JP2012072302A - Polyamide resin composition and molding composed of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyamide resin composition which has excellent rigidity, impact resistance and heat resistance, and in which gas production is reduced upon molding, and a molding using the same.SOLUTION: The polyamide resin composition is obtained by blending (B) 1 to 100 pts.wt. of an ethylene-α-olefin based block copolymer composed of ethylene and 3-20C α-olefin, (C) 1 to 50 pts.wt. of a polyethylene resin and (D) 0.01 to 20 pts.wt. of α, β unsaturated carboxylic acid or the derivatives thereof with (A) 100 pts.wt. of a polyamide resin.

Description

  The present invention relates to a polyamide resin composition excellent in rigidity, impact resistance, and heat resistance and generating less gas during heating or molding and a molded article using the same.

  Polyamide resins are excellent in mechanical properties such as strength and rigidity, and have good heat resistance and chemical resistance, and are widely used in electrical and electronic parts, automotive parts, building material parts, mechanical parts and the like. However, there is a problem in impact resistance and dimensional stability at the time of absolutely dry and at a low temperature, and there is a current situation that the use is limited by the environment.

  In recent years, in order to improve the impact resistance of polyamide resin, a method of blending various elastomers with polyamide resin has been proposed. For example, Patent Document 1 discloses a method of blending an ethylene / α-olefin copolymer elastomer having excellent toughness, but it is necessary to mold at 230 ° C. or higher to obtain a molded article of polyamide resin. Therefore, the ethylene / α-olefin copolymer, which is inferior in heat resistance, is thermally decomposed to generate gas, and the appearance of the molded product is deteriorated due to mold clogging or dirt, and furthermore, mold corrosion is likely to occur. There was a problem. General ethylene / α-olefin copolymer elastomers are random copolymers, and increasing the ethylene component to improve heat resistance increases the glass transition point, resulting in poor toughness of the resulting polyamide resin composition at low temperatures. It is sufficient and not suitable for automotive and electrical / electronic applications where cold resistance, cold heat resistance, freezing resistance and the like are required. Patent Document 2 proposes a cover material or clip material for automobile parts using a polyamide resin blended with an olefin copolymer elastomer. In particular, a clip having a hinge portion needs toughness so as not to break when the hinge portion is bent, and also needs rigidity so that the clip does not come off. By blending an elastomer with a polyamide resin, the impact resistance is improved. However, since the rigidity is lowered, it is not suitable for a clip material.

  In view of the above, there has been a demand for a polyamide resin having heat resistance and low gas properties and having an excellent balance between rigidity and impact resistance.

Japanese Patent Laying-Open No. 2005-330478 JP-A-4-220460

  An object of the present invention is to provide a polyamide resin composition excellent in low gas property, heat resistance, impact resistance and rigidity during molding.

The present invention employs the following means as a result of intensive studies to solve the above problems.
(1) (B) 1 to 100 parts by weight of an ethylene / α-olefin block copolymer comprising (B) ethylene and an α-olefin having 3 to 20 carbon atoms with respect to 100 parts by weight of the polyamide resin ( C) A polyamide resin composition comprising 1 to 50 parts by weight of a polyethylene resin and (D) 0.01 to 20 parts by weight of an α, β unsaturated carboxylic acid or a derivative thereof.
(2) Polyamide resin A) is polycaproamide, polyhexamethylene adipamide, polycaproamide / polyhexamethylene adipamide copolymer, polyhexamethylene adipamide / polyhexamethylene terephthalamide copolymer and polyhexamethylene terephthalamide / The polyamide resin composition according to (1), which is at least one selected from polyhexamethylene sebacamide copolymers.
(3) The polyamide resin composition according to (1) or (2), wherein the polyamide resin (A) has a viscosity number of 90 to 200 ml / g.
(4) The olefin of the ethylene / α-olefin block copolymer (B) is octene, the melting point is 100 ° C. or higher, and the glass transition point is −50 ° C. or lower (1) to The polyamide resin composition according to any one of (3).
(5) The density of polyethylene resin (C) is 0.85-0.98 g / cm < ³ >, The polyamide resin composition in any one of (1)-(4) characterized by the above-mentioned.
(6) A molded article comprising the polyamide resin composition according to any one of (1) to (5).
(7) The molded product according to (6), wherein the molded product has a hinge portion.

  The polyamide resin composition of the present invention is excellent in low gas property, heat resistance, impact resistance, and rigidity at the time of molding. Therefore, it is suitable for automobile parts and electrical / electronic parts, and when it is a molded product having a hinge part. It is effective, and is particularly useful for clips, clamps and band applications that bundle wires, cords, and tubes.

  The present invention will be described in detail below.

  Examples of the (A) polyamide resin used in the present invention include a ring-opening polymer of a cyclic lactam, a polycondensate of an aminocarboxylic acid, a polycondensate of a dibasic acid and a diamine. Proamide (nylon 6), polytetramethylene adipamide (nylon 46), polypentamethylene adipamide (nylon 56), polyhexamethylene adipamide (nylon 66), polyhexamethylene sebacamide (nylon 610) , Polyhexamethylene dodecanamide (nylon 612), polyundecanamide (nylon 11), polydodecanamide (nylon 12), polycaproamide / polyhexamethylene adipamide copolymer (nylon 6/66), polycaproamide / poly Hexamethylene terephthalamide copolymer (nylon 6 / 6T), Rihexamethylene adipamide / polyhexamethylene terephthalamide copolymer (nylon 66 / 6T), polyhexamethylene adipamide / polyhexamethylene isophthalamide copolymer (nylon 66 / 6I), polyhexamethylene terephthalamide / polyhexamethylene isophthalate Amide copolymer (nylon 6T / 6I), polyhexamethylene terephthalamide / polyhexamethylene sebamide copolymer (nylon 6T / 610), polyhexamethylene terephthalamide / polydodecanamide copolymer (nylon 6T / 12), polyhexamethylene azide Pamide / polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (nylon 66 / 6T / 6I), polyxylene adipamide (nylon XD6 , Polyhexamethylene terephthalamide / poly-2-methyl pentamethylene terephthalamide copolymer (nylon 6T / 5MT), poly nonamethylene terephthalamide (nylon 9T) and the like, and mixtures or copolymers of these. Particularly suitable polyamides for the present invention include nylon 6, nylon 66, nylon 66 / 6T, and nylon 6T / 610.

  As the degree of polymerization of the polyamide resin (A) used here, the viscosity number measured according to ISO 307 using 96% sulfuric acid as a solvent is in the range of 90 to 200 ml / g in terms of mechanical properties and fluidity. It is preferable that it is 90 to 150 ml / g. The polymerization method of the (A) polyamide resin used in the present invention is not particularly limited, and melt polymerization, interfacial polymerization, solution polymerization, bulk polymerization, solid phase polymerization, and a combination of these methods can be used. Usually, melt polymerization is preferably used.

  Next, the (B) ethylene / α-olefin block copolymer, which is an essential component of the invention, is obtained by copolymerizing ethylene and at least one α-olefin having 3 to 20 carbon atoms. However, it is a feature that the mode of copolymerization is block copolymerization.

The (B) ethylene / α-olefin block copolymer used in the present invention is characterized by a plurality of blocks of two or more polymerized monomer units having different chemical or physical properties, so-called segments, The following formula:
(AB) n
In the formula, n is an integer of at least 1 and preferably greater than 1, A represents a hard segment in which only ethylene is copolymerized, and B represents a soft segment in which only α-olefin is copolymerized. Due to the molecular skeleton in which the hard segment and the soft segment coexist, it has a lamellar structure like other crystalline resins.

  A method for producing (B) an ethylene / α-olefin block copolymer used in the present invention is disclosed in JP-T-2008-545016, and a catalyst for highly selectively polymerizing ethylene, an α-olefin is highly polymerized. By combining a selectively polymerizing catalyst and a reversible chain transfer agent, a block copolymer different from random copolymerization, which is a conventional copolymerization mode of an ethylene / α-olefin copolymer, can be obtained. The conventional ethylene / α-olefin copolymer is obtained only by a metallocene catalyst composed of a cyclopentadienyl derivative of a group IV metal such as titanium or zirconium and a cocatalyst. The mode of copolymerization obtained is random copolymerization. Moreover, before the manufacturing method by a metallocene catalyst was established, the manufacturing method by a Ziegler catalyst was used, but the copolymerization mode obtained is also random copolymerization.

  Examples of the (B) ethylene / α-olefin block copolymer (B) α-olefin having 3 to 20 carbon atoms used in the present invention include propylene, isobutylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-butene and the like are preferable, and 1-octene is particularly preferable.

  The melting point and glass transition point of the (B) ethylene / α-olefin block copolymer used in the present invention have a melting point of 100 ° C. or higher and a glass transition point of −50 ° C. or lower, preferably 110 ° C. The glass transition point is −55 ° C. or lower, more preferably the melting point is 115 ° C. or higher and the glass transition point is −60 ° C. or lower. When the melting point is 100 ° C. or higher, mold contamination can be reduced, and when the glass transition point is −50 ° C. or lower, the low temperature toughness of the polyamide resin can be improved.

  The melting point of the ethylene / α-olefin block copolymer (B) is determined by using a differential scanning calorimeter (DSC-60, manufactured by Shimadzu Corporation), and the temperature of the polymer is increased from room temperature to 20 ° C./min by differential calorimetry. After observing the endothermic peak temperature observed when measured under the conditions, the temperature was raised to a temperature of 180 ° C., held at that temperature for 3 minutes, and then cooled to −30 ° C. under a temperature drop condition of 20 ° C./min. Thereafter, the endothermic peak temperature observed when measured under a temperature rising condition of 10 ° C./min was determined and taken as the melting point.

  Further, the glass transition point of the (B) ethylene / α-olefin block copolymer is an endothermic peak observed when measured under the temperature rising condition of 20 ° C./min by the differential scanning heat flow meter. After observing the temperature, the temperature was raised to 130 ° C., kept at the same temperature for 3 minutes, then cooled to −100 ° C. at 10 ° C./min, and obtained from the obtained DSC curve according to JIS K7191.

The density of the (B) ethylene / α-olefin block copolymer used in the present invention is 1.00 g / cm ³ or less, preferably 0.90 g / cm ³ or less. When the density is 1.00 g / cm ³ or less, the toughness of the resulting polyamide resin composition can be improved.

  The blending amount of the (B) ethylene / α-olefin block copolymer used in the present invention is selected in the range of 1 to 100 parts by weight, preferably 3 to 50 parts by weight, per 100 parts by weight of the polyamide resin. It is. (B) If the blending amount of the ethylene / α-olefin block copolymer is too small, the toughness improving effect such as tensile elongation at break and impact strength is negligible, and if it is too large, the rigidity, heat resistance, inherently possessed by the polyamide resin, Chemical resistance is significantly impaired.

The polyethylene resin (C) used in the present invention preferably has a density in the range of 0.85 to 0.98 g / cm ³ and a flexural modulus of 50 to 1000 MPa, and the flexural modulus is preferably 100 MPa to 500 MPa. Here, the flexural modulus is a value measured in accordance with ISO178 using a molded product molded in accordance with ISO294-1. If the flexural modulus is less than 50 MPa, the effect of improving the rigidity is negligible, and if it is 1000 MPa or more, the impact resistance decreases. The polyethylene used in the present invention is made of other monomers, for example, α-olefins such as propylene, butene-1, pentene, 4-methylpentene-1, hexene, octene and decene, butadiene, Dienes such as isoprene, cycloolefins such as cyclopentene, cyclohexene and cyclopentadiene, and acrylates such as methyl acrylate, ethyl acrylate and butyl acrylate may be copolymerized.

  The range of 1-50 weight part is selected with respect to 100 weight part of polyamide resin, and, as for the compounding quantity of (C) polyethylene resin used for this invention, Preferably it is 10-30 weight part. (C) By blending a polyethylene resin, it is possible to balance rigidity, toughness and fluidity.

  The (D) α, β unsaturated carboxylic acid or derivative thereof used in the present invention can cause a graft reaction to the (B) ethylene / α-olefin block copolymer and improve the affinity of the entire system. A compound. Preferred examples include maleic acid, fumaric acid, glycidyl acrylate, glycidyl methacrylate, itaconic acid diglycidyl ester, citraconic acid diglycidyl ester, butenedicarboxylic acid diglycidyl ester, butenedicarboxylic acid monoglycidyl ester, maleic anhydride, anhydrous Itaconic acid, citraconic anhydride, maleic imide, itaconic imide, citraconic imide and the like, and glycidyl methacrylate, maleic anhydride, itaconic anhydride and maleic imide are particularly preferably used.

  The blending amount of the (D) α, β unsaturated carboxylic acid or derivative thereof used in the present invention is in the range of 0.01 to 20 parts by weight, preferably 0.03 to 15 parts by weight with respect to 100 parts by weight of the polyamide resin. Part range. If the blending amount is less than 0.01 parts by weight, the affinity and uniformity of the entire resin composition system to be formed is insufficient, which is not preferable. Conversely, if the blending amount is 20 parts by weight or more, an excessive graft reaction is caused. This is not preferable because the increase in viscosity and the decrease in fluidity occur due to the progress of.

  Moreover, it is preferable to add the radical generator used as the starting point of the graft reaction of (D) (alpha), (beta) unsaturated carboxylic acid or its derivative (s). Specific examples of the radical generator include benzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, t-butyl cumyl peroxide, cumene hydroperoxide, 2,5-dimethyl-2,5-di- Examples thereof include t-butylperoxyhexane and 2,5-dimethyl-2,5-di-t-butylperoxyhexyne-3.

  In the composition of the present invention, it is preferable to add a copper compound in order to improve long-term heat resistance within a range that does not impair the effects of the present invention. Specific examples of copper compounds include cuprous chloride, cupric chloride, cuprous bromide, cupric bromide, cuprous iodide, cupric iodide, cupric sulfate, nitric acid. Cupric, copper phosphate, cuprous acetate, cupric acetate, cupric salicylate, cupric stearate, cupric benzoate and inorganic copper halides and xylylenediamine, 2-mercaptobenzimidazole And copper compounds such as benzimidazole. Among these, monovalent copper halide compounds are preferable, and cuprous acetate, cuprous iodide and the like can be exemplified as particularly suitable copper compounds. It is also possible to add an alkali halide in combination with a copper compound. Examples of the alkali halide compound include lithium chloride, lithium bromide, lithium iodide, potassium chloride, potassium bromide, potassium iodide, sodium bromide and sodium iodide. Sodium chloride is particularly preferred.

  Moreover, it is preferable to add another component in the range which does not impair the effect of this invention. For example, antioxidants, heat stabilizers (hindered phenols, hydroquinones, phosphites, etc.), weathering agents (resorcinols, salicylates, benzotriazoles, benzophenones, hindered amines, etc.) Molds and lubricants (montanic acid and its metal salts, its esters, their half esters, stearyl alcohol, stearamide, various bisamides, bisureas and polyethylene waxes), pigments (cadmium sulfide, phthalocyanine, carbon black, etc.), dyes (nigrosine) Etc.), crystal nucleating agent (talc, silica, kaolin, clay, etc.), plasticizer (octyl p-oxybenzoate, N-butylbenzenesulfonamide, etc.), antistatic agent (alkyl sulfate type anionic antistatic agent, poly Oxyethylene Nonionic antistatic agents such as rubitan monostearate, betaine amphoteric antistatic agents, etc.), flame retardants (eg, hydroxides such as red phosphorus, melamine cyanurate, magnesium hydroxide, aluminum hydroxide, polyphosphorus) Ammonium acid, brominated polystyrene, brominated polyphenylene ether, brominated polycarbonate, brominated epoxy resin or a combination of these brominated flame retardants and antimony trioxide), and other polymers can be added.

  As a method of obtaining the polyamide resin composition of the present invention, in melt kneading, for example, when melt kneading with a twin screw extruder, (A) polyamide resin, (B) ethylene and α having 3 to 20 carbon atoms from the main feeder. Examples thereof include a method of supplying an ethylene / α-olefin block copolymer comprising an olefin, (C) a polyethylene resin, (D) an α, β unsaturated carboxylic acid or a derivative thereof.

  The method for molding the polyamide resin composition of the present invention is not particularly limited, and known methods such as injection molding, injection compression molding, press molding, and extrusion molding can be used. Injection molding and injection compression molding are preferred.

  The molded product obtained by molding the composition of the present invention is suitable for automobile parts and electrical / electronic parts because it is excellent in low gas property, heat resistance, impact resistance and rigidity during molding. This is effective when it is a molded product having. The hinge portion referred to here has a thinner shape than the peripheral portion, and is a portion where the molded product can be bent. Especially useful for clips, clamps and bands for bundling wires, cords and tubes.

  The molded products obtained in Examples and Comparative Examples were evaluated by the following methods.

(1) Tensile strength, tensile strain Test piece: A multipurpose test piece having a thickness of 4 mm was molded according to ISO 294-1.
Test conditions: Measurement was carried out according to ISO 527. Tensile speed 50 mm / min, between gauge points 115 mm.
Test atmosphere: Air temperature 23 ° C, humidity 50% RH
Measuring instrument: Universal testing machine 5581 manufactured by Instron Japan.

(2) Bending strength and flexural modulus Test piece: A multi-purpose test piece having a thickness of 4 mm was molded in accordance with ISO294-1.
Test conditions: Measurement was carried out according to ISO 178. Yield speed 2mm / min, span interval 64mm.
Test atmosphere: Air temperature 23 ° C, humidity 50% RH
Measuring instrument: Universal testing machine 5566 manufactured by Instron Japan.

(3) Charpy impact strength Test piece: A multipurpose test piece having a thickness of 4 mm was molded according to ISO294-1. An 80 × 10 × 4 mm test piece was cut from the center portion of the multipurpose test piece, and the obtained test piece was subjected to JISK7144 and notched to obtain an impact test piece.
Test conditions: Measurement was carried out according to ISO 179.
Test atmosphere: Air temperature 23 ° C, -30 ° C, humidity 50% RH
Measuring instrument: Impact tester TYPE6545 manufactured by CEAST.

(4) Deflection temperature under load Test piece: A multi-purpose test piece having a thickness of 4 mm was molded in accordance with ISO294-1.
Test conditions: Measurement was carried out by applying ISO75-2 and applying a load of 0.46 MPa.
Measuring instrument: HDT-TESTER manufactured by Toyo Seiki Co., Ltd.

(5) Hinge test Test piece: A test piece having a hinge portion having a length of 2 mm, a width of 10 mm, and a thickness of 0.35 mm at the center of a length of 80 mm, a width of 10 mm, and a thickness of 1 mm was molded.
Test conditions: The test piece was treated at −30 ° C. for 3 hours, then the hinge part was bent, and a test piece in which no cracks or cracks occurred on the surface was regarded as a good product. The test was conducted with 10 test pieces.
Non-defective product rate calculation method: Number of good products × 100/10 (number of tests).

(6) Weight loss by heating Test conditions: The pellets were weighed and treated again at 285 ° C. for 30 minutes, and weighed again to calculate the amount of reduction (%).
Calculation method: (weighed value after treatment−weighed value before treatment) × 100 / (weighed value before treatment).

  (A) Polyamide resin used in Examples and Comparative Examples (B) Ethylene / α-olefin block copolymer composed of ethylene and α-olefin having 3 to 20 carbon atoms, (C) polyethylene resin, (D ) The α, β unsaturated carboxylic acid or its derivative is as follows.

<Polyamide resin>
A1 Polyamide 66 resin: melting point 265 ° C., viscosity number 150 ml / g
A2 Polyamide 66/6 (97/3 wt%) resin: melting point 260 ° C., viscosity number 125 ml / g.

<Ethylene / α-olefin block copolymer composed of ethylene and α-olefin having 3 to 20 carbon atoms>
B1 ethylene / 1-octene block copolymer (Infuse 9107 manufactured by Dow Chemical Company, density 0.87 g / cm ³ , melting point 121 ° C., glass transition point −62 ° C.)
B2 ethylene / 1-octene block copolymer (Infuse 9500 manufactured by Dow Chemical Company, density 0.87 g / cm ³ , melting point 119 ° C., glass transition point −62 ° C.)
B3 ethylene / 1-octene block copolymer (Infuse 9807 manufactured by Dow Chemical Company, density 0.87 g / cm ³ , melting point 118 ° C., glass transition point −62 ° C.).

<Olefin-based random copolymer>
b1 (Comparative example) Ethylene / 1-butene random copolymer (Mitsui Chemicals, Inc., Toughmer A1050S, density 0.87 g / cm ³ , no melting point, glass transition point −64 ° C.)
b2 (Comparative Example) Ethylene / 1-propylene random copolymer (EP27 manufactured by JSR Corporation, density 0.88 g / cm ³ , unknown melting point, unknown glass transition point)
b3 (Comparative Example) Ethylene / 1-octene random copolymer (Dow Chemical Co. Engage 8100, density 0.87 g / cm ³ , no melting point, glass transition point −55 ° C.).

<Polyethylene resin>
C1 high-density polyethylene (manufactured by Prime Polymer Co., Ltd. Hi-Zex 1300J, density 0.96 g / cm ³ , melting point 134 ° C.)

<Α, β unsaturated carboxylic acid or derivative thereof>
D1 Maleic anhydride (CRYSTAL MAN AB manufactured by NOF Corporation).

  A radical generator (Perhexa 25B manufactured by NOF Corporation) was used as an E1 graft reaction accelerator.

Examples 1-4, Comparative Examples 1-4
Using a twin screw extruder ZSK-57 manufactured by Werner-Pfleiderer, ethylene / A made of (A) polyamide resin (B) ethylene and α-olefin having 3 to 20 carbon atoms from the main feeder with the composition shown in Table 1 α-Olefin block copolymer, (C) polyethylene resin, (D) α, β unsaturated carboxylic acid or derivative thereof are supplied, the resin melting temperature is 290 ° C., and the screw rotation is 200 rpm and the pellets are melt kneaded Turned into. The obtained pellets were vacuum-dried at 80 ° C. for 12 hours. Using the dried pellets, molding was performed under the conditions of a cylinder temperature of 290 ° C. and a mold temperature of 80 ° C. using an injection molding machine NEX1000 manufactured by Nissei Plastic Industry Co., Ltd. to obtain each test piece. The evaluation results are as shown in Table 1.

  From the results of Examples 1 to 4 and Comparative Examples 1 to 4, the polyamide resin composition of the present invention was excellent in rigidity, impact resistance, and heat resistance, and generated less gas during heating use or molding. .

Claims (7)

(A) 1 to 100 parts by weight of an ethylene / α-olefin block copolymer composed of ethylene and an α-olefin having 3 to 20 carbon atoms with respect to 100 parts by weight of the polyamide resin, (C) polyethylene A polyamide resin composition comprising 1 to 50 parts by weight of a resin and (D) 0.01 to 20 parts by weight of an α, β unsaturated carboxylic acid or a derivative thereof. Polyamide resin (A) is polycaproamide, polyhexamethylene adipamide, polycaproamide / polyhexamethylene adipamide copolymer, polyhexamethylene adipamide / polyhexamethylene terephthalamide copolymer and polyhexamethylene terephthalamide / poly The polyamide resin composition according to claim 1, wherein the polyamide resin composition is at least one selected from hexamethylene sebacamide copolymers. The polyamide resin composition according to claim 1 or 2, wherein the polyamide resin (A) has a viscosity number of 90 to 200 ml / g. The olefin of the ethylene / α-olefin block copolymer (B) is octene, the melting point is 100 ° C. or higher, and the glass transition point is −50 ° C. or lower. A polyamide resin composition as described above. The density of a polyethylene resin (C) is 0.85-0.98 g / cm < ³ >, The polyamide resin composition in any one of Claims 1-4 characterized by the above-mentioned. A molded article comprising the polyamide resin composition according to any one of claims 1 to 5. The molded article according to claim 6, wherein the molded article has a hinge portion.