JPH06246226A - Raw material body with easily peelable coating film - Google Patents

Abstract

PURPOSE:To provide a coating system technology wherein only a raw material is recovered and reused from the raw material of a coated specimen after use or removal of an unnecessary coating film adhered and accumulated on a hanger, a stage, a wall, etc., in an industrial coating process caused by scattering when coating is performed is made simple and easy to make reuse of these parts possible. CONSTITUTION:A foaming agent which does not decompose at a necessary drying condition of the coating system but does decompose at more severe condition, is dispersed and compounded in a thermoplastic resin binder and it is applied as an under-coating treatment of the raw material body or the part and after an arbitrary period of use, it is treated at high temp. to decompose and expand it to make peeling of the coating film easy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material having a coating film which can be easily peeled off. The object of the present invention is to contribute to the effective use of resources and thus to the preservation of the global environment, so that it is possible to recover only the material after use from a material such as painted metal, glass, rubber or plastic, and reuse it. Therefore, it is to provide a material having a coating film (coating film) that can be easily peeled off. Another object of the present invention is a hanger for transporting an object to be coated in an industrial coating process, a tool for masking, a table on which the object is placed, a side wall surface of a coating booth, etc., which scatters and adheres during coating. It is an object of the present invention to provide a composition for an undercoat paint that facilitates easy and easy removal of an unnecessary coating film and enables reuse (recycling) of these parts and the like.

[0002]

2. Description of the Related Art Conventionally, as a method of peeling a coating film adhered to a material, which is used for recovering only the material from a coated material and providing it for reuse, alteration by an organic solvent, an acid or an alkaline solution, Alternatively, a chemical method of melting and removing the coating film and applying high temperature (315-760
There are known physical methods such as burning at (° C.), spraying plastic powder at high speed, or applying a high-pressure jet water stream or carbon dioxide pellets to the coating film to remove the coating film from the material.

[0003]

However, the chemical method requires a considerably long time for dissolution and deterioration as the adhesive strength to the material and the durability are improved by the progress of the synthetic resin technology in recent years. There are many problems such as measures against fire caused by evaporation and scattering of organic solvent, length of treatment time in acid and alkali treatment, influence on human body due to temperature rise, maintenance of liquid and treatment of waste liquid. ing. On the other hand, in the physical method, afterburners are installed as a measure against VOC (volatile organic compounds) that occur in the combustion furnace as well as in the physical method, furnace temperature control, air supply equipment, or equipment that generates high-pressure blast in various blast methods, There are many problems such as specially designed booths, humidity control devices, dust recovery devices, and countermeasures for the effects on the human body.

[0004]

Means for Solving the Problems As a result of earnest research, the inventor of the present invention, as a base treatment for the recycling use of the material body, on the assumption that the material body is overcoated and used as a product for a certain period of time. Due to external stimuli, it does not decompose under the required drying conditions of the thermoplastic resin for paint, which incorporates chemical and physical changes that are easy to peel off, and the undercoat paint itself, as well as the middle or top coat paint, but more than that. The present inventors have found that such a defect can be eliminated by using a foaming agent that decomposes under the conditions as a base paint, and have reached the present invention. That is, the present invention applies a base coat containing a foaming agent that decomposes at a temperature higher than the drying temperature of the paint to be peeled off, and a thermoplastic resin binder, and then coats the base body with the paint (top coat paint). A method for producing a material having an easily peelable coating film characterized by the above, and a material having an easily peelable coating film produced by the method.

Suitable blowing agents used in the present invention include (1) inorganic blowing agents such as sodium bicarbonate and ammonium carbonate having a decomposition temperature in the range of 60 to 250 ° C., or (2) azo. Azo-based compounds such as bisformamide, azobisisobutyronitrile, diazoaminebenzene and azodicarbonamide, N, N′-dimethyl N,
In addition to N-nitroso compounds such as N'dinitrosoterephthalamide and N, N'-dinitrosopentamethylenetetramine, benzenesulfonyl hydrazide, toluene-4-
Examples of hydrazide-based organic foaming agents such as sulfonyl hydrazide, benzene 1,3-disulphonyl hydrazide, 4,4′-oxy (benzene sulfonyl hydrazide), and diphenyl sulfone 3,3′-disulfonyl hydrazide. They can be used alone or in combination. As the foaming agent used in the present invention, it is necessary to be higher than the maximum drying temperature of the coating system for coating on the above-mentioned foaming agent, preferably 30 ° C. or higher than the decomposition temperature,
More preferably, it is higher than 50 ° C. This is to prevent the undercoat film produced from the composition of the present invention from foaming and decomposing during the drying of the topcoat film. The particle size of the foaming agent is not particularly limited, but normally a particle size of about 1 μm to 50 μm can be used. However, when a top coat is applied on top of it, it is preferable to use a foaming agent having a particle size as small as possible (preferably about 2 to 5 μm).

The thermoplastic resin binder used in the present invention is an ordinary resin binder for paints, for example, a cellulose-based paint or an acrylic paint which is a lacquer type resin used for general industry, furniture or automobiles. , Vinyl-based paints and alkyd-based paints.
Among these resin binders, a preferable one is that it can be dried at a relatively low temperature, for example, room temperature of 120 ° C. or less, and gives a hard film, but it is softened in a short time (minute unit) when exposed to a temperature of 150 ° C. or more in a high temperature environment. Specific examples thereof include a short oil alkyd resin varnish, a thermoplastic resin varnish (epoxy resin-based resin and ε-caprolactam-modified diisocyanate) (coating resin varnish for metal materials), and the like.

The mixing ratio of the foaming agent in the thermoplastic resin binder is 1 to 20% by weight based on the weight of the resin binder,
It is preferably 5 to 10% by weight. If it is less than 1% by weight, the peeling effect due to foaming is too small. On the other hand, when the content is 20% by weight or more, a so-called excessive foaming state in which the foaming degree required for peeling is exceeded is obtained. To add a foaming agent to these resin binders, a physical (mechanical) process generally performed in paint production such as ball mill, sand grind mill, and dissolver, that is, mixing, dispersion, formulation, adjustment, filtration, etc. In order to produce an undercoat paint from them, for example, the method described in Examples below is used.

Examples of the material used in the present invention include molded articles made of metal, glass, rubber or plastic. The undercoat paint used in the present invention is not particularly limited as long as it is the undercoat paint used for the above materials. As the top coating, the coating usually used in combination with the bottom coating can be used as it is. Therefore, removal of the top coat film for recycling can be achieved simply by adding the composition of the present invention as the undercoat paint without changing the present coating system. Also, for undercoating and topcoating on various materials, ordinary brush coating, roller coating, air or airless spray coating, dip coating in which paint is placed in a tank and the material parts are passed through it to be applied. Various methods such as fluidized dipping and shower coat method are applied.

[0009]

The present invention relates to a foaming agent and a thermoplastic resin binder which decompose at a temperature higher than the drying temperature of the paint to be peeled off.
After making a base paint containing the above, and applying it to the material in advance and drying it sufficiently, the lacquer type top coat paint of room temperature drying is applied to finish the product. , When recycled, if this product is heated at a decomposition temperature or higher, the foaming agent in the undercoating film will be efficiently decomposed with the help of the thermoplastic film and the surface of the material body will be affected by the generated gas. And a lot of air bubbles are generated in the intermediate layer of the top coating film, and innumerable blisters are generated.The voids enable the top coating film to be peeled off with a very small physical force. The problems of the peeling method, especially its inefficiency, unhygienic work environment, installation of large-scale equipment and machinery, etc. are solved, and the hanger for transporting the coated object used in the industrial coating process is solved. Not only for masking and Metal, glass, but also be effective in recycling a variety of coating moldings made of plastic or the like.

[0010]

Example 1 Short oil alkyd resin varnish butyl acetate: toluene 1: 1 produced from coconut oil having an oil length of 30% and number average molecular weight of 1600, trimethylolpropane and phthalic anhydride.
A resin binder was prepared by mixing a 60% solution (weight ratio) diluted with a 20% solution of nitrified cotton in a weight ratio of 4: 1. To 40 parts by weight of this resin binder, Neocerbon N-1000S (manufactured by Eiwa Chemical Industry Co., Ltd., chemical name:
4 parts by weight of 4,4′-oxybis (benzenesulfonyl hydrazide, decomposition temperature: 159 ° C.) was added and well mixed and stirred in a mortar to prepare a peeling composition. This composition was used as a steel plate (manufactured by Daido Steel Co., Ltd., thickness 0.5 mm, 5 × 15 c).
m) is coated (using bar coat # 40) and left overnight at room temperature to dry, and then Nippe Super Coat 300HQ White (manufactured by Nippon Paint Co., Ltd., polyester resin paint) is applied as top coat (bar coat # 30). use)
And dried at 120 ° C. for 10 minutes. The coated steel sheet thus produced had an appearance similar to that of a normal coating film and strongly adhered to the base coating film, and was not damaged at all in the tape peeling test. However, by treating in an oven at 180 ° C for 10 minutes, a blister is generated on the entire surface of the topcoat, which indicates that the basecoat composition coating film has decomposed and foamed. It was confirmed that it peeled off cleanly.

Example 2 Epoxy ester resin (manufactured by Nippon Paint Co., Ltd.) used as a coating resin varnish for metal materials (number average molecular weight:
9500, glass transition point: 40 ° C.) and ε-caprolactam-modified diisocyanate were reacted at a weight ratio of 8: 1 to prepare a thermoplastic resin varnish. To 40 parts by weight of this resin, 4 parts by weight of Neocervon N-1000S was added and mixed well to prepare a peeling composition. The composition was coated (using Bar Coat # 40), dried at 120 ° C. for 10 minutes, Apply topcoat paint (same as above), 120 ℃, 10
It was dried for a minute to produce a coated steel plate for test. By processing this coated steel sheet in an oven at 180 ° C. for 10 minutes, occurrence of blisters in the top coating film was confirmed. JIS-K
As a result of peeling the tape by the 5400 adhesion test method, it was found that the tape showed peelability with an evaluation score of 2 to 4.

Example 3 40 parts by weight of the resin binder of Example 1 was added as a foaming agent,
Exceller S # 10 (manufactured by Eiwa Chemical Industry Co., Ltd., main component:
4 parts by weight of azodicarbonamide (decomposition temperature: 165 ° C.) were added, prepared in the same manner, coated on a steel plate, dried overnight at room temperature, coated with the above-mentioned topcoat paint and dried to prepare a test piece. This coated steel plate was treated in an oven at 220 ° C for 10 minutes, and it was confirmed that front blisters were generated in the top coating film. Evaluation score 2 for tape peeling according to JIS-K5400
It was found to exhibit a peelability of ~ 4.

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C08J 11/04 ZAB 7310-4F // B32B 7/06 9267-4F

Claims (2)

[Claims] 1. A base material is applied with an undercoat paint containing a foaming agent that decomposes at a temperature higher than the drying temperature of the paint to be peeled off and a thermoplastic resin binder, and then the paint (topcoat paint) is applied to the material body. A method for producing a material having a coating film that is easily peeled off, characterized in that 2. A material having a coating film produced by the method according to claim 1, which is easily peeled off.