JPS6229460B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a polyamide resin composition containing an inorganic filler and a glass fiber, and more specifically, by adding xylylene diamine-based polyamide to a polyamide resin molding material containing a glass fiber and an inorganic filler, it is possible to make a molded product by adding The purpose of the present invention is to provide a polyamide resin composition which has improved mechanical properties, particularly tensile, bending, compressive strength, and each modulus of elasticity, has low water absorption, provides molded products with good dimensional stability, and has excellent moldability. Conventionally, nylon 6 has been widely used in various fields such as molding, and in order to improve its mechanical properties or reduce costs, it has been mixed with glass fiber or inorganic fillers to make molding materials. Attempts have been made to formulate combinations of However, when glass fiber is added, although the mechanical properties are improved, the drawbacks of nylon 6, such as high water absorption, large mold shrinkage, lack of dimensional stability, and warpage cannot be overcome. Not enough has been done yet. Furthermore, when an inorganic filler is blended, the mechanical properties, particularly the impact strength, are significantly reduced, and the characteristics of polyamide are not utilized. As a result of our research into improving this nylon 6 molding material, the present inventors found that by adding xylylene diamine-based polyamide to a polyamide resin molding material made of nylon 6 combined with glass fiber and an inorganic filler. This improves the mechanical properties of molded products, has low water absorption, and has excellent dimensional stability.
Furthermore, the present invention was completed by discovering an industrially practical molding material composition with excellent moldability. That is, the present invention is a polyamide resin composition containing nylon 6, xylylene diamine-based polyamide, glass fiber, and an inorganic filler as essential components, wherein the composition contains 10 to 50% by weight of nylon 6 and xylylene diamine. 10-70% by weight of polyamide, total amount of glass fiber and inorganic filler is 20%
~60% by weight. The xylylene diamine-based polyamide in the present invention is obtained from xylylene diamine and an aliphatic linear dibasic acid having 6 to 12 carbon atoms, and the xylylene diamine that is a constituent component of the polyamide is preferably metaxylylene diamine. However, it may contain up to 40% paraxylylene diamine. Also carbon number 6~
Examples of the 12 aliphatic linear dibasic acids include adipic acid, suberic acid, sebacic acid, and dodecanedioic acid, and may be a mixture of two or more of these. Among them, those obtained mainly using adipic acid are particularly preferred in terms of the effect of modifying nylon 6. The amount of xylylene diamine polyamide added to nylon 6 is 100% by weight of the entire composition.
In this case, it is preferably 10 to 70% by weight, particularly preferably 20 to 30% by weight. The inorganic filler used in the present invention is selected from calcium carbonate, talc, mica, and kaolinite, and a mixture of two or more of these may be used. The blending amount of this inorganic filler is preferably 40% by weight or less, particularly around 20% by weight. This amount is determined in relation to the amount of glass fiber used together, and the total amount of glass fiber and inorganic filler in the composition is 20 to 60% by weight, and if it exceeds 60% by weight, it will be added to the nylon resin. In addition, the moldability of the composition is significantly reduced. or
If it is less than 20% by weight, molding shrinkage will increase and the desired strength will not be achieved, so especially 30 to 50% by weight.
Preferably between. The above-mentioned inorganic fillers can usually be used without surface treatment, but those that have been surface treated with a coupling agent or the like can also be used depending on the purpose. The glass fiber is not particularly limited as long as it is used in ordinary glass fiber reinforced plastics, but chopped strands with a length of 3 to 6 m/m are usually used. Furthermore, antioxidants, colorants, lubricants, flame retardants, crystallization promoters, etc. can also be added to the polyamide resin composition of the present invention, if necessary. As a preparation method for obtaining the polyamide resin composition of the present invention, nylon 6, xylylene diamine polyamide, glass fiber chopped strands, and inorganic filler are sufficiently mixed in a predetermined amount, and then mixed in an extruder. For example, the mixture may be kneaded, extruded into strands, and pelletized using a strand cutter. The mechanical properties of molded products obtained from the polyamide resin composition of the present invention are significantly improved compared to the properties originally possessed by nylon 6, but in particular, the tensile, bending, and compressive strengths and modulus of elasticity are significantly improved. The water absorption rate is greatly reduced, the dimensional stability is improved, and the warping of molded products is significantly reduced. Examples of the present invention are described below. The mechanical properties were measured according to ASTM. Example 1 Each polyamide resin composition blended with the composition shown in Table 1 below was pelletized using an extruder, and the pellet was molded into a test piece using an injection molding machine at a mold temperature of 130°C, and its mechanical properties were evaluated. was measured. For comparison, a test piece of a composition containing no metaxylylene diamine polyamide was prepared using the same method.
These test results are shown in Table 1 along with the composition. (Test numbers marked with B in the table are comparative examples. The same applies to the tables below.)

【table】

[Table] Example 2 A composition blended with the composition shown in Table 2 below was pelletized in the same manner as in Example 1, and molded in the same manner as in Example 1 at a mold temperature of 130°C. A pellet with a diameter of 2 inches and a thickness of 1 The molding shrinkage rate of a /8 inch disk-shaped specimen was measured in the direction in which the molten resin flows into the mold and in the direction perpendicular to the direction of flow. The results are shown in Table 2. In this case, it can be said that the smaller this value and the smaller the difference, the better the dimensional stability. Note that the symbol 〓 in Table 2 represents the inflow direction of the molten resin and the direction perpendicular to the inflow direction, respectively, and nylon 66 was added as a crystallization nucleating agent in the composition.

[Table] Example 3 Regarding test pieces with the same composition and shape as Example 2
The water absorption rate was measured when immersed in water for 24 hours at 20°C. The results are shown in Table 3. It can be seen that the water absorption rate is greatly improved by the addition of poly(methaxylylene adipamide).

【table】

Claims (1)

[Scope of Claims] 1. A polyamide resin composition containing nylon 6, xylylene diamine polyamide, glass fiber, and an inorganic filler as essential components, wherein the composition contains 10 to 50% by weight of nylon 6, A polyamide resin composition characterized in that the diamine polyamide is 10 to 70% by weight, and the total amount of glass fiber and inorganic filler is 20 to 60% by weight. 2. The polyamide resin composition according to claim 1, wherein the xylylene diamine-based polyamide is obtained by reacting xylylene diamine with a linear aliphatic dibasic acid having 6 to 12 carbon atoms. 3. The polyamide resin composition according to claim 1, wherein the inorganic filler is at least one selected from calcium carbonate, talc, mica, and kaolinite.