JP2987215B2 - Crosslinked foam sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crosslinked foamed sheet which is excellent in shape retention and can be suitably used as a cover material for automobile interior parts and the like.

[0002]

2. Description of the Related Art A vinyl chloride resin two-layer sheet is known as one using a vinyl chloride resin foam as a pad layer. The sheet has flexibility in surface decoration, durability, and a soft feeling. Since it is suitable for high-cycle production such as thermoforming, which is an economical processing method, in addition to cushioning and excellent sound absorbing properties, it is widely used as a cover material for automobile interior parts.

However, in recent years, automobile interior parts and the like have been required to have an elongation that can withstand a deep drawing nearly twice as much as the conventional one and a shape retaining property after molding in accordance with the diversification and complexity of the design and shape of the automobile. Is growing.

A method for molding a resin composition comprising a vinyl chloride polymer, a foaming agent, a crosslinking agent and the like into a highly foamed article is disclosed in JP-B-52-10370 and JP-B-52-1649.
No. 8 and JP-A-59-223732.

[0005] The high-foamed products obtained by these methods are crosslinked and thus have good heat resistance and excellent high-temperature pressure resistance, and do not suffer from problems such as collapse or tearing due to the pressure of vacuum molding or the like. It is difficult to plastically deform even at high temperature, and it is difficult to maintain the shape of a molded product.

[0006]

[Problems to be Solved by the Invention] In the vacuum forming of a foamed vinyl chloride sheet, in deep drawing usually exceeding 250%, it is difficult to form only by vacuum suction at a heating temperature that does not impair the appearance of the drawing pattern. Therefore, it is customary to perform plug assist.

At this time, the heated sheet is rapidly cooled while being stretched in contact with the plug, and is cooled to 70 to 80 ° C.

[0008] On the other hand, the practical temperature of the molded article when it is mounted in a vehicle may rise to 70 to 80 ° C, so that the molding temperature is too close to the practical temperature. Thermoplastic vinyl chloride resin, which is an amorphous material and does not have a yield point, can be cross-linked or non-cross-linked. Depending on the degree, the aesthetic shape intended for the design could not be maintained, and the commercial value was significantly impaired.

It is an object of the present invention to provide a vinyl chloride foam sheet which has improved the above-mentioned conventional disadvantages and has excellent shape retention after molding.

[0010]

According to a first aspect of the present invention, a vinyl chloride resin composition has a heat distortion temperature of ASTM D648,
The crosslinked foamed sheet contains a modifier at 70 ° C. or higher at a load of 18.5 KGF / cm ² and 5 parts by weight or more based on 100 parts by weight of a vinyl chloride resin.

In a second aspect, the modifier of the first aspect is an acrylonitrile-styrene copolymer (hereinafter referred to as AS) in which the content of a resin, methyl methacrylate or acrylonitrile and styrene is 60% or more. Abbreviated),
Acrylonitrile-butadiene-styrene copolymer (hereinafter abbreviated as ABS), acrylonitrile-ethylenepropylenediene-styrene copolymer (hereinafter abbreviated as AES),
Methyl methacryl / butadiene / styrene copolymer (hereinafter abbreviated as MBS), acrylonitrile / chlorinated polyethylene / styrene copolymer (hereinafter abbreviated as ACS)
It is of a configuration consisting of one or a combination of two or more species. If the content of the resin component is 60% or less, the shape retention effect is impaired due to rubber shrinkage after stretching.

The vinyl chloride resin and the crosslinking agent which are the main components of the crosslinked foamed sheet of the present invention are not particularly limited, but a vinyl chloride copolymer having a hydroxyl group or a carboxyl group in a molecule, an isocyanate A crosslinking reaction system with is preferred. The reaction time can be reduced as compared with other crosslinking methods, and an economic effect can be expected.

The vinyl chloride copolymer having a hydroxyl group or a carboxyl group in the molecule is, for example, a copolymer of a vinyl chloride monomer and a comonomer having a hydroxyl group or a carboxyl group in the molecule and copolymerizable with the vinyl chloride monomer. It can be manufactured by doing.

Comonomers having a hydroxyl group or a carboxyl group in the molecule to be copolymerized include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, and 3-chloro-2. One or more of -hydroxypropyl methacrylate, 3-hydroxybutyl acrylate, ethyl-2-hydroxyethyl fumarate, hydroxybutyl vinyl ether, methacrylic acid, acrylic acid, monobutyl maleate, undecylenic acid and the like can be used.

The modifier used in the present invention has a heat distortion temperature of 7 at an ASTM D648, 18.5 KGF / cm ² load.
0 ° C. or higher is desirable, and AS, ABS, MBS, ACS, A and A having a resin content of methyl methacrylate or acrylonitrile and styrene of 60% or more are contained.
A copolymer such as ES or a ternary polymer is preferred. The heat distortion temperature is ASTM D648, 18.5 KGF /
The reason why the temperature is set to 70 ° C. or higher under a load of cm ² is that an effect of suppressing shape recovery is expected at a practical temperature at which the product after forming and stretching rises to an atmosphere of 70 to 80 ° C.

The use ratio of the modifier is not necessarily limited in the range of 5 parts by weight or more with respect to 100 parts by weight of the vinyl chloride resin as the main component, but usually the composition for the foamed sheet of the present invention is used. In the case of considering the presence or absence of a plasticizer described later, kneadability with vinyl chloride copolymer, processability, expansion ratio of foam, shape retention, economy, etc. 5 to 100 parts by weight of the vinyl resin composition
A range of 50 parts by weight is preferred.

Compounds having at least two functional groups capable of reacting with a hydroxyl group or a carboxyl group in a vinyl chloride copolymer, such as a hydroxyl group or a carboxyl group, can be used as a crosslinking agent. It is a compound having a directly reacting isocyanate group or blocked isocyanate group, carboxyl group, acid anhydride, hydroxyl group, amino group, substituted amino group and the like, and specific examples include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, Methylol propane-tolylene diisocyanate, polymethylene polyphenyl isocyanate, succinic acid, glutaric acid, adipic acid, pimelic acid, azelaic acid, phthalic acid, phthalic anhydride, maleic anhydride, ethylene glycol, glycerin, triglyceride Jill isocyanurate, 4, 4'
Diaminodiphenylmethaneglycidylamine, methylolmelamine and the like.

The foaming agent which is a component of the composition of the present invention comprises:
Usually, any material may be used as long as it is generally used for foam molding of a vinyl chloride resin, and specifically, azodicarbonamide, azobisisobutyronitrile, dinitrosopentamethylenetetramine, N.N'-dimethyl-N.
Organic foaming agents such as N'-dinitrosoterephthalamide, paratoluenesulfonyl hydrazide, P.P'-oxybis (benzenesulfonyl hydrazide) and inorganic foaming agents such as sodium bicarbonate can be used. Can be used.

As the plasticizer, any plasticizer may be used as long as it is used for ordinary vinyl chloride resins. For example, an esterified product of phthalic acid, isophthalic acid, trimellitic acid or pyromellitic acid with an aliphatic or aromatic alcohol, etc. ,
Specifically, dibutyl phthalate, dioctyl phthalate, dibutyl isophthalate, trioctyl trimellitate, and the like are used. In addition, fatty acid ester plasticizers such as phosphate ester plasticizers, dioctyl adipate, and epoxy plasticizers are used. And these can be used alone or in combination.

In the vinyl chloride resin composition for a crosslinked foamed sheet of the present invention, in addition to the above-mentioned essential components, other than the ordinary vinyl chloride resin having no hydroxyl group or carboxyl group, it is used for ordinary vinyl chloride resin. The resulting stabilizer, filler, flame retardant, colorant, etc. may be added.

The foamable vinyl chloride resin composition for a crosslinked foamed sheet of the present invention can be obtained by decomposing each of the above-mentioned components, that is, a vinyl chloride copolymer having a hydroxyl group or a carboxyl group in a molecule, a foaming agent or a crosslinking agent. While maintaining the temperature at which no melting occurs, the mixture is uniformly mixed with a known mixing device such as a ribbon blender, a Henschel mixer, or a kneader, and further, partially mixed with a device such as a calender, an extruder, or a roll at a temperature lower than its melting temperature. It is formed into a crosslinked sheet having a thickness of 0.5 to 5.0 mm and then heated to a temperature not lower than the decomposition temperature of the foaming agent and foamed at a foaming ratio of 2 to 40 times to produce a foamed sheet.

[0022]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples unless departing from the gist thereof.

As the vinyl chloride copolymer, A- (1)
A vinyl chloride copolymer A- (2) having a polymerization degree of 2,800 containing 1% ethylene and a vinyl chloride copolymer having an average polymerization degree of 1,400 containing 2-hydroxypropyl acrylate (3% by weight) was modified. The following four types were used as fillers. B- (1) ABS (Acrylonitrile and styrene content 70%, ASTM D648, 18.5KG
F-cm ² load, heat deformation temperature 110 ° C) B- (2)
MBS (methyl methacrylate and styrene content 70%, ASTM D648, 18.5 KGF / cm ²
B (3) AS (acrylonitrile and styrene content 100%, ASTM D)
648,18.5KGF / cm ² thermal deformation temperature 100 ° C. according to the load) B- (4) AES (acrylonitrile and styrene content 70%, ASTMD648,18.5K
Thermal deformation temperature 85 ° C under GF / cm ² load)

100 parts by weight of vinyl chloride copolymer, 5 parts by weight of hexamethylene diisocyanate (crosslinking agent), 0.5 parts by weight of calcium stearate (stabilizer), and 60 parts by weight of dioctyl phthalate (plasticizer) Azodicarbonamide (a foaming agent) was mixed in the proportions shown in the following table to obtain vinyl chloride resin compositions, and the compositions were kneaded with a roll at 150 ° C. for 5 minutes to obtain an unfoamed sheet.

Next, the unfoamed sheet was heated in hot air at 220 ° C. for 2 minutes, and the shape retention of the foamed sheet of the present invention after stretching was measured. For comparison, A-
Using (1), the test was conducted in the same manner as in the case where no modifier was used, and the results shown in the following table were obtained.

The following method was used to measure the shape retention ratio, which is a property exhibiting the shape retention effect.

The specimen was preheated in an atmosphere of 120 ° C. for 5 minutes and stretched 200% with a normal tensile tester (stretch length L
₁ ) After holding for 30 seconds, remove the heating chamber and air-cool the test piece to 20 ° C.

A test piece left and adjusted at 20 ° C. for 1 hour is heated to 80 ° C.
After reheating for 5 hours with the gear open, adjusting for 1 hour at 20 ° C., measure the dimensional change (length L ₂ after reheating), determine the shape retention rate after re-heating at 80 ° C. after forming and stretching by the following formula. Ask.
In addition, this numerical value shows that shape retention is so high that it is large. Hokatachiritsu _{= L 2 / L 1 × 100} (%)

[0029]

[Table 1]

[0030]

As is clear from the above table, the present invention can achieve a shape retention of 70% or more by blending a specific modifier into a vinyl chloride resin composition. It is possible to obtain a sheet material that has improved shape retention and can respond to diversified and complicated designs such as automotive interior materials.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takashi Horie 1876, Higashi-cho, Hamamatsu-shi, Shizuoka Prefecture Inside Kyowa Leather Co., Ltd. (72) Inventor Sadayuki Takeyama 1876, Higashi-cho, Hamamatsu-shi, Shizuoka Prefecture Kyowa Leather Co., Ltd. (72) Inventor Yoshiro Umemoto 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Yukihiro Kito 1 Toyota Town Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Yukio Ishihara Yoshihara Town, Toyota City, Aichi Prefecture 25, Ueikeike Inside Arako Co., Ltd. (58) Field surveyed (Int.Cl. ⁶ , DB name) C08J 9/06

Claims (2)

(57) [Claims] 1. A vinyl chloride resin composition containing 5 parts by weight of a modifier having a heat distortion temperature of 70 ° C. or more at a load of 18.5 KGF / cm ^{2 according} to ASTM D648, based on 100 parts by weight of the vinyl chloride resin. A crosslinked foamed sheet containing the above. 2. The acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene, wherein the modifier according to claim 1 is methyl methacrylate or acrylonitrile as a resin component and the content of styrene is 60% or more. One or two of a copolymer, an acrylonitrile / ethylene propylene diene / styrene copolymer, a methyl methacryl / butadiene / styrene copolymer, an acrylonitrile / chlorinated polyethylene / styrene copolymer
A crosslinked foamed sheet comprising a combination of more than one species.