Polymer composition and injection molded articles comprising the same

Abstract

Disclosed herein are polymer compositions comprising a polyaryletherketone (PAEK) polymer having a melt viscosity from 80 Pa*s to 220 Pa*s measured according to ASTM D3835 at 400 ℃ and 1000 s-1 shear rate, and also comprising a molecular sieve in an amount from 0.3 wt.% to 8.0 wt.%, based on the total weight of the polymer composition. Also disclosed herein are methods of making an article comprising the disclosed polymer compositions and articles comprising the disclosed polymer compositions.

Description

SSPU 2024 / 036POLYMER COMPOSITION AND INJECTION MOLDED ARTICLES COMPRISING THE SAMEREFERENCE TO RELATED APPLICATIONSThis application claims priority from US Provisional Application Nr 63 / 700073 filed on 2024-09-27, the whole content of this application being incorporated herein by reference for all purposes.FIELD OF THE DISCLOSURE

[0001] The present disclosure relates to the field of polymer compositions for molded articles, particularly injection molded articles. More particularly, the polymer compositions have low melt viscosity and comprise polyaryletherketone polymers and a molecular sieve, which unexpectedly improves the mechanical properties of the polymer composition.BACKGROUND

[0002] Polyaryletherketone polymers are known as high performance plastics with high thermal resistance, which are used for a number of industrial applications where resistance to extreme conditions is required.

[0003] For instance, Oil & Gas exploration and exploitation requires materials able to resist high temperature and pressure, and capable of maintaining the required performances upon prolonged exposure in the said extreme pressure and temperature conditions to aggressive chemicals present in downhole environment, including notably salt water, hydrocarbons, CO2, H2S, etc.

[0004] Still, in the domain of medical devices, polyaryletherketone polymers have become the materials of choice for non-metal structural body implants, such as bone replacements and prostheses, thanks to their un-matched mechanical properties and ability to sustain body fluids environment.

[0005] Today, the known method of reducing the crystallization rate of polyaryletherketone polymers is to blend it with another polymer such as polyetherimide or polyphenylsulfone. The addition level of the second polymer usually needs to be moreSSPU 2024 / 036 than 10 wt. % in order to cause a significant reduction in the rate of crystallization as measured (for example) by the peak crystallization exotherm temperature upon cooling from the melt, Tc. However, the addition to polyaryletherketone polymers of more than 10 wt.% of another polymer changes other properties of the polyaryletherketone polymers, for example, tensile modulus, chemical resistance, water absorption, etc.

[0006] The Applicant unexpectedly found that the materials provided by this disclosure do not incur any significant changes in any of the key properties of the polyaryletherketone polymers.BRIEF SUMMARY

[0007] The toughness properties of polyaryletherketone (PAEK) polymers in general, and polyetheretherketone (PEEK) polymers in particular, is intimately tied to the level of crystallinity and degree of crystalline perfection in the polymer. The faster the crystallization rates, the more perfected the crystalline spherulitic structure is, and the more detrimental that crystalline structure is to properties such as elongation and impact. As a consequence, when the molecular weight of PEEK is reduced to achieve improved melt processability, there is a double barreled negative effect that resin toughness properties endure, one related to the lower molecular weight (due to loss of entanglements from shorter chains), and the second due to the tendency of lower molecular weight PEEK resin to crystallize faster, more vigorously, forming large spherulites that create weak boundaries between the crystalline and amorphous regions of the polymer and thus create weak points for crack initiation or propagation.

[0008] The compositions of this disclosure counteract the second mechanism that causes loss of toughness described above, thereby allowing the toughness of PEEK to be maintained at incrementally lower molecular weights than would otherwise be possible for unmodified PEEK.

[0009] The applications and benefits of this behavior are very wide ranging because many of PEEK’S applications require a combination of high toughness and easy processability. An important example that comes to mind is extruded copper magnet wire insulation coatings. In this application, the end users and processors need low viscosity PEEK in order to facilitate high production throughput rates and better process economics. On theSSPU 2024 / 036 other hand, these same processors and customers want the highest levels of toughness possible in the PEEK to allow the coating to resist the stringent winding requirements as well as heat aging resistance, etc. that is known for PEEK.

[0010] The invention of the present disclosure is envisioned to allow difficult-to-reconcile requirements as described above to be more feasible and achievable.

[0011] Unexpectedly, the Applicant has surprisingly found that the addition of molecular sieves (e.g. zeolites) in fine powder form as additives at very low levels (e.g. less than 10 wt. %) boosts impact resistance for a given melt viscosity, while at the same time providing the additional benefit of reducing the rate of crystallization, thus improving injection moldability into parts of a very thin cross section and intricate geometry and resulting in lower molded in stresses in injection molded parts.DETAILED DESCRIPTION

[0012] In the present application, any description, even if described in relation to a specific embodiment, is applicable to and interchangeable with other embodiments of the present disclosure, and each embodiment thus defined may be combined with another embodiment, unless otherwise indicated or clearly incompatible.

[0013] Where an element or component is said to be included in and / or selected from a list of recited elements or components, it should be understood that in related embodiments explicitly contemplated here, the element or component can also be any one of the individuals recited elements or components, or can also be selected from a group consisting of any two or more of the explicitly listed elements or components; any element or component recited in a list of elements or components may be omitted from such list.

[0014] Any recitation herein of numerical ranges by endpoints includes all numbers subsumed within the recited ranges as well as the endpoints of the range and equivalents.

[0015] The term “comprising” (or equivalents) includes “consisting essentially of,” and also “consisting of.”

[0016] As used herein, the term “consisting essentially of” or “essentially consisting” indicates that the referred to composition contains less than 5.0 wt.%, typically less than 2.0 wt.% or less than 1 .0 wt.%, of any other ingredient.SSPU 2024 / 036

[0017] The use of the singular “a” or “one” herein includes the plural unless specifically stated otherwise.

[0018] It should be understood that the elements, properties, and / or the characteristics of a polymer, product or article, a process, or a use, described in the present specification, may be combined in all possible ways with the other elements, properties and / or characteristics of the polymer, product or article, process or use, explicitly or implicitly, this being done without departing from the scope of the present description.

[0019] Should the disclosure of any patents, patent applications, and publications that are incorporated herein by reference conflict with the description of the present application to the extent that it may render a term unclear, the present description shall take precedence.

[0020] In a first aspect, the present disclosure relates to a polymer composition comprising a polyaryletherketone (PAEK) polymer having a melt viscosity from 80 Pa*s to 220 Pa*s measured according to ASTM D3835 at 400 °C and 1000 s-1using a capillary rheometer with a tungsten carbide die having a length of 3.175 mm and a diameter of 0.5 mm and a molecular sieve in an amount from 0.3 wt.% to 8.0 wt.%, based on the total weight of the polymer composition. In the remainder of the present specification unless explicitly indicated melt viscosity values are determined according to ASTM D3835 at 400 °C and 1000 s-1using a capillary rheometer with a tungsten carbide die having a length of 3.175 mm and a diameter of 0.5 mm.

[0021] Another aspect of the present disclosure relates to a method of making an article comprising melt filtering the presently disclosed polymer composition and injection molding the melt filtered polymer composition.

[0022] Yet another aspect of the present disclosure relates to injection molded articles, compression molded articles, extruded articles, and articles made by fused filament fabrication additive manufacturing comprising the presently disclosed polymer compositions.

[0023] The Polymer Composition

[0024] The presently disclosed polymer compositions comprise a polyaryletherketone (PAEK) polymer and a molecular sieve. The molecular sieve is present in the polymer composition in an amount from 0.3 wt.% to 8.0 wt.%, based on the total weight of theSSPU 2024 / 036 polymer composition. The molecular sieve is advantageously present in the composition in an amount of at least 0.5 wt.%, even at least 0.8 wt.%. The amount of molecular sieve may be at most 7.5 wt.%, even at most 7.0 wt%. A particularly advantageous amount of molecular sieve in the composition was found to be in the range from 0.8 wt.% to 5.0 wt.%.

[0025] The polymer composition comprises the PAEK polymer in an amount of at least 85.0 wt%, even at least 90.0 wt.%. The composition may comprise the PAEK polymer in an amount of from 92.0 wt.% to 99.7 wt.% or from 96.0 wt.% to 99.0 wt.%, based on the total weight of the polymer composition.

[0026] The composition may comprise one or more than one PAEK polymer. The PAEK polymers in the composition may differ in terms of the nature and ratio of the recurring units (R-PAEK) in the polymer. Alternatively, the PAEK polymers in the composition may have the same nature and ratio of recurring units (R-PAEK) and differ in terms of melt viscosity.

[0027] The composition typically has a melt viscosity that does not significantly differ from the melt viscosity of the PAEK polymer. The melt viscosity of the polymer composition is generally from 80 to 250 Pa*s, measured according to ASTM D3835 at 400°C and 1000 s’1, using a capillary rheometer with a tungsten carbide die having a length of 3.175 mm and a diameter of 0.5 mm, even 100 Pa*s to 220 Pa*s.

[0028] The composition can optionally comprise one or more additives. Examples are colorants (e.g., a dye and / or a pigment), ultraviolet light stabilizers, heat stabilizers, antioxidants, acid scavengers, processing aids, nucleating agents, an internal lubricant and / or an external lubricant, flame retardants, smoke-suppressing agents, anti-static agents, anti-blocking agents, or any combination thereof.

[0029] The Polyaryletherketone (PAEK) Polymer

[0030] The presently disclosed polymer composition comprises a polyaryletherketone (PAEK) polymer. The PAEK polymer is a polymer comprising more than 50 mol% of recurring units (R-PAEK), wherein recurring units (R-PAEK) comprise a Ar — C(O) — Ar' group, wherein Ar and Ar', equal to or different from each other, are aromatic groups.

[0031] In some embodiments, the PAEK polymer comprises at least 60.0 mol.%, at least 70.0 mol.%, at least 80.0 mol.%, at least 90.0 mol.%, at least 95.0 mol.%, or at least 99.0SSPU 2024 / 036 mol.%, at least 99.5 mol%, or at least 99.9 mol% of recurring units (R-PAEK). As used herein, mol.% is relative to the total number of moles of recurring units in the PAEK polymer.

[0032] The recurring units (R-PAEK) are selected from the group consisting of formulae (J'-A) to (J'-O) herein below:SSPU 2024 / 036SSPU 2024 / 036

[0033] The PAEK polymer in the inventive composition has a melt viscosity from 80 Pa*s to 220 Pa*s. The melt viscosity may be from 100 Pa*s to 200 Pa*s, even from 120 Pa*s to 180 Pa*s, or from 140 Pa*s to 160 Pa*s. The PAEK polymer melt viscosity is measured as detailed above.

[0034] The PAEK polymer is conveniently selected from the group of PEEK, PEK, PEKEKK polymers.

[0035] PEEK refers to a PAEK in which recurring unit (R-PAEK) is represented by the following formula:

[0036] PEK refers to a PAEK including recurring unit (R-PAEK) represented by the following formula:(J'-c)

[0037] PEKEKK refers to a PAEK including recurring unit (R-PAEK) represented by the following formula:SSPU 2024 / 036

[0038] The PAEK polymer is preferably polyetheretherketone (PEEK).

[0039] The Molecular Sieve

[0040] The disclosed polymer compositions comprise a molecular sieve. The term molecular sieve is used herein to mean a crystalline inorganic material having a plurality of microscopic interconnecting voids or channels extending there through. Such materials include crystalline aluminosilicates, silicoaluminophosphates, and aluminophosphates in acid form or as a salt with a group IA or group HA element such as sodium, potassium, magnesium or calcium and silica polymorphs.

[0041] Preferred molecular sieves for use in this invention are zeolites. The term “zeolite” is used herein to refer to hydrated aluminosilicates of the alkaline and alkaline-earth metals. Advantageously, the zeolite in the inventive polymer composition is selected from sodium aluminosilicate zeolites. The sodium ions may optionally be exchanged with calcium ions, partially or totally.

[0042] Advantageously the molecular sieves used in the inventive composition are sodium aluminosilicate zeolites with an average pore size of 0.5 nm.

[0043] The molecular sieve is incorporated in the PAEK polymer in particulate form. Preferably the median (D50) particle size is from about 0.5 to about 50 microns, more preferably it is from about 0.5 to about 20 microns, even more preferably from about 0.5 to 10 microns. Most preferably, the median particle size of the molecular sieve is from 0.5 to 5 microns. The particle size may determined using laser diffraction. It is generally calculated as volume average.

[0044] Methods of Making an Article

[0045] One aspect of the present disclosure provides a method of making an article. The method comprises melt filtering the presently disclosed polymer composition and injection molding or extrusion molding or compression molding the melt filtered polymer composition. The melt filtered composition can also be fabricated by additive manufacturing using a fused filament fabrication method.SSPU 2024 / 036

[0046] The method comprises a step of melting the polymer composition. The melting step is performed before the melt filtering step.

[0047] Articles

[0048] One aspect of the present disclosure provides for articles comprising the polymer compositions described herein. The article is an injection molded article, a compression molded article, an extruded article, or an article fabricated by fused filament fabrication additive manufacturing.

[0049] A further object of the present disclosure is an injection molded article having at least one of:- a notched Izod impact of 1 .0 J / m or more as measured according to ASTM D256, and- an instrumented impact total energy of 30.0 J or more as measured according to ASTM D3763.

[0050] Any application that benefits from very high melt flowability for a wider injection molding processing window combined with a higher degree of achievable toughness in the finished part is a potential end use for the present disclosure. Suitable examples include: wire and cable coatings, injection molded electrical connectors, electronic parts, cable ties and wire harnesses, lightweight structural components for aerospace, rail and automotive applications.

[0051] Additionally, the invention can find uses in additively manufactured parts using the fused filament deposition method, where a slower or more controlled rate of crystallization is advantageous. Applications also include thin medical and other tubing. Heat shrinkable tubing can especially benefit from a slowed down rate of crystallization because the tubing needs to stay in the amorphous state as extruded. Also, it is important to note that the utility of this invention is applicable not only to neat PEEK polymers as well as to reinforced, filled and otherwise formulated compounds.

[0052] The present invention will be now described in more detail with reference to the following examples, whose purpose is merely illustrative and not intended to limit the scope of the disclosure.

[0053] Raw Materials

[0054] The raw materials used in the examples were as described below.SSPU 2024 / 036

[0055] PEEK - KetaSpire® KT-880FP. This grade has a melt viscosity range of 0.14 kPa*s as measured according to ASTM method D3835 at 400°C and a shear rate of 1000 s’1, using a capillary rheometer with a tungsten carbide die having a length of 3.175 mm and a diameter of 0.5 mm.

[0056] Jalon® synthetic zeolite powder, grade 5A-75, supplied by Luoyang Jalon Micro- nano Materials Co., Ltd an alkali metal aluminosilicate with an effective pore opening of 0.5 nm and is the calcium-exchanged form of the type A zeolite. This zeolite powder particle size was measured by optical means after dispersion in the PEEK polymer to have an average particle size of about 3 microns.

[0057] Methods of Manufacture

[0058] The formulations of the examples were prepared by first tumble blending powders of the PEEK resin and zeolite powder in the desired in the desired compositional ratios for about 20 minutes, followed by melt compounding using a 26 mm diameter Coperion® ZSK-26 co-rotating partially intermeshing twin screw extruder having an L / D ratio of 48:1 . The compounding extruder used had 12 barrel sections with barrel sections 2 through 11 being heated with set point temperature of 350 °C. The die section was also set to a temperature of 350 °C.

[0059] In the case of the comparative example, the PEEK resin powder was fed as is (i.e. no pre-blending) into barrel section 1 of the extruder using a gravimetric feeder feeding into the extruder feed hopper at the feed rate and other extruder conditions indicated in Table I. In the case of the three examples, the PEEK resin powder and zeolite powder pre-blend was also fed at barrel section 1 using a gravimetric feeder at nominal throughput rates ranging from 20 to 25 Ib / hr. Vacuum venting was applied at barrel section 10 to remove any residual moisture or other volatiles from the compound. A single-hole die was used for all the compounds and the molten polymer strand exiting the die was cooled in a water bath and then cut in a pelletizer to form pellets approximately 3.0 mm in length by 2.7 mm in diameter. Details of the conditions used for the compounding process can be found in Table I.

[0060] Injection molding was used to produce the test specimens for the measurement of mechanical properties and heat deflection temperature. Tensile and flexural specimens were prepared from each composition. The tensile test specimens were 3.2 mm (0.125SSPU 2024 / 036 in) thick type I ASTM tensile bars according to ASTM specification D638, and the flexural specimens were 5 in x 0.5 in x 0.125 in dimensions. The mechanical test specimens were injection molded using the following approximate set point conditions which are in harmony with injection molding guidelines recommended by the PEEK supplier.Feed Throat: 160 °F (71 °C)Barrel section 1 : 680 °F (360 °C) Barrel section 2: 690 °F (365 °C) Barrel section 3: 700 °F (371 °C) Barrel section 4: 700 °F (371 °C) Nozzle: 690 °F (365 °) Mold: 430 °F (221 °C).

[0061] The following ASTM tests were conducted on the compounds produced in pellet form:

[0062] D3418: Differential scanning calorimetry (DSC) to determine glass transition, Tg, melting point, Tm, crystallization temperature, Tc and heat of fusion, which is an indication of the level of crystallinity in the sample. The DSC program used consisted of a first heat up cycle to 400 °C at a heating rate of 20 °C / min, a 1 minute hold at 400 °C, a cool down to 30 °C at a cooling rate of also 20 °C. The crystallization temperature, Tc was determined from the location of the peak of the crystallization exotherm during this cooling cycle. The sample was next heated again to 400 °C, again using a heating rate of 20 °C / min. This second heating cycle was used to determine the glass transition temperature, Tg, the melting point, Tm and the heat of fusion of the sample. The Tg was measured as the midpoint of the transition using the half-height method. The Tm was measured and recorded as the temperature of the melting endotherm peak, and the heat of fusion was computed from the integration of the area under the melting endotherm.

[0063] D3835: A capillary rheometer with a tungsten carbide die having a length of 3.175 mm and a diameter of 0.5 mm was used to determine the melt viscosity of each of the compositions at 400 °C and at various shear rates ranging from 100 to 10000 1 / s as indicated in Table II.

[0064] The following ASTM test methods were employed in evaluating all compositions: D638: Tensile propertiesSSPU 2024 / 036D790: Flexural propertiesD256: Notched Izod impact resistanceD4812: Unnotched Izod impact resistanceD3763: Instrumented impact resistance (also known as Dynatup® impact).

[0065] Examples

[0066] The following Examples were prepared according to the above. Comparative Example 1 (CE1 ) was prepared using only PEEK with no molecular sieve.Table I. Inventive and comparative example compositions and the compounding conditions used in their preparationSSPU 2024 / 036Table II. Example compositions and their measured mechanical propertiesSSPU 2024 / 036

[0067] All thermal, mechanical and rheological test results for the comparative and inventive examples can be found in Table II. The glass transition temperature does not change upon the addition of molecular sieve powder. Similarly, the melting point changes slightly, dropping by about 2.5 °C at the addition level of 4.0 wt. % used in Example 4SSPU 2024 / 036(E4). However, the crystallization temperature on cooling from the melt is reduced substantially, dropping by 23 °C at the 4.0 wt.% addition level, and dropping by measurable amounts even for molecular sieve addition levels as low as 1 .0 to 1 .9 wt. %. The reduced Tc value is a manifestation of a significant reduction in the rate of crystallization of the PEEK polymer. This behavior is surprising as there are no known additives that can retard the crystallization of PEEK at such low addition levels (e.g. 1 .0- 2.0 wt. %).

[0068] With the present invention, it is possible to achieve a slower crystallizing PEEK polymer without having a significant impact on other key PEEK properties like crystallinity level, mechanical properties, etc. The reduced rate of crystallization allows improved fabrication aspects such as easier part filling and packing and reduced residual stresses during melt fabrication process, especially when that fabrication process is injection molding.

[0069] The heat of fusion of the inventive formulations are not significantly reduced relative to the case of pure PEEK, and this confirms that the level of achievable crystallinity in the polymer is not changed, only the rate at which this crystallinity level is reached is being affected by the addition of the molecular sieve powder. However, despite the fact that the crystallinity level as measured by DSC thermal analysis is not changed in the PEEK polymer upon the addition of molecular sieve additives, the level of crystallinity in a fabricated part would be expected to be reduced, as, in most cases, the cooling rate in real fabrication processes is faster than the 20 °C cooling rate utilized in DSC analysis. The melt viscosity at the 1 .0 wt% addition level is almost unchanged from the control and is slightly increased progressively at the two higher load levels of molecular sieve powder.

[0070] The mechanical properties of the compositions of Examples 2 to 4 are surprising as significant improvements are observed in comparison to the unmodified PEEK (CE1 ). Toughness, as measured by ASTM impact resistance properties are significantly improved over the control. Notched and unnotched Izod, as well as Dynatup instrumented impact property measures are all improved relative to the control.

Claims

SSPU 2024 / 036CLAIMSWhat is claimed is:1 . A polymer composition comprising: a polyaryletherketone (PAEK) polymer having a melt viscosity from 80 Pa*s to 220 Pa*s measured according to ASTM D3835 at 400 °C and 1000 s’1shear rate using a capillary rheometer with a tungsten carbide die having a length of 3.175 mm and a diameter of 0.5 mm; and a molecular sieve in an amount from 0.3 wt.% to 8.0 wt.%, based on the total weight of the polymer composition.

2. The polymer composition of Claim 1 , wherein the molecular sieve is selected from the group consisting of crystalline aluminosilicates, silicoaluminophosphates, and aluminophosphates.

3. The polymer composition of Claim 1 or 2, wherein the molecular sieve is a zeolite.

4. The polymer composition of any of Claims 1-3, wherein the PAEK polymer is a polymer comprising more than 50 % moles of recurring units (R-PAEK) selected from the group consisting of units of formulae (J’-A) to (J’-O):SSPU 2024 / 036SSPU 2024 / 0365. The polymer composition of any one of claims 1 to 4 wherein the PAEK polymer is selected from the group of PEAK polymers in which the recurring units (R-PEAK) are selected from the group consisting of those of formula (J’-A), (J’-C) and (J’-O).

6. The polymer composition of any of Claims 1-5, wherein the PAEK polymer has a melt viscosity from 100 Pa*s to 200 Pa*s, or from 120 Pa*s to 180 Pa*s, or from 140 Pa*s to 160 Pa*s measured according to ASTM D3835 at 400 °C and 1000 s-1shear rate shear rate using a capillary rheometer with a tungsten carbide die having a length of 3.175 mm and a diameter of 0.5 mm.

7. The polymer composition of any of Claims 1-6, wherein the PAEK polymer is present in the polymer composition in an amount of at least 85.0 wt.%, based on the total weight of the polymer composition.

8. A method of making an article, the method comprising: melt filtering the polymer composition of any of Claims 1-7; and molding the melt filtered polymer composition.

9. The method of Claim 8, wherein the molding is selected from one or more of injection molding, compression molding, extruding, and fused filament fabrication additive manufacturing.

10. An injection molded article made according to the method of Claims 8 or 9.11 . The injection molded article of Claim 10, wherein the injection molded article has at least one of: a notched Izod impact of 1 .0 J / m or more as measured according to ASTM D256, andSSPU 2024 / 036- an instrumented impact total energy of 30.0 J or more as measured according to ASTM D3763.

12. An injection molded article or a compression molded article comprising the polymer composition of any of Claims 1-7.

13. A wire comprising the polymer composition of any of Claims 1-7.

14. An extruded article comprising the polymer composition of any of Claims 1-7.

15. An article fabricated by fused filament fabrication additive manufacturing, the article comprising the polymer composition of any of Claims 1-7.

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