JPH10101832A - Vinyl chloride-based resin composition for expansion molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition for producing an expanded foam while preventing an occurrence of a plate-out in its extrusion molding in good molding processability by formulating a vinyl chloride-based resin, a polymethyl methacrylic processing auxiliary, a hydrotalcite compound and organic and inorganic foaming agents. SOLUTION: This composition for providing an expanded foam having uniformly dispersed fine cells therein, a smooth surface thereon and an excellent weathering and discoloring resistance, comprises (A) 100 pts.wt. vinyl chloride- based resin having a mean degree of polymerization of 400 to 1,200, (B) 0.5 to 30 pts.wt., preferably, 1 to 20 pts.wt. polymethyl methacrylic processing auxiliary with a specific viscosity of 0.10 to 1.00, preferably, 0.20 to 0.80, (C) 0.3 to 10 pts.wt., preferably, 0.5 to 5 pts.wt. hydrotalcite compound, and (D) preferably 0.1 to 0.5 pt.wt. organic foaming agent such as N,N-dinitroso pentamethylenetetramine and preferably 0.5 to 3.0 pts.wt. inorganic foaming agent such as sodium bicarbonate.

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 and, more particularly, to a weather resistant resin which suppresses the occurrence of plate-out during extrusion molding, has good moldability, has uniform and fine foam cells and a smooth surface. The present invention relates to a vinyl chloride resin composition for foam molding capable of giving a foam molded article having good discoloration.

[0002]

2. Description of the Related Art Vinyl chloride resins have been used for various purposes because of their good physical and chemical properties. Extruded foam molded products for use in place of wood, such as building materials, fittings, furniture, etc. are made of uniform fine cells and smooth molding by using an organic foaming agent and an inorganic foaming agent together in the presence of a polymethyl methacrylate-based processing aid. This has been made possible by realizing the product surface (Japanese Patent Publication No. 63-9540). However, in extrusion foaming of a vinyl chloride resin composition, there is a problem that plate-out often occurs. What is plate-out?
Some of the additives contained in the vinyl chloride resin composition precipitate little by little during molding, and mainly adhere to the screw tip and the die inner surface inside the molding machine, and gradually deposit to form a white solid. Say the phenomenon. Plate-out causes unexpected lines and scratches on the extruded product. Therefore, at the time of occurrence of plate-out (a few hours to several days after the start of molding), it is necessary to stop the production of the molded product and dismantle and clean the extruder.

[0003]

DISCLOSURE OF THE INVENTION The present invention has improved plate-out resistance, has a uniform fine cell and a beautiful surface without requiring dismantling and cleaning of an extruder for a long period of time. The object of the present invention is to provide a vinyl chloride resin composition having good processability, which gives a foam molded product having good workability.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, a polyvinyl chloride resin has a polymethyl methacrylate processing aid, a hydrotalcite compound and an organic foaming agent. The present inventors have found that the above-mentioned object can be achieved by blending an inorganic foaming agent and performing foam molding, and have completed the invention based on this finding. That is, the present invention relates to (A) vinyl chloride resin 10
0 parts by weight, (B) 0.5 to 30 parts by weight of a polymethyl methacrylate-based processing aid, (C) 0.3 to 10 parts by weight of a hydrotalcite compound, and (D) an organic foaming agent and an inorganic foaming agent. The average degree of polymerization of the vinyl chloride resin composition for foam molding and the vinyl chloride resin (A) is 40
The above-mentioned vinyl chloride-based resin composition for foam molding, which is 0 to 1200, is provided.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The vinyl chloride resin as the component (A) in the present invention includes, in addition to a vinyl chloride homopolymer, a copolymer of a vinyl chloride-based monomer and a copolymerizable monomer. Coalescing is used. Examples of such copolymerizable monomers include vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as ethyl vinyl ether and cetyl vinyl ether; acrylics, methacrylic acid, ethyl acrylate, methyl methacrylate, and methacrylic acid 2; −
(Meth) acrylic acid and its derivatives such as hydroxypropyl and glycidyl methacrylate; unsaturated dibasic acids and its derivatives such as maleic acid, fumaric acid and monomethyl maleate; aromatic vinyl compounds such as styrene and α-methylstyrene; Vinyl cyanide compounds such as acrylonitrile and methacrylonitrile; vinylidene compounds such as vinylidene chloride and vinylidene bromide;
Olefins and the like. The above comonomers may be used alone or in combination of two or more. The average degree of polymerization (according to JIS K 6721) of the vinyl chloride resin as the component (A) is preferably from 400 to 1200, more preferably from 500 to 800. If the average degree of polymerization is smaller than 400, the expansion ratio tends to be difficult to increase. Those having an average particle size of 80 to 200 μm are preferably used.

The polymethyl methacrylate-based processing aid of the component (B) of the composition of the present invention includes, in addition to methyl methacrylate homopolymer, a monomer copolymerizable therewith, that is,
Ethyl acrylate, butyl acrylate, ethoxyethyl acrylate, 2-ethylhexyl methacrylate, 2-hydroxypropyl methacrylate, acrylonitrile, a copolymer with two or more kinds of vinyl acetate and the like, wherein methyl methacrylate is used. Those having 50% by weight or more, preferably 80% by weight or more are used. As a polymethyl methacrylate-based processing aid of component (C), Japanese Patent Publication No. 5-38
No. 014 methacrylate ester polymer, that is, the inside of the particle is a copolymer of methyl methacrylate and acrylate, the outside of the polymer of methyl methacrylate alone or methyl methacrylate mainly It may be a two-stage resin particle such as a resin coated with a copolymer. The polymethyl methacrylate-based processing aid used as the component (B) preferably has a specific viscosity at 25 ° C of 100 ml of a chloroform solution in which 0.1 gr is dissolved, of 0.10 to 1.00, and 0.20 to 1.00.
More preferably, it is in the range of 0.80. If the value of the specific viscosity is less than 0.10, the surface of the foamed molded article tends to be rough, and if it exceeds 1.00, time may be required for uniform melting.

The component (B), a polymethyl methacrylate-based processing aid, has the effect of improving the melt viscosity characteristics of the vinyl chloride-based resin, maintaining the film strength of the foamed cell, and making it difficult to break. The amount of the component (B) used is the same as that of the component (A) 10
0.5 to 30 parts by weight, preferably 1 to 20 parts by weight per 0 parts by weight
Parts by weight. If the amount is less than 0.5 parts by weight, the holding strength of the film strength during foaming is 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.

In the composition of the present invention, a hydrotalcite compound is contained as the component (C). The hydrotalcite compound is represented by the general formula [Mg _IX Al _X (OH)
₂ ] ^{x +} [(CO ₃ ) _{X / 2} .mH ₂ O] ^x- is a nonstoichiometric compound represented by a positively charged basic layer [Mg _IX Al _X
(OH) ₂ ] ^{x +} and a negatively charged intermediate layer [(CO
₃ ) _{X / 2} · mH ₂ O] ^x- is an inorganic substance having a layered crystal structure. Here, x is greater than 0 and 0.33
It is a number in the following range. Natural products are Mg ₆ Al ₂ (O
H) was obtained as ₁₆ CO ₃ · 4H ₂ O, synthesis products are commercially available mainly _{Mg 4 · 5 Al 2 (OH} ) in the form of ₁₃ CO ₃ · 3.5H ₂ O ones. Examples of the synthesis method include JP-B-46-2280, JP-B-50-30039, JP-B-51-29129, and JP-A-61-17.
A known method described in, for example, Japanese Patent No. 4270 can be exemplified. The hydrotalcite compound is obtained by reacting the hydrotalcite compound with perchloric acid in water at an arbitrary ratio, and replacing part or all of CO ₃ in the hydrotalcite compound with ClO _4. A partially introduced type or a perchloric acid introduced type may be used. Conventionally, hydrotalcite compounds have been added mainly for the purpose of improving the thermal stability of vinyl chloride resins in soft processing, but when added in hard or semi-hard processing, unexpected foaming often occurs. It was not used. However, in the present invention, an effect of improving the plate-out resistance in foam molding has been found,
Furthermore, it was found that the weathering resistance was also improved.

In the composition of the present invention, the content of the hydrotalcite compound as the component (C) is 0.3 to 10 parts by weight, preferably 0.5 to 5 parts by weight, per 100 parts by weight of the vinyl chloride resin. Department. When the content of the hydrotalcite compound is less than 0.3 parts by weight per 100 parts by weight of the vinyl chloride resin, the effect of improving the plate-out resistance is small, and the content of the hydrotalcite compound is 100 parts by weight of the vinyl chloride resin. If it exceeds 10 parts by weight, the extrudability deteriorates and the foam cells of the molded product become large,
In addition, it tends to be uneven.

As the foaming agent (D), a thermally decomposable organic foaming agent and a thermally decomposable inorganic foaming agent are used in combination. Examples of the organic blowing agent include N, N'-dinitrosopentamethylenetetramine, N, N'-dimethyl-N, N'-
Nitroso compounds such as dinitrosoterephthalamide; azo compounds such as azodicarbonamide and azobisisobutyronitrile; benzenesulfonylhydrazide, p, p'-
And hydrazides such as oxybis (benzenesulfonylhydrazide) and toluenesulfonylhydrazide. A foaming agent selected from sodium bicarbonate, ammonium bicarbonate, ammonium carbonate and the like, which is a pyrolytic inorganic foaming agent, is used in combination with the organic foaming agent. By using a thermally decomposable organic and inorganic foaming agent in combination, a foam molded article having a uniform and fine foam cell and a smooth, glossy, and high hardness surface layer can be obtained. The amount of the foaming agent can be appropriately determined according to the type of the foaming agent and the selection of the processing conditions. Usually, the organic foaming agent is used in an amount of 0.05 to 1 per 100 parts by weight of the vinyl chloride resin as the component (A). 0.0 parts by weight, more preferably 0.1 to 0.5 parts by weight, and the inorganic foaming agent is preferably 0.1 to 5.0 parts by weight, more preferably 0.5 to 3.0 parts by weight. Department. When the amounts of the organic foaming agent and the inorganic foaming agent are less than 0.05 part by weight and less than 0.1 part by weight, respectively, it is difficult to obtain an effective expansion ratio. Further, when the organic blowing agent is added in excess of 1.0 part by weight, the thermal stability of the composition may be deteriorated. When the inorganic blowing agent is used in an amount of more than 5.0 parts by weight, fine foam cells are generated. Tends to be difficult.

The composition of the present invention contains, in addition to the above-mentioned components, heat stabilizers and lubricants used in the processing of ordinary vinyl chloride resins, ultraviolet absorbers, impact resistance enhancers, pigments and plasticizers. And an antistatic agent and the like are appropriately added. The plate-out resistance varies depending on the lubricant used. Dibasic acid ester-based lubricants have better plate-out resistance than polyethylene wax-based lubricants. The molding method is not particularly limited, but usually an extrusion molding method is used.

Embodiments of the present invention are described below. (1) (A) 100 parts by weight of a vinyl chloride resin, (B) 0.5 to 30 parts by weight of a polymethyl methacrylate processing aid, (C) 0.3 to 10 parts by weight of a hydrotalcite compound, and (D) A vinyl chloride resin composition for foam molding, comprising an organic foaming agent and an inorganic foaming agent. (2) The average degree of polymerization of the vinyl chloride resin (A) is 400 to
The vinyl chloride resin composition for foam molding according to the above (1), which is 1200. (3) 100 ml of a chloroform solution in which the polymethyl methacrylate processing aid (B) contains methyl methacrylate in an amount of 50% by weight or more and 0.1 gr thereof is dissolved.
The vinyl chloride resin composition for foam molding according to the above (1) or (12), wherein the specific viscosity at 5 ° C is 0.10 to 1.00. (4) The vinyl chloride resin composition for foam molding according to any one of the above (1) to (3), wherein the polymethyl methacrylate processing aid (B) is 1 to 20 parts by weight per 100 parts by weight of the component (A). Stuff. (5) Hydrotalcite compound (C) is component (A) component 1
The above (1), which is 0.5 to 5 parts by weight per 00 parts by weight.
The vinyl chloride resin composition for foam molding according to any one of items (4) to (4). (6) The above (1) wherein the organic and inorganic foaming agents of the component (D) are blended in an amount of 0.05 to 1.0 part by weight and 0.1 to 5.0 parts by weight per 100 parts by weight of the component (A). ) ~
(5) The vinyl chloride resin composition for foam molding according to any of (5).

[0013]

The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples. The amounts of the respective components are based on weight unless otherwise specified. The plate-out resistance and the characteristics of the foam molded article were examined by the following methods. 1) Plate-out resistance After extruding 1 kg of the test composition with a test single-screw extruder, the adhesion state of the plate-out substance inside the die is visually observed, and then the adhesion weight of the plate-out substance is determined. -Judgment by visual observation A: No adhered substance was observed. B: White deposits are observed in an area of 10% or less inside the die. C: White deposits are observed in an area of 20 to 30% inside the die. D: White deposits are observed in an area of 80 to 100% inside the die.・ Measurement of adhesion amount The dice after the plate-out visual observation were weighed, the attached matter was removed with a copper scraper and gauze, and the dies were weighed again, and the difference in weight (mg unit).
Is the adhesion amount.

2) Foam Cell State The cut surface of the molded article is observed with an optical microscope and evaluated according to the following ranks. A: Fine and uniform cell diameter of 120 μm or less. B: Some cells are broken and coarse. C: Many cells are broken and coarse. 3) Surface properties The surface of the molded product is visually observed and touched, and evaluated according to the following rank. A: Smooth B: Slightly shark skin C: Shark skin 4) Foaming ratio The specific gravity of the molded product obtained by press-molding the material composition at 170 ° C. is defined as the true specific gravity, and the specific gravity of the extruded foam molded product is defined as the specific gravity of the molded product. It is measured by the method and determined by the following formula. Expansion ratio = true specific gravity / molded product specific gravity

5) Weathering and discoloration resistance After exposing the molded article for 400 hours according to the WS type of JIS A 1415 (accelerated exposure test method for plastic building materials), the color difference ΔE before and after exposure is determined by a photoelectric colorimeter (JIS Z 8722). The smaller the ΔE, the better the weathering resistance. If ΔE is 10 or more, discoloration is remarkable.

Examples 1 to 5 and Comparative Examples 1 to 6 The components shown in Table 1 were uniformly mixed with a Henschel mixer, and the resulting composition was subjected to extrusion foam molding under the following conditions. Table 1 shows the evaluation of plate-out resistance and the characteristics of the molded product. Test single screw extruder Extruder screw diameter: 20 mmφ screw: L / D = 20, CR = 2.5, rotation speed = 35 rpm Set temperature (° C.): C ₁ = 180, C ₂ = 190, H = 190, D = 195 Die shape: Belt, width 20 mm, height 0.8 mm Land length: 10 mm

[0017]

[Table 1]

Note * 1 ZEST 700L, manufactured by Shin-Daiichi Vinyl Co., Ltd., vinyl chloride homopolymer, average degree of polymerization 680 * 2 Hybrene B403, manufactured by Nippon Zeon Co., Ltd., a copolymer having a methyl methacrylate content of about 90% by weight. 0.78 * 3 Alkamizer 1, manufactured by Kyowa Chemical Industry Co., Ltd., Mg, specific viscosity (measured at 25 ° C. by taking a sample from 100 ml of a chloroform solution in which 0.1 g is dissolved)
_4.5 Al ₂ (OH) ₁₃ CO ₃ .3.5H ₂ O * 4 Azodicarbonamide * 5 Sodium bicarbonate * 6 Calcium carbonate CCR, manufactured by Shiraishi Calcium Co., Ltd. * 7 Calcium / zinc / tin composite stabilizer * 8 Polyethylene wax * 9 Dibasic ester lubricant * 10 Titanium oxide white pigment

In Examples 1 to 5 molded using the composition satisfying the requirements of the present invention, no plate-out was observed, or white deposits were observed in 10% or less of the inner area of the die. Was. The amount of adhesion was 10 mg or less, which was a small amount. In addition, the cell state, surface properties, and expansion ratio of the foamed molded product were good, indicating that the moldability was good as in the prior art (Comparative Examples 1 and 3). It is better to use a dibasic acid ester-based lubricant than a polyethylene wax-based lubricant in terms of plate-out resistance (Examples 1 and 3).
, And 2 and 4). When the hydrotalcite compound was not added, or when 0.2 parts by weight was added per 100 parts by weight of the vinyl chloride resin, white deposits were observed on most of the area in the die, and the deposit amount was as large as 30 to 60 mg. Was. In Comparative Example 6 using only an inorganic foaming agent as the foaming agent, the other components were the same as in Example 5, but the plate-out resistance was good, but the surface of the foam molded product was not smooth.

Examples 6 to 10 and Comparative Examples 7 to 8 The components of the formulations shown in Table 2 were uniformly mixed with a Henschel mixer, and the resulting composition was continuously operated with a large extruder under the following conditions. The extruder was stopped when streaking due to plate-out occurred on the surface of the molded product, and the time required until then, the plate-out resistance, and the characteristics of the molded product were examined. The results are shown in Table 2. Large single screw extruder Extruder screw 65 mmφ screw L / D = 20, CR = 2.5, rotation speed 15 rpm Set temperature (° C.) C ₁ = 110, C ₂ = 130, C ₃ = 150, C ₄ = 1 65 , H = 155, D = 160 Die shape Plate with two ribs, width 150 mm, rib thickness 10 mm and 5 mm, rib height 40 mm land length 100 mm

[0021]

[Table 2]

The notes are the same as in Table 1.

In Examples 6 to 10 in which the composition satisfying the requirements of the present invention was continuously molded by a large-scale extruder on an industrial scale, the time required for a stripping phenomenon due to plate-out to appear on the surface of the molded product, that is, The plate-out occurrence time was 90 to 10 in Comparative Examples 7 and 8 using the composition of the conventional formulation.
0 hours (about 4 days), 180 hours (7.5
Days) to 300 hours (12.5 days). In Examples 6 and 70, the appearance of the adhesion of the plate-out was apparently not improved by C. This is because the extruder was continuously operated until the streaking phenomenon appeared on the surface of the molded product. Whether or not the plate-out property has been improved is determined by the plate-out occurrence time. The foamed cell state, surface texture and specific gravity of the molded article according to the present invention (Examples 6 to 10) are as good as those of the prior art (Comparative Examples 7 and 8). It turns out that it is excellent in molding workability like the product. It is also shown that the weathering and discoloration resistance of a molded article according to the present invention is significantly improved as compared with a molded article according to the prior art.

[0024]

EFFECTS OF THE INVENTION By using the composition of the present invention, the plate-out resistance is good, the extruder can be operated continuously for a long period of time, and the molding processability is the same as that of the conventional vinyl chloride resin. Extrusion foam molding is possible, which provides a molded article having an expansion ratio, good foam cell state and surface properties, and improved weathering and discoloration resistance.

Claims (2)

[Claims] (A) 100 parts by weight of a vinyl chloride resin,
(B) Polymethyl methacrylate processing aid 0.5-3
0 parts by weight, (C) hydrotalcite compound 0.3-1
A vinyl chloride resin composition for foam molding, comprising 0 parts by weight and (D) an organic foaming agent and an inorganic foaming agent. 2. The vinyl chloride resin composition for foam molding according to claim 1, wherein the average degree of polymerization of the vinyl chloride resin (A) is from 400 to 1200.