JPS5919804B2 - Method for manufacturing heat-recoverable articles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a heat-recoverable article provided with an adhesive resin layer.

Conventionally, heat recovery products have been widely used as insulating and waterproof covers for the connections and terminals of electric wires and cables, and as anti-corrosion and waterproof covers for the connections and terminals of steel pipes, copper pipes, aluminum pipes, etc. It is being

The above-mentioned heat-recoverable article is generally made by providing an adhesive resin layer on the inner surface of a heat-shrinkable tube, for example, and after coating the adherend at the connection part or end part, the article is heated and shrunk to bond the above-mentioned adhesive. By adhering the thermoplastic resin layer and the adherend, the heat-recoverable article serves to prevent moisture and corrosive liquid from entering from the edges. Conventionally, as a method for providing an adhesive resin layer on a heat-recoverable molded article such as a heat-shrinkable tube or sheet, a method has been adopted in which the adhesive resin layer is coated on the inner surface or one side of the heat-recoverable molded article after it has been manufactured. The reason for adopting such a method is that in order to impart heat recovery properties to molded products such as tubes and sheets made of thermoplastic resin or rubber, it is necessary to expose the molded products to radiation (
After irradiation with electron beams, gamma rays, Most of the rubber adhesives, polyolefin adhesives, and polyamide adhesives that have been used are crosslinked or decomposed, resulting in a significant decrease in adhesive ability. Therefore, a method has been adopted in which an adhesive resin layer is provided after irradiation. When manufacturing a heat-recoverable article consisting of a heat-recoverable molded article provided with an adhesive resin layer,
Even if an attempt is made to increase productivity, there are limits to the method of forming a molded product and then applying an adhesive resin layer thereon.
For this reason, when making thermoplastic resin or rubber molded products,
It is considered that productivity can be increased by simultaneously molding an adhesive resin layer.

However, if a conventional adhesive is used as the adhesive resin layer, the adhesive ability will be reduced as described above. In order to solve the above problems, for example,
Publication No. 0-3790, Japanese Patent Publication No. 53-23344,
Special Publication No. 53-24986, Special Publication No. 53-3738
As described in Publication No. 6, a crosslinking inhibitor is added to the adhesive layer to prevent crosslinking even when irradiated with radiation,
Methods have been devised such as blending easily decomposable butyl rubber or adding tackifiers. However, the adhesive resin layer obtained by the above method is Even with various changes, sufficient adhesion to various metals as well as plastics such as polyethylene and vinyl chloride resin could not be obtained, and therefore, reliability for long-term insulation, waterproofing, and anticorrosion was poor.

The reason for this is thought to be that since it was necessary to add a large amount of low-molecular-weight substances such as crosslinking inhibitors and tackifiers, these low-molecular substances bloom at the adhesive interface and cause a peeling phenomenon. In view of the above-mentioned problems, the present invention provides a heat-recoverable article provided with an adhesive resin layer that does not reduce adhesive ability even when irradiated with radiation and can maintain excellent adhesive strength over a long period of time. It was developed to manufacture and provide products at low cost, and its gist is that polyamide resin with an amine value of 3 to 30 is added to the inner surface or one side of molded products such as tubes and sheets made of thermoplastic resin or rubber. Saponification degree 50
After providing an adhesive resin layer consisting of a resin composition containing ~90% by weight of a saponified ethylene copolymer and a crosslinking inhibitor,
A heat recovery article characterized in that the molded article is crosslinked by irradiation with radiation, then the molded article is deformed by expansion, stretching, etc. under heating above its softening point, and then cooled in the deformed state. It is in the manufacturing method. In the present invention, the polyamide resin having an amine value of 3 to 30 is a polymer obtained by reacting a dibasic acid called dimer acid with a diamine, such as unsaturated fatty acids such as tall oil fatty acid and soybean oil fatty acid, adipic acid, Azelaic acid, sebacic acid, etc. are added, and further ethylene diamine, hexamethylene diamine, isophenyl diamine, xylene diamine, 4-4'-diaminodicyclohexylmethane, PP'-methylene dianiline, piperazine, trimethylhexamethylene diamine, alkanolamine. It is a polyamide resin that has been subjected to a similar reaction.

The obtained polyamide resin has a number average molecular weight of about 1500 to 2.
0000 range, with a ring and ball softening point of about 80℃~2
A temperature range of 00°C is preferable.

In particular, in the present invention, those having an amine value of 3 to 30 are preferable; if the amine value is less than 2.5, the reactivity is poor and the adhesion with metals is poor, and if the amine value is 35 or more, the reactivity is strong and it is susceptible to thermal deterioration. This is because the compatibility with the ethylene-vinyl acetate copolymer is poor, leading to a decrease in adhesive strength. The polyamide resin having an amine value of 3 to 30 of the present invention is manufactured by Pengel Japan Co., Ltd. under the trade name Barsalon 1128,13.
00,1138,1139,1140,1164,11
65, 1175 etc. and product name Dormide 394, 509, 1310, 535, 1350, 5 manufactured by Fuji Kasei Kogyo Co., Ltd.
12,565, 500, 575, 1360, etc. can be used.

Furthermore, various types of saponified ethylene copolymers can be obtained depending on the vinyl acetate content, melt index, and degree of saponification, but preferably the vinyl acetate content is 4.
It is preferable that the amount is 5% by weight or less, and the degree of saponification is 50 to 90% by weight. This is because if the vinyl acetate content is 45% by weight or more, the adhesion to polyolefin is poor, and the thermal stability and cold resistance are poor.
In addition, if the thermal decomposition rate is 45% by weight or less, the melting point is low and the mechanical strength at high temperatures is low, and the hydrolysis rate is 95% by weight.
This is because the low-temperature impact properties are poor and the melt viscosity is high. More preferably, after saponifying the ethylene-vinyl acetate copolymer, 0.1 to 5.0% by weight of unsaturated carboxylic acid is graft-polymerized, thereby further improving the adhesion to the metal.
Examples of ethylene-vinyl acetate copolymers having a saponification degree of 50 to 90% by weight include Dumilan D-291, D-229, D-159, and D-251 manufactured by Takeda Pharmaceutical Company Limited.
, G-222, G-252, G-422, C-2191
, C-2271, C-1591, C-1570, C-1
580, C-1550, C-2280, etc. can be used. Furthermore, as a crosslinking inhibitor, 4-4/-thiobis-6-tert-m-cresol, 4-4'-methylene-bis-2-tert-butylphenol, 2.
6-tert-butylphenol, 4-4'-butyldenbis-6-tert-butyl-m-cresol, 2.5-tert-amylhydroquinone, etc. can be used.

The blending ratio of these polyamide resins and saponified ethylene polymers is preferably 30 to 80% by weight: 20 to 70% by weight, and the mixture is uniformly kneaded using a heating roll, heating kneader, or the like. Preferably, the adhesive resin further contains 0.5 to 5% by weight of a crosslinking inhibitor. If the polyamide resin content is less than 30% by weight, the adhesiveness with various metals and vinyl chloride resins will be poor, and if it is 80% by weight or more, the adhesiveness with polyolefin resins will be poor.

On the other hand, if the content of the saponified ethylene copolymer is less than 20% by weight, the adhesiveness with the polyolefin resin will be poor;
However, it has poor adhesion with various metals and vinyl chloride resin. Further, if the crosslinking inhibitor is less than 0.5% by weight, it will be crosslinked by electron beam irradiation, lose fluidity during heat shrinkage, and have poor adhesion to adherends. If it exceeds 5% by weight, the crosslinking inhibitor blooms at the adhesive interface, resulting in a decrease in adhesive strength and poor reliability during use.

In particular, ethylene copolymers have traditionally been very easily crosslinked, but by using saponified ethylene copolymers and mixing them in the proportions of the present invention, no crosslinking occurs even when irradiated with electron beams. I newly discovered that this is not the case. The following will be explained based on examples.

Example 1 A polyamide resin with an amine value of 8 and a saponified ethylene vinyl acetate resin with a degree of saponification of 80% by weight were mixed on the inner surface of a polyethylene resin with 4.4/-thiobis-6-tertiary-m-cresol in a ratio of 140:58:2. ,260:39:1,380:
Adhesive resins were roll-kneaded at a ratio of 19.5:0.5 and double extrusion molded, with an outer diameter of 20 WIφ and a wall thickness of 2.07 m.
A double tube was obtained.

After that, the electron beam was 12 Mrad, 24 Mrad, 36 Mrad, respectively.
Mrad irradiation, heating to 150℃ and outer diameter 40Trrf
The product was expanded to nφ and cooled to obtain a heat-recoverable article. The obtained heat-recoverable article was used as a sample for the following performance test. Performance test 1. The heat-recoverable article was heat-shrinked on an aluminum sheath, a vinyl chloride sheath, and a polyethylene sheath cable with an outer diameter of 30 wmφ, and after cooling, a notch with a width of 10 Tm was made in the heat-recoverable article to determine the peel strength with each sheath.

Performance test 2. Adhesive resin was collected from the inner layer of the heat-recoverable article and JISK
-2531, a ring and ball softening point test was conducted to determine the softening point of the adhesive layer.

The results are shown in Table 1.

Example 2 A polyamide resin with an amine value of 10, a saponification degree of 70% by weight, and an unsaturated carboxylic acid content of 1.
5% by weight saponified ethylene vinyl acetate resin and 4.4/-
Methylene-bis-2-tert-butylphenol 140:59.5:0.5,260:39:1,380
Each of the adhesive resins roll-kneaded at a ratio of :18:2 was double extruded to obtain a double tube with an outer diameter of 20 wmφ and a wall thickness of 2.0 mm.

After that, the electron beam was 12 Mrad, 24 Mrad, 36 Mrad, respectively.
Mrad irradiation, heating to 150℃ and outer diameter 40wtmφ
The product was expanded to a temperature of 100% and cooled to obtain a heat-recoverable article. The obtained heat recovery article was subjected to the same performance test as in Example 1, and the results are shown in Table 1. Example 3 A polyamide resin with an amine value of 6, a saponified ethylene vinyl acetate resin with a degree of saponification of 55% by weight, and 4,4'-thiobis-6-tert-1m-cresol were mixed on the inner surface of a polyethylene resin at a ratio of 140:59.5. 0.5,260:39.5:0
．． 5,380:19.5:0.5 roll-kneaded adhesive resins were double extruded, and the outer diameter was 20Trrf.
A double tube with a diameter of 1φ and a wall thickness of 2.07 m was obtained.

After that, the electron beam was 12 Mrad, 24 Mrad, 36 Mrad, respectively.
Mrad irradiation, heating to 150℃ and outer diameter 40Trmφ
The product was expanded to a temperature of 100% and cooled to obtain a heat-recoverable article. The obtained heat-recoverable article was subjected to the same performance test as in Example 1, and the results are shown in Table 1. Comparative Example 1 A polyamide resin with an amine value of 8, an ethylene vinyl acetate resin with a vinyl acetate content of 20% by weight, and 4,4'-thiobis-6-tertiary-m-cresol were mixed on the inner surface of a polyethylene resin in a ratio of 140:59.5:0. 5,260:39.5:0.
Adhesive resins were roll-kneaded at a ratio of 5,380:19.5:0.5 and double extrusion molded to form an outer diameter of 20w! nφ,
A double tube with a wall thickness of 2.0 wr1n was obtained.

After that, the electron beam was 12 Mrad, 24 Mrad, and 3 Mrad, respectively.
Irradiated with 6 Mrad and heated to 150℃ to make the outer diameter 40wmφ
The product was expanded to a temperature of 100% and cooled to obtain a heat-recoverable article. The obtained heat-recoverable article was subjected to the same performance test as in Example 1, and
The results are shown in Table 2. Comparative Example 2 Polyamide with an amine value of 6, ethylene vinyl acetate resin with a vinyl acetate content of 35% by weight, and 4.
4'-thiobis-6-tertiary-m-cresol 1
40:59.5:0.5, 260:39.5:0.5,
Two types of adhesive resins were roll-kneaded at a ratio of 380:19.5:0.5 and extruded to form a mold with an outer diameter of 20 mφ and a wall thickness of 2.0 m.
A double tube of 0 m was obtained.

Claims (1)

[Scope of Claims] 1. A polyamide resin with an amine value of 3 to 30 and saponified ethylene vinyl acetate with a saponification degree of 50 to 90% by weight on the inner surface or one side of a molded product such as a tube or sheet made of thermoplastic resin or rubber. After providing an adhesive resin layer made of a resin composition containing a copolymer and a crosslinking inhibitor, the molded product is crosslinked by irradiation with radiation, and then the molded product is expanded under heating above its softening point. A method for producing a heat-recoverable article, which comprises deforming it by stretching, etc., and then cooling it in the deformed state. 2 30-80% polyamide resin with amine value 3-30
An adhesive resin layer made of a resin composition containing 20 to 70 weight % of a saponified ethylene vinyl acetate copolymer with a saponification degree of 50 to 90 weight % and a crosslinking inhibitor of 0.5 to 5 weight %. A method for producing a heat-recoverable article according to claim 1, which comprises: