BONDED NONWOVEN SHEET BEARING A LUBRICATING COMPOSITION OF A LIQUID POLYSILOXANE AND A LIQUID POLYOXYPROPYLENE COMPOUND
United States Patent 3772069
A bonded nonwoven sheet of synthetic organic fibers having applied thereon a lubricating composition comprising 3-50 percent by weight of liquid polysiloxane and 50-97 percent by weight of defined liquid polyoxypropylene compound, in an amount such that the quantity of polysiloxane present on the sheet is in the range of about 0.06 to 0.8 percent by weight. This lubricated nonwoven fabric is suitable as a primary carpet backing which has high strength after tufting and performs acceptably in continuous dyeing operations.
US Patent References:
Lubricated polypropylene polyethylene self-bonded nonwoven carpet backing
Jung - May 1967 - 3322607
PROCESS OF IMPROVING THE RESISTANCE OF SOILING OF MELT SPUN FIBERS
Smith - November 1971 - 3620823
Cleaning compositions
Terry - October 1960 - 2955047
Treatment of textile materials
Dawson et al. - July 1964 - 3140198
Liquid cleaner and polisher and method of compounding the same
Guss - July 1956 - 2757094
Lubricated polypropylene polyethylene self-bonded nonwoven carpet backing
Jung - May 1967 - 3322607
PROCESS OF IMPROVING THE RESISTANCE OF SOILING OF MELT SPUN FIBERS
Smith - November 1971 - 3620823
Cleaning compositions
Terry - October 1960 - 2955047
Treatment of textile materials
Dawson et al. - July 1964 - 3140198
Liquid cleaner and polisher and method of compounding the same
Guss - July 1956 - 2757094
Application Number:
05/125355
Publication Date:
11/13/1973
Filing Date:
03/17/1971
View Patent Images:
Export Citation:
Assignee:
E. I. du Pont de Nemours and Company (Wilmington, DE)
Primary Class:
Other Classes:
428/451, 106/287.260, 428/523, 442/171, 106/287.140, 252/8.840
International Classes:
D06M15/643; D06M15/647; D06M15/37; B32B27/06; D06M13/00
Field of Search:
117/138.8E,139.5CQ,14R 252/8.9 106/287SB
Primary Examiner:
Martin, William D.
Assistant Examiner:
Childs, Sadie L.
Claims:
What is claimed is
1. A bonded nonwoven synthetic organic fiber sheet to which has been applied a lubricating composition consisting essentially of 3-50 percent by weight of a liquid polysiloxane selected from the group of polymethyl hydrogen siloxane and polydimethyl siloxane and 50-97 percent by weight of a liquid polyoxypropylene compound having a viscosity of at least 100 centipoises at 25°C. and selected from the group of polyoxypropylene glycol and the monobutyl ether thereof, said composition being present in an amount such that the quantity of polysiloxane on the sheet is in the range of about 0.06 and 0.8 percent by weight.
2. The sheet of claim 1 wherein the synthetic organic fibers are continuous polypropylene filaments.
3. The sheet of claim 2 wherein the polysiloxane is polymethylhydrogensiloxane.
4. The sheet of claim 3 wherein the lubricating composition comprises 5-20 percent by weight of polysiloxane and 80-95 percent by weight of polyoxypropylene compound.
1. A bonded nonwoven synthetic organic fiber sheet to which has been applied a lubricating composition consisting essentially of 3-50 percent by weight of a liquid polysiloxane selected from the group of polymethyl hydrogen siloxane and polydimethyl siloxane and 50-97 percent by weight of a liquid polyoxypropylene compound having a viscosity of at least 100 centipoises at 25°C. and selected from the group of polyoxypropylene glycol and the monobutyl ether thereof, said composition being present in an amount such that the quantity of polysiloxane on the sheet is in the range of about 0.06 and 0.8 percent by weight.
2. The sheet of claim 1 wherein the synthetic organic fibers are continuous polypropylene filaments.
3. The sheet of claim 2 wherein the polysiloxane is polymethylhydrogensiloxane.
4. The sheet of claim 3 wherein the lubricating composition comprises 5-20 percent by weight of polysiloxane and 80-95 percent by weight of polyoxypropylene compound.
Description:
BACKGROUND OF THE INVENTION
The invention relates to treated continuous filament nonwoven materials which are suitable as tufting substrates in the production of tufted carpets. Jung, in U.S. Pat. No. 3,322,607, has disclosed continuous filament nonwoven materials which can be used as primary carpet backings in the production of tufted carpets. The same patent also discloses that it is necessary to treat these products with a lubricant prior to tufting, and discloses the use of polysiloxanes as tufting lubricants.
The production of tufted carpets, usually includes a dyeing operation to dye the face yarns. Conventionally, this dyeing operation was effected in dye-becks in which the carpet was formed into a continuous belt and cycled in the dye-beck until the correct face yarn color had been obtained. More recently, however, continuous dyeing processes have been developed in which an undyed, tufted primary carpet backing enters at one end of an apparatus and exits at the other end with dyed face yarns. A typical continuous dyeing process comprises the steps of 1) application of about 100 percent wet pickup of a prepad solution to wet all carpet face fibers; 2) application of about 400 percent of a dye solution which is metered onto the carpet face by doctoring the solution from a roll rotating in the dye solution; 3) steaming the carpet at 100°C. for about 10 minutes; 4) scouring the carpet; 5) removing excess water with suction; and 6) drying the carpet in an oven.
The prepad solution generally contains a pH adjustor and a thickener to keep the solution on the carpet face fibers. The dye solution contains dyes, foaming agent, pH adjustors, and a thickener. The steaming operation is probably the most critical of the entire process. In this operation, condensation of water vapor on the carpet causes a large generation of foam on the carpet surface. This foam distributes the dyestuff evenly throughout the face yarn and helps ensure uniform dyeing. If the foam generation is too low, the surface fibers will not be dyed and the carpet surface will have a frosty appearance. When the foam is uneven, spots of undyed fibers will result. The scouring and drying operations are well known in the art.
The first step in the production of tufted carpets usually involves tufting the face yarns into a primary carpet backing, which is a relatively slow operation. When sufficient yardage of a given style has been produced, the material is stored until dyeing facilities are available. The time elapsed between tufting and dyeing, lag time, of the primary carpet backing may range from 1-2 days to 3-4 weeks. When carpet produced from a primary carpet backing lubricated with a polymethylhydrogensiloxane is lagged more than two to three days before dyeing, poor dyeing performance is obtained in continuous dyeing processes, this typically being characterized by a frosty appearance in the dyed carpet.
Investigations revealed that this poor dyeing performance is due to a reduction in the foam level during the steaming operation, and that this is apparently a result of the presence of the polymethylhydrogensiloxane. Although reducing the amount of polysiloxane on the primary carpet backing can provide some improvements in dyeing performance, this reduction has a deleterious effect on the strength of the tufted material. Furthermore, uniform application of very small amounts of a polysiloxane onto a backing is extremely difficult and generally results in areas having a pickup sufficiently high to pose dyeing problems and other areas where the pickup is so low as to be ineffective as a tufting lubricant.
Polydialkylsiloxanes appear to present much less problem than the polyalkylhydrogensiloxanes when applied to carpet backings destined for continuous dyeings; but the dialkyl products present another problem; these products give carpets which are "scroopy" underfoot, i.e., the carpet pile has an annoying crunchy feel when walked upon.
The problem encountered in continuous dyeing of carpet and the problem relating to feel of the carpet underfoot have both been resolved by the present invention and these problems have been resolved without an appreciable loss in tear strength in the tufted carpet.
SUMMARY OF THE INVENTION
The invention provides a bonded nonwoven sheet of synthetic organic fibers having applied thereon a lubricating composition comprising 3-50 percent by weight of a liquid polysiloxane and 50-97 percent by weight of defined liquid polyoxypropylene compound in an amount such that the quantity of polysiloxane present on the sheet is in the range of about 0.06-0.8 percent by weight. This lubricated, nonwoven fabric is suitable as a primary carpet backing which has high strength after tufting and performs acceptably in continuous dyeing operations.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The preferred nonwoven sheets which are lubricated in accordance with this invention are of the type disclosed and claimed in Petersen -- U.S. Pat. No. 3,502,538. Preferably, the sheets comprise continuous filaments of isotactic polypropylene which have been segmentally drawn by passage over a heated roll adapted with an axially slotted surface to heat only segments of the filaments, followed by passage over unheated draw rolls. Other polypropylene filaments, for example drawn at a single draw ratio, or at two or more different draw ratios, may be used, as can filaments from other spinnable polymers such as polyesters, polyamides, etc.
The most preferred lubricated nonwoven sheets of this invention are made from continuous polypropylene filaments which are preferentially aligned in the length and width directions, as disclosed in Edwards U.S. Pat. No. 3,563,838. These sheets, which are particularly suited for use as primary carpet backings due to their high dimensional stability and strength after tufting, may be prepared by the process described in Troth U.S. Pat. No. 3,477,103. In this process, a primary fluid stream containing a plurality of electrostatically charged continuous filaments is forwarded toward a laydown zone on a receiver surface moving away from the laydown zone. Two secondary fluid streams are alternately impinged on opposite sides of the primary fluid stream thereby deflecting said primary stream and the contained filaments in opposite directions, the filaments being laid down in swaths on the receiver, aligned in the direction of deflection. For the commercial production of nonwoven fabrics, a plurality of filament deflecting devices can be used and disposed so as to provide filament alignment in the machine (length) and in the cross-machine (width) direction.
The nonwoven sheets of this invention may be bonded by methods known in the art but are preferably self-bonded by exposure to saturated steam to provide bond-strength distributions as described in Petersen -- U.S. Pat. No. 3,502,538. Suitable apparatus for effecting this steam-bonding is described in Wyeth -- U.S. Pat. No. 3,313,002. In the following examples, bonding was accomplished in this manner.
The lubricating compositions used in accordance with this invention consist of mixtures comprising 3-50 percent and preferably 5-20 percent by weight of liquid polymonoalkyl or polydialkylsiloxane with 50-97 percent and preferably 80-95 percent by weight of liquid polyoxypropylene compound having a viscosity of at least 100 centipoise at 25°C. The polyoxypropylene component may either have two hydroxy end groups, i.e., the glycol, or may have one hydroxy end group and one alkoxy (preferably from one to six carbon atoms) end group, i.e., the monoalkyl ether. The specified polysiloxanes and polyoxypropylene compounds form relatively stable emulsions when combined and other additives are not needed unless the emulsions are expected to stand for several hours before use. The emulsion of the invention can be applied to the nonwoven sheets by spraying, gravure coating or other techniques.
A preferred emulsion for providing high tufted tongue tear strength while avoiding frostiness in continuous dyeing is prepared from a polymethylhydrogensiloxane (available from Dow-Corning Corp. as DC--1107) and a polyoxypropylene glycol (a dihydroxy material available from Wyandotte Chemical Corp. as "Pluracol" P--1010).
A preferred emulsion for high tufted tear strength without development of scroopiness in carpet is a mixture of polydimethylsiloxane (available from Dow-Corning Corp. as DC--200) and the monobutylether of polyoxypropylene glycol (available from Union Carbide Chemical Corp. as "Ucon" LB385).
The effectiveness of a tufting lubricant may be determined by tufting the lubricated sheet and measuring the tear strength of the tufted sheet, the more effective the lubricant, the higher the tear strength. In the following examples, lubricant effectiveness was measured by tufting the lubricated sheets on a table-top tufter with 3700 denier bulked continuous filament nylon yarn, at 7 tufts/inch (in the machine or length direction) the tufts being spaced three-sixteenths inch apart in the width direction and having a height of seven-sixteenths inch.
The machine direction tufted tongue tear strength was measured in the following manner. The tufted nonwoven sheet is cut into a sample 6 inches wide (cross-machine direction, across tufting rows) and 8 inches long (machine direction along tufting rows). The sample is cut in the center of the width 4 inches in the machine (tufting) direction. The sample is mounted in an "Instron" tester using 1.5 inch by 2 inch serrated clamps. With a jaw separation of 3 inches, one side of the sample cut is mounted in the upper jaw and the other side of the sample cut is mounted in the lower jaw. The sample is uniformly spaced between the jaws. The full scale load is adjusted to a value greater than the tear strength expected for the sample. Using a cross head speed of 12 inches per minute and a chart speed of 10 inches per minute, the "Instron" is started and the sample is torn. An average of the three highest stresses during tearing is taken. The tongue tear strength in pounds is reported as this average divided by 100 and multiplied by the full scale load. In general several determinations are made and the average reported.
The dyeing tests were carried out in continuous dyeing equipment developed by the Kusters Co., Germany (distributed in the U. S. by Zima Corporation, Spartanburg, S.C.). Most of the tests were carried out in semi-works type equipment capable of continuously dyeing tufted goods about 36 inches wide, but some tests were carried out in commercial size equipment capable of handling tufted goods up to 15 feet wide.
EXAMPLE I
This example demonstrates the need for a minimum amount of polysiloxane on the nonwoven sheet to provide lubrication during tufting. Emulsions were formed from different amounts of polymethylhydrogensiloxane (DC--1107) and polyoxypropylene glycol ("Pluracol" P--1010) described above, the latter having a viscosity of about 155 centipoise at 25°C. These were sprayed in an amount of about 2 percent by weight onto a 3.5 oz./yd. 2 bonded nonwoven sheet from segmentally drawn continuous polypropylene filaments, in which the filaments were preferentially aligned in the machine and cross-machine direction, the sheet being prepared by the process described in Troth -- U.S. Pat. No. 3,477,103. The samples were tufted and the tear strength measured in the manner described above.
TABLE I
Finish Composition Polyoxy- Polymethyl- Tufted propylene Polymethyl- hydrogensiloxane Tongue Glycol hydrogensiloxane on sheet Tear % by weight % by weight % by weight lb. 100 2 56 50 50 1 55 90 10 0.2 55 93 7 0.14 57 95 5 0.1 61 96 4 0.08 54 97 3 0.06 53 98 2 0.04 51 99 1 0.02 51 100 0 0 45
Results listed in Table 1 indicate that the tear strength remains high over most of the concentration range, but falls off when the amount of polysiloxane on the sheet drops below about 0.06 percent by weight. For comparative purposes, tufting of a similar nonwoven sheet having no finish applied thereon gave a tufted tongue tear of about 15 lbs.
EXAMPLE II
A 3.0 oz./yd. 2 nonwoven sheet, produced from continuous polypropylene filaments in the manner generally described in Example I was lubricated with various amounts of an emulsion formed from 95 percent by weight of the polyoxypropylene glycol ("Pluracol" P--1010) and 5 percent by weight of polymethylhydrogensiloxane (DC--1107). Samples of these lubricated sheets were tufted and the tufted tongue tear measured. The results, summarized in Table II, again indicate that the tufted tongue tear starts to decrease sharply when the amount of polysiloxane on the sheet drops below about 0.06 percent.
TABLE II
Polymethyl- hydrogensiloxane Finish Composition on sheet Tufted Tongue % by weight on sheet % by weight Tear lbs. 0 0 17 0.52 0.026 38 1.1 0.055 42 2.0 0.1 48 3.03 0.152 48 4.03 0.202 48
EXAMPLE III
The lubricating effect of the mixture of polyoxypropylene glycol and a polysiloxane is demonstrated in this example, in which another nonwoven sheet similar to that in Example I and having a basis weight of about 3.5 oz./yd. 2 was coated (a) with 2 percent of a 95/5 percent by weight emulsion of polyoxypropylene glycol and polymethylhydrogensiloxane, (b) with 1.9 percent of the polyoxypropylene glycol alone, and (c) with 0.1 percent of the siloxane alone [i.e., the amounts respectively of polyoxypropylene glycol and polymethylhydrogensiloxane in items (b) and (c) being the same as those present in combination in item (a)]. The results shown in Table II indicate that the tufted tongue tear of sample a is significantly higher than that of either sample b or sample c.
TABLE III
Finish Tufted Tongue Sample by weight Tear lbs. a 2% Emulsion 53 b 1.9% Polyoxypropylene Glycol 44 c 0.1% Polymethylhydrogen- siloxane 40
EXAMPLE IV
This example demonstrates the improved continuous dyeing performance of the primary carpet backing of this invention, compared with one containing a prior art lubricant.
Long yardages of continuous filament nonwoven backing of the type described in Example I were lubricated respectively with 100 percent polymethylhydrogensiloxane, with a 50/50 mixture of polymethylhydrogensiloxane and polyoxypropylene glycol, and a 5/95 percent mixture of the siloxane and polyoxypropylene glycol. After tufting, samples were lagged for various periods of time before being subjected to a typical continuous dyeing operation as earlier described. Formulations of the prepad and dye solutions used in this dyeing operation are listed in Table IV.
TABLE IV
Dye Bath Formulation: (Pickup .about. 400 percent)
"DuPonol" FAB (Foaming Agent -- E. I. du Pont de Nemours & Co., Inc.): 4 g/l
Polygum 260 (Thickener -- Polymer Industries Incorporated ) : 6 g/l
Monosodium Phosphate (PH buffer): 2 g/l
Color Index Direct Yellow 44 : 3 g/l
Color Index Acid Red 337 : 0.28 g/l
Color Index Acid Blue 40 : 0.95 g/l
Prepad Bath (Pickup .about. 100 percent)
"Merpol" WF (Wetting Agent -- E. I. du Pont de Nemours & Co., Inc.): 5 g/l
"DuPonol" FAB (Foaming Agent -- E. I. du Pont de Nemours & Co., Inc.) : 2 g/l
All the samples were dyed under essentially the same conditions using a steaming time of about 8 minutes at 100°C. After drying, the dyed samples were subjectively evaluated for appearance, dye uniformity, lack of frostiness, etc., the criterion for acceptability being that the product should be free of dyeing defects when dyed at least three weeks and preferably four weeks after tufting.
TABLE V
Tuft Finish Finish on MHP* on to dye Dye Type Sheet wt% Sheet lag time Quality 100% MHP* 1 1 3 days Unacceptable 50/50 PPG**/ MHP* 1 0.5 3 weeks Acceptable 50/50 PPG**/ MHP* 2 1 3 weeks Unacceptable 95/5 PPG**/ MHP* 1 0.05 4 weeks Acceptable 95/5 PPG**/ MHP* 2 0.1 4 weeks Acceptable * Polymethylhydrogensiloxane **Polyoxypropylene glycol
The results in Table V shows that unacceptable dye quality is obtained with 1 percent by weight of polymethylhydrogensiloxane on the sheet, either alone or in combination with the polyoxypropylene glycol.
EXAMPLE V
Additional tests were carried out using a 3 oz/yd. 2 nonwoven polypropylene primary carpet backing to which was applied various amounts of an emulsion containing 95 percent polyoxypropylene glycol and 5 percent polymethylhydrogensiloxane previously described. After tufting, the continuous dyeing performance of the various samples was tested every week, for a number of weeks, to determine how many weeks each sample could be lagged and still obtain acceptable dyeing performance.
Formulations of the baths used in the dyeing operation are listed in Table VI and the dye-quality results are given in Table VII. These results indicate that acceptable performance is obtained with up to 0.72 percent of polysiloxane on the sheet and that the lag time for acceptable performance increases as the amount of polysiloxane on the sheet decreases.
TABLE VI
Dye Bath Formulation (Pickup.about.400 percent)
"Duponol" FAB (Foaming Agent -- E. I. du Pont de Nemours & Co., Inc.): 3.0 g/l
Polygum 260 (Thickener -- Polymer Industries, Inc.) : 5.0 g/l
Monosodium Phosphate (PH Buffer) : 2.0 g/l
Color Index Acid Yellow 174 : 3 g/l
Color Index Acid Blue 40 : 0.73 g/l
Color Index Acid Red 337 : 0.7 g/l
Prepad Bath (Pickup .about. 100 percent)
"Merpol" WF (Wetting Agent -- E. I. du Pont de Nemours & Co., Inc.) : 3 g/l
Polygum 260 (Thickener -- Polymer Industries, Inc.) : 2 g/l
TABLE VII
Polysiloxane Acceptable Dye Finish Pickup on Sheet Quality with Tuft- % by weight % by Weight to-dye lags up to: 14.4 0.72 3 weeks 5.9 0.3 4 weeks 4.6 0.23 9 weeks 4.0 0.2 12 weeks
EXAMPLES VI TO VIII
These examples demonstrate the lubricating effect obtained with other mixtures of polysiloxanes and polyoxypropylene compounds. Nonwoven sheets having a basis weight of 4 oz./yd. 2 produced in the manner generally described in Example I were lubricated (a) with an amount of an emulsion of a polysiloxane and a polyoxypropylene compound, (b) with the polyoxypropylene compound alone and (c) with the polysiloxane alone, the respective amounts of the components in items (b) and (c) being about the same as those present in combination in item (a). The actual materials used and the amount of finish by weight are listed in Table VIII which also gives the results of the tufted tongue tear measurements. In each case, it is seen that the tear strength is significantly higher in samples lubricated with the two component emulsion than with either component separately.
The carpet of Example VIa was allowed to stand for three weeks and was then subjected to a continuous dyeing operation as described in previous examples. Dyeing was uniform and acceptable. The carpets of Examples VIIa and VIIIa were pleasant to walk upon, being free from the scroopiness exhibited by carpets of Examples VIIc and VIIIc. ##SPC1##
EXAMPLE IX
A nonwoven sheet of the type generally described in the preceding examples was lubricated using a gravure coater with varying amounts of the emulsion of Example VII so as to vary the quantity of dimethyl polysiloxane on the sheet from about 0.03 to about 0.11 percent by weight. A sharp drop in tufted tongue tear was observed when the amount of polysiloxane on the sheet dropped below about 0.06 percent by weight.
The invention relates to treated continuous filament nonwoven materials which are suitable as tufting substrates in the production of tufted carpets. Jung, in U.S. Pat. No. 3,322,607, has disclosed continuous filament nonwoven materials which can be used as primary carpet backings in the production of tufted carpets. The same patent also discloses that it is necessary to treat these products with a lubricant prior to tufting, and discloses the use of polysiloxanes as tufting lubricants.
The production of tufted carpets, usually includes a dyeing operation to dye the face yarns. Conventionally, this dyeing operation was effected in dye-becks in which the carpet was formed into a continuous belt and cycled in the dye-beck until the correct face yarn color had been obtained. More recently, however, continuous dyeing processes have been developed in which an undyed, tufted primary carpet backing enters at one end of an apparatus and exits at the other end with dyed face yarns. A typical continuous dyeing process comprises the steps of 1) application of about 100 percent wet pickup of a prepad solution to wet all carpet face fibers; 2) application of about 400 percent of a dye solution which is metered onto the carpet face by doctoring the solution from a roll rotating in the dye solution; 3) steaming the carpet at 100°C. for about 10 minutes; 4) scouring the carpet; 5) removing excess water with suction; and 6) drying the carpet in an oven.
The prepad solution generally contains a pH adjustor and a thickener to keep the solution on the carpet face fibers. The dye solution contains dyes, foaming agent, pH adjustors, and a thickener. The steaming operation is probably the most critical of the entire process. In this operation, condensation of water vapor on the carpet causes a large generation of foam on the carpet surface. This foam distributes the dyestuff evenly throughout the face yarn and helps ensure uniform dyeing. If the foam generation is too low, the surface fibers will not be dyed and the carpet surface will have a frosty appearance. When the foam is uneven, spots of undyed fibers will result. The scouring and drying operations are well known in the art.
The first step in the production of tufted carpets usually involves tufting the face yarns into a primary carpet backing, which is a relatively slow operation. When sufficient yardage of a given style has been produced, the material is stored until dyeing facilities are available. The time elapsed between tufting and dyeing, lag time, of the primary carpet backing may range from 1-2 days to 3-4 weeks. When carpet produced from a primary carpet backing lubricated with a polymethylhydrogensiloxane is lagged more than two to three days before dyeing, poor dyeing performance is obtained in continuous dyeing processes, this typically being characterized by a frosty appearance in the dyed carpet.
Investigations revealed that this poor dyeing performance is due to a reduction in the foam level during the steaming operation, and that this is apparently a result of the presence of the polymethylhydrogensiloxane. Although reducing the amount of polysiloxane on the primary carpet backing can provide some improvements in dyeing performance, this reduction has a deleterious effect on the strength of the tufted material. Furthermore, uniform application of very small amounts of a polysiloxane onto a backing is extremely difficult and generally results in areas having a pickup sufficiently high to pose dyeing problems and other areas where the pickup is so low as to be ineffective as a tufting lubricant.
Polydialkylsiloxanes appear to present much less problem than the polyalkylhydrogensiloxanes when applied to carpet backings destined for continuous dyeings; but the dialkyl products present another problem; these products give carpets which are "scroopy" underfoot, i.e., the carpet pile has an annoying crunchy feel when walked upon.
The problem encountered in continuous dyeing of carpet and the problem relating to feel of the carpet underfoot have both been resolved by the present invention and these problems have been resolved without an appreciable loss in tear strength in the tufted carpet.
SUMMARY OF THE INVENTION
The invention provides a bonded nonwoven sheet of synthetic organic fibers having applied thereon a lubricating composition comprising 3-50 percent by weight of a liquid polysiloxane and 50-97 percent by weight of defined liquid polyoxypropylene compound in an amount such that the quantity of polysiloxane present on the sheet is in the range of about 0.06-0.8 percent by weight. This lubricated, nonwoven fabric is suitable as a primary carpet backing which has high strength after tufting and performs acceptably in continuous dyeing operations.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The preferred nonwoven sheets which are lubricated in accordance with this invention are of the type disclosed and claimed in Petersen -- U.S. Pat. No. 3,502,538. Preferably, the sheets comprise continuous filaments of isotactic polypropylene which have been segmentally drawn by passage over a heated roll adapted with an axially slotted surface to heat only segments of the filaments, followed by passage over unheated draw rolls. Other polypropylene filaments, for example drawn at a single draw ratio, or at two or more different draw ratios, may be used, as can filaments from other spinnable polymers such as polyesters, polyamides, etc.
The most preferred lubricated nonwoven sheets of this invention are made from continuous polypropylene filaments which are preferentially aligned in the length and width directions, as disclosed in Edwards U.S. Pat. No. 3,563,838. These sheets, which are particularly suited for use as primary carpet backings due to their high dimensional stability and strength after tufting, may be prepared by the process described in Troth U.S. Pat. No. 3,477,103. In this process, a primary fluid stream containing a plurality of electrostatically charged continuous filaments is forwarded toward a laydown zone on a receiver surface moving away from the laydown zone. Two secondary fluid streams are alternately impinged on opposite sides of the primary fluid stream thereby deflecting said primary stream and the contained filaments in opposite directions, the filaments being laid down in swaths on the receiver, aligned in the direction of deflection. For the commercial production of nonwoven fabrics, a plurality of filament deflecting devices can be used and disposed so as to provide filament alignment in the machine (length) and in the cross-machine (width) direction.
The nonwoven sheets of this invention may be bonded by methods known in the art but are preferably self-bonded by exposure to saturated steam to provide bond-strength distributions as described in Petersen -- U.S. Pat. No. 3,502,538. Suitable apparatus for effecting this steam-bonding is described in Wyeth -- U.S. Pat. No. 3,313,002. In the following examples, bonding was accomplished in this manner.
The lubricating compositions used in accordance with this invention consist of mixtures comprising 3-50 percent and preferably 5-20 percent by weight of liquid polymonoalkyl or polydialkylsiloxane with 50-97 percent and preferably 80-95 percent by weight of liquid polyoxypropylene compound having a viscosity of at least 100 centipoise at 25°C. The polyoxypropylene component may either have two hydroxy end groups, i.e., the glycol, or may have one hydroxy end group and one alkoxy (preferably from one to six carbon atoms) end group, i.e., the monoalkyl ether. The specified polysiloxanes and polyoxypropylene compounds form relatively stable emulsions when combined and other additives are not needed unless the emulsions are expected to stand for several hours before use. The emulsion of the invention can be applied to the nonwoven sheets by spraying, gravure coating or other techniques.
A preferred emulsion for providing high tufted tongue tear strength while avoiding frostiness in continuous dyeing is prepared from a polymethylhydrogensiloxane (available from Dow-Corning Corp. as DC--1107) and a polyoxypropylene glycol (a dihydroxy material available from Wyandotte Chemical Corp. as "Pluracol" P--1010).
A preferred emulsion for high tufted tear strength without development of scroopiness in carpet is a mixture of polydimethylsiloxane (available from Dow-Corning Corp. as DC--200) and the monobutylether of polyoxypropylene glycol (available from Union Carbide Chemical Corp. as "Ucon" LB385).
The effectiveness of a tufting lubricant may be determined by tufting the lubricated sheet and measuring the tear strength of the tufted sheet, the more effective the lubricant, the higher the tear strength. In the following examples, lubricant effectiveness was measured by tufting the lubricated sheets on a table-top tufter with 3700 denier bulked continuous filament nylon yarn, at 7 tufts/inch (in the machine or length direction) the tufts being spaced three-sixteenths inch apart in the width direction and having a height of seven-sixteenths inch.
The machine direction tufted tongue tear strength was measured in the following manner. The tufted nonwoven sheet is cut into a sample 6 inches wide (cross-machine direction, across tufting rows) and 8 inches long (machine direction along tufting rows). The sample is cut in the center of the width 4 inches in the machine (tufting) direction. The sample is mounted in an "Instron" tester using 1.5 inch by 2 inch serrated clamps. With a jaw separation of 3 inches, one side of the sample cut is mounted in the upper jaw and the other side of the sample cut is mounted in the lower jaw. The sample is uniformly spaced between the jaws. The full scale load is adjusted to a value greater than the tear strength expected for the sample. Using a cross head speed of 12 inches per minute and a chart speed of 10 inches per minute, the "Instron" is started and the sample is torn. An average of the three highest stresses during tearing is taken. The tongue tear strength in pounds is reported as this average divided by 100 and multiplied by the full scale load. In general several determinations are made and the average reported.
The dyeing tests were carried out in continuous dyeing equipment developed by the Kusters Co., Germany (distributed in the U. S. by Zima Corporation, Spartanburg, S.C.). Most of the tests were carried out in semi-works type equipment capable of continuously dyeing tufted goods about 36 inches wide, but some tests were carried out in commercial size equipment capable of handling tufted goods up to 15 feet wide.
EXAMPLE I
This example demonstrates the need for a minimum amount of polysiloxane on the nonwoven sheet to provide lubrication during tufting. Emulsions were formed from different amounts of polymethylhydrogensiloxane (DC--1107) and polyoxypropylene glycol ("Pluracol" P--1010) described above, the latter having a viscosity of about 155 centipoise at 25°C. These were sprayed in an amount of about 2 percent by weight onto a 3.5 oz./yd. 2 bonded nonwoven sheet from segmentally drawn continuous polypropylene filaments, in which the filaments were preferentially aligned in the machine and cross-machine direction, the sheet being prepared by the process described in Troth -- U.S. Pat. No. 3,477,103. The samples were tufted and the tear strength measured in the manner described above.
TABLE I
Finish Composition Polyoxy- Polymethyl- Tufted propylene Polymethyl- hydrogensiloxane Tongue Glycol hydrogensiloxane on sheet Tear % by weight % by weight % by weight lb. 100 2 56 50 50 1 55 90 10 0.2 55 93 7 0.14 57 95 5 0.1 61 96 4 0.08 54 97 3 0.06 53 98 2 0.04 51 99 1 0.02 51 100 0 0 45
Results listed in Table 1 indicate that the tear strength remains high over most of the concentration range, but falls off when the amount of polysiloxane on the sheet drops below about 0.06 percent by weight. For comparative purposes, tufting of a similar nonwoven sheet having no finish applied thereon gave a tufted tongue tear of about 15 lbs.
EXAMPLE II
A 3.0 oz./yd. 2 nonwoven sheet, produced from continuous polypropylene filaments in the manner generally described in Example I was lubricated with various amounts of an emulsion formed from 95 percent by weight of the polyoxypropylene glycol ("Pluracol" P--1010) and 5 percent by weight of polymethylhydrogensiloxane (DC--1107). Samples of these lubricated sheets were tufted and the tufted tongue tear measured. The results, summarized in Table II, again indicate that the tufted tongue tear starts to decrease sharply when the amount of polysiloxane on the sheet drops below about 0.06 percent.
TABLE II
Polymethyl- hydrogensiloxane Finish Composition on sheet Tufted Tongue % by weight on sheet % by weight Tear lbs. 0 0 17 0.52 0.026 38 1.1 0.055 42 2.0 0.1 48 3.03 0.152 48 4.03 0.202 48
EXAMPLE III
The lubricating effect of the mixture of polyoxypropylene glycol and a polysiloxane is demonstrated in this example, in which another nonwoven sheet similar to that in Example I and having a basis weight of about 3.5 oz./yd. 2 was coated (a) with 2 percent of a 95/5 percent by weight emulsion of polyoxypropylene glycol and polymethylhydrogensiloxane, (b) with 1.9 percent of the polyoxypropylene glycol alone, and (c) with 0.1 percent of the siloxane alone [i.e., the amounts respectively of polyoxypropylene glycol and polymethylhydrogensiloxane in items (b) and (c) being the same as those present in combination in item (a)]. The results shown in Table II indicate that the tufted tongue tear of sample a is significantly higher than that of either sample b or sample c.
TABLE III
Finish Tufted Tongue Sample by weight Tear lbs. a 2% Emulsion 53 b 1.9% Polyoxypropylene Glycol 44 c 0.1% Polymethylhydrogen- siloxane 40
EXAMPLE IV
This example demonstrates the improved continuous dyeing performance of the primary carpet backing of this invention, compared with one containing a prior art lubricant.
Long yardages of continuous filament nonwoven backing of the type described in Example I were lubricated respectively with 100 percent polymethylhydrogensiloxane, with a 50/50 mixture of polymethylhydrogensiloxane and polyoxypropylene glycol, and a 5/95 percent mixture of the siloxane and polyoxypropylene glycol. After tufting, samples were lagged for various periods of time before being subjected to a typical continuous dyeing operation as earlier described. Formulations of the prepad and dye solutions used in this dyeing operation are listed in Table IV.
TABLE IV
Dye Bath Formulation: (Pickup .about. 400 percent)
"DuPonol" FAB (Foaming Agent -- E. I. du Pont de Nemours & Co., Inc.): 4 g/l
Polygum 260 (Thickener -- Polymer Industries Incorporated ) : 6 g/l
Monosodium Phosphate (PH buffer): 2 g/l
Color Index Direct Yellow 44 : 3 g/l
Color Index Acid Red 337 : 0.28 g/l
Color Index Acid Blue 40 : 0.95 g/l
Prepad Bath (Pickup .about. 100 percent)
"Merpol" WF (Wetting Agent -- E. I. du Pont de Nemours & Co., Inc.): 5 g/l
"DuPonol" FAB (Foaming Agent -- E. I. du Pont de Nemours & Co., Inc.) : 2 g/l
All the samples were dyed under essentially the same conditions using a steaming time of about 8 minutes at 100°C. After drying, the dyed samples were subjectively evaluated for appearance, dye uniformity, lack of frostiness, etc., the criterion for acceptability being that the product should be free of dyeing defects when dyed at least three weeks and preferably four weeks after tufting.
TABLE V
Tuft Finish Finish on MHP* on to dye Dye Type Sheet wt% Sheet lag time Quality 100% MHP* 1 1 3 days Unacceptable 50/50 PPG**/ MHP* 1 0.5 3 weeks Acceptable 50/50 PPG**/ MHP* 2 1 3 weeks Unacceptable 95/5 PPG**/ MHP* 1 0.05 4 weeks Acceptable 95/5 PPG**/ MHP* 2 0.1 4 weeks Acceptable * Polymethylhydrogensiloxane **Polyoxypropylene glycol
The results in Table V shows that unacceptable dye quality is obtained with 1 percent by weight of polymethylhydrogensiloxane on the sheet, either alone or in combination with the polyoxypropylene glycol.
EXAMPLE V
Additional tests were carried out using a 3 oz/yd. 2 nonwoven polypropylene primary carpet backing to which was applied various amounts of an emulsion containing 95 percent polyoxypropylene glycol and 5 percent polymethylhydrogensiloxane previously described. After tufting, the continuous dyeing performance of the various samples was tested every week, for a number of weeks, to determine how many weeks each sample could be lagged and still obtain acceptable dyeing performance.
Formulations of the baths used in the dyeing operation are listed in Table VI and the dye-quality results are given in Table VII. These results indicate that acceptable performance is obtained with up to 0.72 percent of polysiloxane on the sheet and that the lag time for acceptable performance increases as the amount of polysiloxane on the sheet decreases.
TABLE VI
Dye Bath Formulation (Pickup.about.400 percent)
"Duponol" FAB (Foaming Agent -- E. I. du Pont de Nemours & Co., Inc.): 3.0 g/l
Polygum 260 (Thickener -- Polymer Industries, Inc.) : 5.0 g/l
Monosodium Phosphate (PH Buffer) : 2.0 g/l
Color Index Acid Yellow 174 : 3 g/l
Color Index Acid Blue 40 : 0.73 g/l
Color Index Acid Red 337 : 0.7 g/l
Prepad Bath (Pickup .about. 100 percent)
"Merpol" WF (Wetting Agent -- E. I. du Pont de Nemours & Co., Inc.) : 3 g/l
Polygum 260 (Thickener -- Polymer Industries, Inc.) : 2 g/l
TABLE VII
Polysiloxane Acceptable Dye Finish Pickup on Sheet Quality with Tuft- % by weight % by Weight to-dye lags up to: 14.4 0.72 3 weeks 5.9 0.3 4 weeks 4.6 0.23 9 weeks 4.0 0.2 12 weeks
EXAMPLES VI TO VIII
These examples demonstrate the lubricating effect obtained with other mixtures of polysiloxanes and polyoxypropylene compounds. Nonwoven sheets having a basis weight of 4 oz./yd. 2 produced in the manner generally described in Example I were lubricated (a) with an amount of an emulsion of a polysiloxane and a polyoxypropylene compound, (b) with the polyoxypropylene compound alone and (c) with the polysiloxane alone, the respective amounts of the components in items (b) and (c) being about the same as those present in combination in item (a). The actual materials used and the amount of finish by weight are listed in Table VIII which also gives the results of the tufted tongue tear measurements. In each case, it is seen that the tear strength is significantly higher in samples lubricated with the two component emulsion than with either component separately.
The carpet of Example VIa was allowed to stand for three weeks and was then subjected to a continuous dyeing operation as described in previous examples. Dyeing was uniform and acceptable. The carpets of Examples VIIa and VIIIa were pleasant to walk upon, being free from the scroopiness exhibited by carpets of Examples VIIc and VIIIc. ##SPC1##
EXAMPLE IX
A nonwoven sheet of the type generally described in the preceding examples was lubricated using a gravure coater with varying amounts of the emulsion of Example VII so as to vary the quantity of dimethyl polysiloxane on the sheet from about 0.03 to about 0.11 percent by weight. A sharp drop in tufted tongue tear was observed when the amount of polysiloxane on the sheet dropped below about 0.06 percent by weight.