JPH0228255A - Polyamide resin composition - Google Patents

Abstract

PURPOSE:To obtain the title composition to be suitably used for producing thin-walled molded products of excellent hinge characteristics by incorporating a hexamethylene terephthalamide unit-contg. copolyamide with a specific ethylene-based copolymer. CONSTITUTION:The objective composition can be obtained by incorporating (A) 100 pts.wt. of a polyamide made up of A1: 70-100wt.% of a copolyamide containing 20-60mol% of hexamethylene terephthalamide unit and A2: 0-30wt.% of a high-molecular-weight aliphatic polyamide >=3 (pref. >=3.5) in sulfuric acid relative viscosity with (B) 3-35 pts.wt. of a polymer (blend) made up of B1: 60-100wt.% of an ethylene-based copolymer (ionomer resin) with its side chain containing COOH and carboxylic acid metal salt and B2: 0-40wt.% of a hydrocarbon-based copolymer and (C) 0-10 pts.wt. of a mixture made up of C1: 80-40wt.% of an oxide compound and/or carbonate compound and C2: 20-60wt.% of a polyhydric alcohol.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is suitable for manufacturing thin-walled molded products having excellent physical properties, particularly molded products having thin-walled parts with excellent hinge characteristics (bending resistance). The present invention relates to the polyamide resin composition used.

[Conventional technology].

Polyamide resins are generally known for their excellent heat resistance, strength,
Because of its toughness and moldability, it is used in large quantities as a typical engineering plastic for industrial products such as automobile, electrical, electronic, and mechanical parts, as well as for sports and leisure products.

By the way, polyamide resin easily absorbs water due to its chemical structure (reduction in rigidity when water is absorbed becomes a problem).

As a means to solve this problem, it has been proposed to introduce an aromatic ring into the main chain.

On the other hand, in the above application fields, with the recent trend toward more complex shapes and lighter weight of molded products, there has been an increase in the number of thin-walled parts, for example, with a wall thickness of 1 mm or less, and as a result, in terms of performance,
Rigid ring during water absorption In addition to general mechanical properties, there is an increasing demand for bending resistance of thin-walled parts, ie, hinge properties.

On the other hand, from the viewpoint of moldability, it goes without saying that it is essential that the molten resin flows smoothly even into thin-walled parts, solidifies quickly, and is easily released from the mold. However, in addition to general physical properties, such excellent hinge properties and excellent moldability are rather contradictory requirements, and at present no resin material has been obtained that satisfies them at the same time.

[Problem to be solved by the invention]

As a result of various studies on conventionally known polyamide resins, the present inventors found that polyamides with hard segments containing aromatic rings introduced into the main chain, such as copolyamides containing hexamethylene terephthalamide units, have excellent water absorption properties. It was considered that this is the most suitable base column 1 fat for manufacturing thin-walled molded products having

However, polyamides with hard segments containing aromatic rings introduced into the main chain, such as copolyamides containing hexamethylene terephthalamide units, have the drawbacks of being brittle and having poor hinge properties, although they have high rigidity. Increasing the molecular weight to compensate for this increases the melt viscosity,
Melt formability decreases. Furthermore, because of its rigidity, it has the disadvantage that the molded product has poor mold releasability.

[Means to solve the problem]

In view of the above, the present inventors have conducted extensive research in order to find a resin composition that exhibits excellent hinge properties and excellent moldability based on an aromatic ring-containing polyamide resin that has excellent water absorption properties.

As a result, when an ethylene-based copolymer containing a carboxyl group and a carboxylic acid metal salt in the side chain was added to a copolyamide containing hexamethylene terephthalamide units, the formability and hinge properties of thin-walled parts were considerably improved, and the carbonization It was discovered that the hinge properties were further significantly improved by adding a small amount of a hydrogen-based copolymer and/or a mixture of an oxide compound or a carbonate compound and a polyhydric alcohol, leading to the present invention.

That is, in the present invention, (C) carboxyl groups are added to 100 parts by weight of a polyamide consisting of (A) 70 to 100% by weight of a copolyamide containing hexamethylene terephthalamide units and (B) 10 to 30% by weight of a high molecular weight aliphatic polyamide. and ethylene copolymer 60 containing carboxylic acid metal salt in the side chain
(D) 3 to 35 parts by weight of a polymer or aggregate mixture consisting of 100% by weight and (D) 0 to 40% by weight of a hydrocarbon copolymer, and (E) 80 to 40% by weight of an oxide compound and/or carbonate compound and ( F) Polyhydric alcohol 20-6
The present invention relates to a polyamide resin composition characterized in that it contains 0 to 10 parts by weight of a mixture containing 0 M%.

The present invention will be explained in detail below.

The component (A) hexamethylene terephthalamide unit-containing copolyamide used in the present invention has, as a monomer,
A copolyamide containing hexamethylene terephthalamide units (6T) obtained from hexamethylene diamine and terephthalic acid or a derivative thereof. in particular,
6T-polyhexamethylene adipamide (6T/66)
, 6-polyhexamethylene adipamide-polyε-caprolactam (6T/66/6), 6T/66/polyhexamethylene dodecanamide (6T/6B/612)
), 6T/66/polyhexamethylene adipamide (6
T/66/610), 6T/66/Polytetramethylene adipamide (6T/66/46), 6T/66/
Polyhexamethylene isophthalamide (6T/66/6
1), 6T/polymethaxylylene diamide 77 dipamide (6T/MX[l-6), 6T/66/MX[)-6
etc.

The preferred 6T content in component (A> is 20 to 60
The range is mole %. If the content is less than 20 mol%, it will be difficult to obtain general physical properties, especially high rigidity upon water absorption.On the other hand, if it exceeds 60 mol%, the melting point and melt viscosity of the polymer will become high, and the final composition will become difficult to obtain. Molding processability decreases,
Lose versatility.

The relative viscosity of sulfuric acid (95.5% sulfuric acid) of component (A) is 1.5 to 3.5, particularly preferably 1.7 to 2.
6 is recommended. If the relative viscosity is less than 1.5, general mechanical properties will not be developed, and if it exceeds 3.5,
The melt viscosity is too high and is not suitable for general-purpose molding methods, so it falls outside the appropriate range.

The polyamide of component (A) may be a copolyamide melted or polymerized in the presence of an aliphatic polyamide. Specifically, a method in which all monomer components are polymerized in the coexistence of an aliphatic polyamide, a method in which a 6T copolyamide produced separately with the aliphatic polyamide is copolymerized during melt kneading, and a method in which the mixed material is solid-phase polymerized. It can be manufactured with etc. A particularly preferred copolymer of component (A) is 6
Examples include T/66.6T/66/6.6T/66/612, and the above polymers polymerized in the presence of nylon 66.

The polyamide component may contain a high molecular weight aliphatic polyamide in addition to the above-mentioned hexamethylene terephthal copolyamide. In this case, the hexamethylene terephthal copolyamide is present in an amount of at least 7% of the total polyamide component.
is necessary. When high molecular weight aliphatic polyamide is contained, the amount thereof is preferably 3 to 30% by weight.

As the type of high molecular weight aliphatic polyamide of component (B), nylon 66, nylon 6, nylon 6/66, nylon 610, nylon 612, nylon 11, nylon 12, and nylon 1212 can be used.

The high molecular weight aliphatic polyamide of component (B) has a sulfuric acid relative viscosity ηr (95.5% sulfuric acid) of 3 or more, and particularly preferably has a high molecular weight of 3.5 or more.

In the present invention, the high molecular weight polyamide of component (B) is
Although not an essential component, a small amount (
(30% by weight or less), the variation in tensile elongation of the molded product is reduced, the average value is improved, and stable physical properties with less variation can be obtained overall. However, when added in excess of 30% by weight,
Physical properties such as flexural modulus when water is absorbed are deteriorated, which is not preferable.

ηr of polyamide when mixing fi minutes (A) and (B) is -
Approximately 2 to 5 is preferable for boat fishing, and it can be used depending on the purpose, but as a base polymer for the injection molding composition, the component (A) polymer has an ηr of 2.4 and 2°, and the component ( A combination of B) having a value of 77r3.5 or more is recommended from the viewpoint of balance of fluidity and physical properties.

The ethylene copolymer containing carboxyl groups and carboxylic acid metal salts in the side chains of component (C) is a polymer containing monomer units represented by the general formula, but does not contain unsaturated carboxylic acid ester groups. There is no harm in being.

Here, R1 to RS are each a hydrogen atom or a carbon number 1
~5 alkyl group, and Mk is a metal ion of group IaS Ib, Ua, Ilb or ma of the periodic table of the elements,
For example, Nas K % MgXZn.

A typical example of such a polymer is known as an ionomer resin. Molecular weight has a melt index of 0
．． A range of 1 to 5 is preferable.

Component (C) is added in an amount of 3 to 100M parts of the total polyamide.
The amount used is 35 parts by weight, but if it is less than 3 parts by weight, no impact resistance will be imparted, and if it exceeds 35 weight %, the rigidity and heat resistance will decrease, which is not preferable.

A part of this component (C) may be replaced with a component (D) described below.

The hydrocarbon copolymer of component (D) is ethylene/
In addition to ethylene copolymers such as propylene, ethylene/butene-1, ethylene/hexene-1, and ethylene/propylene/ethylidene norbornene, hydrogenated products of polybutadiene and styrene/butadiene block copolymers are exemplified. The molecular weight is preferably in a range such that the melt index is 1-10.

When a part of component (C) is replaced with component (D), the amount thereof is preferably 15 to 40% by weight based on component (C). 4
If it exceeds 0% by weight, the dispersion system becomes non-uniform, which is thought to be due to a phase separation phenomenon, resulting in a decrease in impact strength and the like. When added in a small amount, this component improves impact resistance and hinge properties.

The oxide compound or carbonate compound of component (E) is represented by the general formula (wherein R6 is a hydrogen atom or an alkyl group, respectively, and X is -0\), and specifically, Examples include ethylene carbonate, ethylene oxide, propylene oxide, and butylene oxide.

Component (E) does not necessarily need to be added, but if it is added together with component (F) in an amount of up to 10 parts by weight, preferably in a range of 5 parts by weight, based on 100 parts by weight of polyamide, the composition This formulation is desirable depending on the application, as the hinge properties of the compound are further improved. This is because component (E) causes some kind of reaction with component (C) in the coexistence of component (F).
This is presumed to be because the bond with the polyamide matrix is strengthened.

However, if the amount added exceeds 10 parts by weight, the effect will further increase, but the heat resistance will decrease, which is not preferable.

When components (E) and (F) are added, the amount thereof is preferably 0.2 parts by weight or more per 100 parts by weight of the total polyamide.

Examples of component (F) include ethylene glycol, trimethylene glycol, butanediol, diethylene glycol, glycerin, and pentaerythritol.

Component (F) also functions as a plasticizer, but it also coexists with component (E) [weight ratio (E)/(F) is 80].
/20 to 40/60), the effect of further improving the hinge properties of the composition is exhibited.

Further, in the present invention, when a crystallization nucleating agent (G) is added,
Furthermore, moldability can be improved.

As component (G), various known inorganic compounds and organic compounds can be used. Examples include titanium oxide, sodium phosphate, sodium phenylphosphonate, sodium phenylphosphinate, talc, calcium stearate, sodium stearate, and melamine cyanurate.

Another compound that is particularly effective in small amounts is talc. Although the amount added varies depending on the type, it is usually desirable to add 1 part or less in order not to adversely affect the physical properties.

In carrying out the present invention, heat-resistant agents, antioxidants, lubricants, plasticizers, dyes, pigments, and other polymers commonly used in polyamides may be added to the composition as necessary, either directly or by masterbatch method. There is no problem in adding it.

The resin composition for injection molding of the present invention has a temperature of 300°C.
Particularly preferred are those having a melt viscosity of 800 to 1,500 voids.

When the melt viscosity exceeds 1500 poise, it is necessary to raise the resin temperature to a high temperature in order to increase fluidity in normal injection molding, but in such high temperature molding, streak-like substances called silver may appear on the surface of the molded product. occurs and the appearance is damaged. On the other hand, if the number of voids is less than 800, although the fluidity is good, the physical properties restrict recycling and repeated use, which is not preferable.

In addition, in order to make the composition within such a melt viscosity range, a so-called solid phase polymerization is carried out in which the polymerization reaction is accelerated by heating a pellet-shaped mixed wire composition using a relatively low molecular weight polyamide as a starting material in a nitrogen atmosphere. It is also possible to apply

Regarding polyamide components, the method of combining melt polymerization and solid phase polymerization can reduce the discharge viscosity of melt polymerization equipment;
Moreover, it can be said to be an effective method for improving polymerization efficiency, such as shortening the polymerization time.

The composition obtained in this way is molded by a method such as injection molding, and is used for automobile engine parts, connectors, bobbins, electrical components, and other automobile parts, electric and electronic parts, industrial goods, etc. It is suitable as a resin composition for hinge molded products having thin-walled parts.

〔Example〕

The physical properties of the molded articles shown in Examples below were measured by the following method.

■Tensile strength: Measured according to ASTM D638.

■Tensile elongation: Measured according to ASTM D638.

■Bending elastic modulus: Measured according to ASTM 0790.

■Eye shift impact strength: Measured according to STM D256.

■Hinge characteristics: A test piece having a thin part with a thickness of 0.61 was bent 150" at a rate of 30 times/minute in an atmosphere of -30°C, and the number of times it took to break was measured.

■Heat distortion temperature: Measured according to ASTM D648.

■Moldability of thin-walled parts: Evaluated by flow length and mold releasability in a mold with a width of 8 mm and a thickness of 0.41.

Production Example 1 Process for producing component (A) polymer ■Polymer (A-1) In a 1001 capacity autoclave, moles of hexamethylenediamine/terephthalate (6T salt) and hexamethylenediamine/adipate (AI salt) were added. The ratio of sulfuric acid was 40/60, the heating melt polymerization was carried out, and the relative viscosity of sulfuric acid was yy r.
(95.5% sulfuric acid) 2.3 6T/66 cobolyamide (A-1) was obtained.

■Polymer (A-2) 6T/66 (40/60
) A copolyamide was obtained. ηr was 1.8.

By subjecting this product to solid phase polymerization (heating at 200° C. for 4 hours), ηr increased to 2.2.

■Polymer (A-3) The melt-polymerized polymer obtained during polymerization of Polymer (A-2) and nylon 66 (solution viscosity 3.5) are mixed in a molar ratio of 90/
After melt-kneading at 10, solid phase polymerization (200''C 14 hours) was performed to obtain a copolyamide (A-3) with ηr of 2.3.

■ Polymer (A-4) 6T/66 cobolyamide ( ηr2.5) (A-4) was prototyped.

■Polymer (A-5) Polymer (A-1> under the same conditions as
Copolyamide 6T/6I/66 (35/5/60
) (A-5) was obtained. ηr was 2.2.

■Polymer (A-6) Polymer (A-5
Copolyamide 6T/66/612 under the same conditions as >
(35/60/5) was obtained. 77r was 2.1.

■Polymer (A-7) In the presence of 5 mol% of prepolymerized polyhexamethylene adipate (nylon 66, ηr 3.0), 6I
Except for polymerizing 40 mol% of salt and 55 mol% of 66 salt,
A polymerization reaction was carried out under the same conditions as for polymer (A-1) to obtain copolyamide 6T/66 (40/60) Cvr 2.
2) was obtained.

■Polymer (A-8) 6T/66 (40/60) (77r 1.8)
80 parts by weight and nylon 66 (ηr 2.6) 2
After extruding 0 parts by weight using a twin-screw extruder PCM30 at a set cylinder temperature of 285° C., the resulting pellet was subjected to solid phase polymerization at 200”C for 13 hours in a nitrogen atmosphere to give ηr of 2.4.

Example 1 90 parts by weight of polymer (A-1), nylon 66 (ηr3.
6) (B-1) 10 parts by weight, ionomer resin Himilan 1855 (Mitsui DuPont Chemical>(C-1) 15
Parts by weight were melt-kneaded using a twin-screw extruder PCM30, and then injection molded at a resin temperature of 290°C to obtain test pieces. Regarding the physical properties of this product, the hinge property (-30°C) showed a high value of 50 times. Further, the general physical property values were also good as shown in Table 1.

Comparative Examples 1-2 Polymer (A-1) alone, and polymer (A-1>90 parts by weight and nylon 66 (77r 2.9) (B-
2) Number of hinge bends for 10 parts by weight of the composition (-30'
C) was tested once and 30 times, respectively, and as shown in Table 1, the general physical property values could not be said to be well balanced.

Comparative Example 3 In Example 1, polymers (A-1) (B-1) (C-1
) was used in an amount of 65.35.30 parts by weight, but the kneading was carried out in the same manner. At the time of humidity conditioning treatment of the obtained composition (8
Immersed in 0″c hot water for 8 hours and then in 23°C water for 8 hours:
Moisture content 2.2%) bending elastic modulus is 8500Kg/CT
In A, nylon 66 (B-2> humidity control treated product (moisture content 3)
．． The flexural modulus of the sample (0%) was not much different from 8100 Kg/c+d.

Example 2 90 parts by weight of polymer (A-2), 10 parts by weight of polymer (B-1), 15 parts by weight of Himilan 1706, and ethylene-propylene rubber (trade name: Tough?-P01801 manufactured by Mitsui Petrochemicals Ltd.) (D-1) 5 parts by weight in Example 1
After kneading and extruding in the same manner as above, a test piece was prepared and the physical properties were measured, and the hinge properties were found to be good in addition to the general physical properties. The results are shown in Table 1.

Example 3 Kneading was carried out under the same conditions as in Example 2 except that 5 parts by weight of hydrogenated polybutadiene (trade name: Tuftic (manufactured by Asahi Kasei Corporation)) (D-2) was used instead of 5 parts by weight of ethylene-propylene rubber. , an extrudate was obtained. This product also had good general physical properties and hinge properties as shown in Table 1.

Example 4 In Example 2, ethylene-carbonate (E-1)
Crosstalk was performed in the same manner except that 1 part by weight and 0.5 part by weight of chrycerin (F-1) were added.

The number of hinge bends (-30°C) of the obtained composition was 14
0 times was extremely excellent, and other physical properties were also excellent as shown in Table 1.

Example 5 A composition in which 0.2 parts of talc (G-1) was added to the composition of Example 4 was obtained in the same manner, and it was found that the solidification rate of this composition was further accelerated. did.

(The following is a blank space) Comparative Example 4.5 Kneading was carried out under the same conditions as in Example 1 except that the polymer (C-1) was used in an amount of 1 part by weight or 40 parts by weight. The physical properties of the obtained composition were as shown in Table 2.

The former showed no improvement in impact resistance; had unsatisfactory heat resistance.

or, the latter

Claims (1)

[Claims] (1) A polyamide consisting of (A) 70 to 100% by weight of a copolyamide containing hexamethylene terephthalamide units and (B) 0 to 30% by weight of a high molecular weight aliphatic polyamide, 10
A polymer consisting of (C) 60 to 100% by weight of an ethylene copolymer containing a carboxyl group and a carboxylic acid metal salt in the side chain and 0 to 40% by weight of (D) a hydrocarbon copolymer based on 0 parts by weight. or 3 to 35 parts by weight of the aggregate mixture, and (E)
Oxide compound and/or carbonate compound 80-4
1. A polyamide resin composition comprising 0 to 10 parts by weight of a mixture of 0% by weight and 20 to 60% by weight of (F) polyhydric alcohol.