WO1994002678A1 - Carpet backing latex composition and process for production - Google Patents

CARPET BACKING LATEX COMPOSITION AND PROCESS FOR PRODUCTION

This invention relates to fiber-containing latex compositions for carpet 5 backcoating and a process forthe production thereof.

Carpets are backcoated to make them more durable and readily handl>sd. A good backcoating system serves to anchor the pile and prevent pull-out of the tufts, minimizes loosening of the pile, reduces shedding, provides dimensional stability and prevents fraying during cutting. 1 u Tufted carpets are backcoated with natural or synthetic latexes which provide excellent pile anchorage and dimensional stability. A secondary backing such as jute, woven polypropylene, non-woven polypropylene, woven or non-woven polyester, scrim, or other material may be laminated to the tufted carpet to further stabilize the product.

Shearing machines are used in the carpet industry to trim the carpet face fiber to 1 5 a uniform height on cut pile finished carpet, and to clean and remove extraneous fiber from the carpet face for textured and loop pile finish carpets. Waste fiber from 0.001 inch to 0.5 inch (0.0004 cm to 0.2 cm) in length and composed of, for example, wool, nylon, polypropylene, polyester, acrylic, rayon or cotton is collected by vacuum from the shearing machines.

The shearing waste fibers are difficult to recycle because they are low in density 20 and, thus, bulky. Also the fibers are contaminated with shearing machine lubricant and the fibers may be of varying lengths and colors. Currently this waste fiber is disposed of via landfill This method is becoming less environmentally satisfactory and more costly. A wide variety of waste fibers that are by-products of other manufacturing processes present similar problems for their disposal or utilization. *-5 it would be desirable to be able to use these shearing waste fibers in some way, and it would be particularly advantageous if these and other waste fibers could be used in the manufacture of carpet.

Previous aitempts to utilize small fibers in carpet backing adhesive compositions have met with failure, primarily due to plugging of equipment such as froth machines with the - u fibers. It would be desirable to be able to include a fibrous component in carpet backing adhesive compositions to improve the physical characteristics, such as tuft bind, of the finished carpet

The present invention provides a carpet backing latex composition comprising an emulsified polymer, non-cellulosic fibers or a mixture of non-cellulosic fibers and cellulosic -?-i fibers, and an effective amount of at least one dispersant for the fibers.

The invention further provides a process for making a carpet backing latex composition comprising adding a dispersant to a carpet backing latex and then adding non- -cellulosic fibers or a mixture of non-cellulosic fibers and cellulosic fibers to the latex with slow agitation.

In another embodiment the instant invention relates to a carpet structure comprising: a primary carpet backing; and attached thereto a face pile; and, optionally, a secondary carpet backing, wherein attachment of the face pile to the primary carpet backing, and, optionally, to the secondary carpet backing is accomplished by means of the fiber-containing carpet backing latex composition.

The process of the present invention provides for the recycling of carpet shearing waste fibers, other waste fibers, non-waste fibers including synthetic or natural virgin fibers, and mixtures thereof into the CARPET LATEX for carpet finishing while using normal processing equipment. By using a dispersant, preferably a polyphosphate dispersant or a combination of a low molecular weight polyacrylate dispersant with a phosphate dispersant, the fiber can be introduced into the latex such that it will be passed through a froth machine without plugging. When applied to the carpet, the physical properties of tuft bind and/or delamination are improved over similarly produced product without the fiber.

Latexes useful in the practice of the present invention include any of those latexes normally used in floor covering applications, such as, for example, styrene butadiene latexes, styrene butadiene vinylidene chloride latexes, polyvinylchloride latexes, butadiene vinylidene chloride latexes, ethylene vinyl chloride, ethylene vinyl acetate and acrylate containing latexes. The latex solids advantageously comprise from 5 to 99.5 weight percent, preferably from 10 to 75 weight percent of the total compound solids. Dispersants useful in the practice of the present invention include, for example, tetrasodium pyrophosphate, tetra potassium pyrophosphate, sodium hexametaphosphate, diammonium phosphate, trisodium pyrophosphate, disodium pyrophosphate, tri-, tetra- and septaphosphate, and polyacrylate dispersants such as, for example, ammonium polyacrylate, sodium polyacrylate, polyacrylic acid, polyacrylate blends and lignosulfonate/polyacrylate blends. The dispersants are advantageously present in amounts of 0.01 to 2.0 weight percent, preferably 0.05 to 0.12 weight percent based on total compound solids. An effective amount of the dispersant is that amount, which, when added to the carpet backing latex composition, will allow the fiber-containing carpet backing latex composition to pass through a froth machine, filters and other associated equipment without plugging it and with minimal build- UP-

Fibers useful in the practice of this invention include, for example, those composed of nylon, polyester, polyethylene, cellulose, wool, acrylate, polypropylene, fiber glass and mixtures thereof. Such fibers advantageously have lengths up to approximately 3.0 mm. Preferably all or part of the fibers used are waste fibers, since the utilization of waste fibers is economically advantageous, while simultaneously reducing the problem of their disposal. More preferable is the utilization of shearing waste fibers, since these fibers are readily available at most carpet manufacturing facilities. Their utilization converts a waste by- -product of the manufacturing process, disposal of which is becoming a serious problem, into an asset.

The term "waste fiber" is meant to include fiber-containing materials which up to now have been considered to be by-products of industrial or manufacturing processes and which require disposal. An example of this is carpet shearing waste fibers. The term "non- -waste fiber" is meantto include virgin fibers aswell as various normally recycled fibrous materials.

In addition, fillers such as, for example, calcium carbonate, clay, calcium sulfate (gypsum), aluminum silicate, and alumina trihydrate, and sur actants such as, for example, ammonium lauryl sulfate, sodium lauryl sulfate, lauryl alcohols and anionic or nonionic surfactants, and disodium N-octadecyl sulfosuccinamate, and thickeners such as, for example, sodium polyacrylate, cellulosics, silicas and alkali swellables may be employed to provide the desired processing viscosity.

Latexes useful in this invention generally contain antioxidants, such as, for example, a hindered phenolic antioxidant in combination with a thioester synergist, such as, for example, Aquamix 494™ from Harwick Chemical, Akron, Ohio; preservatives such as, for example, Proxcel™ GXL available from ICI Americas, Wilmington, Delaware, and 1,2- -benzisothiazo-3-one; and chelating agents such as sodium ethylenediamine tetraacetic acid; and a dispersant, such as, for example, tetrasodium pyrophosphate.

In another embodiment the instant invention relates to a process for making a carpet backing latex composition comprising adding a dispersant to a carpet backing latex and then adding fibers to the latex with slow agitation. Preferably the dispersant is a low molecular weight polyacrylate dispersant and a polyphosphate dispersant. It may also be advantageous to extend the latex with a preferred filler, such as, for example, calcium carbonate, barium sulfate, caicium sulfate, aluminum silicate and alumina trihydrate. A surfactant may also be added to the composition, and preferred surfactants are sodium lauryl sulfate, ammonium lauryl sulfate, lauryl alcohol and disodium N-octa-decyl sulfosuccinamate. The latex composition is then added to a conventional froth machine and processed to entrain approximately 60 percent air and the frothed mixture is applied to an unfinished carpet using conventional coating technology. Floor covering made with the fiber-containing carpet backing latex compositions produced by the process of the instant invention is characterized by increased tuft bind of the finished carpet.

The invention is further illustrated by the following examples: EXAMPLE 1

To 100.0 dry parts per hundred solids (phr) of Dow Chemical's styrene butadiene latex LXC 8303 NA containing from 0.01 to 1.0 phr resin solids of an antioxidant, from 0.01 to 0.5 phr resin solids of a preservative, from 0.01 to 2.0 phr resin solids of a chelating agent and 0.01 to 2.0 phr resin solids of a polyphosphate dispersant and having a pH in the range of 7.2 to 9.5 was added 0.5 dry phr Nopcosperse™ (polyacrylate dispersant), available from Napco Chemical Company, and 20 dry phr shearing waste fiber (nylon/polyester blend). The mixture was finished with the following formulation:

Dry Phr Titan™ 200 Calcium carbonate 500.00

Astromid™ 18 (N-octadecyl-sulfosuccinamate)

Froth Stabilizer 0.36

Emersal™ 6431 (Ammonium lauryl sulfate) Froth Aid 0.20 Jorco™ 11 1 1 (Polyacrylate) Thickener 0.50 to obtain a solids content of 82 weight percent and a viscosity of 12,500 cps Brookfield RVT #5 spindle at 20 rpm.

A control sample without the Nopcosperse™ 44 and shearing waste was also made. These compounds were frothed using Cowie & Riding CR-Twin froth machine to a

67, ± 3 g/3 oz. (757 ± 34 g/l) cup weight and mechanically applied to a 24 oz./sq. yd. (0.8/Kg/m2) straight stitch, level loop nylon carpet. The results were normalized to a constant 26.0 oz./sq. yd. (0.88 Kg/m2) for comparison at equal coat weights:

500 Load The Invention Control

Tuft bind lb. (Nτ) 13.9 (61.9) 16.3 (72.5)

Scrim adhesion 1.40 (245) 1.1 1 (194.3)

5 high peaks Ib./in. (Nτ/m) When Nopcosperse™ 44 was eliminated from the shearing waste sample, or reduced to 0.25 phrthe sample would not pass through the froth machine so no carpet could be produced. EXAMPLE 2

2)

Example 1 was repeated except that the calcium carbonate level was reduced to 480 dry phr and the results were normalized to a constant 26.0 oz./sq. yd. (0.88 Kg/m

To 100.0 dry phr of the latex employed in Example 1 was added 1.0 dry phr sodium hexametaphosphate (SHMP) dispersant and 5 phr of shearing waste fiber (nylon- polyester blend). The mixture was finished with the following formulation:

Dry phr Georgia Marble 200-D Calcium Carbonate 350.00

Tergitol ™ 15 S 7 (Ci 1- 15 Secondary alcohol ethoxylate) Penetrant 0.50

Stanfax™ 318 (Disodium N-octadecyl sulfo succinamate) Froth Stabilizer 0.15

Witcolate™ 6431 (Ammonium lauryl sulfate)

Froth Aid 0.40

Jorco™ 606 Polyacrylate Thickener 0.40 to obtain a solids content of about 80 weight percent and a viscosity of about 8,000 cps Brookfield RVT #5 at 20 rpm. A control sample without the SHMP and shearing waste was also made using the above formulation. These mixtures were frothed using a Cowie & Riding CR- Twin froth machine toa 76.3 ± 0.6 g/3 oz. (862 ± 6.8 g/l) cup weight and mechanically applied to a 24 oz./sq. yd. (0.81 Kg/m2) straight stitch, level loop Nylon carpet. The results were as follows:

Control Invention

Coat Weight oz./sq. yd.

(Kg/m2) 21.7 (0.74) 22.6 (0.77) Tuft bind lb. (Nτ) 15.0 (66.8) 17.2 (76.5) Scrim adhesion 2.79 (488.3) 3.06 (535.5)

5 high peaks Ib./in. (Nτ/m)

EXAMPLE 4

Example 3 was repeated except to use 0.38 phr Colloid™ 208 polyacrylate dispersant in place of the SHMP.

Example 3 was repeated except that the polyphosphate dispersant that is used in the production of the latex was replaced with 0.2 phr of Colloid™ 208 polyacrylate dispersant. No additional dispersant was added. 0 The results were:

Coat weight oz./sq. yd. (Kg/m2) 21.4 (0.73)

Tuft bind lb. (NT) 15.3 (68.1)

Scrim adhesion 2.87 (502.3)

5 high peaks Ib./in. (N-r/m) 5 EXAMPLE 6

The addition of 0.38 phr of additional Colloid™ 208 polyacrylate dispersant to the mixture of Example 5 gave the following results:

Coat weight oz./sq. yd. (Kg/m2) 21.3 (0.72)

Tuft bind lb. (Nτ) 17.2 (76.5) 0 Scrim adhesion 2.71 (474.3)

5 high peaks Ib./in. (N-r/m)

Using the following formulation other latexes are prepared, frothed and mechanically applied to various carpets as in Example 1.

Latex (dry) 100 phr

Water to give 82% total solid 5 Polyacrylate dispersant 0.5 phr

Calcium carbonate filler 500 phr

Shearing Waste Fiber (dry) 20 phr

Astromid 18, Froth stabilizer 0.36 phr

Witrolate 6431 , Froth Agent 0.30 phr

Polyacrylate thickener to give a viscosity of 12,000-13,000 cps Brookfield #5 at 0 20 rpm.

The latexes employed are vinylidene chloride styrene butadiene polymer; vinylidene chloride butadiene polymer; styrene acrylate polymer; ethylene vinyl acetate polymer; ethylene vinyl chloride polymer and vinyl chloride polymer. In addition other ^ formulations containing calcium sulfate, aluminum silicate, barium sulfate and alumina trihydrate are employed as the filler and other surfactants such as ammonium lauryl sulfate, lauryl alcohols and disodium N-octa-decyl sulfosuccinamate are employed with similar beneficial results.

Various modifications may be made in the present invention without departing from the spirit or scope thereof as will be readily understood by those skilled in the art.