JP2010031210A - Polyamide resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyamide resin composition that has excellent flowability during molding and suppresses reduction in mechanical properties by contact with a nonfreezing fluid especially for long time as much as possible and a molded article comprising the polyamide resin composition. <P>SOLUTION: The polyamide resin composition is prepared by mixing 100 pts.wt. of a polyamide resin (A) with 1-20 pts.wt. of a polyamide oligomer (B) having the number of carbon atoms per amide group of ≥15 and ≤30 and a number-average molecular weight of ≥2,000 and ≤9,000. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polyamide resin composition and a molded article comprising the same, and more specifically, is excellent in fluidity at the time of molding, and an aqueous solution containing a polyhydric alcohol such as warm water or ethylene glycol (hereinafter also referred to as “antifreeze”). The present invention relates to a polyamide resin composition having good durability and strength under contact, and a molded product comprising the same.

  Polyamide resins are excellent in mechanical properties such as tensile and bending strength and elastic modulus, and have good heat resistance and chemical resistance, and are used in many fields such as precision machine parts and structural materials. In the fields of automobiles, architecture, and civil engineering, metal parts are being made of resin to reduce weight and streamline assembly. Among these, glass fiber reinforced polyamide resin has excellent heat resistance, oil resistance, and toughness, and is widely used as a material for parts that come into contact with antifreeze.

  However, in recent years, improvement in fluidity has been demanded as a material to be used in order to cope with the reduction in thickness of molded products accompanying the modularization and weight reduction of large automobile parts. On the other hand, it is known that the flowability is improved by mixing a polyamide resin with a low molecular weight polyamide oligomer, and various studies have been made so far.

Patent Document 1 proposes that a low molecular weight polyamide oligomer having a number of carbon atoms per amide group of less than 15 and a number average molecular weight of 3000 or less is mixed with a polyamide resin for the purpose of good flow. Patent Document 2 proposes mixing a low molecular weight polyamide oligomer having less than 10 carbon atoms per amide group with a polyamide resin for the purpose of good flow. Patent Document 3 proposes mixing a polyamide resin with a low molecular weight polyamide oligomer having a carbon atom number per amide group of less than 10 and a melting point of 280 ° C. for the purpose of good flow. Patent Document 4 proposes mixing an oligomer whose precursor is phenol with a polyamide resin for the purpose of good flow. However, although these methods certainly improve the fluidity compared to the polyamide resin alone, there are drawbacks such as brittleness and easy cracking, and since the number of carbon atoms per amide group is small, antifreeze resistance is required. When used as a member, it was not sufficient. Patent Document 5 proposes that a low molecular weight polyamide oligomer obtained by condensation polymerization of a polymerized fatty acid, an aliphatic monocarboxylic acid having 1 to 4 carbon atoms, polyamine and polylactone is used for printing ink.
JP 2004-107576 A Japanese Patent Laid-Open No. 5-194441 JP-T-2006-510780 JP 2006-52411 A Japanese Patent Laid-Open No. 10-330669

  The present invention provides a polyamide resin composition having excellent fluidity at the time of molding, particularly capable of suppressing deterioration of mechanical properties due to contact with antifreeze for a long time, and a molded article comprising the polyamide resin composition. The purpose is to provide.

The present invention employs the following means as a result of intensive studies to solve the above problems.
(1) Polyamide resin (A) 1 to 20 parts by weight of polyamide oligomer (B) having 15 to 30 carbon atoms and 2,000 to 9000 number average molecular weight per 100 parts by weight of amide group A polyamide resin composition,
(2) The polyamide resin of (1), wherein the polyamide resin (A) of (1) is blended in an amount of 5 to 100 parts by weight of the inorganic filler (C),
(3) The polyamide resin composition of (1) or (2), wherein the polyamide resin (A) of (1) has a viscosity number of 90 to 150 ml / g,
(4) The polyamide resin composition according to any one of (1) to (3), wherein the polyamide resin of (1) is hexamethylene sebacamide and / or hexamethylene dodecamide,
(5) The polyamide resin composition according to any one of (1) to (4), wherein the polyamide oligomer (B) of (1) has a melting point of 80 to 130 ° C.
(6) A molded product formed by molding the polyamide resin composition according to any one of (1) to (5),
Is to provide.

  The polyamide resin composition of the present invention and a molded product comprising the same have good flowability at the time of molding, and particularly have good durability and strength even under prolonged contact with warm water or antifreeze. Therefore, it can be suitably used as a hot water circulation device such as a water pump that is a component in an automobile engine room, floor heating that performs floor heating, and road heating that prevents freezing of a road surface in a cold region.

  The present invention will be described in detail below.

  Examples of the polyamide resin (A) used in the present invention include a ring-opening polymer of cyclic lactam, a polycondensation product of aminocarboxylic acid, a polycondensation product of dibasic acid and 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 / polydodecanamide copolymer (nylon 6T / 12), polyhexamethylene adipamide / polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (nylon 66 / 6T) / 6I), polyxylene adipamide (nylon XD6), polyhexamethylene terephthalamide / poly-2-methylpentamethylene terephthalamide copolymer (na Ron 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 610 and nylon 612.

  As the degree of polymerization of the polyamide resin (A) used here, the viscosity number measured according to ISO307 using 96% sulfuric acid as a solvent is in the range of 90 to 150 ml / g in terms of mechanical properties and fluidity. It is preferable that there is a thing of 100-120 ml / g especially. The polymerization method of the polyamide resin (A) 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.

  A copper compound is preferably added to the polyamide resin (A) used in the present invention in order to improve long-term heat resistance. 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, inorganic copper halide 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. The addition amount of the copper compound is usually preferably 0.01 to 2 parts by weight and more preferably 0.015 to 1 part by weight with respect to 100 parts by weight of the polyamide resin. If the amount added is too large, liberation of metallic copper occurs during melt molding, and the value of the product is reduced by coloring. In the present invention, an alkali halide can be added 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.

  In the present invention, the polyamide oligomer (B) used for improving fluidity is obtained by condensation polymerization of a polymerized fatty acid and a polyamine. The number of carbon atoms per amide group is 15 to 30, and the number average molecular weight is 15 to 30. Polymerized fatty acids and polyamines that are 2,000 to 9000 are used.

As the polymerized fatty acid constituting the polyamide oligomer (B) in the present invention, for example, an unsaturated fatty acid such as oleic acid or linoleic acid or a lower alkyl ester thereof (1 to 3 carbon atoms) is polymerized and then purified by distillation. The following composition, also called dimer acid, can be mentioned (numerical value is% by weight).
Monobasic acid having 18 carbon atoms: 0 to 15% (preferably 0 to 10%)
C36 dibasic acid: 60-99% (preferably 70-99%)
Tribasic acid having 54 carbon atoms: 0 to 30% (preferably 0 to 20%)

  Examples of the polyamine constituting the polyamide oligomer (B) in the present invention include aliphatic polyamines, alicyclic polyamines, and aromatic polyamines. Examples of the aliphatic polyamine include ethylenediamine, diethylenetriamine, propylenediamine, iminobispropylamine, hexamethylenediamine, decamethylenediamine, and 2-methylpentamethylenediamine. Examples of the alicyclic polyamine include isophorone diamine, cyclohexylene diamine, and diaminocyclohexane. Aromatic polyamines include diaminophenylmethane and xylylenediamine. Of these polyamines, ethylenediamine is particularly preferred.

  In the present invention, the polyamide oligomer (B) is obtained by condensation polymerization of a polymerized fatty acid and a polyamine. In some cases, an aliphatic monocarboxylic acid having 1 to 4 carbon atoms and a polylactone are added to the polymerized fatty acid and polyamine for condensation. Polyamide oligomers obtained by polymerization may be used.

  Examples of the aliphatic monocarboxylic acid having 1 to 4 carbon atoms include formic acid, acetic acid, propionic acid and butyric acid, and these can be used alone or in admixture at any ratio. If necessary, a part of the aliphatic monocarboxylic acid having 1 to 4 carbon atoms is replaced with a linear or unsaturated fatty acid having 5 or more carbon atoms, a mixed fatty acid obtained from natural fats and oils, an aromatic monocarboxylic acid, or the like. May be.

  Examples of polylactones include β-propiolactone, γ-butyrolactone, δ-valerolactone, β-methyl-δ-valerolactone, ε-caprolactone, and polylactones derived from these lactones. The polylactone has at least two functional groups selected from a hydroxyl group and a carboxyl group as a terminal group, and has a number average molecular weight of usually 2000 or less, preferably 1000 or less. Among the above lactones, ε-caprolactone, δ-valerolactone, and β-methyl-δ-valerolactone are preferable. Among the polylactones, preferred are ring-opening addition polymerizations of low molecular diols (ethylene glycol, diethylene glycol, neopentyl glycol, etc.) and one or more of ε-caprolactone, δ-valerolactone, and β-methyl-δ-valerolactone. The polylactone diol obtained by the reaction is particularly preferable.

  The melting point of the polyamide oligomer (B) of the present invention is preferably 80 to 130 ° C, more preferably 100 to 115 ° C. The melting point was measured by DSC method. The number average molecular weight is 2000 to 9000, preferably 3000 to 7000. The molecular weight was calculated by GPC analysis using α-chloronaphthalene or hexafluoroisopropanol as a solvent. The acid value (JIS K0070-1966) is 25 or less, preferably 20 or less, and the total amine value (ASTM D-2073-66) is usually 7 or less, preferably 5 or less. Here, the acid value means an acid value of a component obtained by combining an unneutralized amino group-containing compound and the organic acid used for neutralization.

  The polyamide oligomer (B) of the present invention can be produced by the same method as the synthesis method of ordinary polymerized fatty acid-based polyamide resin. The reaction temperature of the condensation polymerization reaction is usually 160 to 250 ° C, preferably 180 to 230 ° C. The reaction is preferably performed in an inert gas such as nitrogen gas in order to prevent coloring, and at the end of the reaction, the reaction may be performed under reduced pressure in order to promote the completion of the reaction or the removal of volatile components. The equivalence ratio (carboxyl group / amino group) of the carboxylic acid component and the amine component in the synthesis of the polyamide oligomer is usually (0.7 to 0.97) / 1, preferably (0.75 to 0.95) / 1.

  In the present invention, the blending ratio of the polyamide oligomer (B) needs to be 1 to 20 parts by weight with respect to 100 parts by weight of the polyamide resin (A) of the present invention. Preferably it is 3-15 weight part. If the amount is less than 0.1 parts by weight, there is a problem that sufficient fluidity cannot be obtained. If the amount exceeds 20 parts by weight, the mechanical properties deteriorate.

  In the present invention, an inorganic filler (C) is preferably blended in order to improve the mechanical strength of the polyamide resin composition. Although it does not specifically limit as an inorganic filler (C) used by this invention, Fillers, such as fibrous form, plate shape, powder form, a granular form, can be used. Specifically, glass fibers, PAN-based and pitch-based carbon fibers, stainless steel fibers, metal fibers such as aluminum fibers and brass fibers, organic fibers such as aromatic polyamide resins, gypsum fibers, ceramic fibers, asbestos fibers, zirconia fibers, Alumina fiber, silica fiber, titanium oxide fiber, silicon carbide fiber, rock wool, potassium titanate whisker, silicon nitride whisker, etc., whisker-like filler, wollastonite, selenite, kaolin, mica, clay, bentonite, asbestos, Silicate silicates such as talc, alumina silicate, swellable layered silicates such as montmorillonite, synthetic mica, metal oxides such as alumina, silicon oxide, magnesium oxide, zirconium oxide, titanium oxide, iron oxide, calcium carbonate, magnesium carbonate, Dolomide Which carbonate, calcium sulfate, sulfates such as barium sulfate, glass beads, ceramic beads, boron nitride, silicon carbide, and a non-fibrous fillers such as calcium phosphate and silica. In the above filler, PAN-based carbon fibers are preferably used when glass fibers and conductivity are required. The type of glass fiber is not particularly limited as long as it is generally used for reinforcing a resin, and can be selected from, for example, a long fiber type, a short fiber type chopped strand, a milled fiber, or the like. Moreover, said filler can also be used in combination of 2 or more types. Although there is no length restriction, a chopped strand of 0.1 to 6.0 mm is preferable, and a fiber diameter of 5 to 20 μm is preferable.

  In addition, surface treatment using a known coupling agent (for example, silane coupling agent, titanate coupling agent, etc.) or other surface treatment agent provides better mechanical strength and antifreeze resistance. This is preferable. It is preferable that the ratio of a silane coupling agent contains 0.1-2.0 weight part with respect to 100 weight part of polyamide resin (A) of this invention. If it is less than 0.1 part, a sufficient reinforcing effect cannot be obtained, and if it exceeds 2.0 part, gas is generated during molding and the surface appearance deteriorates, which is not preferable. When melt-kneading polyamide and glass fiber, the glass fiber is coated or focused with a thermoplastic resin such as ethylene / vinyl acetate copolymer or a thermosetting resin such as epoxy resin for the purpose of improving workability. Also good.

  In the present invention, the proportion of the inorganic filler (C) is required to be 5 to 100 parts by weight with respect to 100 parts by weight of the polyamide resin (A) of the present invention. If the amount is less than 5 parts by weight, there is a problem that sufficient mechanical strength cannot be obtained. If the amount exceeds 100 parts by weight, the surface appearance at the time of molding deteriorates.

  In the composition of the present invention, other components such as antioxidants and heat stabilizers (hindered phenol-based, hydroquinone-based, phosphite-based and substituted products thereof), weather resistance, etc. are within the range not impairing the effects of the present invention. Agents (resorcinol, salicylate, benzotriazole, benzophenone, hindered amine, etc.), mold release agents and lubricants (montanic acid and its metal salts, esters, half esters, stearyl alcohol, stearamide, various bisamides, bisureas) And polyethylene wax), pigments (cadmium sulfide, phthalocyanine, carbon black, etc.), dyes (nigrosine, etc.), crystal nucleating agents (talc, silica, kaolin, clay, etc.), plasticizers (octyl p-oxybenzoate, N- Butylbenzenesulfonamide), antistatic (Alkyl sulfate type anionic antistatic agents, nonionic antistatic agents such as polyoxyethylene sorbitan monostearate, betaine amphoteric antistatic agents, etc.), flame retardants (eg red phosphorus, melamine cyanurate, hydroxylation) Hydroxides such as magnesium and aluminum hydroxide, ammonium polyphosphate, brominated polystyrene, brominated polyphenylene ether, brominated polycarbonate, brominated epoxy resins or combinations of these brominated flame retardants with antimony trioxide), etc. The polymer can be added.

  As a method for obtaining the polyamide resin composition of the present invention, in melt kneading, for example, in the case of melt kneading with a twin screw extruder, the polyamide resin (A) and the polyamide oligomer (B) are supplied from the main feeder, and an inorganic filler ( The method of supplying C) from the side feeder of an extruder is mentioned.

  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.

  Here, the use of the molded article of the polyamide resin composition of the present invention can be suitably used as a water pump that is a component in an automobile engine room, floor heating that performs floor heating, and prevention of freezing of road surfaces in cold regions. A warm water circulation device such as road heating can be mentioned. The hot water circulation device refers to a device for adjusting the antifreeze liquid to 30 ° C. to 60 ° C. and circulating it through a pipe. The hot water circulation device consists of a heat exchanger heated by a heat source, a storage tank that stores hot water, and a circulation pump that forcibly circulates hot water, and each is connected by a pipe to circulate the hot water. A certain temperature can be maintained under the road.

  For example, the pipe of a hot water circulation device such as floor heating or road heating circulates an aqueous solution containing polyhydric alcohol such as hot water or ethylene glycol, and contains polyhydric alcohol adjusted to 30 ° C to 120 ° C. It is preferable that an aqueous solution or water adjusted to 30 ° C. to 90 ° C. is passed. Since the aqueous solution containing polyhydric alcohol has an effect as an antifreeze, it can be suitably used as a hot water circulation device used in cold regions.

  Such polyhydric alcohols include ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,5-pentanediol, hexylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, Examples thereof include polyethylene glycol, polypropylene glycol, glycerin and the like, and ethylene glycol and propylene glycol, all of which are effective, can be preferably used.

  Hereinafter, although an example is given and the present invention is explained in detail, the gist of the present invention is not limited only to the following examples.

Evaluation method (1) Antifreeze resistance Tensile strength after treating a test piece in a 50% aqueous solution of long life coolant (LLC) at 130 ° C. for 1000 hours was measured as a measure of antifreeze resistance.
Test piece: A square plate of 80 × 80 × 3 mm obtained by injection molding is ½ size of ASTM: D638 type I (full length: 80 mm, parallel part length: 30 mm, parallel part width: 5 mm, thickness 3 mm) A test piece in the direction perpendicular to the flow direction was obtained by cutting the material.
Measuring instrument: Universal testing machine 5581 manufactured by Instron Japan
Test conditions: tensile speed 2 mm / sec, distance between chucks 50 mm
Test atmosphere: Air temperature 23 ° C and 130 ° C, humidity 50%

(2) Fluidity Using a Nissei Plastic Industrial Injection Molding Machine NEX1000, a spiral flow measuring mold having a spiral shape with a width of 10 mm, a thickness of 2 mm and a total length of 600 mm, a molding temperature of 250 ° C., an injection pressure of 60 MPa, a mold temperature of 80 Injection molding was performed under the condition of ° C., and the distance flowing through the mold was measured, which was used as an indicator of fluidity. It shows that fluidity | liquidity is so favorable that the flow length which shows the distance to flow is long.

(3) Amino terminal group amount 0.5 g of the substance to be measured was precisely weighed and dissolved in 25 cc of a phenol / ethanol mixed solvent (83.5: 16.5, volume ratio), and then titrated with a 0.02N aqueous hydrochloric acid solution. .

Raw materials The polyamide resin, polyamide oligomer, glass fiber, and polyamide 66 oligomer used in Examples and Comparative Examples are as follows.

<Polyamide resin>
Polyamide 610 resin having a melting point of 215 ° C., a viscosity number of 108 ml / g, and an amino terminal group amount of 3.2 × 10 ⁻⁵ mol / g.

<Polyamide oligomer>
(Polyamide oligomer): “Polymide S-40E” manufactured by Sanyo Chemical Industries, Ltd.
A polyamide oligomer having 18 carbon atoms per amide group, a number average molecular weight of 4500, a melting point of 110 ° C., an acid value of 5 and a total amine value of 5.

<Inorganic filler>
(Glass fiber): “T292H” manufactured by Nippon Electric Glass Co., Ltd.

<Polyamide 66 oligomer>
An autoclave with a pressure resistance of 30 kg / cm 2 is charged with 600 parts by weight of hexamethylenediamine, 584 parts by weight of adipic acid, 682 parts by weight of behenic acid, and 1000 parts by weight of water, and heated to 180 ° C. under hermetically pressurized atmosphere. After reaching 180 ° C., the pressure was released while maintaining the tube temperature, and the tube pressure was changed to atmospheric pressure over 3 hours. Thereafter, the reaction was continued for 1 hour under a nitrogen stream while gradually raising the temperature. After cooling, the contents were pulverized to obtain a polyamide 66 oligomer. A polyamide 66 oligomer having 5 carbon atoms per amide group and a number average molecular weight of 1800.

Examples 1-3, Comparative Examples 1-3
Using the twin screw extruder TEX-44 manufactured by Nippon Steel Works, the ratio of the materials shown below is used to supply polyamide resin from the upstream supply port, and glass fiber from the downstream supply port. Then, the mixture was melt-kneaded and pelletized at a resin melting temperature of 260 ° C. and a screw rotation of 200 rpm. The obtained pellets were vacuum-dried at 80 ° C. for 12 hours. Using the dried pellets, a square plate of 80 × 80 × 3 mm is formed at a cylinder temperature of 290 ° C. and a mold temperature of 80 ° C. with a Nissei Plastic Industrial Injection Molding Machine NEX1000, and the square plate is cut. A test piece compliant with the ASTM method in the direction perpendicular to the flow was obtained. The test piece was evaluated for antifreeze resistance. The evaluation results are as shown in Table 1.

  From the results of the comparative examples with Examples 1 to 3 and Comparative Examples 1 to 3, the resin of the present invention has both good fluidity and antifreeze resistance.

Claims (6)

1 to 20 parts by weight of polyamide oligomer (B) having 15 to 30 carbon atoms and 2,000 to 9000 number average molecular weight per 100 parts by weight of polyamide resin (A) Polyamide resin composition. The polyamide resin composition according to claim 1, wherein 5 to 100 parts by weight of the inorganic filler (C) is blended with 100 parts by weight of the polyamide resin (A). The polyamide resin composition according to claim 1 or 2, wherein the polyamide resin (A) has a viscosity number of 90 to 150 ml / g. The polyamide resin composition according to any one of claims 1 to 3, wherein the polyamide resin (A) is hexamethylene sebacamide and / or hexamethylene dodecamide. The polyamide resin composition according to any one of claims 1 to 4, wherein the polyamide oligomer (B) has a melting point of 80 to 130 ° C. A molded product formed by molding the polyamide resin composition according to claim 1.