Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Patent
1996-01-19
1998-06-16
Nilano, Patrick D.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
4273722, 4273855, 4273935, 4284231, 4284242, 4284248, 524591, 524839, 524840, 525123, 525455, C08J 300, C08K 320, C08L 7500, B32B 2700
Patent
active
057671885
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to water-based paint compositions, a painting method and paint films; more narrowly, it relates to water-based paint compositions suitable as primers of plastic material, and particular polypropylene material, to a method of painting them, and to their paint films.
Plastic materials are popular as industrial materials for automobiles and household electrical appliances. Polypropylene materials in particular are among the materials most in demand because have good chemical and physical properties, are light and low priced, and moreover are easy to recycle, etc.
However, because polypropylene materials have low polarity and crystallinity, paint films do not readily adhere to them, and in normal painting special pre-treatment is necessary.
As the above pretreatment, flame treatment, corona discharge treatment, treatment by exposure to ultraviolet radiation, plasma treatment and painting with special primer can be cited; but flame treatment is a fire hazard, and corona discharge treatment, ultraviolet irradiation and plasma treatment are not very popular either, for reasons such as the fact that treatment uniform treatment of material in complex shapes is difficult, and that the costs of equipment are considerable, etc.; and the adherence of paint films is generally ensured by painting with a special primer. In the automobile industry, painting with special primers of this type is generally carried out as follows.
Firstly, the polypropylene material is degreased and cleaned in 1,1,1-trichloroethane vapour and then dried. The special primer is painted onto this polypropylene material, it is dried naturally or force dried, and then the topcoat paints are painted onto the surface of the primer, heated and cured to form a completed paint film on the material.
The role of the special primer here is to ensure adherence with both the polypropylene material and the topcoat paint film. Consequently, special primers include as an essential component polyolefin resin with a high affinity for the polypropylene material in order to confer adhesion to the polypropylene material; and adherence to the topcoat paint film is ensured by further introducing polar groups into this polyolefin, and if necessary using it mixed with a polar resin. An example of such specialised primers are primer compositions made up of epoxy resin and chlorinated polyolefin resin modified with an acid anhydride, known in Japanese Examined Patent 63-50381.
However, the polyolefin resins which are essential resin components in prior special primers have quite high molecular masses, and are not readily soluble in organic solvents, so primers adjusted to a viscosity suitable for painting contain a large quantity of organic solvent, and a large quantity of organic solvent is released into the atmosphere during painting. Consequently, there is a risk of fire, and problems with deterioration of the working environment and atmospheric pollution are produced.
Similarly, the 1,1,1-trichloroethane which is employed for degreasing and cleaning polypropylene materials destroys the ozone layer, and its use is restricted; hence, new degreasing and cleaning methods are being investigated, and the switch over to these new methods has already begun. The new methods are largely water washing methods using acid or alkaline detergents.
However, whereas the method using 1,1,1-trichloroethane, besides cleaning the surface of the material, acts to swell the material and etch the surface, which contributes considerably to adhesion between the special primer and the material, the new methods are weak as far as this sort of action is concerned, and switching to the new methods invites a decrease in adhesion between special primers and the material. This lowering of adhesion affects particularly the petrol resistance and water resistance of the paint film, and means that the paint film becomes prone to blistering and peeling. Various methods are available for testing the petrol resistance of paint films; particularly rigorous are tests of petrol re
REFERENCES:
Derwent, "Aqueous resin composition paint adhesive comprise chlorinated polyolefin base sodium hydroxide tri ethylamine option surfactant".
Furuuchi Kazuyoshi
Hermann Ulrich
Kamikuri Joshimasa
Nakamishi Toshihiko
BASF Lacke & Farben AG
Nilano Patrick D.
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