US2668787A - Method of making a bonded permeable article - Google Patents

Description

1954 A. F. SCHRAMM, JR

METHOD OF MAKING A BONDED PERMEABLE ARTICLE Filed Jan. 9, 1951 2 Sheets-Sheet'l IITTOIP/VE'Y 1954 A. F. SCHRAMM; JR

METHOD OF MAKING A BONDED PERMEABLE ARTICLE Filed Jan. 9, 1951 2 Shei-Sheet 2 JTTOIP/VE) Patented Feb. 9, 1954 METHOD OF MAKING A BONDED PERMEABLE ARTICLE August F. Schramm, Jr., White Plains, N. Y.

Application January 9, 1951, Serial No. 205,087

6 Claims. 1

This invention relates to coated sheeting and the method of making it. The invention relates more particularly to the application of spaced particles of thermoplastic material to a textile fabric or the like, with simplification and shortening of the treatment required to produce an air and moisture permeable coating.

Interest has existed for a long time in the application of plastic coating material to fabrics, as in the making of material for shoes, collars, and other clothing that require breathing propperties permitting the passage of air and moisture through the coated sheet material. I have previously developed a method in which a fabric is wet through with water before the application of the plastic particles. The water decreases the penetration and diifusion of the particles during the subsequent warming step. The water serves in fact to prevent the passage of plastic particles through the cloth and thus preserves in one face of the fabric the original texture and appearance.

. When this pretreatment with water is used, it is necessary finally to subject the cloth containing the water and the applied particles to an elevated temperature for a period of time sulficiently long not only to soften the plastic particles but also to evaporate the considerable content of water in the fabric.

I have now discovered a method of eliminating the holding period required for the evaporatlon of the water in the previous method. I now confine the pretreating water to an extremely thin film over the face of the fabric to be coated.

. In this manner I prevent actual penetration of the water through the fabric. As a result, I decrease the water to be evaporated to about or so of the water required in my earlier method in which the water penetrated the fabric. I decrease correspondingly the time required for the subsequent drying in the heating step, the exact percentage decrease in the proportion of water and drying time varying with the thickness of the fabric treated. The percentage decrease in water content and subsequent drying time over the previous method is greater the thicker the fabric selected for the treatment.

1" directly in contact with the said film, and then,

warming the product until the water of the film is evaporated, until discontinuity develops in the film due to the evaporation, and finally until the thermoplastic particles are softened by the heat so that they become fluid and penetrate through the discontinuities of the now ruptured film into surface portions of the permeable sheet originally used, the term fluid meaning flowable as a liquicl or semi-liquid mass. In the preferred embodiment, the resulting coated sheet is subjected to a hot ironing step. This improves the anchorage of the thermoplastic particles in the face of the cloth and smooths or flattens somewhat the exposed surface of the particles.

The invention will be illustrated by description in connection with the attached drawings to which reference is made.

Fig. 1 is a perspective view of my product in the development or manufacturing stage with parts broken away for clearness of illustration.

Fig. 2 is a sectional view on line 2-2 of Fig. 1.

Fig. 3 is a sectional view of the product subsequent to the warming step.

Fig. 4 is a similar sectional view of the product after being subjected to pressure plates or rolls. I

Fig. 5 is a perspective view broken away for the purpose of illustration of a modification of the invention.

Fig. 6 is a sectional view of an assembly of parallel threads bonded. according to the invention.

Fig. 7 is a perspective view of a quilted form of my product.

The permeable sheet material selected for illustration is a Woven textile fabric 10 in Figs. 1-4, an assembly l8 of warp threads only in Figs. 5 and 6, and a felt 24 in Fig. 7. ,The applied aqueous film or gel is shown at l2 and at 20 and the thermoplastic particles at I4, 16, 22, and 26, the scale varying in the several drawings and the drawings being in part diagrammatic.

The discontinuous residue of the gel left after the evaporation of water is not shown as the residue is practically invisible.

The various elements of the structure are exaggerated in certain dimensions in the drawings, the extent of the magnification being particularly large in the case of the size. or spacing of the particles shown at M, I6, 22, and 26 and the thickness of the film l2.

The thermoplastic particles as used are about 20 to 200 mesh in average size.

The film I2 is so thin as to be invisible over the surface of the fabric except as wetness affects the appearance of the material. It is considered that on a reasonably finely woven fabric the film thickness of the wet gel shown at l2 will average not more than about .001 inch, the film increasing in average thickness with coarseness of the weave aifording low spots into which the gel may be forced by the method of application to be described.

The permeablesheet material selected for coating is one" that ishighly' absorbent and'suitably parallel threads, felt, or the like.

warp threads without any woof. Such anassembly of warp threads bonded by rny particles 24,

as shown in Fig. is suitable-for filibonfitock. The felt depressed at intervals 'as'at the ftigouglfis r;

mass of the particles is effected by warming and softening of the particles.

As the Water gel which is used to supply the film I2, I use water and any usual thickening agent for Water that is effective in extremely small proportions, such as /2% to 5% of the thickening agent on the weight of water, in giving a viscous semi-solid gel that maybe buttered onto a fabric butthatj is isojdii'ficpltly flowable as not to -penetrateand wet through the fabric. Examples of organic thickening agents that may be used are carboxymethyl cellulose, gelatinasodium alginate such as Kelco, and agarfagar.

Carboxyrnethyl cellulose is available in large "--i1uantities;'*is "ffctive for the purpose, and is 28, in the manner of quilting and bonded by: the n thermoplastic particles is particularly adapted'for use in snow suits and other forms of warm cloth- "The material ofthe thermoplastic particles is solid and freeifiowing. at roomttemperature, stable on "aging; without deteriorating effect" upon the organic fibers to whichit is to'be applied, and softenable to ilowable' (fluid) condition at'teniperatures withinsthe'range300 9to 400 F: but preferably not at temperatures as low as 212 F. The particles? may be pigmented or mixedtwith dyes in conventional manner to establish: the color desired.

Examples-of thermoplastic material that meets these general requirementsa'nd that may be used are vinyl chloride resinfanexample being a co' polymer of vinyl" chloride and 'vinylac'etatein the'pr'op'orti'on of about 95 parts ofithe former to 5 of the latter, polyvinylbutyral;cellulose ace tate,and methylmetiiacrylates" Included in 'the' "thermoplastic material is a plasticizer; if any is' reqi'iired toimparttherm'cplasticityjselect'ed from the 'plasti'cizers* employed commerciallyforthe p'articularplastic used The plasticizer selected is preferably one that'isboth non toxic undeflthe 'Cohditionsof useandl'stibstantially "-non' fiammable2"* "Examples of' such plasticizers that may be used are tributoxyethyl phosphate; "dimethoxyethyl phth'alatei 'andan alkylaryl phosphate;- as;for instaricerbutyl*cresyl phosphate (Santicizer 141), and tri'c'resyl phos phateT'When 'fthe plastic material is cellulose acetate, 1 preferte iis uie itliiiiethoxyeth'yl phthalate or one of the phosphates asa 'pla's :r --v .nr; ywwq'l-l- 2 "f, To promote free-flowing characteristics. insolid conditionbf 'thecoinbi'fiat'ion of plasticand plas ticizer' censtitiitmg together thef'thermoplastic material er the particles! MaIid I 3, I preferably include theplasticiz er in" the particles in"special fornig I preferto include' the plasticizer in latent plasticizing condition? Thus, "I" absorb the' plas ticizer in the minute macroscopically; invisible pores of the particlesl l withoutbeingdistributed therethrou'ghout"in'such' manner as to soften the entire'particle 'tda condition interfering with the free-flowing properties of-fth'e solid particles at room temperamres'sf This V conditionor itlie plasticizer is effected in accordance with technique nowknownJ-In this technique, thermoplastic particle's *are tumbleld under an "extremery nne spray of plasticizer in liquid condition; th e-p'las ticizer being so finely atomized" as w-e terphe' microscopic pores Within "the particlesdfl {""Ifis retained therein, in suifici enthuantity ultimately to plasticize Ithe particle'swhen subsequent distribution of the plasticizer throughouttneentire resistant to development of objectionable odor or appearance on long exposure to air containing moisture and common bacteria. For this reason, I prefer to use carboxymethyl cellulose. I find no advantageswhich offset the disadvantages of poor agingproperties in "some of the other thick: ening agents.

Dyes, pigments andv resin. stabilizers may; be used-Jinaccordance with usual manner; to. estab-r: lish thedesired color andto stabilize the. resin';::'"

As to proportions, Iuse such a. ratioaofwater to selected thickening agent, in "thegel of. film I 2, that the gelmay'be buttered'on Withaknifefor the; usual doctor-blade.;coating operatiomwithout flowing through the cloth; A suitable proportion is:.that which gives awviscosity equalttos thattof aboutfia 2% dispersion in water of? high .viscosity carboxymethyl cellulose such? as Hercules: Type '.r...-: l.... all Theplasticizer. is used inproportionsthatzare known, for each combination'offchosenplasticizer and plastic, torgivearcomposition that is soften able; to; :flowable fiuidrcondition't at temperatures,

within the range. 300?; to 5400:F;ibutrndt*ati a;.

In applying the gel of the thickening agentin mercialscale this is done: by drawing the fabric under 'a :ibank' of'tlie 'gel atsor'dinary tempfatiif andfin'advan'ce of afrdoctor blade set to rub at lower edge:- ag'ainst or approximatelyagainst the upper surface of the fabric; "Asthefabricpasses ins'conta'ct with-.-ithe'bank" 'of gel TI thereupbn arrd then 'under' 'the' doctor blade, the blade s i inio''otlis out the gel as "anf'i'rivisiblei film ""thatiwets con; tinuously the upper .facei'ofithefabric .ancltthe" upper face-only.r-"-

The; thermoplastic, particles are then applied over, the wet; film xof aqueousfigel... They are applied by sifting ior otherwise" placinga layer offparticles' upon the. wet film. Thejlayeifimay be continuous and: several particles deep. "The clothpis then reversedy-so that ytlieiapplied "particle's .arezbelow the face of thefabric and below the ifilm oi -gel. In this-xposition,*theifrbridis lightlyjtapped at close intervalsior blowniwi'th a mild air-stream; to 'rerno've'"tlioseofthe particles't'hatare 1 adhered'lightly at"leasjt'b 't wet fili'fn 15: gel? Because thewatr pres'erifinthe film is 111"21135 form of a very viscous gel, the water does not flow by capillarity or otherwise through the layer of particles in direct contact with the film. As a result there is no bonding to the film of those particles which are kept by other particles from direct contact with the film. The use of the Viscous film and the subsequent knocking off or blowing off operation remove the particles out of direct contact with the film and leave on the film a layer of single particle thickness. The particles in this layer define between them spaces somewhat larger than those required for breathing in the finished product.

The fabric with the wet film and spaced particles thereon is next subjected to the warming step. The fabric and applied materials are passed through a radiant heat oven of standard design. In this oven, radiant heat is reflected directly upon the surface of the fabric carrying the wet film and the thermoplastic particles. No mechanical part contacts the applied particles. The water is removed by an, evaporation at a speed that approaches flash evaporation, because only a very thin film of water is present.

An alternative form of heating for the fabric, wet film, and applied particles is dielectric heatmg.

When the water has been evaporated, then the additional radiant energy which is received raises the temperature to 300-400 F., the temperature of softening of the thermoplastic particles to a fiowable fluid condition.

During the evaporation step, the film 12 of gel becomes discontinuous. In fact it disappears. The thickening agent representing the residue from the drying of the gel, containing originally only 2% or so of the agent, either cracks or shrivels into small flakes so that there is discontinuity, that is, a large proportion of free space at close intervals through what was originally a continuous film of the gel.

To improve the anchorage of the thermoplastic particles after completing the heating operation described above, the product is suitably ironed. This may be done by passing the product through rollers at ironing temperature, as, for instance, when the product first issues from the warming step described. Under such circumstances, the thermoplastic material is forced by the pressure upon it to penetrate somewhat more than formerly within the fabric, with resultant better anchorage, and to assume leveled upper surfaces as shown at 16 in the drawings. When it is desired to impress a pattern on the thermoplastic particles, the rollers may be provided with the negative of the desired pattern. Also the rollers may be replaced by pressure plates of suitable surface smoothness or pattern, as desired.

The procedure of the method illustrated above is repeated with the substitution of paper or felt in sheet form for the fabric.

The treatment may be applied to both face and back of the sheet material, with plastic particles of the same or different colors.

The overall effect of my method is the prevention of penetration of water through the permeable sheet material in the initial treatment with the aqueous gel, the provision on the sheet of a wet film which adheres lightly the thermoplastic particles directly in contact with the film but which does not penetrate through or between the particles to those which are out of direct contact with the film, the development in the film of discontinuity by the drying operation, and anchorage of the thermoplastic particles in spaced relationship to each other. The final product, therefore, is one having a thermoplastic but permeable coating which permits the passage therethrough of water vapor and air.

A treated sheet with the particles applied as described may be used in effecting lamination. Thus a second sheet may be laid upon the treated surface with particles 22 and adhered thereto by pressure against the said particles in heat softened condition.

The invention will be further illustrated by description in connection with the following specific examples of the practice of it.

Example 1 A Woven cotton fabric is moistened on its face with a solution of carboxymethyl cellulose in the proportion of 2 parts of the carboxymethyl cellulose to parts of water. The moistening is made to advantage by spreading and just enough of the solution is applied to Wet the entire surface of the fabric.

Over the wet film of the carboxymethyl cellulose on the fabric there is then dusted a thin layer of particles of vinyl chloride resin containing 20% of dimethoxyethyl phthalate os plasticizer.

The assembly is then reversed, so that the applied layer of particles is down. The fabric is then tapped slightly on the back to dislodge those of the particles which are not in direct contact with the wet surface of the fabric.

The product with the spaced particles adhering is then passed through an infrared heating system maintained at such a temperature as to establish within the particles a temperature of about 325 F. The product with the thus softened thermoplastic particles is then sent through cold ironing rollers which flatten out the particles and press them to an appreciable distance within the surface portion of the fabric.

Example 2 In making a product of the kind shown in Figs. 5 and 6, a series of parallel closely spaced unwoven threads such as warp threads are laid in one plane. Upon this assembly of threads a wet film of the carboxymethyl cellulose and then thermoplastic particles ar applied, warmed and pressed, all by the technique described. The particles bridge the spaces between adjacent ones of the fibers. The result is a bonding of the spaced threads without the need of the cross or woof strands.

Example 3 The procedure of Example 1 is followed except that the sheet material treated is the relatively thick felt 24 of matted fibers, such as a sheet of cotton batting, both sides of the felt are treated, and special press plates are used in place of the smoothing rollers of the earlier example. i

The press plates are provided with spaced elevations of surface which form the negative of the pattern desired in the finished article. When the elevations are a series of cross ridges, then the press plates on the two sides of the assembly impress the troughs and cause compression of the felt at the positions shown at 28 in Fig. '7.

The plastic particles are caused to penetrate the felt, the penetration being particularly deep at the said positions. This causes a quilting effect preventing displacement of the matted fibers without the need of stitching. A facing fabric may be applied to one or both sides of the felt materia1:.,-a't,thesameatime that-thenompressipn takes; planet It gwill beinndetstoodthatitzisiintendeditq cover all changes and mod-ifleatiens ofE the-examples of the invention herein chosen:fonthe -puvppse. of

perature' of SUN-400 FL, removing thpse ptthe eisit articlesm n t. d re t y n; -11 23 t, w h; the said m h m yel d v in s a es b twee er a n ne hrm 9 la e arti1 I nd heat.- math9sheti m and. rfemeiningfispacedrtherm zr plastic particles to the temperature of soft me at.thers gt artiqles, t flQWab fluid qomitti n,

' eatin p usi sstn w-w an ve1om enmpf di qqtttim it fi t wei fi m r sidu emp educed andefi ally tcausi es tten eto mainingthermoplastic ipartielesa and, penetration of them -.within; the surface .,portion:. of the said Sheet.

2;The --method of claim -1 in which: the said permeahle sheet; is a band t of elosely spaced" unotenhp ra el t t le: hre s;

h me hq l. 9 aim, 1 i w ch t s i Permea le. eet; c n h spf.,c q e y,;s qed,

'ening agentused-in-the-gelds-carboxymethy1 --ce1- lulese.

GS-The method ofclaim 1 in which the product of the heating is subjected-t0 apressing-operation i301 increase the extent 0f- -=penetration' of the thermoplastic particleswithin the permeable sheet "and'ttr shape-the expqsedsurfaces pP-th said-particles:

References ,Cited:.,in 1 1.6 filejmof ,.th.i 's.patent UN TED HPATENTSI Number Name Date 1,22j622; WVeinheim Oct.f9,-"l917 l,'76 0;820" Dr w u May-27,1930 215L186 Chadwick; Mar. *2-1-;'*l939 2,190,711 Hanson Feb. 20,1940 2,355;9 1'9" Lipsius Aug. 15 ,=1944 2,390,780 Cornwall; Dec.--11; 1945 2919735428,- Goldman Septwl0g-1946 2, 4 15;023--- Novptny Jan. tee-r1947 2, 15 511,071 Jahant May- 4,="1948 2,489,466 Schramm: Now 29361949 2,491,396 Seckel; Dec1-"18f1949 2,6 Q3',;5 Schr-amm July; 15 3-1952,

FQREIQNLPATENTITS-E;

Number Count -N Date:

s92;116-- France-; Jan-.---e,-1944-

Claims (1)

1. IN MAKING A COATED SHEET MATERIAL THAT IS PERMEABLE TO AIR AND MOISTURE, THE METHOD WHICH COMPRISES APPLYING TO THE FACE OF A PERMEABLE SHEET A THIN FILM OF A VISCOUS AQUEOUS DISPERSION OF AN ORGANIC THICKENING AGENT IN THE PROPORTION OF 0.5 PART 5 PARTS OF THE THICKENING AGENT FOR 100 PARTS OF THE DISPERSION, THE SAID DISPERSION REMAINING ON THE FACE OF TE SHEET, THEN APPLYING DIRECTLY UPON THE SAID FILM IN WET CONDITION A FREE-FLOWING MASS OF FINE PARTICLES OF NORMALLY SOLID THERMOPLASTIC MATERIAL THAT ARE INSOLUBLE IN THE SAID DISPERSION AND ARE SOFTENABLE INDIVIDUALLY TO FLOWABLE FLUID CONDITION AT A TEMPERATURE OF 300*-400* F., REMOVING THOSE OF THE SAID PARTICLES NOT DIRECTLY IN CONTACT WITH THE SAID FILM, THIS REMOVAL DEVELOPING SPACES BETWEEN THE REMAINING THERMOPLASTIC PARTICLES, AND HEATING TH SHEET,FILM AND REMAINING SPACED THERMOPLASTIC PARTICLES TO THE TEMPERATURE OF SOFTENING OF THE SAID PARTICLES TO FLOWABLE FLUID CONDITION THIS HEATING CAUSING LOSS OF WATER AND DEVELOPMENT OF DISCONTINUITY OF THE FILM RESIDUE SO PRODUCED AND FINALLY CAUSING SOFTENING OF THE REMAINING THERMOPLASTIC PARTICLES AND PENETRATION OF THEM WITHIN THE SURFACE PORTION OF THE SAID SHEET.

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