JP2528163B2 - Highly rigid and impact resistant polyamide resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a polyamide resin composition having excellent rigidity, impact resistance and heat resistance of its molded product.

(Prior Art) Polyamide resins are widely used as injection molding materials for parts such as automobiles and electric products, in particular, because the molded products have excellent mechanical properties.

However, when applied as a material for parts used under conditions where excessive external force or heat is applied, the rigidity,
At present, it is not always satisfactory in terms of impact resistance and heat resistance.

(Problems to be Solved by the Invention) The present invention provides a polyamide resin composition in which the drawbacks of conventional polyamide resins are improved and the molded product has excellent rigidity, impact resistance and heat resistance. With the goal.

[Structure of the Invention] (Means and Actions for Solving Problems) The polyamide resin composition of the present invention comprises: (A) a polyamide resin or a resin mixture containing a polyamide resin; and (B) a component (A) uniformly. It is characterized by comprising dispersed layered silicate and (C) impact resistance improving material.

The component (A) constituting the composition of the present invention is a polyamide resin or a resin mixture containing a polyamide resin.

Polyamide resin is an acid amide bond (-CONH
-), Specifically, ε-caprolactam, 6-aminocaproic acid, ε-enanthlactam,
7-aminoheptanoic acid, 11-aminoundecanoic acid, 9-
Polymers or copolymers obtained from aminononanoic acid, α-pyrrolidone, α-piperidone, etc .; hexamethylenediamine, nanomethylenediamine, undecamethylenediamine, dodecamethylenediamine, metaxylylenediamine and other diamines, and terephthalic acid, isophthalic acid Examples thereof include polymers or copolymers obtained by polycondensation with an acid, adipic acid, or a dicarboxylic acid such as sebacic acid, or bread products thereof.

The polyamide resin of component (A) has an average molecular weight of 9,000.
Those of up to 30,000 are preferred.

As the other resin used when the component (A) is a mixture of a polyamide resin and another polymer, polypropylene,
Examples thereof include ABS resin, polyphenylene oxide, polycarbonate, polyethylene terephthalate, and polybutylene terephthalate.

When the component (A) is used as a mixture, the content of the polyamide resin is preferably 80% by weight or more.

The component (B) is a layered silicate. The component (B) is a component that contributes to impart excellent mechanical properties and heat resistance to the molded product obtained from the polyamide resin composition.

Its shape is usually 6 to 20Å in thickness and the length of one side is
The range of 0.002 to 1 μm is preferable.

Layered silicate is 0.002-1 μm on a side and has a thickness of 6-2.
It indicates one unit of 0% substance.

The interlayer distance of the layered silicate refers to the distance between the centers of gravity of the plate of the layered silicate. And when the layered silicate is uniformly dispersed, when the layered silicate (B) is dispersed in the component (A), 50% or more of the layered silicate is separated into individual pieces without forming lumps,
A state in which molecules are dispersed in parallel and / or at random with an interlayer distance of 20Å or more being maintained. In addition,
It is more preferable that 70% or more of the layered silicate is in such a state.

As a raw material of such a layered silicate, a layered phyllosilicate mineral composed of a layer of magnesium silicate or aluminum silicate can be exemplified. Specific examples include montmorillonite, saponite, beidellite, nontronite, smectite clay minerals such as hectorite stevensite, vermiculite, halloysite, and the like. It may be Of these, montmorillonite is preferred.

The method of uniformly dispersing the layered silicate of the component (B) in a polyamide resin or a resin containing polyamide is not particularly limited, but when the raw material of the layered silicate of the present invention is a multilayered clay mineral, Alternatively, a method of contacting with a swelling agent to preliminarily expand the layers to facilitate incorporation of the monomer between the layers, and then mixing with a polyamide monomer and polymerizing (see JP-A-62-74957) may be used. In addition, a polymer compound is used as a swelling agent, and the space between layers is 100Å in advance.
A method of spreading the above and melt-kneading the same with a polyamide resin or a resin containing the polyamide resin to uniformly disperse the resin may be used.

The blending ratio of the component (B) is preferably 0.05 to 30 parts by weight, more preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the component (A). When the blending ratio of the component (B) is less than 0.05 parts by weight, the rigidity and heat resistance of the molded body are not improved so much, which is not preferable, and when it exceeds 30 parts by weight, the fluidity of the resin composition is extremely lowered. It is not preferable because it may not be suitable as a material for injection molding.

The component (C) is an impact resistance improving material. The component (C) is not particularly limited as long as it can improve the impact resistance of the molded product. As the component (C), for example, at least one selected from the following impact resistance improvers can be used.

An impact resistance improver comprising a copolymer obtained from ethylene, an unsaturated carboxylic acid and an unsaturated carboxylic acid metal salt, an impact resistance improver comprising an olefin copolymer containing 0.01 to 10 mol% of an acid group, And an impact resistance improver comprising a block copolymer obtained from a vinyl aromatic compound and a conjugated diene compound containing 0.01 to 10 mol% of an acid group or a hydrogenated product of the block copolymer, and the like. can do.

In the copolymer constituting the impact resistance improver, the proportion of ethylene units in the copolymer is 90 to 98 mol%, the balance is substantially unsaturated carboxylic acid units and unsaturated carboxylic acid metal. It is composed of salt units. If the proportion of ethylene units is too small, the material will have high rigidity but low impact resistance, which is not preferable.If it is too large, the compatibility with polyamide will be poor and the impact strength will not improve much. In some cases, the layers may be peeled off, which is not preferable.

Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, ethacrylic acid, and the like. Even if a part of the unsaturated carboxylic acid is methyl ester, ethyl ester, propyl ester or butyl ester, etc. Good.

The metal salt of unsaturated carboxylic acid is a salt of the aforementioned unsaturated carboxylic acid and a metal of Group IA, IB, II A, II B, III A and VIII of the Periodic Table of the Elements. Examples of such metals include sodium, potassium, copper, magnesium, calcium, barium, zinc, cadmium, aluminum, iron, cobalt and nickel. Among these, sodium, potassium, magnesium, calcium, barium and zinc are preferable.

Examples of the olefin copolymer constituting the impact resistance improver include copolymers obtained from olefin hydrocarbons such as ethylene, propylene, butylene, isobutylene, and amylene.

The olefin-based copolymer may contain a structural unit having an unsaturated bond. The unit can be introduced by copolymerizing dicyclopentadiene, ethylidene norbornene and the like.

The olefin copolymer is a block or random copolymer containing 70 mol% or more of ethylene units and propylene units, the molar ratio of the ethylene units and propylene units is 1: 2 to 6: 1, 2.16 kg / It is preferable that the melt flow rate (MFR) at 230 ° C is 1 to 10.

Such an olefin copolymer contains 0.01 to 10 mol% of acid groups. If the content of the acid group is too small, the compatibility with the polyamide is poor, and the impact resistance does not improve so much, which is not preferable, and even if it is too much, there is no effect to some extent in improving the impact resistance, It is not preferable because productivity is deteriorated.

As a method of introducing an acid group into the olefin copolymer,
A method in which a radical generator such as benzoyl peroxide or t-butyl hydroperoxide is reacted with maleic anhydride or acrylic acid at the time of copolymerization can be applied.

Examples of the vinyl-based aromatic compound that is a raw material for producing the copolymer that constitutes the impact resistance improver include styrene, vinylxylene, vinylnaphthalene, α-methylstyrene and vinyltoluene. These can be used in combination of two or more.

Similarly, examples of the conjugated diene-based compound that is a raw material for production include butadiene, isoprene, 1,3-pentadiene, and 2,3-dimethylbutadiene. These can be used in combination of two or more.

In the copolymer, a polymer (I) composed of a vinyl aromatic compound unit and a polymer (II) composed of a conjugated diene compound unit have the following formula: I-II-I (in the formula, even if I is the same, , Which may be different from each other) are preferred. With such a constitution of the copolymer, it is possible to improve impact resistance and maintain good moldability. Further, the polymer (II) may be partially hydrogenated.

The ratio of the polymer (I) and the polymer (II) constituting the copolymer is preferably such that the polymer (II) is 60 mol% or more. If the proportion of the polymer (II) is too small, the impact resistance improving effect cannot be exhibited, which is not preferable.

Such a copolymer contains 0.01 to 10 mol% of acid groups. If the content of the acid group is outside this range, it is not preferable for the same reason as described above.

As a method of introducing an acid group into the olefin copolymer,
A method similar to the above can be applied.

The blending ratio of the component (C) is preferably 5 to 70 parts by weight, more preferably 8 to 60 parts by weight, based on 100 parts by weight of the component (A). If the blending ratio of the component (C) is less than 5 parts by weight, the impact resistance of the molded product is insufficiently improved, which is not preferable, and if it exceeds 70 parts by weight, the rigidity (flexural modulus) and heat resistance gradually increase. It is not preferable because it decreases.

In addition to the components (A) to (C) described above, the resin composition of the present invention has improved moldability of dyes, pigments, fibrous reinforcements, particulate reinforcements, release agents and the like depending on the application. Agents, plasticizers, heat resistance improvers, foaming agents, flame retardants and the like can be added.

The method for producing the resin composition of the present invention is not particularly limited as long as it can uniformly disperse each constituent component. For example, when the raw material of the silicate of the component (B) is a multi-layered clay mineral, it is contacted with a swelling agent,
The components (A) and (B) are prepared by a method in which the layers are preliminarily expanded to facilitate the incorporation of the monomer between the layers, and then the mixture is mixed with the monomer forming the component (A) and polymerized (see JP-A-62-74957). A method of mixing and further blending the impact resistance improving material of the component (C), a method of kneading and blending the component (C) into the melt-kneaded product of the components (A) and (B), or (A) and ( A method of blending the component (C) into the powder or pellet-shaped molded product of the component B) and then melt-kneading can be applied.

At present, various inventions have been proposed in which an impact resistance improving material is compounded in order to improve the impact resistance of a polyamide resin.
However, a composition showing excellent impact resistance at low temperature has a drawback that rigidity and heat resistance are lowered. The present invention has improved its drawbacks by compounding a composition in which a layered silicate is uniformly dispersed in a polyamide resin or a resin containing the same with an impact resistance improver. Although the reason is not clear, it is considered that the rigidity and the heat resistance can be improved without impairing the impact resistance because the layered silicate is uniformly dispersed.

(Example) Example 1 100 g of montmorillonite, which is a raw material having a width of one unit of layered silicate of 9.5 Å on average and a side length of about 0.1 µm, was dispersed in 10 water, and 51.2 g of 12-amino was added thereto. Dodecanoic acid and 24m
l of concentrated hydrochloric acid was added, and the mixture was stirred for 5 minutes and then filtered. Further, this was thoroughly washed and then vacuum dried. By this operation, a complex of ammonium 12-aminododecanoate and montmorillonite was prepared. The layered silicate content in the composite was about 80%.

Next, 10 kg of ε-caprolactam, 1 kg of water and 100 g of the above complex were placed in a reaction vessel equipped with a stirrer, and stirred at 100 ° C. so that the inside of the reaction system became uniform. The temperature was further raised to 260 ° C., and the mixture was stirred for 1 hour under a pressure of 15 kg / cm ² . Then, the pressure was released and the reaction was carried out at 260 ° C. for 3 hours under atmospheric pressure while volatilizing water from the reaction vessel. After completion of the reaction, the reaction product taken out in a strand form from the lower nozzle of the reaction vessel was water-cooled and cut to obtain pellets composed of a polyamide resin (average molecular weight 15,000) and montmorillonite. Immerse this pellet in hot water,
About 10% of unreacted monomer was extracted, removed, and dried in vacuum.

Next, an impact resistance improver (impact resistance improvement) comprising a copolymer composed of 95 mol% of ethylene units, 2 mol% of methacrylic acid units, 2 mol% of zinc methacrylate units and 1 mol% of methyl methacrylate units. Material a) was prepared with high pressure polyethylene production equipment and saponification equipment using the corresponding monomers.

Then, the pellets and the impact resistance improving material a were mixed for 30 minutes by a blender at a weight ratio of 65:35. Next, the mixture was extruded using a twin-screw kneading extruder TEX30 (manufactured by Nippon Steel Works, Ltd.) to set the extruder temperature C ₁ : 250 ° C, C ₂ : 270 ° C.
C _3: 270 ℃, die temperature: 270 ° C., to obtain a kneaded in the conditions the compositions of the present invention.

The composition thus obtained was injection-molded under the following conditions to prepare a test piece, and the following test was conducted using this test piece. The results are shown in the table. In addition, the compounding amount of each component in the table is shown by converting the actual compounding amount into parts by weight. The same applies below.

Injection molding machine; Toshiba Machine Co., Ltd. IS-80 Cylinder set temperature: C ₁ 240 ℃; C ₂ 260 ℃; C ₃ 270 ℃; C ₄ (nozzle) 270 ℃ Injection pressure: 600 kg / cm ² Mold temperature: 88 ° C Injection time: 10 seconds Cooling time: 20 seconds Measurement test Tensile yield strength: ASTM-D-638 Elongation at break: ASTM-D-638 Flexural modulus: ASTM-D-790 (23 ° C for all tests) In a dry state, the impact resistance: ASTM-D-256 (a dry state at -30 ° C was performed.) Heat distortion temperature: ASTM-D-648 (tested in a dry state). Examples 2 and 3 In Example 1, the amount of swollen montmorillonite placed in the reaction vessel was 200 g (Example 2) or 400 g (Example 3).
A composition was obtained in the same manner as in Example 1 except that.

Using this composition, each test was conducted in the same manner as in Example 1. The results are shown in the table.

Comparative Example 1 In Example 1, ε was obtained without charging the composite into the reaction vessel.
-Pellets were prepared in the same manner except that only 10 kg of caprolactam and 1 kg of water were charged. Further, each test was conducted in the same manner as in Example 1 except that the impact resistance improving material a was not mixed with the pellets. The results are shown in the table.

Comparative Example 2 In Example 2, the reaction vessel was charged with ε without charging the composite.
Each test was carried out as in Example 2, except that only 10 kg of caprolactam and 1 kg of water were charged. The results are shown in the table.

Example 4 Instead of the impact resistance improving material a in Example 2, M.
Random copolymer 100 with a FR (2.16kg / 230 ℃) of 3g / min and a molar ratio of ethylene units and propylene units of 47:53.
0.7 parts by weight of maleic anhydride and 0.2 parts by weight of benzoyl peroxide were added to 1 part by weight, and the impact resistance improver b obtained by melting reaction was used, and the bread ratio at the time of kneading was polyamide silicate complex; b = 80: A composition was obtained in the same manner as in Example 2 except that the composition was changed to 20.

Using this composition, each test was conducted in the same manner as in Example 1. The results are shown in the table.

Comparative Example 3 In Example 4, the reaction vessel was charged with ε without charging the composite.
-Each test was carried out as in Example 4, except that only 10 kg of caprolactam and 1 kg of water were charged. The results are shown in the table.

Example 5 In Example 4, instead of the impact resistance improving material b, M.
A partially hydrogenated block copolymer composed of polystyrene-polybutadiene-polystyrene (molar ratio 10:80:10) having an FR (2.16 kg / 230 ° C.) of 3.4 g / 10 min, Example 4
A composition was obtained in the same manner as in Example 4 except that the one modified with 0.05 mol% maleic acid (impact resistance improver c) was used in the same manner as in.

Using this composition, each test was conducted in the same manner as in Example 1. The results are shown in the table.

Comparative Example 4 In Example 5, without charging the composite into the reaction vessel, ε
Each test was carried out as in Example 5, except that only 10 kg of caprolactam and 1 kg of water were charged. The results are shown in the table.

As is clear from the table, in the comparative examples, the characteristics are deteriorated in any of the measurement test results such as tensile strength, whereas in this example, the characteristics are not deteriorated. , Found to be excellent overall.

[Effect of the Invention] The molded product obtained from the composition of the present invention has excellent rigidity (tensile strength and flexural modulus), impact resistance and heat resistance.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display area C08L 23:04) C08L 23:04) (C08L 77/00 (C08L 77/00 55:00) 55 (00) (72) Inventor Takesumi Nishio 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (72) Inventor Akane Okada Aichi District, Aichi-gun, Nagakute Town, Nagakage, Yokoshiro 41 1 Toyota Central Co., Ltd. In the laboratory (56) Reference JP 62-74957 (JP, A) JP 62-45651 (JP, A) JP 63-145357 (JP, A)

Claims (2)

(57) [Claims] 1. (A) A polyamide resin or a resin mixture containing a polyamide resin, (B) In the component (A), each unit has a side of 0.002 to 1
(A) component containing a layered silicate having a thickness of 6 to 20 Å and having an average inter-layer distance of 20 Å and uniformly dispersed in a molecular state, and (C) impact resistance improving material. A polyamide resin composition, characterized in that after the composition of the component (B) is prepared, the component (C) is mixed therein. 2. A blending ratio of 0.05 to 30 parts by weight of the component (B) and 5 to 70 parts of the component (C) with respect to 100 parts by weight of the component (A).
The polyamide resin composition according to claim 1, which is parts by weight.