Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Patent
1995-09-20
1998-02-10
Stemmer, Daniel
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
15624412, 156324, 1565835, 264129, 264257, 264258, B29C 4702, B29C 7050
Patent
active
057164797
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention concerns a method for manufacturing fiberglass-reinforced thermoplastic panels, their advantageous applications and also equipment with which to implement this method.
2. Description of the Prior Art
The manufacture of fiberglass reinforced thermoplastic panels using a homogeneous melt of the thermoplastic in an extruder is known, in which the melt is forced out through a die to flow between parallel-running fiberglass mats. Next these fiberglass mats are impregnated at raised pressure and higher temperature with the thermoplastic melt and the composite so formed is then cooled under pressure.
This procedure suffers from the drawback that the thermoplastic melt is deposited only on one side of the fiberglass mat. As a result, high pressures and high temperatures must be applied to ensure uniform impregnation of the mats. In turn, however, high pressures require bulky, energy-consuming presses which are difficult to handle.
SUMMARY OF THE INVENTION
The object of the invention is to create an easily implemented, energy-conserving method for the manufacture of fiberglass-reinforced thermoplastic panels simultaneously allowing uniform impregnation of the fiberglass mat(s) being used.
Accordingly the invention proposes a method in which at least one fiberglass mat (10, 11) is made to pass through the aperture (3', 4') of an impregnation nozzle (3, 4) which is fed in controlled manner with the thermoplastic melt (26, 28) from the extruders (1, 2) such that two streams of melt (26', 26" and 28', 28") are formed and deposited at the outlet of the nozzle aperture (27, 27') onto the top and bottom sides of the glass mat (10, 11), the impregnation of the fiberglass mat taking place in the process. Thereafter, the fiberglass mat (30, 30') impregnated with the thermoplastic is guided into a gap (18) between entry rollers of a double belt press (5) and is calibrated, finally being compressed by means of the cooling plates (22, 22') into the fiberglass-reinforced thermoplastic panels (25).
The invention also proposes simultaneously passing two fiberglass mats (10, 11) through the apertures (3', 4') of the impregnating nozzles (3, 4) which are fed in controlled manner with the thermoplastic melts (26, 28) from the extruders (1, 2), such that two flows of melt (26', 26" and 28', 28") are formed and deposited at the outlet of the nozzle aperture (27, 27') onto the top and bottom sides of the glass mats (10, 11) with simultaneous impregnation of the fiberglass mats. Thereafter, the glass mats (30, 30'), impregnated with thermoplastic, are made to pass into the gap (18) between entry rollers of the double belt press (5) and are calibrated, and then are compressed by means of the cooling plates (22, 22') into the fiberglass-reinforced thermoplastic panels (25).
Advantageously the fiberglass mats (10, 11) are preheated in the nozzle aperture (3', 4').
A low-viscosity polypropylene melt, which may contain additives such as peroxides, is advantageously used as the impregnation thermoplastic melt (26, 28).
The invention offers another advantage, wherein the flow of melt (26', 26" and 28', 28") is controlled by means of melt-control valves (29, 29') present in the distribution unit (8, 9).
Advantageously the fiberglass mat is composed of cut, tangled and/or unidirectional and/or directional uncut glass fibers with a surface content of 450 to 1,300 g/m.sup.2.
In another advantageous embodiment of the method of the invention, the impregnated fiberglass mats 30, 30' are calibrated in the cross-sectionally adjustable gap 18 between the entry rollers. Thereafter, the compound of thermoplastic and fiberglass mats so formed is compressed at a maximum pressure of 2 bars in the compression zone.
Advantageously the fiberglass-reinforced thermoplastic panels manufactured in the manner of the invention are used as molded parts, for instance automotive parts.
The equipment with which to implement the method of the invention is composed of the extruders (1, 2), the control u
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Erhardt Gunter
Mikats Gunther
Isosport Verbundbauteile Gesellschaft m.b.H.
Stemmer Daniel
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