JP2023112242A - Semi-aromatic polyamide resin composition and molding including the same - Google Patents

Abstract

To provide a semi-aromatic polyamide resin composition that is excellent in low wear resistance and extrusion processability.SOLUTION: A semi-aromatic polyamide resin composition includes (A) a semi-aromatic polyamide including an aromatic dicarboxylic acid component primarily composed of terephthalic acid and an aliphatic diamine component primarily composed of decane diamine (component A) and also includes, relative to 100 pts.wt. of the A component, 0.1 pt.wt. or more and less than 3 pts.wt. of (B) an aliphatic polyamide (component B) and 1-20 pts.wt of (C) a polyethylenic slidability imparting agent (component C).SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a semi-aromatic polyamide resin composition having excellent low abrasion properties and extrusion processability, and a molded article using the same.

In recent years, semi-aromatic polyamides have been used as sliding members such as gears and bearings in automobiles and electrical/electronic equipment. Among them, sliding member applications such as various gears and bearings are exposed to continuous or intermittent frictional force, and therefore require low wear properties when sliding against mating members. In recent years, there has been a demand for components that can achieve a long life even in harsh environments such as high temperatures and high loads, and a higher degree of wear resistance than ever before is required.

As a semi-aromatic polyamide resin composition having slidability, for example, Patent Document 1 discloses a resin composition in which polyamide 10T (a polyamide composed of terephthalic acid and 1,10-decanediamine) is incorporated with a slidability imparting agent. However, low wear properties under severe environments such as high loads are insufficient. Patent Document 2 discloses a resin composition containing MXD6 (polyamide composed of adipic acid and meta-xylenediamine) containing a slidability imparting material and an aliphatic polyamide, but the low wear property is insufficient.

Japanese Patent No. 5837377 Japanese Patent No. 6827815

An object of the present invention is to provide a semi-aromatic polyamide resin composition which is excellent in low wear and extrusion processability, and a molded article using the same.

As a result of intensive studies by the present inventors to solve the above-mentioned problems, a semi-aromatic polyamide composed of an aromatic dicarboxylic acid component mainly composed of terephthalic acid and an aliphatic diamine component mainly composed of decanediamine, The present inventors have found that the above object can be achieved by blending an aliphatic polyamide and a polyethylene-based slidability imparting material in a specific ratio, and have completed the present invention.

That is, the above-mentioned problem is to solve the following problems with respect to 100 parts by weight of a semi-aromatic polyamide (component A) composed of (A) an aromatic dicarboxylic acid component containing terephthalic acid as a main component and an aliphatic diamine component containing decanediamine as a main component, (B) 0.1 parts by weight or more and less than 3 parts by weight of an aliphatic polyamide (component B) and (C) 1 to 20 parts by weight of a polyethylene-based slidability imparting material (component C). This is achieved by a group polyamide resin composition.

The details of the present invention will be described below.

(A component: semi-aromatic polyamide)
The A component of the present invention contains an aromatic dicarboxylic acid component and an aliphatic diamine component as constituent components, the aromatic dicarboxylic acid component is mainly composed of terephthalic acid, and the aliphatic diamine component is mainly composed of decanediamine. It is. From the viewpoint of heat resistance, the content of terephthalic acid is preferably 80 mol % or more, more preferably 100 mol %, in the aromatic dicarboxylic acid component. From the viewpoint of improving mechanical properties, the content of decanediamine is preferably 80 mol % or more, more preferably 100 mol %, in the aliphatic diamine component. A specific example of the A component is PA10T.

The aromatic dicarboxylic acid component may contain aromatic dicarboxylic acids other than terephthalic acid. Examples of aromatic dicarboxylic acids other than terephthalic acid include phthalic acid, isophthalic acid, and naphthalenedicarboxylic acid. Aromatic dicarboxylic acids other than terephthalic acid are preferably contained in an amount of 20 mol% or less, more preferably substantially absent, relative to the total number of moles of the raw material monomers.

The aliphatic diamine component may contain other aliphatic diamines than decanediamine. Other aliphatic diamines include, for example, 1,2-ethanediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptane Diamine, 1,8-octanediamine, 1,9-nonanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 1,13-tridecanediamine, 1,14-tetradecanediamine, 1,15-pentadecanediamine etc. Aliphatic diamines other than the decanediamine component are preferably contained in an amount of 20 mol % or less, more preferably substantially absent, relative to the total number of moles of the raw material monomers.

The A component in the present invention preferably has a melting point higher than 300°C, which may improve the heat resistance. When it has multiple melting points, or when two or more semi-aromatic polyamides are used, it may have a melting point of 300° C. or lower.

Here, the melting point of component A in the present invention means that approximately 10 mg of semi-aromatic polyamide pellets are sampled and measured using a differential scanning calorimeter under a nitrogen atmosphere at a rate of 20° C./min from the molten state. It refers to the temperature of the endothermic peak that appears when the temperature is lowered to 20°C 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.

The A component can be produced using a conventionally known thermal polymerization method or solution polymerization method. A heat polymerization method is preferably used because it is industrially advantageous. Examples of the heat polymerization method include a method comprising step (i) of obtaining a reaction product from an aromatic dicarboxylic acid component and an aliphatic diamine component, and step (ii) of polymerizing the obtained reaction product.

As the step (i), for example, an aromatic dicarboxylic acid powder and a monocarboxylic acid are mixed, heated in advance to a temperature higher than the melting point of the aliphatic diamine and lower than the melting point of the aromatic dicarboxylic acid, and A method of adding an aliphatic diamine to a dicarboxylic acid powder and a monocarboxylic acid without substantially containing water so as to maintain the state of the aromatic dicarboxylic acid powder can be mentioned. Alternatively, as another method, a suspension consisting of a molten aliphatic diamine and a solid aromatic dicarboxylic acid is stirred and mixed to obtain a mixed liquid, and then the melting point of the finally produced semi-aromatic polyamide At a temperature of less than 100°C, a reaction of aromatic dicarboxylic acid, an aliphatic diamine and a monocarboxylic acid to form a salt and a reaction of polymerizing the produced salt to form a low polymer are performed to form a mixture of the salt and the low polymer. method to obtain. In this case, the crushing may be performed while reacting, or the crushing may be performed after taking out once after the reaction. As the step (i), the former is preferable because the shape of the reaction product can be easily controlled.

In step (ii), for example, the reaction product obtained in step (i) is solid-phase polymerized at a temperature below the melting point of the semi-aromatic polyamide to be finally produced to increase the molecular weight to a predetermined molecular weight. , to obtain semi-aromatic polyamides. Solid state polymerization is preferably carried out at a polymerization temperature of 180 to 270° C. for a reaction time of 0.5 to 10 hours in an inert gas stream such as nitrogen.

The reaction apparatus for steps (i) and (ii) is not particularly limited, and a known apparatus may be used. Step (i) and step (ii) may be performed in the same device or in different devices.

In the production of component A, a polymerization catalyst may be used to increase the efficiency of polymerization. Polymerization catalysts include, for example, phosphoric acid, phosphorous acid, hypophosphorous acid, or salts thereof. The addition amount of the polymerization catalyst is usually preferably 2 mol % or less with respect to the total monomers constituting the semi-aromatic polyamide.

(B component: aliphatic polyamide)
Aliphatic polyamides used as component B in the present invention include poly ε-capramide (PA6), polytetramethylene adipamide (PA46), polyhexamethylene adipamide (PA66), polyhexamethylene sebacamide (PA610 ), polyhexamethylenedodecanamide (PA612), polyundecamethyleneadipamide (PA116), polyundecanamide (PA11), polydodecanamide (PA12) and polyamide copolyamides containing at least two different polyamide components of these. Polymers, mixtures thereof, and the like are mentioned. Among them, polyamides having 6 or less carbon atoms in the structural unit are preferred, and PA6 (nylon 6) and PA66 (nylon 66) are preferred from the viewpoint of economy. By using an aliphatic polyamide, it is possible to improve the wear resistance of the molded product.

The relative viscosity of the aliphatic polyamide is not particularly limited, and may be appropriately set according to the purpose. For example, in order to obtain a resin composition that is easy to mold, the aliphatic polyamide preferably has a relative viscosity of 1.9 to 4.0, more preferably 2.0 to 3.5. If the relative viscosity of the aliphatic polyamide is less than 1.9, the toughness of some molded articles may be insufficient, resulting in deterioration of mechanical properties. On the other hand, when the relative viscosity of the aliphatic polyamide exceeds 4.0, the resin composition may be difficult to mold, and the resulting molded article may have poor appearance.

The content of component B is 0.1 parts by weight or more and less than 3 parts by weight, preferably 0.3 to 2.5 parts by weight, more preferably 0.5 to 2 parts by weight, relative to 100 parts by weight of component A. Department. If the content is less than 0.1 parts by weight or more than 3 parts by weight, the amount of wear during sliding increases.

(Component C: polyethylene-based slidability imparting material)
As the polyethylene-based slidability imparting material used as the C component in the present invention, those known per se can be used. By using the polyethylene-based slidability-imparting material, it is possible to improve the wear resistance of the molded product. Examples of polyethylene used as a starting material for producing a polyethylene-based slidability imparting material include high-density polyethylene, low-density polyethylene, ultra-high molecular weight polyethylene, and viscosity-average molecular weight of tens of thousands or more. The following polyethylene waxes and mixtures of one or more thereof are exemplified. As a method for modifying polyethylene, various conventionally known methods can be employed, for example, a method of introducing a functional group by oxidation reaction by introducing air into the polyethylene in a molten state of 140 to 180 ° C., and a method of introducing a functional group by an oxidation reaction. Suspending or dissolving in a solvent, usually at a temperature of 80 to 200 ° C., adding and mixing a modifying monomer and a radical polymerization initiator etc. for graft copolymerization, or melting point or higher, for example, 180 A method of contacting a modifying monomer and a radical polymerization initiator under melt-kneading at a temperature of up to 300° C. may be mentioned. Examples of modifying monomers include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, crotonic acid, nadic acid (endocis-bicyclo[2,2]hept-5-ene-2,3 -dicarboxylic acid), etc., and its derivatives include acid halides, esters, amides, imides, anhydrides, etc., for example, malenyl chloride, maleimide, acrylic acid amide, methacrylic acid amide, glycidyl methacrylate, anhydrous Maleic acid, citraconic anhydride, monomethyl maleate, dimethyl maleate, glycidyl maleate and the like. Among these, modified polyethylene resins modified with maleic acid, maleic anhydride or a mixture thereof are preferred, and modified polyethylene resins modified with maleic anhydride are particularly preferred. By using these preferred modified polyethylene resins, it may be possible to further improve the abrasion resistance of molded articles.

The preferred range of viscosity average molecular weight (Mv) of component C is 100,000 to 1,000,000, more preferably 200,000 to 900,000, and particularly preferably 300,000 to 800,000. be. By using a polyethylene resin within this range, it may be possible to further improve the abrasion resistance of the molded product. The viscosity-average molecular weight of component C is obtained from the following general formula (1) using the intrinsic viscosity [η] measured in a decalinic acid solvent at 135°C.
Mv=5.37×10 ⁴ [η] ^1.37 (1)
The content of component C is 1 to 20 parts by weight, preferably 3 to 18 parts by weight, more preferably 5 to 15 parts by weight, per 100 parts by weight of component A. If the content is less than 1 part by weight, the amount of wear during sliding increases. If it exceeds 20 parts by weight, the extrusion workability will be deteriorated.

(About other additives)
In addition, the resin composition of the present invention may be blended with other thermoplastic resins within the scope of the present invention, and if necessary, antioxidants, impact modifiers, plasticizers, organic or inorganic fillers. Additives such as additives, flame retardants, colorants, light stabilizers, heat stabilizers, antistatic agents, antiblocking agents, lubricants other than component C, dispersants, flow modifiers, crystal nucleating agents, etc. can be done.

(Manufacture of resin composition)
Any method may be employed to produce the resin composition of the present invention. For example, a method of premixing each component and optionally other components, followed by melt-kneading and pelletizing can be mentioned. Means for premixing include a Nauta mixer, a V-type blender, a Henschel mixer, a mechanochemical device, an extrusion mixer, and the like. In the pre-mixing, granulation can be performed by an extrusion granulator, a briquetting machine, or the like. After pre-mixing, the mixture is melt-kneaded by a melt-kneader typified by a vented twin-screw extruder, and pelletized by a device such as a pelletizer. Other examples of the melt-kneader include a Banbury mixer, a kneading roll, a constant temperature stirring vessel and the like, but a vented twin-screw extruder is preferred. Alternatively, each component and, optionally, other components may be supplied independently to a melt-kneader typified by a twin-screw extruder without being premixed.

(About molded products)
The resin composition of the present invention obtained as described above can be produced into various products by injection molding or extrusion molding of the pellets produced as described above. Further, it is also possible to directly form a sheet, film, profile extrusion molded product, and injection molded product from the resin melt-kneaded in an extruder without going through pellets. In injection molding, not only ordinary molding methods but also injection compression molding, injection press molding, gas-assisted injection molding, foam molding (including injection of supercritical fluid), insert molding, injection molding, etc. Molded articles can be obtained using injection molding methods such as mold coating molding, adiabatic molding, rapid heat and cool molding, two-color molding, sandwich molding, and ultra-high speed injection molding. The advantages of these various molding methods are already widely known. For molding, either cold runner method or hot runner method can be selected. Moreover, the resin composition of the present invention can also be molded into various shaped extruded products and sheets by extrusion molding. In extrusion molding, a molded product can be obtained by extruding a round bar and then cutting it into a disk shape, or by extruding a thick sheet and then punching it into a predetermined shape. can.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a semi-aromatic polyamide resin composition excellent in low wear and extrusion processability and a molded article using the same. It can be suitably used for sliding members used in electric/electronics, semiconductors, automobiles, industrial machinery, OA equipment and construction fields.

The mode for carrying out the present invention summarizes the preferable range of each of the above requirements, and for example, the representative examples are described in the following examples. Of course, the present invention is not limited to these forms.

Hereinafter, embodiments for carrying out the present invention will be described with reference to examples. In addition, evaluation of various physical properties was implemented by the following method.

[Evaluation of Resin Composition]
As evaluation of extrusion processability, stability during extrusion was measured, and as evaluation of low wear property, specific abrasion loss was measured by the following methods.
(1) Extrusion Processability Stability during extrusion was evaluated according to the following criteria.
Strands are stable during extrusion. : O The strand during extrusion is unstable and pelletization is difficult. : ×
(2) Specific wear amount After drying the pellets obtained by the following method at 130 ° C. for 6 hours, using an 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. A hollow cylindrical test piece having an outer diameter of 25.6 mm, an inner diameter of 20 mm and a height of 15 mm was obtained according to the JIS K7218A method. According to the JIS K7218A method, the test piece was subjected to a friction and wear tester (EFM) under the conditions of a test piece of the same shape made of carbon steel (S45C) and a surface pressure of 0.75 MPa, a sliding speed of 500 mm / s, and a sliding distance of 3000 m. -3-G, manufactured by Orientec Co., Ltd.). The weight loss of the test piece after sliding was weighed to the nearest 0.1 mg using an electronic balance, and the specific wear amount was calculated using the formula described in JIS K7218A method. The test was conducted three times, and the average value thereof was taken as the specific wear amount of the composition. The specific wear amount must be 2.0×10 ⁻⁶ mm ³ /N·m or less.

[Example 1-8, Comparative Example 1-4]
According to the addition amount shown in Table 1, A component, B component and C component were separately supplied to the twin-screw extruder from the first supply port. Here, the first supply port is the root supply port. Extrusion is performed using a vented twin-screw extruder with a diameter of 30 mmΦ (manufactured by Japan Steel Works, Ltd.: TEX30α-31.5BW-3V), screw rotation speed of 200 rpm, discharge rate of 20 kg / h, vent vacuum degree of 3 kPa. It was melted and kneaded to obtain pellets. The extrusion temperature was 330°C.

(A component)
A-1: Semi-aromatic polyamide: PA10T (manufactured by Unitika Ltd.: Zecot XP500)
(B component)
B-1: Aliphatic polyamide: PA6 (manufactured by Ube Industries, Ltd.: UBE nylon 1011FB)
B-2: Aliphatic polyamide: PA66 (manufactured by Ube Industries, Ltd.: UBE Nylon 2015B)

(C component)
C-1: Maleic anhydride-modified polyethylene resin obtained in Production Example 1 <Production Example 1>
15% by weight of ultra-high molecular weight polyethylene (Hi-Zex Million 630M manufactured by Mitsui Chemicals, Inc.) with an intrinsic viscosity of 31 dl/g measured in a decalic acid solvent at 135°C and a limit measured in a decalic acid solvent at 135°C 100 parts by weight of a polyethylene resin mixture consisting of 85% by weight of polyethylene (Hi-Zex 2200J manufactured by Prime Polymer Co., Ltd.) having a viscosity of 2 dl/g, 1 part by weight of maleic anhydride and an organic peroxide (perhexin manufactured by NOF Corporation) 25B) 0.07 part by weight was mixed with a Nauta mixer, and the resulting mixture was melt-kneaded with a single-screw extruder (EXT 40 m / m extruder manufactured by Isuzu Kakoki Co., Ltd.) set at 250 ° C. C- One component was obtained. The resulting modified polyethylene resin had an intrinsic viscosity [η] measured in decalinic acid at 135°C of 5.5 dl/g and a viscosity average molecular weight Mv of 550,000.

C-2: Polyethylene resin obtained in Production Example 2 <Production Example 2>
15% by weight of ultra-high molecular weight polyethylene (Hi-Zex Million 630M manufactured by Mitsui Chemicals, Inc.) with an intrinsic viscosity of 31 dl/g measured in a decalic acid solvent at 135°C and a limit measured in a decalic acid solvent at 135°C 100 parts by weight of a polyethylene resin mixture containing 85% by weight of polyethylene (Hi-Zex 2200J manufactured by Prime Polymer Co., Ltd.) having a viscosity of 2 dl/g was mixed in a Nauta mixer, and the resulting mixture was subjected to uniaxial extrusion at 250°C. (EXT40m/m extruder manufactured by Isuzu Kakoki Co., Ltd.) to obtain a C-2 component. The intrinsic viscosity [η] of the resulting polyethylene resin measured in decalinic acid at 135° C. was 5.5 dl/g, and the viscosity average molecular weight Mv was 550,000.
C-3: Oxidized polyethylene wax: Hi-Wax 310MP (product name) (manufactured by Mitsui Chemicals, Inc., viscosity average molecular weight of about 3,000)

<Examples 1 to 8>
Since the resin composition is within the scope of the present claims, the result was excellent in low wear and extrusion processability.

<Comparative Example 1>
Since the content of the B component was less than the lower limit, the specific wear amount was large.
<Comparative Example 2>
Since the content of the B component exceeded the upper limit, the specific wear amount was large.
<Comparative Example 3>
Since the content of the C component was less than the lower limit, the specific wear amount was large.
<Comparative Example 4>
Pelletization was not possible because the content of component C exceeded the upper limit.

Claims (4)

(A) Semi-aromatic polyamide (component A) consisting of an aromatic dicarboxylic acid component mainly composed of terephthalic acid and an aliphatic diamine component mainly composed of decanediamine (B) aliphatic polyamide A semi-aromatic polyamide resin composition comprising 0.1 parts by weight or more and less than 3 parts by weight of (Component B) and 1 to 20 parts by weight of (C) a polyethylene-based slidability imparting material (Component C). 2. The semi-aromatic polyamide resin composition according to claim 1, wherein the B component is nylon 6 and/or nylon 66. 3. The semi-aromatic polyamide resin composition according to claim 1, wherein component C is a modified polyethylene resin modified with maleic anhydride having a viscosity average molecular weight of 100,000 to 1,000,000. thing. A molded article made of the semi-aromatic polyamide resin composition according to any one of claims 1 to 3.