Semi-aromatic polyamide resin composition and molded article made therefrom

Abstract

To provide a semi-aromatic polyamide resin composition which is superior in terms of low wear characteristics after heat treatment as well as extrusion processability.SOLUTION: A semi-aromatic polyamide resin composition comprises 3 to 80 pts.wt. of (B) meta-type wholly aromatic polyamide fiber (component B) relative to 100 pts.wt. of (A) a semi-aromatic polyamide resin comprising a dicarboxylic acid component mainly composed of terephthalic acid and an aliphatic diamine component mainly composed of 1,10-decanediamine (component A).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a semi-aromatic polyamide resin composition excellent in low wear properties and extrusion processability after heat treatment, and a molded article made thereof.

Background Art

[0002] In recent years, semi-aromatic polyamide resins have been used as sliding members such as gears and bearings in automobiles and electric / electronic devices. Among them, in applications of sliding members such as various gears and bearings, since they are exposed to continuous or intermittent frictional forces, low wear properties when sliding against mating materials are required. In recent years, there has been a demand for members that can achieve a longer life even in harsh environments such as high temperature and high load, and higher mechanical strength, heat resistance, and low wear properties than in the past have been required.

[0003] As resin compositions containing wholly aromatic polyamide fibers having slidability, for example, Patent Document 1 discloses a resin composition in which wholly aromatic polyamide fibers are contained in a thermoplastic resin, and Patent Document 2 discloses a resin composition in which para-type wholly aromatic polyamide fibers and polytetrafluoroethylene are contained in polyamide 10T (a polyamide resin composed of terephthalic acid and 1,10-decanediamine). However, these resin compositions are insufficient in low wear properties when subjected to a harsh environment exposed to high temperatures.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object of the present invention is to provide a semi-aromatic polyamide resin composition excellent in low wear property and extrusion processability after heat treatment, and a molded article made thereof. [Means for Solving the Problems]

[0006] As a result of intensive studies to solve the above problems, the present inventors have found that by blending a meta-type wholly aromatic polyamide fiber in a specific ratio with a semi-aromatic polyamide resin composed of a dicarboxylic acid component mainly composed of terephthalic acid and a diamine component mainly composed of 1,10-decanediamine, the above object can be achieved, and thus the present invention has been completed.

[0007] That is, the present invention is as follows. 1. A semi-aromatic polyamide resin composition comprising (A) 100 parts by weight of a semi-aromatic polyamide resin (component A) composed of a dicarboxylic acid component mainly composed of terephthalic acid and an aliphatic diamine component mainly composed of 1,10-decanediamine, and (B) 3 to 80 parts by weight of a meta-type wholly aromatic polyamide fiber (component B). 2. The semi-aromatic polyamide resin composition according to item 1 above, comprising (C) 1 to 30 parts by weight of a polyethylene-based slidability-imparting material (component C) with respect to 100 parts by weight of component A. 3. The semi-aromatic polyamide resin composition according to item 2 above, wherein component C is a modified polyethylene resin modified with at least one compound selected from the group consisting of maleic acid and maleic anhydride and having a viscosity-average molecular weight of 100,000 to 1,000,000. 4. A molded article made of the semi-aromatic polyamide resin composition according to any one of items 1 to 3 above.

[0008] Hereinafter, the details of the present invention will be described.

[0009] (Component A: Semi-aromatic polyamide resin) Component A of the present invention is a semi-aromatic polyamide resin composed of a dicarboxylic acid component mainly containing terephthalic acid and an aliphatic diamine component mainly containing 1,10-decanediamine. When a polyamide resin other than the semi-aromatic polyamide resin is used, the low wear resistance after heat treatment decreases. From the viewpoint of heat resistance, the content of terephthalic acid is preferably 80 mol% or more, more preferably 100 mol%, in the dicarboxylic acid component. From the viewpoint of improving mechanical properties, the content of 1,10-decanediamine is preferably 80 mol% or more, more preferably 100 mol%, in the aliphatic diamine component. Specific examples of Component A include PA10T and the like.

[0010] The dicarboxylic acid component may contain a dicarboxylic acid other than terephthalic acid. Examples of the dicarboxylic acid other than terephthalic acid include aromatic dicarboxylic acid components such as phthalic acid, isophthalic acid, and naphthalenedicarboxylic acid, aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, and dodecanedioic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid. The dicarboxylic acid other than terephthalic acid is preferably 20 mol% or less, more preferably substantially not contained, based on the total number of moles of the raw material monomers.

[0011] The aliphatic diamine component may contain a diamine other than 1,10-decanediamine. Examples of the other diamine include, for example, 1,2-ethanediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 1,13-tridecanediamine, 1,14-tetradecanediamine, and 1,15-pentadecanediamine. The diamine other than the 1,10-decanediamine component is preferably 20 mol% or less, more preferably substantially not contained, based on the total number of moles of the raw material monomers.

[0012] Component A in the present invention preferably has a melting point higher than 300 °C, and in some cases, the heat resistance can be further improved thereby. When there are multiple melting points or when using two or more semi-aromatic polyamide resins, it may have a melting point of 300 °C or lower.

[0013] Here, the melting point of Component A in the present invention refers to the temperature of the endothermic peak that appears when about 10 mg of pellets of the semi-aromatic polyamide resin are collected, and using a differential scanning calorimeter, in a nitrogen atmosphere, the temperature is lowered from the molten state to 20 °C at a rate of 20 °C / min and held for 5 minutes, and then the temperature is raised at a rate of 20 °C / min. However, when two or more endothermic peaks are detected, the peak with the highest temperature is taken as the melting point.

[0014] Component A can be produced using conventionally known methods such as the thermal polymerization method and the solution polymerization method. From the viewpoint of industrial advantage, the thermal polymerization method is preferably used. Examples of the thermal polymerization method include a method comprising a step (i) of obtaining a reaction product from a dicarboxylic acid component and a diamine component, and a step (ii) of polymerizing the obtained reaction product.

[0015] As step (i), for example, a method is to mix a dicarboxylic acid powder and a monocarboxylic acid, heat them in advance to a temperature equal to or higher than the melting point of the diamine and lower than the melting point of the dicarboxylic acid, and add the diamine to the dicarboxylic acid powder and monocarboxylic acid at this temperature without substantially containing water so as to keep the dicarboxylic acid in a powder state. Alternatively, as another method, a suspension composed of a molten diamine and a solid dicarboxylic acid is stirred and mixed to obtain a mixed solution, and then, at a temperature lower than the melting point of the finally produced semi-aromatic polyamide resin, a salt formation reaction by the reaction of the dicarboxylic acid, diamine, and monocarboxylic acid and a low polymer formation reaction by the polymerization of the produced salt are carried out to obtain a mixture of the salt and the low polymer. In this case, crushing may be carried out while the reaction is in progress, or the reaction product may be taken out once after the reaction and then crushed. As step (i), the former method, which is easier to control the shape of the reaction product, is preferred.

[0016] As the step (ii), for example, there may be mentioned a method of subjecting the reaction product obtained in the step (i) to solid-phase polymerization at a temperature lower than the melting point of the finally produced semi-aromatic polyamide resin to increase the molecular weight to a predetermined molecular weight and obtaining a semi-aromatic polyamide resin. The solid-phase polymerization is preferably carried out in an inert gas stream such as nitrogen at a polymerization temperature of 180 to 270°C and a reaction time of 0.5 to 10 hours.

[0017] The reaction apparatuses for the step (i) and the step (ii) are not particularly limited, and known apparatuses may be used. The step (i) and the step (ii) may be carried out in the same apparatus or in different apparatuses.

[0018] In the production of the component A, a polymerization catalyst may be used to enhance the polymerization efficiency. Examples of the polymerization catalyst include phosphoric acid, phosphorous acid, hypophosphorous acid or their salts. The addition amount of the polymerization catalyst is usually preferably used at 2 mol% or less based on all the monomers constituting the semi-aromatic polyamide resin.

[0019] (Component B: meta-type wholly aromatic polyamide fiber) As the meta-type wholly aromatic polyamide fiber used as the component B in the present invention, any fiber belonging to the category called meta-type wholly aromatic aramid fiber may be used. By using the meta-type wholly aromatic polyamide fiber, excellent low wear property after heat treatment can be exhibited.

[0020] Particularly preferred meta-type aromatic polyamide fibers are those in which 85 mol% or more of all the repeating units of the polymer are metaphenylene isophthalamide units, and particularly preferably those composed of a polymetaphenylene isophthalamide homopolymer. Incidentally, as the third component that can be copolymerized in a small amount, aromatic diamines such as paraphenylenediamine as the diamine component and aromatic dicarboxylic acids such as terephthalic acid as the acid component may be mentioned.

[0021] The fineness of the single fiber of the meta-based polyamide fiber is preferably in the range of 0.1 to 5.5 dtex, more preferably 0.3 to 2.5 dtex. When the fineness of the staple fiber is less than 0.1 dtex, there are many difficulties in the spinning technology, not only making it difficult to stably produce fibers of good quality due to yarn breakage and hairiness, but also increasing the cost in some cases. On the other hand, when the fineness of the staple fiber exceeds 5.5 dtex, the mechanical properties of the fiber, especially the strength reduction, becomes large, and it may be difficult to uniformly disperse the fiber in the molded body when it is made into a fiber-reinforced resin molded body.

[0022] The content of the B component is 3 to 80 parts by weight, preferably 10 to 75 parts by weight, more preferably 20 to 70 parts by weight, and still more preferably 30 to 65 parts by weight with respect to 100 parts by weight of the A component. When the content of the B component exceeds 80 parts by weight, the extrusion processability deteriorates. On the other hand, when the content is less than 3 parts by weight, the low wear resistance after heat treatment deteriorates.

[0023] (C component: polyethylene-based slidability imparting material) The semi-aromatic polyamide resin composition of the present invention can contain a polyethylene-based slidability imparting material as the C component. By using the polyethylene-based slidability imparting material, the low wear resistance of the molded body can be further improved. As the polyethylene-based slidability imparting material, those known per se can be used, and examples include high-density polyethylene, low-density polyethylene, ultra-high molecular weight polyethylene, polyethylene obtained by polymerizing ultra-high molecular weight polyethylene and high molecular weight or low molecular weight polyethylene by a multi-step polymerization method, and modified products thereof. These may be used as a mixture of two or more.

[0024] As the polyethylene used as a starting material when producing a polyethylene-based sliding property-imparting material, for example, high-density polyethylene, low-density polyethylene, ultra-high molecular weight polyethylene with a viscosity-average molecular weight of tens of thousands or more, polyethylene wax with a viscosity-average molecular weight of tens of thousands or less, and a mixture of one or more of these are exemplified. As methods for modifying polyethylene, various conventionally known methods can be adopted. For example, a method of introducing a functional group by an oxidation reaction by introducing air into the above polyethylene in a molten state at 140 to 180 °C, suspending or dissolving the above polyethylene in a solvent, and usually adding and mixing a monomer for modification and a radical polymerization initiator at a temperature of 80 to 200 °C for graft copolymerization, and a method of bringing the monomer for modification and the radical polymerization initiator into contact under melt kneading at a temperature above the melting point, for example, 180 to 300 °C, etc. are mentioned. Examples of the monomer for modification include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, crotonic acid, and nadic acid (endo-cis-bicyclo[2,2]hept-5-ene-2,3-dicarboxylic acid), etc., and derivatives thereof include acid halides, esters, amides, imides, and anhydrides, etc. For example, maleyl chloride, maleimide, acrylamide, methacrylamide, glycidyl methacrylate, maleic anhydride, citraconic anhydride, monomethyl maleate, dimethyl maleate, and glycidyl maleate, etc. are mentioned. Among these, a modified polyethylene resin modified with maleic acid, maleic anhydride, or a mixture thereof is preferable, and a modified polyethylene resin modified with maleic anhydride is particularly preferable. By using these preferable modified polyethylene resins, the low wear property of the molded body may be further improved.

[0025] The preferable range of the viscosity-average molecular weight (Mv) of the C component is from 100,000 to 1,000,000, more preferably from 200,000 to 900,000, and particularly preferably from 300,000 to 800,000. By using a polyethylene resin within this range, the low wear property of the molded body may be further improved. The viscosity-average molecular weight of the C component is determined from the following general formula (1) using the intrinsic viscosity [η] measured in a decalin solvent at 135 °C. Mv = 5.37×10 4 [η] 1.37 ···(1)

[0026] The content of component C is preferably 1 to 30 parts by weight, more preferably 3 to 28 parts by weight, and still more preferably 5 to 25 parts by weight with respect to 100 parts by weight of component A. If the content is less than 1 part by weight or exceeds 30 parts by weight, the low wear resistance after heat treatment may decrease.

[0027] (Regarding other additives) In the resin composition of the present invention, within a range not contrary to the gist of the present invention, other thermoplastic resins can be blended, and if necessary, antioxidants, impact modifiers, plasticizers, organic and inorganic fillers other than component B, flame retardants, coloring materials, light stabilizers, heat stabilizers, antistatic agents, antiblocking agents, lubricants excluding component C, dispersants, flow modifiers, crystal nucleating agents and other additives can be included.

[0028] (Manufacture of resin composition) To manufacture the resin composition of the present invention, any method can be adopted. For example, a method of preliminarily mixing each component and optionally other components, then melt-kneading and pelletizing can be mentioned. Examples of the means for preliminary mixing include Nauta mixer, V-type blender, Henschel mixer, mechanochemical device, extrusion mixer, etc. In preliminary mixing, granulation can also be carried out by an extrusion granulator or a briquetting machine in some cases. After preliminary mixing, melt-kneading is performed with a melt-kneading machine typified by a vented twin-screw extruder, and pelletizing is performed with equipment such as a pelletizer. Other examples of the melt-kneading machine include Banbury mixer, kneading roll, constant-temperature stirring vessel, etc., but a vented twin-screw extruder is preferred. Alternatively, a method of independently supplying each component and optionally other components to a melt-kneading machine typified by a twin-screw extruder without preliminary mixing can also be adopted.

[0029] (Regarding molded articles) The resin composition of the present invention obtained as described above can usually be used to produce various products by injection molding or extrusion molding the pellets produced as described above. Furthermore, without passing through the pellets, it is also possible to directly form the resin melt-kneaded by an extruder into sheets, films, profile extruded products, and injection molded products. In injection molding, not only ordinary molding methods but also, as appropriate according to the purpose, injection compression molding, injection press molding, gas assist injection molding, foam molding (including those by injection of supercritical fluids), insert molding, in-mold coating molding, adiabatic mold molding, rapid heating and cooling mold molding, two-color molding, sandwich molding, and ultra-high speed injection molding and other injection molding methods can be used to obtain molded products. The advantages of these various molding methods are already widely known. Also, either a cold runner system or a hot runner system can be selected for molding. Further, the resin composition of the present invention can also be used to form various profile extruded products and sheets by extrusion molding. In extrusion molding, a method of obtaining a molded body by extruding a round bar and then cutting it into a disk shape, or a method of obtaining a molded body by extruding a thick sheet and then punching it into a predetermined shape can be used.

Advantages of the Invention

[0030] According to the present invention, it is possible to provide a semi-aromatic polyamide resin composition excellent in low wear properties and extrusion processability after heat treatment, and a molded product made therefrom. The molded product obtained from the resin composition of the present invention can be suitably used, for example, as a sliding member used in the fields of electric and electronic, semiconductor, automobile, industrial machinery, OA equipment, and construction.

Modes for Carrying Out the Invention

[0031] The modes for carrying out the present invention are an aggregation of the preferable ranges of the above-mentioned respective requirements. For example, representative examples thereof are described in the following examples. Of course, the present invention is not limited to these modes.

Examples

[0032] Hereinafter, embodiments for implementing the present invention will be described with reference to examples. The evaluation of various physical properties was carried out by the following methods.

[0033] [Evaluation of Resin Composition] Regarding the evaluation of extrusion processability, the stability during extrusion was measured by the following method, and the specific wear rate after heat treatment was measured as an evaluation of low wear property by the following method. (1) Extrusion Processability Regarding the stability during extrusion, evaluation was carried out according to the following criteria. The strand during extrusion is stable: ○ The strand during extrusion is unstable and pelletization is difficult: ×

[0034] (2) Specific Wear Rate after Heat Treatment The pellets obtained by the following method were dried at 130 °C for 6 hours, and then a hollow cylindrical test piece with an outer diameter of 25.6 mm, an inner diameter of 20 mm, and a height of 15 mm was obtained by injection molding machine (EC130SXII-4Y, manufactured by Toshiba Machine Co., Ltd.) at a cylinder temperature of 330 °C and a mold temperature of 130 °C in accordance with JIS K7218A method. The test piece was left standing in an oven at 200 °C for 100 hours to carry out heat treatment. The heat-treated test piece was slid using a friction and wear testing machine (EFM-3-G, manufactured by Orientec Co., Ltd.) under the conditions of a surface pressure of 0.75 MPa, a sliding speed of 500 mm / s, and a sliding distance of 3000 m with a test piece of the same shape made of carbon steel (S45C) in accordance with JIS K7218A method. The weight loss of the test piece after sliding was weighed to the unit of 0.1 mg using an electronic balance, and the specific wear rate was calculated using the calculation formula described in JIS K7218A method. The test was carried out 3 times, and the average value thereof was taken as the specific wear rate of the composition after heat treatment. The specific wear rate after heat treatment needs to be 40×10 -6 mm 3 / N·m or less.

[0035] [Examples 1-16, Comparative Examples 1-5, 7] According to the addition amounts shown in Table 1 and Table 2, Component A, Component C, and other components were separately supplied to a twin-screw extruder from the first supply port. Here, the first supply port refers to the supply port at the base. Component B was separately supplied using a side feeder from the second supply port. Extrusion was carried out using a vented twin-screw extruder with a diameter of 30 mm Φ (manufactured by Nippon Steel Works, Ltd.: TEX30α-31.5BW-3V). Pellets were obtained by melt-kneading at a screw rotation speed of 200 rpm, a discharge rate of 20 kg / h, and a vacuum degree of the vent of 3 kPa. The extrusion temperature was 330 °C.

[0036] [Comparative Example 6] Pellets were obtained in the same manner as in Example 1 except that the extrusion temperature was 260 °C. [Comparative Example 8] Pellets were obtained in the same manner as in Example 1 except that the extrusion temperature was 290 °C.

[0037] In addition, the following materials were used in the examples and comparative examples of the present invention. (Component A) A-1: Semi-aromatic polyamide resin: PA10T (manufactured by Unitika Ltd.: Zecon XP500) A-2 (Comparative Example): Aliphatic polyamide resin: PA6 (manufactured by Ube Industries, Ltd.: UBE Nylon 1011FB) A-3 (Comparative Example): Aliphatic polyamide resin: PA66 (manufactured by Asahi Kasei Corporation: Leona 1402S)

[0038] (Component B) B-1: Meta-type wholly aromatic polyamide fiber: ST2.2×1 (product name) (manufactured by Teijin Limited, major axis 12 μm, average fiber length 1 mm, without sizing agent) B-2 (Comparative Example): Para-type wholly aromatic polyamide fiber: T322EH (product name) (manufactured by Teijin Limited, major axis 12 μm, average fiber length 3 mm, polyester resin sizing agent) B-3 (Comparative Example): Para-type wholly aromatic polyamide fiber: TW1088 (product name) (manufactured by Teijin Limited, major axis 12 μm, average fiber length 0.25 mm, polyester resin sizing agent)

[0039] (Component C) C-1: Maleic anhydride-modified polyethylene resin obtained in Production Example 1 <Production Example 1> 15 parts by weight of ultra-high molecular weight polyethylene (Hizex Million 630M manufactured by Mitsui Chemicals, Inc.) having an intrinsic viscosity measured in a decalin solvent at 135°C of 31 dl / g and 85 parts by weight of polyethylene (Hizex 2200J manufactured by Prime Polymer Co., Ltd.) having an intrinsic viscosity measured in a decalin solvent at 135°C of 2 dl / g were mixed with 1 part by weight of maleic anhydride and 0.07 part by weight of an organic peroxide (Perhexyne-25B manufactured by NOF Corporation) in a Nauter mixer. The resulting mixture was melt-kneaded using a single-screw extruder (EXT40m / m extruder manufactured by Isuzu Kako Co., Ltd.) set at 250°C to obtain a modified polyethylene resin. The intrinsic viscosity [η] of the obtained modified polyethylene resin measured in decalin at 135°C was 5.5 dl / g, and the viscosity-average molecular weight Mv was 550,000.

[0040] C-2: Polyethylene resin obtained in Production Example 2 <Production Example 2> 100 parts by weight of a polyethylene resin mixture composed of 15 parts by weight of ultra-high molecular weight polyethylene (Hizex Million 630M manufactured by Mitsui Chemicals, Inc.) having an intrinsic viscosity measured in a decalin solvent at 135°C of 31 dl / g and 85 parts by weight of polyethylene (Hizex 2200J manufactured by Prime Polymer Co., Ltd.) having an intrinsic viscosity measured in a decalin solvent at 135°C of 2 dl / g were mixed in a Nauter mixer. The resulting mixture was melt-kneaded using a single-screw extruder (EXT40m / m extruder manufactured by Isuzu Kako Co., Ltd.) set at 250°C to obtain a polyethylene resin. The intrinsic viscosity [η] of the obtained polyethylene resin measured in decalin at 135°C was 5.5 dl / g, and the viscosity-average molecular weight Mv was 550,000.

[0041] C-3: Oxidized polyethylene wax: Hiwax 310MP (product name) (manufactured by Mitsui Chemicals, Inc., viscosity-average molecular weight of about 3,000)

[0042]

Table 1

[0043]

Table 2

[0044] <Examples 1 to 16> Since it is a resin composition within the scope of the claims, it had excellent low wear property and extrudability after heat treatment. <Comparative Example 1> Since the content of Component B was less than the lower limit, the specific wear amount after heat treatment was large. <Comparative Example 2> Since the content of Component B exceeded the upper limit, the extrusion processability was poor. <Comparative Examples 3 and 4> Since Component B is a component outside the scope of the claims, the specific wear amount after heat treatment was large. <Comparative Examples 5 to 8> Since Component A is a component outside the scope of the claims, the specific wear amount after heat treatment was large.

Claims

1. (A) A semi-aromatic polyamide resin composition characterized by containing 3 to 80 parts by weight of a meta-based wholly aromatic polyamide fiber (Component B) with respect to 100 parts by weight of a semi-aromatic polyamide resin (Component A) composed of a dicarboxylic acid component mainly composed of terephthalic acid and an aliphatic diamine component mainly composed of 1,10-decanediamine.

2. The semi-aromatic polyamide resin composition according to Claim 1, characterized by containing 1 to 30 parts by weight of a polyethylene-based slidability-imparting material (Component C) with respect to 100 parts by weight of Component A.

3. The semi-aromatic polyamide resin composition according to Claim 2, characterized in that Component C is a modified polyethylene resin modified with at least one compound selected from the group consisting of maleic acid and maleic anhydride and having a viscosity-average molecular weight of 100,000 to 1,000,000.

4. A molded article made of the semi-aromatic polyamide resin composition according to any one of Claims 1 to 3.

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