Pellet, manufacturing method of pellet, molding and gear

Abstract

To provide a pellet capable of manufacturing a molding including a glass fiber and semi-aromatic polyamide and excellent in durability, a manufacturing method of a pellet, and a molding and a gear using the pellet as a material and excellent in durability.SOLUTION: A pellet includes semi-aromatic polyamide and a glass fiber. The semi-aromatic polyamide includes a structural unit expressed by a formula (1) below. In a cross section at a center in a MD direction of a test piece obtained at a specific pellet molding condition, a variation coefficient of a distance between centers of gravity of glass fibers is 0.570 or less. [Ar1 is a phenylene group or a naphthylene group and p is an integer of 4 to 12].SELECTED DRAWING: Figure 2B

Description

[Technical Field]

[0001] The present disclosure relates to a pellet, a method for producing the pellet, a compact, and a gear. [Background technology]

[0002] Polyamides are widely used as molding materials for various components. For example, Patent Document 1 discloses a polyamide resin composition containing (A) a polyamide resin, (B) glass fibers having a carboxylic acid anhydride-containing unsaturated vinyl monomer compound on at least a portion of the surface thereof, and (C) a copolymer containing the carboxylic acid anhydride-containing unsaturated vinyl monomer and having a glass transition temperature Tg exceeding 60°C. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6209213 Summary of the Invention [Problem to be solved by the invention]

[0004] However, there is still room for improvement in the durability of molded articles containing semi-aromatic polyamides.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide pellets containing glass fiber and semi-aromatic polyamide that can be used to produce molded articles with excellent durability, a method for producing such pellets, and a molded article and gear that are made from such pellets and have excellent durability. [Means for solving the problem]

[0006] As a result of intensive research to solve the above-mentioned problems, the inventors have found that the durability of a molded body obtained by injection molding pellets can be improved by setting the value of the coefficient of variation of the distance between the centers of gravity of glass fibers, which is measured for a cross section of a test piece obtained by injection molding pellets, to a predetermined value, and have completed the present disclosure. That is, the present disclosure has the following aspects.

[0007] [1] A pellet comprising a semi-aromatic polyamide and a glass fiber, The semi-aromatic polyamide has a structural unit represented by the following formula (1): The pellets are molded under the following molding conditions to obtain a test piece, and in a cross section at the center in the MD direction of the test piece, the coefficient of variation of the distance between the centers of gravity of the glass fibers is 0.570 or less. (Molding conditions) [Test piece] Test piece type A specified in ISO 3167:93. [Injection molding conditions] Barrel temperature 330~350℃, mold temperature 120℃, back pressure 7MPa, screw rotation speed 100rpm, injection pressure 70MPa, injection speed 26mm / s, injection time 2 seconds, holding pressure 50MPa, cooling time 20 seconds, filling time 2 seconds [ka] [In formula (1), Ar 1 represents a phenylene group or a naphthylene group, and the plurality of Ar 1 may be the same or different, and p is an integer of 4 to 12.

[0008] [2] The pellet according to [1], wherein the content of the glass fiber is 10% by mass or more and 60% by mass or less relative to 100% by mass of the total content of the semi-aromatic polyamide and the glass fiber.

[0009] [3] In the formula (1), the Ar 1 represents a 1,4-phenylene group, and p is 9 or 10.

[0010] [4] A method for producing the pellets according to any one of [1] to [3], The method includes melt-kneading a semi-aromatic polyamide and glass fibers in an extruder, The extruder comprises a kneading zone, The method for producing pellets, wherein the kneading zone comprises counter-rotating screw elements.

[0011] [5] A molded article obtained by injection molding the pellets according to any one of [1] to [3].

[0012] [6] A gear comprising a semi-aromatic polyamide and glass fiber, The semi-aromatic polyamide has a structural unit represented by formula (1), A gear in which the coefficient of variation of the distance between centers of gravity of the glass fibers is 0.570 or less in a cross section of the gear teeth cut along a perpendicular bisector to a line connecting the tooth base and the tooth tip. [ka] [In formula (1), Ar 1 represents a phenylene group or a naphthylene group, and the plurality of Ar 1 may be the same or different, and p is an integer of 4 to 12. [Effects of the Invention]

[0013] According to the present disclosure, it is possible to provide pellets containing glass fiber and semi-aromatic polyamide that can be used to produce a molded article having excellent durability, a method for producing such pellets, and a molded article and gear having excellent durability that are made from such pellets. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 4 is a partial enlarged view illustrating gear teeth. [Figure 2A]1 is an example of an SEM image used to calculate the coefficient of variation of the distance between the centers of gravity of glass fibers in the examples. [Figure 2B] The SEM image in Figure 2A was binarized using image analysis software and used to calculate the coefficient of variation of the distance between the centers of gravity of the glass fibers. [Figure 3] FIG. 1 is a plan view showing a resin gear manufactured in an example. [Figure 4] FIG. 1 is a schematic diagram showing the outline of the cylinder part and the screw configuration of a twin-screw extruder used in the examples. DETAILED DESCRIPTION OF THE INVENTION

[0015] The pellets, the method for producing the pellets, the compacts, and the gears of the present disclosure will be described below.

[0016] <Pellets> The pellet of the embodiment is a pellet containing a semi-aromatic polyamide and a glass fiber, The semi-aromatic polyamide has a structural unit represented by the following formula (1): The pellets are molded under the following molding conditions to obtain a test piece, and in a cross section at the center in the MD direction of the test piece, the coefficient of variation of the distance between the centers of gravity of the glass fibers is 0.570 or less. (Molding conditions) [Test piece] Test piece type A specified in ISO 3167:93. [Injection molding conditions] Barrel temperature 330~350℃, mold temperature 120℃, back pressure 7MPa, screw rotation speed 100rpm, injection pressure 70MPa, injection speed 26mm / s, injection time 2 seconds, holding pressure 50MPa, cooling time 20 seconds, filling time 2 seconds

[0017] [ka] [In formula (1), Ar 1 represents a phenylene group or a naphthylene group, and the plurality of Ar 1may be the same or different, and p is an integer of 4 to 12.

[0018] In this specification, the term "semi-aromatic polyamide" refers to a polyamide in which the total amount of aliphatic diamines and aliphatic dicarboxylic acids accounts for 30 mol% or more and 70 mol% or less of the total amount of diamine components and dicarboxylic acid components constituting the polyamide, with the remainder being aromatic diamines and aromatic dicarboxylic acids.

[0019] Pellets having the above coefficient of variation of 0.570 or less have improved durability of molded articles obtained by injection molding the pellets, compared to pellets that do not satisfy the above coefficient of variation of 0.570 or less.

[0020] The pellets contain glass fibers, and the coefficient of variation of the distance between the centers of gravity of the glass fibers, measured on a cross section of a test piece molded from the pellets under the molding conditions described above, is 0.570 or less, preferably 0.568 or less, more preferably 0.566 or less, and even more preferably 0.564 or less.

[0021] Pellets having a coefficient of variation of glass fibers in the cross section of the test piece of 0.570 or less have high durability when molded by injection molding the pellets.

[0022] The value of the coefficient of variation may be 0.060 or more, 0.080 or more, 0.100 or more, or 0.150 or more.

[0023] The value of the coefficient of variation may be 0.060 or more and 0.570 or less, 0.080 or more and 0.568 or less, 0.100 or more and 0.566 or less, or 0.150 or more and 0.564 or less.

[0024] The coefficient of variation is an index representing the variation in the distance between the centers of gravity of the glass fibers. The smaller the value of the coefficient of variation, the smaller the variation in the distance between the centers of gravity. The coefficient of variation is expressed as standard deviation / average value. By dividing the standard deviation by the average value, the influence of the magnitude of the distance between the centers of gravity can be eliminated, and the variation can be evaluated with high accuracy.

[0025] The average value of the distance between the centers of gravity of the glass fibers may be 80.0 μm or less, 58.3 μm or more and 78.0 μm or less, or 58.5 μm or more and 76.0 μm or less.

[0026] The standard deviation of the distance between the centers of gravity of the glass fibers may be 34.0 μm or less, 32.0 μm or more and 33.9 μm or less, or 32.5 μm or more and 33.8 μm or less.

[0027] The "distance between centers of gravity" of glass fibers is measured as the distance between the centers of gravity of the areas occupied by the cross sections of scattered glass fibers in a two-dimensional observation image of the cross section at the center of the MD direction of the test piece to be measured.

[0028] The "average value of the distance between centers of gravity" of the glass fibers is calculated by calculating the distance between centers of gravity of all combinations of the cross sections of the multiple glass fibers that appear in the two-dimensional observation image, and then calculating the arithmetic average value of all the distances between centers of gravity obtained.

[0029] The "coefficient of variation of the distance between centers of gravity" of glass fibers is calculated based on the distance between centers of gravity of glass fibers scattered across the cross section at the center of the MD direction of the test piece. That is, the coefficient of variation can be calculated by dividing the standard deviation by the average value obtained by calculating the standard deviation from the distance between centers of gravity and the average value.

[0030] In the test piece, which is an injection-molded article, the glass fibers are oriented in the MD direction. In the cross section of the test piece at the center in the MD direction, the cross section of the glass fibers cut in the direction perpendicular to the axial direction of the glass fibers (hereinafter simply referred to as the "orthogonal direction") is exposed.

[0031] In this embodiment, the dispersion state (distance between centers of gravity) of the glass fibers dispersed within the pellets is confirmed as a substitute for the dispersion state of the glass fibers in the test specimen. The inventors' studies have revealed that test specimens obtained by injection molding pellets under the above molding conditions maintain the dispersion state of the glass fibers in the pellets to a large extent, while allowing the measurement of the distance between centers of gravity for a larger number of glass fibers than in pellets, thereby enabling the dispersion state to be grasped more appropriately. In other words, it has been found that there is a positive correlation between test specimens injection-molded from pellets with poor dispersion (long distance between centers of gravity in the cross section) and test specimens injection-molded from pellets with good dispersion (short distance between centers of gravity in the cross section) that exhibit a similarly poor dispersion state to the pellets, while test specimens injection-molded from pellets with good dispersion (short distance between centers of gravity in the cross section) exhibit a similarly good dispersion state to the pellets.

[0032] In the case of ordinary cylindrical glass fibers, the cross section of a glass fiber cut in the orthogonal direction is observed to be circular, and therefore can be easily distinguished from the cross section of a glass fiber not cut in the orthogonal direction. The cross section of a glass fiber cut at a slight inclination from the orthogonal direction may also be included in the measurement object. In the case of a normal cylindrical glass fiber, the cross section of a glass fiber cut at a slight inclination from the orthogonal direction is observed to be elliptical. In this specification, the cross section of a glass fiber cut in the orthogonal direction is defined as a cross section of a glass fiber in which the ratio of the major axis / minor axis of the circumscribed rectangle that is the smallest area surrounding the cross section of the glass fiber is 1 or more and 2 or less. Alternatively, cross sections that do not fall within the "cross section of a glass fiber in which the ratio of the major axis to the minor axis of the circumscribed rectangle with the smallest area surrounding the cross section of the glass fiber is 1 or more and 2 or less" may be manually excluded from the measurement object before analyzing the distance between the centers of gravity.

[0033] The value of the coefficient of variation of the distance between the centers of gravity of the glass fibers is obtained by the following image acquisition and analysis.

[0034] [Coefficient of variation of distance between centers of gravity of glass fibers] (Image acquisition) The test piece to be measured is cut, the cut piece is immersed in epoxy resin, and polished so that the cut surface to be measured is exposed. Next, an ion sputtering device (for example, Hitachi, Ltd., E-1030) was used to -7 A palladium alloy is vapor-deposited onto the cut surface under a pressure of 10 Pa, and a cross-sectional image of the test piece is obtained using a scanning electron microscope (SEM, Hitachi, Ltd., S-4700 model) at an accelerating voltage of 25 kV and an observation magnification of 600x. In the cross-sectional image of the test piece, glass fibers cut in a direction perpendicular to the axial direction of the glass fibers are used as the object for measuring the distance between the centers of gravity of the glass fibers.

[0035] (analysis) The cross-sectional image was subjected to median processing with a filter size of 5 × 5 using image analysis software (Mitani Corporation, WinROOF, Ver. 3.54), and then binarized into regions of the resin phase and regions of the cross section of the glass fiber (for example, the threshold for binarization was set to 100). The threshold for binarization was set to a value that allows visual inspection of the image and distinguishes between regions occupied by glass fiber and regions occupied by other components. Using the processed two-dimensional observation image, dust and noise that are clearly not glass fiber, regions of glass fiber cut in the middle of the image edge, and regions of glass fiber not cut in a direction perpendicular to the axial direction of the glass fiber were excluded from the analysis. The average and standard deviation of the distance between the centers of gravity of the glass fiber regions, and the coefficient of variation expressed as standard deviation / average value, were then calculated.

[0036] For the analysis, cross-sectional images containing 30 to 500 cross sections of glass fibers cut in orthogonal directions are used. Analysis is performed using 20 to 100 such cross-sectional images, with the total number of glass fiber cross sections being 3,000 to 10,000.

[0037] The average diameter of the circular area equivalent diameter (diameter converted into a perfect circle of the same area) of the region occupied by one glass fiber obtained from the above two-dimensional observation image may be a numerical value exemplified as the fiber diameter (single fiber diameter) of the glass fiber described below, and may be, for example, 5 μm or more and 20 μm or less.

[0038] The coefficient of variation of the distance between the centers of gravity of the glass fibers can be controlled by adjusting the production conditions related to the intensity of melt kneading in the process of kneading the semi-aromatic polyamide and the glass fibers, as will be explained later in the pellet production method.

[0039] <Glass fiber> Examples of the glass fiber include long-fiber type chopped glass fiber, short-fiber type milled glass fiber, etc. The above-mentioned pellets may contain two or more types of glass fiber.

[0040] Examples of glass fibers include E-glass, A-glass, C-glass, D-glass, AR-glass, R-glass, S-glass, and mixtures thereof. Among these, E-glass is preferred because it has excellent strength and is easily available.

[0041] As the glass fiber, weakly alkaline fiber is preferable because it has excellent mechanical strength (tensile strength and Izod impact strength). In particular, glass fiber having a silicon oxide content of 50% by mass or more and 80% by mass or less, based on the total mass of the glass fiber, is preferable, and glass fiber having a silicon oxide content of 65% by mass or more and 77% by mass or less is more preferable.

[0042] The glass fibers may be treated with a coupling agent such as a silane-based coupling agent or a titanium-based coupling agent, if necessary.

[0043] The glass fibers may be coated with a thermoplastic resin such as a urethane resin, an acrylic resin, or an ethylene / vinyl acetate copolymer, or a thermosetting resin such as an epoxy resin. The glass fibers may also be treated with a sizing agent.

[0044] The number average fiber length of the glass fibers in the pellets is preferably 20 μm or more, more preferably 30 μm or more, and even more preferably 40 μm or more. When the number average fiber length of the glass fibers is 20 μm or more, the effect as a reinforcing material in a molded article molded using the pellets is improved more than when the number average fiber length is less than 20 μm.

[0045] The number average fiber length of the glass fibers in the pellets is preferably 1000 μm or less, more preferably 800 μm or less, and even more preferably 500 μm or less. In the case of pellets in which the number average fiber length of the glass fibers is 1000 μm or less, the fluidity of the composition containing the semi-aromatic polyamide and the glass fibers is improved compared to when the number average fiber length exceeds 1000 μm, and even molded articles having a fine structure can be easily molded.

[0046] An example of the numerical range of the number average fiber length of the glass fibers in the pellets is preferably 20 μm or more and 1000 μm or less, more preferably 30 μm or more and 800 μm or less, and even more preferably 40 μm or more and 500 μm or less.

[0047] (Measurement of number average fiber length of glass fibers) Here, the number average fiber length of the glass fibers in the pellets can be measured by the following method. First, 5 g of pellets were heated in an air atmosphere in a muffle furnace (Yamato Scientific Co., Ltd., "FP410") at 600 °C for 4 hours to remove the resin and obtain an ashed residue containing glass fibers. 0.3 g of the ashed residue was added to 50 mL of ethylene glycol to prepare a mixed solution, which was then irradiated with ultrasound for 5 minutes using an ultrasonic cleaner (VELVO-CLEAR, model number: VS-25). This allowed the ashed residue to be uniformly dispersed in the ethylene glycol, yielding a sample solution containing dispersed glass fibers.

[0048] Next, 5 mL of the sample solution was diluted 5 times with ethylene glycol to obtain a sample solution. The resulting sample solution was then imaged one by one using a particle shape image analyzer (Beckman Coulter's Rapid VUE). The imaged glass fibers were observed from the viewing direction, and their longitudinal lengths were recorded as the fiber lengths.

[0049] The measurement is terminated when the number of measured glass fibers reaches 10,000, and the arithmetic mean value of the fiber lengths of 10,000 glass fibers is calculated from the fiber lengths of each glass fiber obtained, which is the number-average fiber length of the glass fibers.

[0050] The average fiber diameter (single fiber diameter) of the glass fibers is preferably 5 μm or more and 20 μm or less. When the average fiber diameter of the glass fibers is 5 μm or more, handling becomes easier and production efficiency can be improved compared to when the average fiber diameter is less than 5 μm. The average fiber diameter of the glass fibers is more preferably 5.5 μm or more, and even more preferably 6 μm or more. Furthermore, when the average fiber diameter of the glass fibers is 20 μm or less, the fluidity of the liquid crystal polyester pellet composition is improved compared to when the average fiber diameter exceeds 20 μm. Furthermore, the effect of the glass fibers as a reinforcing material for the molded article obtained by injection molding the pellets is further improved. The average fiber diameter of the glass fibers is more preferably 17 μm or less, and more preferably 15 μm or less. An example of the numerical range of the average fiber diameter (single fiber diameter) of the glass fibers is preferably 5 μm or more and 20 μm or less, more preferably 5.5 μm or more and 17 μm or less, and even more preferably 6 μm or more and 15 μm or less.

[0051] The diameter of the glass fibers remains substantially unchanged even after melt-kneading.

[0052] Furthermore, unless otherwise specified, the "fiber diameter of glass fiber" refers to the value measured by "Method A" among the methods described in JIS R3420 "7.6 Single Fiber Diameter."

[0053] The number average fiber length and number average fiber diameter of the glass fibers in a molded product made from pellets can be measured in the same manner as above, except that "pellets" is replaced with "molded product."

[0054] <Semi-aromatic polyamide> Semi-aromatic polyamides can be obtained as polymers of aliphatic diamines and aromatic dicarboxylic acids.

[0055] When the pellets contain a semi-aromatic polyamide, the heat resistance of the molded article obtained by injection molding the pellets is increased.

[0056] The aliphatic diamine is preferably an aliphatic diamine having 4 to 12 carbon atoms. Examples of aliphatic diamines having 4 to 12 carbon atoms include 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, and 1,12-dodecanediamine. These may be used alone or in combination of two or more.

[0057] Examples of aromatic dicarboxylic acids include terephthalic acid, phthalic acid, isophthalic acid, naphthalenedicarboxylic acid, etc. These may be used alone or in combination of two or more.

[0058] The semi-aromatic polyamide contained in the pellets is a semi-aromatic polyamide having a structural unit represented by the following general formula (1).

[0059] [ka] [In formula (1), Ar 1 represents a phenylene group or a naphthylene group, and the plurality of Ar 1 may be the same or different from each other. p is an integer of 4 to 12, and multiple p's may be the same or different from each other.

[0060] From the viewpoint of excellent heat resistance and durability of a molded article obtained by injection molding the pellets, it is more preferable that Ar 1 represents a phenylene group or a naphthylene group, and the plurality of Ar 1 may be the same or different, and p may be 9 or 10.

[0061] From the viewpoint of obtaining a molded article obtained by injection molding the pellets with even better heat resistance and durability, it is more preferable that Ar 1 represents a phenylene group or a naphthylene group, and the plurality of Ar 1 may be the same or different, and p may be 10.

[0062] The Ar 1 The phenylene group in Ar may be a 1,4-phenylene group or a 1,3-phenylene group. 1 The naphthylene group includes a 2,6-naphthylene group and a 2,7-naphthylene group.

[0063] Preferably, in the general formula (1), Ar 1 represents a 1,4-phenylene group, and p may be an integer of 4 to 12.

[0064] More preferably, in the general formula (1), Ar 1 represents a 1,4-phenylene group, and p may be 9 or 10.

[0065] Particularly preferably, in the general formula (1), Ar 1 represents a 1,4-phenylene group, and p may be 10.

[0066] In the semi-aromatic polyamide, the content of the structural unit represented by the general formula (1) is preferably 40% or more, more preferably 80% or more, and even more preferably 90% or more, relative to the total number of all structural units in the semi-aromatic polyamide (100%).

[0067] In the semi-aromatic polyamide, the structural unit represented by the general formula (1) is Ar 1 represents a phenylene group or a naphthylene group, and the plurality of Ar 1may be the same or different, and the content of structural units in which p is 9 or 10 is preferably 40% or more, more preferably 80% or more, and even more preferably 90% or more, relative to the total number of all structural units in the semi-aromatic polyamide (100%).

[0068] In the semi-aromatic polyamide, the structural unit represented by the general formula (1) is Ar 1 represents a 1,4-phenylene group, and p is 9 or 10, the content of which is preferably 40% or more, more preferably 80% or more, and even more preferably 90% or more, relative to the total number of all structural units (100%) in the semi-aromatic polyamide.

[0069] In the semi-aromatic polyamide, the structural unit represented by the general formula (1) is Ar 1 represents a 1,4-phenylene group, and p is 10, the content of which is preferably 40% or more, more preferably 80% or more, and even more preferably 90% or more, relative to the total number of all structural units (100%) in the semi-aromatic polyamide.

[0070] The melt mass flow rate (MFR) of the semi-aromatic polyamide, measured in accordance with JIS K 7210 at a test temperature of 330°C and a load of 2160 g, is preferably 150 g / 10 min or less, more preferably 125 g / 10 min or less, and even more preferably 100 g / 10 min or less. In another aspect, the melt mass-flow rate (MFR) of the semi-aromatic polyamide, measured in accordance with JIS K 7210 at a test temperature of 330°C and a load of 2160 g, is preferably 80 g / 10 min or less, more preferably 50 g / 10 min or less, and even more preferably 30 g / 10 min or less.

[0071] The melt mass-flow rate (MFR) of the semi-aromatic polyamide, measured in accordance with JIS K 7210 at a test temperature of 330°C and a load of 2160 g, may be 5 g / 10 min or more, 10 g / 10 min or more, or 15 g / 10 min or more.

[0072] The upper and lower limit values of the melt mass-flow rate (MFR) of the semi-aromatic polyamide exemplified above can be freely combined.

[0073] The melt mass-flow rate (MFR) of the semi-aromatic polyamide measured in accordance with JIS K 7210 at a test temperature of 330°C and a load of 2160 g may be, for example, 5 g / 10 min or more and 150 g / 10 min or less, 10 g / 10 min or more and 125 g / 10 min or less, or 15 g / 10 min or more and 100 g / 10 min or less. In another aspect, the melt mass-flow rate (MFR) of the semi-aromatic polyamide, measured in accordance with JIS K 7210 at a test temperature of 330°C and a load of 2160 g, may be, for example, 5 g / 10 min or more and 80 g / 10 min or less, 10 g / 10 min or more and 50 g / 10 min or less, or 15 g / 10 min or more and 30 g / 10 min or less. Resin compositions containing semi-aromatic polyamides having an MFR within the above range tend to have excellent heat resistance and durability.

[0074] The MFR of the semi-aromatic polyamide can be controlled by appropriately adjusting conditions related to the reaction efficiency of the polymerization reaction, such as the raw material monomer, catalyst, and reaction time.

[0075] <Optional ingredients> The pellets may contain optional components that do not fall under either the semi-aromatic polyamide or the glass fiber.

[0076] Examples of optional components include fillers other than the glass fibers, additives, and resins that do not fall under the category of semi-aromatic polyamides (hereinafter sometimes referred to as "other resins").

[0077] The filler may be a fibrous filler or a granular filler. The filler may be an inorganic filler or an organic filler.

[0078] The content of the optional components relative to the total mass of the pellets (100% by mass) may be 10% by mass or less, 3% by mass or less, or 0% by mass.

[0079] The pellets may further contain fillers other than glass fibers, but preferably do not contain any fibrous fillers other than glass fibers.

[0080] Examples of the additives include stabilizers, release agents, antioxidants, heat stabilizers, ultraviolet absorbers, antistatic agents, surfactants, flame retardants, and colorants.

[0081] Examples of other resins include thermoplastic resins such as polyester, polyphenylene sulfide, polyether ketone, polycarbonate, polyphenylene ether, polyetherimide, and fluororesin; and thermosetting resins such as phenolic resin, epoxy resin, polyimide resin, and cyanate resin.

[0082] (Content) In the pellets, the proportion of the content of the glass fiber relative to the total content of the semi-aromatic polyamide and the glass fiber (100% by mass) is preferably 10% by mass or more, and more preferably 10% by mass or more and 60% by mass or less, The content is more preferably 20% by mass or more and 55% by mass or less, and even more preferably 30% by mass or more and 50% by mass or less. Pellets having a glass fiber content of not more than the above lower limit have excellent durability of molded articles obtained by injection molding the pellets. Pellets having a glass fiber content of not more than the above upper limit have better fluidity during injection molding.

[0083] From the same viewpoint, the content of the glass fibers relative to the total mass of the pellets (100% by mass) is preferably 10% by mass or more, preferably 10% by mass or more and 60% by mass or less, more preferably 20% by mass or more and 55% by mass or less, and even more preferably 30% by mass or more and 50% by mass or less.

[0084] From the viewpoint of durability of the molded body obtained by injection molding the pellets, the content of the semi-aromatic polyamide relative to the total mass of the pellets (100% by mass) is preferably 40% by mass or more, preferably 40% by mass or more and 90% by mass or less, more preferably 45% by mass or more and 80% by mass or less, and even more preferably 50% by mass or more and 70% by mass or less.

[0085] The proportions of the glass fiber and semi-aromatic polyamide contained in the pellets may be, for example, preferably 10% by mass or more and 60% by mass or less of the glass fiber and 40% by mass or more and 90% by mass or less of the semi-aromatic polyamide, relative to 100% by mass of the total mass of the pellets; more preferably 20% by mass or more and 55% by mass or less of the glass fiber and 45% by mass or more and 80% by mass or less of the semi-aromatic polyamide; and even more preferably 30% by mass or more and 50% by mass or less of the glass fiber and 50% by mass or more and 70% by mass or less of the semi-aromatic polyamide.

[0086] The pellets can be obtained by molding a resin composition containing a semi-aromatic polyamide and glass fibers.

[0087] The molding method for molding a molded body using pellets is not particularly limited, but melt molding is preferred, and examples include extrusion molding and injection molding. A molding method can be selected depending on the shape of the molded body, etc., and the molded body can be molded into the desired shape.

[0088] The pellets described above can be used as a material for molded articles for any purpose to which a resin composition can generally be used as a material. Examples of the molded articles of this embodiment include electrical and electronic components such as connectors, sockets, relay parts, coil bobbins, optical pickups, oscillators, printed wiring boards, circuit boards, semiconductor packages, and computer-related parts; semiconductor manufacturing process-related parts such as IC trays and wafer carriers; home electrical appliance parts such as VTRs, televisions, irons, air conditioners, stereos, vacuum cleaners, refrigerators, rice cookers, and lighting fixtures; lighting fixture parts such as lamp reflectors and lamp holders; audio product parts such as compact discs, laser discs (registered trademarks), and speakers; optical cable ferrules, telephone parts, facsimile parts, and communication equipment parts such as modems; separation claws and heater holders. Examples of suitable products include parts for copying machines and printing machines; mechanical parts such as impellers, fan gears, gears, bearings, motor parts and cases; automotive parts such as mechanical parts for automobiles, engine parts, engine room parts, electrical parts, and interior parts; cooking utensils such as microwave cooking pots and heat-resistant tableware; heat insulation and soundproofing materials such as flooring and wall materials, support materials such as beams and pillars, building materials such as roofing materials, or civil engineering and construction materials; parts for aircraft, spacecraft, and space equipment; radiation facility components such as nuclear reactors, marine facility components, cleaning tools, optical equipment parts, valves, pipes, nozzles, filters, membranes, medical equipment parts and materials, sensor parts, sanitary equipment, sporting goods, leisure goods, and cable ties.

[0089] Among these, the molded article obtained by injection molding the pellets is preferably a gear.

[0090] The gear of this embodiment is a gear including a semi-aromatic polyamide and glass fibers, wherein the semi-aromatic polyamide has a structural unit represented by the following formula (1), and the coefficient of variation of the distance between the centers of gravity of the glass fibers is 0.570 or less in a cross section of the gear teeth cut along a perpendicular bisector to a line connecting the tooth base and the tooth tip.

[0091] Figure 1 is a partially enlarged view of a gear tooth, as observed from a field of view along the rotation axis of the gear. Figure 1 is an enlarged view of the side of a gear tooth exposed on the side of a spur gear, a type of gear. The above-mentioned "root" and "tip" are defined as follows:

[0092] First, when the gear G is viewed from above, the intersections P1 and P2 between the root circle C and the gear tooth T are found. When the intersection P3 between the tooth T and the perpendicular bisector L1 of the baseline BL connecting the intersections P1 and P2 is assumed, the intersection P3 is defined as the "tooth tip." Furthermore, when the intersection P4 between the perpendicular bisector PB and the root circle C is assumed, the intersection P4 is defined as the "tooth dedendum."

[0093] Assuming that perpendicular bisector L2 is the line segment between intersections P3 and P4 of perpendicular bisector L1, the gear is cut along an imaginary plane that includes perpendicular bisector L2 and is perpendicular to perpendicular bisector L1. The coefficient of variation of the distance between the centers of gravity is calculated for the obtained cross section. The method for calculating the coefficient of variation of the distance between the centers of gravity is as described above in [Coefficient of variation of the distance between the centers of gravity of glass fiber].

[0094] In the injection-molded gear, the molten resin flows from the base of the gear teeth to the tip of the gear teeth during molding, so the glass fibers are oriented in the gear teeth from the base of the gear teeth to the tip of the gear teeth, just as the glass fibers are oriented in the MD direction in the test specimen.

[0095] Types of gears include spur gears, helical gears, racks, internal gears, worm gears, worm wheel gears, and bevel gears, including hypoid gears.

[0096] The coefficient of variation of the glass fibers in the gear teeth can be determined as follows, by appropriately changing the method so that the "side surface of the gear teeth" can be observed depending on the type of gear.

[0097] If the gear is a helical gear, an internal gear, or a worm wheel gear, the "side of the gear tooth" is exposed in the field of view along the rotation axis of the gear. Therefore, the coefficient of variation of the glass fiber in the gear tooth can be determined in the same manner as shown in Figure 1.

[0098] When the gear is a rack, the "side of the gear tooth" is exposed in a field of view perpendicular to the extension direction of the gear. Therefore, when the gear is a rack, the coefficient of variation of the glass fiber in the gear tooth can be found by replacing the "intersection of the tooth root circle C and the gear tooth T" with the "intersection of the rack tooth root and the gear tooth" for intersection points P1 and P2 in Figure 1, and otherwise following the same method as shown in Figure 1.

[0099] If the gear is a bevel gear, the "side surface of the gear tooth" is exposed in a field of view perpendicular to the rotation axis of the gear. Therefore, if the gear is a bevel gear, in the above explanation using Figure 1, the operation of "cutting the gear at an imaginary plane that includes the perpendicular bisector L2 and is perpendicular to the perpendicular bisector L1" can be read as "cutting the gear at an imaginary plane that includes the perpendicular bisector L2 and follows the ridge of the gear tooth," and the rest can be determined in the same manner as the method shown in Figure 1.

[0100] When the gear is a worm wheel gear, the worm wheel gear is first cut along a cross section including the rotation axis of the gear to expose the cross section of the gear teeth, and then the coefficient of variation of the glass fiber in the gear teeth can be determined in the same manner as when the gear is a rack.

[0101] Such gears have excellent durability. The durability of the gears can be measured by the following durability test.

[0102] (Gear durability test) A metal master gear as a driving gear and a resin gear to be tested are meshed and set in a power absorption gear operation test machine specified in JIS B 1759. The testing machine is operated under the following conditions: load torque on the plastic gear is 5 N·m, rotation speed is 5000 rpm, no lubrication, temperature is 150°C, humidity is 50% RH, and backlash in the normal direction is 0.1 mm, and the total number of rotations until the plastic gear breaks is measured. In this durability test, "destruction" of the plastic gear refers to a state in which power cannot be transmitted from the metal master gear of the drive gear to the plastic gear, for example, due to breakage of the plastic gear teeth. In addition, the test is conducted using a hot air generator to constantly blow hot air onto the drive gear and plastic gear so that the temperature inside the test tank is always maintained at 150°C. The shape and material of the metal master gear and the shape of the resin gear to be tested can be those described in the Examples.

[0103] The above-mentioned gear has good durability under high load conditions, and therefore may be used under conditions in which the torque applied to the gear is 4 N·m or more, or may be used under conditions in which the torque is 4 N·m or more and 30 N·m or less, or may be used under conditions in which the torque is 5 N·m or more and 20 N·m or less.

[0104] According to the pellets described above, the coefficient of variation of the distance between the centers of gravity of the glass fibers obtained from the test piece obtained under the specified molding conditions is 0.570 or less, and therefore the molded article obtained by injection molding the pellets has high durability.

[0105] The small coefficient of variation of the distance between the centers of gravity of the glass fibers leads to a uniform distribution of the glass fibers in the molded body, which is believed to result in the following phenomena: 1) stress concentration due to the difference in elastic modulus between the glass fibers and the non-glass fiber portions is unlikely to occur, and 2) aggregation of the glass fibers is reduced, reducing the probability that a glass fiber will fall off while entangling surrounding glass fibers.These phenomena are believed to contribute to the improvement of the durability of the molded body.

[0106] <Pellet manufacturing method> A method for producing pellets according to an embodiment includes melt-kneading a semi-aromatic polyamide and glass fibers in an extruder, the extruder including a kneading zone, and the kneading zone including a reverse-feeding screw element.

[0107] As the extruder, a known extruder can be used, and depending on the number of screws, examples include a single-screw extruder, a twin-screw extruder, a multi-screw extruder, etc., with a twin-screw extruder being preferred. The twin-screw extruder may be a co-rotating twin-screw extruder or a counter-rotating twin-screw extruder, with a co-rotating twin-screw extruder being preferred.

[0108] In the method for producing pellets, the extruder includes a kneading zone, the kneading zone including a counter-feeding screw element.

[0109] In the kneading zone, the raw materials in the extruder can be kneaded depending on the shape and arrangement of the screw elements, etc. The screw elements that can make up the kneading zone are roughly classified into forward screw elements (R) that transport the kneaded material in the same direction as the transport direction of the kneaded material from the raw material inlet to the outlet, reverse screw elements (L) that transport the kneaded material in the opposite direction to the transport direction, and neutral screw elements (N) that transport the kneaded material in neither direction. When the kneading zone includes the reverse screw element (L), the kneading strength between the semi-aromatic polyamide and the glass fiber is improved, and pellets having a coefficient of variation of the distance between the centers of gravity of the glass fiber of 0.570 or less in the cross section of a test piece molded under the above molding conditions can be easily produced.

[0110] The kneading zone preferably further comprises a progressive screw element (R). In order to further increase the kneading intensity, the kneading zone preferably has screw elements in the following order from the raw material inlet side: a forward screw element (R) and a reverse screw element (L).

[0111] The kneading zone may further include a neutral screw element (N). When the kneading zone includes a neutral screw element (N), it is preferable that the kneading zone has these screw elements in the following order from the raw material inlet side: a forward screw element (R), a neutral screw element (N), and a reverse screw element (L).

[0112] The number of screw elements constituting the kneading zone may be 1 or more and 10 or less, or may be 2 or more and 5 or less.

[0113] When the screw configuration shown in the examples (FIG. 4) has a kneading zone (first kneading zone N1 in FIG. 4) in which only the semi-aromatic polyamide is melt-kneaded and the semi-aromatic polyamide and the glass fiber are not melt-kneaded, the kneading zone does not need to include a reverse screw element.

[0114] The screw elements constituting the kneading zone may be of various shapes, and examples thereof include kneading disks, which are capable of distributing the glass fibers well. Examples of kneading disks include those having a shape in which multiple disks with flight tips parallel to the axial direction of the screw are stacked on top of each other. The disk shape preferably has one to three flight tip vertices, more preferably two or three, and even more preferably two.

[0115] The number of discs per screw element may be 3 to 5, and 3 is preferred.

[0116] The temperature of the kneading zone (hereinafter also referred to as the barrel temperature) is preferably 5 to 40°C higher than the melting point of the semi-aromatic polyamide, and may be, for example, 300°C or higher and 360°C or lower, or 320°C or higher and 340°C or lower. By setting the temperature of the kneading zone within the above range, the kneading strength is improved, and it is possible to easily produce pellets in which the coefficient of variation of the distance between the centers of gravity of the glass fibers is 0.570 or less in the cross section of a test piece molded under the above molding conditions.

[0117] The screw length L / screw diameter D of the extruder may be 10 or more and 300 or less, or 20 or more and 200 or less.

[0118] The screw rotation speed of the extruder may be 50 rpm or more and 300,000 rpm or less, or may be 100 rpm or more and 12,000 rpm or less.

[0119] The discharge rate of the kneaded material in the extruder may be 1 kg / min or more and 600 kg / min or less, or may be 5 kg / min or more and 400 kg / min or less.

[0120] The extruder preferably has a vacuum vent. The kneaded product kneaded in the extruder is extruded, for example, through a die in the form of a strand, and then cut into a desired length and molded, which can be provided as a molding material such as pellets.

[0121] The molding material can be further subjected to melt molding such as injection molding as exemplified above to be molded into the shape of a desired molded article such as a gear, which can be provided as a molded article.

[0122] The pellet manufacturing method is as follows: A molding material comprising a semi-aromatic polyamide and glass fibers, The semi-aromatic polyamide has a structural unit represented by the general formula (1) [in formula (1), Ar 1 represents a phenylene group or a naphthylene group, and the plurality of Ar 1 may be the same or different, and p is an integer of 4 to 12. The pellets may be produced under the following molding conditions, and in a cross section of the center of MD of a test piece obtained by molding the pellets under the following conditions, the coefficient of variation of the distance between the centers of gravity of the glass fibers may be 0.570 or less. (Molding conditions) [Test piece] Test piece type A specified in ISO 3167:93. [Injection molding conditions] Barrel temperature 330~350℃, mold temperature 120℃, back pressure 7MPa, screw speed 100rpm, injection pressure 70MP, injection speed 26mm / s, injection time 2 seconds, holding pressure 50MPa, cooling time 20 seconds, filling time 2 seconds.

[0123] According to the above-described pellet manufacturing method, the above-described pellets can be manufactured. [Example]

[0124] Next, the present disclosure will be described in more detail by showing examples, but the present disclosure is not limited to the following examples.

[0125] ≪Raw materials≫ Resin: Semi-aromatic polyamide PA10T(Ar 1 represents a 1,4-phenylene group, and p is 10. PA9T (Kuraray, Genestar N1000A, Ar 1 represents a 1,4-phenylene group, and p is 9. Filler: Glass fiber (Nippon Electric Glass Co., Ltd., T-262H, average fiber diameter 10.5 μm, average fiber length 3 mm, coated with a film-forming agent containing an acid copolymer)

[0126] <Pellet production> [Examples 1 and 2, Comparative Examples 1 and 2] The above base resin was added to a twin-screw extruder (manufactured by Ikegai Corporation, PCM-30HS, screw diameter D: 30 mm, screw length L: 1230 mm, L / D: 41) in the blending amounts (mass%) shown in Table 1 through the main feeder, and glass fiber was added through the side feeder. The mixture was melt-kneaded under conditions of a barrel temperature of 320 to 340°C, a screw rotation speed of 250 rpm, and a discharge rate of 10 kg / min. The mixture was then discharged in the form of strands through a circular nozzle (discharge port) with a diameter of 4 mm, and pelletized using a pelletizer (manufactured by Isuzu Chemical Engineering Co., Ltd.) with a roller speed of 22 m / min and a rotary blade adjusted to 270 rpm, thereby obtaining pellets for each of the Examples and Comparative Examples.

[0127] FIG. 4 is a schematic diagram of the cylinder portion of the twin-screw extruder used. The twin-screw extruder has a cylinder block of C0 to C10 extending from the main feeder MF toward the die outlet, with a side feeder SF at position C6. The screw configuration inside the cylinder has two kneading zones N1 and N2 at positions C4 and C9, and the rest of the section is made up of flight screws.

[0128] The screw pattern (A) in Figure 4 is the screw pattern used in Examples 1 and 2. The second kneading zone N2 at position C9 is composed of, in order from the main feeder side, a forward screw element (3R), a neutral screw element (3N), and a reverse screw element (3L). The barrel temperature in the kneading zone is 340°C. Screw pattern (B) in Figure 4 is the screw pattern adopted in Comparative Examples 1 and 2. The second kneading zone N2' at position C9 is composed of three progressive screw elements (3R), (3R), and (3R) in this order from the main feeder side. The barrel temperature in the kneading section is 340°C, the same as screw pattern (A).

[0129] The "3" included in the symbols (3R, 3N, 3L) representing each screw element indicates that one screw element is made up of three kneading discs.

[0130] In screw pattern (A), the first kneading zone N1 at position C4 is configured in the order of 3R, 3N, 3N, 3N, 3L, 3L from the main feeder side. In screw pattern (B), the first kneading zone N1' at position C4 is configured the same as the first kneading zone N1.

[0131] <Measurement> [Number average fiber length of glass fibers in the test specimen] The number average fiber length of the glass fibers in the test piece was measured as described above in (Measurement of the number average fiber length of glass fibers).

[0132] [Fiber diameter of glass fiber in test specimen] The fiber diameter of the glass fibers in the test piece was measured by "Method A" among the methods described in JIS R3420 "7.6 Single Fiber Diameter," and was calculated as the average value for all the measured glass fibers.

[0133] [Coefficient of variation of distance between centers of gravity of glass fibers] (Image acquisition) The average value of the distance between the centers of gravity of the glass fibers in each example and its standard deviation were determined by image analysis of the SEM images. Specifically, the pellets obtained in the examples and comparative examples were used as molding materials to injection mold test pieces Type A specified in ISO 3167: 93. The injection molding conditions were as follows: barrel temperature 330 to 350°C, mold temperature 120°C, back pressure 7 MPa, screw rotation speed 100 rpm, injection pressure 70 MPa, injection speed 26 mm / s, injection time 2 seconds, dwell pressure 50 MPa, cooling time 20 seconds, and filling time 2 seconds.

[0134] The center of the obtained specimen was cut perpendicular to the resin flow direction (TD) and immersed in epoxy resin. The cut surface was then pressed against waterproof abrasive paper (Refine Tech Co., Ltd.) rotating at 200 rpm using a polishing machine (Kasai Shoko Co., Ltd., Refine Polisher). The cut surface was polished for 3 minutes with each of the waterproof abrasive papers, changing from #320 to #600, #1200, #1500, and #2000, while running water over the polished surface. After polishing, the polished surface was pressed against a suede cloth (Refine Tech Co., Ltd.) rotating at 200 rpm and allowed to run for 30 minutes over a diluted solution of 0.3 μm alumina oxide powder (Refine Tech Co., Ltd.) diluted with water to remove cutting particles and other debris. The polished surface was then pressed against a suede cloth (Refine Tech Co., Ltd.) rotating at 200 rpm and allowed to run water over the polished surface for 1 hour to remove the alumina.

[0135] Next, an ion sputtering device (Hitachi, Ltd., E-1030) was used to -7 A palladium alloy was vapor-deposited on the cut surface under a pressure of 0.05 mm, and the specimen was observed using a scanning electron microscope (SEM, Hitachi, S-4700 model) at an accelerating voltage of 25 kV and a magnification of 600 times to obtain a cross-sectional image of the specimen.

[0136] Since glass fibers are generally oriented in the resin flow direction, cross sections perpendicular to the short axis of the glass fibers, i.e., the axial direction of the glass fibers, are observed on the cut surface, as shown in Figures 2A and 2B below. However, there were also a few glass fibers oriented perpendicular to the resin flow direction, and there were areas where cross sections perpendicular to the long axis of the glass fibers, i.e., the axial direction of the glass fibers, were observed. Therefore, images of the cross sections of the glass fibers were acquired by avoiding the areas of glass fibers oriented perpendicularly. Furthermore, because voids were sometimes present in the cross sections, images were acquired by avoiding the void areas. In other words, cross sections that did not fall within the "glass fiber cross section with a ratio of the long axis to the short axis of the circumscribed rectangle with the smallest area surrounding the cross section of the glass fiber, between 1 and 2," were manually excluded before analyzing the distance between the centers of gravity.

[0137] (analysis) The cross-sectional images obtained above were subjected to median processing with a filter size of 5 × 5 using image analysis software (Mitani Corporation, WinROOF, Ver. 3.54), and then binarized into regions of the resin phase and regions of the cross section of the glass fiber (the threshold for binarization was set to 100). The threshold for binarization was set to a value that allowed visual inspection of the image and distinguishing between regions occupied by glass fiber and regions occupied by other components. Using the processed 2D observation images, dust and noise that were clearly not glass fiber and regions of glass fiber cut off in the middle of the image edge were excluded from the analysis. The average value and standard deviation of the distance between the centers of gravity of the glass fiber regions were then calculated, and the coefficient of variation, expressed as "standard deviation / average distance between the centers of gravity," was then calculated from these values. For the analysis, 20 cross-sectional images containing 30 or more glass fibers (total number of glass fibers: 1,000) were used. Figures 2A and 2B show an example of an SEM image (Figure 2A) used to calculate the coefficient of variation of the distance between the centers of gravity of glass fibers, and a processed image (Figure 2B) that was used to calculate the coefficient of variation of the distance between the centers of gravity of glass fibers after the SEM image was binarized using image analysis software.

[0138] [Gear manufacturing and durability testing] The pellets from Examples 1 and 2 and Comparative Examples 1 and 2 were used as molding materials and injection molded under the following injection conditions: barrel temperature 320-340°C, mold temperature 120°C, back pressure 6 MPa, screw rotation speed 100 rpm, injection pressure 100 MPa, injection speed 30 mm / s, injection time 6 seconds, dwell pressure 90 MPa, and cooling time 25 seconds. The gear shape of the Examples and Comparative Examples was a spur gear with a module of 1, number of teeth 48, pressure angle 20°, reference diameter 48 mm, tip diameter 50 mm, root diameter 45.5 mm, face width 8 mm, transition coefficient 0, and spanning tooth thickness 16.909 mm (spanning tooth number 6). The shape of the manufactured resin gear is shown in Figure 3.

[0139] A durability test was carried out on each of the gears obtained in the examples and comparative examples. A metal master gear [material: S45C carburized, quenched, and tempered (surface hardening treatment); gear shape: spur gear; module 1; number of teeth: 67; pressure angle: 20°; reference circle diameter: 67 mm; tip circle diameter: 69 mm; root circle diameter: 64.5 mm; face width: 15 mm; transition coefficient: 0; spanning tooth thickness: 23.079 (number of spanning teeth: 8)] was installed as a drive gear in a power absorption gear operation test machine specified in JIS B 1759, and meshed with the resin gear obtained in the examples or comparative examples.

[0140] The testing machine was operated under the following conditions: load torque of 5 N·m on the plastic gear, rotational speed of 5000 rpm, no lubrication, temperature of 150°C, humidity of 50% RH, and backlash in the normal direction of 0.1 mm, and the total number of rotations until the plastic gear broke was measured.

[0141] In this durability test, "destruction" of the plastic gear refers to a state in which power cannot be transmitted from the metal master gear of the drive gear to the plastic gear, for example, due to breakage of the plastic gear teeth. In addition, the test was conducted using a hot air generator to constantly blow hot air onto the drive gear and plastic gear so that the temperature inside the test tank was always maintained at 150°C.

[0142] The results of the above measurements are shown in Table 1.

[0143] [Table 1]

[0144] Furthermore, for the gear molded in Example 1, the gear teeth were cut along a perpendicular bisector to the line connecting the tooth base and tooth tip, and the coefficient of variation of the distance between the centers of gravity was determined for the glass fibers exposed in the cross section. As a result, it was confirmed that the cross section of the gear tooth tip also had the same dispersion state of glass fibers as the results confirmed for the test specimen. Average distance between centers of gravity of glass fibers: 60.1 μm Standard deviation: 33.5μm Coefficient of variation: 0.557

[0145] According to the results of the durability test, in Examples 1 and 2, in which the coefficient of variation of the distance between the centers of gravity of the glass fibers was 0.570 or less, the durability of the plastic gears was significantly improved compared to Comparative Examples 1 and 2, in which the coefficient of variation did not satisfy the requirement of 0.570 or less.

[0146] The durability test was conducted under high load conditions of a torque of 5 N m and at a high temperature of 150°C, demonstrating that the pellets of Examples 1 and 2 are useful pellets that can be used to produce gears with excellent high-temperature durability under high load conditions.

[0147] The configurations and combinations thereof in each embodiment are merely examples, and additions, omissions, substitutions, and other modifications of the configurations are possible without departing from the spirit of the present disclosure. Furthermore, the present disclosure is not limited to the respective embodiments, but is limited only by the claims. [Explanation of symbols]

[0148] MF: Main feeder SF...Side feeder N1: First kneading zone N2: Second kneading zone L...Reverse feed screw element N...Neutral screw element R...Progressive screw element

Claims

1. A pellet comprising a semi-aromatic polyamide and glass fibers, The semi-aromatic polyamide has a structural unit represented by the following formula (1): The pellets are molded under the following molding conditions to obtain a test piece, and in a cross section at the center in the MD direction of the test piece, the coefficient of variation of the distance between the centers of gravity of the glass fibers is 0.570 or less. (Molding conditions) [Test piece] Test piece type A specified in ISO 3167:

93. [Injection molding conditions] Barrel temperature: 330-350°C, mold temperature: 120°C, back pressure: 7MPa, screw rotation speed: 100rpm, injection pressure: 70MPa, injection speed: 26mm / s, injection time: 2 seconds, holding pressure: 50MPa, cooling time: 20 seconds, filling time: 2 seconds 【Chemical 1】 [In formula (1), Ar １ represents a phenylene group or a naphthylene group, and the plurality of Ar groups contained in the semi-aromatic polyamide １ may be the same or different, and p is an integer of 4 to 12.

2. The pellet according to claim 1, wherein the content of the glass fiber is 10% by mass or more and 60% by mass or less relative to 100% by mass of the total content of the semi-aromatic polyamide and the glass fiber.

3. In the formula (1), the Ar １ The pellet according to claim 1 or 2, wherein p is a 1,4-phenylene group and p is 9 or 10.

4. A method for producing pellets according to claim 1 or 2, The method includes melt-kneading a semi-aromatic polyamide and glass fibers in an extruder, The extruder comprises a kneading zone, The method for producing pellets, wherein the kneading zone comprises counter-rotating screw elements.

5. A molded article obtained by injection molding the pellets according to claim 1 or 2.

6. A gear comprising a semi-aromatic polyamide and glass fiber, The semi-aromatic polyamide has a structural unit represented by the following formula (1): A gear, wherein the coefficient of variation of the distance between centers of gravity of the glass fibers is 0.570 or less in a cross section of the gear teeth cut along a perpendicular bisector to a line connecting the tooth base and the tooth tip. 【Chemistry 2】 [In formula (1), Ar １ represents a phenylene group or a naphthylene group, and the plurality of Ar groups contained in the semi-aromatic polyamide １ may be the same or different, and p is an integer of 4 to 12.

Images