JPH0649855B2 - Ethylene / vinyl acetate copolymer type hot melt adhesive composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hot melt adhesive composition which exhibits excellent adhesion to various metals or plastics, and whose adherend has excellent water resistance.

More specifically, it relates to a hot melt adhesive composition obtained by blending an ethylene / vinyl acetate copolymer with a saponified product (or an acid modified product thereof) and a polyamide resin.

Ethylene / vinyl acetate copolymer (hereinafter sometimes abbreviated as EVA) has been conventionally used as a hot melt adhesive.
For example, it has been widely used as an adhesive for paper, cardboard and wood. However, it lacks adhesives for metals and plastics, and is rarely used for metals.

On the other hand, a saponified product of ethylene / vinyl acetate copolymer (hereinafter sometimes abbreviated as HEVA) or an acid-modified product thereof (hereinafter sometimes abbreviated as HEVA-C) is a metal, glass, ceramic, wood, It is known to show good adhesiveness to a wide range of materials such as fibers and plastics, and is used as a hot melt adhesive.

The inventors of the present invention have been able to mix EVA with metals or plastics by simply mixing a small amount of HEVA (or HEVA-C) and a small amount of polyamide resin with EVA which has been conventionally used as a hot melt adhesive. We have found that the adhesive strength improves dramatically. These results indicate that EVA has a small amount of HEVA (or HE
This was a surprising fact not found in the composition in which VA-C) was added or the composition in which a small amount of polyamide resin was added to EVA. Furthermore, among EVA, the vinyl acetate content is relatively high and the melt index is 3
E of the following (MI: g / 10min. ASTM D-1238 Revised)
HEVA (or HEVA-C) to this using VA
It has been found that an adhesive composition having excellent water resistance performance can be obtained for a long period of time while maintaining excellent adhesive strength by blending with a polyamide resin. The present invention has been made based on these findings.

That is, the present invention provides (A) an ethylene / vinyl acetate copolymer having a vinyl acetate content of 15 to 55% by weight of 20 to 75%.
Parts, (B) 10-60 parts of a partially saponified ethylene / vinyl acetate copolymer having a vinyl acetate content of 15-55% by weight or its acid modified product, and (C) a polyamide resin 5-50
A hot melt adhesive composition containing 100 parts by weight of (A), (B) and (C).

The ethylene / vinyl acetate copolymer (A) that can be used in the present invention has a vinyl acetate content of 15 to 55% by weight and a melt index of 0.5 to 450 (preferably 0.5 to 100). belongs to. As such components, various grades are commercially available for raw materials such as hot melt adhesives.
It can be used as (A). In the present invention, among the components (A), particularly by using an ethylene-vinyl acetate copolymer (A ') having a vinyl acetate content of 40 to 45% by weight and a melt index of 0.5 to 3, It is possible to obtain an adhesive composition that exhibits excellent water resistance over an extremely long period of time. Such copolymers are already on the market, and these can be used as they are.

The partially saponified ethylene / vinyl acetate copolymer (B) that can be used in the present invention is the acetic acid ester part of the ethylene / vinyl acetate copolymer (which usually has a melt index of 0.5 to 300). It is a polymer obtained by saponifying about 30 to 99%. Such partially saponified HEVA (B) is already known and can be produced by a conventional method. Particularly preferred for use in the present invention is a vinyl acetate content of 25-45% by weight.
And the degree of saponification is about 50 to 99%. Further, an acid-modified product obtained by further modifying such HEVA with an acid is a component (B) particularly suitable for obtaining a durable adhesive composition, and such an acid-modified product is
It usually has an acid value of 1 to 30 mgKOH / g. This is a modified product which can be produced by grafting a carboxyl group-containing vinyl monomer such as acrylic acid, methacrylic acid or maleic acid onto HEVA, and is a known modified product per se.

The polyamide resin (C) that can be used in the present invention is a condensate obtained by reacting a polycarboxylic acid and a polyamine, and further appropriately an alkanolamine or the like by a conventional method, and has a molecular weight of 2000 to 30,000. .
The resin terminal usually has an amino group, but it may have a carboxyl group. Examples of the polycarboxylic acid include dimer acid, adipic acid, mazelaic acid, and sepatic acid, which are obtained by heat-polymerizing unsaturated fatty acid such as tall oil fatty acid or soybean oil fatty acid. On the other hand, examples of the polyamine include ethylenediamine. , Hexamethylenediamine, 4,4'-diaminodiphenylmethane, trimethylhexamethylenediamine,
Xylene diamine, piperazine, isophorodiamine,
ω, ω'-diaminomethylcyclohexane, 4,4'-
Mention may be made of diaminodicyclohexylmethane. Examples of alkanolamines include ethanolamine and propanolamine. As the polyamide resin used in the present invention, various grades have already been manufactured and sold, but a dimer acid-based polyamide resin is particularly preferable.

Among the hot melt adhesive compositions of the present invention, as a particularly preferred composition, (B) 15 to 50 parts, and (C) 10 to 45 parts are compounded with respect to 30 to 60 parts of the component (A). The compositions that have been mentioned can be mentioned. The adherend using the composition within such a range is excellent in low-temperature adhesion performance and durability performance.

In addition to these three essential components, the composition of the present invention may contain various compounding agents that are usually contained in hot melt adhesives, as long as the effects of the present invention are not impaired. Examples of such a compound include inorganic substances such as talc, calcium silicate, zinc oxide, and titanium oxide, various tackifiers, waxes, antioxidants, antioxidants, and ultraviolet absorbers used for ordinary hot melt adhesives. , A stabilizer, etc. can be mentioned.

The adhesive composition of the present invention, the above components (A), (B), (C), may be mixed in powder form, respectively, usually after melt-blending these components, For example, a composition molded into pellets, tablets, sheets or films is used. The hot melt adhesive molded in this way is applied to various materials using conventional means. That is, the pellets or tablets can be applied to the adherend by a hot melt applicator, roll coater, extruder or the like, and the sheet or film can be laminated on the adherend. The melt blending temperature is about 100 to 120 ° C. when the extruder is used, and various compounding agents are usually blended at the time of melt mixing, but may be blended after melting such as talc, and are appropriately selected.

The hot melt adhesive composition of the present invention comprises a metal (for example, iron, aluminum, copper, lead, zinc, etc.) and a plastic (for example, polyolefin resin such as polyethylene and polypropylene, polyvinyl chloride resin, thermoplastic polyurethane resin, polyacrylate). It has excellent adhesive strength to (such as resin). Therefore, it is useful as an adhesive for polyethylene-coated steel pipes, vinyl chloride-coated steel pipes, polyethylene-coated wires, vinyl chloride-coated wires, and the like. Further, it is particularly suitable as an adhesive between the polyethylene sheet for external corrosion protection and the steel pipe in the joint portion of the polyethylene-coated steel pipe. It can also be used as an adhesive for coating the outer surfaces of power cables and communication cables. In the case of adhering metal and plastics, to component (A) 35 to 55 parts, component (B) 15 to 35 parts and component (C) 15 to 40 parts.
It is preferable to use a partially compounded composition. That is,
The hot-melt adhesive having such a composition not only exhibits excellent adhesive strength, but also has excellent water resistance.

Since the composition of the present invention melts at a relatively low temperature, it has an excellent industrial practical advantage that strict temperature conditions are not required for bonding.

Hereinafter, the present invention will be described more specifically with reference to examples.

Example 1 Dumilan C-2270 formulated in the proportions shown in the table below
(Saponified acid-modified ethylene / vinyl acetate copolymer; manufactured by Takeda Pharmaceutical Co., Ltd.), Macromelt 6240 (dimer acid-based polyamide, manufactured by Henkel Japan Ltd.), Evaflex 260 (ethylene / vinyl acetate copolymer) The coalesced product, manufactured by Mitsui Polychemical Co., Ltd., was melt-blended at 100 ° C. using an extruder and then pelletized. Then, an adhesive sheet having a thickness of 100 μ was prepared using the pellet. The 100 μ adhesive sheet was sandwiched between low-density polyethylene (0.5 mm thick) and iron (# 240 polished), and pressure-bonded at 150 ° C. for 3 minutes to bond polyethylene and iron. When the 180 ° peeling adhesive strength (JIS-K6854) was examined using this sample, the following results were obtained.

(1) Mixing ratio indicates parts by weight (the same applies below) (2) Material break means material breakage (the same applies below) Example 2 Dumiran C-2271 compounded in the ratio shown in the table below
(Saponified acid-modified ethylene / vinyl acetate copolymer, manufactured by Takeda Pharmaceutical Co., Ltd.), Macromelt 6240 (dimer acid polyamide, manufactured by Henkel Japan Ltd.), Evaflex 250 (ethylene vinyl acetate copolymer, Mitsui Polychemical Industry Co., Ltd.) using an extruder at 100 ° C
After melt-blending with, pelletized, and then using this pellet, an adhesive sheet having a thickness of 100 μm was prepared. The above 100 is applied to the treatment of soft polyvinyl chloride sheet and zinc-treated iron plate.
The μ-thickness adhesive sheet was sandwiched and pressed at 150 ° C. for 3 minutes to bond the vinyl chloride sheet and the iron plate. Use this one 1
When the 80 ° peel adhesive strength was examined, the following results were obtained.

Example 3 Dumilan C-1590 blended in the proportions shown in the table below
(Saponified acid-modified ethylene / vinyl acetate copolymer, manufactured by Takeda Pharmaceutical Co., Ltd.), Versalon 1139 (dimer acid polyamide, manufactured by Nippon Henkel Co., Ltd.), Evaflex 250 (ethylene vinyl acetate copolymer, Mitsui Polychemical Industry Co., Ltd. was melt-blended at 100 ° C. using an extruder and then pelletized. Then, an adhesive sheet having a thickness of 100 μ was prepared using the pellets. This was sandwiched between two hard vinyl chloride sheets and pressed at 150 ° C. for 1 minute to bond them. When the 180 ° adhesive strength of this product was examined, the following results were obtained.

Example 4 Evaflex 40LX (ethylene / vinyl acetate copolymer; vinyl acetate content 40% by weight MI 2, manufactured by Mitsui Polychemicals Co., Ltd.), Dumilan C-2271 (acid-modified ethylene / vinyl acetate copolymer saponified product, Takeda Pharmaceutical Co., Ltd.
And Macromelt 6239 (polyamide resin, manufactured by Henkel Japan Ltd.) in the proportions shown in the table below.
Pellets were produced using an extruder at 0 ° C. A 100μ thick adhesive sheet is made from these pellets, and a medium density polyethylene film (100μ thick) is applied to an iron plate (3m
m thickness, # 240, polishing process), 1 at 130 ℃
The polyethylene and iron were bonded together by applying pressure for 5 minutes. This product was tested for 180 ° tensile adhesive strength and water resistant adhesive strength after 6 months, and the following results (No. 1) were obtained.

In the above formulation, the same experiment as above was carried out by using Evaflex 45LX (ethylene vinyl acetate copolymer; vinyl acetate content 45% by weight, MI 2.5, manufactured by Mitsui Polychemical Co., Ltd.) instead of Evaflex 40LX. I did. The results are shown in the table below. 2 shows.

Example 5 Evaflex 250 (ethylene / vinyl acetate copolymer; vinyl acetate content 28% by weight, MI 15, manufactured by Mitsui Polychemical Co., Ltd.) 45 parts by weight, Dumilan D-159 (ethylene / vinyl acetate copolymer Ken) Compound, Takeda Pharmaceutical Co., Ltd.
30 parts by weight of Co., Ltd. and 25 parts by weight of Macromelt 6240 (polyamide of dimer acid type, manufactured by Henkel Japan Ltd.) were melt-blended at 120 ° C. using an extruder and then pelletized. Then use this pellet for 100
A μ-thick adhesive sheet was prepared.

This is a medium density polyethylene film (100μ thick) and iron plate
(3mm thickness, # 240, polishing process) Clamped between 150 ℃
Then, it was pressure-bonded for 15 minutes to bond polyethylene and iron.

When the 180 ° peel adhesion strength of this product was examined, it was 15 kg
The value of / inch was obtained.

Claims (1)

[Claims] 1. An ethylene / vinyl acetate copolymer (A) having a vinyl acetate content of 15 to 55% by weight, and (B) an ethylene / vinyl acetate copolymer having a vinyl acetate content of 15 to 55% by weight. 10 to 60 parts of a partially saponified polymer or its acid-modified product and 5 to 50 parts of (C) polyamide resin are contained so that the total of (A), (B) and (C) is 100 parts by weight. A hot melt adhesive composition comprising: