JPH0439422B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a heat-recoverable article that can reliably coat and seal objects made of various metals, plastics, or a combination thereof. [Background of the Invention] Connections and terminal parts of power cables, communication cables, copper pipes, copper pipes, etc. are required to have properties such as insulation, water resistance, and sealing properties. Heat recoverable articles such as coated heat recoverable sleeves and terminal caps are widely used. However, the hot-melt adhesives currently used in heat recovery products can be applied to various materials used for the above-mentioned connections and terminals, such as metals such as iron, copper, lead, aluminum, and stainless steel, as well as polyethylene, polypropylene, and polyethylene. It has been difficult to completely adhere to synthetic resins such as vinyl chloride and polyester. Some types adhered to polyethylene and metals, but did not adhere to polyvinyl chloride or polyester at all. On the contrary, it adhered to polyvinyl chloride and polyester, but did not adhere at all to polyethylene and polypropylene. For bonding polyolefin resins such as polyethylene and polypropylene to metals such as copper, iron, and aluminum, use ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, ionomer resin, ethylene glycidyl methacrylate copolymer, ethylene glycidyl methacrylate-vinyl acetate ternary copolymer, ethylene Ethylene acrylic acid-acrylic ester ternary copolymers obtained by hydrolyzing or thermally decomposing acrylic ester copolymers are known. However, these adhesives had insufficient adhesion to lead-sheathed cables, polyvinyl chloride-sheathed cables, and the like. Furthermore, although these ethylene adhesives have excellent low-temperature impact resistance, they have low high-temperature shear adhesive strength and high-temperature peel strength, resulting in displacement of connections and gas leaks during actual use. On the other hand, polyamide resins, saturated polyester resins, and the like are known for adhering polyvinyl chloride or polyester resins to metals such as copper, lead, and aluminum. However, these did not adhere to polyethylene sheathed cables and also had very poor low temperature impact resistance. For this reason, if the cable was bent or subjected to impact at low temperatures, the adhesive would crack or peel, making it impractical. However, in reality, various combinations of materials are used for the connections and terminals of power cables and communication cables, and many types of plastics and rubbers, such as polyolefin resin and polyvinyl chloride resin, are used for the materials of heat-recoverable products. Therefore, as mentioned above, the adherends that can be bonded are limited.
This is extremely inconvenient. In addition, the usage environment of recent electric wires and cables, copper pipes,
Copper pipes, etc. are used in a wide range of temperatures, from extremely low temperatures (about -40℃) to high temperatures (about 80℃), and heat-recoverable products coated with heat-melting adhesives that can withstand these temperatures are now required. However, I was still not satisfied with anything. In order to solve these problems, a hot-melt adhesive made by blending the above-mentioned ethylene adhesive and the latter polyamide adhesive is disclosed in JP-A-56-122880. This adhesive is a universal adhesive that exhibits adhesion to a variety of adherends, but in order to exhibit its versatility, it was necessary to mix a specific ethylene resin and a specific polyamide resin. The ethylene resin is preferably an ethylene vinyl acetate copolymer with a hydrolysis rate of 50 to 90% by weight, preferably graft polymerized with 0.1 to 5.0% by weight of an unsaturated carboxylic acid, and the polyamide resin has an amine value of 0.5 to 30. Polyamide resins were preferred. However, such hot-melt adhesives have
It was discovered that because it has -OH, -COOH, and _-NH2 groups, when heated for a long time, these two react, raising the adhesive's softening point and increasing its viscosity, resulting in insufficient adhesive strength. . For this reason, it was found that when used at high temperatures, reactions occur gradually and change over time, and storage stability is poor even at low temperatures. Furthermore, it has been found that when metal and plastic are used under water after being bonded together, the adhesive strength at the interface gradually decreases, corrosion of the metal progresses, and interfacial delamination occurs. [Summary of the Invention] The present invention does not deteriorate universal adhesive properties, does not change over time at high temperatures, has excellent storage stability,
Furthermore, the present invention provides a heat-recoverable article coated with a hot-melt adhesive having excellent adhesive strength in water. The adhesive according to the present invention is a mixture of a specific ethylene copolymer and a specific polyamide resin in a predetermined ratio,
Moreover, it is a hot-melt adhesive that has been obtained for the first time by adding a reaction inhibitor that prevents the reaction between acid and amine, and maintains excellent low-temperature impact resistance and high-temperature adhesion. In detail, hydrolysis rate 50-90% by weight
Ethylene vinyl acetate copolymer and amine value 3~
It is a hot-melt adhesive made by mixing 30 polyamide resins in a weight ratio ranging from 90:10 to 60:40, and adding and mixing primary or secondary aliphatic or aromatic amines. . [Detailed Description of the Invention] Various hydrolysates of ethylene vinyl acetate copolymers can be obtained depending on the vinyl acetate content, melt index, and hydrolysis rate, but preferably those with a vinyl acetate content of 45 It is preferable that the hydrolysis rate is 50 to 90% by weight or less. This is because if the vinyl acetate content is 45% by weight or more, the adhesion to polyolefin is poor, and the heat stability and cold resistance are poor. Further, if the thermal decomposition rate is less than 45% by weight, the melting point is low and the mechanical strength at high temperatures is low.If the hydrolysis rate is 95% by weight or more, the low-temperature impact resistance is poor and the melt viscosity is high. More preferably, the adhesion to metals is further improved by hydrolyzing the ethylene vinyl acetate copolymer and then grafting 0.1 to 5.0% by weight of unsaturated carboxylic acid. Hydrolysis rate 50
~90% by weight ethylene vinyl acetate copolymer is, for example, Dumilan D manufactured by Takeda Pharmaceutical Company Limited.
-291, D-229, D-159, D-251, G-222,
G-252, G-422, C-2191, C-2271, C-
1591, C-1570, C-1580, C-1550, C-2280
Toyo Soda Co., Ltd. Product name Mersen H-6410, H-
6810, H-6820, H-6822, H-6960, etc. can be used. Furthermore, polyamide resins with an amine value of 0.5 to 30 are polymers made by reacting dibasic acids called dimer acids with diamines, such as unsaturated fatty acids such as tall oil fatty acids and soybean oil fatty acids, adipic acid, azelaic acid, and sebacic acid. etc., and further reacted with ethylenediamine, hexamethylenediamine, isophoronediamine, xylylenediamine, 4-4'-diaminodicyclohexylmethane, P-P'-methylenedianiline, piperazine, trimethylhexamethylenediamine, alkanolamine, etc. It is made of polyamide resin. The obtained polyamide resin preferably has a number average molecular weight in the range of about 1,500 to 20,000 and a ring and ball softening point in the range of about 80°C to 200°C. In particular, in the present invention, the amine value is 0.5 to 30.
If the amine value is less than 0.5, it will have poor reactivity and poor adhesion to metals, and if the amine value is more than 35, it will be highly reactive and susceptible to thermal deterioration, and it will be less compatible with ethylene-vinyl acetate copolymers. This is because it may lead to a decrease in adhesive strength. Examples of primary or secondary aliphatic or aromatic amines in the present invention include diethylenetriamine, triethylenetetramine, diethylaminopropylamine, diamine diphenyl sulfone,
Examples include N-nitrosodiphenylamine, N-nitrosophenyl β-naphthylamine, and sulfonamide derivatives. Adding 0.1 to 5.0 parts by weight of these amines prevents the reaction between the acid groups in the EVA resin and the amide groups in the polyamide, prevents increases in softening point and viscosity, and stabilizes the adhesive strength in water for a long time. Guarantee sex. If the amount of amines added is less than 0.1 parts by weight, the effect will not be sufficient, while if it is more than 5.0 parts by weight, this is not preferable because it will cause low temperature embrittlement of the hot melt adhesive and a decrease in adhesive strength. Examples of the polyamide resin of the present invention having an amine value of 0.5 to 30 include Barsalon 1128, manufactured by Henkel Japan Co., Ltd.;
1300, 1138, 1139, 1140, 1164, 1165, 1175, etc., product name Dormide 394, 509, manufactured by Fuji Chemical Industry Co., Ltd.
1310, 535, 1350, 512, 656, 500, 575, 1360,
etc. can be used. Furthermore, the hot-melt adhesive used in the present invention contains rubber components such as styrene-butadiene block copolymer and styrene-isoprene block copolymer as one of the few low-temperature modifiers, natural rubber and butyl rubber, and terpene as a thickening agent. It is also possible to add resins, terpene phenol resins, phenolic resins, alkyl phenol resins, etc., colorants, fillers, anti-aging agents, etc. In the heat-recoverable article of the present invention, the heat-recoverable rubber or plastic layer is in the form of a sleeve, cap, tape, etc. It is obtained by crosslinking it by irradiating it with electron beams or adding a chemical crosslinking agent, then expanding or stretching it in a heated state, and then cooling it as it is, and it does not need to be heated during use. It has the property of recovering to its original shape. As a specific example of a heat-recoverable article, a polyolefin resin such as polyethylene, ethylene vinyl acetate copolymer, ethylene ethyl copolymer, etc. is used as an insulating material for the outer layer, and a heat-melting adhesive material for the inner layer is used according to the present invention. Using the adhesive obtained in , extrusion processing is performed as follows. Using two extrusion molding machines, the tube is made with a diameter of 2 to 200 mm and a wall thickness of 1 to 10 mm, with hot melt adhesive on the inside and polyolefin resin on the outside (however, the inside and outside thickness ratio is 3:7 to 7: After extrusion into a tube shape (position 3 is best), only the outer layer material is crosslinked with electron beams or gamma rays. As a method for crosslinking only the outer layer, a commonly used method such as adding a crosslinking promoter to the outer layer and a crosslinking inhibitor to the inner layer may be used. The obtained double tube is heated to 100 to 200°C while applying internal pressure inside the tube to expand the inner diameter to 2 to 5 times, and then cooled to obtain a heat-recoverable article. Alternatively, a double tube may be obtained by separately extruding the outer layer and the inner layer and then aligning them after thermal expansion. When the thus obtained heat-recoverable article having a two-layer structure is heated to 120 to 250°C, the inner layer material is thermally melted and firmly adheres to the adherend. The article obtained by the present invention can be inserted in advance into the connecting part or terminal part of a power cable or a communication cable, and can be used as a cable connector, a copper conductor or a polyethylene sheath.
The tube is covered with a PVC sheath, neoprene rubber sheath, etc. so as to overlap, and heated from the outside of the tube with an electric heater or propane gas burner.
The article can be heat-shrinked and the inner layer of hot-melt adhesive can be used to bond the various materials together, making it waterproof and insulating. The heat-shrinkable coating method described above is simpler and requires less skill than the conventional insulating tape wrapping method, and provides highly reliable waterproofing and insulation properties, offering great advantages. The following will explain based on examples. Example 1 Dumilan D-215 (hydrolysis rate ≒ 80%) and Barsalon No. 1140 (amine value ≒ 8) were used as heat-melting adhesives to be applied to the inner surface of a heat-recoverable article, and amines were also used. Melt-mix triethylenetetramine at polymerization ratios of 90:10:0.5, 70:30:1.0, and 50:50:3.0 (roll kneading at 150°C for 15 minutes),
Further press molding was performed at 150°C to obtain adhesive sheets of 2.0 mm and 0.5 mm thickness. The obtained adhesive sheet was used as a sample for the next performance test. Performance Test 1 A 2.0 mm thick adhesive sheet was subjected to a low temperature embrittlement test according to JIS K-6760 to determine the low temperature embrittlement temperature. Performance test 2 2.0mm thick adhesive sheet at 150℃ for 1 hour and 3 hours.
After heating for 5 and 10 hours, a ring and ball softening point test was conducted according to JIS K-2531 to determine the softening point of the adhesive. Performance test 3 2.0mm thick adhesive sheet at 150℃ for 1 hour and 3 hours.
After heating for 5 and 10 hours, a melt index test was conducted according to JIS K-6760 to determine the adhesive properties.
The viscosity at 190°C was determined. Performance test 4 0.5mm thick adhesive sheet at 80℃ for 5 days, 10 days, 20 days
After storage for 30 days, it was pasted on the inner surface of a heat-recoverable sleeve made of cross-linked polyethylene (inner diameter 60mm, wall thickness 2.0mm), and then placed on top of a cable sheath (made of vinyl chloride sheath, lead sheath) with an outer diameter of 45mm. After cooling, a notch with a width of 10 mm was made in the heat-recoverable sleeve to determine the peel strength with each sheath. The results of those performance tests are shown in Table 1. Example 2 Dumilan D-2270 (hydrolysis rate ≒ 70%,
Unsaturated carboxylic acid content 1.5%) and Bar Salon No.
1300 (amine value ≒ 10) and N-nitrosodiphenylamine as the amine, the polymerization ratios were 90:10:0.5, 70:30:1.0, and 50:50:
Melt mixing at a ratio of 3.0 (roll kneading for 15 minutes at 150°C)
After that, press molding at 150℃ or less, 2.0
Adhesive sheets with mm thickness and 0.5 mm thickness were obtained. The obtained adhesive sheet was subjected to the same performance test as in Example 1 to evaluate its performance. The results are shown in Table 2. Example 3 Dumilan D-1550 (hydrolysis rate ≒ 55%,
Unsaturated carboxylic acid content 2.0%) and Bar Salon No.
1358 (amine value ≒ 6) and metaphenylenediamine as an amine were melt-mixed (at 150°C) at weight ratios of 90:10:0.5, 70:30:1.0, and 50:50:3.0, respectively. Roll kneading for 15 minutes) and press forming at 150℃ to a thickness of 2.0 mm.
An adhesive sheet with a thickness of 0.5 mm was obtained. The obtained adhesive sheet was subjected to the same performance test as in Example 1 to evaluate its performance. The results are shown in Table 3. Comparative Example 1 As a conventional heat-melting adhesive for heat-recoverable articles,
Using the EVA and polyamide resins used in Example 1, melt mixing (roll kneading at 150°C for 15 minutes) was carried out at the same ratio without adding a reaction inhibitor, and then
Press molding was performed at 150°C to obtain adhesive sheets with a thickness of 2.0 mm and 0.5 mm. The obtained adhesive sheet is Example 1
Performance tests similar to those were conducted to evaluate performance.
The results are shown in Table 4. Comparative Example 2 As a conventional heat-melting adhesive for heat-recoverable articles,
Using the EVA resin and polyamide resin used in Example 2, melt mixing (roll kneading at 150 ° C. for 15 minutes) was performed at the same ratio without adding a reaction inhibitor.
Furthermore, it is press-formed at 150℃ or less, and has a thickness of 2.0 mm and 0.5 mm.
An adhesive sheet with a thickness of mm was obtained. The obtained adhesive sheet was subjected to the same performance test as in Example 1 to evaluate its performance. The results are shown in Table 5.

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〔Effect of the invention〕

From the above results, we found that ethylene vinyl acetate copolymer with a hydrolysis rate of 50 to 90% by weight and an amine value of 3 to 90% by weight
A hot-melt adhesive made by mixing 30 polyamide resins at a polymerization ratio ranging from 90:10 to 60:40, and further adding 0.1 to 5.0 parts by weight of primary or secondary aliphatic or aromatic amines. has excellent low-temperature embrittlement properties and excellent adhesive force stability when held at high temperatures, and can universally adhere to various adherends. The adhesive article is one that can reliably coat and seal objects made of various materials.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an example of a heat-recoverable article, in which 1 shows a heat-recoverable tube made of a crosslinked polyolefin resin, and 2 shows a hot-melt adhesive.

Claims (1)

[Claims] 1. A mixture of an ethylene vinyl acetate copolymer with a hydrolysis rate of 50 to 90% by weight and a polyamide resin with an amine value of 0.5 to 30 in a necessary portion of at least one side of a heat-recoverable rubber or plastic layer. Furthermore, 0.1 to 5.0 parts by weight of primary or secondary aliphatic or aromatic amines are added to 100 parts by weight of the total amount of the ethylene vinyl acetate copolymer and polyamide in a weight ratio of 90:10 to 60:40. 1. A heat-recoverable article comprising a layer of a heat-melting adhesive mixed in parts by weight. 2. The heat-recoverable article according to claim 1, wherein the ethylene vinyl acetate copolymer is graft-polymerized with 0.1 to 5.0% by weight of an unsaturated carboxylic acid.