JPS6411072B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to underhood parts for automobiles made of polyamide, which have good resistance to road surface antifreeze agents containing metal halide compounds such as calcium chloride and zinc chloride as main ingredients, and have excellent rigidity and heat resistance. Recently, there has been a noticeable trend in the automobile industry to replace conventional metal parts with resin for purposes such as weight reduction, rust prevention, and sound insulation to improve fuel efficiency. Among them, polyamide resin has characteristics such as excellent heat resistance, oil resistance, moldability, and toughness, so its application to automobile underhood parts is attracting attention. The term "underhood parts for automobiles" as used in the present invention refers to parts that are installed below the hood of a car, i.e., the bonnet or bottom plate, and are exposed to water splashed up from the road surface and chemicals such as anti-freeze agents. It is. Particularly suitable for parts inside the engine room, brake piping,
Fuel piping, etc. Specifically, cooling fan, radiator tank top and base, cylinder head cover, oil pan, timing chain cover, timing belt cover, gear box cover, water pump housing, steering column lock housing, fuel. These include filters, vapor canisters, brake reservoirs, engine compartment gears, valves, and connectors, electrical parts such as fastener clips, fuel pipes, vacuum pipes, hydraulic clutch hoses, air brake lines, and car cooler hoses. However, polyamides with a relatively high concentration of amide groups, such as nylon 6 and nylon 66, which are commonly used among polyamide resins, inherently have a strong affinity for inorganic metal salts such as calcium chloride and zinc chloride. Therefore, underhood parts for automobiles made of these materials have a serious drawback of being attacked by metal salts such as calcium chloride, magnesium chloride, and zinc chloride, and cracking occurs within a short period of time. In general, large amounts of antifreeze agents containing calcium chloride, magnesium chloride, etc. are sprayed on roads in cold regions to prevent road surfaces from freezing, especially in winter, but these inorganic metal salts are exposed to high temperature atmospheres. If it adheres to the underhood parts of a car, it will cause cracks in the parts, and there is a high risk of car accidents caused by this. Therefore, although automobile underhood parts made of materials such as nylon 6 and nylon 66 have excellent toughness and heat resistance, and are inexpensive, they do not have sufficient resistance to road deicing agents, which limits the expansion of their applications. Therefore, the emergence of a low-grade polyamide-based material with excellent road antifreeze properties is currently eagerly awaited. Therefore, the present inventors investigated polyamide-based underhood parts for automobiles that satisfy required properties such as resistance to road antifreeze agents, rigidity, toughness, heat resistance, and chemical resistance. An automobile underhood that has extremely excellent physical properties, and is made of a polyamide containing an aromatic component and maintaining crystallinity, or a mixture of the polyamide and a normal aliphatic polyamide, with an inorganic reinforcing material added thereto as necessary. It has been discovered that the material can be used as a material for parts. That is, the present invention provides (A) a crystalline product whose main constituents are at least one component selected from aliphatic lactams having 4 to 8 carbon atoms, amino acids, diamines, and dicarboxylic acids, and an aromatic component represented by the following formula. Polyamide or this and (B) aliphatic polyamide
The object of the present invention is to provide an automobile underhood part formed by molding a blend consisting of 100 parts by weight of a mixture of 80% by weight or less and 0 to 100 parts by weight of (C) an inorganic reinforcing material. where X, Y: (-CH ₂ ) _-n NH ₂ or (-CH ₂ ) _-o
COOH R: _C1 to _C4 alkyl group l: An integer of 0 to 4 m: An integer of 1 to 3 n: An integer of 0 to 2 The polyamide (A) used in the present invention is a fatty acid having 4 to 8 carbon atoms. At least one component selected from group lactams, amino acids, diamines and dicarboxylic acids, such as ε-caprolactam, tetramethylene diamine, hexamethylene diamine, adipic acid, etc., and an aromatic component represented by the above formula, such as para-aminomethylbenzoic acid, Melt polymerization is possible with main constituents such as para-aminoethylbenzoic acid, terephthalic acid, 2-methylterephthalic acid, 2,5-dimethylterephthalic acid, 2,5-dibromoterephthalic acid, paraxylylene diamine, etc., and it is also crystalline. It is a polyamide that maintains its properties. The other components are not particularly limited, and conventionally known polyamide-forming components can be used. Typical examples of these polyamides include copolymer polyamides of para-aminomethylbenzoic acid and ε-caprolactam or hexamethylenediamine adipate (nylon PAMBA/6, PAMBA/
66), copolymer of hexamethylene diamine terephthalate and ε-caprolactam or hexamethylene diamine adipate (nylon
6T/6, 6T/66), paraxylylenediamine
Copolymers of adipate and ε-caprolactam or hexamethylenediamine adipate (nylon PXD6/6, PXD6/66), etc.
It is also possible to use two or more types of polyamides in combination. All of the polyamides mentioned here are already well known, but their application to the field of automotive underhood parts and their resistance to metal halides such as calcium chloride, as well as their rigidity and Until now, it was not known at all that it had excellent effects such as heat resistance, toughness, and chemical resistance. In other words, the feature of the present invention is that even though the polyamide whose main constituents are a specific aliphatic component and an aromatic component has an amide group concentration (the number of amide groups relative to the number of constituent carbon atoms), it is not much different from ordinary nylon 6 or nylon 66. This material is based on the new finding that it has extremely good resistance to metal halides, and its distinctive feature lies in the application of this material to specific automotive underhood parts that take advantage of its properties. The manufacturing conditions for the crystalline polyamide (A) used here are not particularly limited, and the polymer can be obtained by appropriately combining normal pressure, increased pressure, and reduced pressure operations at a temperature of 200 to 350°C. Furthermore, there is no particular restriction on the degree of polymerization of the crystalline polyamide (A), and polyamides having a relative viscosity generally within the range of 1.7 to 4.5 can be arbitrarily selected. These (A) crystalline polyamides can be used alone, but other (B)
It can also be used as a mixture with up to 80% by weight of aliphatic polyamide. (B) Aliphatic polyamide used in the present invention is polycaproamide (nylon 6), polyhexamethylene adipamide (nylon 66), polyhexamethylene sebamide (nylon 610), polyhexamethylene dodecamide (nylon 612), polyundecamethylene adipamide (nylon 116), polyundecaneamide (nylon 11), polydodecanamide (nylon 12), and copolyamides thereof, and two or more of the above polyamides are used in combination. It is also possible. The degree of polymerization of the aliphatic polyamide (B) used here is not particularly limited, and polyamides having a relative viscosity generally within the range of 2.0 to 5.0 can be arbitrarily selected. Examples of the inorganic reinforcing material (C) used in the present invention include glass fiber, asbestos fiber, carbon fiber, calcium carbonate, talc, magnesium oxide, aluminum oxide, wollastenite, fine mica, granular glass, and potassium titanate whiskers. can. The underhood parts for automobiles of the present invention are made of (A) crystalline polyamide containing specific aliphatic components and aromatic components, or this and normal (B) aliphatic polyamide at 80% by weight or less, more preferably 75% by weight or less. mixture of
It can be obtained by molding a composition comprising 100 parts by weight of the inorganic reinforcing material (C) and 0 to 100 parts by weight, more preferably 0 to 90 parts by weight. Here, if the amount of (B) aliphatic polyamide used exceeds 80% by weight, the resistance to metal halides will noticeably decrease, making it impossible to obtain automobile underhood parts with excellent road antifreeze properties, and , is not preferable because it lacks heat resistance and the purpose of metal replacement cannot be achieved. Furthermore, if the amount of inorganic reinforcing material added to 100 parts by weight of polyamide exceeds 100 parts by weight, the toughness will rather decrease and the product will become brittle, impairing its function as an underhood part for automobiles, which is not preferable. Inorganic reinforcement is not necessary especially when obtaining flexible parts. (A) component polyamide, (B) component polyamide and (C)
There are no particular restrictions on the method of blending the inorganic reinforcement, and for example, polyamide pellets, powder, pieces, etc. and the inorganic reinforcement are uniformly mixed in a high-speed stirrer, and then melt-kneaded in an extruder with sufficient kneading capacity. Alternatively, methods such as dry blend injection or extrusion molding can be used. The underhood parts for automobiles of the present invention are molded by subjecting the above-mentioned polyamide compound to molding methods generally known for thermoplastic resins such as injection molding, extrusion molding, blow molding, and vacuum molding, but in particular injection molding or extrusion. Cooling fans, radiator tanks, cylinder head covers, oil pans, gears, valves, brake piping, fuel piping, and other tubes and pipes obtained by molding.
Other exhaust gas system parts, electrical system parts such as connectors, sheets, etc. are useful. Note that the molded parts obtained in this way can also be subjected to secondary processing such as painting, vapor deposition, and adhesion. In addition, the automotive underhood parts of the present invention may contain other ingredients, such as pigments, dyes, heat resistant agents, antioxidants, weathering agents, lubricants, crystal nucleating agents, antistatic agents, as long as they do not impair their moldability or physical properties. Agents, plasticizers, other polymers, etc. can be added and introduced. In particular, when the present inventors have already proposed polymers with excellent road antifreeze properties, such as ethylene-based ionomer resins, which have high practical value when added for the purpose of imparting more flexibility, You can get hood parts. The present invention will be explained in further detail by giving examples below. The physical properties of the test pieces described in Examples were measured in accordance with the following method. (1) Relative viscosity: JIS K6810 (2) Tensile test: ASTM D638 (3) Bending test: ASTM D790 (4) Izot impact test: ASTM D256 (5) Metal halide resistance test: Underhood molded product heated to 90℃ After soaking in warm water for 24 hours,
The molded product was left in a gear oven at 100°C, and one cycle consisted of spraying a 50% calcium chloride solution in the form of water droplets every hour, and the number of cycles until the molded product cracked was measured. (6) Crystallinity: When the temperature is raised and lowered at 20℃/min using Perkin Elmer's DSC1B type, the appearance of a clear melting endothermic peak (melting point) and crystallization exothermic peak (crystallization point) Crystallinity was evaluated. Example 1 Relative viscosity 2.50, melting point 270°C, crystallization temperature obtained by melt polymerization of a mixture of 30 parts by weight of an equimolar salt of hexamethylenediamine/terephthalic acid and 70 parts by weight of an equimolar salt of hexamethylenediamine/adipic acid. 225℃
Add 45 parts by weight of chopped strand glass fiber TP-24 manufactured by Nippon Glass Fiber Co., Ltd. to 100 parts by weight of nylon 6T/66 (30/70) copolymer and mix uniformly with a high-speed stirrer. The mixture was melt-kneaded using an extruder with a diameter of 65 mm and then pelletized. After drying this pellet in vacuum, it was molded using an injection molding machine at a cylinder temperature of 290°C and a mold temperature of 80°C to form a physical property test piece according to ASTM standards, with a length of 450 mm and a width of
A box-shaped cylinder head cover of 200 mm, height 80 mm, and wall thickness 3.5 mm was molded. Using the molded piece obtained here, we examined its mechanical properties and resistance to metal halides.
It has been found that it exhibits extremely excellent properties as shown below. Tensile strength 1800 Kg/cm ² Bending strength 2600 Kg/cm ² Flexural modulus 108000 Kg/cm ² Izot impact strength 9.0 Kg・cm/cm Notch Resistance to calcium chloride No cracking after 10 cycles or more of testing. Example 2 Nylon with a relative viscosity of 2.90 obtained by melt polymerizing equimolar salts of hexamethylene diamine and adipic acid
66: 50% by weight and nylon 6T used in Example 1/
66 (30/70) copolymer: After adding 45 parts by weight of the same glass fiber as in Example 1 to 100 parts by weight of a 50% by weight mixture, kneading with an extruder and injection molding were performed in the same manner as in Example 1. A physical property test piece and a box-shaped cylinder head cover were prepared according to ASTM standards. When the mechanical properties and resistance to metal halides of the molded piece obtained here were examined, it was found that it exhibited extremely excellent properties as shown below. Tensile strength 1700 Kg/cm ² Bending strength 2500 Kg/cm ² Flexural modulus 92000 Kg/cm ² Izot impact strength 9.5 Kg・cm/cm Notch Calcium chloride resistance 10 cycles or more Comparative example 1 Nylon 66 used in Example 2 When examining the calcium chloride resistance of a cylinder head cover obtained by injection molding in the same manner as in Example 1 by mixing 100 parts by weight of glass fiber with 45 parts by weight of glass fiber, it was found that the molded product improved in just the first cycle. Numerous cracks appeared on the entire surface. Example 3 Nylon 12 with a relative viscosity of 2.40 obtained by melt polymerizing ω-laurolactam: 60% by weight and nylon 6T/66 (30/70) copolymer used in Example 1: 40% by weight
After adding 45 parts by weight of the same glass fiber as in Example 1 to 100 parts by weight of the mixture, kneading in an extruder and injection molding were carried out in the same manner as in Example 1 to obtain physical property test pieces according to ASTM standards and a box-shaped cylinder head cover. was prepared. When the mechanical properties and resistance to metal halides of the molded piece obtained here were examined, it was found that it exhibited extremely excellent properties as shown below. Tensile strength 1600 Kg/cm ² Bending strength 2300 Kg/cm ² Flexural modulus 81000 Kg/cm ² Izot impact strength 10.2 Kg cm/cm Notch Calcium chloride resistance 10 cycles or more Comparative example 2 Nylon 12 used in Example 3 : 100 parts by weight and 45 parts by weight of glass fiber were mixed and injection molded in the same manner as in Example 1. The physical properties of the test piece were as follows, and the strength and rigidity were unsatisfactory as a metal substitute material. It was hot. Bending strength 1400 Kg/cm ² Flexural modulus 43000 Kg/cm ² Examples 4 to 10 Obtained by performing the same operation as in Example 1, changing the type of polyamide, the type of inorganic reinforcing material, the blending amount, etc. The characteristics of the test piece and underhood parts were investigated and the results shown in Table 1 were obtained. It has been found that molded articles having extremely excellent properties can be obtained in all cases shown in Table 1.

[Table] Example 11 Relative viscosity 2.60, melting point 257 obtained by melt polymerizing a mixture of 60 parts by weight of equimolar salt of hexamethylene diamine terephthalic acid and 40 parts by weight of ε-caprolactam.
℃, Nylon 6T/6 (60/40) with crystallization temperature 182℃
A homogeneous mixture of 80% by weight copolymer and 20% by weight nylon 116 with a relative viscosity of 2.75 obtained by melt polymerizing equimolar salts of undecamethylene diamine and adipic acid was fed to a tube extruder with a diameter of 45 mm. ,
By extruding it into a cylindrical shape at 270℃ through an internal pressure tube forming die and cooling it in 5℃ water through a sizing plate, it is made into a cylinder with an outer diameter of 4.8mm and a wall thickness of 0.6mm.
A tube molded product was obtained. After treating the tube obtained here in 80℃ hot water for 24 hours, it was bent to a minimum inner bending radius of 10mm.
A model test of road antifreeze properties was conducted by immersing it in a 50% zinc chloride aqueous solution at 23℃.
Even after 200 hours, no cracks appeared at all. Example 12 The nylon 6T/66 (35/65% by weight) copolymer used in Example 4 was heated to a cylinder temperature using an injection molding machine.
295℃, mold temperature 70℃, length 20mm, width 10mm,
A box-shaped connector with a height of 15 mm and 10 wiring holes was molded. When the calcium chloride resistance of the molded product obtained here was examined, it showed resistance to 8 cycles and exhibited excellent properties.

Claims (1)

[Scope of Claims] 1 (A) The main constituents are at least one component selected from aliphatic lactams having 4 to 8 carbon atoms, amino acids, diamines, and dicarboxylic acids, and aromatic components represented by the following formula. An underhood part for an automobile formed by molding a blend consisting of 100 parts by weight of a crystalline polyamide or a mixture thereof with (B) 80% by weight or less of an aliphatic polyamide and (C) 0 to 100 parts by weight of an inorganic reinforcing material. where X and Y: ( _-CH2 ) _{-nNH2 or} (-
CH ₂ ) _-o COOH R: C ₁ to C ₄ alkyl group l: An integer of 0 to 4 m: An integer of 1 to 3 n: An integer of 0 to 2.