Coating processes – Direct application of electrical – magnetic – wave – or... – Pretreatment of coating supply or source outside of primary...
Patent
1996-01-25
1998-06-02
Szekely, Peter A.
Coating processes
Direct application of electrical, magnetic, wave, or...
Pretreatment of coating supply or source outside of primary...
1563096, 156327, 156334, 204168, 264483, 427375, 427461, 427569, 427195, 522157, 522161, 523300, C09J12300, B05D 314, C08J 328
Patent
active
057596425
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a process for producing a polymer which can be used preferably as a powder coating material and/or hot-melt adhesive and to its use.
Processes for producing powder coating materials in which generally a mixing of polyethylene with .alpha.-olefinic polymeric additives takes place are already known (Catalog MIRATHEN Leuna Werke AG, 10/92). The polymeric additives contain certain functional groups which permit corresponding use of the powder coating material produced therefrom. It is disadvantageous in this case that there can only ever be produced one powder coating material for a limited application in each case. On the other hand, it is not possible to produce a powder coating material for a broad field of applications.
Furthermore, hot-melt adhesives are known, in particular on the chemical bases of polyvinyl acetate, polyamides, ethylene-vinyl acetate copolymers and polyester. These hot-melt adhesives are likewise formulated for certain specific applications, the requirements of which they meet, so that there are strict limits to any possibility of versatile use of the hot-melt adhesives.
DE-A 41 41 805 discloses a process and an apparatus for producing thermoplastic parts with the aid of low-temperature plasmas. This involves treating powdered or granular raw materials with low-temperature plasma before they are molded into a semi-finished product or component, in order to obtain a modification of the powder grain surface of the raw materials over a limited period of time.
The invention is therefore based on the object of providing a process of generic type by which powder coating materials and/or hot-melt adhesives which are versatile, that is to say can be used for a multiplicity of different application areas, can be produced in a simple and inexpensive way.
SUMMARY OF THE INVENTION
This object is achieved according to the invention by polyolefins being subjected to a low-temperature plasma treatment with frequencies changing during the treatment in a frequency range from 30 kHz to 10 GHz. Low-temperature plasma treatment is understood here to mean that the material to be treated is itself not heated beyond a certain temperature range, for example 40.degree. C. to 60.degree. C. It has surprisingly been found that, by this plasma treatment, the introduced polyolefins can be adjusted such that they can be used as powder coating materials or hotmelt adhesives generally, in particular also with different materials.
In an advantageous refinement of the invention it is envisaged that the plasma treatment is carried out preferably in a frequency range from 13.56 MHz to 2.45 GHz. In particular if the plasma treatment is carried out at changing frequencies, preferably with combinations of varyingly high, changing frequencies, it is possible very advantageously to cater for a different chemical structure and different compositions of the polyolef ins serving as starting materials, so that in each case powder coating materials or hot-melt adhesives having the properties necessary for their intended use can be produced.
In a further preferred refinement of the invention, it is envisaged that the plasma treatment is carried out under the supply of an inert gas, for example helium and/or argon, or under the supply of a reaction gas, for example oxygen and/or nitrogen. It is further preferred if the plasma treatment is carried out successively with an inert-gas plasma and at least one reaction-gas plasma or a reaction-gas plasma mixture or under the supply of a mixture of at least one inert gas and one reaction gas. By selection of a composition of the process gas matched to the starting material (inert gas, reaction gas, reaction gas mixture) it is possible to incorporate to an adequate extent the reactive groups required for the purpose of a coating and/or adhesive bonding, for example hydroxyl groups, carboxyl groups, primary and secondary amino groups. These groups are capable of reacting with the material to be coated and/or to be adhesively bonded and o
REFERENCES:
patent: 4626473 (1986-12-01), Loh et al.
patent: 5234723 (1993-08-01), Babacz
"Coatings, Inks, and Related Products," Chemical Abstracts vol. 102, No. 2, Jan. 14, 1995, Abstract No. 826lf, D.A. Rodchenko et al. Kunststoff Taschenbuch, pp. 258 & 259.
Arplas Gesellschaft Fur Plasmatechnologie mbH
Szekely Peter A.
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