Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1984-01-12
1984-07-10
Griffin, Ronald W.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
106252, 106264, 523500, 523523, 523526, 525170, C09D 352, C09D 368, C09D 502
Patent
active
044593791
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to aqueous film-forming binder dispersions or emulsions which are used as rapid-hardening coatings and may contain plasticizers, flatting agents, fillers, pigments, additives and assistants.
Aqueous emulsions of unsaturated polyester resins are known from European Patent Specification No. 3,337, corresponding to U.S. Pat. No. 4,281,068. They contain two unsaturated polyesters having .beta.,.gamma.-ethylenically unsaturated ether groups, and one of these polyesters additionally contains cocondensed polyalkylene glycol radicals. These known emulsions are free of monomers and contain waxes or paraffins as barrier agents to prevent inhibition of polymerization by atmospheric oxygen. These known emulsions can be hardened, in mixture with photoinitiators, with the aid of UV radiation or can be polymerized, in mixture with peroxides, at room temperature. They are proposed for the open-pore coating of wood or wood-like materials.
These known polyester emulsions have the disadvantage that they require a relatively long drying time, and, when using higher temperatures, an intermediate drying step over an evaporation zone is necessary to remove the water, since otherwise the film is made milky by water inclusions. When using a continuous operation where very short hardening times are important, the hardening time is not adequate to ensure that the material can be stacked or wound up.
SUMMARY OF THE INVENTION
The object of the present invention is therefore to provide aqueous dispersions or emulsions of this type for rapid-hardening coatings and which do not have the known disadvantages.
This object is achieved, surprisingly, by means of aqueous film-forming binder dispersions or emulsions which are used as rapid-hardening coatings and which contain at least one acrylate polymer having a film-forming temperature of above 60.degree. C. and at least one unsaturated polyester resin.
Particularly good results are obtained with--and hence preferable are those--aqueous dispersions or emulsions in which 70 to 30% by weight of unsaturated polyester resin are used per 30 to 70% by weight of acrylate polymer, and the total of acrylate polymer and unsaturated polyester resin is 100% by weight.
The invention also relates to the use of the aqueous dispersion or emulsion for producing rapid-hardening coatings on surfaces of wood, wood materials, paper, fleeces, cured or uncured, woven or nonwoven substrates which are impregnated with impregnating resins, plastic sheeting, asbestos cement board, mineral fiber board and metals, such as, for example, aluminum.
The invention also relates to a process for producing a rapid-hardening coating on a substrate, which process comprises mixing the aqueous dispersion or emulsion according to the invention with a water-soluble peroxide hardener and, after application to the substrate, hardening the coating within a few seconds at a temperature of above 80.degree. C., preferably above 100.degree. C., to give a nontacky and stackable result.
The dispersions or emulsions according to the invention do not contain organic solvent and can be diluted with water. They are also free of monomers which could be copolymerized with the unsaturated polyesters.
The dispersions or emulsions according to the invention are virtually odor-free, and they are suitable for use as rapid-hardening coatings on many substrates. The hardened coatings are scratch-proof and resistant towards water, alcohol, household chemicals and solvents. Since water is the only diluent used, the dispersions or emulsions are nonflammable. Working equipment with which these materials come into contact can be cleaned by rinsing down with water. The additional use of crosslinking (sic) agents is dispensed with.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
To effect hardening, cobalt accelerators and peroxide hardeners are added to the dispersions or emulsions according to the invention. At elevated temperatures above 80.degree. C., nontacky hardening immediately commences after a short tim
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BASF Farben & Fasern AG
Griffin Ronald W.
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