JP5911426B2 - Polyamide resin composition and molded product obtained therefrom - Google Patents

Description

  The present invention relates to a polyamide resin composition that is excellent in light weight and bending properties and can reduce warpage when formed into a molded body.

  A polyamide resin composition reinforced with an inorganic reinforcing material is known. As such an inorganic reinforcing material, in addition to fibrous reinforcing materials such as glass fibers and carbon fibers, granular reinforcing materials such as talc and mica are used. A polyamide resin composition filled with such a high content of inorganic reinforcing material has greatly improved bending characteristics. However, on the other hand, since the density becomes too high due to the inorganic reinforcing material, there is a problem that it becomes too heavy to be used as a molded body in various uses, and the use is limited.

  In order to reduce the weight of such a high-density polyamide resin composition, it has been proposed to use a layered silicate instead of an inorganic reinforcing material. By using the layered silicate, it is possible to obtain a polyamide resin composition having a low density and a significantly improved bending property. However, the polyamide resin composition in which the layered silicate is used instead of the inorganic reinforcing material has a high bending property improvement effect, but the resulting polyamide body becomes brittle because the polyamide molecular chain is strongly restrained by the layered silicate. There is a problem that the effect of improving the strength is limited.

  JP63-251461A and JP06-84435A propose polyamide resin compositions containing fibrous clay minerals in order to reduce the weight of the polyamide resin composition while improving the bending characteristics. In the polyamide resin compositions disclosed in JP63-251461A and JP06-84435A, weight reduction is achieved. However, since the anisotropy peculiar to the fibrous reinforcing material is remarkably exhibited, there is a problem that the warp is remarkably exhibited in a molded body (particularly, a thin molded body) obtained from the resin composition.

  On the other hand, JPS53-121843A proposes a resin composition containing both a plate-like filler and a fibrous reinforcing material. However, the molded body obtained from the polyamide resin composition disclosed in JPS53-121843A has a problem in that the warp is not sufficiently reduced, and in addition, the bending characteristics are deteriorated.

  In order to solve such problems, the present invention is excellent in light weight and bending characteristics while maintaining toughness, which is a property inherent to a polyamide resin, and can reduce warpage when formed into a molded body. An object is to provide a polyamide resin composition.

That is, the gist of the present invention is as follows.
(1) A polyamide resin composition comprising a polyamide resin (A), a fibrous clay mineral (B), a fibrous reinforcing material (C) and a non-fibrous clay mineral (D) as constituent components,
The fibrous clay mineral (B) is sepiolite and / or palygorskite,
The fibrous reinforcing material (C) is glass fiber and / or carbon fiber,
The blending ratio of the (A), (B), (C) and (D) satisfies the following formulas (I), (II) and (III) at the same time in terms of mass ratio,
The polyamide resin composition, wherein the content of (D) is 0.1 to 10 parts by mass with respect to 100 parts by mass of the polyamide resin composition obtained.
(A) / [(B) + (C) + (D)] = 40/60 to 90/1 (I)
(B) / [(C) + (D)] = 8/92 to 75/25 (II)
(C) / (D) = 1/1 to 50/1 (III )
(2 ) A molded product obtained by molding the polyamide resin composition of (1 ) .
( 3 ) The molded product according to ( 2 ), wherein the thickness is 3 mm or less.
( 4 ) A method for producing a polyamide resin composition according to (1 ) , comprising the following (i) to (iii):
(I) A step of melting the monomer constituting the polyamide resin (A) and the acid (E) at a temperature equal to or higher than the melting point of the monomer and further mixing the fibrous clay mineral (B) to obtain a mixture.
(Ii) Resin containing polyamide resin (A) and fibrous clay mineral (B) by subjecting the mixture obtained in step (i) to melt polymerization and polymerizing monomers constituting polyamide resin (A) Obtaining a composition;
(Iii) After step (ii), the fibrous reinforcing material (C) and the non-fibrous clay mineral (D) are added to the resin composition containing the polyamide resin (A) and the fibrous clay mineral (B). In addition, a step of melt kneading.
( 5 ) A method for producing a polyamide resin composition according to (1 ) , comprising the following step (iv):
Step (iv): A step of melt-kneading the polyamide resin (A), the fibrous clay mineral (B), the fibrous reinforcing material (C), and the non-fibrous clay mineral (D).

  According to the present invention, the fibrous clay mineral is used while maintaining the toughness that is the inherent property of the polyamide resin, and thus it is excellent in lightness and bending properties. In addition, the fibrous reinforcing material and the non-fibrous clay mineral are used. Thus, a polyamide resin composition capable of reducing warpage when formed into a molded body is obtained.

It is the schematic for showing the test piece for evaluating the curvature amount of the molded object formed by shape | molding the polyamide resin composition obtained by this invention, Comprising: FIG. 2 is a schematic view showing a test piece for evaluating the amount of warpage in a molded article formed by molding the polyamide resin composition obtained in the present invention, after 24 hours from taking out from a mold. .

The present invention is described in detail below.
The polyamide resin composition of the present invention contains a polyamide resin (A), a fibrous clay mineral (B), a fibrous reinforcing material (C), and a non-fibrous clay mineral (D).

  The polyamide resin (A) in the present invention is a polymer having, in the main chain, an amide bond mainly composed of aminocarboxylic acid, lactam, diamine and dicarboxylic acid, or a pair of salts of diamine and dicarboxylic acid.

  Examples of aminocarboxylic acids include 6-aminocaproic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid. Examples of the lactam include ε-caprolactam, ω-undecanolactam, ω-laurolactam and the like. Examples of the diamine include tetramethylene diamine, hexamethylene diamine, undecamethylene diamine, and dodecamethylene diamine. Examples of the dicarboxylic acid include dicarboxylic acids such as adipic acid, suberic acid, sebacic acid, and dodecanedioic acid.

  Examples of the polyamide resin (A) include polycaproamide (nylon 6), polytetramethylene adipamide (nylon 46), polyhexamethylene adipamide (nylon 66), polycaproamide / polyhexamethylene adipamide Copolymer (nylon 6/66), polyundecamide (nylon 11), polycaproamide / polyundecamide copolymer (nylon 6/11), polydodecamide (nylon 12), polycaproamide / polydodecamide copolymer (nylon 6/12) , Polyhexamethylene sebamide (nylon 610), polyhexamethylene dodecamide (nylon 612), polyundecamethylene adipamide (nylon 116), and mixtures and copolymers thereof. Among these, nylon 6 and nylon 66 are preferable from the viewpoint of excellent heat resistance and easy molding.

  In the present invention, the fibrous clay mineral (B) is contained for the purpose of remarkably improving the bending properties of the polyamide resin (A). The fibrous clay mineral (B) is a fibrous hydrous magnesium silicate mineral. Of these, sepiolite and palygorskite are preferably used in that they are easily dispersed in the polyamide resin and do not impair the fluidity during processing of the resulting polyamide resin composition.

Sepiolite is a natural mineral containing Mg ₈ H ₂ (SiO ₄ O ₁₁ ) · 3H ₂ O as a main component. Palygorskite is a natural mineral containing Mg ₈ Al ₂ Si ₈ O ₂₀ (OH ₂ ) · 8H ₂ O as a main component. In the palygorskite, magnesium may be replaced with iron or aluminum.

The basic structure of the fibrous clay mineral (B) will be described below.
Fibrous clay mineral (B) is a fibrous hydrous magnesium silicate mineral with a three-layer structure with an octahedral magnesium oxide layer as the central layer and a tetrahedral silicate layer on each side. It is what you have. Since this three-layer structure extends along the X-axis direction (fiber length direction), the crystals of the fibrous clay mineral (B) are fibrous, that is, fibrous crystals. In the fibrous clay mineral (B), a plurality of fibrous crystals may agglomerate along the fiber direction.

  In the fibrous clay mineral (B), the tetrahedral silicate layer is inverted and bonded on the Z-axis every several units. Therefore, the octahedral magnesium oxide layer becomes a discontinuous layer and forms zeolite pores in the fiber cross section. Further, the fibrous clay mineral (B) has a large number of silanol groups (Si—OH groups) along the X-axis direction. Therefore, the zeolite pores have a property that a highly polar substance such as water can easily enter.

  Thus, the fibrous clay mineral (B) is porous while being fibrous compared to other clay minerals. Therefore, while being bulky, there is an advantage of excellent dispersibility in the polyamide resin (A). As a result, when it is contained in the resin composition of the present invention, it is possible to effectively improve the bending characteristics with a small amount, and there is an effect that the density is not increased.

  In the present invention, the fibrous reinforcing material (C) is used for the purpose of further reducing the warpage of the polyamide resin (A). That is, the combined use of the fibrous clay mineral (B) and the fibrous reinforcing material (C) can significantly reduce the warpage of the molded product obtained from the resin composition of the present invention.

  The fibrous reinforcing material (C) is, for example, carbon fiber, glass fiber, boron fiber, asbestos fiber, polyvinyl alcohol fiber, polyester fiber, acrylic fiber, wholly aromatic polyamide fiber, polybenzoxazole fiber, polytetrafluoroethylene fiber, Examples include kenaf fiber, bamboo fiber, hemp fiber, bagasse fiber, high-strength polyethylene fiber, alumina fiber, silicon carbide fiber, potassium titanate fiber, brass fiber, stainless steel fiber, steel fiber, ceramic fiber, and basalt fiber. These fibrous reinforcing materials (C) may be used alone or in combination of two or more. Of these, glass fibers and carbon fibers are preferably used because of their performance and availability.

  The average fiber length in the resin composition of the fibrous reinforcing material (C) is preferably 100 to 2000 μm, and more preferably 200 to 800 μm. If it is less than 200 μm, the effect of reducing warpage may be reduced. On the other hand, when it exceeds 2000 μm, the operability may be deteriorated such that the fluidity of the resulting resin composition is lowered.

  In order to control the average fiber length in the resin composition of the fibrous reinforcing material (C) within the above range, the resin composition containing the polyamide resin (A) and the fibrous clay mineral (B) is used. When the fibrous reinforcing material (C) is added and melt-kneaded, the melt-kneading conditions can be changed as appropriate. For example, the average fiber length of the fibrous reinforcing material (C) can be controlled by changing the screw configuration of the twin screw extruder or changing the charging position of the fibrous reinforcing material (C). More specifically, if the side feeder is used from the middle of the twin-screw extruder after the melt kneading, the average fiber length of the fibrous reinforcing material (C) can be easily set within a preferable range. Furthermore, compared with the case where the fibrous reinforcing material (C) is introduced from the middle stream of the twin-screw extruder, the average fiber length of the fibrous reinforcing material (C) can be increased by feeding from the downstream side. Moreover, when shortening the average fiber length of the fibrous reinforcing material (C), a method of adopting a screw configuration in which a disk that increases the degree of kneading, such as a kneading disk, is used.

  The average fiber diameter of the fibrous reinforcing material (C) is preferably 5 to 20 μm, and more preferably 10 to 13 μm. If it is less than 5 μm, it may be difficult to obtain a resin composition, and the reinforcing effect may be reduced. On the other hand, when it exceeds 20 μm, the toughness of the glass fiber is lowered, and the resulting resin composition may become brittle.

  The cross section of the fibrous reinforcing material (C) may be a general round shape, a rectangle, or any other irregular cross section. Among these, from the viewpoint of reducing warpage in the molded product obtained from the resin composition of the present invention, the major axis is in the range of 10 to 50 μm, the minor axis is in the range of 5 to 20 μm, and the ratio of major axis / minor axis Is preferably a flat cross-sectional shape of 1.5 to 10.

  When glass fiber or carbon fiber is used as the fibrous reinforcing material (C), the adhesion between the polyamide resin (A) and the fibrous reinforcing material (C) is improved, and the warp of the resulting resin composition is further reduced. Therefore, it is preferable that the glass fiber and the carbon fiber are surface-treated with a silane coupling agent.

  Moreover, the silane coupling agent may be used as a sizing agent for bundling glass fibers or carbon fibers. When glass fibers or carbon fibers are bundled, the number of filaments is usually preferably about 50 to 30,000 filaments.

  Examples of the silane coupling agent include a vinyl silane silane coupling agent, an acrylic silane silane coupling agent, an epoxy silane silane coupling agent, and an amino silane silane coupling agent. An aminosilane-based coupling agent is particularly preferable in that it is easy to obtain an adhesion effect with the reinforcing material (C).

  The non-fibrous clay mineral (D) is included in the resin composition of the present invention together with the fibrous reinforcing material (C), thereby expressing the effect of reducing the warpage of the molded product obtained from the resin composition. There are advantages. Examples of the non-fibrous clay mineral (D) include mica, talc, kaolin, and flat glass fiber powder. Of these, talc is particularly preferably used from the viewpoint of reducing warpage, shape, and availability.

  The shape of the non-fibrous clay mineral (D) is preferably a plate shape from the viewpoint of reducing warpage in the molded product obtained from the resin composition of the present invention.

  The average thickness of the non-fibrous clay mineral (D) is preferably 0.001 to 20 μm, and more preferably 0.005 to 1 μm. What is less than 0.001 μm may be difficult to obtain. On the other hand, when it exceeds 20 μm, not only the warp reduction effect in the molded product obtained from the resin composition of the present invention is lowered, but the resulting resin composition may become brittle.

  The length of the short side and the long side of the non-fibrous clay mineral (D) is preferably 0.1 to 100 μm, and more preferably 1 to 50 μm. If it is less than 0.1 μm, the effect of reducing warpage may be reduced in a molded product obtained from the resin composition of the present invention. On the other hand, if it exceeds 100 μm, the resulting resin composition may become brittle.

  The aspect ratio of the non-fibrous clay mineral (D) is preferably less than 5, and more preferably less than 3. When it is 5 or more, not only the warpage reduction effect is lowered in the molded product obtained from the resin composition of the present invention, but also the warpage may be increased.

In the polyamide resin composition of the present invention, the content ratios of the polyamide resin (A), the fibrous clay mineral (B), the fibrous reinforcing material (C), and the non-fibrous clay mineral (D) are as follows: It is necessary to satisfy the formulas (I), (II) and (III) simultaneously.
(A) / [(B) + (C) + (D)] = 40/60 to 90/10 (I)
(B) / [(C) + (D)] = 8/92 to 75/25 (II)
(C) / (D) = 1/1 to 50/1 (III)

  Furthermore, it is necessary that it is 0.1-10 mass parts with respect to 100 mass parts of polyamide resin compositions from which the content rate of (D) is obtained.

  In the above formula (I), (A) / [(B) + (C) + (D)] is preferably 45/55 to 85/15, and preferably 50/50 to 80/20. More preferred. In the above formula (I), if the content ratio of (A) is less than 40% by mass, the toughness of the resulting resin composition is extremely lowered, so that the bending of the molded body obtained from the polyamide resin composition of the present invention Strength decreases. On the other hand, if the content ratio of (A) exceeds 90% by mass, the contents of the fibrous clay mineral (B), the fibrous reinforcing material (C) and the non-fibrous clay mineral (D) are too small. The effect (namely, the improvement effect of a bending characteristic, and the reduction effect of a curvature) show | played by containing these components falls.

  In the above formula (II), (B) / [(C) + (D)] is preferably 10/90 to 70/30, and more preferably 15/85 to 65/35. In the above formula (II), if the content ratio of (B) is less than 8% by mass, the resulting molded article is poor in the effect of containing (B) and does not exhibit the effect of improving the bending properties. On the other hand, when the content ratio of (B) exceeds 75% by mass, the toughness of the obtained resin composition is extremely lowered, so that not only the resulting molded body becomes brittle but also the density increases excessively. The lightness is lost. Or since it becomes difficult in the below-mentioned process (ii) at the time of obtaining a resin composition, it becomes difficult to obtain a polyamide resin composition.

  In the above formula (III), (C) / (D) is preferably 3/1 to 48/1, more preferably 5/1 to 46/1. When the content ratio of (C) is less than 1 times the content ratio of (D), the warp reduction effect is poor. On the other hand, when the content ratio of (C) exceeds 50 times the content ratio of (D), the density increases excessively and the specific strength decreases.

  The content of (D) is preferably 0.2 to 8 parts by mass and more preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the obtained resin composition. When the content of (D) is less than 0.1 parts by mass, the effect of reducing warpage becomes poor. On the other hand, when the content of (D) exceeds 10 parts by mass, the molded product obtained by the poor toughness of the polyamide resin composition becomes inferior in specific strength.

  In the polyamide resin composition of the present invention, as long as the effects of the present invention are not impaired, a heat stabilizer, an antioxidant, a pigment, an anti-coloring agent, a weathering agent, a flame retardant, a plasticizer, and a crystal nucleus are provided as necessary. Various additives such as an agent and a release agent may be contained.

The method for producing the polyamide resin composition of the present invention will be described below.
The 1st manufacturing method of the polyamide resin composition of this invention includes the following process (i)-(iii).
(I) A step of melting the monomer constituting the polyamide resin (A) and the acid (E) at a temperature equal to or higher than the melting point of the monomer and further mixing the fibrous clay mineral (B) to obtain a mixture.
(Ii) Resin containing polyamide resin (A) and fibrous clay mineral (B) by subjecting the mixture obtained in step (i) to melt polymerization and polymerizing monomers constituting polyamide resin (A) Obtaining a composition;
(Iii) After step (ii), the fibrous reinforcing material (C) and the non-fibrous clay mineral (D) are added to the resin composition containing the polyamide resin (A) and the fibrous clay mineral (B). In addition, a step of melt kneading.

  That is, in the first production method, the monomer constituting the polyamide resin (A) is brought into a molten state, and the fibrous clay mineral (B) is mixed with the molten monomer by means such as stirring to obtain a mixture. . Then, the polyamide resin composition of the present invention is obtained by subjecting the obtained mixture to melt polymerization and then melt-kneading the fibrous reinforcing material (C) and the non-fibrous clay mineral (D).

First, process (i) is demonstrated below.
Step (i) is a step in which the monomer constituting the polyamide resin (A) is heated and melted together with an acid to form a solution, and the fibrous clay mineral (B) is added and mixed by means such as stirring. Although it does not specifically limit as this stirring method, In order to make it melt-mix efficiently, the method of heating and stirring, etc. are mentioned. Further, in the stirring method, the shape and the rotational speed of the stirring blade are not particularly limited.

  The temperature in step (i) needs to be a temperature equal to or higher than the melting point of the monomer constituting the polyamide resin (A). For example, when ε-caprolactam is used as the monomer constituting the polyamide resin (A), it is necessary to melt at a heating temperature of 69 ° C. or higher. When an equimolar salt of adipic acid and hexamethylenediamine is used, it is necessary to melt at a heating temperature of 202 ° C. or higher.

  An acid (E) is an acid whose pKa (25 degreeC, the value in water) is 6 or less, for example. Specific examples include phosphoric acid, phosphorous acid, hydrochloric acid, sulfuric acid, and nitric acid. The amount of acid (E) used is not particularly limited, but from the viewpoint of the polymerization rate and the molecular weight of the resulting polyamide, 0.01 to 1 mass with respect to 100 parts by mass of the monomer constituting the polyamide resin (A). It is preferable that it is about a part.

Next, process (ii) is demonstrated.
In the step (ii), the mixture obtained in the step (i) is subjected to melt polymerization to polymerize the monomers constituting the polyamide resin (A), and the polyamide resin (A) and the fibrous clay mineral (B) are obtained. It is a process of obtaining the resin composition containing.

  The polymerization temperature in step (ii) is preferably 210 to 300 ° C. If the polymerization temperature is less than 210 ° C., it may be difficult to increase the degree of polymerization or the dispersibility of the fibrous clay mineral (B) may be reduced. On the other hand, when the polymerization temperature exceeds 300 ° C., the polyamide resin (A) may be decomposed and yellowed.

  In the first production method, a step of removing unreacted monomers and oligomers may be provided after step (ii).

Next, process (iii) is demonstrated.
In the step (iii), the fibrous reinforcing material (C) and the non-fibrous clay mineral (for the resin composition containing the polyamide resin (A) and the fibrous clay mineral (B) obtained in the step (ii) D) is a step of melt-kneading.

  In the step (iii), for example, kneading can be performed using a twin-screw kneading extruder or the like. The kneading conditions are not particularly limited. For example, from the viewpoint of suppressing plasticization and deterioration of the obtained resin composition, it is preferable to set the melting temperature to about 240 to 290 ° C. and the screw rotation speed to about 150 to 400 rpm.

  In step (iii), the resin composition containing the polyamide resin (A) and fibrous clay mineral (B) obtained in step (ii) is supplied from the main hopper, and the fibrous reinforcing material (C) Fibrous clay mineral (D) can be supplied from the side feeder.

The 2nd manufacturing method of the polyamide resin composition of this invention includes the following processes (iv).
Step (iv): A step of melt-kneading the polyamide resin (A), the fibrous clay mineral (B), the fibrous reinforcing material (C), and the non-fibrous clay mineral (D).

  That is, in the second production method of the polyamide resin composition of the present invention, the fibrous clay mineral (B) is melt-kneaded with the polyamide resin (A), and then the fibrous reinforcing material (C) and the non-fibrous clay. Mineral (D) may be melt-kneaded. Alternatively, the polyamide resin (A), the fibrous clay mineral (B), the fibrous reinforcing material (C), and the non-fibrous clay mineral (D) may be charged together and melt-kneaded.

  For the melt kneading in the step (iv), a twin-screw kneading extruder or the like can be used. The kneading conditions are not particularly limited. For example, from the viewpoint of suppressing plasticization and deterioration of the obtained resin composition, it is preferable to set the melting temperature to about 240 to 290 ° C. and the screw rotation speed to about 150 to 400 rpm.

  In the first and second production methods of the present invention, when the polyamide resin composition of the present invention is finally obtained, in the resin composition, the polyamide resin (A) and the fibrous clay mineral (B) It is necessary that the contents of the fibrous reinforcing material (C) and the non-fibrous clay mineral (D) are in the range of the above formulas (I) to (III).

  In the 1st and 2nd manufacturing method of this invention, in the range which does not impair an effect to this invention, the process of mix | blending another polymer and an additive may be included as needed. The blending of these other polymers and additives is performed at an arbitrary stage.

  The molded body of the present invention can be obtained by subjecting the polyamide resin composition obtained in the present invention to a normal molding method. For example, it can be set as a molded object using hot melt molding methods, such as injection molding, extrusion molding, blow molding, and sintering molding. Moreover, it can also be set as a thin film by melt | dissolving the polyamide resin composition of this invention in an organic solvent solution, and attaching | subjecting to a casting method.

  In the polyamide resin composition of the present invention, the fibrous reinforcing material (C) and the non-fibrous clay mineral (D) are used in combination. Therefore, compared with a polyamide resin composition containing a fiber reinforcing material such as a conventional glass fiber or carbon fiber alone, it is excellent in lightness and bending properties, and warpage when formed into a molded body is reduced. . For this reason, the molded article of the present invention is not only used for general goods and household goods in which a thick molded article is used, but is thin (for example, the thickness when the molded article is 2 mm or less) and has a dimensional accuracy. It is particularly suitably used in required applications (for example, automotive parts and electrical / electronic parts applications).

  In general, if the molded body is thick, the occurrence of warpage tends to be reduced, and if the molded body is thin, the occurrence of warpage tends to be significant. The resin composition of the present invention contains a fibrous reinforcing material (C) and a non-fibrous clay mineral (D) simultaneously as a reinforcing material for the polyamide resin. Therefore, even if it is a case where it is set as a thin molded object, it becomes possible to suppress the expression of curvature notably.

  Examples of parts used in applications that are thin and require dimensional accuracy include parts used around automobile transmissions and around engines.

  Specifically, as parts around the transmission of a car, a base plate used for a pedestal such as a shift lever and a gear box, and as parts around the engine, a cylinder head cover, an engine mount, an air intake manifold, a throttle body, an air intake pipe, a radiator Parts such as tank, radiator support, water pump renlet, water pump outlet, thermostat housing, cooling fan, fan shroud, oil pan, oil filter housing, oil filter cap, oil level gauge, timing belt cover, engine cover, etc. .

  As electric / electronic parts, personal computers, copiers, scanners and other multifunction devices, OA equipment represented by FAX, mobile phones, palmtop computers, e-books, mobile devices such as electronic dictionaries, liquid crystal televisions, plasma televisions, organic Examples include housings such as various displays such as EL, and housing materials.

  Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not limited to the following examples.

The raw materials used in Examples and Comparative Examples are shown below.
(1) Monomer constituting polyamide resin, or polyamide resin (A-1): ε-caprolactam (manufactured by Ube Industries, melting point: 69 ° C.)
(A-2-1): 1,10-decanediamine (A-2-2): terephthalic acid (A-3): Polyamide 66 (trade name “E2000” manufactured by Unitika Ltd.)

(2) Fibrous clay mineral (B-1): Sepiolite (manufactured by TOLSA, trade name “PANGEL HV”)
・ (B-2): Palygorskite (made by Showa KDE, trade name “POLEISY”)

(3) Fibrous reinforcement (C-1): Glass fiber (trade name “MAFT692” manufactured by Owens Corning) (glass fiber having an average fiber diameter of 13 μm and a round cross section)
(C-2): Glass fiber (manufactured by Nitto Boseki Co., Ltd., trade name “CSG3PA820S”) (flat glass fiber having a flat cross section with a major axis of 28 μm, a minor axis of 7 μm, and a major axis to minor axis ratio of 4.0)
(C-3): Carbon fiber (manufactured by Mitsubishi Rayon Co., Ltd., trade name “TR06NEB4J”) (PAN-based carbon fiber having an average fiber diameter of 7 μm and a round cross section)
(C-4): Stainless steel fiber (manufactured by Nippon Seisen Co., Ltd., trade name “Naslon SUS304”), average fiber diameter 8 μm)

(4) Non-fibrous clay mineral (D-1): Talc (made by Nippon Talc Co., Ltd., trade name “K-1”) (average particle size 8 μm)
-(D-2): Mica (Kuraray Co., Ltd., trade name “Clarite Mica 300D”) (average particle size 40 μm, aspect ratio 35)

(5) Acid / phosphorous acid (Nacalai Tesque)

The evaluation methods used in the examples and comparative examples are shown below.
2. Test method (1) Ash content About 5 g of pellets were put in a crucible and weighed, then incinerated at 400 ° C. for 2 hours and further at 600 ° C. for 3 hours, and sufficiently cooled to room temperature while suppressing moisture absorption in a desiccator. Thereafter, the residue in the crucible was calculated as the inorganic ash (mass%) by the following formula.
Ash content (mass%) = 100 × {mass of material after incineration treatment (g)} / {mass of sample before incineration treatment (g)}

(2) Average fiber length of fibrous reinforcing material in resin composition Length of residue after placing test piece (size: 10 mm × 10 mm × 3 mm) in a magnetic crucible and incineration in an electric furnace maintained at 500 ° C. for 15 hours The thickness was measured with a digital microscope (“VHX-500” manufactured by KEYENCE Corporation, magnification 20 times). The measurement was performed on 200 residues, and the average value thereof was defined as the average fiber length.

(3) Density A 10 mm × 10 mm × 4 mm size section was cut out from a test piece having a length of 100 mm, a width of 10 mm, and a thickness of 4 mm obtained by injection molding, and the density (g / cm ³ ) was measured according to ISO1183.

(4) Bending strength The bending strength (MPa) was measured according to ISO178 about the test piece of length 100mm, width 10mm, and thickness 4mm obtained by injection molding.

(5) Specific strength The specific strength was calculated by the following formula from the measured values of the density and bending strength obtained in (1) and (2) above.
Specific strength (kN · m / kg) = [bending strength (MPa)] / [density (g / cm ³ )]

  The specific strength varies depending on the content of the fibrous clay mineral (B), the fibrous reinforcing material (C), and the non-fibrous clay mineral (D), and the density and bending characteristics of the obtained polyamide resin composition differ. In this case, by calculating the bending strength per unit density, it is an index for making it easier to compare the superiority and inferiority of the reinforcing effect. That is, a high specific strength value indicates that the molded product has a low bending density and a high bending strength. In the present invention, a material having a specific strength of 150 kN · m / kg or more can be practically used.

(6) Bending strain (toughness)
Bending strain (%) was measured in accordance with ISO178 for a test piece having a length of 100 mm, a width of 10 mm, and a thickness of 4 mm obtained by injection molding.

(7) Flexural modulus The flexural modulus (GPa) of a test piece having a length of 100 mm, a width of 10 mm, and a thickness of 4 mm obtained by injection molding was measured according to ISO178. In the present invention, those having 5 GPa or more are assumed to be practically usable.

(8) Warpage amount The amount of warpage was measured for a disk-shaped test piece having a diameter of 100 mm and a thickness of 1.6 mm obtained by injection molding.
That is, the test piece taken out from the mold was immediately put into a desiccator, allowed to stand for 24 hours, and then cooled to room temperature (23 ° C.). Subsequently, the test piece was taken out from the desiccator, and the test piece was allowed to stand on a horizontal plate. And in this test piece, the distance from the following four horizontal boards (reference surface 1) was measured, and the amount of curvature was computed from the measured value.

  The four points for measuring the amount of warpage are the four points a, b, c and d in the test piece immediately after removal shown in FIG. That is, as shown in FIG. 1, the position of the side gate of the disk-shaped test piece is a. Then, positions 90 °, 180 °, and 270 ° counterclockwise in the circumferential direction with respect to a are defined as b, c, and d, respectively.

And the test piece which curvature generate | occur | produced is left still so that it may protrude below with respect to a horizontal board, as shown in FIG. With point a as reference point 1, upward displacement (displacement 2 at point c, displacement 3 at point d, displacement 4 at point b) with respect to reference point 1 at each of points b to d was measured. And the amount of curvature was computed by the following formulas.
Warpage (mm) = | (total displacement of point b and point d) / 2− (displacement of point c) / 2 |
In the present invention, it is preferable that the amount of warpage is less than 3 mm.

Production Example 1
100 parts by mass of ε-caprolactam (A-1) and 0.2 parts by mass of phosphorous acid were put in the same container. Then, the mixture was stirred and mixed at a rotational speed of 4000 rpm using a homomixer (trade name “TK homomixer MARKII20” manufactured by Primix Co., Ltd.) while heating at 80 ° C. Thereafter, 1.1 parts by mass of sepiolite (B-1) was added while stirring to prepare a uniform mixture. Next, the obtained mixture was put into an autoclave and polymerized for 1 hour while stirring at an internal temperature of 260 ° C.

  After completion of the polymerization, the resin composition containing the polyamide resin and (B-1) was taken up in a strand form from the bottom valve of the autoclave. Then, the resin composition taken up in a strand shape was cooled and solidified in a hot tub, and cut into pellets with a pelletizer. The obtained pellets were refined with hot water at 95 ° C. for 24 hours to remove unreacted monomers and oligomers. Then, it dried at 80 degreeC for 24 hours, and also vacuum-dried at 80 degreeC for 48 hours, and obtained the fibrous clay mineral compounding polyamide resin (P-1).

Production Examples 2-14
As shown in Table 1, a polyamide resin was obtained in the same manner as in Production Example 1 except that the monomer constituting the polyamide resin and the type and blending amount of the fibrous clay mineral were changed.

Production Example 15
1,10-decanediamine (A-2-1) 50 parts by mass, terephthalic acid (A-2-2) 48 parts by mass, benzoic acid 0.7 parts by mass as a terminal blocking agent, sodium hypophosphite as a polymerization catalyst 0.06 part by mass of monohydrate was put in an autoclave, heated to 100 ° C., stirred with a double helical stirring blade at a rotation speed of 28 rpm, and heated for 1 hour. The molar ratio of the raw material monomers was 1,10-decanediamine: terephthalic acid = 50: 50. The mixture was heated to 230 ° C. while maintaining the rotation speed at 28 rpm, and then heated at 230 ° C. for 3 hours. The formation reaction and crushing of salt and low polymer were performed simultaneously. After releasing the water vapor generated by the reaction, the resulting reaction product was taken out.

  The reaction product obtained as described above was polymerized by heating at 230 ° C. for 5 hours under a normal pressure nitrogen stream in a dryer to obtain a polyamide resin (P-15).

Example 1
89 parts by mass of the fibrous clay mineral-containing polyamide resin (P-1) obtained in Production Example 1 and 1 part by mass of talc (D-1) were dry blended, and a twin-screw extruder (manufactured by Toshiba Machine Co., Ltd., “TEM37BS type”). ) From the root supply port. Further, 10 parts by mass of glass fiber (C-1) was side-fed and extruded under the conditions of a barrel temperature of 250 to 270 ° C., a screw rotation speed of 200 rpm, and a discharge of 15 kg / h while venting. The molten resin discharged from the tip of the extruder was taken up into a strand shape, and the strand was cooled and solidified by passing through a bat filled with cooling water. Then, it cut into the pellet form and obtained the polyamide resin composition.

  The pellet-shaped polyamide resin composition obtained was injection molded at a cylinder temperature of 270 ° C. and a mold temperature of 80 ° C. using an injection molding machine (Toshiba Machine Co., Ltd., “EC-100 type”) to produce a test piece. did. Table 2 shows the results of each test performed on the obtained test pieces.

Examples 2-12, Comparative Examples 1-10
As shown in Table 2, polyamides were obtained in the same manner as in Example 1 except that the types and contents of fibrous clay mineral-containing polyamide resin, fibrous reinforcing material (C) and non-fibrous clay mineral (D) were changed. A resin composition was obtained. The resin composition was injection molded to obtain a test piece. Evaluation was performed about the obtained test piece. The evaluation results are shown in Table 2.

Example 13
79 parts by mass of the polyamide resin (P-10) obtained in Production Example 10, 10 parts by mass of the fibrous clay mineral (B-1) and 1 part by mass of talc (D-1) were dry blended, and a twin-screw extruder (Toshiba) Top feed was made from the root supply port of “TEM37BS type” manufactured by Kikai Co., Ltd. Further, 10 parts by mass of glass fiber (C-1) was side-fed and extruded under the conditions of a barrel temperature of 250 to 270 ° C., a screw rotation speed of 200 rpm, and a discharge of 15 kg / h while venting. The molten resin discharged from the tip of the extruder was taken up into a strand shape, and the strand was cooled and solidified by passing through a bat filled with cooling water. Then, it cut into the pellet form and obtained the polyamide resin composition. This is step (iv). The obtained polyamide resin composition was injection-molded to obtain a test piece. Evaluation was performed about the obtained test piece. The evaluation results are shown in Table 2.

Example 14
A polyamide resin composition was obtained in the same manner as in Example 13 except that the polyamide resin (P-15) obtained in Production Example 15 was used and the barrel temperature was 320 to 340 ° C. The resin composition was injection molded to obtain a test piece. Evaluation was performed about the obtained test piece. The evaluation results are shown in Table 2.

Example 15
A polyamide resin composition was obtained in the same manner as in Example 13 except that the polyamide resin (A-3) was used and the barrel temperature was 270 to 290 ° C. The resin composition was injection molded to obtain a test piece. Evaluation was performed about the obtained test piece. The evaluation results are shown in Table 2.

  The polyamide resin compositions obtained in Examples 1 to 15 were excellent in lightness, bending characteristics, and low warpage while maintaining toughness, which is a characteristic inherent to the polyamide resin.

  In particular, Example 2 in which the blending ratio of (A), (B), (C) and (D) was optimal was remarkably excellent in the balance of specific strength, flexural modulus and low warpage. .

  Furthermore, Examples 7 and 8 using glass fibers and carbon fibers having a flat cross section as the fibrous reinforcing material (C) were further excellent in all performance balances.

  Example 12 in which mica was used as the non-fibrous clay mineral (D) was superior in low warpage as compared with Example 9 in which talc was used.

  Since the polyamide resin composition obtained in Comparative Example 1 did not contain the fibrous reinforcing material (C) and the non-fibrous clay mineral (D), the amount of warpage was large.

  Since the resin composition obtained in Comparative Example 2 did not contain the non-fibrous clay mineral (D), the amount of warpage could not be reduced sufficiently.

  Since the resin composition obtained in Comparative Example 3 did not contain the fibrous reinforcing material (C), the amount of warpage could not be reduced sufficiently.

  Since the resin composition obtained in Comparative Example 4 did not contain the fibrous clay mineral (B), the bending characteristics were insufficiently improved and the specific strength was poor.

  In the resin composition obtained in Comparative Example 5, since the amount of the fibrous clay mineral (B) was too small, the bending characteristics were not improved sufficiently and the specific strength was inferior.

  In Comparative Example 6, since the blending amount of the fibrous clay mineral (B) was excessive, stirring in the step (ii) became difficult. Therefore, subsequent polymerization became insufficient and a resin composition could not be obtained.

  In the resin composition obtained in Comparative Example 7, the amount of the fibrous reinforcing material (C) was too small relative to the non-fibrous clay mineral (D), and thus the amount of warpage was not sufficiently reduced.

  In the resin composition obtained in Comparative Example 8, the amount of the fibrous reinforcing material (C) was excessive with respect to the non-fibrous clay mineral (D). Therefore, the toughness of the molded body obtained from the resin composition was poor, and the specific strength was inferior.

  In the resin composition obtained in Comparative Example 9, since the amount of the non-fibrous clay mineral (D) was too small, the amount of warpage was not sufficiently reduced.

  The resin composition obtained in Comparative Example 10 contained an excessive amount of non-fibrous clay mineral (D). Therefore, the toughness of the polyamide resin composition obtained from the resin composition is poor, and the specific strength of the molded product is poor.

The polyamide resin composition of the present invention is excellent in lightness, bending characteristics and toughness, and warpage when formed into a molded body is remarkably reduced. Therefore, it can be suitably used in various material fields, particularly in the field where warpage is a problem when a thin molded body is used, and is very useful.

Claims (5)

A polyamide resin composition comprising a polyamide resin (A), a fibrous clay mineral (B), a fibrous reinforcing material (C) and a non-fibrous clay mineral (D) as constituent components,
The fibrous clay mineral (B) is sepiolite and / or palygorskite,
The fibrous reinforcing material (C) is glass fiber and / or carbon fiber,
The blending ratio of the (A), (B), (C) and (D) satisfies the following formulas (I), (II) and (III) at the same time in terms of mass ratio,
The polyamide resin composition, wherein the content of (D) is 0.1 to 10 parts by mass with respect to 100 parts by mass of the polyamide resin composition obtained.
(A) / [(B) + (C) + (D)] = 40/60 to 90/10 (I)
(B) / [(C) + (D)] = 8/92 to 75/25 (II)
(C) / (D) = 1/1 to 50/1 (III) The molded object formed by shape | molding the polyamide resin composition of Claim 1 . Thickness is 3 mm or less, The molded object of Claim 2 characterized by the above-mentioned. A method for producing a polyamide resin composition according to claim 1 , comprising the following (i) to (iii):
(I) A step of melting the monomer constituting the polyamide resin (A) and the acid (E) at a temperature equal to or higher than the melting point of the monomer and further mixing the fibrous clay mineral (B) to obtain a mixture.
(Ii) Resin containing polyamide resin (A) and fibrous clay mineral (B) by subjecting the mixture obtained in step (i) to melt polymerization and polymerizing monomers constituting polyamide resin (A) Obtaining a composition;
(Iii) After step (ii), the fibrous reinforcing material (C) and the non-fibrous clay mineral (D) are added to the resin composition containing the polyamide resin (A) and the fibrous clay mineral (B). In addition, a step of melt kneading. A method for producing a polyamide resin composition according to claim 1, comprising the following step (iv).
Step (iv): A step of melt-kneading the polyamide resin (A), the fibrous clay mineral (B), the fibrous reinforcing material (C), and the non-fibrous clay mineral (D).

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