JP2008007753A - Polyamide resin composition and molded product thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyamide resin composition for portable electronic equipment, excellent in mechanical strength, thin-wall moldability and warpage resistance. <P>SOLUTION: The polyamide resin composition comprises a total of 100 wt.% of (A) 30-80 wt.% of a polyamide MP and (B) 20-70 wt.% of a second polyamide resin 245°C or higher in melting point and also contains filler(C). In this resin composition, the filler C comprises a fibrous filler(C1) as an optional component and a filler(C2) as the essential component in the weight ratio C1/C2 of (0:10) to (9:1), wherein the content of the filler C is 30-250 pts.wt. based on a total 100 pts.wt. of the polyamide MP(A) and the second polyamide resin(B), and the polyamide MP(A) is such a polyamide resin as to be obtained by polycondensation reaction between a mixed diamine comprising 90-50 mol% of m-xylylenediamine and 10-50 mol% of p-xylylenediamine and an α,ω-straight-chain aliphatic dibasic acid and/or an aromatic dibasic acid. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a polyamide resin composition and a molded article, and more specifically, a polyamide resin composition and a molded article excellent in mechanical strength, thin-wall moldability, crystallinity, and warpage, and suitable for a thin flat plate-shaped portable electronic device part. About.

  Portable electronic devices such as PDAs, portable game machines, and mobile phones are often dropped for carrying, and drop impact is an important characteristic especially for exterior parts such as housings. When the thickness of the product can be increased, a resin composition composed of these resins and a small amount of filler is used in addition to non-reinforced polycarbonate resin and ABS resin having excellent impact resistance.

  A portable electronic device component may require a flat plate-shaped component that requires rigidity to support the internal structure without going outside. For example, the back side of the keyboard may be designed to require a back plate that supports the keys. In this part, the circuit board may be used directly. However, when the strength and rigidity of the circuit board is obtained, the material that satisfies both the electric characteristics such as dielectric constant and dielectric loss tangent, which are required characteristics of the board, and the strength and rigidity of the circuit board. Selection becomes difficult. In addition, a back plate or a frame may be necessary for the liquid crystal display panel, and a material that is thin but has high rigidity and low warpage is required. As countermeasures in such cases, magnesium thixo molding, die-cast metal or iron plate processed products are options, but it is difficult to use metal when lightening requirements, insulation requirements, and electromagnetic waves need to pass. .

  Instead of such metal or iron plate processed products, high-rigidity, high-strength thermoplastic injection molding materials with excellent mass productivity are used. As such a thermoplastic injection molding material, for example, a xylylenediamine-based polyamide resin obtained by polycondensation of α, ω-linear aliphatic dibasic acid and xylylenediamine (hereinafter abbreviated as “polyamide MX”). Resin compositions based on the main component have been proposed. However, the polyamide MX resin has a slow crystallization rate, and when a thin molded product is molded using the resin composition, the molded product has a low crystallinity. Therefore, it is necessary to increase the crystallinity by molding at a high mold temperature of 130 ° C. or higher, or by subjecting the molded product to an annealing treatment. In particular, when molding is performed at a higher mold temperature, the mold is thermally deformed and burrs are likely to occur in the molded product, and it is difficult to obtain a good molded product without advanced mold manufacturing technology. .

  For example, a polyamide resin composition for molding excellent in molding workability, which is obtained by blending glass fibers with a polyamide resin mixed with polyamide MX and polyamide 66, is proposed, and the crystallization speed is increased by blending polyamide 66. It is known that the molding cycle can be shortened (Patent Document 1). However, the polyamide MX used as an example is a polyamide resin obtained from metaxylylenediamine and adipic acid (hereinafter abbreviated as “polyamide MXD6”). When the polyamide 66 is blended with the polyamide MXD6, There may be inconveniences such as an increase in water absorption of the resin composition and a decrease in mechanical strength, and problems may remain in dimensional stability such as warpage and shrinkage when thin-walled moldability and thin-walled molded products are obtained.

  As a crystal nucleating agent to a polyamide resin (hereinafter abbreviated as “polyamide MP”) obtained from a mixed xylylenediamine composed of paraxylylenediamine and metaxylylenediamine and an α, ω-linear aliphatic dibasic acid. A resin composition containing talc has been proposed (Patent Document 2). However, since the polyamide 66 is not used in such a proposal, the heat resistance and water absorption characteristics of the resin composition, which is a problem in the above-described proposed technology, are improved, and the resin composition can be obtained without blending the polyamide 66. It is possible to increase the crystallization speed and improve the moldability. However, even in such a technique, it is necessary to raise the mold temperature to 130 ° C. at the time of molding, and further, when a thin molded product is molded, crystallization failure occurs.

  A resin composition comprising a polyamide resin obtained from xylylenediamine and an α, ω-linear aliphatic dibasic acid and boron nitride as a crystal nucleating agent has been proposed, and has a sufficient crystallization speed during molding. In order to obtain, when the ratio of paraxylylenediamine and metaxylylenediamine used for polycondensation of polyamide resin is 0 to 10/100 to 90 mol%, it is necessary to blend polyamide 66 in addition to boron nitride. It is taught that when the ratio of paraxylylenediamine to metaxylylenediamine is 10 to 45/90 to 55 mol%, it is not necessary to blend polyamide 66 (Patent Document 3).

  0 to 300 parts by weight of an inorganic filler, copper compound and / or 100 parts by weight of a mixed polyamide resin comprising 20 to 90% by weight of polyamide 6 resin and / or polyamide 66 resin and 10 to 80% by weight of aromatic polyamide resin Alternatively, a polyamide resin composition comprising 0.01 to 5 parts by weight of a halide is proposed, and the polyamide resin composition is particularly excellent in light resistance in addition to the excellent properties inherent in polyamide. In addition, it is taught that it can be used for exterior parts for railways, building materials and housing parts (Patent Document 4). As an example, a resin composition obtained by blending an inorganic filler, a copper compound, and a halide with a mixed polyamide resin composed of a polyamide 6 resin and an aromatic polyamide resin is mentioned. However, when molding a thin molded article having a thickness of about 1 mm, the crystallization speed is not sufficient even if the resin composition described in Patent Documents 3 and 4 is used, and the crystallization degree and warpage of the resulting thin molded article are not sufficient. And burr properties are not sufficient.

  It is molded using a molding material obtained by mixing a fibrous reinforcing material such as glass fiber or carbon fiber with a base material in which aromatic polyamide, amorphous polyamide, and polyamide 6 are mixed. An electronic equipment casing excellent in rigidity, toughness, and dimensional stability has been proposed (Patent Document 5). However, even if such a technique is used, a mold temperature of 130 ° C. or higher is required for molding the casing, and problems of burrs and poor crystallization still remain.

JP-A-51-63860 Japanese Patent Laid-Open No. 7-41669 JP 7-41670 A JP 2001-106902 A JP 2004-168849 A

  The present invention comprises a polyamide resin composition excellent in the crystallization speed, thin moldability, crystallinity, warpage, and burr properties of a thin molded product while maintaining the mechanical strength as polyamide MX. It is to provide a molded product.

  As a result of repeated studies to achieve the above object, the present inventors have found that the ratio of metaxylylenediamine and paraxylylenediamine in xylylenediamine, which is a raw material of polyamide MX (metaxylylenediamine / paraxylylenediamine). When the above-mentioned crystallization problem in thin-wall molding can be solved by a resin composition comprising a polyamide MP having a melting point of 245 ° C. or higher and a polyamide MP having an amine) of 90-50 / 10-50 mol% I got the knowledge. In addition, when the plate composition is further blended with the fibrous filler at a specific ratio as necessary, the low warpage performance required particularly for thin-walled portable electronic devices can be sufficiently satisfied. I got the knowledge.

  This invention is completed based on said knowledge, The 1st summary is polyamide MP (A) 30-80 weight%, melting | fusing point 245 degreeC or more polyamide resin (B) 20-70 weight%. (The total amount of both is 100% by weight), and further contains, as filler (C), a fibrous filler (C1) as an optional component and a plate-like filler (C2) as an essential component. The content ratio (C1) :( C2) of the filler (C1) and the plate-like filler (C2) is 0:10 to 9: 1, and the content of the filler (C) is the polyamide MP (A) and the polyamide resin. 30 to 250 parts by weight based on 100 parts by weight of the total of (B), and the polyamide MP (A) is 90 to 50 mol% of metaxylylenediamine and 10 to 50 mol% of paraxylylenediamine. And including And covering diamine, alpha, it consists in the polyamide resin composition, which is a polyamide resin obtained by polycondensation reaction between ω- linear aliphatic dibasic acid and / or aromatic dibasic acids.

  The second gist of the present invention resides in a molded article formed by molding the above resin composition, and the third gist is a condition that the mold temperature controller temperature is less than 90 ° C. In the manufacturing method of said molded article characterized by including the process shape | molded by this.

  According to the present invention, by improving the crystallization speed and thin moldability of the resin composition without impairing impact resistance, strength, rigidity, etc., burrs are generated in the molded product even at a low mold temperature of 130 ° C. or less. Therefore, a thin-wall molding is possible, and a polyamide resin composition excellent in mechanical strength, crystallization performance, and warpage and a thin-wall molded product comprising the same can be obtained. In particular, the polyamide resin composition of the present invention has an excellent low warpage performance in addition to the high rigidity and impact resistance required for portable electronic device parts. It is suitable for equipment parts use, for example, PDA, a portable game machine, a mobile phone, an ID card, an automobile electronic key, and the like.

<Polyamide resin composition>
Hereinafter, the present invention will be described in detail. The polyamide MP (A) used in the present invention is obtained by polycondensation of a mixed diamine mainly composed of xylylenediamine with an α, ω-linear aliphatic dibasic acid and / or an aromatic dibasic acid. Specifically, it is a polyamide resin, specifically, 50 to 90 mol% of metaxylylenediamine and 10 to 50 mol% of paraxylylenediamine, preferably 50 to 80 mol% of metaxylylenediamine and 20 to 50 mol of paraxylylenediamine. %, And a polyamide resin obtained by polycondensation of an α, ω-linear aliphatic dibasic acid and / or aromatic dibasic acid having 6 to 12 carbon atoms.

  In the above mixed diamine, diamines other than the above xylylenediamine, for example, aliphatic diamines such as tetramethylenediamine, 2-methylpentamethylenediamine, hexamethylenediamine, and aromatics such as metaphenylenediamine and paraphenylenediamine It may contain alicyclic diamines such as diamine, 1,3-bisaminomethylcyclohexane, 1,4-bisaminomethylcyclohexane, etc., and the proportion of diamines other than the above xylylenediamine (ratio in all diamines) Is usually 10 mol% or less, preferably 5 mol% or less.

  Examples of the α, ω-linear aliphatic dibasic acid and / or aromatic dibasic acid include glutaric acid, adipic acid, azelaic acid, sebacic acid, suberic acid, dodecanedioic acid, and isophthalic acid (I). Terephthalic acid (T) and the like. Among these, adipic acid, sebacic acid, suberic acid, dodecanedioic acid and the like are preferable, and adipic acid is more preferable.

  The relative viscosity of the polyamide MP (A) used in the present invention is usually in the range of 2.0 to 4.0, preferably 2.0 to 2.7. If the relative viscosity is too low (meaning that it has a low molecular weight), the physical properties of the resin are insufficient. On the other hand, if it is too high, molding is difficult, and if the relative viscosity exceeds 4.0, polyamide MP It becomes difficult to manufacture. In the present specification, the relative viscosity means a viscosity measured at a temperature of 23 ° C. using a resin concentration of 1 g / 100 ml prepared using 96% sulfuric acid as a solvent.

  The content of polyamide MP (A) is 30 to 80% by weight, preferably 30 to 70% by weight, based on 100% by weight in total of polyamide MP (A) and polyamide resin (B) having a melting point of 245 ° C. or higher. When the content of polyamide MP (A) is less than 30% by weight, the elastic modulus decreases, and when it exceeds 80% by weight, the crystallization speed during molding decreases.

  In the present invention, a polyamide resin (B) having a melting point of 245 ° C. or higher is blended with the polyamide MP (A) in order to obtain a resin composition with improved crystallization speed and crystallinity of the thin molded product.

  The melting point in the present invention is the temperature at the peak top of the endothermic peak observed by the differential scanning calorimetry (DSC) method. The endothermic peak is defined as an endothermic peak observed when the sample is heated and melted once to eliminate the influence of heat history as much as possible and then heated again. Specifically, it can be obtained in the following manner. The temperature is raised from 30 to 300 ° C. at a rate of 10 ° C./min, held at 300 ° C. for 2 minutes, and then lowered to 200 ° C. at a rate of 20 ° C./min. Further, the temperature is raised to 300 ° C. at a rate of 10 ° C./min, and the melting point is obtained from the peak top of the endothermic peak observed at the time of temperature rise. Moreover, melting | fusing point is 245 degreeC or more means that melting | fusing point measured by DSC is always 245 degreeC or more in the range of relative viscosity 2.0-4.0.

  Specific examples of the polyamide resin (B) having a melting point of 245 ° C. or higher include polyamide 66, 6T, 46, 66 / 6T, 6T / 6I, 66 / 6T / 6I, dibasic acids such as terephthalic acid, isophthalic acid, Examples include various high melting point polyamide resins obtained by adjusting the mixing ratio of hexamethylenediamine and methylpentadiamine as adipic acid and diamine. Among these, polyamide 66 is preferable because it is inexpensive and easily available, has a high crystallization rate, has good fluidity, and has the best thermal stability.

  The relative viscosity of the polyamide resin (B) having a melting point of 245 ° C. or higher is usually in the range of 2.0 to 4.0, preferably 2.0 to 2.7. When the relative viscosity is too low, the physical properties of the resin are insufficient. On the other hand, when the relative viscosity is too high, the moldability tends to decrease.

  The content of the polyamide resin (B) having a melting point of 245 ° C. or more is 20 to 70% by weight, preferably 30 to 70% with respect to 100% by weight in total of the polyamide MP (A) and the polyamide resin (B) having a melting point of 245 ° C. or more. % By weight. When the content of the polyamide resin (B) having a melting point of 245 ° C. or higher is less than 20% by weight, the crystallization speed at the time of molding is lowered, and when it exceeds 70% by weight, the elastic modulus is lowered.

  In addition to the polyamide MP (A) and the polyamide resin (B) having a melting point of 245 ° C. or higher, other polyamide resins may be added to the resin composition of the present invention. Examples of other polyamide resins include polyamide 6/66, 66 / 6I, 6 / 6T / 6I and the like from the viewpoint of improving the surface appearance. Moreover, it is good also as a polymer alloy by mix | blending another thermoplastic resin. Examples of other thermoplastic resins include modified polypropylene resins, polyethylene resins, and PPS resins from the viewpoint of improving chemical resistance and slidability of the main polyamide resin. Moreover, PPE resin, AS resin, ABS resin, PET resin etc. are mentioned from a viewpoint of impact resistance improvement.

  Content of said other polyamide resin and other thermoplastic resin is 50 weight% or less normally as a ratio in the sum total of polyamide MP (A) and polyamide resin (B), Preferably it is 40 weight% or less.

  In the present invention, the filler (C) is blended in order to improve the warpage performance, mechanical strength and rigidity of the molded product. That is, the plate-like filler (C2) is used alone or in combination with the fibrous filler (C1) and the plate-like filler (C2), and preferably both are blended at a specific ratio as described later. That is, the fibrous filler (C1) is a preferable optional component, and the plate filler (C2) is an essential component.

  The fibrous filler (C1) is a filler having a fibrous appearance, and specific examples thereof include inorganic fibers such as glass fiber, carbon fiber, and ceramic fiber, and metal fibers such as stainless steel fiber and brass fiber. And organic fibers such as liquid crystal Kevlar.

  In addition to the above, a powdery filler having an aspect ratio of 5 or more is also preferably used. Specific examples thereof include inorganic compound whiskers such as potassium titanate, aluminum borate, titanium oxide, and calcium carbonate, and minerals such as wollastonite having an aspect ratio of 5 or more. Since the aspect ratio changes in the compounding process, the “aspect ratio” referred to here is “aspect ratio of raw material”. Two or more of these fibrous fillers may be used in combination.

When the fibrous filler (C1) is a glass fiber, the composition of the glass fiber is arbitrary, but a composition capable of forming glass fiber is better than molten glass. Preferable compositions include E glass composition, C glass composition, S glass composition, alkali-resistant glass and the like. Although the tensile strength of glass fiber is arbitrary, 290 kg / mm < ² > or more is preferable. Usually, E glass is preferable because it is easily available.

  The glass fiber is preferably surface-treated with a silane coupling agent such as γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-aminopropyltriethoxysilane. The adhesion amount of the surface treatment agent is usually 0.01% by weight or more of the glass fiber weight.

  Furthermore, if necessary, a resin mixture having a film forming ability such as a fatty acid amide compound, a lubricant such as silicone oil, an antistatic agent such as a quaternary ammonium salt, an epoxy resin, an acrylic resin, or a urethane resin, and a film forming ability. It is also possible to use glass fibers that have been surface-treated with a combination of a resin having a heat stabilizer and a flame retardant.

  Examples of the plate filler (C2) include glass flake, mica, talc, clay, graphite, sericite, montmorillonite, plate calcium carbonate, plate alumina and the like. Two or more of these may be used in combination. Among these, glass flakes, mica, and talc are preferred from the viewpoint of the balance of bending characteristics, impact resistance, dimensional stability, fluidity, and product appearance. Since portable electronic device parts are often required to have particularly high impact resistance, it is most preferable to use glass flakes having the highest impact resistance.

  As glass flakes suitable as the plate-like filler (C2), those having an E glass composition and a C glass composition are available as general commercial products. The average particle size varies depending on the grade of each company, but it is a glass having a flat plate structure, preferably about several tens of μm to 1 mm, and more preferably about 50 to 800 μm. Moreover, you may use together 2 or more types of glass flakes from which an average particle diameter differs. Furthermore, the surface treatment is preferably performed with a silane coupling agent such as γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and the like. The amount is usually 0.01% by weight or more of the glass flake weight.

  Mica suitable as the plate-like filler (C2) may be natural mica or synthetic mica. Mica (mica) is roughly divided into muscovite and phlogopite, and both can be used in the present invention. As natural mica, those having an average particle diameter of 1000 μm for large particles and about 5 μm for small particles are commercially available. A synthetic mica having a thickness of about several μm is also available. In the present invention, any size can be used. From the viewpoint of surface appearance and dimensional stability, the size is usually 5 to 100 μm. Two or more types of mica having different average particle diameters may be used in combination. Moreover, the surface-treated thing and the thing converged in order to reduce bulk density can be used.

  Talc suitable as the plate filler (C2) is a mineral crystal mainly composed of magnesium silicate. There is no restriction | limiting in an average particle diameter, Arbitrary things can be used. When mix | blending for the purpose of the reinforcement effect of a resin composition, a thing with an average particle diameter of 3-100 micrometers is preferable. Moreover, you may use together 2 or more types of talc from which an average particle diameter differs. Further, a surface-treated one and a converged one to reduce the bulk density can be used. Talc exhibits an effect as a nucleating agent in addition to the reinforcing effect, and can improve the moldability by increasing the crystallization speed of the resin composition. In such a case, a part of the component (C2) (for example, about 0.3 to 5% by weight in the component (C2)) is talc having a small average particle size (for example, having an average particle size of about 1 to 10 μm). ) Is preferably used instead.

  When used as a reinforcing material, the content of the filler (C) is 30 to 250 parts by weight, preferably 60 parts per 100 parts by weight in total of polyamide MP (A) and polyamide resin (B) having a melting point of 245 ° C. or higher. It is -200 weight part, More preferably, it is 70-160 weight part. When the content is less than 30 parts by weight, mechanical properties such as rigidity and the effect of improving warpage are insufficient, and when the content exceeds 250 parts by weight, it becomes difficult to produce a resin composition.

  Moreover, the content ratio of the fibrous filler (C1) and the plate-like filler (C2) is 0:10 to 9: 1 as a weight ratio of (C1) :( C2), and the required low warpage level Although it depends on the balance of strength, it is preferably in the range of 1: 9 to 8: 2, more preferably 3: 7 to 7: 3. By setting the content ratio of the component (C1) and the component (C2) within the above range, it is preferable because both mechanical properties and warpage of the molded product can be effectively improved.

  A nucleating agent is preferably added to the resin composition of the present invention in order to increase the crystallization rate and improve moldability. There is no restriction | limiting in particular as a nucleating agent, A well-known inorganic nucleating agent and an organic nucleating agent can be used. The average particle size of the inorganic nucleating agent is usually 0.01 to 20 μm, preferably 0.1 to 7 μm. Content of a nucleating agent is 0.001-8 weight part normally with respect to a total of 100 weight part of a component (A) and a component (B), Preferably it is 0.01-4 weight part. When the content of the nucleating agent is less than 0.001 part by weight, the expected effect may not be obtained. When the content is more than 8 parts by weight, the effect as a foreign matter is expressed and the strength and impact value are reduced. There is a case.

  Moreover, in order to improve the mold release property at the time of shaping | molding, it is preferable to add a mold release agent to the resin composition of this invention. Specific examples of the releasing agent include long-chain aliphatic carboxylic acids having 14 or more carbon atoms such as stearic acid and palmitic acid and derivatives thereof (eg, esters, alkali metal salts, alkaline earth metal salts, amides, etc.), stearyl Higher aliphatic alcohols having 14 or more carbon atoms such as alcohol and derivatives thereof, amines having 14 or more carbon atoms such as stearylamine and derivatives thereof, waxes such as low molecular weight polyethylene wax, paraffin wax, silicone oil, silicone gum, etc. Can be mentioned. Content of a mold release agent is 0.03-1.5 weight part normally with respect to a total of 100 weight part of a component (A) and a component (B), Preferably it is 0.03-0.5 weight part. By setting the content within the above range, the effect of improving the releasability can be sufficiently exhibited, and the generation of gas during molding and the deterioration of the appearance of the molded product surface can be prevented.

  In addition to the above, various additives generally used in the polyamide resin composition, for example, flame retardants, stabilizers, pigments, dyes, weather resistance improvers, and the like can be appropriately added as necessary.

  For example, examples of the flame retardant include known phosphorus-based, halogen-based, and silicon-based flame retardants. As the stabilizer, common copper halide (for example, copper iodide, copper chloride, copper bromide) and / or alkali metal halide (for example, potassium iodide, potassium bromide, etc.) stabilizer for polyamide resins. Mixtures and organic stabilizers (for example, hindered phenols, phosphites, etc.) can be mentioned.

  Further, for the purpose of suppressing an undesired amide exchange reaction between the polyamide MP (A) and the polyamide resin (B) having a melting point of 245 ° C. or more which causes a decrease in physical properties, for example, paragraphs of JP-A-2003-105095 It is also effective to use an amide exchange inhibiting stabilizer such as an inorganic acid salt of a metal of group 1 or 2 of the periodic table of elements or a hydroxide thereof as described in the number [0014].

  Content of said stabilizer is 0.01-5 weight part normally with respect to a total of 100 weight part of a component (A) and a component (B), Preferably it is 0.1-2 weight part. When the content is less than 0.01 parts by weight, the thermal discoloration improvement and the weather resistance / light resistance improvement effect may be insufficient, and when the content exceeds 5 parts by weight, the mechanical properties decrease. Sometimes. These stabilizers may be used in combination of two or more.

  In addition, an elastomer can be added to the resin composition of the present invention in order to further improve the impact strength. Examples of the elastomer include polyolefin elastomers, diene elastomers, polystyrene elastomers, polyamide elastomers, polyester elastomers, polyurethane elastomers, fluorine elastomers, and silicon elastomers. Among these, polyolefin elastomers or polystyrene elastomers are preferable. When these elastomers are used after being modified for compatibilization with polyamide, the effect is further enhanced. Modification with an acid (preferably maleic acid or maleic anhydride), epoxy modification, and the like are suitable modifications for the resin composition of the present invention. The content of the elastomer is usually 0.5 to 20 parts by weight, preferably 0.5 to 10 parts by weight with respect to 100 parts by weight as the total of the component (A) and the component (B).

  The method for producing the resin composition of the present invention is not particularly limited, and the above components (A), (B) and (C2) are usually added, and the component (C1) added as necessary. And other additives are blended in a predetermined amount, and melt-kneaded. The melt kneading method may be any known method. For example, pellets can be produced by using a single-screw or twin-screw extruder, a Banbury mixer, or a similar device, and charging all materials from the root of the extruder and melting and kneading them together. In addition, component (C2) and, if necessary, component (C1) are side-feeded and kneaded while adding component (A) and component (B) and other components added as necessary and melting them. The method, components (A), (B), (C2) and other components added as necessary are added and melted, and if necessary, the component (C1) is side-feeded and kneaded. Can also be adopted. In addition, two or more kinds of compounds having different additives and compositions may be pellet blended to produce a resin composition pellet blend within the composition range defined in the present invention, or a part of powder component and liquid component may be added. A method of blending separately can also be employed.

<Molded product and manufacturing method thereof>
The resin composition of the present invention can be formed into various molded articles by molding methods generally used for thermoplastic resin compositions, that is, injection molding methods, hollow molding methods, extrusion molding methods, and the like. Since it is excellent in fluidity and mechanical properties, it is particularly useful as a thin molded product by an injection molding method. The resulting thin-walled molded product has both high impact resistance and rigidity, as well as low anisotropy and low warpage. Therefore, portable computers such as electronic notebooks and PADs, pagers, and mobile phones. It is a component such as an internal structure or a casing used for portable electronic devices such as telephones and PHS, and is particularly suitable for a plate-shaped component.

  The plate shape referred to in the present invention refers to a thin plate shape as a whole, and the cross section may be slightly curved or curved. Further, for the sake of functionality and design, it may be provided with irregularities, windows, holes, and the like. In particular, the product shape of the portable electronic device as described above is thin, and many parts such as internal structures and housings can be said to be substantially plate shapes except for a rib portion and a hinge portion. For example, in the case of a foldable mobile phone casing, the overall shape is substantially plate-like except for the rib portion and the hinge portion. There may be a large number of holes, bosses and the like in this part, but in the present invention, if such a part is less than 50% of the entire area, it is assumed that the part has a plate shape. Among them, the resin composition of the present invention is suitable for a part having a flat plate shape having an average thickness of 1.2 mm or less excluding ribs, bosses, and hinges, because low warpage is desired. Among these, the resin composition of the present invention is particularly suitable for a flat plate (base) that supports internal structural components incorporated in a portable electronic device.

  In addition, since the resin composition of the present invention is excellent in crystallization performance, for example, when a portable electronic device part is produced by injection molding using the resin composition of the present invention, usually sufficient crystallinity is obtained. Mold temperature controller temperature that is difficult to obtain, specifically less than 130 ° C., more preferably less than 110 ° C., and even less than 90 ° C. It is possible to manufacture parts having a crystallinity of 28% or more. In particular, when the thickness of the part is thin, specifically, when the thickness is 1.2 mm or less, this tendency is remarkable.

  When the EMI shielding property is required for the portable electronic device component of the present invention, carbon fiber, metal fiber, or metal-plated glass fiber, carbon fiber, or organic fiber is used as the fibrous filler (C1). It is preferable to do. Further, the EMI shielding property can be imparted to the portable electronic device component of the present invention by conducting conductive coating, metal plating or metal vapor deposition.

  EXAMPLES The present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to these examples unless it exceeds the gist. The materials used in the following examples are as follows.

(A-1) Polyamide MP: produced according to the following production example.

  730 g of adipic acid was charged into a 3 liter flask equipped with a stirrer, thermometer, reflux condenser, raw material dripping device, heating device, etc., and the temperature inside the flask was raised to 160 ° C. in a nitrogen atmosphere. The acid was melted. Into the flask, 680 g of mixed xylylenediamine containing 30 mol% of paraxylylenediamine and 70 mol% of metaxylylenediamine was successively added dropwise over about 2.5 hours. During this time, the reaction was continued with stirring while maintaining the internal temperature always above the melting point of the product, and the temperature was raised to 270 ° C. at the end of the reaction. Water generated by the reaction was discharged out of the reaction system by a partial condenser. After completion of the dropwise addition, the reaction was continued by stirring at a temperature of 275 ° C., and the reaction was terminated after 1 hour. The product was removed from the flask, cooled with water and pelletized. The obtained polyamide resin had a melting point of 258 ° C., a crystallization temperature of 216 ° C., and a relative viscosity (measured in a 96% sulfuric acid solution at a concentration of 1 g / 100 ml at 23 ° C.) of 2.08.

(A-2) Polyamide MXD6: Mitsubishi Gas Chemical Co., Ltd. product, trade name “Polyamide MXD6 # 6000”, polyamide resin produced from metaxylylenediamine and adipic acid, melting point 243 ° C., crystallization temperature 206 ° C., relative Viscosity 2.14

(B-1) Polyamide 66: DuPont product, trade name “Zytel 101”, melting point 264 ° C., relative viscosity 3.0

(B-2) Polyamide 6: Mitsubishi Engineering Plastics Co., Ltd., trade name “Novamid (registered trademark) 1007J”, melting point 225 ° C., relative viscosity 2.14

(B-3) Polyamide 46: manufactured by DSM, trade name “Stanyl”, melting point 295 ° C.

(C1) Glass fiber: Chopped strand, manufactured by Asahi Fiber Glass Co., Ltd., trade name “CS03JAFT2”, average fiber diameter 10 μm, average fiber length 3 mm (manufacturer nominal value)

(C2-1) Glass flake: manufactured by Nippon Sheet Glass Co., Ltd., trade name “Fureka REFG-301”, average particle diameter of about 600 μm (manufacturer nominal value).

(C2-2) Mica (phlogopite): manufactured by Hayashi Kasei Co., Ltd., trade name “Mica B82”, average particle diameter 82 μm (manufacturer nominal value)

(C2-3) Talc A: Hayashi Kasei Co., Ltd., trade name “Micron White 5000A”, average particle diameter 4.1 μm (manufacturer nominal value)

(C2-4) Talc B: manufactured by Hayashi Kasei Co., Ltd., trade name “micelleton”, average particle size 1.4 μm (manufacturer nominal value)

  Mold release agent: Montanate ester wax, manufactured by Clariant Japan, trade name “Licowax E”

  Examples 1-9 and Comparative Examples 1-16:

(1) Preparation of resin composition pellets:
Each component excluding the fibrous filler (C1) is weighed so as to have the composition shown in Tables 1 to 3 below, blended with a tumbler, and then a twin-screw extruder “TEM35B (barrel 10 block configuration) manufactured by Toshiba Machine Co., Ltd.” ”And melted. Thereafter, the component (C1) was side-fed from the seventh block counted from the hopper side to prepare a resin composition pellet. The temperature setting of the extruder was uniformly 280 ° C.

(2) Evaluation of bending strength, flexural modulus and Charpy impact strength:
<Molding of ISO test piece>
After drying the pellets of each resin composition obtained by the above method at 80 ° C. for 48 hours, using a FANUC injection molding machine “100T”, cylinder temperature 280 ° C., mold temperature controller temperature 130 ° C., Under the conditions of an injection time of 20 seconds and a cooling time of 15 seconds, VP switching was performed when about 95% resin was filled, and the holding pressure was set to a higher 620 kgf / cm ² × 25 seconds within a range where no burr occurred, and an ISO test piece was molded. In order to use the obtained ISO test piece for a bending test and a Charpy impact test, both ends were cut and a notch cut was performed in accordance with the method described in ISO.

<Evaluation>
Using the test specimen for evaluation obtained above, the bending strength and the flexural modulus were measured according to the ISO178 standard, and the notched Charpy impact strength was measured according to the ISO179 standard. The results are shown in Tables 1-3. The desired performance of the molded article of the present invention is that the bending strength is 150 MPa or more, the flexural modulus is 10 GPa or more, and the notched Charpy impact strength is 2 MPa or more.

(3) Warpage evaluation:
<Molding of molded product for evaluation>
After each resin composition pellet obtained by the above method was dried at 80 ° C. for 48 hours, an injection molding machine “100T” manufactured by FANUC was used, the cylinder temperature was 280 ° C., the holding pressure was 620 kgf / cm ² × 25 seconds, Under conditions of injection time of 15 seconds and cooling time of 30 seconds, the mold temperature controller temperature is changed to 80 ° C, 100 ° C, 130 ° C, and the measurement value and VP switching position are adjusted. The mold cavity was filled with resin from a fan gate having a side of 100 mm and a thickness of 0.8 mm, and the following molded article for evaluation was molded.

<Evaluation of warpage>
After cooling the molded article for evaluation, the molded article removed from the mold without cutting the gate portion was left overnight at 25 ° C. and a humidity of 65%. Then, the said molded article was set | placed on the horizontal surface, the fan gate side was made into the reference | standard, the height of the end surface on the opposite side was made into the height of lifting, and the following references | standards evaluated. The evaluation results are shown in Tables 1-3.

○: Lifting height ≦ 0.5 mm
Δ: 0.5 mm <lifting height ≦ 2.0 mm
X: 2.0 mm <height of lifting (however, the sign “−” in the table was “x” or “Δ” in the next evaluation of releasability, so the warpage was not evaluated) Means.)

(4) Evaluation of releasability:
The mold release during ejection when molding was performed under the same conditions as the molding conditions for the evaluation molded product in (3) above was evaluated according to the following criteria. The evaluation results are shown in Tables 1-3.

○: When there is no particular problem △: When the mold can be released while being deformed ×: The ejector contact part of the molded product is pierced by the ejector or greatly deformed and stuck to the mold and must be peeled off manually. If not

(4) Evaluation of crystallinity:
Crystallinity was evaluated by the crystallinity obtained by DSC. In DSC, when a material is melted or vaporized by raising the temperature, the melting point, heat amount, and crystallization state can be examined by observing the generation or absorption of the heat amount of the material. Evaluation was made by the following method.

  Approximately 10 mg from the center of the molded product obtained by adopting the same conditions as the molding conditions for the molded product for evaluation in (3) above and changing the mold temperature controller temperature to 80 ° C., 100 ° C., and 130 ° C. The molded product was cut out, the obtained molded product was heated from 30 ° C. to 300 ° C. by DSC, the calorific value of the exothermic peak and the endothermic peak at the time of temperature elevation was obtained, and the crystallinity was obtained by the following formula (1). It was.

  Crystallinity (%) = (heat quantity of endothermic peak (J / g) −heat quantity of exothermic peak (J / g)) / (theoretical heat of fusion (J / g) in each resin composition) × 100 (1) )

  The method for measuring the theoretical heat of fusion in the present invention is as follows. That is, the endothermic peak calories at the melting points of polyamide resins having various crystallinities are measured by DSC, and the obtained endothermic peak calories and crystallinity are plotted on two axes to create a calibration curve. The amount of heat at the extrapolation point of 100% of the crystallinity of the line was defined as the theoretical heat of fusion. In addition, the crystallinity degree of the polyamide resin used for DSC measurement employ | adopted the density gradient tube method generally used, and measured it based on JISK7112.

When the degree of crystallinity is 28% or more, it is determined that the crystallization of the molded product has sufficiently progressed. When the degree of crystallinity is 25% or more and less than 28%, crystallization of the molded product is slightly insufficient, but it is determined that there is no problem as an actual molded product. When the crystallinity is 15% or more and less than 25%, the crystallization of the molded product is insufficient, and it is judged that there is a problem as an actual molded product. When the degree of crystallinity is less than 15%, the molded product is hardly crystallized, and it is determined that it cannot be used as an actual molded product.
The results are shown in Tables 1-3.

<Evaluation of burr properties>
Using the same molding conditions as those for the molded article for evaluation in (3) above, the molded article obtained by changing the mold temperature controller temperature to 80 ° C, 100 ° C, and 130 ° C was visually checked for burrs. Observed. When burrs existed, the maximum length of burrs existing in a 10 mm region from the fan gate side in the resin flow direction was measured with calipers and evaluated according to the following criteria. The results are shown in Tables 1-3.

◎: No burr ○: Burr exists mainly near the fan gate, and burr length ≦ 100μm
Δ: Burr exists mainly in the vicinity of the fan gate, 100 μm <Burr length ≦ 500 μm
×: Burr exists mainly in the vicinity of the fan gate, 500 μm <Burr length XX: Burr exists on the entire surface of the molded product

  The results show the following.

(1) Polyamide MP, polyamide 66, and Examples 1 to 9 in which the content of the filler is within the range defined by the present invention are rigid, impact resistance, mold release, crystallinity of molded product, and low warpage performance. Excellent and almost no burr is generated.

(2) Comparative Examples 1 to 8, in which polyamide MXD6 is used instead of polyamide MP of Examples 1 to 8 and the contents of polyamide MXD6 and polyamide 66 are within the range defined in the present invention, Examples 1 to 8 Further, the crystallinity of the thin molded product is inferior, and burrs tend to occur. The decrease in crystallinity is particularly great when molding is performed at a low mold temperature.

(3) Although the content ratio of polyamide MP and polyamide 66 is within the range specified in the present invention, the comparative example 9 in which the content ratio of fibrous filler and plate-like filler is outside the range specified by the present invention is polyamide MP. And the composition ratio of polyamide 66 are equal, the filler content is similar, and the warpage of the molded product is higher than in Examples 1 to 3 in which the content ratio of the fibrous filler and the plate-like filler is within the range defined by the present invention. Sexuality decreases.

(4) Polyamide MXD6 is used instead of polyamide MP, and Comparative Examples 10 to 12 in which the contents of polyamide MXD6 and polyamide 66 are outside the range defined in the present invention are releasability, warpage of a thin molded product, Crystallinity is inferior and burrs are likely to occur. In particular, when the mold temperature is low, the crystallinity of the molded product is low.

(5) Further, when Example 1 is compared with Comparative Examples 13 and 14, it can be seen that the combined use of polyamide MP and polyamide 66 as the polyamide resin improves the crystallinity of the molded product and reduces the occurrence of burrs. . The improvement in crystallinity is particularly remarkable when molding is performed at a low mold temperature.

(6) Comparative Examples 15 and 16 in which polyamide 6 having a melting point of 225 ° C. is blended instead of polyamide 66 are inferior in crystallinity, warpage, and burr properties of the molded product as compared with Examples 1 and 3.

  As described above, when the content ratio of the polyamide MP and the polyamide 66 is within the range defined by the present invention and a plate-like filler is used, preferably, a fibrous and plate-like filler are used in combination at a specific ratio. It can be seen that the object of the present invention can be achieved.

  According to the present invention, the crystallization speed and thin moldability of the resin composition can be improved, thin molding can be performed at a low mold temperature that does not reach 130 ° C., and the generation of burrs is small, and the deburring process. Can be omitted, and production at low cost becomes possible. Since the resin composition of the present invention has excellent low warpage performance in addition to high rigidity and impact resistance required for portable electronic device parts, it is used for portable electronic device parts having a circuit board inside, for example, It is suitable for PDAs, portable game machines, cellular phones, ID cards, electronic keys for automobiles, and the like.

Claims (11)

  Polyamide MP (A) 30 to 80% by weight, melting point 245 ° C. or higher polyamide resin (B) 20 to 70% by weight (the total amount of both is 100% by weight), Furthermore, as filler (C), The fibrous filler (C1) as an optional component and the plate-like filler (C2) as an essential component are contained, and the content ratio (C1) :( C2) of the fibrous filler (C1) and the plate-like filler (C2) is 0. 10 to 9: 1, and the content of the filler (C) is 30 to 250 parts by weight with respect to a total of 100 parts by weight of the polyamide MP (A) and the polyamide resin (B). (A) is a mixed diamine containing 90 to 50 mol% of metaxylylenediamine and 10 to 50 mol% of paraxylylenediamine, an α, ω-linear aliphatic dibasic acid and / or aromatic. With dibasic acid A polyamide resin composition, which is a polyamide resin obtained by a polycondensation reaction.   The polyamide resin composition according to claim 1, wherein the content ratio (C1) :( C2) of the fibrous filler (C1) to the plate-like filler (C2) is 0:10 to 9: 2.   The polyamide resin composition according to claim 1 or 2, wherein the polyamide resin (B) having a melting point of 245 ° C or higher is polyamide 66.   The polyamide resin composition according to any one of claims 1 to 3, wherein the fibrous filler (C1) is at least one selected from the group of glass fibers, carbon fibers, and inorganic compound whiskers.   The polyamide resin composition according to any one of claims 1 to 4, wherein the plate-like filler (C2) is at least one selected from the group consisting of glass flakes, mica and talc.   The polyamide resin composition according to any one of claims 1 to 3, wherein the fibrous filler (C1) is glass fiber and the plate-like filler (C2) is glass flake.   The polyamide resin composition according to any one of claims 1 to 6, which is used for portable electronic devices.   A molded article comprising the polyamide resin composition according to any one of claims 1 to 7.   The molded product according to claim 8, wherein the molded product has a flat plate shape, and an average thickness of portions excluding ribs, bosses, and hinge portions is 1.2 mm or less.   The molded article according to claim 8 or 9, wherein the crystallinity is 28% or more.   The method for producing a molded product according to any one of claims 8 to 10, comprising a step of molding under a condition that the mold temperature controller temperature is less than 90 ° C.