JPH0242396B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field 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. BACKGROUND OF THE INVENTION The use of hot melt adhesives to bond metals and plastic compositions is well known. 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 contrary, 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-vinyl acetate have been used to bond polyolefin resins such as polyethylene and polypropylene to metals such as copper, iron, and aluminum. Known are 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 connecting 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 connected 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 (approximately -40℃) to high temperatures (approximately 80℃), and there has been a need for hot-melt adhesives that can withstand this temperature, but there is still no satisfactory product. Ta. In order to solve these problems, a hot-melt adhesive made by blending the above-mentioned ethylene adhesive and the latter polyamide-based adhesive is disclosed in JP-A-56-122880. This adhesive is a versatile adhesive that exhibits adhesion to a variety of adherends, but in order to demonstrate 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...
It was discovered that because it has OH groups, -COOH groups, 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, it gradually reacts and changes over time, and also has poor storage stability even at low temperatures. [Summary of the Invention] The present invention provides a hot-melt adhesive that does not deteriorate its universal adhesive properties, does not change over time at high temperatures, and has excellent storage stability. The present invention was obtained for the first time by mixing a specific ethylene copolymer and a specific polyamide resin in a predetermined ratio, and adding a reaction inhibitor that prevents the reaction between acid and amine. A hot-melt adhesive that maintains impact resistance and high-temperature adhesive properties.
The gist is that ethylene vinyl acetate copolymer with a hydrolysis rate of 50 to 90% by weight and an amine value of 3
-30 polyamide resins are mixed in a weight ratio ranging from 90:10 to 60:40, and further mixed with primary or secondary aliphatic or aromatic amines. It's in the mold adhesive. [Specific Description of the Invention] Various types of hydrolyzate of the above-mentioned ethylene vinyl acetate copolymer can be obtained depending on the vinyl acetate content, melt index, and hydrolysis rate. It is preferable that the amount is 45% by weight or less and the hydrolysis rate is 50 to 90% by weight. The reason is that the vinyl acetate content is 45% by weight.
This is because the adhesiveness with the polyolefin is poor and the heat stability and cold resistance are poor. In addition, the thermal decomposition rate
This is because if the hydrolysis 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, 0.1 to 5.0% by weight of unsaturated carboxylic acid is added after hydrolyzing ethylene vinyl acetate copolymer.
Graft polymerization further improves adhesion to metals. Examples of ethylene-vinyl acetate copolymers with a hydrolysis rate of 50 to 90% by weight include Dumilan D-291, D-229, D-159, and D- manufactured by Takeda Pharmaceutical Company Limited.
251, D-222, D-252, D-422, C-2191, C
-2271, C-1591, C-1570, C-1580, C-
1550, C-2280, etc., 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 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, hexamethylene diamine, isophorone diamine, xylene diamine, 4-4'-diamino, dicyclohexylmethane, P-P'-methylene dianiline, piperazine, trimethylhexamethylene diamine, 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
An amine value of 0.5 to 30 is preferable; if the amine value is less than 0.5, the reactivity is poor and the adhesion with metals is poor; if the amine value is 35 or more, the reactivity is strong and it is susceptible to thermal deterioration; This is because the compatibility of the two is poor, leading to 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, 1301, 1302, 1138, 1139, 1140, 1164,
1165, 1175, etc., product name Tomide 394, 509, 1310, 535, 1350, 512, 565, manufactured by Fuji Kasei Kogyo Co., Ltd.
500, 575, 1360, etc. can be used. The primary or secondary aliphatic or aromatic amines of the present invention include diethylenetriamine,
Triethylenetetramine, diethylaminopropylamine, heterocyclic diamine, metaxylene diamine, metaphenylene diamine, diaminodiphenylsulfone, N-nitrosodiphelamine, N-
These amines include nitrosophenyl β-naphthylamine, sulfonamide derivatives, etc.
Adding 0.1 to 5.0 parts by weight prevents the reaction between the acid groups in the EVA resin and the amide groups in the polyamide resin, prevents increases in softening point and viscosity, and ensures long-term stability of adhesive strength. If the additive amount is less than 0.1 part by weight, the effect will not be sufficient, while if it is more than 5.0 parts by weight, the hot-melt adhesive will become embrittled at low temperature and the adhesive strength will decrease, which is not preferable. Furthermore, the hot-melt adhesive of the present invention contains a small amount of thickening agent such as tempel resin, terpene phenol resin, phenol resin, alkyl phenol resin, etc. and a styrene-butadiene block copolymer styrene as a low-temperature modifier. It is also possible to add rubber components such as isoprene styrene block copolymer, natural rubber, butyl rubber, colorants, fillers, anti-aging agents, etc. [Example] The following will explain based on an example. Example 1 Ethylene vinyl acetate copolymer (hereinafter referred to as EVA)
Dumilan D-215 (hydrolysis rate ≒ 80%) was used as a polyamide resin (hereinafter abbreviated as PAm), and Barsalon No. 1140 (amine value ≒ 80%) was used as a polyamide resin (hereinafter abbreviated as PAm).
8), and triethylenetetramine as an amine at 90:10:0.5 and 70:30:
A hot-melt adhesive was obtained by melt-mixing (roll kneading at 150°C for 15 minutes) at a weight ratio of 1.0, 50:50:3.0. This was then press-molded at 150°C to produce adhesive sheets of 2.0 mm and 0.5 mm thickness, which were used as samples for the next performance test. Performance test 1 A 2.0 mm thick adhesive sheet was subjected to a low temperature embrittlement test using JISK-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, the softening point of the adhesive was determined by conducting a ring and ball softening point test according to JISK-2531. Performance test 3 2.0mm adhesive sheet at 150℃ for 1 hour, 3 hours, 5
The adhesive was heated for 10 hours and then subjected to a melt index test using JISK-6760.
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, sandwich the sheet between a 2.0 mm thick cross-linked polyethylene sheet (abbreviated as PE in Table 1) and a steel plate, a polyvinyl chloride sheet (PVC), and a copper plate (Cu) at 150℃ for 10 minutes. After press bonding and cooling, a 180°C peel test was conducted according to JISK-6854. The results of those performance tests are shown in Table 1. Example 2 Dumilan C-2270 as EVA (hydrolysis rate≒
70%, unsaturated carboxylic acid content 0.5%), PAm
Using Bar Salon No. 1300 (amine value ≒ 10) as
Furthermore, as amines, N-nitrosodiphenylamine was added at 90:10:0.5, 70:30:1.0, respectively.
Melt mix at a weight ratio of 50:50:3.0 (roll kneading at 150℃ for 15 minutes) to make a hot melt adhesive, and then
Adhesive sheets with a thickness of 2.0 mm and 0.5 mm were obtained by press molding at 150°C. 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 C-1550 as EVA (hydrolysis rate ≒
55%, unsaturated carboxylic acid content 0.5%), PAm
Using Bar Salon No. 1358 (amine value ≒ 6) as
Furthermore, as amines, metaphenylenediamine was added at 90:10:0.5, 70:30:1.0, and 50:50:
Melt-mix at a weight ratio of 3.0 (roll kneading at 150℃ for 15 minutes), then press-form at 150℃ to a thickness of 2.0mm.
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 The conventional hot-melt adhesive used was the EVA and polyamide resin used in Example 1,
These were melt-mixed at the same ratio (roll kneading at 150°C for 15 minutes) without adding a reaction inhibitor, and were further 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 adhesive used was the EVA and polyamide resin used in Example 2,
These were melt-mixed (roll kneaded at 150°C for 15 minutes) at the same ratio without adding a reaction inhibitor, 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.

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〔Effect of the invention〕

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 0.5 to 90%.
Hot-melt adhesives using polyamide resin No. 30 and primary or secondary aliphatic or aromatic amines have low low-temperature embrittlement temperatures and have excellent adhesive strength to various adherends. Among them, the hydrolysis rate is 50-90%.
The ethylene vinyl acetate copolymer and amine value of
0.5-30 polyamide resin 90:10 to 60:40
Mix in weight proportions in the range of , and then add amines
The adhesive formulation added in a proportion of 0.1 to 5.0 parts by weight has excellent thermal stability of the adhesive, and excellent change over time and storage stability. On the other hand, as can be seen from the results in Tables 4 and 5, with the conventional mixture of ethylene vinyl acetate copolymer and polyamide resin, the adhesive lacks thermal stability and has poor storage stability. It was found that the adhesive strength rapidly decreased to various adherends, making it 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
Mix in a weight ratio of 60:40, and further add primary or secondary aliphatic or aromatic amines from 0.1 to
The hot-melt adhesive to which 5.0 parts by weight has been added has excellent low-temperature embrittlement properties and excellent adhesive strength stability when held at high temperatures, and can universally adhere to various adherends. This proves the significance of

Claims (1)

[Claims] 1. Consists of 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 weight ratio in the range of 90:10 to 60:40. 0.1 to 100 parts by weight of the mixture contains primary or secondary aliphatic or aromatic amines.
A hot-melt adhesive characterized by containing 5.0 parts by weight. 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.