Polyamide composition and molded article

Abstract

The purpose of the present invention is to provide a polyamide composition with which it is possible to avoid an excessive decrease in adhesiveness (i.e., adhesive strength) between a molded article and an object (e.g., an interstitial filler) on the molded article, said excessive decrease being likely to occur when the molded article is exposed to a high-temperature environment for a long period of time. The polyamide composition contains a polyamide, a fibrous inorganic reinforcing material, and a thermally conductive inorganic filler. When left to stand for 1000 hours in an environment at a temperature of 150 DEG C, the ratio of the peak area of 1750 cm-1 to 1700 cm-1 to the peak area of 1665 cm-1 to 1630 cm-1 in the infrared absorption spectrum is 0.10 or less. Here, the "infrared absorption spectrum" is an infrared absorption spectrum having a depth of 50 [mu] m from the surface of a molded article when the molded article is molded using the polyamide composition into a molded article having an arithmetic average roughness (Ra) of 0.1 [mu] m and then left to stand for 1000 hours in an environment at a temperature of 150 DEG C.

Description

Technical Field

[0001] This invention relates to polyamide compositions and molded articles. Background Technology

[0002] With the surge in demand for resin-based electronic devices and light-emitting diodes (LEDs), the miniaturization of components, and the increasing capacity and / or long lifespan of batteries in battery electric vehicles (BEVs), efficiently dissipating heat generated inside electronic devices has become an important issue.

[0003] As one solution, a highly heat-dissipating gap filler is sometimes introduced between the heat-generating electrical and electronic components (such as batteries and motors) and the housing components. By using the gap filler to fill cavities (i.e., spaces where air hardly flows) and / or gaps, the heat generated by the electrical and electronic components can be efficiently transferred to surrounding components (such as battery-related components), thus enabling efficient heat dissipation.

[0004] As peripheral components of batteries (such as battery casings and base plates for battery modules), resin molding is sometimes studied from the perspectives of lightweighting, production cycle, and shape freedom. As for resins, engineering plastics, especially polyamides with high heat resistance, are frequently researched.

[0005] Because high thermal conductivity is required for battery peripheral components, polyamides are typically blended with a large amount of inorganic materials with high heat dissipation properties (i.e., inorganic materials with high thermal conductivity). However, polyamide compositions containing a large amount of inorganic materials sometimes solidify during injection molding with the inorganic materials exposed on the surface. In the case of glass as the inorganic material, this is called glass float, a type of molding defect (see Patent Document 1 for information on inorganic material float). When this molding defect occurs, strong impacts or shaking of the battery can easily cause the separation of gap fillers, etc., which may lead to defects caused by this separation (e.g., misalignment between the battery and battery peripheral components). As a result, cavitation is created between the battery and battery peripheral components, thereby reducing heat dissipation and potentially shortening the battery's lifespan. The same concern exists for peripheral components of electrical and electronic components other than the battery, such as those of motors.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent No. 6518587

[0009] Patent Document 2: Japanese Patent No. 6249565

[0010] Patent Document 3: Japanese Patent No. 5993824 Summary of the Invention

[0011] The problem the invention aims to solve

[0012] Molded parts used as peripheral components of electrical and electronic components (such as batteries and motors) in battery electric vehicles (BEVs) tend to be exposed to high-temperature environments for extended periods. Therefore, it is required that molded parts used as peripheral components of electrical and electronic parts be able to dissipate heat through gap fillers not only before but also after prolonged exposure to high temperatures. This requirement is becoming increasingly stringent with the increasing prevalence and performance-oriented development of battery electric vehicles (BEVs).

[0013] The object of this invention is to provide a polyamide composition capable of preventing excessive reduction in the adhesion (i.e., adhesive strength) between the molded article and objects on the molded article (e.g., gap fillers) that may occur when the molded article is exposed to a high-temperature environment for a prolonged period. A further object of this invention is to provide a molded article capable of preventing excessive reduction in the adhesion (i.e., adhesive strength) between the molded article and objects on the molded article (e.g., gap fillers) that may occur when the molded article is exposed to a high-temperature environment for a prolonged period.

[0014] Solution for solving the problem

[0015] In order to solve this problem, the present invention has the following [1] configuration. [1]

[0017] A polyamide composition comprising polyamide, fibrous inorganic reinforcement, and thermally conductive inorganic filler.

[0018] When the polyamide composition is placed at 150°C for 1000 hours, the infrared absorption spectrum at 1750 cm⁻¹... -1 ~1700cm -1 The area of ​​the peak (hereinafter sometimes referred to as "peak A") relative to 1665 cm⁻¹ -1 ~1630cm -1 The proportion of the area of ​​peak B (hereinafter sometimes referred to as "peak B") is less than 0.10.

[0019] When the polyamide composition is placed at 150°C for 1000 hours, the difference in its arithmetic mean roughness (Ra) before and after is less than 1.5 μm in absolute value.

[0020] Here, "infrared absorption spectrum" refers to the infrared absorption spectrum at a depth of 50 μm from the surface of the molded article after the polyamide composition is molded into a molded article with an arithmetic mean roughness (Ra) of 0.1 μm and placed at a temperature of 150°C for 1000 hours.

[0021] The difference in arithmetic mean roughness (Ra) is determined by the following steps: After making a flat molded article with an arithmetic mean roughness (Ra) of 0.1 μm using a polyamide composition, the flat molded article is placed at a temperature of 150°C for 1000 hours, and then the arithmetic mean roughness (Ra) is measured.

[0022] According to [1], the strength of molded articles can be improved by fibrous inorganic reinforcing materials, specifically by improving the flexural strength of molded articles.

[0023] Moreover, thermally conductive inorganic fillers can improve the thermal conductivity of molded products, that is, the heat dissipation of molded products.

[0024] Furthermore, by maintaining a peak area ratio below 0.10, excessive degradation of the adhesion between the molded product and objects on it (such as interstitial fillers) that may occur when the molded product is exposed to high temperatures for extended periods can be avoided. This is because the degree of polyamide degradation during prolonged exposure to high temperatures can be reduced. This will be explained further. 1750cm -1 ~1700cm -1 The peak (peak A) is enlarged due to the deterioration of the polyamide. On the other hand, the 1665 cm⁻¹ peak... -1 ~1630cm -1 The peak (i.e., peak B) is the peak originating from the carbonyl group of the amide bond. Therefore, in the infrared absorption spectrum after being placed at 150°C for 1000 hours, the smaller the ratio of the area of ​​peak A to the area of ​​peak B (i.e., peak A area / peak B area), the less the polyamide deteriorates. According to [1], since this ratio, i.e., the peak area ratio, is less than 0.10, the degree of deterioration of the polyamide on and / or near the surface of the molded article when the molded article is exposed to a high temperature environment for a long time can be reduced. Therefore, the detachment of thermally conductive inorganic fillers and fibrous inorganic reinforcing materials and the generation of cracks that may occur when the molded article is exposed to a high temperature environment for a long time can be reduced. That is, the degree of deterioration of the smoothness of the molded article when the molded article is exposed to a high temperature environment for a long time can be reduced. As a result, the excessive reduction of the adhesion between the molded article and objects (e.g., gap fillers) on the molded article that may occur when the molded article is exposed to a high temperature environment for a long time can be avoided.

[0025] Furthermore, the difference in arithmetic mean roughness (Ra) is less than 1.5 μm in absolute value. That is, the difference between the arithmetic mean roughness (Ra) after being placed at 150°C for 1000 hours and the arithmetic mean roughness (Ra) before placement (specifically, before being placed at 150°C for 1000 hours) is less than 1.5 μm. Therefore, it is possible to further avoid excessive reduction in the adhesion between the molded article and objects on the molded article (such as gap fillers) that may occur when the molded article is exposed to a high temperature environment for a long time.

[0026] The present invention preferably has the following configurations [2] to

[13] . [2]

[0028] The polyamide composition according to [1] has a flexural strength of 120 MPa or more and a thermal conductivity of 0.60 W / m·K or more.

[0029] Here, the flexural strength is a value measured after preparing test pieces using the polyamide composition. The thermal conductivity is a value measured after preparing disc-shaped samples using the polyamide composition.

[0030] According to [2], when molded articles are used as peripheral components of electrical and electronic components (e.g., batteries, motors), they can have appropriate mechanical properties and thermal conductivity. [3]

[0032] According to the polyamide composition of [1] or [2], wherein the difference is less than 1.0 μm in absolute value.

[0033] According to [3], it is possible to further avoid the excessive reduction in adhesion between the molded article and objects on the molded article (such as gap fillers) that may occur when the molded article is exposed to high temperature environment for a long time. [4]

[0035] The polyamide composition according to any one of [1] to [3] further comprises an antioxidant and a stabilizer. [5]

[0037] The polyamide composition according to any one of [1] to [4], wherein the polyamide comprises a crystalline polyamide.

[0038] According to [5], it is possible to improve the mechanical properties of polyamide compositions. [6]

[0040] The polyamide composition according to any one of [1] to [5], wherein the relative viscosity of the polyamide is 2.0 or more and 3.6 or less.

[0041] Here, the relative viscosity is the value measured according to JIS K6920-2:2009, using 98% sulfuric acid at a sample (i.e., polyamide) of 1 g / dL and 25°C.

[0042] According to [6], when the polyamide composition is melted and flowed for injection molding, the polyamide composition can exhibit preferred flowability for injection molding. [7]

[0044] The polyamide composition according to any one of [1] to [6], wherein the content of the thermally conductive inorganic filler is 35% by mass or more.

[0045] According to [7], it is possible to further improve the thermal conductivity of the molded product, that is, the heat dissipation of the molded product. [8]

[0047] The polyamide composition according to any one of [1] to [7], wherein the thermally conductive inorganic filler has been surface treated.

[0048] Regarding [8], thermally conductive inorganic fillers can be surface-treated, for example, with compounds that readily react with carboxylic acid groups and / or carboxylic anhydride groups. By surface-treating thermally conductive inorganic fillers with compounds that readily react with carboxylic acid groups and / or carboxylic anhydride groups, mechanical properties and thermal conductivity can be equally (i.e. uniformly) exhibited in polyamide compositions and / or molded articles, and the deterioration of the smoothness of molded articles when exposed to high temperatures for extended periods can be further reduced. This will be explained. By surface-treating thermally conductive inorganic fillers with compounds that readily react with carboxylic acid groups and / or carboxylic anhydride groups, the affinity of thermally conductive inorganic fillers for polyamides can be improved, thereby improving the dispersibility and adhesion of thermally conductive inorganic fillers. Improved dispersibility contributes to the equally (i.e. uniformly) exhibited mechanical properties and thermal conductivity in polyamide compositions and / or molded articles. On the other hand, improved adhesion helps increase the interfacial strength between the thermally conductive inorganic filler and the polyamide, thus reducing the detachment of the thermally conductive inorganic filler that may occur when the molded product is exposed to high temperature for a long time. Therefore, it can further reduce the deterioration of the smoothness of the molded product when it is exposed to high temperature for a long time. [9]

[0050] The polyamide composition according to any one of [1] to [8] is used as a raw material for a molded article in which a gap filler is provided.

[10]

[0052] The polyamide composition according to any one of [1] to [9] further comprises a phenolic antioxidant and a copper compound.

[0053] According to

[10] , the degree of degradation of polyamide on and / or near the surface of the molded article when it is exposed to high temperature for a long time can be effectively reduced. Therefore, it is possible to further avoid the excessive reduction of adhesion between the molded article and objects (e.g., gap fillers) that may occur when the molded article is exposed to high temperature for a long time. This will be explained. When the molded article is exposed to high temperature for a long time, free radicals are sometimes generated at a rate that exceeds the free radical capture rate of phenolic antioxidants. That is, the amount of free radicals generated per unit time sometimes exceeds the amount of free radicals captured per unit time by phenolic antioxidants. By using copper compounds with phenolic antioxidants, the polyamide can be stabilized, thereby reducing the oxidative degradation of the polyamide caused by free radicals that are not captured by phenolic antioxidants. Therefore, the degree of degradation of polyamide on and / or near the surface of the molded article when it is exposed to high temperature for a long time can be effectively reduced, thereby further reducing the deterioration of the smoothness of the molded article. As a result, it is possible to further avoid excessive reduction in the adhesion between the molded part and objects on the molded part (such as gap fillers) that may occur when the molded part is exposed to high temperature environment for a long time.

[11]

[0055] According to the polyamide composition described in

[10] , wherein the phenolic antioxidant has a hindered structure,

[0056] The copper compound is at least one selected from the group consisting of copper acetate, copper iodide, and copper bromide.

[0057] According to

[11] , by giving the phenolic antioxidant a hindered structure, the reaction rate with free radicals that cause oxidative degradation of the molded surface can be prevented from becoming too fast, thus allowing the phenolic antioxidant to exert its oxidative degradation effect for a longer period of time. By making the copper compound at least one selected from the group consisting of copper acetate, copper iodide, and copper bromide, the polyamide can be further stabilized, thus further reducing the oxidative degradation of the polyamide caused by free radicals not captured by the phenolic antioxidant.

[12]

[0059] The polyamide composition according to any one of [1] to

[11] further comprises a release agent.

[0060] According to

[12] , when a polyamide composition is molded using a mold (e.g., in the case of injection molding), the molded article can be easily removed from the mold. Therefore, even when the molded article is formed into a complex shape, it is possible to easily remove the molded article from the mold.

[13]

[0062] A molded article obtained by molding the polyamide composition described in any one of [1] to

[12] .

[0063] In order to solve the above problems, the present invention may also have the following

[14] configuration.

[14]

[0065] A polyamide composition comprising polyamide, fibrous inorganic reinforcing material, thermally conductive inorganic filler, phenolic antioxidant, and copper compound.

[0066] According to

[14] , the strength of molded articles can be improved by fibrous inorganic reinforcing materials, specifically by improving the flexural strength of molded articles.

[0067] Moreover, thermally conductive inorganic fillers can improve the thermal conductivity of molded products, that is, the heat dissipation of molded products.

[0068] Furthermore, by using phenolic antioxidants and copper compounds, excessive reduction in the adhesion between the molded article and objects on the molded article (such as interstitial fillers) that may occur when the molded article is exposed to high temperatures for extended periods can be avoided. This will be explained below. As mentioned above, by using copper compounds, the polyamide can be stabilized, thus reducing oxidative degradation of the polyamide caused by free radicals not captured by the phenolic antioxidants. Therefore, the degree of degradation of the polyamide on and / or near the surface of the molded article when it is exposed to high temperatures for extended periods can be effectively reduced, thereby reducing the deterioration of the smoothness of the molded article. As a result, excessive reduction in the adhesion between the molded article and objects on the molded article (such as interstitial fillers) that may occur when the molded article is exposed to high temperatures for extended periods can be avoided.

[0069] The present invention preferably has the following configuration

[15] .

[15]

[0071] A molded article obtained by molding the polyamide composition described in

[14] .

[0072] The effects of the invention

[0073] Polyamide compositions can be provided that can prevent excessive reduction in the adhesion (i.e., adhesive strength) between the molded article and objects on the molded article (e.g., gap fillers) that may occur when the molded article is exposed to high temperatures for extended periods. Molded articles can also be provided that can prevent excessive reduction in the adhesion (i.e., adhesive strength) between the molded article and objects on the molded article (e.g., gap fillers) that may occur when the molded article is exposed to high temperatures for extended periods. Attached Figure Description

[0074] Figure 1The photograph is taken when the surface of the flat plate molded in Example 1 was observed under a microscope after being treated at 150°C for 1000 hours.

[0075] Figure 2 The photograph is taken under a microscope when the surface of the flat molded product formed in Comparative Example 2 was observed after being treated at 150°C for 1000 hours. Detailed Implementation

[0076] The embodiments of the present invention will now be described in detail.

[0077] <1. Polyamide Composition>

[0078] <1.1. Polyamide>

[0079] The polyamide composition of this embodiment contains polyamide. Polyamide is a polymer having amide bonds (-NHCO-) ​​in its main chain.

[0080] Crystalline polyamides are preferred as polyamides. By including crystalline polyamides in the polyamide composition, the mechanical properties of the polyamide composition can be improved. Furthermore, the mechanical properties of the molded article when exposed to high temperatures for extended periods can also be improved. Examples of crystalline polyamides include polyamide 6 (PA6), polyamide 66 (PA66), polyamide 46 (PA46), polyamide 56 (PA56), polyamide 11 (PA11), polyamide 12 (PA12), polyamide 510 (PA510), polyamide 610 (PA610), polyamide 612 (PA612), poly(m-phenylene adipamide) (PAMXD6), hexamethylenediamine-terephthalic acid polymer (PA6T), and hexamethylenediamine- The following polymers are used: terephthalic acid and adipic acid polymer (PA6T / 66), hexamethylenediamine-terephthalic acid and ε-caprolactam copolymer (PA6T / 6), trimethylhexamethylenediamine-terephthalic acid polymer (PATMD-T), isophthalic acid-adipic acid and isophthalic acid copolymer (PAMXD6 / MXDI), trimethylhexamethylenediamine-terephthalic acid and ε-caprolactam copolymer (PATMDT / 6), and diaminodicyclohexylmethane-isophthalic acid and laurolactam copolymer. It should be noted that these polymers can be used alone or in combination. Furthermore, any polyamide derived from plant-based raw materials can be used, as long as it is a crystalline polyamide. Polyamide 6 is preferred due to its excellent moldability, melt flowability, and mechanical properties.

[0081] Polyamide 6 is preferably a polyamide with ε-caprolactam as the main raw material. Polyamide with ε-caprolactam as the main raw material can be obtained by polycondensation. Other monomers can also be copolymerized in polyamide 6. Examples of such monomers include amino acids such as 11-aminoundecanoic acid, 12-aminododecanoic acid, and p-aminomethylbenzoic acid; lactams such as ω-laurolactam; aliphatic diamines such as tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, 2-methylpentamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4- / 2,4,4-trimethylhexamethylenediamine, and 5-methylnonamethylenediamine; aromatic diamines such as m-phenylenediamine and p-phenylenediamine; 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, and bis(4-aminomethyl)cyclohexane. Alicyclic diamines such as (-aminocyclohexyl)methane, bis(3-methyl-4-aminocyclohexyl)methane, 2,2-bis(4-aminocyclohexyl)propane, bis(aminopropyl)piperazine, and aminoethylpiperazine; alicyclic dicarboxylic acids such as adipic acid, octanoic acid, azelaic acid, sebacic acid, and dodecanoic acid; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, sodium isophthalate-5-sulfonate, hexahydroterephthalic acid, and hexahydroisophthalic acid; and alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, and 1,3-cyclopentanedicarboxylic acid. Two or more of these can also be copolymerized.

[0082] Of the total 100 mol% of monomer units constituting polyamide 6, units derived from ε-caprolactam are preferably 60 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and even more preferably 90 mol% or more. It can be 100 mol%.

[0083] The relative viscosity of the crystalline polyamide is preferably 1.5 or higher, more preferably 1.8 or higher, and even more preferably 2.0 or higher. A viscosity of 1.5 or higher helps to suppress excessive increase in fluidity when the polyamide composition is melted and flowed. For example, when the polyamide composition is melted and flowed for injection molding, it prevents the polyamide composition from exhibiting excessively high fluidity for injection molding. Furthermore, it can further improve strength. The relative viscosity of the crystalline polyamide is preferably 4.5 or lower, more preferably 4.0 or lower, and even more preferably 3.6 or lower. A viscosity of 4.5 or lower helps to suppress excessive decrease in fluidity when the polyamide composition is melted and flowed. For example, when the polyamide composition is melted and flowed for injection molding, it prevents the polyamide composition from exhibiting excessively low fluidity for injection molding. Furthermore, it can improve the dispersibility of the thermally conductive inorganic filler. The relative viscosity is measured according to JIS K6920-2:2009 using 98% sulfuric acid at a sample (i.e., polyamide) concentration of 1 g / dL and a temperature of 25°C.

[0084] In the polyamide composition of this embodiment, the content of crystalline polyamide in 100% by mass of polyamide is preferably 80% by mass or more. The content of crystalline polyamide may be 90% by mass or more, 95% by mass or more, 98% by mass or more, or 100% by mass.

[0085] The polyamide composition of this embodiment may contain amorphous polyamide. When the polyamide composition contains amorphous polyamide, it becomes easier to transfer the polyamide composition to the molded article (i.e., mold transfer) during injection molding. The amorphous polyamide can be a polyamide in which no melting peak of crystallization is confirmed in the thermogram measured by differential scanning calorimetry (DSC). Examples of amorphous polyamides include polymers obtained by polycondensation of diamines such as 4,4'-diamino-3,3'-dimethyldicyclohexylmethane (CA), 4,4'-diaminodicyclohexylmethane (PACM), m-phenylenediamine (MXD), trimethylhexamethylenediamine (TMD), isophorone diamine (IA), 4,4'-diaminodicyclohexylpropane (PACP), and hexamethylenediamine with dicarboxylic acids such as terephthalic acid, isophthalic acid, adipic acid, sebacic acid, and dodecanedicarboxylic acid, and lactams such as caprolactam and laurolactam as needed. It should be noted that these monomers can be used individually or in combination. Of course, other monomers can also be copolymerized in amorphous polyamides.

[0086] In particular, considering the ease with which crystallization can be suppressed, amorphous polyamides preferably contain aromatic components. Among the amorphous polyamides containing aromatic components, polyamide 6T / 6I, made from terephthalic acid, isophthalic acid, and adipic acid, and polyamide 6T / 66, made from terephthalic acid, adipic acid, and hexamethylenediamine, are preferred. Of these, polyamide 6T / 6I is more preferred from the perspective of moldability.

[0087] In the polyamide composition of this embodiment, the polyamide content is preferably 25% by mass or more, more preferably 30% by mass or more, and even more preferably 38% by mass or more. The polyamide content is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 42% by mass or less.

[0088] <1.2. Fibrous Inorganic Reinforcing Materials>

[0089] The polyamide composition of this embodiment includes a fibrous inorganic reinforcing material. The fibrous inorganic reinforcing material improves strength, specifically flexural strength. In addition, it also improves rigidity, heat resistance, and other properties.

[0090] Examples of fibrous inorganic reinforcing materials include glass fiber, carbon fiber, aramid fiber, alumina fiber, silicon carbide fiber, and zirconium oxide fiber. Other examples include whiskers such as aluminum borate and potassium titanate; needle-like wollastonite; and ground fibers. Glass fiber and carbon fiber are preferred. It should be noted that they can be used alone or in combination.

[0091] Examples of glass fibers include chopped strands. The fiber length is preferably 1 mm to 20 mm. The cross-sectional shape of the glass fiber can be circular or non-circular. Here, "cross-sectional shape" refers to the shape of the cross-section perpendicular to the length direction of the glass fiber. Examples of non-circular cross-sections include approximately elliptical, approximately oblong, and approximately cocoon-shaped cross-sections. The flatness of the non-circular cross-section glass fiber is preferably 1.5 to 8. Here, flatness refers to the ratio of the major diameter to the minor diameter (i.e., major diameter / minor diameter) when considering a rectangle with the smallest area tangent to the cross-section perpendicular to the length direction of the glass fiber, with the long side length defined as the major diameter and the short side length defined as the minor diameter. The minor diameter of the glass fiber is preferably 1 μm to 20 μm. The major diameter of the glass fiber is preferably 2 μm to 100 μm.

[0092] Regarding fibrous inorganic reinforcing materials, the ratio of average fiber length to average fiber diameter is preferably 100 or more, more preferably 200 or more. This ratio is preferably 1000 or less, more preferably 800 or less. This ratio can be 500 or less.

[0093] The fibrous inorganic reinforcing material is preferably treated with a coupling agent. This improves its affinity with polyamide and enhances its mechanical properties. Additionally, it improves appearance characteristics. Examples of coupling agents include organosilane compounds, organotitanium compounds, organoborane compounds, and epoxy compounds. It should be noted that coupling agents that readily react with carboxylic acid groups and / or carboxylic anhydride groups are preferred. By surface-treating the fibrous inorganic reinforcing material with a compound that readily reacts with carboxylic acid groups and / or carboxylic anhydride groups, the mechanical properties can be exhibited equally (i.e., uniformly) in the polyamide composition and / or molded article, and the deterioration of the smoothness of the molded article when exposed to high temperatures for extended periods can be further reduced. This will be explained further. By surface-treating the fibrous inorganic reinforcing material with a compound that readily reacts with carboxylic acid groups and / or carboxylic anhydride groups, the affinity of the fibrous inorganic reinforcing material for polyamide is improved, thus enhancing the dispersibility and adhesion of the fibrous inorganic reinforcing material. Improved dispersibility contributes to the uniform (i.e., homogeneous) mechanical properties exhibited in the polyamide composition and / or molded article. On the other hand, improved adhesion enhances the interfacial strength between the fibrous inorganic reinforcement and the polyamide, thus reducing the potential detachment of the fibrous inorganic reinforcement when the molded article is exposed to high temperatures for extended periods. This further minimizes the deterioration of the smoothness of the molded article during prolonged exposure to high temperatures. Examples of coupling agents include silane-based coupling agents, titanate-based coupling agents, and aluminum-based coupling agents. Among these, silane-based coupling agents such as aminosilane coupling agents and epoxysilane coupling agents are preferred. It should be noted that pretreatment with a coupling agent is preferred, but the coupling agent can also be added later.

[0094] In the polyamide composition of this embodiment, the content of the fibrous inorganic reinforcing material is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. If it is 5% by mass or more, the flexural strength, i.e., the overall strength, can be further improved. On the other hand, the content of the fibrous inorganic reinforcing material is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. If it is 50% by mass or less, the situation where it is difficult to manufacture molded articles using the polyamide composition can be avoided.

[0095] <1.3. Thermally Conductive Inorganic Fillers>

[0096] The polyamide composition of this embodiment contains a thermally conductive inorganic filler. The thermal conductivity of the molded article can be improved by using a thermally conductive inorganic filler, thus improving the heat dissipation of the molded article. "Thermo-conductive inorganic filler" can refer to a filler containing an inorganic compound and having a thermal conductivity of 1 W / m·K or higher.

[0097] Inorganic compounds included in thermally conductive inorganic fillers include, for example, boron nitride, aluminum oxide, silicon dioxide, aluminum hydroxide, magnesium oxide, and aluminum nitride. They can be used alone or in combination. It should be noted that thermally conductive inorganic fillers preferably possess insulating properties.

[0098] Examples of thermally conductive inorganic fillers containing magnesium oxide include sintered bodies (i.e., sintered bodies containing magnesium oxide) and lightly calcined magnesium oxide. Sintered bodies are preferred. Here, "sintered body," specifically "sintered body containing magnesium oxide," refers to a granular sintered body formed by the combination of several particles containing magnesium oxide. The sintered body may further contain silicon oxide (SiO2) and calcium oxide (CaO). In addition to containing magnesium oxide, silicon oxide (SiO2), and calcium oxide (CaO), the sintered body may also contain compounds formed by their reactions. For example, the sintered body may contain B2O3, Al2O3, Fe2O3, Na2SO4, etc.

[0099] The magnesium oxide content in the sintered body is preferably 85.0% by mass or more, more preferably 88.0% by mass or more, even more preferably 90.0% by mass or more, even more preferably 92.0% by mass or more, and even more preferably 94.0% by mass or more. If it is 85.0% by mass or more, the thermal conductivity of the sintered body is excellent. On the other hand, the magnesium oxide content in the sintered body can, for example, be 99.7% by mass or less.

[0100] The median particle size of the thermally conductive inorganic filler is preferably 1 μm or more, more preferably 2 μm or more, further preferably 5 μm or more, and even more preferably 10 μm or more. A particle size of 1 μm or more helps to suppress excessive reduction in flowability when the polyamide composition melts and flows. The median particle size can be 30 μm or more, or 60 μm or more. On the other hand, the median particle size is preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 100 μm or less. A particle size of 200 μm or less further improves thermal conductivity. The median particle size can be 80 μm or less. It should be noted that here, the median particle size is D50, specifically, the particle size representing 50% of the cumulative particle size distribution in the thermally conductive inorganic filler based on volume.

[0101] Examples of the shapes (i.e., particle shapes) of thermally conductive inorganic fillers include flat, needle-like, spherical, fibrous, and irregular shapes. Among these, spherical and irregular shapes are preferred. If spherical, it can impart uniform heat dissipation to the molded article without deviation in any direction, including the flow direction, vertical direction, and thickness direction.

[0102] The thermally conductive inorganic filler preferably undergoes surface treatment, and more preferably, surface treatment with a coupling agent. Examples of coupling agents include organosilane compounds, organotitanium compounds, organoborane compounds, and epoxy compounds. It should be noted that coupling agents that readily react with carboxylic acid groups and / or carboxylic anhydride groups are preferred. By surface treating the thermally conductive inorganic filler with a compound that readily reacts with carboxylic acid groups and / or carboxylic anhydride groups, the mechanical properties and thermal conductivity can be exhibited equally (i.e., uniformly) in the polyamide composition and / or molded article, and the deterioration of the smoothness of the molded article when exposed to high temperatures for extended periods can be further reduced. This will be explained further. By surface treating the thermally conductive inorganic filler with a compound that readily reacts with carboxylic acid groups and / or carboxylic anhydride groups, the affinity of the thermally conductive inorganic filler for polyamide can be improved, thus improving the dispersibility and adhesion of the thermally conductive inorganic filler. Improved dispersibility helps to ensure that the polyamide composition and / or molded article exhibit equal (i.e., uniform) mechanical properties and thermal conductivity. On the other hand, improved adhesion contributes to the interfacial strength between the thermally conductive inorganic filler and the polyamide, thus reducing the potential detachment of the thermally conductive inorganic filler when the molded article is exposed to high temperatures for extended periods. Therefore, it is possible to further reduce the deterioration of the smoothness of the molded article when exposed to high temperatures for extended periods. It should also be noted that it can reduce the potential deterioration of the thermal conductivity of the molded article when exposed to high temperatures for extended periods. Examples of coupling agents include silane-based coupling agents, titanate-based coupling agents, and aluminum-based coupling agents. Among these, silane-based coupling agents such as aminosilane coupling agents and epoxysilane coupling agents are preferred. It should be noted that pretreatment with a coupling agent is preferred, but the coupling agent can also be added later.

[0103] In the polyamide composition of this embodiment, the content of thermally conductive inorganic filler is preferably 20% by mass or more, more preferably 25% by mass or more, even more preferably 30% by mass or more, and even more preferably 35% by mass or more. If it is 20% by mass or more, the heat dissipation performance can be further improved. The content of thermally conductive inorganic filler can be 40% by mass or more, or 45% by mass or more. On the other hand, the content of thermally conductive inorganic filler is preferably 60% by mass or less, more preferably 55% by mass or less, and even more preferably 50% by mass or less. If it is 60% by mass or less, excessive reduction in fluidity when the polyamide composition melts and flows can be suppressed.

[0104] <1.4. Antioxidants and Stabilizers>

[0105] The polyamide composition of this embodiment preferably contains an antioxidant and / or a stabilizer, more preferably both an antioxidant and a stabilizer. The antioxidant and / or stabilizer can suppress the oxidative degradation of the polyamide.

[0106] Examples of antioxidants or stabilizers include phenolic antioxidants, copper compounds, alkali metal halides, hindered amine stabilizers (HALS), organophosphorus stabilizers, amine antioxidants, sulfur-based antioxidants, particulate iron, particulate dispersed metal powders, and metal cyanide salts. Among these, phenolic antioxidants are preferred as antioxidants. Copper compounds and alkali metal halides are preferred as stabilizers. It should be noted that they can be used alone or in combination.

[0107] As phenolic antioxidants, hindered phenolic antioxidants, i.e., phenolic antioxidants with a hindered structure, are preferred. By giving the phenolic antioxidant a hindered structure, the reaction rate with free radicals, which are the cause of oxidative degradation on the surface of the molded article, can be prevented from becoming too fast. Therefore, the phenolic antioxidant can exert its oxidative degradation effect for a longer period of time. The hindered structure can be a structure in which at least one of the two carbon atoms adjacent to the carbon atom containing the hydroxyl group in the carbon atom of the benzene ring contained in the aromatic hydrocarbon has a bulky substituent. An example of a bulky substituent is the tert-butyl group. Examples of hindered phenolic antioxidants include N,N'-hexamethylene-bis-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide, bis(3,3-bis-(4'-hydroxy-3'-tert-butylphenyl)butyrate) glycol ester, 2,1'-thioethyl bis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 4,4'-butylidene-bis(3-methyl-6-tert-butylphenol), and triethylene glycol-3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate ("SONGNOX2450", molecular weight 633). It should be noted that they can be used alone or in combination.

[0108] In the polyamide composition of this embodiment, the content of the phenolic antioxidant is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.15% by mass or more. If it is 0.05% by mass or more, the oxidative degradation of the polyamide composition can be further suppressed. On the other hand, the content of the phenolic antioxidant is preferably 1.0% by mass or less, more preferably 0.5% by mass or less. The content of the phenolic antioxidant can be 0.4% by mass or less, 0.3% by mass or less, or 0.25% by mass or less.

[0109] Copper compounds have the effect of preventing the oxidative degradation of polyamides. This can be attributed to the fact that the copper ions in the copper compounds coordinate with the amide groups, thereby forming chelates, which in turn stabilize the polyamide.

[0110] Examples of copper compounds include copper fatty acids and copper halides. Examples of copper halides include copper chloride, copper bromide, copper iodide, and copper fluoride. Examples of copper fatty acids include copper acetate, copper laurate, and copper stearate. Among these, copper bromide, copper iodide, and copper acetate are preferred, and copper bromide is more preferred. As copper bromide, copper (II) bromide is preferred. It should be noted that these compounds can be used alone or in combination.

[0111] The content of copper compound relative to 100 parts by weight of polyamide resin, based on copper (i.e., converted to elemental copper), is preferably 0.001 parts by weight or more, more preferably 0.005 parts by weight or more. If it is 0.001 parts by weight or more, the oxidative degradation of the polyamide composition can be further suppressed. The content of copper compound relative to 100 parts by weight of polyamide resin, based on copper (i.e., converted to elemental copper), is preferably 1.0 parts by weight or less, more preferably 0.5 parts by weight or less, more preferably 0.1 parts by weight or less, and even more preferably 0.03 parts by weight or less. If it is 1.0 parts by weight or less, corrosion of the mold, extruder, and molding machine (e.g., corrosion of the screw, barrel, etc.) that may be caused by copper compound can be suppressed.

[0112] In the polyamide composition of this embodiment, the content of the copper compound is preferably 0.001% by mass or more, more preferably 0.003% by mass or more, more preferably 0.005% by mass or more, even more preferably 0.007% by mass or more, and even more preferably 0.010% by mass or more. The content of the copper compound may be 0.015% by mass or more, or 0.020% by mass or more. On the other hand, the content of the copper compound is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, even more preferably 0.3% by mass or less, even more preferably 0.1% by mass or less, even more preferably 0.07% by mass or less, and even more preferably 0.05% by mass or less.

[0113] As antioxidants, phenolic antioxidants and copper compounds are preferred, and hindered phenolic antioxidants and copper compounds are more preferably used together. By using these substances together, the degree of degradation of the polyamide on and / or near the surface of the molded article when it is exposed to high temperatures for extended periods can be effectively reduced. Therefore, excessive reduction in adhesion between the molded article and objects on it (e.g., interstitial fillers) that may occur when the molded article is exposed to high temperatures for extended periods can be further prevented. This will be explained below. When a molded article is exposed to high temperatures for extended periods, free radicals may sometimes be generated at a rate exceeding the free radical scavenging rate of phenolic antioxidants. That is, the amount of free radicals generated per unit time may sometimes exceed the amount of free radicals scavenged per unit time by phenolic antioxidants. For example, when a molded article is exposed to 150°C for extended periods, the amount of free radicals generated per unit time may sometimes exceed the amount of free radicals scavenged per unit time by hindered phenolic antioxidants. By using copper compounds in conjunction with phenolic antioxidants, the polyamide can be stabilized, thereby reducing the oxidative degradation of the polyamide caused by free radicals not scavenged by phenolic antioxidants. Therefore, it can effectively reduce the degradation of polyamide on and / or near the surface of molded articles when they are exposed to high temperatures for extended periods, thereby further reducing the deterioration of the smoothness of the molded articles. As a result, it can further prevent excessive reduction in the adhesion between the molded articles and objects on them (such as interstitial fillers) that may occur when the molded articles are exposed to high temperatures for extended periods. It should be noted that other antioxidants (such as hindered amine stabilizers (HALS), organophosphorus stabilizers, amine antioxidants, sulfur-based antioxidants, particulate iron, particulate dispersed metal powder, and metal cyanide salts) can also be used in conjunction with phenolic antioxidants and copper compounds.

[0114] In the polyamide composition of this embodiment, the total content of phenolic antioxidants and copper compounds in 100% by mass of the antioxidants is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 93% by mass or more. The total content of phenolic antioxidants and copper compounds may be 95% by mass or more, 98% by mass or more, or 100% by mass.

[0115] Alkali metal halides (i.e., alkali metal halides) also have the function of preventing the oxidative degradation of polyamides. Examples of alkali metal halides include potassium iodide and potassium bromide. In the case where the polyamide composition of this embodiment contains a copper compound and an alkali metal halide, the precipitation of copper can also be prevented by the alkali metal halide.

[0116] In the polyamide composition of this embodiment, the content of alkali metal halide is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.08% by mass or more. On the other hand, the content of alkali metal halide is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, even more preferably 0.4% by mass or less, even more preferably 0.3% by mass or less, and even more preferably 0.2% by mass or less.

[0117] In the polyamide composition of this embodiment, the content of the antioxidant is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.15% by mass or more. On the other hand, the content of the antioxidant is preferably 1.0% by mass or less, more preferably 0.5% by mass or less. The content of the antioxidant may be 0.4% by mass or less, 0.3% by mass or less, or 0.25% by mass or less.

[0118] In the polyamide composition of this embodiment, the content of the stabilizer is preferably 0.005% by mass or more, more preferably 0.01% by mass or more, and even more preferably 0.015% by mass or more. On the other hand, the content of the stabilizer is preferably 0.1% by mass or less, more preferably 0.07% by mass or less, even more preferably 0.05% by mass or less, and even more preferably 0.04% by mass or less.

[0119] In the polyamide composition of this embodiment, the total content of antioxidants and stabilizers is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.15% by mass or more. On the other hand, the total content of antioxidants and stabilizers is preferably 1.0% by mass or less, more preferably 0.5% by mass or less. The total content may be 0.4% by mass or less, 0.3% by mass or less, or 0.25% by mass or less.

[0120] <1.5. Release Agent>

[0121] The polyamide composition of this embodiment preferably contains a mold release agent. By including a mold release agent in the polyamide composition, the molded article can be easily removed from the mold when the polyamide composition is molded using a mold (e.g., during injection molding). Therefore, even when the molded article is formed into a complex shape, it can be easily removed from the mold.

[0122] Examples of release agents include esters and metal salts of long-chain fatty acids. Examples of release agents include amide compounds such as ethylene bis(terephthalamide) and methylene bis(stearamide). Examples of release agents include aliphatic hydrocarbon-based waxes, polyethylene-based waxes, and polysiloxane-based silicone oils. Among these, release agents based on fatty acid metal salts and fatty acid esters are preferred. That is, release agents based on fatty acid metal salts and fatty acid esters (i.e., fatty acid esters) are preferred. It should be noted that they can be used alone or in combination.

[0123] Examples of fatty acid metal salts include metal salts of fatty acids with 12 to 40 carbon atoms, such as stearic acid, palmitic acid, behenic acid, erucic acid, oleic acid, lauric acid, and linalic acid. Among these, metal salts of aliphatic carboxylic acids with 22 to 30 carbon atoms are preferred. In particular, from the viewpoint of mold release properties, salts of alkali metals or alkaline earth metals, such as benzyl acid, limonic acid, and linalic acid, are more preferred. Examples of alkali metals or alkaline earth metals include lithium, sodium, magnesium, and calcium.

[0124] Examples of higher fatty acid ester compounds include mixtures with beeswax palmitate as the main component, stearate stearate, benzyl benzyl acid, stearate benzyl benzyl acid, glyceryl monopalmitate, glyceryl monostearate, glyceryl distearate, glyceryl tristearate, pentaerythritol monopalmitate, pentaerythritol monostearate, pentaerythritol distearate, pentaerythritol tristearate, and pentaerythritol tetrastearate.

[0125] In the polyamide composition of this embodiment, the content of the mold release agent is preferably 0.01% by mass or more, more preferably 0.1% by mass or more. If it is 0.01% by mass or more, it can prevent the polyamide composition from adhering to the mold when it is injected into the mold and prevent wrinkles that may occur on the surface of the molded article during demolding. On the other hand, the content of the mold release agent is preferably 1.0% by mass or less, more preferably 0.5% by mass or less.

[0126] <1.6. Other additives, etc.>

[0127] The polyamide composition of this embodiment may include, for example, carbon black, copper oxide, light stabilizer, nucleating agent, antistatic agent, pigment, dye, electromagnetic wave inhibitor, etc. Of course, the polyamide composition of this embodiment may also include resins other than polyamide.

[0128] In the polyamide composition of this embodiment, the total content of the fibrous inorganic reinforcing material and the thermally conductive inorganic filler is preferably 50% by mass or more, more preferably 55% by mass or more, and even more preferably 58% by mass or more. On the other hand, the total content of the fibrous inorganic reinforcing material and the thermally conductive inorganic filler is preferably 70% by mass or less, more preferably 65% ​​by mass or less, and even more preferably 62% by mass or less.

[0129] <1.7.Physical Properties>

[0130] The higher the flexural strength of the polyamide composition in this embodiment, the better. The flexural strength is preferably 120 MPa or more, more preferably 150 MPa or more, further preferably 160 MPa or more, and even more preferably 170 MPa or more. If it is 120 MPa or more, the molded article can have suitable mechanical properties when used as a peripheral component of electrical and electronic parts (e.g., batteries, motors). The flexural strength can be 230 MPa or less, 220 MPa or less, or 215 MPa or less. It should be noted that the flexural strength of the polyamide composition is a value measured after test pieces are made using the polyamide composition. Specifically, the flexural strength of the polyamide composition is a value measured by the method described in the examples.

[0131] The higher the thermal conductivity of the polyamide composition in this embodiment, the better. The thermal conductivity is preferably 0.60 W / m·K or higher, more preferably 0.65 W / m·K or higher, and even more preferably 0.70 W / m·K or higher. If it is 0.60 W / m·K or higher, the molded article can have appropriate thermal conductivity when used as a peripheral component of electrical and electronic parts (e.g., batteries, motors). The thermal conductivity of the polyamide composition can be 1.20 W / m·K or lower, 1.10 W / m·K or lower, or 1.00 W / m·K or lower. It should be noted that the thermal conductivity of the polyamide composition is a value measured after preparing a disc-shaped sample using the polyamide composition. Specifically, the thermal conductivity of the polyamide composition is a value measured by the method described in the examples.

[0132] The polyamide composition of this embodiment, when placed at 150°C for 1000 hours, exhibits an infrared absorption spectrum at 1750 cm⁻¹. -1 ~1700cm -1 The peak area (i.e., peak A) relative to 1665 cm⁻¹ -1 ~1630cm -1The ratio of peak area (i.e., peak B) to peak area (i.e., peak area ratio) is preferably 0.10 or less. Here, "infrared absorption spectrum" refers to the infrared absorption spectrum at a depth of 50 μm from the surface of the molded article after the polyamide composition has been molded into a molded article with an arithmetic mean roughness (Ra) of 0.1 μm and then placed at 150°C for 1000 hours. By keeping the peak area ratio below 0.10, excessive reduction in adhesion between the molded article and objects on it (e.g., gap fillers) that may occur when the molded article is exposed to high temperatures for extended periods can be avoided. This is because the degree of deterioration of the polyamide when the molded article is exposed to high temperatures for extended periods can be further reduced. This will be explained further. 1750 cm⁻¹ -1 ~1700cm -1 The peak (peak A) is enlarged due to the deterioration of the polyamide. On the other hand, the 1665 cm⁻¹ peak... -1 ~1630cm -1 The peak (i.e., peak B) originates from the carbonyl group of the amide bond. Therefore, in the infrared absorption spectrum after being placed at 150°C for 1000 hours, the smaller the ratio of peak A area to peak B area (i.e., peak A area / peak B area), the less the polyamide deteriorates. According to the polyamide composition of this embodiment, since this ratio, i.e., the peak area ratio, is 0.10 or less, the degree of deterioration of the polyamide on and / or near the surface of the molded article when the molded article is exposed to a high temperature environment for a long time can be further reduced. Therefore, the detachment and cracking of thermally conductive inorganic fillers and / or fibrous inorganic reinforcing materials that may occur when the molded article is exposed to a high temperature environment for a long time can be reduced. That is, the degree of deterioration of the smoothness of the molded article when it is exposed to a high temperature environment for a long time can be reduced. As a result, the excessive reduction of adhesion between the molded article and objects (e.g., interstitial fillers) that may occur when the molded article is exposed to a high temperature environment for a long time can be avoided.

[0133] The peak area ratio is more preferably 0.09 or less, more preferably 0.08 or less, more preferably 0.06 or less, more preferably 0.05 or less, and more preferably 0.04 or less. The peak area ratio can be 0.03 or less, or 0.02 or less. It should be noted that the peak area ratio is specifically the value measured by the method described in the embodiments.

[0134] For the polyamide composition of this embodiment, the arithmetic mean roughness (Ra) (hereinafter sometimes referred to as "treated roughness") after being placed at a temperature of 150°C for 1000 hours is preferably 3.0 μm or less, more preferably 2.5 μm or less, and even more preferably 2.0 μm or less. If it is 2.0 μm or less, excessive reduction in adhesion between the molded article and objects (e.g., gap fillers) on the molded article that may occur when the molded article is exposed to a high temperature environment for a long time can be further avoided. The arithmetic mean roughness (Ra) can be 1.5 μm or less, 1.2 μm or less, or 1.0 μm or less. It should be noted that the treated roughness of the polyamide composition is a value measured after a flat molded article with an arithmetic mean roughness (Ra) of 0.1 μm is made using the polyamide composition and then placed at a temperature of 150°C for 1000 hours. Specifically, the treated roughness is a value measured by the method described in the examples.

[0135] For the polyamide composition of this embodiment, the difference in arithmetic mean roughness (Ra) before and after being placed at 150°C for 1000 hours is preferably 1.5 μm or less in absolute value. That is, the difference between the arithmetic mean roughness (Ra) after being placed at 150°C for 1000 hours (i.e., the roughness after treatment) and the arithmetic mean roughness (Ra) before being placed at 150°C for 1000 hours (hereinafter sometimes referred to as "roughness before treatment") is preferably 1.5 μm or less. If it is 1.5 μm or less, it is possible to further avoid excessive reduction in the adhesion between the molded article and objects (e.g., gap fillers) on the molded article that may occur when the molded article is exposed to a high temperature environment for a long time. This difference is more preferably 1.3 μm or less, more preferably 1.0 μm or less, more preferably 0.8 μm or less, and more preferably 0.6 μm or less.

[0136] <1.8. Manufacturing method and application>

[0137] The polyamide composition of this embodiment can be manufactured by mixing at least the polyamide, the fibrous inorganic reinforcing material, the thermally conductive inorganic filler, and the desired antioxidant and / or stabilizer using a mixing apparatus. For mixing, an extruder (e.g., a single-screw extruder, a twin-screw extruder), a pressure kneader, etc., can be used. An extruder is preferred, and a twin-screw extruder is more preferred. Examples of mixing temperatures include 220°C to 300°C. The mixing time can be, for example, approximately 2 to 15 minutes.

[0138] For example, the polyamide composition of this embodiment can be manufactured by: melt-blending at least the polyamide, fibrous inorganic reinforcing material, thermally conductive inorganic filler, and antioxidant and / or stabilizer as needed using a twin-screw extruder, then extruding the filament, cooling the filament as needed, and cutting the filament as needed.

[0139] It should be noted that, at least when using copper compounds as stabilizers, the masterbatch containing copper compounds can be blended with polyamide, fibrous inorganic reinforcing materials, thermally conductive inorganic fillers, etc., before compounding. Alternatively, copper compounds can be added at any stage of polyamide manufacturing. For example, they can be added to the brine solution of the polyamide raw material, or injected into the molten polyamide midway through melt polymerization.

[0140] The shape of the polyamide composition in this embodiment can be appropriately set. For example, the polyamide composition in this embodiment can be in granule form, in strand form, in powder form, or can be molded into any shape. Granule form is preferred.

[0141] The polyamide composition of this embodiment can be used as a raw material for various molded articles. It is suitable for use as a raw material for electrical and electronic components requiring high thermal conductivity, automotive components (e.g., electric vehicle components), industrial components, etc. Examples of such components include lamp holders, electrical components, heat sinks, semiconductor packaging components, cooling fan components, connectors, switches, housing covers, battery housings, components used around battery housings, and components used inside battery housings (e.g., the base plate of a battery module). Here, the battery housing can be the housing of a battery pack. In particular, it is suitable for manufacturing peripheral components (e.g., battery housings, components used around battery housings, and components used inside battery housings) of electrical and electronic components (e.g., batteries) that generate high Joule heat. It is particularly suitable for manufacturing battery housings. Here, when the battery housing comprises multiple components, the use of the polyamide composition for manufacturing the battery housing refers to the use of the polyamide composition for manufacturing at least one component.

[0142] The polyamide composition of this embodiment can be suitably used as a raw material for molded articles in which gap fillers are provided. That is, the polyamide composition of this embodiment can be suitably used to manufacture molded articles in which gap fillers are provided. In order to provide gap fillers to the molded article, gap fillers can be applied to the molded article. On the other hand, gap fillers can also be provided to the molded article as a result of the following steps: applying gap fillers to something (e.g., components constituting a battery or motor), and then adhering it to the molded article using the gap fillers. The gap fillers may contain thermally conductive inorganic fillers. The description of the thermally conductive inorganic fillers of the gap fillers is repeated with the above description (i.e., the description of the thermally conductive inorganic fillers of the polyamide composition of this embodiment), and therefore is omitted. Therefore, the description of the thermally conductive inorganic fillers of the polyamide composition of this embodiment can also be treated as the description of the thermally conductive inorganic fillers of the gap fillers. The gap fillers may further contain polymers. Examples of polymers include silicone and polyurethane. It should be noted that they can be used alone or in combination. The polymers may be oligomers. The thermally conductive inorganic fillers may further contain curing agents. Thermally conductive inorganic fillers may contain other additives. Preferably, the thermally conductive inorganic filler is curable. It should be noted that the object disposed on the molded article can be anything other than a gap filler.

[0143] <2. Molded Products>

[0144] The molded article of this embodiment can be obtained by molding the polyamide composition of this embodiment described above. That is, the molded article of this embodiment can be obtained from the polyamide composition of this embodiment described above. As molding methods, examples include injection molding, extrusion molding, blow molding, etc. Among these, injection molding is preferred from the viewpoint of being able to achieve complex shapes.

[0145] Example

[0146] The following examples and comparative examples illustrate the present invention in more detail. Unless otherwise specified, "parts" refers to "parts by mass" and "%" refers to "% by mass".

[0147] <1. Raw Materials>

[0148] Use the raw materials shown below.

[0149] <1.1. Polyamide>

[0150] A1...MEIDA's "M2000" (polyamide 6, relative viscosity 2.0, melting point 225℃)

[0151] A2... "ZISAMIDE TP4208" (polyamide 6, relative viscosity 2.5, melting point 225℃) manufactured by Jisheng Company

[0152] A3... "ZISAMIDE TP6603" (polyamide 6, relative viscosity 3.6, melting point 225℃) manufactured by Jisheng Company

[0153] <1.2. Fibrous Inorganic Reinforcing Materials>

[0154] B1... "ECS301HP-3-H" (glass fiber) manufactured by Chongqing International Composite Materials Co., Ltd. (CPIC).

[0155] B2... "CFUW-MC" (carbon fiber) manufactured by Japan Polymer Industry Co., Ltd.

[0156] <1.3. Thermally conductive inorganic fillers>

[0157] C1...RF-50-AC manufactured by Ube Materials Co., Ltd. (a sintered magnesium oxide with a surface-treated particle size of 50 μm, comprising magnesium oxide, calcium oxide, and silicon oxide.)

[0158] C2... "HF-10" manufactured by Tokuyama Corporation (aluminum nitride with a particle size of 10μm. Untreated).

[0159] C3… sintered magnesium oxide with a surface-treated particle size of 10 μm (details to follow).

[0160] C4… sintered magnesium oxide with a surface-treated particle size of 100 μm (details to follow).

[0161] Thermally conductive inorganic filler C3

[0162] A thermally conductive inorganic filler is obtained by subjecting a 10 μm sintered body of magnesium oxide (containing magnesium oxide, calcium oxide and silicon oxide) manufactured according to Japanese Patent No. 5993824 to the same surface treatment as thermally conductive inorganic filler C1 (i.e. "RF-50-AC").

[0163] Thermally conductive inorganic filler C4

[0164] A thermally conductive inorganic filler is obtained by subjecting a 100 μm sintered body of magnesium oxide (containing magnesium oxide, calcium oxide and silicon oxide) manufactured according to Japanese Patent No. 5993824 to the same surface treatment as thermally conductive inorganic filler C1 (i.e. "RF-50-AC").

[0165] <1.4. Antioxidants or stabilizers>

[0166] D1...SONGNOX2450 (hindered phenolic antioxidant) manufactured by SONGWON.

[0167] D2... Copper bromide manufactured by Nippon Chemical Industries, Ltd.

[0168] D3... Potassium iodide from the Contract Resource System of the Corporation

[0169] <1.5. Release Agent>

[0170] E1...Licolub WE-40 (aliphatic ester) manufactured by Clariant Japan Co., Ltd.

[0171] E2... "NP1500-S" (magnesium stearate) manufactured by Tamnan Chemical Industry Co., Ltd.

[0172] <1.6. Coupling Agents>

[0173] F...KBE-903 (3-aminopropyltriethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd.

[0174] <2. Granulation>

[0175] The raw materials are measured according to the mixing ratios recorded in Tables 1 and 2, mixed using a rotary drum, and then fed into a twin-screw extruder to obtain granules. The set temperature of the twin-screw extruder is 250℃~300℃, and the mixing time is 5 minutes~10 minutes.

[0176] <3. Evaluation Methods>

[0177] <3.1. Relative viscosity of polyamide (98% sulfuric acid solution method)>

[0178] The relative viscosity was determined using an Ubbelohde viscometer according to JIS K6920-2:2009, with 98% sulfuric acid, at a polyamide concentration of 1 g / dL and a temperature of 25°C.

[0179] <3.2. Melting point of polyamide>

[0180] The endothermic peak temperature was determined using a differential scanning calorimeter (Seiko Instruments Co., Ltd.'s "EXSTAR 6000") with a heating rate of 20°C / min.

[0181] <3.3. Arithmetic Mean Roughness (Ra)>

[0182] Using an injection molding machine with a barrel temperature of 260°C and a mold temperature of 90°C, granules were molded into flat products with a thickness of 2 mm, a length of 100 mm, and a width of 100 mm. The arithmetic mean height, specifically, and arithmetic mean roughness (Ra) of the surface profile features of the flat products were measured according to JIS B 0601:2013. After treating the flat products at 150°C for 1000 hours, the arithmetic mean roughness (Ra) was also measured using the same method, i.e., according to JIS B 0601:2013.

[0183] <3.4. Peak Area Ratio of the Spectrum>

[0184] Using an injection molding machine with a barrel temperature of 260℃ and a mold temperature of 90℃, granules were molded into flat products with a thickness of 2mm, a length of 100mm, and a width of 100mm, achieving an arithmetic mean roughness (Ra) of 0.1μm. After treating the flat products at 150℃ for 1000 hours, test specimens were cut from them. The specimens were then embedded in epoxy resin, and cut perpendicular to the specimen surface. The exposed cross-section was then polished smooth using a rotary polisher with abrasive paper attached.

[0185] For the ground cross-section specimens, micro-infrared measurements were performed using the reflectance method (device: Agilent Technologies, Cary 670FTIR / Cary 620FTIR microscope). A 64×64 MCTFPA detector was used at a resolution of 8 cm⁻¹. -1 The measurements were performed under the condition of a cumulative total of 256 times. The grinding section specimens were arranged such that the end of the section was parallel to the y-axis of the measurement surface and the end of the section was included in the measurement range (specifically, 350 μm square. The measurement points are 4096 points with x=0~63 and y=0~63) within the range of x=1~10.

[0186] The spectral data obtained by micro-infrared spectroscopy were converted to Kramers-Kronig using the accompanying analysis software. The spectra at each measurement point were confirmed from the left end of the measurement range, and the main peak originating from the embedding resin was detected (in this study, epoxy resin was used, specifically bisphenol A epoxy resin as the embedding resin, therefore the peak was at approximately 1510 cm⁻¹). -1 The position of the x-value obtained by adding 9 to the x-value (the end that constitutes the sample surface) when the number of points of the main peak first falls below half is taken as the measurement point at a depth of 50 μm from the sample surface. This is because the length between measurement points is approximately 5.5 μm.

[0187] From 64 measurement points at a depth of 50 μm from the sample surface, according to 1665 cm... -1~1630cm -1 Eight measurement points were selected in descending order of peak area, and the average spectrum of these eight points was taken as the spectrum at a depth of 50 μm from the sample surface. It should be noted that the inorganic filler content is high on the sample surface, making it impossible to obtain a spectrum with sufficient intensity. Therefore, the spectrum at a depth of 50 μm from the sample surface was obtained following the steps described above.

[0188] In the spectrum at a depth of 50 μm from the sample surface, the 1750 cm⁻¹ value was determined. -1 ~1700cm -1 The peak area and 1665cm -1 ~1630cm -1 The peak area is 1750 cm⁻¹. -1 ~1700cm -1 The peak at 1665 cm⁻¹ is the carbonyl peak, which becomes larger due to the deterioration of the polyamide. On the other hand, the peak at 1665 cm⁻¹... -1 ~1630cm -1 The peak originates from the carbonyl group of the amide bond. It should be noted that the peak at 1800 cm⁻¹ is... -1 ~1780cm -1 The average absorbance at 1600 cm⁻¹ -1 ~1580cm -1 After determining the baseline by using the average absorbance of the lines, their peak areas are calculated.

[0189] Then, calculate 1750cm. -1 ~1700cm -1 The peak area relative to 1665 cm⁻¹ -1 ~1630cm -1 The ratio of peak area to peak area, i.e., 1750cm -1 ~1700cm -1 Peak area / 1665cm -1 ~1630cm -1 The peak area (i.e., the peak area ratio).

[0190] <3.5. Bending Strength>

[0191] Using an injection molding machine with a barrel temperature of 260°C and a mold temperature of 80°C, granules are molded into test pieces of the shape specified in JIS K7139:2009 A1. For these test pieces, a bending test is performed according to ISO 178:2010 to determine the bending strength (i.e., the maximum bending stress the test piece can withstand during the bending test). The bending test is conducted using Method A, with a support distance of 64 mm, a test speed of 2 mm / min, and no change in strain rate during the test.

[0192] <3.6. Thermal conductivity>

[0193] Using an injection molding machine with a barrel temperature of 260℃ and a mold temperature of 90℃, granules were molded into a flat product with a thickness of 2mm, a length of 100mm, and a width of 100mm. The center of the flat product was then cut into a circular plate with a width of approximately 10mm. The thermal diffusivity, density, and specific heat of the circular plate sample were measured. The thermal diffusivity was determined using the laser flash method according to ASTM E1461. The density was determined using the water displacement method according to ISO 1183:1987. The specific heat was determined according to the method of JIS K7123:1987. Based on these results, the thermal conductivity was calculated using the following formula.

[0194] [Mathematical Expression 1]

[0195]

[0196] It should be noted that the thermal conductivity of flat molded products treated at 150°C for 1000 hours should also be calculated using the above steps.

[0197] <3.7. Adhesion to interstitial fillers>

[0198] Using granules, two plate-shaped articles with a thickness of 3 mm, a length of 55 mm, and a width of 15 mm and an arithmetic mean roughness (Ra) of 0.1 μm were formed. A gap filler with a thickness of 1 mm and a square diameter of 15 mm was applied to the front end of one of the two sides of the first article along its length. The gap filler was then clamped and bonded to the front end of one of the two sides of the second article along its length. This resulted in an object formed by the first article, the second article, and the gap filler that bonded them together. A test piece with a length of 95 mm and a width of 15 mm was cut from this object. After the test piece was placed at 130°C for 1000 hours (i.e., after a degradation-accelerating treatment), a tensile test was performed. In the tensile test, the first article of the test piece was clamped with a first clamp, the second article of the test piece was clamped with a second clamp, and then the test piece was stretched along its length. In this tensile test, if the shear bond strength (i.e., the stress obtained by dividing the load by the joint area) at the point of peeling between the first or second molded article and the gap filler is less than 0.1 MPa, it is judged as ×. On the other hand, if the shear bond strength at the point of peeling is 0.1 MPa or more, it is judged as 0.

[0199] <4. Results>

[0200] The following table shows the results.

[0201] [Table 1]

[0202]

[0203] [Table 2]

[0204]

[0205] In these tables, the physical properties marked "after thermal degradation" refer to the physical properties after being treated at 150°C for 1000 hours.

[0206] The smaller the peak area ratio and the smaller the difference in arithmetic mean roughness (Ra) before and after treatment at 150°C for 1000 hours, the better the adhesion to the interstitial filler (refer to Examples 1-15 and Comparative Examples 1-6).

[0207] The surface of the plate molded article of Example 1 (peak area ratio of 0.03) and the plate molded article of Comparative Example 2 (peak area ratio of 0.14) were observed after being treated at 150°C for 1000 hours. The surface of the plate molded article of Example 1 was smoother than that of the plate molded article of Comparative Example 2 (see reference). Figure 1 and Figure 2 On the surface of the flat molded article of Comparative Example 2, a great deal of thermally conductive inorganic filler and fibrous inorganic reinforcing material were exposed, and many cracks were also present in the parts where resin (i.e. polyamide) was present.

[0208] By using hindered phenolic antioxidants and copper bromide in combination, the peak area ratio can be synergistically reduced. In this regard, using 0.2 parts by mass of hindered phenolic antioxidant resulted in a peak area ratio reduction of 0.03 (refer to Comparative Examples 1 and 2). Using 0.02 parts by mass of copper bromide resulted in a peak area ratio reduction of 0.09 (refer to Comparative Examples 1 and 6). On the other hand, by using 0.2 parts by mass of hindered phenolic antioxidant and 0.02 parts by mass of copper bromide in combination, the peak area ratio was reduced by 0.14 (refer to Comparative Examples 1 and 2).

[0209] By using hindered phenolic antioxidants and copper bromide in combination, the deterioration of the arithmetic mean roughness caused by treatment at 150°C for 1000 hours can be synergistically reduced. In this regard, using 0.2 parts by mass of hindered phenolic antioxidants, the arithmetic mean roughness decreased by 0.8 μm after 1000 hours of treatment at 150°C (refer to Comparative Examples 1 and 2). Using 0.02 parts by mass of copper bromide, the arithmetic mean roughness decreased by 2.1 μm after 1000 hours of treatment at 150°C (refer to Comparative Examples 1 and 6). On the other hand, by using 0.2 parts by mass of hindered phenolic antioxidants and 0.02 parts by mass of copper bromide in combination, the arithmetic mean roughness decreased by 3.8 μm after 1000 hours of treatment at 150°C (refer to Comparative Examples 1 and 2).

[0210] Without using thermally conductive inorganic fillers, the thermal conductivity of the molded article is too low (see Comparative Example 4). Without using fibrous inorganic reinforcing materials, the flexural strength of the molded article is too low (see Comparative Example 5).

[0211] Industrial availability

[0212] This invention provides polyamide compositions and molded articles, which can therefore be used industrially.

Claims

1. A polyamide composition comprising polyamide, a fibrous inorganic reinforcing material, and a thermally conductive inorganic filler. When the polyamide composition is placed at 150°C for 1000 hours, the infrared absorption spectrum at 1750 cm⁻¹... -1 ~1700cm -1 The peak area relative to 1665 cm⁻¹ -1 ~1630cm -1 The proportion of peak area is below 0.

10. When the polyamide composition is placed at 150°C for 1000 hours, the difference in its arithmetic mean roughness (Ra) before and after is less than 1.5 μm in absolute value.

2. The polyamide composition according to claim 1, wherein the flexural strength is 120 MPa or more and the thermal conductivity is 0.60 W / m·K or more.

3. The polyamide composition according to claim 1, wherein, The difference is less than 1.0 μm in absolute value.

4. The polyamide composition according to claim 1, further comprising an antioxidant and a stabilizer.

5. The polyamide composition according to claim 1, wherein, The polyamide comprises crystalline polyamide.

6. The polyamide composition according to claim 1, wherein, The polyamide has a relative viscosity of 2.0 or higher and 3.6 or lower.

7. The polyamide composition according to claim 1, wherein, The content of the thermally conductive inorganic filler is 35% by mass or more.

8. The polyamide composition according to claim 1, wherein, The thermally conductive inorganic filler has undergone surface treatment.

9. The polyamide composition according to claim 1, used as a raw material for molded articles in which gap fillers are provided.

10. The polyamide composition according to claim 1, further comprising a phenolic antioxidant and a copper compound.

11. The polyamide composition according to claim 10, wherein, The phenolic antioxidant has a hindered structure. The copper compound is at least one selected from the group consisting of copper acetate, copper iodide, and copper bromide.

12. The polyamide composition according to claim 1, further comprising a release agent.

13. A molded article obtained by molding the polyamide composition according to any one of claims 1 to 12.

Images