JPH11199770A - Polyamide resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition being excellent in heat stability during molding and gives a product excellent in flexural modulus, tensile strength, and tensile elongation by molecularly uniformly dispersing a layered silicate among the layers of which a tert. amine has been intercalated. SOLUTION: The polyamide resin used is desirably one having a relative viscosity of 1.5-3.5, a terminal amino content of 20-90 milliequivalents/kg, and a terminal carboxyl content of 20-100 milliequivalents/kg. A desirable example of the tert. amine used is monomethyldidecylamine. The layered silicate used is a layered phyllosilicate composed of magnesium silicate or aluminum silicate layers and is exemplified by swellable fluoromica. It should have a cation exchange capacity of at least 30 mulliequivalents/100 g, and at least 70% of the ion exchange capacity should be ascribable to the intercalated tert-amine. The layered silicate is dispersed in the polyamide resin in such a manner that at least 50% of its particles have a particle diameter in the range of 1 μm or below and are uniformly dispersed at an average distance among particles of 2 nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a polyamide resin composition. More specifically, the present invention relates to a polyamide resin composition having excellent flexural modulus, tensile strength and tensile elongation, and having excellent thermal stability during molding.

[0002]

2. Description of the Related Art In order to improve various properties, especially mechanical properties, of organic polymer materials such as thermoplastic resins, it has been practiced to add inorganic fillers such as talc, kaolinite, and mica. I have. However, simply melt-mixing these with the thermoplastic resin does not uniformly disperse the inorganic filler in the thermoplastic resin in a molecular state, and therefore, a thermoplastic resin composite having sufficiently satisfactory properties cannot be obtained.

Japanese Patent Publication No. 58-35211 discloses that in order to uniformly disperse an inorganic filler in a polyamide resin in a molecular state, a silicate, particularly a layered silicate, is selected, and is preliminarily prepared with an amino acid or a polyamide salt. After intercalation with an organic compound such as, for example, a monomer is polymerized in the presence of such a layered silicate to produce a polyamide resin composite in which the composite is uniformly dispersed molecularly.

However, although the rigidity of the polyamide resin composite obtained by this method is improved with an increase in the amount of the layered silicate, there is a problem that the tensile elongation which is an essential feature of the polyamide resin is remarkably reduced. Was. Collection of High Polymer Papers; vol. 52, no. 7, p440 (1
995) proposes a method for controlling the dispersion state of the layered silicate by adding a diamine together with an amino acid in the process of intercalating the layered silicate with an organic compound. However, in this method, rigidity and strength were reduced, and tensile elongation was not sufficiently improved.

[0005] Here, the intercalation means that an alkali or alkaline earth metal ion between layered silicate layers is ion-substituted with a target organic ion and inserted between the layers. JP-A-8-12881 reports that elongation is improved without substantially lowering rigidity by using a quaternary ammonium ion having an alkyl chain having 12 or more carbon atoms instead of an amino acid or a nylon salt. ing. However, the quaternary ammonium ion has a problem that the production is troublesome and there is a fear that the thermal stability at the time of molding due to a free compound may be reduced.

[0006]

The present invention relates to a polyamide resin composition in which a layered silicate is uniformly dispersed molecularly in a polyamide resin. More specifically, the present invention relates to a polyamide resin composition having a flexural modulus, tensile strength and tensile elongation. An object of the present invention is to provide a polyamide resin composition which is excellent in heat stability during molding.

[0007]

The present inventors have studied various organic compounds to be intercalated between layers of the layered silicate. As a result, by using a tertiary amine as the organic compound, the flexural modulus and the tensile strength were improved. The present inventors have found that a polyamide resin composition having excellent tensile elongation and excellent thermal stability during molding can be obtained, and the present invention has been completed.

That is, the present invention is as follows. 1) A polyamide resin composition comprising 100 parts by weight of a polyamide resin and 0.5 to 30 parts by weight of a layered silicate obtained by intercalating a tertiary amine. 2) The layered silicate has a cation exchange capacity of 30 meq /
2. The polyamide resin composition according to the above item 1, which is a layered silicate of 100 g or more.

(3) The polyamide resin composition as described in (1) or (2) above, wherein the phyllosilicate is intercalated with a tertiary amine for at least 70% of its ion exchange capacity. 4) The polyamide resin composition according to the above 1, 2, or 3, wherein the layered silicate is swellable fluoromica.

(5) The above-mentioned (1), wherein the tertiary amine has at least one alkyl group having 6 or more carbon atoms.
5. The polyamide resin composition according to 2, 3, or 4. Hereinafter, the present invention will be described in detail. Polyamide resin used in the present invention, for example, polyamide 66 resin,
Polyamide 610 resin, polyamide 612 resin, polyamide 6I (I is isophthalic acid) resin, polyamide 6
T (T stands for terephthalic acid) resin, polyamide MXD6
(MXD means meta-xylylenediamine), polyamide 46 resin, polyamide 6 resin, polyamide 3 resin, polyamide 11 resin, polyamide 12 resin and / or a copolymer thereof.

The relative viscosity (ηr) of the polyamide resin is as follows.
A range of 5 to 3.5 is preferable, and a more preferable range of the relative viscosity (ηr) is 1.9 to 3.0. If the relative viscosity (ηr) is less than 1.5, the toughness may decrease. If the relative viscosity (ηr) exceeds 3.5, the fluidity may decrease and the appearance of the molded article may deteriorate. Further, the amino group as an end group of the polyamide resin is 20 to 90 meq / kg,
The carboxyl group preferably has a range of 20 to 100 meq / kg, and more preferably the terminal group has an amino group of 40 to 70 meq / kg and a carboxyl group of 40 to 80 meq / kg. If the amino group as the terminal group of the polyamide resin is less than 20 meq / kg, printability and dyeability may be reduced, and it is difficult to increase the molecular weight of a polyamide exceeding 90 meq / kg. If the carboxyl group is less than 20 meq / kg, the adhesion to the surface-treated inorganic filler or the like may be deteriorated. If the carboxyl group exceeds 100 meq / kg, the thermal stability may be deteriorated. Get higher.

The tertiary amine used in the present invention is a tertiary amine represented by the following formula (a).

[0013]

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(In the formula (a), R ₁ , R ₂ and R ₃ each represent a molecular structure composed of a carbon atom, a hydrogen atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom, and the like. It may be the same or different.) A specific example is as follows. Tertiary amines having the same alkyl group such as trimethylamine, triethylamine, tributylamine, trioctylamine, trihexylamine, tridecylamine, tridodecylamine, tritetradecylamine, trihexadecylamine and trioctadecylamine. Dimethylhexylamine, dimethyloctylamine, dimethyldecylamine,
Dimethylalkylamines such as dimethyldodecylamine, dimethyltetradecylamine, dimethylhexadecylamine, dimethyloctadecylamine, dimethyleicosanylamine, dimethyloctadecenylamine, and dimethyloctadecadienylamine; Diethylhexylamine, diethyloctylamine, diethyldecylamine,
Diethylalkylamines such as diethyldodecylamine, diethyltetradecylamine, diethylhexadecylamine and diethyloctadecylamine;

Dibutylalkylamines such as dibutylhexylamine, dibutyloctylamine, dibutyldecylamine, dibutyldodecylamine, dibutyltetradecylamine, dibutylhexadecylamine and dibutyloctadecylamine; Monomethyldihexylamine, monomethyldioctylamine, monomethyldidecylamine, monomethyldidodecylamine, monomethylditetradecylamine, monomethyldihexadecylamine, monomethyldioctadecylamine, monomethyldioctadecenylamine, monomethyldioctadecenylamine, etc. Of monomethyldialkylamine. Monoethyldihexylamine, monoethyldioctylamine, monoethyldidecylamine, monoethyldidodecylamine, monoethylditetradecylamine, monoethyldihexadecylamine,
Monoethyldialkylamines such as monoethyldioctadecylamine.

Monobutyldialkylamines such as monobutyldihexylamine, monobutyldioctylamine, monobutyldidecylamine, monobutyldidodecylamine, monobutylditetradecylamine, monobutyldihexadecylamine and monobutyldioctadecylamine . Methylbenzylhexadecylamine, ethylbenzylhexadecylamine, butylbenzylhexadecylamine,
Tertiary amines having an aromatic ring such as monobenzyldihexadecylamine and dimethylbenzylamine. Tertiary amines derived from aromatic amines such as dimethylphenylamine. An alkyl [PE represented by the following formula (b) or (c) or (d)
G] or [PPG] amine ([PEG] represents a polyethylene glycol chain, [PPG] represents a polypropylene glycol chain, and the same applies to the following).

[0017]

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[0018]

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[0019]

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(However, equations (b), (c), and (d)
Wherein R ₄ , R ₅ , and R _{6 each} independently represent an alkyl group having 6 to 20 carbon atoms, and m ₁ , m ₂ , m ₃ , n ₁ , n ₂ , and n ₃ are 1
Is an integer greater than or equal to. 2 <m ₁ , m ₂ , m ₃ , n ₁ ,
n ₂ , n ₃ <60, preferably 6 ≦ m ₁ , m ₂ , m ₃ ,
n ₁ , n ₂ , n ₃ ≦ 30. Specific examples of the monoalkylbis [PEG] amine represented by the formulas (b), (c) and (d) include monomethylbis [PEG] amine, monoethylbis [PEG] amine and monobutyl [PEG]. Tertiary amine having a polyethylene glycol chain such as amine, monomethylbis [PP
G] amines, tertiary amines having a polypropylene glycol chain such as monoethylbis [PPG] amine and monobutyl [PPG] amine, and other products containing a hydroxy group of methacrylic acid and products containing a 3-alkoxy-2-hydroxypropyl group.

Among them, dimethylmonohexylamine, dimethylmonodecylamine, dimethylmonooctylamine, dimethylmonododecylamine, monomethyldihexylamine, monomethyldidecylamine, monomethyldioctylamine, monomethyldidodecylamine, monomethylditetradecylamine, monomethyl Dihexadecylamine, monomethyldioctadecylamine, monoethyldihexylamine, monoethyldidecylamine, monoethyldioctylamine, monoethyldidodecylamine, monoethylditetradecylamine, monoethyldihexadecylamine, monoethyldioctadecyl Tertiary amines having at least one alkyl group having 6 to 30 carbon atoms such as amines in one molecule; monomethylbis [PEG] amine, monoethylbis PEG] amine, monobutylbis [PEG] amine, monotetradecylbis [PEG] amine, monohexadecylbis [PEG] amine, monododecylbis [PEG] amine, monooctadecylbis [PEG] amine, etc. Tertiary amine having two in the molecule; monomethylbis [PP
G] amine, monoethylbis [PPG] amine, monobutylbis [PPG] amine, monotetradecylbis [P
PG] amine, monohexadecylbis [PPG] amine, monododecylbis [PPG] amine, tertiary amine having two polypropylene glycol chains in one molecule such as monooctadecylbis [PPG] amine, etc. are polyamide resin compositions. Tertiary amine having at least one alkyl group having 6 or more carbon atoms in one molecule, and is most preferable.
Monomethyldidecylamine, monomethyldioctadecylamine, trioctylamine and monomethyldihexylamine. Incidentally, these tertiary amines can be used alone or as a mixture of plural kinds.

In a layered silicate obtained by intercalating a tertiary amine having no alkyl group having 6 or more carbon atoms,
The compatibility with the polyamide may be reduced, and the mechanical properties may be reduced due to poor dispersion of the layered silicate. The amount of the tertiary amine is preferably 70 to 300%, more preferably 90 to 200%, based on the cation exchange capacity of the layered silicate.
More preferably, it is in the range of 99 to 150%. When the intercalation amount of the tertiary amine is less than 70% of the layered silicate cation exchange capacity, the layered silicate is difficult to be uniformly dispersed in the polyamide resin in a molecular state, and when it exceeds 300%, the thermal stability during molding is increased. May be worse.

The layer silicate in the present invention is a layer phyllosilicate composed of a magnesium silicate or aluminum silicate layer, and specifically includes montmorillonite, swellable fluoromica, saponite, beidellite,
Hectorite, stevensite, vermiculite,
Halloysite and the like can be exemplified, and preferably montmorillonite, swellable fluoromica, and more preferably swellable fluoromica. These may be synthetic or natural.

The layered silicate is more preferably a highly purified layered silicate of 95% or more obtained from a naturally occurring layered silicate or a synthesized layered silicate. In the case of swellable fluoromica, talc or silica fluoride is preferable. Those synthesized in the solid phase using sodium chloride and / or lithium silicofluoride as a raw material are more preferable. The layered silicate has a water swelling property, and the cation exchange capacity of the layered silicate is 30 to 300 meq / l.
00g is preferred, and more preferably 60 to 300 meq / 100g. If the cation exchange capacity is less than 30 meq / 100 g, the layered silicate does not sufficiently swell in the polymer, so that it tends to be difficult to uniformly and molecularly disperse it in the polyamide resin. The layered silicate in excess of / 100 g is hardly present in nature or is industrially difficult to synthesize.

In the present invention, the layered silicate preferably contains an alkali or alkaline earth metal ion or the like between the layers, and these ions are preferably Na ⁺ ions or Li ⁺ ions. These interlayer ions are ion-substituted with ammonium ions and mixed with a polyamide monomer or polyamide resin. The shape of the layered silicate used in the present invention has a layered crystal structure, and the length of one side of the layer is preferably in the range of 10 to 5000 nm on average, and the thickness of one layer is preferably 6 to 10 °. .

In the present invention, the layered silicate is contained in the polyamide resin in an average particle size of 1 μm or less, preferably 0.7 μm or less.
It is preferable that 50% by weight or more thereof is uniformly dispersed at an average distance of 2 nm or more in the range of 500 nm to 500 nm. The amount of the layered silicate added is 10
The amount is 0.5 to 30 parts by weight, preferably 1 to 10 parts by weight, more preferably 2 to 5 parts by weight with respect to 0 parts by weight. If the addition amount is less than 0.5 part by weight, the effect of improving rigidity is insufficient, and if it exceeds 30 parts by weight, it becomes difficult to uniformly disperse the layered silicate in a molecular state.

In the present invention, the polyamide resin composition contains at least 10% by weight of a polyamide resin,
Preferably, it may be a mixture with a resin other than the polyamide resin as long as it contains 20% by weight or more. Examples of the resin other than the polyamide resin include polyethylene, polypropylene, polystyrene, acrylonitrile-styrene resin, acrylonitrile-butadiene-styrene resin. ,
Examples include styrene-butadiene block copolymers and hydrogenated products thereof, thermoplastic polyesters, polymethyl methacrylate, polycarbonate, polyphenylene ether, polyoxymethylene, polyphenylene sulfide, polysulfone, polyether sulfone, polyether imide, polyether ether ketone, and the like. can do.

When these resins are mixed with a polyamide resin composition, two or more kinds may be used in combination. When these resins are mixed with the polyamide resin composition, in the case of a combination incompatible with the polyamide resin, a compatibilizer can be blended. As such a compatibilizing agent, conventionally known ones can be widely used.

If necessary, the polyamide resin composition may contain a dye, a pigment, a fibrous reinforcement (glass fiber, carbon fiber, etc.), a particulate reinforcement, a moldability improver such as a release agent, a thickener, and a plasticizer. Agents, lubricants, impact resistance improving agents, foaming agents, heat resistance improving agents, weathering agents, flame retardants, nucleating agents, and the like. As a method for producing the polyamide resin composition of the present invention, a method of adding a layered silicate to a polyamide monomer and polymerizing (polymerization method), a method of blending a polyamide resin and a layered silicate and then melt-kneading (melting) Kneading method) is preferred. In the polymerization method, a layered silicate obtained by intercalating a tertiary amine into a polyamide monomer is mixed and stirred, and while the layered silicate is previously dispersed in the polyamide monomer, the temperature is increased while stirring, and the dehydration and the polymerization reaction are performed under nitrogen. It is good to carry out with gas flow. In addition, as a melt kneading method, a twin-screw extruder provided with two or more zones for increasing kneading (screw using parts for increasing compression, shearing, and diverting, for example, a screw having a shallow groove, a kneading disk, etc.). It is preferable that the mixture is melt-kneaded while being deaerated.

The polyamide resin composition of the present invention can be prepared by a known method generally used for molding a thermoplastic resin,
For example, it is molded into various molded articles by a method such as injection molding, blow molding, inflation molding, vacuum molding, extrusion molding, and heat and pressure molding.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples. The preparation method, evaluation method, and the like are as follows. [Method of intercalating amine into layered silicate] 50 g of layered silicate shown in Table 1 was mixed and dispersed in 2 liters of water, and the amine or ammonium salt shown in the table and a 35% hydrochloric acid aqueous solution were added thereto. 1.5 times the equivalent of the cation exchange capacity of the layered silicate was added, and the mixture was heated to 80 ° C. and stirred for 60 minutes. (The hydrochloric acid aqueous solution was not added when the ammonium salt was added.) Further, using a Buchner funnel, suction filtration was performed while sufficiently washing with water, followed by vacuum drying at 80 ° C. for 48 hours. Then, a dry solid mass of a layered silicate in which sodium ions between layers were replaced with ammonium ions was obtained, and this mass-like composite was pulverized to about 0.3 to 10 μm with a pulverizer to obtain a powder.

[0032]

[Table 1]

[Evaluation Items and Methods] (a) Dispersibility Ultra-thin sections of resin composition pellets obtained by the methods of Examples and Comparative Examples were cut out, and dispersibility was measured with a transmission electron microscope manufactured by JEOL Ltd. Observation was performed using JEM1200.
The evaluation with a transmission electron microscope was performed based on the following criteria.

：: Good dispersibility (50% or more of a layer having a thickness of 1 μm or less) ×: Poor dispersibility (a layer of less than 50% of a layer having a thickness of 1 μm or less) ××: Very poor (Most exist in a lump of 1 μm or more) (b) Tensile strength and tensile elongation The resin composite materials obtained from the methods of Examples and Comparative Examples were
Using a JSW-J100SS-II molding machine manufactured by Nippon Steel Works Co., Ltd., an ASTM No. 3 dumbbell molded product was injection molded at a resin temperature of 295 ° C. ASTM
Evaluation of tensile strength and tensile elongation was performed according to D123.

(C) Flexural Modulus The resin composite materials obtained by the methods of Examples and Comparative Examples were
Using a JSW-J100SS-II molding machine manufactured by Nippon Steel Works Co., Ltd., an ASTM No. 3 strip-shaped molded product was injection molded at a resin temperature of 295 ° C. This strip forming form is referred to as ASTM D79
The flexural modulus was evaluated according to 0.

(D) Thermal stability during molding The resin composite materials obtained by the methods of Examples and Comparative Examples were
Using a JSW-J100SS-II molding machine manufactured by Nippon Steel Works Co., Ltd., an ASTM No. 3 strip-shaped molded product was injection molded at a resin temperature of 295 ° C. This strip-formed body was visually observed to evaluate the presence or absence of air bubbles. The evaluation criteria were as follows.

：: no bubbles in the molded body ×: bubbles in the molded body

[0038]

Examples 1 to 5 Polyamide 66 manufactured by Asahi Kasei Kogyo Co., Ltd.
The resin Leona 1300 and the layered silicate were mixed in the types and amounts shown in Table 2, respectively, and melt-kneaded pellets were obtained while degassing at a resin temperature of 295 ° C. using a twin screw extruder ZSK25 manufactured by Werner & Friedler. Then, a polyamide resin composite material pellet was obtained. The pellets thus obtained were dried at 80 ° C. for 24 hours in a nitrogen flow atmosphere, and were subjected to predetermined evaluation.

Table 2 shows the results.

[0040]

Comparative Examples 1 to 4 Examples 1 to 4 were repeated except that the types and amounts of the polyamide resin and the layered silicate shown in Table 3 were used.
A test piece was prepared and evaluated in the same manner as in No. 4. Table 3 shows the results.

[0041]

[Table 2]

[0042]

[Table 3]

As is clear from the table, the polyamide resin composition of the present invention has a higher flexural modulus and a higher tensile strength than a polyamide resin composite material comprising a layered silicate having an amino acid and a polyamide salt and a polyamide resin. Excellent in tensile elongation and excellent in thermal stability during molding.

[0044]

The polyamide resin composition of the present invention has excellent flexural modulus, tensile strength, tensile elongation, and thermal stability during molding. Accordingly, the polyamide resin composition of the present invention can be used, for example, as a vehicle exterior part, a wheel cover, a door mirror stay, a roof leg, a sunroof deflector, and as an automobile interior part, an instrument panel, a wire harness connector, and a water pump for a tara radiator. Impeller, wiper motor cover,
Thrust wire of canister, distributor cam, transmission, bearing, rotary sealing, bush, door bushing, brake leader, seat roller, radiator tank, fuel tank, harness, connector, engine parts, engine cover, intake manifold, cylinder Head covers, shock absorber parts, etc. Sockets, switches, fuse boxes, as OA and electronic components
Fuse case, electric heater parts, SMT connector,
Connectors, copier parts. It is also suitable for a wide range of applications such as bicycle wheels, fishing gear reels, desk legs, chair legs, structural materials such as crescents (key covers for sashes), vehicle parts, daily necessities, toys, miscellaneous goods, and building material parts.

Claims (5)

[Claims] 1. A layered silicate having an intercalated tertiary amine of 0.5 to 3 parts by weight, based on 100 parts by weight of a polyamide resin.
A polyamide resin composition comprising 0 parts by weight. 2. The layered silicate has a cation exchange capacity of 30.
The polyamide resin composition according to claim 1, wherein the composition is a layered silicate having a milliequivalent / 100 g or more. 3. The polyamide resin composition according to claim 1, wherein at least 70% of the ion exchange capacity of the layered silicate is intercalated with a tertiary amine. 4. The polyamide resin composition according to claim 1, wherein the layered silicate is swellable fluoromica. 5. The method according to claim 1, wherein the tertiary amine has at least one alkyl group having 6 or more carbon atoms.
5. The polyamide resin composition according to 2, 3, or 4.