JPS62174263A - Shape-memory elastomer - Google Patents

Abstract

PURPOSE:To provide the title elastomer whose shape can be restored when temp. is raised, even though deformation occurs at room temp., consisting of a mixture of a vinyl polymer having a three-diemsional network structure and an acrylic polymer or a copolymer having a three-dimensional network structure composed of both components. CONSTITUTION:A polymer of a component A mainly composed of a vinyl monomer (e.g., methyl methacrylate or vinyl chloride) is maixed with a polymer of a component B mainly composed of an acrylic acid derivative (e.g., n-butyl acrylate) or nutural rubber, a synthetic rubber, at leastone of said components A and B having a three-dimensional network structure. The desired shape- memory elastomer having a glass transition temp. of 0-50 deg.C is formed from the resulting compsn. or a copolymer having a three-dimensional network structure composed of the monomers of the components A and B. Though said elastomer is a kind of an elastomer, it has a shape-memory effect and electrical conductivity.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention maintains a state in which it is deformed into an arbitrary shape near room temperature (0 to 50°C), and returns to its original shape when the temperature rises above room temperature. The present invention relates to a shape-memory elastomer having the above-mentioned properties, and a shape-memory elastomer having electrical conductivity in addition to the above-mentioned properties.

[Conventional technology]

Elastomers such as rubber and plastics have the property of deforming when external force is applied to them at room temperature, and returning to their original state when the external force is removed. None of the conventional elastomers had shape memory properties, such as being deformed by applying an external force, maintaining the deformed shape even after the external force is removed, and returning to the original shape when the environment changes.

Materials having shape memory properties include only certain metals and shape memory alloys.

In general, the lower the glass transition temperature Tg, the easier it is to relax internal strain during deformation. However, in general rubber, Tg is considerably lower than room temperature; -57°C, and -73°C for natural rubber. Therefore, even if these rubbers are deformed at room temperature, they instantly return to their original shape when the external force is removed.

[Problem that the invention seeks to solve]

Although the present invention is an elastomer made of rubber or plastic material rather than a metal material, it maintains its shape even if it is deformed at room temperature, and has shape memory properties that restore it to its original shape when the temperature rises above room temperature. Alternatively, the present invention aims to provide an elastomer that has conductivity in addition to the above properties.

[Means of problem solving]

The composition of the present invention is a mixture of a polymer of component A containing a vinyl monomer as a main component and a polymer of component B containing an acrylic acid derivative as a main component or natural or synthetic rubber, in which at least one A composition having a three-dimensional network structure or a copolymer having a three-dimensional network structure of an A component monomer and a B component monomer, and having a glass transition temperature Tg of 0 to 50°C. It is characterized by Furthermore, in addition to the above structure, a conductive filler is blended.

In the present invention, a polymer blend of a component A polymer mainly composed of a vinyl monomer and a component B polymer mainly composed of an acrylic acid derivative or natural or synthetic rubber (however, a small amount of (polymer has a three-dimensional network structure) or obtained by copolymerizing component A monomer and component B monomer with a crosslinkable group-containing vinyl monomer, and has a three-dimensional network structure and the glass transition temperature Tg from about 0 to 50°C.
, preferably adjusted to 20 to 40°C.

The main components of component A include vinyl monomers such as methyl methacrylate, vinyl chloride, styrene, and acrylonitrile, and the main components of component B include acrylic esters. In particular, when the main component of component A is methyl methacrylate, the main component of component B is expressed by the general formula, n=Q~8 Preferred are acrylic esters such as ethyl acrylate, 2-ethylhexyl acrylate, and n-butyl acrylate.When the main component of component A is vinyl chloride, butadiene-acrylonitrile is preferred as the component B monomer; When the main component is styrene, butadiene is preferred as the component monomer.The mixing ratio of component A and component B or rubber is A.
The ratio of component/B component or rubber is 9515 to 5/95 (weight ratio), preferably 80/20 to 20/80.

In order to obtain a three-dimensional network structure, generally the main components of component A and component B are copolymerized with a crosslinkable group-containing vinyl monomer by bulk polymerization or emulsion polymerization, and then a crosslinking agent is used.
In some cases, heat crosslinking is performed without a crosslinking agent. In the case of rubber, it is crosslinked using a common rubber vulcanizing agent.

As the crosslinkable group-containing vinyl monomer, (al vinyl monomer having a carboxyl group, (b)
Vinyl monomer with epoxy group, (C) vinyl monomer with reactive halogen group, (d) diene vinyl monomer, tel vinyl monomer with hydroxyl group, m vinyl monomer with amide group Among the vinyl monomers mentioned above, only one is selected and copolymerized.

Examples of the vinyl monomer having a fal carboxyl group include acrylic acid, methacrylic acid, and itaconic acid. In this case, the crosslinking agent is preferably polyepoxides such as ethylene glycol diglycidyl ether and 1,6-hexanesiol diglycidyl ether, and polyols such as 1,4-butanediol and 1,1,1-trimethylolpropane. Alternatively, heat crosslinking may be carried out without using a crosslinking agent.

fb) Examples of the vinyl monomer having an epoxy group include allyl glycidyl ether, glycidyl acrylate, and glycidyl methacrylate.

In this case, suitable crosslinking agents include polyamines such as diethylenetriamine and metaphenylenediamine, polycarboxylic acids such as adipic acid, acid anhydrides such as pyromellitic anhydride and maleic anhydride, polyamides, and sulfonamides.

(C) Examples of the vinyl monomer having a reactive halogen group include 2-chloroethyl vinyl ether and monochlorovinyl acetate. In this case, suitable crosslinking agents include polyamines such as diethylenetriamine and triethylenetetramine, and polycarbamates such as hexamethylenediamine carbamate.

+dl Diene vinyl monomers include, for example, divinylbenzene, piperylene, isoprene, pentadiene, vinylcyclohexene, chloroprene, butadiene,
Examples include methylbutadiene, cyclopentadiene, ethylene glycol diacrylate, propylene glycol diacrylate, ethylene glycol dimethacrylate, and propylene glycol dimethacrylate. In this case, the crosslinking agent includes sulfur, organic peroxides such as benzoyl peroxide, dicumyl peroxide, and 2,5-dimethyl-2,5-di-tert-butyl peroxyhexane;
Preferred are azo compounds such as azobisisobutyronitrile, and vinyl compounds such as divinylbenzene, triallyl cyanurate, and triallyl isocyanurate. Alternatively, heat crosslinking may be carried out without using a crosslinking agent.

(e) Vinyl monomers having hydroxyl groups include, for example, hydroxyalkyl acrylate, hydroxyalkyl methacrylate, hydroxyalkoxy acrylate,
Examples include N-methylol acrylamide. In this case, the crosslinking agent is hexamethylene diisocyanate, 2.
Preferred are polyisocyanates such as 4-tolylene diisocyanate, polycarboxylic acids such as adipic acid, and alkoxymethylmelamines such as methoxymethylmelamine.

(fl Vinyl monomers having an amide group include, for example, acrylamide and methacrylamide.

In this case, the crosslinking agent is preferably aminoformaldehyde, or heat crosslinking may be performed without using a crosslinking agent.

It is desirable to select these crosslinkable group-containing vinyl monomers that have passed through the main components of component A and component B, respectively. For example, when the main component is methyl methacrylate or acrylic acid ester, hydroxyalkyl acrylate, hydroxyalkyl methacrylate, etc. are preferred, and when the main component is vinyl chloride, vinyl chloroacetate, epoxyalkyl methacrylate, etc. are preferred.

In addition, when these main components are styrene or acrylonitrile, it is not necessarily necessary to copolymerize the crosslinkable group-containing vinyl monomer.

These crosslinkable group-containing vinyl monomers are added in an amount of 1 to 10 mol %, preferably 1 to 6 mol %, to 90 to 99 mol % of the main components of component A or B for copolymerization. After that,
A three-dimensional network structure is formed using a crosslinking agent suitable for the copolymerized polyfunctional vinyl monomer. The amount of crosslinking agent is preferably 0.1 to 10% by weight based on the total amount. Depending on the crosslinkable group-containing vinyl monomer, heat crosslinking can be performed without a crosslinking agent.

To produce the shape memory elastomer according to the invention,
A polymer of component A and a polymer of component B or natural or synthetic rubber are blended and then crosslinked to form a three-dimensional network structure in at least one of component A or component B. Preferably, both are crosslinked simultaneously to form a three-dimensional network structure. Alternatively, the A component monomer and the B component monomer may be copolymerized and then crosslinked to form a three-dimensional network structure.

The polymer of component A of the present invention has a glass transition temperature Tg of 0 to 1.
50℃, the polymer of component B has a glass transition temperature Tg of 110
It is preferable that the temperature is 0 to 50°C, and it is further preferable that both have a molecular weight of at least the same.

In this way, the Tg of the shape memory elastomer can be adjusted from about 0 to 50°C by adjusting the combination of the polymer of component A, the polymer of component B, or natural and synthetic rubber, the composition ratio, and the degree of development of the three-dimensional network structure. , preferably adjusted to 20 to 40°C.

Furthermore, when a conductive filler is added to these compositions, conductive shape memory elastomers can be obtained. As the conductive filler, conductive carbon black such as Ketjen blank, acetylene black, and HAF carbon, and metal powder such as iron powder, nickel powder, and copper powder are used in composition 100.
By adding 5 to 50 parts by weight, preferably 10 to 40 parts by weight, the volume resistivity increases from 102 to 10'
It will be about Ωcm. Alternatively, a conductive film may be formed on the surface of the elastomer using a metal or a conductive filler by a method such as sputtering or ion blasting.

Furthermore, various compounding agents such as fillers, reinforcing agents, and vulcanizing agents commonly used in the rubber industry can be appropriately added to the shape-memory elastomer of the present invention.

[Effect]

Since the elastomer according to the present invention has a three-dimensional network structure formed inside the molecule and is gelled, it can be freely deformed at room temperature without fluid deformation. Moreover, T
g is around room temperature, which is about 100°C higher than that of ordinary rubber, so it takes a long time to restore its shape after being deformed, and the deformed state can be maintained for a long time. When exposed to heat or exposed to hot water, it returns to its original shape within a few seconds.

Furthermore, electrically conductive materials are given thermal energy by being energized and return to their original shape within a few seconds.

〔effect〕

According to the present invention, it can be easily processed into any shape at room temperature, and the shape can be maintained for a long time. Moreover,
A shape-memory elastomer that can restore its original shape by applying thermal energy, such as by soaking it in hot water, can be obtained.

In particular, conductive shape-memory elastomers immediately restore their original shape when energized.

Utilizing such properties, the shape memory elastomer of the present invention can be used as a joining material for pipes of different diameters, an internal laminate material for pipes, a laminate material for rod-shaped objects, automobile bumpers, gap materials for residential partitions, stationery, It is widely used in educational materials, decorative equipment, crafts such as bottles, and construction fixing materials.

[Example 1] and [Comparative Example 1.2] 80 parts by weight of a copolymer (A component polymer) consisting of 96% bivinyl chloride and 4 mol% vinyl chloroacetate, 80 mol% butadiene, and 20 mol% acrylonitrile. butadiene-acrylonitrile copolymer (B component polymer)
20 parts by weight and 4 parts by weight of diethylenetriamine were mixed, kneaded with hot rolls, and rolled at 150°c x 30'' to a thickness of 2 mm.
A sheet with a size of 50 x 10 mm was prepared and used as Example 1. The Tg of this elastomer was 38°C.

Separately, 100 parts by weight of the above component A polymer and 4 parts by weight of diethylenetriamine were blended, and a sheet was prepared in the same manner as in Example 1 to prepare Comparative Example 1. In addition, the Tg of this elastomer
The temperature was 74°C. Further, 2 parts by weight of dicumyl peroxide was blended with 10 parts by weight of the above B component polymer, and Example 1
A sheet was prepared in the same manner as Comparative Example 2. Note that the Tg of this elastomer was -50°C.

When each of the above sheets was bent and deformed by approximately 90 degrees at 25° C., this shape was maintained for a long time at room temperature and no change was observed. Place this deformed molded product in boiling water at 70°C.
When M was removed, the actual can of Example 1 immediately returned to its original shape. The sample in Comparative Example 1 did not recover to its original shape even when immersed in hot water at 70°C, and cracks appeared on the surface.

Furthermore, even when the material of Comparative Example 2 was deformed at 25° C., it returned to its original shape as soon as the external force was removed, and could not be deformed.

[Example 2] and [Comparative Example 3.4] 60 parts by weight of a copolymer consisting of 98 mol% methyl methacrylate and 2 mol% 2-hydroxyethyl acrylate as the A component polymer, and acrylic acid as the B component polymer. 40 M parts of a copolymer consisting of 96 mol% of ethyl and 4 mol% of 2-hydroxyethyl acrylate;
Knead 4 parts by weight of lylene diisocyanate and mix at 160°C
A sheet was prepared in the same manner as in Example 1 except that the sheet was molded at 30°, and when a deformation test was conducted, the same results as in Example 1 were obtained. The Tg of this elastomer is 35°C.
Met.

Separately, 100 parts by weight of the copolymer of component A of Example 2 and 2.
Comparative Example 3 was prepared by kneading and molding 4 parts by weight of 4-tolylene diisocyanate, and copolymer 1 of component B of Example 2 was prepared.
00 parts by weight and 4 parts by weight of 2.4-)lylene diisocyanate were kneaded and molded to form Comparative Example 4, and the same tests as in Example 1 were conducted.

Comparative Example 3 obtained the same results as Comparative Example 1, and Comparative Example 4 obtained the same results as Comparative Example 2. The Tg of the elastomer of Comparative Example 3 was 90°C, and the Tg of the elastomer of Comparative Example 4 was -24°C.

[Example 3] and [Comparative Example 5.6] Blends having the composition shown in Table 1 were kneaded with a hot roll, and
A sheet was prepared at 30'°C.

When the obtained sheet was subjected to the same deformation test as Example 1, Example 3 obtained the same results as Example 1, Comparative Example 5 obtained the same results as Comparative Example 1, and Comparative Example 6 obtained the same results as Comparative Example 1. The same results as in Table 1 were obtained in Table 1. The units are parts by weight.

[Example 4] and [Comparative Example 7.8] Blends having the compositions shown in Table 2 were kneaded with a hot roll, and 150
A sheet similar to that in Example 1 was produced at 30°C.

Table 2 [Example 5] and [Comparative Example 9.10] The compositions shown in Table 3 were kneaded with a heated roll,
A sheet similar to that in Example 1 was prepared at 30'°C.

Table 3 [Example 6] and [Comparative Example 1). 12] A sheet similar to that in Example 1 was prepared by kneading the compositions shown in Table 4 using a heated roll at 150° C. x 30°.

Table 4 When the obtained compound molded products were subjected to deformation such as bending, twisting, tension, compression, etc. at 25°C and 90°C, the molded products were energized. It recovered to its original shape within minutes. Comparative Example 7.9.1) did not recover its shape even when energized and had cracks on its surface. Furthermore, even when Comparative Example 8.1O1)2(7)Mo(7) was deformed at 25°C, it immediately returned to its original state and could not be deformed.

Patent applicant N.OK Co., Ltd. Agent Patent attorney Toshio Yoshida (1 other person) January 2, 1985 Commissioner of the Japan Patent Office Michibe Uga 1, Indication of the case 1988 Patent Application No. 14767 2, Invention Name: Shape-memory elastomer 3, relationship with the amended person case Patent applicant address: 1-12-15 Shibadaimon, Minato-ku, Tokyo Name: Nisoka Co., Ltd. 4, agent ■150 Address: 29 Shoto-chome, Shibuya-ku, Tokyo No. 21 No. 5, Date of amendment order Voluntary action 6, Subject of amendment Fraction of claims in the specification and detailed description of the invention (1) The claims are corrected as shown in the attached sheet.

(2) In the specification, page 6, lines 9 to 10, "A component and 8 components...or rubber" is replaced by [A component polymer and B component polymer]
The mixing ratio of the component polymer or rubber is A component polymer/B
The component polymer or rubber is corrected to -1.

(3) Ibid., page 9, line 3, between “etc.” and “bi”, “
Insert “multifunctionality”.

(4) Same, page 1), line 2, replace “A component or B component” with “
"A component polymer or B component polymer" is corrected.

(5) Same, page 12, line 5, ``sputter'' is corrected to ``sputtering''.

Amended Claims (1) A mixture of a polymer of component A containing a vinyl monomer as a main component and a polymer of component B containing an acrylic acid derivative as a main component or natural or synthetic rubber, A composition in which at least one side has a three-dimensional network structure or a copolymer having a three-dimensional network structure of an A component monomer and a B component monomer, the glass transition temperature Tg being 0 to 50°C. A shape memory elastomer.

(2) The shape memory elastomer according to claim 1, wherein the mixing ratio of the component A polymer and the component B polymer or natural or synthetic rubber is 9515 to 5/95.

(3) The glass transition temperature Tg of the polymer of component A is 0 to 15
The shape memory elastomer according to claim 1 or 2, wherein the glass transition temperature Tg of the component B polymer or natural or synthetic rubber is 1100°C to 50°C.

(4) A mixture of a polymer of component A containing a vinyl monomer as a main component and a polymer of component B containing an acrylic acid derivative as a main component or a natural or synthetic rubber, at least one of which has a three-dimensional fiber structure. A composition having a structure or a copolymer having a three-dimensional network structure of an A component monomer and a B component monomer, and having a glass transition temperature Tg of 0 to 50°C! A shape memory elastomer made by filling a copolymer with a conductive filler.

(5) The shape memory elastomer according to claim 4, wherein the mixing ratio of the component A polymer and the component B polymer or natural or synthetic rubber is 9515 to 5/95.

(6) The glass transition temperature Tg of the polymer of component A is 0 to 15
The shape memory elastomer according to claim 4 or 5, wherein the glass transition temperature Tg of the polymer of component B or natural or synthetic rubber is -100'C to 50°C.

(7) 5 to 5 per 100 parts by weight of composition or copolymer
The shape memory elastomer according to claim 4, which is filled with 0 parts by weight of a conductive filler.

Claims (7)

[Claims] (1) A mixture of a component A polymer mainly composed of a vinyl monomer and a component B polymer mainly composed of an acrylic acid derivative or natural or synthetic rubber, at least one of which has a three-dimensional network. A composition having a structure or a copolymer having a three-dimensional network structure of an A component monomer and a B component monomer, the shape memory elastomer having a glass transition temperature Tg of 0 to 50°C. . (2) The shape memory elastomer according to claim 1, wherein the mixing ratio of component A and component B or natural or synthetic rubber is 95/5 to 5/95. (3) The glass transition temperature Tg of the polymer of component A is 0 to 15
The shape memory elastomer according to claim 1 or 2, wherein the glass transition temperature Tg of the polymer of component B or natural or synthetic rubber is -100°C to 50°C. (4) A mixture of a polymer of component A containing a vinyl monomer as a main component and a polymer of component B containing an acrylic acid derivative as a main component or natural or synthetic rubber, at least one of which has a three-dimensional network. A composition having a structure or a copolymer having a three-dimensional network structure of an A component monomer and a B component monomer, the composition having a glass transition temperature Tg of 0 to 50°C. A shape memory elastomer filled with a filler. (5) The shape memory elastomer according to claim 4, wherein the mixing ratio of component A and component B or natural or synthetic rubber is 95/5 to 5/95. (6) The glass transition temperature Tg of the polymer of component A is 0 to 15
The shape memory elastomer according to claim 4 or 5, wherein the glass transition temperature Tg of the polymer of component B or natural or synthetic rubber is -100°C to 50°C. (7) The shape memory elastomer according to claim 4, which is filled with 5 to 50 parts by weight of a conductive filler per 100 parts by weight of the composition.