US 3821066 A
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United States Patent [191 Tillotson et a1. t
[ CARPET AND METHOD OF MAKING  Inventors: Neil E. Tillotson, Dicksville Notch,
N.H.; Sebastian A. Consoli, Lawrence, Mass.
 Assignee: Tillotson Corporation, Needham,
221 Filed: Dec. 6,1972 [21 Appl. No; 312,666
 References Cited UNITED STATES PATENTS 3,772,132 11/1973 Dulin,.lr. ..156/72 FOREIGN PATENTS OR APPLICATIONS Great Britainli 161/65 [111 3,821,066 [4511 June 28, 1974 Primary Examiner-William 1. Van Balen Attorney, Agent, or Firm-Kenway & Jenney  ABSTRACT A tufted carpet coated with a fused thermoplastic resin on the underside of a tufted primary backing is formed by impregnating the primary backing with a liquid plasticizer either undiluted or diluted with a solvent for the plasticizer, coating the underside of the primary backing with a solid resin powder capable of being plasticized by the plasticizer and fusing the resin coating by heating. The primary backing can be tufted subsequent to impregnation and preferably prior to impregnation with the plasticizer. In one embodiment a secondary backing, either impregnated with plasticizer or containing no plasticizer is applied to the resin coating either prior to or during the time the resin is fused to' adhere the primary backing to the secondary backing. l
14 Claims, 2 Drawing Figures 1 CARPET AND METHOD OF MAKING BACKGROUND OF THE INVENTION This invention relates to a method for increasing the tuft lock of carpet and to the product obtained therefrom. More particularly, the present invention relates to a process for coating the underside of a tufted carpet with a thermoplastic resin to provide sufficient strength and stabilityto lock the tufts of the carpet in the primary backing. I
Presently, the large majority of the worlds carpets are produced by a tufting process wherein yarn is stitched to a primary backing to form a yarn pile on one surface of the primary backing while a portion of the yarn, known as the bundle wrap, protrudes through the opposing surface of the primary backing. After the stitching step, a secondary backing is applied adhesively to the primary backing and the bundle wrap to provide dimensional stability, drape and enchance the tuft lock of the yarn,i.e., the strength with which the yarn is retained by the primary backing. In most applications the use of the secondary backing is necessary in order to provide the carpet with the desired dimensional stability and drape. The adhesive used to laminate the secondary backing to the bundle wrap and primary backing retains the yarn in place, secures the individual fibers of the yarn, prevents pilling of the yarn, controls dimensional stability (handle or drape) and retains the secondary backing securely to the carpet. Also, it is extremely important that the adhesive not migrate past the primary backing into the exposed yarn pile otherwise the yarns will become stiff and the final carpet will be unacceptable. I
Presently, the most widely'used adhesive system is based upon a latex or a carboxylated latex that is applied to the underside of the primary backing. The water in the latex system migrates through the primary backing into the exposed yarns but the adhesive is retained by the primary backing and the bundle wrap. The latex then is cured and the final carpet dried in large ovens at elevated temperatures. This is a costly process due to the large expense of the ovens, energy requirements floor space requirements, and labor to operate the ovens. A second adhesive system known as the hot-melt system based on the use of vinyl resins also is undesirable since it requires the expense of specially heated containers for transporting, storing, handling and applying the resin to the under surface of the primary backing. In addition, these melted resins tend to migrate into the exposed yarn thereby producing unsatisfactory carpets.
The tuft lock of the carpets produced with either latex adhesives or the hot-melt vinyl adhesives is undesirably low and the yarn can be pulled easily from the primary backing. This low tuft lock has necessitated laying carpets in one or a few large pieces that conform to the shape of the surface being covered rather than permitting the use of small rectangular pieces to cover the same area since the risk of pulling the yarn from the backing when using small pieces would be increased substantially. If carpets having desirable handle and drape were to have a tuft lock greater than presently available they could be laid in small rectangular pieces thus reducing installation labor costs greatly.
It has been proposed to employ stronger adhesives between the layers to increase tuft lock. However, ad-
herence of a secondary backing to the bundle wrap of the carpet presents unique problems that have prevented the use of these stronger adhesives. In order for the adhesive to be fully effective in adhering the yarn to the primary backing, it must penetrate all or substantially all of the bundle wrap. However, the adhesive must not penetrate past the primary hacking into the exposed yarn to any significant degree or theexposed yarn will become stiff and the resultant carpet will be unacceptable. It would be highly desirable to provide tufted carpets having improved tuft lock without increasing the stiffness of exposed yarn and to provide a process for making these carpets which reduces the high heating requirements of present systems. Furthermore, it would be desirable to provide a tufted carpet having desirable handle or drape with or without a secondary backing.
SUMMARY OF THE INVENTION The present invention is based upon the discovery that the underside surface of a tufted carpet through which the bundle wrap of the tufted yarn protrudes can be coated with a thermoplastic resin composition by impregnating the primary backing; with a plasticizer for the resin and subsequently depositing powdered resin substantially free of plasticizer onto the impregnated backing. Since the deposited resin is substantially free of plasticizer, it has an affinity for the plasticizer in the backing thereby causing the plasticizer to be imbibed by the resin and concentrated on the surface of the backing coated with the resin. By virtue of this attraction by the resin, the tufted surface of the primary is coated with little or no resin so that it does not render the exposed tufted yarn stiff. The resin powder then is fused by heating. The fused resin adheres the bundle wrap to the primary backing and provides superior tuft lock. In one embodiment, a secondary backing either impregnated with plasticizer or containing no plasticizer can be applied to the resin-coated primary backing and adhered thereto while the resin is being fused.
DESCRIPTION OF SPECIFIC EMBODIMENTS Impregnation'of the primary backing ,with plasticizer can be effectedeither prior to or subsequent to tufting the primary backing. The plasticizer can be undiluted or diluted with a solvent for the plasticizer. After the impregnation and tufting, the primary backing is coated with powdered unplasticized resin composition on the surface having the exposed bundle wrap. The plasticizer is imbibed into the resin coating so that the surface of the primary backing opposing the surface coated with resin is rendered substantially free of the plasticizer. Thereafter, the resin coating is fused, as for example by being heated in an oven. By virtue of the plasticizer imbibation, little or no resin is present in the exposed tufted yarn and if present only at the surface of the primary backing. It is-preferred that the primary backing be tufted prior to impregnation with the plasticizer so that the bundle wrap then can be more easily impregnated with plasticizer thereby improving subse quent resin adherence thereto.
The process of this invention provides substantial advantages over the process of the prior art in that the tuft lock obtained is far superior to that obtained with present adhesives. Furthermore, the superior tuft lock is obtained with little or no impregnation of the exposed tufted yarn so that the exposed yarn retains the desired appearance even when employing a relatively open primary backing material such as jute.
Any method for coating resin onto the impregnated backing, by which a substantially uniform resin coating is attained can be employed. For example, the impregnated backing can be placed into a gaseous dispersion of the resin. This is accomplished conveniently by placing the backing into a chamber and shaking the resin powder onto the backing so that only the backing surface having the bundle wrap exposed is contacted with the resin. Alternatively, the surface of the impregnated backing can be placed on the surface of a bed of resin or the resin can be spread on the undersurface of the tufted backing as for example with a doctor knife. Since the resin powder contains little or no plasticizer, excess powder drops from the backing upon removal from contact with the resin. The resin is fused at a temperature between about 275 and 350C preferably between 300 and 325C.
It has been found that it is essential to impregnate the backing with the plasticizer prior to contactwith the resin since it has been found that stiff products having a coating that is easily cracked are obtained when the backing is not impregnated with plasticizer. Various amounts of plasticizer can be mixed with the resin so long as the amount mixed is not great enough to cause the resin to become liquid or to form a cake so that it cannot flow freely as a powder.
Suitable resins that can be employed in the process of this invention one of those that can be solvated by the plasticizer and adhered to the backing including vinyl polymers such as polyvinylchloride, polyvinyl acetate, vinyl chloride-vinyl acetate co-polymers, polyvinylidene chloride, and the like.
Any plasticizer which plasticizes the resin coating without damaging the backing can be employed. Exemplary suitable plasticizers include adipic acid esters, such as diethyl adipate, di-n-hexyl adipate; glycol derivatives such as diethylene glycol dipelargonate, triethylene glycol dipelargonate; chlorinated paraffins; phosphoric acid derivatives such as tri(2-ethylhexyl) phosphate, tributoxyethyl phosphate, triphenyl phosphate, cresyl diphenyl phosphate, tricresyl phosphate, and the like; phthalic acid derivatives such as dimethyl phthalate, dibutyl phthalate, dioctyl phthalate, butyl cyclohexyl phthalate, or the like; sebacic acid derivatives such as dimethyl sebacate, dibutyl sebacate, diisooctyl sebacate, or the like.
Any suitable material can be employed to form the primary backing which is not plasticized by plasticizer impregnated therein such as jute or polypropylene which is woven into a fabric. Furthermore any yarn composition now used in carpets can be employed herein including polyamides (nylons), polyesters, acrylics and wool.
The resin composition employed as a coating can comprise one hundred percent resin or it can contain the usual resin additive such as fillers, dyes, pigments, blowing agents, heat stabilizers, light stabiliziers etc. As stated above, the resin also can contain a plasticizer but only in low concentration such that the resin composition remains in the form of a freely flowing powder. The plasticizer can be employed alone or diluted with any suitable solvent for the plasticizer such as a mineral oil, with 5050 mixture of plasticizer and solvent being found especially suitable.
When applying a resin containing an additive such as a filler, it has been found convenient to apply a first light coat of resin to the primary backing followed by a second coat of powdered resin containing the filler. A second coat containing about 10 parts filler per part resin has been found to provide excellent results.
The primary backing is impregnated with sufficient plasticizer so that the resin which contacts the fabric is plasticized and substantially all of the plasticizer is absorbed by theresin thereby rendering the opposing surface of the backing coated with little or no resin.
In one aspect of this invention, a secondary backing comprising a woven or knitted fabric which may or may not be impregnated with a plasticizer is intimately contacted with the resin coating on the tufted primary backing. Thereafter, the resin is fused by heating to adhere the primary and secondary backing and to adhere the bundle wrap to the primary backing. To effect adherence of the two backings, the relative proportion of plasticizer in both backings to resinis maintained within the values set forth above.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a schematic view of a process that can be used to practice the present invention.
FIG. 2 is a cross-sectional view of the product of this invention without a secondary backing.
DESCRIPTION OF THE DRAWINGS Referring to FIG. I, a primary backing 1 comprising a woven fabric such as jute or polypropylene is unwound from storage roller 2 and directed into a conventional tufting apparatus 3 wherein yarns 4 are tufted into the primary backing l to form a pile faced surface 5 and bundle wrap 6 on the undersurface 7 of the primary backing. The tufted primary backing is passed under guide roller 8 and onto drum 9. The drum 9 is coated with an absorbent material such as felt and is rotated in a bath of liquid plasticizer 10 and contacted with the tufted primary backing so that liquid plasticizer absorbed by the coating on drum 9 is transferred to the primary backing l and the bundle wrap 6 by absorbtion. The plasticizer-impregnated tufted primary backing 11 passes under guide roller 12 and over the top open surface of a container 14 which contains a fluidized bed of powdered resin which contacts the underside surface of the tufted primary backing l1 and is adhered thereto. The fluidized resin bed 15 is formed by pumping a gas into plenum chamber 16, through the holes 17 in plate 18 and into the container 14. The powdered resin adhered to the tufted primary backing l1 imbibes plasticizer from the primary backing which causes the resin to become solvated. The resin-coated primary backing 19 passes under guide roller 20 and onto the surface of a heated roller 21 which is maintained at a temperature such that the resin becomes fused to the bottom surface of the primary backing. The tufted, resin-coated primary backing 22 then is wound on storage roller 23.
The carpet of this invention comprises the primary backing 1 having a tufted pile 4 on one surface and on the under surface thereof having bundle wraps 6 coated with a thermoplastic fused resin 24.
1. A process for producing carpeting comprising a primary backing having a yarn pile on one surface and a bundle wrap of the pile on the other surface and a fused resin coating on the surface having the bundle wraps which comprises impregnating said primary backing with a liquid plasticizer, coating the impregnated primary backing on the surface having the bundle wrap with a solid resin powder which is capable of being plasticized by said plasticizer and heating the resin to fuse the resin to said primary backing and bundle wraps.
2. The process of claim 1 wherein the pile and bundle wraps are formed into the primary backing prior to impregnating the primary backing with the plasticizer.
3. The process of claim 1 wherein a secondary backing is applied to the resin coating on said primary backing either prior to or during the time the resin is fused to adhere said primary backing to said secondary backing.
4. The process of claim 2 wherein a secondary backing is applied to the resin coating on'said primary backing either prior to or during the time the resin is fused to adhere said primary backing to said secondary backing.
5. The process of claim 1 wherein the resin comprises poly (vinyl chloride).
6. The process of claim 2 wherein the resin comprises poly (vinyl chloride).
7. The process of claim 3 wherein the resin comprises 6 poly (vinyl chloride).
8. The process of claim 4 wherein the resin comprises poly (vinyl chloride).
9. A carpet comprising a primary backing having a yarn pile on one surface and bundle wraps on the other surface, said surface having bundle wraps being coated with a fused thermoplastic resin composition containing a plasticizer for said resin, said yarn pile being substantially free of resin.
10. The carpet of claim 9 having a secondary backing adhered to said primary backing with said fused resin.
plastic resin and a filler.