JPH08259722A - Production of vinyl chloride resin composition for foam molding - Google Patents

Abstract

PURPOSE: To obtain a vinyl chloride resin composition which is satisfactory in moldability and foamability even when containing a relatively large amount of wood meal and is especially suitable for producing a molded foam as a substitute for natural wood. CONSTITUTION: A vinyl chloride resin is compounded with a mixture of wood meal previously prepared and a thermally decomposable foaming agent to obtain the objective composition. The foaming agent is preferably sodium bicarbonate or a mixture thereof with a thermally decomposable organic foaming agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a vinyl chloride resin composition for foam molding, and more particularly to a vinyl chloride resin for foam molding suitable for producing a foam molded article which is a substitute material for natural wood. It relates to a method for producing a composition.

[0002]

BACKGROUND OF THE INVENTION Vinyl chloride resins are flame-retardant, have good mechanical strength, and have good weather resistance and chemical resistance, so they are not only non-foam molded products but also structural materials and building materials as foam molded products. Widely used in furniture and furniture.

Conventionally, as a method for producing this type of foamed molded article,
A molding machine such as an extrusion molding machine or an injection molding machine is used to form a vinyl chloride resin composition for foam molding obtained by mixing a vinyl chloride resin, wood powder, a pyrolytic foaming agent, and other necessary additives together. There is known a method of foam-molding using (for example, JP-B-63-9540 and JP-A-55).
-116752).

The foamed molded article obtained by such a method is
In particular, in order to give a feel and lightness close to that of natural wood and obtain a substitute material for natural wood, it is effective to mix a relatively large amount of wood powder with a vinyl chloride resin and foam it. Further, as wood powder, wood scraps and wood chips can be crushed and used, which has an advantage that resources can be recycled.

[0005]

However, when a relatively large amount of wood powder is mixed with a vinyl chloride resin, the wood powder is not well compatible with the vinyl chloride resin and easily aggregates. Therefore, the wood powder and the like are extruded. Formability deteriorates due to cumulative adhesion and clogging in molding machines such as molding machines and injection molding machines. Further, the efficiency of the specific gravity reduction of the obtained foam-molded article is deteriorated and the foamability is reduced, which makes it difficult to impart the lightness close to that of natural wood.

The present invention is intended to solve the above-mentioned problems, and it is an object of the present invention to obtain good moldability and foamability even when a relatively large amount of wood powder is blended, and especially to replace natural wood. An object of the present invention is to provide a method for producing a vinyl chloride resin composition for foam molding, which is suitable for producing a foam molded article as a material.

[0007]

The method for producing a vinyl chloride resin composition for foam molding according to the present invention comprises blending a vinyl chloride resin with a mixture of a wood powder and a pyrolyzable foaming agent prepared in advance. The above object can be achieved thereby.

In the present invention, as the vinyl chloride resin, a vinyl chloride homopolymer, a copolymer of vinyl chloride and another monomer, a graft of vinyl chloride graft-polymerized with an ethylene-vinyl acetate copolymer, etc. Polymers and resins obtained by chlorinating homopolymers, copolymers or graft polymers thereof are used.

Other monomers copolymerizable with vinyl chloride include α-olefins such as ethylene and propylene, vinyl esters such as vinyl acetate and vinyl propionate,
Vinyl ethers such as butyl vinyl ether and cetyl vinyl ether, (meth) acrylic acid esters such as methyl (meth) acrylate, butyl (meth) acrylate and hydroxyethyl (meth) acrylate, aromatic vinyls such as styrene and α-methylstyrene. And vinyl halides such as vinyl fluoride, vinylidene fluoride, and vinylidene chloride, and N-substituted phenylmaleimides such as N-phenylmaleimide and N-cyclohexylmaleimide.

The degree of polymerization of these vinyl chloride resins is J
400 to 20 with an average degree of polymerization specified in IS K6721
00 is preferable. If the average degree of polymerization is less than 400, the strength of the foam-molded product obtained will decrease, and conversely, the average degree of polymerization will be 20.
If it exceeds 00, the viscosity at the time of melting becomes high and the moldability deteriorates. In particular, the average degree of polymerization is more preferably 400 to 1000 from the viewpoint of stabilizing the bubbles during foaming.

Examples of the woody powder include wood such as cypress, pine, toga, and lauan, hardboard, scraps of wood, wood chips, pulp, and the like.
A wood material derived from cellulosic fibers such as rice husks and bagasse is crushed, and the maximum particle size is preferably 600 μm or less and the average particle size is 200 μm or less, more preferably 150 μm or less. Maximum particle size is 600μ
If it exceeds m 2 and the average particle size exceeds 200 μm, there is a possibility that it will remain in the molding machine during foam molding, causing clogging and burning.

The water content of the wood powder is 10% by weight or less, and it is preferable that the water content is as low as possible. If the water content exceeds 10% by weight, water may foam during foam molding, resulting in a rough surface of the resulting foam molded article, and deterioration of the resin may be promoted during molding.

Examples of the heat-decomposable foaming agent include azodicarbonamide, N, N'-dinitrosopentamethylenetetramine, p, p'-oxybis (benzenesulfonylhydrazide) and other heat-decomposable organic foaming agents, and baking soda-based foaming agents. Pyrolysis-type inorganic foaming agents such as The baking soda-based foaming agent is a foaming agent containing sodium bicarbonate as a main component, and examples thereof include trade names SC-D, SC-K and SC855 manufactured by Eiwa Chemical Co., Ltd.

In particular, the baking soda-based foaming agent is highly safe in handling and has a function of neutralizing an acidic gas called wood acid or wood vinegar generated during molding to prevent coloring of the foamed molded product. Of the above pyrolytic foaming agents, it is preferable to use a baking soda foaming agent or a mixed foaming agent of a baking soda foaming agent and a pyrolytic organic foaming agent.

In the present invention, the vinyl chloride resin is blended with a mixture of wood powder prepared in advance and a thermal decomposition type foaming agent. The mixture of the wood powder and the pyrolytic foaming agent is prepared by mixing a predetermined amount of the wood powder and the pyrolytic foaming agent powder with a mixing device such as a mixer (Henschel mixer, super mixer, etc.), raft machine, ball mill, etc. It is prepared by mixing in powder form.

The mixture of wood powder and pyrolyzable foaming agent is
When only the pyrolytic organic foaming agent is used as the pyrolytic foaming agent, generally, the wood powder is 5 to 150 parts by weight, the pyrolytic organic foaming agent is 0.0 to 100 parts by weight of the vinyl chloride resin.
It is preferable to prepare by uniformly mixing so that 5 to 5.0 parts by weight is contained. In particular, the thermal decomposition type organic foaming agent is 0.
More preferably, it is prepared so as to contain 1 to 2.0 parts by weight.

When the amount of wood powder is less than 5 parts by weight, properties close to those of natural wood may not be obtained, and when it exceeds 150 parts by weight, melt molding may be difficult. Also,
If the heat-decomposable organic foaming agent is less than 0.05 part by weight, a sufficiently light foamed molded product may not be obtained, and conversely, if it exceeds 5.0 parts by weight, the bubbles may be broken during foaming to be connected. It may become non-uniform and the surface condition and strength of the foamed molded product may deteriorate.

When a baking soda-based foaming agent or a mixed foaming agent of a baking soda-based foaming agent and a pyrolyzable organic foaming agent is used as the heat-decomposable foaming agent, generally 5 to 100 parts by weight of vinyl chloride resin is used to obtain a wood powder of 5 to 5. 150 parts by weight, baking soda foaming agent 0.1
5.0 parts by weight or 0.1 parts by weight or more of a baking soda-based blowing agent and 0.1% to 5.0 parts by weight of a blowing agent mixed with a pyrolyzable organic blowing agent are uniformly mixed. It is preferably prepared. In particular, it is more preferable to use the above mixed foaming agent and prepare such that 0.5 to 2.5 parts by weight of this mixed foaming agent is contained.

Also in this case, if the amount of wood powder is less than 5 parts by weight, properties close to those of natural wood may not be obtained, and if it exceeds 150 parts by weight, melt molding may be difficult. If the amount of the baking soda-based foaming agent or the mixed foaming agent of the baking soda-based foaming agent and the heat-decomposable organic foaming agent is less than 0.1 parts by weight, a sufficiently light foamed molded product may not be obtained. ．
If the amount exceeds 0 parts by weight, bubbles may be broken and connected during foaming, resulting in non-uniformity, which may deteriorate the surface condition and strength of the foamed molded product.

In the present invention, when a mixture of wood powder and a thermal decomposition type foaming agent is prepared, or when the above mixture prepared in advance is blended with a vinyl chloride resin, a foaming aid is added as necessary. Agents, heat stabilizers, heat stabilizing aids, lubricants,
Known additives such as processing aids, plasticizers, impact modifiers, fillers, cell nucleating agents, pigments, light stabilizers, UV absorbers, antistatic agents, flame retardants, and wood acid neutralizers. May be mixed.

Of these various additives, the heat stabilizer is usually mixed. In addition, a foaming aid and a processing aid are often mixed. In this case, the foaming aid is generally mixed together in preparing the mixture of wood powder and pyrolytic foaming agent. Further, the heat stabilizer, the processing aid, etc. are generally mixed together when the mixture of the wood powder and the thermal decomposition type foaming agent is mixed with the vinyl chloride resin.

As the foaming aid, zinc oxide (zinc white),
Lead oxide, cadmium oxide, magnesium oxide, cadmium stearate, barium stearate, zinc acetate, salicylic acid, benzoic acid, glycerin, diethylene glycol and the like are used.

As the heat stabilizer, lead white, basic lead sulfite, dibasic lead sulfite, tribasic lead sulfate, dibasic lead phosphite, silica gel coprecipitated lead silicate, lead stearate, lead benzoate, Lead stabilizers such as dibasic lead stearate and lead naphthenate, metal soap stabilizers such as calcium stearate, barium stearate and zinc stearate, organotins such as dibutyltin malate, dioctyltin laurate and dibutyltin mercaptide. A system stabilizer is used. Note that the combined use of a stabilizer having a mercapto group and a lead-based stabilizer is not preferable because it reacts with each other to form a sulfide and contaminates a molded article.

Epoxy compounds, phosphites and the like are used as the heat stabilizing aid. As the lubricant, fatty acids such as stearic acid, fatty acid esters, olefin wax and the like are used. An acrylic resin or the like is used as a processing aid. Dioctyl phthalate or the like is used as the plasticizer. ABS, MBS, chlorinated polyethylene and the like are used as the impact resistance improver. As the filler, calcium carbonate, talc, etc. are used.

Although a urea-based resin such as urea-formaldehyde resin can be used as the wood acid neutralizer,
These urea resins may leave an odor in the foamed molded product, and are not preferable for the production of interior materials for homes and furniture.
In this case, it is preferable to use a baking soda-based foaming agent having a function of neutralizing wood acid or a mixed foaming agent of a baking soda-based foaming agent and a thermally decomposable organic foaming agent as the thermal decomposition-type foaming agent.

In the present invention, the above vinyl chloride resin is blended with a mixture of a wood powder prepared in advance and a thermal decomposition type foaming agent in order to mix the vinyl chloride resin with the wood powder prepared in advance and a thermal decomposition type foaming agent. Using a mixing device such as a mixer (Henschel mixer, super mixer, etc.), a rafting machine, a ball mill, etc., the mixture of and is mixed uniformly at an appropriate temperature to obtain a powdery or granular mixture. further,
If necessary, the powdery or granular compound is melt-kneaded at a temperature lower than the decomposition temperature of the pyrolytic foaming agent and then pelletized by a pelletizer.

When blending a vinyl chloride resin with a mixture of a wood powder prepared in advance and a thermal decomposition type foaming agent,
Further, for the purpose of increasing the expansion ratio, there is no problem even if the same pyrolytic organic foaming agent or pyrolytic inorganic foaming agent such as baking soda-based foaming agent is additionally mixed together.

Thus, a vinyl chloride resin composition for foam molding is obtained. To produce a foam-molded article using this foam-molding vinyl chloride-based resin composition, this foam-molding vinyl chloride-based resin composition is fed to a molding machine such as an extrusion molding machine or an injection molding machine to obtain a known product. It is foam-molded by the method. For example, when a foamed molded product is produced by an extruder, the cylinder temperature of the extruder is generally set to 110 to 190 ° C and the mold temperature is set to 130 to 190 ° C.

[0029]

[Function] When a vinyl chloride resin is mixed with a wood powder and a thermal decomposition type foaming agent to produce a vinyl chloride resin composition for foam molding, the vinyl chloride resin is preliminarily prepared with a pyrolyzed wood powder. When mixed with a foaming agent, the wood powder is blended with the vinyl chloride resin as if it were covered with a pyrolytic foaming agent, and the surface friction resistance of the wood powder is reduced, resulting in agglomeration of the wood powder. It is speculated that this will be suppressed.

When the vinyl chloride resin composition for foam molding thus obtained is subjected to foam molding by a molding machine such as an extrusion molding machine or an injection molding machine, wood powder and the like are accumulated on the molding machine. It prevents foaming and clogging and improves moldability. Moreover, even though it contains a relatively large amount of wood powder, the gas generated from the thermal decomposition type foaming agent is efficiently foam-molded. The foamability is improved by contributing to the formation of bubbles in the product.

[0031]

The effects of the present invention will be described below with reference to experimental examples. Experimental Examples 1-27 Preparation of Mixture of Wood Powder and Pyrolysis-type Foaming Agent Wood powder: Wood for building materials is dried and crushed to have a water content of 5.
0% by weight, average particle size 60 μm, maximum particle size 60 μm. Thermal decomposition type: azodicarbonamide (ADCA) (AC # 1 manufactured by Eiwa Chemical Co., Ltd.) Foaming agent N, N'-dinitrosopentamethylenetetramine (DPT) (Cellular D manufactured by Eiwa Chemical Co., Ltd.) p, p'-oxybis (Benzenesulfonyl hydrazide) (OBSH) (Neocerbon N # 5 manufactured by Eiwa Chemical Co., Ltd.
000) Baking soda foaming agent (SC-D manufactured by Eiwa Chemical Co., Ltd.) Foaming aid: Zinc flower (ZA-100 manufactured by Sakai Chemical Co., Ltd.)

The above wood powder, pyrolyzable foaming agent and foaming auxiliary agent were mixed at a ratio shown in Table 1 for 30 minutes at a temperature of 40 to 80 ° C. by a 100 liter super mixer (Kawata Kogyo Co., Ltd.). And a total of 15 types A to O shown in Table 1
A mixture of different wood powders and a pyrolytic foaming agent was prepared. However, the type O in Table 1 consists of wood powder only.

Production of vinyl chloride resin composition for foam molding Polyvinyl chloride (average degree of polymerization: 800), shown in Table 1 15
Mixture of wood powder and pyrolytic foaming agent, heat stabilizer, processing aid, and additional pyrolytic foaming agent at a ratio of 100 liter super mixer (manufactured by Kawada Industry Co., Ltd.) The mixture was mixed for 15 minutes at a temperature of 70 to 120 ° C., and the obtained powdered mixture was further melt-kneaded by a 50 mmΦ twin-axis different-direction oblique-axis extruder (SLM50 manufactured by Nagata Seisakusho), and produced by a pelletizer. The mixture was granulated to obtain 27 kinds of pellet-like compounds.

The cylinder temperature of the extruder is set with a temperature gradient of 100 ° C. at the base to 130 ° C. at the tip,
The mold temperature was set to 140 and the screw rotation speed was set to 20 rpm.

Performance of vinyl chloride resin composition for foam molding
Evaluation Using the above 27 kinds of pellet-like compounds, a 30 mmΦ single screw extruder (GT-32 manufactured by Plastic Engineering Laboratory Co., Ltd.
A), T-die (lip width 33 mm, lip thickness 5 mm), sizing die (lip width 40 mm, lip thickness 8 mm) equipped with a cooling water tank (length 1 m, water volume 30 liters, water temperature 1
(9 to 21 ° C.), extrusion foaming was carried out by a foam molding machine comprising a take-up machine (take-off speed 60 cm / min), and the moldability and foamability during foam molding were evaluated.

The cylinder temperature of the extruder is set with a temperature gradient from 100 ° C. at the root to 180 ° C. at the tip,
The mold temperature was set to 170 ° C. and the screw rotation speed was set to 20 rpm.

The moldability during foam molding was evaluated by whether or not the resin composition was clogged during foam molding continuously for 4 hours and the surface condition of the obtained sheet-shaped foam molded article. Here, those having a smooth and glossy surface are marked with ◯, those with a rough texture are marked with Δ, and those with surface irregularities are marked with x. Further, the moldability during foam molding was evaluated by the specific gravity of the obtained sheet-shaped foam molded article. Table 3 shows the results.

As is clear from Experimental Examples 1 to 27,
A vinyl chloride resin composition for foam molding (Experimental Examples 1 to 19) obtained by mixing a vinyl chloride resin with an appropriate amount of a mixture of a wood powder and a thermal decomposition type foaming agent prepared in advance has good moldability and Shows foamability.

[0039]

[Table 1]

[0040]

[Table 2]

[0041]

[Table 3]

[0042]

As described above, the method for producing a vinyl chloride resin composition for foam molding according to the present invention comprises blending a vinyl chloride resin with a mixture of a wood powder and a pyrolyzable foaming agent prepared in advance. When performing foam molding using the vinyl chloride resin composition for foam molding thus obtained, good moldability and foamability can be obtained even when a relatively large amount of wood powder is blended. In particular, a vinyl chloride resin composition for foam molding suitable for producing a foam molded article which is a substitute material for natural wood can be obtained.

Particularly, in the present invention, when a baking soda-based foaming agent or a mixed foaming agent of a baking soda-based foaming agent and a pyrolysis-type organic foaming agent is used as the thermal decomposition-type foaming agent, wood acid generated during molding or An acid gas called wood vinegar can be neutralized to obtain a foam-molded product having no coloration or odor.

Claims (1)

[Claims] 1. A method for producing a vinyl chloride resin composition for foam molding, which comprises blending a vinyl chloride resin with a mixture of a wood powder prepared in advance and a thermal decomposition type foaming agent.