US2126818A

US2126818A - Gas-retaining fabric

Info

Publication number: US2126818A
Application number: US97448A
Authority: US
Inventors: Theron P Sager; David F Houston
Original assignee: Individual
Current assignee: Individual
Priority date: 1936-08-22
Filing date: 1936-08-22
Publication date: 1938-08-16
Anticipated expiration: 1955-08-16

Description

Patented Aug. 1 6,

PATENT OFFICE GAS-RETAININ G FABRIC Theron P. Sager and David F. Houston, Washington, D. C.

No Drawing. Application August 22, 1936.

Serial No. 97,448

2 Claims.

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) This invention relates to the treatment of fabrics employed for the retention of lifting gases in lighter-than-air craft, and it particularly relates to the provision of a gas impermeable coating for such fabrics.

One object of the invention is to provide a coating material which may be readily applied by calendering, brushing, spraying, or spreading.

Another object is to provide a coating which shall be highly flexible and durable under varying conditions of atmospheric exposure.

It is customaryin the construction of gas-retainlng fabrics to apply a film or coatingto the surface of-the fabric which will prevent the dif-' fusion of the enclosed'gases. Rubberized fabric has been employed as a gas-retaining medium. Rubberized fabric is relatively. inexpensive and easily manufactured,. but a film of rubber is inherently permeable to gases and the use of 'rubberized fabric in the construction of gas cells results in a high loss of lifting gases. varnishes, lacquers, and dopes having cellulose derivatives as their basic" materials. have been suggested as gas retaining films. Those which have been proposed have not, however, been wholly satisfactory, either because of their high rate of diffusion to gases or because they tend to crack on flexing v of the coated fabric. Another class of materials which is employed as coatings for gas-retaining fabrics includes substancesrsuch as goldbeaters skin,. gelatin, and regenerated cellulose. These materials, while highly impermeable to lifting gases, all have a fault in common in that they are maintained in a flexible condition by the pres- .:.5 ence of glycerol or'slmilar hygroscopic plasticizer.

The presence of a hygroscopic plasticizer causes a wide variation in the weight of thecoated fabric under varying conditions of atmospheric humidity. A further objection' to the use of these materials is that they are readily subject to attack by mold and bacteria.

This invention 'consists in the discovery that films containing an oleflne-polysulphlde reaction product are highly impermeable to hydrogen and 4 5 helium, and in addition the foregoing disadvantages-of gas-retaining fabrics formerly proposed may be overcome by employing as a coating on such fabrics an oleilne-polysulphide reaction product. A fabric thus coated possesses the char- .30 acteristlc flexibility of rubber but differs from rubber in having a low permeability to'llfting gases. The term oleflne-polysulphide reaction product relates, to a plastic material obtained by the interaction of alkaline or alkaline earth poly-.

- sulphides and organic compounds containing methylene or substituted methylene groups, and

particularly to additive halogen derivatives of such compounds. Such a material may be appliedto a fabric by any of the .customarily'employed methods. In the form of a plastic mass it may be calendered. Dispersedin a suitable solvent it may be sprayed, brushed, .or spread with a spreading machine. The material may be employed ,as an impermeable coating unmixed with any-other material and not subjected to any heat treatment; To. obtain, however, the.

most satisfactory physical characteristics it has been found desirable to compound it with varying amounts of rubber, pigments, accelerators, and vulcanizing agents. Likewise, it has been found desirable to cure the coated fabric at ele;- vated temperatures to obtain the most satisfactory strength and flexibility. A fabric coated with an olefine-polysulphide reaction product is remarkably resistant to water and organic sol- I ven'ts, notably the hydrocarbons. It has also been found to be highly impermeable to hydrogen and helium.

In the following examples illustrative of our invention the olefl'ne-polysulphide reaction product referred to therein was of a grade known as "Thiokol 13, prepared by the Thiokol' Corporation, Yardville, New Jersey. The scope of this inventionlis not, however, limited to this particular grade of material.

Example 1 One hundred gramsof olefine-polysulphide reaction product was dissolved in 1000' grams of carbon disulphide and applied to a closely woven balloon fabric by brushing. The balloon fabric weighed 2 ounces per square yard. The coating was dried at 125 F. until all residual solvent was driven off. The coated fabric weighed 5.7 ounces per square'yard and gave a diffusion rate of 0.5 liter, per square meter per 24 hours.

Example 2 A material serving as another example was composed as follows inparts by weight:

Oleflne polysulphide reaction product--- Zinc oxide 10 Tetramethylthiuram disulphide 0.2

then applied to a closely woven balloon fabric by brushing on a plurality of coats. The coated fabric was cured in a drum in open steam for 60 minutes at 264 F.

The cured fabric, which weighed 5,6 ouncesper square yard, gave a diffusion rate of 0.4 liter per square meter per 24 hours.

Example 3 A mixture composed in parts by weight of the following was prepared:

Olefine-polysulphide reaction product 100 Smoked sheet rubber 10 Zinc oxide 10 Carbon black 20 Tetramethylthiuram disulphide 0.25

Example 4 This example illustrates the adaptation of our invention to a variation of coated fabric construction. To a closely woven balloon fabric was applied the following in parts by weight:

Smoked sheet rubber 100 Zinc oxide 10 Stearic acid 1 Sulphur 0.6 Tetramethylthiuram disulphide 0.25 Mercaptobenzothiazole 1 Benzol 3600 The solution was applied to the fabric with a spreading machine to the amount, upon evaporation of the solvent, of 0.6 ounce per square yard.

To the preponderan-tly rubberized surface of this fabric was then applied a material composed in parts by weight of the-following:

Oleflne-poly sulphide reaction product--- 100 Smoked sheet rubber"; 50 Zinc oxide 10 Tetramethylthiuram disulphide 0.25 Beta trichlorethane 1800 The solution was applied with a spreading ma.- chlne. The amount of coating applied was 0.8 ounce per square yard.

To this coated surface was then applied the following mixture in parts by weight:

Oieflne-polysulphlde reaction product 100 Zinc oxide 10 Tetramethylthiuram disulphide 0.1

Beta trichlorethane 1100 The amount of coating deposited from this mix- The mixture was then dispersed ture was 2.6 ounces per square yard. The coated fabric was then heated in dry heat for 60 minutes at 264 F. In this method of construction the intermediate coating serves as an adhesive layer by which the outer coating of olefine-polysulphide reaction product is attached to the rubberized fabric.

In the foregoing examples the functions of the various compounding ingredients are as follows:

Rubber is added to improve the tensile strength of the compounded material. Zinc oxide is an important ingredient which materially assists in altering the properties of the olefine-polysulphide reaction product during the final heat treatment with the result that the material is rendered more resilient and resistant to abrasive action. Carbon black increases the toughness of the mixture. Tetramethylthiuram disulphide, mercaptobenzothiazole, sulphur and stearic acid improve the properties of the compounded material by assisting the curing of the rubber and theolefine-polysulphide reaction product.

The foregoing examples are given merely for purposes of illustration. Numerous modifications are possible and will be apparent.

Other modifications and changes in the proportions and arrangements of the parts may be made by those skilled in the art without departing from the nature and scope of the invention, as defined in the appendedclaims.

' The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

Having thus set forth and disclosed the nature of this invention, what we claim is:

1. The method of providing a balloon fabric impermeable to lifting gases which comprises applying a gas impervious continuous film to a closely woven balloon fabric weighing approximately two ounces per square yard, the fabric being first rubberized before the continuous film is applied, the continuous film including a coating composition comprising an olefine-polysulphide reaction product and rubber, the oleflne-poly-,

sulphide reaction product being the basic ingredient of the composition and providing the impermeability factor to the fabric, whereby the completed impermeable balloon fabric has its weight increased from two and four-fifths to three times its original weight.

2. A balloon fabric impermeable to lifting gases comprising a closely woven fabric weighing approximately two ounces per square yard, a rubberized coating on said fabric and a continuous gas impervious film on said rubberized fabric, said film comprising an oleiine-polysulphide reaction product and rubber, the oleflne-polysulphide product being the basic ingredient of the composition and providing the impermeability factor to the completed fabric, the completed fabric weighing from two and four-fifths to three times the weight ofthe original fabric. I

THERON P. SAGER. DAVID F. HOUSTON.