THERMOPLASTIC POLYESTER, A THERMOPLASTIC POLYURETHANE

AND A CARBODIIMIDE

This application claims priority from United States application serial number 61/350, 1 1 1 filed June 1 , 2010.

FIELD OF THE INVENTION

The present invention relates to oriented thermoplastic polymeric monofilaments comprised of a polymer blend, and to woven industrial textiles which include these monofilaments as at least some of their component yarns. The invention more particularly relates to monofilaments, and woven papermakers forming fabrics including yams thereof, formed from a polymer blend of a thermoplastic polyester, a thermoplastic polyurethane, and a carbodiimide; either or both of the polyester and polyurethane optionally may include an effective amount of an organosilicon compound in quantities sufficient to lower the surface energy of the monofilaments.

BACKGROUND OF THE INVENTION

Monofilaments formed from blends of polyethylene terephthalate (PET), thermoplastic polyurethane (TPU) and a polycarbodiimide are well known. See, for example, Bhatt et al. US 5, 169, 71 1 and US 5,502, 120. Similar compositions are also disclosed by Wagner et al. US 5,700,881 ; others may be known. The use of carbodiimides, in particular polycarbodiimides (PCDI ) to stabilize polyesters against hydrolytic and other forms of degradation is also well known; see for example US 5,246,992 (Wick et al. ) and US 5,81 1 ,508 (Zeitler et al. ).

US Patents 5, 169, 71 1 and 5,502, 120 teach the use of a polymer blend consisting of from about 60 to 90% parts by weight (pbw), based on the total weight of the monofilament, of a PET whose intrinsic viscosity (IV) is preferably in the range of from 0.65 to 1.05, together with from about 40 to 10% pbw of a TPU, which may be either an ester-based type or an ether-based type. The blend may additionally contain up to 5% pbw of a suitable polycarbodiimide type hydrolysis stabilizer masterbatch, such as Stabaxol E7646 which is provided from Rhein Chemie Rheinau GmbH, of Mannheim, Germany.

A "masterbatch" is a plastic, rubber, or elastomer mixture in which there is a high additives concentration, such as rubber with carbon black, or plastic with color pigment; it is used to proportion additives accurately into large bulks of plastic, rubber, or elastomer. According to the ' 120 and '71 1 patents, the Stabaxol E7646 masterbatch is added to the PET polymer of the blend prior to processing into monofilaments so as to increase the hydrolysis resistance of the final product. Product literature from Rhein Chemie Rheinau GmbH indicates that Stabaxol E7646 is a 15% pbw concentrate of Stabaxol PI 00, an aromatic polycarbodiimide polymerized from 2,4,6-Triisopropyl-m-phenylene di- isocyanate (TRIDI ), Chemical Abstracts Registiy Number 29963-44-8, in 85% medium intrinsic viscosity PET (IV = 0.81 ). As a result, the effective amount of the carbodiimide in the resulting polymer can be no higher than about 0.75% pbw in this prior art blend. The ' 120 and '71 1 patents identify that the useful effective amount of stabilizer, i.e. the Stabaxol E 7646 masterbatch, and not the relevant active component Stabaxol P I 00, to be used is in the range of zero to a maximum of 5% of the total weight.

The ' 120 and '71 1 patents further identify that the TPU was selected from the following candidate materials: an adipate polyester based polyiirethane such as TEXIN<R> 445D available from Mobay Chemical Corporation, of Pittsburgh, PA; a polyester based polycaprolactone type polyiirethane such as ELASTOLLAN<R> C95 available from BASF SE, of Ludwigshafen, Germany; a polyester based polycaprolactone type polyiirethane such as PELLETHANER ⁾ 2102-80A available from Dow Chemical Company of Midland, MI; a polyether based polyiirethane such as TEXIN<R> 990A available from Mobay; and a polyether based polyiirethane such as PELLETHANER ⁾ 2103-80A available from Dow Chemical Company.

Although monofilaments and papermakers fabrics produced in accordance with the teachings of the ' 120 and '71 1 patents have been found to be highly effective with respect to their wear resistance and other physical properties, there remains a need for a polymeric monofilament forming material which can further extend the life of industrial fabrics into which yarns formed thereof are incorporated.

It has now been found that significant improvements can be obtained in the physical properties of monofilaments and fabrics formed therefrom, in particular with respect to their resistance to abrasion, contamination and shower damage, if significantly greater amounts of a carbodiimide hydrolysis stabilizer material are added into the blend, in particular about from 2 to 3 times the amount disclosed in the ' 120 and '71 1 patents. "Abrasion resistance" refers to the ability of the monofilament and fabrics woven therefrom to resist wear caused by the continuous frictional effect from moving contact between the fabric and various stationaiy machine components; it is generally measured in comparison to a common standard, for example by comparison with conventional PET yarns, and is refeired to as Relative Abrasion Resistance, or RAR. Yarns with high RAR values greater than 1.0 are more resistant to wear than the standard, and thus provide a longer service life, than yarns with RAR values less than 1.0. "Contamination resistance" refers to the ability of the fabric to shed contaminants in the stock from which the product formed or carried by the fabric is made. "Shower damage" refers to strand fibrillation and complete destruction of localized areas of a fabric due to repeated exposure to cleaning by high pressure needle showers in a papermaking or similar machine. It has been found that these improvements can be obtained without sacrificing any other advantageous properties of the monofilaments, such as the ability of the strand to crimp when woven into fabrics

It has thus been found that when a masterbatch is added to the polymer blend in amounts such that the masterbatch comprises from 5 to 15% pbw of the polymer blend, and the masterbatch consists of sufficient carbodiimide to provide a final amount of carbodiimide in the polymer blend, and monofilaments formed therefrom, ranging from 0.75% pbw to as much as 3% pbw, the unexpected improvements noted above in the physical properties of the resulting monofilament are obtained in comparison to the prior art. To provide this desired amount in the blend using currently available products such as polycarbodiimide Stabaxol PI 00 or monomelic carbodiimide Stabaxol I, it has been found that the masterbatch should comprise at least 15% pbw to at least about 20% pbw or more of the carbodiimide, in about 80% pbw to 85 % pbw polyester.

The relatively higher amounts of either the polymeric or monomelic forms of the carbodiimide employed in the present blend in comparison to prior art teachings appear to produce a compatibilizing effect on the thermoplastic polyester PET and the TPU, i.e. improving the interfacial boundaries between the polymer components, thereby yielding a monofilament which is more robust and at least as malleable during weaving as those produced in accordance with the prior art. The carbodiimide can be either polymeric or monomelic. If polymeric, it may be polymerized from 2,4,6-Triisopropyl-m-phenylene di-isocyanate. A suitable polycarbodiimide product is commercially available as Stabaxol<R> P I 00 from Rhein Chemie Rheinau GmbH, and has been found to be particularly effective for use in the polymer blend and monofilaments formed thereof; others may also be suitable. The polycarbodiimide, or PCDI, is also available in masterbatch form under the designation Stabaxol<R> E7646 from the same supplier; other similar masterbatch designations may also be appropriate for this purpose. If monomelic, a suitable carbodiimide material has been found to be 2,2,6,6 ^' -tetraisopropyl diphenyl carbodiimide; this material is commercially available from Rhein Chemie Rheinau GmbH under the designation Stabaxol-I. Other commercially available carbodiimides may prove satisfactoiy. The polymeric form of the carbodiimide (i.e. the PCDI ) has been found to be particularly effective and may be preferable for use in the polymer blend of the invention; however, substantial benefits in terms of wear and the contamination resistance of monofilaments and fabrics including same have also been obtained using the monomelic form of the carbodiimide.

It has further been found that, by addition of an effective amount of an organosilicon compound, R^SiO (where R represents an alkane group having from 5 to 50 carbon atoms) into either, or both, the PET and TPU components of the polymer blend, the resultant monofilaments (and fabrics formed therefrom) appear to exhibit lower surface energy characteristics than similar monofilaments and fabrics formed from same which do not contain the organosilicon compound. Lowering the surface energy characteristics of the monofilament will reduce, to an appreciable extent, the frictional properties (and thus the machine drag loads and subsequent power consumption) created by fabrics as they pass over stationary components during operation in moist, wet environments such as are found in the forming section of a papermaking machine.

It appears that the low surface energy properties attributed to the organosilicon additive contribute to improvements to the contamination resistance of fabrics made from monofilaments which include quantities of this material. As used herein, the term "low surface energy" refers to the propensity of monofilaments and fabrics made thereof to shed contaminants and fluids, and to exhibit a lower coefficient of friction in comparison to similar monofilaments which do not contain quantities of the organosilicon additive. In general, surface energy refers to the interaction between the forces of cohesion and adhesion which determine whether or not wetting (the spreading of a liquid over a surface) occurs. Surface energy is most commonly quantified using a contact angle goniometer; however a number of different methods may also be used, such as a peel test in which a strip of tape is attached to a fabric sample and then pulled away, and the force required to remove the strip measured using a CRE type testing machine. It thus appears that the essential benefit provided by the organosilicon additive in this polymer blend is a reduction in the coefficient of friction of fabrics incorporating the monofilament, as measured by the drag load of the fabric on the machine for which it is intended. A further benefit appears to be an additional reduction in the propensity of contaminants to adhere to fabrics made from monofilaments into which the organosilicon additive has been incorporated.

In the polymer blends of the invention, it has been found that the addition of a small amount of a low surface energy organosilicon polymer, in the range of about 5% pbw that is incorporated into about 95% pbw unmodified TPU or a thermoplastic polyester such as PET, is effective to lower the surface energy of monofilaments extinded from the novel blend of this invention. It is consequently anticipated that both adipate and polycaprolactone type polyester polyiirethanes would be suitable in the practice of the present invention. As used herein, the term "organosilicon polymer" refers to polymeric silanes or siloxane polymers, such as polydimethylsiloxane, which have been incorporated into either a polyester or polyurethane.

SUMMARY OF THE INVENTION

The present invention therefore seeks to provide a polymer blend, oriented thermoplastic monofilaments comprised of the blend, and woven industrial fabrics including as at least some of their components monofilaments comprised of the blend.

In a first broad embodiment, the invention seeks to provide an oriented thermoplastic monofilament comprising a polymer blend, the blend comprising at least one thermoplastic polyester, a thermoplastic polyurethane (TPU), and a carbodiimide, wherein the polymer blend comprises i) between 50% parts by weight (pbw) and 70% pbw of a first thermoplastic polyester selected from polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polybutylene naphthalate (PBN), polycyclohexylenedimethylene terephthalate acid modified (PCTA) and polyethylene naphthalate (PEN); ii) between 25% pbw and 35% pbw of the TPU, the TPU having a Shore A hardness value of less than 95; and iii) a carbodiimide provided in a masterbatch, wherein the masterbatch comprises between about 15% pbw and about 20% pbw of the carbodiimide as a concentrate combined with between about 80% and about 85% of a second thermoplastic polyester, and the monofilament comprises at least 0.75% pbw of the carbodiimide. Preferably, the carbodiimide comprises between 0.75% pbw and 3% pbw of the monofilament.

Preferably, the first thermoplastic polyester is polyethylene terephthalate (PET), in which case preferably it has a medium to high intrinsic viscosity (IV). Preferably, it has an IV prior to blending of between 0.65 and 1.05 as measured by solution viscosity using a 50/50 w/w mixture of trifluoroacetic acid and dichloromethane at 30°C according to the procedure described in ASTM D4603-03, and more preferably an IV between 0.93 and 0.97.

Preferably, the second thermoplastic polyester is polyethylene terephthalate (PET), in which case preferably it has a medium intrinsic viscosity of about 0.81. Preferably, the TPU is selected from a polyether and a polyester. More preferably the TPU is a polyester and is selected from an adipate type and a polycaprolactone type.

Preferably, the TPU has a Shore A hardness value of between 75 and 85, and more preferably of about 80.

The carbodiimide can be a polycarbodiimide or a monomelic carbodiimide, and preferably the carbodiimide comprises an aromatic carbodiimide selected from a monomelic carbodiimide and a polycarbodiimide.

Where the carbodiimide is a polymeric carbodiimide, preferably it is polymerized from 2,4,6-Triisopropyl-m-phenylene di-isocyanate. Alternatively, the carbodiimide is a monomeric carbodiimide comprising 2,2,6,6 ^' -tetraisopropyl diphenyl carbodiimide. Optionally, the monofilament further comprises an organosilicon polymer selected from a silanized polyester and a silanized polyurethane. Preferably, the organosilicon polymer is a silanized polyurethane, and the polymer blend comprises between 1.0% pbw and 4% pbw of the silanized polyurethane, more preferably from about 1.5% pbw to about 3.5% pbw, most preferably between about 1.55% pbw and 3.0% pbw of the silanized polyurethane. The invention also seeks to provide an industrial textile comprising yams at least some of which are monofilaments according to the invention. In some embodiments, the industrial textile comprises a papermakers forming fabric, preferably as a woven textile, in which the monofilaments comprise at least some of the weft yarns, or at least some of the warp yarns, or some of each of the weft yarns and the warp yarns.

The invention further seeks to provide a method of preparing an oriented thermoplastic monofilament, comprising the steps of

(a) providing a first polyethylene terephthalate (PET), having an intrinsic viscosity (IV) prior to blending of between 0.65 and 1.05 as measured by solution viscosity using a 50/50 w/w mixture of trifluoroacetic acid and dichloromethane at 30°C according to the procedure described in ASTM D4603-03;

(b) providing a thermoplastic polyurethane (TPU) having a Shore A hardness value of less than 95;

(c) providing a masterbatch comprising between about 15% parts by weight (pbw) and about 20% pbw of a carbodiimide as a concentrate combined with between about 80% pbw and about 85% pbw of a second PET having a medium IV of about 0.81 ;

(d) preparing a polymer blend of between 50% and 70% of the first PET, between 25% pbw and 35% pbw of the TPU and between 5% and 15% pbw of the masterbatch; and

(e) extruding the blend of step (d) to produce the monofilament. If thermoplastic polyesters other than PET are selected for use in the polymer blend from which the monofilaments of the inventions are prepared, the polyester must have an intrinsic viscosity that is equivalent to, or provides similar results to that obtained using a PET whose IV ranges from 0.65 to 1.05, preferably about 0.93 to 0.97.

At present, PET resin types 5149 and 5157 available from DAK Americas LLC of Charlotte, NC, or type 8912 available from Indorama of Spartanburg, SC, or a solid-stated PET resin product coded as PQB8-095 and available from Nan Ya Plastics Coip. USA of Livingston, NJ is preferred for use in the polymer blends of the present invention. It is expected that it would be possible to obtain similar, or even improved, results by incorporating suitable amounts of an organosilicon polymer such as a siloxane modified polyester, for example NEA062Q 136 available from Clariant Coip. of Charlotte, NC. into the high intrinsic viscosity PET so as to obtain the benefits provide by a low surface energy silanized component.

Several polyurethane materials are considered to provide satisfactoiy results in the polymer blends of the present invention when combined with an appropriate organosilicon. For example, "Desmopan<R> 385 E", available from Bayer MaterialScience AG of Leverkusen, Germany, is a TPU-Polyester (thermoplastic polyester-urethane) material having a Shore A hardness of 85 - 89 which appears to impart both good hydrolysis resistance and mechanical properties to extruded products into which it is incorporated. A physical blend of about 5% pbw of a silicone modified polyester and 95% pbw polybutanediol adipate type polyurethane provided satisfactoiy results. Another material which has been found to be suitable for use in the present invention is a polycaprolactone copolyester based TPU available from Merquinsa, of Barcelona, Spain under the designation "Pearlthane<R> 1 1T80". This polymer material has a Shore A hardness of 82. In general, the TPU component of the polymer blend should have a Shore A hardness that is in the range of between about 75 - 85, with a Shore A hardness of about 80 being preferred.

In the polymer blend of the present invention, the TPU may be either a polycaprolactone or polybutanediol adipate type and, further, may be either polyether-based or polyester- based, generally depending on the intended end use. However, polyester based type TPU appears to offer better compatibility between the TPU and PET of the polymer blend and hence may be preferred, in particular where intended for use in hot, moist environments. Polyether types are the most resistant to hydrolytic attack but as noted above are less compatible with the PET, as manifested by greater fibrillation after high pressure showering, for example. Presently, an adipate type polyester based material such as Desmopan<R> 385 E, available from Bayer MaterialScience AG of Leverkusen, Germany, having a Shore A hardness of 85 - 89 is preferred. Another material which has been found to be suitable for use in the present invention is a polycaprolactone copolyester based TPU available from Merquinsa, of Barcelona, Spain under the designation "Pearlthane<R> 1 1T80". It has also been found that polycaprolactone types of TPU tend to provide better hydrolysis resistance than adipate types. METHOD OF MANUFACTURE

The monofilaments of the present invention may be produced by any suitable known method, typically as follows. Pellets of the selected medium to high IV thermoplastic polyester, in particular PET are physically blended with the selected suitable TPU in a ratio of from about 50 - 70% pbw of medium to high intrinsic viscosity PET to about 25 - 35% TPU whose hardness is in the range of about Shore A 75-85. The ratio of these materials is adjusted to allow for an amount of carbodiimide masterbatch sufficient to comprise from about 5 - 15% of the total weight of the composition to be added in pelletized form. The masterbatch will contain sufficient carbodiimide, either monomelic or polymeric, to ensure that it will be present in an amount ranging from at least about 0.75% to as much as about 3% pbw in the final extruded monofilament. A polycarbodiimide masterbatch such as Stabaxol<R>KE7646 is presently preferred for this use; however, others may be suitable.

The thermoplastic polyester, TPU and carbodiimide masterbatch materials are then physically blended in diy pelletized or powder form to provide a uniform mixture, then placed in an extruder hopper and extinded as monofilament. Preferably, the extruder type is a twin screw extiiider; however, single screw extruders may provide satisfactoiy results. Non-limiting extrusion conditions will provide temperatures in the range of about 260 - 265°C in each heater zone and the extruder die. The die may have as many holes as are suitable.

Alternatively, it is also possible to blend the components and then extrude them, using a twin or single screw extiiider, to pelletize the extiiidate, and then use these pellets to produce the final monofilament by the previous procedure. Either method would be appropriate, but more uniform blending of the components may be obtained by first compounding the polymers, pelletizing the result, and then extruding the monofilament from the precompounded extiiidate.

The final monofilament is extruded through the die holes and then quenched in a water bath at a temperature of about 66°C positioned from about 2 to 6 cm underneath the die. The quenched monofilament is then drawn in a water bath at a temperature of about 74°C at a draw ratio of 3.36: 1. It is then drawn further in a hot air oven at a temperature of about 230°C to a total draw ratio of about 5.0 and then allowed to relax about 25% at a temperature of about 280°C. The finished monofilament is then taken up on spools. Papermaking and other industrial fabrics are then formed by weaving the monofilament into fabric form, preferably as a weft yarn material located so as to be in contact with the various stationary elements of the papermaking machine when the fabric is in use.

DESCRIPTION OF THE FIGURES AND EXPERIMENTAL RESULTS The invention will now be described further with reference to experimental results, and to Figure 1 , which is a graphical representation of the relative abrasion resistance of monofilaments of the invention.

So as to ascertain the relative efficacy of the polymer blend of the present invention in comparison to other, similar materials, various monofilaments of polyester and polymer blends were prepared according to the methods described above and tested to determine their relative abrasion resistance, contamination resistance, and resistance to shower damage.

L Abrasion Resistance

Figure 1 is a graph showing the Relative Abrasion Resistance (RAR) as measured by the caliper loss of monofilaments that were subjected to a standard test. In this test, monofilament samples were located so as to be in contact with the stationary wear surfaces of an abrasive test instrument. The yarn samples were wrapped under tension over a wheel within which a plurality of ceramic inserts are mounted and oriented parallel to the axis of rotation so as to mimic the abrasive conditions to which fabrics would be exposed on a papermaking machine. The wheel was rotated at known speed for a set duration of time and immersed in a water bath for lubrication. The amount of tensile loss measured at the end of the test is indicative of the wear resistance of the fabric, and thus the monofilaments from which it was woven. Relative Abrasion Resistance (RAR) is the quotient obtained by dividing the average number of cycles to failure of the sample by the average number of cycles to failure of the control. The higher the RAR value, the less material that has been abraded away and thus the greater the expected abrasion resistance of the material.

The graph shows the RAR of 8 monofilament samples, which are further identified in Table 1 below as follows: Table 1 : RAR Test Results for Monofilaments as Shown in Figure 1

In Table 1 above, Samples 1 and 2 were a "standard" high intrinsic viscosity PET used in the production of technical monofilaments for industrial fabrics. Samples 3 and 4 were monofilaments comprised of a blend of PET, TPU and about 5% pbw PCDI masterbatch such as are described in US 5, 169,71 1 and US 5,502, 120 (Bhatt et al. ), and served as the control samples for this test. Sample 5 was comprised of a blend of PET, TPU and about 5% pbw PCDI masterbatch; the TPU contained 5% pbw of an organosilicon material (LSE). The 5% pbw PCDI masterbatch in these samples provided a concentration of about 0.75% carbodiimide in the extinded monofilament. Samples 6 and 7 were comprised of the same PET and PCDI as were used in the Samples 3 and 4 except that the TPU used was Desmopan<R> 385 LSE which contained 5% pbw of an organosilicon material R ₂ S1O in 95% thermoplastic polyurethane. Sample 8 was comprised of the same blend as for Samples 3 and 4 (i.e. the amount of PCDI was about 5% pbw) but additionally contained 5% pbw of an organosilicon material R ₂ S1O in 95% thermoplastic polyurethane, where R represents an alkane group. Sample 8 was extruded in a single pass, meaning it was not pre-compounded offline prior extrusion. The polymers used in Samples 1 - 7 were mixed, extruded, the result pelletized, and then extruded in final monofilament form; the polymers of Sample 8 were mixed during the extrusion, i.e. in a single pass. The test results presented in Table 1 and graphically in Figure 1 show that monofilaments comprised of a polymer blend according to the present invention which contained an organosilicon compound exhibit a higher RAR value than either unblended PET, or a blend of PET and TPU such as is described in the prior art. Further, monofilaments comprised of a blend of PET and PCDI and which further include in the TPU a organosilicon polymer, exhibit even further improvement in abrasion resistance as compared to those which did not contain the organosilicon polymer. This test indicates that, when in use, fabrics including the novel yarns of the present invention, which contain a higher amount of carbodiimide than has been previously suggested, are more abrasion resistant than similar fabrics made entirely from PET yarns, or fabrics made from the prior art blend.

2. Peel Test

Table 2 below shows the results obtained from testing polymer plaques made from various polymer blends according to the invention as compared to those of the prior art so as to determine the amount of force required to remove an adhesive backed tape from their surfaces. This test, noted above, is an indicator of how well contaminants may be shed from a fabric surface as a function of the amount of energy that may be required to remove them using e.g. high pressure showers. Contamination resistance is an important characteristic of papermaking fabrics because contaminants such as adhesives from recycled fiber sources can lodge on the fabric, blocking drainage and marring the sheet carried by the fabrics. In this test, a tape is applied to and adhered to the plaque surface and then pulled off in a direction normal to the surface using a CRE type tensile testing machine. The force required to remove the tape is recorded and averaged over time.

Table 2: Peel Test Results

In Table 2, Sample A was a polymer blend of about 60% pbw high intrinsic viscosity PET, and 40% pbw of a polyether based TPU which further included 5% pbw of an organosilicon modified polyether type TPU. Sample B was comprised of a similar blend but the TPU used was a polyester type. Samples C and E were each a polyether or a polyester type TPU + high IV PET controls that did not contain an organosilicon material. Sample D was a similar polymer blend of high IV PET with polyester type organosilicon modified TPU which contained 10% pbw organosilicon. Sample F was an unblended high IV PET.

The data in Table 2 shows that a plaque comprised entirely of PET (Sample F) exhibited the highest average peel load at 6.94 pounds (lbs), whereas a similar plaque formed from a polymer blend of PET and a polyether based TPU and 5% of an organosilicon polymer component (Sample A) exhibited the lowest peel load. All of the samples containing organosilicon polymer, i.e. samples A, B and D exhibited lower average peel forces than either of the control samples C and E, or the PET sample F. These data show that fabrics woven from yarns formed from a polymer blend according to the invention and which include an organosilicon polymer component are expected to be more resistant to contamination than comparable fabrics which do not contain the organosilicon modified component.

3, High Pressure Shower Damage Resistance Papermaking fabrics such as forming fabrics are usually cleaned during the return run portion of their operation using high pressure needle jet showers so as to remove contaminants and other foreign matter from their surfaces. As noted above, these showers can cause monofilament fibrillation and holes to appear in the fabric structure, thus rendering it unsuitable for continued use. Thus, it is important that the fabric and their component yams be as resistant as possible to such damage.

To determine their resistance to high pressure shower damage, a test has been devised in which a woven fabric sample is tensioned across an open span and subjected to showering by a high pressure needle shower. The fabric is continuously monitored and the time taken for the first visible sign of damage is recorded. The longer it takes for visible damage to occur in the fabric sample is an indicator that the sample is more resistant to shower damage than another sample whose time to become damaged is less. Table 3 below provides data with respect to three samples which were compared with respect to their resistance to shower damage. Table 3 : Fabric High Pressure Shower Damage Resistance

In Table 3, Sample G was a fabric in which monofilament yams comprised of the polymer blend disclosed in the Ί 20 and '71 1 patents (Bhatt et al. - 60% high IV PET, plus 40% TPU & 3% pbw PCDI masterbatch to provide from about 0.45% pbw to about 0.5 % pbw carbodiimide content in the monofilament were positioned in the machine side surface (MS ) of the fabric and thus exposed directly to the high pressure shower. Sample H contained yams formed from a polymer blend of the present invention which are comprised of PET, TPU and from 5- 15% pbw PCDI in a masterbatch so as to provide a carbodiimide content of from about 0.75% pbw to about 2.25% pbw in the yarns. Sample I was comprised of the same polymer blend as Sample H, but the TPU was replaced by an organosilicon modified TPU containing 5% of an organosilicon material (LSE).

As can be seen from the data presented in Table 3, fabrics woven from yarns comprised of PET, TPU and from 2-3 times the amount of PCDI stabilizer required in the prior art (Sample G ) exhibit more than 100% improvement in shower damage resistance, while similar fabrics to those in Sample H but which contain about 5% pbw organosilicon in TPU provide even further benefit.