US2055450A - Waterproof fabric and production thereof - Google Patents

Description

22 H ER El AL u S p l L. BEND H ERxhOr e t l PROOF FABRIC AND PRODUCTION TH WATER Filed sept. 12, 1931 3 nncntor RHMIEJENMUJ. 515191 HDD Lamm.

.maa sept. 22, 1936 Frio WATERPROOF FABRIC l. THEBEF l- PRODUCTION Howard L. Bender, Bloomfield, and Frank I. Bennett, Jr., Highland lark, N. J., assignors to Johnson & Johnson, New Brunswick, N. J., a corporation of New clersey filaires.

The invention relates to waterproof fabrics and to the production thereof and more particularly to fabrics whether interstitial or otherwise. such as woven or other textile fabric and 5 fabrics of the nature of paper, which inherently or of themselves are not waterproof and require treatment to make them so; and it provides a Waterproof fabric possessed of certain definite,

distinctive, and novel characteristics whereby it' is susceptible of manifold uses and applications in the industrial arts and sciences.

The waterproof properties of. liquid coating compositions such as reaction condensation products having resin characteristics are well known and prior to this invention it has been proposed to make fabrics waterproof by treating them with reactive resinous materials. The liquid coating composition was applied generally by dipping or by spraying and the result was more or less satisfactory where relatively heavy gage or non-uniformity of thickness of the coatling was of no moment and where stiffness -or tackiness, either manifest or eventual, were not problems.

Attempts to perfect the practice by resort to calendering failed because none of the known materials would lend themselves to known methods of calendering; and so it is that, although the literature fairly abounds with suggestions and examples of resinoid coated cloths or other fabrics, the information has no practical value and the results are abortive in the sense that a careful following out of the specications'and mode of procedure simply results in a stiff composite fabric leaving much to be desired in stability and general appearance;

The nature .of the invention resides in the method, and in the product of that'method. which in one aspect consists in the selection and treatment of a reactive resin composition to condition it for successful application by calendering or otherwise, and in another aspect consists in the method of calendering, or in short, coordinating 'the factors of proper coatingmateriai and proper application of that material, for the ultimate purpose and result of producing a waterproof fabric. characterized by its marked exibility, uniformity of gage or thickness, and by its stability and freedom from tackiness over long periods of time regardless of exposure to dinerent temperature conditions.

e invention will be described in connection with the accompanying drawing, forming a part.

5- hereof, wherein Application September l2, 1931, Serial No. 562,588

(Cl. ill-68) Figure 1 is a layout of apparatus suitable for practicing the invention.

Figs. 2 and 3 are plan and sectional views, respectively, of the new fabric; and

Fig. 4 is a sectional view of fabric coated on 5 both sides, either with reactive resin composition, or with one facing of such composition andwith the other facing of, for example, the conventional rubber adhesive mass or compound.

The coating material In the practice of the invention considerable care and caution should be exercised in preparing the proper coating material and in properly treating the same so that it readily will lend 15 itself to successful application, such as successful calendering, which includes proper filming and freedom from pin holes. The starting ma.- terial may be such complex compounds formed by reacting fatty oils and fatty acids containing at least one unsaturated bond per molecule with mono phenols, diphenols or polyphenols as phenol, xylenol, resorcinol, etc. in presence of socalled converting agents for instance, metallic salts such as iron chloride, acids such as phosphoric acid or sulphuric acid, organic acids such as oxalic acid, natural resins such as rosin and organicliquids as triethyl citrate. These complex compounds act like highly substituted phenolic compounds in that they dissolve in alkaline solutions under proper conditions which vary for each individual compound. However, they all dissolve in vsaturated sodium hydroxide ethyl alcohol solutions to give sodium salts which can be converted back to the original complex oil-phenol compound by acidification. The cornplex oil-phenol compounds and fatty acid phenol compounds also are alike in that they all react with aldehydes, such as formaldehyde, benzaldehyde, furfuraldehyde or salicyldehyde or even in such weak aldehydic compounds as some starches and sugars, to form resins. The complex oil-phenol compounds may be mixed with any other phenol and the mixture made into a resinous complex by reacting with aldehydes. These products are soluble in fatty oils so that free fatty oils may be mixed therewith and the mixture made by reaction with aldehydes, or hardening agents. into resinous complexes modined by free oil.

Excellent results have been achieved with a resinous material consisting of parts phenol, parts tung oil, two parts phosphoric acid, which material, in substantially the proportions stated. is reuxed for two hours at about to 55 190 C. more or less. After cooling there is added to it 20 parts, more or less, hexamethylenetetramine, and the mass is thenreacted for one hour at C. or to a viscosity of 200 k. v., when a sample is dissolved in an equal weight of toluene. The product when run through a filter press is a soft, sticky, semi-iuid mass having an odor strongly suggestive of ammonia.

Milling The reactive product just described, when in the form of a thick viscous varnish will penetrate into fibrous structures and modify their flexibility; on the other hand, when set to a thin jell it no longer penetrates but swells in solvents to give a dry surfaced jelled mass, resembling gelatins in water, which is diflicult to knife spread. And, if sucient solvent combination is used to break the jell structure, the mixture is very dilute and sticky.

The product in this state is unsuitable for calender-coating because, obviously, it is fugitive in the sense that it has a tendency to now promlscuously due to the presence of solvents and volatiles and the character and -extent of its penetration cannot be controlled. However, we have discovered that by a certain and definite treatment we are able to obtain wholly unexpected and remarkable results in phase characteristlcs and to obtain an end product which can be frictioned to a degree Where it can be calendercoated in the form of flexible, thin, coherent sheets or films which are substantially confined to the surface of the fabric. By substantially confined to the surface we mean that although the new coating material may and does to a certain extent penetrate into major interstices or voids of the fabric for anchorage purposes it does not penetrate to any -substantial extent into minute interflbrous spaces such as ybetween the bers of the threads or between adjacent bers at the crossing of the threads of wovenfabrics.

According to the conditioning step of our invention, a batch of flexible resinoid material together with from eight to twenty per cent of its weight of filler is worked down, for example, in a suitable mill 5, 'the rolls of which are heated to about 180 F. The filler may be either of the inert or of the reactive type. Examples of the former are Whiting, corn starch, barytes, wood our, powdered asbestos, and the like inert materials, either alone or in various combinations. Examples of the reactive llers are zinc oxide, magnesium oxide, lead oxide, aluminum oxide, etc. It is preferred to use the so-called reactive type of filler and, for example, zinc oxide. In fact, we have discovered that the use of a reactive filler has far reaching consequences and makes for a decided advance in the art. The reactive filler eventually combines chemically with either the excess oils in the resin or with the uncombined phenol to form complex organic compounds which might be called phenolates.

It is preferred to use the so-called reactive type of filler and, for example, zinc oxide. The reactive ller eventually combines chemically with either the excess oils in the resin or with the uncombined phenol to form complex organic compound.e which might be called phenolates. It has been found that when an ordinary phenol formaldehyde resin is mechanically worked down, as by kneading or milling, with a filler such as zinc oxide, in the presence of heat, until it is more thoroughly combined than it would be in the varnish state, the zinc oxide does not operate to form a harder rubbery mass but is simply dispersed throughout the spongy resinous material the same as any other ller.

The phenol-oil-formaidehyde product should not be allowed to have reached too advanced a state of polymerization before mixing it with the reactive filler because otherwise the oil, phenol and aldehyde may become so combined that no unsaturated bonds remain to hook up with the zinc oxide.

The so-called hot mill is operated for about twenty minutes, whereupon the batch is transferred for further and immediate working to the rolls of a so-called cold mill 6, that is to say, a mill operated at about room temperature. The second milling is continued, likewise, for about twenty minutes, or until the material is free from air or gas inclusions and otherwise manifests readiness for calendering.

Hot milling affects both the chemical and physical state of the resinoid in that the resinoid action is slightly advanced on the hot rolls, and the physical condition is such that the resinoid is smooth and has the proper consistency (allowing for the cold rolling) to be calendered onto the cloth. If the resinoid were merely removed from the hot rollsv and permitted to stand, the hardening action would possibly proceed to a point wherefthe resinoid would be useless. Therefore, the plastic resinoid mass is removed from the hot rolls and Worked on the cold rolls. The cold rolls increase the homogeneity of the resinoid and also stop the chemical hardening action or polymerization of the resinoid so that the mass can be' stored until desired for calendering, without chemical hardening.

In using the hot and cold rolls, the mass is merely worked on the hot rolls as above indicated. Then a hot sheet is taken off of the hot rolls and fed by hand or by gravity or other means to the cold rolls where it is further worked and cooled to room temperature. A mass of the unformed amorphous material from the cold rolls is then friction calendered on to a base, such as cloth.

Calendering Successful calendering depends largely upon temperature conditions which vary somewhat for each rubbery resinoid so used. Acccordingly, for the above example, the top roll of the calender 1 is heated to about F., the bottom roll to about F., the middle roll being maintained at room temperature or from iive to ten degrees above it. When the top roll is below 120 F., the material does not sheet well and when it is above that temperature the lm presents pin holes, probably due to air or gas inclusions or to a tendency of the material to adhere to the roll. Experiments were tried with the middle roll at less than room temperature and it was found that moisture condensation from the air and from the'cioth or other fabric in contact with the hot bottom roll seriously affected the binding of the mass to the cloth. The bottom roll is kept at a higher heat than the middle roll because it was found, that with both at the same temperature, the material had a, tendency to transfer to the bottoni rou in the space beyond the edges of the cloth. It further developed that moisture in the cloth or other fabric operated detrimentally against uni- .formity of adhesion of the coating. If only traces of moisture are present, they are removed by the heat of the bottom roll, otherwise thorough dryness of the fabric may be insured by resorting to conventional drying facilities.

Curing The coated fabric when it leaves the calender is not very tacky and may be rolled upon itself on a regular mill roll. In the above example, in this' state. it is not stable for the various commercial ypurposes for which it is intended. Hence, in

order to promote further polymerization, to remove any vestige of tackiness, and to insure a vso hard enamel surface finish characterized by its uniformity of gage, its smoothness, its resistance to abrasion and its flexibility which for all practical purposes is that of the foundation fabric, the coated material is subjected to heat treatment, as by passing it through a heater. It may here be remarked that, for some resinoid mixtures and for certain uses, heating beyond the calender stage is not necessary.

The product It is characteristic of the new product that the cohesion or binding action between the foundation` fabric and the coating is of such nature that, as graphically shown in Fig. 3, there is controlled penetration into the interstices or voids of the foundation fabric, generally just sufcient` such as that employed with surgical tape or plaster, in case the material is to be employed as a tape or plaster or-for industrial applications requiring adhesion.

The double coated or double faced fabric is shown in Fig. 4 in which 9 is the waterproof coating and l is the other coating whatever it may be. And it may be any suitable coating, without regard to contained solvents, in that it is a further merit of the improved resinoid coating that it is substantially indestructible when wetted with orotherwise exposed to chemicals such as encountered daily in the arts, trades and professions; and equally important it is compatible with the conventional rubber adhesive mass such as employed in the manufacture of surgical tapes. in this connection it here may be remarked that the impregnated tape of our invention is distinguished from known products in this, that the not adhere in another condition, that is to say, the adhesive will adhere to the phenolic resinoid before either the one or the other is cured but will not adhere after curing and so the finished tape can be rolled upon itself or stacked.

Having described the invention, what is claimed 1. The new fabric embodying porous foundation material and a erible calendered coat comprising the reaction product of an oil soluble phenol-oil-aldehyde resinous complex and a substance adapted to render it into a plastic rubberlike mass whereby the coat is manifested as a thin coherent lm substantially confined tothe surface to which it is applied;

2. The new fabric embodying sheeted porous foundation material and a flexible heat cured calendered coat covering an area thereof and comprising the reaction product of an oil soluble phenol-oil-aldehyde resinous complex and a substance adapted to render it into a plastic rubberlike mass whereby the coat is manifested as a thin coherent lm substantially confined to the surface of the area to which it is applied.

3. The new fabric embodying flexible sheeted porous foundation material and a iiexible heat cured calendered coat covering an area of one side thereof and comprising the reaction product of an oil soluble phenol-oil-aldehyde resinous complex and a substance adapted to render it into a plastic rubber-like mass whereby the coat is manifested as a thin coherent film substantially conned to the surface to which it is applied, and another coat of material compatible with the calendered coat and covering an area of the opposite side of the fabric.

4. Woven fabric having as an integral part thereof a water,l heat and chemical resisting calendered coat which does not appreciably impair the inherent flexibility of the fabric, said coat comprising the reaction product of an oil soluble phenol-oil-a.ldehyde resinous complex and a substance adapted to render it into a plastic rubber-like mass whereby the coat is manifested as a thin coherent lm substantially conned to the surface of the fabric.

5. IThe new fabric embodying porous foundation material and a flexible calendered coat comprising the heat hardened reaction product of an

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