JPH0129231B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an adhesive composition for PVC steel plates, and more specifically, for use in PVC film lamination or
The present invention relates to an adhesive composition that aims to reduce the processing temperature conditions during baking of an undercoat adhesive for vinyl chloride sol coating. Conventionally used methods for manufacturing PVC steel sheets include applying an adhesive to the steel plate and baking it, then laminating a PVC sheet, or applying an adhesive and baking it, then applying a PVC sol paint and baking it. Alternatively, after applying the adhesive and baking it, there is a method in which the vinyl chloride resin is extruded in a sheet form and pressure-fused. In order to fully demonstrate this, high-temperature treatment at 220°C or higher is usually required. However, such high-temperature processing not only has the disadvantage of impairing the appearance of the product and causing discoloration of the laminate.
Even from an energy perspective, the loss is large. As a result of repeated research aimed at developing adhesives for PVC steel sheets, especially adhesives that exhibit good adhesion under low-temperature processing conditions, the inventors have developed a combination of methacrylate ester polymers and vinyl chloride polymers. The present invention was completed based on the discovery that a composition containing the above-described materials satisfies the above objects. The present invention relates to (A) general formula (In the formula, R ₁ is an alkyl group having 8 or less carbon atoms or a group having 8 or less carbon atoms having a substituent containing three or more elements among carbon, hydrogen, nitrogen, and oxygen.) One type of methacrylic acid ester represented by Or a weight average molecular weight obtained by polymerizing a monomer that contains two or more types and can contain 20% by weight or less of a vinyl monomer that can be copolymerized with these if necessary.
100 parts by weight of at least one methacrylic acid ester polymer of 30,000 or more, and (B) 50 parts by weight of polyvinyl chloride and/or vinyl chloride.
Vinyl chloride polymer 1 consisting of at least one vinyl chloride copolymer containing at least % by weight
This adhesive composition for PVC steel plates has good low-temperature adhesion and is composed of 50 parts by weight. By interposing the adhesive composition of the present invention between a vinyl chloride sheet and a steel plate, thermocompression bonding can be performed at a relatively low temperature of about 180°C. The methacrylic ester used in the methacrylic ester polymer, which is component (A) of the present invention, is preferably mainly composed of a methacrylic acid alkyl ester, from the viewpoint of compatibility of each component and toughness as an adhesive. Particularly preferred are methyl methacrylate and ethyl methacrylate, which have a small number of carbon atoms. In order to improve the adhesiveness to steel sheets, it is preferable to add methacrylic acid esters having functional groups as substituents, such as glycidyl methacrylate, allyl methacrylate, dimethylaminoethyl methacrylate,
Examples include hydroxyethyl methacrylate, but esters other than these may be selected depending on the treatment state of the steel sheet surface, the temperature conditions during adhesion, etc., or one or more esters may be mixed and used. Next, as the vinyl monomer that can be copolymerized with the above-mentioned methacrylic acid ester, monomers that are preferable for adjusting the Tg and polarity (compatibility parameter) of the adhesive polymer are used for the purpose of improving adhesiveness. Examples of monomers include methacrylic acid, itaconic acid, acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, vinyl acetate, vinyl chloride, vinylidene chloride,
Examples include maleic anhydride and vinyl isocyanate. The content of these is preferably 20% by weight or less of the methacrylic ester polymer, and if it exceeds 20% by weight, it is not preferable because the advantages of the methacrylic ester polymer such as compatibility and toughness are impaired. Polymerization can also be carried out by emulsion polymerization, suspension polymerization, bulk polymerization, etc.; however, in these cases, it is necessary to dissolve the polymer in a solvent after obtaining it. A polymer obtained by polymerization is used. The weight average molecular weight of the polymer is
It is preferably 30,000 or more, and if it is less than 30,000, the weather resistance and boiling water resistance decrease due to an increase in low molecular weight content, which is not preferable. The vinyl chloride resin used in the present invention is polyvinyl chloride and/or a vinyl chloride copolymer containing 50% by weight or more of vinyl chloride, and is used by dissolving a powdered resin produced by a normal industrial method in a solvent. . The vinyl chloride polymer that is component (B) of the present invention is polyvinyl chloride and/or vinyl chloride copolymer, and examples of vinyl chloride copolymer include 50% by weight or more of vinyl chloride, vinyl acetate, and methacrylic acid. Examples include copolymers with methyl, vinyl bromide, vinylidene chloride, maleic anhydride, etc.;
A copolymer with vinyl acetate from Tg etc. is preferable,
Furthermore, polyvinyl chloride and vinyl chloride copolymer can be mixed in any proportion. The degree of polymerization of these polyvinyl chloride and/or vinyl chloride copolymers is not particularly selected, but in order to improve physical properties such as boiling water resistance, a higher degree of polymerization is preferable, and it is also important to use the polyvinyl chloride and/or vinyl chloride copolymers during use and during adhesive production. From the viewpoint of viscosity, etc., a lower degree of polymerization is preferable. and
A polymerization degree range of 200 to 1500 is a preferred range when used industrially as an adhesive. The vinyl chloride polymer is 1 to 50 parts by weight per 100 parts by weight of the specific methacrylic acid ester polymer,
Preferably 1 to 25 parts by weight are added. If the amount of vinyl chloride resin blended is less than 1 part by weight, the adhesive effect to vinyl chloride resin at low temperatures cannot be exhibited.
If it exceeds 50 parts by weight, it becomes difficult to balance the adhesion of the methacrylic acid ester polymer to the steel plate. In the present invention, in addition to the methacrylic acid ester polymer and the vinyl chloride resin polymer, epoxy resins, phenolic resins, curing agents, plasticizers, fillers, pigments, and the like can be added as necessary. The above blended resin and additives are mixed together with a suitable organic solvent to form a liquid adhesive, and the solvent and mixing method may be any commonly used method. Parts and % in the following examples represent parts by weight and % by weight, respectively. Example 1 Methyl methacrylate 90 parts Glycidyl methacrylate 5 Acrylonitrile 5 AIBN (azobisisobutyronitrile) 0.5 Xylene 100 Butanol 100 The above mixture was placed in 10 flasks and reacted at 80°C for 3 hours in a nitrogen atmosphere. Next, add 1.0 part of AIBN and react at 90°C for an additional 3 hours. The obtained light yellow resin solution was heated to a polymerization degree of 450 and a vinyl acetate content of 13%.
solution of vinyl chloride copolymer (solvent: toluene/
Mix with 100 parts by weight of MIBK=1/1, solid content 10%). Next, MEK/ethyl cellosolve = 100 parts/100 parts is added as a thinner for dilution, and 5 parts of Epikote 828 (epoxy resin manufactured by Ciel Chemical Co., Ltd.) are added and mixed uniformly to obtain an adhesive solution. Adhesion was evaluated using a degreased zinc phosphate treated steel plate and a soft PVC sheet (100μ thick) as adherends. The results are shown in Table 1. Examples 2 and 3 and Comparative Example 1 Adhesive solutions were obtained in the same manner as in Example 1, except that the composition of the methacrylic acid ester polymer was changed as shown in Table 1, and the adhesive properties were evaluated in the same manner. Example 4 and Comparative Examples 2 to 5 When component (B) is not used, or when polyvinyl chloride or polyvinyl acetate is used as component (B) in the parts listed in Table 2 for 100 parts of the methacrylic acid ester polymer, An adhesive solution was obtained in the same manner as in Example 1 and evaluated in the same manner. The results are shown in Table 2.

【table】

【table】

[Table] 1 Test method (1) Erichsen test Cut the sheet into a rectangular shape at 5 mm intervals, then push it out 8 mm using an Erichsen testing machine. Visually evaluate the appearance and check if there is no peeling.
Those with slight peeling are represented by △, and those with clear peeling are represented by ×. The peeling length is measured by peeling from the top of the protruding sample using an Erichsen tester. The peeling length was measured in all four directions of the square shape, and the average value was expressed in mm. (2) Boiling water test In the same manner as above, the sample protruded using the Erichsen tester was immersed in boiling water for 2 hours, and then the appearance and peeling length were evaluated in the same manner as above. 2. Sheet lamination method: Apply adhesive to the steel plate to a thickness of 5μ.
Heat to 180℃, attach a PVC sheet using a roller, and cool with water.

Claims (1)

[Claims] 1 (A) General formula (In the formula, R ₁ is an alkyl group having 8 or less carbon atoms or a group having 8 or less carbon atoms having a substituent containing three or more elements among carbon, hydrogen, nitrogen, and oxygen.) One type of methacrylic acid ester represented by Or a weight average molecular weight obtained by polymerizing a monomer that contains two or more types and can contain 20% by weight or less of a vinyl monomer that can be copolymerized with these if necessary.
100 parts by weight of at least one methacrylic acid ester polymer of 30,000 or more, and (B) 50 parts by weight of polyvinyl chloride and/or vinyl chloride.
Vinyl chloride polymer 1 consisting of at least one vinyl chloride copolymer containing at least % by weight
An adhesive composition for PVC steel plates having good low-temperature adhesion and comprising 50 parts by weight. 2. The composition according to claim 1, wherein component (B) is a vinyl chloride copolymer having a degree of polymerization of 200 to 1,500. 3. The composition according to claim 1, wherein component (B) is a vinyl chloride-vinyl acetate copolymer. 4. The composition according to claim 1, wherein component (A) contains 50% by weight or more of a methyl methacrylate component.