JP2017036378A - Polyamide resin composition and molded body by molding the same - Google Patents

Abstract

[Problem] To provide a polyamide resin composition capable of obtaining a metallic-like molded article with little generation of flow marks and high luminance.
SOLUTION: Contains 100 parts by mass of polyamide resin (A), 1 to 10 parts by mass of swellable layered silicate (B), 1 to 7 parts by mass of aluminum powder (C) and 2 to 15 parts by mass of glass beads (D). The polyamide resin composition, wherein the polyamide resin (A) is polyamide 6, a mixture of polyamide 6 and polyamide 11, or a mixture of polyamide 6 and polyamide 12.
[Selection figure] None

Description

  The present invention relates to a polyamide resin composition capable of obtaining a metallic-like molded article with little generation of flow marks and high brightness.

  For interior parts of automobiles, products in which a molded body made of a thermoplastic resin is decorated in a metallic style may be used.

  In order to obtain such a product, a resin obtained by filling a thermoplastic resin such as a 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 the composition. 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.

International Publication No. 99/013006 Pamphlet

  However, the molded body obtained from the polyamide resin composition described in Patent Document 1 has a metallic appearance, but a flow mark is generated due to the orientation of particles expressing a metallic color such as aluminum powder. There was a problem that the brightness was lowered.

  An object of the present invention is to provide a polyamide resin composition that solves the above-described problems and that is capable of obtaining a metallic-like molded article with less generation of flow marks and high luminance.

In order to solve such problems, the present inventor has intensively studied, and as a result, has found that the above object can be achieved by blending glass beads, and has reached the present invention.
That is, the gist of the present invention is as follows.

(1) Polyamide resin (A) 100 parts by mass, swellable layered silicate (B) 1-10 parts by mass, aluminum powder (C) 1-7 parts by mass and glass beads (D) 2-15 parts by mass The polyamide resin composition characterized by the above-mentioned.
(2) The polyamide resin composition according to (1), wherein the polyamide resin (A) is polyamide 6, a mixture of polyamide 6 and polyamide 11, or a mixture of polyamide 6 and polyamide 12.
(3) A molded article comprising the polyamide resin composition according to (1) or (2).

  According to the polyamide resin composition of the present invention, it is possible to obtain a metallic-like molded body with less generation of flow marks and high luminance.

  The polyamide resin composition of the present invention contains a polyamide resin (A), a swellable layered silicate (B), aluminum powder (C), and glass beads (D).

  The polyamide resin (A) is not particularly limited, and examples thereof include polyamide 6, polyamide 46, polyamide 66, polyamide 11, polyamide 12, polyamide 610, polyamide 612, polyamide 116, a mixture thereof, and a copolymer thereof. Can be mentioned. Among these, polyamide 6 alone, a mixture of polyamide 6 and polyamide 11, or a mixture of polyamide 6 and polyamide 12 is preferable. The content of polyamide 6 in the polyamide resin (A) of the mixture is preferably 60 to 100% by mass, and more preferably 70 to 90% by mass. The brightness is further improved by using the mixture.

  The relative viscosity of the polyamide resin (A) is not particularly limited, but is preferably 1.5 to 3.5 under the conditions of a temperature of 25 ° C. and a concentration of 1 g / dL using 96 mass% concentrated sulfuric acid as a solvent. It is more preferably 0.7 to 3.2, and even more preferably 1.9 to 3.0. If the relative viscosity is less than 1.5, the resulting molded article of the polyamide resin composition may be inferior in rigidity. On the other hand, when the relative viscosity exceeds 3.5, the fluidity is inferior, the kneading becomes difficult, and the moldability is lowered, so that the surface glossiness may be lowered.

  The polyamide resin composition of the present invention needs to contain a swellable layered silicate (B). Luminance can be increased by containing the swellable layered silicate (B).

  Examples of the swellable layered silicate (B) include smectites such as montmorillonite, beidellite, hectorite, and saconite; vermiculites such as vermiculite; Examples include brittle mica such as wright, clintonite, and anandite, and chlorite groups such as dombasite, sudite, kukeite, clinochlore, chamonite, and nimite. In the present invention, swellable fluorine mica, montmorillonite, and hectorite are particularly preferably used. These may be used alone or in combination of two or more. The swellable layered silicate may be naturally produced or artificially synthesized or modified.

The swellable fluorine mica 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 examples thereof include sodium and lithium. A, b, X, Y, and Z represent coefficients, respectively, 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 the swellable fluorine mica, for example, silicon oxide, magnesium oxide and various fluorides are mixed, and the mixture is completely melted in a temperature range of 1400-1500 ° C. in an electric furnace or a gas furnace, and then cooled. A melting method in which swellable fluorine mica is crystal-grown in a reaction vessel during the process can be mentioned. 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 swellable fluorinated mica tends to decrease.

Montmorillonite has a structural formula represented by the following formula.
M _a Si (Al ₂ -aMg) O ₁₀ (OH) ₂ .nH ₂ O
(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.)

  Montmorillonite can be obtained by refining a naturally produced product by a water treatment or the like.

  It is known that montmorillonite has the same type of ion substitution product such as magnesia montmorillonite, iron montmorillonite, and iron magnesia montmorillonite, and these may be used.

Hectorite has a structural formula represented by the following formula, for example.
Na _0.66 (Mg _5.34 Li _0.66 ) Si ₈ O ₂₀ (OH) ₄ .nH ₂ O

  Hectorite may be obtained naturally or may be obtained by synthesis.

  Hectorite has a structure composed of a negatively charged silicate layer mainly composed of silicate and a cation having an ion exchange capacity interposed between the layers. Compared with other layered silicates, the hectorite has a hydroxyl group. Since it is contained in a large amount, water molecules can easily enter between layers (that is, hydrophilicity is high) and easily swell. In addition, the particle size is small compared to other layered silicates.

  The content of the swellable layered silicate (B) is required to be 1 to 10 parts by mass, preferably 2 to 9 parts by mass, with respect to 100 parts by mass of the polyamide resin (A). It is more preferably 8 parts by mass. Luminance improves by containing a predetermined amount of swellable layered silicate (B). When the content of the swellable layered silicate (B) is less than 1 part by mass, the luminance is lowered, which is not preferable. On the other hand, when the content exceeds 10 parts by mass, the luminance of the resulting molded article is lowered, the smoothness is lowered, and the surface glossiness is lowered.

  Content of aluminum powder (C) needs to be 1-7 mass parts with respect to 100 mass parts of polyamide resin (A), and it is preferable that it is 2-4 mass parts. When the content of the aluminum powder (C) is less than 1 part by mass, the obtained molded product is not preferable because sufficient luminance cannot be obtained. On the other hand, when it exceeds 7 mass parts, since the smoothness of the obtained molded object falls and surface glossiness falls, it is unpreferable.

  The average particle size of the aluminum powder (C) is preferably 5 to 40 μm. When the average particle diameter of the aluminum powder (C) exceeds 40 μm, the effect of reducing the flow mark may not be obtained. On the other hand, when the average particle diameter of the aluminum powder (C) is less than 5 μm, the luminance may decrease. Moreover, it is preferable that the thickness of aluminum powder (C) is 0.1-0.9 micrometer. When the thickness of the aluminum powder (C) is less than 0.1 μm, the aluminum powder may be deformed during the melt-kneading process and sufficient luminance may not be obtained. On the other hand, when the thickness of the aluminum powder (C) exceeds 0.9 μm, the aluminum powder tends to be oriented and sufficient luminance may not be obtained.

  The average particle diameter of the aluminum powder can be measured by a laser diffraction / scattering type particle size distribution measuring device, for example, Microtrack 2 (manufactured by Nikkiso Co., Ltd.). The average thickness of the aluminum powder can be calculated by a simple average of 50 aluminum powders measured by an electron microscope on the cross section of the molded product.

  The content of the glass beads (D) is required to be 2 to 15 parts by mass with respect to 100 parts by mass of the polyamide resin (A), and preferably 3 to 10 parts by mass. When the content of the glass beads (D) is less than 2 parts by mass, the resulting molded product is not preferable because a sufficient flow mark reduction effect cannot be obtained. On the other hand, when the content exceeds 15 parts by mass, This is not preferable because the luminance is lowered, the smoothness is lowered, and the surface glossiness is lowered.

  The average particle diameter of the glass beads (D) is preferably 5 to 45 μm. When the average particle diameter of the glass beads (D) exceeds 45 μm, the luminance may decrease. On the other hand, when the average particle diameter of the glass beads (D) is less than 5 μm, the effect of reducing the flow mark may not be obtained.

  As long as the effects of the present invention are not impaired, additives such as pigments, plasticizers, lubricants, mold release agents, and antistatic agents may be added to the polyamide resin composition of the present invention. The method of mixing these with the polyamide resin composition of the present invention is not particularly limited.

  Although the manufacturing method of the polyamide resin composition of this invention is not specifically limited, For example, it can obtain by performing the polymerization reaction of the monomer component which comprises a polyamide resin (A) in presence of swellable layered silicate (B). And a polyamide resin containing a swellable layered silicate, an aluminum powder (C), and glass beads (D). By producing by the above method, the swellable layered silicate (B) can be uniformly dispersed in the polyamide resin (A), and the glossiness of the obtained molded product can be further enhanced. As said monomer used for a polymerization reaction, 6-aminocarboxylic acid and (epsilon) -caprolactam are preferable.

  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 manufacture by melting and mixing a polyamide resin containing a swellable layered silicate obtained by carrying out the copolymerization reaction, aluminum powder (C), and glass beads (D).

  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. A polyamide resin containing a swellable layered silicate obtained in the presence of the swellable layered silicate (B), and another polymer (or another polymer containing a swellable layered silicate); It is preferable to produce a polyamide resin composition by melting and mixing aluminum powder (C) and glass beads (D). 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), so that 6-aminocaproic acid or ε-caprolactam Preferably there is.

  When two or more types of molten mixtures of polymers composed of aminocarboxylic acid units are used as the polyamide resin (A), they are preferably sufficiently melt-kneaded. When melt kneading is insufficient, for example, when the difference in melt viscosity between the two polyamide resins to be melt-mixed is large, or when the difference in melting point is large, a sea-island structure is exhibited without being uniformly mixed with each other. There is. In such a case, particularly in the present invention, it becomes difficult to uniformly orient the contained aluminum powder (C) when obtaining a molded product, so that the luminance is partially impaired or the luminance is uneven. Inconvenience such as doing may occur. In addition, when using the copolymer comprised from 2 or more types of aminocarboxylic acid units as a polyamide resin (A), such a concern reduces.

  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 as the lactam, 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.

  In order to remove aminocarboxylic acid (lactam) remaining in the polyamide resin after polymerization, it is preferable to scour the polyamide resin pellets with hot water. As a refinement | purification method, the method of processing for 8 hours or more in 90-100 degreeC hot water is mentioned, for example.

  When melt-mixing the polyamide resin containing the swellable layered silicate, the aluminum powder (C), and the glass beads (D), a known melt-kneading extruder can be used. As a method for supplying aluminum powder (C) and glass beads (D) to a melt-kneading extruder, a mixture of aluminum powder (C) and glass beads (D) in the swellable layered silicate-containing polyamide resin, Although it may be charged all at once from the main hopper, aluminum powder (C) and glass beads (D) are fed from the middle of the extruder in order to suppress crushing or breakage of aluminum powder (C) and glass beads (D) as much as possible. It is preferable to supply at the downstream of the extruder as much as possible.

  The swellable layered silicate-containing polyamide resin, aluminum powder (C), and glass beads (D) may not be sufficiently melt-kneaded, and are mixed within a range that does not hinder the work in the subsequent injection molding process. It only has to be done. If necessary, a dry blend of the swellable layered silicate-containing polyamide resin, aluminum powder (C), and glass beads (D), and a swellable layered silicate-containing polyamide resin and aluminum powder (C) are melt mixed. The product obtained by dry blending the glass beads (D) with the product may be directly supplied to an injection molding machine, and may be melt-kneaded in the injection molding machine for injection molding.

  Since the aluminum powder (C) is brittle with respect to external stress, it can be obtained that the screw shear stress during melt-kneading is not applied to the aluminum powder (C) as much as possible in the production of the resin composition and the molding of the molded body. It is preferable for improving the surface glossiness of the molded product.

  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 vacuum molding, pressure molding, and vacuum / pressure molding after sheet processing. Among these, the injection molding method is preferable. As an injection molding method, in addition to a general injection molding method, gas injection molding, injection press molding, or the like can 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 (melting point − of the resin composition. 20 ° C.) or less. If the molding temperature is too low, the moldability may become unstable, such as a short circuit occurring in the molded product, or the surface glossiness of the resulting molded product may be lost. On the other hand, if the molding temperature is too high, the polyamide resin composition may be decomposed, which may cause the strength of the resulting molded product to decrease or the surface glossiness to decrease.

  The molded product of the present invention, particularly a molded product 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, it influences the fluidity | liquidity in the metal mold | die of a composition, and also the dispersibility of the swellable layered silicate (B) and aluminum powder (C) in a polyamide resin composition. For example, when the injection speed is high, the orientation of the aluminum powder (C) is disturbed and the brightness tends to decrease. Therefore, the injection speed should be low to medium.

  Since the molded body of the present invention is a metallic-like molded body with less generation of flow marks and high brightness, it can be suitably used for various automobile parts, electrical and electronic parts. Examples of automotive parts include various instruments such as speedometers, tachometers, fuel gauges, water temperature gauges, and distance meters in instrument panels, car stereos, navigation systems, various switches around air conditioners, buttons, and center consoles. Examples include shift levers, side brake grips, door trims, armrests, and door levers. Examples of the electric and electronic parts include 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.

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

1. Evaluation Method (1) Preparation of Test Pieces 1 and 2 Using the obtained polyamide resin composition, with an EC-100II type injection molding machine manufactured by Toshiba Machine Co., Ltd., a resin temperature of 260 ° C., a mold temperature of 100 ° C., and a holding pressure Injection molding was performed under the conditions of 30 MPa, injection speed 100 mm / second, injection pressure 100 MPa, cooling time 10 seconds, plate-like molded body (test piece 1) 90 mm long × 50 mm wide × 2 mm thick, and 80 mm long × 60 mm wide × A plate-like molded body having a convex portion with a curvature radius of 50 mm at the center portion having a thickness of 1 mm (a plate-shaped molded body in which the plate-like portion and the convex portion are in a circular shape with a diameter of 50 mm, test piece 2) was obtained. A mold having one side gate at the center in the short side direction was used.

(2) Luminance Using a variable angle spectral color difference meter (variable angle spectral colorimetry system GSP-2 manufactured by Murakami Color Research Laboratory), an incident angle of 45 °, a light receiving angle of 40 °, a D65 / 2 light source, and a visual field L * was measured at 2 °, and L * was evaluated as luminance.
The luminance was 160 or more.

(3) Flow mark In the test piece 2, the bottom part of the convex part top part was observed and it was confirmed whether there existed the part (flow mark) from which the color tone changed with the periphery.
○: There is no portion where the color tone is changed compared to the surrounding portion.
X: There is a portion where the color tone changes compared to the peripheral portion.

(4) Surface glossiness Based on JISZ8741, the surface glossiness was measured about the test piece 1 using the Nippon Denshoku gloss meter VG7000 type gloss meter.
The glossiness was 85 or more.

2. material

(1) Polyamide resin (A)
・ Polyamide resin (A-8)
Polyamide 11, “BMN O” manufactured by Arkema
・ Polyamide resin (A-9)
Polyamide 12, "AMN O TLD" manufactured by Arkema

(2) Swellable layered silicate (B)
B-1: swellable fluorine mica, “ME-100” manufactured by Co-op Chemical Co., Ltd.
B-2: swellable montmorillonite, “Jungel HV” manufactured by Hojun Co., Ltd., average particle size 5.0 μm, cation exchange capacity 70 meq / 100 g
B-3: Swellable hectorite, “Bentone HC” manufactured by Elementis Specialties, cation exchange capacity: 80 meq / 100 g

(3) Aluminum powder (C)
・ Aluminum paste, “Silbead M200-BP” manufactured by Asahi Kasei Chemicals Corporation, average particle size 20 μm, average thickness 0.4 μm, solid content 90% by mass, polyethylene glycol 10% by mass

(4) Glass beads (D)
・ Borosilicate glass, “UBS-002E” manufactured by Unitika Ltd., particle size 0 to 20 μm, spherical

(5) Polyamide resin containing swellable layered silicate (P-1)
To 100 parts by mass of ε-caprolactam, 0.4 parts by mass of phosphorous acid, 4 parts by mass of swellable fluorinated mica (B-1), and 5 parts by mass of water were added and stirred at 80 ° C. for 1 hour, and then 260 ° C. The mixture was stirred at 0.7 MPa for 1 hour and then stirred at 260 ° C. and normal pressure for 1 hour to carry out polymerization to obtain a polyamide resin (P-1) containing a swellable layered silicate.

・ (P-2) to (P-7)
Except having compounded each component with the compounding quantity of Table 1, it performed operation similar to the time of manufacturing the polyamide resin (P-1) containing swellable layered silicate, and contained swellable layered silicate. Polyamide resins (P-2) to (P-7) were obtained.

Example 1
100 parts by mass of polyamide resin (P-1) containing swellable layered silicate, 3 parts by mass of aluminum powder (C), and 2 parts by mass of glass beads (D) are mixed together, and the main hopper of the single screw extruder Then, the mixture was melt kneaded and extruded into a strand form from a die, and then cooled and pelletized to obtain polyamide resin composition pellets. Melt kneading was performed at a resin temperature of 260 ° C., a screw rotation of 200 rpm, and a discharge rate of 30 kg / hour.

Examples 2-14, Comparative Examples 1-7
Except having changed so that it might become a combination composition of Table 2, operation similar to Example 1 was performed and the polyamide resin composition pellet was obtained.

  Table 2 shows the evaluation results of the polyamide resin compositions obtained in Examples 1 to 14 and Comparative Examples 1 to 7.

  The polyamide resin compositions of Examples 1 to 14 had high luminance and few flow marks.

Since the polyamide resin composition of Comparative Example 1 did not contain glass beads, a flow mark was generated.
Since the polyamide resin composition of Comparative Example 2 contained a small amount of glass beads, a flow mark was generated.
Since the polyamide resin composition of Comparative Example 3 contained a large amount of glass beads, the brightness and surface glossiness were low.
The polyamide resin composition of Comparative Example 4 had low luminance because the amount of the swellable layered silicate was small.
Since the polyamide resin composition of Comparative Example 5 contained a large amount of the swellable layered silicate, the luminance and surface glossiness were low.
The polyamide resin composition of Comparative Example 6 had low luminance because the blending amount of aluminum powder was small.
Since the polyamide resin composition of Comparative Example 7 contained a large amount of aluminum powder, the surface glossiness was low.

Claims (3)

It contains 100 parts by mass of polyamide resin (A), 1-10 parts by mass of swellable layered silicate (B), 1-7 parts by mass of aluminum powder (C), and 2-15 parts by mass of glass beads (D). A polyamide resin composition. The polyamide resin composition according to claim 1, wherein the polyamide resin (A) is polyamide 6, a mixture of polyamide 6 and polyamide 11, or a mixture of polyamide 6 and polyamide 12. The molded object which consists of a polyamide resin composition of Claim 1 or 2.