JPS629274B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a hot-melt adhesive composition that has been improved to have strong adhesion to both metals and plastics. It is well known to use hot melt adhesives to bond metals and plastic compositions. It is widely known that hot-melt adhesives can be applied to, for example, heat-shrinkable sleeves, terminal caps, etc., for connection and terminal sections of power cables, communication cables, copper pipes, steel pipes, and the like. However, currently used hot-melt adhesives are made of 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, polyvinyl chloride, polyester, etc. It was difficult to completely adhere to synthetic resin. Some types adhered to polyethylene and metals, but did not adhere to polyvinyl chloride or polyester at all. On the other hand, it adhered to polyvinyl chloride and polyester, but did not adhere at all to polyethylene and polypropylene. Conventionally, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ionomer resin, ethylene-glycidyl methacrylate copolymer, ethylene-glycidyl methacrylate-acetic acid have been used to bond polyolefin resins such as polyethylene and polypropylene to metals such as copper, iron, and aluminum. Known are vinyl ternary copolymers and ethylene acrylic acid-acrylic ester ternary copolymers obtained by hydrolyzing or thermally decomposing ethylene acrylic ester copolymers. 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 properties. 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, the connection parts and terminal parts of power cables and communication cables are made of a combination of various materials, so it is extremely inconvenient that the adherends that can be bonded are limited as described above. In addition, the usage environment of recent electric wires and cables, copper pipes,
The environment in which steel pipes and other products are used has expanded over a wide range of temperatures, from extremely low temperatures (about -40℃) to high temperatures (about 80℃), and there has been a need for heat-melting adhesives that can withstand such temperatures. Nakatsuta. In order to solve these problems, a method of mixing the above-mentioned ethylene-based adhesive and the latter polyamide-based adhesive was considered, but the two have poor compatibility, and simply mixing the two components is not a versatile method. I couldn't get any adhesive. The present invention provides a hot-melt adhesive that universally adheres to various metals and plastics and has excellent low-temperature impact resistance and high-temperature adhesive strength. The present invention achieves the following by mixing a specific ethylene copolymer and a specific polyamide resin in a predetermined ratio.
This is the first hot-melt adhesive to be developed that maintains excellent low-temperature impact resistance and high-temperature adhesion. Its gist is that it is made by mixing ethylene-vinyl acetate copolymer with a hydrolysis rate of 50-90% by weight and polyamide resin with an amine value of 3-30 in a weight ratio ranging from 90:10 to 60:40. It is a hot-melt adhesive. Various types of hydrolyzate of the above ethylene vinyl acetate copolymer can be obtained depending on the vinyl acetate content, melt index, and hydrolysis rate, but preferably the vinyl acetate content is 45% by weight.
It is preferable that the hydrolysis rate is below 50 to 90% by weight. The reason for this is that when 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 90% 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. Examples of ethylene-vinyl acetate copolymers with a hydrolysis rate of 50 to 90% by weight include Duramine D-291, D-229, D-159, and D- manufactured by Takeda Pharmaceutical Co., Ltd.
251, G-222, G-252, G-422, C-2191, C
-2271, C-1591, C-1570, C-1580, C-
1550, C-2280, etc. can be used. Furthermore, polyamide resins with an amine value of 3 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, soybean oil fatty acids, adipic acid, azelaic acid, and sebatin. Add acids, etc., and further add ethylenediamine, hexamethylenediamine, isophoronediamine, xylylenediamine, 4-4'-diamino, dicyclohexylmethane, P-P'-methylenedianiline, piperazine, trimethylhexamethylenediamine, alkanolamine, etc. Examples include reacted polyamide resins. 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 3.
-30 is preferable; if the amine value is less than 2.5, the reactivity will be poor and the adhesion to metals will be poor; if the amine value is more than 35, the reactivity will be strong and susceptible to thermal deterioration; This is because the compatibility is poor, leading to a decrease in adhesive strength. Examples of the polyamide resin of the present invention having an amine value of 3 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, 565, 500, 575, 1360,
etc. can be used. Further, to the hot-melt adhesive of the present invention, terpene resin, terpene phenol resin, phenol resin, alkyl phenol resin, etc., coloring agent, filler, anti-aging agent, etc. may be added as a small amount of thickening agent. is also possible. The following will be explained based on examples. Example 1 Ethylene vinyl acetate copolymer (hereinafter referred to as EVA)
Dumilan D-215 (hydrolysis rate ≒ 80%) was used as a polyamide resin (hereinafter referred to as PAm
Bar Salon No. 1140 (amine value ≒ 8) was used as 95:5, 85:15, 75:
Melt mixing at weight ratios of 25, 65:35, and 50:50 (150℃
(roll kneading for 15 minutes) to obtain a hot-melt adhesive.
Further press molding at 150℃ to 2.0mm thickness and 0.5mm thickness.
This was made into a thick adhesive sheet and 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 A 2.0 mm thick adhesive sheet was subjected to a ring and ball softening point test according to JIS K-2531 to determine the softening point of the adhesive. Performance test 3 A 0.5 mm thick adhesive sheet was combined with a 2.0 mm thick cross-linked polyethylene sheet (abbreviated as PE in Table 1), a polyvinyl chloride sheet (PVC), a copper plate (Cu), a steel plate (Fe), a lead plate ( Pb) and an aluminum plate (Al), press-bonded at 150℃ for 10 minutes, and after cooling.
A 180° peel test was conducted according to JIS K-6854.
As a representative example, adhesion between cross-linked polyethylene and steel plates was tested in -40°C and +80°C atmospheres. The results of those performance tests are shown in Table 1. Example 2 Dumilan C-2270 (hydrolysis rate ≒ 70%, unsaturated carboxylic acid content 0.5%) was used as EVA,
Bar Salon No. 1300 as PAm (amine value ≒ 10)
using 95:5, 85:15, 75:25, respectively.
Melt mixing at a weight ratio of 65:35, 50:50 (15 at 150 °C
The mixture was kneaded in rolls for 1 minute) to obtain a hot-melt adhesive, which was then press-molded at 150°C to obtain adhesive sheets with a thickness of 2.0 mm and a thickness of 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 2. Example 3 Dumilan C-1550 (hydrolysis rate ≒ 55%, unsaturated carboxylic acid content 0.5%) was used as EVA in PAm
Using Bar Salon No. 1358 (amine value ≒ 6) as 95:5, 85:15, 75:25, 65:
35, 50:50 weight ratio (roll kneading at 150℃ for 15 minutes), and then press molding at 150℃.
Adhesive sheets with a thickness of 2.0 mm and a thickness of 0.5 mm 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 3. Comparative Example 1 The conventional hot-melt adhesive used was Evaflex No. 220 (ethylene vinyl acetate copolymer manufactured by Mitsui Polychemical Co., Ltd. with a hydrolysis rate of 0%).
and Bar Salon No. 1165 (amine value ≒ 1.5) 70:
The adhesive sheets were melt-mixed (roll kneaded at 150°C for 15 minutes) at a weight ratio of 30:30 and 30:70, and then press-molded at 150°C to obtain adhesive sheets with a thickness of 2.0 mm and a thickness of 0.5 mm. 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 4. Comparative Example 2 The conventional hot-melt adhesives used were Sumilink DR-55SS (ethylene vinyl acetate copolymer manufactured by Sumitomo Chemical, hydrolysis rate ≒ 100%) and Versalon No. 1140 (amine value ≒ 8). in weight percentage
They were melt-mixed (roll kneaded at 150°C for 15 minutes) at a ratio of 70:30 and 30:70, and were further press-molded at 150°C to obtain adhesive sheets of 2.0 mm and 0.5 mm thickness. 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 4.

【table】

【table】

【table】

[Table] As can be seen from the performance test results in Tables 1, 2, and 3, the ethylene vinyl acetate copolymer of the present invention has a hydrolysis rate of 50 to 90% and an amine value of 3 to 30.
Hot-melt adhesives using polyamide resins have low low-temperature embrittlement temperatures and have excellent adhesive strength to various adherends. Among them, adhesive formulations in which an ethylene vinyl acetate copolymer with a hydrolysis rate of 50 to 90% and a polyamide resin with an amine value of 3 to 30 are mixed in a weight ratio in the range of 90:10 to 60:40 have particularly excellent adhesive properties. There is. Those with a blending ratio of 95:5 have a slightly higher softening point and must be bonded at high temperatures;
The low-temperature embrittlement temperature of No. 50 was found to be -40°C or higher, indicating poor cold resistance. Furthermore, as can be seen from the results in Table 4, conventional mixtures of ethylene vinyl acetate copolymers and polyamide resins have poor low-temperature embrittlement and high softening points, so they do not provide sufficient adhesive strength with various adherends. It turned out to be impractical and impractical. From the above test results, the hydrolysis rate of the present invention is 50~
90% by weight of ethylene vinyl acetate copolymer and polyamide resin with an amine value of 3 to 30 in a ratio of 90:10 to
A hot-melt adhesive mixed in a weight ratio of 60:40 has excellent low-temperature embrittlement and high-temperature adhesive strength, and can universally adhere to various adherends. This proves the significance of the present invention.

Claims (1)

[Scope of Claims] 1. Consisting of a mixture of ethylene vinyl acetate copolymer with a hydrolysis rate of 50 to 90% by weight and polyamide resin with an amine value of 3 to 30 in a weight ratio in the range of 90:10 to 60:40. A hot-melt adhesive featuring: 2. The hot-melt adhesive 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.