US 3519526 A
Description (OCR text may contain errors)
July 7, 1970 R. J. CAREY ETAL 3,519,526
ELASTOMER-BACKED CARPET Filed July 21. 1966 '25 7 29 22 mmmrfwawqy m 3 INVENTORS ROBERT J CAREY GEORGE M BRYANT ANDREW T WALTER ATTORNEY United States Patent 3,519,526 ELASTOMER-BACKED CARPET Robert J. Carey and George M. Bryant, South Charleston, and Andrew T. Walter, Charleston, W. Va., assignors to Union Carbide Corporation, a corp-oration of New York Filed July 21, 1966, Ser. No. 566,988 Int. Cl. B321 /20, 27/40; D03d 27/100 US. Cl. 161-67 2 Claims ABSTRACT OF THE DISCLOSURE A method for making an elastomer-backed carpet having a backing of absorbent paper impregnated with an elastomer.
The invention relates to a process for producing elastomer-backed carpets, and to the new and useful carpets that can be produced thereby.
Conventional carpets are made by tufting fibers onto a primary backing, and then, in most cases, cementing a secondary backing behind the primary backing. Both the primary and the secondary backings are often made of jute, a material that has a number of inherent disadvantages. For instance, most of the jute grown in the world comes from the Indian sub-continent, primarily Pakistan, and political uncertainties and other factors cause serious jute shortages from time to time. Excessive exposure to moisture will cause jute to shrink and, eventually, to decay since it is of vegetable origin. Thus, there is an understandable desire to substitute other materials for jute in either the primary or the secondary backings, or both. Among the materials that have been proposed as backings for carpets have been resilient plastics such as foam rubber, flexible urethane foam, foamed vinyl chloride resins, and the like. The use of such elasto-plastic backings provides a cushioning effect on the carpet as well as other advantages such as shrink resistance, freedom from the uncertainties of the jute market, moisture resistance, and the like. The present invention relates to an improved method for providing an elasto-plastic backing for a carpet and the improved carpets that are made by the process of the invention.
The process of the invention comprises the steps of:
(a) Depositing a layer of reactive liquid between a layer of pile faced fabric and a layer of absorbent paper to form a sandwich wherein the said layer of reactive liquid is in intimate contact with both the back of said pile faced fabric and said absorbent paper, and
(b) Curing said reactive liquid to a resilient material, thus forming a carpet having a resilient backing.
The understanding of the invention is facilitated by reference to the accompanying drawings.
FIGS. 1, 2 and 3 are schematic diagrams of alternative methods for carrying out the process of the invention. In FIG. 1, the reactive liquid is deposited from the reactive liquid feed system 11 as a thin layer 26 onto the top side of a moving layer of absorbent paper 12 which is fed from paper feed out roll 13. After the level of the thin layer of reactive liquid 26 is adjusted by suitable means such as doctor blade 14, a moving layer of pile faced fabric 15 from feed out roll 16 is brought into contact with the adjusted layer of reactive liquid 27 with the pile facing up and the back of the pile faced fabric 15 in contact with the adjusted layer of reactive liquid 27. The sandwich consisting of the reactive liquid layer 27 between the absorbent paper 12 and the pile faced fabric 15 is then passed under a squeeze roll and into a curing zone 17, which can be a forced draft oven 28 as depicted in FIG. 1. The reactive liquid is cured to a elasto-plastic material 29 in the curing zone 17, after 3,519,526 Patented July 7, 1970 'ice which the carpet 18 is recovered by a procedure such as winding onto a take up roll 19. Conventional carrier means, such as endless belt 21 can be provided for facilitating the motion of the layers in the process of the invention.
FIG. 2 depicts an alternate manner for carrying out the invention wherein curing zone 17 is a hot plate 30, optionally with a canopy 24, and wherein the layers are moved through the process of the invention by a pair of driven draw rolls 22.
FIG. 3 depicts still another alternative method for carrying out the process of the invention. In this method, the? paper 12 is fed from the top and the pile faced fabric 15 from the bottom. Also, the curing zone 17 consists of electric radiant heaters and reflectors 25, and the carrier means is a tenter frame table 23.
A major point of novelty of the invention resides in the use of absorbent paper such as crepe paper, or the like. The paper absorbs some of the reactive liquid to an extent sufiicient to become impregnated with the liquid. After the liquid cures to an elasto-plastic material, the paper is no longer identifiable as such because it is permeated or saturated with the cured elasto-plastic. In a preferred aspect of the invention, embossed crepe paper is used as the absorbent paper. When such embossed crepe paper is used, the carpet product of the invention has the embossed pattern on the back surface, even though the paper is no longer apparent as a separate layer. This is highly advantageous because in many cases it is desired to have an embossed pattern on the back of a carpet for aesthetic and non-slip purposes, and the like. It is desirable that the absorbent paper have an elongation in all directions of at least 10 percent and preferably of about 15 percent.
The pile faced fabric employed can be conventional carpeting material having fibers tufted onto a primary backing of jute, paper, cloth, plastic, or the like.
The reactive liquid employed in the process of the invention is a material that reacts or cures to a resilient plastic composition. For instance a highly desirable type of reactive liquid is one that cures to form a urethane polymer elastomer, which can be cellular (foamed) or non-cellular, whichever is desired. As is well known in the art, a urethane foam or elastomer is formed by reacting one or more polyols and optionally a curing agent such as a diamine with one or more organic polyisocyanates. Present technology relating to urethane foams and elastomers is summarized in Polyurethanes-Chemistry and Technology, Part II Technology by Saunders and Frisch, published in 1964 by Interscience Publishers, New York. The urethane elastomers employed are preferably non-foamed or only slightly expanded.
A useful reactive liquid urethane elastomer-forming formulation contains as the polyol a mixture of polypropylene glycol having a molecular weight of between about 425 and about 4000 and a short chain polyol having a molecular weight of about 60 to about 700 and functionality of 3 or higher, and as the prepolymer the reaction product of a polyisocyanate and a short chain polyol having a molecular weight range of between 60 and 700 in a molar ratio of about 2:1 to 6:1 (isocyanatez'polyol). The organic polyisocyanate is employed in about 1-20 percent stoichiometric excess as is customary in the art. It is also preferred to employ a filler such as clay in the reactive liquid formulation. The use of fillers, pigments and dyes in urethane elastomer formulations is well known.
Curing of the urethane-forming reactive liquid to an elastomer can be accomplished by heating to an elevated temperature for a few minutes, for example, to -160 C. for from about two to about thirty minutes. The curing reaction is facilitated by employing a catalytic quantity of a catalyst. Known catalysts include dibutyltin dilaurate, stannnous octoate, lead octoate, and zinc dimethyldithiocarbamate. Especially useful catalysts are those which are relatively inactive at room temperatures, but which become active when heated to, for instance, 50 C. or more. An example of such a heat sensitive catalyst is Zinc dimethyldithiocarbamate.
The reactive liquid is normally employed in an amount such that the cured resilient plastic material has a thickness of from about one-eighth to about three-eigths of an inch, although greater or lesser thicknesses can be-employed if desired. The reactive liquid is metered into the process of the invention by conventional means. i
The carpets of the invention have enhanced utility for most uses of carpets as a result of the desirable properties of the resilient plastic backing. For instance, if the tufted fibers and the primary backing are synthetic materials, the carpets of the invention can be employed outside. The resilient backing lessens or eliminates the need for padding, in many cases.
EXAMPLE To one tank of a machine designed to meter two streams of liquid reactant continuously to a mixing head was charged about 20 pounds of a suitable polyol mixture having a hydroxyl number of about 91. The polyol mixture consisted of about 40 parts of a polypropylene glycol of about 1200 molecular weight, about 10 parts of a propylene oxide adduct of sorbitol having a hydroxyl number of 490, and 50 parts of a silica clay filler. To the tank was also added a lead catalyst (lead octoate) to make about 0.5% catalyst on the weight of contained polyol.
To the second tank of the machine was charged about 10 pounds of an activator system consisting of about 84 parts of tolylene diisocyanate prereacted with about 16 parts of dipropylene glycol and having about 30 percent free isocyanate.
Ingredients in the storage tanks were metered continuously to a suitable mixing head in the ratio of about 350 parts of the polyol mixture to about 90 parts of the toluene diisocyanate prepolymer. The reacting mixture of polyol and isocyanate was discharged continuously to an absorptive substrate consisting of embossed, creped kraft paper. The mix was spread evenly in a film about .070 inch thick on the embossed, creped kraft paper as it was drawn continuously under a suitable doctor blade. The tufted carpet to be backed was pressed immediately onto the uncured urethane film and held in place by an applied weight as the laminated structure was drawn continuously over a smooth, internally heated metal plate. The metal plate had a surface temperature of about 120- 130 C. After about minutes the cured laminate was removed from the hot surface and cooled.
The finished product made as described in this example had many very useful features that compared favorably with a sample of commercial carpet having woven jute as secondary backing. A tensile force of 204 pounds was re quired to rupture a test specimen one inch Wide, a force of 48 pounds was required to propagate a tear notch in a tongue tear test and a pull of 25 pounds was required to dislodge a tuft in a tuft lock test. These values compare with 250 lbs., pounds and 19 pounds respectively for these tests on the commercial carpet. All of these values are considered by the trade to be adequate. However the urethane backed carpet is impervious to moisture and to drycleaning fluids while the commercial carpet is very susceptible to damage by contact with these fluids. In these tests the bond between layers of jute in the commercial carpet is broken down almost completely and tuft lock is seriously impaired by water and by cleaning solvents.
The urethane backed carpet compares very favorably with the commercial carpet in handle, heft and attractive appearance.
What is claimed is:
1. A process for producing carpeting having a resilient backing which comprises the steps of depositing a layer of a liquid' urethane polymer-forming composition between a layer of pile faced fabric and a layer of embossed crepe paper to form a sandwich wherein said layer of liquid urethane polymer-forming composition is in intimate contact with the back of said pile faced fabric and with said embossed crepe paper, andcuring said liquid urethane polymer-forming composition to a resilient material to form carpeting comprising a pile faced fabric having bonded thereto a resilient backing, wherein said embossed crepe paper is no longer identifiable as such, said carpeting thus having a non-skid backing.
2. The carpeting produced by the process of claim 1.
References Cited UNITED STATES PATENTS 2,341,979 2/1944 Cunnington 156-79 X 2,641,296 6/ 1953 Marco 15679 X 2,787,571 4/1957 Miller 16l67 X 3,061,475 10/1962 Wallace 15679 X 3,123,508 3/1964 Waugh 15679 X 3,175,936 3/1965 Squier et a1 15679 3,219,502 11/1965 Willy 15679 3,285,800 11/1966 Bartell et al 161l59 X 3,257,483 6/1966 Eberle 156-79 X 3,293,094 12/ 1966 Nairn et al. 15679 FOREIGN PATENTS 494,301 10/ 1938 Great Britain.
JOHN T. GOOLKASIAN, Primary Examiner C. B. COSBY, Assistant Examiner US. Cl. X.R.