Spunbonded nonwoven fabric

Abstract

A spunbonded nonwoven fabric having a silicone-glycol copolymer thereon is disclosed. Of particular interest is the spunbonded nonwoven polypropylene fabric used as carpet backing.

Description

A spunbonded fabric is a continuous filament nonwoven fabric made by combining all the steps from polymer to finished fabric in one process. Curtains of filaments are extruded, drawn, forwarded to a belt and combined there into a web with the required design. The web is then bonded and can be finished in the same single process.

The basic process steps for making spunbonded nonwoven fabrics are quite simple. Multiple spinnerettes extrude large numbers of filaments which are drawn and oriented by rolls or high velocity air, in groups and then projected in some desired geometrical array onto a slower moving porous belt provided with suction to hold down the filaments. The belt then carries the web to a bonding operation (heater rolls, binder application, etc.) and then to a series of further operational steps in the process. These latter can be the traditional textile finishing steps such as printing or embossing when process speeds are compatible. From there the fabric is inspected, wound up and packaged.

There are many spunbonded nonwoven fabrics available commercially. Examples of such materials are those based on polyesters, polypropylene, polyethylene, nylon or combinations of the foregoing. The particular fiber type used will depend on the nature of the finished product one wishes to make. End uses for spunbonded nonwoven fabrics ranges from such things as book covers, to clothing fabric to carpet backing.

This invention relates to a spunbonded non-woven fabric having thereon a silicone-glycol copolymer having the general formula (CH.sub.3).sub.3 SiO{(CH.sub.3).sub.2 SiO}.sub.x -{(CH.sub.3)GSiO}.sub.y Si(CH.sub.3).sub.3 wherein G is a radical of the structure --R(OC.sub.3 H.sub.6).sub.z OH, R is an alkylene radical containing from 1 to 18 carbon atoms, x has an average value of from 40-90, y has an average value of from 1-10, and z has an average value of from 1-10.

This invention also relates to a spunbonded nonwoven polyolefin fabric having thereon a silicone-glycol copolymer having the general formula set forth above.

This invention still further relates to a spunbonded nonwoven polypropylene carpet backing having thereon a silicone-glycol copolymer having the general formula set forth above.

Other aspects of this invention and the objects thereof will be apparent to those skilled in the art from the following more detailed disclosure and description of the invention.

One of the most significant commercial uses of spunbonded nonwoven fabric has been the use of spunbonded nonwoven polypropylene as a carpet backing. The spunbonded nonwoven polypropylene fabric has been substituted for the woven jute backing materials that have been used heretofore in the production of carpets. In this process the carpet yarn is threaded through a large needle which punches through the spunbonded nonwoven polypropylene fabric which is designated as the primary backing. A looper device catches the yarn on the under side to form loops or tufts and the needle is then withdrawn. The backing fabric is then advanced and the cycle is repeated to form additional tufts. The tufts make up the pile or face of the final carpet. A commercial tufting machine may have up to 2,400 needles in a row all working in unison to make a carpet up to 15 feet in width. The primary backing, which is the spunbonded nonwoven polypropylene, is the structural base of the carpet. It hold the tufts in place and provides dimensional stability and strength to the carpet. To the back of the tufted spunbonded nonwoven polypropylene there is added a glue or latex coating, for example, natural rubber or styrene butadiene rubber, which coating firmly anchors the tufts in place and keeps them from pulling out. A final jute or foam back may then be placed on the carpet to act as a pad or cushion. In the development of this use of the spunbonded nonwoven fabric it was found that the needles did extensive damage to the carpet backing on penetration of the structure resulting in a large loss in strength during the tufting process. It was then discovered that by the application of a methyl hydrogen polysiloxane fluid to the spunbonded nonwoven polypropylene carpet backing that the penetration of the needle through the carpet backing in the tufting process was facilitated and that the fiber damage and loss of strength which resulted therefrom could be significantly reduced.

A number of difficulties were encountered, however, with the use of the methyl hydrogen polysiloxane fluid. The most severe of these difficulties was encountered during the dyeing process for carpets employing the spunbonded nonwoven polypropylene carpet backing. More specifically, in the Kuster's continuous dyeing process (foam dyeing with steam) for carpets the methyl hydrogen polysiloxane fluid on the carpet backing reduced the foam level in the system resulting in non-uniform dyeing of the carpet. Other problems were the reduced wettability of the carpet, a tendency for the carpet to float in aqueous systems, the relative flammability of the carpet, and the high cost of the methyl hydrogen polysiloxane fluid employed.

It has been found in accordance with this invention that when the silicone-glycol copolymer having the general formula set forth above is employed in place of the methyl hydrogen polysiloxane fluid employed heretofore that not only is good lubricity obtained facilitating needle penetration through the carpet backing during the tufting process but also the problems involved in the dyeing of the carpet in the Kuster system are significantly reduced if not entirely eliminated.

As can be seen from the general formula set forth above the silicone-glycol copolymer which produces the results and advantages of this invention is a trimethylsilyl endblocked siloxane which can contain from 40-90 dimethylsiloxane units therein and from 1-10 methylglycol units. The copolymers useful herein are water insoluble. The water soluble silicone-glycol copolymers wet the latex backing too much allowing it to penetrate the polypropylene backing too far resulting in a poor carpet.

The glycol units are represented in the general formula by the symbol G which is more specifically defined as having the structure --R(OC.sub.3 H.sub.6).sub.z OH. The R radical in this structure can be any alkylene unit containing from 1-18 carbon atoms. Thus, for example, R can be a methylene, ethylene, propylene, butylene, isobutylene, hexylene, decylene, dodecylene or an octadecylene radical. The glycol portion represented by the (OC.sub.3 H.sub.6) portion of the structure is as can be seen from the formula a propylene glycol. This glycol is hydroxyl endblocked or as is commonly stated in the art an uncapped glycol. As indicated there can be an average of from 1-10 propylene oxide units making up the glycol portion of the structure, i.e., z has an average value of from 1-10. It is preferred, however, that z have an average value of from 1-5.

The methyl-glycol units in the silicone-glycol copolymer can range from an average value of 1-10 which is to say y can have a value from 1-10. However, it is generally preferred that the average value of y be in the range of from 1-5. The subscript x can have an average value of from 40-90 but preferably ranges in value from 50-75. The subscript x defines the number of dimethylsiloxane units in the silicone-glycol copolymer.

Based on the disclosure of the structure herein the preparation of the silicone-glycol copolymer set forth above will be obvious to those skilled in the art of the preparation of such materials.

The silicone-glycol copolymer can be applied to the spunbonded nonwoven fabrics by any of the well known techniques for applying finishes to fabrics and textile materials. However, the use of a gravure roll is the preferred method at this time. The amount applied to the fabric will depend to some extent on the desired results but generally speaking will fall within the range of 0.1-10 percent by weight based on the weight of the fabric. However, it is believed that generally an amount in the range of 0.5-5 percent will meet most needs. The silicone glycol copolymer can be applied to the fabric neat or in the form a solution in a suitable carrier such as water (emulsified), the lower alcohols, ethers, ketones and other water compatible solvents.

Now in order that those skilled in the art may better understand how the present invention can be practiced the following examples are given by way of illustration and not by way of limitation. All parts and percents referred to herein are by weight and all viscosities measured at 25.degree.C. unless otherwise specified.

EXAMPLE 1

A silicone-glycol copolymer having the general formula ##SPC1##

was applied to a spunbonded nonwoven polypropylene carpet backing using a gravure roll. A pickup of about 1% of the silicone-glycol copolymer, based on the weight of the carpet backing, was achieved. A piece of tufted carpet was then made from this treated backing. It was found that the needle lubricity provided by this silicone-glycol copolymer during the tufting process was equivalent to that obtained with the presently used methyl hydrogen polysiloxane fluid at the same 1% add-on level.

A latex rubber backing was placed on the above prepared carpet. The latex was found to penetrate about 35% of the thickness of the spunbonded nonwoven polypropylene whereas the latex penetrates about 30% of the thickness when the spunbonded nonwoven polypropylene has been treated with the methyl hydrogen polysiloxane fluid. Both of these levels of penetration are within commercially acceptable levels.

EXAMPLE 2

The silicone-glycol copolymer of Example 1 was applied via gravure roll to a spunbonded nonwoven polypropylene carpet backing with a 4% pickup or add-on being obtained. A piece of tufted carpet was then made from this treated backing and allowed to age for seven weeks before dyeing it by the Kuster process. In the dyeing process the foam started in 5 seconds, reached a height of 2 inches, had a life of 120 seconds, and was of very good quality. In short, no problem was encountered in the dyeing of this carpet.

By comparison the spunbonded nonwoven polypropylene carpet backing having a 3% add-on of a methyl hydrogen polysiloxane fluid by gravure roll and made into a tufted carpet, could not be dyed by the Kuster process because no foam formed due to the presence of this siloxane. This test was conducted after the treated carpet had aged one week.

Note that more of the silicone-glycol copolymer of this invention was added on and hence its antifoaming action would have been expected to be more severe. And secondly, the sample of this invention was aged longer as the spunbonded nonwoven polypropylene carpet backing tends to become more difficult to dye with age after finishing.

EXAMPLE 3

When the following silicone-glycol copolymers are substituted for the one used in the preceding examples, a spunbonded nonwoven polypropylene carpet backing is obtained which provides excellent needle lubricity during tufting, and which can be dyed by the Kuster process without causing significant defoaming. ##SPC2##

EXAMPLE 4

When 2% of a silicone-glycol copolymer having the general formula ##SPC3##

is applied to a spunbonded nonwoven polyester fabric or to a spunbonded nonwoven polyethylene fabric excellent finishes are obtained.

Claims

1. A spunbonded nonwoven fabric having thereon a silicone-glycol copolymer having the general formula

(CH.sub.3).sub.3 SiO{(CH.sub.3).sub.2 SiO}.sub.x {(CH.sub.3)GSiO}.sub.y Si(CH.sub.3).sub.3

wherein

G is a radical of the structure --R(OC.sub.3 H.sub.6).sub.z OH,

R is an alkylene radical containing from 1 to 18 carbon atoms,

x has an average value of from 40 to 90,

y has an average value of from 1 to 10, and

2. A fabric as defined in claim 1 wherein R contains from 3 to 6 carbon atoms, x has an average value from 50 to 75, y has an average value from 1

3. A fabric as defined in claim 2 wherein R contains 3 carbon atoms, x has an average value of about 67, y has an average value of about 3, and z has

4. A fabric as defined in claim 1 which is selected from the group

6. A fabric as defined in claim 5 which is selected from the group

9. A fabric as defined in claim 8 wherein R contains from 3 to 6 carbon atoms, x has an average value from 50 to 75, y has an average value from 1

10. A fabric as defined in claim 9 wherein R contains 3 carbon atoms, x has an average value of about 67, y has an average value of about 3, and z has

12. A fabric as defined in claim 11 wherein R contains from 3 to 6 carbon atoms, x has an average value from 50 to 75, y has an average value from 1

13. A fabric as defined in claim 12 wherein R contains 3 carbon atoms, x has an average value of about 67, y has an average value of about 3, and z has an average value of about 2.5.