JPH0433954A - Polyamide composition - Google Patents

Abstract

PURPOSE:To obtain a polyamide composition having excellent gas barrier properties, moldability drawing workability and flexibility, by blending a half aromatic polyamide of specific structure with a specific amount of an aliphatic polyamide. CONSTITUTION:(A) 99-1wt.% half aromatic polyamide comprising 5-30mol% structure unit shown by formula I (X is -O-, -S-, etc.; R is 6-15C bifunctional aromatic group; n is 0 or 1) and 99-70mol% structural unit shown by formula II is blended with (B) 1-99wt.% aliphatic polyamide (e.g. nylon).

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to polyamide compositions. More specifically, the present invention relates to a polyamide composition that has high gas barrier properties and is also excellent in moldability, stretching workability, and flexibility.

[Prior Art] In recent years, various resins, specifically ethylene-vinyl alcohol copolymer resins, vinylidene chloride resins, acrylonitrile copolymer resins, and polymer resins have been used for packaging food and beverages that require gas barrier properties. Taxylylene adipamide (
Polyamides such as MXD-6 (hereinafter abbreviated as MXD-6) are used depending on the purpose.

Among these gas barrier resins, MXD・6 is PE.
It is used for multilayer containers co-injected with T and multilayer films co-extruded with various thermoplastic resins such as polyethylene and polypropylene.

By the way, since the melting point of MXD-6 is as high as 240°C, it was necessary to set the resin temperature to 250°C or higher during melt molding. However, such high temperatures induce deterioration of other resins to be coextruded or of the resin used as the adhesive layer.
There was a problem in that the resulting molded products often had fish eyes and trouble ordering gel-like materials.

Furthermore, MXD-6 had problems in drawing workability and flexibility, so it could not necessarily be said to be a fully satisfactory material.

Generally, it is known as a method to lower the melting point of crystalline polyamide and to improve stretching workability by adding an appropriate amount of a copolymer component to either diamine or dicarboxylic acid, or both. However, it has been extremely difficult to lower the melting point and improve the drawing workability of MXD-6 while maintaining its excellent gas barrier properties. Also, as a method to improve the flexibility of MXD-6, it is known to mix an aliphatic polyamide such as nylon-6, but the melting point of MXD-6 is 240.
Because the resin temperature is as high as 250 °C, the resin temperature is
The temperature had to be above °C. Such temperatures tend to induce deterioration of the aliphatic polyamide to be mixed, and there is a problem in that fish eyes and gel-like substances frequently occur in the film of the obtained mixture.

(Purpose of the Invention) In order to solve this problem, the present inventors particularly aimed to
As a result of intensive studies on copolymerization components such as diamines and dicarboxylic acids, it was discovered that by introducing a carboxylic acid component with a specific structure, it is possible to lower the melting point and achieve excellent stretching workability while maintaining gas barrier properties. Furthermore, by mixing an aliphatic polyamide with the above-mentioned semi-aromatic polyamide, a polyamide composition having high gas barrier properties as well as excellent moldability and flexibility was discovered, and the present invention was achieved.

[Structure of the invention]

That is, the present invention provides semi-aromatic polyamide (A) 99-1
A polyamide composition comprising 1 to 99% by weight of an aliphatic polyamide (B) and a semi-aromatic polyamide (A).
) is (a) 5 to 30 mol% of the structural unit represented by the following formula [1]... [1] ([In formula 11, X is 10-, -3-, -NH-R is , represents a divalent aromatic group having 6 to 15 carbon atoms, and n is O or 1
It is. ) (5) The present invention relates to a polyamide composition characterized in that it is a semi-aromatic polyamide composed of 95 to 70 mol% of the structural unit represented by the following formula [11]...[I[].

The present invention will be explained in detail below.

The semi-aromatic polyamide (A) constituting the polyamide composition of the present invention is meta-xylene diamine and a dicarboxylic acid represented by the following formula [11],
and a polyamide composed of adipic acid.

HOzCCHzX (Rχ), ICHzCOzH-[I
II) (where X is -O-, -S-, or -N
-preferably represents 10-. n is 0 or 1.

R represents an aromatic group having 6 to 15 carbon atoms. ) R is specifically: - The dicarboxylic acid represented by the formula [1[r] is iminodiacetic acid, oxydiacetic acid, thiodiacetic acid,
Examples include 1,4-phenylenedioxydiacetic acid, 1°3-phenylenedioxydiacetic acid, and 2,6-naphthalenedioxydiacetic acid. Among these, particularly preferred are oxydiacetic acid and 1,4-phenylenedioxydiacetic acid.

Further, the semi-aromatic polyamide (A) constituting the polyamide composition of the present invention may be copolymerized with a small amount of other diamines other than metaxylene diamine and other dicarboxylic acids other than those mentioned above.

The proportion of the dicarboxylic acid represented by the general formula (II[) among all dicarboxylic acids is 5 to 30 mol%, preferably 5 to 25 mol%. That is, if it is less than 5 mol %, the melting point of the obtained polymer will be lowered to a low degree and the object of the present invention cannot be achieved. On the other hand, if it exceeds 30 mol %, the polymer will be substantially amorphous and the gas barrier during stretching or orientation will be reduced.
It has low commercial value because it cannot improve sexual performance.

In order to produce the semi-aromatic polyamide (A) having the composition described above, melt polymerization may be carried out from a nylon salt or an aqueous solution thereof according to a conventional method. During polymerization, monobasic acids such as acetic acid, benzoic acid, and stearic acid, and monoacid bases such as hexylamine, stearylamine, and aniline may be added as molecular weight regulators. It is also possible to add heat stabilizers such as sodium phosphite, phosphorous acid, phosphoric acid, hindered phenol, and other polymerization additives.

The copolyamide obtained in this way has a relative viscosity (ηrel) of 1.7 to 3.5 dl/g, especially 1
．． 8 to 3.0 dl/g is preferred.

Next, examples of the aliphatic polyamide (B) constituting the polyamide composition of the present invention include nylon-6, nylon-6,6, nylon-6,10° nylon-6/6.6
Copolymers, nylon-6/6, IO copolymers, etc. can be mentioned.

The polyamide composition of the present invention comprises 99 to 1% by weight of the above-mentioned semi-aromatic polyamide (A) and 1 to 99% by weight of the aliphatic polyamide.
% (B) by weight. The mixing ratio of the two is (A) relative to the total amount of (A) and (B).
) is particularly preferably from 99 to 5% by weight. More preferably, it is 95 to 10% by weight. (A) and (B
This is because if the ratio of (A) to the total amount of (A) is less than 1% by weight, gas barrier properties will not be sufficient.

In addition, if the ratio of (A) to the total amount of (A) and (B) exceeds 99% by weight, semi-aromatic polyamide (A)
This is because the flexibility of the material is not sufficiently improved.

The method for mixing the semi-aromatic polyamide (A) and the aliphatic polyamide (B) of the present invention is usually to uniformly mix the respective chips and, if necessary, melt-knead them one or more times using an extruder or the like. , Various stabilizers, filler pigments, dyes, lubricants, anti-blocking agents may be used when mixing components (A) and (B) or when forming a film as necessary, but are not limited to these. Well-known additives such as additives or various thermoplastic resins can be blended.

The method for forming a film of the polyamide composition of the present invention is not particularly limited, and films and sheets can be formed by known film forming methods such as the T-die method and the 71z-john method.

In particular, the polyamide composition of the present invention can be suitably used as a film stretched in the -axis or two-wheel direction.

The film is usually plasticized by the inflation method or T-die method at a molding temperature higher than the melting point of either the semi-aromatic polyamide (A) or the aliphatic polyamide (B), and the film extruded from the die is usually 8
It is rapidly cooled to a temperature of 0° C. or lower to obtain an unstretched film.

In order to obtain a sequential two-wheel stretched film, a method is used in which an unstretched film extruded from a T-die is longitudinally stretched using a casting roll, and then transversely stretched in a tenter. In the case of simultaneous two-wheel stretching, a tenter method, a tubular method, etc. are used. The unstretched film may be subjected to humidity control or drying before proceeding to the stretching step.

The stretching temperature is preferably 120°C or less, particularly about 110 to 80°C, since workability deteriorates if it exceeds 120''C.

The stretching speed was set at 500%/sec because no improvement in gas barrier properties was observed when stretching was less than 5.000%/sec.
0%/sec or more, especially io, ooo%/s
ec or more is preferable.

When the stretching ratio is less than 1.5 x 1.5, no improvement in gas barrier properties is observed due to stretching, so 1.
5 x 1.5 or more especially 2. OX2.0 or more is preferable.

The biaxially oriented polyamide film of the composition of the present invention obtained as described above has high gas barrier properties and at the same time is excellent in flexibility.

The composition of the present invention can be easily multilayered with other packaging resins by coextrusion or lamination.

Here, packaging resins include polyester, polypropylene, polyester terephthalate, polycarbonate,
Examples include polyamide, polystyrene, polyvinyl chloride, ethylene-vinyl alcohol co-lipolymer resin, and the like.

〔Example] The present invention will be specifically explained below using examples.

In addition, the following measured values in Examples were measured as follows.

・Relative viscosity of polyamide (ηre: 98% concentrated sulfuric acid is used, the concentration is 1 g/dl, 25
Measured at °C.

・Oxygen permeation rate: 0X-TRA manufactured by MODERN C0NTR0L in the United States
Measured with N 10150H at 23° C. and 100% RH.

・Melting point (Tm): It was measured using a differential scanning calorimeter (DSC).

・Tensile modulus, tensile elongation: Measured according to ASTM D-688.

Reference example 1 <Manufacture of semi-aromatic polyamide (A)> Metaxylene diamine 2.45 kg Water
5.3kg ・Adipic acid 2.24kg1.3-
11.0 g of acetic acid was added to a salt aqueous solution consisting of 0.61 kg of phenylenedioxydiacetic acid, and the mixture was charged into a reaction tank equipped with a stirrer.
The heating and pressure were increased until the system pressure reached .

After reaching 18 kg/cil, the system pressure becomes 18) cg/
The polymerization reaction was started by stirring while releasing the pressure so as to reach cd. During that time, the internal temperature rose slowly from 210°C. After 5 hours, almost no water was distilled out, and at this point the internal temperature was 240°C. The pressure was further released, and after the pressure was reduced until the system internal pressure finally reached 200 mHH, the pressure was returned and the molten polymer was extracted from the bottom of the reaction tank.

The polyamide thus obtained had a relative viscosity (ηrel) of 2.51 and a melting point (Trn) of 216°C.

Reference example 2 <Manufacture of semi-aromatic polyamide (A)> Meta-xylene diamine 2.45 kg, water
11.0 g of acetic acid was added to a salt aqueous solution consisting of 5.1 kg, 2.24 kg of adipic acid, and 0.36 kg of oxydiacetic acid, and the mixture was charged into a reaction tank equipped with a stirrer.
After replacing with sufficient nitrogen, heating and pressure increase were carried out until the system pressure reached 18 kg/d.

After reaching 18 kg/c'Iil, the system pressure increases to 18 kg/c'Iil.
cfl! The polymerization reaction was started by stirring while releasing the pressure so that the temperature of the mixture was 100%. During that time, the internal temperature rose slowly from 210°C. After 5 hours, almost no water was distilled out, and at this point the internal temperature was 240°C. The pressure was further released until the system internal pressure finally reached 200 Hg, and then the pressure was returned and the molten polymer was extracted from the bottom of the reaction tank.

The polyamide thus obtained had a relative viscosity (ηrel) of 2.49 and a melting point (Tm) of 219°C.

Example 1 After mixing 95 parts by weight of the semi-aromatic polyamide (A) obtained in Reference Example 1 and 5 parts by weight of nylon-6 (1020CA manufactured by Mitsubishi Kasei Corporation) in the form of chips in a V-shaped tumbler,
40-ho extruder with T-die (manufactured by Bumen Tekko Co., Ltd. ES-
40 type) to obtain an unstretched film at an extrusion temperature of 240"C. This film was heated to 95°C, stretched by an inflation method, and then heat-set at 85°C for 30 seconds to obtain a film with a thickness of 25μ. The oxygen permeation amount, tensile modulus, and tensile elongation of the film thus obtained are shown in Table 1.

Examples 2 to 4 After tri-blending the semi-aromatic polyamide (A) obtained in Reference Example 1 and nylon-6 (102 OCA manufactured by Mitsubishi Kasei Corporation) in the proportions shown in Table 1, the same procedure as in Example 1 was carried out. It was made into a film and various measurements were performed. The results are shown in Table 1.

Comparative Example 1 The semi-aromatic polyamide (A) obtained in Reference Example 1 was formed into a film in the same manner as in Example 1, and various measurements were performed.

The results are shown in Table 1.

Examples 5 to 8 After tri-blending the semi-aromatic polyamide (B) obtained in Reference Example 2 and nylon-6 (1020 CA manufactured by Mitsubishi Kasei Corporation) in the proportions shown in Table 1, the same operation as in Example 1 was carried out. It was made into a film and various measurements were performed. The results are shown in Table 1.

Comparative Example 2 The semi-aromatic polyamide (B) obtained in Reference Example 2 was formed into a film in the same manner as in Example 1, and various measurements were performed.

The results are shown in Table 1.

Comparative Example 3 MXD・6 (manufactured by Mitsubishi Gas Chemical Co., Ltd., product name: Reny
6007. ηrel=2.53. Tm=237°C
) 80 parts by weight, and nylon-6 (102O manufactured by Mitsubishi Chemical Corporation)
After mixing 20 parts by weight of CA) in the form of chips in a V-shaped tumbler, extrusion temperature was 261° using a 40 mm extruder with a T-die (Model ES-40 manufactured by Member Iron Works Co., Ltd.).
An unstretched film was obtained in step C. This film was heated to 105°C.
The film was heated to 100° C., stretched by an inflation method, and then heat-set at 90° C. for 30 seconds to obtain a film with a thickness of 25 μm. Various measurements were performed using the film thus obtained.

The results are shown in Table 1.

Comparative Example 4 MXD-6 used in Comparative Example 3 was formed into a film in the same manner as in Comparative Example 1, and various measurements were performed. The results are shown in Table 1.

(Effects of the Invention) As shown in Table 1, the polyamide composition of the present invention has excellent gas barrier properties, moldability, and stretching workability as well as flexibility compared to conventional polyamide compositions. Moreover, its commercial value is high.

Claims (1)

[Claims] (1) A polyamide composition consisting of 99 to 1% by weight of semi-aromatic polyamide (A) and 1 to 99% by weight of aliphatic polyamide (B), wherein the semi-aromatic polyamide (A) is (a) 5 to 1% by weight; 30 mol% structural unit represented by the following general formula [I]▲There are mathematical formulas, chemical formulas, tables, etc.▼... [I] (In the [I] formula, X is -O-, -S-, -NH -, R represent a divalent aromatic group having 6 to 15 carbon atoms, and n is 0 or 1.) (b) 95 to 70 mol% of the structural unit represented by the following formula [II] ▲ Formula , chemical formula, table, etc. ▼...[II] A polyamide composition characterized by being a semi-aromatic polyamide composed of the following.