Plastic and nonmetallic article shaping or treating: processes – Direct application of electrical or wave energy to work – Limited to treatment of surface or coated surface
Patent
1997-05-23
1999-11-23
Silbaugh, Jan H.
Plastic and nonmetallic article shaping or treating: processes
Direct application of electrical or wave energy to work
Limited to treatment of surface or coated surface
264483, 264489, 427573, 20415715, 204165, B01J 1912
Patent
active
059894776
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process for the chemical modification of solids containing alkyl groups, and to chemically modified solids containing alkyl groups.
It is known that solids containing alkyl groups, for example polyolefins and waxes, can be used in many fields. Use, for example, as coating materials, hot-melt adhesives etc., is possible. For the processability of the solids containing alkyl groups in the most varied fields of use, these solids must be mixed with certain additives which are latched to the particular field of use. Because of the multiplicity of possible fields of application, a comprehensive uniform use of the solids containing alkyl groups is thus impossible.
Kunststoff-Taschenbuch, 25th edition, pages 248 to 259, discloses a process for the aftertreatment of solids containing alkyl groups. In this process, the surface of the solid containing alkyl groups, for example a PE surface, is treated with a high-voltage plasma, in order to achieve a local chemical modification. Owing to this local surface treatment, for example in the case of moldings, an improvement in the coatability or printability is achieved. However, it is a disadvantage in this case that an additional aftertreatment must be performed, the application of which is possible only to a restricted extent owing to the provision of a high-voltage plasma unit for the finished product.
The object therefore underlying the invention is to create a process of the generic type by which a chemical modification of solids containing alkyl groups is possible in a simple and inexpensive manner.
According to the invention, this object is achieved by heating the solids containing alkyl groups to temperatures above their melting point and subjecting them to a plasma treatment in a frequency range from 10 kHz to 10 GHz. Surprisingly, it was found that owing to the conversion of the solids containing alkyl groups into a melt and their plasma treatment, a modification of material properties can be specifically induced within the solids containing alkyl groups. Owing to the conversion into a melt, a qualitatively and quantitatively higher grade chemical modification may be achieved. In particular, by means of the plasma treatment of the melt of the solids containing alkyl groups, special chemical products can be achieved which can be used in a versatile manner without requiring a further complex aftertreatment. A degree of the chemical modification of the solids containing alkyl groups may preferably be achieved in a simple manner by adjusting a viscosity of the melt and/or parameters of the plasma treatment.
In an advantageous development of the invention it is provided that the plasma treatment is carried out with alternating frequencies, preferably with combinations of different alternating frequencies. Thus, the plasma treatment can be carried out highly advantageously with successively selectable frequencies, with alternately selectable different frequencies, with at least two simultaneously selectable different frequencies, and combinations of frequency selections resulting therefrom. By this means, the chemical modification can highly advantageously be matched to the different chemical structure of the solids containing alkyl groups used and to their application by the chemical modification.
In a further advantageous development of the invention, it is provided that the plasma treatment is carried out with supply of at least one inert gas, for example helium and/or argon, and/or with supply of at least one reaction gas, for example oxygen and/or nitrogen. It is further preferred if the plasma treatment is carried out in succession with an inert gas plasma and at least one reaction gas plasma and/or a reaction gas plasma mixture or with supply of a mixture of at least one inert gas and one reaction gas. By choosing a composition of the process gas during the plasma treatment (inert gas, reaction gas, reaction gas mixture) which is matched to the solids which contain the alkyl groups and are to be modified, it is possible to incorporate
REFERENCES:
patent: 2167718 (1939-08-01), Harris, Jr. et al.
Noller, Chemistry of Organic Compounds, p. 205, 1965.
Chemical Abstracts, 26473d., vol. 81, No. 6, Aug. 12, 1974.
Arplas Gesellschaft Fur Plasmatechnologie mbH
Jones Kenneth M.
Silbaugh Jan H.
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