０ｍｍの一軸押出機により下記条件にて押出発泡成形した。成形品の特性を表１に示す。

【００２５】
【表１】

【００２６】
注
ＭＭＡ メチルメタクリレート
ｎＢＡ ｎ−ブチルアクリレート
ＥＡ エチルアクリレート
ｎＢＭＡ ｎ−ブチルメタクリレート
【００２７】
【表２】

【００２８】
注
＊１ ＺＥＳＴ７００Ｌ、新第一塩ビ（株）製、塩化ビニル樹脂、平均重合 度６８０
＊２ セルユント、（株）シマダ商会製、木粉、平均粒径８０μｍ、水分５重量％
＊３ 酸化チタン粒付着木粉、ミサワテクノ（株）製、Ｅ６０−Ｔ５−３、酸化チタン含有量５重量％、平均粒径６０μｍ、含水率５％
＊４ 三塩基性硫酸鉛／ステアリン酸鉛複合熱安定剤
＊５ ポリエチレンワックス
＊６ 炭酸カルシウムＣＣＲ、白石カルシウム（株）製、平均粒径０．０８μｍ
＊７ カーボンブラック（ＴＰＨ００１２、東洋インキ製造株式会社製）／縮合アゾレッド（ＴＸＨ４３６０、同社製）／ビスアゾイエロー（ＴＸＨ２１１０、同社製）複合顔料
【００２９】
本発明の要件を備えた組成物を用いて成形した実施例１〜３では、発泡セル状態及び表面性状が良好で十分な発泡倍率を有し、かつ引張強さも満足される成形品が得られた。
メタクリル酸エステル系樹脂を配合しなかった比較例１では、発泡セル状態、表面性状及び発泡倍率いずれも悪かった。
【００３０】
メタクリル酸エステル系樹脂として、ガラス転移点が規定範囲より高い共単量体単位が含まれた樹脂Ｃや、ガラス転移点は規定範囲にある共重合体であっても含有量が少い樹脂Ｄを用いた比較例２又は３は発泡セルが粗くなり、発泡倍率が上がらず成形品表面も鮫肌状を帯びたものになった。また、規定範囲のガラス転移点を有する共単量体を規定比率より多く含有するメタクリル酸エステル系樹脂Ｅを用いると発泡倍率は高いが発泡セルが粗く、表面性状の荒れて引張り強さの劣った成形品を与えた（比較例４）。規定ガラス転移温度の共単量体を規定量含有するメタクリル酸エステル系樹脂であっても比粘度が規定範囲から外れると、小さくても又は大きくても、発泡セル状態や成形品表面が荒れた成形品が得られた（比較例５，６）。
メタクリル酸エステル系樹脂の配合量が少なすぎたり、又は多すぎたりすると発泡セル又は表面が著しく荒れた成形品を与えた（比較例７，８）。
【００３１】
【発明の効果】
本発明組成物を用いることにより、均一微細な発泡セル構造と平滑な表皮とを有し、しかも木質感に富んで十分な機械的強度を持つ、建材や家具材に適する成形品が得られる。[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a vinyl chloride resin composition blended with wood powder, and more specifically, it has a uniform fine cell structure and a smooth skin, and gives a molded article that is rich in wood texture and suitable for building materials and furniture materials. The present invention relates to a vinyl chloride resin composition that can be used.
  The present invention further relates to a method for producing the vinyl chloride resin composition.
[0002]
[Prior art]
Since wood can be repeatedly produced by photosynthesis, it is reviewed as a rich and promising resource different from petroleum resins. There is an attempt to nurture forests with fast-growing tree species and reduce the increased carbon dioxide concentration in the atmosphere to regenerate a healthy global environment, while at the same time systematically cutting and using wood as a resource for human life It is happening. Under these circumstances, we developed a vinyl chloride resin composition that is often used in building materials by blending wood powder with a vinyl chloride resin, which is a general-purpose resin with high mechanical strength and easy molding. If possible, a harmonious way of using earth resources will be cultivated.
Conventionally, for the purpose of producing an appearance and feel similar to wood, it is often performed by blending wood powder with vinyl chloride resin. However, since a considerable amount of wood flour must be blended, there are problems that mechanical strength such as tensile strength is greatly reduced, and natural wood texture has not been realized yet.
[0003]
In order to clarify the grain and improve the ease of processing, a vinyl chloride resin composition to which a urea resin is added in addition to wood flour has been proposed (Japanese Patent Laid-Open Nos. 60-42007 and 60). -73807, JP-A-60-73808). In addition to wood powder, vinyl chloride resin composition to which inorganic filler such as mica and polyethylene, ethylene-vinyl acetate copolymer or ABS resin are added has a low coefficient of linear expansion, impact resistance and moldability. (Japanese Unexamined Patent Publication Nos. 60-192746 and 60-192747). However, even with these, the wood powder is not uniformly mixed, and the wood texture of the molded product is insufficient.
Dispersing and homogenizing was greatly improved by blending wood powder with inorganic powder or plastic powder adhered during plastic processing (JP-A-5-177610, JP-A-5-261708). A resin molded product rich in wood texture has not yet been obtained only by blending the powder with the vinyl chloride resin.
[0004]
[Problems to be solved by the invention]
  In view of the above situation, the present invention has a uniform and fine foam cell structure and a smooth skin, and does not deteriorate in mechanical strength and is rich in wood texture, and is suitable for building materials such as window frames and furniture materials. Vinyl chloride resin composition capable of giving molded productAnd method for producing the vinyl chloride resin compositionIt was made for the purpose of providing.
[0005]
[Means for Solving the Problems]
  In order to solve the above problems, the present inventors have achieved the above object by blending wood powder with vinyl chloride resin in the presence of a methacrylic ester resin having a specific composition as a processing aid. Based on this finding, the present invention has been completed.
  Thus, in the present invention, first, (A) 100 parts by weight of vinyl chloride resin, (B) methyl methacrylate70-75(Meth) acrylate having a glass transition point of -20 ° C. or less by weight%.30-25It is composed of a total of 100% by weight of monomer units of 0% to 10% by weight and, if necessary, monomers copolymerizable therewith, and the specific viscosity is1.8-3.3Particles having a core-shell structure made of a methacrylic acid ester resin, the core layer of which is a methyl methacrylate homopolymer or a methyl methacrylate unit of 70% by weight or more, and the glass transition point of the homopolymer is − The (meth) acrylate unit is 30% by weight or less, and the shell layer of the (meth) acrylate unit having a glass transition point of -20 ° C or less is 20 to 20 ° C or less. The content ratio of the (meth) acrylate in the copolymer comprising 50% by weight of the copolymer, and the content ratio of the (meth) acrylate unit in the copolymer constituting the shell layer constituting the core layer More than 5 to 30 parts by weight of methacrylic ester resin particles, (C) 0.1 to 3.0 parts by weight of pyrolytic foaming agent, and (D) an average particle diameter of 50 to 5 By blending wood flour 5-150 parts by weight of 0μm to provide vinyl chloride resin composition.
  Secondly, the present invention includes (A) 100 parts by weight of vinyl chloride resin, (B) 5 to 30 parts by weight of methacrylic ester resin particles having the core-shell structure, and (D) an average particle diameter of 50 to 50 parts by weight. 5 to 150 parts by weight of 500 μm wood flour is put into a mixer and heated to 120 to 160 ° C. while stirring and mixing. When the temperature reaches the above temperature, (C) thermal decomposition is performed on the mixture. Provided is a method for producing a vinyl chloride resin composition, wherein 0.1 to 3.0 parts by weight of a mold foaming agent is added, and then the temperature is lowered.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
The vinyl chloride resin used as the component (A) in the composition of the present invention includes a vinyl chloride homopolymer and 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 ethers such as allyl-3-chloro-2-oxypropyl ether and allyl glycidyl ether; Acrylic acid, maleic acid, itaconic acid, Unsaturated carboxylic acids such as 2-hydroxyethyl acrylate, methyl methacrylate, monomethyl maleate, diethyl maleate and maleic anhydride, their esters or their anhydrides; unsaturated such as acrylonitrile and methacrylonitrile Toryls; Acrylamides such as acrylamide, N-methylolacrylamide, acrylamide-2-methylpropanesulfonic acid, (meth) acrylamidepropyltrimethylammonium chloride; Allylamines such as allylamine benzoate and diallyldimethylammonium chloride and derivatives thereof Can be mentioned. The monomers exemplified above are only a part of the copolymerizable monomers, and are exemplified in pages 75 to 104 of “Polyvinyl Chloride” Nikkan Kogyo Shimbun (1988) edited by the Kinki Chemical Association Vinyl Division. Various monomers can be used. In addition, a resin such as ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl acrylate copolymer, chlorinated polyethylene, vinyl chloride or vinyl chloride and a copolymerizable monomer as described above A resin obtained by graft polymerization is also included. These vinyl chloride resins may be produced by any conventionally known production method such as suspension polymerization, emulsion polymerization, solution polymerization, and bulk polymerization. The average degree of polymerization is preferably from 400 to 1500, more preferably from 600 to 1100 as measured by JIS K 6721. If the average degree of polymerization of the vinyl chloride resin is less than 400, the expansion ratio tends to be difficult to increase. Conversely, if the average polymerization degree is greater than 1500, many foamed cells may be mixed.
[0007]
  In the present invention, as the component (B), methyl methacrylate70-75(Meth) acrylate having a glass transition point of -20 ° C. or less by weight%.30-25It is composed of a total of 100% by weight of monomer units of 0% by weight to 10% by weight and, if necessary, monomers copolymerizable therewith, and has a specific viscosity of1.8-3.3Particles having a core-shell structure made of a methacrylic ester resin are used. The core layer of the methacrylic ester resin particles is composed of a methyl methacrylate homopolymer or a methyl methacrylate unit of 70% by weight or more, and a glass transition point of the homopolymer of −20 ° C. or less and a (meth) acrylate unit of 30% by weight. And the shell layer is made of a copolymer containing 20 to 50% by weight of (meth) acrylate units whose homopolymer has a glass transition point of -20 ° C. or less, and The content ratio of the (meth) acrylate unit in the copolymer constituting the shell layer is higher than the content ratio of the (meth) acrylate in the copolymer constituting the core layer.
  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 ethyl acrylate (glass transition point of homopolymer −22 ° C.), n-propyl acrylate (-52 ° C.), n -Butyl acrylate (same as -54 ° C), isobutyl acrylate (same as -24 ° C), n-octyl acrylate (same as -65 ° C), 2-ethylhexyl acrylate (same as -85 ° C), methoxyethyl acrylate (same as -85 ° C) Ethoxyethyl acrylate (same as −50 ° C.), n-octyl methacrylate (same as −20 ° C.), n-decyl methacrylate (same as −65 ° C.), n-lauryl methacrylate (same as −65 ° C.), etc. 1 type may be used and it may be used in combination of 2 or more types. In particular, n-butyl acrylate is preferable.
  Examples of the monomer copolymerizable with methyl methacrylate or (meth) acrylate that gives a homopolymer having a glass transition point of −20 ° C. or lower include aromatic vinyl compounds such as styrene, vinyl toluene, and α-methyl styrene. Vinyl cyanide compounds such as (meth) acrylonitrile and vinylidene cyanide; 2-hydroxyethyl fumarate, hydroxybutyl vinyl ether, monobutyl maleate, glycidyl methacrylate, butoxyethyl methacrylate and the like.
[0008]
  The particles of the (B) component methacrylate ester resin have a core-shell structure, but the monomer composition as a whole particle is a methyl methacrylate unit.70-75(Meth) acrylate unit in which the glass transition point of the homopolymer is -20 ° C or lower, preferably -30 ° C or lower.30-25In addition, it contains 0 to 10% by weight of comonomer units copolymerizable with these as required, and the total is 100% by weight.
  The content of methyl methacrylate units is70If it is less than% by weight, the expansion ratio of the foamed molded product will not increase.75When the amount is more than% by weight, the compatibility with the wood powder of the methacrylic ester resin is deteriorated, and the wood powder is aggregated or the size of the foamed cells is not uniform, resulting in a non-uniform composition.
  The particles of the (B) component methacrylate ester resin have a core-shell structure, and the core layer has a methyl methacrylate homopolymer or 70% by weight or more of methyl methacrylate units, and the glass transition point of the homopolymer is The (meth) acrylate unit is made of a copolymer containing 30% by weight or less of a (meth) acrylate unit that is −20 ° C. or less, and the shell layer has 20 units of (meth) acrylate having a homopolymer glass transition point of −20 ° C. or less. The content of the (meth) acrylate in the copolymer comprising the copolymer comprising ˜50% by weight, wherein the content ratio of the (meth) acrylate unit in the copolymer constituting the shell layer constitutes the core layer Since it is more than the ratio, the following effects are produced. That is, there is an advantage that the latex coagulation after the polymerization can be performed at a relatively low temperature of, for example, 55 to 80 ° C. in the production of the methacrylic ester resin particles of the component (B). It is easy to adapt and the uniformity of mixing and dispersion is improved, so that the foamed molded product can be made more uniform.
[0009]
  In the core-shell structure particles of the methacrylic ester resin as the component (B), the weight ratio of the core to the shell is preferably 1/1 to 15/1. The methacrylic acid ester resin used as the component (B) has a specific viscosity at 25 ° C. of 100 ml of a chloroform solution in which 0.2 gr is dissolved.1.8-3.3It is necessary to be in the range of 2.0 to 3.0. If the value of the specific viscosity is less than 1.5, the surface of the molded product will be rough, and if it exceeds 4.0, uniform melting will occur.LongIt takes time. For adjusting the specific viscosity, a general method such as selection of a polymerization reaction temperature, use of a chain transfer agent such as t-dodecyl mercaptan or carbon tetrachloride can be employed.
  The (B) component methacrylate ester resin 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 foamed cells and makes it difficult to break. Has an effect. The blending amount of the component (B) in the present invention is preferably 5 to 30 parts by weight, more preferably 10 to 20 parts by weight per 100 parts by weight of the vinyl chloride resin of the component (A). When the blending amount of the component (B) is less than 5 parts by weight, the retention strength of the film strength at the time of foaming is weakened and the foamed cells are easily destroyed. On the other hand, if the blending amount exceeds 30 parts by weight, the melt viscosity becomes high, the heat generation becomes large and the resin is liable to be thermally deteriorated, and the size of the foamed cells tends to be non-uniform.
[0010]
As the pyrolyzable foaming agent which is the component (C) of the composition of the present invention, a pyrolyzable organic foaming agent and / or a pyrolyzable inorganic foaming agent is used. Examples of the former include nitroso compounds such as N, N′-dinitrosopentamethylenetetramine and N, N′-dimethyl-N, N′-dinitrosotephthalamide; azos such as azodicarbonamide and azobisisoptyronitrile. Examples thereof include sulfonyl hydrazides such as compounds, benzenesulfonyl hydrazide, p, p'-oxybis (benzenesulfonyl hydrazide) and toluenesulfonyl hydrazide. Examples of the latter include sodium bicarbonate, ammonium bicarbonate, ammonium carbonate and the like. In this invention, 1 type (s) or 2 or more types selected from the group of said organic or / and inorganic pyrolytic foaming agent can be used.
In the present invention, it is inappropriate to heat and volatilize low boiling point organic compounds such as trifluoromethane and petroleum ether for use as a foaming agent. This is because the foamed cell becomes rough and the molded product becomes difficult to use with nails or screws, which may not be suitable for building materials.
The blending amount of the pyrolytic foaming agent of the component (C) in the present invention is preferably 0.1 to 3.0 parts by weight, more preferably 0.5 to 100 parts by weight per 100 parts by weight of the vinyl chloride resin of the component (A). 1.5 parts by weight. When the blending amount of the component (C) is less than 0.1 parts by weight, the inside of the molded product obtained with a low foaming ratio tends to lack the wood texture, and conversely if it exceeds 3.0 parts by weight, the molded product surface Tends to be rough and the surface hardness tends to decrease.
[0011]
In the present invention, as the component (D), wood powder having an average particle size of 50 to 500 μm is 5 to 150 parts by weight, preferably 22 to 120 parts by weight, more preferably 100 parts by weight of vinyl chloride resin (A). 25 to 100 parts by weight are used. When the blending amount of the wood powder is less than 5 parts by weight, it is difficult to express the wood texture in the molded product, and when it exceeds 150 parts by weight, the molded product becomes brittle. In the present invention, by blending the above component (B), even if blended in a high number of wood flour exceeding 20 parts by weight, it is familiar to the vinyl chloride resin and can be uniformly dispersed. It has uniform and fine foamed cells and a smooth skin, and can express wood texture strongly.
The tree species of the wood flour used in the present invention is not particularly limited, and wood such as softwood such as cedar, tsuga, lawan, and hardwood timber, sawdust, sawdust, and the like can be used. In order to obtain the component (D) of the present invention from these woods, for example, the wood is preferably made into a relatively rounded wood powder having an average particle size 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 larger than that of wood flour and whose average particle size is smaller than the average particle size of wood flour. Specifically, metals, metal oxides and metal salts, inorganic oxides, plastic particles, etc. Is mentioned. A preferred component (D) is wood powder having metallic or inorganic particles such as titanium oxide, nickel, calcium carbonate, silica, mica, etc. attached to the surface. The hard small particles adhere to the surface of the wood flour in such a manner that the hard small particles such as entrapment bonding including biting of the hard small particles into the wood flour, and sandwiching bonding of a plurality of hard small particles that are bitten and bonded to each other are included. Adhesion by pressing external force against the wood powder surface portion may be used, or hard small particles may be adhered to the wood powder with an adhesive. In this case, the above-mentioned wood powder is charged into a ball mill or the like together with 1-50% by weight of hard small particles, and is treated by performing dust explosion prevention treatment under a nitrogen atmosphere.
[0012]
The average particle diameter of (D) component used for this invention is 50-500 micrometers, Preferably it is 30-100 micrometers. Here, the average particle diameter refers to a reading of the value of the opening corresponding to 50% by weight by obtaining a cumulative weight% curve for the opening by sieving the powder. When the average particle size of the component (D) is less than 50 μm, the bulk specific gravity becomes small and the mixing operability for preparing the composition is deteriorated, and when it is more than 500 μm, the surface of the molded product is rough and the expansion ratio is lowered.
(D) It is preferable that the water | moisture content in a component is 10 weight% or less, More preferably, it is 5 weight% or less.
In addition to the above-mentioned components, the composition of the present invention includes, in addition to heat stabilizers and lubricants used in the processing of ordinary vinyl chloride resins, UV absorbers, impact resistance enhancers, pigments, plasticizers, antistatic agents. An agent or the like is appropriately added.
[0013]
  The present inventionofTo prepare the composition:(A) 100 parts by weight of vinyl chloride resin, (B) 5 to 30 parts by weight of methacrylic ester resin particles having the core-shell structure, and (D) 5 to 150 parts by weight of wood flour having an average particle size of 50 to 500 μm. All the parts are put into a mixer and heated up to 120 to 160 ° C. while stirring and mixing. Then, when the temperature is reached, (C) pyrolytic foaming agent 0.1 to 3 is added to the mixture. Add 0.0 part by weight and then lower the temperature. More specifically,Usually, the components (A), (B) and (D), etc., except the pyrolytic foaming agent (C), are first put into a mixer such as a Henschel mixer and mixed while stirring vigorously. The temperature is raised to 160 ° C. Moisture absorbed in the wood flour is volatilized during the mixing process. When the temperature is reached, the mixture is transferred to a cooling mixer, and the pyrolytic foaming agent (C) is added, and then the temperature is lowered to 50 to 60 ° C. The extracted powdery mixture can be used as a molding compound as it is, but it is usually pelletized. A preferable method for producing the pellet includes a method of producing a pellet using a twin-screw extruder at 150 to 170 ° C. and discharging residual moisture in the wood flour from the vent hole. In the above method for preparing the composition of the present invention, the bulk specific gravity is large and the additives such as pigments are uniformly dispersed by adding all the components except the foaming agent at the time of initial mixing in a Henschel mixer or the like. A mixture can be obtained.
  Although there is no restriction | limiting in particular as a shaping | molding method for obtaining the vinyl chloride-type resin molded product similar to natural wood using this invention composition, Usually, an extrusion molding method is taken.
[0014]
  In the following, the present inventionPreferred composition and method for producing the sameAn aspect is described.
(1) The average degree of polymerization of the vinyl chloride resin is 400-1500.
(2) Specific viscosity at 25 ° C. of 100 ml of chloroform solution in which 0.2 g of methacrylic acid ester resin is dissolved is 2.0 to 3.0.
(3) The weight ratio of the core to the shell is 1/1 to 15/1.
(4) The blending amount of wood powder having an average particle size of 50 to 500 μm is 22 to 120 parts by weight.
[0015]
【Example】
Next, although an Example and a comparative example are given and the resin composition of this invention is demonstrated concretely, this invention is not limited to these Examples. The number of parts and% are based on weight.
Methacrylic acid ester resins A to G were prepared as follows. The specific viscosity of each resin was measured at 25 ° C. by taking a sample from 100 ml of a chloroform solution in which 0.2 gr of resin was dissolved.
[0016]
  Methacrylate ester resin production example 1
  To a stainless steel reactor, 60 parts of methyl methacrylate, 15 parts of n-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 are added, and the polymerization temperature is stirred. Emulsion polymerization was performed at 55 ° C. After confirming the completion of the reaction based on the solid content concentration of the sampled reaction solution, the resulting latex (with polymer particles as seed) is used.Methyl15 parts of methacrylate and 10 parts of n-butyl acrylate were added, followed by polymerization at 55 ° C. to complete the reaction, and a latex having a solid content concentration of 40.2% was obtained. The obtained latex was salted out by adding aluminum sulfate under heating, dehydrated, washed, and dried to obtain Resin A. The composition and specific viscosity of Resin A are shown in Table 1.
[0017]
Methacrylate ester resin production example 2
30 parts of ethyl acrylate is used instead of 25 parts of n-butyl acrylate, 55 parts of methyl methacrylate and 20 parts of ethyl acrylate are used as monomers to be added during the first stage polymerization, and chain transfer agent t -Same as Methacrylate ester resin production example 1 except that 0.1 part of dodecyl mercaptan was added and 15 parts of methyl methacrylate and 10 parts of ethyl acrylate were used as monomers to be added at the second stage of polymerization. To obtain Resin B. The composition and specific viscosity of Resin B are shown in Table 1.
[0018]
Methacrylate ester resin production example 3
Instead of 25 parts of n-butyl acrylate, 20 parts of n-butyl methacrylate (glass transition point of homopolymer 20 ° C.) is used, and 65 parts of methyl methacrylate and n- 10 parts of butyl methacrylate and 0.03 part of t-dodecyl mercaptan were added, and 15 parts of methyl methacrylate and 10 parts of n-butyl methacrylate were used as monomers to be added during the second stage polymerization. Otherwise, the same procedure as in Production Example 1 of methacrylic ester resin was carried out to obtain Resin C. The composition and specific viscosity of Resin C are shown in Table 1.
[0019]
Methacrylate ester resin production example 4
Add 93 parts methyl methacrylate, 7 parts ethyl acrylate, 0.05 part t-dodecyl mercaptan, 1 part sodium alkyl sulfate with 12 to 18 carbon atoms, 0.1 part potassium persulfate and 150 parts water to a stainless steel reactor. Then, emulsion polymerization was carried out at 70 ° C. with stirring, and the completion of the reaction was confirmed by the solid content concentration of the sampled reaction liquid.
The obtained latex was salted out by adding aluminum sulfate under heating, dehydrated, washed and dried to obtain Resin D. The composition and specific viscosity of the resin D are shown in Table 1.
[0020]
Methacrylate ester resin production example 5
Similar to Methacrylate ester resin production example 4 except that 60 parts of methyl methacrylate and 40 parts of n-butyl acrylate were used as monomers for the polymerization reaction, and the amount of t-dodecyl mercaptan was 0.07 part. Resin E was obtained. The composition and specific viscosity of Resin E are shown in Table 1.
[0021]
Methacrylate ester resin production example 6
Similar to Methacrylate ester resin production example 4 except that 75 parts of methyl methacrylate and 25 parts of n-butyl acrylate were used as polymerization reaction monomers and the amount of t-dodecyl mercaptan was 0.20 part. And resin F was obtained. The composition and specific viscosity of the resin F are shown in Table 1.
[0022]
Methacrylate ester resin production example 7
t-dodecyl mercaptan was not added and instead of 0.1 part of potassium persulfate as a radical initiator, 0.20 part of cumene hydroperoxide, 0.1 part of sodium formaldehyde sulfoxylate, ethylenediaminetetraacetic acid Resin G was obtained in the same manner as in Methacrylate ester resin production example 6 except that 0.02 part of iron and 0.01 part of sodium ethylenediaminetetraacetate were used and the reaction temperature was 5 ° C. The composition and specific viscosity of the resin G are shown in Table 1.
[0023]
The properties of the foamed molded product were examined by the following method.
1) Foamed 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 diameter is a fine and uniform state of 100 μm or less.
B: Cells that are destroyed and roughened are scattered.
C: Many cells are destroyed and roughened.
D: Most of the cells that were destroyed and roughened.
2) Molded product surface properties
Visually and touch the surface of the molded product and evaluate it according to the following rank.
A: Smooth
B: Slightly dark skin
C: Skin
D: Many granular protrusions.
3) True specific gravity and molded product specific gravity
Measured by the underwater replacement method according to JIS K 7112.
4) Molded product foaming ratio
Using the specific gravity value from the above measurement, the following formula is used.
Foaming ratio = true specific gravity / molded product specific gravity
5) Tensile strength
It is measured at a tensile speed of 10 mm / min using a JIS K 7113 No. 1 test piece.
[0024]
Examples 1-3, Comparative Examples 1-8
Each type and amount of ingredients shown in Table 2 were blended in a Henschel mixer as follows. Water vapor was volatilized while charging and mixing a vinyl chloride resin, a methacrylic ester resin (except for Comparative Example 1), wood flour, heat stabilizer, lubricant, filler and pigment. When the temperature increased to 140 ° C., the mixture was transferred to a cooling mixer and the blowing agent was added while mixing, and the temperature was lowered to 60 ° C.
The obtained powdery mixture was pelletized under the following conditions using a single screw extruder with a cylinder diameter of 65 mm. In addition, the water | moisture content which remains in wood powder was volatilized from the vent hole.

The pellets thus obtained were subjected to extrusion foam molding under the following conditions using a single screw extruder having a cylinder diameter of 40 mm. Table 1 shows the characteristics of the molded product.

[0025]
[Table 1]

[0026]
note
MMA methyl methacrylate
nBA n-butyl acrylate
EA ethyl acrylate
nBMA n-butyl methacrylate
[0027]
[Table 2]

[0028]
note
* 1 ZEST700L, Shin-Daiichi PVC Co., Ltd., vinyl chloride resin, average polymerization degree 680
* 2 Selunt, manufactured by Shimada Shokai Co., Ltd., wood flour, average particle size 80μm, moisture 5% by weight
* 3 Titanium oxide grain-attached wood powder, manufactured by Misawa Techno Co., Ltd., E60-T5-3, titanium oxide content 5% by weight, average particle size 60 μm, moisture content 5%
* 4 Tribasic lead sulfate / lead stearate composite heat stabilizer
* 5 Polyethylene wax
* 6 Calcium carbonate CCR, manufactured by Shiraishi Calcium Co., Ltd., average particle size 0.08μm
* 7 Carbon Black (TPH0012, manufactured by Toyo Ink Manufacturing Co., Ltd.) / Condensed Azo Red (TXH4360, manufactured by the company) / Bisazo Yellow (TXH2110, manufactured by the company) composite pigment
[0029]
In Examples 1 to 3 molded using the composition having the requirements of the present invention, a molded article having a satisfactory foam cell state and surface properties, a sufficient foaming ratio, and satisfactory tensile strength is obtained. It was.
In Comparative Example 1 in which the methacrylic ester resin was not blended, the foamed cell state, the surface property, and the foaming ratio were all poor.
[0030]
As a methacrylic ester resin, a resin C containing a comonomer unit having a glass transition point higher than a specified range, or a resin D having a low content even if the glass transition point is a copolymer having a specified range. In Comparative Example 2 or 3 using the foamed cell, the foamed cell was rough, the foaming ratio was not increased, and the surface of the molded product was crusty. In addition, when a methacrylate ester resin E containing a comonomer having a glass transition point in a specified range is contained in a proportion higher than the specified ratio, the foaming cell is rough but the foam cell is rough, the surface properties are rough, and the tensile strength is inferior. A molded product was provided (Comparative Example 4). Even if it is a methacrylic ester resin containing a specified amount of a comonomer having a specified glass transition temperature, the foamed cell state and the surface of the molded product are rough, even if the specific viscosity is out of the specified range, whether it is small or large Molded articles were obtained (Comparative Examples 5 and 6).
When the blending amount of the methacrylic ester resin was too small or too large, a foamed cell or a molded article having a remarkably rough surface was obtained (Comparative Examples 7 and 8).
[0031]
【The invention's effect】
By using the composition of the present invention, it is possible to obtain a molded article suitable for building materials and furniture materials having a uniform fine cell structure and a smooth skin, and rich in wooden texture and having sufficient mechanical strength.

Claims (2)

(A) 100 parts by weight of vinyl chloride resin, (B) 70 to 75 % by weight of methyl methacrylate, 30 to 25 % by weight of (meth) acrylate having a glass transition point of −20 ° C. or less, and as required. A core-shell made of a methacrylic ester resin having a specific viscosity of 1.8 to 3.3, which is composed of a monomer unit of 0 to 10% by weight of a copolymerizable monomer and a total of 100% by weight. Particles having a structure, the core layer of which is a methyl methacrylate homopolymer or 70% by weight or more of a methyl methacrylate unit, and the glass transition point of the homopolymer is −20 ° C. or less and a (meth) acrylate unit of 30% by weight A copolymer containing 20 to 50% by weight of a (meth) acrylate unit whose homopolymer has a glass transition point of −20 ° C. or less. A methacrylic compound comprising a copolymer, wherein the content ratio of the (meth) acrylate unit in the copolymer constituting the shell layer is larger than the content ratio of the (meth) acrylate in the copolymer constituting the core layer. 5-30 parts by weight of acid ester resin particles, (C) 0.1-3.0 parts by weight of pyrolytic foaming agent, and (D) 5-150 parts by weight of wood flour having an average particle size of 50-500 μm A vinyl chloride resin composition. (A) 100 parts by weight of vinyl chloride resin, (B) 5 to 30 parts by weight of methacrylic ester resin particles having a core-shell structure according to claim 1 , and (D) an average particle diameter of 50 to 500 μm. 5 to 150 parts by weight of wood flour are charged all at once into a mixer and heated to 120 to 160 ° C. while stirring and mixing. When the temperature is reached, (C) Pyrolytic foaming is applied to the mixture. A method for producing a vinyl chloride resin composition, comprising adding 0.1 to 3.0 parts by weight of an agent and then lowering the temperature.