CA2313866A1 - Polymer blends of trimethylene terephthalate and an elastomeric polyester - Google Patents

Abstract

A polymer blend consisting essentially of at least 50% by weight, based on the total weight of the composition, of polytrimethylene terephthalate and a polyamide. Oriented fibers and extrusions produced from the polymer blend are durable under repetitive compressive stresses, exhibit mechanical properties comparable to neat polyamide-6, and provide moisture stability similar to yarns and extrusions comprised of polyamide-6/10 or polyamide-6/12.

Description

Polymer Blends o~f Trimethylene Terephthalate and a Polyamide Field of the Invention The present invention relates to a polymer blend consisting essentially of from about 50~ to about 95~ of polytrimethylene terephthalate and of from about 5~ to about 50~ a polyamide, based on the total weight of the polymer composition. The polymer blend can be used in the fabrication of industrial fabrics that are particularly suitable for use in rigorous environments, where the dimensional stability and mechanical properties of the fabrics are important.
~ackQround of the Invention Modern industrial fabrics are commonly assembled by weaving, braiding, knitting, knotting and other known methods from polymeric monofilament or multifilament yarns. It is also known from EP 802280 to assemble such fabrics from a plurality of extruded polymeric strips or panels. The chosen polymers are most frequently polyesters, copolyesters, polyamides, polyphenylene sul:Eides, polyphenylene oxides, fluoropolymers or polyketones. Selection of any particular polymer for a specific application will generally be dictated by the physical and mechanical properties desired, the cost of the polymer, and the prevailing environmental conditions of the end use.
The present i.nventi.on is primarily concerned with a polymer blend for use in fabricating industrial fabrics intended for environments where the dimensional stability and resistance to repetitive compressive stress of the fabrics are important. The invention is thus particularly relevant to papermaking fabrics which are used to form, drain, dewater and convey a paper web as it is created within a paper making machine.
For the purposes of this application, the term "fabric" is taken to mean an assembly of components. The term "component" is taken to mean any of t:he components from which a fabric can be assembled, such as yarns (including monofilament, multifilament and spun forms) oz: extrusions. The components forming the fabric can be arranged by interlacing, entangling or engagement so as to form an integrated cohesive structure, such as nets, cloth, felts, textiles and the like, which. are created by weaving, knitting, knotting, joining, felting, needling, spiral winding, bonding, or similar methods. Typical components include individual monofilaments, multifilaments, spiral coils, and profiled plastics extrusions such as strips, tiles or panels.
These components are generally fabricated by an. appropriate method such as melt extrusion, melt spinning, casting or slitting from an extruded :film. The fabricated components are then joined to form an integrated cohesive structure.
In a papermaking machine, a paper web is created in three stages. In the forming section, a water based stock of papermaking components is discharged onto a moving continuous forming fabric. As the fabric conveys the stock through the forming section, :it is .drained and agitated to provide a somewhat self supporting wet paper web. Drainage of the stock is augmented by various stationary elements with which the forming fabric. is in moving contact:. The web is then transferred to the press section where a major proportion of the remaining water is removed by mechanical pressing in a series of high pressure nips between opposed press rolls. Press fabrics are used both to convey the web, and to receive expelled water. The web then

- 2 -passes to the dryer section, in which it is conveyed on at least one dryer fabric over a series of heated cylinders where the remaining water is removed by evaporation. The resulting paper is then calendered, slit and wound onto reels.
Papermaking fabrics must ideally possess multiple characteristics simultaneously:
(a) they must: be resistant to abrasive wear caused by their passage over the various stationary elements in the paper making machine, and by contact with solids in the stock which they a.re to convey:
(b) they must be structurally stable, so as to function as designed within the range of stresses imposed during their use;
(c) they must: resist dimensional r_hanges in the plane of the fabric due to moisture absorption over a wide range of moisture contents;
(d) they must, resist stretching under the tension imposed by the powered rolls which drive the fabrics on the machine:
and (e) they muat be resistant to degradation caused by the various materials present in both the fiber-water slurry and in the materials. used to clean the fabrics, at the prevailing temperatures of use.
In addition, some industrial fabrics, such as press felts used in the press section of a papermaking machine, must be resistant_to compaction and repetitive cyclic compressive stress.
Of the various polymers available for industrial fabrics applications, those most commonly used in paper making are:
- polyesters, in particular polyethylene terephthalate (PET) and various copolymers thereof, and - polyamides, particularly polyamide-6 (also known as polycaprolactam), and polyamide-6/6 (also known as polyhexamethylene adipamide).
Although yarns and extrusions formed from both polymer types offer certain advantageous characteristics, there are essentially two difficulties associated with their use:
(i) while PET generally provides adequate chemical resistance and dimensional stability, and is also amenable to weaving, having good crimpability and heatsetting behaviour, its abrasion and compaction resistance are not always adequate, especially in higher speed paper machines; and (ii) although both polyamide-6 and polyamide-6/6 have adequate abrasion and. comp~action resistance, they do not possess adequate dimE~nsional stability in the moisture range found in the paper making environment, and the. mechanical properties of yarn~~ aid fabrics made from them are known to change.
US 5,137,601 to Hsu discloses papermaking fabrics, in particular press felts, whose component fibers and filaments are fabricated from polypropylene terephthalate, herein after referred to as PfT. In view of the use of "propylene" in the polymer name, this appears to be a polymer of terephthalic acid and 1,2-propanediol. The fabrics are alleged to have chemical resistance properties similar to polyester, and physical properties comparable to polyamide-6. There is no disclosure of suitable intrinsic: viscosities for the PPT, no identification of suitable grades, no discussion of the possibility of blending PPT
with a second poJ_ymer, nor are there any teachings to suggest that this polymer may be' suitable to withstand repetitive cyclic compressive stress.

Best, in EP 844320, discloses monafilaments for use in paper making machine clothing whose principle :.component is polytrimethylene terephthalate (described by Best as PTMT, and stated to be a polymer of terephthalic acid and 1,3-propanediol).
In a preferred embodiment, the PTT may be blended with up to 45$
by weight of polyurethane so as to improve the abrasion resistance of the monofilaments. There is no disclosure of the appropriate grade or intrinsic viscosity for a suitable PTT, nor does the disclosure teach that blending of PTT with any polymer other than polyurethane will improve the ability of the components to withstand repetitive cyclic compressive stresses and therefore increase the service life of the components.
Specifically, there is no disclosure or suggestion that other polymers may prov_Lde satisfactory results.
Despite these innovations, and for various other reasons including the cost of the raw materials, neat polyamide yarns are still preferred for many industrial fabric applications. The term "neat" as used herein refers to a polymer system containing only one polymer, e.g. polyamide-6, and nothing else. The compaction and abrasion resistance of these polyamide based yarns is useful in physically demanding applications, such as paper makers press felts, filtration fabrics, and the like.. However, the fact that thE~se polyamide yarns absorb moisture, and thus undergo physical changes in their mechanical properties, dimensions and weight when the environment of use exposes them to different moisture conditions, limits their use in moist environments where such variations often cannot be tolerated.
This difficulty is discussed inter olio in US 4,529,013, US
4,289,173 and DE 2,502,,466 which teach that fabrics including more than 50~ pol.yamide yarns tend to grow or stretch as they absorb moisture in a wet environment, and will shrink as they dry out, thus rendering the fabric unstable on the machine.
To circumvent these dimensional stability problems, fabric manufacturers have turned to substantially more costly polyamides, such ass polyamide-6/10 and polyamide-6/12, especially in instances where wet-to-dry dimensional stability is crucial.
However, the cost of these polymer resins is approximately three times greater than either polyamide-6 or polyamide-6/6. E5lrther, polyamide-6/10 and polyamide-6/12 yarns have comparatively poorer thermal properties, making them attractive for only a limited number of very specific: applications.
While the moisture stability performance of polyamide-6 and polyamide-6/6 yarns has been improved, yarn manufacturers have as yet been unable to address effectively the special combination of requirements necessary for paper machine clothing applications, in particular: cost, wet-to-dry dimensional stability, and resistance to both abrasive wear and repetitive compressive stress cycling.
Polytrimethylene terephthalate, herein referred to as PTT, which is also known as poly(1,3-propanediol terephthalate), is a polymer that has recently become commercially available. PTT
appears to combine a number of the mechanical properties of both polyesters and polyamides. PTT is commercially available from Shell Chemical Co. of Houston, Texas under the trade name CORTERRA'n' and is stated to be the reaction product of purified terephthalic acid and 1,3-propanediol. Two grades of PTT are currently available in bulk: carpet grade, which has an intrinsic viscosity as supplied of about 0.92 dL/g, and a second grade which has an intrinsic viscosity as supplied of about 1.3 dL/g. In both cases, the intrinsic viscosity quoted is measured according to ASTM D4603-96 on the bulk resin prior to extrusion into monofilament.s: the intrinsic viscosity when measured on monofilaments of extruded PTT is somewhat lower. Unless indicated otherwise, all intrinsic viscosity values quoted herein are determined by this ;procedure.
The present inventors have discovered that industrial fabrics whose components are comprised of at least 50~ to about 95~ by weight of :PTT, and from about .i0$ to about 5$ by weight, based on the total. weight of the composition, of a polyamide, are as resistant to compaction, and are able to withstand cyclic repetitive stresses as well as components fabricated from polyamide-6/10 or polyamide-6/12 while retaining their dimensional stability. The components are found to be as chemically stable as those formed from PET and are.amenable to weaving when formed into monofilament or multifilament yarns.
The finished PTT Y>lend components are thus particularly suitable for use in the assembly of industrial fabrics such as press felts for papermaking machines. Components fabricated from neat PTT
having an intrinsic viscosity of about 0.92 dL/g or less cannot survive exposure to about 9,000 cycles of repetitive cyclic compressive stress (under the test conditions set out below) without catastrophic failure. We have now discovered that if at least about 5~ by weight of a polyamide is added to the PTT, then components formed from. the resulting blend exhibit sufficient resiliency to survive exposure to at least 54,000 cycles of compressive strE:ss. The resistance to repetitive cyclic compressive stresa exhibited by components formed from a blend of PTT having an ini~rinsic viscosity of about 0.87 dL/g, and from about 5~ up to at least about 30~ of a polyamide, is about equal to that of similar components formed from neat PTT resin having _ 7 _ an intrinsic viscosity of about 1.3 dL/g. Components fabricated from a blend of from about 95$ to about 50~ by weight PTT (having an intrinsic viscosity before processing of from about 0.87 dL/g to at least 1.3 dL/g), end from about 50~ to about 5~ by weight based on the total composition of a polyamide appear to exhibit resistance to repetitive cyclic compressive stress that is roughly equivaleni~ to that obtained from components formed from neat polyamide-6, polyamide 6/6 or polyamide-6/12. Thus components formed from blends of PTT having a bulk intrinsic viscosity in the range of from about 0.87 dL/g to at least 1.3 dL/g appear to be suitable for use in industrial fabrics intended for environments. where resistance to repetitive cyclic compressive stre:>s, abrasive wear, chemical degradation and dimensional. stability under changing moisture conditions are important.
Rricf Descr~nt~on sf th Drawing Figure 1 shows diagrammatically the wet-to-dry dimensional stability of monofilaments prepared from neat polyamides, neat PTT, and from a PTT/pol.yamide blend.
y,~ry of the Invention In its broadest embodiment, this invention seeks to provide a thermoplastic polymer blend consisting essentially of from about 95~ to aboui~ 50~ by weight, based on the total composition, of polytrimethylene terephthalate(PTT), having an intrinsic viscosity from about 0.87 dL/g to at least about 1.3 dL/g, and from about 5~ to about 50~ of a polyamide.
In a first more narrow embodiment, the present invention seeks to providE: components which can be assembled into an industrial fabric which are fabricated from a thermoplastic _ g _ polymer blend consisting essentially of from about 95~ to about 50~ by weight, based on the total composition, of polytrimethylene terephthalate(PTT), having : an intrinsic viscosity from about 0.87 dL/g to at least about 1.3 dL/g, and from about 5~ to .about 50$ of a polyamide.
In a second narrow embodiment the present invention seeks to provide industrial fabrics including components fabricated from a polymer blend consisting essentially of from 95~ to about 50~
by weight, based on the total composition, of polytrimethylene terephthalate(PTT), having an intrinsic viscosity from about 0.87 dL/g to at least about 1.3 dL/g, and from about 5~ to about 50~
of a polyamide.
Components such as yarns(monofilament, multifilament and spun) and extrusions formed from this polymer blend can be assembled either alone, or in admixture with components fabricated from other materials, to provide fabrics which are resistant to cyclic repetitive compressive stress and fibrillation, as well as to permanent deformation caused by compressive stress.
Preferably, the intrinsic viscosity of the PTT resin from which the yarns or extrusions is produced is at least 0..87 dL/g:
more preferably, the intrinsic viscosity is at least about 0.92 dL/g. _ Preferably, the polyamide is an aliphatic polyamide.
The polymer blend may also contain from about 0.05 to about 5$ by weight based on t:he total weight of the composition of one or more conventional additives, such as stabilizers, plastic _ g _ processing aids, colourants, and inhibitors of oxidative, hydrolytic or thermal degradation. The amount and type of additive used blend will be dependent upon the intended end use of the polymer blend.
Preferably, t:he components of the industrial fabrics of this invention are monofilaments or multifilaments which are assembled by weaving. Alternatively, the components are extruded strips or panels which are assembled by snap/press fitting, spiral winding or by rapier insertion according to the methods described by Baker in EP 802280.
Preferably, all of the components of the industrial fabrics of this invention are fabricated from the PTT blend.
Alternatively, at least some of the components that are oriented in the direction of a tensional load placed on the fabric under its conditions oiE use are fabricated from the PTT blend. As a further alternative, air least some of those components that are oriented in a direct=ion within the plane of the fabric substantially per~oendicular to the direction of a tensional load placed on the fabric under its conditions of use are fabricated from the PTT blend.
D_Ptey ~ ed DeSCr'l~f'' ~'n of tha TnvantlOn ' Components of the industrial fabrics of this invention are produced using known methods of melt extrusion from a blend_of PTT polymeric resin having an intrinsic viscosity of at least about 0.87 dL/g together with a thermoplastic polyamide, using a conventional single or twin screw extruder under conditions suitable for the polymer blend involved. From about 95$ to about 50~ by weight based on the total composition of the PTT resin, together from about 5$ to about 50~ by weight of the polyamide, and from about 0.5~ to about 5$ by weight of any additives (so as to produce a blend whose components total 100 by weight), are metered to the e~arudei: either as separate streams or as a mixture. The polymer resins and any additives are mixed and melted in the extz:uder at a temperature of from about 230°C to about 310°C . As the extruder screw ( s ) conveys the components forward, the molten and thoroughly blended resin is fed into a metering pump that drives the blended resin mixture through a die to form a molten extrudate. The extrusion temperature is preferably from aY>out 2:30°C to about 310°C, and more preferably is from about 240°C to about 280°C.
The molten e:~trudate can be quenched in air or watery water quenching is preferred. For the production of monofilaments, the solid extrudate is drawn into yarn at room or an elevated temperature in a multi-stage draw process. For the compositions disclosed herein, the preferred range for the drawing temperature is from about 65°C to about 260°C, with energy being supplied between independently speed controlled godets that provide a final draw ratio of from about 3:1 to about 6:1. The final yarns are allowed to relax about 0-25$ by passing them through a relaxing stage at. a temperature of from about 65°C to about 260°C: the yarns aoe then wound onto spaols. The preceding normal processing conditions have been found to provide acceptable results others may prove suitable.
PTT yarns produced from neat PTT resin whose intrinsic viscosity is from about 0.86 dL/g to about 0.92 dL/g or less, known as carpet grade, do not offer the necessary mechanical integrity required for repetitive compressive stress applications. Although the wet-to-dry dimensional stability of yarns formed from this range of intrinsic viscosities is excellent, as well as their mechanical properties as measured by traditional test methods (e.g. percent elongation) compared to a neat polyamide-6 yarn, the performance of these PTT yarns under repetitive cyclic compressive stress is poor.
This is demonstraated in the following tests, where the resistance of yarns formed from neat polyamide-6 to repetitive compressive stress is compared to the following:
(a) yarn extruded from neat polyamide-6/6;
(b) yarn extruded from neat polyamide-12~
(c) yarn extrudE:d from neat PTT palymeric resin having an intrinsic viscosity of 0.87 dL/g,:
(d) yarn extrudE~d from neat PTT polymeric resin having an intrinsic viscosity of 1.3 dL/g,;
(e) yarn extrudE:d from a blend of PTT having an intrinsic viscosity of about 0.87 dL/g with from 5~ to 30~ by weight of polyamide-12~ and ( f ) yarn extrudESd from a blend of PTT having an intrinsic viscosity of about 0.87 dL/g and about 5$ polyamide-6.
In these and later tests, the control yarns of neat polyamide-6 resin. were extruded from Ultramid~ X-301 available from BASF, the control yarns of neat polyamide-6/6 were extruded from DuPont FE3077L polyamide-6/6 resin available from E.L. DuPont de Nemours Co., Vilmington, Delaware, and the control yarns of polyamide-12 were extruded from Rislan Aesno polyamide-12, available from Elf Atochem North America of Philadelphia, Pennsylvania. Twro samples of PTT were used. One sample had an intrinsic viscosity of 0.87 dL./g, and was obtained from the Degussa Co.: as supplied this polymer was not identified by a grade or other designation. The other sample had an intrinsic viscosity as supplied of 1.3 dL/g, and was Corterra CP51300, r which is available from Shell Chemical Company, of Houston, Texas.
In these tests, yarns were produced from PTT blended with polyamide in amounts of from about 5~ to about 30$ by weight, based on the total composition. The polyamides used in the blends were polyamide-6 and polyamide-12.
The monofilaments were produced as follows. Each of the polyamide-6, polyamide-6/6, polyamide-12, neat PTT samples and PTT resin/polyamide-12 blends, were fed through a single screw extruder at a melt temperature of about 280°C. Oriented strands were produced from the extrudate using conventional godet and hot air oven technology to achieve the necessary drawing. The oven temperatures were about 200°C and overall draw ratios of about 4 were used. The final monofilaments had a diameter of about 0.20 mm.
The monofila:ment samples were first tested to determine their wet-to-dry dimensional stability. The wet-to-dry dimensional stability of a monofilament was determined using the following method. Fiber samples greater than 1 meter in length were obtained from each of the control and test monofilaments.
These samples were first conditioned by exposing them to air at 23°C and 50~ relative humidity for 24 hours. Each sample was then cut to a convenient length, typically l meter. The samples were then immersed in distilled water at room temperature for 24 hours, removed from the water, blotted surface dry, and their wet length accurately measured. The samples were then again exposed to air at 23°C and 50$ relative humidity for 24 hours, and their dry length then measured. The wet and dry cycle measurements were then repeated. The changes in length are expressed as a percentage, and the: average percent change in length over the two wet to dry cycles is taken as being indicative of the stability of the monofilament under these conditions. -Figure 1 shows that the percent change in the length of the control monofilament made of neat polyamide-6 was about 3.5$ and that of the monofilamen,ts made from the PTT blends was about 0.3$. This test demonstrates that the monofilaments produced from the PTT blends have superior wet-to-dry dimensional stability when compared to monofilaments produced from a neat polyamide-6 resin.
The resistance to repetitive compressive stress cycling of monofilaments formed from neat PTT whose intrinsic viscosity is from about 0.87 to about 0.92 dL/g (the intrinsic viscosity of the PTT in the finished yarn is lower) is poor and their physical response, as determined by their loss in diameter and gross failure by fibrillation, is unacceptable for paper machine clothing applications. 'This was surprising, as this grade of PTT
is supplied as "carpet grade", which was expected to withstand repetitive compressive stress . There was no way to predict priori that this material would not be suitable in applications where resistance to repeated compressive stress is important, such as clothing i:or a papermaking machine.
Table 1 provides test data to illustrate this case. In this test, monofilaments formed from the polyamide-6 control resin, neat polyamide-6/Ei, newt polyamide-12, two grades of neat PTT "
and various blends of PTT with polyamide-12, were each subjected to a repetitive cyclic compressive stress test to simulate the compressive stress cycling experienced. by a paper machine press felt passing through a nip under load. In this test, a pressure of approximately 7.3 MPa at 40°C was applied at a frequency of 300 compression per minute for 180 minutes using a laboratory scale dynamic compaction tester to simulate 54,000 compression cycles. The samples are each wrapped around a notched crossover plate so as to create a grid which simulates a press felt base weave with a mes'.h of :L6 x 16 yarns per cm. The samples and crossover plate are then placed in the dynamic compaction tester where they are subjected to repeated compression under constant load and recovered under zero load. The samples are removed at specific time intervals and examined for damage. Table l shows the calculated physical response of all of the monofilaments, based on a summary of test samples, as determined by their percent loss in original diameter following 54,000 cycles of compression and relaxation.
In Table 1, PA-6 refers to polyamide-6; PA-6/_6 refers to polyamide-6/6; PA--12 refers to polyamide-12; PTT(A) refers to PTT
yarns formed from resin having an intrinsic viscosity of 0.87 dL/g as supplied: PTT (l3) refers to PTT yarns formed from resin having an intrin~;ic viscosity of 1.3 dL/g as supplied; and all blends total 100$.

Percent Diameter Loss of Monofilaments under Repetitive Compressive Stress.
Number of Compression Cycles Yarn Composition 9,000 18,000 27,000 36,000 54,000 PA-6 33.7 38.1 40.9 43.1 46.2 PA-6/6 28.8 33.3 36.3 38.6 42.0 PTT(A)~ Samples failed before 9,000 cycles 95$ PTT(A),5$ P.A-12 33.6 38.3 42.1 44.7 48.6 90$ PTT (A) , 10$ F?A-1233. 5 39..3 43. 0 46. 0 50.4 80$ PTT(A),20$ ~?A-12 38.6 52.5 46.2 49.0 53.3 70$PTT(A), 30$ ~'A-12 41.5 46.5 49.7 52.2 55.8 95$ PTT(A), 5$ PA-6 31.2 37.0 40.8 43.7 48.3 PA-12 21.1 26.0 29.4 32.2 36.4 PTT(B) 18.9 23.6 26.8 29.3 33.3 Table 1 showa that yarns fabricated from PTT(A), which has an intrinsic viscosity of about 0.87 dL/g as supplied, do not survive the repetitive cyclic compressive stress test. However, following addition. of from 5$ to about 30$ polyamide-12,.or of 5$
polyamide-6, to PTT(A), the yarns are now able to survive the test and suffer a diameter loss that is comparable to that found for the neat polyamide-6. and polyamide-6/6 control yarns, and-is similar to that for PTT(B). However, as shown in Figure 1, the yarns based on PTT do not suffer rom the dimensional stability problems of neat ~polyamide-6.

The results displayed in Table 1 also show that a yarn product formed from the PTT having an intrinsic viscosity of about 0.87 to about 0.92 dL/g as taught by the prior art is not viable in applications where resistance to repeated compressive stress is important, such as in papermaking machine press felt fabrics.

Claims (14)

What is Claimed is:

1. A thermoplastic polymer blend consisting essentially of from about 95% to about 50% by weight, based on the total composition, of polytrimethylene terephthalate (PTT), having an intrinsic viscosity from about 0.87 dL/g to at least about 1.3 dL/g, and from about 5% to about 50% by weight of a polyamide, the intrinsic viscosity of the PTT being measured according to ASTM
D4603-96.

2. A component which can be assembled into an industrial fabric which is fabricated from a thermoplastic polymer blend consisting essentially of from about 95% to about 50% by weight, based on the total composition, of polytrimethylene terephthalate (PTT), having an intrinsic viscosity from about 0.92 dL/g to at least about 1.3 dL/g, and from about 5% to about 50% by weight of a polyamide, the intrinsic viscosity of the PTT being measured according to ASTM D4603-96.

3. An industrial fabric including components fabricated from a polymer blend consisting essentially of from about 95% to about 50% by weight, based on the total composition, of polytrimethylene terephthalate (PTT), having an intrinsic viscosity from about 0.92 dL/g to at least about 1.3 dL/g, and from about 5% to about 50% by weight of an elastomeric polyester, the intrinsic viscosity of the PTT being measured according to ASTM D4603-96.

4. A thermoplastic polymer blend according to Claim 1 wherein the polyamide is an aliphatic polyamide.

5. A component according to Claim 2 chosen from the group consisting of yarns and extrusions.

6. A component according to Claim 4 which is a yarn chosen from the group consisting of monofilament yarn, multifilament yarn and spun yarn.

7. A polymer blend according to Claim 1 wherein the intrinsic viscosity of the PTT resin from which the polymer blend is produced is at least about 0.92 dL/g.

8. A thermoplastic polymer blend according to Claim 1 further including from about 0.05% to about 5% by weight based on the total weight of the composition of one or more conventional additives.

9. A thermoplastic polymer blend according to Claim 8 wherein the additives comprises at least one member chosen from the group consisting of stabilizers, plastic processing aids, colourants, and inhibitors of oxidative, hydrolytic or thermal degradation.

10. An industrial fabric according to Claim 3 assembled by weaving components chosen from the group consisting of monofilaments and multifilaments.

11. An industrial fabric according to Claim 3 assembled by a method chosen from the group consisting of snap/press fitting, spiral winding and by rapier insertion, and wherein the components are extruded strips or panels.

12. An industrial fabric according to Claim 3 wherein all of the components of the industrial fabric are fabricated from the blend of PTT and an elastomeric polyester.

13. An industrial fabric according to Claim 3 wherein at least some of those components that are oriented in the direction of a tensional load placed on the fabric under its conditions of use are fabricated from the blend of PTT and a polyamide.

14. An industrial fabric according to Claim 3 wherein at least some of those components that are oriented in a direction within the plane of the fabric substantially perpendicular to the direction of a tensional load placed on the fabric under its conditions of use are fabricated the blend of PTT and a polyamide.