JP2017210591A - Polyamide resin composition, molded article, and method for producing polyamide resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyamide resin composition capable of providing a molded article having high mechanical strength and excellent appearance, a molded article using the polyamide resin composition, and a method for producing a polyamide resin composition.SOLUTION: The polyamide resin composition contains: 100 pts.mass of a polyamide resin having a half-crystallization time (ST(P)) of 20-500 seconds; 5-60 pts.mass of carbon fibers having a number-average fiber length of 3-10 mm; and inorganic fibers having a number-average fiber length of 50-200 μm and selected from carbon fibers and glass fibers. The inorganic fibers having a number-average fiber length of 50-200 μm are contained in an amount of 40-850 pts.mass based on 100 pts.mass of the carbon fibers having a number-average fiber length of 3-10 mm.SELECTED DRAWING: None

Description

  The present invention relates to a polyamide resin composition, a molded article, and a method for producing a polyamide resin composition.

  Conventionally, it has been studied to increase the strength of a molded article composed of polyamide resin by blending carbon fiber with polyamide resin. For example, Patent Document 1 discloses a composition containing a polyamide resin (A), a glass fiber (B), a PAN-based carbon fiber (C) and a conductive carbon (D), and the polyamide resin (A) A polyamide resin containing 60% by mass or more of a polyamide MX resin synthesized from xylylenediamine and an α, ω-linear aliphatic dibasic acid, with respect to the total amount of (A) to (D), (A) Is 30 to 83% by mass, (B + C) is 15 to 65% by mass, (C) is 5 to 35% by mass, (D) is 2 to 20% by mass, ( A polyamide resin composition having a C + D) content of 7 to 55% by mass, a tensile strength of 150 MPa or more, and a tensile modulus of 15 GPa or more is disclosed.

JP 2011-132550 A

  However, it has been found that the polyamide resin molded product blended with carbon fiber may be inferior in appearance. On the other hand, if the amount of carbon fiber is reduced in order to improve the appearance, the mechanical strength is inferior. The present invention aims to solve the above-mentioned problems, and is a polyamide resin molded product blended with carbon fiber, which has a high mechanical strength and can provide a molded product with an excellent appearance. It is an object of the present invention to provide a composition, a molded article using the polyamide resin composition, and a method for producing the polyamide resin composition.

Based on the above problems, the present inventors have intensively studied. As a result, the polyamide resin is blended with carbon fibers having a number average fiber length of 3 to 10 mm, and the number average fiber length is 50 to 200 μm. It discovered that the said subject could be solved by mix | blending the inorganic fiber selected from carbon fiber and glass fiber, and making these compounding quantities into a predetermined range. Specifically, the above problem has been solved by the following means <1>, preferably <2> to <9>.
<1> 100 parts by mass of a polyamide resin having a semi-crystallization time (ST (P)) of 20 to 500 seconds, 5 to 60 parts by mass of carbon fibers having a number average fiber length of 3 to 10 mm, and a number average fiber length Is an inorganic fiber selected from carbon fibers and glass fibers, and the number average fiber length is 50 to 200 μm, the number average fiber length is 3 to 10 mm. A polyamide resin composition containing 40 to 850 parts by mass with respect to parts by mass.
<2> The polyamide resin composition according to <1>, wherein the inorganic fiber having a number average fiber length of 50 to 200 μm is a milled fiber.
<3> The polyamide resin composition according to <1> or <2>, further comprising an elastomer.
<4> The total amount of carbon fibers having a number average fiber length of 3 to 10 mm and inorganic fibers having a number average fiber length of 50 to 200 μm occupies 35 to 55% by mass of <1> to <1. The polyamide resin composition as described in any one of 3>.
<5> The polyamide resin composition according to any one of <1> to <4>, wherein the inorganic fiber having a number average fiber length of 50 to 200 μm includes at least a carbon fiber.
<6> The polyamide resin is composed of a structural unit derived from a diamine and a structural unit derived from a dicarboxylic acid, and 70 mol% or more of the structural unit derived from the diamine is derived from at least one of metaxylylenediamine and paraxylylenediamine. And 70 mol% or more of the structural unit derived from dicarboxylic acid is derived from α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms, according to any one of <1> to <5>. Polyamide resin composition.
<7> The polyamide resin composition according to <6>, wherein the α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms includes at least one of adipic acid and sebacic acid.
<8> A molded product obtained by molding the polyamide resin composition according to any one of <1> to <7>.
<9> A polyamide resin having a semi-crystallization time (ST (P)) of 20 to 500 seconds, a carbon fiber having a number average fiber length of 3 to 10 mm, a number average fiber length of 50 to 200 μm, and carbon Blending and kneading inorganic fibers selected from fibers and glass fibers,
5 to 60 parts by mass of carbon fiber having a number average fiber length of 3 to 10 mm is blended with respect to 100 parts by mass of the polyamide resin having a semi-crystallization time (ST (P)) of 20 to 500 seconds,
The manufacturing method of the polyamide resin composition which mix | blends 40-850 mass parts of said inorganic fiber whose said number average fiber length is 50-200 micrometers with respect to 100 mass parts of carbon fibers whose said number average fiber length is 3-10 mm.

  According to the present invention, a polyamide resin molded product blended with carbon fibers, which can provide a molded product having high mechanical strength and excellent appearance, and a molded product using the polyamide resin composition And a method for producing a polyamide resin composition can be provided.

  Hereinafter, the contents of the present invention will be described in detail. In the present specification, “to” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.

Polyamide resin composition The polyamide resin composition of the present invention comprises 100 parts by mass of a polyamide resin having a semi-crystallization time (ST (P)) of 20 to 500 seconds and a carbon fiber having a number average fiber length of 3 to 10 mm ( Hereinafter, it may be referred to as “specific carbon fiber.” 5 to 60 parts by mass, the number average fiber length is 50 to 200 μm, including inorganic fibers selected from carbon fiber and glass fiber, the number average fiber length 40 to 850 parts by mass with respect to 100 parts by mass of carbon fibers having a number average fiber length of 3 to 10 mm. It is characterized by. By molding using such a polyamide resin composition, a molded product having high mechanical strength and excellent appearance can be obtained.
In the present invention, by using a polyamide resin having a semi-crystallization time (ST (P)) of 20 to 500 seconds, since the solidification of the resin during molding is slow, it becomes easier to cover the surface of the molded product with the resin. The filler floating on the surface can be reduced, and a good appearance can be obtained. Since the specific inorganic fiber is a short fiber, when the specific inorganic fiber is mixed in the carbon fiber, the short specific inorganic fiber enters between the carbon fibers, thereby suppressing the undulation on the surface of the molded product. Therefore, a molded product having an excellent appearance can be obtained while maintaining the mechanical strength.

  Even if specific inorganic fiber is mix | blended, the specific gravity can be made small by mix | blending the polyamide resin composition of this invention with the said carbon fiber whose number average fiber length is 3-10 mm. Specifically, the specific gravity of the polyamide resin composition of the present invention has an upper limit of 1.70 or less, 1.60 or less, 1.55 or less, 1.50 or less, 1.48 or less, 1.45 or less, 1 .42 or less. The lower limit of the specific gravity can be, for example, 1.30 or more. The specific gravity of the polyamide resin composition of the present invention is measured according to the method described in Examples described later.

<Polyamide resin having a semi-crystallization time (ST (P)) of 20 to 500 seconds>
In the present invention, a polyamide resin having a half crystallization time (ST (P)) of 20 to 500 seconds (hereinafter sometimes referred to as “specific polyamide resin”) is used.
The semi-crystallization time is a value measured by a depolarization photometry method under the conditions that the sample melting temperature is the melting point of the polyamide resin + 30 ° C., the sample melting time is 3 minutes, and the crystallization oil bath temperature is 140 ° C. The de-change altitude method can be measured using, for example, a polymer crystallization rate measuring device (manufactured by Kotaki Seisakusho, model: MK701).

In the present invention, the semi-crystallization time (ST (P)) by crystallization at 140 ° C. in the depolarization photometric method of the specific polyamide resin is preferably 20 to 450 seconds, more preferably 25 to 150 seconds. .
By setting the half crystallization time to 20 seconds or more, the surface state of the molded product can be made uniform. Moreover, if the said half crystallization time is 500 second or less, the solidification defect and mold release defect in injection molding can be suppressed. Furthermore, when the crystallization of the obtained molded article proceeds sufficiently, the temperature dependence of the water absorption rate and physical properties of the molded article is small, and the dimensional stability is also good.

The polyamide resin used in the present invention is not particularly defined as long as it is a polyamide resin satisfying the above-mentioned half crystallization time, but a polyamide resin containing an aromatic ring in the molecule is preferable.
The specific polyamide resin used in the present invention is more preferably composed of a structural unit derived from diamine and a structural unit derived from dicarboxylic acid, and 70 mol% or more of the structural unit derived from diamine is metaxylylenediamine and paraxylylenediamine. Is a polyamide resin in which 70 mol% or more of the structural unit derived from dicarboxylic acid is derived from an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms. By using such a polyamide resin, the obtained molded product has an excellent balance between mechanical strength and appearance.

  The specific polyamide resin is preferably composed of 70 mol% or more, more preferably 80 mol% or more, further preferably 90 mol% or more, particularly preferably 95 mol% or more of metaxylylenediamine and paraxylylenediene. Preferably, the structural unit derived from at least one of the amines and derived from the dicarboxylic acid is 70 mol% or more, more preferably 80 mol% or more, still more preferably 90 mol%, particularly preferably 95 mol% or more, and the number of carbon atoms is Derived from 4 to 20 α, ω-linear aliphatic dicarboxylic acids.

Examples of diamines other than metaxylylenediamine and paraxylylenediamine that can be used as raw material diamine components for specific polyamide resins include tetramethylenediamine, pentamethylenediamine, 2-methylpentanediamine, hexamethylenediamine, heptamethylenediamine, and octamethylenediamine. Aliphatic diamines such as methylenediamine, nonamethylenediamine, decamethylenediamine, dodecamethylenediamine, 2,2,4-trimethyl-hexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, 1,3-bis (amino Methyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, bis (4-aminocyclohexyl) methane, 2,2-bis Such as alicyclic diamines such as 4-aminocyclohexyl) propane, bis (aminomethyl) decalin, bis (aminomethyl) tricyclodecane, bis (4-aminophenyl) ether, paraphenylenediamine, bis (aminomethyl) naphthalene, etc. Examples include diamines having an aromatic ring, and one kind or a mixture of two or more kinds can be used.
When a diamine other than xylylenediamine is used as the diamine component, it is preferably less than 20 mol% of the structural unit derived from diamine, and more preferably 10 mol% or less.

  Preferred examples of the α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms for use as the raw material dicarboxylic acid component of the polyamide resin include succinic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, adipic acid, Aliphatic dicarboxylic acids such as sebacic acid, undecanedioic acid, and dodecanedioic acid can be exemplified, and one or a mixture of two or more types can be used. Among these, the melting point of the polyamide resin is in an appropriate range for molding processing Therefore, adipic acid or sebacic acid is more preferable.

  Examples of the dicarboxylic acid component other than the α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms include phthalic acid compounds such as isophthalic acid, terephthalic acid and orthophthalic acid, 1,2-naphthalenedicarboxylic acid, 3-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 1,7-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3- Examples thereof include naphthalenedicarboxylic acids such as isomers such as naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid, and one kind or a mixture of two or more kinds can be used. When a dicarboxylic acid component other than an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms is used, it is preferably less than 20 mol% of the structural unit derived from the dicarboxylic acid, and is 10 mol% or less. Is more preferable.

  Even when the specific polyamide resin is composed mainly of a structural unit derived from diamine and a structural unit derived from dicarboxylic acid, it does not completely exclude other structural units, such as ε-caprolactam and laurolactam. It goes without saying that structural units derived from aliphatic aminocarboxylic acids such as lactams, aminocaproic acid and aminoundecanoic acid may be included. In the present invention, the total of the structural unit derived from the diamine and the structural unit derived from the dicarboxylic acid in the specific polyamide resin preferably accounts for 93% or more of all the structural units, and more preferably 97% or more.

  Moreover, in order to adjust the semi-crystallization time of a polyamide resin, you may use 2 or more types of polyamide resins. For example, it is composed of the structural unit derived from the diamine and the structural unit derived from dicarboxylic acid, and 70 mol% or more of the structural unit derived from the diamine is derived from at least one of metaxylylenediamine and paraxylylenediamine, and derived from dicarboxylic acid Examples include a blend of a polyamide resin in which 70 mol% or more of the structural unit is derived from an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms and an aliphatic polyamide resin. Examples of the aliphatic polyamide resin include polyamide 6, 11, 12, 46, 66, 610, 612, 6I, 6/66, and the like.

The melting point of the specific polyamide resin is preferably 150 to 310 ° C, more preferably 180 to 300 ° C, and further preferably 180 to 280 ° C.
Moreover, 50-150 degreeC is preferable, as for the glass transition point of specific polyamide resin, 55-120 degreeC is more preferable, More preferably, it is 60-100 degreeC. Within this range, the heat resistance of the molded product tends to be better.
The melting point and glass transition point are measured according to the methods described in the examples described later.

  The specific polyamide resin preferably has a lower limit of the number average molecular weight (Mn) of 6,000 or more, more preferably 8,000 or more, further preferably 10,000 or more, and 15,000. More preferably, it is more preferably 20,000 or more, and even more preferably 22,000 or more. The upper limit of the Mn is preferably 35,000 or less, more preferably 30,000 or less, further preferably 28,000 or less, and further preferably 26,000 or less. Within such a range, the heat resistance, elastic modulus, dimensional stability, and moldability become better.

The specific polyamide resin preferably has a molecular weight distribution (weight average molecular weight / number average molecular weight (Mw / Mn)) of 1.8 to 3.1. The molecular weight distribution is more preferably 1.9 to 3.0, still more preferably 2.0 to 2.9. By setting the molecular weight distribution in such a range, a three-dimensional structure excellent in mechanical properties tends to be easily obtained.
The molecular weight distribution of the specific polyamide resin can be adjusted, for example, by appropriately selecting the polymerization reaction conditions such as the type and amount of the initiator and catalyst used during the polymerization, and the reaction temperature, pressure, and time.

  The number average molecular weight and the weight average molecular weight can be determined by GPC measurement. Specifically, two instruments, “HLC-8320GPC” manufactured by Tosoh Corporation, and two “TSK gel Super HM-H” manufactured by Tosoh Corporation are used as columns. Used, eluent of sodium trifluoroacetate concentration 10 mmol / L hexafluoroisopropanol (HFIP), resin concentration 0.02 mass%, column temperature 40 ° C., flow rate 0.3 mL / min, refractive index detector (RI) It can be measured under conditions and determined as a standard polymethyl methacrylate equivalent value. A calibration curve is prepared by dissolving 6 levels of PMMA in HFIP.

The lower limit of the content of the specific polyamide resin in the polyamide resin composition of the present invention is preferably 45% by mass or more of the polyamide resin composition, more preferably 47% by mass or more, and 50% by mass or more. More preferably. The upper limit of the content is preferably 70% by mass or less, more preferably 65% by mass or less, and further preferably 60% by mass or less.
The specific polyamide resin contained in the polyamide resin composition of the present invention may be one kind or two or more kinds. In the case of two or more types, the total amount is preferably within the above range.

<Carbon fiber having a number average fiber length of 3 to 10 mm>
In the present invention, carbon fibers (specific carbon fibers) having a number average fiber length of 3 to 10 mm are used. By using the carbon fiber having such a length, a molded product having excellent mechanical strength can be obtained. The type of the specific carbon fiber is not particularly defined, and any of polyacrylonitrile-based carbon fiber (PAN-based fiber) and pitch-based carbon fiber using pitch is preferably used, and polyacrylonitrile-based carbon fiber (PAN-based fiber) ) Is more preferable.

The specific carbon fiber is preferably chopped strand.
The specific carbon fiber has a lower limit of the number average fiber length of 3 mm or more, preferably 4 mm or more. The upper limit of the number average fiber length is 10 mm or less, preferably 8 mm or less, more preferably 7 mm or less, and further preferably 6 mm or less.
The specific carbon fiber preferably has a number average fiber diameter of 3 to 20 μm, more preferably 5 to 15 μm. By using carbon fibers in such a range, the obtained molded product can be made more excellent in balance between mechanical strength and appearance.
The specific carbon fiber has a tensile strength of 5.0 GPa or less (preferably 3.5 to 5.0 GPa, more preferably 3.5 to 5.0) as measured according to JIS R7601 at 23 ° C. of the specific carbon fiber. 4.9 GPa) can also be used.
In the polyamide resin composition of the present invention, even when a material having a relatively low tensile strength is used, the elastic modulus and the Charpy impact strength can be maintained, and a good appearance can be achieved.
Specific examples of the specific carbon fiber include, for example, trading card manufactured by Toray Industries, Inc., besfite filament manufactured by Toho Tenax Co., Ltd., and pyrofil manufactured by Mitsubishi Rayon Co., Ltd.

The lower limit of the content of the specific carbon fiber in the polyamide resin composition of the present invention is 5 parts by mass or more of the specific carbon fiber with respect to 100 parts by mass of the specific polyamide resin, preferably 10 parts by mass or more, and more preferably 13 parts by mass or more. Preferably, 15 parts by mass or more is more preferable, 30 parts by mass or more is more preferable, and 34 parts by mass or more is even more preferable. The upper limit of the content is 60 parts by mass or less, preferably 50 parts by mass or less, more preferably 45 parts by mass or less, and still more preferably 40 parts by mass or less. By setting it as such a range, the molded product obtained can be made more excellent by the balance of mechanical strength and an external appearance.
1 type of specific carbon fiber contained in the polyamide resin composition of this invention may be sufficient, and 2 or more types may be sufficient as it. In the case of two or more types, the total amount is preferably within the above range.

<Inorganic fiber having a number average fiber length of 50 to 200 μm and selected from carbon fiber and glass fiber>
In the present invention, inorganic fibers (specific inorganic fibers) having a number average fiber length of 50 to 200 μm are used, and milled fibers are preferable. When milled fiber is milled, the fiber surface is damaged. This flawed portion can help the specific carbon fiber to be more finely crushed during melt kneading, and the surface appearance of the resulting molded product can be more effectively improved.

In the specific inorganic fiber used in the present invention, the lower limit of the number average fiber length is preferably 10 μm or more, more preferably 20 μm or more, further preferably 40 μm or more, and further preferably 50 μm or more. . The upper limit of the number average fiber length is preferably 200 μm or less, more preferably 150 μm or less, further preferably 120 μm or less, and further preferably 100 μm or less. By setting it as such a range, the molded product obtained can be made more excellent by the balance of mechanical strength and an external appearance.
In the specific inorganic fiber used in the present invention, the lower limit of the number average fiber diameter is preferably 1 μm or more, more preferably 2 μm or more, and further preferably 3 μm or more. The upper limit of the number average fiber diameter is preferably 25 μm or less, more preferably 20 μm or less, and further preferably 15 μm or less. By setting it as such a range, the molded product obtained can be made more excellent by the balance of mechanical strength and an external appearance.
The average fiber length and the average fiber diameter are determined by observing the length and diameter of a desired 100 fibers using a microscope and calculating the average value.

The specific inorganic fiber used in the present invention is selected from carbon fiber and glass fiber, and preferably includes at least carbon fiber, and 90% by mass or more of the specific inorganic fiber included in the polyamide resin composition of the present invention is carbon fiber. It is more preferable. By using carbon fiber as the specific inorganic fiber, familiarity with the specific carbon fiber is improved, and the effects of the present invention are more effectively exhibited.
As a commercial item of the specific inorganic fiber used by this invention, Central Glass Co., Ltd. product, EFH 50-31 / T, Nippon Electric Glass Co., Ltd. product, EPG70M-01N, Zoltec Co., Ltd. and PX35MF0150 are illustrated.

  The specific inorganic fiber used in the present invention may be surface-treated with a surface treatment agent. Examples of the surface treatment agent include silane coupling agents such as γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-aminopropyltriethoxysilane. Moreover, it is preferable that the adhesion amount of a surface treating agent is 0.01-1 mass% of a specific inorganic fiber.

The lower limit of the content of the specific inorganic fiber in the polyamide resin composition of the present invention is that the specific carbon fiber is 40 parts by mass or more, preferably 50 parts by mass or more, and 60 parts by mass or more with respect to 100 parts by mass of the specific carbon fiber. More preferably, 70 parts by mass or more is more preferable, 80 parts by mass or more is more preferable, and 90 parts by mass or more is even more preferable. The upper limit of the content is 850 parts by mass or less, preferably 650 parts by mass or less, more preferably 450 parts by mass or less, further preferably 350 parts by mass or less, still more preferably 200 parts by mass or less, and 150 parts by mass or less. Even more preferred.
The specific inorganic fiber contained in the polyamide resin composition of the present invention may be only one kind or two or more kinds. In the case of two or more types, the total amount is preferably within the above range.

  In the polyamide resin composition of the present invention, the lower limit of the total amount of the specific carbon fiber and the specific inorganic fiber is preferably 35% by mass or more, more preferably 37% by mass or more, More preferably, it is 40 mass% or more. The upper limit of the content is preferably 55% by mass or less, more preferably 53% by mass or less, and further preferably 50% by mass or less.

<Elastomer>
The polyamide resin composition of the present invention may contain an elastomer. By including an elastomer, impact resistance can be improved. Elastomers are known as impact resistance improvers, but it is known that impact resistance is not improved with resin compositions containing carbon fibers, and elastomers are added to the polyamide resin composition of the present invention. It is surprising that the impact resistance is improved.
The elastomer used in the present invention includes methyl methacrylate-butadiene-styrene copolymer (MBS resin), methyl methacrylate-butadiene rubber copolymer (MB resin), styrene-butadiene triblock called SBS, SEBS. Copolymer and its hydrogenated product, Styrene-isoprene triblock copolymer called SPS and SEPS and its hydrogenated product, Olefin thermoplastic elastomer called TPO, polyester elastomer, siloxane type Examples thereof include rubber, acrylate rubber, and siloxane copolymer elastomer. As the elastomer, the elastomer described in paragraphs 0075 to 0088 of JP2012-251061A, the elastomer described in paragraph numbers 0101 to 0107 of JP2012-1777047A, and the like can be used. Incorporated herein. In the present invention, a styrene-butadiene triblock copolymer and a hydrogenated product thereof are preferable, and SEBS is more preferable.

The blending amount of the elastomer is 0.5 to 10 parts by mass, preferably 1 to 8 parts by mass, and more preferably 3 to 7 parts by mass with respect to 100 parts by mass of the polyamide resin.
The polyamide resin composition of the present invention may contain only one type of elastomer, or may contain two or more types. When 2 or more types are included, the total amount falls within the above range.

<Black colorant>
The polyamide resin composition of the present invention preferably contains a black colorant. In the present invention, by adding a black colorant, it is possible to provide a molded article having high appearance and high rigidity, high modulus of elasticity, and suppression of carbon fiber floating and carbon fiber transparency. become.

The type of the black colorant is not particularly defined, and examples thereof include pigments such as carbon black and titanium black, nigrosine and aniline black.
In the polyamide resin composition of the present invention, by incorporating carbon black, the carbon black functions as a nucleating agent, and good moldability can be achieved even when thin-walled. That is, in the present invention, since a resin having a low crystallization rate is used, curing is difficult to proceed in thin-wall molding, but by adding carbon black as a black colorant, carbon black functions as a nucleating agent and cures. Proceed. As a result, in the present invention, a thin molded product having a thickness of 1 mm or less can be molded well.

As the carbon black used in the present invention, any conventionally known carbon black can be used. Examples thereof include furnace black, channel black, ketjen black, and acetylene black. Among them, it is preferable to use carbon black excellent in hiding power and DBP absorption of 30 to 300 g / 100 cm ³ , particularly furnace black, because a stable color tone can be expressed.

  As nigrosine used in the present invention, any conventionally known nigrosine dye can be used. I. SOLVENTBLACK5, C.I. I. Examples of SOLVENTBLACK7 include black azine-based condensation mixtures described in COLORINDEX. Examples of commercially available products include Nubian Black (trade name) manufactured by Orient Chemical.

  Nigrosine used in the present invention is not particularly limited in its production method. For example, a method obtained by oxidizing and dehydrating aniline, aniline hydrochloride and nitrobenzene at a reaction temperature of 160 to 180 ° C. in the presence of iron chloride. Can be mentioned. Nigrosine is obtained as a mixture of various different compounds depending on reaction conditions, charged raw materials, charged ratio, and the like, and is a mixture of various triphenazine oxazines and azine compounds such as phenazine azine.

  Examples of aniline black used in the present invention include C.I. I. It is an oxidative condensation mixture such as a black aniline derivative described in COLORINDEX as PIGMENTBLACK1, and is a mixture with several intermediates and by-products depending on the oxidative condensation reaction conditions. Specifically, by subjecting aniline hydrochloride and aniline to oxidative condensation for 1-2 days at a reaction temperature of 40 to 60 ° C., by complete immersion in sulfuric acid dichromate solution for a short time, complete oxidative condensation , And can be obtained as a black colorant mixture. Examples of aniline black include aniline black manufactured by ICI.

The blending amount of the black colorant in the polyamide resin composition of the present invention is preferably 0.1 to 5.0% by mass, more preferably 0.5 to 3.0% by mass. More preferably, it is 0-2.5 mass%.
The black colorant contained in the polyamide resin composition of the present invention may be one type or two or more types. When 2 or more types are included, the total amount is preferably within the above range.

<Release agent>
In order that the polyamide resin composition of this invention may improve the mold release property at the time of shaping | molding, it is preferable to mix | blend a mold release agent. As the release agent, those which do not easily reduce the flame retardancy of the polyamide resin composition of the present invention are preferable, and examples thereof include carboxylic acid amide waxes, bisamide waxes, and long-chain fatty acid metal salts.

The carboxylic acid amide wax is obtained by a dehydration reaction between a mixture of a higher aliphatic monocarboxylic acid and a polybasic acid and a diamine compound. As the higher aliphatic monocarboxylic acid, a saturated aliphatic monocarboxylic acid having 16 or more carbon atoms and a hydroxycarboxylic acid are preferable, and examples thereof include palmitic acid, stearic acid, behenic acid, montanic acid, 12-hydroxystearic acid and the like. It is done. Examples of polybasic acids include dibasic or higher carboxylic acids such as malonic acid, succinic acid, adipic acid, sebacic acid, pimelic acid, azelaic acid and other aliphatic dicarboxylic acids, and phthalic acid, terephthalic acid and other aromatics. And alicyclic dicarboxylic acids such as cyclohexane dicarboxylic acid and cyclohexyl succinic acid.
Examples of the diamine compound include ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, hexamethylenediamine, metaxylylenediamine, tolylenediamine, paraxylylenediamine, phenylenediamine, and isophoronediamine. .

  The softening point of the carboxylic acid amide wax in the present invention can be arbitrarily adjusted by changing the mixing ratio of the polybasic acid to the higher aliphatic monocarboxylic acid used in the production thereof. The mixing ratio of the polybasic acid is preferably in the range of 0.18 to 1 mol with respect to 2 mol of the higher aliphatic monocarboxylic acid. The amount of the diamine compound used is preferably in the range of 1.5 to 2 mol per 2 mol of the higher aliphatic monocarboxylic acid, and varies according to the amount of polybasic acid used.

  Examples of the bisamide wax include diamine compounds and fatty acid compounds such as N, N′-methylenebisstearic acid amide and N, N′-ethylene bisstearic acid amide, or N, N′-dioctadecyl terephthalic acid. Mention may be made of dioctadecyl dibasic acid amides such as amides.

  The long-chain fatty acid metal salt is a metal salt of a long-chain fatty acid having 16 to 36 carbon atoms. For example, calcium stearate, calcium montanate, sodium montanate, zinc stearate, aluminum stearate, sodium stearate, stearic acid Lithium etc. are mentioned.

When mix | blending a mold release agent with the polyamide resin composition of this invention, 0.1-3.0 mass parts is preferable with respect to 100 mass parts of specific polyamide resin, 0.1-2.0 mass is preferable. Part is more preferred.
Only one type of release agent may be used, or two or more types may be used in combination. When using 2 or more types together, it is preferable that a total amount becomes the said range.

<Nucleating agent>
The polyamide resin composition of the present invention may contain a nucleating agent in order to adjust the crystallization rate. The kind of the nucleating agent is not particularly limited, but talc, boron nitride, mica, kaolin, calcium carbonate, barium sulfate, silicon nitride, potassium titanate and molybdenum disulfide are preferable, and talc and boron nitride are more preferable. Talc is more preferable.
When the polyamide resin composition of the present invention contains a nucleating agent, the content thereof is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 8 parts by mass with respect to 100 parts by mass of the specific polyamide resin. Preferably, 0.1-5 mass parts is more preferable.
The polyamide resin composition of the present invention may contain only one kind of nucleating agent, or may contain two or more kinds. When 2 or more types are included, the total amount is preferably within the above range.

<Other additives>
Furthermore, the polyamide resin composition of the present invention may contain other components as necessary. For example, heat stabilizers, antioxidants, ultraviolet absorbers, dyes and pigments other than black colorants, flame retardants, anti-dripping agents, antistatic agents, antifogging agents, antiblocking agents, fluidity improvers, plasticizers, Dispersing agents, antibacterial agents, thermoplastic resins other than the above, and the like can be mentioned. These components are preferably 5% by mass or less of the polyamide resin composition of the present invention.
The polyamide resin composition of the present invention may contain a filler component other than the specific carbon fiber and the specific inorganic fiber. Examples of other filler components include carbon fibers having a number average fiber length of less than 3 mm, carbon fibers having a number average fiber length of more than 10 mm, and whiskers. As one embodiment of the polyamide resin composition of the present invention, other filler components can be substantially not contained. Here, “substantially not containing” is exemplified that the specific carbon fiber content is 5% by mass or less.

<Manufacturing method of polyamide resin composition>
The manufacturing method of the polyamide resin composition of this invention can employ | adopt widely the manufacturing method of a well-known thermoplastic resin composition.
As one embodiment of the method for producing a polyamide resin composition of the present invention, a polyamide resin having a semi-crystallization time (ST (P)) of 20 to 500 seconds, a carbon fiber having a number average fiber length of 3 to 10 mm, and And the number average fiber length is 50 to 200 μm, including mixing and kneading inorganic fibers selected from carbon fibers and glass fibers, and the semicrystallization time (ST (P)) is 20 to 500 seconds. 5 to 60 parts by mass of carbon fiber having a number average fiber length of 3 to 10 mm is blended with respect to 100 parts by mass of a certain polyamide resin, and 100 parts by mass of carbon fiber having a number average fiber length of 3 to 10 mm, The manufacturing method of the polyamide resin composition which mix | blends 40-850 mass parts of inorganic fibers whose number average fiber length is 50-200 micrometers is mentioned. An example of such a polyamide resin composition is pellets.
Specifically, the specific polyamide resin, the specific carbon fiber, the specific inorganic fiber, and other components to be blended as necessary are mixed in advance using various mixers such as a tumbler and a Henschel mixer, and then Banbury mixer And a melt kneading method using a mixer such as a roll, a brabender, a single-screw kneading extruder, a twin-screw kneading extruder, or a kneader.

Further, for example, each component is not mixed in advance, or only a part of the components (for example, specific carbon fiber and specific inorganic fiber) is mixed in advance and supplied to an extruder using a feeder and melt-kneaded. The polyamide resin composition of the present invention can also be produced.
In addition, for example, a composition obtained by mixing a part of components (for example, a black colorant) in advance, supplying the mixture to an extruder, and melt-kneading is used as a master batch, and this master batch is mixed with the remaining components again. And the polyamide resin composition of this invention can also be manufactured by melt-kneading.
In addition, for example, when mixing a component that is difficult to disperse, the component that is difficult to disperse is dissolved or dispersed in a solvent such as water or an organic solvent in advance, and is kneaded with the solution or dispersion. It can also improve sex.

<Molded product>
The molded article of the present invention is formed by molding the polyamide resin composition of the present invention. There are no restrictions on the shape, pattern, color, size, etc. of the molded product, and it may be set arbitrarily according to the application of the molded product.
In particular, examples of the molded product of the present invention include thin molded products. The thickness of the thin part in the molded article provided from the polyamide resin composition of the present invention can be 0.2 to 4 mm, and particularly a molded article having a part having a thickness of 0.5 to 2 mm. It is also possible to provide.
The molded product obtained from the polyamide resin composition of the present invention preferably has a bending strength of 300 MPa or more, more preferably 340 MPa or more, further preferably 350 MPa or more, and preferably 370 MPa or more. Even more preferred. Although the upper limit of the bending strength is not particularly defined, for example, 500 MPa or less, and even 450 MPa or less is sufficiently practical.
The molded product obtained from the polyamide resin composition of the present invention preferably has a flexural modulus of 23 GPa or more, more preferably 25 GPa or more, and even more preferably 27 GPa or more. Although the upper limit of the elastic modulus is not particularly defined, for example, 40 GPa or less, and even 38 GPa or less is sufficiently practical.
The bending strength and bending elastic modulus in the present invention are measured by the methods described in the examples described later.

  Examples of applications of the molded article of the present invention include parts such as electrical and electronic equipment, OA equipment, information terminal equipment, machine parts, home appliances, vehicle parts, building members, various containers, leisure goods / miscellaneous goods, and lighting equipment. Be mentioned.

  The manufacturing method of the molded article of the present invention is not particularly limited, and a molding method generally adopted for the thermoplastic resin composition can be arbitrarily adopted. For example, injection molding method, ultra-high speed injection molding method, injection compression molding method, two-color molding method, hollow molding method such as gas assist, molding method using heat insulating mold, rapid heating mold were used. Molding method, foam molding (including supercritical fluid), insert molding, IMC (in-mold coating molding) molding method, extrusion molding method, sheet molding method, thermoforming method, rotational molding method, laminate molding method, press molding method, etc. Is mentioned. A molding method using a hot runner method can also be used. When a mold is used in molding, the mold temperature is preferably 100 ° C. or higher, more preferably 120 ° C. or higher because a specific polyamide resin is used in the present invention. If the mold temperature is too low, the crystallization of the specific polyamide resin is insufficient, and the mold transferability of the appearance tends to deteriorate, or the carbon fibers tend to float. The upper limit of the mold temperature is preferably 180 ° C. or less from the viewpoint of suppressing deformation when the molded product is released from the mold. The upper limit is not particularly defined, but can be, for example, 160 ° C. or less.

  The present invention will be described more specifically with reference to the following examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.

<Material used in Examples>
MXD6: polymetaxylylene adipamide, manufactured by Mitsubishi Gas Chemical Company, trade name “MX Nylon S6000”, melting point 243 ° C., glass transition point 75 ° C.
Polymer crystallization rate measuring device (manufactured by Kotaki Seisakusho, model: MK701) under the conditions of depolarization photometry, sample melting temperature + 30 ° C melting point of polyamide resin, sample melting time 3 minutes, and crystallization oil bath temperature 140 ° C The half crystallization time (ST (P)) measured using was 100 seconds.
The melting point of the polyamide resin was measured as the temperature at the peak top of the endothermic peak at the time of temperature increase observed by the DSC (Differential Scanning Calorimetry) method. The glass transition temperature of the polyamide resin was measured as a peak top temperature measured by heating and melting the polyamide resin once to eliminate the influence of the thermal history on the crystallinity and then raising the temperature again.
Specifically, using a DSC measuring device, the amount of the polyamide resin as a sample is about 1 mg, nitrogen is flowed at 30 mL / min as the atmospheric gas, and the rate of temperature increase is expected from room temperature at 10 ° C./min. The melting point was determined from the temperature at the peak top of the endothermic peak observed when the mixture was heated to a temperature equal to or higher than the melting point. Next, the melted polyamide resin was rapidly cooled with dry ice, and the temperature was raised again to a temperature equal to or higher than the melting point at a rate of 10 ° C./min to obtain a glass transition temperature. As the DSC measuring instrument, DSC-60 manufactured by Shimadzu Corporation was used.

PA66: Polyamide 66, manufactured by DuPont, Zytel 101NC-10, melting point 265 ° C., glass transition point 55 ° C.
The half crystallization time (ST (P)) measured in the same manner as described above was 3 seconds.

MP6: Synthesized according to the following production example.
<< Synthesis of Polyamide (MP6) >>
After adipic acid is heated and dissolved in a reactor under a nitrogen atmosphere, the molar ratio of paraxylylenediamine (Mitsubishi Gas Chemical) and metaxylylenediamine (Mitsubishi Gas Chemical) is While gradually dropping a 3: 7 mixed diamine under pressure (0.35 MPa) so that the molar ratio of diamine to adipic acid (made by Rhodia) is about 1: 1, the temperature is increased to 270 ° C. Raised. After completion of the dropping, the pressure was reduced to 0.06 MPa and the reaction was continued for 10 minutes to adjust the amount of the component having a molecular weight of 1,000 or less. Thereafter, the content was taken out into a strand shape and pelletized with a pelletizer to obtain a polyamide resin. Hereinafter, it is referred to as “MP6”. The resulting MP6 had a melting point of 257 ° C. and a glass transition point of 75 ° C. The half crystallization time (ST (P)) measured in the same manner as described above was 30 seconds.

MP10: Synthesized according to the following production example.
<< Synthesis of Polyamide (MP10) >>
730 g of sebacic acid was charged into a 3 L flask equipped with a stirrer, thermometer, reflux condenser, raw material dripping device, heating device, etc., and the temperature inside the flask was raised to 160 ° C. in a nitrogen atmosphere to increase sebacic acid. Was melted. Into the flask, 680 g of mixed xylylenediamine containing 30 mol% of paraxylylenediamine and 70 mol% of metaxylylenediamine was successively added dropwise over about 2.5 hours. During this time, the reaction was continued with stirring while maintaining the internal temperature always above the melting point of the product, and the temperature was raised to 270 ° C. at the end of the reaction. Water generated by the reaction was discharged out of the reaction system by a partial condenser. After completion of the dropping, the reaction was continued by stirring at a temperature of 275 ° C., and the reaction was terminated after 1 hour. The product was removed from the flask, cooled with water and pelletized. The resulting MP10 had a melting point of 215 ° C. and a glass transition point of 63 ° C. The half crystallization time (ST (P)) measured in the same manner as described above was 30 seconds.

Carbon fiber 1: Polyacrylonitrile-based carbon fiber, manufactured by Mitsubishi Rayon Co., Ltd., Pyrofil TR06NL, tensile strength 4.9 GPa, number average fiber diameter 7 μm, number average fiber length 6 mm
Carbon fiber 2: Soltec milled fiber, manufactured by Soltec, PX35MF0150, number average fiber diameter 7 μm, number average fiber length 100 μm
Glass fiber 1: Milled fiber, manufactured by Central Glass Co., Ltd., EFH 50-31 / T, number average fiber diameter 11 μm, number average fiber length 50 μm
Wollastonite: NYGLOS8-10013, Sakai Kogyo Co., Ltd. Elastomer: SEBS, FG1901GH, Kraton Polymer Japan Co., Ltd. Nucleating Agent 1: Talc, Hayashi Kasei Co., Ltd., Micron White 5000S
Nucleating agent 2: Talc, Hayashi Kasei Co., Ltd., Micron White 5000A

Black colorant 1: Carbon black, manufactured by Mitsubishi Engineering Plastics, PR-MP10BK1
Black colorant 2: Carbon black, manufactured by Mitsubishi Engineering Plastics, PR-MP6BK
Black colorant 3: Carbon black, manufactured by Ota Kasei Co., Ltd., # 45-50
Mold release agent 1: Ketone wax, manufactured by Emery Oleo Chemicals Japan, LOXIOLEP 2036-18
Release agent 2: calcium montanate, manufactured by Nitto Kasei Kogyo Co., Ltd., CS-8CP

Examples and Comparative Examples <Compounds of Polyamide Resin Composition>
Each component is weighed according to Table 1 described later, and components other than carbon fiber, glass fiber, wollastonite and black colorant are blended with a tumbler, and from the basis of a twin screw extruder (Toshiki Machine Co., Ltd., TEM26SS). Charged and melted. The black colorant was added and kneaded after producing a 50% by mass masterbatch with a polyamide resin. After kneading, carbon fibers, glass fibers, and wollastonite were side fed to prepare resin pellets (polyamide resin composition). The set temperature of the extruder was 280 ° C.

<Measurement method of bending strength and flexural modulus>
After drying the resin pellet obtained by the above-mentioned manufacturing method at 120 ° C. for 4 hours, an ISO tensile test piece having a thickness of 4 mm was injection molded using NEX140III manufactured by Nissei Plastic Industry Co., Ltd. The cylinder temperature was 280 ° C and the mold temperature was 130 ° C.
Based on ISO178, the bending strength (unit: MPa) and the bending elastic modulus (unit: GPa) were measured at a temperature of 23 ° C. using the ISO tensile test piece (4 mm thickness).

<Charpy impact strength>
Using the ISO tensile test piece obtained by the method described above, the Charpy impact strength with a notch was measured under the condition of 23 ° C. in accordance with ISO 179-1 and ISO 179-2. The unit of Charpy impact strength is indicated by kJ / m ² .

<Measurement method of specific gravity>
The specific gravity was measured according to ISO1883 using the ISO tensile test piece obtained by the above method.

<Appearance>
After drying the resin pellet obtained by the above-mentioned manufacturing method at 120 ° C. for 4 hours, a 100 square plate having a thickness of 3 mm was injection-molded using FANUC α-100iA. The cylinder temperature was 280 ° C and the mold temperature was 130 ° C. The obtained plate was visually confirmed from an oblique angle under a three-wavelength fluorescent lamp, and the state of the plate surface was digitized according to the following criteria.
5: Swelling is not confirmed and the mirror surface is completely mirrored 4: Swelling is almost not confirmed and the mirror surface is almost mirror surface 3: Swelling is confirmed in a very small part but close to the mirror surface 2: Swelling Partly confirmed 1: Swelling is confirmed over the entire surface

The unit of each component in Table 1 is mass%.
As is clear from the above results, the polyamide resin composition of the present invention was able to achieve high mechanical strength and excellent appearance. Further, a molded product having a small specific gravity was obtained. Furthermore, higher Charpy impact strength can be achieved by blending elastomer.

Claims (9)

100 parts by mass of a polyamide resin having a semi-crystallization time (ST (P)) of 20 to 500 seconds, 5 to 60 parts by mass of carbon fibers having a number average fiber length of 3 to 10 mm, and a number average fiber length of 50 to 200 μm, including inorganic fibers selected from carbon fibers and glass fibers,
The inorganic fiber whose number average fiber length is 50-200 micrometers is a polyamide resin composition containing 40-850 mass parts with respect to 100 mass parts of carbon fibers whose said number average fiber length is 3-10 mm. The polyamide resin composition according to claim 1, wherein the inorganic fiber having a number average fiber length of 50 to 200 μm is a milled fiber. Furthermore, the polyamide resin composition of Claim 1 or 2 containing an elastomer. The total amount of the carbon fiber whose said number average fiber length is 3-10 mm and the inorganic fiber whose said number average fiber length is 50-200 micrometers occupies 35-55 mass% of the whole, either of Claims 1-3. 2. The polyamide resin composition according to item 1. The polyamide resin composition according to any one of claims 1 to 4, wherein the inorganic fibers having a number average fiber length of 50 to 200 µm include at least carbon fibers. The polyamide resin is composed of a structural unit derived from diamine and a structural unit derived from dicarboxylic acid, and 70 mol% or more of the structural unit derived from diamine is derived from at least one of metaxylylenediamine and paraxylylenediamine, The polyamide resin composition according to any one of claims 1 to 5, wherein 70 mol% or more of the structural unit derived from the acid is derived from an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms. . The polyamide resin composition according to claim 6, wherein the α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms contains at least one of adipic acid and sebacic acid. The molded article formed by shape | molding the polyamide resin composition of any one of Claims 1-7. A polyamide resin having a semi-crystallization time (ST (P)) of 20 to 500 seconds, a carbon fiber having a number average fiber length of 3 to 10 mm, a number average fiber length of 50 to 200 μm, a carbon fiber and glass Including mixing and kneading inorganic fibers selected from fibers,
5 to 60 parts by mass of carbon fiber having a number average fiber length of 3 to 10 mm is blended with respect to 100 parts by mass of the polyamide resin having a semi-crystallization time (ST (P)) of 20 to 500 seconds,
The manufacturing method of the polyamide resin composition which mix | blends 40-850 mass parts of said inorganic fiber whose said number average fiber length is 50-200 micrometers with respect to 100 mass parts of carbon fibers whose said number average fiber length is 3-10 mm.