US2721816A

US2721816A - Asphalt-impregnated kraft paper panel board

Info

Publication number: US2721816A
Application number: US325340A
Authority: US
Inventors: Robert H Wood
Original assignee: Simplex Paper Corp
Current assignee: Simplex Paper Corp
Priority date: 1952-12-11
Filing date: 1952-12-11
Publication date: 1955-10-25
Anticipated expiration: 1972-10-25

Description

Oct. 25, 1955 R. H. WOOD 2,

ASPHALT-IMPREGNATED KRAFT PAPER PANEL BOARD I Filed Dec. 11, 1952 lj iolmm H Wood B ably sized and preferably hard sized.

United States Patent Ofiice 2,72 1,8 16 Patented Oct. 25, 1955 ASPHALT-IMPREGNATED KRAFT PAPER PANEL I BOARD This invention relates to waterproof asphalt-impregnated multiply kraft paper boards.

Panel boards of this character have been used quite extensively in the automobile industry and one important use has been on the inner side of the body providing a surface to which the fabric upholstery material is attached. The panel board heretofore in use for this purpose has not been entirely satisfactory for two principal reasons. In the first place, it has an exterior surface of outwardly protruding fibers, which rub off on the workmans hands. The asphaltic impregnated fibers are such as to come off on the workmans hands, which soil the upholstery when the latter is applied to the panel or in mounting the upholstered panel in the automobile body. In the second place, it is desired to sew the upholstery fabric to the panel, but this has not been satisfactorily accomplished because during the sewing operation, the needle picks up some of the asphalt impregnant and then soils the fabric. The expense of cleaning the fabric soiled in this way has been considerable.

It is a desideratum to overcome these difficulties and objections and to produce a new and improved panel board, which has the desirable qualities of the waterproof asphalt board heretofore in use and additionally, can be handled and sewed satisfactorily without soiling the hands of the operator, the sewing needle, and of greatest importance, the upholstery itself.

Other objects of the invention will hereinafter appear, and for the purpose of illustration but not of limitation, an embodiment of the invention is shown on the accompanying drawings, in which Figure l is an enlarged top perspective view partly in section, of a panel board;

Figure 1A is an enlarged portion of Figure 1, and

Figure 2 is an enlarged top perspective view of the board showing a portion of each individual ply folded back upon itself for purposes of clarity.

The illustrated embodiment of the invention comprises a panel board P which has great strength, rigidity, is water-resistant, and not appreciably afiected by changes in temperature and humidity, and is of a multiply asphaltimpregnated kraft paper structure. As shown, the board is made up of three plies a, b and 0, although the number of plies may be increased as desired. Each of the plies consists of a sheet of kraft paper of suitable thickness, as for example .016 inch, produced from sulphate pulp having cellulose fibers in a single layer extending approximately equally in all directions. Preferably, the cellulose fibers are continuous and relatively long.

In order to render the sheet water-resistant, it is suit- It should be understood that the exposed surfaces of the plies a and c are smooth and hard, obtained in any suitable manner as by calendering, whereas the inner or unexposed surfaces have outwardly protruding fibers. In other words, the two exposed surfaces of the panel board P are smooth and hard with no protruding fibers, whereas the unexposed surfaces of the plies have protruding fibers. These protruding fibers cooperate with an adhesive for bonding the several plies together. The adhesive is placed between the several plies and is absorbed by the board, the greatly enlarged section of Figure 1 showing how the adhesive absorbs into the board, following the fibers by capillary action for effecting an efiicient and satisfactory bond. A satisfactory adhesive for this purpose may be a mixture of latex and starch paste, the latter containing Water as a solvent, although other adhesives may be satisfactory. It will further be understood that the panel board is preferably subjected to some pressure to hold the plies together until the adhesive has had sufi'icient time to set.

Prior to the assembly of the sheets in superposed relation, each sheet is impregnated either completely or partially on the two sides with asphalt. I have found that asphalt applied at a temperature of approximately 450 F. aifords satisfactory penetration of the asphalt into the kraft paper sheet. I desire that the asphalt upon cooling be exceedingly hard and brittle, so that it preferably should have a melting point of approximately 180 F. and a penetration point of from zero to one. Such penetration point is determined by the standard method of test for the penetration of bituminous materials as devised by the American Society for Testing Materials, and is a test well-known to those skilled in this art. According to this test, the result (1) would be expressed in a degree, such degree being equivalent to .01 of a centimeter, which a standard needle will vertically penetrate a sample of the material in five seconds under a load of one hundred grams, the material being at a temperature of 77 F.

With an asphalt impregnated kraft paper sheet having a penetration point of zero to one, a needle penetrating the panel board for the purpose, for example, of sewing fabric upholstery material to the board, will actually punch out a hole through the material because of the brittleness of the asphalt. This militates against any of the asphalt adhering to the needle and thereby soiling the upholstery fabric during the sewing operation. In this manner, one of the objectionable features inherent in panel board of this type heretofore in use, is clearly obviated, and it is found empirically that a panel board of this structure with the asphalt impregnation of such a penetration point, can be sewed without difliculty, and does not have the objectionable soiling or damaging characteristics so far as the fabric upholstery material is concerned. With an asphaltic impregnant of the brittleness as above specified, the thread employed in the sewing operation is not stained and by maintaining a clean thread during the sewing of the upholstery material to the panel board, the desired cleanliness of the upholstery is maintained.

The elimination of the protruding fibers from the exposed fiat surfaces of the panel board is a definite advantage in that it prevents staining of the hands of the workmen and the consequent dirtying of the upholstery material. The smooth, hard finish on these surfaces, which may be achieved by the use of calendering rolls, dispenses with the fuzziness with its attendant objections. In order to secure the plies to each other, the inner surfaces of the outer plies have the protruding fibers which cooperate with the protruding fibers on both surfaces of the intermediate ply, to secure these plies properly together.

It is to be understood that numerous changes in details of construction, arrangement and operation may be effected without departing from the spirit of the invention, especially as defined in the appended claim.

What I claim is:

A panel board comprising a plurality of superposed sheets, each sheet being resistant to physical change in a wide range of temperature and humidity conditions and being composed of sized fiber pulp consisting of a singly formed layer of fibers of cellulose disposed substantially uniformly in all directions, each sheet being impregnated with asphalt having a melting point of the order of 180 F. and a penetration point not exceeding 1, the exposed surfaces of the outermost sheets being smooth with the fibers thereof lying within the plane thereof, the surfaces of the sheets between said exposed surfaces having protruding fibers, and an adhesive extending into the body of the sheets through the protruding fibers and conjoining adjacent sheets, said melting and penetration point characteristics of the impregnating asphalt providing brittleness whereby a sewing needle passing through the 4 panel board punches out a hole therethrough, and adherence of the asphalt to the needle and to thread employed therewith is precluded.

References Cited in the file of this patent UNITED STATES PATENTS 1,694,523 White Dec. 11, 1928 2,073,894 Wood Mar. 16, 1937 2,278,146 Moeller Mar. 31, 1942 2,299,144 Heritage et al. Oct. 20, 1942 2,448,357 Craig et al. Aug. 31, 1948