Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Patent
1997-06-04
1999-03-02
Copenheaver, Blaine R.
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
15624422, 15624424, 15624427, 156324, 264 459, 264258, 264321, B29C 4706, B29C 4790, B32B 3106, B32B 3108
Patent
active
058765344
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention concerns a composite panel as well as a process for the manufacture of the same.
DESCRIPTION OF RELATED ART
Composite panels are multi-layered connecting materials made up by one or more core layers as well as by outer layers attached to the same. They are used, for example, for the molded fittings of motor vehicles, causing the composite panel to be subjected to high mechanical stress. Therefore, the raw material providing for at least the outer layers has a metallic base. However, these materials are unsuitable, particularly due to their weight, for automobile fittings.
Therefore, the composite panels used for the molded fittings of automobiles have preferably a base of light plywood. These plywood composite panels consist of a fundamentally uneven number--at least 3 to 15--of thin wood layers glued to each other, wherein the fiber direction of the adjoining layers is alternated mainly at 90.degree.. The adhesion is carried out with acrylic adhesives under pressure and high temperatures, generating work materials of a higher resistance.
These materials are, however, disadvantaged because they are structured inhomogeneously with respect to the material due to the adhesive layers. Defective areas with deteriorated mechanical values can also be caused by the inhomogeneously structured composite construction.
Plywood also has the further disadvantage that it absorbs in large measure the humidity of the air, whereby the mechanic values such as those of the resistance to bending are also deteriorated.
The object of the invention is to provide homogeneously structured composite panels that have good mechanical values and low total weight.
SUMMARY OF THE INVENTION
Proposed is a composite panel (40) comprising a foamed thermoplastic core layer (39), which is attached on both sides with fiberglass mat-reinforced outer layers (25, 25') without adhesive.
This composite panel is further characterized in that it has a density of 0.5 to 0.8 g/cm.sup.3 and in that the thermoplastic materials of the core and the outer layers are of the same group of plastics, preferably of the group of the polyolefins.
Further advantages of the composite panel of the invention are that the thermoplastic polyoleofin material of the core and the outer layers is polypropylene.
A process for manufacturing a composite panel is also included in the invention, which is characterized in that mat-reinforced thermoplastics, two fiberglass mats (10, 11) are guided through the nozzle apertures (3', 4') of the impregnation nozzles (3, 4), which are feed in controlled manner by means of the extruders (1, 2) with the thermoplastic melts (26, 28) and in that each of the two streams of melt (26', 26", and 28', 28") is formed and applied to the upper and lower side of the glass mats (10, 11) at the outlet of the nozzle aperture (27, 27'), whereby the pre-impregnation of the fiberglass mats takes place and in that with the foamed thermoplastic (39') transported by means of the extruder nozzle aperture (37), which thermoplastic (39') serves for the formation of the core layer (39), are guided into the gap (18) between rollers of the double band press (5), whereby the pre-impregnated fiberglass mats are pre-calibrated, on the one hand, and on the other, are attached on both sides to the foamed thermoplastics (39') without using an adhesive, so that a pre-compound (36) is formed and then pressed under pressure by means of the cooling plates (22, 22') into the composite panel (40).
The fiberglass mats (10, 11) are advantageously preheated in the nozzle aperture (3', 4') and the foamed thermoplastic (39') is preheated in the nozzle aperture (37).
Further advantages of the invention process are that a low viscosity polypropylene melt is used as thermoplastic melt (26, 28), which can contain additives such as peroxide, and the melt stream (26', 26") and (28', 28") can be regulated by means of the melt-control valves (29, 29') installed in the distributor unit (8, 9).
A further advantage of the invention process, th
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Copenheaver Blaine R.
Isosport Verbundbauteile Gesellschaft m.b.H.
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