JP2002012707A - Vulcanizable rubber composition and cross-linked rubber molding and its production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vulcanizable rubber composition which is suitable for producing a cross-linked rubber molding exhibiting high rubber elasticity, shape memory, and shape recovery. SOLUTION: This composition comprises a vulcanizable rubber (e.g. EPT), an amorphous resin (e.g. polystyrene), a softener (e.g. an aromatic mineral oil), and a compatibilizer compatible with both a rubber and an amorphous resin (e.g. styrenegraft polyethylene). When the composition is vulcanized and then molded at the glass transition temperature of the amorphous resin or higher, a cross-linked molding exhibiting a shape memory of 50% or higher, a shape recovery of 70% or higher, and a permanent elongation after 150% elongation of 20% or lower is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a rubber having excellent rubber elasticity,
The present invention relates to a vulcanizable rubber composition capable of producing a molded article having shape memory, a crosslinked rubber molded article having shape memory, and a method for producing the molded article.

[0002]

BACKGROUND OF THE INVENTION Conventionally, molded products called heat-shrinkable films, sheets, or tubes have been used in applications such as sealing and packaging of articles, coating electric wires and steel pipes, and coating glass bottles. Has been used.

As a typical example, a heat-shrinkable molded article made of polyvinyl chloride is widely known, but it has insufficient weather resistance and also causes the plasticizer contained therein to ooze out. there were. Accordingly, similar heat-shrinkable molded articles made of polyethylene or polypropylene have been developed, but their use has been limited because of their low rubber elasticity.

Japanese Patent Publication No. 3-60664 discloses a technique in which a crosslinked stretched product of an ethylene / 1-butene / polyene random copolymer rubber is applied to a heat-shrinkable film or sheet. Also, when polyethylene is blended with ethylene propylene diene rubber (EPT),
It is also known that heat-shrinkable tubes can be produced. However, according to the study of the present inventors, the rubber elasticity of any of these heat-shrinkable films, sheets, or tubes was not yet practically sufficient.

[0005] Furthermore, the chemical technology magazine "MOL, VOL.6 (19
89), pp. 42-46, by Sumio Takei, published by Ohmsha, Inc.), introduces various shape memory resins. According to the study by the inventors, the rubber elasticity is low and the shrinkage (start) temperature is low, so that there is inconvenience in use.

Under these circumstances, there is a demand for a heat-shrinkable molded article having high rubber elasticity and capable of freely controlling the shrinkage (starting) temperature and easy to use.

In general, vulcanized rubber products are prepared by kneading raw rubber with various compounding agents such as a reinforcing agent, a softening agent, a filler, a vulcanizing agent and the like, by press molding, extrusion molding or calendar molding. After being shaped according to the molding means, it is shipped as a product through a vulcanization process.

Here, a grain pattern or the like is formed on the product surface.
In the case of (shaping), a method of passing the compounded rubber compound through a molding roll (embossing roll) engraved with a pattern such as a grain when "distributing" the compounded rubber compound into a sheet is adopted. However, this molding method has the following manufacturing difficulties.

(1) The required amount of the compounded rubber compound is not constant in each place due to the uneven shape of the engraved pattern, or if there is a particularly deep place, the amount of the compound before being sent to the molding roll is not constant. The amount of compounded rubber compound had to be controlled during the dispensing roll. (2) In the case of fine patterns, the lower the viscosity of the compounded rubber compound used and the higher the adhesiveness, the more the compounded rubber compound becomes clogged in the fine concave portions of the surface of the molding roll, and the more frequently the rubber compound is used. Needed to clean the surface. (3) When the molding step and the vulcanization step are not continuous,
The "separated" long sheet is once wound up and stored, but before the vulcanization process is started, the surface of the sheet once molded is determined by the weight of the long sheet and the winding pressure. Was sometimes thinned or deformed.

When a vulcanized rubber product having a concave cross section and extruded into a ribbon having a small thickness is manufactured, the compounded rubber compound may be once formed into a concave shape by passing it through an extruder. By the time the vulcanization step was completed, the shaped shape was sometimes deformed. Furthermore, even for relatively thick vulcanized rubber products such as glass run channels for automobiles, it is necessary to design the die in detail taking into account the similar deformation that occurs during vulcanization.

Further, in the production of a vulcanized rubber product in the form of a tube having a blade like a weather strip sponge, not only is the die required to be precisely designed, but also the compounded rubber compound is required to have a blade. It was molded with the supporting pillars incorporated, and the complicated manufacturing process of separating the pillars after vulcanization into a product was adopted, and these also contributed to increasing the production cost.

In the case of a vulcanized rubber product having a short curved tube such as a joint hose used for a joint portion of a radiator hose for an automobile, the compounded rubber compound is once extruded into a hose. After that, it is cut short, then a mandrel is inserted into it, and then vulcanized in that state to produce. However, with a soft compound rubber compound, not only is it difficult to insert the mandrel, but also the hose is torn or damaged during the insertion, and the wound may remain on the product as it is.

As described above, there is a demand for a molded body that can easily return to its original shape even if the molded body is deformed for some reason after being formed into a final shape.

[0014]

SUMMARY OF THE INVENTION It is an object of the present invention to produce a heat-shrinkable molded article having high rubber elasticity and shape memory, capable of controlling the temperature for starting shape memory. To provide a vulcanizable rubber composition, a molded article thereof, and a method for producing the same.

Another object of the present invention is to have high rubber elasticity and shape memory, and to be able to return to the original shape even if it is temporarily deformed, and to be suitable for shaping such as molding. To provide a vulcanizable rubber composition, a molded article thereof, and a production method thereof.

[0016]

That is, the present invention provides a vulcanizable rubber (A), an amorphous resin (B), a softener (C) compatible with the amorphous resin, and a vulcanizable rubber. And a compatibilizer (D) compatible with both the amorphous resin and the amorphous resin, wherein the amorphous resin (B) is a vulcanizable rubber (A) 10
The present invention relates to a vulcanizable rubber composition compounded in an amount of 3 to 50 parts by weight with respect to 0 part by weight.

Here, the vulcanizable rubber (A) is a copolymer rubber composed of ethylene, an α-olefin having 3 to 20 carbon atoms and a non-conjugated polyene, and the amorphous resin (B) is
A polymer having a glass transition point of 70 ° C. or higher, for example, a styrene polymer is preferred.

The softener (C) is preferably a mineral oil softener, particularly an aromatic mineral oil, and is blended in an amount of 0.01 to 100 parts by weight based on 1 part by weight of the amorphous resin (B). Is desirable.

The compatibilizer (D) is preferably a copolymer containing at least one structural unit of the vulcanizable rubber (A) or the amorphous resin (B) as its own structural unit. A block copolymer including a block chain composed of the same structural unit as at least one structural unit of the vulcanizable rubber (A) or the amorphous resin (B), the vulcanizable rubber (A) or the amorphous resin ( A graft copolymer containing a trunk polymer or a branch polymer comprising at least one structural unit of B), or a rubber-like substance such as a vulcanizable rubber (A) and an amorphous resin (B) It is desirable that the amorphous polymer resin is a copolymer obtained by reacting with each other.

Specific examples of the compatibilizer include styrene-grafted polyethylene, styrene-grafted polypropylene, styrene-propylene block copolymer, styrene-isoprene-styrene triblock copolymer hydrogenated product, and styrene-butadiene-styrene triblock copolymer. Examples include a hydrogenated compound, a hydrogenated styrene-isoprene block copolymer, and a hydrogenated styrene-butadiene block copolymer.

The compatibilizing agent is an amorphous resin (B) 100
It is desirable to mix 0.01 to 100 parts by weight with respect to parts by weight.

The present invention also provides a crosslinked molded article produced by vulcanizing the above rubber composition, wherein (a) the shape recovery rate is 70% or more, and (b) the shape memory rate is 50%. The present invention relates to (c) a crosslinked rubber molded article having excellent physical properties and excellent shape memory properties and shape recovery properties having a permanent elongation after elongation of 150% of 20% or less.

Further, the method for producing a crosslinked rubber molded article is such that a vulcanized molded article is once produced from the above rubber composition, and then the vulcanized molded article is subjected to a temperature higher than the glass transition point of the amorphous resin (B). A method of shaping at a temperature and then cooling to a temperature below its glass transition point is preferred.

[0024]

DETAILED DESCRIPTION OF THE INVENTION Vulcanizable Rubber Composition The rubber composition according to the present invention comprises a vulcanizable rubber (A), an amorphous resin (B), a softener (C), and a compatibilizer. (D) is an essential component, and various compounding agents are added and mixed as necessary. Next, each component will be described in detail.

<Vulcanizable Rubber (A)> First, the vulcanizable rubber (A) that can be used in the present invention may be a natural rubber, a synthetic rubber, or a mixture thereof. Examples of the synthetic rubber include ethylene / α-olefin / non-conjugated polyene copolymer rubber, styrene butadiene rubber, nitrile rubber, chloroprene rubber, acrylic rubber, and hydrogenated NBR.

Among these, a particularly preferred synthetic rubber is an ethylene / α-olefin / non-conjugated polyene copolymer rubber. Here, the α-olefin has 3 to 2 carbon atoms.
0 olefins, propylene, 1-butene, 4
Examples thereof include -methyl-1-pentene, 1-hexene, 1-octene and 1-decene, and propylene and 1-butene are particularly preferably used. The molar ratio of ethylene to α-olefin (ethylene / α-olefin) in the copolymer is in the range of 60/40 to 85/15, preferably 65/35 to 80/20.

As the non-conjugated polyene, a cyclic or chain non-conjugated polyene is used. Examples of the cyclic non-conjugated polyene include 5-ethylidene-2-norbornene, dicyclopentadiene, 5-vinyl-2-norbornene, norbornadiene and methyltetrahydroindene, and examples of the chain non-conjugated polyene include 1, 4-hexadiene, 7-methyl-1,6-octadiene, 8-methyl-4-ethylidene-1,7-nonadiene and 4-ethylidene-1,7-undecadiene. These non-conjugated polyenes may be used alone or in combination of two or more to form a copolymer component.

Preferred ethylene / α-olefin / non-conjugated polyene copolymer rubbers obtained by combining the above monomers include ethylene / propylene / dicyclopentadiene copolymer rubber and ethylene / propylene / 5-ethylidene-2-norbornene copolymer rubber. Polymer rubber, ethylene / propylene / 1,4-hexadiene copolymer rubber, ethylene /
Examples thereof include 1-butene / 1,4-hexadiene copolymer rubber.

The iodine value indicating the non-conjugated polyene content in the copolymer is from 1 to 40, preferably from 2 to 35, more preferably from 3 to 30. Further, the intrinsic viscosity [η] of this copolymer rubber is 0.8 to 4.0, preferably 1.0 to 3.5, more preferably 1.1 when measured in decalin at 135 ° C. ~ 3.0 (dl / g).
When the iodine value and the intrinsic viscosity are in the above ranges, a crosslinked rubber molded article having excellent rubber elasticity can be produced.

A method for producing an ethylene / α-olefin / non-conjugated polyene copolymer rubber having such a constitution is already known, and for example, a method described in “Polymer Production Process (published by the Industrial Research Institute Co., Ltd., p. 309). To 330) ").

<Amorphous Resin (B)> Next, the kind of the amorphous resin (B) is not particularly limited.
Glass transition point (T
g) is a non-crystalline resin having a temperature of 70 ° C. or higher, preferably 70 to 200 ° C., more preferably 80 to 180 ° C. When the glass transition point is within the above range, a crosslinked rubber molded article having a shape such as a film, a sheet, a tube, or a deformed shape can keep its shape stably.

Specific examples of the amorphous resin include (1) a styrene resin, (2) an ethylene / cyclic olefin copolymer resin, (3) an acrylic resin, and (4) a vinyl chloride resin. . Here, as the styrene resin, (1) polystyrene, (2) an ABS resin which is a copolymer of acrylonitrile, butadiene and styrene,
(3) AES resin, which is a copolymer of acrylonitrile, EPT, and styrene, and (4) AAS resin, which is a terpolymer resin containing acrylonitrile, styrene, and special rubber as main raw materials. In addition, examples of the ethylene / cyclic olefin copolymer resin include an ethylene / norbornene copolymer resin and an ethylene / tetracyclododecene copolymer resin. Of these, styrene resins are preferably used.

If the affinity between the amorphous resin (B) and the vulcanizable rubber (A) is too high, for example, if both are compatible at the molecular level, the rubber of the resulting cross-linked molded article is When the amorphous resin is selected, it is desirable that the amorphous resin is not compatible with the vulcanizable rubber at the molecular level when the amorphous resin is selected, and that the amorphous resin is uniformly dispersed in the vulcanizable rubber in the form of particles.

The compounding amount of the amorphous resin is determined according to the vulcanizable rubber (A)
3 to 50, preferably 5 to 40, based on 100 parts by weight
More preferably, it is 5 to 30 parts by weight. When the blending amount of both is within this range, a crosslinked rubber molded article having an excellent balance between heat recovery and rubber elasticity can be obtained.

<Softener (C)> The softener (C) has compatibility with the amorphous resin, assists the dispersibility of the amorphous resin, and at the same time acts as a lubricant for the rubber. This is for improving workability, and sometimes controls the glass transition point of the amorphous resin. The following substances can be used as examples of such softeners.

(1) Petroleum softeners such as naphthenic process oils, aromatic process oils, lubricating oils, paraffin, liquid paraffin, petroleum asphalt, petrolatum, etc. (2) Coal tar, coal tar bitch etc. (3) Fat oil softeners such as castor oil, rapeseed oil, soybean oil, coconut oil, etc. (4) Tall oil (5) Waxes such as beeswax, carnauba wax and lanolin (6) Fatty acids such as ricinoleic acid, palmitic acid, stearic acid, barium stearate and calcium stearate or metal salts thereof

(7) Naphthenic acid or its metallic soap (8) Pine oil, rosin or its derivative (9) Synthetic polymer substance such as terpene resin, petroleum resin, coumarone indene resin, atactic polypropylene (10) Dioctyl lid Rate, dioctyl adipate
Ester plasticizers such as dioctyl sebacate, etc. (11) Carbonate ester plasticizers such as diisododecyl carbonate (12) Others, microcrystalline wax, sub (factice), liquid polybutadiene, modified liquid polybutadiene, liquid Thiocol, hydrocarbon synthetic lubricating oil, etc.

In the present invention, among these,
The mineral oil softeners (1), (2) and (9) are preferably used, and aromatic mineral oils exemplified by aromatic process oils are particularly desirable. These softeners are sold under trade names such as Diana Process AC-460 (product of Idemitsu Kosan Co., Ltd.), Diana Process AC-12 (product of Idemitsu Kosan Co., Ltd.), and Esso Process Oil 110 (product of Esso Oil Co., Ltd.). It can be used for the invention.

These softeners can be used as the vulcanizable rubber (A) 10
It is used in an amount of usually 100 parts by weight or less, preferably 70 parts by weight or less based on 0 parts by weight. Further, the weight composition ratio of the softener (C) and the amorphous resin (B) ((C) /
(B)) is desirably 1/100 to 100/1. When the compounding amount of the softening agent is within the above range, the processability of the rubber composition can be improved.

<Compatibilizer (D)> The compatibilizer (D) is a substance having compatibility with both the rubber and the amorphous resin. The material is not particularly limited as long as it promotes the action of stably dispersing uniformly. Such a compatibilizer is not limited in molecular structure, but it is a copolymer containing at least one structural unit of the vulcanizable rubber or the amorphous resin as its own structural unit. This is convenient for increasing the compatibility with both.

Examples of the compatibilizer include the following types. (1) It is a block copolymer and has a block unit composed of the same structural unit as at least one structural unit of the vulcanizable rubber or the amorphous resin. (2) It is a graft copolymer and has a trunk polymer or a branch polymer composed of the same structural unit as at least one structural unit of the vulcanizable rubber or the amorphous resin. (3) A copolymer formed by a rubber-like material and an amorphous polymer resin reacting with each other.

Among the compatibilizers, specific examples corresponding to the block copolymer or the graft copolymer described in (1) or (2) include styrene-grafted polyethylene, styrene-grafted polypropylene, styrene-isoprene-
Hydrogenated styrene triblock copolymer, hydrogenated styrene-butadiene-styrene triblock copolymer, hydrogenated styrene-isoprene block copolymer, hydrogenated styrene-butadiene block copolymer, etc. it can.

Further, the copolymer (3) will be described in more detail. The interpolymer reaction between the rubber-like material and the amorphous polymer resin is promoted, and the block copolymer or the graft copolymer is formed. It is what formed the union. Here, the rubbery material may be the same as or different from the above-described vulcanizable rubber (A), and the amorphous polymer resin may be the above-mentioned amorphous resin (B).
And may be the same or different. In addition, the reaction between the polymers can proceed by heating and mixing the rubber-like material and the amorphous polymer resin preferably using an extruder or the like, preferably in the presence of a radical initiator such as an organic peroxide. . Therefore, the copolymer of (3) may be a copolymer formed in advance by the above-described method, or a copolymer formed in the process of preparing a composition or the process of manufacturing a molded article. There may be. In the present invention, it is desirable to formulate a preformed copolymer as a compatibilizer.

The compounding amount of the compatibilizing agent is as follows.
The amount is 0.01 to 100 parts by weight, preferably 0.1 to 50 parts by weight, more preferably 0.2 to 10 parts by weight based on 00 parts by weight. When the compounding amount is within this range, the shape memory property of the vulcanized rubber molded article can be improved. Although the reason is not clear, it is considered that the compatibilizing agent stabilizes the amorphous resin fine particles dispersed in the blending step and affects the morphology of the rubber / amorphous resin alloy.

<Other Compounding Agents> The vulcanizable rubber composition according to the present invention contains a sulfur-based or organic peroxide-based vulcanizing agent and, if necessary, a vulcanization accelerator or a vulcanization aid. Is blended. In addition, a conventionally known compounding agent, for example, a reinforcing material, a processing aid, a pigment, an antioxidant, a filler, a foaming agent, and the like can be compounded within a range not to impair the object of the present invention. Next, various compounding agents will be described.

1. Vulcanizing agents As the sulfur-based compound, for example, sulfur, sulfur chloride,
Examples include sulfur dichloride, morpholine disulfide, alkylphenol disulfide, tetramethylthiuram disulfide, and selenium dithiocarbamate. Among them, sulfur is preferable, and these sulfur compounds are usually used in an amount of 0.1 to 1 based on 100 parts by weight of the vulcanizable rubber (A).
0, preferably 0.5 to 5, more preferably 1.0 to
It is added in a proportion of 3.0 parts by weight.

As the organic peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane , 2,5-dimethyl-
2,5-di (t-butylperoxy) hexyne-3, di-t-butyl peroxide, di-t-butylperoxy-
3,3,5-trimethylcyclohexane, di-t-butyl hydroperoxide and the like. Among them, dicumyl peroxide, di-t-butyl peroxide, di-
t-Butylperoxy-3,3,5-trimethylcyclohexane is preferably used. The amount of the organic peroxide used is usually 1 × 10 4 per 100 g of the vulcanizable rubber (A).
^{-3 to} 5 × 10 ^-2 , preferably 3 × 10 ^{-3 to} 3 × 10 ^-2 mol.

When a sulfur compound is used as a vulcanizing agent, it is preferable to use a vulcanization accelerator in combination. The following compounds can be used as the vulcanization accelerator. (1) N-cyclohexyl-2-benzothiazol-sulfenamide, N-oxydiethylene-2-benzothiazol-sulfenamide, N, N'-diisopropyl-
2-benzothiazolsulfenamide, 2-mercaptobenzothiazole, 2- (2,4-dinitrophenyl) mercaptobenzothiazole, 2- (2,6-diethyl-4-morpholinothio) benzothiazo And thiazole compounds such as dibenzothiazyl-disulfide

(2) Guanidine compounds such as diphenyl guanidine, triphenyl guanidine, diortho tolyl guanidine, etc. (3) Aldehyde amine compounds such as acetaldehyde-aniline condensate and butyl aldehyde-aniline condensate (4) 2-mercaptoimidazoline (5) Thiourea compounds such as diethylthiourea and dibutylthiourea

(6) Thiuram compounds such as tetramethylthiuram monosulfide and tetramethylthiuram disulfide (7) Dithiocarbamate compounds such as zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate and tellurium diethyldithiocarbamate (8) dibutylxanthogen Xanthate compounds such as zinc acid (9) Other zinc white

These vulcanization accelerators can be used as vulcanizable rubber (A)
0.1 to 20, preferably 0.2 to 10, more preferably 0.5 to 5 parts by weight is added to 100 parts by weight.

When an organic peroxide is used as a vulcanizing agent, it is preferable to use a vulcanizing aid in combination. Examples of the vulcanization aid include sulfur; quinone dioximes such as p-quinone dioxime; (meth) acrylic compounds such as ethylene glycol dimethacrylate and trimethylolpropane trimethacrylate; and diallyl phthalate. And allyl compounds such as triallyl isocyanurate; and other maleimide compounds and divinylpentene. Such a vulcanization aid is used in an amount of 0.5 to 2 with respect to 1 mol of the organic peroxide used.
Moles, preferably in equimolar proportions.

2. Processing aids Processing aids used in normal rubber processing can be used. Such processing aids include, for example, Risino-
Higher fatty acids such as luic acid, stearic acid, palmitic acid and lauric acid; higher fatty acid salts such as barium stearate, calcium stearate and zinc stearate; ricinoleate, stearate, palmitate, laurate, etc. And higher fatty acid esters. These processing aids are usually blended in an amount of 10 parts by weight or less, preferably 1 to 5 parts by weight, based on 100 parts by weight of the vulcanizable rubber (A).

3. Anti-aging agent In the present invention, excellent heat resistance and durability are exhibited without particularly adding an anti-aging agent, but the product life can be further extended by adding an appropriate amount. Examples of the antioxidant include aromatic secondary amine stabilizers such as phenylbutylamine and N, N'-di-2-naphthyl-p-phenylenediamine; dibutylhydroxytoluene, tetrakis [methylene-3 (3,5 Phenol stabilizers such as -di-t-butyl-4-hydroxyphenyl) cinnamate] methane; bis [2-methyl-4- (3-n-alkylthiopropionyloxy) -5-t-butylphenyl Thioether stabilizers such as sulfides; and dithiocarbamate stabilizers such as nickel dibutyldithiocarbamate. These anti-aging agents can be used alone or in combination of two or more,
Usually 0.1 to 100 parts by weight of the vulcanizable rubber (A).
5, preferably 0.5 to 3 parts by weight.

4. Reinforcing materials, fillers Reinforcing materials are SRF, GPF, FEF, MAF, I
Various carbon blacks such as SAF, SAF, FT, and MT, and finely divided silica are appropriately used. As the filler, light calcium carbonate, heavy calcium carbonate, talc, clay and the like are used. These reinforcing materials and fillers are usually blended in a proportion of 200 parts by weight or less, preferably 150 parts by weight or less, based on 100 parts by weight of the vulcanizable rubber (A).

5. Pigments Inorganic pigments such as titanium white and organic pigments such as naphthol green B can be used. These pigments can be generally added in an amount of up to 20 parts by weight, preferably up to 10 parts by weight, based on 100 parts by weight of the vulcanizable rubber (A).

6. Foaming Agent The vulcanizable rubber composition according to the present invention can be foamed by adding a foaming agent to the foamed composition to produce a crosslinked rubber molded article having a foam structure. As the foaming agent used for foam molding, any of commercially available foaming agents can be suitably used, and examples thereof include the following compounds.

(1) Inorganic foaming agents such as sodium bicarbonate, sodium carbonate, ammonium bicarbonate, ammonium carbonate and ammonium nitrite. (2) N, N'-dinitrosoterephthalamide, N,
Nitroso compounds such as N'-dinitrosopentamethylenetetramine; (3) Azo compounds such as azodicarbonamide, azobisisobutyronitrile, azocyclohexylnitrile, azodiaminobenzene and barium azodicarboxylate.

(4) benzenesulfonyl hydrazide,
Sulfonyl hydrazide compounds such as toluenesulfonyl hydrazide, p, p'-oxybis (benzenesulfonyl hydrazide) and diphenylsulfone-3,3'-disulfenyl hydrazide; (5) calcium azide, 4,4'-diphenyl disulfonyl azide; Azide compounds such as p-toluenesulfonyl azide.

Among these, azo compounds, sulfonyl hydrazide compounds and azide compounds are preferably used. The amount of the foaming agent is appropriately adjusted so that the specific gravity of the foam after vulcanization and foaming becomes 0.01 to 0.9, and the foaming agent is usually added to 100 parts by weight of the vulcanizable rubber (A). , 0.5
~ 30, preferably 1-20, more preferably 2-10
It is blended in a ratio of parts by weight.

If necessary, a foaming aid may be used together with a foaming agent. The addition of a foaming aid is effective in controlling the decomposition temperature of the foaming agent, making the air bubbles uniform, and the like. Examples of the foaming aid include organic acids such as salicylic acid, phthalic acid, stearic acid, and oxalic acid, urea and derivatives thereof.

<Preparation of Composition> In the present invention, a vulcanizable rubber (A), an amorphous resin (B), a softener (C), and a compatibilizer (D), and if necessary, a vulcanizing agent. By adding other compounding agents such as the above, mixing them sufficiently, and kneading them, a vulcanizable rubber composition can be prepared. The following method is described as an example of the mixing method.

First, a vulcanizable rubber (A) such as an ethylene / α-olefin / non-conjugated polyene copolymer rubber, an amorphous resin (B) and a compatibilizer (D) are mixed with an extruder, for example, a twin screw. Using an extruder, mix at 100-300 ° C. and add kneading. A softening agent (C) and various additives such as a reinforcing material, a filler and a pigment, which are added as necessary, are added to the kneaded material, and the mixture is mixed with a mixer such as a Banbury mixer.
Kneading is performed at a temperature of from about 1 to about 170C for about 3 to 30 minutes. Next, if necessary, a vulcanizing agent, a vulcanization accelerator or a vulcanization aid is additionally mixed with the kneaded material by using rolls such as open roll, and the roll temperature is about 40 to 80. The mixture is kneaded at a temperature of about 3 to 30 minutes for about 3 to 30 minutes and "dispensed" to prepare an unvulcanized rubber compound, that is, a vulcanizable rubber composition formed into a ribbon or sheet.

In the composition thus obtained, the amorphous resin (B) is in the form of particles and is uniformly dispersed in the vulcanizable rubber (A). 0.1 ~
200, preferably 0.1 to 100, more preferably 0.1 to 50 μm. When the particle diameter of the amorphous resin is within the above range, the deformation and recovery of the amorphous resin particles occur promptly, exhibiting a high effect on shape recovery and expression of shape memory described later.

Crosslinked Rubber Molded Product The crosslinked rubber molded product according to the present invention has (a) a shape recovery rate of 7
0% or more, preferably 80% or more, more preferably 85%
% Or more, (b) the shape memory ratio is 50% or more, preferably 60% or more, more preferably 70% or more, and (c) the permanent elongation after 150% elongation is 20% or less, preferably 18% or less, more preferably 15% or less.

Such a crosslinked rubber molded article is a molded article having both a high shape recovery rate and a high shape memory rate, and a permanent elongation after 150% elongation, which is an index of rubber elasticity, is 20% or less. It is also a molded article having high rubber elasticity.

Here, the shape recovery rate, the shape memory rate and 1
The permanent elongation after 50% elongation can be measured according to the method described below. (1) Shape recovery rate and shape memory rate First, using a press molding machine, a thickness of 2.2 to 2.5 mm
Vulcanized sheet is vulcanized in a mold at 170 ° C. for 12 minutes, 2 mm (thickness) × 15 cm (length) × 12 cm
A (horizontal) vulcanized sheet is obtained. 10m from this vulcanized sheet
A test piece is prepared by punching a rectangular plate of m (width) x 60 mm (length).

Next, three points were set in the length direction of the central portion of the test piece.
A 0 mm mark was drawn, and the test piece was deformed using a jig so that the mark became 60 mm. The test piece was placed in an oven at 180 ° C. and left for 5 minutes. Thereafter, the test piece was removed from the oven. Remove and cool with water. One day after the jig was removed, the distance between marked lines (L ₁ ) drawn on the surface of the test piece was measured. Next, the test piece is placed again in an oven at 180 ° C., left for 5 minutes, taken out, left at room temperature for 30 minutes, and then the distance between marked lines (L ₂ ) is measured again.

The shape recovery rate and the shape memory rate are calculated according to the following equations using the distances between the reference lines (L ₁ ) and (L ₂ ) measured as described above. Shape recovery rate [%] = [(L ₁ −L ₂ ) × 100] / [L ₁
−30] Shape memory ratio [%] = [(L ₁ −30) × 100] / [6
0-30]

(2) Permanent elongation after 150% elongation The permanent elongation after 150% elongation is measured according to JIS K6301. The test piece is used by punching out a JIS No. 3 test piece from a vulcanized sheet of 2 mm (thickness) × 15 cm (length) × 12 cm (width) formed at the time of the test.

The crosslinked rubber molded article having these physical properties is
The vulcanizable rubber composition comprising the vulcanizable rubber (A), the amorphous resin (B), the softener (C), and the compatibilizer (D) is subjected to a crosslinking treatment according to a production method described later. The crosslinked rubber molded article thus obtained has a structure in which the amorphous resin is dispersed in the crosslinked rubber layer in the form of particles.

The reason why this crosslinked rubber molded article exhibits the above-mentioned shape memory property is not clear, but the present inventors think as follows. That is, when the vulcanized rubber is shaped at a high temperature, the particles of the amorphous resin dispersed in the crosslinked rubber are deformed into a sheet shape in the direction of deformation, which increases the rubber elasticity (deformation recovery). Hindering. However, when heated again under no tension, the shape of the amorphous resin returns to the original particle shape, acts as a filler in the crosslinked rubber molded article, and exhibits high rubber elasticity at the operating temperature.

Method for Producing Crosslinked Rubber Molded Article The crosslinked rubber molded article having the above-mentioned physical properties can be produced under ordinary molding methods and conditions. Next, an example of the manufacturing method will be described. First, the unvulcanized rubber compound was extruded, calendered, pressed, injection-molded, transferred,
It is molded into a desired shape using a molding machine or the like. Simultaneously with or after molding, the molded body is usually placed in a vulcanizing tank for 15 minutes.
Crosslinking is carried out by heating at 0 ° C. to 270 ° C. for 1 to 30 minutes, or foam molding and crosslinking are performed to obtain a crosslinked rubber molded article. As the vulcanizing tank, a steam vulcanizing can, a hot air vulcanizing tank, a glass bead fluidized bed, a molten salt vulcanizing tank, a microwave vulcanizing tank, and the like can be used. Alternatively, they can be used in combination.

In the method for producing a crosslinked rubber molded article according to the present invention, the crosslinked rubber molded article thus obtained is further shaped at a temperature not lower than the glass transition point of the amorphous resin, After being placed in an atmosphere having the above temperature or in an atmosphere having a temperature equal to or higher than the glass transition point, the shape is formed at a temperature equal to or higher than the glass transition point of the amorphous resin. Thereafter, the mixture is cooled to a temperature lower than the glass transition point. The cooling method may be any of natural cooling, water cooling, air cooling, and the like.

The crosslinked rubber molded article obtained by shaping at a temperature equal to or higher than the glass transition point of the amorphous resin is shaped even after the force applied for final shaping is removed. Shape,
For example, the shape of a film, sheet, tube or the like is maintained as it is. However, when the molded article is again placed in an atmosphere at a temperature equal to or higher than the glass transition point of the amorphous resin, it can be returned to the shape of the vulcanized rubber molded article before final shaping, that is, it can return to the original shape. it can.

Therefore, for example, a tube-shaped crosslinked rubber molded article having a large inner diameter after final shaping, and a tube-shaped crosslinked rubber molded article having a smaller inner diameter before final shaping. In some cases, a tube-shaped crosslinked rubber molded article having a small inner diameter can be returned by a reheating operation, and expansion and contraction can be repeated.

[0077]

Next, the present invention will be described with reference to examples.
The present invention is not limited by these examples.

Examples 1 to 3 Ethylene / propylene / non-conjugated polyene copolymer rubber, amorphous resin, softener and compatibilizer used were as follows. (1) Ethylene / propylene / 5-ethylidene-2-norbornene copolymer rubber (hereinafter abbreviated as EPT) Ethylene / propylene (molar ratio) = 67/33 Iodine value 23 [η] = 2.17 (dl / g) (2) Amorphous resin: polystyrene Nippon Polystyrene Co., Ltd., product name: G747R Glass transition point: 127 ° C. (3) Softener: aromatic process oil Idemitsu Kosan Co., Ltd. product, trade name: Diana Process AC-4
60 (4) Compatibilizer: Styrene-grafted polyethylene Trade name Modiva A1100 polystyrene / polyethylene = 30/70 (% by weight)

First, the above-mentioned EPT, polystyrene, softener, compatibilizer and various compounding agents were kneaded for 2 minutes at a temperature of 120 ° C. or more using a Banbury mixer at the following ratio to obtain a compound. .

Composition of the blend: (The blending amount is shown in parts by weight) EPT 110 Polystyrene 20 Softener 103 Compatibilizer 0.2 Carbon black 160 Stearic acid 1 Zinc white (Inoue lime product: AZO-B) 5 Processing assistant Agent (Lion product: PEG # 4000) 2 Dewatering agent (Inoue lime product: VESTA PP) 5

Next, the roll surface temperature was set to 60 ° C.
Thereafter, a 6-inthio-pump roll set at 60 ° C. was prepared, and the above-mentioned composition was wound around a roll. On this occasion,
Various compounding agents were added to the above-mentioned compound, adjusted so as to have the following compounding formula, kneaded on an open roll, and separated to obtain a 2.2 mm thick unvulcanized sheet. I got it.

Composition of Final Formulation: (Blending amount is shown in parts by weight) Vulcanization Accelerator CBS (Sanshin Chemical Industries: Noxeller CZ) 0.8 Vulcanization Accelerator ZnBDC Sanshin Chemical Industrial Products: Sancera-BZ) 1.5 Vulcanization Accelerator TMDT (Sanshin Chemical Industrial Products: Sancera-TT) 0.5 Vulcanization Accelerator EU (Sanshin Chemical Industrial Products: Sancera-22-C) 0.5 Vulcanization accelerator TeEDC (Sanshin Chemical Industries: Sansera-TE) 0.2 Vulcanizing agent (Sanshin Chemicals: Sanfel R) 1.5 Sulfur 0.3

The unvulcanized sheet was formed using a press molding machine.
By press molding in a mold at 170 ° C. for 12 minutes, a vulcanized sheet of 2 mm (thickness) × 15 cm (length) × 12 cm (width) was obtained. Then, from this vulcanized sheet, 10
A rectangular test piece of mm (width) x 60 mm (length) was punched out, and the shape memory ratio and the shape recovery ratio were determined by the above-mentioned method using this test piece. The shape memory processing temperature at this time was 100 ° C.

Further, a JIS No. 3 test piece was punched from the above vulcanized sheet, and the tensile strength, elongation, hardness, and permanent elongation after 150% elongation were measured by the following methods. It was also noted. (1) Tensile test: Based on JIS K6251. (2) Hardness: based on JIS K6251. (3) Permanent elongation after 150% elongation: JIS K630
1.

Example 2 In Example 1, a block copolymer having a polystyrene block chain and a polyethylene / polypropylene block copolymer block chain as a compatibilizer (Kuraray product: Septon 200 (trade name))
Example 1 except that styrene content of 30% by weight was used.
The same was done. The results are also shown in Table 1.

[0086]

[Table 1]

[0087]

As described above, the vulcanizable rubber composition according to the present invention contains an amorphous resin, a softening agent and a compatibilizing agent, and thus has high rubber elasticity, shape memory and shape recovery. Thus, a crosslinked rubber molded article having good properties can be produced.

Further, by selecting an amorphous resin having an appropriate glass transition point, the crosslinked rubber molded article produced therefrom can easily control the shape memory starting temperature and can be easily used. The body is obtained.

Further, according to the present invention, (1) the crosslinked rubber molded article produced from the vulcanizable rubber composition has excellent rubber elasticity and shape memory and shape recovery properties. After the shaping and shaping, even if the deformation temporarily occurs, the shape can be easily returned to the original shape. At that time, a crosslinked rubber molded article can be produced from the rubber composition by a simple production method.

Accordingly, the vulcanizable rubber composition according to the present invention and the crosslinked rubber molded article produced therefrom may be formed into a film, sheet or tube shape, etc., which may have a pattern such as a grain. As a heat-shrinkable molded article having
Applications such as various seal materials, grommets, gathers for clothes, connecting members for deformed pipes, and joint hoses such as radiator hoses for automobiles, glass run channels, weather strip sponges It can be widely used for applications such as automobile parts.

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Claims (16)

[Claims] 1. A vulcanizable rubber (A), an amorphous resin (B), a softener (C) compatible with the amorphous resin, and both the vulcanizable rubber and the amorphous resin. A composition comprising a compatibilizer (D) which is compatible with the vulcanizable rubber (A) and 100 parts by weight of the vulcanizable rubber (A).
A vulcanizable rubber composition, which is added in an amount of 0 parts by weight. 2. The method according to claim 1, wherein the softener (C) is an amorphous resin (B).
The vulcanizable rubber composition according to claim 1, wherein the rubber composition is contained in an amount of 0.01 to 100 parts by weight per 1 part by weight. 3. The method according to claim 1, wherein the compatibilizer (D) is added in an amount of 0.01 to 100 parts by weight based on 100 parts by weight of the amorphous resin (B). The vulcanizable rubber composition as described in the above. 4. The vulcanizable rubber (A) is a copolymer rubber comprising ethylene, an α-olefin having 3 to 20 carbon atoms and a non-conjugated polyene.
The vulcanizable rubber composition according to any one of claims 1 to 3. 5. The vulcanizable rubber according to claim 1, wherein the amorphous resin (B) is a polymer having a glass transition point of 70 ° C. or higher. Composition. 6. The vulcanizable rubber composition according to claim 1, wherein said amorphous resin (B) is a styrene polymer. 7. The vulcanizable rubber composition according to claim 1, wherein the softener (C) is a mineral oil softener. 8. The vulcanizable rubber composition according to claim 1, wherein the softener (C) is an aromatic mineral oil. 9. The vulcanizable rubber (A) wherein the compatibilizer (D) is
The vulcanizable rubber composition according to any one of claims 1 to 8, wherein the copolymer is a copolymer containing at least one structural unit of the amorphous resin (B) as its own structural unit. object. 10. A block copolymer comprising a block chain comprising the same structural unit as at least one structural unit of the vulcanizable rubber (A) or the amorphous resin (B). 9. The method according to claim 1, wherein the two are united.
A vulcanizable rubber composition according to any one of the above. 11. The compatibilizer (D) contains a stem polymer or a branch polymer composed of the same structural unit as at least one structural unit of the vulcanizable rubber (A) or the amorphous resin (B). The vulcanizable rubber composition according to any one of claims 1 to 8, which is a graft copolymer. 12. The method according to claim 1, wherein the compatibilizer (D) is styrene-grafted polyethylene, styrene-grafted polypropylene, styrene-propylene block copolymer, styrene-isoprene-styrene triblock copolymer hydrogenated product, styrene-butadiene-styrene tributylene. It is at least one copolymer selected from the group consisting of hydrogenated block copolymers, hydrogenated styrene-isoprene block copolymers, and hydrogenated styrene-butadiene block copolymers. Item 10. The vulcanizable rubber composition according to any one of Items 1 to 8. 13. The method according to claim 1, wherein said compatibilizer (D) is a copolymer obtained by reacting a rubbery substance and an amorphous polymer resin with each other. A vulcanizable rubber composition according to any one of the above. 14. The composition according to claim 1, wherein the particles of the amorphous resin (B) are dispersed in the form of particles having an average particle diameter of 0.1 to 200 μm. The vulcanizable rubber composition according to any one of the above. 15. A crosslinked molded article obtained by vulcanizing the rubber composition according to any one of claims 1 to 14, wherein (a) the shape recovery rate is 70% or more, and (b) shape memory. 50% rate
(C) The permanent elongation after 150% elongation is 20%
A crosslinked rubber molded article characterized by the following. 16. A vulcanized molded article is once produced from the rubber composition according to any one of claims 1 to 14, and then the vulcanized molded article has a glass transition point higher than that of the amorphous resin (B). A method for producing a crosslinked rubber molded article, comprising shaping at a temperature and then cooling to a temperature lower than the glass transition point.