WO2011122300A1

WO2011122300A1 - Polyamide resin composition, method for producing said polyamide resin composition and molded article obtained using said polyamide resin composition

Info

Publication number: WO2011122300A1
Application number: PCT/JP2011/055724
Authority: WO
Inventors: 弘文迎
Original assignee: ユニチカ株式会社
Priority date: 2010-03-31
Filing date: 2011-03-11
Publication date: 2011-10-06
Also published as: TW201141925A; JP5730284B2; CN102712809A; JPWO2011122300A1; CN102712809B

Abstract

Disclosed is a polyamide resin composition containing 100 parts by mass of a polyamide resin, 0.5 - 20 parts by mass hectorite, 15 - 200 parts by mass of a fibrous reinforcing material and 0.01 - 3 parts by mass of a silane coupling agent. The polyamide resin composition is characterized by the size of the hectorite being an average thickness of 1 - 10 nm and an average length on the short side of 25 - 100 nm, and the proportion of the average length on the long side and the average length on the short side being average length on long side/average length on short side = 1.5 - 5. The polyamide resin composition is further characterized by the average distance between particles of the hectorite therein being 10 - 200 nm.

Description

Polyamide resin composition, method for producing the polyamide resin composition, and molded article using the polyamide resin composition

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

Conventionally, for the purpose of improving the strength and rigidity of a polyamide resin, a reinforced polyamide resin has been obtained by blending an inorganic filler. Among these, for the purpose of imparting strength and rigidity to the polyamide resin composition, the polyamide resin composition is reinforced by containing a fibrous reinforcing material. However, in general, the density of the fibrous reinforcing material is larger than that of the polyamide resin. Therefore, in order to improve the tensile strength and the flexural modulus (rigidity), the density increases as the amount of the fibrous reinforcing material used in the polyamide resin composition is increased. In a field where a light-weight resin is required, it is unsuitable to use a polyamide resin composition having a high density, and therefore there are cases where the use of the polyamide resin composition having an increased density is limited.

On the other hand, a polyamide resin composition having a significantly improved reinforcing efficiency has been developed by dispersing a swellable layered silicate, which is a kind of inorganic filler, at a molecular level in a resin. In this case, even if the amount of the swellable layered silicate used is small, there is an advantage that the rigidity is greatly improved. However, when only the swellable layered silicate is used, there is a problem that the reinforcing effect on the tensile strength is not improved so much.

Regarding such problems, JP2009-35593A discloses a polyamide resin composition containing a layered silicate surface-treated with an aliphatic amine such as octadecylamine for the purpose of improving the tensile strength. . However, JP2009-35593A has a problem in that a process for treating the surface of the layered silicate with an aliphatic amine is necessary, which complicates the process and increases costs. Furthermore, there is a problem that the tensile strength is not sufficiently improved.

Similar to JP2009-35593A, JP2009-35591A includes a polyamide resin composition containing glass fiber, swellable layered silicate, and fine fibrous magnesium silicate for the purpose of improving the tensile strength of the polyamide resin. It is disclosed. However, JP2009-35591A has a problem that the density of the polyamide resin composition increases due to the use of fine fiber magnesium silicate.

In view of the above problems, the present invention inherently has a polyamide resin by using a hectorite, a fibrous reinforcing material, and a silane coupling agent having a specific size and dispersion state in the resin composition. An object of the present invention is to obtain a low-density polyamide resin composition that is remarkably excellent in flexural modulus in addition to the tensile strength being applied. Furthermore, it aims at obtaining the molded object which uses the manufacturing method of this polyamide resin composition, and this polyamide resin composition.

As a result of intensive studies to solve such problems, the present inventor uses hectorite, a fibrous reinforcing material, and a silane coupling agent in which the size and dispersion state in the resin composition are in a specific range. Thus, the present inventors have found that a polyamide resin composition having a remarkably excellent tensile strength and flexural modulus can be obtained without increasing the density.
That is, the gist of the present invention is as follows.
(1) A polyamide resin composition containing 100 parts by weight of a polyamide resin, 0.5 to 20 parts by weight of hectorite, 15 to 200 parts by weight of a fibrous reinforcing material, and 0.01 to 3 parts by weight of a silane coupling agent. The hectorite has an average thickness of 1 to 10 nm and an average length of the short side of 25 to 100 nm, and the average length ratio of the long side to the average length of the short side is the average length / short length of the long side. An average length of sides = 1.5 to 5, and an average interparticle distance in the polyamide resin composition of hectorite is 10 to 200 nm.
(2) A method for producing a polyamide resin composition comprising the following steps (i), (ii) and (iii) in this order in producing the polyamide resin composition of (1).
Step (i): Mixing hectorite while stirring the monomer constituting the polyamide resin, the compound having an amino group and the inorganic acid at a temperature equal to or higher than the melting point of the monomer constituting the polyamide resin, and further adding water. In addition, a step of obtaining a preparation liquid by stirring at a rotational speed of 100 to 5000 rpm (ii): a step of obtaining a resin composition containing a polyamide resin and hectorite by polymerizing the preparation liquid obtained in step (i) (Iii): Step (3) in step (i) in which the resin composition containing the polyamide resin and hectorite obtained in step (ii) is melted to knead the fibrous reinforcing material and the silane coupling agent. The method for producing a polyamide resin composition according to (2), wherein mixing is performed so that the rotational viscosity of the adjustment liquid measured with a B-type viscometer is 1 to 400 Pa · s.
(4) A method for producing a polyamide resin composition comprising the following step (iv) when producing the polyamide resin composition of (1).
Step (iv): A molded product obtained by molding the polyamide resin composition in the step (5) (1) in which a polyamide resin is melt-kneaded with hectorite, a fibrous reinforcing material and a silane coupling agent.

According to the present invention, the combined use of hectorite, a fibrous reinforcing material, and a silane coupling agent in which the size and dispersion state in the resin composition are in a specific range allows the polyamide resin to be pulled without increasing the density. It is possible to obtain a polyamide resin composition that is remarkably excellent in strength and flexural modulus. Furthermore, the manufacturing method of this polyamide resin composition and the molded object using this polyamide resin composition can be obtained. Such a polyamide resin composition can be suitably used in the material field requiring high mechanical properties, and has a very high industrial utility value.

It is the image of the layer structure of the hectorite used for this invention image | photographed with the transmission electron microscope (TEM). It is the image of the secondary particle which the layer structure of the hectorite used for this invention aggregated image | photographed with the scanning electron microscope (SEM).

Hereinafter, the present invention will be described in detail.

The polyamide resin composition of the present invention contains a polyamide resin, hectorite having a specific size and dispersion state in the resin composition, a fibrous reinforcing material, and a silane coupling agent.

The polyamide resin in the present invention is a polymer having an amide bond in the main chain, the main raw material of which is aminocarboxylic acid, lactam , diamine and dicarboxylic acid, or a pair of diamine and dicarboxylic acid salts. Specific examples of the raw material of the polyamide resin include aminocarboxylic acids such as 6-aminocaproic acid, 11-aminoundecanoic acid and 12-aminododecanoic acid; lactams such as ε-caprolactam, ω-undecanolactam and ω-laurolactam; Examples include diamines such as tetramethylene diamine, hexamethylene diamine, undecamethylene diamine, and dodecamethylene diamine; dicarboxylic acids such as adipic acid, suberic acid, sebacic acid, and dodecanedioic acid.

Preferred examples of such polyamide resins include polycaproamide (nylon 6), polytetramethylene adipamide (nylon 46), polyhexamethylene adipamide (nylon 66), polycaproamide / polyhexamethylene adipa. Mido copolymer (nylon 6/66), polyundecamide (nylon 11), polycaproamide / polyundecamide copolymer (nylon 6/11), polydodecamide (nylon 12), polycaproamide / polydodecanamide 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, nylon 66, and nylon 12 are particularly preferable from the viewpoint that the effect of increasing the tensile strength by hectorite can be remarkably enhanced.

In the present invention, hectorite is used for the purpose of remarkably improving the tensile strength and flexural modulus of the polyamide resin. Hectorite has a structure composed of a negatively charged silicate layer mainly composed of silicate and a cation having ion exchange ability interposed between the layers. The composition of hectorite is generally represented by Na _0.66 (Mg _5.34 Li _0.66 ) Si ₈ O ₂₀ (OH) ₄ .nH ₂ O.

Hectorite is plate-shaped and has a substantially elliptical shape or a substantially rectangular shape. Therefore, compared with the case where only the fiber reinforcing material is used, the tensile strength and the bending elastic modulus can be effectively improved while sufficiently reducing the amount of use. Therefore, even if the tensile strength and the flexural modulus are sufficiently improved, a polyamide resin composition having a sufficiently reduced density can be obtained. Further, when a swellable layered silicate other than hectorite is used, the tensile strength cannot be improved because the size of the swellable layered silicate in the polyamide resin composition does not fall within the range defined in the present invention.

In the present invention, hectorite preferably has a cation exchange capacity of 30 to 100 meq / 100 g or more, and more preferably 55 to 95 meq / 100 g or more. When the cation exchange capacity is less than 30 meq / 100 g, the swelling ability is low, and therefore the polyamide resin composition remains substantially in an uncleavable state. Therefore, the size of hectorite does not fall within the range specified in the present invention. In addition, it cannot be dispersed well in the polyamide resin composition. Therefore, it is not possible to obtain a polyamide resin composition having significantly improved tensile strength and flexural modulus. On the other hand, when the cation exchange capacity exceeds 100 milliequivalents / 100 g, since the cleavage proceeds excessively, the flexural modulus is improved, but there is a tendency to become brittle. As a result, the tensile strength when the fibrous reinforcing material is used together cannot be remarkably improved.

The cation exchange capacity of hectorite is determined in accordance with the bentonite (powder) cation exchange capacity measurement method (JBAS-106-77) according to the standard test method of the Japan Bentonite Industry Association. Specifically, an apparatus in which a leachate container, a leach tube, and a receiver are connected in the vertical direction is used. Then, by immersing the hectorite in 1N aqueous solution of ammonium acetate the pH was adjusted to 7, to replace all of its layers of ion exchange cations NH ^4+, obtain NH ⁴⁺ type hectorite. Thereafter, the NH ⁴⁺ type hectorite is thoroughly washed with water and ethyl alcohol, and then immersed in a 10% by mass aqueous potassium chloride solution to replace NH ⁴⁺ in the hectorite with K ⁺ . . Subsequently, the cation exchange capacity of hectorite, which is a raw material, can be determined by neutralizing titrating NH ⁴⁺ leached with the above ion exchange reaction using a 0.1N aqueous sodium hydroxide solution.

In order to achieve the effect of the present invention, it is essential to define the size of hectorite in the polyamide resin composition within a predetermined range. By setting the size of hectorite in the polyamide resin composition within a specific range, various physical properties of the polyamide resin composition, particularly tensile strength and flexural modulus can be greatly improved.

In the present invention, the shape of hectorite is plate-like as described above, and is oval or substantially rectangular. By setting it as such a shape, when the polyamide resin composition of this invention is used as a molded object, the orientation direction of the hectorite disperse | distributed in a molded object turns into a long piece direction. As a result, it is possible to increase the tensile strength in the long piece direction. When the shape of the hectorite is plate-like and is oval or substantially rectangular, the size of the hectorite in the polyamide resin composition is as follows.

Hectorite is a swellable layered silicate, that is, has a structure in which a plurality of layer structures are gathered at random and overlapped. The average thickness (that is, the total average thickness of the overlapping portions in the layer structure) needs to be 1 to 10 nm, and preferably 1.5 to 8 nm. That the average thickness of hectorite exceeds 10 nm indicates that cleavage is insufficient. Therefore, the size of hectorite does not fall within the range specified in the present invention. In addition, since the hectorite cannot be dispersed well in the polyamide resin composition, sufficient rigidity and heat resistance are not exhibited. On the other hand, when the thickness is less than 1 nm, there is a problem that various physical properties, in particular, the reinforcing effect of tensile strength and flexural modulus cannot be obtained sufficiently.

The shape of hectorite will be described below with reference to FIGS. 1 and 2. FIG. 1 is an image of the layer structure of hectorite used in the present invention, taken by a transmission electron microscope (TEM). FIG. 2 is an image of secondary particles in which the layer structure of hectorite used in the present invention is aggregated, which is taken by a scanning electron microscope (SEM). As shown in FIG. 2, the secondary particles of hectorite before being dispersed in the resin composition are those in which the layer structure shown in FIG. On the other hand, in the swellable layered silicate other than hectorite, the layer structure is regularly stacked to form secondary particles. Therefore, the shape of the swellable layered silicate other than hectorite is significantly different from the shape of hectorite. As a result, the size of the swellable layered silicate in the polyamide resin composition does not fall within the range specified in the present invention.

As for the size of hectorite in the polyamide resin composition, the average length of the short side is required to be 25 to 100 nm, and preferably 30 to 95 nm. When the average length of the short side is less than 25 nm, sufficient rigidity and heat resistance are not exhibited. On the other hand, when the average length of the short side exceeds 100 nm, rigidity and heat resistance are sufficiently developed, but tensile strength is not sufficiently developed.

The size of hectorite in the polyamide resin composition is such that the average length of its long side is 38.
It is preferably from ˜500 nm, more preferably from 45 to 400 nm. If the long side average length is less than 38 nm, the tensile strength may not be sufficiently improved. On the other hand, if the average length of the long side exceeds 500 nm, the tensile strength increases, but the toughness may decrease on the other hand.

In the present invention, it is necessary that the ratio of the average length of the long side to the average length of the short side is (average length of long side) / (average length of short side) = 1.5-5. More preferably 1.6 to 4.5. If the length ratio between the long side and the short side is out of the above range, the tensile strength is not improved. On the other hand, when the length ratio of the long side and the short side is out of the above range, there is a problem that dispersibility in the polyamide resin is lowered.

In the present invention, the initial size of hectorite is not particularly limited. Here, the initial size is the size of hectorite before being contained in the polyamide resin composition. That is, it is the size of secondary particles formed by a plurality of hectorite layer units gathering and overlapping, and is different from the size of hectorite contained in the polyamide resin composition. When hectorite is contained in the polyamide resin composition, cleavage proceeds from the state of secondary particles to a layer unit consisting of one or several hectorites, and dispersion in the polyamide resin composition proceeds. Therefore, the size of hectorite contained in the polyamide resin composition is different from the initial size. In order to set the size of hectorite in the polyamide resin composition to the size prescribed in the present invention, the initial size (secondary particle size) is preferably used with an average particle size of 1 to 50 μm, and is preferably 5 to 45 μm. More preferably, the thickness is 10 to 40 μm. In addition, as a method for adjusting the initial size of hectorite, pulverization with a known apparatus such as a jet mill may be mentioned.

In order to achieve the effect of the present invention, it is necessary that the particle size of hectorite in the resin composition is in the above specific range. In addition, how to obtain | require average thickness and average length is explained in full detail in an Example.

The hectorite needs to be well dispersed in the polyamide resin composition for the purpose of improving the tensile strength in the resin flow direction, particularly in a molded product obtained by injection molding. In the present invention, the average inter-particle distance in the resin composition is used as an indicator of good dispersion in the polyamide resin composition. That is, in the present invention, the average interparticle distance needs to be 10 to 200 nm, and more preferably 15 to 180 nm. There exists a problem that toughness falls that the distance between average particles is less than 10 nm. On the other hand, when it exceeds 200 nm, there exists a problem that tensile strength and a bending elastic modulus cannot be expressed with sufficient balance.

In the present invention, the interparticle distance refers to a linear distance connecting the centers of adjacent hectorites of the observed hectorite by observing the inside of the resin composition with a transmission electron microscope. The measuring method will be described in detail later in the evaluation method.

The hectorite content is required to be 0.5 to 20 parts by mass, preferably 1 to 18 parts by mass with respect to 100 parts by mass of the polyamide resin. When the content is less than 0.5 parts by mass, there is a problem that the effect of containing hectorite is not sufficiently exhibited and the tensile strength is lowered. On the other hand, when the amount exceeds 20 parts by mass, the dispersibility in the resin composition is lowered, so that the tensile strength is lowered. In addition, there is a problem that the operability during melt kneading is lowered. Of the hectorite content of 0.5 to 20 parts by mass with respect to 100 parts by mass of the polyamide resin, the smaller the hectorite content, the higher the dispersion efficiency in the polyamide resin composition, so that cleavage proceeds. Tend.

The hectorite may be organically treated for the purpose of improving the adhesion with the polyamide resin when blended during melt kneading. Examples of the organic treatment method include a method of inserting an amine or amino acid between layers.

In addition, a swellable layered silicate other than hectorite may be used in combination with hectorite as long as the effects of the present invention are not impaired. Examples of swellable layered silicates other than hectorite include smectites (montmorillonite, beidellite, hectorite, soconite, etc.), vermiculites (vermiculite, etc.), micas (fluorine mica, muscovite, paragonite, phlogopite, lipidoid). Etc.), brittle mica family (margarite, clintnite, anandite, etc.), chlorite family (donbasite, sudoite, kukeite, clinochlore, chamonite, nimite, etc.). The content of the swellable layered silicate other than hectorite is preferably 0.1 to 5 parts by mass, and 0.2 to 3 parts by mass with respect to 100 parts by mass of hectorite, from the viewpoint of not inhibiting the improvement in tensile strength. Is more preferable.

In the present invention, a fibrous reinforcing material is used for the purpose of further improving the tensile strength and flexural modulus of the polyamide resin. That is, the combined use of hectorite and fibrous reinforcing material can significantly improve the tensile strength and the flexural modulus.

Examples of the fibrous reinforcing material include glass fiber, carbon fiber, whisker and the like. Among these, glass fiber is preferable from the viewpoint of the highest effect of improving tensile strength and bending elastic modulus in combination with hectorite.

The glass fiber is not particularly limited, and ordinary fibers are used. The cross section of the glass fiber may be a general round shape, a rectangle, or other irregular cross section. Moreover, the size of glass fiber is not specifically limited.

The carbon fiber is not particularly limited, and a normal one is used. The size and cross-sectional shape of the carbon fiber are not particularly limited.

The content of the fibrous reinforcing material is required to be 5 to 200 parts by mass with respect to 100 parts by mass of the polyamide resin, and preferably 10 to 180 parts by mass. When the content is less than 5 parts by mass, there is a problem that sufficient tensile strength and flexural modulus cannot be obtained. On the other hand, when it exceeds 200 mass parts, there exists a problem that the operativity at the time of melt-kneading falls.

The polyamide resin composition of the present invention must contain a fibrous reinforcing material and a silane coupling agent at the same time. By using the fibrous reinforcing material and the silane coupling agent in combination, there is an advantage that the adhesion between the polyamide resin and the fibrous reinforcing material is improved, and sufficient tensile strength and bending elastic modulus can be obtained. When the silane coupling agent is not contained, the effect of improving the adhesion between the polyamide resin and the fibrous reinforcing material is poor, and thus the bending elastic modulus is improved, but the tensile strength is not sufficiently improved. Moreover, when a coupling agent other than the silane coupling agent is used, not only the tensile strength cannot be improved efficiently, but also the effect of improving the flexural modulus is hindered.

The content of the silane coupling agent needs to be 0.01 to 3 parts by mass, and more preferably 0.02 to 0.9 parts by mass with respect to 100 parts by mass of the polyamide resin. When the content is less than 0.01 parts by mass, the effect of improving the adhesion between the polyamide resin and the fibrous reinforcing material becomes insufficient, and sufficient tensile strength cannot be obtained. On the other hand, when it exceeds 3 parts by mass, not only the effect of improving the adhesion between the polyamide resin and the fibrous reinforcing material is saturated, but also the toughness of the polyamide resin is impaired and sufficient mechanical properties cannot be obtained.

The silane coupling agent used in the present invention is not particularly limited, and vinyl silane silane coupling agent, acrylic silane coupling agent, epoxy silane coupling agent, amino silane coupling agent, isocyanate silane coupling agent. Etc. Of these, an epoxy-based silane coupling agent is preferable from the viewpoint of easily obtaining a sufficient tensile strength improvement effect.

The polyamide resin composition of the present invention has a heat stabilizer, an antioxidant, a pigment, an anti-coloring agent, a weathering agent, a flame retardant, a plasticizer, a crystal nucleating agent, a release agent, etc. May be contained. Examples of the heat stabilizer and the antioxidant include hindered phenols, phosphorus compounds, hindered amines, sulfur compounds, copper compounds, alkali metal halides, and mixtures thereof.

The method for producing the polyamide resin composition of the present invention will be described below. One of the following two methods can be used for the method for producing the polyamide resin composition of the present invention.

The first production method of the polyamide resin composition of the present invention includes the following steps (i) to (iii).
Step (i): Mixing hectorite while stirring the monomer constituting the polyamide resin, the compound having an amino group, and the inorganic acid at a temperature equal to or higher than the melting point of the monomer constituting the polyamide resin while stirring. A step of adding water and stirring at a rotational speed of 100 to 5000 rpm to obtain a preparation liquid (hereinafter sometimes referred to simply as “preparation step”)
Step (ii): A step of polymerizing the preparation liquid obtained in step (i) to obtain a resin composition containing a polyamide resin and hectorite (hereinafter, sometimes simply referred to as “polymerization step”)
Step (iii): The step of melting the resin composition containing the polyamide resin and hectorite obtained in step (ii) and kneading the fibrous reinforcing material and the silane coupling agent (hereinafter simply referred to as “kneading step”) May be called)
That is, the monomer constituting the polyamide resin is set in a molten state, and hectorite is blended in the molten monomer. Thereafter, the polyamide resin composition of the present invention is obtained by polymerizing and melt-kneading the fibrous reinforcing material and the silane coupling agent.

First, the preparation process in the first manufacturing method will be described below.

The preparation step is a step in which the monomer constituting the polyamide resin by stirring is heated and melted together with a compound having an amino group and an inorganic acid to form a solution, and hectorite and water are sequentially added and stirred. The stirring method in the preparation step is not particularly limited as long as the monomer, hectorite, and water constituting the polyamide resin are uniformly mixed, and examples thereof include a melt mixing method while stirring with heating. In that case, the shape and the rotational speed of the stirring blade are not particularly limited.

The temperature of the preparation process needs to be a temperature equal to or higher than the melting point of the monomer constituting the polyamide resin. For example, when ε-caprolactam is used as the monomer constituting the polyamide resin, it is necessary to melt at a heating temperature of 69 ° C. or higher. Moreover, when a molar salt such as adipic acid / hexamethylenediamine is used, it is necessary to melt at a heating temperature of 202 ° C. or higher.

In the preparation step, it is necessary to use a compound having an amino group and an inorganic acid. A compound having an amino group reacts with an inorganic acid to form a quaternary amine. The quaternary amine penetrates between the layers of hectorite in the subsequent polymerization step. As a result, the interlayer can be changed from hydrophilic to hydrophobic, and the dispersibility of hectorite can be promoted.

Examples of the compound having an amino group include aminocarboxylic acids such as 6-aminocaproic acid, 11-aminoundecanoic acid and 12-aminododecanoic acid, decylamine, stearylamine, dodecylamine, octadecylamine, oleylamine, benzylamine, methyldodecylamine, Examples include benzyltrialkylamines such as methyloctadecylamine, dimethyldodecylamine, dimethyloctadecylamine, benzyltrimethylamine, benzyltriethylamine, benzyltributylamine, benzyldimethyldodecylamine, and benzyldimethyloctadecylamine. The compound having an amino group may have a functional group other than the amino group.

An inorganic acid is an acid having a pKa (value at 25 ° C. in water) of 6 or less. Specific examples include phosphoric acid, phosphorous acid, hydrochloric acid, sulfuric acid, and nitric acid. Of these, phosphorous acid is preferred from the viewpoint of easy cleavage of hectorite and low corrosiveness to equipment.

The amount of the compound having an amino group is preferably 2 to 20 parts by mass, more preferably 3 to 10 parts by mass with respect to 100 parts by mass of hectorite. If the amount of the compound having an amino group is less than 2 parts by mass, the hectorite layer cannot be sufficiently hydrophobized, and the dispersibility of hectorite may be lowered. On the other hand, if it exceeds 20 parts by mass, the compound having an amino group may be attached to the end of the polyamide, and the degree of polymerization of the polyamide resin may not increase.

The amount of the inorganic acid used is from the viewpoint of promoting the cleavage of hectorite, and in order to set the (average length of the long side) / (average length of the short side) of the cleaved hectorite to 1.5-10. ,
The amount is preferably 0.3 to 4 parts by mass, more preferably 0.5 to 3 parts by mass with respect to 100 parts by mass of hectorite. If the amount of acid used is less than 0.3 parts by mass, hectorite may not be sufficiently cleaved. On the other hand, when it exceeds 4 mass parts, operativity may fall in a preparation process.

The stirring rotation speed in the adjustment step needs to be 100 to 5000 rpm, and preferably 200 to 4500 rpm. When the rotational speed is less than 100 rpm, the uniformity of the adjustment liquid is lowered. On the other hand, when it exceeds 5000 rpm, it becomes difficult to obtain an appropriate rotational viscosity.

The rotational viscosity of the adjustment liquid in the adjustment step is preferably 1 to 400 Pa · s, more preferably 5 to 350 Pa · s, and particularly preferably 10 to 300 Pa · s. When the rotational viscosity is less than 1 Pa · s, the dispersibility of hectorite is lowered, and the effect of improving the tensile strength becomes insufficient. On the other hand, if it exceeds 400 Pa · s, the rotational viscosity of the adjustment liquid is too high, and it becomes difficult to dispense the adjustment liquid to the polymerization apparatus.

Next, the polymerization step in the first production method will be described below.

The polymerization step is a step of polymerizing the adjustment liquid to obtain a resin composition containing a polyamide resin and hectorite.

Hectorite contains more hydroxyl groups than other swellable layered silicates, so water molecules can easily enter between layers (ie, have high hydrophilicity), and swell easily. In addition, the particle size is small compared to other swellable layered silicates. Therefore, as in the prior art, in the case of using a method for obtaining a polyamide resin composition by stirring the monomer and water constituting the polyamide resin such as caprolactam or aminocarboxylic acid together with hectorite and further subjecting to polymerization. There are the following problems. That is, since the hydrophilicity between the hectorite layers is high, water is rapidly absorbed and the hectorite becomes bulky. For this reason, the rotational viscosity of the polyamide resin composition increases, and uniform stirring becomes difficult. In addition, the handleability of the resulting resin composition deteriorates. Therefore, the amount of hectorite added cannot be increased, and it becomes difficult to significantly improve the tensile strength and flexural modulus of the polyamide resin.

In contrast, in the first production method of the present invention, first, the monomer constituting the polyamide resin, the compound having an amino group, and the inorganic acid are subjected to the preparation step, and then hectorite is added to the polymerization step. It is attached. Therefore, the layer of hectorite is substituted with a quaternary amine formed by a reaction between a compound having an amino group and an inorganic acid, and becomes hydrophobic. Therefore, water molecules do not easily enter between the layers of hectorite, and as a result, they do not easily swell. In addition, when the polyamide resin enters between the layers of hectorite, it is cleaved and uniformly dispersed. As a result, increase in viscosity of the resulting polyamide slurry can be suppressed, and various physical properties of the resin composition containing the polyamide resin and hectorite can be improved in a well-balanced manner in the polymerization step while preventing a decrease in handleability. .

In the first production method, when the polyamide resin composition of the present invention is finally obtained, the hectorite content must be in the above range.

The form of hectorite in the polymerization step is not particularly limited as long as the dispersibility in the monomer constituting the polyamide resin can be improved, but a powder form is preferable because the dispersibility is improved.

The polymerization temperature in the polymerization step is preferably 240 to 280 ° C, and more preferably 245 to 275 ° C. When the polymerization temperature is lower than 240 ° C., there are problems that it is difficult to increase the degree of polymerization and that the dispersibility of hectorite is lowered. On the other hand, when the polymerization temperature exceeds 280 ° C., the polyamide resin may be decomposed and yellowed.

The pressure in the polymerization step is preferably 0.3 to 1.5 MPa, more preferably 0.4 to 1.0 MPa. If the pressure is less than 0.3 MPa, hectorite may not be dispersed well. As a result, the tensile strength and the flexural modulus are not sufficiently expressed. On the other hand, when the pressure exceeds 1.5 MPa, improvement in polymerizability and hectorite dispersibility can be expected, but equipment specifications with high pressure resistance must be provided, which may increase the economic burden.

Next, the kneading process in the first production method will be described. The kneading step is a step of melt-kneading the fibrous reinforcing material and the silane coupling agent into the resin composition containing the polyamide resin and hectorite obtained in the polymerization step.

In the kneading step, for example, kneading can be performed using a twin-screw kneading extruder or the like. The kneading conditions are not particularly limited, but from the viewpoint of plasticizing the resin composition and suppressing deterioration, melt kneading is preferably performed under conditions of a melting temperature of 240 to 290 ° C. and a screw rotation of 150 to 400 rpm.

In the kneading step, the polyamide resin obtained in the polymerization step can be supplied from the main hopper, and the fibrous reinforcing material can be supplied from the side feeder.

In the kneading step, the silane coupling agent can be supplied using any means. The supply method includes a method of supplying the polyamide resin and the silane coupling agent from the main hopper while dry blending, a method of supplying the polyamide resin and the silane coupling agent separately from the polyamide resin, or a method of supplying from the side feeder.

In the first production method, when the polyamide resin composition of the present invention is finally obtained, the content of the fibrous reinforcing material needs to be in the above range. Furthermore, when the polyamide resin composition of the present invention is finally obtained, the content of the silane coupling agent needs to be in the above range.

The second manufacturing method of the polyamide resin composition of the present invention includes the following step (iv).
Step (iv): Step of obtaining a resin composition by melting and kneading hectorite, a fibrous reinforcing material, and a silane coupling agent to a polyamide resin (hereinafter, sometimes simply referred to as “melt kneading step”)
That is, in the second production method of the polyamide resin composition of the present invention, hectorite may be melt-kneaded with the polyamide resin, and then the fibrous reinforcing material and the silane coupling agent may be melt-kneaded. Hectorite, fibrous reinforcing material and silane coupling agent may be charged all at once and melt-kneaded. In order to promote the dispersion of hectorite in the polyamide resin, a method of kneading the fibrous reinforcing material and the silane coupling agent after melt-kneading the polyamide resin and hectorite in advance is preferable.

For the melt-kneading, a twin-screw kneading extruder or the like can be used, and the melting temperature is preferably 240 to 290 ° C. from the viewpoint of plasticizing the resin composition and suppressing deterioration. In addition, in order to suppress breakage of the fibrous reinforcing material, it is preferable to add the fibrous reinforcing material and the silane coupling agent using a side feeder as downstream as possible on the twin-screw kneading extruder.

In the melt-kneading step, the following arbitrary methods may be used to disperse hectorite in the polyamide resin. That is, using a method such as a method of dry blending and supplying a polyamide resin and hectorite from the main hopper, a method of supplying a polyamide resin from the main hopper, and a method of supplying hectorite from the side feeder, etc. Light can be dispersed.

In the second production method, when the polyamide resin composition of the present invention is finally obtained, the hectorite content needs to be in the above range.

The form of hectorite in the melting step is not particularly limited as long as the dispersibility in the monomer constituting the polyamide resin can be improved. A powder form is preferable because it facilitates dispersion.

In this way, by blending hectorite, the effect of sufficiently improving the tensile strength can be obtained.

In the second production method, when the polyamide resin composition of the present invention is finally obtained, the content of the fibrous reinforcing material needs to be in the above range. Furthermore, when the polyamide resin composition of the present invention is finally obtained, the content of the silane coupling agent needs to be in the above range.

The advantages of the second manufacturing method will be described below. Since the first manufacturing method includes a polyamide resin polymerization step (that is, step (ii)), a large facility is required to obtain a target polyamide resin composition. On the other hand, the second production method can obtain the target polyamide resin composition only by melt kneading, and therefore can obtain the polyamide resin composition with relatively simple equipment. However, it is more preferable to use the first production method in terms of hectorite dispersibility and mass productivity.

The first production method and the second production method of the present invention may include a step of blending other polymers and additives as necessary, as long as the effects of the present invention are not impaired. Is possible. The blending of these other polymers and additives is performed at an arbitrary stage.

The molded body of the present invention can be produced 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. Among these, from the viewpoint that the excellent tensile strength and flexural modulus, which are the characteristics of the polyamide resin composition of the present invention, can be most effectively used, it is preferable to form a molded body by injection molding. The molding conditions in this case are not particularly limited, but for example, a resin temperature of 230 to 290 ° C. and a mold temperature of about 80 ° C. are preferable.

Further, the polyamide resin composition of the present invention can be dissolved in an organic solvent solution and subjected to a casting method to form a thin film. In addition, as a molded object, it is preferable that it is a molded object which has a form in which hectorite and a fibrous reinforcement are easy to orientate, since the reinforcement effect of a hectorite and a fibrous reinforcement can be obtained more easily.

The molded article of the present invention can be used for automobile parts, electrical parts, household goods, etc. by taking advantage of its excellent characteristics. In particular, it can be used around automobile transmissions and engines. Specifically, the base plate used for pedestals such as shift levers and gearboxes around the transmission of an automobile, and the cylinder head cover, engine mount, air intake manifold, throttle body, air intake pipe, radiator tank, radiator around the engine It is suitably used for 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 and the like.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples. In addition, the raw material used for the Example and the comparative example is as follows.
(A) Monomer constituting polyamide resin, or polyamide resin (A-1): ε-caprolactam (manufactured by Ube Industries)
(A-2): 12-aminododecanoic acid (manufactured by Ube Industries)
(A-3): Nylon 6 (product name “A1030BRL” manufactured by Unitika Ltd.)
(A-4): Nylon 66 (trade name “CM3001” manufactured by Toray Industries, Inc.)
(B) Hectorite or other swellable layered silicate (B-1): Hectorite (manufactured by Elementis Specialties, trade name “Bentone HC”) [Composition: Na _0.66 (Mg _5.34 Li _{0. 66} ) Si ₈ O ₂₀ (OH) ₄ · nH ₂ O] (cation exchange amount: 90 meq / 100 g)
(B-2): Organically treated hectorite (trade name “Bentone 27” manufactured by Elementis Specialties) (hectorite with benzylmethylalkylammonium inserted between the layers. The carbon number of the alkyl group is 16 to 18). Composition: Na _0.66 (Mg _5.34 Li _0.66 ) Si ₈ O ₂₀ (OH) ₄ .nH ₂ O] (cation exchange amount: 90 meq / 100 g)
(B-3): Swellable fluorinated mica (trade name “ME-100” manufactured by Coop Chemical Co., Ltd.) (cation exchange amount: 110 meq / 100 g)
(B-4): Montmorillonite (Kunipia, trade name “Kunipia F”) (cation exchange amount: 100 meq / 100 g)
(B-5): Organically treated montmorillonite (manufactured by Hojun Co., Ltd., trade name “Esben NX”) (montmorillonite with dimethyloctadecylammonium inserted between the layers) (cation exchange amount: 100 meq / 100 g)
(C) Fibrous reinforcing material (C-1): Glass fiber (glass fiber having a circular cross section having a diameter of 10 μm and a length of 3 mm) (trade name “HP3540” manufactured by PPG)
・ (C-2): Polyacrylonitrile-based (PAN-based) carbon fiber (trade name “HTA-C6-NR” manufactured by Toho Tenax Co., Ltd.)
(D) Silane coupling agent (D-1): 3-glycidoxypropyltrimethoxysilane (trade name “KBM-403” manufactured by Shin-Etsu Chemical Co., Ltd.)
(D-2): 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name “KBM-603”)
Evaluation methods used in Examples and Comparative Examples are as follows.
(1) Tensile strength It measured according to ISO527. In the present invention, a material having a pressure of 180 MPa or more can be practically used.
(2) Flexural modulus Measured according to ISO178.
(3) Average thickness of hectorite or swellable layered silicate in polyamide resin composition From the obtained polyamide resin composition, an ISO test piece was prepared by injection molding. A part of the test piece with a suitable size was taken out from a surface parallel to the flow direction of the resin at the time of molding, and an ultrathin section having a thickness of 70 nm was prepared using a frozen microtome. The ultrathin sections were examined for hectorite or swellable layered silicate in the polyamide resin composition using a transmission electron microscope (trade name “JEM-1230 TEM” manufactured by JEOL Ltd.) (acceleration voltage: 100 kv). That is, from the observed electron micrograph, the thickness of hectorite or swellable layered silicate dispersed in the polyamide resin composition was measured, and the average value was calculated. The number of measurements was 100.
(4) Average short side length and average long side length of hectorite or swellable layered silicate in the polyamide resin composition From the obtained polyamide resin composition, an ISO test piece was prepared by injection molding. From the direction perpendicular to the resin flow direction during molding of the test piece, a part was taken out in an appropriate size, and an ultrathin section having a thickness of 70 nm was prepared using a frozen microtome. The ultrathin sections were examined for hectorite or swellable layered silicate in the polyamide resin composition using a transmission electron microscope (trade name “JEM-1230 TEM” manufactured by JEOL Ltd.) (acceleration voltage: 100 kv). That is, from the observed electron micrograph, the short side length and long side length of hectorite or swellable layered silicate dispersed in the polyamide resin composition were measured, and the average value was calculated. The number of measurements was 100.
(5) Average interparticle distance of hectorite or swellable layered silicate in the polyamide resin composition From the obtained polyamide resin composition, an ISO test piece was prepared by injection molding. From the direction parallel to the flow direction of the resin at the time of molding in the test piece, a part was taken out at an appropriate size, and an ultrathin section having a thickness of 70 nm was prepared using a frozen microtome. The ultrathin sections were analyzed for the state of dispersion of hectorite or swellable layered silicate in the polyamide resin composition using a transmission electron microscope (trade name “JEM-1230 TEM” manufactured by JEOL Ltd.) (acceleration voltage: 100 kv). Examined. That is, from the observed electron micrograph, the distance between particles of hectorite or swellable layered silicate dispersed in the polyamide resin composition was measured, and the average value was calculated. Interparticle distance is the distance measured from the center of hectorite or swellable layered silicate dispersed in the polyamide resin composition to the nearest hectorite or swellable layered silicate center. It is. The number of measurements was 100.
(6) Density According to ISO1183, it measured by the underwater substitution method on 23 degreeC conditions.
(7) Specific elastic modulus The specific elastic modulus was calculated from the bending elastic modulus obtained in (2) above and the density obtained in (6).
Specific modulus = (flexural modulus) / (density)
It shows that the bending elastic modulus per unit weight of a polyamide resin composition or a molded object obtained from it is so high that the numerical value of a specific elastic modulus is large. In the present invention, it is preferable that the specific elastic modulus is large. In the present invention, when less than 50 parts by mass of the fibrous reinforcing material is blended, 5.5 GPa or more can be practically used when the fibrous reinforcing material is blended by 50 mass parts or more. It was supposed to be.

Preparation of Resin Compositions (P-1) to (P-10), (P-17) Consisting of Polyamide Resin and Hectorite or Swellable Layered Silicate ε-Caprolactam or 12-Amino in the proportions shown in Table 1 Dodecanoic acid, pure water, and phosphoric acid were mixed and stirred at 80 ° C. for 30 minutes while heating. So far, it is process (i). Next, as shown in Table 1, the kind and the mixing ratio of hectorite or swellable layered silicate were changed and charged, and an adjustment liquid was obtained with the number of revolutions and the rotational viscosity shown in Table 1. Thereafter, polymerization was performed at 260 ° C. for 1 hour at the pressure shown in Table 1, and then polymerization was performed at 260 ° C. and normal pressure for 1 hour. Up to this point, it is step (ii).

Preparation of resin composition (P-11), (P-12), (P-13) comprising polyamide resin and hectorite or swellable layered silicate Polyamide resin and layered silicate Was kneaded at a melting temperature of 280 ° C. This is step (iv).
Example 1
(P-1) 105 parts by mass, (C-1) 50 parts by mass, and (D-1) 0.1 parts by mass were melt-kneaded. This is step (iii). For the melt-kneading, a twin screw extruder (manufactured by Toshiba Machine Co., Ltd., trade name “TEM37BS”) was used. The temperature of melt kneading was 270 ° C. The obtained polyamide resin composition was subjected to evaluation. The evaluation results are shown in Table 2.

Example 2
(P-1) 105 parts by mass, (C-1) 50 parts by mass, and (D-1) 2 parts by mass were melt-kneaded. This is step (iii). For the melt-kneading, the above twin screw extruder was used. The temperature of melt kneading was 270 ° C. The obtained polyamide resin composition was subjected to evaluation. The evaluation results are shown in Table 2.
Example 3
105 parts by mass of (P-1), 50 parts by mass of (C-1), and 0.1 parts by mass of (D-2) were melt-kneaded. This is step (iii). For the melt-kneading, the above twin screw extruder was used. The temperature of melt kneading was 270 ° C. The obtained polyamide resin composition was subjected to evaluation. The evaluation results are shown in Table 2.
Example 4
(P-2) 100.5 parts by mass, (C-1) 50 parts by mass, and (D-1) 0.1 parts by mass were melt-kneaded. This is step (iii). For the melt-kneading, the above twin screw extruder was used. The temperature of melt kneading was 270 ° C. The obtained polyamide resin composition was subjected to evaluation. The evaluation results are shown in Table 2.
Example 5
110 parts by mass of (P-3), 50 parts by mass of (C-1), and 0.1 parts by mass of (D-1) were melt-kneaded. This is step (iii). For the melt-kneading, the above twin screw extruder was used. The temperature of melt kneading was 270 ° C. The obtained polyamide resin composition was subjected to evaluation. The evaluation results are shown in Table 2.
Example 6
(P-5) 105 parts by mass, (C-1) 200 parts by mass, (D-1) 0.1 parts by mass were melt-kneaded. This is step (iii). For the melt-kneading, the above twin screw extruder was used. The temperature of melt kneading was 270 ° C. The obtained polyamide resin composition was subjected to evaluation. The evaluation results are shown in Table 2.
Example 7
(P-6) 105 parts by mass, (C-1) 50 parts by mass, (D-1) 0.01 parts by mass were melt-kneaded. This is step (iii). For the melt-kneading, the above twin screw extruder was used. The temperature of melt kneading was 270 ° C. The obtained polyamide resin composition was subjected to evaluation. The evaluation results are shown in Table 2.
Example 8
(P-7) 105 parts by mass, (C-1) 50 parts by mass, (D-1) 3 parts by mass were melt-kneaded. This is step (iii). For the melt-kneading, the above twin screw extruder was used. The temperature of melt kneading was 200 ° C. The obtained polyamide resin composition was subjected to evaluation. The evaluation results are shown in Table 2.
Example 9
107 parts by mass of (P-12), 50 parts by mass of (C-1), and 0.1 parts by mass of (D-1) were melt-kneaded. This is step (iv). For the melt-kneading, the above twin screw extruder was used. The temperature of melt kneading was 270 ° C. The obtained polyamide resin composition was subjected to evaluation. The evaluation results are shown in Table 2.
Example 10
107 parts by mass of (P-13), 50 parts by mass of (C-1), and 0.1 parts by mass of (D-1) were melt-kneaded. This is step (iv). For the melt-kneading, the above twin screw extruder was used. The temperature of melt kneading was 270 ° C. The obtained polyamide resin composition was subjected to evaluation. The evaluation results are shown in Table 2.
Example 11
120 parts by mass of (P-4), 50 parts by mass of (C-1), and 0.1 parts by mass of (D-1) were melt-kneaded. This is step (iii). For the melt-kneading, the above twin screw extruder was used. The temperature of melt kneading was 270 ° C. The obtained polyamide resin composition was subjected to evaluation. The evaluation results are shown in Table 2.
Example 12
(P-1) 105 parts by mass, (C-2) 20 parts by mass, and (D-1) 0.1 parts by mass were melt-kneaded. This is step (iii). For the melt-kneading, the above twin screw extruder was used. The temperature of melt kneading was 270 ° C. The obtained polyamide resin composition was subjected to evaluation. The evaluation results are shown in Table 2.
Example 13
120 parts by mass of (P-4), 50 parts by mass of (C-1), and 0.1 parts by mass of (D-1) were melt-kneaded. This is step (iii). For the melt-kneading, the above twin screw extruder was used. The temperature of melt kneading was 270 ° C. The obtained polyamide resin composition was subjected to evaluation. The evaluation results are shown in Table 3.

Comparative Example 1
(P-8) 105 parts by mass, (C-1) 50 parts by mass, and (D-1) 0.1 parts by mass were kneaded. This is step (iii). For the melt-kneading, the above twin screw extruder was used. The temperature of melt kneading was 270 ° C. The obtained polyamide resin composition was subjected to evaluation. The evaluation results are shown in Table 3.
Comparative Example 2
(P-9) 105 parts by mass, (C-1) 50 parts by mass, and (D-1) 0.1 parts by mass were kneaded. This is step (iii). For the melt-kneading, the above twin screw extruder was used. The temperature of melt kneading was 270 ° C. The obtained polyamide resin composition was subjected to evaluation. The evaluation results are shown in Table 3.
Comparative Example 3
(P-10) 155 parts by mass, (C-1) 50 parts by mass, and (D-1) 0.1 parts by mass were kneaded. This is step (iii). For the melt-kneading, the above twin screw extruder was used. The temperature of melt kneading was 270 ° C. The obtained polyamide resin composition was subjected to evaluation. The evaluation results are shown in Table 3.
Comparative Example 4
107 parts by mass of (P-11), 50 parts by mass of (C-1), and 0.1 parts by mass of (D-1) were melt-kneaded. This is step (v). For the melt-kneading, the above twin screw extruder was used. The temperature of melt kneading was 285 ° C. The obtained polyamide resin composition was subjected to evaluation. The evaluation results are shown in Table 3.
Comparative Example 5
105 parts by mass of (P-1) and 50 parts by mass of (C-1) were melt-kneaded. For the melt-kneading, the above twin screw extruder was used. This is step (iii). The temperature of melt kneading was 270 ° C. The obtained polyamide resin composition was subjected to evaluation. The evaluation results are shown in Table 3.
Comparative Example 6
(P-1) 105 parts by mass, (C-1) 50 parts by mass, and (D-1) 4 parts by mass were kneaded. This is step (iii). For the melt-kneading, the above twin screw extruder was used. The temperature of melt kneading was 270 ° C. The obtained polyamide resin composition was subjected to evaluation. The evaluation results are shown in Table 3.
Comparative Example 7
(P-14) 105 parts by mass, (C-1) 50 parts by mass, and (D-1) 0.1 parts by mass were kneaded. This is step (iii). For the melt-kneading, the above twin screw extruder was used. The temperature of melt kneading was 270 ° C. The obtained polyamide resin composition was subjected to evaluation. The evaluation results are shown in Table 3.
Comparative Example 8
(P-15) 105 parts by mass, (C-1) 50 parts by mass, and (D-1) 0.1 parts by mass were kneaded. This is step (iii). For the melt-kneading, the above twin screw extruder was used. The temperature of melt kneading was 270 ° C. The obtained polyamide resin composition was subjected to evaluation. The evaluation results are shown in Table 3.
Comparative Example 9
(P-1) 105 parts by mass, (C-1) 10 parts by mass, and (D-1) 0.1 parts by mass were kneaded. This is step (iii). For the melt-kneading, the above twin screw extruder was used. The temperature of melt kneading was 270 ° C. The obtained polyamide resin composition was subjected to evaluation. The evaluation results are shown in Table 3.
Comparative Example 10
(P-1) 105 parts by mass, (C-1) 210 parts by mass, and (D-1) 0.1 parts by mass were kneaded. This is step (iii). For the melt-kneading, the above twin screw extruder was used. The temperature of melt kneading was 270 ° C. Since the blending of (C-1) was excessive, polyamide resin composition pellets could not be obtained.
Comparative Example 11
120 parts by mass of (P-16), 50 parts by mass of (C-1) and 0.1 parts by mass of (D-1) were melt-kneaded. This is step (iii). For the melt-kneading, the above twin screw extruder was used. The temperature of melt kneading was 270 ° C. The obtained polyamide resin composition was subjected to evaluation. The evaluation results are shown in Table 3.
Comparative Example 12
(P-17) 105 parts by mass, (C-1) 50 parts by mass, and (D-1) 0.1 parts by mass were kneaded. This is step (iii). For the melt-kneading, the above twin screw extruder was used. The temperature of melt kneading was 270 ° C. The obtained polyamide resin composition was subjected to evaluation. The evaluation results are shown in Table 3.

The polyamide resin compositions obtained in Examples 1 to 12 were sufficiently improved in tensile strength and flexural modulus without increasing the density.

Since the polyamide resin compositions obtained in Comparative Example 1 and Comparative Example 2 used a swellable layered silicate other than hectorite, the average length of the short sides of the swellable layered silicate was excessive, and the swellability was increased. The ratio of the average long side length / average short side length of the layered silicate was too small. Therefore, the tensile strength was inferior.

Since the polyamide resin composition obtained in Comparative Example 3 had an excessive hectorite content, the average inter-particle distance of the swellable layered silicate was too small, and the average long side length of the swellable layered silicate was also large. The ratio of length / average short side length was too small. Therefore, the tensile strength was inferior.

Since the polyamide resin composition obtained in Comparative Example 4 used a swellable layered silicate other than hectorite, the ratio of the average long side length / average short side length of the swellable layered silicate was too small. The average thickness of the layered silicate was also thick. Therefore, the tensile strength was inferior.

The polyamide resin composition obtained in Comparative Example 5 was inferior in tensile strength because it did not contain a silane coupling agent.

The polyamide resin composition obtained in Comparative Example 6 had an excessive amount of silane coupling agent, so that the toughness of the polyamide resin was impaired and the tensile strength and specific modulus were inferior.

Since the polyamide resin composition obtained in Comparative Example 7 uses a swellable layered silicate other than hectorite, the ratio of the average long side length / average short side length of the swellable layered silicate is too small, It was inferior in tensile strength.

Since the polyamide resin composition obtained in Comparative Example 8 was not blended with an inorganic acid, the average short side length and average thickness of hectorite were excessive, and the average long side length / average of the swellable layered silicate The ratio of short side length was too small, and the bending elastic modulus was inferior.

The polyamide resin composition obtained in Comparative Example 9 was inferior in tensile strength and flexural modulus because the amount of fibrous reinforcing material was insufficient.

Since the polyamide resin composition obtained in Comparative Example 11 uses a swellable layered silicate other than hectorite, the ratio of the average long side length / average short side length of the swellable layered silicate is too small, It was inferior in tensile strength.

The polyamide resin composition obtained in Comparative Example 12 had an excessively low average number of hectorite due to an excessively low rotational speed in step (i), and was inferior in flexural modulus.

The polyamide resin composition of the present invention can improve the tensile strength and the flexural modulus without increasing the density. Therefore, it can be suitably used in various material fields and is useful.

Claims

A polyamide resin composition comprising 100 parts by weight of a polyamide resin, 0.5 to 20 parts by weight of hectorite, 15 to 200 parts by weight of a fibrous reinforcing material, and 0.01 to 3 parts by weight of a silane coupling agent, The size of the hectorite is 1 to 10 nm in average thickness and 25 to 100 nm in average length on the short side, and the average length ratio of the long side to the average length of the short side is the average length of the long side / average of the short side A polyamide resin composition having a length of 1.5 to 5 and an average interparticle distance of 10 to 200 nm in the polyamide resin composition of the hectorite.
A method for producing a polyamide resin composition comprising the steps (i), (ii) and (iii) in this order in producing the polyamide resin composition according to claim 1.
Step (i): Mixing hectorite while stirring the monomer constituting the polyamide resin, the compound having an amino group and the inorganic acid at a temperature equal to or higher than the melting point of the monomer constituting the polyamide resin, and further adding water. In addition, a step of obtaining a preparation liquid by stirring at a rotational speed of 100 to 5000 rpm (ii): a step of obtaining a resin composition containing a polyamide resin and hectorite by polymerizing the preparation liquid obtained in step (i) (Iii): A step of melting the resin composition containing the polyamide resin and hectorite obtained in step (ii) and kneading the fibrous reinforcing material and the silane coupling agent.
3. The method for producing a polyamide resin composition according to claim 2, wherein in the step (i), the adjustment liquid measured with a B-type viscometer is mixed so that the rotational viscosity is 1 to 400 Pa · s.
When manufacturing the polyamide resin composition of Claim 1, the following process (iv) is included, The manufacturing method of the polyamide resin composition characterized by the above-mentioned.
Step (iv): Step of melt-kneading hectorite, fibrous reinforcing material and silane coupling agent to polyamide resin
The molded object obtained by shape | molding the polyamide resin composition of Claim 1.