US2772181A

US2772181A - Coated web product and method of making same

Info

Publication number: US2772181A
Application number: US314244A
Authority: US
Inventors: Sedgwick C Rogers; Kenneth J Harwood
Original assignee: Kimberly Clark Corp
Current assignee: Kimberly Clark Corp
Priority date: 1952-10-11
Filing date: 1952-10-11
Publication date: 1956-11-27
Anticipated expiration: 1973-11-27
Also published as: GB763453A

Description

Nov. 27, 1956 s. c. ROGERS ETAL COATED WEB PRODUCT AND METHOD OF MAKING SAME Filed OC'L. ll, 1952 United States arent COATED WEB PRDUCT ANB l'VIETHD 0F MAKING SAME Sedgwick C. Rogers, Appleton, and Kenneth J. Harwood,

Neenah, Wis., assignors, by mesne assignments, to Kirnberly-Clark Corporation, a corporation of Deiaware Application ctoher 11, 1952, Serial No. 314,244

11 Claims. (Cl. 117-9) This invention relates generally to improved web products and more particularly to web products having incorporated therein a soft, flexible, water insensitive bonding agent, and the method of producing the same.

Many web products include a bonding agent for adhesively connecting the bers of the web. Such products are adaptable for a wide range of uses, such as, wrappers for sanitary napkins, disposable towels, various hospital and surgical uses, etc.

When a bonding agent is used in a web product it atects the properties of the product. The type of bonding agent chosen is particularly important when the web product is designed for use as a wrapper for a sanitary napkin. in such case it is important that the bonding agent be water insensitive (i. e. it does not lose its bonding properties in the presence of Water or disintegrate in the presence of Water) so that the web product will not disintegrate in use; be suiiiciently soft and exible so as not to detract from softness and flexibility of the lbers o' the web product; and be of sucient adhesive strength to impart a tensile strength to the web product suicient to prevent the web from disintegrating under a reasonable sculiing action.

The various bonding agents which have heretofore been used in wrappers for sanitary napkins have imparted to the wrapper certain undesirable properties. One common bonding agent which has been used in such wrappers consists or plasticized polyvinyl acetate containing emulsifying agents, thickeners, etc. Bonding agents of this type are somewhat water sensitive and do not have the flexibility and softness desired for use in sanitary napkin wrappers.

The main objects of the present invention are to provide web products having a new and 'unproved bonding agent incorporated therein; to provide web products of the character indicated which are sui'liciently soft, flexible, and water insensitive so as to make such products acceptable for use as a wrapper for sanitary napkins; to provide web products of the character indicated which are of sulhcient tensile strength so as to be scuff resistant; and to provide web products of the character indicated which may be made economically and Which will require the employment of relatively inexpensive materials. Other objects of the invention are to provide a method for producing web products of the character indicated, and to provide a method of producing web products which affords easy control of the characteristics of such web products. Other objects and advantages of the invention will be understood by reference to the following specification and accompanying drawings in which there are schematically illustrated various web products formed in accordance with the present invention and the method of producing such products.

In the drawings: Y

Fig. l is a more or less schematic illustration on an enlarged scale of one form of web product made in accordance with the present invention;

f' 2,772,181 Ice Patented Nov. 27, 1956 Fig. 2 is a schematic illustration of the method and apparatus for producing the web product illustrated in Fig. l;

Fig. 3 is a more or less schematic illustration on an enlarged scale of a part of the method and apparatus shown in Fig. 2; and

Fig. 4 is a more or less schematic illustration on an enlarged scale of a detail of construction of the woven component of the improved web product.

Fig. 5 is a schematic illustration of another form of web product made in accordance With the present invention.

Web products, made in accordance with the present invention, generally comprise a plurality of filaments which are bonded together by a partially fused mixture of a thermoplastic water insensitive, resinous material and a compatible plasticizer. The word filament as used in this specilication is intended to include both discrete fibers and threads.

By the term compatible plasticizer as used in this specilication and claims, we mean that the selected plasticizer must be able to maintain the resin as a dispersion when the resin is in solid form, and that the plasticizer is soluble in the resin when the resin is completely fused and relatively insoluble in the resin at temperatures considerably below the fusing point of the resin. The plasticizer should dsc have low volatility and no decomposition at the temperature of fusion of the resin. In order to facilitate the milling of the resin and its dispersion, the plasticizer preferably has a high degree of fluidity at room temperature.

The preferred form of the invention makes use of materials known as organosols and plastisols as the adhesive bonding materials. In both these types of suspensions, the resin, in the form in which it is applied to the Web, is dispersed in a suspending medium consisting essentially of the compatible plasticizer in the case of the plastisol, and a mixture of the plasticizer and an organic solvent in the case of the organosol.

Because of its strength and adhesive properties, We prefer to use a vinyl resin, particularly polyvinyl chloride or a polyvinyl chloride acetate copolymer as the main resinous constituent in the bonding composition. The invention, however, is not limited to the use of this particular resin, but applies to the use of other thermoplastic, water insensitive resinous materials combined with their compatible plasticizers.

Suitable plasticizers for the vinyl resins include dioctyl phthalate, dioctyl sebacate, polyethylene glycol di(2 ethylhexoate), secondary plasticizers, such as partially hydrogenated mixtures of isomeric terphenyls, and mixtures of these plasticizers. Plastisols and organosols of the type indicated are prepared by milling resin agglomerates with the plasticizer in a pebble mill, ball mill, or the like to subdivide the resin sutiiciently and to blend the mixture into a substantially uniform suspension of resin particles within the plasticizer. if the resin particles are already suliiciently small (on the order of one micron or less) the millingl may be eliminated and the resin particles may then be added to the plasticizer directly by simple stirring.

Compositions of this type go through several stages during heating. As heat is applied and the temperature is raised, it appears that the outer surfaces or the resin particles tend to be solvated by the plasticizer. The temperature at which all of the resin has been solvated by the plasticizer and is formed into a homogenous mass is known as the fusion temperature. The partially fused state exists when only a portion of the resin is solvated in the plasticizer. In this stage of cure, the resin-plasticizer mixture is in the nature of a gel, It is the continued heating of the mixture at the characteristic fusion temperature of the resin which causes the resin to fuse together into a continuous film and to develop its maximum physical properties.

These characteristics are taken advantage of in operating the process of the present invention, as will appear from the following description.

Web products made in accordance with this invention may take a variety of forms, one such form being shown .in Fig. 1. This product is designed for use as a wrapper for a sanitary napkin and is generally similar in outward appearance to the web product set forth in Harwood and Le Dain Patent No. 2,564,689, issued August 21, 1951. It should be understood that the bonding agent employed herein can be used in a similar manner in various other web products, a few of which shall be described at a later point.

The web product shown in Fig. 1 includes a thread web of Woven material, such as gauze, which is represented in the figure On an enlarged scale in about the 9 proportions of an 18 x 8 web, that is a web having 18 threads to an inch extending in a lengthwise or machine direction of the fabric, and 8 threads to the inch extending crosswise of the length of the fabric. The lengthwise extending threads are indicated at 2, and the cross threads at 3.

A stable dispersion of a thermoplastic, water insensin tive, resinous material and a compatible plasticizer, speciiically a mixture of a polyvinyl chloride and dioctyl phthalate, appears along discrete areas 4a at alternate intersections of the woven threads and also more or less continuously as indicated at 4b along the lengths of the lengthwise threads 2. An applique or facing 5 of nonwoven fber, such as cotton liber, is adhesively embedded in the solidified mixture of resin and plasticizer. The facing or applique of ber may be formed of other natural fibers or various synthetic fibers or mixtures of natural and synthetic bers suitable to the purpose for which the product is destined.

The fibers which form the `applique may be of various lengths depending on the process employed for their formation, and in one practical embodiment they range from 1,66 inch or even less, to one inch or more in length with a large proportion of fibers being of an intermediate length, say of around (46 of an inch. In general, the applique is made very thin or of a very light density since a Very heavy or tight mat of cotton on the woven web is usually not desired in a wraper for a sanitary napkin.

The web product shown in Fig. l-may be produced in the manner illustrated in Fig. 2. As illustrated in thisgure, the web of woven filaments or the like is drawn from a supply roll 6 and guided by means of suitable guide rolls 7 over an yapplicator roll 8.

A relatively stable dispersion; i. e., one which does not change markedly upon standing, consisting of finely divided particles of a thermoplastic, water insensitive, resinous material and a Compatible plasticizer is contained in the reservoir 9 above the applicator roll 8. The dispersion may be delivered into a pool 10 formed between a portion of the applicator roll surface and one side of a doctor blade 11 which regulates, in well-known manner, the thickness of the dispersion carried by the surface of the applicator roll 8 beyond the doctor blade 11. By this arrangement, the dispersion is 'applied to the upper surface of the woven web 1.

In order to have the dispersion deposited on the gauze web in the pattern and distribution shown .in Fig. l and remain on the surface of the gauze threads with but little, if any, penetration thereof, it is essential that the viscosity of the dispersion be between 2,900 and 16,000 centipoises and preferably between 4,000 and 7,000 centipoises.

In order to Iapply the dispersion tothe Web 2 in .the manner illustrated, it is also necessary to drive the applicator roll S at a slightly different rate of speedfrom the speed of the woven web 1. For example, the gauze may be driven at a speed of around 200 feet per minute while the surface speed of the applicator roll ,is about 196 feet per minute. When the gauze rate and the roll are driven at this relationship; i. e., at a speed differential of about 2 to 5%, the effect is to cause the gauze 1 to wipe across the surface of the roll 8 to thereby scrape some of the viscous dispersion from the roll. Y

As shown in Fig. 3, the gauze 2 bears on the dispersion carrying applicator roll 3 particularly at the thread crossings. The portions of the cross threads 3 which overlie the longitudinal threads 2; more or less project in the normal plane of the gauze. These projecting or high portions of the cross threads 3 tend to scrape some of the dispersion from the surface of the roll 8. This is represented in Fig. 3 where the crosswise thread indicated at 3a, is illustrated as having Ea small amount of.

cumulated small blobs la of the dispersion at alternate intersections of the threads as indicated in Fig. l.

The lengthwise extending threads also pick up a coating of the dispersion which extends circumferentially only from about 1A to about 1/2 of the distance around the threads, more or less, continuously lengthwise thereof. The lengthwise continuity of the dispersion on the longitudinal threads may be broken for short lengths immediately behind the cross threads 3 and perhaps haphazardly at other points as shown, due to various causes; for example, a probable tendency to stretch or elongate the dispersion ribbons which would evidently occur as an incident of travel of the gauze 1 at a higher speed than the surface speed of the dispersion applicator roll 8.

The quantity and location of the dispersion in the areas la and 4b may be adjusted by adjusting relative speeds of thel web 1 and the dispersion applying roll 8, by adjusting the circumferential extent of the contact between the web 1 and the dispersion applying roll 8, and by adjusting the depth of the coating of dispersion on the applying roll 8. In the illustrated arrangement, the dispersion is more or less accumulated or piled up on the forward or leading sides of the cross threads 3 at their points of crossing the lengthwise threads 2. If the roll 8 is rotated at a surface speed which is greater than that of the gauze travel, such accumulations of dispersion will be produced in back of said portions of the cross threads 3.

After the upper surface of the web 1 is coated with the dispersion, the web is run over a heated roll 12 which causes the dispersion to gel by partially or completely fusing most of the smaller resin particles while leaving the larger particles incompletely fused, but with their outer surfaces swelled with the plasticizer. Thus the gelled, partially fused dispersion contains discrete resin particles and plasticized resin, and may also contain some plasticizer.

The temperature of the heated roll 12 is such as to just solidify the dispersion during the time in which it is in contact with the web and is generally 'within the range of 240 to 295 F. for the polyvinyl chloridedioctyl phthalate combination. 'Ihe preferred range is froml 280 to 295 F. These temperatures are below the 350 to 360 F. fusion temperature ofy these resins. The roll 12 is slightly raised with respect to the applicator roll 8 in order to keep the web against the roll 12 for longer than a momentary contact.

It is extremely important for the purposes of this invention that'the resin be incompletely fused at this stage of the process.` The flow characteristics of the resinplasticizer change very substantially as the resin is heated to its fusion point, as at this temperature, the resin and plasticizer both become fluid and homogenously intermixed. If the resin is completely fused at this stage, it impregnates the web quite substantially and becomes unavailable for attachment to the subsequently applied applique. If, however, the temperature is controlled so that the resin is not completely fused, but only set up to the gelled stage, the resin remains on the surface of the threads, and when cooled slightly, is practically dry to the touch. In this condition, the resin-treated web can be handled easily in the remainder of the equipment without causing gumming up of the rolls and similar problems. The resin-plasticizer combination in this state of partial cure can be stored for indefinite periods without noticeable deterioration or loss of adhesive capability.

After leaving the roll 12, the coated web cools sufficiently so as to render the partially fused dispersion coated surface non-tacky, permitting it to be wound into rolls such as indicated at 6a for subsequent use, or it may proceed directly into the zone of operation of mechanism which deposits the liber applique on the coated surface of the web.

The fibers which form the non-woven applique or facing emanate from cotton slivers, header rolls, coiler cotton, or any suitable lap or bat of the selected cotton or other fiber. In the following description, the terms lap and bat, when employed to refer to a source of fibers, refer to any suitable assemblage thereof whether or not in the forms technically known as sliver, header roll, lap, bat, etc. The lap or bat of bers is preferably non-woven, and although it may be and usually is of self-supporting strength, it is preferably not too tightly made or felted.

In Fig. 2, the source of the fiber applique 5 is shown as being a lap of cotton; that is to say, a non-woven bat of cotton (or other) fiber which is suitably fed to ward a divellicating or detibering roll 13. This detibering roll is driven at a high speed and its surface is provided with a multiplicity of teeth projecting from the normal roll surface, said teeth being operative to pull fibers from the lap as the lap is fed toward the roll. The feed of the lap toward the roll should be carefully regulated to permit the teeth of the divellicating roll 13 to act against only a single fiber thickness on the end of the la thereby to insure disintegration of the lap fiber by fiber and to avoid the biting off of heavy chunkso'f fiber which would be somewhat objectionable because such chunks would interfere with the desired smoothness and softness of the final product.

The debering roll 13 is arranged in suitable relation to a continuously traveling belt 14 on which the separated bers are deposited at 5b to build up a secondary or refined lap or bat 5c of fiber. The thickness of the bat may be controlled as desired, by appropriately regulating the speed of travel ofthe belt 14, by regulating the rate at which the lap is fed to the divellicating roll 13, and also by appropriately selecting a starting lap of predetermined thickness.

A suction box 1S is preferably associated with the upper reach of the belt 1d to facilitate and more or less control the deposition of the fibers on the belt 14. Suitable guide walls may be arranged to confine the stream of fibers in the desired bat.

'The refined lap or bat 5c of fibers may be rolled upon itself for storage purposes and for subsequent use. However, the refined bat 5c may be fed directly into the operating zone of a second deiibering or divellicating roll 16 of substantially the same character as the divellicating roll 15. The speed at which the bat Se is fed to the roll 16 is, of course, carefully controlled to insure operation of the roll 16 on substantially single ber portions, 0f the advancing, and Of tllsbaS The farmation of thel bat 5 be so regulated tljiat` this refined bat may be fed forwardly at the same rate as that of the starting lap and the roll 16 will operate ina satisfactory manner to properly disintegrate the refined bat 5c into single fiber pieces. By this arrangement, the rolling of the bat 5c upon itself may be avoided and the process made substantially continuous from the disintegration of the lap 5a to the deposition of the fibers on and attachment thereof to the carrier web.

This subiection of the fiber material to successive defioering operations results in very effective untangling and separation of the fibers so that the deposition of ber on the carrier web may easily be conned to films as light as 1.5 grams per square yard, lthe ber being quite uniformly distributed and deposited usually in a haphazard directional arrangement, although byvmean's of certain controls, the directional arrangement may be more or less predetermined. The stream 5d of fibers produced by the divellicating roll 16 is suitably guided to the surface of the web 1 which may come directly from the heated roll 12 or from the supply roll 6b which would be one of the rolls produced as indicated at 6a. If the web is drawn from a supply roll such as the roll 6b, the roll is so mounted and the web is so drawn from it that the dispersion bearing side of the web will be on the top face of the web, on which side the stream 5d of bers is deposited. The deposition of the bers Sd on the web may be aided by means of a suction box 17 associated with the web 1. y

The web ,1 now having an applique or facing S of non-woven fiber is next guided by means of suitable guide rolls 18, 1S around a portion of a iinn but resilient calender roll 19 which is supported by a rigid supporting roll 20. A ily roll 23 urges the Webagainst a heated steel or similar hard rigid calender roll 21 which cooperates with the calender roll 19 to press the fiber applique and woven web tightly together, Vthe heat of the roll 21 serving to soften the partially fused dispersion in the areas 4a and 4b so as to permit the fibers 5d to be embedded in the softened dispersion. The temperature of the heated calender roll 21 is preferably maintained at a temperature below that required lto completely fuse the resin and plasticizer of the dispersion during thetime that the coated web is in contact with the heated calender roll 21. This temperature is generally maintained within the range of 26S-320 F. for the `combination of polyvinyl chloride and dioctyl phthalate. If the temperaturevis raised to a point Where the resin and plasticizer of the dispersion completely fuse, the resultant` plasticized resin is sufciently iluidrto flow aroundvand be absorbed by the fibers and woven web thereby altering the characteristics of the web product and is sufficiently tacky to gum up the calender rolls. lThe temperature should be sufficiently high, however, to increase the degree of fusion of the resin above that of the material on the coated web prior to this final calendering.`

The calender roll 19 is preferably constructed of cotton discs stacked in the direction of the length of the roll under such compression asV to provide it with a surface which is at least slightly compressible or resilient. When the ber faced woven webris calendered by being run between the

rolls

19 and 21, the threads of the woven web are more or less compressed into each other at their crossings and the threads are more or less flattened approximately as represented at 22 in Fig. 4. This flattening and embedding the threads in each other serves to eliminate to a considerable extent the prominences usually present in woven material at the crossings of the interwoven threads. To a lesser extent, the entire lengths of the threads are also slightly flattened. Flattening of the crossing thread portions and the meshing thereof into each other, and the indicated flattening of the threads throughout their lengths probably serves to increase the flexibility of the fabric since the thickness of the material is reduced with.

a corresponding increase in bendability. The employment of the more or less resilient, cotton constructed roll 19Yavoids cutting up the threads of the woven web at their crossings when subjected to the indicated calendering operation. If desired, the guide roll 18 may be heated to a temperature near that of the calender roll 2l so as to preheat the coated web before it reaches the heated calender rolls. This preheating Aoperation permits the web to be run at a faster rate of speed between the calender rolls 19 and 21 than would be otherwise possible.

After the web passes the calender rolls, the applique is eifectively bonded to the web 1 so that there is a negligible amount of loose ber which will dust olf the finished web product during handling. This effective bonding of the ber results mainly from the direct adhesive bonding of some of the bers to spaced portions of the woven web; for example, at the areas 4a and the various points where the bers cross the coatings 4b on the threads 2, and from the Vfact that some of the bers which are directly bonded to the woven web are intertwined with and'rnore or less overlap some of the other bers which Vdo not directly contact any portion of the partially fused dispersion, and also in part by the normal cohesive tendency between bers of the same kind, especially after the calendering operation whereby the bers are forced into intimate contact with each other andwith the carrier web. For the reasons indicated, even the shortest bers are effectively retained in the applique, it being understood that the ber lengths might vary from JAG of an inch to as much as three inches or more.

By causing the threads of the woven fabric to be adhesively bonded together at alternate crossings thereof as shown at 4a, the Woven web itself is stabilized in respect to the position of the threads relative to one an other. This helps to maintain the woven threads in the desired uniform, grid-like formation which provides an effective support for vthe non-woven ber applique; it also adds appreciably to the appearance of the product. By spacing the points of adhesive'bonding of the threads of the carrier web and of the applied ber to the carrier web, the normal flexibility of the woven material is maintained to a high degree, if not in its entirety. By employing an adhesive material which is'permanently exible, the adhesive on the longitudinal threads 2 of the gauze will not, despite its nearly continuous application to the threads, materially stiften the threads or the gauze.

The applique of non-woven bers arranged in haphazard directions as shown in Fig. l, serves as a sort of shield for the relatively harshl threads of the woven web, the lm or facing presenting a soft, smooth surface which has important non-chang characteristics when the material is employed as a wrapper for sanitary napkins or other types of bandages. When the lm of non-woven ber is made somewhat heavier, the material may be adaptable to the making of ornamental fabrics such as drapes, the woven thread component serving -to impart adequate strength while the non-woven film provides a nshed looking surface which may be imprinted or other wise decorated. By the employment of a fairly strong suction in the suction boX, a considerable amount of ber may be caused to extend through the gauze so as to form a facing on'both sides of the .gauze web. For certain purposes, this may be highly desirable.

Instead of the indicated type of divellicating or debering apparatus, we may employ other equipment such as garneting or carding machines or drawing frames (such asV the supply wrap ,apart into its `component ber and to deposit such separated bers on the carrier web.

As previously stated, the operating conditions mustbe f such that the dispersion coating remains on the surface of the carrier web with little, if any, penetration ofthe threads of the woven web. By the Vemployment of aV permanently exible adhesive dispersion which will remainV on the surface of the threads, mostrof the normal flexibility of the components of the material are preserved. However, for some purposes, it may be desirable tohave the adhesive dispersion penetrate the threads of the woven: web.

combination of thermoplastic water insensitive,.resinous materials and compatible plasticizers. For a polyvinyl chloride-dioctyl phthalate combination, the viscosity of the dispersion should be within the range of 2900 to 16,0% centipoiscs so as to locate the dispersion at the cross threads with discontinuous portions onrthe warp threads. T his requirement effectively determines the relative amounts of the resin and plasticizer in the dispersion.

One suitable formulation for the dispersion consists of 56 parts by weight of polyvinyl chloride resin (Geon 121) powder and 44 parts by weight of dioctyl phthalate plasticizer. There is some freedom in these proportions but because of the viscosity requirement, it is preferred to keep the specified proportions within `2 parts by weight (i. e., from 54-58 parts polyvinyl chloride to 42-46 parts plastici/ier). This formulation may be applied at the rate of about 2 grams per square yard or 18 x 8 gauze. lt easily fuses to the desired extent when it passes over the heated roll l2 which is at a. temperature of around fS31-290 F., remaining on the surface of the gauze threads with but little, if any, penetration thereof. The

partially fused resin is water insensitive and permanently.

exible so that there is no stitfening with age.

in certain formulations of thermoplastic resins and compatible plasticizers, it may be desirable to use an organosol prepared by adding a volatile organic thinner such as diisobutyl ketone, Xylene, high ash naphtha and the like, to the dispersion to obtain the proper viscosity for the dispersion. When such organic thinner is added to the dispersion, it will evaporate as the dispersion is heated to the point here the resin begins to fuse with plasticizer. Gne suitable organosol contains 60 parts by weight polyvinyl chloride resin, 6() parts dioctyl phthalate, 46 parts petroleum naphtha thinner, and 52 parts diisobutyl ketone properly milled together.

Variations in respect to the formulation and quantity of the dispersion, and types and quantity of ber ern ployed in producing the faced web serve to alter the characteristics of the final web product. Forexample, the use of large quantities of adhesive dispersion tends to impair the softness and flexibility of the web product, and larger quantities of ber per unit of woven web tends to impair the permeability of the web product while increasing its cushion characteristic.

Otherplastisol mixtures which have been used successfully in the practice of the invention include the following:

When this is desired, a web product having an. applique of non-woven ber made in the manner described'. above, may be run through `an oven maintained at a temp-- Partially hydrogenated mixture of isomeric terphenyls Suitable organosol formulations include the following:

Parts by weight Polyvinyl chloride-polyvinyl acetate resin 20 Dioctyl phthalate 13.5 Xylene 18.6 High flash naphtha 3 Polyvinyl chloride-poiyvinyl acetate resin 20 ilolyethyiene glycol di(2-ethylhexoate) 15 Xylene 15 In the above described web product a solidified mixture of a thermoplastic, water insensitive resin and a compatible plasticizer bonds the filaments of a particular web product. it should be understood that the use of this novel bonding agent is not confined to this particular type or form of web product, but can be used generally whenever it is desired to bond together the filaments of Woven or non-woven web products. When such a solidified mixture of thermoplastic, water insensitive, resin and plasticizer is employed as a bonding agent for a web product, it is generally applied in the same manner as has been described in connection with the web product shown in Fig. l.

A Web product may be made in accordance with the present invention by applying said dispersion to a Woven or knitted thread web, or to a non-Woven web` formed by carding, garnetting, air-laying or by other mechanisms. The dispersion may be applied to the entire surface or to selected portions of the surface of such webs. The dispersion may be applied to the woven or non-Woven webs in a direct .l ann-er by spraying, brushing, immersing the web in a bath of the dispersion, by running the web over a suitable printing roll, etc., or in an indirect manner through the agency of coated threads or filaments placed, either singly or in bundles in straight lines along the surface of the web or deposited in haphazard direction over the entire surface or over discrete portions of the surface of the Web. The web having the dispersion thereon is heated so as to partially fuse the dispersion and calendered in said heated condition.

The coated fibers or laments, referred to above, may be produced by applying the described dispersion of finely divided particles of thermoplastic, Water insensitive resin, and a compatable plasticizer to the surface of said fibers or filaments by spraying, brushing, immersion, etc. Heat is then applied by any suitable method to the coated fibers or filaments until the dispersion gels by forming a partially fused mixture of resin and plasticizer.

One form of non-woven web produced by the present invention is illustrated in Fig. 5. This Web product may be made by first forming a carded web of fibers 24 of substantial length and then applying a dispersion similar to that used in making the web product shown in Fig. 2 on the surface of the web along lines 25 extending crosswise of the direction of the fibers in the web. The coated web is then run over a heated roller or through a drying oven to gel the dispersion by partially fusing the thermoplastic resin and plasticizer in the dispersion. Finally, the web product is run through a heated calender stack so as to embed the fibers in the softened dispersion, and to cause additional fusing of lthe resin. The par tially or totally fused Aresin on the vsurface ofI the Vcarded fibers in the finished web product is water insensitive and permanently flexible so that it does not detract from the softness or usefulness of the product; at the same time it imparts to the web a self-sustaining strength which makes the web product useful for a variety of purposes for which it was previously unacceptable. y

For many applications it is desirable to` avoid complete fusion of the resin not only for the time of application of the resin to the fibers but throughout the entire process. When doing so, it has been found that substantially smaller quantities of the resin need be employed to achieve comparable results. For example, amounts of the resinplasticizer in the range from l0 to 25% by'weight of threads, produces an acceptable material Where the resin is not completely fused, Whereas with a completely fused product, amounts of the r'esin-plasticizer composition of 50% or more by Weight of threads must be employed for equivalentresults. s

The above examples of web products are not intended to be inclusive of all such products which might be made in accordance with the present invention.

The teachings of the present invention can, for example, be applied to laminating web products by a process 'in which an adhesive of the type described is applied to a series of non-Woven webs. The adhesive on the webs will be in the partially fused state, as described. The webs may then be assembled and passed through heated calender rolls to cause further fusion and bonding of the plies together.

Various of the features of the invention which are believed to be new are set forth in the appended claims.

We claim.

1. A method of forming a web product comprising the steps of forming a stable dispersion of finely divided particles of a thermoplastic, water insensitive resin and a compatible plasticizer, said dispersion having a viscosity within the range of 2900 to 16,000 centipoises, applying said dispersion over at least a portion of the surface of a filament web, and heating said web containing said dispersion thereon to a temperature suicient to only partially fuse said resin particles with said plasticizer and thereby produce a substantially dry surface coating on the filaments of said web Without substantial impregnation of resin Within said filaments..

2. A `method of forming a web product comprising the steps of forming a stable dispersion of finely divided particles of a polyvinyl resin and a compatible plasticizer, said dispersion having a viscosity within the range of 2900 to 16,000 centipoises, applying said dispersion over at least a portion of the surface of a filament web, and heating said web having said dispersion thereon to a temperature of between 240 to 295 F. to only partially fuse the resin in said plasticizer and thereby produce a substantially dry surface coating on the filaments of said web without substantial impregnation of resin within said filaments.

3. A method of forming a web product comprising the steps Yof forming a stable dispersion of finely divided particles of a thermoplastic, water insensitive resin and a compatible plasticizer, said dispersion having a viscosity` within the range of 2900 to 16,000 centipoises, applying said dispersion over at least a portion of the surface of a filament web, heating said web having said dispersion thereon to a temperature sufficient to only partially fusey said resin particles in said platicizer and thereby solidify said dispersion on the surface of said web Without subtantialimpregnation of resin within the filaments of said web, and thereafter further heating said dispersion on said web at a temperature suicient to cause further fusion of said resin, said further heating being insuficient to completely fuse said resin particles in said plasticizer so that said dispersion remains solidified on the surface of said web withoutsubstantial impregnation of resin within the filaments of said web.

, 4. A method of forming a web product comprising the steps of forming a stable dispersion of inely divided particles of polyvinyl chloride resin in dioctyl phthalate, said dispersion having a viscosity within the range of 2900 to 16,000 centipoises, applying said dispersion over at least a portion of Vthe surface of ya filament web, and heating said web containing said dispersion thereon to a temperature suliicient to only partially fuse said particles of polyvinyl chloride resin in said dioctyl phthalate and thereby produce a substantially dry surface coating on the `iiilaments of said web without substantial impregnation of resin Within said filaments.

5. A method of forming a web product comprising the steps of forming a stable dispersion of finely divided particles of polyvinyl chloride resin in ldioctyl phthalate, said dispersion having a viscosity within the range of 2900 to 16,000 centipoises, said mixture containing 42 to 46 parts by weight of dioctyl phthalate to 54 to 58 parts by weight of polyvinyl chloride resin, applying said dispersion over at least a portion of the surface of a lilament web, Vand heating said web containing said dispersion to a temperature suiiicient to only partially fuse said polyvinyl chloride resin 4in said dioctyl phthalate and thereby produce a substantially dry surface coatingon the ilaments of said web without substantial impregnation of resin within the iilaments of said web.

6. A method of forming a web product comprising the steps of forming a stable dispersion of finely divided particles of a thermoplastic, water insensitive resin and a compatible plasticizer, `said dispersion having a viscosity within the range of 2900 to 16,000 centipoises, applying said dispersion over at least a portion of the surface of a woven web, heating said web having said dispersion thereon to a temperature sufficient to only partially fuse said resin in said plasticizer and thereby solidify said dispersion on the surface of the threads of said web without substantial impregnation of resin within said threads, depositing an applique of separated bers on the surface of said web having said solidified dispersion thereon, and reheating said fiber containing web to a temperature sucient to soften said dispersion and further fuse said resin, said reheating being insufficient to completely fuse said resin lin said plasticizer so that said dispersion remains on the surface of the threads of said web without substantial impregnation of resin within said threads, and calenderingl said ber containing Web while in said heated condition so as to bring said web and applique into intimate contact with said dispersion whereby the web and applique become embedded in said dispersion.

7. A method of forming a web product comprising the steps of forming a stable dispersion of finely divided particles of a polyvinyl chloride resin in dioctyl phthalate,

Y said dispersion having a viscosity within the range of 2900 Y to 16,000 centipoises, applying said dispersion over at least a portion of the surface of a Woven web, heating said web having said dispersion thereon to a temperature suicient to only partially fuse said polyvinyl chloride resin in said dioctyl phthalate and thereby solidify said dispersion on the surface of the threads of said web without substantial impregnation of resin within said threads, depositing an applique of separated fibers on the surface of said woven web having said solidified dispersion thereon, reheating said liber containing web to a temperature suicient to soften the dispersion and to cause further fusion of said polyvinyl chloride resin, said reheating being insuflicient to completely fuse said polyvinyl chloride resin in said dioctyl phthalate so that said dispersion remains on the surface of the threads of said web without substantial yimpregnation of resin within said threads, and

calendering said liber containing web while insaid heated condition to bring said web and applique into intimate cort-Y v thereon to a temperature of between 240 to 295 F. to

only partially fuse said polyvinyl chloride resin in said dioctyl phthalate and thereby solidify said dispersion on the threads of said web without substantial impregnation of resin within said threads, depositing an applique of Y separated fibers on the surface of said web having said solidified dispersion thereon, reheating said liber containing web to a temperature of between 265 and 320 F. to soften said dispersion and to cause further fusion of said resin, and calendering said ber containing web while in said heated condition to bring the web and applique into intimate contact with said dispersion whereby the web and applique are embedded in said dispersion, said reheating being insufficient to completely fuse said polyvinyl chloride resin whereby said dispersion remains solidified on the surface of the threads of said web without substantial impregnation of resin within said threads.

9. The method of forming a web product which comprises forming a stable dispersion of finely divided particles Y of polyvinyl chloride resin in a compatible plasticizer,

said dispersion having a viscositywithinthe range of from 2900 to 16,000 centipoises, applying said dispersion over at least a portion of the surface of a woven web such that the dispersion is applied primarily lengthwise of said web, and heating said web and the dispersion applied thereto at a temperature sucient to only partially fuse said polyvinyl chloride resin and thereby produce a substantially dry surface coating on the threads of said web without substantial impregnation of resin within said threads.

10. A web product compo-sed of filaments having a surface coating comprising a discontinuous pattern of a partially fused mixture of 54 to 58 parts by weight of polyvinyl chloride resin'in 42 to 46 parts by weight of dioctyl phthalate bonded to portions of the surface of said filaments.

11. A web product composed of lilaments having a surface coating comprising a discontinuous pattern of a partially fused mixture of 54 to 58 parts by weight of a polyvinyl chloride resin in 42 to 46 parts by weight of dioctyl phthalate bonded to portions of the surface of said filaments, the amount of said mixture beingrfrorn 10 to 25% by weight of said filaments.

References Cited in the tile of this patent UNITED STATES PATENTS 2,426,316 Martin Aug. 26, 1947 2,564,689 Harwood et al. Aug. 21, 1951 FOREIGN PATENTS 588,447 Great Britain May 22, 1947 631,850 Great BritainY Nov.'10, 1949 OTHER REFERENCES Baird: British Plastics, April 1948,Y pp. 167 to 171., Sirota: Dispersion Coating, Organic Finishing, December 1950, pp. 11 to 15.

Claims

8. A METHOD OF FORMING A WEB PRODUCT COMPRISING THE STEPS OF FORMING A STABLE DISPERSION OF FINELY DIVIDED PARTICLES OF POLYVINYL CHLORIDE RESIN IN DIOCTYL PHTHALATE, SAID DISPERSION HAVING A VISCOSITY WITHIN THE RANGE OF 2900 TO 16,000 CENTIPOISES, SAID DISPERSION CONTAINING 42 TO 46 PARTS BY WEIGHT OF POLYVINYL CHLORIDE RESIN, APPLYING SAID DISPERSION OVER AT LEAST A PORTION OF THE SURFACE OF A THREAD WEB, HEATING SAID THREAD WEB HAVING SAID DISPERSION THEREON TO A TEMPERATURE OF BETWEEN 240 TO 295* F. TO ONLY PARTIALLY FUSE SAID POLYVINYL CHLORIDE RESIN IN SAID DIOCTYL PHTHALATE AND THEREBY SOLIDIFY SAID DISPERSION ON THE THREADS OF SAID WEB WITHOUT SUBSTANTIAL IMPREGNATION OF RESIN WITHIN SAID THREADS, DEPOSITING AN APPLIQUE OF SEPARATED FIBERS ON THE SURFACE OF SAID WEB HAVING SAID SOLIDIFIED DISPERSION THEREON, REHEATING SAID FIBER CONTAINING WEB TO A TEMPERATURE OF BETWEEN 265 AND 320* F. TO SOFTEN SAID DISPERSION AND TO CAUSE FURTHER FUSION OF SAID RESIN, AND CALENDERING SAID FIBER CONTAINING WEB WHILE IN SAID HEATED CONDITION TO BRING THE WEB AND APPLIQUE INTO INTIMATE CONTACT WITH SAID DISPERSION WHEREBY THE WEB AND APPLIQUE ARE EMBEDDED IN SAID DISPERSION, SAID REHEATING BEING INSUFFICIENT TO COMPLETELY FUSE SAID POLYVINYL CHLORIDE RESIN WHEREBY SAID DISPERSION REMAINS SOLIDIFIED ON THE SURFACE OF THE THREADS OF SAID WEB WITHOUT SUBSTANTIAL IMPREGNATION OF RESIN WITHIN SAID THREADS.