Stabilized polyetheretherketone (PEEK) compositions

Abstract

The present invention relates to a polyetheretherketone (PEEK) composition (I) containing lanthanum hydroxide. It has been found that lanthanum hydroxide can be used to stabilize the PEEK composition for a long period of time at temperatures between 210°C and 300°C, preferably between 230°C and 270°C, for a period of 500 hours or more, preferably 1000 to 3000 hours or more. [Formula 1] JPEG2025533316000013.jpg3267

Description

[Technical Field]

[0001] The present invention relates to a polymer composition comprising polyetheretherketone (PEEK) and a rare earth compound. The present invention further relates to the use of said rare earth compound as a thermal stabilizer in a polymer composition comprising PEEK. [Background technology]

[0002] Thermoplastic polymers are widely used in engineering. Their adaptability to reshape with temperature has opened up a wide range of manufacturing methods, such as casting, molding, and forging, which typically have much higher throughput than non-thermal processes. However, this temperature sensitivity limits the high-temperature performance of thermoplastics, especially when exposed to high temperatures for extended periods of time.

[0003] Therefore, various heat stabilizing additives are known that mechanically reinforce the compound or chemically inhibit thermal degradation.

[0004] Regarding the latter option, it should be mentioned that the main cause of the deterioration of mechanical properties over time when exposed to high temperatures is the degradation of polymer chains by radicals. To combat this problem, both organic and inorganic radical scavengers are used.

[0005] Rare earth elements such as cerium and lanthanum have been shown to scavenge radicals and thereby thermally stabilize thermoplastics.

[0006] For example, WO 2021 / 074178 A1 discloses the heat stabilizing effect of both cerium oxide hydrate and lanthanum hydroxide on thermoplastic polyesters, which is observed in terms of the tensile strength of thermoplastic polyesters heat-aged over long periods of time.

[0007] Other examples of mixing plastics in general, and thermoplastic polymers in particular, with additives such as stabilizers, fillers, plasticizers and colorants in order to adapt their properties to the desired field of application include:

[0008] The use of cerium dioxide to stabilize organic polymers against degradation by free radicals is disclosed in EP 1832624 A1. These radicals are primarily generated by ultraviolet light, although heat is also mentioned as a possible cause. The use of lanthanum is not disclosed in this patent.

[0009] US Pat. No. 9,969,882 B2 describes the use of rare earth compounds, preferably cerium tetrahydroxide and lanthanum trihydroxide, as inorganic radical scavengers in polyamides for long-term heat stabilization at temperatures of at least 180° C.

[0010] CN106279646A relates to a heat-resistant polybutylene succinate, in particular a heat-resistant polybutylene succinate containing a nucleating agent such as kaolin, mica, titanium dioxide, carbon nanotubes, cyclodextrin or cyclic lanthanum phosphate.

[0011] US 3,621,074 A discloses a process for the polycondensation of diglycol terephthalate, in which lanthanum phosphate can be used as a catalyst.

[0012] Other references that specifically disclose the use of cerium salts as stabilizers include GB 904,972, EP 3006500, WO 2019 / 191574 A1, CN 110183638 A, KR 20170063159 A, CN 104086877 B, CN 108329573 A, WO 2004 / 106311, "Plastics Additives Handbook" (H. Zweifel, R.D. Maier, M. Schiller, 6th Edition, Carl Hanser Verlag, Munich, 2009), CN 102775635 A, CN 101200556 B, and Yang et al. (2015) Ind. Eng. Chem. Res. 54(44):11048-11055.

[0013] Polyetheretherketone (PEEK) is a thermoplastic semi-crystalline polymer with excellent mechanical properties. The structural unit of the PEEK monomer is:

[0014] [ka]

[0015] Although its glass transition temperature is approximately 150°C, PEEK retains many of its mechanical properties even at temperatures between 200°C and 260°C, making it suitable for many high-temperature applications. Its melting point is approximately 340°C.

[0016] Therefore, PEEK is a thermoplastic polymer that is inherently relatively heat resistant, and therefore, a person skilled in the art would not initially think of adding a heat stabilizer to PEEK.

[0017] US 3,925,307 discloses the addition of antioxidants to polyaryletherketones. This document does not mention PEEK. This document mentions, inter alia, lanthanum hydroxide (La(OH)3) and cerium oxide hydroxide (CeO2 x H2O) as antioxidants. At 400°C, i.e., above the melting point of the polymer, heat resistance is observed for only 30 minutes. Therefore, this document is concerned with short-term stabilization of the polymer under process conditions. This document does not mention the long-term stability of PEEK under use conditions (i.e., at high temperatures but below the melting point).

[0018] The properties of two commercially available PEEK materials are disclosed in the "Victrex® Material Properties Guide" (https: / / www.victrex.com / - / media / downloads / literature / en / material-properties-guide_us-4-20.pdf, downloaded on October 13, 2022) and the "KetaSpire® PEEK Design & Processing Guide" (https: / / content.solvay.com / ketaspire-peek-design-and-processing-guide.pdf, downloaded on October 13, 2022).

[0019] Regarding long-term stability under thermal stress, according to these publications, PEEK does not show a significant decrease in tensile strength upon prolonged heat aging, in contrast to what was observed, for example, with the thermoplastic polyesters investigated in WO2021 / 074178.

[0020] Furthermore, according to these publications, no significant decrease in maximum breaking elongation after long-term heat aging was observed at temperatures in the range of 180°C to 220°C.

[0021] These temperatures are lower than the currently recommended maximum continuous use temperature of 240°C.

[0022] However, it has been found that PEEK does indeed show a decrease in maximum elongation at break when heat aged for extended periods at temperatures approaching or exceeding 210°C, especially 240°C.

[0023] Because maximum elongation at break is a measure of a polymer's toughness, it is particularly desirable to maintain this property even under aggressive temperature conditions that normally result in aging. [Prior art documents] [Patent documents]

[0024] [Patent Document 1] WO2021 / 074178A1 [Patent Document 2] EP1832624Al [Patent Document 3] US9,969,882B2 [Patent Document 4] CN106279646A [Patent Document 5] US3621074A [Patent Document 6] GB904,972 [Patent Document 7] EP3006500 [Patent Document 8] WO2019 / 191574A1 [Patent Document 9] CN110183638A [Patent Document 10] KR20170063159A [Patent Document 11] CN104086877B [Patent Document 12] CN108329573A [Patent Document 13] WO2004 / 106311 [Patent Document 14] CN102775635A [Patent Document 15] CN101200556B [Patent Document 16] US3,925,307 [Patent Document 17] WO2021 / 074178 [Non-patent literature]

[0025] [Non-Patent Document 1] "Plastics Additives Handbook" (H. Zweifel, RD Maier, M. Schiller, 6th Edition, Carl Hanser Verlag, Munich, 2009) [Non-patent document 2] Yang et al. (2015) Ind.Eng.Chem.Res.54(44):11048~11055 [Non-patent document 3] "Victrex® Material Properties Guide" (https: / / www.victrex.com / - / media / downloads / literature / en / material-properties-guide_us-4-20.pdf, downloaded on October 13, 2022) [Non-patent document 4] "KetaSpire® PEEK Design & Processing Guide" (https: / / content.solvay.com / ketaspire-peek-design-and-processing-guide.pdf, downloaded October 13, 2022) Summary of the Invention [Problem to be solved by the invention]

[0026] The present invention aims to improve the heat aging resistance, particularly the long-term heat aging resistance, of polyether ether ketone (PEEK). [Means for solving the problem]

[0027] This object is solved by a polyetheretherketone (PEEK) composition according to claim 1. Preferred embodiments are set out in the subclaims.

[0028] Furthermore, the present invention relates to the use of lanthanum hydroxide for the long-term stabilization of PEEK compositions according to claim 4. [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 1 shows the results of long-term heat aging on the tensile strength of PEEK compositions. [Figure 2] FIG. 1 shows the effect of incorporating cerium oxide hydrate and lanthanum hydroxide into PEEK on elongation at break after heat aging at 230° C. for 500 hours. [Figure 3] FIG. 1 shows the effect of incorporating lanthanum hydroxide (standard and fine particle grades) on elongation at break upon heat aging at 230° C. for 500 hours. [Figure 4] FIG. 1 shows the effect of incorporating lanthanum hydroxide (standard and fine particle grades) on elongation at break upon heat aging at 230° C. for 3000 hours. [Figure 5] FIG. 1 shows the effect of incorporating lanthanum hydroxide (standard and fine particle grades) on elongation at break upon heat aging at 270° C. for 3000 hours. [Figure 6] FIG. 1 shows the effect of incorporating different lanthanum hydroxide loadings on elongation at break upon heat aging at 230° C. for 500 hours. [Figure 7] FIG. 1 shows the effect of incorporating different lanthanum hydroxide loadings on elongation at break upon heat aging at 270° C. for 500 hours. [Figure 8] FIG. 1 shows the effect of incorporating different lanthanum hydroxide loadings on elongation at break upon heat aging at 230° C. for 1500 hours. [Figure 9] FIG. 1 shows the effect of incorporating different lanthanum hydroxides on elongation at break upon heat aging at 270° C. for 1500 hours. [Figure 10] Figure 1 compares the effect of incorporating lanthanum hydroxide (fine particle grade) on the elongation at break of PEEK, polybutylene terephthalate (PBT), and polyamide 66 (PA66) when heat-aged at temperatures higher than their respective maximum recommended continuous use temperatures. DETAILED DESCRIPTION OF THE INVENTION

[0030] In a first aspect, the present invention provides a polyetheretherketone (PEEK) composition containing lanthanum hydroxide.

[0031] [ka]

[0032] The present invention further provides in a second aspect the use of lanthanum for the long-term stabilization of a PEEK composition at a temperature of 210°C to 300°C, preferably 230°C to 270°C, for a period of 500 hours or more, preferably 1000 to 3000 hours or more.

[0033] The following disclosure applies equally to the first and second aspects described above.

[0034] By "PEEK composition" it is to be understood a polymer composition which contains at least 50%, preferably at least 70%, of PEEK.

[0035] As is well known to those skilled in the art, polymer compositions may contain significant amounts of additives such as fillers, binders, or reinforcing materials.

[0036] The compositions of the present invention may contain PEEK as the sole polymeric matrix-forming component. In the case of composite materials in particular, the polymeric composition may include one or more matrix-forming polymeric components and reinforcing materials, such as fibers, which may also be polymeric. In a preferred embodiment of the present invention, PEEK is the only polymeric matrix-forming component.

[0037] The composition of the invention is in particular PEEK or consists essentially of PEEK.

[0038] Surprisingly, lanthanum hydroxide (La(OH)3) was found to have a long-term thermal stabilizing effect on PEEK with respect to maximum elongation at break.

[0039] Considering the above literature, it can be considered that the industry is focusing on Ce-based rare earth heat stabilizers rather than La-based ones. The reason is that stable Ce 3+ and Ce 4+ The remarkable redox properties of cerium oxide hydrates, which have the form, and even formally tetravalent (oxidized) cerium(IV) hydrate, more precisely, non-stoichiometric Ce(OH) 4-n The well-known phenomenon of Ce exhibiting the formula: In addition, the f-orbital of Ce is occupied, which may promote electron delocalization when capturing free radicals.

[0040] Since none of these criteria apply to lanthanum, its use as a thermal stabilizer for PEEK has not been straightforward, and experts could not have predicted the effects described herein.

[0041] Even more surprisingly, other known heat stabilizers, such as cerium oxide hydrate in particular, have been found to be essentially ineffective in stabilizing the maximum elongation at break of PEEK upon extended heat aging.

[0042] In the context of the present invention, improved long-term heat aging resistance is understood to mean a smaller rate of loss in mechanical property values ​​due to long-term heat aging at high temperatures compared to the initial values ​​before heat aging.

[0043] Said mechanical properties preferably mean Young's modulus, tensile strength and, in the context of the present invention, in particular elongation at break.

[0044] In the context of the present invention, heat ageing, in particular long-term heat ageing, is understood to be caused by exposing the polymer composition, i.e. the PEEK polymer contained therein, to high temperatures.

[0045] High temperature is understood to be slightly below or above the known maximum use temperature of PEEK, whose currently known maximum continuous use temperature is 240°C, and therefore below its melting point.

[0046] One particular aspect of the invention is to improve the heat aging resistance of PEEK in the temperature range of 210°C to 300°C, preferably up to 230°C to 270°C.

[0047] In one embodiment of the present invention, the addition of lanthanum hydroxide increases the maximum elongation at break after heat aging in the temperature range of 210°C to 300°C, preferably at a maximum of 230°C to 270°C, for 500 hours to 3000 hours or more, preferably 1000 hours to 3000 hours, and more preferably 2000 hours to 3000 hours.

[0048] Surprisingly, the PEEK composition according to the present invention exhibits excellent heat aging resistance, especially for long-term thermal stress. This effect is due to the lanthanum hydroxide used according to the present invention. Heat aging is generally based on a thermo-oxidative degradation mechanism via a radical chain reaction. Free radicals are formed in the polymer under the influence of heat and oxygen. It has been found that the lanthanum hydroxide used according to the present invention can improve the long-term heat aging resistance of PEEK. Such an effect has not been reported before.

[0049] Preferred features of the present invention will be outlined below with reference to embodiments.

[0050] The amount of lanthanum hydroxide may be in the range of 0.05% to 20% by weight. Furthermore, the amount of lanthanum hydroxide may be in the range of 0.05% to 10% by weight. The amount of lanthanum hydroxide is preferably 0.05% to 5.0% by weight, more preferably 0.1% to 5.0% by weight, and most preferably 0.3% to 5% by weight, for example, 0.5% by weight.

[0051] Furthermore, the amount of lanthanum hydroxide may be, for example, 5.0 wt%, 1.0 wt%, 0.7 wt%, 0.3 wt%, or 0.1 wt%. A preferred amount of lanthanum hydroxide may also be in the range of 0.1 wt% to 3.0 wt%, more preferably 0.3 wt% to 3 wt%, and most preferably 0.3 wt% to 0.7 wt%.

[0052] The pH value of lanthanum hydroxide is preferably 7.5 to 11.5, more preferably 8.5 to 11.

[0053] The lanthanum hydroxide preferably has a BET specific surface area of ​​2 m 2 / g~20m 2 / g, more preferably 6m 2 / g~13m 2 / g.

[0054] Lanthanum hydroxide is preferably D 50 is 0.3 μm to 6.0 μm, more preferably 0.5 μm to 5.0 μm, even more preferably 0.5 μm to 3.5 μm, and most preferably 0.5 μm to 1 μm.

[0055] Smaller average particle size, especially D 50 Lanthanum hydroxide particles with an average particle size of 0.5 μm to 1 μm have been found to be more effective than particles with a larger average particle size.

[0056] All Ds in this specification 50The value refers to the particle size at "x" volume % in the cumulative distribution (e.g., D 50 is at least 1 μm means that 50% by volume of the particles have a diameter smaller than 1 μm).

[0057] The lanthanum hydroxide has an LOI of preferably 8.0% to 15.0%, more preferably 10.0% to 15.0%, and most preferably 12.0% to 14.5%.

[0058] Lanthanum hydroxide, in particular, satisfies all of the above parameters, i.e., specific pH value, BET specific surface area, D 50 , fulfilling the LOI. [Example]

[0059] PEEK-based molding compounds are available on the market from several suppliers. In this example, a PEEK-based molding compound with a medium viscosity suitable for injection molding processes was used (Vestakeep 2000 G, unreinforced grade, manufacturer: EVONIK).

[0060] Incorporation of cerium oxide hydrate (for comparison) and lanthanum hydroxide (invention) into PEEK The gravimetric incorporation of cerium oxide hydrate and lanthanum hydroxide was carried out in a separate mixing step on a co-rotating twin-screw extruder Coperion ZSK 26 Mcc from Coperi (Stuttgart).

[0061] The screw diameter (D) was 26 mm and the L / D ratio was 48. Vestakeep 2000 G was supplied in pellet form and did not require conditioning before compounding. A throughput of more than 50 kg / h was required to maintain a constant mass flow rate of 0.5 wt.% of cerium oxide hydrate or lanthanum hydroxide over time.

[0062] material: Cerium oxide hydrate: pH6.8, BET specific surface area 64.7m 2 / g, D50 1.1μm, LOI 5.5% Lanthanum hydroxide: pH 9.6, BET specific surface area 8.2m 2 / g, D 50 3.2μm, LOI 14.2% Lanthanum hydroxide "fine particles": pH 9.8, BET specific surface area 9.7m 2 / g, D 50 0.8μm, LOI 13.6%

[0063] For weight feeding, a Loss-in-Weight-Brabender dosing unit was used to feed the base molding compound Vestakeep 2000 G and cerium oxide hydrate or lanthanum hydroxide.

[0064] Two venting ports are provided on the twin-screw extruder to remove any moisture remaining during the compounding process.

[0065] A strand cutter was used to produce cylindrical pellets with a diameter of approximately 2 mm and lengths of 2–5 mm, which were then used to fabricate test specimens by injection molding.

[0066] The following compounds were used / produced: - Compound A-PEEK Vestakeep 2000 G - Injection molding grade - Compound B-PEEK Vestakeep 2000 G + 0.5% by weight cerium oxide hydrate - Compound C-PEEK Vestakeep 2000 G + 0.5% by weight lanthanum hydroxide - Compound D-PEEK Vestakeep 2000 G + 0.5% by weight lanthanum hydroxide "fine particles" - Compound E-PEEK Vestakeep 2000 G + 0.05% by weight lanthanum hydroxide "fine particles" - Compound F-PEEK Vestakeep 2000 G + 0.1% by weight lanthanum hydroxide "fine particles" - Compound G-PEEK Vestakeep 2000 G + 0.3% by weight lanthanum hydroxide "fine particles" - Compound H-PEEK Vestakeep 2000 G + 0.7% by weight lanthanum hydroxide "fine particles" - Compound I-PEEK Vestakeep 2000 G + 1.0% by weight lanthanum hydroxide "fine particles" - Compound J-PEEK Vestakeep 2000 G + 3.0% by weight lanthanum hydroxide "fine particles" - Compound K-PEEK Vestakeep 2000 G + 5.0% by weight lanthanum hydroxide "fine particles" Compounding conditions – ZSK 26 twin-screw extruder: Throughput = 60 kg / h Speed=900rpm

[0067] [Table 1]

[0068] Incorporation of lanthanum hydroxide into polyesters and polyamides (for comparison) Lanthanum hydroxide ("microparticles") is mixed with a polymer composition different from PEEK, i.e. - Polybutyl ester (PBT) (PBT Ultradur B4520, manufacturer: BASF) and - Polyamide 66 (PA66) (PA66 Zytel E42, manufacturer: DuPont) The fabrication process was similar to that for the incorporation into PEEK, but of course taking into account the possible processing temperatures of these different polymers.

[0069] The following compounds were used / produced: - Compound L-PBT Ultradur B4520 + 0.5% by weight lanthanum hydroxide "fine particles" - Compound M-PA66 Zytel E42 + 0.5% by weight lanthanum hydroxide "fine particles"

[0070] Specimen preparation: PEEK: The tensile test rods were produced by injection molding according to DIN EN ISO 527-1 using an Engel Victory 330 / 80 injection molding machine. The granules of the compositions (compounds A to D) were dried at 150°C for 6 hours before the injection molding process.

[0071] PBT / PA66: The test specimens were prepared in the same manner as the PEEK specimens.

[0072] Heat aging: PEEK: The heat ageing process was carried out in a drying oven from Treibacher Industrie AG at specified temperatures of 230°C, 270°C, and 300°C for 500, 1000, 1500, and 3000 hours. At 230°C and 270°C, a Heraeus drying oven (model: Function line T 5042 EK) was used, and at 300°C, a Memmert oven (model: UF160) was used.

[0073] PBT: The heat aging temperature applied was 170°C, which is higher than the maximum recommended temperature for continuous use.

[0074] PA66: The heat aging temperature applied was 190°C, which is higher than the maximum recommended temperature for continuous use.

[0075] The mechanical properties of the heat-aged specimens were tested on a Zwick Z150 Allround-Linie universal testing machine.

[0076] After heat aging, specimens were conditioned in water at 80°C for 72 hours before mechanical testing.

[0077] Test conditions: Tensile tests were carried out according to DIN EN ISO 527. The speed was 1 mm / min up to the yield point and then 50 mm / min up to break. Young's modulus, tensile strength and elongation at break were measured.

[0078] result: At temperatures below 240°C, the effect of long-term heat aging on the tensile strength of PEEK is not significant: Figure 1 and Table 1 below show the results of long-term heat aging of PEEK compositions with respect to tensile strength. It can be seen that there is no significant effect on tensile strength (MPa) even after a period of 3000 hours at 230°C. This is true for both the unmodified PEEK (Compound A) and the PEEK composition containing lanthanum hydroxide (Compound C).

[0079] [Table 2]

[0080] The effect of long-term heat aging on the elongation at break of PEEK. Figure 2 and Table 2 below show the effect of incorporating cerium oxide hydrate and lanthanum hydroxide into PEEK on the elongation at break (%) after heat aging at 230°C for 500 hours.

[0081] For unmodified PEEK (compound A), the elongation at break decreases significantly after 500 hours of heat aging at 230°C.

[0082] PEEK modified with cerium oxide hydrate (Compound B) also shows a significant decrease.

[0083] However, PEEK modified with lanthanum hydroxide according to the present invention (Compound C) showed almost no reduction in elongation at break.

[0084] It is noted that the addition of both cerium oxide hydrate and lanthanum hydroxide reduces the elongation at break of the starting material, but this reduction is within acceptable limits.

[0085] [Table 3]

[0086] FIG. 3 and Table 3 show the same results as FIG. 2, based on the elongation at break ("relative elongation at break", determined as the quotient of the elongation at break values ​​before (100%) and after heat aging).

[0087] The surprising effect of lanthanum hydroxide (Compound C) compared to unmodified PEEK (Compound A) and PEEK modified with cerium oxide hydrate (Compound B) is now even more apparent.

[0088] As known to those skilled in the art, it is important that a polymer composition maintain essentially stable initial (ie, pre-use) properties during use.

[0089] [Table 4]

[0090] Figures 4 and 5 and Table 4 below show the effect of lanthanum hydroxide particle size on elongation at break, tested at three different temperatures: 230°C, 270°C, and 300°C for up to 3000 hours.

[0091] At each temperature, unmodified PEEK (Compound A) was compared to PEEK modified with lanthanum hydroxide (Compound C) and PEEK modified with lanthanum hydroxide "fine particles" (Compound D).

[0092] [Table 5]

[0093] At each temperature, the superior effect of using "fine particle" lanthanum hydroxide (Compound D) is evident.

[0094] Furthermore, it was found that at very high temperatures (300°C), a decrease in tensile strength of PEEK can be observed between 500 and 1000 hours, and this decrease can also be suppressed by incorporating lanthanum hydroxide into PEEK.

[0095] Figures 6 and 7, and Table 5 below, show the effect of lanthanum hydroxide content on elongation at break, tested at two temperatures, 230°C and 270°C, for 500 hours.

[0096] In particular, unmodified PEEK (Compound A) was compared to PEEK modified with different amounts of lanthanum hydroxide (Compounds D-K) at each temperature.

[0097] [Table 6]

[0098] Some compounds were also tested at 1500 hours, and the results are summarized in Table 6 below and Figures 8 and 9.

[0099] [Table 7]

[0100] The results show the stabilizing effect of 0.05 wt % to 5.0 wt % lanthanum hydroxide (Compounds D to K) compared to unmodified PEEK (Compound A) at both 230 and 270 °C for 500 and up to 1500 h.

[0101] Effect on different polymers: Figure 10 and Table 7 below show comparative results based on elongation at break for the incorporation of lanthanum hydroxide "microparticles" into PEEK (Compound D), PBT (Compound L), and PA66 (Compound M), respectively. For all polymers, the temperatures were slightly higher than the maximum recommended for continuous use.

[0102] A significant stabilizing effect of lanthanum hydroxide on PEEK can be seen compared to PBT (slight stabilization) and PA.

[0103] [Table 8]

[0104] Characterization of lanthanum hydroxide The test methods for characterizing lanthanum hydroxide according to the present invention are described below. All analyses were performed in duplicate.

[0105] pH value determination A 10 wt % slurry of lanthanum hydroxide in deionized water was prepared and stirred for 30 minutes, after which the pH was measured with a pH meter (Model: SevenExcellence, manufactured by Mettler Toledo) at 20°C (±1°C) while stirring.

[0106] Determination of BET specific surface area Before the measurement, 1 g of lanthanum hydroxide was dried at 250°C for 60 min under a nitrogen purge.

[0107] The BET specific surface area was determined with a Tristar 3020 surface and porosity analyzer (Micromeritics) using nitrogen as the analysis gas.

[0108] Particle size distribution by laser diffraction method D 50 Decision D represents the diameter of the powder particle. 50 is known as the median diameter or mean value of a particle size distribution and represents the particle size at 50% of the cumulative distribution (e.g., D 50 (If the diameter is 2.0 μm, it means that 50% of the particles have a diameter smaller than 2.0 μm.)

[0109] Lanthanum hydroxide (0.5 g) was introduced as a powder into the laser particle size analyzer. Prior to measurement, the sample was also treated with ultrasound at 50 W for 60 seconds.

[0110] Determination of loss on ignition Using a chamber furnace (model: N11HR manufactured by Nabertherm), 20 g of lanthanum hydroxide was heated from room temperature to 1000°C, and the loss on ignition (LOI) was determined by holding the temperature at 1000°C for 2 hours.

Claims

1. A polyetheretherketone (PEEK) composition containing lanthanum hydroxide. 【Chemical 1】

2. 2. The PEEK composition according to claim 1, characterized in that the amount of lanthanum hydroxide is 0.05 wt.% to 5.0 wt.%, more preferably 0.1 wt.% to 5.0 wt.%, most preferably 0.3 wt.% to 0.5 wt.%, for example 0.5 wt.%.

3. The lanthanum hydroxide has a D measured by laser diffraction analysis in accordance with the present specification ５０ 2. The PEEK composition according to claim 1, wherein the particle size is 0.5 to 1 μm.

4. Use of lanthanum hydroxide for long-term stabilization of PEEK compositions at temperatures between 210°C and 300°C, preferably between 230°C and 270°C, for periods of 500 hours or more, preferably 1000 to 3000 hours or more.

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