Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Patent
1992-01-10
1993-11-02
Aftergut, Jeff H.
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
156252, 156253, 156296, 156324, 1565835, 264109, 264113, B29C 6502, B29C 6518
Patent
active
052580857
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a process for producing a laminated material in sheet or membrane form from thermoplastic foam, in particular for use as a drainage sheet or membrane.
Prior Art
A process of the generic type is known from DE-C2-30 37 011 (US-A-4,417,932). According to this process, membranes or sheets are produced from remnant shreds of polyethylene foam of high apparent density by means of radiant heat and subsequent pressure treatment. A disadvantage of the known process is the high expenditure on apparatus. Furthermore, this process is suitable only for the processing of foam shreds of uniform apparent density. High fault susceptibility is to be observed in particular in the case of low apparent densities (less than 80 kg/m.sup.3).
Similar processes are also known from British Patent 1,578,045 and US-A-3,746,610.
Object
The object of the present invention is, therefore, to provide a process for producing a layered material in sheet or membrane form from thermoplastic foam, in particular for use as a drainage sheet or membrane, which makes it possible to process foam material of various apparent densities with low expenditure on apparatus.
SUMMARY OF THE INVENTION
This object is achieved according to the invention by being piled up to form a layer of uniform height and temperature of the foam, perforated and fused with the aid of pins, which are heated to a temperature of more than 250.degree. C., preferably up to 800.degree. C. (e.g., 400.degree. to 800.degree. C.), and which have an outside diameter of 2 to 15 mm, at an average spacing of 10 to 50 mm and with a dwell time of the pins of 1 to 10 s maintaining the compression.
An essential feature of the invention is that the compacted foam strips, lengths or shreds are fused to one another within a short time by means of heated metal pins or the like. The high maximum temperature of the pins, preferably 600.degree. to 700.degree. C., has the effect that the foam material is in contact with the metal pins only for a short time and is subsequently further heated indirectly, i.e., by thermal conduction or thermal radiation. Accordingly, the finished membrane or sheet subsequently has perforations composed of channels, the individual channels having a diameter which is approximately 2 to 4 mm greater than the diameter of the pins used.
The process according to the invention can be performed both discontinuously and (quasi) continuously. In the case of a discontinuous procedure, for example, foam shreds of chemically or physically crosslinked polyethylene foam, in particular remnant or recycling material, are poured into a mould, the filling height preferably being 20 to 200 mm, especially 30 to 150 mm. If a foam material of high relative density is used, a low filling height is preferred and, if foam material of lower relative density is used, a higher filling height is preferred. The mould is subsequently closed by means of a perforated cover and the foam is compressed. Subsequently, externally heated or internally heatable metal pins are pushed through the holes of the cover and, after a dwell time of 1 to 10 s, preferably 2 to 4 s, are withdrawn again. The heated or heatable metal pins may in this case be arranged in one or more rows, if appropriate all the holes or channels may also be produced simultaneously by a correspondingly high number of metal pins. The diameters of the holes of the cover are expediently adapted to the outside diameter of the heated or heatable metal pins.
The process according to the invention can be carried out (quasi) continuously in a particularly cost-effective way by shreds or the like of thermoplastic foam, preferably of chemically or physically crosslinked polyethylene foam, being compacted between two compression-resistant chain belts (double-belt press) and fed to a fusing station. The compression-resistant chain belts are, in this case, expediently perforated and move in steps. During the standstill phase, the fusing is performed by pushing externally heated or internally heated
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patent: 3384696 (1968-05-01), Makansi
patent: 3451109 (1969-06-01), Klein
patent: 3746610 (1973-07-01), Hoegger
patent: 3867240 (1975-02-01), Doerfling
patent: 3966526 (1976-06-01), Doerfling
patent: 4082824 (1978-04-01), Del Carpio
patent: 4417932 (1983-11-01), Breitscheidel et al.
patent: 4758297 (1988-07-01), Calligarich
patent: 5066531 (1991-11-01), Legg et al.
Patent Abstracts of Japan, vol. 7, No. 81 (M-205), Apr. 5, 1983 (JP 58-5335).
Breitscheidel Hans-Ulrich
Lorry Cosmas
Aftergut Jeff H.
Huls Troisdorf Aktiengesellschaft
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