JPS6033852B2 - Polyamide resin composition for molding - Google Patents

Description

[Detailed description of the invention] The present invention relates to polyamide resin compositions.

More specifically, the present invention relates to a molding polyamide resin composition that provides a molded article with improved physical performance and molding workability in a molding composition of a xylylenediamine-based polyamide resin. Already, glass fibers have been applied to xylylene diamine polyamide resin (hereinafter abbreviated as "MX nylon") synthesized from xylylene diamine whose main component is meta-xylylene diamine and Q,■-linear aliphatic basic acid. Alternatively, it is well known that by adding and reinforcing carbon fiber, a polyamide resin molding material with excellent chemical, thermal, and mechanical properties that could not be obtained with resin alone can be obtained (Japanese Patent Publication No. 1986-6144 number, Nippon Tokukai 1977
No. 1-63860, Japanese Patent Application Publication No. 111547-1982).

However, in glass fiber or carbon fiber reinforced molding materials, the average fiber diameter is 3 to 13 French meters, and the average fiber length is 2 or more square meters, which is a relatively large fiber size, so the gate diameter is 0.5 mm.
When injection molding precision parts such as watch gears with a diameter of 3 skin or less, the injection pressure must be set at 2000 to 40
Even if it is raised to 00k9/ground, it does not pass through the gate, so the desired molded product cannot be obtained.

On the other hand, it does not contain any of these fiber reinforcements, that is,
Natural xylylene diamine polyamide resin is
Of course, injection molding is possible even if the gate diameter is less than 0.3 mm in diameter, but if the molded product to be obtained is extremely thin, such as a gear, the strength and rigidity of natural is insufficient for practical use. It was difficult. Another application is the production of plastic rolls that require surface precision and hardness when hot. Glass fiber or carbon fiber reinforced molding materials can satisfy the hardness when hot, but post-processing (surface polishing) is required. Also, the surface roughness (center line average roughness Ra) is 0.1
It is impossible to finish the surface to a precision of less than 0.05 rm, while with natural, the surface roughness can be finished with an accuracy of less than 0.05 rm, but the hardness when heated is insufficient and it has not been put to practical use. As a result of various studies on various micro-reinforced materials and their surface treatment methods, the present inventors have found a polyamide resin composition for molding that solves these problems and have arrived at the present invention.

Xylylene diamine polyamide resin in the present invention,
In other words, "MX nylon" is a diamine component consisting of metaxylylene diamine alone or a mixture of para-xylylene diamine containing 60% or more of meta-xylylene diamine, and which has 6 carbon atoms, 12 carbon atoms, and 12 carbon atoms.
It is a polyamide resin synthesized by a polycondensation reaction with Q, one or more linear aliphatic dibasic acids such as adipic acid and sebacic acid.

When considering the balance of performance of molded products, the above Q, w
-Adipic acid is particularly excellent among straight-chain aliphatic dibasic acids.

This MX nylon gives molded products with excellent mechanical strength, but on the other hand, it has less crystallization than normal nylon).
To solve this problem, it was previously discovered that adding nylon 66 as a crystal nucleating agent promoted crystallization (Japanese Patent Publication No. 6386/1986), and this paper This crystallization promoting effect is also utilized in the molding composition of the present invention, and the blending of nylon 66 in the molding composition of the present invention is effective over a wide quantitative range in terms of shortening the molding cycle time. However, in consideration of the physical properties of the molded product, it is appropriate that nylon 66 occupies 5 to 15% by weight of the total composition.

The potassium titanate fiber used in the present invention has the general formula K20・nTi02 or K20・nTi02・1
/2day20 (in the formula, n represents an integer of 2 to 8), and specifically, for example, 4-potassium titanate fiber, 6-potassium titanate fiber, or 8-potassium titanate fiber.
A single composition such as potassium titanate fiber or a mixed composition thereof, with an average fiber diameter of 1 French or less, an average fiber length of 5 to 100 French, and an average fiber length/average fiber ridge ratio (
A suitable material has an aspect ratio of 10 or more.

Here, the average fiber diameter, average fiber length, and aspect ratio of the potassium titanate fibers are determined by scanning electron microscopy in at least 5 fields of view and at least 1 field per field of view.
This is based on the results of measurements on fibers that are more than extinct.

When the average fiber diameter, average fiber length, and aspect ratio of the potassium titanate fibers are outside the above ranges, for example, when the average fiber diameter is larger than lr and the average fiber length is smaller than 5 threads, that is, the aspect ratio is smaller than 5. If it is present, the reinforcing effect of the potassium titanate fibers will be small and undesirable.

Furthermore, fibers with an average fiber length longer than 100 mm are difficult to produce industrially and lack practical use. As the potassium titanate fiber used in the present invention, for example, “
There is a product commercially available under the trademark "TISM0" (manufactured by Otsuka Chemicals), which has an average fiber diameter of 0.2.
~0.5mm, average fiber length 10-20 strands, aspect ratio 2
0-100 high strength single crystal whiskers.

The mechanical properties and heat resistance can be significantly improved by incorporating the potassium titanate fibers in the molding resin composition of the present invention in an amount of 5 to 4% by weight; however, if the amount is less than 5% by weight, the improvement effect is not achieved. On the other hand, even if it exceeds 4% by weight, the effect of improving physical properties is small compared to the amount added, and the high density of potassium titanate fibers is significantly lower than that of MX nylon berets, making compounding difficult. It is difficult and therefore not practical.

Although the potassium titanate fibers are effective even if used without being hardened, they cannot be used with ordinary coupling agents such as silane coupling agents such as epoxysilane, aminosilane, acrylic silane, or titanate coupling agents. Surface treatment further improves mechanical properties.

Among them, epoxysilane and aminosilane coupling agents are highly effective, with 0.0% strength against potassium titanate fibers.
It is preferable to add 3 to 5% by weight and subject it to surface treatment.
In order to obtain the molding composition of the present invention, there are various methods for blending potassium titanate fibers into MX nylon, and any method can be selected. Method: A method of adding it just before the end of synthesis; or a method of dry blending the MX nylon pellet obtained in the synthesis with potassium titanate fibers and then melt-extruding them to form pellets. In addition, the molding resin composition of the present invention may contain various additives such as flame retardants, heat stabilizers, and lubricants, depending on the use and purpose, within a range that does not adversely affect the original moldability and physical properties of the composition. One or more types of agents can be added. The polyamide resin composition for molding of the present invention is reinforced with extremely microscopic yet high-strength potassium titanate single crystal fibers. It is now possible to mold ultra-precision parts such as watch gears, which were previously impossible to mold, and the properties such as tensile strength, bending strength, and flexural modulus have been significantly improved, making them increasingly lighter, thinner, shorter, and smaller. This will greatly contribute to technological innovation and resource conservation.

In addition, compared to glass fiber or carbon fiber reinforced materials, mold shrinkage is less variable because it is a microfiber, but the effect of improving heat distortion temperature is also large, and the resulting molded product is Its surface condition is close to that of a natural product, and it can achieve surface precision that could not be achieved with conventional reinforced materials.It is extremely effective in practical use, and is used not only in various precision machines, but also in general exterior and interior parts. It is expected that Hereinafter, the content of the present invention will be explained in more detail with reference to Examples.
These are just one embodiment, and the present invention is not limited to these examples in any way. Examples 1 to 3 and Comparative Examples 1 and 2 Polymer was dissolved in 96% sulfuric acid 100% at 25°C.
A pellet of poly(meth-xylylene adipamide) (hereinafter abbreviated as "nylon MX6J") with a relative viscosity of 2.43 as measured in In addition, as a potassium titanate single crystal fiber, TISMO DI02 (trade name manufactured by Otsuka Chemical ■, average fiber diameter 0.3 mm, average fiber length 14 mm, aspect ratio 47, treated product with 1% by weight of epoxy silane added), In addition to the amount such that the blending ratio in the total amount is 3% by weight, V
After mixing in a mold blender, it is melted and thickened using a screw melt extruder, extruded into a string, cooled through a water bath, cut into pellets using a rotary cutting machine, and dried to obtain a molding composition. I got it.

At this time, the mixing conditions of nylon 66 to nylon MX6, nylon MX6/nylon. 66 to 70/0, 65/5
, 60/10, 55'15, and 50/20.
These molding compositions are heated to a mold temperature of 13°C using an injection molding machine.
A bending strength test piece specified in JIS K7203 was injection molded as 000, and the cooling time required until the surface hardness of the molded product reached 20, 30, or 40 in Barcoll hardness immediately after opening the mold was measured.

The results and the bending property measurement results are summarized in Table 1. Table 1 From Table 1, the appropriate blending amount of nylon 66 is 5 to 15% by weight; if it is less than 5% by weight, the cooling time will be long and there will be problems with moldability, while if it exceeds 15% by weight, It can be seen that this is not desirable because the mechanical properties deteriorate.

Examples 4-7 and Comparative Example 3 Weight % of the same nylon 661 used in Examples 1-3
Nylon MX with a relative viscosity of 2.25 measured in the same manner
Potassium titanate fiber treated with aminosilane (manufactured by Otsuka Chemical Co., Ltd., Tismo DIOI, average fiber diameter 0.3mm, average fiber length 14mm, aspect ratio
47) was added in different amounts to prepare pellet-shaped molding compositions in the same manner as in Examples 1 to 3, and various JIS
Test pieces were injection molded and various physical properties were measured.

The results are shown in Table 2. Table 2 From Table 2, it is clear that when 5 to 4% by weight of potassium titanate fiber is added, the mechanical strength, heat resistance, and molding shrinkage rate are greatly improved compared to natural fibers.

It should be noted that, as described above, in the case of Example 7, it is quite difficult to supply a composition containing more than 40% by weight because the potassium titanate fibers are bulky in the melt extrusion process. In addition, a molding composition prepared in the same manner as the molding composition of Example 6 and containing 3% by weight of glass fiber with a fiber length of 3 skin and the resin composition of Comparative Example 3 were used, and the pinpoint gate diameter was When injection molding was attempted using a mold for a watch gear on the 0.2 side, the molding composition containing glass fiber could not be filled even if the molding pressure was increased to 1500 kg/lump or higher, whereas the comparison In the molding compositions of Example 3 and Example 6, it was possible to sufficiently fill the molding composition even at 500 k9/m.

However, since the composition of Comparative Example 3 had a low heat distortion temperature of 93 qo, demolding was difficult and continuous production was not possible.

Claims (1)

[Scope of Claims] 1. A molding polyamide resin composition comprising 55 to 90% by weight of a xylylene diamine polyamide resin, 665 to 15% by weight of nylon, and 5 to 40% by weight of potassium titanate single crystal fiber. 2. The polyamide for molding according to claim 1, wherein the potassium titanate single crystal fibers are short fibers with an average fiber diameter of 1 μ or less, an average fiber length of 5 to 100 μ, and an average fiber length/average fiber diameter ratio of 10 or more. Resin composition. 3 Potassium titanate single crystal fiber is 0.3 of the fiber weight
The polyamide resin composition for molding according to claim 1, which is treated with a surface treatment agent of 5.0% by weight.