JPH08259809A - Polyamide resin composition - Google Patents

Abstract

PURPOSE: To obtain a polyamide resin composition for molding having high strength and modulus capable of substituting a metal and excellent in formability. CONSTITUTION: This composition is obtained by compounding a crystalline copolymer and an inorganic filler. The crystalline copolymer is obtained by the polycondensation of a mixed xylylenediamine, which is composed of 25-65mol% of p-xylylenediamine and 75-35mol% of m-xylylenediamine, with an α, ω-straight chain aliphatic dicarboxylic acid having the number of carbons of 6-12. In the copolymer, the difference between a melting point and a crystallization temperature determined by DSC method is <=60 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyamide resin composition for molding which has a high strength and a high elastic modulus which can be substituted for metals and which has a good moldability.

[0002]

2. Description of the Related Art Polyamide resins represented by nylon 6 and nylon 66 are excellent in toughness, chemical resistance, electrical characteristics and the like, and are widely used as molding materials for automobile parts, machine parts, electric / electronic equipment parts, etc. It's being used. inside that,
Polyamide obtained from metaxylylenediamine and adipic acid (hereinafter sometimes referred to as nylon MXD6)
Has high strength, high elastic modulus, and low water absorption compared to conventional polyamide resins, and is used as an alternative metal material for electrical and electronic equipment parts and automobile parts that are required to be lightweight and compact. Utilization has advanced, and in recent years, the demand has increased remarkably.

The crystallization speed of nylon MXD6 is slower than that of nylon 6 or nylon 66. Therefore, nylon M
When the XD6 is used alone, it is difficult to crystallize in the mold during injection molding, it is difficult to perform thin-wall molding, and problems such as deformation of the obtained molded product and deterioration of mechanical strength are likely to occur. for that reason,
In order to use Nylon MXD6 as a molding material, it is necessary to mix nylon 66 or talc powder, which has a high crystallization rate, to increase the crystallization rate or to raise the mold temperature to improve the moldability. There is (Japanese Patent Publication Sho 54-3245)
8). However, since nylon 66 is blended, the water absorption rate is larger than that of nylon MXD6 alone, and therefore the mechanical strength is reduced due to water absorption.

[0004]

The present invention is based on nylon M
In order to solve the above-mentioned problems of XD6, a mixture of metaxylylenediamine and paraxylylenediamine as a diamine component and adipic acid as a dicarboxylic acid component are used as a main raw material of polyamide, and a high crystallization rate is obtained. By obtaining a polymerized polyamide and adding an inorganic filler to the copolymerized polyamide, a polyamide having good moldability, particularly effective in shortening the molding cycle time and lowering the mold temperature, or suitable for thin-wall molding The purpose is to provide a molding material.

[0005]

As a result of intensive studies, the present inventors have found that a polyamide resin composition using a copolyamide obtained from a specific monomer composition has a high crystallization rate and good moldability. In addition, the present invention was found to be effective in shortening the molding cycle time, and completed the present invention.

That is, according to the present invention, para-xylylenediamine 25-65 mol% and meta-xylylenediamine 75-
The difference between the melting point and the crystallization temperature measured by the DSC method obtained by the polycondensation reaction of 35 mol% of mixed xylylenediamine and the α, ω-straight chain aliphatic dicarboxylic acid having 6 to 12 carbon atoms is The present invention relates to a polyamide resin composition comprising a crystalline copolyamide having a temperature of 60 ° C. or lower and an inorganic filler.

The DSC method according to the present invention refers to JIS-712.
1 is used. Generally, the smaller the difference between the melting point and the crystallization temperature measured by the DSC method, the higher the crystallization rate of the polymer. Therefore, when the difference between the melting point and the crystallization temperature exceeds 60 ° C., it is often a polyamide that does not have a sufficient degree of crystallization. Molding using such a polyamide shortens the cycle time and shortens the cycle time. It becomes difficult to lower the mold temperature.

The diamine which is a monomer of the copolyamide used in the present invention is para-xylylenediamine 25-65.
A mixed xylylenediamine containing 75% to 35% by mol of meta-xylylenediamine, and optionally an aliphatic diamine such as tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, octamethylenediamine, nonamethylenediamine and the like. , Aromatic diamines such as metaphenylenediamine and paraphenylenediamine, and alicyclic diamines such as 1,3-
One or more of bisaminomethylcyclohexane, 1,4-bisaminomethylcyclohexane and the like can be appropriately selected and used within a range not exceeding 5 mol% of all diamines.

When the content of para-xylylenediamine in the mixed xylylenediamine is less than 25 mol%, the crystallization rate of the obtained copolyamide is low and the difference between the melting point and the crystallization temperature exceeds 60 ° C. This causes deterioration of moldability, deformation of the molded product due to poor crystallization, and deterioration of mechanical strength. Further, when the content of paraxylylenediamine in the diamine component exceeds 65 mol%, the melting point of the obtained copolyamide resin approaches 300 ° C., and thermal deterioration due to heating during molding tends to occur, which facilitates molding. Disappear.

The dicarboxylic acid, which is a monomer for the copolyamide used in the present invention, has α, which has 6 to 12 carbon atoms,
ω-aliphatic dicarboxylic acids, preferably adipic acid, optionally aliphatic dicarboxylic acids such as succinic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid. Etc.
One or more of aromatic dicarboxylic acids such as 1,5-naphthalenedicarboxylic acid is 5 mol% of all dicarboxylic acids.
It may be appropriately selected within a range not exceeding. Relative viscosity of the copolyamide used in the present invention (96% sulfuric acid solution 1 g /
100 mL) is preferably 1.5 to 4.0 in consideration of the melt viscosity during molding and the mechanical strength after molding.

In the present invention, it is not necessary to blend nylon 66, which has been blended with a conventional molding material using nylon MXD6. By not blending nylon 66, the water absorption rate decreases, and it is possible to prevent deterioration of mechanical properties due to water absorption.

The inorganic filler used in the present invention is not particularly limited as long as it is generally used for this kind of composition.
Powdered, fibrous, granular, and flake-like inorganic fillers or a combination thereof can be used. The blending ratio of the inorganic filler is preferably 10 to 150 parts by weight with respect to 100 parts by weight of the copolyamide in consideration of mechanical performance and the like.

As the fibrous filler, glass fibers, whiskers of potassium titanate or calcium sulfate, carbon fibers and alumina fibers can be used. The powdery filler preferably has a particle size of 100 μm or less, more preferably 80 μm or less, and carbonates such as kaolinite, silica, calcium carbonate and magnesium carbonate, and sulfuric acid such as calcium sulfate and magnesium sulfate. salt,
Sulfides and metal oxides can be used.

In the present invention, it is preferable to use talc powder to further promote crystallization. The talc used is preferably 100 μm or less, more preferably 8 μm.
It has a particle size of 0 μm or less, and is mixed in a ratio of 30 parts by weight or less with respect to 100 parts by weight of the copolyamide. When the blending ratio of talc exceeds 30 parts by weight with respect to 100 parts by weight of the copolyamide, the flowability of the resin at the time of molding may be deteriorated, and the mechanical performance of the obtained molded product may be deteriorated, which is preferable. Absent.

In addition, if necessary, one or more additives such as flame retardants, antistatic agents, lubricants, plasticizers, stabilizers against oxidation and deterioration due to heat and ultraviolet rays, and colorants may be used. it can.

[0016]

The use of the copolyamide of the present invention facilitates thin-wall molding, which has been difficult with conventional molding materials using nylon MXD6, and further shortens the molding cycle and lowers the mold temperature. Moldability was improved. Furthermore, deterioration of mechanical properties due to water absorption was suppressed.

[0017]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. In the examples, "parts" represent parts by weight unless otherwise specified. The molding conditions of Example 1 are as shown below.

Cylinder temperature 280 ° C. Mold temperature 130 ° C. Injection pressure 1000 kg / cm ² Molding conditions of Example 2 are as follows. Cylinder temperature 290 ° C. Mold temperature 130 ° C. Injection pressure 1000 kg / cm ² Molding conditions of Comparative Example 1 are as follows. Cylinder temperature 270 ℃ Mold temperature 130 ℃ Injection pressure 1000kg / cm ²

The evaluation was carried out by the following method. (1) Transition temperature: JIS K7121 (however, the water content of the measurement sample was set to 0.1% by weight or less.) (2) Specific gravity: ASTM D792 (3) Tensile test: ASTM D638 (4) Bending test: ASTM D790 (5) Water absorption test: ASTM D570 (in water, 24 hours) (6) Semi-crystallization time: depolarization intensity method, equipment used Kotaki Seisakusho Co., Ltd. polymer crystallization rate measuring device MK-701
Mold, melting temperature 280 ° C. (Example 1), 290 ° C. (Example 2), 270 ° C. (Comparative Example 1), melting time 3 minutes, crystallization bath temperature 130 ° C., sample shape is pellet.

Example 1 Adipic acid was heated and melted in a reactor under a nitrogen atmosphere.
Paraxylylenediamine (3) was added to the molten dicarboxylic acid.
Mixed xylylenediamine containing 0 mol% and metaxylylenediamine of 70 mol% was successively added dropwise, and the mixture was stirred while maintaining the reaction temperature so as to always exceed the melting point of the product. After the completion of dropping, the reaction was continued with stirring until a predetermined viscosity was reached, and when the viscosity was reached, the product was discharged from the reaction can, cooled with water and pelletized. The copolymerized polyamide obtained is hereinafter referred to as "polyamide A". Polyamide A has a melting point of 258 ° C., a crystallization temperature of 206 ° C., and a relative viscosity (96% sulfuric acid solution 1 g / 100).
mL) was 2.08.

4 parts of talc and 100 parts of glass fiber were mixed with 100 parts of polyamide A synthesized under the above conditions,
A bent type single-screw extruder (manufactured by Nakatani Machinery Co., Ltd.) was used to melt and knead at a cylinder temperature of 280 ° C., followed by water cooling and pelletization. Using the obtained resin composition, a test piece for tensile test, a test piece for bending test and a test piece for water absorption test were molded by an injection molding machine. Table 1 shows the evaluation results.

Example 2 Adipic acid was heated and melted in a reactor under a nitrogen atmosphere.
To the molten dicarboxylic acid, 5 parts of paraxylylenediamine was added.
A mixed xylylenediamine containing 0 mol% and metaxylylenediamine of 50 mol% and metaxylylenediamine are finally mixed in two stages such that paraxylylenediamine is 40 mol% and metaxylylenediamine is 60 mol%. The mixture was added dropwise in portions and stirred while maintaining the reaction temperature so as to always exceed the melting point of the product. After the completion of dropping, the reaction was continued with stirring until a predetermined viscosity was reached, and when the viscosity was reached, the product was discharged from the reaction can, cooled with water and pelletized. The copolymerized polyamide obtained is hereinafter referred to as "polyamide B". Polyamide B had a melting point of 269 ° C., a crystallization temperature of 227 ° C., and a relative viscosity (96% sulfuric acid solution 1 g / 100 mL) of 2.13.

4 parts of talc and 100 parts of glass fiber were mixed with 100 parts of polyamide B synthesized under the above conditions,
Using a vented single-screw extruder (manufactured by Nakatani Machinery Co., Ltd.), the mixture was melt-kneaded at a cylinder temperature of 290 ° C., then water-cooled and pelletized. Using the obtained resin composition, a test piece for tensile test, a test piece for bending test and a test piece for water absorption test were molded by an injection molding machine. Table 1 shows the evaluation results.

Comparative Example 1 Nylon MXD6 (manufactured by Mitsubishi Gas Chemical Co., Inc., melting point 237)
℃, crystallization temperature 152 ℃, relative viscosity 2.10 90 parts of nylon, nylon 66 (manufactured by Toray Industries, Inc.) 10 parts, talc 4
Parts and 100 parts of glass fiber were blended and melt-kneaded at a cylinder temperature of 270 ° C. using a vent type single-screw extruder (manufactured by Nakatani Machinery Co., Ltd.), then water-cooled and pelletized.
Using the obtained resin composition, a test piece for tensile test, a test piece for bending test and a test piece for water absorption test were molded by an injection molding machine. Table 1 shows the evaluation results.

The half-crystallization time of Examples 1 and 2 is
It was shorter than in Comparative Example 1, and it was confirmed that the crystallization rate was increased. Further, the mechanical properties of Examples 1 and 2 are at the same level as those of Comparative Example 1 of the prior art. The water absorption of Examples 1 and 2 is lower than that of Comparative Example 1.

Table 1 Example 1 Example 2 Comparative Example 1 Polyamide resin A B MXD6 (a) Melting point (° C.) 258 269 237 (b) Crystallization temperature (° C.) Difference between 206 227 152 (a) and (b) (° C.) 52 42 85 Component mixing ratio (parts by weight) Polyamide resin 100 100 90 Nylon 66 0 0 10 Glass fiber 100 100 100 Talc 4 4 4 Half crystallization time (sec) 2.9 2.5 6.0 Specific gravity 1.65 1.65 1.65 Tensile strength (MPa) 282 255 273 Tensile modulus (GPa) 20 19 20 Tensile elongation (%) 2.0 1.9 2.1 Bending strength (MPa) 359 329 364 Flexural modulus (GPa) 17 17 18 Water absorption (%) 0.10 0.10 0.13

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuyoshi Watanabe 5-6-2 Higashihachiman, Hiratsuka City, Kanagawa Sanryo Engineering Plastics Co., Ltd. Technical Center

Claims (1)

[Claims] 1. A mixed xylylenediamine composed of 25 to 65 mol% of paraxylylenediamine and 75 to 35 mol% of metaxylylenediamine, and α, ω-having 6 to 12 carbon atoms.
Obtained by a polycondensation reaction with a linear aliphatic dicarboxylic acid,
The difference between the melting point and the crystallization temperature measured by the DSC method is 60 ° C.
A polyamide resin composition comprising the following crystalline copolyamide and an inorganic filler.