JPS6329906B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an adhesive composition for laminating a synthetic resin film such as vinyl chloride or acrylic resin to a metal plate. The present invention relates to a urethane-modified acrylic adhesive composition that provides excellent adhesion and processing adhesion at low heat activation temperatures. (Object of the invention) The object is to laminate films of vinyl chloride, acrylic resin, etc. using the low heat-activated adhesive composition of the invention.
It saves energy during the lamination process, improves product appearance, and makes it easier to laminate thin films, and provides synthetic resin film-coated metal plates with good product appearance at a lower cost while maintaining excellent adhesive properties. It's about doing. (Prior art) It is well known that various synthetic resin adhesives are conventionally used when laminating various synthetic resin films such as vinyl chloride onto cold-rolled steel sheets, galvanized steel sheets, etc. . For example, for vinyl chloride coated steel sheets,
No. 52-128979, the main component of which is a vinyl chloride-bi-maleic acid copolymer, and the main component of which is methyl methacrylic resin. For acrylic-coated steel sheets, epoxy is disclosed in Japanese Patent Application Laid-open No. 134686/1986.
There are polyacrylate type and nitrile rubber type shown in JP-A-52-128979. For polypropylene-coated steel sheets, those containing propylene-acrylic acid copolymer and vinyl chloride-vinyl maleic acid copolymer as the main components shown in JP-A-52-130832. Furthermore, for vinylidene fluoride coated steel sheets, a system containing polyester as the main component is disclosed in JP-A-52-74680. Furthermore, for vinyl fluoride coated steel sheets, there is a two-component type commercially available from DuPont of the United States, which has acrylic resin as its main component. And this is what we showed in the aforementioned Special Publication No. 57-28516. Although these have been developed according to their respective purposes and have been evaluated including practical aspects, they are insufficient to realize excellent adhesive properties at a low thermal activation temperature, which is the main objective of the present invention. It is enough.
(References Japan Adhesive Association Journal Vol.19, No.3, p.110
~ (1983)) Note that the low heat activation temperature referred to here refers to the temperature at which the adhesive layer reaches its maximum temperature when both the bonding roll and the laminated synthetic resin film are at room temperature or below in the normal roll lamination method. The temperature is below 180℃. Most adhesives currently in practical use have a thermal activation temperature range of over 200°C. Lamination of films at a relatively high thermal activation temperature as conventionally practiced has the following drawbacks. The first problem is the surface appearance of the product. One of them is the embossed return of the film. This is a phenomenon in which the embossments cut in advance flow due to high temperatures during lamination. As a result, the surface gloss increases and the product image becomes distorted. Furthermore, subtle uneven gloss in the form of diagonal lines, which is thought to be caused by tension during film production, may become visible depending on the type of embossed pattern and the color tone of the film. Secondly, there are some problems in the lamination process. One of these problems is the problem of film breakage that rarely occurs when the film is thin, such as 0.1 mm or less. This is due to the instantaneous high temperature and the film tension during lamination, causing the film to melt and
This is a phenomenon that leads to flowing and cutting. In addition, high-temperature heating reduces the line speed itself, which has a considerable impact on productivity. Furthermore, since the high-temperature heating itself causes a large energy loss, it is not desirable from the viewpoint of cost savings and resource conservation. To solve these problems, several acrylic and polyester adhesives have been proposed as adhesives for low-temperature bonding. However, from a practical standpoint, further improvements are considered necessary due to insufficient process adhesion and short pot life due to mixing of two liquids. (Structure of the Invention) The present invention eliminates such drawbacks and makes vinyl chloride,
Films such as acrylic resin are laminated to metal plates such as cold-rolled steel sheets and galvanized sheets using low-temperature adhesive compositions, making it easy to create products with high workability and durability, as well as excellent appearance. The aim is to provide it at a low price. That is, when laminating a synthetic resin film and a metal plate, 5 to 20 parts by weight of acrylic acid or methacrylic acid, 5 to 45 parts by weight of acrylic ester, 20 to 80 parts by weight of methacrylic ester, and 1 to 15 parts by weight of glycidyl methacrylate. The purpose can be achieved by applying a synthetic resin film coating adhesive consisting of 1 to 30 parts by weight of a polyisocyanate compound having two or more isocyanate groups in the molecule to 100 parts by weight of an acrylic copolymer consisting of . Hereinafter, the adhesive of the present invention will be explained in detail. The acrylic resin adhesive composition in the present invention includes 5 to 20 parts by weight of acrylic acid or methacrylic acid, 5 to 45 parts by weight of an acrylic ester having an alkyl group having 1 to 10 carbon atoms, and 5 to 45 parts by weight of an acrylic ester having an alkyl group having 1 to 10 carbon atoms. It is copolymerized with a monomer composition of 20 to 80 parts by weight of a methacrylic ester having an alkyl group and 1 to 15 parts by weight of glycidyl methacrylate.
120,000, 100 parts by weight of an acrylic copolymer having a glass transition temperature of 90 to 140°C, and 1 to 30 parts by weight of a polyisocyanate compound having two or more isocyanate groups in the molecule, combined with a ketone solvent or an aromatic solvent alone. Alternatively, it is formed by dissolving it in a mixed solvent. In the monomer composition of the acrylic copolymer of the present invention, the introduction of a carboxyl group into the copolymer molecule due to the presence of acrylic acid or methacrylic acid, which is an unsaturated carboxylic acid, improves the adhesion effect to the adherend. In this case, if the amount of acrylic acid or methacrylic acid is less than 5 parts by weight, the adhesive effect will be small, and if it exceeds 20 parts by weight, physical properties such as water resistance will deteriorate. It is preferably used in a range of 5 to 15 parts by weight. Next, the type and amount of acrylic ester and methacrylic ester are important factors contributing to the physical properties of the copolymer. That is, when the number of carbon atoms in the alkyl group exceeds 10, physical properties such as heat resistance deteriorate. If the blending amount of methacrylic acid ester, which is one of the representative hard components of the copolymer, is less than 20 parts by weight, the heat softening property of the adhesive will increase, and if it exceeds 80 parts by weight, the flexibility will deteriorate. parts by weight, preferably
30 to 70 parts by weight are used. The above methacrylic acid ester monomers may be styrene, styrene,
Substitution with acrylamide is also possible. In addition, if the amount of the acrylic acid ester monomer, which is a soft component, exceeds 45 parts by weight, the heat resistance will decrease and
If the amount is less than 1 part by weight, the flexibility will decrease, so the amount is preferably 5 to 45 parts by weight, preferably 10 to 40 parts by weight. Furthermore, if the amount of glycidyl methacrylate is more than 15 parts by weight, physical properties such as adhesion and heat resistance will improve, but flexibility will be poor, and if it is less than 1 part by weight, the degree of crosslinking will be reduced, resulting in poor heat resistance. decreases, so 1
~15 parts by weight, preferably 1 to 10 parts by weight. By blending a polyisocyanate compound that reacts with this acrylic copolymer, it is possible to increase the degree of crosslinking of the adhesive composition in general, and to realize stronger adhesion, especially in a low heat activation temperature range. Can be done. Also, as already mentioned in Special Publication No. 57-28516,
It has also been found that sufficient performance can be achieved even if the resin composition (B) blended for the purpose of imparting flexibility is omitted. The polyisocyanate compound used in the present invention may be any compound having two or more isocyanate groups in one molecule, such as toluylene diisocyanate,
Diisocyanates such as xylylene diisocyanate and 4,4'-diphenylmethane diisocyanate or Desmodyur R, Desmodyur L and Desmodyur N (all trade names,
Examples include triisocyanates such as those manufactured by Bayer, Germany. If the amount of the polyisocyanate compound is less than 1 part by weight, the adhesion to the base metal plate will be insufficient and the effect will be poor from the standpoint of low-temperature adhesion. In addition, if it exceeds 30 parts by weight, not only will water resistance decrease, but there will also be disadvantages such as gelation and shortened pot life.
~30 parts by weight, preferably 5 to 20 parts by weight. In addition to the above main components, the adhesive composition of the present invention includes:
Things that improve the flexibility and adhesion of nitrile rubber, thermoplastic urethane, natural rubber, vinyl chloride-vinyl-maleic acid copolymer, etc. In addition, materials that improve heat resistance and adhesion such as epoxy resins, modified phenolic resins, and polyamide resins, inorganic pigments such as titanium oxide and carbon black, and organic pigments such as phthalocyanine blue and red lake pigments, as well as strontium chromate, calcium chromate, Commonly used inorganic rust-preventive pigments such as chromium compounds such as barium chromate, lead compounds such as basic lead chromate, calcium plumate, etc. may be added. The adhesive composition of the present invention includes toluene, methyl ethyl ketone, methyl cellosolve acetate, ethyl complex acid, n-butyl alcohol and other aliphatic, alicyclic or aromatic hydrocarbons, esters, ketones, ethers, Conventional organic solvents can be used, such as one or a mixture of two or more of alcohols and the like. Examples of the synthetic resin film used in the present invention include thermoplastic films such as vinyl chloride, vinyl fluoride, polyester, polyacrylate, polyethylene, and polypropylene, and synthetic rubber films, but particularly preferred are vinyl chloride films,
It is an acrylic film. Most of these coated films are usually 0.03 to 0.50 mm. On the other hand, the base metal plates include hot-rolled steel sheets, cold-rolled steel sheets, electrogalvanized steel sheets, hot-dipped galvanized steel sheets,
These include electrolytic chromic acid treated steel plates, tin-plated steel plates, stainless steel plates, aluminum plates, etc., and these may be used as they are or after being subjected to a commonly used chemical conversion treatment. In order to obtain a synthetic resin-coated steel sheet using the adhesive composition of the present invention, the adhesive dissolved in an organic solvent is coated on one or both sides of the metal sheet by a commonly used method such as roll coating or curtain flow coating. The thickness of the adhesive after drying is 1 to 50 μm.
After applying it so that the metal plate temperature is 130~270℃
The coated metal plate is dried by heating for about 0.2 to 5 minutes, and then vinyl chloride film, acrylic film, etc. are laminated thereon by the roll lamination method to obtain a coated metal plate. Heating the metal plate at a temperature of 180°C or less is sufficient for adhesive strength that can withstand normal drawing processing. The coated metal plate obtained in this way can easily be provided as a thin film type product with a high quality product appearance while maintaining high workability. Furthermore, in terms of energy saving during the manufacturing process, the contribution rate is extremely large compared to conventional adhesives. The present invention will be explained in more detail with reference to Examples below. Example 1 In a four-necked flask equipped with a stirring bar, a reflux condenser, and a dropping funnel, 20 parts by weight of methyl ethyl ketone,
After adding 60 parts by weight of toluene and replacing the air in the flask with nitrogen, a mixed monomer consisting of 10 parts by weight of methacrylic acid, 45 parts by weight of methyl methacrylate, 20 parts by weight of ethyl acrylate, and 3 parts by weight of glycidyl methacrylate was added. After stirring and mixing, benzoyl peroxide was added dropwise in a hot bath controlled at 80°C, and the mixture was stirred for about 10 hours to obtain an acrylic copolymer with a number average molecular weight of about 20,000. 5 parts by weight of xylylene diisocyanate were added to 100 parts by weight of this acrylic copolymer, and after stirring for 2 hours, an adhesive having a concentration of 30% by weight was prepared using a mixed solvent of methyl ethyl ketone and toluene. The adhesive thus obtained is degreased and
It was coated with a roller coater on one side of a 0.6 mm thick hot-dipped galvanized steel sheet that had been chemically treated (Bonderite #3920, manufactured by Nippon Parkerizing Co., Ltd.) so that the coating amount after drying was 70 mg/dm ² . Next, dry and heat in a gas oven.
After increasing the temperature of the steel plate to 180℃ for 30 seconds,
While maintaining the same temperature, a 0.1 mm thick semi-hard vinyl chloride film was immediately laminated using a roll laminator at a linear pressure of 7 kg/cm, and immediately cooled to obtain a vinyl chloride coated steel sheet. The adhesive strength and process adhesion of this coated steel plate were measured by a 180° peel test and an Erichsen test according to JIS K-6744. In addition, to examine the adhesive durability, the Erichsen test was performed in the same manner as above after immersing it in boiling water for 12 hours. These results are summarized in Table 1 together with the observation results of the film appearance. Example 2 7 parts by weight of Desmodyur N (trade name, product of Bayer AG, Germany) was added to the same amount of acrylic copolymer as shown in Example 1, and an adhesive with a concentration of 30% by weight was prepared in the same manner as in Example 1. was prepared. A vinyl chloride coated steel plate was prepared using this adhesive in the same manner as in Example 1, and the same tests as in Example 1 were conducted to examine the performance. These results are summarized in Table 1. Example 3 An adhesive prepared in the same manner as in Example 1 was applied to a 0.6 mm thick cold-rolled steel sheet that had been subjected to only alkali degreasing, and a vinyl chloride-coated steel sheet was produced under the same conditions as in Example 1. This was subjected to the same test as in Example 1 to examine its performance. These results are summarized in Table 1. Examples 4, 5, 6 An adhesive prepared in the same manner as in Example 2 was applied to a steel plate under the same conditions as in Example 1. Next, the steel plate was dried and heated in a gas oven for 30 seconds to reach a temperature of 170°C (this is referred to as Example 4) and 160°C, respectively.
℃ (this is referred to as Example 5) and 150 ℃ (this is referred to as Example 6), and a vinyl chloride coated steel plate was obtained in the same manner as in Example 1. These were subjected to the same test as in Example 1 to examine their performance. These results are summarized in Table 1. Comparative Example 1 100 parts by weight of methyl methacrylic resin (manufactured by Rohm and Haas, Paraloid A-101), 10 parts by weight of phenol resin (AP-107F, manufactured by Gunei Chemical Co., Ltd.), nitrile rubber (manufactured by Gutsudoritsuchi Chemical Co., Ltd.,
Hiker 1001) 5 parts by weight, vinyl chloride-vinyl-maleic acid copolymer (manufactured by Union Carbide, VMCH)
A vinyl chloride-coated steel plate was prepared in the same manner as in Example 1 using an adhesive prepared by dissolving 3 parts by weight in a mixed solvent of methyl ethyl ketone, toluene, and xylene to a concentration of 30% by weight. Example 1
A similar test was conducted to examine the performance. The results are summarized in Table 1. Comparative Example 2 The same amount of acrylic copolymer as shown in Example 1 was mixed with 3 parts by weight of a phenol resin (Pryauchen 5010, manufactured by Dainippon Ink Co., Ltd.), and a bisphenol A type epoxy resin (manufactured by Ciel Co., Ltd., Epicoat).
1001) 100 parts by weight and imidazole (manufactured by Shikoku Kasei Co., Ltd.,
2 parts by weight of a modified epoxy resin consisting of 5 parts by weight of Kyuazol 2MZ) was added to a mixed solvent of methyl ethyl ketone and toluene, and the mixture was stirred for 8 hours at room temperature using an ordinary all-purpose stirrer to prepare an adhesive having a concentration of 30% by weight. Using this adhesive, a vinyl chloride coated steel plate was prepared in the same manner as in Example 1, and the same tests as in Example 1 were conducted to examine the performance. The results are summarized in Table 1. 【table】

Claims (1)

[Claims] 1 Acrylic copolymer 100 consisting of 5 to 20 parts by weight of acrylic acid or methacrylic acid, 5 to 45 parts by weight of acrylic ester, 20 to 80 parts by weight of methacrylic ester, and 1 to 15 parts by weight of glycidyl methacrylate.
An adhesive composition for coating a synthetic resin film comprising 1 to 30 parts by weight of a polyisocyanate compound having two or more isocyanate groups in the molecule.