Chemistry: electrical and wave energy – Processes and products – Electrostatic field or electrical discharge
Patent
1993-11-09
1995-06-27
Niebling, John
Chemistry: electrical and wave energy
Processes and products
Electrostatic field or electrical discharge
204164, 204165, B29C 7104
Patent
active
054276624
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method for producing an ionomer. The invention relates more in particular to the producing of an ionomer from a plastic which initially usually contains no incorporated ion compounds in addition to the normal organic covalent bonds.
This new method for producing ionomers comprises: surface of the plastic; and
It has been found, namely, that if a plastic is loaded with an electrical field in the presence of an electrically conducting medium, groups are radicalized or ionized from the external and/or internal plastic surface in the direction of the electrical field in the plastic, which groups are converted as a result for instance of oxidation reactions into for example carboxylic acids and/or sulphonic acids. Understood by plastic surface is, among other things, an external plastic surface optionally provided with grooves, scratches or other surface defects and walls of cavities in the plastic which may contain contaminants. Under the influence of the electrically conducting medium these oxidized groups will dissociate and in the presence of metal ions form the characteristic ionogenic, functional groups, i.e. chemically bonded salt groups. Thus formed in the generally amorphous phase of the plastic are hydrophilic channels which are however semi-permeable. The electrically conducting medium, for instance water, is mobile in these channels but hydrated ions can only displace in these channels under the influence of the electrical field. Depending on the nature and composition of the electrically conducting medium and the applied electrical field an ionomer according to the invention can also be provided with cavities in which salts are entrapped.
Both liquids and gases can be used as electrically conducting medium. The latter has the particular objective that the oxidized groups can dissociate and form an ionogenic, functional group with the metal ions supplied by the medium. The electrically conducting medium can be an inorganic medium such as water and ammonia. The electrically conducting medium can likewise be an organic medium such as alkanols, for instance methanol and ethanol. If the electrically conducting medium has an inherent insufficient activity, diverse reactive components can be added to the medium and/or to the plastic.
One group of reactive components consists of gases such as oxygen, ozone, sulphur oxide, for instance sulphur dioxide. Such gases can sustain and assist the radical-forming or ion-forming reactions as well as the oxidation reactions.
Another group of reactive components is formed by salts, particularly salts of multivalent metal ions such as copper, tin and manganese. Such metal ions accelerate the growth of the hydrophilic channels, possibly partly due to a catalytic acceleration of the oxidation reactions.
Another group of reactive components is formed by surface-active substances such as a soap. These surface-active substances, for example a stearate, can on the one hand effect the same function as the salts and on the other reduce the surface tension so that the electrically conducting, more or less polar medium can penetrate more rapidly into the apolar plastic. Other examples of soaps for use comprise alkyl sulphonates, aryl sulphonates, alkyl(aryl) sulphonates and ethylene oxide adducts optionally in combination with alkyl and/or aryl groups.
The magnitude of the electrical field applied over the plastic is not limited to a determined value. A first forming of ionogenic, functional groups already takes place from a value of 1 V/mm of plastic. An upper limit for the magnitude of the electrical field is determined by the short-circuit voltage of the plastic, which voltage can change as the ionomeric character of the plastic increases. A reasonable speed for the forming of the ionogenic, functional groups occurs with an electrical field of 0.2 to 20 kV/mm. If for instance the plastic consists of polyethylene, optimum speeds for the forming of ionogenic, functional groups are obtained when the electrical field amounts to 0.5 to 10 kV/mm. In gener
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N.V. Kema
Niebling John
Phasge Arun S,.
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