JPH07138478A - Production of polyamide molded body - Google Patents

Abstract

PURPOSE:To easily obtain a polyamide molded body in high efficiency, excellent in mechanical strength and sliding characteristics and heat resistance, useful for industrial products, etc., by adding a specific N-acyllactam to a specific polyamide resin composition during its kneading in a molten state to conduct a reaction followed by molding. CONSTITUTION:(A) A bifunctional N-acyllactam of formula II (X is an alkyl or an aromatic group; R is an alkyl) is added to a polyamide resin composition prepared by incorporating a total of 100 pts.wt. of (B) 60-90wt.% of nylon 46 resin and (C) 40-10wt.% of nylon 6 or nylon 66 resin satisfying the relationship I ([NH2] and [COOH] are terminal amino group level and terminal carboxyl group level expressed by g eq./10<6>g, respectively) with (D) 5-40 pts.wt. of an inorganic filler, during its kneading in a molten state to conduct a reaction, followed by molding to a specified shape, thus obtaining the objective molded body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyamide molded article, and more particularly to a method for producing a nylon 46 molded article having a high molecular weight during melt molding.

[0002]

Nylon 46 made from tetramethylenediamine or its functional derivative and adipic acid or its functional derivative is excellent in mechanical strength such as tensile strength, bending strength, impact strength, heat resistance and sliding characteristics. Because it is also excellent, it has great utility value as a useful engineering plastic.

Conventionally, this resin is mainly produced by injection molding,
General-purpose polyamide centered on nylon 66 has heat resistance,
It has been applied to applications where sliding properties, chemical resistance, etc. are insufficient. However, recently, product development by blow molding has been actively carried out centering on the air intake around the engine and the intake manifold, and general-purpose polyamide lacks heat resistance. Development has come to be required. Further, in order to develop new applications, the development of nylon 46 suitable for extrusion molding mainly on pipes is also required.

In order to be compatible with these molding methods, it is desirable that the viscosity is high and the crystallization rate is slow. However, since nylon 46 has a low viscosity when melted and has a high crystallization rate, blow molding or extrusion molding is difficult with ordinary nylon 46. In order to be compatible with these molding methods, it is necessary to increase the viscosity at the time of melting, and there is a strong demand for a method for manufacturing a molded product using high molecular weight nylon 46.

In the meantime, in order to obtain a high-molecular weight molded product, the conventional method is to melt-mold a high-molecular-weight chip in a kneader such as an extruder, but in the case of nylon 46, the resin By nature, it is difficult to increase the molecular weight by an economical method.

That is, since the melting point is as high as 290 ° C. and it is close to the decomposition point of the resin, it is impossible to reach the degree of polymerization which can be used as a molded product by the usual melt polymerization method.
The special solid-state polymerization method described in JP-A No. 0 and JP-A-56-149431 must be used. Therefore, in order to further improve the degree of polymerization, it is necessary to adopt more severe solid-state polymerization conditions. This not only has low productivity, but it is difficult to control the degree of polymerization. On the other hand, as another method for obtaining a polyamide having a high degree of polymerization, British Patent No. 69364 discloses a method in which a chain linking agent of bis-N-acyllactam is added during the polymerization of polyamide. -1
Japanese Patent No. 71732 proposes a method in which a carbamoyllactam type chain linking agent is added to polyamide and reacted in an extruder. However, in the case of nylon 46, the former method by melt polymerization cannot be adopted,
In the latter method, the effect of increasing the degree of polymerization of the polymer obtained is small and unsatisfactory.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and makes it possible to increase the molecular weight of nylon 46 without using the solid-state polymerization method, which has low productivity and is difficult to control the degree of polymerization. It is an object of the invention to provide a method for

The present inventors have already proposed a method for obtaining a high-molecular-weight nylon 46 molded body in Japanese Patent Laid-Open No. 3-62826. In this method, amino terminal groups of 46 molecules of nylon are linked with a biscaprolactam compound to increase the molecular weight. However, after the examination,
It has been found that the number of amino terminal groups of nylon 46 is not always stable, and when the number of amino terminal groups is small, a sufficient effect of increasing the molecular weight is not exhibited. The present invention relates to a method for efficiently obtaining a high-molecular-weight nylon 46 molded product even under such circumstances.

[0009]

The present inventors have arrived at the present invention as a result of extensive studies aimed at achieving the above object.

The present invention relates to (A1) nylon 46 resin 60
~ 90% by weight and (A2) nylon 6 satisfying the following formula
Resin and / or nylon 66 resin 40 to 10% by weight

[0011]

## EQU2 ## [NH ₂ ]-[COOH]> 20 [wherein, [NH ₂ ] and [COOH] represent the amount of terminal amino group and the amount of terminal carboxyl group in gram equivalent / 10 ⁶ gram unit, respectively. ] The polyamide resin composition prepared by blending 5 to 40 parts by weight of the inorganic filler (B) with 100 parts by weight of a polyamide resin mixture containing the above and a bifunctional N-acyl lactam are reacted in, for example, a melt kneader. A method for producing a polyamide molded body, which comprises molding into a desired shape while performing the above.

The present invention will be described in detail below.

The component (A1) nylon 46 resin used in the present invention is a polyamide obtained by a condensation reaction using adipic acid or its functional derivative as the acid component and tetramethylenediamine or its functional derivative as the amine component. However, a part of the adipic acid component or the tetramethylenediamine component may be replaced with another copolymerization component.

Preferred embodiments of the nylon 46 resin are JP-A-56-149430 and JP-A-56-14943.
No. 1 publication.

The nylon 6 resin as the component (A2) used in the present invention is a washing polymer obtained by polymerizing ε-caprolactam, and ε-caprolactam can be used as long as the basic properties of the nylon 6 resin are not impaired. Other monomers may be copolymerized or blended. Here, in order to prepare a nylon 6 resin having more amino terminal groups than carboxyl terminal groups, it is necessary to add a small amount of an amine component to ε-caprolactam for polymerization. In this case, the amine component may be a monoamine, but it is more advantageous to use a diamine from the viewpoint of polymerization rate. Examples of the diamine include hexamethylenediamine, aliphatic amines such as m-xylylenediamine, and aromatic amines such as p-phenylenediamine and m-phenylenediamine. Any heat-stable one may be used. .

The component (A2) nylon 66 resin used in the present invention means polyhexamethylene adipamide and polyamide containing hexamethylene adipamide unit as a main constituent, and is a conventional melt polymerization method, that is, a raw material. It can be obtained by a method in which a substantially equimolar salt of hexamethylenediamine and adipic acid is charged into a polymerization tank together with water and polymerization is carried out at a temperature of about 250 to 300 ° C. under normal pressure, increased pressure, or reduced pressure. At this time, a nylon 66 resin having a larger amount of amino terminal groups than the amount of carboxyl terminal groups can be obtained by adding a small amount of an amine component and polymerizing the same as in the case of the nylon 6 resin.

Here, an important requirement for the component (A2) is the amount of the terminal group,

[0018]

## EQU3 ## [NH ₂ ]-[COOH]> 20 [wherein, [NH ₂ ] and [COOH] represent the amount of terminal amino group and the amount of terminal carboxyl group respectively in gram equivalent / 10 ⁶ gram unit. ] It is necessary to satisfy the condition of. If this condition is not satisfied, the final polymerization degree will not be high, so that high viscosity during molding cannot be obtained.

The ratio of the components (A1) and (A2) in the present invention is 60 to 90:40 to 10 by weight.
The component (A2) is an essential component for obtaining a high viscosity during molding and a moderate decrease in crystallization rate, and the ratio thereof is 10 w.
If it is less than t%, this improvement effect is small, while 40%
When the content exceeds wt%, the heat resistance represented by HDT (load deflection temperature) and the like decreases, and the characteristics of nylon 46 are impaired, which is not preferable.

The inorganic filler as the component (B) used in the present invention includes powdery and fibrous fillers. Examples of the powdery filler include kaolin, wollastonite, talc, mica, calcium carbonate, glass flakes and the like. Examples of the fibrous filler include glass fiber, aramid fiber, carbon fiber, potassium titanate whiskers, boron whiskers, and the like, and two or more kinds of them can be used in combination. These fillers have the effects of increasing the heat resistance expressed on a scale such as HDT and increasing the viscosity during molding. The addition amount is 5 to 40 parts by weight with respect to 100 parts by weight of the polyamide resin mixture composed of (A1) and (A2). If the amount is less than 5 parts by weight, the heat resistance of the obtained molded article becomes low, and the characteristics of nylon 46 resin are lost. If it exceeds 40 parts by weight,
Although it has the effect of increasing the heat resistance, it is not preferable because the extensibility during blow molding is impaired. Among these inorganic fillers, glass fiber is particularly preferable, and the glass fiber is not particularly limited as long as it is generally used for reinforcing resin.
These may be coated with a sizing agent (for example, a polyurethane-based or polyvinyl acetate-based sizing agent), a coupling agent (for example, a silane compound or a borane compound), or another surface treatment agent.

The bifunctional N-acyl lactam compound used in the present invention is represented by the following general formula.

[0022]

[Chemical 1]

(Here, X represents an alkyl group or an aromatic group, and R represents an alkyl group.) Specific examples of the compound represented by the general formula are N, N'-isophthaloylbis-ε-. Caprolactam, N, N'-adipoylbis-ε-valerolactam, N, N'-isophthaloylbisvalerolactam, N, N'-isophthaloylbisbutyrolactam, N, N'-isophthaloylbisbutyro A lactam etc. can be mentioned.

These compounds can be easily synthesized by reacting the corresponding carboxylic acid dihalide and lactam in the presence of an inorganic alkali such as amine or KOH.

In the present invention, a polyamide resin composition obtained by blending (B) with a polyamide resin mixture consisting of (A1) and (A2) is reacted with a bifunctional N-acyl lactam in advance. A general method is to dry-blend and melt-knead this.

The amount of the bifunctional N-acyl lactam added to the nylon 46 is preferably 0.5 to 3.0 times the equivalent amount of the acyl group based on the amino terminal group amount of the nylon 46, and the highest molecular weight is preferable. It is 1.0 to 2.0 to obtain. On the contrary, if the amount added is too large, the molecular weight decreases.

The melting temperature at this time is 5 to 30 ° C., preferably 5 to 15 ° C. higher than the melting point of nylon 46, and the kneading time is 1 to 15 minutes, preferably 2 to 6 minutes.

According to the present invention, it is possible to increase the degree of polymerization of nylon 46, which results in an increase in viscosity during melting and a decrease in crystallization temperature. As a result, it becomes possible to manufacture a molded body by blow molding or extrusion molding, which has been difficult in the past, and it becomes possible to utilize nylon 46 resin beyond the frame of injection molding.

[0029]

EXAMPLES Examples will be described below, but the present description is not limited thereto. In addition, the measurement of various characteristics in Examples and Comparative Examples was performed by the following methods.

(1) Intrinsic viscosity [η] Polymer 0.2, 0.4 and 0.8 g are each added to 100
Dissolve in ml of meta-cresol and ηrel at 35 ℃
Measure (t / t ₀ ). Next, each concentration c (g / 100
(ηrel-1) / c is plotted against (ml) and [η] is calculated from the extrapolated value (c → 0) of the straight line obtained from the three points.

(2) Amount of Terminal Group The amount of amino terminal group [NH ₂ ] was determined by dissolving the polymer in m-cresol and titrating with 0.01N p-toluenesulfonic acid. The amount of terminal carboxyl groups [COOH] was determined by dissolving the polymer in benzyl alcohol and titrating with 0.1 N sodium hydroxide.

(3) Deflection Temperature Under Load (HDT) According to ASTM D648, the load was measured at a load of 264 Psi and a specimen thickness of 1/4 inch.

(4) Melting point and crystallization temperature Differential Scanning Calo made by Du Pont Instruments
Rimeter 910 type, temperature rising / falling rate 20 ° C / min, 33
The measurement was carried out at a holding time of 3 minutes at 0 ° C.

The following materials were used in Examples and Comparative Examples. As component (A1) nylon 46, STANYL KS300 and KS400 manufactured by DSM Co. of the Netherlands were used. As the constituent component (A2) nylon 6 and nylon 66, the following (a) to (d) were used. (A) [η] = 1.41, [NH ₂ ] = 66 by adding 0.25 mol% of m-xylylenediamine to ε-caprolactam for melt polymerization, washing with hot water and drying.
A chip having [COOH] = 18, water content = 0.05%, and monomer content = 0.2% was obtained. (B) By adding 0.26 mol% of diethylenetriamine to ε-caprolactam, melt-polymerizing, washing with hot water and drying, [η] = 1.08, [NH ₂ ] = 97,
A chip having [COOH] = 28, water content = 0.05%, and monomer content = 0.2% was obtained. (C) [η] = 1.34, [NH ₂ ] = 4 by melt-polymerizing ε-caprolactam, washing with hot water, and drying.
5, [COOH] = 46, water content = 0.05%, and monomer content = 0.2% were obtained. (D) Hexamethylenediamine was added to AH salt in an amount of 0.25 mol%, and the mixture was subjected to melt polymerization to obtain [η] = 1.37, [NH ₂ ]
= 68, [COOH] = 20 chips were obtained. As the component (B) inorganic filler, chopped strand-cut glass fiber (manufactured by Nippon Electric Glass Co., Ltd.) having a length of 3 mm was used.

The polyamide resin mixtures of Examples and Comparative Examples were extruded and pelletized by a twin-screw extruder (TEX44, manufactured by Japan Steel Works) at a cylinder temperature of 270 to 330 ° C. A predetermined amount of N, N′-terephthaloylbiscaprolactam powder was dry-blended to the obtained pellets, and an injection molding machine (IS60B, manufactured by Toshiba Machine) molding temperature 305 ° C., mold temperature 120 ° C., molding cycle 35 Molded in seconds to obtain a test piece for evaluation. As examples and comparative examples, the compositions and the evaluation results of the above items are shown in Tables 1 and 2.

[0036]

[Table 1]

[0037]

[Table 2]

The blow moldability of icicles was determined by the following method. Direct blow molding machine (SE5I / BA
2, manufactured by Sumitomo Heavy Industries), cylinder temperature 270-29
A rectangular shaped body was blow-molded at 0 ° C. and a die head temperature of 270 to 280 ° C., and it was judged from the drawdown property during molding, the wall thickness, the presence or absence of rupture during blowing, the surface property and the like.

[Examples 1 to 10 and Comparative Examples 1 to 8] In Examples 1 to 3, [η] was increased and good blow moldability was obtained. On the other hand, Comparative Examples 1 and 3 do not use biscaprolactam and have a low [η]. Although Comparative Example 2 uses biscaprolactam, since it does not contain the component (A2), it has a low [η] and a low blow moldability.

Examples 4 to 6 are examples in which the kinds of the components (A1) and (A2) are changed, and similar effects can be obtained. Comparative Example 4 is an example in which nylon 6 which does not satisfy the condition of [NH ₂ ]-[COOH]> 20 is used as the component (A2).
₂ ] is small and the [η] up effect does not appear. Also, in Comparative Example 7 in which the amount of nylon 6 is increased, the HDT becomes low,
The characteristics of nylon 46 are lost.

Example 7 is an example in which the amount of viscaprolactam is small, but when it is too large (Comparative Example 5), [η] is used.
Is low, which is not preferable.

Comparative Example 8 is an example in which the component (B) is not contained, and although [η] increases, the HDT becomes too low, which is not preferable. On the other hand, if the glass fiber is too much (Comparative Example 6), the elongation fluidity is impaired and the blow moldability becomes poor.

In Examples 9 and 10, the kind of biscaprolactam was changed, and similar effects were obtained.

[0044]

The present invention is based on (A1) nylon 46 (A
2) By increasing the molecular weight by reacting a polyamide resin composition composed of nylon 6 (and / or) nylon 66 and (B) an inorganic filler satisfying specific conditions with a bifunctional N-acyl lactam as a chain linking agent, A new resin molding material that can be used for blow molding or extrusion molding while maintaining the heat resistance of nylon 46 was obtained.

Claims (3)

[Claims] 1. (A1) 60 to 90% by weight of nylon 46 resin and (A2) 40 to 10% by weight of nylon 6 resin and / or nylon 66 resin satisfying the following formula: [NH ₂ ]-[COOH ]> 20 [wherein [NH ₂ ] and [COOH] represent the amount of terminal amino groups and the amount of terminal carboxyl groups in gram equivalent / 10 ⁶ gram unit, respectively.] ] To a polyamide resin composition prepared by blending 5 to 40 parts by weight of an inorganic filler (B) with 100 parts by weight of a polyamide resin mixture consisting of A method for producing a polyamide molded product, which comprises forming the product into a predetermined shape after the forming. 2. The amount of bifunctional N-acyl lactam added is
The method for producing a polyamide molded product according to claim 1, wherein the amount of acyl groups with respect to the amount of amino terminal groups of the polyamide resin composition (mixture) is in the range of 0.5 to 3.0 times equivalent. 3. The bifunctional N-acyl lactam is N, N-terephthaloylbis-ε-caprolactam.
The method for producing a polyamide molded body according to 1.