JPH09302186A - Vinyl chloride resin composition for injection molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain vinyl chloride resin composition for injection molding which can give molded products excellent in appearance without silver streaking and blister even in the injection molding by compounding a formulation comprising a vinyl chloride resin, a methyl methacrylate copolymer and a lubricant at a specific temperature. SOLUTION: A formulation of (A) 100 pts.wt. of a vinyl chloride resin, for example, having an average polymerization degree of 300-8,000, particularly of 700-3,000, (B) 0.1-5 pts.wt. of a methyl methacrylate copolymer, for example, a methyl methacrylate and an acrylic ester copolymer, (C) 0.1-2 pts.wt. of a lubricant, for example, an aliphatic hydrocarbon lubricant, a higher fatty alcohol lubricant and an aliphatic amide lubricant is compounded at a temperature of 100-120 deg.C.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a vinyl chloride resin composition suitable as an injection molded product.

[0002]

2. Description of the Related Art Conventionally, vinyl chloride resin compositions have been widely used because of their excellent physical properties and processability. Among them, a vinyl chloride resin composition for injection molding has been used for various applications such as a pipe joint because a molded product having a complicated shape can be obtained. However, since a vinyl chloride resin composition as a material may cause defective molding, a suitable material has been desired.

[0003]

As this molding defect,
If water or volatile matter remains in the material, there is a phenomenon called silver streak, in which a silver-white streak is generated in the resin flow direction. As a measure against this silver strip phenomenon, a method has been adopted in which the extruder is equipped with a vent to remove water and volatile components from the resin. Was not obtained. In addition, when the flow of the material is not stable, there is a phenomenon called blister in which a round convex portion is formed on the surface of the molded product due to air trapped near the surface of the molded product. Therefore, an object of the present invention is to provide a vinyl chloride resin composition for injection molding which does not cause molding defects such as silver strips and swelling in an injection molded product.

[0004]

In order to solve the above-mentioned problems, the inventors of the present invention have made earnest studies and found that when a methyl methacrylate copolymer and a lubricant were added to a vinyl chloride resin in a specific ratio, injection molding was performed. Stabilize the flow of the resin at the time so that the swelling phenomenon can be eliminated. Also, the vinyl chloride resin compound is
Usually, the liquid temperature is low, so the resin temperature
The inventors have found that silver strips can be eliminated by raising the resin temperature to 100 ° C. or higher at which the water evaporates at the stage of compounding before granulation, although the temperature is not raised to 100 ° C. or higher. That is, the vinyl chloride resin composition for injection molding of the present invention comprises 100 parts by weight of a vinyl chloride resin, 0.1 to 5 parts by weight of a methyl methacrylate copolymer and 0.1 to 2 parts of a lubricant.
It is a mixture of parts by weight at a resin temperature of 100 to 120 ° C.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The vinyl chloride resin composition for injection molding of the present invention will be described in detail below. The vinyl chloride-based resin used in the vinyl chloride-based resin composition includes a vinyl chloride homopolymer, a vinyl chloride monomer of 50% by weight or more, and a copolymerization weight of the vinyl-based monomer copolymerizable therewith. Examples thereof include a polymer or a graft copolymer obtained by graft-polymerizing a vinyl chloride monomer to a polymer other than these, and among these, a vinyl chloride homopolymer is preferable.
These vinyl chloride resins usually have an average degree of polymerization of 300 to 8,
Although those having an average polymerization degree of 000 are used, those having an average degree of polymerization of 700 to 3,000 are preferable in view of the balance between moldability and mechanical properties.

Examples of the vinyl monomer copolymerizable with the vinyl chloride monomer include α-olefins such as ethylene, propylene and butylene; vinyl acetate, vinyl cabronate, vinyl laurate and stearin. Vinyl esters such as acid vinyl; butyl vinyl ether, octyl vinyl ether, dodecyl vinyl ether, phenyl vinyl ether and other alkyl vinyl ethers;
Esters of acrylic acid or methacrylic acid such as ethyl acrylate, n-butyl acrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate; aromatic vinyls such as styrene and α-methylstyrene; vinylidene chloride, vinyl fluoride. , Halogenated olefins such as vinyl bromide and propylene chloride; N-substituted maleimides such as N-phenylmaleimide and N-cyclohexylmaleimide; acrylics such as acrylic acid, methacrylic acid, acrylonitrile, maleic anhydride and itaconic anhydride Examples thereof include derivatives, and these are used alone or in combination of two or more.

Examples of the polymer that can be graft-polymerized with a vinyl chloride monomer include ethylene / vinyl acetate copolymers, ethylene / vinyl acetate / carbon monoxide copolymers, ethylene / ethyl acrylate copolymers, ethylene. Ethyl acrylate / carbon monoxide copolymer, ethylene / methyl methacrylate copolymer, ethylene / propylene copolymer, acrylonitrile / butadiene copolymer, polyurethane, chlorinated polyethylene, chlorinated polypropylene, methyl methacrylate / butadiene / styrene copolymer Coalescing,
Examples thereof include acrylonitrile / butadiene / α-methylstyrene copolymer, polybutyl acrylate, butyl rubber, polystyrene, styrene / butadiene copolymer, and acrylic rubber, and these are used alone or in combination of two or more. Further, these may be used in combination with a monomer having at least one unsaturated group copolymerizable with the vinyl chloride monomer.

The methyl methacrylate-based copolymer used as the second component in the vinyl chloride resin composition is a copolymer of methyl methacrylate and an acrylate ester. Examples of the acrylate ester used here include: , Methyl acrylate, ethyl acrylate, -n-butyl acrylate, isobutyl acrylate, acrylic acid-
2-Ethylhexyl, ethyl methacrylate, -n-butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate and the like can be mentioned, and these are used alone or in combination of two or more. These methyl methacrylate-based copolymers are the above vinyl chloride-based resins 1
0.1-5 parts by weight, preferably 0.5-2, relative to 00 parts by weight
Used in parts by weight. If it is less than 0.1 parts by weight, the flow is not stable and swelling occurs, which is not preferable, and if it is 5 parts by weight or more, the melt viscosity is too high and the fluidity is impaired, which is not preferable as an injection molding material.

The lubricant used as the third component in the vinyl chloride resin composition is, for example, an aliphatic hydrocarbon lubricant such as low molecular weight wax, polyethylene wax, paraffin wax, liquid paraffin; higher aliphatic such as stearyl alcohol. Alcohol-based lubricants; Aliphatic amide-based lubricants such as stearic acid amide, palmitic acid amide, and methylenebisstearamide; fatty acid ester-based lubricants such as glyceryl monostearate, ethyl diaminostearate, and butyl stearate; or metallic soap and silicone. Examples thereof include oils, and these are used alone or in combination of two or more. These lubricants are used in an amount of 0.1 to 2 with respect to 100 parts by weight of the above vinyl chloride resin.
Used in parts by weight. If it is less than 0.1 parts by weight, swelling may occur, and the mold releasability from the mold is deteriorated to cause poor appearance, and if it exceeds 2 parts by weight, the supply to the injection molding machine may not only be reduced. In addition, bleed-out occurs on the surface of the molded product, which is not preferable.

The vinyl chloride resin composition contains, in addition to the above three components, a stabilizer, a plasticizer, a modifier, a filler, and a colorant, which are generally used in the vinyl chloride resin, if necessary. And the like can be added and blended within a range that does not impair the object of the present invention. Examples of the stabilizer include lead-based stabilizers such as tribasic lead sulfate, dibasic lead phosphite, basic lead sulfite, dibasic lead phthalate, lead white, and lead laurate or stearate; butyl. Tin malate, octyl tin malate, di-n-alkyl tin mercaptide, di-n-
Alkyl tin dilaurate, dibutyl tin dimaleate, dibutyl tin lauryl mercaptide, dioctyl tin-S, S '
-Tin stabilizers such as bis (isooctylmercaptoacetate), dibutyltin bisisooctylthioglycolate, di-n-octyltin malate polymer, dibutyltin mercaptopropionate; calcium, cadmium,
Organic metal salt stabilizers such as barium or zinc laurate or stearate and metal soap stabilizers; antimony stabilizers such as antimony mercaptocarboxylic acid salts or ester salts; phosphate stabilizers; epoxidized soybean oil, Examples include epoxidized oil stabilizers such as epoxidized linseed oil, hindered phenols such as bisphenol dimerized with BHT, sulfur, and methylene groups, and ultraviolet absorbers such as salicylates, benzophenone, and benzotriazole. Used alone or in combination of two or more.

Examples of the plasticizer include phthalic acid esters such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, di-n-octyl phthalate (hereinafter referred to as DOP), diisodecyl phthalate and butylbenzyl phthalate. Aliphatic dibasic acid esters such as dibutyl adipate, di-n-hexyl adipate, dibutyl sebacate; tributyl phosphate, tri-2-n-ethylhexyl phosphate, tricresyl phosphate, triphenyl phosphate, etc. Phosphoric acid esters; trimellitic acid-tri-2-ethylhexyl, trimellitic acid tributyl and other trimellitic acid esters; pentaerythritol ester,
Glycol esters such as diethylene glycol benzoate; epoxidized vegetable oils such as epoxidized soybean oil and epoxidized linseed oil; citrate esters such as acetyltributyl citrate, acetyltrioctyl citrate, and tri-n-butyl citrate; tetra -N-
Octyl pyromellitate, polypropylene adipate,
Other examples include polyester plasticizers, which are used alone or in combination of two or more. Since the present invention relates to a hard vinyl chloride resin composition in the present invention, it is preferable to use 10 parts by weight or less for the purpose of enhancing processability and fluidity, not for the purpose of plasticizing.

Examples of the modifier include ethylene / vinyl acetate copolymer, ethylene / ethyl acrylate copolymer, chlorinated polyethylene, methyl methacrylate / butadiene / styrene copolymer, acrylonitrile / butadiene / styrene copolymer. Impact modifiers such as acrylic rubber; heat-resistant modifiers such as acrylonitrile / butadiene / α-methylstyrene copolymers, methyl methacrylate / acrylic acid ester copolymers, and other copolymers using maleimide; antimony trioxide Flame retardants such as aluminum hydroxide, sodium antimonate, phosphate esters and phosphate compounds, chlorinated paraffins, chlorinated olefins, and hexabromobenzene; partially crosslinked NBR, acrylic rubber, elasticity imparting agents such as polyurethane; Is a foaming agent, antistatic agent, Surface active agents, optionally selected from among such conductive agent is used in one or a combination of two or more.

Examples of the fillers include carbonates such as heavy calcium carbonate, light calcium carbonate, precipitated calcium carbonate, magnesium carbonate and dawsonite; oxides such as silica, diatomaceous earth and titanium oxide; hydroxylation. Hydroxides such as aluminum and magnesium hydroxide; (sulfite) s such as calcium sulfate and barium sulfate; silicates such as talc, clay, mica, calcium silicate; carbons such as carbon black and graphite Hollow or solid glass beads, short glass fibers, metal fibers,
Inorganic fiber type such as short carbon fiber and carbon fiber; metal powder type such as iron powder and copper powder; heat resistant resin such as polyimide and silicone. These are used in one kind or in combination of two or more kinds. .

As the colorant, any one can be selected from those conventionally used for coloring plastics. Examples of such a colorant include aluminum powder, metal powders such as bronze powder, carbon salts such as carbon black, titanium oxide, zinc white, oxides such as red iron oxide, and sulfates such as precipitated barium sulfate. Calcium carbonate, carbonate such as basic magnesium carbonate, clay, silicate such as ultramarine, chromate such as yellow lead,
Aluminates such as cobalt blue, inorganic pigments such as ferrocyan compounds such as navy blue; toluidine red,
Permanent Carmine FB, Disazo Yellow AAA,
Azo pigments such as lake red C, polycyclic pigments such as phthalocyanine blue, indanthrone blue, quinacridone red, Victoria pure blue BO lake, dyed lakes such as alkali blue toner, azine pigments, fluorescent pigments, etc. And organic dyes, basic dyes, acid dyes, oil-soluble dyes, disperse dyes, and the like, which are used alone or in combination of two or more.

The vinyl chloride resin composition of the present invention can be mixed in the same steps as the conventional vinyl chloride resin composition. In other words, use a mixer such as a Henschel mixer or ribbon blender to adjust the resin temperature at that time to 100
Dry blending in the range of up to 120 ° C is preferred. In particular, when a mixture of a vinyl chloride resin, a methyl methacrylate copolymer and a lubricant is charged into the above mixer at room temperature and mixed, and the resin temperature rises to a range of 100 to 120 ° C. It is better to take it out. At that time, the temperature of the mixer may be adjusted. If the resin temperature is less than 100 ° C, the water and volatile components in the composition cannot be sufficiently removed, so that the generation of silver strips cannot be prevented, and if it exceeds 120 ° C, the shear of the Henschel mixer and ribbon blender cannot be prevented. This may cause the compound to burn and discolor, which is not preferable. Like the conventional vinyl chloride resin composition, the above-mentioned compound can be kneaded and granulated with a Banbury mixer, a mixing roll, a single-screw or twin-screw extruder and the like. Further, a molded product can be obtained by molding the compound with an injection molding machine without granulating.

[0016]

EXAMPLES Hereinafter, specific embodiments of the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited to these descriptions. The ingredients (parts by weight) of the formulations shown in Table 1 and Table 2 were put into a Henschel mixer having a capacity of 20 liters and mixed, and the resin temperature of the mixture was changed from room temperature to the temperature shown in Table 1 or Table 2. The temperature was raised with steam until it rose. The mixture was granulated with a 50 mm single-screw extruder (with vent) using a full flight screw with L / D = 22 and a compression ratio of 2.0 to obtain a sample (pellet). This was tested by the following method, and the results are shown in Table 1 and Table 2.
It was also described in. The details of each component used are shown below.

Test method Molding test: A sample (pellet) is molded by an 85t injection molding machine. The appearance of the molded product was observed and evaluated according to the following criteria. The samples that could not be molded were described as "molding difficult" in the table. (Silver strip) O: No occurrence, X: Occurrence. (Blistering) ◯: No occurrence, X: Occurrence. (Discoloration) ◯: No discoloration, ×: Discoloration.

(Details of components) Vinyl chloride resin (PVC in the table): TK-700
(Shin-Etsu Chemical Co., Ltd., trade name, vinyl chloride homopolymer with an average degree of polymerization of 700) Vinyl chloride resin (same as above): TK-1000 (Shin-Etsu Chemical Co., Ltd., trade name, chloride with an average degree of polymerization of 1,000) Vinyl homopolymer) -Methyl methacrylate copolymer: Metabrene P-551A (trade name, manufactured by Mitsubishi Rayon Co., Ltd.)-Lubricant: AC-6A (trade name, polyethylene wax manufactured by Allied Chemical Co., Ltd.)-Lubricant: VPM882 (Henkel) Hakusui Co., Ltd., trade name, ester wax) ・ Organotin stabilizer: TM-188J (Katsuda Kako Co., Ltd. trade name,
Dioctyl tin mercaptide) ・ Ca-Zn stabilizer: SHZ-76 (Shinagawa Kako Co., Ltd., trade name)

[0019]

[Table 1]

[0020]

[Table 2]

[0021]

EFFECTS OF THE INVENTION The vinyl chloride resin composition of the present invention can produce a molded product having excellent appearance without the occurrence of silver strips or swelling even in injection molding.

Claims (1)

[Claims] 1. A vinyl chloride resin 100 parts by weight, a methyl methacrylate copolymer 0.1 to 5 parts by weight, and a lubricant 0.1 to 2
A vinyl chloride resin composition for injection molding, which comprises mixing parts by weight of a mixture at a resin temperature of 100 to 120 ° C.