JP2014080574A - Polyamide resin composition and molding obtained by molding the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition capable of being molded into a polyamide resin molding having excellent weld strength and brightness while having rigidity.SOLUTION: The polyamide resin composition includes: 100 pts.mass of a polyamide resin (A); 1 to 10 pts.mass of a swellable layered silicate (B); and 0.5 to 5 pts.mass of a metallic pigment (C). The polyamide resin composition is characterized in that the polyamide resin (A) is constituted of two or more kinds of amino carboxylic acid units.

Description

  The present invention relates to a polyamide resin composition capable of molding a polyamide resin molded article having excellent weld strength and luminance while having rigidity.

A molded body formed of a thermoplastic resin such as a polyamide resin is generally used for an interior / exterior cover of an automobile engine cover or home appliance.
The appearance of such a resin molded body may require a metallic color tone such as steel or aluminum alloy. In particular, in recent years, there has been an increasing demand for the aesthetics of resin moldings, and the appearance of resin moldings is required not only to have a metallic color tone, but also to have a glossy appearance and a high luster. . In addition, various kinds of metallic tones are required, from silver-gray to slightly whiteish gray.

  In order to satisfy such requirements, conventionally, a method of applying a paint containing metal powder such as aluminum on the surface of a resin molded body, so-called metallic coating, has been performed. However, since this metallic coating uses an organic solvent, there is a problem in terms of work environment, and there is also a problem that the productivity is inferior and the cost is high.

As a method for solving the above problems, a resin composition obtained by filling a thermoplastic resin such as polyamide resin with metallic particles such as aluminum or glossy particles whose surfaces such as mica, wollastonite and glass are coated with metal. It has been proposed to mold using objects.
For example, Patent Document 1 discloses a polyamide resin composition in which particles expressing a metallic color are blended with a polyamide resin in which layered silicate is uniformly dispersed at a molecular level. Patent Document 2 discloses a polyamide resin composition containing a polyamide resin and metal flakes.

International Publication No. 99/13006 Special table 2001-509524 gazette

However, the molded body obtained from the polyamide resin composition described in Patent Documents 1 and 2 containing layered silicate, metal flakes and the like with respect to the polyamide resin has a metallic color tone, but has a weld strength. In addition to being inferior and the appearance of the welded portion inferior, there was a problem of low brightness.
An object of the present invention is to solve the above-mentioned problems and to provide a polyamide resin composition capable of forming a polyamide resin molded article having excellent weld strength and luminance while having rigidity.

As a result of intensive studies to solve such problems, the present inventors have found that a resin composition using a polyamide resin having a specific configuration can solve the above problems, and reached the present invention. did.
That is, the gist of the present invention is as follows.

(1) A polyamide resin composition comprising 100 parts by weight of a polyamide resin (A), 1 to 10 parts by weight of a swellable layered silicate (B), and 0.5 to 5 parts by weight of a metallic pigment (C). Resin (A) is comprised from 2 or more types of aminocarboxylic acid units, The polyamide resin composition characterized by the above-mentioned.
(2) The polyamide resin composition according to (1), wherein the polyamide resin (A) is a copolymer composed of two or more aminocarboxylic acid units.
(3) The polyamide resin (A) is a copolymer composed of a 6-aminocaproic acid unit and an 11-aminoundecanoic acid unit and / or a 12-aminododecanoic acid unit. -Content of an amino caproic acid unit is 60-90 mass%, The polyamide resin composition as described in (2) characterized by the above-mentioned.
(4) The polyamide resin composition according to (1), wherein the polyamide resin (A) is a molten mixture of two or more polymers composed of aminocarboxylic acid units.
(5) The polyamide resin (A) is a molten mixture of polyamide 6 and polyamide 11 and / or polyamide 12, and the polyamide 6 content in the polyamide resin (A) is 60 to 90% by mass. The polyamide resin composition according to (4).
(6) The polyamide resin composition according to (1), wherein the swellable layered silicate (B) is any one selected from fluorine mica, montmorillonite, and hectorite.
(7) The polyamide resin composition according to (1), wherein the metallic pigment (C) is any one selected from aluminum, iron, oxides thereof, and titanium-coated mica.
(8) The polyamide resin composition according to (1), further comprising a weathering agent (D).
(9) The polyamide resin composition according to (1), further comprising lithium halide and / or nigrosine.
(10) A method for producing the polyamide resin composition according to (2) or (3) above, comprising a polymerization reaction step of a copolymer carried out in the presence of the swellable layered silicate (B). A process for producing a polyamide resin composition characterized by the above.
(11) A method for producing the polyamide resin composition according to (4) or (5) above, wherein at least one polymerization reaction step of the polymer is performed in the presence of the swellable layered silicate (B). The manufacturing method of the polyamide resin composition characterized by including.
(12) A molded article obtained by molding the polyamide resin composition according to any one of (1) to (9).

The polyamide resin composition of the present invention contains a metallic pigment, the polyamide resin is composed of two or more aminocarboxylic acid units, and also contains a swellable layered silicate, so that it has rigidity, weld strength, brightness. Can be provided.
Moreover, the outstanding weather resistance can be provided to a molded object by combining the polyamide 6, and the polyamide 11 and / or the polyamide 12 as a polyamide resin.

  The polyamide resin composition of the present invention comprises a polyamide resin (A), a swellable layered silicate (B), and a metallic pigment (C), and the polyamide resin (A) comprises two or more amino acids. It must be composed of carboxylic acid units.

  Examples of the aminocarboxylic acid unit constituting the polyamide resin (A) include 6-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, paraaminomethylbenzoic acid and the like. Since the effect of uniformly dispersing the swellable layered silicate (B) contained in the polyamide resin composition is high, it is preferable to contain 6-aminocaproic acid as a structural unit, and the weld strength of the obtained molded body Therefore, it is preferable to contain 11-aminoundecanoic acid and / or 12-aminododecanoic acid as a structural unit.

  In the present invention, the polyamide resin (A) may be a copolymer composed of two or more of the above aminocarboxylic acid units, or may be melted using two or more polymers composed of the above aminocarboxylic acid units. It may be a mixture. When a copolymer is used as the polyamide resin (A), a molded article having particularly excellent weld strength can be obtained. On the other hand, when a molten mixture of two or more kinds of polymers is used as the polyamide resin (A), weather resistance is obtained. In particular, it is possible to obtain a molded article that is particularly excellent.

  When the polyamide resin (A) is a copolymer composed of two or more kinds of aminocarboxylic acid units, for the above reasons, a 6-aminocaproic acid unit, an 11-aminoundecanoic acid unit and / or 12-amino is used. A copolymer composed of dodecanoic acid units is preferred. That is, the polyamide resin (A) is a polyamide 6 / polyamide 11 copolymer (nylon 6/11), a polyamide 6 / polyamide 12 copolymer (nylon 6/12), or a polyamide 6 / polyamide 11 / polyamide 12 copolymer (nylon 6 / 11/12).

  The content of the 6-aminocaproic acid unit in the polyamide resin (A) is preferably 60 to 90% by mass, more preferably 65 to 85% by mass, and further preferably 70 to 80% by mass. . When the content of the 6-aminocaproic acid unit is less than 60% by mass, the resulting molded article has a reduced rigidity, whereas when it exceeds 90% by mass, the weld strength may be decreased.

Further, when the polyamide resin (A) is a molten mixture of two or more kinds of polymers, for the reasons described above, polyamide 6 composed of 6-aminocaproic acid units, polyamide 11 composed of 11-aminoundecanoic acid units, and / or Or it is preferable that it is a molten mixture with the polyamide 12 which consists of a 12-amino dodecanoic acid unit.
The content of polyamide 6 in the polyamide resin (A) is preferably 60 to 90% by mass, more preferably 65 to 85% by mass, and further preferably 70 to 80% by mass. When the content of polyamide 6 is less than 60% by mass, the resulting molded article has a reduced rigidity, while when it exceeds 90% by mass, the weld strength may be decreased.

  The polyamide resin (A) in the present invention is composed of two or more aminocarboxylic acid units as described above, but may contain a diamine unit and a dicarboxylic acid unit as long as the effects of the present invention are not impaired. Good. Examples of the diamine unit include tetramethylene diamine, hexamethylene diamine, undecamethylene diamine, and dodecamethylene diamine. Examples of the dicarboxylic acid unit include adipic acid, suberic acid, sebacic acid, dodecanedioic acid, terephthalic acid, and isophthalic acid. Etc. That is, the polyamide resin (A) in the present invention is polytetramethylene adipamide (nylon 46), polyhexamethylene adipamide (nylon 66), polyhexamethylene sebacamide as long as the effects of the present invention are not impaired. (Nylon 610), polyhexamethylene dodecamide (nylon 612), polyundecamethylene adipamide (nylon 116), polyhexamethylene terephthalamide (nylon 6T), polydecamethylene terephthalamide (nylon 10T), etc. Or may be melt-mixed.

  The relative viscosity, which is an index of the molecular weight of the polyamide resin (A), is not particularly limited, but the relative viscosity measured under the conditions of 96 mass% concentrated sulfuric acid as a solvent at a temperature of 25 ° C. and a concentration of 1 g / dl is 1.5 to 3.5 is preferable, 1.7 to 3.2 is more preferable, and 1.9 to 3.0 is even more preferable. If the relative viscosity is less than 1.5, the resulting polyamide resin composition may have a reduced weld strength. On the other hand, if the relative viscosity exceeds 3.5, the fluidity is inferior, the kneading becomes difficult, and the moldability is lowered, so that the luminance may be inferior.

  The polyamide resin composition of the present invention contains a metallic pigment (C) in order to improve the brightness of the resulting molded article, but together with the metallic pigment (C), a specific amount of swellable layered silicate ( It is necessary to contain B) simultaneously. By containing the swellable layered silicate (B), the dispersibility of the metallic pigment (C) can be improved, and by improving the dispersibility of the metallic pigment (C), the clear feeling is improved and the metallic Even if there is little content of a pigment (C), the clear feeling of a molded object can be improved efficiently.

  The swellable layered silicate (B) constituting the polyamide resin composition of the present invention may be naturally produced or artificially synthesized or modified, for example, smectite group (montmorillonite, beidellite, hectorite, soconite). Etc.), vermiculites (vermiculite, etc.), mica (fluorine mica, muscovite, paragonite, phlogopite, lepidrite, etc.), brittle mica (margarite, clintonite, anandite, etc.), chlorite (donbasite, sudite) , Kukeite, clinochlore, chamonite, nimite, etc.). In the present invention, Na-type or Li-type swellable fluorinated mica, montmorillonite, and hectorite are particularly preferably used, and two or more types may be used in combination.

The swellable fluorine mica preferably used in the present invention generally has a structural formula represented by the following formula.
M _a (Mg _X Li _b ) Si ₄ O _Y F _Z
(In the formula, M represents an ion-exchangeable cation, and specific examples include sodium and lithium. A, b, X, Y, and Z each represents a coefficient, and 0 ≦ a ≦ 0.5. 0 ≦ b ≦ 0.5, 2.5 ≦ X ≦ 3, 10 ≦ Y ≦ 11, 1.0 ≦ Z ≦ 2.0.)

As a method for producing such a swellable fluorinated mica, for example, silicon oxide, magnesium oxide and various fluorides are mixed, and the mixture is completely melted in a temperature range of 1400 to 1500 ° C. in an electric furnace or a gas furnace. A melting method in which a crystal of swellable fluorinated mica grows in the reaction vessel during the cooling process.
Further, there is a method of using talc [Mg ₃ Si ₄ O ₁₀ (OH) ₂ ] as a starting material and intercalating alkali metal ions to impart swellability to obtain a swellable fluorine mica (Japanese Patent Laid-Open No. Hei. No. 2-149415). In this method, swellable fluoromica can be obtained by heat-treating talc and alkali silicofluoride mixed at a predetermined blending ratio in a magnetic crucible at a temperature of 700 to 1200 ° C. for a short time. At this time, the amount of alkali silicofluoride mixed with talc is preferably in the range of 10 to 35% by mass of the entire mixture. When it is outside this range, the yield of the swellable fluorinated mica tends to decrease.

The montmorillonite used in the present invention is represented by the following formula, and can be obtained by refining a naturally produced product using a water syrup treatment or the like.
M _a Si (Al ₂ -aMg) O ₁₀ (OH) ₂ .nH ₂ 0
(In the formula, M represents a cation such as sodium, and 0.25 ≦ a ≦ 0.6. Further, the number of water molecules bonded to the ion-exchangeable cation between layers depends on conditions such as cation species and humidity. (It is represented by nH ₂ O in the formula.)
In addition, montmorillonite is known to have isomorphic ion substitution products such as magnesia montmorillonite, iron montmorillonite, iron magnesia montmorillonite, and these may be used.

The hectorite used in the present invention is represented by the following formula, and may be naturally obtained or may be obtained by synthesis.
Na _0.66 (Mg _5.34 Li _0.66 ) Si ₈ O ₂₀ (OH) ₄ .nH ₂ O
Hectorite has a structure composed of a negatively charged silicate layer mainly composed of silicate and a cation having an ion exchange ability interposed between the layers, and compared with other swellable layered silicates, Since many hydroxyl groups are contained, water molecules are likely to enter between layers (that is, highly hydrophilic) and easily swell. In addition, the particle size is small compared to other swellable layered silicates.

  The content of the swellable layered silicate (B) in the polyamide resin composition of the present invention needs to be 1 to 10 parts by mass with respect to 100 parts by mass of the polyamide resin (A), and 2 to 9 parts by mass. It is preferable that it is 3-8 mass parts. When the content of the swellable layered silicate (B) is less than 1 part by mass, the clear feeling of the obtained molded article is insufficient or the bending elastic modulus is lowered. On the other hand, when the content exceeds 10 parts by mass, not only the smoothness and clearness of the resulting molded article are lowered, but also the weld strength is lowered.

  There is no restriction | limiting in particular as the metallic pigment (C) which comprises the polyamide resin composition of this invention, A well-known thing can be used. As the metallic pigment (C), for example, one or a plurality of metals made of aluminum, iron, nickel, chromium, tin, zinc, indium, titanium, silicon, and copper, or a plurality of these metals or a group of these metals are used. And metal powder pigments made of any of the oxides, nitrides, sulfides or carbides of these alloys or a group of these metals. In addition, titanium-coated mica can also be used. Among these, as the metallic pigment (C), aluminum, iron, oxides thereof, and titanium-coated mica are preferably used in that the effect of improving the glossiness of the polyamide resin composition is excellent. Also good.

The average particle diameter of the metallic pigment (C) is preferably 1 to 100 μm, more preferably 2 to 80 μm, further preferably 3 to 60 μm, and particularly preferably 4 to 40 μm. The metallic pigment (C) having an average particle size of less than 1 μm has a low effect of improving the glossiness and is difficult to obtain. On the other hand, if the average particle size of the metallic pigment (C) exceeds 60 μm, handling when obtaining a polyamide resin composition becomes difficult, and melt mixing is performed while maintaining the average particle size of the raw material metallic pigment (C). It becomes difficult to do. Moreover, even if melt-mixing is possible, the resulting molded article of the polyamide resin composition has a high gloss, but tends to be inferior in design.
The average particle diameter of the metallic pigment (C) can be measured by a laser diffraction / scattering particle size distribution measuring device, for example, Microtrack 2 (manufactured by Nikkiso Co., Ltd.).

The average thickness of the metallic pigment (C) is preferably 1 to 30 μm, more preferably 1 to 20 μm, and further preferably 1 to 10 μm. The metallic pigment (C) having an average thickness of less than 1 μm is inferior in rigidity and it is difficult to maintain the shape when melt-mixed, and thus it is difficult to obtain a molded body having sufficient glossiness. On the other hand, the metallic pigment (C) having an average thickness of more than 30 μm has a reduced orientation, and the resulting molded product is inferior in luminance.
The average thickness of the metallic pigment (C) can be calculated by a simple average of 50 metallic pigments measured with an electron microscope.

The aspect ratio (average particle diameter / average thickness) of the metallic pigment (C) is preferably 2 to 60, more preferably 2 to 50, and further preferably 2 to 30. When the aspect ratio is less than 2, the brightness of the obtained molded article is inferior. Those having an aspect ratio exceeding 60 are difficult to obtain industrially, and even if obtained, the dispersion stability is inferior, and the surface smoothness of the resulting molded article is impaired.
The aspect ratio of the metallic pigment (C) can be obtained by dividing the value of the average particle diameter by the average thickness value.

  Content of the metallic pigment (C) in the polyamide resin composition of this invention needs to be 0.5-5 mass parts with respect to 100 mass parts of polyamide resins (A), and 0.7-4 mass Part is preferable, and 1 to 3 parts by mass is more preferable. When the content of the metallic pigment (C) is less than 0.5 parts by mass, the resulting molded product has insufficient luminance. On the other hand, when the amount exceeds 5 parts by mass, the molded product not only has excessive brightness and deteriorates the design, but also the weld strength decreases.

As described above, the polyamide resin composition of the present invention contains a metallic pigment, the polyamide resin is composed of two or more aminocarboxylic acid units, and contains a swellable layered silicate, so that it has rigidity. Thus, a polyamide resin molded article having excellent weld strength and brightness can be obtained.
Moreover, the molded object formed by shape | molding the polyamide resin composition of this invention has the extremely improved weather resistance in outdoor use conditions.
When a polyamide resin molded body is used over a long period of time, usually outdoors or in an environment where it is directly exposed to sunlight, a cracked defect called crazing occurs on the surface of the molded body. Mild crazing only impairs the design, but severe crazing greatly reduces the mechanical properties of the molded body. In particular, the molded body containing a metallic pigment has a problem that crazing is remarkably generated starting from the metallic pigment. However, when the polyamide resin composition of the present invention is used, the occurrence of crazing in the molded product can be effectively suppressed.

  Further, in the polyamide resin composition of the present invention, when a polyamide resin (A) having a 6-aminocaproic acid unit and an 11-aminoundecanoic acid unit and / or a 12-aminododecanoic acid unit is used, a molded article is obtained. The effect of improving the weather resistance and the effect of improving the appearance of the weld portion can be increased. Usually, in an injection molded product of a resin composition containing a metallic pigment, when the molten resin flowing through the injection mold is merged, the metallic pigment (C) is oriented in a specific direction at the merged portion. As a result, the reflection of the weld part of the molded body is lost, and the weld part often becomes a black streak and impairs the design. Since the polyamide resin composition of the present invention uses the polyamide resin (A), not only the weather resistance of the molded product but also the appearance of the welded portion can be improved, and can be applied in a wide range of applications.

The polyamide resin composition of the present invention is excellent in weather resistance as described above, but may further contain a weathering agent (D) in order to further enhance its effect.
Examples of the weathering agent (D) include benzotriazole compounds, benzophenone compounds, triazine compounds, benzoate compounds, hindered amine compounds, salicylic acid phenyl ester compounds, cyanoacrylate compounds, malonic acid ester compounds, and oxalic acid. Examples include anilide compounds. These may be used alone or in combination of two or more. Of these, triazine compounds, malonic acid ester compounds, and oxalic anilide compounds are preferred. Moreover, since the hindered amine compound has a high effect of scavenging radicals and suppressing photooxidation of the polyamide resin composition, the effect of suppressing ultraviolet absorption in combination with other weathering agents is enhanced.

The content of the weathering agent (D) is preferably 0.1 to 2 parts by mass, and more preferably 0.2 to 1.8 parts by mass with respect to 100 parts by mass of the polyamide resin (A). When the content of the weathering agent (D) is less than 0.1 parts by mass, the effect of suppressing ultraviolet absorption becomes insufficient, and the resulting molded article may change in color tone or decrease in surface gloss. When the content of the weathering agent (D) exceeds 2 parts by mass, the effect of suppressing UV absorption is no longer saturated and uneconomical, and the weathering agent (D) bleeds out on the surface of the molded body, and molding is performed. The brightness and clearness of the body may be impaired, and the color tone may be changed.
Even when the hindered amine compound and the other weathering agent described above are used in combination as the weathering agent (D), the total amount of these contents is 0.1 to 2 with respect to 100 parts by mass of the polyamide resin (A). It is preferable that it is a mass part. The mass ratio of the hindered amine compound and other weathering agent (hindered amine compound / other weathering agent) is preferably 5/95 to 50/50, more preferably 15/85 to 45/55, More preferably, it is 25/75 to 40/60.

The polyamide resin composition of the present invention preferably contains lithium halide and / or nigrosine in order to improve the metallic feel of the resulting molded article.
The lithium halide used in the present invention is not particularly limited, and examples thereof include lithium chloride, lithium bromide, and lithium iodide. By blending lithium halide, the melting temperature and crystallization temperature of the polyamide resin are lowered, the fluidity is further improved, the flow mark of the molded body is reduced, and the metallic feeling can be improved. Lithium chloride is particularly preferable because of its high effect.
The content of the lithium halide is preferably 0.05 to 5 parts by weight, more preferably 0.1 to 2 parts by weight, with respect to 100 parts by weight of the polyamide resin (A). More preferably, it is 1 part by mass. If the content of the lithium halide is less than 0.05 parts by mass, the effect of improving the metallic feeling may not be sufficient. On the other hand, when the amount exceeds 5 parts by mass, problems such as a decrease in mechanical strength of the resulting molded article and bleeding out of lithium halide to the molded article surface may occur.
Furthermore, the polyamide resin composition of the present invention preferably contains potassium halide together with lithium halide. Examples of the potassium halide include potassium iodide, potassium bromide, and potassium chloride. By using potassium halide together, the dissolution of lithium halide in the polyamide resin composition is promoted, and in the resulting molded article, the effect of reducing the flow mark and improving the metallic feeling is further enhanced. The content of potassium halide is preferably 0.1 to 5 times that of lithium halide. If the amount is less than 0.1 times, the effect is poor, and if the amount exceeds 5 times, the effect may be saturated.

Nigrosine used in the present invention is not particularly limited, and examples thereof include COLOR INDEX and C.I. I. SOLVENT BLACK 5 and C.I. I. Mention may be made of black azine-based condensation mixtures such as those described as SOLVENT BLACK 7. Such nigrosine can be obtained, for example, by oxidizing and dehydrating condensation of aniline, aniline hydrochloride and nitrobenzene at a reaction temperature of 160 to 180 ° C. in the presence of iron chloride. Further, purified nigrosine obtained by purifying the nigrosine thus obtained and having an aniline or diphenylamine content of less than 0.1% may be used. As such nigrosine, Cramitity 81 and NUBIAN BLACK series manufactured by Orient Chemical Industry are commercially available.
By containing nigrosine, the melting temperature and crystallization temperature of the polyamide resin are lowered, the fluidity is further improved, the flow mark of the molded body is reduced, and the metallic feeling can be improved. Further, weather resistance can be further improved by using nigrosine.
The content of nigrosine is not particularly limited, but is preferably 0.1 to 1.0 part by mass with respect to 100 parts by mass of the polyamide resin (A).

  A pigment, a heat stabilizer, an antioxidant, a weathering agent, a plasticizer, a lubricant, a release agent, an antistatic agent, etc. may be added to the polyamide resin composition of the present invention as long as the properties are not significantly impaired. it can. Examples of heat stabilizers and antioxidants include sulfur compounds, copper compounds, and alkali metal halides. In addition, the method of mixing these with the resin composition of this invention is not specifically limited. Moreover, in order to assist flame retardancy in particular, a condensed phosphate ester, polyphosphoric acid, a nitrogen compound flame retardant, or the like may be added.

Next, the manufacturing method of the polyamide resin composition of this invention is demonstrated.
In the present invention, the polyamide resin composition can be produced by melt-kneading the polyamide resin (A), the swellable layered silicate (B), and the metallic pigment (C).
In the present invention, the polyamide resin (A) and the swellable layered silicate (B) obtained by polymerizing the monomer component constituting the polyamide resin (A) in the presence of the swellable layered silicate (B). It is preferable to produce a polyamide resin composition by melt-mixing the mixture and the metallic pigment (C) using a mixture of
In the presence of the swellable layered silicate (B), the monomer component constituting the polyamide resin (A) is polymerized to disperse the swellable layered silicate (B) uniformly in the polyamide resin (A). And the glossiness of the resulting molded article can be further increased.
As the monomer used in the polymerization reaction, an aminocarboxylic acid or a lactam thereof can be used. Therefore, the lactam may be used as an aminocarboxylic acid as a raw material for the polymerization reaction.

  When the polyamide resin (A) is a copolymer composed of two or more aminocarboxylic acid units, two or more aminocarboxylic acids (lactams) in the presence of the swellable layered silicate (B) It is preferable to produce a polyamide resin composition by using a mixture obtained by carrying out the copolymerization reaction of and melting and mixing the mixture and the metallic pigment (C).

In the case where the polyamide resin (A) is a molten mixture of two or more polymers composed of aminocarboxylic acid units, the polymerization reaction of at least one of the two or more polymers is performed. In the presence of the swellable layered silicate (B), a mixture of the resulting polymer and the swellable layered silicate (B) and another polymer (or other polymer and the swellable layered silicate (B) )) And the metallic pigment (C) are preferably melt mixed to produce a polyamide resin composition.
The aminocarboxylic acid that undergoes a polymerization reaction in the presence of the swellable layered silicate (B) has a high effect of uniformly dispersing the swellable layered silicate (B), and therefore 6-aminocaproic acid or ε-caprolactam Preferably there is.

As a method for polymerizing aminocarboxylic acid (lactam) in the presence of the swellable layered silicate (B), water is prepared after charging the swellable layered silicate (B) and aminocarboxylic acid (lactam) in an autoclave. The method of melt polycondensation method is used within the range of temperature 240-300 degreeC, pressure 0.2-3MPa, 1-15 hours using initiators, such as. When ε-caprolactam is used, it is preferable to polymerize at a temperature of 250 to 280 ° C., a pressure of 0.5 to 2 MPa, and a range of 3 to 5 hours.
Moreover, in order to remove the aminocarboxylic acid (lactam) remaining in the polyamide resin after polymerization, it is preferable to scour the polyamide resin pellets with hot water, and the condition is 90 to 100 ° C. For 8 hours or more in hot water.

When melt-mixing the mixture of the polyamide resin (A) and the swellable layered silicate (B) and the metallic pigment (C), a known melt-kneading extruder can be used.
In order to suppress crushing or breakage due to kneading of the metallic pigment (C) as much as possible, the screw is preferably used uniaxially rather than biaxially.
As a method for supplying the metallic pigment (C) to the melt-kneading extruder, a mixture of the metallic pigment (C) and the mixture may be added all at once from the main hopper, but the metallic pigment (C) may be crushed or In order to suppress breakage as much as possible, the metallic pigment (C) is preferably supplied from the middle of the extruder with a side feeder, and more preferably supplied downstream of the extruder.
The mixture and the metallic pigment (C) may not be sufficiently melt-kneaded, and may be mixed as long as the operation is not hindered in the subsequent injection molding process. If necessary, a mixture obtained by dry blending the mixture and the metallic pigment (C) may be directly supplied to an injection molding machine, or may be melt-kneaded in the injection molding machine to perform injection molding.
Since the metallic pigment (C) is brittle with respect to external stress, in this way, the screw shear stress during melt kneading should not be applied to the metallic pigment (C) as much as possible in the production of the resin composition and the molding of the molded body. Is preferable for improving the glossiness of the molded article to be obtained.

The molded article of the present invention is formed by molding the polyamide resin composition of the present invention. Examples of the molding method include injection molding, blow molding, extrusion molding, inflation molding, and post-sheet processing such as vacuum molding, pressure molding, and vacuum / pressure molding. Among these, it is preferable to use the injection molding method. In addition to typical injection molding methods, gas injection molding, injection press molding, and the like can also be employed.
As injection molding conditions suitable for the polyamide resin composition of the present invention, for example, the cylinder temperature is equal to or higher than the melting point or flow start temperature of the resin composition, preferably 190 to 270 ° C., and the mold temperature is ( The melting point is −20 ° C. or less. If the molding temperature is too low, the moldability may become unstable, for example, a short may occur in the molded body, or the glossiness of the surface of the resulting molded body may be lost. On the other hand, when the molding temperature is too high, the polyamide resin composition is decomposed, and the strength of the resulting molded product may be reduced, or the glossiness may be reduced.
The molded article of the present invention, particularly a molded article obtained by the injection molding method, has high brightness, but various conditions during injection molding, such as resin temperature, injection speed, injection pressure, mold temperature, are well balanced. By setting, the luminance can be further improved. In addition, these conditions are the fluidity | liquidity in the metal mold | die of the fuse | melted polyamide resin composition, Furthermore, the dispersibility of the swellable layered silicate (B) and a metallic pigment (C) in a polyamide resin composition. It needs to be set carefully because it has an impact. For example, when the injection speed is high, the orientation of the metallic pigment (C) is disturbed and the brightness tends to decrease. Therefore, the injection speed is preferably from low to medium.

  Specific examples of the molded article of the present invention include various automobile parts, electric and electronic parts. Since the molded body of the present invention is excellent in brightness, such as metallic luster, especially as a resin part, as an automobile part, various instruments such as a speedometer, a tachometer, a fuel meter, a water temperature meter, a distance meter in an instrument panel, etc. , Car stereos, navigation systems, various switches around air conditioners, buttons, shift levers at the center console, side brake grips, door trims, armrests, door levers, etc. It can be used as a replacement material for plastic parts. As electrical and electronic parts, various parts and casings around a personal computer, cellular phone parts and casings, and other resin parts for electrical appliances such as OA equipment parts can be used. Moreover, since it is excellent in weather resistance and the appearance of the wild portion, it is suitable for long-term use such as automobile parts.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples.

1. Evaluation Method (1) Smoothness The smoothness of the obtained plate-like molded product was visually evaluated.
○: Mold transfer is sufficient and smooth.
Δ: The pigment contained does not float or sink, but the smoothness is slightly inferior.
X: The pigment contained contained is floated or sinked, and has no smoothness.

(2) Spots of color tone The plate-like molded product was observed with the naked eye, and the dispersion state of the contained pigment was evaluated.
○: Uniformly dispersed.
(Triangle | delta): There are some spots in dispersion | distribution and shading is seen.
X: Light and shade are seen, and pigments are locally aggregated.

(3) Surface glossiness Based on JIS Z8741, the surface glossiness of the plate-shaped molded body was measured using a gloss meter (Nippon Denshoku Co., Ltd. gloss meter VG7000). The glossiness is preferably 90% or more practically.

(4) Luminance The luminance was sensory-evaluated with the naked eye by observing from a direction of an angle of 45 ° with the normal line of the plate-shaped molded body under a fluorescent lamp having an illuminance of 1000 Lx.
5: It has a glare feeling but is excessive.
4: Although it has a glare feeling, it is slightly excessive.
3: It has a moderate glare feeling.
2: The metal-specific brightness is insufficient.
1: Does not have metal-specific shine.

(5) Clear feeling The plate-like molded body was observed from various angles under a fluorescent lamp with an illuminance of 1000 Lx, and the clear feeling was subjected to sensory evaluation with the naked eye.
○: When a fluorescent lamp is projected on the surface of the plate-shaped molded body, the shape of the fluorescent lamp can be seen as it is.
(Triangle | delta): When a fluorescent lamp is projected on the plate-shaped molded object surface, although the shape of a fluorescent lamp can be seen, the line of a fluorescent lamp appears blurred.
X: Even if a fluorescent lamp is projected on the surface of the plate-shaped molded body, the shape of the fluorescent lamp cannot be recognized.

(6) Weld part appearance In injection molding, molten resin is allowed to flow from the side gates at both ends of the mold at the same time. Is the joining interface (line) clearly visible at the resin joining part formed at the center of the resulting plate-like molded product? It was judged visually. In addition, in the polyamide resin composition of the present invention, unlike the usual evaluation of the weld part (particularly, the strength of the weld part is reduced), the appearance of the metallic pigment contained in the composition changes sharply at the resin joining part. Special evaluations were made for these defects.
4: The line is not visible.
3: The line is inconspicuous.
2: The line can be visually recognized, but it is not clear.
1: Anisotropy occurs in the orientation of the metallic pigment, and the line is clearly visible in a linear shape.

(7) Flow Mark The plate-like molded body was observed from various angles under a fluorescent lamp with an illuminance of 1000 Lx, and the presence or absence of the flow mark was evaluated with the naked eye. The flow mark is a flow unevenness of the metallic pigment, and it is better that there is no flow mark.
4: There is no flow mark.
3: There is a flow mark in the molded body gate.
2: There are flow marks at the molded body gate and the periphery (flow end) of the molded body.
1: There is a flow mark throughout the molded body.

(8) Weather resistance Using a sunshine weather meter (S80 type manufactured by Suga Test Instruments Co., Ltd.), the plate-shaped molded body was subjected to conditions of a black panel temperature of 63 ° C., a humidity of 50% RH, and a rainfall time of 18 minutes (120 minutes cycle). A 500 hour test was conducted. The weather resistance was evaluated by measuring the color difference and the surface gloss before and after the test.
The color difference was measured based on JIS Z 8722 using a gloss meter (spectral color difference meter SE6000 manufactured by Nippon Denshoku Co., Ltd.). In practice, the color difference after the weather resistance test is preferably such that ΔE is 3 or less.
The glossiness was measured based on JIS Z 8741 using a gloss meter (Gloss Meter VG7000 manufactured by Nippon Denshoku Co., Ltd.). In practice, the gloss retention after the weather resistance test is preferably 80% or more.

(9) Bending elastic modulus Based on ISO178, the bending elastic modulus of the plate-shaped molded body was measured. The flexural modulus is preferably 3 GPa or more, and more preferably 4 GPa.

(10) Tensile strength retention ratio of weld part Using the obtained resin composition, with an injection molding machine (EC-100II type manufactured by Toshiba Machine Co., Ltd.), resin temperature 260 ° C., mold temperature 100 ° C., holding pressure 30 MPa, A test piece (multipurpose test piece according to ASTM D 638-95, test piece A) was molded with a two-point gate from both ends at an injection speed of 100 mm / s, an injection pressure of 100 MPa, and a cooling time of 10 seconds. Moreover, the same test piece (no weld, test piece B) was molded using the same mold at a one-point gate, and the respective tensile strengths were measured according to ASTM D638. The ratio of the tensile strength of the test piece A having the weld portion to the tensile strength of the test piece B was calculated by the following formula, the retention ratio of the tensile strength of the weld portion was calculated, and the weld strength was evaluated.
Tensile strength retention ratio of weld part (%) = {(tensile strength of test piece A having weld part) / (tensile strength of test piece B)} × 100
Practically, the tensile strength retention ratio of the weld portion is preferably 60% or more, and more preferably 65% or more.

2. Raw material (1) Polyamide resin monomer component, ε-caprolactam (manufactured by Ube Industries)
・ 11-Aminoundecanoic acid (manufactured by Junsei Co., Ltd.)
・ 12-aminododecanoic acid (manufactured by Ube Industries)
(2) Polyamide resin PA6: Polyamide 6 ("A1030BRL" manufactured by Unitika)
PA11: Polyamide 11 (“BMN O” manufactured by Arkema)
PA12: Polyamide 12 (“AMN O TLD” manufactured by Arkema)
PA66: Polyamide 66 (“E2000” manufactured by Unitika)

(3) Swellable layered silicate B-1: Swellable fluorinated mica ("ME-100" manufactured by Co-op Chemical)
B-2: Hectorite ("Bentone HC" manufactured by Elementis Specialties)
B-3: Montmorillonite (Hogel Jun. “Bengel HV”)

(4) Metallic pigment / C-1: Aluminum powder masterbatch (“NME U20TZ” manufactured by Toyo Aluminum Co., Ltd., aluminum powder (average particle diameter 20 μm, average thickness 4 μm) kneaded in 70% by mass)
C-2: Pearl pigment (“Iriodin # 100” manufactured by Merck Japan, mica (average particle diameter 20 μm, average thickness 0.3 μm) coated with 0.1 μm titanium)

(5) Weathering agent D-1: hindered amine light stabilizer (“Tinuvin 770” manufactured by BASF)
D-2: Benzotriazole UV absorber (“Tinuvin 234” manufactured by BASF)
D-3: An oxalic acid anilide ultraviolet absorber (“Sanduvor VSU” manufactured by Clariant)

(6) Nigrosine ("Cramity 81" manufactured by Orient Chemical Co., Ltd.)
(7) Lithium chloride (reagent)

Example 1
80 parts by mass of ε-caprolactam and 20 parts by mass of 11-aminoundecanoic acid were charged with 0.4 parts by mass of phosphorous acid, 5 parts by mass of swellable layered silicate (B-1), and 5 parts by mass of water. The mixture was stirred at 260 ° C. for 1 hour, then stirred at 260 ° C. and 0.7 MPa for 1 hour, then stirred at 260 ° C. and normal pressure for 1 hour to conduct polymerization, and the swellable layered silicate (B-1) was added to 5. A polyamide resin (P-1) containing 2% by mass was obtained.
The obtained swellable layered silicate-containing polyamide resin (P-1) and metallic pigment (C-1) were mixed together so as to have the blending amounts shown in Table 1, and from the main hopper of the single screw extruder The resulting mixture was melt kneaded and extruded into a strand from a die, and then cooled and pelletized to obtain polyamide resin composition pellets. The melt kneading was performed at a resin temperature of 260 ° C., a screw rotation of 200 rpm, and a discharge rate of 30 kg / h.
Using the obtained polyamide resin composition, with an injection molding machine (EC-100II type manufactured by Toshiba Machine Co., Ltd.), the resin temperature is 260 ° C., the mold temperature is 100 ° C., the holding pressure is 30 MPa, the injection speed is 100 mm / s, and the injection pressure. Injection molding was performed under the conditions of 100 MPa and a cooling time of 10 seconds to obtain a plate-like molded body having a length of 90 mm × width of 50 mm × thickness of 2 mm. In addition, although the metal mold | die which has one side gate in the center of a short side direction was used, for the shaping | molding of the molded object for weld evaluation, what has a side gate in each of two opposing short side direction centers. Using. Table 2 shows the results of various evaluations using the obtained plate-shaped molded body.

Examples 2-24, Comparative Examples 1-9
Swellable layered silicate-containing polyamide resins (P-2) to (P-12) were obtained in the same manner as in Example 1 except that the charging composition shown in Table 1 was used. Subsequently, except having mix | blended each component with the compounding quantity of Table 1, it carried out similarly to Example 1, and obtained the polyamide resin composition pellet, and also performed injection molding. Various evaluation was performed using the obtained plate-shaped molded object. The results are shown in Table 2. However, in Example 11, instead of the single screw extruder, polyamide resin composition pellets were produced using a twin screw extruder.

  In Examples 1 to 24, since each component constituting the resin composition is within the range specified by the present invention, the obtained molded articles were excellent in weld strength and luminance. In the example using a copolymer as the polyamide resin (A), the weld strength tends to be improved, and in the example in which two or more polymers are melt-mixed, the weather resistance tends to be improved. Since Examples 19 to 22 contained a weathering agent (D) in the resin composition, the obtained molded article had further improved weather resistance as compared with Example 1. In Examples 23 and 24, since the resin composition contains nigrosine or lithium chloride, the fluidity was improved, and the obtained molded article had a reduced flow mark and an improved weld strength.

In Comparative Example 1, since the content of the metallic pigment (C) in the resin composition was less than the lower limit value, the obtained molded article had insufficient luminance. In Comparative Example 2, since the content of the metallic pigment (C) in the resin composition exceeded the upper limit, the obtained molded product had unevenness in color tone, the smoothness was impaired, and the glare feeling was excessive. The design was impaired.
In Comparative Example 3, since the content of the swellable layered silicate (C) in the resin composition was less than the lower limit, the obtained molded product had a clear feeling and a reduced flexural modulus. In Comparative Example 4, since the content of the swellable layered silicate (C) in the resin composition exceeded the upper limit, there was an aggregate of the swellable layered silicate, and the resulting molded article had poor smoothness. The clear feeling was impaired and the weld strength was lowered.
In Comparative Examples 5 and 6, since the aminocarboxylic acid constituting the polyamide resin (A) was only 6-aminocaproic acid, the obtained molded article had low weld strength, poor weld appearance, and a flow mark. It was conspicuous and inferior in weather resistance.
In Comparative Example 7, the aminocarboxylic acid constituting the polyamide resin (A) was only 11-aminoundecanoic acid, and Comparative Example 8 was only 12-aminododecanoic acid. Clear feeling and bending elastic modulus were lowered.
In Comparative Example 9, the polyamide resin (A) is composed of one kind of aminocarboxylic acid, diamine and dicarboxylic acid, and the obtained molded product has a poor weld appearance and a noticeable flow mark. Met.

Claims (12)

  A polyamide resin composition comprising 100 parts by weight of a polyamide resin (A), 1 to 10 parts by weight of a swellable layered silicate (B), and 0.5 to 5 parts by weight of a metallic pigment (C), the polyamide resin (A ) Is composed of two or more aminocarboxylic acid units.   The polyamide resin composition according to claim 1, wherein the polyamide resin (A) is a copolymer composed of two or more aminocarboxylic acid units.   The polyamide resin (A) is a copolymer composed of a 6-aminocaproic acid unit and an 11-aminoundecanoic acid unit and / or a 12-aminododecanoic acid unit, and the 6-aminocaproic acid in the polyamide resin (A) Content of a unit is 60-90 mass%, The polyamide resin composition of Claim 2 characterized by the above-mentioned.   The polyamide resin composition according to claim 1, wherein the polyamide resin (A) is a molten mixture of two or more polymers composed of aminocarboxylic acid units.   The polyamide resin (A) is a melt mixture of polyamide 6 and polyamide 11 and / or polyamide 12, and the content of polyamide 6 in the polyamide resin (A) is 60 to 90% by mass. Item 5. The polyamide resin composition according to Item 4.   2. The polyamide resin composition according to claim 1, wherein the swellable layered silicate (B) is any one selected from fluorine mica, montmorillonite, and hectorite.   2. The polyamide resin composition according to claim 1, wherein the metallic pigment (C) is any one selected from aluminum, iron, oxides thereof, and titanium-coated mica.   Furthermore, a weathering agent (D) is contained, The polyamide resin composition of Claim 1 characterized by the above-mentioned.   The polyamide resin composition according to claim 1, further comprising lithium halide and / or nigrosine.   A method for producing a polyamide resin composition according to claim 2 or 3, comprising a polymerization reaction step of a copolymer in the presence of a swellable layered silicate (B). A method for producing the composition.   A method for producing the polyamide resin composition according to claim 4 or 5, comprising at least one polymerization reaction step of a polymer performed in the presence of the swellable layered silicate (B). A method for producing a polyamide resin composition.   The molded object formed by shape | molding the polyamide resin composition in any one of Claims 1-9.