JPS59227437A - Heat-recoverable article - Google Patents

Abstract

PURPOSE:To make it possible to prepare a composition developing no tackiness even if electron beam is irradiated, by adding a polyfunctional monomer to a block copolymer of vinylidene chloride and plypropylene hexafluoride. CONSTITUTION:A block copolymer of vinylidene fluoride and polypropylene hexafluoride is prevented from the development of tackiness when irradiated with electron beam by adding a polyfunctional monomer having two or more of double bond or triple bond functional groups in the molecule thereof to said copolymer. Therefore, this fluorine type elastomer composition can be used in a heat-recoverable article prepared by applying deformation processing to a molded article after the irradiation of electron beam. In addition, a block copolymer consisting a fluorine-containing monomer such as ethylene tetrafluoride other than polypropylene hexafluoride and vinyliden fluoride may be used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a heat-recoverable article having particularly excellent flame retardancy and heat aging resistance.

[Background of the invention]

Heat-recoverable products (molded products such as tubes, caps, tapes, etc.) are widely used to insulate, protect, waterproof, and corrosion-proof exposed parts such as connectors and wiring connections in electrical equipment such as TVs and VTRs. It is also used as a cover for resistors, capacitors, etc.

Conventionally, polyvinyl chloride 1 has been used as a material for heat-recoverable articles.
Fit resins, polyolefins, polyester resins (polyethylene terephthalate), silicone resins, etc. are used. Flame retardants and stabilizers have been added to improve the flame retardancy and heat aging resistance of these materials.

In recent years, the requirements for flame retardancy and heat aging resistance for heat-recoverable products have become more stringent, and in addition to these performances, there have also been demands for improvements in oil resistance and chemical resistance, as well as transparency. Therefore, it has become difficult for the conventional materials mentioned above to satisfy all of these properties. The use of fluororubber has been proposed as a material that meets these demands.

However, with fluororubber alone, it is not possible to make heat-recoverable articles because it does not have so-called heat-setting properties, and a crystalline resin is usually mixed therein to impart heat-setting properties. In this case, a crystalline fluororesin such as polyvinylidene fluoride was mixed so as not to impair the properties of the fluorine rubber (heat resistance, oil resistance, etc.). However, when polyvinylidene fluoride is mixed, the physical properties of the resulting mixture tend to vary;
It was difficult to obtain a uniform product.

A block copolymer of vinylidene fluoride and another fluorine-containing monomer has heat-setting properties like the above mixture, and can produce heat-recoverable articles.

The method for manufacturing heat-recoverable articles is to mold a molded product such as a tube, cap, tape, etc. by an appropriate method such as extrusion, injection, or press, then crosslink the molded product by electron beam irradiation, and then heat it. This is done by applying deformation such as expansion and stretching, and then cooling to maintain the deformation.However, irradiated copolymers have tackiness and are sticky during deformation processes such as expansion and stretching, so they are difficult to use with processing equipment. It was difficult to deform the molded parts because they would stick to each other or the molded parts would stick to each other.

[Summary of the invention]

The present invention is a fluorine-based block copolymer suitable as a heat-recoverable molded product, which has a composition that does not exhibit tackiness even when irradiated with an electron beam, and which can be manufactured because the composition has no tackiness. The present invention provides a heat-recoverable article. The gist of the first invention is that a block copolymer of vinylidene fluoride and a fluorine-containing monomer represented by polypropylene hexafluoride (hereinafter abbreviated as polypropylene hexafluoride, etc.) has two molecules in the molecule.
The second aspect of the invention is a fluorine-based elastomer composition characterized by adding a polyfunctional monomer having two or more double bonds or triple bond functional groups. A fluorine-based elastomer composition made by adding a polyfunctional monomer having two or more double bonds or triple bond functional groups in the molecule to a block copolymer such as polypropylene, which is cross-linked by electron beam irradiation. The heat recovery article is characterized in that it is deformed into a predetermined shape and deformation strain remains.

[Detailed description of the invention]

In the present invention, the block copolymer of vinylidene fluoride and polypropylene 67 fluoride, which is a fluorine-based elastomer, has two or more double bonds or triple bond functional groups in the molecule, unlike other fluorine-based elastomers. By adding a polyfunctional monomer, tackiness does not appear when exposed to electron beam irradiation. Therefore, this fluorine-based elastomer composition can be used for heat recovery articles manufactured by deforming molded products after electron beam irradiation. be able to. In addition to hexafluorinated polypropylene, other fluorine-containing monomers such as 4-fluoroethylene, or block copolymers with vinylidene fluoride may also be used.

Other fluororesins include crystalline resins such as polytetrafluoroethylene and polyvinylidene fluoride, but polytetrafluoroethylene has an expandable temperature close to the decomposition temperature and is difficult to expand, while vinylidene fluoride is hard and has an expandable temperature. The area is small and expansion is difficult. Furthermore, a random copolymer of vinylidene fluoride and propylene hexafluoride, which is a fluorine elastomer, does not set when expanded or cooled, and cannot be used as a heat-shrinkable tube. In addition, blends of resin and elastomer are difficult to mix uniformly, have large variations in mechanical strength, and may or may not expand during expansion, making stable production difficult.

In the present invention, the polyfunctional monomers include triallylcyanurate (TAC), )lylylisocyanurate-1-(
TAIC), ethylene glycol dimecacrylate, 1.3 butylene glycol diacrylate, trimethylolpropane trimethacrylate-1-1l-rimedylolethane trimethacrylate, l-rimedyolpropane triacrylate, ■・rimethylol Triacrylate, tetramedilolmethanetetraacrylate-1
Refers to difunctional or trifunctional monomers such as .

The effects of the present invention are not impaired even if pigments, lubricants, etc. that are added or blended with ordinary rubbers, resins, etc. are added or blended.

〔Example〕

Examples and comparative examples of the present invention will be described below.

As an example, the following fluorine-based elastomer composition was created.

(Parts by weight) Daiel Elastomer T530×100 Polyfunctional Monomer 5 The polyfunctional monomers used are as shown in Table 1. After uniformly mixing each composition using an extruder, the inner diameter is 5111. ffi, a tube with a wall thickness of 1.5mm was extruded and crosslinked by irradiation with an electron beam at the dose shown in Table 1. 11) Heat the resulting tube to 250°C, apply air pressure inside the DUF to expand it to an internal diameter of 14 mm in an expansion die with an internal diameter of 1.6 nm, and cool it in the expanded state to remove heat. A resilient tube was created.

The expansibility of the tube when making the heat-recoverable tube and the heat-shrinkability of the obtained heat-recoverable tube were evaluated. The evaluation method is as follows.

(1) Expandability --- The ease with which the expansion tube in contact with the inner wall surface of the expansion die was pulled out from the expansion die was evaluated.

×: The tackiness, that is, the adhesiveness is large, and the strength of the tube is also reduced, so that the tube breaks when pulled out.

△: Due to high tackiness, the duplex stretches when pulled out, making it difficult to pull out.

Good: The tube has some tackiness, and the tube stretches when pulled out, but the stretch is 30% or less.

◎: There is almost no tackiness, and the elongation due to pulling is 15%.
It is as follows.

(11) Heat shrinkability: The fully shrunk inner diameter was measured when the sample was heat-shrinked using a burner.

As a comparative example, a tube of the same size as in the example was prepared using Daicel elastomer T530 alone, irradiated with an electron beam at the dose shown in Table 2, and expanded in an expansion die in the same manner as in the example. The results of the expansion evaluation are shown in Table 2.

Table 1 Polyfunctional monomers Irradiation dose Expandability Within complete shrinkage
Diameter Example 1 Triallyl cyanuride-1.5 Mracl
◎ 6LnfL〃 2 Triallylisocyanuride-1・ ], OMrad ◎ 5
．． 5m57 3 Ejiren Krikorjimeku
5 Mrad ○ 62 Yekryle-1・22,1, 1.3 Butylene glycol di'7'/') b-1, 5 Mrad ○
5.7111M7751 Rimedirol Propane 1, +) Me, Y Kuril-1, 10 Mrad Q
5.5 mm'/6'・Remedirol Equantrimekkurye-1・1.0 M″″°d
◎ 5.3 rnx2,71・limethylolpropane triacrylate 10 Mrad ◎
5°3 nun.

, 7 8 Trimedilol Ecun 11. ．． Aku, , , -to5 Mrad ◎
5.7 myth Table 2 As is clear from Table 1, the composition in which a polyfunctional monomer is added to the block copolymer of vinylidene fluoride and polypropylene hexafluoride has tackiness (expandability) when irradiated with an electron beam. Therefore, the composition can be used to obtain heat-recoverable articles that are heat-shrinkable by 7 minutes.

On the other hand, as can be seen from Table 2, in the comparative example, tackiness was exhibited by electron beam irradiation, and the strength was also reduced by heating, making it impossible to create a heat-recoverable article.

Claims (3)

[Claims] (1) Adding a polyfunctional monomer having two or more double bonds or triple bond functional groups in the molecule to a block copolymer of vinylidene fluoride and one or more other fluorine-containing monomers 1. A heat-recoverable article, which is a molded article crosslinked by electron beam irradiation and made of a blended composition, which is deformed into a predetermined shape and has residual deformation strain. (2) The heat-recoverable article according to claim (1), wherein the other fluorine-containing monomer is propylene hexafluoride. (3) The polyfunctional upper layer is 1-diallyl isocyanurate-1-1-lylyl cyanurate, trimethylolpropane trimethacrylate, trimedylolequontrimethacrylate, trimethylolpropane) and rearylate, The heat-recoverable article according to claim 1, wherein the monomer is a monomer selected from the group of trimethylolethane triacrylate and tetramethylolmethanetetraacrylate-1.