JPS6251306B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a coating composition that can be cured at room temperature or at low temperature to provide a high-performance coating film with excellent adhesion to a substrate and a good balance of appearance, physical performance, gasoline resistance, chemical resistance, etc. It is something. In recent years, various types of plastics have come to be used as materials for automobile parts and household electrical appliances, and in particular, the use of plastics to reduce the weight of automobile parts has been avoided in order to save energy, and this trend seems to be expanding. It is. Currently, various plastics are used in large quantities, but polyolefin resins and the like are only partially used despite being relatively cheap. This is largely due to the lack of good coating compositions for polyolefin resins, and in particular the property of polyolefins, which makes it difficult for coatings to adhere.Therefore, the development of coating compositions that have good adhesion to polyolefin resins is greatly needed. It is expected. In response to these demands, various coating compositions that adhere to polyolefins are currently being developed. As one of these, studies are underway to utilize the fact that chlorinated polyolefin adheres well to polyolefin as an adhesive aid for polyolefin. however,
Apart from the two-coat method in which a chlorinated polyolefin is used as an undercoat and then another resin is applied as a topcoat, in most cases, one-coat finishes that contain chlorinated polyolefin in the paint are made by combining the chlorinated polyolefin and the paint resin. There is a problem in that the compatibility of chlorinated polyolefin is poor and the appearance of the coating film is poor.If you want to improve the appearance of the coating film, there is a limit to the amount of chlorinated polyolefin that can be used, which causes problems in adhesion.
There are thermoplastic, air-drying products that attempt to satisfy both of these requirements, but these do not have sufficient coating film performance such as gasoline resistance or chemical resistance.
That is, at present, no coating composition has been found that has good adhesion, film appearance, and film performance. As a result of repeated research aimed at solving the above problems, the inventors of the present invention have developed a one-coat finish with good adhesion, excellent appearance, and resistance to gasoline, solvents, water, and chemicals. We have discovered a composition that creates a coating film with excellent performance. That is, the present invention comprises: (1) Basic nitrogen-containing acrylic monomer 0.2 to 30% by weight (2) Ester of acrylic acid or methacrylic acid with aliphatic monohydric alcohol or a mixture thereof 35 to 99.8% by weight (3) Acrylic copolymer obtained by blending monoethylenically unsaturated monomers copolymerizable with component (1) and component (2) so that the total amount is 100% by weight, and () carboxyl Consisting of a chlorinated polyolefin modified with a group-containing monoethylenically unsaturated monomer and a compound or resin having two or more epoxy groups per molecule, ()/() is 98/2 to 30 /70,
()/() is a coating composition consisting of 98/2 to 70/30. Component (1) of the acrylic copolymer (), that is, the basic nitrogen-containing acrylic monomer, is used to react with a compound or resin () having two or more epoxy groups per molecule to cause crosslinking. Dimethylaminoethyl acrylate or methacrylate, diethylaminoethyl acrylate or methacrylate, t-butylaminoethyl acrylate or methacrylate, etc. are preferably used. The amount used is 0.2 to 30% by weight, preferably 2 to 15% by weight. Component (2) of the acrylic copolymer (2) is preferably an ester of acrylic acid or methacrylic acid and a monovalent acyclic or cyclic aliphatic monohydric alcohol, particularly methanol, ethanol, propanol, butanol, etc. Esters, etc., and mixtures thereof are preferred, 35-99.8% by weight of the monomer, preferably 50-99.8% by weight of the monomers.
80% by weight is used. Component (3) of the acrylic copolymer () includes styrene, acrylic acid,
Preferably used are methacrylic acid, 2-hydroxyethyl acrylate or methacrylate, acrylamide, methacrylamide, etc., and other components (1) and (2) such as α-methylstyrene, vinyltoluene, acrylonitrile, vinyl acetate, etc.
Anything that can be copolymerized with can be used. The amount used is preferably 0 to 60% by weight for styrene etc.
Can be used at 10-40% by weight. Acrylic acid, methacrylic acid, etc. are preferably 10% or less, and other monomers are
20% or less is preferable. The acrylic copolymer (2) is preferably polymerized by solution radical polymerization. That is, conventional polymerization initiators such as azobis are used in the presence of aromatic solvents such as toluene and xylene, and/or alcohol solvents such as isopropanol and isobutanol, and/or ester solvents such as ethyl acetate and butyl acetate. Polymerized by method. Chlorinated polyolefin modified with carboxyl group-containing monoethylenically unsaturated monomer ()
Chlorine is an essential component in order to provide adhesion to the substrate without causing defects in the appearance of the coating film due to poor compatibility when mixed with the above acrylic copolymer () to form a coating film. Preferably used are chlorinated polyethylene, chlorinated polypropylene, etc. modified with acrylic acid, methacrylic acid, etc. The ratio of these chlorinated polyolefins to the carboxyl group-containing monoethylenically unsaturated monomer is 99.9/0.1 to 80/20, preferably 99/1. ~90/10, and if the carboxyl group-containing monoethylenically unsaturated monomer is too small, the compatibility with the above acrylic copolymer will be poor,
If the amount is too large, the solubility of the modified chlorinated polyolefin itself in aromatic organic solvents becomes poor. Modification is achieved by grafting a carboxyl group-containing monoethylenically unsaturated monomer onto the chlorinated polyolefin using a radical generator as a catalyst. Those using peroxide catalysts are preferable, and those using peroxide catalysts are not suitable because they may cause significant discoloration when mixed with the acrylic copolymer (2). Glucidyl ether of a polyhydric alcohol is preferably used as the compound or resin having two or more epoxy groups per molecule. That is, ethylene glycol diglycidyl ether, glycerol polyglycidyl ether, sorbitol polyglycidyl ether and the like are preferably used, but are not limited thereto. For example, any material containing a substance having two or more epoxy groups per molecule can be used, such as an acrylic resin copolymerized with glycidyl acrylate or methacrylate. The blending ratio of the acrylic copolymer () and the chlorinated polyolefin () modified with a monoethylenically unsaturated monomer containing a carboxyl group is ()/() of 98/2 to 30/70, preferably
Used in the range 90/10 to 50/50. Too little () will result in insufficient adhesion to the substrate, while too much will cause problems with gasoline resistance, chemical resistance, etc. The blending ratio of the acrylic copolymer () and the compound or resin () having two or more epoxy groups per molecule is ()/() from 98/2 to 70/
30, preferably in the range of 95/5 to 80/20. If there is too little (), the crosslinking reaction with () will not be sufficient, causing problems in performance such as gasoline resistance, solvent resistance, and chemical resistance, and if there is too much, it will have a negative effect on weather resistance. In the composition of the present invention, it is desirable to mix the acrylic copolymer (), the modified chlorinated polyolefin (), and the epoxy compound or resin () immediately before coating. The epoxy compound or resin (2) may be mixed in advance, and the mixture and the acrylic copolymer (2) may be mixed immediately before coating. Pigments, additives, solvents, etc. are added as necessary, and the mixture is applied to the object to be coated. The applied coating film is dried at room temperature or, if necessary, by heating at a relatively low temperature, and a cured coating film is formed by a crosslinking reaction. Although it can be cured at relatively low temperatures and provides sufficient performance, there is no problem even if it is cured at high temperatures. A feature of the present invention is that in a coating film forming method using a compound or resin having an epoxy group as a crosslinking agent in the crosslinking reaction of a specific acrylic resin, the compound or resin modified with a carboxyl group-containing monoethylenically unsaturated monomer is used. The key point lies in the introduction of a specific chlorinated polyolefin. By using the composition of the present invention, a coating film with excellent adhesion to polyolefin resins, a good surface condition, and an excellent appearance can be obtained with a one-coat finish. It is possible to obtain a high-performance coating film with far superior gasoline resistance, solvent resistance, alkali resistance, chemical resistance, etc., than coating films obtained by similar methods. The composition of the present invention is preferably used for coating polyolefin resins, preferably polypropylene resins, and can also be used for coating other plastics, wood, general metals, and the like. In order to clarify the effects of the present invention, examples thereof are shown below. Example 1 In a flask equipped with a condenser, a thermometer, and a stirrer, 100 parts of toluene, 8 parts of dimethylaminoethyl methacrylate, and 35 parts of n-butyl methacrylate were added.
parts, 30 parts of methyl methacrylate, 27 parts of styrene,
Add 1 part of azobisisobutyronitrile to 80°C.
After stirring for 2 hours, 0.3 part of azobisisobutyronitrile was added 5 times every 2 hours, and the polymerization was completed in 16 hours to obtain an acrylic copolymer resin solution (2) with a nonvolatile content of 50%. Commercial untreated chlorinated polypropylene (non-volatile content 30%, degree of chlorination 35%) in another similar flask
Add 380 parts of acrylic acid, 6 parts of acrylic acid, and 1 part of azobisisobutyronitrile, stir at 70℃ for 2 hours, and then add azobisisobutyronitrile 6 times every 2 hours.
Add 0.3 parts at a time and finish in a total of 16 hours, and the non-volatile content
31% modified chlorinated polypropylene resin solution ()
I got it. Next, add 20 parts of toluene, 40 parts of titanium oxide, and sand grinder beads to 10 parts of the acrylic copolymer resin liquid in () and shake to disperse the pigment.
Add acrylic copolymer resin solution () 110 to this
1 part, 35 parts of the above modified chlorinated polypropylene resin solution ( ), and 6 parts of commercially available sorbitol polyglycidyl ether ( ) were mixed, diluted with aromatic thinner, and spray-painted on a polypropylene plate.
After drying at 60°C for 30 minutes, it was dried at room temperature for 7 days and various tests were conducted. A high-performance coating film with an excellent balance of adhesion, coating appearance, and various performances was obtained. The results are shown in Table 1. Example 2 In a flask similar to Example 1, 100% of toluene was added.
parts, 10 parts of dimethylaminoethyl methacrylate,
63 parts of methyl methacrylate, butyl acrylate
25 parts of acrylic acid, 2 parts of azobisisobutyronitrile, and 1 part of azobisisobutyronitrile were charged, and the same polymerization as in Example 1 was carried out to obtain an acrylic copolymer resin solution (2) with a nonvolatile content of 50%. In another similar flask, 380 parts of commercially available untreated chlorinated polypropylene (30% nonvolatile content, 35% degree of chlorination), 6 parts of methacrylic acid, and 1 part of azobisisobutyronitrile were charged, and the same method as in Example 1 was placed. Polymerization was carried out to obtain a modified chlorinated polypropylene resin solution () with a nonvolatile content of 31%. Next, a test piece was prepared in the same manner as in Example 1, and various tests were conducted. As a result, a high-performance coating film with an excellent balance of adhesion, coating film appearance, and various performances was obtained. The results are shown in Table 1. Comparative Example 1 A test piece was prepared in exactly the same manner as in Example 1, except that a commercially available untreated chlorinated polypropylene resin solution was used as it was in place of the modified chlorinated polypropylene resin solution () in Example 1, and various tests were carried out. I did this. The appearance and gloss of the coating film were poor, and there were also variations in adhesion. The results are shown in Table 1. Comparative Example 2 20 parts of toluene, 40 parts of titanium oxide, and sand grinder beads were added to 10 parts of the acrylic copolymer resin solution () obtained in Example 1, and the mixture was shaken.
Disperse the pigment. 110 parts of an acrylic copolymer resin solution () and 6 parts of commercially available sorbitol polyglycidyl ether () were added to this, and test pieces were prepared and tested in the same manner as in Example 1. As a result, satisfactory adhesion was not obtained and the coating film performance was also insufficient. The results are shown in Table 1. Comparative Example 3 In a flask similar to Example 1, 100% of toluene was added.
43 parts of n-butyl methacrylate, 30 parts of methyl methacrylate, 27 parts of styrene, and 1 part of azobisisobutyronitrile and polymerized in the same manner as in Example 1 to obtain an acrylic copolymer resin solution with a nonvolatile content of 50%. I got (). Next, add 20 parts of toluene to 10 parts of the acrylic copolymer resin solution () and titanium oxide.
Add 40 parts and a sand grinder bead and shake to disperse the pigment. This was mixed with 110 parts of the acrylic copolymer resin solution () and 35 parts of the modified chlorinated polypropylene resin solution obtained in Example 1, diluted with aromatic thinner, and spray-painted onto a polypropylene plate. Thereafter, test pieces were prepared in the same manner as in Example 1, and various tests were conducted. As a result, the adhesion was rather poor, and the coating film performance was not satisfactory. The results are shown in Table 1.

【table】

【table】

Claims (1)

[Claims] 1 () (1) Basic nitrogen-containing acrylic monomer 0.2 to 30% by weight (2) Ester of acrylic acid or methacrylic acid and aliphatic monohydric alcohol or a mixture thereof 35 to 99.8% Weight% (3) Acrylic copolymer obtained by blending monoethylenically unsaturated monomers copolymerizable with component (1) and component (2) so that the total amount is 100% by weight, and () Consisting of a chlorinated polyolefin modified with a carboxyl group-containing monoethylenically unsaturated monomer and a compound or resin having two or more epoxy groups per molecule, ()/() is from 98/2 to 30/70,
A coating composition in which ( )/( ) is 98/2 to 70/30.