JPS58201844A - Preparation of highly crystallized polyamide molded article - Google Patents

Abstract

PURPOSE:To obtain the titled molded article having improved mold shrinkage and dimensional change by water-adsorption, by compounding a polyamide with fine powder of nylon 46 having high rate of crystallization, and melting and molding the compound. CONSTITUTION:A polyamide, especially a high polymeric polyamide having a melting point of 200-290 deg.C is compounded with 0.01-5wt% of the fine powder (e.g. passing through a 50mesh sieve) of nylon 46 (having melting point of 270- 295 deg.C) as a meltable and crystallization-accelerating uncleation agent. The mixture is molten and molded at a temperature higher than the melting point of nylon 46 (e.g. 270-330 deg.C) to obtain the objective highly crystallized polyamide molded article having lower melting point than nylon 46.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a highly crystallized polyamide molded article, which includes blending a nucleating agent capable of melting and promoting crystallization during melt molding of polyamide.

In general, polyamide molded products have excellent mechanical properties and are widely used as industrial materials such as fiber materials, membrane molding materials, and structural materials.
It has the drawbacks of high thermal shrinkage and poor dimensional stability. - Membrane molded products have large mold shrinkage rates and water absorption dimensional changes, and improvements in polyamide molded products are desired from the viewpoint of moldability and productivity.

The inventors of the present invention have conducted extensive research to improve these drawbacks, and as a result have arrived at the present invention.

That is, in the present invention, when melting and molding lyamide-resistant resin having a lower melting point than nylon 46, 0.01 to 5% by weight of fine powder of nylon 46 is blended, and the melting of nylon 46 (■ melt molding at a high temperature) is carried out. The gist of this paper is a method for producing a highly crystallized polyamide molded article characterized by the following.

In the present invention, nylon 46 is a copolyamide containing 80 mol% or more of polytetramethylene adipamide and tetramethylene adipamide units, and has a melting Q of 295~
270°C.

Nylon 46 has a good molecular symmetry and has a crystallization rate several times faster than nylon 66, which is conventionally considered to be a polyamide with a high crystallization rate.

In the present invention, nylon 46 acts as a nucleating agent and must be blended in the form of fine powder, and melt molding must be performed at a humidity higher than the melting point of nylon 46. During melt molding, nylon 46 is uniformly melted and dispersed in the polyamide used for molding, but it first crystallizes during the cooling process of the molded product, and due to the fast crystallization rate, it can be used for molding. It is thought that this effectively generates crystal nuclei in the polyamide and promotes the crystallization of the molded product during the subsequent cooling process of the molded product.

Conventionally, the method of adding a crystal nucleating agent when manufacturing a polyamide molded article by melt molding is well known, and Japanese Patent Publication No. 44-3509 describes the addition of nylon 6T to nylon 66 or nylon 68.

For nylon 66/6T, Japanese Patent Publication No. 49-47261 proposes a method of adding nylon 66 containing highly melting and unique spherulites to nylon O. All of these conventional methods require spinning at a temperature lower than the melting point of the polymer added as a crystal nucleating agent.

In all of the above proposals, a crystal nucleating agent with a melting point higher than the melting point of the polymer to be molded is dispersed by a solution method, a master chip method, etc., and the nucleating agent is molded without melting.
The purpose is to discover the effect of nucleating agents, and the effect of nucleating agents can be said to be essentially the same as that of inorganic nucleating agents (iron powder, glass powder, Ti02), etc.

Unexamined Japanese Patent Publication No. 5, as a method of molding at a temperature higher than the melting point of the nucleating agent.
The method of No. 2-18919 is mentioned. In this method, fine powder of nylon 66/6T is added to nylon 6 and spun at a temperature higher than the melting point of the nucleating agent nylon 6676T, but the effect is not so significant. The melting point of the nylon 66/6T used is 270-330°C,
This is thought to be due to the slow crystallization rate of the nucleating agent itself during melt cooling.

For the effectiveness of a polymer nucleating agent, it is not sufficient that it has excellent compatibility with the polymer used for molding and that the melting point of the nucleating agent is higher than the melting point of the polymer used for molding. Even after the nucleating agent is once melted, the nucleating agent effect is diminished during the cooling process.

In the case of a so-called melting nucleating agent, the crystallization rate of the nucleating agent itself must be extremely fast.

Nylon 46Fi in the present invention satisfies all of these requirements.

The polyamide to be melt-molded in the present invention has a melting point lower than 295°C (and the polyamide resin which is melt-molded at a temperature higher than 270°C, especially has a melting point of 200 to 290°C).
Polyamides having a high degree of polymerization are suitable.

A specific example is nylon 4. nylon 6, nylon 6
6. Nylon 610. Examples include nylon 410 and copolyamides thereof. Preferred examples of copolyamides include copolyamides with improved rigidity (7) in which aromatic amide units are introduced, such as those in which all paraphenylene terephthalamide units are introduced into nylon 66.

The melt molding temperature is determined by the melting point, molecular weight, melt viscosity, etc. of the polyamide to be molded.

The temperature must be higher than 270°C, which is higher than the melting point of the nylon 46 (copolyamide) incorporated as a nucleating agent. There is no particular upper limit to the melt molding temperature, but if the temperature is too high, it will be impossible to obtain a good molded product due to thermal decomposition of the polyamide, so in general! It is assumed to be below +30°C.

The crystallization rate is indicated by the difference ΔT (degree of supercooling) between the melting point (Tm) of the polymer and the crystallization temperature determined by a differential calorimeter (DSC). The smaller the ΔT, the faster the crystallization occurs during the process of cooling below the melting point. When the temperature drop rate is set to 80''~min, N a y 6 (T
m = 225-fl), nylon 66 (Tm = 26
5°C).

The ΔT of nylon 46 homopoly-q-(Tm=295°C) is 115°C, 65°C, and 950°C, which further corresponds to the rate of temperature drop during the production of molded products such as plastics, films, and fibers. DSC under faster descent speeds
In the measurement, a larger difference in ΔT appears. Nylon 66/6T ij copolyamide also has a crystallization rate similar to or lower than that of nylon 66.

The object of the present invention is to use a nylon 46 nucleating agent with a high crystallization rate in an amount of 0.01% by weight or more based on the total amount of the molded product, preferably 0.01% by weight or more based on the total amount of the molded product.
This can be achieved by adding 0.05% by weight or more and 5% by weight or less. If it is less than 0.01% by weight, the effect is not sufficient;
When the amount added is greater than 96% by weight, an increase in the number of thread breakages during spinning or modification of the polyamide used for molding is observed.

According to the method of the invention, the particle size of the polymeric nucleating agent is.

A microstructurally uniform fiber can be obtained even if the diameter is on the order of one-tenth of the diameter of the undrawn yarn, and in the case of plastics, even if the particle size is coarser than that of fibers, the present invention can be used. You can reach your goal. The effects of the molten nucleating agent of the present invention on molded products include increasing the strength of molded products, improving Young's modulus,
This is brought about by improvements in the crystallinity of the molded product, such as reductions in hot water shrinkage and thermal deformation.

In carrying out the present invention, textiles, plastics.

As the conditions for melt forming a film, etc., it is possible to adopt up to four of the conditions for the case where no nucleating agent is added. In addition, upon melt molding, there are nine types of additives used in combination, such as heat resistance, light resistance, #oxidizing agent, pigment, etc., and there are no particular limitations on the amounts.

Next, the present invention will be explained in more detail with reference to Examples.

In addition, DSC measurement method, molding of test piece, melt spinning
The stretching and evaluation methods were as follows.

(1'l DSC measurement: 8η of the molded product sample was weighed, and the measuring device was equipped with a bar key
A model SO-1 manufactured by Perkin 7 E5mer was used.

The measurement was performed in a nitrogen atmosphere, and the temperature was raised to 295°C at a rate of 1σC15+, held for 5 minutes, and then heated to 10"C.
Cooling is performed at a constant rate of /%, and the endothermic peak temperature due to melting (
Tms ) and exothermic peak temperature based on crystallization (Tcs
') was sought. ΔTs = Tms − Tcs, Δ
The smaller T8 is, the higher the crystallization rate of the molded article is.

(2) A molded polyamide pellet as a test piece and a predetermined amount of fine powder (50%
After blending the molding machine (TS made by Nisshin Jushi Co., Ltd.)
-150), tg degree profile 250”C-27
Molding was carried out at 0°C-280°C. Molding was carried out by setting the mold temperature to 80"CK number, setting the injection time to 15 seconds, and varying the cooling time.

(3) Mold releasability and deformation mold releasability were determined by separation from the mold from the cavity during molding and by coming off the spool.

Good: 0 Slightly poor: △ Poor: × Deformation of the test piece during extrusion (knockout) was determined by moving the test piece using a dial gauge on the surface plate.

The difference between the maximum thickness due to deformation of the test piece and the thickness of a good test piece is displayed as the amount of deformation. However, the test piece size is 1
/2'X 1/2'X 5' rectangular piece.

(4) Measurement of tensile strength An ASTM-1/8' dumbbell test piece was formed using the method of (3).

Using this, tensile strength was measured according to ASTM-D63B.

(5) Spinning and stretching by melt spinning/stretching spin draw method, 126[]d/7
A 10 f yarn was obtained, details of which are given in each example.

(6) Relative viscosity: JIS K/)810 4.2.1
(Hayoung's modulus: J Engineering S L1073-19655.10
(8) Heat shrinkage rate (heat loss): JIS T, 1073-
19655.12(a)B Example 1゜ Poly(tetramethylene adipamide/hexamethylene adipamide/hexamethylene a9-civamide) (molar ratio 80/20, Tm = 272) was added to nylon 66 pellets with a relative viscosity of 6.0.
A fine powder (passed through 50 meshes) obtained by pulverizing the powder (100°C) was mixed well in the proportions shown in Table I, and injection molding was performed according to the method described above.

The results are shown in Table IK.

Table 1 10- Example 2 Fine powder of poly(tetramethylene adipamide/hexamethylene adipamide) (molar ratio 90/10, Tm = 283°C) ground into nylon 6 chips with a relative viscosity of 6.3 (passed through 100 meshes) was added in the amount shown in Table 1, mixed well, and melt-spun at a spinning temperature of 292°C.
After applying water-based emulsion oil, temperature: 70°C, peripheral speed: 4
It is taken up by a roller of 50 m/min, and the temperature of the roller is 140°.
The first stage is stretched to 5.5 times with the first stretching row of C.
While the first stretching roller and the second stretching roller at a temperature of 150°C are in contact with a hot plate at 200°C, the second stretching roller is
It was drawn in stages to produce a drawn yarn of 1260d/210f.

The results are shown in Table IK. 5 in the table is a comparative example using a nucleating agent of nylon 66/6T (molar ratio 80/20, Tm=273°C).

Table 1 Example 3 A fine powder (passed through 100 meshes) of polytetramethylene adipamide (Tm=') 95°C) was added to a nylon 66 chip with a relative viscosity of 3.1 in the amount shown in Table 1. After mixing well, melt-spinning at a spinning temperature of 3[]0°C,
After applying water-based emulsion oil, temperature: 80°C, circumferential speed: 4
00+n/min roller and temperature 150
The first stage of stretching is carried out by 3.0 times between the first stretching roller at 170°C, and the first stretching is carried out while contacting a hot plate at 220°C between the first stretching roller and the second stretching roller at 170°C. A second stage drawing was carried out to 7 times, and a drawn tip of 12601/210f was produced.

The results are shown in the table below. &5 in the table is nylon 66/6T (
This is a comparative example using a nucleating agent with a molar ratio of 65/35 and Tm=290″C).

Front yo -13=

Claims (1)

[Claims] (1) When melt-molding polyamide with a lower melting point than nylon 46, 0.01 to 5 weight percent of fine powder of nylon 46 is blended and melt-molding is performed at a temperature higher than the melting point of nylon 46. A method for producing highly crystallized polyamide molded products.