Resin composition and gear

Abstract

Provided is a resin composition containing a polyaryl ketone, wherein the resin composition contains a polysiloxane, the polysiloxane contains a structure represented by formula (1), a peak corresponding to a cyclic siloxane is detected in pyrolysis GC / MS of the resin composition, and the content ratio of the polysiloxane in the resin composition is 0.25-1.25 mass%. (In formula (1), R1 and R2 each independently represent a C1-3 alkyl group.)

Description

Resin composition and gear

[0001] The present disclosure relates to a resin composition and a gear.

[0002] Precision molded products such as gears are widely used in fields such as automobiles and industrial machinery, and include, for example, precision molded products made of metal and precision molded products made of resin. Among these, precision molded products made of resin have properties such as light weight, corrosion resistance, and low noise. Therefore, they are expected to be used in the above fields. For example, Patent Document 1 discloses a composition for resin gears containing two or more polyether ether ketone resins with different melt viscosities, a fluororesin-based solid lubricant, and aramid fibers.

[0003] Japanese Patent Application Laid-Open No. 2021-134225

[0004] However, the present inventors have recognized that when a resin composition containing polytetrafluoroethylene, which is the fluororesin-based solid lubricant of Patent Document 1, is used to produce a precision molded resin product, the product may be deformed during molding. In addition, precision molded products are required to have few defects in appearance.

[0005] An object of the present disclosure is to provide a resin composition that can suppress deformation during molding of precision molded products and can suppress defects in the appearance of precision molded products.

[0006] The present disclosure relates to the following: [1] A resin composition containing a polyaryl ketone, wherein the resin composition contains a polysiloxane, the polysiloxane has a structure represented by the following formula (1), a peak corresponding to a cyclic siloxane is detected in pyrolysis GC / MS of the resin composition, and a content of the polysiloxane in the resin composition is 0.25 to 1.25 mass%. (In formula (1), R １ and R ２each independently represents an alkyl group having 1 to 3 carbon atoms.) [2] The resin composition according to [1], wherein the content of the polysiloxane in the resin composition is 0.30 to 1.00 mass%. [3] The resin composition according to [1] or [2], wherein the polyaryl ketone is polyether ether ketone. [4] The resin composition according to any one of [1] to [3], wherein the melt viscosity of the polyaryl ketone at a temperature of 400°C and a shear rate of 1216 [1 / sec] is 150 to 650 Pa·sec. [5] The resin composition according to any one of [1] to [4], wherein the melt viscosity of the resin composition at a temperature of 400°C and a shear rate of 1216 [1 / sec] is 380 to 510 Pa·sec. [6] The resin composition according to any one of [1] to [5], wherein the number average molecular weight of the polysiloxane is 10,000 to 10,000,000. [7] The resin composition according to any one of [1] to [6], wherein the viscosity of the polysiloxane is 1 to 10,000 Pa·sec. [8] A gear, which is a molded article of the resin composition according to any one of [1] to [7].

[0007] According to the present disclosure, there is provided a resin composition that can suppress deformation during molding of a precision molded product and suppress appearance defects of the precision molded product. Also provided is a gear that is a molded product of the resin composition of the present disclosure.

[0008] The resin composition was subjected to pyrolysis GC / MS analysis, and the deformation amount during molding was evaluated.

[0009] The present disclosure will be described below based on specific embodiments. In this specification, when a numerical range is described with a lower limit and an upper limit separately, the numerical range can be a combination of any of the lower limit and upper limit values.

[0010] As described above, the inventors' investigations have revealed that when precision molded gears are molded using a resin composition containing polytetrafluoroethylene (PTFE) and polyaryl ketone, deformation can occur during molding. This is thought to be due to the high mold temperature during injection molding, causing the molded product to stick to the mold. Precision molded products are more susceptible to such deformation due to the large contact area between the molded product and the mold. Further investigations have revealed that using a resin composition containing a specific polysiloxane can suppress mold sticking, thereby reducing deformation during molding. While the reason for this is unclear, the inventors speculate as follows: By including a polysiloxane having a specific structure in the resin composition, cyclic siloxanes such as hexamethylcyclotrisiloxane are generated on the surface of the molded product during molding, improving the mold releasability and sliding properties of the molded product. As a result, mold sticking can be suppressed, and deformation during molding can be suppressed.

[0011] The resin composition contains a polyaryl ketone. The polyaryl ketone is not particularly limited, and polyether ketone, polyether ether ketone (PEEK), polyether ketone ketone (PEKK), polyether ketone ether ketone ketone (PEKEKK), etc. can be used. Among them, polyether ether ketone is preferable. One type of polyaryl ketone may be used alone, or two or more types may be used.

[0012] The melt viscosity of the polyaryl ketone at a temperature of 400°C and a shear rate of 1216 [1 / sec] is preferably 150 to 650 Pa·sec, more preferably 200 to 650 Pa·sec, even more preferably 350 to 650 Pa·sec, and particularly preferably 450 to 650 Pa·sec. The melt viscosity can be measured by the method described below. By keeping the viscosity within the above range, the strength of the resin composition when it is formed into a precision molded product is further improved. Furthermore, when the melt viscosity is within the above range, the crystallization rate (solidification rate) of the polyaryl ketone slows. As a result, it may be difficult to sufficiently cool the molded product when it is obtained, which may lead to the molded product sticking to the mold. The resin composition of the present disclosure has good mold releasability even in such cases, and can suppress deformation of the molded product during molding.

[0013] The content of the polyaryl ketone in the resin composition is not particularly limited, but is preferably, for example, 80.00 to 99.75 mass %, more preferably 85.00 to 99.50 mass %, and even more preferably 90.00 to 99.00 mass %.

[0014] The resin composition contains a polysiloxane, and the polysiloxane includes a structure represented by the following formula (1). (In formula (1), R １ and R ２ each independently represents an alkyl group having 1 to 3 carbon atoms (preferably 1 to 2, more preferably 1).

[0015] As described above, when the resin composition contains a polysiloxane having a structure represented by the above formula (1), cyclic siloxanes are generated on the surface of the molded article during molding, improving the mold releasability and sliding properties of the molded article. As a result, it is possible to suppress the molded article from sticking to the mold, and to suppress deformation of the molded article during molding. It is assumed that this is due to the heat resistance of the structure represented by formula (1).

[0016] Generally, the structural units of polysiloxane include R ３ SiO １／２ M unit, R ２ SiO ２／２D units represented by RSiO ３／２ T units represented by SiO ４／２ (R is an organic group such as an alkyl group). Here, the structure represented by the above formula (1) is a D unit. When a polysiloxane contains D units, the D units have lower heat resistance than Q units or T units, so the D units undergo thermal decomposition due to the heat generated during molding, and a portion of the polysiloxane becomes a cyclic siloxane that contributes to improving mold releasability and sliding properties. As a result, the mold releasability and sliding properties of the molded article are improved. When Q units or T units are contained as the main structural units of a polysiloxane, a three-dimensional network structure is formed, resulting in a polysiloxane with excellent heat resistance. Therefore, such polysiloxanes are less likely to undergo thermal decomposition due to the heat generated during molding. As a result, cyclic siloxanes are not sufficiently generated, and the mold releasability and sliding properties of the molded article are not improved.

[0017] The presence of a polysiloxane containing the structure represented by formula (1) in a resin composition can be confirmed by pyrolysis GC / MS. As described above, when a polysiloxane contains a D unit, a peak corresponding to a cyclic siloxane is detected during pyrolysis by pyrolysis GC / MS. When this peak is confirmed, it can be said that the resin composition contains a polysiloxane containing the structure represented by formula (1).

[0018] That is, in the resin composition of the present disclosure, a peak corresponding to a cyclic siloxane is detected in the pyrolysis GC / MS of the resin composition. The cyclic siloxane is not particularly limited, and examples thereof include cyclic dimethyl cyclic siloxanes, such as trimers such as hexamethylcyclotrisiloxane, tetramers such as octamethylcyclotetrasiloxane, pentamers such as decamethylcyclopentasiloxane, hexamers such as dodecamethylcyclohexasiloxane, heptamers such as tetradecamethylcycloheptasiloxane, and octamers such as hexadecamethylcyclooctasiloxane. In addition, low molecular weight cyclic siloxanes such as trimers to decamers are preferred.

[0019] Examples of peaks corresponding to cyclic siloxanes include peaks at m / z=222, 296, 370, 444, 518, and 592. These peaks may be of one type or a plurality of types. The peak at m / z=222 corresponds to hexamethylcyclotrisiloxane, the peak at m / z=296 corresponds to octamethylcyclotetrasiloxane, the peak at m / z=370 corresponds to decamethylcyclopentasiloxane, the peak at m / z=444 corresponds to dodecamethylcyclohexasiloxane, the peak at m / z=518 corresponds to tetradecamethylcycloheptasiloxane, and the peak at m / z=592 corresponds to hexadecamethylcyclooctasiloxane.

[0020] The number average molecular weight of the polysiloxane is not particularly limited, but may be, for example, 10,000 to 10,000,000, preferably 100,000 to 10,000,000, more preferably 1,000,000 to 10,000,000, and particularly preferably 2,000,000 to 10,000,000. Within the above range, the heat resistance of the structure represented by formula (1) becomes more favorable, and thermal decomposition is more likely to occur during molding.

[0021] The viscosity of the polysiloxane is not particularly limited, but may be, for example, 1 to 10,000 Pa sec, preferably 10 to 10,000 Pa sec, more preferably 100 to 10,000 Pa sec, even more preferably 1,000 to 10,000 Pa sec, and particularly preferably 2,000 to 10,000 Pa sec. Within this range, the number average molecular weight of the polysiloxane tends to fall within the above range.

[0022] Furthermore, examples of a method for incorporating a polysiloxane having a structure represented by formula (1) into a resin composition include incorporating EverGlide (registered trademark) manufactured by PolymerDynamix or GENIOPLAST (registered trademark) PELLET S manufactured by Wacker Asahi Kasei Silicones into the resin composition. That is, the resin composition preferably contains one or more selected from the group consisting of EverGlide (registered trademark) and GENIOPLAST (registered trademark) PELLET S, and more preferably contains EverGlide (registered trademark). As EverGlide (registered trademark), EverGlide (registered trademark) MB3225 is preferred.

[0023] The polysiloxane may be in a solid form at 23° C. and 1 atmosphere (hereinafter, such a polysiloxane may be simply referred to as a solid polysiloxane). By including such a solid polysiloxane, thermal decomposition of the D units due to the heat during molding can more easily occur.

[0024] The polysiloxane content in the resin composition is 0.25 to 1.25% by mass. It is preferably 0.30 to 1.00% by mass, and more preferably 0.30 to 0.70% by mass. If the polysiloxane content is less than 0.25% by mass, cyclic siloxanes are not sufficiently generated on the surface of the molded article during molding, making it difficult to improve the mold releasability and sliding properties of the molded article. Furthermore, if the polysiloxane content exceeds 1.25% by mass, silver streaks may occur, resulting in poor appearance of the molded article. While the reason why silver streaks may occur when the polysiloxane content exceeds 1.25% by mass is unclear, it is thought that if the polysiloxane content is too high, some of the polysiloxane may undergo thermal decomposition during molding, resulting in the generation of gas. The polysiloxane content in the resin composition can be measured by extracting the polysiloxane from the resin composition.

[0025] The melt viscosity of the resin composition at a temperature of 400°C and a shear rate of 1216 [1 / sec] is preferably 100 to 550 Pa·sec, more preferably 150 to 550 Pa·sec, even more preferably 250 to 550 Pa·sec, particularly preferably 350 to 550 Pa·sec, and especially preferably 380 to 510 Pa·sec. The melt viscosity can be measured by the method described below. By keeping the viscosity within the above range, the strength of the resin composition when it is formed into a precision molded product is further improved. Furthermore, when the melt viscosity is within the above range, the crystallization rate (solidification rate) of the polyaryl ketone contained in the resin composition is slowed. As a result, it may be difficult to perform sufficient cooling when obtaining a molded product, and the molded product may be more likely to stick to the mold. The resin composition of the present disclosure has good mold releasability even in such cases, and can suppress deformation of the molded product during molding. In addition, when the melt viscosity is 380 to 510 Pa·sec, deformation during molding of precision molded products is easily suppressed, and defects in the appearance of precision molded products are easily suppressed.

[0026] The resin composition may contain other additives, such as inorganic fillers, light stabilizers, ultraviolet absorbers, antistatic agents, and pigments.

[0027] The method for producing the resin composition is not particularly limited, but for example, the resin composition can be produced by mixing the above-mentioned polyaryl ketone and the above-mentioned polysiloxane in a container while heating. That is, the method for producing the resin composition preferably includes a step of heating and mixing the polyaryl ketone and the polysiloxane. In addition, the resin composition can be produced by adopting a known method.

[0028] The resin composition of the present disclosure can be suitably used for precision molded products. That is, the resin composition of the present disclosure can be said to be a resin composition for precision molded products, specifically a resin composition for gears. A molded product of the resin composition can be made into a precision molded product. Specifically, a molded product of the resin composition can be made into a gear. By using the resin composition of the present disclosure, a molded product is obtained in which deformation and appearance defects are suppressed. The method for manufacturing a gear is not particularly limited, but the gear can be manufactured by molding the resin composition of the present disclosure using any molding method such as extrusion molding, injection molding, compression molding, or vacuum molding. Among these, injection molding is preferably used.

[0029] The shape of the gear is not particularly limited, but for example, the module m can be 1.0 to 12.0. The number of teeth can be 40 to 65. The face width can be 5 to 15 mm. The pressure angle can be 15 to 25°. The inner diameter φ of the mounting boss can be 10.00 to 20.00 mm. When the resin composition of the present disclosure is used, gears having the above shapes can be easily obtained.

[0030] Furthermore, examples of molded articles from the resin composition of the present disclosure include worm gears, impellers, cams, joints, shafts, bearings, small screws, bolts, nuts, sliding parts, connectors, trolley wire hangers, coil springs, spiral springs, snap buttons, wire for electrical binding, wire mesh, header materials, washers, contact probes, pressure gauges (Bourdon tubes), springs for electronic and electrical devices, switches, relays, lead frames, diaphragms, bellows, fuse clips, cable ties, and bushings.

[0031] The methods for measuring the physical properties of the resin composition will be described below.

[0032] <Method for measuring melt viscosity of polyaryl ketone and resin composition> The melt viscosity of polyaryl ketone and resin composition is measured according to the following procedure: The melt viscosity of polyaryl ketone and resin composition is measured at a temperature of 400°C and a shear rate of 1216 [1 / s] according to JIS K7199 (ISO 11443).

[0033] <Pyrolysis GC / MS of Resin Composition> Pyrolysis GC / MS of a resin composition is measured by the following procedure. 1 mg of the resin composition is weighed out as a measurement sample, and pyrolysis is carried out under the following pyrolysis conditions. GC / MS measurement is then carried out under the following GC / MS measurement conditions. <Pyrolysis Conditions> Apparatus: Frontier Lab EGA / PY-3030D Pyrolysis Conditions: 400°C 10 min Interface: 320°C <GC / MS Measurement Conditions> GC / MS: JEOL GCTOFMS / Agilent GC7890B Injection Port Temperature: 320°C Column: DB-5MS 30m-0.25mmI.D-0.25μm Carrier Gas: He, 1 ml / min, const. Flow Oven: Maintain at 40°C for 2 minutes, then increase temperature to 300°C at 20°C / min (13 minutes) Interface: 300°C Split ratio: split 50 / 1 MSD: EI / Scan, ion source: 230°C m / z: 10-800

[0034] The configurations and combinations thereof in each embodiment are merely examples, and additions, omissions, substitutions, and other modifications of the configurations are possible as appropriate within the scope of the spirit of the present invention. The present disclosure is not limited to the embodiments, but is limited only by the scope of the claims.

[0035] The present disclosure will be specifically described below with reference to examples, but the present disclosure is not limited to the aspects of the following examples.

[0036] Example 1: 100 parts by weight of polyetheretherketone (Polypla-Evonik, trade name: VESTAKEEP® 5000G) and 1.2 parts by weight of EverGlide® MB3225 (PolymerDynamix) were dry-blended in advance and mixed at 380°C in a twin-screw extruder with an L / D ratio of 40 and a length of 40 mm to obtain a resin composition. MB3225 is a masterbatch containing polyetheretherketone as the base resin and 25% by weight of polysiloxane. The resulting resin composition was injection-molded by thermal melting to obtain a gear. The gear had the following physical properties: module m = 1.0, number of teeth 54, face width 10 mm, pressure angle 20°, and mounting boss inner diameter φ 13.25 mm. The molding machine used was a FANUC Roboshot S-2000i-100B. The molding conditions were: resin temperature: 400°C, mold temperature: 200°C, injection speed: 20 mm / sec, dwell pressure: 120 MPa, dwell time: 15 seconds, cooling time: 40 seconds, ejector pin protrusion delay when mold is opened: 30 seconds. The obtained gears were evaluated as follows.

[0037] The results of pyrolysis GC / MS of the resin composition using the above method are shown in Figure 1. As shown in Figure 1, a peak corresponding to cyclic siloxane was confirmed. Furthermore, the melt viscosity of the resin composition was measured using the above method, and was found to be 500 Pa sec.

[0038] <Evaluation of Ejector Load> The ejector load when ejecting a gear from a mold during injection molding was measured on the ejector load screen of the molding machine. The minimum value (%) was read from the waveform during ejection, and its absolute value was used as the ejector load value. A small ejector load indicates excellent releasability and sliding properties of the gear from the mold.

[0039] Evaluation of Deformation During Forming The amount of deformation during forming was evaluated using a Keyence VR-3200 One-Shot 3D Shape Measuring Instrument. The gear was placed with the protruding surface facing up. Using the observation application, the focus was set on the web portion so that the entire length (diameter) of the gear could be captured. Images were taken while connecting with continuous measurement (Figure 2A). In the analysis application, a straight profile line was drawn using the profile tool in the profile measurement window, including the center of the gear (Figure 2B). Next, a reference line was drawn on the web portion using the "Line-Point" measurement mode in the "Measurement Tool" menu. The boss portion in Figure 2C, marked with an "x," was used as a point. The distance between the reference line and the point (i.e., the distance between the reference line and the boss portion) was measured at two points (the "x" in Figure 2C). The average value [mm] of the two points was rounded to one decimal place, and this value was used as the amount of deformation during forming.

[0040] <Evaluation of Gear Appearance> The appearance of the gears was evaluated visually. The evaluation criteria were as follows. Here, silver streaks refer to a phenomenon in which gas or air appears on the surface of a molded product, and the presence or absence of silver streaks in the web portion of the molded product was confirmed. A: No silver streaks were observed visually. B: Silver streaks were observed visually.

[0041] Examples 2 and 3 Resin compositions and gears were obtained in the same manner as in Example 1, except that the amount of EverGlide (registered trademark) added was changed so that the content of polysiloxane in the resin composition was changed to the value shown in Table 1. The evaluation results are shown in Table 1. Here, pyrolysis GC / MS was also performed on the resin compositions of Examples 2 and 3, and peaks corresponding to cyclic siloxanes were confirmed, as in Example 1.

[0042] Comparative Examples 1 to 7 Resin compositions and gears were obtained in the same manner as in Example 1, except that the type of polyether ether ketone and the type of additive were as shown in Table 1 and the content of polysiloxane in the resin composition was changed to the values ​​shown in Table 1. The evaluation results are shown in Table 1. For the gear of Comparative Example 1, the amount of deformation during molding was evaluated in the same manner as in Example 1. The results are shown in Figure 3. Figure 3A shows a photographed image, corresponding to Figure 2A. Figure 3B shows the set straight profile line, corresponding to Figure 2B. Figure 3C shows two-point measurements of the distance between the reference line and a point, corresponding to Figure 2C. As is clear from Figure 3, in Comparative Example 1, gear deformation occurred during molding. In Comparative Examples 2, 3, and 5 to 7, in which the type of polyether ether ketone was the same as in Example 1, gear deformation occurred during molding, as in Comparative Example 1.

[0043] The results of pyrolysis GC / MS performed on the resin compositions of Comparative Examples 5 and 6 are shown in Figure 1. As shown in Figure 1, no peaks corresponding to cyclic siloxanes were observed. Similar results were obtained for Comparative Examples 1, 2, and 7. In Table 1, L4000G indicates VESTAKEEP (registered trademark) L4000G manufactured by Polypla-Evonik, 5000G indicates VESTAKEEP (registered trademark) 5000G manufactured by Polypla-Evonik, E.G. indicates EverGlide (registered trademark) MB3225, PTFE micropowder indicates Dionin PTFE micropowder TF9205 manufactured by 3M, silicone resin powder 1 indicates silicone resin powder KMP-590 manufactured by Shin-Etsu Chemical Co., Ltd., and silicone resin powder 2 indicates silicone resin powder X-52-854 manufactured by Shin-Etsu Chemical Co., Ltd. Regarding the amount of additive added, when the additive was MB3225, MB3225 was added so that the amount of polysiloxane contained in MB3225 added was the value shown in Table 1. For other additives, the amounts listed in Table 1 were added.

[0044] According to the present disclosure, there is provided a resin composition that can suppress deformation during molding of a precision molded product and suppress defects in appearance of the precision molded product. Also, there is provided a gear that is a molded product of the resin composition of the present disclosure.

Claims

1. A resin composition containing a polyaryl ketone, the resin composition containing a polysiloxane, the polysiloxane having a structure represented by the following formula (1), a peak corresponding to a cyclic siloxane is detected in a pyrolysis GC / MS of the resin composition, and the content of the polysiloxane in the resin composition is 0.25 to 1.25 mass%. (In formula (1), R １ and R ２ each independently represents an alkyl group having 1 to 3 carbon atoms.

2. The resin composition according to claim 1, wherein the content of said polysiloxane in said resin composition is 0.30 to 1.00 mass %.

3. The resin composition according to claim 1 or 2, wherein the polyaryl ketone is polyether ether ketone.

4. A resin composition according to any one of claims 1 to 3, wherein the polyaryl ketone has a melt viscosity of 150 to 650 Pa·sec at a temperature of 400°C and a shear rate of 1216 [1 / sec].

5. A resin composition according to any one of claims 1 to 4, wherein the melt viscosity of the resin composition at a temperature of 400°C and a shear rate of 1216 [1 / sec] is 380 to 510 Pa·sec.

6. The resin composition according to any one of claims 1 to 5, wherein the number average molecular weight of the polysiloxane is 10,000 to 10,000,000.

7. The resin composition according to any one of claims 1 to 6, wherein the viscosity of the polysiloxane is 1 to 10,000 Pa·sec.

8. A gear molded from the resin composition according to any one of claims 1 to 7.

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