Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1997-05-12
2004-02-03
Aftergut, Jeff H. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S214000, C156S221000, C156S245000, C156S285000, C156S309900, C156S322000, C264S257000, C264S510000, C264S511000, C264S571000
Reexamination Certificate
active
06685789
ABSTRACT:
The present invention relates to a method of manufacturing a laminated thermoforming which consists of a thermoformable thermoplastic resin, resin mixtures, or a resin matrix as substrate material of the thermoforming and at least one deformable backing material.
The present known methods in which laminating is effected in particular in order to improve the optical appearance or the thermal insulation and in which foils, non-wovens, textiles or foams are used as backing material comprise, inter alia, the subsequent backing of a substrate part with the use of additional adhesive, direct back spraying in the low-pressure method, direct back embossing in the compression-injection method, direct back-foaming in the foaming method and thermoforming.
Further methods which are known and possible at the present time in which metallic and/or electric conductive structures are applied to or in the plastic, in particular in order to improve or produce electromagnetic screening are, among others, the subsequent integrating of a metal fabric by special constructions in the entire part, by the working of conductive polymers in the injection molding process, by coating with conductive varnishes, by lining with metallic foils, by vapor deposition with aluminum, or by electro-chemical/galvanotechnical coating.
Furthermore, a screening material capable of deep drawing is available on the market as multiple-sandwich material of EVA non-woven fiber and metal non-woven fiber especially for EMI screening, the EVA non-woven fiber serving as thermoplastic adhesive and the metal non-woven fabric consisting of an alloy which melts upon the processing.
From German Utility Model G 92 16 080.8, a deep-drawing part of thermodeformable thermoplastic resin, resin mixture, or a resin matrix is known which consists of a fiber-reinforced polypropylene or polyethylene or a corresponding copolymer.
By the properties described in said utility model, this deep-drawing part finds many fields of use, including ones in which, in addition to the technical function, optical and decorative requirements and/or noise-dampening, insulating, electrical, electromagnetic or stability requirements exist which cannot be satisfied without additional surface treatment.
From German Patent Application DE 42 11 077 a method is known for the production of a molding having a structured surface in which a decoration substrate is first of all inserted into a deep-drawing mold, a plastic plate is introduced for the drawing of a molding, heated to forming temperature and then pulled into the mold by vacuum in the region of the deep-drawing mold. In this connection, the side facing the plastic molding should be at least partially material-locked in a surface layer of the plastic molding.
This method has the disadvantage that this material-locked connection cannot be obtained to a sufficient extent in all cases of use. In particular, in the event of larger deformations such as deep troughs and difficult geometry of the molded parts, such as undercuts, the required shaping and/or connection cannot be reliably obtained. Furthermore, the known method cannot be reliably used in the case of decoration materials of little or no air permeability since uncontrollable inclusions of air can remain between the plastic panel and the decorative material.
It is an object of the present invention to provide an inexpensive method for the simple manufacture of thermoformed parts which are backed on at least one side and consist of heat-deformable thermoplastic resin material, in which a dependable connection is obtained between the deformed plastic panel and the backing web and which is suitable both for backing materials for decorative or insulating purposes as well as materials of metal or other high-strength materials.
This object is achieved by the invention in the manner that before the thermoforming, at least one deformable backing web is introduced in the space between the plastic panel and a deep-drawing mold, the deformable backing web consisting of a material which stretches under the conditions of pressure and temperature which occur upon the thermoforming and/or of a material which does not stretch even under the pressure and temperature conditions occurring upon the thermoforming but is deformable on the surface by its intermeshing or change in angular position, and that the pressure and temperature conditions of the thermoforming process are so adjusted that plastic panel and backing web are permanently attached to each other by incorporation of melting together.
The invention proceeds in this connection from the discovery that a distinction may basically be made between two types of material for the backing web which is to be applied.
On the one hand, those materials which under the pressure and temperature conditions occurring during the thermoforming are themselves extendable and stretchable, in which connection the possible limits of the pressure and temperature conditions of both the material of the substrate panel and the backing material can be determined.
Other materials such as, for instance, metals, including metal alloys, or glass or carbon fibers, are as a rule extendable to stretchable only at temperatures which are above the limits of the processing temperature of a substrate plate. For the use of such materials, extendibility or stretchability of the material itself is, however, not necessarily required, inasmuch as backing webs for other uses which are deformable by their surface structure are available or can be produced. There are concerned here, in particular, metal-wire fabrics which are extendable in the surface due to their mesh shape, and metal-wire webs in which the wires are at a predetermined angle to each other and surface stretchability is possible during the processing by change in the angles.
Both types of material can also be present in mixed form, for instance as mixed fabric of cotton having metal wires woven or knitted therein.
Both materials, as well as mixed forms, can be undetachably attached to the substrate panel by the method of the invention if the pressure and temperature conditions of the thermoforming process are so selected that the backing web is incorporated into the substrate panel or melted together with it, in which connection the thermoforming process is preferably deep drawing.
By additional support by compressed air, a better precision in the shaping of the sandwich of plastic panel and backing web is obtained which makes undercuts and 90° bends possible since the sandwich is pressed with considerably greater forces into the deep-drawing mold. This goes hand in hand with a more dependable anchoring of the backing web in the surface of the plastic panel as a result of these greater forces. Furthermore, higher stretching and elongation forces can be exerted on the material or the structure of the backing web, as a result of which the precision in shaping is also improved.
The reliability of the material-locked connection is increased also in the case of backing webs of little or no air permeability.
For backing materials of high permeability such as, for instance, thin textiles in which only a controlled depth of penetration into the surface of the plastic panel is to take place, the method of the invention is particularly suitable, particularly in the case of complex shaping. Depending on the materials used, the method of the invention makes it possible to vary and optimize the parameters, pressing pressure and temperature of the plastic panel, which are causal for the shaping, in particular, of complex mold regions, and for the depth of penetration within a widened range for the pressing pressure. Thus, with the same shapeability, by lower temperature together with higher pressing pressure, the penetration caused by the temperature-dependent flowability can be reduced.
The same is true here for backing materials of metal or other high-strength materials which do not melt together with the plastic panel but adhere by targeted degree of the incorporation.
Apparatus at the present time permit s
Aftergut Jeff H.
Bachman & LaPointe P.C.
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