US1975286A - Process of manufacturing waterproof crepe-paper - Google Patents

Description

Patented Oct. 2, 1934 1,975,286 raooass or MANUFACTURING WATER.-

PROOF CREPE-PAPER Friedrich Moritz Otto Pinofi, London, England, assignor, by mesne assignments, to The Patent and Licensing Corporation, New York, N. Y., a corporation of Massachusetts No Drawing.

Application December 5, 1931,

4 Serial No. 579,347. In Germany December 10,

, 1930 2 Claims.

The invention relates to the manufacture of waterproof or water-impermeable crepe-paper with the aid of aqueous dispersions of asphalt, paraflin, wax or similar water-repellent sub-. stances.

Waterproof or water-impermeable crepe-pa' per has hitherto been manufactured by applying molten asphalt or the like to a sheet of paper and creping the paper on a roll by means of a scraper or doctor in contact with the roll. When the paper is made in this manner, it is neces-.

sary that the asphalt be heated or treated with solvents in order to bring it to an adhesive state. It is furthermore essential that the face of the paper to which the asphalt is applied be brought into contact with the creping roll in order to cause the paper to adhere thereto during the creping operation.

In the manufacture of crepe-paper comprising several layers, where asphalt or the like is placed between two adjacent layers in order to make the product impermeable to water, the paper obtained according to the known process is indeed creped on both sides. However, all the cavities between the two layers of paper are necessarily filled with asphalt and consequently an extremely large quantity of asphalt or the like substance is required. The asphalted crepe-papers thus produced no longer constitute crepepapers proper, since they cannot be pulled out, which is an essential property of crepe-paper. Moreover they have the drawback of being extremely susceptible to changes in temperature on account of their high content of asphalt or the like, whilst, moreover, they cannnot be produced in thin sheets. As a result these products have no practical importance.

It has now been found that these drawbacks,

viz. the necessity of bringing the water-repellent material, while hot, into contact with the creping roll, the consumption of considerable quantitles of water-repellent substance and the reduced elasticity of such creped papers, canbe avoided by using the water-repellent substance in the form of an aqueous dispersion during the creping process. In the products thus obtained the layer of water-repellent substance is of a uniform thickness throughout and the shape of this layer is practically the same as that of the oreped paper.

In general the creping is done by bringing the paper, while adhering to a roll, into contact with a scraper or doctor, whereby it is crinkled and folded. For this purpose it is necessary that the paper sticks to the roll, as otherwise the crinkling action does not take place. In order to effect such adhesion the creping may preferably be carried out on wet paper, and therefore a new and technically important effect of the use of the water-repellent substance in dispersed form consists in that the water of the dispersion serves for bringing the required moisture into the paper. When providing either a finished, previously dried paper web, or a semifinished, not or incompletely dried paper web, with an aqueous dispersion of water-repellent substance the paper absorbs the water of .the aqueous dispersion at the moment of its being brought into contact with the dispersion and 'is thereby capable of being pressed onto the creping roll with such adhesiveness as is required for the subsequent .crinkling and folding bymeans of the scraper. In principle it is then immaterial which side of the paper provided with an aqueous dispersion of water-repellent substance is brought into contact with the creping roll,

since, owing to the absorption of water from the dispersion, the side not carrying the dispersion as well as the other side is adhesive to the roll.

The manufacture of waterproof or water-impermeable crepe-paper according to the inven tion is subject to several variations.

Thus, for example, a semi-finished, not or incompletely dried paper web can be provided, while being on the paper making machinery, on one side or, if desired, on bothsides with the dis persed waterrepellent substance and thereupon creped in the usualway, without previous desiccation or after incomplete desiccation. I

In a similar way the creping can be performed on paper comprising several layers with waterrepellent substance in between. An aqueous dispersion of water-repellent substance is then applied between the semi-finished, wet paper layers which are then united to a compact paper web, which without previous desiccation or after an incomplete desiccation, is subjected'to the creping treatment in a wet condition. In place of semi-finished paper layers it is also possible to produce crepe-paper comprising several layers by using webs of finished paper, between which the aqueous dispersion of water-repellent substance is applied. The webs of paper then absorb the water from the dispersion, and are united by pressure to a single web with the water-repellent substance between the layers, this product being subsequently, either without previous drying 'or after partial drying, subjected in a wet condition to the crepingtreatment.

According to the invention the creping can also .be performed on ordinary, previously desiccated paper webs, after the latter being treated in some way or other as described above with an aqueous dispersion of water-repellent substance. In such cases the paper is sufficiently moistened by the water ofthe dispersion applied on one side or on both sides of the paper, or-between the instances, being creped in the usual manner before desiccation or after partial desiccation.

When working up dispersions of asphalt or similar water-repellent substances according to the invention, it is preferable to use those dispersions which coagulate only after extraction of the water, as is the case, for example, with the dispersions of bituminous substances pro duced with clay as a dispersing-agent.

The waterproof or water-impermeable crepepapers produced according to the invention have wide application. They are particularly suitable for the manufacture of elastic and waterproof paper bags, for use as waterproof and elastic packing-material and for decoration purposes. In the latter case they can be provided in the usual way with patterns, or dyed, which can be suitably done before the creping.

I claim as my invention:

1. A process of manufacturing waterproof crepe-paper comprising incorporating an aqueous bituminous emulsion with fibrous pulp, forming the mixture into a sheet and subjecting the sheet to a creping operation while in a moist condition, and subsequently drying the creped sheet to effect coalescence of the emulsion.

2. A process of manufacturing waterproof crepe-paper which comprises creping a web of fibrous material while in moist condition before it has been completely dried on the paper machine and carrying aqueous bituminous emulsion, and subsequently drying the creped web to effect coalescence of the emulsion.

FRIEDRICH MORJTZ O'I'I'O PINOFF.