GB2308598A - Dispersed polymer blend - Google Patents

Description

DISPERSED POLYMER BLEND This invention relates to polymer blends. More particularly, this invention is directed to improving the wear the properties of thermoplastic polymer blends.

The tribological properties of a polymer can sometimes be improved by the addition of certain lubricants. Not all lubricants act in the same manner and not all will improve tribological properties. Indeed, the term "lubricant" is a relative term as "lubricating" the polymer can refer to a number of different phenomena.

Lubricating polymer additives can generally be classified as external or internal lubricants. Internal lubricants are useful as processing aids which act to lessen intermolecular attraction in the bulk polymer.

Internal lubricants thus make the polymer more workable than it might otherwise be by such means as lubricating the shear surfaces of the extruder through which they are processed. They are not generally employed to contribute to the overall wear properties of the polymer in which they are added.

External lubricants, on the other hand, reduce the adhesion between two surfaces. They may be added to a polymer expressly for the purpose of improving its wear properties and can make the polymer more suitable for use in such applications as gears, bearings, cams, and the like. Other factors being equal, the effectiveness of one external lubricant relative to another will depend on the degree to which it is present at the area or point of contact between two or more materials. Thus, dispersion of the external lubricant in the polymer matrix to which it is added is an important factor in preparing a polymer for tribological applications. Lubricant dispersion in a polymer involves minimizing lubricant particle agglomeration and maximizing the uniformity of the distribution of the particles.It is possible to affect either phenomena or both depending upon the mechanism by which dispersancy is attained.

Some fluoropolymers such as polytetrafluoroethylene (PTFE) have found extensive utility as external lubricants in certain polymer blends. However, as is true of all additives, the suitability of the additive is largely governed by the degree to which it can be compatibly maintained in the polymer matrix. The perfectly alternating polymers of carbon monoxide and olefins mentioned above are generally referred to as aliphatic polyketones and are now well known in the art.

Unfortunately, the use of PTFE as an additive to enhance the tribological properties of the polymer has been inhibited by the pronounced agglomeration of PTFE and the nonuniform distribution of the agglomerates in the polymer matrix. PTFE is nonpolar and such polyketone polymers are polar. When such a blend has been attempted, the PTFE particles have been found to agglomerate forming aggregates on the order of 100-200R.

This agglomeration reduces the efficacy of the lubricant since it cannot be placed uniformly across the area of contact between the polymer and the material with which it will be in contact. This can lead to inferior wear properties and a reduction in impact properties.

PTFE particle agglomeration must generally be kept at about 30y or less for any polymer to experience an improvement in wear properties--a fact not previously recognized in the art. When PTFE has been added to a polymer and the blend has been found not to improve in wear properties, the problem has generally been addressed by increasing the PTFE load. This approach may result in a more uniform distribution of lubricant particles but will do nothing to diminish agglomeration. While this will generally improve wear properties it is not a desirable approach due to the expense of the additional PTFE and the adverse impact of high additive loads. Such high levels of additive loading diminish the other desirable properties for which the polymer matrix was selected in the first place.Increasing the PTFE load in polyketone blends to overcome this problem has proven undesirable for many applications since PTFE loads greater than about 10 %wt noticeably reduce the impact properties of the polyketone polymer.

Silicone oils have been used as both external and internal polyketone polymer lubricants. The use of silicone oil can be tricky. Employing a low viscosity additive will improve the processability of the polymer but can adversely affect the modulus of the polymer at the loading levels needed to exhibit the desired processability effect. Employing high viscosity silicone additives may improve the dynamic coefficient of friction of the polymer without performing the desired role of internal lubrication (i.e., a processing aid). Silicone oils have been used to some beneficial effect in polyketones. However, where this has been done, external lubrication has generally required the use of high viscosity silicone oils at loads greater than about 1 %wt (preferably greater than about 2 %wt) and has resulted in an improvement (reduction) of DCOF on the order of about 50%.It is still desirable to further improve the tribological properties of polyketone polymers and extend the available choices of blends capable of doing so.

US Patent 3,449,290 to Foster proposes a specific elastomeric combination comprising a polysiloxane gum, polytetrafluoroethylene, an end-blocked polysiloxane oil, and a mixture of reinforcing and extending fillers. The addition of the polysiloxane oil and reinforcing and extending agents requires severe and prolonged shearing action for effect and the effect that is attained is an improvement in processability. There is no noted improvement in tribological properties of the materials.

Further, even this effect is not attainable without the inclusion of both reinforcing and extending fillers.

About 75 parts by weight filler and 50 parts by weight extender per 100 parts by weight polysiloxane gum are used. Such additive loadings would diminish the properties necessary to use most polymers in tribological applications. Thus, the multifarious components and high loads required by Foster would militate against such an approach in polyketones.

US Patent 5,006,581 to Nakame et al proposes a blend comprising a synthetic resin, a modifier (such as PTFE), and a dispersability improver. The dispersability improver therein proposed is a silicon containing polyester. That is, the dispersability improver was a copolymer of a siloxane and a polyester such as a polymer of esterified terepthalic acid. It appears that the dispersability improver must be a copolymer of the type described to prevent decomposition or bleeding of the material during processing. The synthetic resins of this patent do not include polyketones.

US Patent 4,959,404 to Nakame et al proposes a blend comprising a thermoplastic, a modifier (such as PTFE), and a dispersability improver. The dispersability improver therein proposed was a silicon containing polyacetal copolymer. The silicon containing portion of the copolymer is between 0.01 and 30 kwt of a material derived from a silicon oil. It appears that the dispersability improver must be a copolymer of the type described to prevent decomposition or bleeding of the material during processing. The thermoplastics of this patent do not include polyketones. The rationale supporting both Nakame patents incorporates a traditional polymer blending approach: to blend two materials together one should seek an agent (here a dispersability improver) which is structurally and functionally compatible with both. Hence, the copolymerization of the siloxane.While finding the best agent for accomplishing such a task is not necessarily easy, Nakame's approach would suggest that dispersing PTFE in polyketones would require an agent which itself was more compatible with the polymer matrix than is a silicone oil (it too is nonpolar).

US Patent 4,931,710 to DeVara and Kenny proposes a servoactuator wherein the motor drive pinion is made of polymer made by blending polyimide, about 18 kwt chlorofluorinated polymer, and about 2 kwt unspecified silicone lubricant. The patent provides no further information regarding the nature of this polymer.

Nothing is known of its tribological properties nor is anything known of how it is prepared. It is worth noting, however, that it is loaded with at least about 20 %wt additives. Such loading is undesirable for most polyketone tribological applications since one may diminish the physical/mechanical properties.

US Patent 4,556,604 to Ohbayashi proposes employing a graphite material in concert with a silicone oil as a means for adhering the silicone oil onto a magnetic recording medium. The graphite may be fluorinated and must have a particle size of less than 2p(0.01-0.1 are preferred). The inventors further warn against deriving the fluorinated graphite from a carbonaceous material having particle sizes on the order of 10p as an unsuitable material would result from its use.

Consistent polyketone polymer blends having relatively low additive loading levels and exhibiting improved tribological properties are still desired.

A method for enhancing the tribological properties of thermoplastic polymers is presented in which thermoplastic polymers are blended with PTFE and a dispersing agent comprising silicon oil. The silicone oil is a medium viscosity polysiloxane.

In one aspect of the invention, the blend comprises up to about 10 Awt PTFE and 2 kwt silicone oil, balance polyketone polymer.

In another aspect of the invention, the blend comprises up to about 10 %wt PTFE and less than 1 kwt silicone oil, balance polyketone polymer.

The PTFE particles in the material so blended have an average particle size of less than about 30 microns along their longest dimension and can be uniformly dispersed throughout the polymer matrix by practicing the method of this invention.

It has been found that the addition of certain silicone oils to a thermoplastic polymer/PTFE blend results in an improvement in one or more of the tribological properties of the polymers. These properties include a reduced coefficient of friction, an increased ability to sustain a load under a velocity, and a resistance to wear. Such improvements are achieved without significantly adversely affecting other important mechanical properties of the polyketone polymer.

Throughout this specification, the Dynamic Coefficient of Friction (DCOF), Limiting Pressure Velocity (LPV), and Wear Factors (K) will be referenced with respect to the following meanings. During relative motion of two surfaces in contact the DCOF is the ratio of the resulting frictional force to the applied normal force while holding the relative surface velocity constant over time. While holding the relative surface velocity constant between two specimens in contact and increasing the applied normal force in a stepwise manner in time, the LPV is the multiplicative product of the normal pressure and surface velocity at the step just prior to catastrophic material failure due to thermal softening.As performed on a thrust washer test apparatus using ASTM D3702, K is defined by the following relationship: K=W/FVT where W=volume wear in cubic inches, F=normal load in pounds, V=surface velocity in feet per minute, and T=test duration in hours.

Generally speaking, the materials useful in the practice of this invention include a thermoplastic polymer, fluoropolymers (fluorinated hydrocarbons) , one or more suitable silicone oils, and other common polymer additives. For instance, fillers, extenders, other lubricants, pigments, plasticizers, and other polymeric materials can be added to the compositions to improve or otherwise alter the properties of the composition. In general, the practice of this invention involves suitably intermixing sufficient quantities of the useful material to form the inventive blend.The most preferred thermoplastic polymers used in the blend of this invention are linear alternating polymer of carbon monoxide and at least one ethylenically unsaturated hydrocarbon (sometimes simply referred to as a polyketone polymer) . Other thermoplastic polymers can be used as the polymer matrix. These can include such polymers as, for example, polyethylene.

The polyketone polymers which are employed as the major component of the polymer composition of the invention are of a linear alternating aliphatic structure and contain substantially one molecule of carbon monoxide for each molecule of ethylenically unsaturated hydrocarbon. By aliphatic it is meant that the polymer backbone itself is aliphatic. It is possible to incorporate or append aromatic groups to the backbone and yet the polymer itself would be considered aliphatic since the polymer backbone itself would be comprised of substantially no aromatic groups as one would find in, for example, a PEEK polymer. The preferred polyketone polymers are copolymers of carbon monoxide and ethylene or terpolymers of carbon monoxide, ethylene and a second ethylenically unsaturated hydrocarbon of at least 3 carbon atoms, particularly an a-olefin such as propylene.

When the preferred polyketone terpolymers are employed as the major polymeric component of the blends of the invention, there will be within the terpolymer at least about 2 units incorporating a moiety of ethylene for each unit incorporating a moiety of the second hydrocarbon. Preferably, there will be from about 10 units to about 100 units incorporating a moiety of the second hydrocarbon. The polymer chain of the preferred polyketone polymers is therefore represented by the repeating formula

where G is the moiety of ethylenically unsaturated hydrocarbon of at least 3 carbon atoms polymerized through the ethylenic unsaturation and the ratio of y:x is no more than about 0.5. When copolymers of carbon monoxide and ethylene are employed in the compositions of the invention, there will be no second hydrocarbon present and the copolymers are represented by the above formula wherein y is zero. When y is other than zero, i.e. terpolymers are employed, the

units and the

units are found randomly throughout the polymer chain, and preferred ratios of y:x are from about 0.01 to about 0.1. The precise nature of the end groups does not appear to influence the properties of the polymer to any considerable extent so that the polymers are fairly represented by the formula for the polymer chains as depicted above.

The polyketone polymers of number average molecular weight from about 1000 to about 200,000, particularly those of number average molecular weight from about 20,000 to about 90,000 as determined by gel permeation chromatography are of particular interest. The physical properties of the polymer will depend in part upon the molecular weight, whether the polymer is a copolymer or a terpolymer, and in the case of terpolymers the nature of the proportion of the second hydrocarbon present.

Typical melting points for the polymers are from about 175 OC to about 300 "C, more typically from about 210 C to about 270 CC. The polymers have a limiting viscosity number (LVN), measured in m-cresol at 60 OC in a standard capillary viscosity measuring device, from about 0.5 dl/g to about 10 dl/g, more frequently from about 0.8 dl/g to about 4 dl/g.

Preferred methods for the production of the polyketone polymers are illustrated by U.S. Pats. Nos.

4,808,699 and 4,868,282 to van Broekhoven, et al which issued on Feb. 28, 1989 and Sep. 19, 1989 respectively and are herein incorporated by reference. U.S. Patent No. 4,808,699 teaches the production of linear alternating polymers by contacting ethylene and carbon monoxide in the presence of a catalyst comprising a Group VIII metal compound, an anion of a nonhydrohalogenic acid with a pKa less than 6 and a bidentate phosphorous, arsenic or antimony ligand. U.S. Patent No. 4,868,282 teaches the production of linear random terpolymers by contacting carbon monoxide and ethylene in the presence of one or more hydrocarbons having an olefinically unsaturated group with a similar catalyst.

Fluorinated hydrocarbons (fluoropolymers) useful in this invention typically have a melting temperature at least 10-20 degrees above 500 OF (5-10 degrees above 278 OC). Examples of such fluoropolymers include perfluoroalkoxy resin (PFA), ethylene-tetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP) and polytetrafluoroethylene (PTFE). PTFE is preferred. The fluoropolymers are generally present in an amount of from about 1-15 wt , and preferably from about 5-10 wt based on total blend composition.

The useful silicone oils can be described as linear chains of polydimethyl siloxane with medium viscosities.

For the purposes of this specification, a medium viscosity range for silicone oils is between about 10,000 and about 50,000 centistokes at 25 OC. High viscosity silicone oils (greater than about 60,000 cs) will not synergistically improve the effectiveness of PTFE as an external lubricant since it is difficult for such viscous materials to travel throughout the polymer. matrix. The most preferred silicone oil is a polydimethyl siloxane having a viscosity of about 30,000 centistokes at 25 OC.

These are commercially available from a variety of well known suppliers. Typically, silicone oil(s) are present in the blend in an amount of from about 0.1-5 wtt, and preferably from about 0.5-2 wtW.

Generally speaking, any conventional or known method for producing blends is considered suitable for blending the materials of this invention so long as a relatively uniform distribution of the components is obtained. In one embodiment, fluoropolymer powder is dry blended with silicone oil and metered upstream along with polyketone polymer pellets into a twin screw extruder/single screw extruder. The fluoropolymer powder/silicone oil blend can also be metered down-stream into a twin screw extruder while the polyketone polymer is metered upstream. Alternatively, a dry blend of polyketone polymer pellets, fluoropolymer powder and silicone oil can be metered up-stream into a twin or single screw extruder.

The inventive blend can be processed by conventional methods such as extrusion and injection moulding into various articles of manufacture which are particularly useful in applications such as in the manufacture of gears and bearings where good tribological properties are required.

The invention is further illustrated by the following non-limiting examples.

EXAMPLES In each of the examples that follow tribological properties were determined using a Computer Controlled Multi-Specimen Test Machine manufactured by Falex Corporation. In this testing, a thrustwasher injection molded from the material to be tested was spun against a steel stationary washer in one direction. Data logging for the following parameters was conducted continuously: speed, load, temperature, wear, and run time. LPVs, DCOF, and Wear Factors were computed from this data logging.

LPV was measured at 100 fpm velocity with stepped load increments to specimen failure. Specimen failure is the sudden loss of structural integrity at melt softening. DCOF measurements were performed at 10 ft/min with 10 lb increment increases at 15 minute intervals.

Wear tests were run at 8 lbs. load and 50 fpm velocity for 40 hours to seat the test specimens. Specimens were then run at the same conditions for about 212 hours on a new stationary washer. The test specimen and stationary washer were measured for thickness and weight before and after each run. The specific gravity of the test specimen was then incorporated into the computation of the resulting wear factor.

The blends were prepared by dry blending the components in a Welex blender and compounding them in a 25 mm Berstorff twin screw extruder operating at a melt processing temperature of between about 250 and 270 OC.

Sample test specimens were molded in the form of 1/16 inch thick, type V, ASTM D638 tensile bars on a Arburg injection moulder. Physical testing of the test specimens used a Instron Model 1123 tensile tester.

Cross sections of samples of the materials prepared in the Examples were also visually inspected using a microscope with and without the use of cross polars.

Magnification at 1000X and 1300X was used to analyze particle formation, particle characterization, and dispersion of the additives in the polymer matrix.

In each example in which silicone oil is a blend component, the silicone oil is a polydimethyl siloxane with a viscosity of about 30,000 centistokes at 25 OC commercially available through the Dow Chemical Company.

The PTFE used in these examples was "WHITCON-TL-6" brand PTFE commercially available from Whitcon.

Example Neat linear polyketone (terpolymer of carbon monoxide, ethylene, and a minor amount of propylene) having a melting point of about 220 OC and a limiting viscosity number of about 1.8 dl/g was prepared. The tribological properties were tested as set forth above.

The results of this testing is shown in Table 1.

Examples 2 and 3 (Comparative) Examples 2 and 3 are blends of polyketone polymer of Example 1 with 10 wtW and 15 wtW polytetrafluoroethylene (PTFE) respectively. Results are shown in Table 1.

Relative to Example 1, there was little improvement in LPV, but the DCOF dropped to 0.32 and 0.23 for examples 2 and 3 respectively. The high PTFE concentration in Example 3 appears to have a beneficial effect on DCOF. The Notched Izod values decreased from 4 ft-lb/in for the neat polymer (Example 1) to 2.4 and 2.5 ft-lb/in for examples 2 and 3 respectively. Also, the room temperature Gardner impact energy declined substantially. Finally, the elongation at yield (an indication of toughness) was reduced substantially for Examples 2 and 3 as compared to the neat polymer (Example 1).

Microscopy revealed that the PTFE agglomerated to form aggregates averaging between about 100 and 200p along their largest dimension. The particles are not uniformly dispersed throughout the polymer matrix and are irregularly shaped. The effect of the PTFE on the polymer was therefore very localized and nonuniform and interferes with the ability of the PTFE to plate out on the opposing surface in contact with a polyketone article as is necessary for good external lubrication.

This example shows that some improvement in tribological properties occurs with the addition of PTFE alone. However, in order to see significant improvement, one must substantially load the polymer with additive at which point mechanical properties begin to decline.

Moreover, even at high lubricant concentrations little if any improvement in the polymer's ability to sustain loads under a velocity is achieved.

Examples 4 and 5 Examples 4 and 5 are polyketone polymer of Example 1 blended with 10 wtW PTFE and 2.0 wtt silicone oil.

Results are shown in Table 1.

Relative to Examples 1, 2 and 3, there is a substantial increase in LPV for examples 4 and 5; 46,000 and 43,300 respectively. The DCOF values for Examples 4 and 5 are essentially equal to the value for Example 3 (containing 15 wt PTFE) and almost four times lower than that of the neat polymer. The wear factor for Example 5 is 73, which is considerably lower than the wear factor for the neat polymer (263). Also, the standard deviation (test error) is measurably higher for Example 1 as compared to Example 5, which is another indication that Example 5 is a better tribological material than the neat polymer.

Microscopy revealed that the PTFE was uniformly dispersed throughout the polymer matrix. PTFE particle size was between 5 and 30 microns throughout the specimen with the majority of the particles substantially less than about 15 microns along their largest detectable dimension.

These examples show that the silicone oil adheres preferentially to the PTFE and acts as a dispersing agent for the PTFE, thereby reducing coalescence during the compounding step. This results in superior tribological properties relative to polyketone/PTFE blends without the use of silicone oil. In addition, the good PTFE dispersion in Examples 4 and 5 also leads to improvements in impact energy and general overall toughness compared to Examples 2 and 3, which exhibit poor PTFE dispersion.

Example 5 Example 6 contains 0.5 wt% silicone oil and 10 wtW PTFE. Like Examples 4 and 5, Example 6 also possesses good triblcical properties; a LPV of 46,700, a DCOF of 0.35 and a 4 wear factor. Results are shown in Table 1.

In addition, the Izod impact energy and elongation at yield values were almost equal to those of Examples 4 and 5.

Microscopy revealed that PTFE particles were somewhat larger but were still less than 30 microns and uniformly dispersed throughout the polymer matrix.

This blend is comprised of a total additive load which is 4.5 %wt less than the blend of Example 5 (PTFE alone) and yet still attains significant improvement in tribological properties. This reduction in additive load benefits the overall mechanical properties of the blend so that wear properties are not improved at the expense of other important polymer characteristics.

Example 7 (Comparative) In this example, a blend is prepared in which the only lubricant additive to the polyketone of Example 1 is 2 %wt silicone oil. Results are shown in Table 1.

There is a slight improvement in LPV but the DCOF did not improve relative to neat polymer. Further, this blend was extremely difficult to process during injection molding. The relatively low viscosity of the silicone oil led to its migration out of the polymer and onto the screw making it difficult to fill the screw during each cycle. The PTFE/silicone oil blends did not suffer from this problem due to silicone/PTFE adherence.

The silicone oil appeared as round droplets in the sample under the microscope.

Table 1 Wear Properties and Mechanical Properties for polyketone Grades. The number in parenthesis is one standard deviation.

Example Silicone PTFE Final Limiting Wear Stress @ Elong @ Gardner @ Izod @ oil (wt%) (wt%) Dynamic PV Factor @ Yield Yield RT (in RT COF psi X PV=2000 (psi) (%) lb/in) (tt lb) ft/min @; 100 fpm 1 0 0 0.86 31500 263 8700 43 > 400 4.0 (0.12) (3800) (243) (120) (0.7) 2 0 10 0.32 35000 8200 39 71 2.4 (0.02) (5000) (140) (3.1) (4) (0.2) 3 0 15 0.23 35000 7910 35 44 2.5 (0.11) (5000) (92) (0.5) (4) (0.2) 4 2 10 0.21 46000 7520 53 230 3.8 (0.03) (7200) (110) (1.8) (13) (0.23) 5 2 10 0.21 43300 73 7700 52 -- 6.26 (0.02) (2900) (13) (80) (2.3) (0.62) 6 0.5 10 0.35 46700 64 8200 46 -- 3.5 (0.11) (10400) (10) (47) (1.0) (0.21) 7 2 0 0.9 35500 8220 (0.07) (1300) (96) Note: Testing was conducted utilizing a stainless steel stationary washer.

The specific gravity of the silicone oil of these examples is about .978 gm/cm3 while that of PTFE is about 2.14 gm/cm3/ Therefore, at equal weight concentrations, one would expect the silicone oil to display a higher volumetric concentration than PTFE. Thus, one would expect to find round droplets attributable to the silicone oil in the blends of Examples 4 and 5 as well as the blend of Example 7. However, this was not the case as PTFE particles were clearly the dominant features.

This is a further indication of the preferential adherence of silicon oil for PTFE resulting in enhanced particle dispersion.

Example 8 (Hypothetical) A polyethylene blend is prepared by drymixing polyetheylene and 10 kwt PTFE and then compounding the blend in the same way that the polyketone polymers are compounded. PTFE particle agglomerations from about 100-200 microns are readily observed in the polymer matrix through a microscope. The particles are not uniformly dispersed through the polymer matrix.

Example9 A polyethylene blend was prepared by drymixing polyethylene, 10 kwt PTFE, and 2 kwt silicon oil as described above. The average PTFE particle size was less than 30 microns and the particles were uniformly dispersed throughout the polymer matrix.

Claims (18)

1. A method of improving the dispersion of a fluorinated hydrocarbon polymer lubricant in a polymer blend comprising a thermoplastic polymer and a fluorinated hydrocarbon polymer comprising the step of adding a medium viscosity silicone oil to the said polymer blend so that the average particle size of said fluorinated hydrocarbon polymer in said blend is less than about 30.

2. The method of claim 1 wherein said lubricant is PTFE.

3. The method of claim 1 wherein said silicone oil is a polydimethyl siloxane having a viscosity between about 10,000 and 50,000 centistokes at 25 C.

4. The method of claim 3 wherein said silicon oil has a viscosity of about 30,000 centistokes at 25 OC.

5. The method of claim 1 wherein from about .5 to 5 kwt (basis total weight of blend) said silicone oil is added.

6. The method of claim 5 wherein from about .5%wt (basis total weight of blend) silicon oil is added.

7. The method of claim 2 wherein from about 1 to 10 kwt (basis total weight of blend) of PTFE is added.

8. The method of claim 1 wherein said polymer is a linear alternating polyketone.

9. A polymer blend comprising a thermoplastic polymer, a fluorinated hydrocarbon polymer, and a medium viscosity silicon oil.

10. The blend of claim 9 wherein said fluorinated hydrocarbon polymer is PTFE.

11. The blend of claim 9 wherein said silicone oil is a polydimethyl siloxane having a viscosity between about 10,000 and 50,000 centistokes at 25 OC.

12. The blend of claim 11 wherein said silicon oil has a viscosity of about 30,000 centistokes at 25 OC.

13. The blend of claim 12 comprising from about .5 to 5 %wt (basis total weight of blend) said silicone oil.

14. The blend of claim 13 comprising about .5 %wt (basis total weight of blend) silicon oil.

15. The blend of claim 14 comprising from about 1 to 10 %wt (basis total weight of blend) of PTFE.

16. The blend of claim 15 wherein said thermoplastic polymer is a linear alternating polyketone.

17. A polyketone polymer blend comprising polyketone polymer, uniformly dispersed 1-10 kwt PTFE (basis total weight of blend), and .5-2%wt silicon oil having a viscosity from 10,000-50,000 centistokes at 25 OC.

18. The blend of claim 17 wherein said silicon oil has a viscosity of about 30,000 centistokes at 25 OC.