US 1626276 A
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Description (OCR text may contain errors)
Patented Apr..2 6, I927.
'UNHTED STATS PTENT" OFFICE.
GUSTAVUS J. ESSELEN, JR., F SWAMPSCOTT, MASSACHUSETTS.
PROTECTING COVERING FOR RUBBER SHEETS.
Application filed March 29, 1924. Serial No. 702,771.
' keep the sheets from sticking together. The
' usual material used for this purpose is the so called holland made from a strong cotton fabric which is provided with a smooth glaze. This fabric is smooth enough sothat it .can be stripped from the sticky surface of unvulcanized rubber and is strong enough so as not to readily tear when stripped off. The material, however, is expensive. Ihave discovered that the paper known to the trade as glassine paper may be employed as a satisfactory and inexpensive substitute for the fabric holland as a protecting coating for sheet rubber. This glassine paper is a stock product and can be easily obtained and may be used without special treatment. This paper is mechanically tough, it has a highly glazed Surface which permits it to be readily stripped from the surface of unvulcanized rubber, and has a homogeneous substantially transparent body through which the surface of the rubber is visible for inspection. Glassine paper ismade from cellulose pulp which has been mechanically hydrated. It is made by a wet milling process in which the cellulose fibers are subjected to crushing andrubbing in the presence of water. This mechanical action is carried to a point where the cellulose fibers are reduced to a hydrated pulp, from which the glassine paper is made. The sheet' "formed from the hydrated cellulose pulp is passed in a moist condition between highly polished heater calender rolls under pressure in order to give it a smooth highly glazed surface. The term glassine paper is ordinarily employed in the trade to describe a paper havin a glass-like or glazed surface and made rom mechanically hy-- drated cellulose pulp, as distinguished from chemically parchmentized papers. Paper is ordinarily chemically parchmentized by passing a sheet of the formed paper through a bath of sulphuric acid which superficially dissolves the surfaces of the sheet, leaving the fibers in the interior of the sheet subas a kraft paper.
stanti ally unaffected. This chemically parchmentized paper does not have the homogeneous substantially transparent body of glassinepaper. The chemical parchmentizing treatment does not produce a glazed surface like that of glassine paper, but on the contrary produces a characteristic uneven cockled surface which it is very difficult, if not impossible, to eliminate by calendering. Moreover, the chemical parchmentizing treatment leaves certain chemical residues in the paper, which, unless the greatest pains are taken to remove them, WOUlCl have a deleterious effect, in time, on
the paper-or on rubber in contact with the paper or on both. Suggestions have been made to employ chemically parchmentized paper as a liner for sheet rubber, but if so used it would require special calendering and softening treatment before it could be used at all, whereas glassine paper may be employed without such speclal treatment.
In Figures 1 and-2 of the drawings is illustrated the rubber sheet with the glassine paper protective coating applied thereto. In these drawings 1 indicates the rubber sheet and 2 the glassine paper protective coating.
While the glassine paper, if made'with a moderately heavy body, has suflicient strength to enable it to be stripped from the rubber, it may be combined with a backing of a stronger or heavier bodied paper, such employed in the paper trade to designate certain papers of special quality having unusually tough fiber, the word being adopted from the German word kraft whlch means strength. A compositeprot'ecting"sheet for rubber may be made from a 'backing of a heavier paper, such as a kraft paper, and a facing of glassine paper on one or both sides of the backing,and secured thereto by a flex ible adhesive such, for example, as a flexible glue made from animal glue glycerine'and water. I
In Figure 8 is illustrated diagrammatically the modification of the invention, and in which 1 indicates the rubber sheet, 2 the glassine paper and 3 the" backing of kraft paper. 7
While the preferred embodiment of the The term kraft paper is' present invention has been specifically de- I scribed it is to be understood that the invention is not limited to all of the details hereembodied within e e 05 of the following claims. ,4
I claim: I
1. The combination with a sheet of rubber, of a readily separable protecting sheet of smooth surfaced glassine paper, substantially as described.
2. The combination with a sheet of rubber, of a readily separable protecting sheet of paper made from mechanically hydrated cellulose pulp and having a smooth highly glazed surface which permits it to be readily stripped from the rubber, substantially as described.
3. The combination with a sheet of rubber,
of a readily separable protecting sheet of paper having a substantially transparent homogeneous body made from mechanically hydrated cellulose pulp and having a smooth highly glazed surface which permits itto be readily stripped from the rubber, substantially as described.
4. The combinationwith a sheet of rubber, of, a readily separable protecting sheet of paper formed from a hydrated cellulose pulp into a substantially transparent homogeneous sheetand calendered to give it a smooth highly glazed surfacewhich permits it to be readily stripped from the'rubber, said paper being employed Without chemical parchmentizing treatmentvor impregnation with softening agents, substantially as described.
5. The combination with a sheet of rubber,
cellulose pulp and having a highly glazed surface which permits it to be readily stripped from the rubber, and having a strengthening backing of a heavier tough fiberedpaper, substantially as described.
7. The combination with a sheet ofrubber,
of a readily separable protecting sheet of paper made from' mechanically hydrated cellulose pulpand having a highly glazed surface which permits it to be readily stripped from the rubber, and having -a strengthening backing of a tough fibered stronger paper secured thereto with a flexible adhesive, substantially as described.
8. The combination with a sheet of rubber,
of areadily separable protecting composite. sheet of paper formed of a strengthening paper backing, and a facing on both sides thereof composed of a highly glazed paper made from mechanically hydrated cellulose pulp, substantially as described.
In testimony whereof I have hereuto set my hand.
GUSTAVUS J ESSELEN, J R.