Aromatic polyether ketone molded article and method for producing same

Abstract

To provide an aromatic polyether ketone molded body that has both high mechanical strength and large elongation.SOLUTION: The aromatic polyether ketone molded body includes a matrix phase and dispersion phases that are dispersed in the matrix phase. The matrix phase comprises an aromatic polyether ketone and has a crystallite size larger than 63Å. The dispersion phases comprise carbon black and / or carbon nanotubes.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an aromatic polyether ketone molded article that can be used for various parts. [Background technology]

[0002] In the field of industrial machinery, there is a demand for replacing metal parts with resin molded bodies from the viewpoint of weight reduction, etc. Patent Document 1 discloses a technique for improving the mechanical strength of resin molded bodies. This technique can improve the mechanical strength of resin molded bodies by increasing the crystallinity of the resin component and restricting the degree of freedom of molecular motion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-150984 Summary of the Invention [Problem to be solved by the invention]

[0004] Parts for which resin molded articles are expected to replace metal parts include sliding members such as gear members. For sliding members, high mechanical strength and high elongation are advantageous for improving durability. However, little is known about technologies that can achieve both high mechanical strength and high elongation in resin molded articles.

[0005] In view of the above circumstances, an object of the present invention is to provide an aromatic polyether ketone molded article having both high mechanical strength and large elongation. [Means for solving the problem]

[0006] In order to achieve the above object, an aromatic polyether ketone molded article according to one embodiment of the present invention includes a matrix phase and a dispersed phase dispersed in the matrix phase. The matrix phase is composed of aromatic polyether ketone and has a crystallite size of greater than 63 Å. The dispersed phase is composed of at least one of carbon black and carbon nanotubes.

[0007] In this aromatic polyether ketone molded article, the matrix phase is composed of aromatic polyether ketone, thereby achieving high mechanical strength. Furthermore, in this aromatic polyether ketone molded article, the matrix phase has a large crystallite size, thereby achieving high elongation. In other words, this aromatic polyether ketone molded article can achieve both high mechanical strength and high elongation.

[0008] The aromatic polyether ketone constituting the matrix phase may have a molecular weight distribution in which the maximum peak molecular weight is in the range of 50,000 or more. The dispersed phase may be made of carbon black, and the area ratio of the region occupied by the dispersed phase having a particle size of 0.1 μm or more may be 0.6% or more. The dispersed phase may be made of carbon nanotubes, and the area ratio of the region occupied by the dispersed phase having a particle size of 0.1 μm or more may be 1.9% or more. The matrix phase may be made of polyether ether ketone. The aromatic polyether ketone molded article may be configured as a sliding member. The aromatic polyether ketone molded article may be configured as a gear member.

[0009] In one embodiment of the method for producing an aromatic polyether ketone molded article according to the present invention, a molded article is produced by injection molding, in which a dispersed phase composed of at least one of carbon black and carbon nanotubes is dispersed in a matrix phase composed of an aromatic polyether ketone having a molecular weight distribution with a maximum peak molecular weight in the range of 50,000 or more. The molded body is annealed at a temperature higher than the intermediate temperature between the melting point and the glass transition point of the matrix phase and lower than the melting point of the matrix phase.

[0010] It is known that aromatic polyether ketones with large molecular weights are less likely to develop large crystallite sizes. In contrast, in the above-described configuration, at least one of carbon black and carbon nanotubes is dispersed in a matrix phase, and annealing is performed at a high temperature close to the melting point of the matrix phase. In the high-temperature environment during annealing, molecular motion becomes active even in aromatic polyether ketones with large molecular weights. In such a matrix phase with active molecular motion, at least one of the carbon black and carbon nanotubes that make up the dispersed phase serves as the nucleus of crystallites, thereby promoting grain growth even in crystallites composed of long molecular chains. As a result, the above-described configuration results in a matrix phase with large crystallite sizes. [Effects of the Invention]

[0011] As described above, the present invention can provide an aromatic polyether ketone molded article that has both high mechanical strength and large elongation. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a flowchart showing a method for manufacturing a resin molded body according to an embodiment of the present invention. [Figure 2] FIG. 10 is a plan view showing an example in which the resin molded body is configured as a gear member. DETAILED DESCRIPTION OF THE INVENTION

[0013] [Explanation of resin molded body] The present invention relates to an aromatic polyether ketone molded article, which is a resin molded article formed primarily from aromatic polyether ketone. More specifically, the resin molded article according to this embodiment includes a matrix phase composed of aromatic polyether ketone and a dispersed phase composed of carbon powder dispersed in the matrix phase. The carbon powder constituting the dispersed phase is composed of at least one of carbon black and carbon nanotubes.

[0014] The aromatic polyether ketone constituting the matrix phase is a resin composed of a benzene ring, an ether, and a ketone. In the resin molded product according to this embodiment, it is preferable to use polyether ether ketone (PEEK), which has excellent heat resistance and mechanical strength, as the aromatic polyether ketone constituting the matrix phase.

[0015] In the resin molded article according to this embodiment, the aromatic polyether ketone constituting the matrix phase preferably has a large molecular weight, specifically, a molecular weight distribution with a maximum peak molecular weight in the range of 50,000 or more, whereby the resin molded article according to this embodiment has high mechanical strength due to mutual binding between long molecular chains.

[0016] Furthermore, in the resin molded product according to this embodiment, the crystallite size of the aromatic polyether ketone in the matrix phase is large, specifically, greater than 63 Å. As a result, in the resin molded product according to this embodiment, the molecular chains constituting each crystallite are less likely to break even when a large tensile stress is applied, and therefore, large elongation can be obtained.

[0017] That is, in the resin molded article according to this embodiment, the matrix phase is composed of long molecular chains, and the crystallite size in the matrix phase is large, so that both high mechanical strength and large elongation can be achieved, which results in high durability when used in applications such as sliding members.

[0018] To measure the molecular weight distribution of the aromatic polyether ketone that constitutes the matrix phase, , Ge permeation chromatography do. The maximum peak molecular weight refers to a molecular weight corresponding to the number of molecules (frequency) that forms a peak value in a molecular weight distribution curve obtained by molecular weight measurement.

[0019] The crystallite size of the matrix phase can be measured using a diffraction pattern obtained by X-ray diffraction (XRD). That is, the crystallite size of the matrix phase can be calculated based on the Scherrer equation by measuring the half-width of the maximum peak corresponding to the aromatic polyether ketone in the diffraction pattern.

[0020] The crystallite size of the matrix phase should be larger than 63 Å, and although no disadvantages due to an excessively large size have been confirmed at this stage, it is believed that there is a limit to the improvement in mechanical strength that can be achieved by increasing the crystallite size of the matrix phase. From this perspective, the upper limit of the crystallite size of the matrix phase is assumed to be, for example, 250 Å.

[0021] 1 is a flowchart showing a method for producing a resin molded product according to this embodiment. First, in step S01, a raw material is prepared. The raw material prepared in step S01 is prepared as a kneaded mixture of, for example, aromatic polyether ketone constituting the matrix phase and carbon powder constituting the dispersed phase.

[0022] In step S01, the aromatic polyether ketone used has a molecular weight distribution in which the maximum peak molecular weight is in the range of 50,000 or more. Also, in step S01, the carbon powder used has a particle size distribution appropriate for achieving the effect described in step S03 below.

[0023] The kneaded material as a raw material is obtained, for example, by kneading aromatic polyether ketone and carbon powder using a single-screw extruder, a twin-screw extruder, etc. In step S01, the kneaded material as a raw material can also be prepared as a commercially available product in which aromatic polyether ketone and carbon powder are kneaded in advance.

[0024] Next, in step S02, the raw material prepared in step S01 is molded into a shape appropriate for the intended use. The raw material can be molded using injection molding. The raw material compact obtained in step S02 has a dispersed phase made of carbon powder dispersed in a matrix phase made of aromatic polyether ketone.

[0025] In step S02, the grain growth of crystallites in the matrix phase having a large molecular weight is difficult to proceed, and therefore, it is difficult to obtain a large crystallite size in the matrix phase in the raw material compact obtained in step S02. For this reason, in this embodiment, step S03 is performed to increase the crystallite size of the matrix phase.

[0026] In step S03, the raw material compact obtained in step S02 is annealed. The holding temperature for the annealing in step S03 is higher than the temperature generally set in an annealing treatment intended to relieve residual stress, specifically, a temperature higher than the midpoint between the melting point and the glass transition point of the matrix phase and lower than the melting point of the matrix phase.

[0027] In raw material compacts, molecular motion becomes active even in the matrix phase with a large molecular weight in such a high-temperature environment close to the melting point. In such a matrix phase with active molecular motion, the carbon powder constituting the dispersed phase serves as the nucleus of the crystallites, facilitating grain growth even for crystallites composed of long molecular chains. Furthermore, the carbon nanotubes constituting the dispersed phase also have the effect of improving the thermal conductivity of the entire raw material compact including the matrix phase. Therefore, in raw material compacts whose dispersed phase is composed of carbon nanotubes, the molecular motion of the matrix phase becomes even more active during annealing, further promoting grain growth of the crystallites.

[0028] That is, in step S03, the dispersion of carbon powder and the annealing treatment at a high temperature close to the melting point of the matrix phase work synergistically to promote grain growth of crystallites in the matrix phase with a large molecular weight, thereby obtaining a resin molded product with a large crystallite size in the matrix phase.

[0029] The effect of promoting particle growth by serving as the nuclei of crystallites in the dispersed phase is believed to be obtained regardless of the size of the dispersed phase, but is more effective when the dispersed phase is made to a certain extent. In this regard, in the resin molded article according to this embodiment, when the dispersed phase is made of carbon black, it is preferable that the area ratio of the region occupied by the dispersed phase having a particle size of 0.1 μm or more is 0.6% or more. Furthermore, when the dispersed phase is made of carbon nanotubes, it is preferable that the area ratio of the region occupied by the dispersed phase having a particle size of 0.1 μm or more is 1.9% or more.

[0030] On the other hand, in the resin molded article according to this embodiment, from the viewpoint of moldability, the area ratio of the region occupied by the dispersed phase having a particle size of 0.1 μm or more is preferably 20% or less, and more preferably 10% or less. The area ratio of the dispersed phase of the resin molded article can be determined from a photograph of the resin molded article taken with a fluorescence microscope.

[0031] The annealing treatment of the raw material compact in step S03 can be performed using a known heating method, such as hot air heating, far-infrared heating, near-infrared heating, etc. The annealing treatment of the raw material compact is typically performed in the atmosphere, but may also be performed in, for example, a low oxygen partial pressure or an inert gas.

[0032] The resin molded article according to this embodiment is particularly suitable for application to parts where stress tends to concentrate locally. Examples of such parts include sliding members such as gear members, seal rings, thrust washers, and bearings. The resin molded article according to this embodiment configured as a sliding member exhibits high durability.

[0033] 2 shows a gear member as an application example of the resin molded article according to this embodiment as a sliding member. In gear members, stress tends to concentrate at the roots of the multiple teeth T arranged continuously along the outer periphery, but by configuring the gear member as the resin molded article according to this embodiment, chipping of the teeth T can be effectively suppressed.

[0034] [Examples and Comparative Examples] Examples and comparative examples of the above embodiment will be described.

[0035] (Examples 1 to 4 and Comparative Examples 1 and 2) In Examples 1 to 4 and Comparative Examples 1 and 2, samples of resin molded bodies were prepared and evaluated. In all of Examples 1 to 4 and Comparative Example 2, carbon black was used as the carbon powder constituting the dispersed phase. Comparative Example 1 differs from the above embodiment in that no dispersed phase was used and no annealing treatment was performed. Comparative Example 2 differs from the above embodiment in that no annealing treatment was performed.

[0036] The same aromatic polyether ketone was used in all of Examples 1 to 4 and Comparative Examples 1 and 2. Specifically, in all of Examples 1 to 4 and Comparative Examples 1 and 2, the polyether ether ketone "Vestakeep (registered trademark) 5000G" manufactured by Polypla-Evonik was used as the aromatic polyether ketone.

[0037] The same carbon black was used in all of Examples 1 to 4 and Comparative Example 2. Specifically, carbon black "#750B" manufactured by Mitsubishi Chemical Corporation was used in all of Examples 1 to 4 and Comparative Example 2. Note that in Comparative Example 1, no carbon black was used, that is, only aromatic polyether ketone was used.

[0038] Table 1 shows the holding temperatures and holding times of the annealing treatment in Examples 1 to 4. Table 1 also shows the area ratio of the region occupied by the dispersed phase having a particle size of 0.1 μm or more in the samples of Examples 1 to 4 and Comparative Examples 1 and 2, and the crystallite size of the matrix phase of the samples.

[0039] The area ratio of the dispersed phase for each sample was determined from photographs of each sample taken with an Olympus BX53M fluorescence microscope. The crystallite size of the matrix phase for each sample was determined from the diffraction pattern of each sample obtained by measurement with a Rigaku Samartlab X-ray diffractometer.

[0040] As shown in Table 1, the crystallite size of the matrix phase in all of Examples 1 to 4 was larger than that in Comparative Example 1. In contrast, the crystallite size of the matrix phase in Comparative Example 2 was equivalent to that in Comparative Example 1. This confirmed that annealing at high temperatures is effective in increasing the crystallite size of the matrix phase.

[0041] [Table 1]

[0042] A tensile test was conducted to evaluate the fracture properties of each sample of Examples 1 to 4 and Comparative Examples 1 and 2. An "AGX" manufactured by Shimadzu Corporation was used for the tensile test. In the tensile test, each sample was formed into an A12 dumbbell shape in accordance with JIS K7139 (2009), and the tensile speed was 10 mm / min, with the other conditions being the same.

[0043] As a result, Table 2 shows the yield strength, yield stroke, and tensile product for Examples 1 to 4 and Comparative Examples 1 and 2 as percentage changes (%) compared to Comparative Example 1. The yield strength and yield stroke were determined from the stress-strain curve obtained in the tensile test, and the tensile product was calculated from the yield strength and yield stroke.

[0044] In all of Examples 1 to 4, the yield stroke was significantly improved, particularly compared to Comparative Example 1, resulting in a tensile product that was 15% or higher. On the other hand, in Comparative Example 2, the yield stroke was smaller than in Examples 1 to 4. This confirmed that large elongation could be obtained by increasing the crystallite size of the matrix phase.

[0045] Next, a gear durability test was conducted on each sample according to Examples 1 to 4 and Comparative Examples 1 and 2 to evaluate the product characteristics as a gear member. In the gear durability test, each sample had a gear shape. In the gear durability test for each sample, a gear member (made of S45C) was used as the mating member, and the sample was rotated while meshing with the mating member.

[0046] In addition, the gear durability tests for each sample were conducted under the same conditions, with a rotational speed of 1,000 rpm and a torque of 10 N·m. Grease was used as a lubricant between each sample and the mating material during rotation. Each sample was judged as "OK" or "NG" based on the presence or absence of chipped teeth after 1.1 million rotations.

[0047] Table 2 shows the results of the gear durability test for Examples 1 to 4 and Comparative Examples 1 and 2. No tooth chipping occurred in any of the samples according to Examples 1 to 4, whereas tooth chipping occurred in all of the samples according to Comparative Examples 1 and 2. This shows that Examples 1 to 4 provide high product characteristics as gear members.

[0048] [Table 2]

[0049] Examples 5 to 7 In Examples 5 to 7, samples of resin molded bodies were prepared and each sample was evaluated. In all of Examples 5 to 7, carbon nanotubes were used as the carbon powder constituting the dispersed phase. In all of Examples 5 to 7, aromatic polyether ketone was used, which was the same as in Examples 1 to 4 and Comparative Examples 1 and 2.

[0050] Furthermore, the same carbon nanotubes were used in all of Examples 5 to 7. Specifically, carbon nanotubes "NC7000" manufactured by Nanocyl Corporation were used in all of Examples 5 to 7.

[0051] Table 3 shows the holding temperatures and holding times of the annealing treatment in Examples 5 to 7. Table 3 also shows the area ratio of the region occupied by the dispersed phase having a particle size of 0.1 μm or more in the samples of Examples 5 to 7 and Comparative Example 1, and the crystallite size of the matrix phase of the samples. The area ratio of the dispersed phase and the crystallite size of the matrix phase in each sample were determined using the same methods as in Examples 1 to 4 and Comparative Examples 1 and 2.

[0052] As shown in Table 3, in all of Examples 5 to 7, the crystallite size of the matrix phase was larger than that of Comparative Example 1. In particular, in Example 6, in which the area ratio of the dispersed phase was large, a significantly larger crystallite size was obtained. This confirmed that the effect of promoting grain growth of crystallites was obtained by having a large amount of carbon nanotubes with high thermal conductivity.

[0053] [Table 3]

[0054] For Examples 5 to 7, in order to evaluate the fracture properties, tensile tests were carried out in the same manner as in Examples 1 to 4 and Comparative Examples 1 and 2. As a result, Table 4 shows the yield strength, yield stroke, and tensile product for Examples 5 to 7 and Comparative Example 1 as percentage changes (%) compared to Comparative Example 1.

[0055] In all of Examples 5 to 7, the yield strength and yield stroke were improved compared to Comparative Example 1, resulting in a tensile product that was 20% or higher. In particular, in Example 6, which had a large area ratio of the dispersed phase, both the yield strength and yield stroke were the largest. This confirmed that a large tensile product could be obtained by increasing the crystallite size of the matrix phase.

[0056] Next, in order to evaluate the product characteristics as gear members for each sample of Examples 5 to 7 and Comparative Example, a gear durability test was conducted in the same manner as for Examples 1 to 4 and Comparative Examples 1 and 2. Table 4 shows the results of the gear durability test for Examples 5 to 7 and Comparative Example 1. No tooth chipping occurred in any of the samples of Examples 5 to 7. This shows that Examples 5 to 7 have excellent product characteristics as gear members.

[0057] [Table 4]

[0058] [Other embodiments] Although the embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to the above-described embodiments and that various modifications can be made.

[0059] For example, the molecular weight of the aromatic polyether ketone constituting the matrix phase is not particularly limited as long as the resin molded article of the present invention has sufficient mechanical strength depending on the application, etc. In other words, the aromatic polyether ketone constituting the matrix phase may have a maximum peak molecular weight in any range in its molecular weight distribution.

[0060] Furthermore, the aromatic polyether ketone constituting the matrix phase of the resin molded article of the present invention may be other than polyether ether ketone (PEEK), and may be, for example, polyether ketone (PEK), polyether ketone ketone (PEKK), polyether ether ketone ketone (PEEKK), polyether ketone ether ketone ketone (PEKEKK), etc. Furthermore, the matrix phase of the resin molded article of the present invention may be configured as a blend of multiple types of aromatic polyether ketones.

Claims

1. a matrix phase composed of polyether ether ketone having a molecular weight distribution with a maximum peak molecular weight in the range of 50,000 or more, and having a crystallite size of 63 Å or larger; a dispersed phase composed of at least one of carbon black and carbon nanotubes and dispersed in the matrix phase; An aromatic polyether ketone molded article comprising:

2. The aromatic polyether ketone molded article according to claim 1, the dispersed phase is composed of carbon black, The area ratio of the region occupied by the dispersed phase having a particle size of 0.1 μm or more is 0.6% or more. Aromatic polyether ketone molding.

3. The aromatic polyether ketone molded article according to claim 1, the dispersed phase is composed of carbon nanotubes, The area ratio of the region occupied by the dispersed phase having a particle size of 0.1 μm or more is 1.9% or more. Aromatic polyether ketone molding.

4. The aromatic polyether ketone molded article according to claim 1, configured as a sliding member Aromatic polyether ketone molding.

5. The aromatic polyether ketone molded article according to claim 4, Configured as a gear member Aromatic polyether ketone molding.

6. A molded article is produced by an injection molding method, in which a dispersed phase composed of at least one of carbon black and carbon nanotubes is dispersed in a matrix phase composed of an aromatic polyether ketone having a molecular weight distribution with a maximum peak molecular weight in the range of 50,000 or more; The molded body is annealed at a temperature higher than the intermediate temperature between the melting point and the glass transition point of the matrix phase and lower than the melting point of the matrix phase. A method for producing an aromatic polyether ketone molded article.

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