JP5907804B2 - Heat discoloration metallic polyamide resin composition - Google Patents

Description

  The present invention relates to a heat-discoloring metallic polyamide resin composition.

In recent years, the design process by raw material coloring, especially metallic-colored raw material colored parts, has been in increasing demand for electrical / electronic parts, machine parts, automobile parts, etc. in order to omit the painting process on the design parts due to environmental considerations. .
In particular, since the demand for parts in an automobile engine room is high as described above, and it is cheaper and more productive than a coated product, a technique related to a raw material colored part has been proposed. (For example, refer to Patent Document 1).
Furthermore, a metallic polyamide resin is disclosed in which the discoloration with time in a hot atmosphere in a polyamide resin is reduced (see, for example, Patent Documents 2 to 4).

JP-A-11-294184 JP-A-11-293106 JP-A-11-315205 Special table 2001-509524 gazette

However, the material-colored component disclosed in Patent Document 1 has a problem that color change with time occurs when it is continuously used in a high-temperature atmosphere.
In recent years, the number of parts in the engine room tends to be overcrowded, and the use environment in the engine room becomes severe, so that it is necessary to further reduce thermal discoloration at high temperatures. The polyamide resins disclosed in Nos. 4 to 4 still have a problem that their heat discoloration characteristics are insufficient with respect to market demands.

  Therefore, an object of the present invention is to provide a heat-resistant color-changing metallic tone polyamide resin composition in which discoloration with time when exposed to a high-temperature atmosphere is further effectively reduced.

As a result of intensive studies to solve the above-described problems of the prior art, by adding a predetermined amount of a phosphinic acid-based stabilizer and a metallic color pigment having a specific thickness to a polyamide resin containing a predetermined amount of a copper compound. The present invention has been found out that it exhibits excellent heat discoloration.
That is, the present invention is as follows.

[1]
(A) Polyamide resin containing 40 ppm or more of copper compound in terms of copper: 100 parts by mass;
(B) Metallic coloring pigment having an average thickness of 0.05 to 0.4 μm: 1.0 to 5.0 parts by mass;
(C) Phosphinic acid stabilizer: 0.05 to 0.18 parts by mass;
, A heat discoloration-resistant metallic polyamide resin composition.
[2]
The heat discoloration-resistant metallic amide resin composition according to [1], wherein the polyamide resin (A) is polyamide 66.
[3]
The heat-resistant color-changing metallic polyamide resin composition according to [1] or [2] , further including 5 to 25 parts by mass of (D) inorganic filler with respect to 100 parts by mass of the polyamide resin (A). .
[4]
A molded article obtained by molding the heat discoloration-resistant metallic polyamide resin composition according to any one of [1] to [3] .
[5]
The molded product according to [4] , which is a part in an automobile engine room.
[6]
A method for producing a heat discoloration-resistant metallic polyamide resin composition according to any one of [1] to [3],
5 to 10 parts by mass of polyethylene glycol is blended with 100 parts by mass of the metallic coloring pigment (B) to make the metallic coloring pigment (B) into a paste, and the paste-like metallic coloring pigment (B) and a polyamide resin ( A) and a step of kneading the phosphinic acid stabilizer (C) with an extruder ,
Method for producing a resistance to thermal discoloration metallic tone polyamide resin composition.

  ADVANTAGE OF THE INVENTION According to this invention, the metallic-tone polyamide resin composition excellent in the heat-resistant discoloration property in a high temperature atmosphere is obtained.

Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail.
In addition, this invention is not restrict | limited to the following embodiment, A various deformation | transformation can be implemented within the range of the summary.

[Heat-resistant color-changing metallic polyamide resin composition]
The heat discoloration-resistant metallic polyamide resin composition of the present embodiment (hereinafter sometimes simply referred to as a polyamide resin composition) is
(A) Polyamide resin containing 40 ppm or more of copper compound in terms of copper: 100 parts by mass;
(B) Metallic coloring pigment having an average thickness of 0.05 to 0.4 μm: 1.0 to 5.0 parts by mass;
(C) Phosphinic acid stabilizer: 0.05 to 0.18 parts by mass;
Containing.
Hereinafter, the components of the heat-resistant color-changing metallic polyamide resin composition of the present embodiment will be described.

((A) Polyamide resin)
There is no particular limitation on the polyamide resin (A) constituting the polyamide resin composition of the present embodiment (hereinafter sometimes referred to as “polyamide resin (A)” and “component (A)”), and a conventionally known polyamide is used. can do.
For example, ε-caprolactam, adipic acid, sebacic acid, dodecanedioic acid, isophthalic acid, terephthalic acid, hexamethylenediamine, tetramethylenediamine, 2-, methylpentamethylenediamine, 2,2,4-trimethylhexamethylenediamine, 2 , 4,4-trimethylhexamethylenediamine, metaxylylenediamine, homopolymers obtained by appropriately combining polyamide-forming monomers such as bis (3-methyl-4aminocyclohexyl) methane, copolymers alone, homopolymers , A mixture of copolymers, a mixture of a copolymer and a homopolymer, and the like can be used.
Although not limited to the following examples, specifically, polyamide 6, polyamide 66, polyamide 610, polyamide 612, polyamide 11, polyamide 12, polyamide MXD6, polyamide formed by polymerizing hexamethylenediamine and isophthalic acid (Polyamide 6I), homopolymers such as polyamide (polyamide PACMI) obtained by polymerizing isophthalic acid and bis (3-methyl-4aminocyclohexyl) methane, and polyamides obtained by polymerizing adipic acid, isophthalic acid and hexamethylenediamine (Polyamide 66 / 6I copolymer), polyamide (polyamide 66 / 6T copolymer) obtained by polymerizing adipic acid, terephthalic acid and hexamethylenediamine, and polymerizing adipic acid, cyclohexic acid and hexamethylenediamine. Polyamide (Polyamide) 66 / 6C copolymer), polyamide (polyamide 6I / 6T copolymer) obtained by polymerizing isophthalic acid, terephthalic acid and hexamethylenediamine, and polymerizing adipic acid, isophthalic acid, terephthalic acid and hexamethylenediamine. Polyamide (polyamide 66 / 6I / 6T copolymer), polyamide obtained by polymerizing terephthalic acid, 2,2,4-trimethylhexamethylenediamine and 2,4,4-trimethylhexamethylenediamine (polyamide TMDT copolymer) ), A copolymerized polyamide obtained by polymerizing isophthalic acid, terephthalic acid, hexamethylenediamine and bis (3-methyl-4aminocyclohexyl) methane, and isophthalic acid, terephthalic acid, hexamethylenediamine and bis (3-methyl-4) Aminocyclohexyl) methane is polymerized Mixtures comprising copolymerized polyamide and polyamide 6, a mixture of polyamide MXD6 and polyamide 66 and the like.

Among the various polyamides mentioned above, in particular, half of polyamide 66, polyamide 66 / 6C copolymer, polyamide 66 / 6C / 6I copolymer, polyamide 66 / 6T copolymer, polyamide 66 / 6T / 6I copolymer, etc. Aromatic polyamide has a high melting point and is suitable as a material for obtaining parts that require more heat resistance.
In addition, polyamide 66 / 6I copolymers, semi-aromatic polyamides such as polyamide MXD6, and mixtures of these semi-aromatic polyamides and other aliphatic polyamides have a crystallization temperature depending on their copolymerization ratio and mixing ratio. Since it can be controlled as appropriate, the mold transferability is improved by lowering the crystallization temperature, and the molded product molded using these is not easily exposed to the inorganic filler on the surface, and has excellent appearance. It becomes goods.
In addition, since a mixture of polyamide 66 and a polyamide having a long ethylene group such as polyamide 612 or polyamide 610 is excellent in hydrolysis resistance under high temperature and high humidity, it is necessary to obtain a part used in a high temperature and high humidity environment. Suitable as a material.
Among the polyamide 66 mixtures, those containing 50 mass% or more of the polyamide 66 component are more preferable, and those containing 70 mass% or more are more preferable from the viewpoints of moldability and mechanical properties at high temperatures.

The (A) polyamide resin can be polymerized by a conventionally known method.
Examples thereof include a heat melting method, a solution method using a dicarboxylic acid halide component and a diamine component, and the like.
In particular, the thermal melting method is most effective, and the polymerization form may be a batch type or a continuous type.
The polymerization apparatus is not particularly limited, and any known apparatus such as a continuous reactor, an autoclave reactor, a tumbler reactor, a kneader or other extruder reactor can be used.

A copper compound is added to the polyamide resin (A) as an antioxidant. In addition to this, an iodine compound is preferably added.
Examples of the copper compound include, but are not limited to, copper iodide, cuprous bromide, cupric bromide, cuprous chloride, copper acetate, copper propionate, copper benzoate, Examples include copper adipate, copper terephthalate, and copper isophthalate. Among these, copper iodide and copper acetate are preferable, and copper iodide is more preferable.
Examples of the iodine compound include, but are not limited to, potassium iodide, magnesium iodide, ammonium iodide, and the like. Among these, potassium iodide is preferable.
These copper compounds and iodine compounds may be used alone or in combination of two or more.

The concentration of the copper compound in the polyamide resin (A) is 40 ppm or more and 200 ppm or less, preferably 50 ppm or more and 175 ppm or less, more preferably 60 ppm or more and 150 ppm or less, in terms of heat discoloration, as the concentration converted to copper.
When copper is less than 40 ppm, the heat discoloration deteriorates, and even if copper exceeds 200 ppm, the effect of improving heat discoloration does not change.

The molar ratio of iodine and copper contained in the copper compound and iodine compound is preferably 5 <iodine / copper and 30 ≧ iodine / copper from the viewpoint of suppressing copper metal precipitation when the polyamide resin (A) is melted. . Thereby, it is possible to suppress iodine elution from the molded product after injection molding, and to further suppress the occurrence of corrosion of the injection molding machine screw.
A more preferable range is 13 ≦ iodine / copper ≦ 25, and a further preferable range is 15 ≦ iodine / copper ≦ 22.

The concentration of copper in the polyamide resin (A) can be quantified by the following method. In addition, the numerical value used in the following method is a specific example, and is not limited to the following.
First, 0.5 g of polyamide resin (A) is weighed and 20 mL of concentrated sulfuric acid is added. After wet decomposition on the heater and cooling, 5 mL of hydrogen peroxide is added and heated on the heater until the total amount becomes 2-3 mL. Concentrate.
Cool again and make up to 500 mL with pure water.
Using an IRIS / IP manufactured by Thermo Jarrel Ash as a measuring device, the wavelength is quantified by high frequency inductively coupled plasma (ICP) emission analysis.
Specifically, a sample is spray-introduced into an Argo plasma obtained by fusion coupled plasma (ICP) emission analysis method or high frequency inductive coupling method, and emission spectrum (atomic emission spectrum) of atoms excited by high-temperature thermal energy It can be quantified by measuring the wavelength and intensity and performing element identification and quantitative analysis.
For the determination of iodine, a sample is precisely weighed, placed in an absorption liquid, for example, a nitrite solution, and then combusted and decomposed in an oxygen-rich flask. Further, the absorption liquid is bathed, and ICS-2000 manufactured by Dionex is used. , Column: IonPacAG18AS18, detector: quantified by ion chromatography using an electric conductivity detector.

The moisture in the polyamide resin (A) is not particularly limited, but the pellet moisture content is preferably 0.1% by mass or more in order to suppress an increase in the molecular weight when the compound raw material is melted with polyamide. In order to suppress decomposition, the pellet moisture content is preferably 0.5% by mass or less.
The pellet moisture content can be determined according to JIS K7251 using a Karl Fischer moisture meter.

((B) metallic coloring pigment)
The polyamide resin composition of this embodiment may be described as (B) metallic color pigment (hereinafter referred to as metallic color pigment (B), (B) component) having an average thickness of 0.05 to 0.4 μm. ) In an amount of 1.0 to 5.0 parts by mass with respect to 100 parts by mass of the polyamide resin (A).
Although it does not restrict | limit especially as a material of a metallic coloring pigment (B), For example, aluminum, coloring aluminum, a pearl pigment, a color graphite, a color glass flake, steel, silver, tin, nickel etc. are mentioned, Especially, Aluminum is preferred.

The metallic color pigment (B) has an average thickness of 0.05 to 0.4 μm from the viewpoint of availability, cost, and heat discoloration.
When the thickness is less than 0.05 μm, it is difficult to obtain and expensive, and when it exceeds 0.4 μm, the heat discoloration of the polyamide resin composition deteriorates.
This is because the metallic coloring pigment (B) also has an effect of concealing the thermal discoloration of the resin, but if the thickness of the metallic coloring pigment (B) becomes too large, the metallic coloring present on the surface portion of the molded product. This is because the number of pigments (B) is reduced, thereby reducing the concealing effect of the metallic color pigment (B), and the thermal discoloration on appearance tends to deteriorate.
0.05-0.4 micrometer is preferable and, as for the average thickness of a metallic coloring pigment (B), 0.08-0.35m is more preferable.

Further, the average thickness (t) of the metallic coloring pigment (B) can be calculated by the following formula using the water surface diffusion area per gram: WCA (m ² / g).
t = 0.4 / WCA
In addition, the water surface diffusion area is a certain pretreatment, specifically, 1 to 2 ml of 5% by weight of mineral spirit solution of stearic acid is added to 1 g of the metallic coloring pigment, and after preliminary dispersion, 50 ml of petroleum benzine is added and mixed. After heating at 45 ° C. for 2 hours, the solution is suction filtered through a filter and powdered, and then obtained according to JIS-K-5906-1991.

Moreover, the preferable shape of a metallic coloring pigment (B) is a coin shape with an average particle diameter of 5-20 micrometers from a viewpoint of the metallic feeling of the polyamide resin composition of this embodiment, and a high-class appearance.
When the average particle size is less than 5 μm, the metallic feeling disappears, and when it exceeds 20 μm, it becomes lame and loses a high-class feeling.
The average particle diameter of the metallic color pigment (B) can be measured using a Laser Micron Sizer LMS-24 manufactured by Seishin Enterprise Co., Ltd.

  The content of the metallic coloring pigment (B) in the polyamide resin composition of the present embodiment is 1.0 part by mass or more with respect to 100 parts by mass of the polyamide resin (A) from the viewpoint of the brightness of the molded product, From the viewpoint, it is 5.0 parts by mass or less. Preferably they are 1.5 mass parts or more and 4.0 mass parts or less, More preferably, they are 1.5 mass parts or more and 3.0 mass parts or less.

The metallic color pigment (B) preferably has an average surface roughness Ra of 20 nm or less.
The average surface roughness of the metallic color pigment (B) can be measured by the following method.
As an apparatus for observing the surface form of the metallic color pigment (B), an atomic force microscope, manufactured by Topometrix, TMX-2010 can be used.
First, as a pretreatment, the metallic color pigment (B) of the sample for measurement is ultrasonically washed with an excess of methanol or chloroform, then vacuum-dried, dispersed again in acetone, dropped onto a Si wafer, and naturally dried. Do.
Next, measurement is performed with the atomic force microscope. At this time, the surface roughness is quantified by selecting a metallic colored pigment (B) that does not overlap with another metallic colored pigment (B), and measuring 5 μm square. The surface roughness curve is measured by 300 scans per field of view, and the calculated average roughness of the roughness curve (arithmetic average of the altitude values within the reference length of 5 μm) is obtained.
Usually, the reference length used for the measurement depends on the average particle diameter, but it is preferable to select 5 μm for the metallic color pigment (B) contained in the polyamide resin composition of the present embodiment.
The average surface roughness Ra of the metallic coloring pigment (B) is preferably 20 nm or less, more preferably 15 nm or less.
When the average roughness Ra of the metallic color pigment (B) is 20 nm or less, the regular reflectance on the surface of the molded product molded using the polyamide resin composition of the present embodiment, that is, the surface glossiness is increased, which is extremely excellent. Brightness and metallic feel.

Aluminum, which is a suitable material for the metallic coloring pigment (B), has been designated as a dangerous substance class 2 metal powder A by the Fire Service Act. Dry aluminum is particularly dangerous because it may cause a dust explosion, but it must be wetted by liquid. This produces the effect of greatly reducing the risk of this dust explosion. Examples of the liquid to be used include mineral spirit, toluene, xylene and the like, and mineral spirit is generally selected.
When a polyamide resin composition is prepared using an aluminum paste in which aluminum is wet, mineral spirits remain in the polyamide resin composition, and a molding defect called silver streak tends to occur during injection molding. In order to eliminate this appearance defect phenomenon, it is preferable to keep aluminum in a wet state by using polyethylene glycol instead of mineral spirit as a pre-stage for mixing with the polyamide resin composition.
When aluminum is wetted using polyethylene glycol to obtain an aluminum paste, 5 to 10 parts by mass of polyethylene glycol is preferably used with respect to 100 parts by mass of aluminum.

((C) Phosphinic acid stabilizer)
The polyamide resin composition of the present embodiment comprises (C) a phosphinic acid stabilizer (hereinafter sometimes referred to as a phosphinic acid stabilizer (C), a stabilizer, and a component (C)) as the polyamide resin. (A) It contains 0.05-0.18 mass part with respect to 100 mass parts.
As the phosphinic acid stabilizer (C), an organic phosphorus-containing stabilizer having a valence state of phosphorus of +1 is preferable.
Examples of the compound of the organic phosphorus-containing stabilizer (oxidation state + 1) include hypophosphite. Although not limited to the following examples, specific examples include sodium hypophosphite, calcium hypophosphite, magnesium hypophosphite, hypophosphite diol ester, melamine hypophosphite, etc. Sodium phosphate is preferred. These phosphinic acid-based stabilizers may be used alone or in combination of two or more.
The addition amount of the phosphinic acid stabilizer (C) is 0.05 parts by mass or more and 0.18 parts by mass or less with respect to 100 parts by mass of the polyamide resin (A) from the viewpoint of the effect of suppressing thermochromic properties.
A preferable addition amount is 0.07 to 0.175 parts by mass, and more preferably 0.075 to 0.16 parts by mass.
The phosphinic acid stabilizer (C) has an effect of suppressing thermal discoloration of the thermoplastic resin, but also exhibits a reaction of metallizing copper of the copper compound which is an antioxidant. May be damaged.

In the polyamide resin composition of the present embodiment, it is preferable to previously knead the phosphinic acid stabilizer (C) in the polyamide resin composition in order to obtain stable heat discoloration. When the phosphinic acid stabilizer (C) is added by external moisture, the phosphinic acid stabilizer (C) is classified in the hopper at the time of transfer by a pellet bag as a pellet of the polyamide resin composition or during injection molding. In some cases, there is a difference in thermochromic properties between the early stage and the later stage of injection molding.
From the above viewpoint, in the production process of the polyamide resin composition, the polyamide resin (A), the aluminum paste (B) substituted with polyethylene glycol, the phosphinic acid stabilizer (C) by a single-screw or twin-screw extruder. It is preferable to prepare a colored masterbatch, and a method of adding a phosphinic acid stabilizer (C) during polymerization of the polyamide resin can also be selected.

((D) inorganic filler)
The polyamide resin composition of this embodiment may be described as (D) inorganic filler (hereinafter referred to as inorganic filler (D), (D) component) with respect to 100 parts by mass of the polyamide resin (A). It is preferable that 5-25 mass parts is further contained.
There is no restriction | limiting in particular in an inorganic filler (D), The thing currently used for the normal reinforced thermoplastic resin can be used.
The inorganic filler (D) is not particularly limited. For example, in addition to fibrous fillers such as glass fiber, carbon fiber, and metal fiber, talc, kaolin, mica, wollastonite, alumina silicate, alumina, oxidation Non-fibrous fillers such as titanium, silicon oxide, iron oxide, magnesium oxide, flaky glass glass beads, and boron nitride can be used.
These may be used alone or in combination of two or more.
Among these, preferable fillers are glass fiber, talc, wollastonite, kaolin and mica, and talc is particularly preferable.

It is preferable that a coupling agent, a sizing agent, or the like is appropriately attached to the surface of the glass fiber.
The coupling agent is not limited to the following examples, and examples thereof include amino-based, epoxy-based, chloro-based, cationic silane coupling agents, aminosilane-based coupling agents, and the like.
Examples of the sizing agent include, but are not limited to, the following examples: maleic anhydride-based, urethane-based, acrylic-based, and sizing agents containing copolymers or mixtures thereof.

The talc is represented by a chemical formula of 4SiO ₂ .3MgO.H ₂ O and is called hydrous magnesium silicate. Usually, talc ore is pulverized by a conventionally known method to obtain a particle size of about 0.1 to 20 μm, and a more preferable talc particle size is 0.5 to 5 μm.
The kaolin has a chemical composition of Al ₂ Si ₂ O ₅ (OH) ₄ , and there are kaolinite, dickite, nacrite, and halloysite which are different in the stacking method of the two-octahedral type 1: 1 layer, but any of them can be used. . Usually, the kaolin blended with the polyamide resin (A) is preferable from the viewpoint of reducing the volatile components in the molded product of the polyamide resin composition and improving the stability during processing of the molded product. The particle diameter of kaolin is usually suitably about 0.1 to 3 μm. Moreover, the higher the whiteness, the less the influence on the color tone of the molded product, which is preferable.

The wollastonite has a chemical name of calcium metasilicate and is a mineral of white needle crystals. Usually, it contains 40 to 60% by mass of SiO ₂ and 40 to 55% by mass of CaO, and other components such as Fe ₂ O ₃ , Al ₂ O ₃ , MgO, Na ₂ O and K ₂ O. is there.
Wollastonite having an oil absorption of 20 to 50 cc / 100 g, a bulk specific gravity of 0.1 to 1.0, a fiber length of 0.1 to 1000 μm, and an average particle diameter of 0.1 to 50 μm is preferably used. it can.
The average particle size referred to here is a laser diffraction / scattering type particle size distribution device or the like for which wollastonite is stirred and dispersed in pure water that has been further irradiated with ultrasonic waves to have a transmittance of 85%. The particle diameter corresponding to 50% of the cumulative particle size distribution in the method derived using
The wollastonite may be a naturally occurring one, pulverized or classified in some cases, or a synthetic product.
In addition, from the viewpoint of the Hunter whiteness being 60 or more and not deteriorating the weather resistance to the polyamide resin (A), the pH value of the slurry when mixed with high purity water to make a 10% by mass slurry is 6-8. Can be preferably used.

The mica is not particularly limited, although the crystal structure and chemical composition differ depending on the production area and synthesis method.
In the polyamide resin composition of the present embodiment, the main component of mica used as the component (D) is SiO ₂ , and the crystal structure is such that the SiO ₄ tetrahedron is connected to a hexagonal mesh plate, and this plate is composed of two sheets. A set is preferred. Further, it is preferable that ions having octahedral positions (for example, Al ³⁺ , Mg ²⁺ ) are ionically bonded between the plates. This is called a tablet, which is stacked in layers, and ions of alkali metal or alkaline earth metal (for example, K ⁺ , Li ⁺ , Na ⁺ ) are ion-bonded between the tablets.
Mica includes muscovite, phlogopite, biotite, and artificial mica. Any of these may be used, but muscovite and artificial mica that are closer to white are preferably used.
Mica is pulverized into flakes using the weak ionic bond between tablets. Since the rigidity of a molded object can be improved, so that the ratio with respect to the width | variety of this thickness is high, it can use preferably. In general, mica having a particle diameter of about 1 to 30 μm is preferably used because it has a good balance between appearance and rigidity.

The blending ratio of the inorganic filler (D) in the polyamide resin composition of the present embodiment is preferably 5 to 25 parts by mass of the inorganic filler (D) with respect to 100 parts by mass of the polyamide resin (A).
In order to obtain sufficient mechanical properties, the inorganic filler (D) is preferably 5 parts by mass or more, and in order to obtain a good metallic feeling of the molded product, the inorganic filler (D) is 25 parts by mass. The following is preferable. More preferably, it is 7-25 mass parts.

(Other materials)
The polyamide resin composition of the present embodiment includes an antioxidant, an ultraviolet absorber, a heat stabilizer, a photodegradation inhibitor, and a plasticizer that are added to a normal thermoplastic resin within a range that does not impair the object of the present invention. Further, a lubricant, a release agent, a nucleating agent, a flame retardant, a coloring dye / pigment and the like can be added.
Further, other thermoplastic resins may be blended. It should be noted that phenolic antioxidants are preferably not used because they may deteriorate the heat discoloration.
These additives may be added during the polymerization of the polyamide resin (A), or may be melt-kneaded when a polyamide resin composition is produced by uniaxial or biaxial extrusion. Further, when the polyamide resin composition is molded, it may be melt kneaded in an injection molding machine cylinder by master batch blending.

[Production method of polyamide resin composition]
As a manufacturing method of the polyamide resin composition of the present embodiment, for example, the components (A) to (C) described above, the component (D) and other materials as necessary, a single screw or twin screw extruder, etc. The method of melt-kneading using the well-known apparatus of this, and processing to a pellet form is mentioned.
In addition, in the production process of the polyamide resin composition, the components may be mixed together, and coloring using a polyamide resin (A), a metallic color pigment (B), a phosphinic acid stabilizer (C), and the like. A master batch may be obtained and melt kneaded in an injection molding machine cylinder by master batch blending.
Further, 5 to 10 parts by mass of polyethylene glycol is blended with 100 parts by mass of the metallic color pigment (B) to make the metal color pigment (B) into a paste, and the paste-like metal color pigment (B) and polyamide A method for producing a polyamide resin composition by melt-kneading a resin (A) and a phosphinic acid-based stabilizer (C) with an extruder is based on the ignition when a metallic color pigment is made into a paste with an organic solvent such as mineral spirit. In addition to reducing the risk of explosion, it is preferable from the viewpoint of obtaining a polyamide resin composition capable of preventing appearance defects due to thermal history during injection molding.

[Molded product of polyamide resin composition]
A predetermined molded product is obtained by molding the polyamide resin composition of the present embodiment by a normal molding method.
Examples of the molding method include injection molding, compression molding, blow molding, extrusion molding, and the like. Among these, the injection molding method is preferable.
In addition, special molding methods such as gas-assisted injection molding method or melted piece method can be selected, and multiple molded products can be obtained by secondary processing such as vibration welding, ultrasonic welding, laser welding, hot plate welding, etc. .
The polyamide resin composition of the present embodiment has a high designability and an advanced heat discoloration under a high temperature atmosphere, and is particularly suitable for use in an automobile engine room. Specific examples include an engine cover, an oil cap, a cylinder head cover, a timing belt cover, a wheel cap, and the like, and can also be suitably used for motorcycle parts, electric tool housings, and the like.

  Hereinafter, the present invention will be described in detail with reference to specific examples and comparative examples, but the present invention is not limited to the following examples.

The raw materials and evaluation methods used in Examples and Comparative Examples are shown below.
<Raw materials>
((A) Polyamide resin)
A-1: Polyamide 66 (Leona 1402S011 manufactured by Asahi Kasei Chemicals Corporation)
A-2: Polyamide 66 (Leona 1300S321 manufactured by Asahi Kasei Chemicals Corporation)
A-3: Polyamide 66/6 (Leona 94N05B0003 manufactured by Asahi Kasei Chemicals Corporation)

((B) metallic coloring pigment)
A ball mill having an inner diameter of 10 cm and a length of 30 cm was filled with a composition comprising 50 g of atomized aluminum powder, 1 L of mineral spirit and 10 g of oleic acid, and 2 kg of zirconia spheres having a diameter of 2 mm. The ball mill was kept at a grinding temperature of 30 ° C., and grinding was performed at a rotational speed of 72 rpm.
Under the above conditions, the average diameter of the atomized aluminum powder and the grinding time are adjusted to obtain a metallic coloring pigment, and the metallic coloring pigment is subjected to a predetermined treatment, and the following (B-1) to (B-6) ) Was obtained.
B-1: Coin-like aluminum pigment; mineral paste was separated with an aluminum paste having an average particle diameter of 7 μm, an average thickness of 0.12 μm, and an average roughness of 19 nm using a centrifuge, and then ADEKA PEG400 (polyethylene glycol) manufactured by ADEK A Co., Ltd. The aluminum remaining in step) was put into a wet state. At this time, 10 parts by mass of polyethylene glycol was used for 100 parts by mass of aluminum.
B-2: Coin-like aluminum pigment; after separating mineral spirits from an aluminum paste having an average particle diameter of 14 μm and an average thickness of 0.27 μm and an average roughness of 19 nm using a centrifuge, it was added to ADEKA PEG400 (polyethylene glycol) manufactured by ADEKA Corporation. The remaining aluminum was wetted. At this time, polyethylene glycol was used in an amount of 10 parts by mass of polyethylene glycol with respect to 100 parts by mass of aluminum.
B-3: Coin-like aluminum pigment; an aluminum paste having an average particle diameter of 19 μm, an average thickness of 0.36 μm and an average roughness of 19 nm was used. In addition, without using a centrifuge, 10 parts by mass of the mineral spirit was added to 100 parts by mass of aluminum.
B-4: Coin-like aluminum pigment; mineral paste was separated from an aluminum paste having an average particle diameter of 8 μm and an average thickness of 0.08 μm and an average roughness of 19 nm using a centrifuge, and then ADEKA PEG400 (polyethylene glycol) manufactured by ADEKA Corporation The aluminum remaining in was moistened. At this time, 10 parts by mass of polyethylene glycol was used for 100 parts by mass of aluminum.
B-5: Flaked aluminum pigment; mineral paste was separated from aluminum paste having an average particle diameter of 19 μm and an average thickness of 0.20 μm and an average roughness of 30 nm using a centrifuge, and then ADEKA PEG400 (polyethylene glycol) manufactured by ADEK A Co., Ltd. The aluminum remaining in was wet. At this time, 10 parts by mass of polyethylene glycol was used for 100 parts by mass of aluminum.
B-6: Coin-like aluminum pigment; after separating mineral spirits from an aluminum paste having an average particle diameter of 20 μm and an average thickness of 0.44 μm and an average roughness of 19 nm using a centrifuge, it was added to ADEKA PEG400 (polyethylene glycol) manufactured by ADEKA Corporation. The remaining aluminum was wetted. At this time, polyethylene glycol was used in an amount of 10 parts by mass of polyethylene glycol with respect to 100 parts by mass of aluminum.

((C) Phosphinic acid stabilizer)
C-1: Sodium hypophosphite (NaP Taihei Chemical Industrial Co., Ltd.)

((D) inorganic filler)
D-1: Chopped glass fiber (GF) (T275H manufactured by Nippon Electric Glass Co., Ltd.)
D-2: Talc (FMP Talc Co., Ltd. LMP-100)

((E) Organic heat stabilizer)
E-1: Phenol-based antioxidant (SUMILIZER GA-80 manufactured by Sumitomo Chemical Co., Ltd.)
E-2: Hindered phenol antioxidant (IRGANOX 1098 manufactured by BASF)
E-3: Phosphite anti-coloring agent (HCA manufactured by Sanko Co., Ltd.)
E-4: Phosphite antioxidant (Azukastab PEP36 manufactured by ADEKA Corporation)

<Evaluation method>
((1) Heat discoloration test)
Using polyamide resin composition pellets of Examples and Comparative Examples described later, SE50D injection molding machine manufactured by Sumitomo Heavy Industries, Ltd., the cylinder temperature is 280 ° C., and the injection pressure and speed are set so that the filling time is about 0.7 seconds. After appropriately adjusting and applying injection holding pressure at 40 MPa for 12 seconds, a flat plate having a length of 90 mm, a width of 60 mm, and a thickness of 2 mm (gate size 10 mm × 2 mm) was obtained after a cooling time of 14 seconds. The mold temperature was set to 80 ° C.
This molded product was exposed to 400Hr and 800Hr in a 150 ° C. (damper opening degree 25%) atmosphere in a PHH-102 perfect oven manufactured by Espec Co., Ltd.
In the test pieces before and after the heat treatment, the color difference ΔE was measured by a color meter manufactured by Minolta Co., Ltd., CM-200.
2 (spectral colorimeter) CM-S9W (software). It shows that it is excellent in the heat-resistant discoloration property in a high-heat atmosphere, so that the value of this color difference (DELTA) E is small.

((2) Metallic feeling)
The molded product obtained in (1) above was visually determined.
The evaluation criteria are as follows.
A: Metallic feeling with very good brightness.
○: Good metallic feeling, but slightly inferior in luminance.
Moreover, it evaluated using the Kansai Paint Co., Ltd. product laser type metallic feeling measuring apparatus Alcope LMR-200.
The laser-type metallic sensation measuring apparatus has a configuration including a laser light source disposed at an incident angle of 45 degrees and a light receiver at light receiving angles of 0 degrees and -35 degrees. The measured value is a light receiving angle of −35 degrees at which the maximum light intensity is obtained except for the light in the specular reflection area reflected from the surface of the measurement surface, and is proportional to the intensity of the regular reflection light from the surface of the measurement surface. The IV value as a parameter was determined. It is assumed that the IV value is a parameter representing the magnitude of luminance, and a larger value is better.
Further, the F / F value was obtained by making the degree of change in reflected light intensity non-dimensional with the average reflection intensity when the observation angle (light receiving angle) was changed.
The F / F value is a parameter representing the magnitude of the flop property of the metallic color pigment (B), and a larger numerical value indicates a better metallic feeling.

((3) Surface gloss)
Using a handy gloss meter gloss checker IG-320 manufactured by HORIBA, Ltd., Gs60 ° of the molded product obtained in the above (1) was measured.
Gs60 ° is an amount representing the degree of reflection when light is applied to the surface, and is a value determined by the ratio of the intensity of reflected light at the measurement portion and the intensity of reflected light from the gloss reference plate. .
As a reference value, the glossiness of the glass plate surface with a refractive index of 1.567 is set to 100 as a reference.
The Gs 60 ° indicates the degree of reflection as a relative value when measured by tilting the light source and the light receiver by 60 ° with respect to the surface of the measurement portion being 0 °.
The one where the numerical value was large evaluated that the external appearance of a molded article was favorable.

((4) Bending characteristics)
An ISO178 test piece was obtained by the same method as in (1) above, and the maximum bending strength and bending elastic modulus were measured in an atmosphere of 120 ° according to ISO178.
It was evaluated that a higher value was preferable.

((5) Molded product shrinkage)
A test piece was obtained by the same method as in (1) above, and allowed to stand at 23 ° C. and 50% relative humidity for 24 hours. .Measured with an accuracy of 1 mm and compared with the mold standard dimension at the mold temperature at the time of molding measured in advance by the same method, and the difference between the dimension of the test piece and the mold standard dimension is the mold standard dimension. The value obtained by dividing the value by 100 minutes was defined as the molding shrinkage.
It was evaluated that a lower value of the molding shrinkage rate was more suitable.

((6) Retention Silver Strip Evaluation)
One of the appearance defect phenomena in the molded product after the fifth shot from the start of the molding operation when the cooling time is 14 seconds and when it is extended to 40 seconds in the molding method (1). The presence or absence of silvery streak was observed. It was evaluated that the absence of this silver strip was excellent in retention stability.

[Example 1]
The polyamide 66 of A-1 and the polyamide 66 of A-2 were blended to obtain a polyamide resin mixture.
The content of the copper compound in the polyamide resin mixture was adjusted to 40 ppm in terms of copper.
To 100 parts by mass of this polyamide resin mixture, 2.2 parts by mass of the B-1 coin-shaped aluminum pigment and 0.1 parts by mass of C-1 sodium hypophosphite were added. Using a twin-screw extruder TEM35 manufactured by Toshiba Machine Co., Ltd., the polyamide resin composition was melt-kneaded at 285 ° C. at a barrel temperature of 285 ° C. and a screw rotation speed of 300 rpm to obtain metallic-like polyamide resin pellets.
Evaluation was performed by the above-described method using the obtained pellets.

[Example 2]
The amount of C-1 sodium hypophosphite added was 0.05 parts by mass.
Other conditions were the same as in Example 1 to obtain a metallic polyamide resin composition pellet.

Example 3
The amount of C-1 sodium hypophosphite added was 0.075 parts by mass.
Other conditions were the same as in Example 1 to obtain a metallic polyamide resin composition pellet.

Example 4
The amount of C-1 sodium hypophosphite added was 0.15 parts by mass.
Other conditions were the same as in Example 1 to obtain a metallic polyamide resin composition pellet.

Example 5
The amount of C-1 sodium hypophosphite added was 0.175 parts by mass.
Other conditions were the same as in Example 1 to obtain a metallic polyamide resin composition pellet.

Example 6
The polyamide 66 of A-1 and the polyamide 66 of A-2 were blended to obtain a polyamide resin mixture.
The content of the copper compound in the polyamide resin mixture was adjusted to 50 ppm in terms of copper.
Other conditions were the same as in Example 1 to obtain a metallic polyamide resin composition pellet.

Example 7
The addition amount of the coin-like aluminum pigment of B-1 was 1.7 parts by mass.
Other conditions were the same as in Example 6 to obtain a metallic polyamide resin composition pellet.

Example 8
The polyamide 66 of A-1 and the polyamide 66 of A-2 were blended to obtain a polyamide resin mixture.
The content of the copper compound in the polyamide resin mixture was adjusted to 60 ppm in terms of copper.
Other conditions were the same as in Example 1 to obtain a metallic polyamide resin composition pellet.

Example 9
B-4 was used as a metallic coloring pigment.
Other conditions were the same as in Example 8, and a metallic polyamide resin composition pellet was obtained.

Example 10
B-2 was used as a metallic coloring pigment.
Other conditions were the same as in Example 8, and a metallic polyamide resin composition pellet was obtained.

Example 11
B-3 was used as a metallic coloring pigment.
Other conditions were the same as in Example 8, and a metallic polyamide resin composition pellet was obtained.

[Example 12] B-5 was used as a metallic coloring pigment.
Other conditions were the same as in Example 8, and a metallic polyamide resin composition pellet was obtained.

Example 13
As an inorganic filler (D), 7 parts by mass of D-1 chopped glass fiber (GF) was added to 100 parts by mass of the polyamide resin (A).
Other conditions were the same as in Example 8, and a metallic polyamide resin composition pellet was obtained.

Example 14
As an inorganic filler (D), 8 parts by mass of D-2 talc was added to 100 parts by mass of the polyamide resin (A).
Other conditions were the same as in Example 8, and a metallic polyamide resin composition pellet was obtained.

Example 15
A-1 polyamide 66 and A-3 polyamide 66/6 were blended to obtain a polyamide resin mixture.
The content of the copper compound in the polyamide resin mixture was adjusted to 50 ppm in terms of copper.
Other conditions were the same as in Example 6 to obtain a metallic polyamide resin composition pellet.

[Comparative Example 1]
The polyamide 66 of A-1 and the polyamide 66 of A-2 were blended to obtain a polyamide resin mixture.
The content of the copper compound in the polyamide resin mixture was adjusted to 20 ppm in terms of copper.
Other conditions were the same as in Example 1 to obtain a metallic polyamide resin composition pellet.

[Comparative Example 2]
C-1 sodium hypophosphite (NaP) was not added.
Other conditions were the same as in Example 1 to obtain a metallic polyamide resin composition pellet.

[Comparative Example 3]
The amount of C-1 sodium hypophosphite (NaP) added was 0.03 parts by mass.
Other conditions were the same as in Example 1 to obtain a metallic polyamide resin composition pellet.

[Comparative Example 4]
The amount of C-1 sodium hypophosphite (NaP) added was 0.2 parts by mass.
Other conditions were the same as in Example 1 to obtain a metallic polyamide resin composition pellet.

[Comparative Example 5]
The addition amount of the coin-like aluminum pigment of B-1 was 0.5 part by mass.
Other conditions were the same as in Example 6 to obtain a metallic polyamide resin composition pellet.

[Comparative Example 6]
The metallic coloring pigment to be added was a coin-like aluminum pigment (B-6) having an average thickness of 0.44 μm.
Other conditions were the same as in Example 8, and a metallic polyamide resin composition pellet was obtained.

[Comparative Example 7]
C-1 sodium hypophosphite (NaP) was not added.
It replaced with this and 0.1 mass part of E-1 phenolic antioxidant was added with respect to 100 mass parts of polyamide resins (A).
Other conditions were the same as in Example 11, and metallic polyamide resin composition pellets were obtained.

[Comparative Example 8]
C-1 sodium hypophosphite (NaP) was not added.
Instead of this, 0.1 part by mass of E-2 hindered phenol antioxidant was added to 100 parts by mass of the polyamide resin (A).
Other conditions were the same as in Example 11, and metallic polyamide resin composition pellets were obtained.

[Comparative Example 9]
C-1 sodium hypophosphite (NaP) was not added.
Instead of this, 0.1 part by mass of an E-3 phosphite-based anti-coloring agent was added to 100 parts by mass of the polyamide resin (A).
Other conditions were the same as in Example 11, and metallic polyamide resin composition pellets were obtained.

[Comparative Example 10]
C-1 sodium hypophosphite (NaP) was not added.
Instead of this, 0.1 part by mass of E-4 phosphite antioxidant was added to 100 parts by mass of the polyamide resin (A).
Other conditions were the same as in Example 11, and metallic polyamide resin composition pellets were obtained.

  In Examples 1 to 15, a metallic polyamide resin composition excellent in heat discoloration under a high temperature atmosphere was obtained.

  The polyamide resin composition of the present invention is industrially used as a part in an automobile engine room, a motorcycle part, a power tool housing, and the like, which require high designability and high heat discoloration under a high temperature atmosphere. It has sex.

Claims (6)

(A) Polyamide resin containing 40 ppm or more of copper compound in terms of copper: 100 parts by mass;
(B) Metallic coloring pigment having an average thickness of 0.05 to 0.4 μm: 1.0 to 5.0 parts by mass;
(C) Phosphinic acid stabilizer: 0.05 to 0.18 parts by mass;
, A heat discoloration-resistant metallic polyamide resin composition. The heat discoloration-resistant metallic amide resin composition according to claim 1, wherein the polyamide resin (A) is polyamide 66. The heat-resistant color-changeable metallic polyamide resin composition according to claim 1 or 2 , further comprising 5 to 25 parts by mass of an inorganic filler (D) with respect to 100 parts by mass of the polyamide resin (A). The molded article which shape | molded the heat-resistant discoloration property metallic-tone polyamide resin composition as described in any one of Claims 1 thru | or 3 . The molded article according to claim 4 , which is a part in an automobile engine room. A method for producing a heat-resistant color-changing metallic polyamide resin composition according to any one of claims 1 to 3,
5 to 10 parts by mass of polyethylene glycol is blended with 100 parts by mass of the metallic coloring pigment (B) to make the metallic coloring pigment (B) into a paste, and the paste-like metallic coloring pigment (B) and a polyamide resin ( A) and a step of kneading the phosphinic acid stabilizer (C) with an extruder ,
Method for producing a resistance to thermal discoloration metallic tone polyamide resin composition.