Chemistry: electrical and wave energy – Processes and products – Electrostatic field or electrical discharge
Patent
1999-01-04
2000-11-14
Gorgos, Kathryn
Chemistry: electrical and wave energy
Processes and products
Electrostatic field or electrical discharge
42218604, 42218605, 264 83, 264446, 264483, H05F 300
Patent
active
061465038
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for dry surface treatment of at least one surface portion of an object, and more particularly concerns the surface treatment of polymer articles, for example to modify their wettability.
2. Description of the Related Art
With regard to the example of polymers, it is known that a polymer surface does not wet in contact with water. Instead, water forms droplets rather than a continuous film when in contact with such a surface.
Under certain circumstances or for certain applications, it is nevertheless desirable to provide polymer surfaces which can be wet with water or, in general, with a fluid (for example an ink or a paint).
The most widespread process for treating such polymer surfaces consists of the so-called "corona discharge" treatment. Such a process makes it possible to modify the wettability of a polymer surface at relatively low cost, and is already used very widely on an industrial scale.
However, there are a number of drawbacks with such a process, in particular because of the fact that it is only suitable for the treatment of thin polymer films and that it is therefore incapable of treating polymer surfaces of large articles and, in general, three-dimensional articles (in particular, the great difficulties encountered, for example, in adapting to the treatment of automobile body parts will be understood).
The Applicant Company recently proposed, in document EP-A-370870, a process for dry fluxing of a metal surface before soldering or tinning using an alloy, which is noteworthy in that the surface to be fluxed is treated, at a pressure close to atmospheric pressure, with a treatment gas atmosphere which comprises excited or unstable species and is substantially free of electrically charged species, and is obtained from a gas mixture delivered at the gas outlet of an instrument for forming excited or unstable gas species.
In this document, this process is more particularly exemplified and illustrated with the aid of a particular instrument for forming excited or unstable gas molecules, operating substantially at atmospheric pressure, which is described in the document FR-A-2,692,730 in the name of the Applicant Company.
This work has undeniably given an advantageous first response to the question of the limitation of objects which can be treated in volume.
SUMMARY AND OBJECT OF THE INVENTION
The object of the present invention is to overcome the drawbacks which have already been pointed out, and to provide a process and a device for surface treatment of objects which can further have relatively low gas consumption so that it can be compatible with use on an industrial scale for large numbers of objects to be treated.
It therefore relates to a process for dry surface treatment of at least one surface portion of an object, according to which a primary gas is passed through at least one instrument for forming excited or unstable gas species, and the surface portion is brought in front of the gas outlet of the instrument with a view to treating it with a secondary gas which is delivered to the gas outlet, and contains excited or unstable gas species and is one wherein the secondary gas delivered through the outlet of the instrument and used for the treatment is taken in again by the Venturi effect and reinjected into the instrument.
The process according to the invention may further have one or more of the following characteristics: electrically charged species; to the invention, the term "pressure close to atmospheric pressure" is intended to mean a pressure lying in the range from 0.1.times.10.sup.5 Pa to 3.times.10.sup.5 Pa; oxidizing gases and reducing gases; outlet of the instrument, where appropriate in front of the gas outlets of a plurality of instruments for forming excited or unstable gas species which are arranged in parallel over the width of the object and/or successively in front of the gas outlets of a plurality of instruments for forming excited or unstable gas species which are arrang
REFERENCES:
patent: 3484363 (1969-12-01), Williams
patent: 4946568 (1990-08-01), Kalwar et al.
patent: 5458856 (1995-10-01), Marie et al.
patent: 5484560 (1996-01-01), Moriyama et al.
patent: 5667563 (1997-09-01), Silva, Jr.
patent: 5858312 (1999-01-01), Sindzingre et al.
Copy of EP Search Report No. PCT/FR97/01027 dated Sep. 9, 1997.
Rabia Stephane
Sindzingre Thierry
Gorgos Kathryn
L'Air Liquide Societe Anonyme pour l 'Etude et l 'Exploitation d
Nicolas Wesley A.
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