JPS62191B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to an improved bonding method capable of strongly bonding plastics to each other, metals to each other, or plastics to metals. Plastics have a wide range of excellent physical properties, are easy to produce on a large scale, and are inexpensive, so they are in great demand. However, the major disadvantage of using this material is that it generally has poor adhesion to plastics and metals, including itself. In order to improve this drawback, various bonding methods have been discovered as shown below. One method is to use a polyurethane or polyester adhesive to bond the plastic to another object. However, the adhesive bodies obtained by these two methods have low peel strength, and also cannot be said to have sufficient heat resistance (peel strength in a heated atmosphere). Furthermore, a method of bonding with a thermosetting epoxy resin is also known, but the epoxy resin has poor flexibility, and the bonded body obtained by this method is weak in bending and easily cracks. Additionally, if it is immersed in hot water, it will be hydrolyzed, resulting in a decrease in adhesive strength. An object of the present invention is to provide an advantageous bonding method that eliminates the above-mentioned drawbacks. According to the method of the present invention, an adhesive having high peel strength, good heat resistance, flexibility, and good hot water resistance can be obtained. is obtained. That is, the method of the present invention uses a composition in which polyolefin and a compound having two or more reactive double or triple bonds in one molecule are uniformly mixed between plastics, between metals, or between plastics and metals. The adhesive is heated and bonded under conditions that allow adhesion to occur. However, the plastics mentioned here refer to the following: That is, 1 cellulose acetate, cellulose acetate butyrate, nitrocellulose, polymethylstyrene, polycarbonate, polystyrene,
Polyvinyl chloride, polymethyl methacrylate, ethyl cellulose, 2 epoxy resin, polyester resin, phenol resin, urea resin, diallyl phthalate resin,
Melamine resin, polyamide resin, polyurethane resin, 3. Polyolefin (low density and high density polyethylene, polypropylene,) chlorinated polyether, polyacetal, 4. Trifluoroethylene resin, polytetrafluoroethylene, etc. Further, metals include, for example, iron, copper, aluminum, tin, zinc, alloys thereof, or metals plated with these. Although it is sufficient if the metal surface is clean, it is advantageous to perform plasting or chemical conversion treatment before adhering, as this will give better results. Now, the adhesive method of the present invention is characterized by using a composition made by homogeneously mixing polyolefin and a specific reactive compound. Density polyethylene, high density polyethylene, polypropylene, polybutene
1. Ethylene-propylene copolymer, ethylene-
Vinyl acetate copolymer, etc. Further, the specific reactive compound is a compound having two or more reactive double bonds or triple bonds in one molecule, and the following examples are specific examples thereof. 1 triallyl ester of cyanuric acid or isocyanuric acid such as triallyl cyanurate and triallyl isocyanurate, 2 triallyl trimellitate, triallyl trimesic acid, triallyl pyromellitate, triallyl benzophenonetetracarboxylate polyallyl ester of carboxylic acid such as ester, 3 trimethylolpropane triacrylate,
1,2,3 propanetriol acrylate,
1,3,5 triacryloyloxybenzene,
There are compounds having two or more acryloyloxy groups or methacryloyloxy groups such as ethylene glycol dimethacrylate and trimethylolpropane trimethacrylate, tripropargyl trimesate, etc., and these may be used alone or in combination of two or more. Therefore, the blending ratio of this polyolefin and the specific reactive compound is in the range of 0.1 to less than 20 parts by weight (particularly preferred blending amount is 1 to 10 parts by weight) per 100 parts by weight of the polyolefin. mix within. In addition, the blending ratio of the above-mentioned specific reactive compound is 0.1 part by weight to 100 parts by weight of polyolefin.
The reason for limiting the amount to less than 20 parts by weight is that if the proportion of the specific reactive compound is less than 100 parts by weight of polyolefin, no substantial effect of improving adhesive strength can be obtained, and if more than 20 parts by weight is blended, the adhesive strength will be adversely affected. This is because it leads to a decrease in Although it is not clear why the adhesive strength is improved when the above-mentioned polyolefin composition is used in the adhesive method of the present invention, it is presumed that this is due to crosslinking occurring in the polyolefin. That is, the reactive compound is graft-polymerized onto the polyolefin by heat, thereby crosslinking the polyolefins together. Since this graft polymer is a graft material, it has good adhesion to metals and polyester, and furthermore, crosslinking reduces the crystallinity of the polyolefin, improving its physical properties as an adhesive, resulting in a significant improvement in adhesive strength. think of it as something that Methods for blending the reactive compound into the polyolefin include mechanical kneading with a mixer, etc., methods of diffusing the reactive compound into the polyolefin using a solvent, mixing with a hot roll, Banbury mixer, etc. Conventional formulation methods in polymer processing are used. Furthermore, additives such as a radical polymerization inhibitor, an antioxidant, a flame retardant, etc. may be added to the mixture of the polyolefin and the reactive compound thus obtained. In addition, it is more preferable to add an antioxidant in order to improve the anti-aging properties and adhesive strength of the composition, and examples of the antioxidant include the following. That is, pentaerythrityl-tetrakis [3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 1,3,5
-trimethyl-2,4,6-tris-(3,5-
di-t-butyl-4-hydroxybenzyl)-benzene, 1,1,3-tris-(5-t-butyl-4
-hydroxy-2-methylphenyl)-butane,
1,3,5-tris-(3,5-di-t-butyl-
4-hydroxybenzyl)-isocyanurate,
4,4'butylidenebis-(6-t-butyl-3-methylphenol, 2,6-di-t-butyl-p-cresol, 4,4'thiobis-(6'-t-butyl-3-methylphenol)
-methylphenol), 2,2'-methylenebis-
(6-t-butyl-4-methylphenol) Next, in the bonding method of the present invention, the polyolefin composition as described above is interposed between the objects to be bonded, and the polyolefin composition is heated and bonded. As a method for interposing the adhesive composition, (a) the above-mentioned powdered adhesive composition is interposed. (b) The above-mentioned polyolefin composition may be formed into a sheet or film in advance, and this may be interposed between adherends, that is, between plastics and metals, or between plastics and metals. It is not specific. In addition, the conditions for heat bonding in the method of the present invention vary depending on the polyolefin used, but the heating temperature is in the range from the melting point of the polyolefin used in the adhesive composition to 90°C above the melting point. The time is preferably about 1 minute to 30 minutes. Next, the present invention will be further specifically explained with reference to Examples. The test method for the peel adhesion strength of the adhesive is as follows:
Measured according to JIS K-6854-1973. Example 1 2.0 parts of trimethylolpropane triacrylate was added to 100 Phr of isotactic polypropylene powder (MI1.0), and acetone was further added and mixed in a V-type blender. This composition was press-molded to form a 0.1 mm thick It was made into a sheet. The obtained sheet was then placed on an aluminum plate (2 mm thick) and a polyethylene terephthalate film (0.3 mm thick).
This was then hot pressed using a press molding machine to bond them together. The pressing conditions were a temperature of 200°C, a time of 15 minutes, and a load of about 5 kg. For comparison, a polyester adhesive, triethylene glycol-modified polyethylene terephthalate, was used in place of the above-mentioned adhesive sheet, and the pieces were adhered in the same manner. The adhesive strength of the thus obtained adhesive body was measured. The results obtained are shown in Table 1.

[Table] Example 2 Isotactic polypropylene (MI0.7)
, trimethylolpropane trimethacrylate
5.0 parts and 0.1 part of pentaerythrityl-tetrakis [3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] as an antioxidant were added, and after roll kneading, press molding was carried out.
A 0.1mm film was produced. This film was sandwiched between polyethylene terephthalate films having a thickness of 0.2 mm, and pressed into a single piece using a press. Pressing conditions are 190℃
The test was carried out for 20 minutes at a temperature of . The T peel strength of this product was 6.53 kg/cm. For comparison, isotactic polypropylene (MI 0.7) was press-molded into a 0.1 mm thick film, and a 0.2 mm thick polyethylene terephthalate film was adhered thereto using the same method as the former. The T peel strength of this product was 0.60 kg/cm.

Claims (1)

[Claims] 1. When bonding plastics, metals, or plastics and metals, a polyolefin is used between the two, and 0.1 of a compound having two or more reactive double or triple bonds in one molecule per 100 parts by weight of the polyolefin. 1. A bonding method comprising: mixing parts by weight to less than 20 parts by weight, interposing a mixture in which the mixture is uniformly mixed, and heating the mixture.