JPH0718180A - Polyamide resin composition - Google Patents

Abstract

PURPOSE:To obtain a material, having a high strength and rigidity under actual use conditions and excellent in impact resistance and appearance properties of molding surfaces. CONSTITUTION:This polyamide resin composition is composed of 100 pts.wt. blended polyamide composed of (A) 40-95wt.% semiaromatic polyamide constructed from (a) 70-95wt.% hexamethylene adipamide unit obtained from adipic acid and hexamethylendiamine and (b) 5-30wt.% hexamethylene isophthalamide unit obtained from isophthalic acid and hexamethylendiamine and (B) 60-5wt.% aliphatic polyamide and (C) 10-250 pts.wt. inorganic filler.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyamide resin, and more particularly to a polyamide resin composition having excellent mechanical properties, impact resistance and appearance in actual use.

[0002]

2. Description of the Related Art In recent years, polyamide resins have been used as exterior structural members by taking advantage of their excellent mechanical properties and their ability to develop a reinforcing effect when reinforced with an inorganic filler such as glass fiber, excellent coloring properties, and moldability. It has started to be done. The exterior structural member, for example, a leg of a chair, a leg of a desk, a relatively large stress such as a wheel rim of an automobile is a material used for a structural part that requires surface glossiness,
Conventionally, it is mainly used for metal materials. Performances that are commonly required for exterior structural members include high strength and rigidity and good appearance, and impact resistance is also required depending on the application. Until now, mainly Ny6 and Ny66
Although the / 6 copolymer was used, satisfactory strength and rigidity could not be obtained because the rigidity was lowered when absorbing water.

To improve this, Japanese Patent Publication No. 64-110
No. 73 and Japanese Patent Laid-Open No. 4-149234, that is, a polyamide containing an aromatic ring such as terephthalic acid or isophthalic acid is used to reduce the water absorption rate at the time of atmospheric equilibrium water absorption and reduce the rigidity due to water absorption. Techniques that do not cause deterioration are known. However, the introduction of a rigid aromatic ring component leads to an improvement in the strength and rigidity of the resin, but on the other hand, the impact resistance characteristic decreases, so both strength and rigidity and impact resistance characteristics are required. It has been difficult to use it for such applications such as automobile wheel rims.

As a technique for improving the impact resistance of polyamide, a technique of dispersing an elastomer component in a polyamide resin matrix is known, and many techniques have been developed so far. However, in this technique, the strength and rigidity decrease with the blending amount of the elastomer, and although the strength and rigidity are improved to some extent by adding an inorganic filler such as GF excessively, conversely, the inorganic filler on the surface of the molded product is improved. This causes the surface glossiness to decrease due to the rise of the surface. That is, there has been no material which has a suitable balance of strength and rigidity and impact resistance under atmospheric equilibrium and which has excellent appearance on the surface of a molded product.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a material suitable for an exterior structural member which requires a certain degree of impact resistance. More specifically, it has high strength and rigidity in actual use. The object of the present invention is to provide a material having excellent impact resistance and appearance of the surface of the molded product.

[0006]

The present invention achieves the above object, and its gist is as follows. The present invention includes: (A) as a polyamide component, a) 70 to 95% by weight of a hexamethylene adipamide unit obtained from adipic acid and hexamethylene diamine, and b) a hexamethylene isophthalamide unit obtained from isophthalic acid and hexamethylene diamine. 5 to 30% by weight of semi-aromatic polyamide 40 to 95% by weight and (B) aliphatic polyamide 60 to 5% by weight to 100 parts by weight of blended polyamide, (C) inorganic filler 10 to It relates to a polyamide resin composition comprising 250 parts by weight.

The details of the invention will be described below.

The semi-aromatic polyamide used in the present invention is a hexamethylene adipamide unit (hereinafter referred to as N66) obtained from adipic acid and hexamethylene diamine and a hexamethylene isophthalamide unit obtained from isophthalic acid and hexamethylene diamine. (Hereinafter referred to as N6I).

The composition ratio of each component is 70 to 95% by weight of N66 and 5 to 30% by weight of N6I. The preferable composition ratio is 72 to 93% by weight for N66 and 7 to 28% by weight for N6I.
Is. When N6I is more than 30% by weight, the crystallinity is significantly lowered, and the cooling time in the mold at the time of molding becomes long, resulting in poor productivity. Further, it cannot be used for applications requiring chemical resistance (for example, oil resistance of spokes of bicycle wheels). If N6I is less than 5% by weight, the crystallization temperature of the resin becomes high and the inorganic filler rises on the surface of the molded product, resulting in extremely poor surface appearance. N66, N
The copolyamide composed of each component of 6I is obtained by polycondensation reaction of adipic acid, isophthalic acid and a salt of hexamethylenediamine, and known reaction methods include melt polymerization, solid phase polymerization, solution polymerization and interfacial polymerization. Etc.
The molecular weight of the semi-aromatic polyamide used in the present invention is 1.5 to 2.8, preferably 1.6 to 2 in sulfuric acid solution viscosity ηr (100 g of 95.5% sulfuric acid per 25 g of polymer, measured at 25 ° C.). 0.7, and more preferably 1.7 to 2.6.

The aliphatic polyamide referred to in the present invention is -C.
It refers to a substantially linear polyamide having H ₂ —, specifically, nylon 46 and nylon 66 (hereinafter referred to as Ny).
66), nylon 610, nylon 612, nylon 6, nylon 11, nylon 12, nylon 66 and nylon 6 (hereinafter referred to as Ny6) copolymer, nylon 66 and nylon 610 copolymer, nylon 66 and nylon 612 copolymer, etc. And two or more types may be mixed. More preferably nylon 6 or nylon 66/6 copolymer is preferred. The molecular weight of the aliphatic polyamide is not particularly limited and may be within the known molecular weight range. However, when the shape of the molded product is such that the surface appearance of the molded product is not relatively deteriorated, a high molecular weight aliphatic polyamide is preferable and the sulfuric acid solution viscosity is ηr = 2.3 to
A range of 4.5 is preferred. If ηr is lower than 2.3, the effect of imparting impact resistance is not sufficient, and if ηr is higher than 4.5, the fluidity decreases and the inorganic filler rises a lot on the surface of the molded product, resulting in poor appearance. Will decrease.

The amount of the aliphatic polyamide compounded is 5 to 60% by weight, preferably 10% by weight, based on the total amount of the polyamide resin.
˜55 wt%. If it is less than 5% by weight, the impact properties will not be improved, and if it is more than 60% by weight, the strength and rigidity will decrease due to water absorption, and sufficient strength and rigidity cannot be obtained under actual use. The inorganic filler used in the present invention is glass fiber, carbon fiber, mica, talc, kaolin, wollastonite, calcium carbonate, potassium titanate or the like. Of these, a filler containing glass fiber as a main component is preferable, and one or more kinds of other inorganic fillers may be mixed with the glass fiber.

The blending amount of the inorganic filler of the present invention is 10 to 250 parts by weight based on 100 parts by weight of the polyamide resin,
It is preferably 15 to 200 parts by weight. If the amount is less than 10 parts by weight, the reinforcing effect of the inorganic filler will not be sufficiently exhibited and satisfactory strength and rigidity cannot be obtained. On the other hand, if the amount is more than 250 parts by weight, the fluidity of the resin deteriorates and it becomes difficult to fill the thin portion with the resin. Further, the decrease in fluidity is not preferable because it deteriorates the appearance of the surface of the molded product.

The method of blending the polyamide of the present invention with the inorganic filler may be a known method of pelletizing the rope of the resin composition obtained after melt-kneading using a conventional uniaxial or biaxial extruder. Further, at this time, within a range not impairing the object of the present invention, a heat stabilizer, an ultraviolet absorber, an antioxidant,
Lubricants, nucleating agents, antistatic agents, release agents, dye-based colorants, pigment-based colorants, flame retardants, plasticizers, other resins and the like may be added. The molded article of the present invention can be obtained by a usual melt molding method, for example, an injection molding method.

[0014]

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Example 1 Equimolar salt of adipic acid and hexamethylenediamine 2.0
0 kg, 0.50 kg of equimolar salt of isophthalic acid and hexamethylenediamine, and 2.5 kg of pure water were charged in a 5 L autoclave and well stirred. After sufficiently substituting with N _{2, the} temperature was raised from room temperature to 220 ° C. over about 1 hour while stirring. At this time, the internal pressure becomes 18 kg / cm ² -G due to the natural pressure of water vapor in the autoclave,
Further heating was continued while removing water from the reaction system so that the pressure did not exceed 8 kg / cm ² -G. After an additional 2 hours, when the internal temperature reached 260 ° C, heating was stopped, the discharge valve of the autoclave was closed, and the temperature was cooled to room temperature over about 8 hours. After cooling, the autoclave was opened, and about 2 kg of polymer was taken out and pulverized. The obtained pulverized polymer was added to 10
Place it in an L evaporator at 10 ° C at 200 ° C under N ₂ flow.
Solid-state polymerization was carried out for a period of time. Relative viscosity of sulfuric acid (η
r: Polymer 1 g / 95.5%, sulfuric acid 100 ml, 25
(Measured in ° C) changed from 1.38 to 2.30.

70 parts by weight of the obtained polymer was added with Ny6 (η
r: 3.2) 30 parts by weight were blended, and glass fiber (03JA416 manufactured by Asahi Fiber Glass Co., Ltd.) was melt-kneaded under the following conditions using a twin-screw extruder. Twin screw extruder (W
Cylinder temperature of ERNER ZSK25) is 280
The temperature was set to 0 ° C., and the blend polymer was charged from the hopper at a screw rotation of 100 rpm. Glass fiber is Zone
From 4, the resin composition was side-fed so that the glass fiber content was 50 wt%. The polymer charging section and the glass fiber charging section were thoroughly purged with N ₂ . Vent vacuum was applied from Zone 6 (650 mmHg). Discharge rate 9.4
kg / HR ,. The resin temperature was 305 ° C.

The pellets thus obtained were treated with N ₂ at 80 ° C.
After drying for 24 hours, injection molding machine (P, manufactured by Nissei Plastic Co., Ltd.
A test piece was prepared using S40E). Molding is set at a cylinder temperature of 290 ° C and a mold temperature of 80 ° C, with an injection speed of 5
The cycle was 0%, injection pressure 70 kg / cm ² -G, injection 10 seconds, and cooling 20 seconds. The measuring method of the test piece is as follows.

Tensile strength: Performed according to ASTM D638. Bending strength: Performed according to ASTM D790. Flexural modulus: measured according to ASTM D790. IZOD (with notch): Performed according to ASTM D790. Appearance: The presence or absence of glass fiber floating on the surface of the molded product was visually determined. The test results are shown in Table 1 below.

Example 2 Equimolar salt of adipic acid and hexamethylenediamine 2.2
A semi-aromatic polyamide was prepared in the same manner as in Example 1 except that 5 kg, 0.25 kg of an equimolar salt of isophthalic acid and hexamethylenediamine, and 2.5 kg of pure water were used as starting materials (ηr: 2.4). ), And Ny6 and glass fiber were blended in the same manner as in Example 1.

Example 3 Equimolar salt of adipic acid and hexamethylenediamine 1.8
A semiaromatic polyamide was prepared in the same manner as in Example 1 except that 75 kg, 0.625 kg of an equimolar salt of isophthalic acid and hexamethylenediamine, and 2.5 kg of pure water were used as starting materials (ηr: 2.4). ), As in Example 1, Ny6
And glass fiber were blended.

Example 4 Equimolar salt of adipic acid and hexamethylenediamine 1.8
0 kg, ε-caprolactam 0.20 kg and pure water 2.
A polymer was obtained in the same manner as in Example 1 using 5 kg as a starting material (ηr: 3.0). 30 parts by weight of the polymer, 70 parts by weight of the semi-aromatic polyamide obtained in Example 1 and 100 parts by weight of glass fiber were mixed with 100 parts by weight of the polymer under the same extrusion conditions as in Example 1.

Example 5 Example 5 was repeated except that the aliphatic polyamide was Ny66 (Leona 1300).

Example 6 The same polyamide as in Example 1 was used, and the blending amount of glass fiber was 50 parts by weight. Example 7 The same polyamide as in Example 1 was used, and the amount of glass fiber was 78 parts by weight.

Example 8 The same method as in Example 1 was carried out except that the blending ratio of the copolyamide consisting of N6I units as the N66 unit and Ny6 used in Example 1 was 85 parts by weight to 15 parts by weight.

Comparative Examples 1 and 2 Ny6 and N66 units and N6 used in Examples 1 and 4
The copolyamide composed of I units was used, and the glass fiber compounding method was the same as in Example 1. Comparative Example 3 Ny66 (Leona 1300) and Ny6 (ηr: 3.2)
Was prepared in the same manner as in Example 1 except that 70 parts by weight to 30 parts by weight of was added. Comparative Example 4 Equimolar salt of adipic acid and hexamethylenediamine 1.2
A semi-aromatic polyamide was prepared in the same manner as in Example 1 except that 5 kg, 1.25 kg of an equimolar salt of isophthalic acid and hexamethylenediamine, and 2.5 kg of pure water were used as starting materials (ηr: 2.3). Ny6 (ηr:
3.2) was blended as in Example 1 and melt-kneaded under the same conditions.

Comparative Example 5 The glass fiber alone was kneaded in the same manner as in Example 1 with the semi-aromatic polyamide obtained in Example 1 without using the aliphatic polyamide. Comparative Example 6 1.0 equimolar salt of adipic acid and hexamethylenediamine
Semi-aromatic as in Example 1, except that 0 kg, 0.40 kg of equimolar salt of isophthalic acid and hexamethylenediamine, 0.60 kg of equimolar salt of terephthalic acid and hexamethylenediamine and 2.5 kg of pure water were used as starting materials. A group polyamide was prepared (ηr: 2.3). Only this glass fiber was kneaded with this polyamide in the same manner as in Example 1.

Comparative Example 7 A copolyamide composed of N66 units and N6I units used in Example 1 and Ny6 were blended at the same blending ratio as in Example 1 and extruded without adding glass fiber.

Comparative Example 8 Ny6, a copolyamide composed of N66 units and N6I units used in Example 1, was blended at the same compounding ratio as in Example 1, and glass fiber was added to 300 parts by weight with respect to 100 parts by weight of polyamide resin. Blended so that A jetting phenomenon was strongly observed on the surface of the molded product produced under the above molding conditions, and a satisfactory molded product could not be obtained. Using the resin compositions obtained in the above Examples 2 to 8 and Comparative Examples 1 to 7, test pieces were prepared and tested in the same manner as in Example 1. The results are shown in Tables 1 and 2.

[0028]

[Table 1]

Note 1) Atmospheric equilibrium water absorption condition; 23 ° C., 50% RH atmosphere Note 2) Appearance; ◯: GF does not rise on the surface of the molded product, ×: GF does rise, Note 3) Comparative example 4: Molding time cycle (injection) 10 seconds (cooling) 20 seconds showed poor releasability, and (injection) 10 seconds (cooling) 35 seconds were used for sampling. Note 4) The value in () is the flexural modulus retention rate ({[flexural modulus immediately after molding] / [flexural modulus at atmospheric equilibrium water absorption]) x 1
00 (%))

[0030]

[Table 2]

In each of Examples 1 to 8, there is little decrease in strength and rigidity during atmospheric equilibrium water absorption, and the impact resistance characteristic value,
The appearance is also high. On the other hand, in Comparative Examples 1 to 3, the strength / rigidity is greatly reduced under atmospheric equilibrium water absorption, and the retention rate for the strength / rigidity immediately after molding is 70% or less. Comparative Examples 4-7
Has a low impact strength.

[0032]

According to the present invention, it is possible to obtain a polyamide resin composition having excellent mechanical properties, impact resistance and appearance in actual use.

Claims (1)

[Claims] 1. (A) As a polyamide component, a) 70 to 95% by weight of a hexamethylene adipamide unit obtained from adipic acid and hexamethylenediamine, and b) Hexamethyleneisophthalamide obtained from isophthalic acid and hexamethylenediamine. (C) Inorganic filler 10 to 100 parts by weight of a blend polyamide consisting of 40 to 95% by weight of a semi-aromatic polyamide composed of 5 to 30% by weight of a unit and (B) 60 to 5% by weight of an aliphatic polyamide. A polyamide resin composition consisting of ˜250 parts by weight.