JP2006274061A - Continuous fiber reinforced semi-aromatic polyamide resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition excellent in water absorbing property, heat resistance, chemical resistance, fatigue resistance and the like, particularly capable of maintaining high mechanical strength even in case of exposing for a long time under the condition of a high temperature, and a molded article comprising the resin composition. <P>SOLUTION: The continuous fiber reinforced semi-aromatic polyamide resin composition includes 100 parts by mass of a semi-aromatic polyamide resin (A) comprising a dicarboxylic acid unit (a) having 50-100 mol% of a terephtalic acid unit and a diamin unit (b) having 50-100 mol% of a 1,9-nonanediamine unit and/or a 2-methyl-1,8-octanediamine unit, and 5-300 parts by mass of a fibrous reinforcing material (B) having a fiber length of 3 mm or longer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention provides a long fiber reinforced semi-aromatic polyamide resin composition having excellent moldability and excellent mechanical properties, heat aging resistance and fatigue resistance, pellets made of the resin composition, and molding the resin composition. And a molded product formed by molding the pellet.

  General-purpose polyamides typified by nylon 6 and nylon 66 have excellent properties such as heat resistance, chemical resistance, rigidity, slidability, and moldability, and exhibit extremely high toughness in the moisture absorption state. It has been used for a wide range of applications such as parts, electrical and electronic parts, and sliding parts. However, these general-purpose polyamides do not sufficiently withstand the dimensional change and chemical resistance performance during water absorption, and various problems are occurring in the performance enhancement of recent materials. In the automotive field, there is a demand for automobile weight reduction, fuel efficiency, and resin conversion as a substitute for metals, which are associated with environmental problems. However, these general-purpose polyamides can meet sufficient demands. It is gone.

  For example, as the temperature in the engine room increases due to the pursuit of higher engine efficiency, there is an increasing demand for improved heat resistance for resin parts used in automobiles. In addition, the resin parts used in automobiles must have durability against chemicals such as gasoline, engine oil, calcium chloride aqueous solution, LLC aqueous solution (cooling water), and the rigidity, strength, toughness, creep resistance, etc. Since demands for performance are becoming higher year by year, conventional polyamides are becoming unable to cope with problems such as dimensional changes due to water absorption and insufficient heat resistance.

  In the electrical and electronic field, with the spread of surface mounting technology (SMT), resins used for connectors and the like are required to have reflow soldering heat resistance. Particularly in recent years, due to the rapid development of lead-free solder, the reflow solder temperature tends to further increase, and conventional polyamides are no longer able to cope with it. In addition, from the viewpoint of suppressing blisters during reflow soldering, there is an increasing demand for resins having both heat resistance and low water absorption.

  Furthermore, the usage environment of sliding parts is expanding to a high surface pressure and high temperature atmosphere, and conventional polyamides have insufficient wear resistance and durability. In addition, dimensional accuracy is extremely important for sliding parts, but the conventional polyamide has a problem that the dimensional change due to water absorption is large and troubles due to poor meshing of the gear occur.

A resin composition comprising a semi-aromatic polyamide (PA6T) having terephthalic acid and isophthalic acid as a dicarboxylic acid component and 1,6-hexanediamine as a diamine component has been proposed as a polyamide that can cope with the various problems described above. (See Patent Documents 1 to 3).
Further, as a resin composition having further excellent performance in heat resistance, low water absorption and creep resistance, terephthalic acid is a dicarboxylic acid unit, and 1,9-nonanediamine and / or 2-methyl-1,8-octanediamine is used. A resin composition comprising a semi-aromatic polyamide having a diamine unit as a diamine unit has been proposed (see Patent Documents 4 to 6).

  On the other hand, as a means for improving the strength of the polyamide resin, a technique of blending a fibrous reinforcing material such as glass fiber with the polyamide is known. Generally, a short fiber such as polyamide resin and chopped strand is mixed. A fiber-reinforced polyamide resin composition is produced by extruding with an extruder. However, in this method, fiber breakage is unavoidable during kneading in an extruder, and it is difficult to sufficiently bring out the inherent performance of the fibrous reinforcing material to be blended.

In order to solve such problems and to give higher mechanical strength, long fibers (for example, glass fibers having a length of 3 mm or more) are blended in a polyamide resin composition containing polyamide resin such as polyamide 66. The technique which performs is known (refer patent documents 7-11).
However, a polyamide resin composition capable of maintaining a high mechanical strength even under extremely severe conditions such as being exposed for a long time at a high temperature has not been known.
Japanese Patent Laid-Open No. 3-7761 Japanese Patent Laid-Open No. 3-72565 JP 60-158220 A JP 7-228769 A JP 7-228772 A JP 7-228774 A JP-A-8-28572 JP-A-5-9380 Japanese Patent Laid-Open No. 5-208418 JP-A-6-107944 JP-A-7-330918

  The present invention provides a resin composition excellent in water absorption, heat resistance, chemical resistance, fatigue resistance, etc., and a pellet made of the resin composition, and a molded product formed by molding them, in particular, high temperature. It is an object of the present invention to provide a resin composition capable of maintaining a high mechanical strength even under conditions exposed to a long time, pellets made of the resin composition, and a molded product formed by molding them. .

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention can provide a high degree of mechanical strength when blended with a specific polyamide resin with a specific size long fiber reinforcement, at high temperatures. The present inventors have found that a polyamide resin composition capable of maintaining a high mechanical strength even when exposed to a long time is obtained, and the present invention has been completed.

That is, the present invention provides a dicarboxylic acid unit (a) containing 50 to 100 mol% of terephthalic acid units, 50 to 100 mol of 1,9-nonanediamine unit and / or 2-methyl-1,8-octanediamine unit. % Long-fiber reinforced half containing 100 parts by mass of semi-aromatic polyamide resin (A) composed of diamine unit (b) and 5 to 300 parts by mass of fibrous reinforcing material (B) having a fiber length of 3 mm or more. An aromatic polyamide resin composition.
Further, the present invention is a pellet made of the above-mentioned long fiber reinforced semi-aromatic polyamide resin composition, the length of the pellet is 3 to 30 mm, and the fibrous reinforcing material (B) is substantially a pellet. It is a pellet characterized by having the same length.
Preferably, the present invention is the above pellet in which the fibrous reinforcing material (B) is arranged substantially parallel to the length direction of the pellet.
Furthermore, this invention is a molded article obtained by shape | molding the said long fiber reinforced semi-aromatic polyamide resin composition and the said pellet.

  The long fiber reinforced semi-aromatic polyamide resin product of the present invention is superior in heat resistance, mechanical properties, chemical resistance, and the like as compared with the conventional long fiber reinforced polyamide resin composition, and particularly in heat aging resistance. It is excellent and can maintain a high mechanical strength even under conditions where it is exposed for a long time at a high temperature. Therefore, for example, in applications such as automotive metal parts, it can be used as an alternative material that has been difficult in the past.

The present invention will be described in detail below.
In this specification, the “long fiber” means a fiber having a fiber length of 3 mm or more, and the “short fiber” means a fiber having a fiber length of less than 3 mm.
The long fiber reinforced semi-aromatic polyamide resin composition of the present invention includes 100 parts by mass of a semi-aromatic polyamide resin (A) and 5 to 300 parts by mass of a fibrous reinforcing material (B) having a fiber length of 3 mm or more. .
(Description of semi-aromatic polyamide resin (A))
The semi-aromatic polyamide resin (A) comprises a dicarboxylic acid unit (a) containing 50 to 100 mol% of terephthalic acid units (hereinafter simply referred to as dicarboxylic acid unit (a)), a 1,9-nonanediamine unit and / or It consists of a diamine unit (b) containing 50 to 100 mol% of 2-methyl-1,8-octanediamine unit (hereinafter simply referred to as diamine unit (b)).

  The content rate of the terephthalic acid unit in a dicarboxylic acid unit (a) is 50-100 mol%, Preferably it is 75-100 mol%, More preferably, it exists in the range of 90-100 mol%. When the content of the terephthalic acid unit in the dicarboxylic acid unit (a) is less than 50 mol%, the heat resistance of the resulting long fiber reinforced semi-aromatic polyamide resin composition is lowered.

  The dicarboxylic acid unit (a) may contain other dicarboxylic acid units other than the terephthalic acid unit as long as it is less than 50 mol%. Examples of such other dicarboxylic acid units include malonic acid, dimethylmalonic acid, succinic acid, glutaric acid, adipic acid, 2-methyladipic acid, trimethyladipic acid, pimelic acid, 2,2-dimethylglutaric acid, 2, Aliphatic dicarboxylic acids such as 2-diethylsuccinic acid, azelaic acid, sebacic acid and suberic acid; alicyclic dicarboxylic acids such as 1,3-cyclopentanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid; isophthalic acid, 2, 6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,4-phenylenedioxydiacetic acid, 1,3-phenylenedioxydiacetic acid, diphenic acid, diphenylmethane-4,4 '-Dicarboxylic acid, diphenylsulfone-4,4'-dicarboxylic acid, 4,4'-biphenyl Unit derived from an aromatic dicarboxylic acid such as a carboxylic acid can be exemplified, it is possible to use one or more of them. The content of these other dicarboxylic acid units in the dicarboxylic acid unit (a) is preferably 25 mol% or less, and more preferably 10 mol% or less. Furthermore, a unit derived from a polyvalent carboxylic acid such as trimellitic acid, trimesic acid, pyromellitic acid and the like may be included within a range where melt molding is possible.

  The content of the 1,9-nonanediamine unit and / or 2-methyl-1,8-octanediamine unit in the diamine unit (b) is 50 to 100 mol%, preferably 75 to 100 mol%, more preferably. It is in the range of 90 to 100 mol%. By setting the content of 1,9-nonanediamine unit and / or 2-methyl-1,8-octanediamine unit in diamine unit (b) within the above range, toughness, slidability, heat resistance, moldability, low A long fiber reinforced semi-aromatic polyamide resin composition excellent in water absorption and light weight can be obtained.

  The diamine unit (b) may contain other diamine units other than 1,9-nonanediamine units and 2-methyl-1,8-octanediamine units as long as it is 50 mol% or less. Such other diamine units include ethylenediamine, propylenediamine, 1,4-butanediamine, 1,6-hexanediamine, 1,8-octanediamine, 1,10-decanediamine, 1,12-dodecanediamine, 3- Such as methyl-1,5-pentanediamine, 2,2,4-trimethyl-1,6-hexanediamine, 2,4,4-trimethyl-1,6-hexanediamine, 5-methyl-1,9-nonanediamine, etc. Aliphatic diamines; cycloaliphatic diamines such as cyclohexanediamine, methylcyclohexanediamine, and isophoronediamine; p-phenylenediamine, m-phenylenediamine, xylylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone 4,4′-diaminodiphenyl ether, etc. Can be mentioned units derived from aromatic diamines, it can be used one or two or more of them. The content of these other diamine units in the diamine unit (b) is preferably 25 mol% or less, and more preferably 10 mol% or less.

  When the diamine unit (b) contains both a 1,9-nonanediamine unit and a 2-methyl-1,8-octanediamine unit, the 1,9-nonanediamine unit and 2-methyl- in the diamine unit (b) The molar ratio with the 1,8-octanediamine unit is preferably in the range of 1,9-nonanediamine unit: 2-methyl-1,8-octanediamine unit = 90: 10-50: 50, 85: More preferably, it is in the range of 15 to 55:45.

  Furthermore, the semiaromatic polyamide resin (A) used in the present invention may contain an aminocarboxylic acid unit as necessary. Specific examples of such aminocarboxylic acid units include units derived from lactams such as caprolactam and lauryllactam; aminocarboxylic acids such as 1-aminolauric acid and 1-aminododecylic acid. The content of aminocarboxylic acid units is preferably 40 mol or less and more preferably 20 mol or less with respect to 100 mol of all dicarboxylic acid units (a) of the semi-aromatic polyamide resin (A).

  In the semi-aromatic polyamide resin (A) used in the present invention, it is preferable that 10 mol% or more of the end groups of the molecular chain is sealed with an end-capping agent. The proportion of the end groups of the molecular chain being sealed with the end-capping agent (end-capping rate) is more preferably 40 mol% or more, and even more preferably 60 mol% or more. When the semi-aromatic polyamide resin (A) having a terminal blocking rate of 10 mol% or more is used, a long fiber reinforced semi-aromatic polyamide resin composition having better heat resistance and the like can be obtained.

The above-mentioned end-capping rate is determined by measuring the number of terminal carboxyl groups, terminal amino groups, and terminal groups blocked by a terminal blocking agent present in the semi-aromatic polyamide resin (A). (1) The number of each terminal group is preferably determined from the integral value of the characteristic signal corresponding to each terminal group by ¹ H-NMR in terms of accuracy and simplicity.

[Equation 1]
Terminal sealing rate (%) = [(A−B) / A] × 100 (1)

[In the formula, A represents the total number of terminal groups of the molecular chain (this is usually equal to twice the number of semi-aromatic polyamide resin (A) molecules), and B represents the terminal carboxyl group remaining unsealed. And the total number of terminal amino groups. ]

  The end-capping agent is not particularly limited as long as it is a monofunctional compound having reactivity with the amino group or carboxyl group at the end of the semi-aromatic polyamide resin (A). Monocarboxylic acid or monoamine is preferable from the viewpoint of property and the like, and monocarboxylic acid is more preferable from the viewpoint of easy handling. In addition, acid anhydrides, monoisocyanates, monoacid halides, monoesters, monoalcohols, and the like can also be used.

  The monocarboxylic acid used as the end-capping agent is not particularly limited as long as it has reactivity with an amino group. For example, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, laurin Aliphatic monocarboxylic acids such as acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, pivalic acid and isobutyric acid; cycloaliphatic monocarboxylic acids such as cyclohexanecarboxylic acid; benzoic acid, toluic acid, α-naphthalenecarboxylic acid , Β-naphthalene carboxylic acid, methyl naphthalene carboxylic acid, aromatic monocarboxylic acid such as phenyl acetic acid; any mixture thereof. Among these, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid in terms of reactivity, stability of the sealing end, price, etc. Benzoic acid is preferred.

  The monoamine used as the end-capping agent is not particularly limited as long as it has reactivity with a carboxyl group. For example, methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, decylamine , Stearylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine and other aliphatic monoamines; cyclohexylamine, dicyclohexylamine and other alicyclic monoamines; aniline, toluidine, diphenylamine, naphthylamine and other aromatic monoamines; any of these A mixture etc. can be mentioned. Among these, butylamine, hexylamine, octylamine, decylamine, stearylamine, cyclohexylamine, and aniline are preferable from the viewpoints of reactivity, high boiling point, stability of the sealing end and price.

  The semi-aromatic polyamide resin (A) used in the present invention can be produced using any method known as a method for producing crystalline polyamide. For example, it can be produced by a solution polymerization method or an interfacial polymerization method using acid chloride and diamine as raw materials, a melt polymerization method using dicarboxylic acid and diamine as raw materials, a solid phase polymerization method, or the like.

  The semi-aromatic polyamide resin (A) is prepared, for example, by first adding a diamine, a dicarboxylic acid, a catalyst, and, if necessary, an end-capping agent together to produce a nylon salt, and then at a temperature of 200 to 250 ° C. Produced by heat polymerization to give a prepolymer having an intrinsic viscosity [η] at 30 ° C. of 0.1 to 0.6 dl / g in concentrated sulfuric acid, followed by solid phase polymerization or polymerization using a melt extruder. be able to. When the final stage of the polymerization is carried out by solid phase polymerization, it is preferably carried out under reduced pressure or under an inert gas flow. The polymerization temperature at this time is preferably in the range of 200 to 280 ° C. Further, the polymerization temperature when the final stage of the polymerization is performed by a melt extruder is preferably 370 ° C. or lower.

  In producing the semi-aromatic polyamide resin (A), in addition to the above-mentioned end-capping agent, for example, as a catalyst, phosphoric acid, phosphorous acid, hypophosphorous acid, their salts or esters, etc. are added Can do. Examples of the salt or ester include phosphoric acid, phosphorous acid or hypophosphorous acid and metals such as potassium, sodium, magnesium, vanadium, calcium, zinc, cobalt, manganese, tin, tungsten, germanium, titanium, and antimony. Salt; ammonium salt of phosphoric acid, phosphorous acid or hypophosphorous acid; ethyl ester, isopropyl ester, butyl ester, hexyl ester, isodecyl ester, octadecyl ester, decyl ester of phosphoric acid, phosphorous acid or hypophosphorous acid , Stearyl ester, phenyl ester and the like.

  The semi-aromatic polyamide resin (A) used in the present invention preferably has an intrinsic viscosity [η] measured in concentrated sulfuric acid at 30 ° C. of 0.4 to 3.0 dl / g. It is more preferably 6 to 2.0 dl / g, and further preferably 0.8 to 1.8 dl / g.

(Description of fibrous reinforcement (B))
There is no restriction | limiting in particular as a kind of fibrous reinforcement (B) used in this invention, For example, glass fiber, carbon fiber, boron fiber, or metal fiber (Example: Stainless steel fiber, aluminum fiber, copper fiber etc.) etc. Inorganic fiber, polyparaphenylene terephthalamide fiber, polymetaphenylene terephthalamide fiber, polyparaphenylene isophthalamide fiber, polymetaphenylene isophthalamide fiber, fiber obtained from condensate of diaminodiphenyl ether and terephthalic acid or isophthalic acid Organic fibers such as wholly aromatic polyamide fibers or wholly aromatic liquid crystal polyester fibers can be used, but glass fibers are preferably used. A fibrous reinforcement (B) may be used individually by 1 type, or may use 2 or more types together.
The fibrous reinforcing material (B) is a silane coupling agent, titanium coupling agent, other polymer or low molecular weight for the purpose of improving dispersibility and adhesion in the semi-aromatic polyamide resin (A). What is surface-treated with the surface treating agent can be used.

In the long fiber reinforced semi-aromatic polyamide resin composition of the present invention, the fibrous reinforcing material (B) has a fiber length of 3 mm or more. When the fiber length is less than 3 mm in the resin composition, it becomes difficult to obtain a molded product having a high mechanical strength. The fiber length of the fibrous reinforcing material (B) is 3 to 30 mm from the viewpoint of improving the biting property of a screw such as an extruder when the long fiber reinforced semi-aromatic polyamide resin composition of the present invention is molded. It is preferably within the range, more preferably within the range of 4 to 20 mm, and even more preferably within the range of 5 to 15 mm.
In addition, this fiber length is the value prescribed | regulated with respect to the fibrous reinforcement (B) after a mixing | blending in the long fiber reinforced semi-aromatic polyamide resin composition of this invention. That is, the fiber length of the fibrous reinforcing material (B) before blending is not particularly limited.

  The content rate of the fibrous reinforcing material (B) in the long fiber reinforced semi-aromatic polyamide resin composition of the present invention is 5 to 300 parts by mass with respect to 100 parts by mass of the semi-aromatic polyamide resin (A). When the content is less than 5 parts by mass, the reinforcing effect by the fibrous reinforcing material (B) is small. Conversely, when it exceeds 300 parts by mass, the workability in preparation or molding of the composition is remarkably inferior. There is almost no improvement in strength that accompanies the increase. Considering the balance between the reinforcing effect and workability, the preferred fiber blending amount is 20 to 200 parts by mass, particularly preferably 30 to 150 parts by mass with respect to 100 parts by mass of the semi-aromatic polyamide resin (A).

  The ratio of the total mass of the semiaromatic polyamide resin (A) and the fibrous reinforcing material (B) in the long fiber reinforced semiaromatic polyamide resin composition of the present invention is 40 to 100 mass%. It is preferably 55 to 100% by mass.

  The long fiber reinforced semi-aromatic polyamide resin composition of the present invention may contain one or more of other thermoplastic resins as long as the purpose and effect thereof are not significantly impaired. In addition, in order to impart desired properties according to the purpose, known additives generally added to thermoplastic resins, such as copper stabilizers, antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, etc. Stabilizers, antistatic agents, flame retardants, flame retardant aids, colorants such as dyes and pigments, lubricants, lubricants, plasticizers, crystallization accelerators, crystal nucleating agents, and the like can be further blended. Further, glass flakes, mica, glass powder, glass beads, talc, clay, alumina, carbon black, wollastonite and other plate-like or powdery inorganic compounds or whiskers may be used in appropriate amounts. In addition, fibrous reinforcements other than the above-mentioned fibrous reinforcement (B), such as fibrous reinforcements composed of short fibers having a fiber length of less than 3 mm and fibrous reinforcements composed of long fibers having a fiber length of more than 30 mm. May be included.

  Examples of the copper stabilizer include cuprous chloride, cuprous bromide, cuprous iodide, cupric chloride, cupric bromide, cupric iodide, cupric phosphate, Inorganic copper salts such as cupric pyrophosphate, copper sulfide and copper nitrate, copper salts of organic carboxylic acids such as copper acetate, organometallic compounds such as copper acetylacetonate, etc. Two or more kinds can be used. When these copper compounds are blended, the blending amount is preferably within a range of 0.01 to 1 part by mass with respect to 100 parts by mass of the semi-aromatic polyamide resin (A). More preferably, it is in the range of 02 to 0.5 parts by mass.

  These copper stabilizers include lithium chloride, lithium bromide, lithium iodide, sodium fluoride, sodium chloride, sodium bromide, sodium iodide, potassium fluoride, potassium chloride, potassium bromide, potassium iodide, etc. It can be used with an alkali metal halide or an organic substance capable of forming a complex with copper, such as a benzimidazole derivative, an alkylenediamine, and an alkylenetriamine. Among these, potassium iodide is preferable. The use amount of the above-mentioned alkali metal halide or organic substance capable of forming a complex with copper is preferably in the range of 1 to 20 times by mass with respect to the copper stabilizer.

  Examples of the antioxidant include hindered phenol antioxidants, hindered amine antioxidants, phosphorus antioxidants, sulfur antioxidants, and the like.

  The blending method in the case of blending such other thermoplastic resins and known additives is not particularly limited, and it is preferable to adopt a method that can uniformly mix these, and usually a semi-aromatic polyamide A method of blending the fibrous reinforcing material (B) after melt-kneading the resin (A) with another thermoplastic resin or a known additive is employed. The type of equipment used for melt-kneading, melt-kneading conditions, etc. are not particularly limited, but it is possible to adopt a method of kneading with a device such as a twin screw extruder at a temperature in the range of about 300-350 ° C. for 1-30 minutes. it can.

  The production method of the long fiber reinforced semi-aromatic polyamide resin composition of the present invention is not particularly limited, but a production method in which shearing force is not applied as much as possible in order to suppress fiber breakage after blending the fibrous reinforcement (B). Of these, the production method by pultrusion is particularly preferred. The pultrusion molding basically involves impregnating a resin while drawing continuous reinforcing fibers. In the present invention, the semi-aromatic polyamide resin (A) and, if desired, other thermoplastics described above are used. A method of impregnating a fibrous reinforcing material (B) in an impregnation bath containing an emulsion, suspension, solution or melt containing a resin or a known additive, and the semi-aromatic polyamide resin (A) Alternatively, a powder of what is blended with the above-mentioned other thermoplastic resins or known additives is sprayed onto the fibrous reinforcing material (B), or the fibrous reinforcing material (B) is placed in a tank containing the powder. Any method can be used in which the powder is adhered to the fibrous reinforcing material (B) by passing it, and then melted. However, using an extruder, a roving shape is formed in the crosshead die. Fibrous reinforcement of While passing through (B), the melted semi-aromatic polyamide resin (A) and the above-mentioned other thermoplastic resin, known additives and the like are supplied to the crosshead die and directly impregnated. The method is preferred.

The long fiber reinforced semi-aromatic polyamide resin composition thus obtained is preferably processed into pellets. In the case of processing into a pellet, the strand-like long fiber reinforced semi-aromatic polyamide resin composition obtained by pultrusion as described above can be cooled and then cut by a pelletizer or the like. In addition, it is preferable to adjust the length of the pellet at the time of making it into a pellet within the range of 3-30 mm. By adjusting the length of the pellet within this range, a pellet in which the fibrous reinforcing material (B) is substantially the same length as the pellet can be obtained. The length of the pellet is more preferably in the range of 4 to 20 mm, and still more preferably in the range of 5 to 15 mm.
Further, by such a method, a pellet in which the fibrous reinforcing material (B) in the pellet is arranged substantially parallel to the length direction of the pellet can be obtained.

  The molded article of the present invention can be obtained by molding a long fiber reinforced polyamide resin composition or a melt of the above pellets. As the molding method, any known method can be used. Specifically, it is generally used for thermoplastic resin compositions such as injection molding, extrusion molding, press molding, blow molding, calendar molding, and casting molding. And a molding method used. A molding method combining the above molding methods can also be employed. In the molded product, the fibrous reinforcing material derived from the fibrous reinforcing material (B) is preferably dispersed with a weight average fiber length of 1 mm to 10 mm.

  The use of the molded product obtained from the resin composition or pellet of the present invention is not particularly limited. For example, automobile parts (eg, rear differential mount, engine mount, upper arm, lower arm, shaft, etc.), electric / electronic parts (eg: Applications include sealing materials, electrical insulating materials, dielectric materials, connectors, capacitor seats, relays, sockets, etc.), sliding parts (eg, various gear applications, etc.), industrial parts, clothing products, and the like.

The weight average fiber length of the fibrous reinforcing material contained in the molded article of the present invention can be measured, for example, by the following method.
(I) A test piece having a width of 5 mm, a thickness of 3 mm, and a length of 15 mm is cut out from the molded product.
(Ii) The test piece is immersed in a solvent (eg, trifluoroacetic acid or the like), components other than the fibrous reinforcement (such as semi-aromatic polyamide resin) are dissolved, and only the fibrous reinforcement is taken out from the test piece.
(Iii) The taken-out fibrous reinforcement is dispersed in water or the like as necessary, and observed with an optical microscope (approximately 50 times magnification) or the like, and the fiber length of 500 fibrous reinforcements in the field of view is measured. .
(Iv) The fiber length of each fiber is Li, the number of fibers of the fiber length Li is qi, and the weight average fiber length Lw is obtained based on the following equation (2).

[Equation 2]
Lw = (Σqi × Li ² ) / (Σqi × Li) (2)

  The long fiber reinforced polyamide resin composition of the present invention and the pellets obtained therefrom can be formed into a mechanism / structural part (eg, an automobile undercarriage part or a metal substitute application). By using the long fiber reinforced polyamide resin composition of the present invention and pellets obtained therefrom, these parts are excellent in strength, fatigue resistance and impact resistance, and particularly in heat aging resistance.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to this. In the following examples and comparative examples, the following materials were used as polyamide resins and fibrous reinforcing materials. Each evaluation method followed the following method.

PA-1:
A terephthalic acid unit, a 1,9-nonanediamine unit and a 2-methyl-1,8-octanediamine unit [1,9-, produced according to the method described in Example 2 of JP-A-7-228689 Intrinsic viscosity [η] (measured in concentrated sulfuric acid at 30 ° C.) 1.20 dl / g, melting point 302 ° C., consisting of nonanediamine unit: 2-methyl-1,8-octanediamine unit = 80: 20 (molar ratio)] Semi-aromatic polyamide resin having a terminal sealing ratio of 70% (terminal sealing agent: benzoic acid) and a density of 1.14 g / cm ³ .

PA-2:
A terephthalic acid unit, a 1,9-nonanediamine unit and a 2-methyl-1,8-octanediamine unit [1,9-, produced according to the method described in Example 2 of JP-A-7-228689 Intrinsic viscosity [η] (measured in concentrated sulfuric acid at 30 ° C.) 1.20 dl / g, melting point 273 ° C., consisting of nonanediamine unit: 2-methyl-1,8-octanediamine unit = 60: 40 (molar ratio)] Semi-aromatic polyamide resin having a terminal sealing ratio of 70% (terminal sealing agent: benzoic acid) and a density of 1.14 g / cm ³ .

PA-3:
Polyhexamethylene adipamide ("UBE nylon 2020B" manufactured by Ube Industries, Ltd.).

PA-4:
Semi-aromatic polyamide resin ("Don Pont" 101L ") consisting of terephthalic acid and isophthalic acid units (terephthalic acid units: isophthalic units = 60:40 (molar ratio)) and 1,6-hexanediamine units

Fibrous reinforcement-1:
Glass fiber (manufactured by Nittobo, RS240QR482, shape: roving)

Fibrous reinforcement-2:
Glass fiber (short fiber) (Brand: Nittobo, CS3J-256S)

Evaluation of gas generation:
When injection molding was performed at 320 ° C. using the pellets produced in the following examples and comparative examples, the amount of smoke generated from the cylinder tip of the injection molding machine was evaluated according to the following criteria.
A: Almost no smoke.
B: Smoke a little.
C: There is smoke.

Evaluation of biting property:
When injection molding was performed using the pellets produced in the following Examples and Comparative Examples, the degree of biting into the screw of the injection molding machine was evaluated according to the following criteria.
A: Good biting.
B: Somewhat bad.
C: Almost no biting.

Product burn rating:
Surface of molded product at the time of mold filling (mold size: 40 mm × 100 mm × 2 mm, mold temperature: 150 ° C.) when injection molded at 320 ° C. using pellets produced in the following examples and comparative examples Was evaluated according to the following criteria.
A: No burning.
B: Slightly generated.
C: Many burns.

Evaluation of mechanical strength:
Using the pellets produced in the following examples and comparative examples, a dumbbell specimen having a thickness of 3 mm was prepared according to JIS K7113, and mechanical strength (tensile yield strength, tensile fracture elongation, tensile elastic modulus) was obtained. Evaluated.

Evaluation of heat aging resistance:
The dumbbell test pieces having a thickness of 3 mm produced using the pellets produced in the following examples and comparative examples were placed in a hot air dryer at 190 ° C. for a certain period of time (100, 300, 500, 1000, 2000, 3000 hours), respectively. These were measured for tensile yield strength in accordance with JIS K7113, and the ratio (retention rate of tensile yield strength) to the tensile yield strength before treatment with the hot air dryer was calculated to be heat aging resistance.

Evaluation of chemical resistance:
Using the pellets produced in the following examples and comparative examples, a dumbbell test piece having a thickness of 3 mm was prepared, immersed in the following chemicals at 23 ° C. for 7 days, and then taken out of the dumbbell test piece. The surface was visually observed and evaluated according to the following evaluation criteria.
<Chemicals>
Gasoline Engine oil Methanol Toluene Chloroform Hot water (80 ° C)
Acid (10wt% sulfuric acid water)
Alkali (50wt% NaOH water)
Calcium chloride (50wt% water)
<Evaluation criteria>
A: Appearance is good.
B: There is cloudiness on the surface.
C: Cracks are generated.

Evaluation of weight average fiber length The weight average fiber length of the fibrous reinforcing material in the molded article of the present invention was measured as follows.
A test piece having a width of 5 mm, a thickness of 3 mm, and a length of 15 mm was cut out from the molded product, immersed in trifluoroacetic acid to dissolve portions other than the fibrous reinforcement, and only the fibrous reinforcement was taken out from the test piece. . The obtained fibrous reinforcing material is observed with an optical microscope (magnification: 50 times), 500 arbitrary fibrous reinforcing materials in the field of view are selected, the fiber length is measured, and based on the above formula (2) The weight average fiber length was measured.

<Example 1>
Semi-aromatic polyamide resin PA-1 was supplied to an extruder equipped with a crosshead die and melt-kneaded at 320 ° C. (residence time 3 minutes). At the same time, roving-like fibrous reinforcing material-1 was supplied to the crosshead die, and a resin composition was produced by pultrusion molding. Under the present circumstances, the supply amount of PA-1 was adjusted so that content of the fibrous reinforcement in a composition might be 100 mass parts with respect to 100 mass parts PA-1. The obtained resin composition was cooled by water cooling and then cut every 13 mm to obtain cylindrical pellets having a length of 13 mm and a diameter of 2 to 3 mm. In the obtained pellet, it was confirmed with an optical microscope that the fibrous reinforcing material was arranged substantially parallel to the length direction of the pellet. Each evaluation was performed according to each evaluation method described above using the obtained pellets. The results are shown in Table 1 below.

<Example 2>
A cylindrical pellet having a length of 13 mm and a diameter of 2 to 3 mm was produced in the same manner as in Example 1 except that PA-2 was used instead of PA-1. In the pellet, it was confirmed with an optical microscope that the fibrous reinforcing materials were arranged substantially parallel to the length direction of the pellet. Using this pellet, each evaluation was performed according to each evaluation method described above. The evaluation results are shown in Table 1 below.

<Comparative Example 1>
A cylindrical pellet having a length of 13 mm and a diameter of 2 to 3 mm was produced in the same manner as in Example 1 except that PA-3 was used instead of PA-1. In the pellet, it was confirmed with an optical microscope that the fibrous reinforcing materials were arranged substantially parallel to the length direction of the pellet. Using this pellet, each evaluation was performed according to each evaluation method described above. The evaluation results are shown in Table 1 below.

<Comparative example 2>
A cylindrical pellet having a length of 13 mm and a diameter of 2 to 3 mm was produced in the same manner as in Example 1 except that PA-4 was used instead of PA-1. In the pellet, it was confirmed with an optical microscope that the fibrous reinforcing materials were arranged substantially parallel to the length direction of the pellet. Using this pellet, each evaluation was performed according to each evaluation method described above. The evaluation results are shown in Table 1 below.

<Comparative Example 3>
Using a twin screw extruder (manufactured by Plastics Engineering Laboratory, BT-30), the fibrous reinforcing material-2 was side-fed to the semi-aromatic polyamide resin PA-1 and melt-kneaded at 320 ° C. (retention) Time 3 minutes). Under the present circumstances, the supply amount of the fibrous reinforcement-2 was adjusted so that content of the fibrous reinforcement in a composition might be 100 mass parts with respect to 100 mass parts PA-1. The fiber length of the fibrous reinforcing material in the composition was 2 mm or less. The obtained resin composition was cooled by water cooling and then cut every 2 mm to obtain cylindrical pellets having a length of 2 mm and a diameter of 1.5 mm. When the pellet was observed with an optical microscope, the arrangement direction of the fibrous reinforcing material in the pellet was not uniform and was not arranged substantially parallel to the length direction of the pellet. Each evaluation was performed according to each evaluation method described above using the obtained pellets. The results are shown in Table 1 below.

<Example 3>
Using the pellets obtained in Example 1, injection molding was performed under the conditions of a cylinder temperature of 320 ° C. and a mold temperature of 150 ° C. using a 220-ton injection molding machine manufactured by Nippon Steel Co., Ltd. : A molded product of 215 mm × 12.7 mm × 3.2 mm was obtained. It was 3-5 mm when the weight average fiber length of the glass fiber of this molded article was measured according to the method described in the above “Method for measuring weight average fiber length”.

  As is clear from the above, the pellet of Example 1 containing 100 parts by mass of PA-1 and 100 parts by mass of a fibrous reinforcing material having a fiber length of 13 mm, and 100 parts by mass of PA-2 and the fiber length of 13 mm. In any of the pellets of Example 2 containing 100 parts by mass of a certain fibrous reinforcing material, almost no gas generation was observed during injection molding, good biting into the screw of the injection molding machine, and gold No burning of the surface of the molded product during mold filling was observed. Moreover, both the pellets of Examples 1 and 2 had excellent mechanical strength. Furthermore, although the pellets of Examples 1 and 2 were somewhat poor in chemical resistance in methanol, they showed good chemical resistance for all other chemicals. In addition, as is apparent from the evaluation of heat aging resistance, the pellets of Examples 1 and 2 both maintained good mechanical strength even when exposed to high temperatures for a long time.

The long fiber reinforced semi-aromatic polyamide resin composition of the present invention has low water absorption, excellent heat resistance, chemical resistance, slidability, creep resistance, rigidity, toughness, and higher strength. It becomes possible to provide a molded article. Furthermore, the long fiber reinforced semi-aromatic polyamide resin composition of the present invention can maintain high mechanical strength even under conditions where it is exposed to a high temperature for a long time.
Accordingly, a molded article made of the long fiber reinforced semi-aromatic polyamide resin composition of the present invention and a molded article made of pellets of the resin composition are automobile parts, sliding parts, electric / electronic parts (eg, sealing materials, electric parts). Insulating materials, dielectric materials, etc.), industrial parts, clothing products, etc. can be used in a wide range of applications.

Claims (6)

  Dicarboxylic acid unit (a) containing 50 to 100 mol% of terephthalic acid unit, and diamine unit containing 50 to 100 mol% of 1,9-nonanediamine unit and / or 2-methyl-1,8-octanediamine unit ( a long fiber reinforced semi-aromatic polyamide resin composition comprising 100 parts by mass of a semi-aromatic polyamide resin (A) comprising 5) and 5 to 300 parts by mass of a fibrous reinforcing material (B) having a fiber length of 3 mm or more. .   The molar ratio of the 1,9-nonanediamine unit to the 2-methyl-1,8-octanediamine unit in the diamine unit (b) is 1,9-nonanediamine unit: 2-methyl-1,8-octanediamine unit = 90: The long fiber reinforced semi-aromatic polyamide resin composition according to claim 1, wherein the composition is 10 to 50:50.   A pellet comprising the long fiber reinforced semi-aromatic polyamide resin composition according to claim 1 or 2, wherein the pellet has a length of 3 to 30 mm, and the fibrous reinforcing material (B) is substantially a pellet. Pellets characterized by having the same length.   The pellet according to claim 3, wherein the fibrous reinforcing material (B) is arranged substantially parallel to the length direction of the pellet.   A molded product obtained by molding the long fiber reinforced semi-aromatic polyamide resin composition according to claim 1 or 2, wherein the fibrous reinforcing material (B) is dispersed with a weight average fiber length of 1 mm to 10 mm.   A molded product obtained by molding the pellet according to claim 3 or 4, wherein the fibrous reinforcing material (B) is dispersed with a weight average fiber length of 1 mm to 10 mm.