Coating processes – With cutting – holding – severing – or abrading the base
Patent
1993-12-23
1995-07-25
Owens, Terry J.
Coating processes
With cutting, holding, severing, or abrading the base
427428, 4274342, 118202, 118206, 118419, B05D 118, B05D 128, B05C 112, B05C 3152
Patent
active
054360315
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention concerns a method for impregnating a flat, fibrous substrate penetrated by a fluid synthetic resin of low viscosity, products made using this method and apparatus with which to carry out the method.
2. Discussion of the Prior Art
It is known to lower the viscosity of the resin to be deposited on a substrate to achieve adequate impregnation. Illustratively this is done by adding solvents such as water or alcohols. When using paper, the addition of water to the resin mixture causes swelling of the substrate. The large amount of solvent required for swelling must be evaporated following impregnation; this condition requires substantial transit times in the drier and as a result limits on the capacity of the impregnating device.
It is further known from the Japanese patent document A 59-042923 to avoid an increase in viscosity during impregnation by preventing solvent evaporation from the bath by means of a cover. The substrate to be impregnated is guided by a scoop roller dipping into the bath and thereupon it is returned by direction-changing rollers into the resin bath.
SUMMARY OF THE INVENTION
The object of the invention is to create a method which reduces the quantities of solvents and hence the drying times, thereby shortening the transit times in the drier.
The object of the invention is achieved by the method of the invention in that the substrate web 1 is preheated by means 2 known per se and guided over and uniformly wetted, by a friction roller 3 which is heated when called for and is in contact with a low-viscosity, aqueous solution of synthetic resin 5, 5' in a bath 4, at the web surface 6 with said solution 5, 5', the low-viscosity, aqueous solution of synthetic resin being heated uniformly and at least part of the synthetic resin penetrates the surface of the substrate web 1, and in that thereupon the substrate web loaded with synthetic resin is fully soaked a,ad in that the substrate web impregnated with synthetic resin then passes through a metering device 7 and drying channel 8 wherein solvents of the aqueous, synthetic-resin solution absorbed by the substrate web are extensively evaporated in a flow of hot air, the said substrate web then being cut to size as flat pieces 10 in cutting means 9 and thereupon being stacked in a stacking means 11.
The aqueous solution of synthetic resin 5, 5' advantageously contains 0 to 30%-weight of lower alcohols.
The temperature of the friction roller 3 advantageously is kept constant in the range of 40' to 120.degree. C.
The support web 1 advantageously is preheated to a temperature in a range from 40.degree. to 95.degree. C., illustratively using a heated roller. The aqueous, low-viscosity synthetic-resin solution 5 in the bath 4 advantageously may be based on an aminoplastic, such as melamine resin, kept at room temperature during the procedure. The proportion of aminoplastic or melamine resin advantageously is 45 to 65%-weight, the proportion of the aqueous solvents is 35 to 55%-weight.
The resin may be advantageously based on a phenol-formaldehyde resin 5' of which the proportion in the solution is 45 to 80%-weight and the proportion of aqueous solvents is 55 to 20%-weight. The phenol-formaldehyde-resin based synthetic-resin solution is advantageously kept constant at a temperature within the range of 30.degree. to 80.degree. C., preferably 40.degree. to 50.degree. C. by means of a temperature-regulating circuit 12. If the selected synthetic resin is based on an aminoplastic resin, substantially melamine resin 5, then the equipment to carry out the method of the invention is composed of several devices 13 to feed and change the direction of the support web 1, a preheating roller 2, a heated friction roller 3 and a bath 4, with deflection rollers 13' being mounted 1-2 meters above the bath. The apparatus moreover comprises a metering device 7, a drying channel 8, cutting means 9 and stacking means 11. The apparatus with which to carry out the method of the invention using a phenol-fo
REFERENCES:
patent: 1854192 (1932-04-01), Holcomb
patent: 2038607 (1936-04-01), Sauer
patent: 2665221 (1954-01-01), Grangaard
patent: 4397909 (1983-08-01), Goddard et al.
patent: 4588615 (1986-05-01), Otty
Database WPIL, Section Ch, Week 8325, Derwent Publications, Ltd., London, GB; Class A, AN 83-59678K & JP, A, 58 078 724 (Tokyo Shibabura Elec. Ltd.) 12 May 1983.
Patent Abstracts of Japan, vol. 8, No. 146 (M-307) 7 Jul. 1984 & JP, A, 50 042 923 (Matsushita Denko KK) 9 Mar. 1984.
Database WPIL, Section Ch, Week 8641, Derwent Publications, Ltd., London, GB; Class A, AN 86-267347 & JP, A, 61 192 740 (Shin Kobe Elec. Mach.) 27 Aug. 1986.
Database WPIL, Section Ch, Week 8951, Derwent Publications, Ltd., London, GB; Class A, AN 89-375599 & JP, A, 1 283 141 (Aika Kogyo Co., Ltd.) 17 Nov. 1989.
Isovolta Osterreichische Isolierstoffwerke Aktiengesellschaft
Owens Terry J.
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