JPH028246A - Molding polyamide resin composition - Google Patents

Abstract

PURPOSE:To obtain a composition with a high heat distortion temperature capable of ready crystallization at low temperatures by blending two specified polyamide resins with a filler. CONSTITUTION:With (A) 100pts.wt. polyamide resin prepared by mixing (A1) 80-97 pts.wt. polyamide resin composed of xylylene diamine and 6-12C alpha,beta- straight-chain aliphatic dibasic acid with (A2) 20-3 pts.wt. polyamide resin containing tetramethylene adipamide as the main structural unit, (B) 5-230 pts.wt. filler is blended. As the (A1) a resin containing m-xylylene diamine as the main component and as the (A2) a resin having 2.3-6.0 relative viscosity (96% sulfuric acid and 25 deg.C) are preferably used.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a polyamide resin composition for molding.

Conventional technology and its problems Non-stretched molded product of polyamide resin (hereinafter referred to as rMX nylon) synthesized from xylylene diamine and α, ω-linear aliphatic dibasic acid having 6 to 12 carbon atoms teeth,
Due to extremely poor impact resistance, glass fibers (JP-A-51-63860, JP-A No. 54-54) are usually used in polyamide resin.
No. 111547), powdered inorganic filler (Japanese Patent Laid-Open No. 1983)
-84848), carbon fiber (Japanese Unexamined Patent Publication No. 54-111)
No. 547) and potassium titanate fiber (Japanese Unexamined Patent Publication No. 1986-
23446) is already known to impart excellent mechanical properties and dimensional stability to MX nylon.

What is consistent with these known technologies is that the crystallinity of 2MX nylon itself is nylon-6 or nylon-6.
Attempts have been made to improve the molding workability by blending nylon-6,6 into MX nylon to promote crystallization, which has a disadvantage in molding process that it is slow compared to MX nylon.

However, even with this technology, (1) crystallization does not proceed at a mold temperature of 60 to 100°C, which is commonly used for nylon-6 and nylon-6,6 polyamide resins; (2) As the thickness of the molded product becomes thinner, crystallization does not proceed even if the mold temperature is increased, so the heat distortion temperature of the molded product does not improve; Problems may arise in heat resistance (thermal deformability) during actual use, or it may be difficult to release from the mold during molding, requiring sufficient cooling time, resulting in longer molding cycles. The current situation is that we have the following.

Means for Solving the Problems The object of the present invention is to provide a method that facilitates crystallization even in low-temperature molds.
The object of the present invention is to provide a polyamide resin composition for molding, which can improve the heat distortion temperature of the molded product obtained therefrom, and can also shorten the molding cycle of thin-walled molded products.

That is, the present invention (a) Xylylene diamine and α having 6 to 12 carbon atoms.

Polyamide resin 100 obtained by mixing 80 to 97 parts by weight of a polyamide resin obtained from ω-linear aliphatic dibasic acid and (b) 20 to 3 parts by weight of a polyamide resin whose main constituent unit is tetramethylene adipamide. 5 to 230 parts by weight of filler
It relates to a molding polyamide resin composition formed by blending parts by weight.

In the present invention, the polyamide resin (MX nylon) used as component (a) is obtained by polycondensation reaction of xylylene diamine and an α,ω-linear aliphatic dibasic acid having 6 to 12 carbon atoms. It is. Here, xylylene diamine is mainly composed of metaxylylene diamine, and specifically, it may be composed of metaxylylene diamine alone, or it may be composed of metaxylylene diamine in an amount of 60% or more and para-xylylene diamine. A mixture of amines at a ratio of 40% or less may be used. Further, examples of the α,ω-linear aliphatic dibasic acids include adipic acid, superric acid, sebacic acid, undecaniic acid, and dodecanniic acid. Among these dibasic acids, adipic acid is particularly suitable in view of the various properties of the resulting molded product. These dibasic acids may be used alone or in a mixture of two or more. The polycondensation reaction between xylylene diamine and an α,ω-linear aliphatic dibasic acid can be easily carried out according to a conventionally known method.

When MX nylon is blended with glass fiber etc., it can give molded products with excellent mechanical strength, dimensional accuracy, rigidity, etc. However, on the other hand, the drawback is that the crystallization rate is considerably slower than that of ordinary nylon. It is mentioned. for that,
For example, during injection molding, the material that enters the mold crystallizes slowly and takes a long time to cool and be removed, which is not desirable in terms of improving molding efficiency. . As mentioned above, in order to solve this difficulty, the technique of adding nylon-6,6 as a crystallization accelerator to promote crystallization is known, but according to the research of the present inventors. , the crystallization promotion effect of adding nylon-6,6 is not sufficient, and the heat deformation temperature is difficult to rise below 100°C, which is the mold temperature of ordinary polyamide resin compositions for molding, and thin-walled molded products (molded product wall thickness is 1/16
It has been found that the molding cycle cannot be shortened (molding efficiency cannot be improved) if the diameter is less than 1.6 mm, that is, approximately 1.6 mm or less.

Subsequent research revealed that by adding a specific amount of polyamide resin whose main constituent unit is tetramethylene adipamide instead of nylon-6,6 to MX nylon, the advantages of MX nylon (mechanical strength, The inventors have discovered that the above-mentioned difficulties can be solved while maintaining the rigidity, dimensional accuracy, low water absorption, etc., and have arrived at the present invention.

In the present invention, the polyamide resin having tetramethylene adipamide as a main structural unit (hereinafter referred to as "rTM nylon") used as component (b) may be a tetramethylene adipamide homopolymer. It may be a copolymer with methylene adipamide as the main structural unit and a copolymerizable component copolymerizable with this. Examples of the copolymerization component include amino acids such as 6-aminocaproic acid, lactams such as ε-caprolactam, diamines such as hexamethylene diamine, and dicarboxylic acids such as adipic acid and superric acid. Also, (b) of the present invention
The component polyamide includes polyamides other than polytetramethylene adipamide (e.g. 6-nylon, 6.6-
Nylon, 6.10-nylon, 6.12-nylon,
12-nylon, etc.) may be incorporated into the total component (b) in an amount not exceeding about 15%.

The 7M nylon of the present invention can be easily produced according to a conventionally known method, for example, the method disclosed in JP-A-56-149430, JP-A-56-149431, and JP-A-58-83029. be. A typical manufacturing method is to first manufacture a prepolymer with a small amount of cyclic end groups under specific conditions, and then solid-phase polymerize it in a steam atmosphere to prepare high viscosity polytetramethylene adipamide. Examples include a method of heating raw material monomers in a polar organic solvent such as N-methylpyrrolidone, and the like.

The degree of polymerization of the 7M nylon used in the present invention is not particularly limited, but the relative viscosity (measured at 25°C using a 96% sulfuric acid 10011112 solution of 1.0 g of polymer) is 2.3 to 6. 7M nylon having a relative viscosity of about 0 is preferable, and 7M nylon having a relative viscosity of about 2.5 to 5.0 is more preferable.

When the relative viscosity of 7M nylon is lower than 2.3, the mechanical properties of the resulting molded product tend to deteriorate, and conversely, when the relative viscosity of 7M nylon is higher than 6.0, component (a) tends to deteriorate. Both are unfavorable because they tend to have poor uniform meltability with certain MX nylons, resulting in poor moldability and unstable performance.

The blending ratio of component (a) and component (b) is usually a weight ratio of 80 to 97:20 to 3, preferably 90 to 95:10 to 5 by weight.

If the amount of 7M nylon exceeds 20 parts by weight, the characteristics of MX nylon, which is low water absorption and very good dimensional accuracy among nylon resins, will be lost, and if the amount of 7M nylon is more than 20 parts by weight, Even if it is added, it is not appropriate because it hardly contributes to further shortening the molding cycle.

Furthermore, when the blending amount of 7M nylon is less than 3 polymerization parts, the effect of promoting crystallization due to the addition of 7M nylon is hardly recognized, and the heat deformation temperature of the obtained molded product is low, and depending on the ambient temperature in which it is used, there is no arning (110 -b Or, it becomes necessary to mold in a high-temperature mold of 120°C or higher, which poses practical problems such as difficulty in applying it to thin-walled products that are susceptible to thermal deformation when released from the high-temperature mold. This is inconvenient because

The shape of the filler used in the present invention is not particularly limited as long as it is solid, such as powder, granule, flake, spherical, etc.
All types of materials such as fibrous materials can be used. Examples of the granular or powdery filler include calcium carbonate, silica, alumina, and clay talc. Examples of the flaky filler include graphite, sericite, and mica. Examples of the spherical filler include glass beads, shirasu balloons, glass balloons, carbon microballoons, and the like. Examples of the fibrous filler include whiskers such as potassium titanate, carbon graphite, and silicone carbide, and inorganic and organic fibers such as glass fiber, carbon fiber, and aramid fiber. Although such fillers can be used even if they are not normally treated, in order to impart affinity between the polyamide resin and fillers, especially fibrous fillers, silane coupling agents, titanate coupling agents, etc. It is preferable to use those treated with a surface treatment agent such as . In the present invention, such a filler is preferably blended in an amount of usually 5 to 230 parts by weight, or preferably 15 to 150 parts by weight, per 100 parts by weight of the total amount of components (a) and (b). If the amount of filler blended is less than 5 parts by weight, it is disadvantageous because the impact resistance of the resulting molded product is significantly reduced. On the other hand, if the blending amount of the filler exceeds 230 parts by weight, the fluidity of the polyamide resin composition tends to decrease significantly, which is undesirable in terms of molding processing.

Depending on the purpose, the polyamide resin composition of the present invention may contain antioxidants, antistatic agents, conductivity imparting agents such as Ketchen Black, ultraviolet absorbers, lubricants, flame retardants, colorants, and PTFE.
Known additives and modifiers such as sliding property imparting agents such as .

When producing the polyamide resin composition of the present invention,
There is no particular limitation, and any conventional method for producing a resin composition can be applied. That is, the means for blending each component is not particularly limited, and the above (a) component, (b) component, and filler may be premixed in advance using a Henschel mixer, tumbler mixer, etc., or each may be mixed separately using a melt mixer. may be melted and kneaded.

Effect of the invention According to the present invention, the following effects are achieved.

(1) If the resin composition of the present invention is used, a high temperature mold (13
The molding cycle time at 0° C.) can be significantly shortened.

(2) Even in a low-temperature mold (90 to 100°C), the crystallization promoting effect can improve the heat distortion temperature of a molded product obtained by molding the resin composition of the present invention.

(3) The mechanical properties of molded products obtained by molding the resin composition of the present invention can also be significantly improved.

(4) The resin composition of the present invention can be suitably used as a molding material (particularly an injection molding material) in the field of thin-walled molding materials, for example, in the field of ultra-small thin-walled molded products such as clock gears. can be done.

Example Examples are given below to further clarify the present invention.

Hereinafter, the term "parts" simply means "parts by weight."

Examples 1-3, Comparative Examples 1-2 and Reference Example 1 Relative viscosity is 2
．． Polymethaxylylene adipamide (hereinafter referred to as nylon MX6j) having a relative viscosity of 3.
Pellets of polytetramethylene adipamide (hereinafter referred to as nylon TM6J), which is No. 37, were mixed at a blending ratio of nylon TM6 to nylon MX6 of 10010.951.
Potassium titanate single crystal fiber [Tismo D-102, manufactured by Otsuka Chemical ■, average fiber diameter 0.3 μm, average fiber length 14 μm, aspect ratio 47, treated product with 1% by weight of epoxy silane added] 43
parts were supplied from the main hopper and side hopper of a twin-screw extruder [PCM45, manufactured by Ikegai Iron Works], respectively.
The mixture was melt-kneaded at a cylinder temperature of 280 to 300°C, and the resulting strands were cooled in a water bath, pelletized with a pelletizer, and dried to obtain a molding resin composition.

These resin compositions were heated to a mold temperature of 130°C using an injection molding machine.
A bending strength test piece specified in JIS K7203 was injection molded as °C, and the cooling time required until the surface hardness of the molded product reached 30 or 40 in Percoll hardness immediately after opening the mold was measured. If the Percoll hardness is less than 30, the material that has entered the mold has not yet solidified sufficiently and is soft, causing the ejector pin used to push the molded product out of the mold to slip into the molded product, or the molded product to be deformed. A phenomenon was observed. The results and the bending property measurement results are summarized in Table 1 below. As a reference example, Table 1 also shows the results when 10 parts of conventionally known nylon-6,6 was used instead of nylon TM6.

From Table 1 above, the effect is great when the amount of nylon TM6 is 5 to 18 parts, and the effect of its addition is that the required cooling time is less than half that of the case without additives. It is clear that it is possible to shorten the length by about 30% compared to nylon 6, and furthermore, in terms of mechanical properties, it is recognized that there is a considerable improvement effect over the conventional addition of nylon-6,6.

The improvement effect decreases when the amount of nylon TM6 added exceeds 20 parts, and considering that the effect of promoting crystallization (shortening the cooling time) remains the same, the amount of nylon TM6 added is 3 to 3 parts. It can be determined that 20 copies is appropriate.

Example 4 and Reference Example 2 The same pellets used in Example 2 and Reference Example 1 were heated to a cylinder temperature of 290°C, a mold temperature of 90°C, and a mold temperature of 100°C using a flat plate mold with a wall thickness of 1° and 16°. Two levels of ℃ were taken, and molding was carried out at an injection pressure of 600 kg/c 2.
Based on JIS K7207, measuring load 18,
The heat distortion temperature was measured at 5 kgf/c+a2. The results are shown in Table 2 below.

Table 2 From the results in Table 2 above, it is clear that the use of the nylon TM6 of the present invention is better than the use of nylon-6,6 as a crystallization accelerator when molded at mold temperatures of 90°C and 100°C. The heat deformation temperature of molded products is high, and products using nylon TM6 can be used up to 100°C even if molded at a mold temperature of 90°C, whereas products using nylon-6,6 can be used without arning. Otherwise, it will be difficult to use it at 100°C.

Examples 5-7 and Comparative Examples 3-4 Same nylon MX692 as used in Examples 1-3
Various pellets (polyamide resin composition for molding) were similarly produced using the formulations listed in Table 3 below, using 100 parts of polyamide resin in which 100 parts of polyamide resin and 8 parts of nylon TM6 were mixed in advance in a tumbler mixer. Evaluations similar to Examples 1 to 3 were performed. The results are shown in Table 3 below.

The fired clay, mica, and glass fiber in Table 3 were as follows.

Firing Ray: 5atintone 5special
, average particle diameter 1.2 am, Engelhard Micanissilite Mica 200-Kl (surface treatment grade), weight average flake diameter 90 μm 1 weight average aspect ratio 50, ■Glass fiber Nigelathlon C manufactured by Kuraray
303MA416, aminosilane treated product, fiber length 3 m
m s Made by Asahi Fiberglass ■ From Table 3 above, regardless of the form of the filler, and Example 8
So, even if two or more of these fillers are combined, by blending 5 to 230 parts of the filler to 100 parts of the polyamide resin, the cooling time can be significantly shortened, and the mechanical properties can also be significantly improved. is clear.

(that's all)

Claims (1)

[Scope of Claims] [1] (a) xylylenediamine and α having 6 to 12 carbon atoms
, ω-linear aliphatic dibasic acid, and (b) a polyamide resin obtained by mixing 20 to 3 parts by weight of a polyamide resin whose main constituent unit is tetramethylene adipamide. A molding polyamide resin composition comprising 5 to 230 parts by weight of a filler per 100 parts by weight. [2] The polyamide resin whose main structural unit is tetramethylene adipamide has a relative viscosity of 2.3 to 6.0 (96%
The composition according to claim 1, which is polytetramethylene adipamide (sulfuric acid, 25°C).