KR20050121123A - The composition of polyamide resin for micrcellular foaming prcess - Google Patents

Abstract

The present invention relates to a polyamide resin composition for ultra-foaming molding, and more particularly, to a polyamide polymer (polyamide 6) or a polyamide polymer alloy (polyamide 66), glass fiber, amorphous polyamide resin and When the modified alkyl ester compound is mixed in a certain ratio, ultra-foam foam molding improves mechanical properties such as stiffness, heat resistance, and shrinkage rate, and enables control of viscosity and solidification rate to improve non-uniform shell formation, which can be applied to automobile parts. A polyamide resin composition for foam molding.

Description

The composition of polyamide resin for micrcellular foaming prcess}

The present invention relates to a polyamide resin composition for ultra-foaming molding, and more particularly, to a polyamide polymer (polyamide 6) or a polyamide polymer alloy (polyamide 66), glass fiber, amorphous polyamide resin and When the modified alkyl ester compound is mixed in a certain ratio, ultra-foam foam molding improves mechanical properties such as stiffness, heat resistance, and shrinkage rate, and enables control of viscosity and solidification rate to improve non-uniform shell formation, which can be applied to automobile parts. A polyamide resin composition for foam molding.

Recently, with the development of the IT industry as well as the automotive industry, research on plastic substitution of electric / electronic parts has been actively conducted in terms of light weight, low manufacturing cost, improved design freedom, and simplified manufacturing process. As a plastic substitute material, polyamide resin is widely used in automobiles and industries as it is excellent in stiffness, toughness, abrasion resistance, chemical resistance, and reinforcing agent addition effect among mechanical properties. However, the polyamide resin has poor dimensional stability due to moisture absorption, and has a disadvantage of poor impact strength and high mold shrinkage because it is a crystalline polymer, and studies to improve it have been actively conducted. Representative technologies for polymerizing alloys or adding inorganic materials have been proposed. The products used in this improvement include engine covers, fans and shrouds, radiator head tanks, air in take manifolds, and timing-belts for automobile parts. It is applied to housings and covers, such as a cover, various tanks, and ducts.

As is known, in order to increase the stiffness, heat resistance and dimensional stability of polyamide resin, fibrous inorganic fillers such as glass fiber, glass bead, talc (talc, Talc), mica (mica, Method of adding minerals such as minerals of inorganic particles such as Mica, clay, calcium carbonate (CaCO3), ollastonite, barium sulfate, etc. Is being used.

In a similar manner, there is a hybrid reinforcement method in which an inorganic filler or particles are added in a solid state alone or in hybrid form when polyamide is produced, and then injection molded. The above method is well known as a technique of simultaneously using fillers and particles in order to reduce shrinkage variation in the longitudinal and transverse directions of the product after injection molding.

In addition, in order to further improve mechanical properties, a technique of using a third additive or introducing a coupling agent such as a silane compound into a inorganic material is mainly used.

The above methods are proposed in US Pat. Nos. 4,131,591 and 3,843,591 and Japanese Patent Laid-Open Nos. 6-047063 and 5-817440.

Japanese Patent Application Laid-Open No. 8-7235652 proposes an alloy with a polyphenylene-based resin or an unsaturated carboxylic acid-containing rubber component, and Korean Patent Laid-Open Publication No. 1994-0014663 proposes a technique of blending with a polyolefin and an acid functional rubber. It was.

Japanese Patent Laid-Open No. 5-628241, Japanese Patent Laid-Open No. Hei 2-24354 and Japanese Patent Laid-Open No. Hei 6-234896 blend polyamide and polypropylene resin, but use carboxylic acid as a compatibilizer and reinforce glass fibers therein. Japanese Patent Application Laid-open No. Hei 4-151962 and U.S. Patent No. 4,613,647 have suggested the introduction of aromatic polyamides in glass fiber reinforcement in polyamide resins.

In addition, it is introduced as a resin composition reinforced with glass fiber alone or in combination with minerals. In the case of Japanese Patent Application Laid-Open No. 6-0108463, a coupling agent was introduced to improve the impact strength, and in the case of Japanese Patent Publication No. 6-047061, glass was introduced. A composite reinforcement of fiber and clay was proposed, and Japanese Patent Laid-Open No. 59-133249 also introduced a technique of adding glass fiber and a plasticizer. In addition, Japanese Patent Laid-Open No. 58-201844 introduces a superior technique by adding a small amount of nylon 4,6.

This prior art refers to the improvement of rigidity, heat resistance, dimensional stability, and impact resistance by solely or complex strengthening of inorganic fillers and particles in polyamide resins. The addition of materials improves the interfacial bonding between resins or between resins and inorganics, suggesting applications as industrial materials as well as automotive parts.

Specifically, the composition of the filler reinforcement method is applied to the radiator head shank or air intake manifold, and the like, and the simple inorganic particle addition composition is suitable for the lead filler for the fuel inlet, the outside door hand, the engine beauty cover, and the hybrid. It is mentioned that the composite reinforcement composition is applicable to automobile fans, shrouds, timing belt covers, and various ducts.

In order to apply such a polyamide composition to the above various products, most injection molding methods are adopted for the purpose of simply improving mechanical properties. However, in case of excessive molding, the quality of the product is deteriorated due to the addition of excessive minerals. In the case of large and large injection products, warpage and deformation occur due to the shrinkage difference in the longitudinal and transverse directions. In this case, the filling balance becomes a problem, and thus a weld line, a sink, a flow mark, etc. are generated after molding, thereby degrading the value as a product.

This limitation occurs more seriously when the inorganic fillers are added alone, and therefore, it is difficult to expect an improvement in impact resistance and heat resistance of the composition. In addition, due to the technique proposed by alloying with the third compound, in the case of polypropylene, heat resistance becomes poor, and a compatibilizer must be additionally added to enhance the compatibility of polyamide and polypropylene. However, alloys with other polyamides, such as aromatic polyamides and polyamide 4.6 resins, are excellent in heat resistance, rigidity, impact resistance, etc., but are not economical and have high melt viscosity, which causes problems in forming large products of thin films. In particular, when the coupling agent is not treated in the inorganic material used, when the excessive amount is added, the surface defect phenomenon is severe, and not only the quality of the product is degraded but also the impact resistance problem is exposed. In addition, there is a suggestion for the use of the properties of most polyamide compositions, so that each proposed composition is not a big problem, but application to parts requiring complex and higher functionality is difficult. As described above, the conventionally proposed technology is limited in the application of the application because it cannot satisfy all of the physical properties and the required performance, and most of the proposed technology is configured to be suitable for a conventional injection molded product.

The manufacturing technique of a polyamide resin composition is various, and there exists a technique of strengthening an alloy or an inorganic substance with another polymer, electrically conductive, flame-retardant, etc. typically.

In the case of the inorganic-reinforced polyamide resin was introduced above, in the case of the alloy technique, other resins include other polyamide-based, polypropylene-based, polystyrene-based, polyphenylene oxide, thermoplastic elastomer (elastomer). Of course, such an alloy composition may be used alone depending on the use or required performance, but there is a technique for reinforcing inorganic material on the alloy composition according to the performance of the product. In the case of the conductive technology, a carbon fiber, a carbon black powder, ferrite, graphite, and the like are mainly added to a carbon material or a conductive inorganic material. Flame retardant also includes flame retardant polyamide technology that adds a halogen flame retardant, melamine flame retardant or phosphorus flame retardant.

In the case of polyamide, it is well known that the reinforcing effect of the inorganic material is superior to other resins. Therefore, the mineral reinforcement technology has been applied in various and many areas than the technology of other compositions. Automotive parts application of most polyamide compositions is this mineral reinforcement technology, but the inorganic material to be reinforced is small but there is an additional problem of increasing the specific gravity of the material.

The present invention is an injection molding that has recently emerged as a composition capable of forming a high performance product at a low cost of production while economically improving the problems of the prior art in order to satisfy both these technical problems and application application problems. It has excellent technical characteristics in forming the microcellular foaming process (hereinafter referred to as 'micro foaming' or 'micro foaming').

This ultra-foaming process is a solution to solve various technical problems that may occur during injection molding. In recent years, the injection molding process is an injection molding process that has a small size of bubbles (5-50 μm) inside the polymer material of plastic products. It is a physical process that uses super critical fluid as a technology for forming and forming a product. It is an environmentally friendly method, which is different from chemical foaming method.

This is designed by designing and attaching a device that can inject supercritical fluid nitrogen or carbon dioxide gas in the middle of the cylinder during injection molding, incorporating a high pressure liquefied gas into the composition during molding to form a single layer structure, and then When injected, the pressure decreases rapidly, and the gas forms a nucleus to form micro pores at the micro level, thereby forming a fine cell in the composition, and thus a method of injection molding. The present invention is also a composition suitable for such a method.

As a technology of composition, polyamide is used as a basic polymer for toughness, chemical resistance, addition effect, surface beauty, and composite reinforcement of glass fiber and mineral treated with coupling agent at the same time to maximize heat resistance, rigidity and dimensional stability. . In addition, by adding an acidic material to lower the viscosity and crystallization rate to further enhance the surface beauty of the product to invent a composition for the microcellular foam injection molding process.

Applications in these technical fields are automotive products suitable for wide and large thin film applications, including radiator fans, shrouds, intercooler air ducts, timing belt covers, It is a technical field that can be suitably used for applications such as a lid filler door.

The resin composition to be prepared is different in the processing method according to the use, but the injection molding method has been applied to many automobiles, electrical and electronics, industrial materials, general living materials and the like. Parts applied by this injection molding process are lighter and have no bending, deformation, surface sinks, flowmarks, weldlines, etc. due to molding problems during product molding. However, this problem occurs according to the structural shape of the product and has been trying to modify the composition as part of the improvement, but this is also a lot of trial and error and still limited by the use. In order to solve these technical problems, a lot of efforts have been made not only in the resin composition but also in the molding method, which is an injection molding method that has recently been highlighted, and is an ultra-foaming method.

When injection molding is performed by the ultra-foaming method, fine pores are formed in the final product, so that the product is lighter and a good product can be obtained without warping or deformation. In addition, there is no problem in the environment to use nitrogen or carbon dioxide gas, but as the gas is used, the composition to which glass fiber or mineral is added causes surface defects and mechanical strength is injected into the solid as pores are formed inside. There is a disadvantage in that compared with the molded method.

Accordingly, the present inventors have made efforts to improve the problems of mechanical properties deterioration and non-uniform shell formation during ultra-foam foaming of the polyamide resin as described above, resulting in a polyamide polymer (polyamide 6) or a polymer in which the polyamide polymer is alloyed. (Polyamide 66), glass fibers, amorphous polyamide resins and modified alkyl ester compounds are mixed in a fixed ratio to achieve mechanical properties such as stiffness, heat resistance and mold shrinkage during ultra-foam foaming, The present invention has been completed by knowing that the resin and the modified alkyl ester compound can control the appropriate viscosity and the solidification rate to improve the heterogeneous shell formation.

Therefore, the present invention has excellent mechanical properties and uniform shell formation, and thus can be applied to automotive parts such as radiator fans, shrouds, intercooler air ducts, timing belt covers, lead pillar doors, outside door handles and side mirror base plates. The purpose is to provide a moldable polyamide resin composition.

The present invention is 55 to 80% by weight of a polyamide polymer (polyamide 6) represented by the following formula (1) or a polyamide polymer represented by the following formula (2) alloy (polyamide 66); 15 to 45% by weight of glass fibers; 3-10 wt% of amorphous polyamide resin; And a polyamide resin composition for ultrafine foaming molding containing 2 to 5% by weight of a modified alkyl ester compound.

In formula 1 n is an integer of 200 to 15,000:

In Formula 2, n is an integer of 200 to 15,000.

Hereinafter, the present invention will be described in detail.

The polyamide resin composition of the present invention has a flexural modulus of 50,000 kg / cm ² or more according to ASTM D790, meets ASTM D648 heat deflection temperature of 180 ° C. or more, and satisfies 115% or less in the percentage of shrinkage in the flow direction and in the perpendicular direction to ultrafine foaming. Molding can be preferably applied to automobile parts.

The polyamide resin composition of the present invention is characterized by using a polyamide polymer (polyamide 6) or a polyamide polymer alloy (polyamide 66), glass fiber, amorphous polyamide and modified alkyl ester compound, The glass fiber used in this composition used the name "3640" of Fiji Fiji (PPG), and its content is 15 to 45% by weight. If less than 15% by weight, the stiffness and heat resistance are poor, and the resin and the modified alkyl ester compound are mixed and used at a constant ratio.

The polyamide polymer of Formula 1 follows a manufacturing method commonly used in the art. For example, 7.17 parts by weight of water and 0.004 parts by weight of the bubble suppressant, tris- (2.4-dibutyl butylphenyl) -phosphite and N, N'-hexamethylene bis (3.5) based on 100% by weight of ε-caprolactam 0.09 parts by weight of Irganox B1171 (trade name, manufactured by Ciba-Geigy Co., Ltd.), a one-to-one mixture of dietary butyl-4-hydroxy-hydrocinamide, is introduced into a reaction tube at 260 ° C. Subsequently, the pressure is increased to 15 Kg / cm ² and reacted for 1 hour, and then the pressure is gradually lowered while maintaining the pressure for about 30 minutes. Subsequently, the reaction was carried out at the same pressure as the atmosphere for 2 hours, and then the pressure was gradually reduced to -360 mmHg, and the reaction was further proceeded for about 1 hour. can do.

In addition, the production method of the polyamide polymer represented by the formula (2) also follows a known method. Typically, hexamethylenediamine adipate salt as a polyamide polymerization raw material (hereinafter referred to as 'AH' salt) in a polyamide resin polymerization autoclave equipped with a stirrer, a heat sensor, a temperature controller and a steam reflux cooler. And an appropriate amount of water according to the concentration of the AH salt. Subsequently, using a stirrer to increase the temperature, it is dissolved uniformly, and then various additives are prepared in a container for preparing a raw material, using a mixed solvent of methanol and water to prepare a uniform slurry, and then introduced into a reaction tube in which AH salt is dissolved. Manufacture according to. In addition, acetic acid may be added as a viscosity stabilizer for the convenience of the process, and a small amount of hexamethylene diamine and an antifoaming agent may be additionally added as an excess additive, and high purity nitrogen gas may be added after all raw materials are added to the reaction tube. After purging oxygen while purging, the desired polyamide polymer can be obtained.

Table 1 below shows the conditions used in the preparation of the polyamide polymer represented by the formula (1).

TABLE 1

According to Table 1, in the pressure raising and the temperature raising step, as the temperature is increased, the steam is filled in the autoclave, thereby causing a pressure increase. At this time, it raises to 230 degreeC over 1 hour from the point where temperature becomes 120 degreeC. When the pressure reaches 17.5 Kg / cm ² , the pressure is maintained while the steam is discharged to the outside, the temperature is raised to about 250 ° C., and the pressure is dropped to the atmospheric pressure for 70 minutes while the steam is discharged to the outside. Subsequently, after maintaining and stabilizing for 30 minutes, nitrogen is added at about 2 to 2.5 Kg / cm ² to prepare a desired polyamide polymer through a discharging process.

The polyamide polymers of the formulas (1) and (2) obtained by the above-described method are prepared in the form of chips for the final resin composition to be suitable for the present invention, and then dried in a dehumidifying dryer at 90 ° C. for 5 hours. The resins of Chemical Formulas 1 and 2 are not particularly limited. Preferably, Chemical Formula 1 has a relative viscosity of 2.5 to 3.5 (20 ° C., 1 g of polyamide in 100 ml of 96% sulfuric acid), and Chemical Formula 2 has a relative viscosity of 2.4 to 3.0 ( 1 g of polyamide in 100 ml of 96% sulfuric acid is preferably used. If the viscosity is less than the range causes a decrease in stiffness, if the viscosity exceeds the range there is a disadvantage that the surface of the glass fiber surface phenomena, it is difficult to form a uniform cell during ultra-fine foam molding.

The polyamide polymers of Chemical Formulas 1 and 2 may be applied to a conventional injection method (hereinafter, referred to as a 'solid method'), but have a flexural modulus and impact that are roughly distinguished from the rigidity of the polymer for introduction into ultra-foam foaming. In order to solve the problem of non-uniform cell formation caused by the difference in the solidification rate of the core and skin layer of the product cavity during the strength and injection molding, glass fiber, amorphous polyamide and modified alkyl ester compound are added. There is a characteristic of achieving the purpose.

In the case of performing such ultra-foaming molding, since fine pores are formed in the final product, the product is lighter and a good product can be obtained without warping or deformation. In particular, the addition of glass fiber, amorphous polyamide and modified alkyl ester compounds upon foaming can improve the mechanical strength and improve the problems caused by heterogeneous cell formation.

The glass fiber is a glass fiber which is commonly used, and a glass fiber in the form of chop (Chop) commonly used as "G" or "K" glass. A main component is used to be ₂ .Al ₂ O ₃ and CaO CaO.SiO from 10 to 20 wt%, SiO ₂ of 50 to 70% by weight and Al ₂ O ₃ is made up of from 2 to 15% by weight. In particular, the glass fiber is selected to have a coupling (Coupling) treatment with a silane (Silane) on the glass fiber surface for interfacial adhesion with the final composition. Glass fiber used in the present invention is preferably used 3640 (PPG).

Such glass fibers are those having a diameter of 10 to 13 µm and a length of 3 to 3.5 mm, and the content thereof is limited to 15 to 45% by weight based on the total resin composition. If the content is less than 15% by weight, the flexural modulus is lowered, and when the content is more than 45% by weight, the improvement of shrinkage anisotropy of the resin composition is not preferable.

On the other hand, as the amorphous polyamide resin used for the purpose of the composition, C ₆ to C ₁₅ alicyclic diamines, C ₆ to C ₁₅ aliphatic dicarboxylic acids, C ₆ to C ₁₅ lactam acids or amino acids, One or two or more selected from isophthalic acid and terephthalic acid can be used by condensation polymerization. In addition, the amorphous polyamide should contain at least 5 mol% of cycloaliphatic diamine, isophthalic acid, terephthalic acid, and mixtures thereof, below which the purpose of the desired composition cannot be reached.

Examples of the alicyclic diamine include bis (4-amino-cyclohexyl) -methane, bis (4-amino-2-methyl-cyclohexyl) -methane and bis (4-amino-3-methyl-cyclohexyl) -methane , Bis (4-amino-2-ethyl-cyclohexyl) -methane, bis (4-amino-3-ethyl-cyclohexyl) -methane, bis (4-amino-2-propyl-cyclohexyl)- Methane, bis (4-amino-3-propyl-cyclohexyl) -methane, bis (4-amino-2-isopropyl-cyclohexyl) -methane, bis (4-amino-3-isopropyl-cyclo Hexyl) -methane, bis (4-amino-2-methyl-cyclohexyl) -propane, bis (4-amino-3-methyl-cyclohexyl) -propane, bis (4-amino-2-ethyl-syke Lohexyl) -propane, bis (4-amino-3-ethyl-cyclohexyl) -propane, bis (4-amino-2-propyl-cyclohexyl) -propane, bis (4-amino-3-propyl- Cyclohexyl) -propane, bis (4-amino-2-isopropyl-cyclohexyl) -propane, bis (4- Amino-3-isopropyl-cyclohexyl) -propane and the like can be used.

Generally, these alicyclic diamines are geometric isomers that form between carbon atoms and amino groups occupying the 1,4-position of the cyclohexane ring generated by hydrogenation of aromatic rings, that is, trans-trans structure, trans-cis structure, cis-cis It consists of a mixture of structures. Usually, the trans-trans structure has a high glass transition temperature and excellent heat resistance, but there is no big limitation in the present composition. Dicarboxylic acid monomers that can be applied in the same molar ratio as diamine monomers include adipic acid, azelaic acid, sebacic acid, decanoic acid, dodecanoic acid, 2.2.4-trimethyladipic acid, 2.4.4-trimethyladipic acid, 2.2.4- trimethyl hexamethylene diamine, trimethylhexamethylene diamine, etc. 2.4.4- a C ₆ ~ C ₁₅ aliphatic dicarboxylic acid, isophthalic acid, lactam, aromatic dicarboxylic acid represented by terephthalic acid, ε- caprolactone of, w- C ₆ -C ₁₅ lactams and amino acids represented by lauryl lactam and the like.

When the amorphous polyamide is used in 3 to 10% by weight, the amount is less than 3% by weight, the effect is insignificant, even distribution of the cell during the ultra-fine foam molding is difficult and exceeds 10% by weight of the molding processability of the composition is poor and the present invention Although it is different from the purpose of the surface defects are not preferable because of the problem of the molding and the manufacturing cost increases.

In addition, in order to achieve the above object, the modified alkyl ester compound is usually an acrylonitrile-based monomer comprising a vinyl cyanamide compound, an aromatic vinyl compound passing through a styrene monomer, and an alkyl methacrylate compound. It is a graft copolymer obtained from 20 to 50% by weight of conjugated diene rubber, 10 to 40% by weight of aromatic vinyl compound, 5 to 35% by weight of vinyl cyanamide compound and 5 to 25% by weight of alkyl ester compound. It is preferably made of%. In the present invention, the conjugated diene rubber is limited to butadiene latex, and the vinyl cyanamide compound includes acrylonitrile methacrylonitrile, and the aromatic vinyl compound includes styrene, alpha-methyl styrene, para-methyl styrene, vinyl toluene, dimethyl styrene And methacrylic acid alkyl ester compounds may be selected from methacrylate, ethyl acrylate, butyl acrylate, hydroxy acrylate and the like. Such compounds are used in an amount of 2 to 5% by weight. If the amount is less than 2% by weight, the effect of improving the impact strength is insignificant, and when the amount is more than 5% by weight, the heat resistance becomes poor and the viscosity increases, which is not preferable. The composition of the compound used in the present invention is 25% by weight of acrylonitrile, 25% by weight of conjugated butadiene rubber with vinyl cyanamide compound, 35% by weight of alpha-methylstyrene with aromatic vinyl compound, and 15% by weight of methacrylate with alkyl ester compound. Use what consists of:

In addition, a heat resistant agent, a releasing agent, an antistatic agent, a lubricant and the like can be added within a range not impairing the object of the present invention. 1: 1 of tris- (2,4-dibutylbutylphenyl) -phosphate and N-N'-hexamethylenebis (3.5-dibutylbutyl-4-hydroxy-hydrocinamide) containing an amide group as a heat resistant agent A mixture of Iganox B1171 (trade name, Seava Gage) can be used.

The method for producing the polyamide composition of the present invention uses the ultra-foam foam molding known in the art.

At this time, the mixer is kneaded at 270 ° C. to 285 ° C. using a twin screw extruder, and the polyamide polymer and the modified alkyl ester are used at the primary inlet by using an extruder having three inlets to maximize the kneading of the resin composition. Injecting the compound, amorphous polyamide in the secondary inlet, glass fiber in the tertiary inlet, and tertiary inlet in the ejector of the extruder to minimize the breakage of the glass fiber by the screw sheath. It is desirable to install close. In addition, a pressure reducing device called vent is provided near the third inlet and the discharge part, and it is effective to reduce the pressure to 150 mmHg or less.

In particular, the resin composition has been in the spotlight as one of the injection molding method, the ultra-foam foam injection molding is light weight because the product is light, there is no warpage, surface think, flow mark, etc., as well as good dimensional stability injection molding There are advantages such as reduced cycle time and cost. As a result, products without warpage, deflection, surface sinks, flowmarks, weldlines, and the like can be manufactured.

In addition, the conventional supercritical fluid has the disadvantage that glass fiber or minerals are exposed on the surface during injection molding with nitrogen, and that the strength of the product is lower than that of the solid because the cell is formed inside the resin with no apparent appearance. It is possible to obtain an effect.

The polyamide resin composition according to the present invention has a flexural modulus of 50,000 kg / cm ² or more according to ASTM D790, and a heat deflection temperature of 180 ° C. or higher according to ASTM D648, and 115% or less as a percentage of shrinkage in the flow direction and the perpendicular direction. The ultra-fine foam molding can be applied to the radiator fan, the shroud, the intercooler air duct, the lead filler, the timing belt cover, and the like.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the Examples.

Examples 1 to 13

Next, melt kneaded in a twin screw extruder heated to 280 ° C (250 ° C for polyamide 6) according to the composition shown in Table 3, and then made into a chip state and dried using a dehumidifying dryer at 90 ° C for 5 hours, and then ultra-foamed. The specimen was produced using the injection molding machine.

At this time, ultra-foam foaming was performed as shown in Table 2, and the test specimens thus secured were evaluated for flexural modulus, thermal strain temperature, shell formation by electron scanning microscope (SEM), and shrinkage anisotropy by the following physical property evaluation methods. . The supercritical fluid used as a device and equipment for ultra-foam injection is nitrogen (N2), and it is an interface kit, a supercritical fluid port, a feeder, a controller, and a 150 Ts injection device. , Injector, etc. are attached,

TABLE 2

[Property evaluation method]

1) Flexural modulus: measured using 1/8 inch specimen according to ASTM D790

2) Heat deflection temperature: measured at 18.6kg / cm ² load using 1/4 inch specimen according to ASTM D648.

3) Skin and core shell distribution: The disk-shaped cavity (thickness 3.2 mm, diameter 100 mm) prepared for the evaluation of shrinkage anisotropy was cut by 3 x 5 mm in transversely and vertically from the gate at the opposite end of the gate. After aging at 40 ° C. for 3 hours, the central part was broken and the shell distribution of the skin layer and the core layer was observed by SEM of the JSM-T330A model of JEOL. The skin layer was defined to a depth of 0.4 mm from the surface and the rest were considered cores. When no shell was formed in the skin layer, it was judged to be defective.

4) Shrinkage anisotropy: Shrinkage anisotropy was calculated by the following equation by measuring the shrinkage rate in the flow direction and the direction perpendicular to the gate using a disk-shaped cavity 100 mm thick and 3.2 mm in length. The injection molding conditions were the same as the conditions used for the surface observation, and was determined to be poor in the case of more than 115%.

TABLE 3

TABLE 4

Comparative Example 1

The same process as in Example, but was prepared using a polyamide resin and glass fibers as shown in Table 5 below. Ultrafine foam molding of the resin to prepare a specimen and to measure the physical properties are shown in Table 6 below.

TABLE 5

TABLE 6

Comparative Example 2

The polyamide resin was prepared in the same manner as in Example, using only one of a polyamide resin, glass fiber and amorphous polyamide, or a modified alkyl ester compound as shown in Table 7 below. Ultrafine foam molding of the resin to prepare a specimen and to measure the physical properties are shown in Table 8 below.

TABLE 7

TABLE 8

Comparative Example 3

The polyamide resin was prepared in the same manner as in Example, but used outside the content range of the polyamide resin, the glass fiber and the amorphous polyamide, and the modified alkyl ester compound as shown in Table 9 below. Ultrafine foam molding of the resin to prepare a specimen and to measure the physical properties are shown in Table 10 below.

TABLE 9

TABLE 10

As shown in Table 4, Table 6, Table 8 and Table 10, it was confirmed that the present invention can achieve the desired effect only when the components and content defined in the present invention.

As described above, the composition according to the present invention contains a glass fiber, an amorphous polyamide resin and a modified alkyl ester compound in a polyamide resin in a certain ratio, uniform mechanical properties and shell formation, radiator fan, shroud, intercooler air It can be applied to automobile parts such as duct, timing belt cover, lead filler door, outside door handle and side mirror base plate.

Claims (7)

55 to 80% by weight of a polyamide polymer represented by the following formula (1) (polyamide 6) or a polyamide polymer represented by the following formula (2); 15 to 45% by weight of glass fibers; 3-10 wt% of amorphous polyamide resin; And Modified alkyl ester compound 2-5 wt% Polyamide resin composition for ultra-fine foam molding, characterized in that it comprises: [Formula 1] In formula 1 n is an integer of 200 to 15,000: [Formula 2] In Formula 2, n is an integer of 200 to 15,000. According to claim 1, Formula 1 has a relative viscosity of 2.5 to 3.5 (1 g of polyamide in 100 ml of 96% sulfuric acid, 20 ℃, a relative viscosity of 2.4 to 3.0 (polycarbonate in 100 ml of 96% sulfuric acid at 20 ℃, 96%) Polyamide resin composition for ultrafine foam molding, characterized in that the amide 1g). The polyamide resin composition for ultrafine foam molding according to claim 1, wherein the glass fiber is chopped, has a length of 3 to 3.5 mm, and has a diameter of 10 to 13 um. The method of claim 1, wherein the amorphous polyamide resin is selected from C ₆ to C ₁₅ alicyclic diamines, C ₆ to C ₁₅ aliphatic dicarboxylic acids, C ₆ to C ₁₅ lactam acids or amino acids, isophthalic acid and terephthalic acid. Polyamide resin composition for ultrafine foam molding, characterized in that the selected one or two or more selected by condensation polymerization. The polyamide resin composition for ultrafine foam molding according to claim 1 or 4, wherein the amorphous polyamide resin contains 5 mol% or more of alicyclic diamine, isophthalic acid, terephthalic acid, and mixtures thereof. The ultra-expanded foam according to claim 1, wherein the modified alkyl ester compound contains 25% by weight of acrylonitrile, 25% by weight of butadiene rubber, 35% by weight of alpha-methylstyrene, and 15% by weight of methacrylate. Polyamide resin composition for molding. The polyamide resin composition according to claim 1, wherein the polyamide resin composition has a flexural modulus of 50,000 kg / cm ² or more (ASTM evaluation method D790) on a 10% weight reduction basis, a heat deflection temperature of 180 ° C. or more, and a percentage of shrinkage of the flow direction and the perpendicular direction 115. Ultrafine foam molding polyamide resin composition, characterized in that% or less (ASTM evaluation method D648).