JP2882833B2 - Resin composition - Google Patents

Description

The present invention relates to a thermoplastic resin composition having excellent mechanical properties, moldability and heat resistance. More specifically, comprising a polyamide and a specific maleimide-based copolymer, the moisture absorption of polyamide, heat resistance, moldability and coatability have been improved,
The present invention relates to a thermoplastic resin composition.

[Conventional technology]

Polyamide is excellent in properties such as mechanical properties, chemical resistance, abrasion resistance, and electrical properties, but has low heat resistance and a large molding shrinkage, causing defects such as sink marks and warpage in molded products. It has the drawback that it is easy to do. Furthermore, it is known that due to its high hygroscopicity, not only the appearance of the molded product tends to be defective during the molding process, but also the size or shape of the molded product is greatly changed, and the mechanical properties of the molded product are also easily changed. ing. In addition, the viscosity of the molten resin is low, and a drooling phenomenon in which the molten resin flows out like a string from a nozzle of a molding machine at the time of injection molding tends to occur, so that the molding operation is complicated.

In order to improve such disadvantages of polyamide, attempts have been made to mix or react various kinds of polymer substances with polyamide. For example, styrene resins such as polystyrene or styrene-acrylonitrile copolymer have been melt-mixed (Japanese Patent Publication No. 38-23476,
No. 40-7380, U.S. Pat.Nos. 3,243,478, 3,243,479
No. 2,403,889), because these resins have poor compatibility with polyamide, a layered peeling phenomenon was observed in a molded product comprising the obtained composition, and the mechanical properties were also poor. . Attempts have been made to mix a polyamide with a copolymer of styrene and an unsaturated dicarboxylic anhydride monomer (JP-A-56-50931), but the resulting composition has thermal stability and toughness. Was scarce. For the purpose of improving compatibility, a copolymer of styrene and an unsaturated dicarboxylic anhydride monomer was used as a compatibilizer for the styrene resin and the polyamide. Although a composition comprising three components is known (Japanese Patent Application Laid-Open No. 60-195157), the resulting composition has been improved in compatibility and thermal stability, but its effect is insufficient. Met. A copolymer in which both polymer chains are bonded, which is produced by melt-mixing a copolymer containing an imide compound of an unsaturated dicarboxylic acid and a polyamide, is known (JP-A-57-57719; No. 57-141426), and the properties of the obtained copolymer are easily affected by the production conditions of the melt mixer, which is disadvantageous industrially. Furthermore, the heat resistance and toughness of the obtained copolymer were not always sufficient.

[Problems to be solved by the invention]

As described above, many attempts have been made to improve various properties of polyamides, but all of the effects have been insufficient for practical use.

It is an object of the present invention to provide a polyamide resin composition having improved heat resistance and hygroscopicity of a polyamide, good balance of elongation, fluidity, rigidity and the like, and good coatability.

[Means for solving the problem]

That is, the present invention relates to (A) 30 to 70 mol% of an aromatic vinyl monomer group, 10 to 50 mol% of a maleimide monomer group, 0.1 to 40 mol% of an unsaturated dicarboxylic anhydride monomer group, and And 1 to 50% by weight of a maleimide copolymer comprising 0 to 50% by mole of a copolymerizable monomer group, and (B) an amino group content of (0.
5-10) A resin composition containing 50-99% by weight of polyamide-6 and / or polyamide-6,6.6 at an amount of ^10-5 mol / g as an active ingredient, and a maleimide-based copolymer forms dispersed particles. And
Further, the thermoplastic resin composition is characterized in that the dispersed particles have a particle size of 0.01 to 5 microns and the breaking elongation of the resin composition is 10% or more. However, the thermoplastic resin composition does not contain modified polyolefin and glass fiber.

This resin composition has a good balance of elongation, fluidity, rigidity, heat resistance, etc., is excellent in moldability, has low moisture absorption, and is excellent in coatability.

In this resin composition, the molar ratio of all the acid anhydride groups in the maleimide-based copolymer to the total amino groups in the polyamide is preferably controlled to 0.1 to 50, particularly preferably 1 to 20.

The method for producing the maleimide-based copolymer used in the present invention is not particularly limited. For example, aromatic vinyl monomers, maleimide-based monomers, unsaturated dicarboxylic anhydride monomers and other copolymerizable monomers can be used. It can be produced by radical copolymerization of a monomer.

Specific examples of the aromatic vinyl monomer include styrene, α
-Methylstyrene, vinyltoluene, t-butylstyrene, and the like. Specific examples of the maleimide-based monomer include maleimide, N-mesylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-hexylmaleimide, and N-hexylmaleimide. Cyclohexylmaleimide, N-phenylmaleimide, N-tolylmaleimide and the like, specific examples of unsaturated dicarboxylic anhydride monomers include maleic anhydride, methylmaleic anhydride, 1,2-dimethylmaleic anhydride, Examples include ethyl maleic acid and phenyl maleic anhydride.

Examples of the vinyl monomer copolymerizable therewith include vinyl cyanide monomers such as acrylonitrile, methacrylonitrile and α-chloroacrylonitrile, and acrylic acids such as methyl acrylate, ethyl acrylate and butyl acrylate. Ester monomers, methacrylic acid ester monomers such as methyl methacrylic acid ester and ethyl methacrylic acid ester, vinyl carboxylic acid monomers such as acrylic acid and methacrylic acid, acrylamide, methacrylamide, acenaphthylene and N-vinyl Examples thereof include carbazole and the like, and among them, monomers such as acrylonitrile, acrylic ester, methacrylic ester, acrylic acid, and methacrylic acid are particularly preferable.

The method for copolymerizing these monomers is not particularly limited, and any known radical copolymerization method can be used.

As another method for producing a maleimide copolymer used in the present invention, a copolymer of an aromatic vinyl monomer, an unsaturated dicarboxylic acid anhydride monomer and other copolymerizable monomers may be prepared using ammonia or a copolymer. A method of reacting with a primary amine to imidize an acid anhydride group can be exemplified.
The imidation reaction between a polymer substance having an acid anhydride group in a polymer chain and an amine compound is known, for example,
According to the method disclosed in -26936 or 62-8456, by reacting a polymer substance and an amine compound,
A maleimide-based copolymer having an intended imide group can be produced.

Examples of the primary amine used in the imidation reaction include methylamine, ethylamine, propylamine, butylamine, hexylamine, cyclohexylamine,
Decylamine, aniline, toluidine, naphthylamine, chlorophenylamine, dichlorophenylamine,
Bromophenylamine, dibromophenylamine and the like.

The imidization reaction is carried out in a solution state using an autoclave,
The reaction can be performed in a bulk molten state or a suspended state. It is also possible to carry out the reaction in a molten state using a melt kneading device such as a screw extruder.

The solvent used for the melting reaction is arbitrary, for example, acetone, methyl ethyl ketone, methyl isobutyl ketone, ketones such as cyclohexanone, tetrahydrofuran, ethers such as 1,4-dioxane, toluene, aromatic hydrocarbons such as xylene, dimethyl Examples include formamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, and the like.

The reaction temperature for imidization is preferably in the range of 50 to 350 ° C.,
A range from 00 to 300 ° C. is particularly preferred.

The imidation reaction does not necessarily require the presence of a catalyst, but if used, trimethylamine, triethylamine, tributylamine, N, N-dimethylaniline, N, N-
Tertiary amines such as diethylaniline are preferred.

The maleimide-based copolymer used in the present invention contains 30 to 70 mol% of an aromatic vinyl monomer group and 10% of a maleimide-based monomer group.
~ 50 mol%, unsaturated dicarboxylic anhydride monomer group 0.1 ~ 4
0 mol% and 0 to 50 mol% of other copolymerizable monomer groups. More preferred ranges are 50-60 mol% of an aromatic vinyl monomer group, 20-40 mol% of a maleimide-based monomer group, 1-20 mol% of an unsaturated dicarboxylic anhydride monomer group, and other copolymers. 0 to 29 mol% of possible monomer groups. When the amount of the aromatic vinyl monomer group is less than 30 mol%, it is difficult to produce a polymer having a homogeneous composition with good industrial reproducibility, and it is obtained by mixing the maleimide-based copolymer with a polyamide. Inferior properties such as thermal stability, moldability and mechanical strength of the resulting composition. When the content of the aromatic vinyl monomer group exceeds 70 mol% or the content of the maleimide monomer group is less than 10 mol%, the heat resistance of the obtained composition is poor, and the maleimide monomer group is If it exceeds 50 mol%, the moldability of the obtained composition will be poor. If the unsaturated dicarboxylic anhydride monomer group is less than 0.1 mol%, the compatibility of the composition obtained by mixing with the polyamide is poor, and the particle size of the maleimide-based copolymer dispersed particles increases, The mechanical strength is inferior, and a peeling phenomenon is observed in a molded product of the composition. When the content of the unsaturated dicarboxylic acid anhydride monomer group exceeds 40 mol%, the particle size of the maleimide copolymer-dispersed particles of the composition becomes too small, so that the molding processability is inferior and the heat stability of the molded product is poor. The properties may be poor and the surface may be roughened like a shark skin.

The polyamide used in the present invention is polyamide-6,
Polyamide-6,6, which can be used alone or in combination.

In the present invention, the composition is prepared by mixing 1 to 50% by weight of a maleimide-based copolymer and 50 to 99% by weight of a polyamide.
If the amount exceeds 99% by weight, the degree of improvement in heat resistance, moldability or processability of the resulting composition is insufficient, and the amount of the maleimide-based copolymer exceeds 50% by weight or the amount of the polyamide is 50% by weight. Less than the mechanical strength of the composition,
Poor chemical or abrasion resistance.

In the resin composition of the present invention, the maleimide-based copolymer forms dispersed particles, and the particle size of the dispersed particles is 0.01 to 5
It needs to be microns. A particularly preferred particle size is between 0.02 and 2 microns. However, the particle size of the dispersed particles was measured by observing an ultrathin section cut from a sample treated with hydrazine monohydrate and stained with osmic acid with a transmission electron microscope. If the dispersed particle size is less than 0.01 micron, the composition obtained by mixing with the polyamide has a high melt viscosity, and a shark skin-like defect phenomenon occurs on the surface of the molded product.
If the dispersed particle size exceeds 5 microns, the mechanical strength of the composition is poor, the elongation is small, and the effect of improving the moldability is insufficient.

According to the knowledge of the inventor, when the same polyamide is used, a particularly important factor for determining the dispersed particle diameter in the composition is an unsaturated dicarboxylic acid anhydride monomer in the maleimide-based copolymer. This is the content of body residues. When the content is low, the particle size is large, and when the content is high, the particle size is small. Further, depending on the molecular weight of the maleimide-based copolymer, the particle size is small at a low molecular weight and large at a high molecular weight. When the same maleimide-based copolymer is used, the dispersion particle size is large when the amount of amino groups is small and small when the amount is large, depending on the amount of amino groups in the polyamide. Also, depending on the melt viscosity of the polyamide, the lower the viscosity, the higher the viscosity, and the higher the viscosity, the lower the viscosity. Further, as another factor, the dispersed particle size also depends on the method of mixing the maleimide-based copolymer and the polyamide.

To maintain a good balance of physical properties, preferably all the acid anhydride groups in the maleimide-based copolymer with respect to all the amino groups in the polyamide in a molar ratio of 0.1 to 50, particularly preferably 1 to 20
It is good to control.

The mixing of the maleimide-based copolymer and the polyamide can be carried out using a usual melt-kneading apparatus. Examples of suitable melt-kneading apparatuses include a screw extruder, a Banbury mixer, a co-kneader, and a mixing roll.

The resin composition of the present invention can be made into a composition by adding another resin or elastomer according to the purpose. Specifically, ABS resin, AS resin, SMA resin, polycarbonate, polybutylene terephthalate, polyethylene terephthalate, polyphenylene ether and other resins and acrylic rubber,
Preferred examples include elastomers such as ethylene propylene rubber and styrene-butadiene rubber.

Further, the composition of the present invention can be made into a composition by adding other additives or modifiers depending on the application.Specifically, carbon fibers, reinforcing fibers such as aramid fibers, talc, silica, There are fillers such as clay, mica, calcium carbonate, etc., stabilizers, ultraviolet absorbers, flame retardants, lubricants, coloring agents and the like.

〔Example〕

The present invention will be described in more detail with reference to the following examples,
All parts and percentages used in the examples and comparative examples are on a weight basis.

 In addition, the measuring method of various properties is as follows.

Maleimide-based copolymer particle size in the composition: A sample previously trimmed is immersed in hydrazine monohydrate, and the temperature is 60 ° C.
For 48 hours. After washing with water, this sample was immersed in a 1% osmic acid aqueous solution and left at room temperature for 24 hours to stain.
Ultrathin sections were cut out from the stained samples, and transmission electron micrographs were taken. The obtained image was analyzed to determine the particle size.

Heat resistance: Heat distortion temperature (HDT) was measured according to ASTM D-648 using a 1/4 ″ thick injection molded product under a load of 18.6 kg / cm ² .

Impact strength: According to ASTM D-256, a notched Izod was measured using a 1/4 ″ thick injection molded product. The ambient temperature was 23 ° C.

Fluidity: temperature 265 ° C, load 10 according to ASTM D-1238
The melt flow rate (MFR) was measured in kg.

Elongation: A 1/8 ″ injection molded product was subjected to a tensile test according to ASTM D-638, and the elongation at break (El) was measured.

 Moisture content: Measured with a Karl Fischer moisture meter.

Coating cross-cut test: After coating the coating in accordance with JIS K 5400, the coating was peeled off with a gum tape, and the number of peeled cross-cuts was indicated by the number per 100 pieces.

(1) Maleimide copolymer (A-1) The maleimide copolymer was charged to 100 parts of styrene in an autoclave equipped with a stirrer, and the inside of the system was replaced with nitrogen gas under stirring, and then the temperature was raised to 80 ° C. Heated. To this, a solution prepared by dissolving 67 parts of maleic anhydride and 0.2 parts of benzoyl peroxide in 300 parts of methyl ethyl ketone was added over 8 hours. After the addition, the temperature was kept at 80 ° C. for a further 4 hours.

To the above copolymer, 1.2 parts of triethylamine and 38.1 parts of aniline were added and reacted at 150 ° C. for 10 hours. The reaction solution was diluted with dimethylformamide, cooled, poured into a large amount of vigorously stirred methanol, and the precipitate was separated by filtration and dried.
A maleimide-based copolymer (A) was obtained. Maleimide copolymers B to I were similarly prepared. These are shown in Table 1.

(2) Polyamide (-) The following commercially available polyamide was used.

Polyamide: Polyamide-6 containing 5.9 × 10 ⁻⁵ mol / g amino group.

Polyamide: Polyamide-6 containing 2.4 × 10 ⁻⁵ mol / g of amino group.

Polyamide: polyamide-6,6 containing 5.0 × 10 ⁻⁵ mol / g amino group.

Polyamide: polyamide-6,6 containing 3.8 × 10 ⁻⁵ mol / g of amino group.

(3) Mixture of maleimide-based copolymer and polyamide Maleimide-based copolymer (AI) and polyamide (~)
) Was charged into a tumbler mixer at the ratio shown in Table 2 and stirred, and then supplied to a co-rotating twin-screw extruder to be pelletized. The extrusion temperature was 280 ° C.

The physical properties of the obtained composition were evaluated according to the methods described above, and are summarized in Table 2.

The molded product of Experiment No. 11 has particularly bad surface condition near the gate. Also, the fluidity is poor. The molded product of Experiment No. 12 had severe delamination of the gate, low heat resistance, and poor strength.
Experiment No. 13 is very fragile and hardly any satisfactory molded product can be obtained.

(4) Cross-cut peel test of the coating film of the composition The resin composition of Experiment No. 1 shown in Table-2 was molded into a 2 mm thick square plate of 100 mm x 100 mm at 270 ° C using a 2 oz molding machine. The paint is Lecrac # 72 manufactured by Fujikura Kasei Co., Ltd.
A mixture of Leclac # 725 in a ratio of 1: 1 as a thinner was spray-painted on a square plate previously washed with isopropyl alcohol at a thickness of 15 to 20 μm. At room temperature
After drying at 60 ° C. for 30 minutes for 15 minutes, a cross-cut peel test was performed.

The same procedure was performed for the resin composition of Experiment No. 6 and the resin composition of Experiment No. 1 in which polyamide was used instead of polyamide (Experiment No. 15).
Table 3 summarizes the results.

The paint used in this test is for general ABS, but it is clear that the paintability of polyamide is improved.

[Effects of the Invention] As described above, in the resin composition having a specific structure, comprising a specific maleimide-based copolymer and a specific polyamide of the present invention, heat resistance and molding processability, which are disadvantages of polyamide, In addition, since the property of moisture absorption is improved and the good properties of polyamide are maintained, it can be suitably used for applications such as automobile parts, electric equipment parts, kitchen miscellaneous goods parts and the like.

[Brief description of the drawings]

FIG. 1 and FIG. 2 each show experiment number 7 of Example 1.
6 is an electron micrograph showing a dispersion state of maleimide-based copolymer particles in a resin composition obtained in Experiment No. 12 of Comparative Example 1; 1 and 2 are 15,000 times.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-200868 (JP, A) JP-A-1-210444 (JP, A) JP-A-63-193955 (JP, A) (58) Investigation Field (Int.Cl. ⁶ , DB name) C08L 77/00-77/12 C08L 35/06

Claims (1)

(57) [Claims] (A) 30 to 70 mol% of an aromatic vinyl monomer group, 10 to 50 mol% of a maleimide monomer group, 0.1 to 40 mol% of an unsaturated dicarboxylic anhydride monomer group and others. (B) a polyamide having an amino group content of (0.5-10) × 10 ⁻⁵ mol / g; 6, and / or a resin composition containing 50-99% by weight of polyamide-6,6 as an active ingredient, wherein the maleimide-based copolymer forms dispersed particles, and the dispersed particles have a particle diameter of 0.01-5. Microns and the elongation at break of the resin composition
A thermoplastic resin composition having a content of 10% or more.
However, the thermoplastic resin composition does not contain modified polyolefin and glass fiber.