Resin composition, molded article, and method for manufacturing molded article

Abstract

Provided are a resin composition, a molded article, and a method for producing a molded article. A resin composition according to the present disclosure contains a polyamide resin A, a polyamide resin B, and a colorant, wherein: the polyamide resin A contains a diamine unit and a dicarboxylic acid unit; the diamine unit contains a xylylenediamine unit at 70 mol% or more; the dicarboxylic acid unit contains a C11-20 α,ω-linear aliphatic dicarboxylic acid unit at 70 mol% or more; 0.5-20 parts by mass of the polyamide resin B is contained with respect to 100 parts by mass of the total of the polyamide resin A and the polyamide resin B; and the difference (Tmb-Tma) between the melting point Tmb of the polyamide resin B according to differential scanning calorimetry (DSC) and the melting point Tma of the polyamide resin A according to differential scanning calorimetry (DSC) is 35°C to 150°C.

Description

Resin composition, molded article, and method for manufacturing a molded article

[0001] This invention relates to resin compositions, molded articles, and methods for manufacturing molded articles. In particular, it relates to resin compositions mainly composed of polyamide resin.

[0002] Generally, polyamide resins have excellent mechanical properties, heat resistance, impact resistance, and chemical resistance, and are widely used in automotive parts, electrical components, electronic components, household goods, etc. In particular, polyamide resins to which reinforcing fibers, such as glass fibers, are added have significantly improved rigidity, strength, and heat resistance, and it is known that rigidity improves in proportion to the amount of reinforcing fibers added. In addition, from the viewpoint of providing design appeal, colorants such as carbon black are sometimes blended into polyamide resins. For example, Patent Document 1 discloses a polyamide resin composition containing (A) a crystalline polyamide resin mainly composed of polycapramid resin, (B) a semi-aromatic amorphous polyamide resin, (C) an inorganic reinforcing material, (D) a carbon black masterbatch, and (E) a copper compound.

[0003] International Publication No. 2021 / 149674

[0004] Polyamide resins are typically crystalline resins, and molded articles obtained by molding polyamide resins tend to have poor transparency and exhibit cloudiness. Therefore, when colorants are added to polyamide resins, the vividness of the color tends to be poor. In addition, the appearance of the resulting molded articles may be inferior. For this reason, conventional methods such as adding amorphous resins have been employed. On the other hand, with the increasing demand for polyamide resins, there is a need for resin compositions that can achieve improved vividness of color and appearance by other methods. The present invention aims to solve these problems and to provide a resin composition capable of providing molded articles with excellent vividness of color and excellent appearance, as well as a molded article and a method for manufacturing a molded article.

[0005] Under these circumstances, the inventors conducted an investigation and found that the above problems can be solved by using a predetermined polyamide resin in combination with a high-melting-point crystalline polyamide resin. Specifically, the above problems were solved by the following means: [1] A resin composition comprising polyamide resin A, polyamide resin B, and a colorant, wherein polyamide resin A comprises diamine units and dicarboxylic acid units, the diamine units contain 70 mol% or more of xylylenediamine units, and the dicarboxylic acid units contain 70 mol% or more of α,ω-linear aliphatic dicarboxylic acid units having 11 to 20 carbon atoms, the polyamide resin B is present in a quantity of 0.5 to 20 parts by mass per 100 parts by mass of the total of polyamide resin A and polyamide resin B, and the difference (Tmb-Tma) between the melting point Tmb of polyamide resin B according to differential scanning calorimetry (DSC) and the melting point Tma of polyamide resin A according to differential scanning calorimetry (DSC) is 35 to 150°C. [2] The resin composition according to [1], wherein 70 mol% or more of the dicarboxylic acid units of the polyamide resin A are dodecanediic acid units. [3] The resin composition according to [1] or [2], wherein 20 to 100 mol% of the diamine units of the polyamide resin A are metaxylylenediamine units and 80 to 0 mol% are paraxylylenediamine units. [4] The resin composition according to any one of [1] to [3], wherein the melting point Tmb of the polyamide resin B determined by differential scanning calorimetry (DSC) is 260 to 320°C. [5] The resin composition according to any one of [1] to [4], wherein 70 mol% or more of the diamine units of the polyamide resin B are paraxylylenediamine units and 70 mol% or more of the dicarboxylic acid units are sebacic acid units. [6] The resin composition according to any one of [1] to [5], comprising 1 to 6 parts by mass of polyamide resin B per 100 parts by mass of the total of polyamide resin A and polyamide resin B. [7] The resin composition according to any one of [1] to [6], wherein the coloring agent comprises a black coloring agent. [8] The resin composition according to any one of [1] to [7], further comprising reinforcing fibers. [9] The resin composition according to [8], wherein the reinforcing fibers comprise glass fibers.

[10] The resin composition according to any one of [1] to [9], wherein 70 mol% or more of the dicarboxylic acid units of the polyamide resin A are dodecanediacid units, 20 to 100 mol% of the diamine units of the polyamide resin A are metaxylylenediamine units and 80 to 0 mol% are paraxylylenediamine units, the melting point Tmb of the polyamide resin B according to differential scanning calorimetry (DSC) is 260 to 320°C, 70 mol% or more of the diamine units of the polyamide resin B are paraxylylenediamine units and 70 mol% or more of the dicarboxylic acid units are sebaciacic acid units, the polyamide resin B is contained in 1 to 6 parts by mass per 100 parts by mass of the total of the polyamide resin A and the polyamide resin B, the coloring agent contains a black coloring agent and further contains reinforcing fibers, and the reinforcing fibers contain glass fibers.

[11] A molded article formed from any one of [1] to

[10] . A method for manufacturing a molded article, comprising injection molding a resin composition according to any one of [1] to

[10] .

[13] The method for manufacturing a molded article according to

[12] , wherein the cylinder temperature during injection molding is 20°C or higher than the melting point of polyamide resin A and less than the melting point of polyamide resin B.

[0006] The present invention provides a resin composition capable of producing molded articles with excellent color vibrancy and appearance, as well as a molded article and a method for producing a molded article.

[0007] Hereinafter, embodiments for carrying out the present invention (hereinafter simply referred to as "these embodiments") will be described in detail. These embodiments are illustrative examples for explaining the present invention, and the present invention is not limited to these embodiments. In this specification, "~" is used to mean that the numerical values ​​before and after it include the lower and upper limits. Furthermore, the upper and lower limits of numerical values ​​in this specification are given as examples of these embodiments, regardless of the combination of the upper and lower limits. In this specification, preferred combinations of embodiments are more preferred embodiments. In this specification, all physical properties and characteristic values ​​are given at 23°C unless otherwise specified.

[0008] In this specification, unless otherwise specified, the number-average molecular weight shall be the value measured by the following method. The number-average molecular weight (Mn) shall be determined from the value converted to standard polymethyl methacrylate (PMMA) by gel permeation chromatography (GPC). Two columns packed with styrene polymer as the packing material shall be used, and hexafluoroisopropanol (HFIP) with a sodium trifluoroacetate concentration of 2 mmol / L shall be used as the solvent, with a resin concentration of 0.02% by mass, a column temperature of 40°C, a flow rate of 0.3 mL / min, and measurement shall be performed using a refractive index detector (RI). A calibration curve shall be obtained by dissolving six levels of PMMA in HFIP and measuring the values.

[0009] If the measurement methods, etc., described in the standards shown in this specification differ from year to year, unless otherwise specified, the standards as of January 1, 2024 shall apply. If the measurement methods, etc., described in the standards shown in this specification have been abolished as of January 1, 2024, the standards in effect at the time of abolition shall apply.

[0010] The resin composition of this embodiment comprises polyamide resin A, polyamide resin B, and a colorant, wherein polyamide resin A comprises diamine units and dicarboxylic acid units, the diamine units contain 70 mol% or more of xylylenediamine units, and the dicarboxylic acid units contain 70 mol% or more of α,ω-linear aliphatic dicarboxylic acid units having 11 to 20 carbon atoms, and the polyamide resin B is present in a quantity of 0.5 to 20 parts by mass per 100 parts by mass of the total of polyamide resin A and polyamide resin B, and the difference (Tmb - Tma) between the melting point Tmb of polyamide resin B according to differential scanning calorimetry (DSC) and the melting point Tma of polyamide resin A according to differential scanning calorimetry (DSC) is 35 to 150°C. With this configuration, a resin composition is obtained that can provide molded products with excellent color sharpness and appearance. Polyamide resins are generally crystalline resins, and molded products formed from crystalline polyamide resins tend to exhibit some cloudiness. Therefore, even when colorants are added to molded products made from polyamide resins, the resulting color tends to lack sharpness. Furthermore, the appearance of the molded product may be inferior. To address these problems, conventional methods have included blending amorphous polyamide resins with crystalline polyamide resins, or incorporating dyes along with pigments as colorants into crystalline polyamide resins.

[0011] In contrast, this embodiment solves the above problem by using polyamide resin A and crystalline polyamide resin B, which has a higher melting point than polyamide resin A, in combination. This is presumed to be due to the following reasons. That is, by using polyamide resin A and polyamide resin B with different melting points, when molding a resin composition containing polyamide resin A and polyamide resin B, polyamide resin A can be melted, while polyamide resin B can remain partially or completely unmelted. As a result, it is presumed that polyamide resin B can act as a nucleating agent when molding a resin composition containing polyamide resin A and polyamide resin B. Here, it is known that the larger the surface area of ​​a nucleating agent, the more effective it is. Furthermore, polyamide resin A and polyamide resin B have good compatibility, and polyamide resin B can be finely dispersed in polyamide resin A. Also, as mentioned above, crystalline polyamide resin tends to become cloudy when it crystallizes. This is due to the reflection and scattering of light at the interface between the crystalline and amorphous parts. On the other hand, as the crystalline region becomes smaller, the effects of reflection and scattering at the interface decrease, and transparency tends to improve. In this embodiment, by using polyamide resin A with a low degree of crystallinity and a finely dispersed nucleating agent (polyamide resin B), it is presumed that the crystalline region formed in the molded product could be reduced, thereby further improving transparency. As a result, even when a colorant was added, the inherent color of the colorant could be effectively expressed. Furthermore, it is presumed that the slow crystallization of the resin composition resulted in a molded product with excellent appearance. In addition, the molded product formed from the resin composition of this embodiment had high surface hardness.

[0012] The embodiments of the present invention will be described in detail below, but the description of the constituent elements described below is merely one example of an embodiment of the present invention and is not limited to these.

[0013] <Polyamide Resin A> The resin composition of this embodiment includes polyamide resin A. Polyamide resin A contains diamine units (constituent units derived from diamine) and dicarboxylic acid units (constituent units derived from dicarboxylic acid), wherein the diamine units contain 70 mol% or more of xylylenediamine units (constituent units derived from xylylenediamine), and the dicarboxylic acid units contain 70 mol% or more of α,ω-linear aliphatic dicarboxylic acid units having 11 to 20 carbon atoms (constituent units derived from α,ω-linear aliphatic dicarboxylic acid having 11 to 20 carbon atoms). By using such polyamide resin A, a resin composition capable of providing molded articles with excellent appearance can be obtained.

[0014] The diamine units of polyamide resin A are more preferably 75 mol% or more, even more preferably 80 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and especially most preferably 99 mol% or more, which are xylylenediamine units (preferably para-xylylenediamine units and / or meta-xylylenediamine units). The upper limit of the total of the para-xylylenediamine units and meta-xylylenediamine units is 100 mol%.

[0015] It is preferable that 20 to 100 mol% of the diamine units of xylylenediamine are metaxylylenediamine units and 80 to 0 mol% are paraxylylenediamine units (however, the total of metaxylylenediamine units and paraxylylenediamine units does not exceed 100 mol%), more preferably 50 to 100 mol% of the diamine units are metaxylylenediamine units and 50 to 0 mol% are paraxylylenediamine units, even more preferably 55 to 80 mol% of the diamine units are metaxylylenediamine units and 45 to 20 mol% are paraxylylenediamine units, and even more preferably 60 to 80 mol% of the diamine units are metaxylylenediamine units and 40 to 20 mol% are paraxylylenediamine units.

[0016] Other diamines that can be used as raw material diamine components for polyamide resin A, besides metaxylylenediamine and paraxylylenediamine, include aliphatic diamines such as tetramethylenediamine, pentamethylenediamine, 2-methylpentanediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, dodecamethylenediamine, 2,2,4-trimethyl-hexamethylenediamine, and 2,4,4-trimethylhexamethylenediamine, as well as 1,3-bis(aminomethyl) Examples of alicyclic diamines such as cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, bis(4-aminocyclohexyl)methane, 2,2-bis(4-aminocyclohexyl)propane, bis(aminomethyl)decalin, and bis(aminomethyl)tricyclodecane, as well as aromatic ring-containing diamines such as bis(4-aminophenyl) ether, paraphenylenediamine, and bis(aminomethyl)naphthalene, can be used individually or in combination of two or more.

[0017] On the other hand, of the polyamide resin A used in this embodiment, 70% or more, preferably 75 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and especially most preferably 99 mol% or more are α,ω-linear aliphatic dicarboxylic acid units having 11 to 20 carbon atoms (preferably α,ω-linear aliphatic dicarboxylic acid units having 11 to 15 carbon atoms, more preferably α,ω-linear aliphatic dicarboxylic acid units having 12 to 14 carbon atoms, and even more preferably dodecanediic acid units).

[0018] Preferred α,ω-linear aliphatic dicarboxylic acids having 11 to 20 carbon atoms to be used as the raw material dicarboxylic acid component of polyamide resin A used in this embodiment include, for example, aliphatic dicarboxylic acids such as undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, heptadecanedioic acid, octadecanedioic acid, nonadecanedioic acid, and eicosanedioic acid. One or more of these can be used in combination, but among these, dodecanedioic acid and / or tetradecanedioic acid are preferred, and dodecanedioic acid is more preferred. An example of polyamide resin A used in this embodiment is one in which dodecanedioic acid is used as the raw material dicarboxylic acid, and sebacic acid is not used.

[0019] Examples of dicarboxylic acid components other than the above-mentioned α,ω-linear aliphatic dicarboxylic acids having 11 to 20 carbon atoms include α,ω-linear aliphatic dicarboxylic acids having 10 or fewer carbon atoms such as adipic acid and sebacic acid, phthalate compounds such as isophthalic acid, terephthalic acid, and orthophthalic acid, and isomers of naphthalenedicarboxylic acids such as 1,2-naphthalenedicarboxylic acid, 1,3-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 1,7-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid. One or more of these can be used in combination.

[0020] In this embodiment, a preferred embodiment of the polyamide resin A is characterized in that 70 mol% or more (preferably 80 mol% or more, more preferably 90 mol% or more, and even more preferably 95 mol% or more) of the dicarboxylic acid units are dodecanediol units and / or tetradecanediol units (preferably dodecanediol units). Dodecanediol and xylylenediamine may be derived from biological sources (biomass raw materials). Furthermore, in the above embodiment, it is preferable that 20 to 100 mol% of the diamine units are metaxylylenediamine units and 80 to 0 mol% are paraxylylenediamine units, and it is more preferable that 55 to 80 mol% of the diamine units are metaxylylenediamine units and 45 to 20 mol% are paraxylylenediamine units.

[0021] In this embodiment, it is preferable that the polyamide resin A used is a polyamide resin manufactured using biomass raw materials (biomass polyamide resin). By using a biomass polyamide resin, the environmental burden can be reduced. In polyamide resin A, biododecanedioic acid and xylylenediamine can be used as biomass raw materials. In addition, xylylenediamine certified by Mass Balance Certification (ISCC PLUS) can also be used. Mass balance certification means that the extent to which renewable raw materials and bio-raw materials are used in each factory or production facility, and how much of the product is produced or shipped, is quantified and guaranteed together with the quality.

[0022] In this embodiment, the polyamide resin A is mainly composed of diamine units and dicarboxylic acid units, but it goes without saying that other constituent units are not completely excluded, and may also contain lactam units such as ε-caprolactam and laurolactam, and aliphatic aminocarboxylic acid units such as aminocaproic acid and aminoundecanoic acid. Here, "main component" means that among the constituent units of polyamide resin A, the total number of diamine units and dicarboxylic acid units is the largest among all constituent units. In this embodiment, the total of diamine units and dicarboxylic acid units in polyamide resin A preferably accounts for 90% by mass or more of the total constituent units, more preferably 95% by mass or more, even more preferably 97% by mass or more, and even more preferably 99% by mass or more.

[0023] The melting point Tma of the polyamide resin A used in this embodiment, as determined by differential scanning calorimetry (DSC), is preferably 200°C or higher, more preferably 250°C or lower, more preferably 230°C or lower, and even more preferably 210°C or lower. Setting it above the lower limit tends to improve the heat resistance and elastic modulus of the resulting molded article. Setting it below the upper limit tends to improve the transparency of the resulting molded article and the moldability of the resin composition. If the resin composition of this embodiment contains two or more types of polyamide resin A, the melting point of the polyamide resin shall be the melting point of the resin with the highest content. If the polyamide resin A contained in the resin composition of this embodiment exhibits two or more melting points, the melting point of the polyamide resin shall be the lowest melting point. The melting point is measured according to the description in the examples below.

[0024] The polyamide resin A used in this embodiment may be recycled polyamide resin A (including recovered products, material recycled products, chemical recycled products, etc.), rejected products, or scraps generated when molding molded products from polyamide resin compositions.

[0025] The polyamide resin A used in this embodiment preferably has a lower limit of number average molecular weight (Mn) of 6,000 or more, more preferably 8,000 or more, even more preferably 10,000 or more, and also preferably 35,000 or less, more preferably 30,000 or less, and even more preferably 25,000 or less. Within this range, heat resistance, elastic modulus, dimensional stability, and moldability are improved.

[0026] <Polyamide Resin B> The resin composition of this embodiment includes polyamide resin B. Polyamide resin B is not particularly specified as long as the difference (Tmb - Tma) between the melting point Tmb of polyamide resin B according to differential scanning calorimetry (DSC) and the melting point Tma of polyamide resin A according to differential scanning calorimetry (DSC) is 35 to 150°C. As long as polyamide resin B has the desired melting point difference described above, its type and other aspects are not particularly specified, and any known polyamide resin can be used. The polyamide resin may be an aliphatic polyamide resin or a semi-aromatic polyamide resin, with semi-aromatic polyamide resins being preferred. Examples of aliphatic polyamide resins include polyamide 4, polyamide 46, polyamide 6, polyamide 66, polyamide 666, polyamide 610, polyamide 612, polyamide 11, polyamide 12, etc., with polyamide 46 and / or polyamide 66 being preferred, and polyamide 66 being more preferred.

[0027] As for the semi-aromatic polyamide resin, there is no particular requirement as long as it has a desired difference in melting point from polyamide resin A, but polyamide resin B1 is preferred, which contains diamine units and dicarboxylic acid units, wherein the diamine units contain 70 mol% or more of xylylenediamine units, and the dicarboxylic acid units contain 70 mol% or more of α,ω-linear aliphatic dicarboxylic acid units having 4 to 10 carbon atoms.

[0028] The diamine units of polyamide resin B1 are preferably derived from xylylenediamine (preferably para-xylylenediamine) in an amount of 70 mol% or more, more preferably 75 mol% or more, even more preferably 80 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and especially most preferably 99 mol% or more.

[0029] More specifically, xylylenediamine is preferably composed of 0 to 90 mol% metaxylylenediamine units and 100 to 10 mol% paraxylylenediamine units (provided that the total of metaxylylenediamine units and paraxylylenediamine units does not exceed 100 mol%), more preferably 0 to 50 mol% metaxylylenediamine units and 100 to 50 mol% paraxylylenediamine units, even more preferably 0 to 30 mol% metaxylylenediamine units and 100 to 70 mol% paraxylylenediamine units, and even more preferably 0 to 20 mol% metaxylylenediamine units and 100 to 80 mol% paraxylylenediamine units. In polyamide resin B1, it is preferable that the total of para-xylylenediamine units and meta-xylylenediamine units constitutes preferably 80 mol% or more, more preferably 85 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, even more preferably 98 mol% or more, and even more preferably 99 mol% or more of the diamine units. The upper limit of the total of the para-xylylenediamine units and meta-xylylenediamine units is 100 mol%.

[0030] Other diamines that can be used as raw material diamine components for polyamide resin B1 are the same as the other diamines that can be used as raw material diamine components for polyamide resin A.

[0031] On the other hand, of the dicarboxylic acid units in the polyamide resin B1 used in this embodiment, preferably 75 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and especially most preferably 99 mol% or more, are derived from α,ω-linear aliphatic dicarboxylic acids having 4 to 10 carbon atoms (preferably adipic acid and / or sebacic acid, more preferably sebacic acid).

[0032] Examples of dicarboxylic acid components other than the above-mentioned α,ω-linear aliphatic dicarboxylic acids having 4 to 10 carbon atoms include α,ω-linear aliphatic dicarboxylic acids having 11 to 20 carbon atoms, phthalate compounds such as isophthalic acid, terephthalic acid, and orthophthalic acid, and isomers of naphthalenedicarboxylic acids such as 1,2-naphthalenedicarboxylic acid, 1,3-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 1,7-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid. One or more of these can be used in combination.

[0033] As a preferred embodiment of the polyamide resin B1 in this embodiment, 70 mol% or more (preferably 80 mol% or more, more preferably 90 mol% or more, and even more preferably 95 mol% or more) of the dicarboxylic acid units are derived from sebacic acid. Sebacic acid may be derived from biological raw materials (biomass raw materials). Furthermore, in the above embodiment, it is preferable that 0 to 20 mol% of the diamine units are derived from metaxylylenediamine and 100 to 80 mol% are derived from paraxylylenediamine.

[0034] In this embodiment, the polyamide resin B1 is mainly composed of diamine units and dicarboxylic acid units, but it goes without saying that other constituent units are not completely excluded, and may also contain lactams such as ε-caprolactam and laurolactam, and aliphatic aminocarboxylic acid units such as aminocaproic acid and aminoundecanoic acid. Here, "main component" means that the total number of diamine units and dicarboxylic acid units is the largest among all constituent units of the polyamide resin B1. In this embodiment, the total of diamine units and dicarboxylic acid units in the polyamide resin B1 preferably accounts for 90% by mass or more of the total constituent units, more preferably 95% by mass or more, even more preferably 97% by mass or more, and even more preferably 99% by mass or more.

[0035] The melting point Tmb according to the differential scanning calorimetry (DSC) of the polyamide resin B used in this embodiment is preferably 260°C or higher, and preferably 320°C or lower, more preferably 310°C or lower, and even more preferably 300°C or lower. By setting it to be not less than the lower limit value, crystallization in a low-temperature mold and transparency tend to be further improved. Also, by setting it to be not more than the upper limit value, the moldability tends to be further improved. When the resin composition of this embodiment contains two or more kinds of polyamide resin B, the melting point of the polyamide resin is the melting point of the resin with the highest content. When the polyamide resin B contained in the resin composition of this embodiment exhibits two or more melting points, the melting point of the polyamide resin is the lowest melting point. The melting point is measured according to the description of the examples described later.

[0036] The polyamide resin B used in this embodiment is preferably a polyamide resin (biomass polyamide resin) produced using a biomass raw material. By using a biomass polyamide resin, the environmental load can be reduced. In the polyamide resin B, as the biomass raw material, biosebacic acid and xylylenediamine can be used. Also, xylylenediamine certified by mass balance (ISCC PLUS) can be used. Mass balance certification means that it quantifies how much renewable raw materials and bio-based raw materials are used for each factory and production facility, and how much products are produced and shipped, and is guaranteed together with the quality.

[0037] The polyamide resin B used in this embodiment may be a recycled product of the polyamide resin B (including recovered products, material recycled products, chemical recycled products, etc.), a defective product, or a scrap material generated when molding a molded product from the polyamide resin composition.

[0038] The polyamide resin B used in this embodiment preferably has a lower limit of number average molecular weight (Mn) of 6,000 or more, more preferably 8,000 or more, even more preferably 10,000 or more, and also preferably 35,000 or less, more preferably 30,000 or less, and even more preferably 25,000 or less. Within this range, heat resistance, elastic modulus, dimensional stability, and moldability are improved.

[0039] <Blend of Polyamide Resin A and Polyamide Resin B> The blend contains 0.5 to 20 parts by mass of polyamide resin B per 100 parts by mass of the total of polyamide resin A and polyamide resin B. Setting the blend above the lower limit tends to promote more effective crystallization of the resin composition in the mold at low temperatures. Setting the blend below the upper limit tends to improve the impact resistance of the resulting molded product. The content of polyamide resin B per 100 parts by mass of the total of polyamide resin A and polyamide resin B is preferably 0.7 parts by mass or more, more preferably 1 part by mass or more, even more preferably 1.5 parts by mass or more, even more preferably 2 parts by mass or more, even more preferably 3 parts by mass or more, and also preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 6 parts by mass or less. Setting the blend above the lower limit tends to promote more effective crystallization of the resin composition at low temperatures. Even setting the blend below the upper limit tends to improve the appearance of the resulting molded product.

[0040] In the resin composition of the present embodiment, the total content of polyamide resin A and polyamide resin B used in the present embodiment is preferably 40 to 100% by mass in the resin composition. When the resin composition of the present embodiment contains reinforcing fibers, the total content of polyamide resin A and polyamide resin B is preferably 40% by mass or more, more preferably 50% by mass or more, further preferably 60% by mass or more, still more preferably 64% by mass or more, and may be 68% by mass or more. Also, it is preferably 85% by mass or less, more preferably 80% by mass or less, and may be 75% by mass or less. When the resin composition of the present embodiment does not contain reinforcing fibers, the total content of polyamide resin A and polyamide resin B is preferably 90% by mass or more, more preferably 95% by mass or more, further preferably 97% by mass or more, and is preferably 100% by mass or less, and may be 99% by mass or less. The resin composition of the present embodiment may contain only one kind of polyamide resin A and polyamide resin B used in the present embodiment, or may contain two or more kinds. When containing two or more kinds, it is preferable that the total amount is within the above range.

[0041] In the polyamide resin A in the present embodiment, the difference in the number of carbon atoms of the dicarboxylic acid unit and the number of carbon atoms of the dicarboxylic acid unit in the polyamide resin B is preferably 1 or more, preferably 1.5 or more, more preferably 1.8 or more. Also, it is preferably 4.2 or less, more preferably 3.0 or less. The number of carbon atoms of the dicarboxylic acid unit is, for example, 10 in the case of a dodecane diacid unit. When polyamide resin A and / or polyamide resin B contains two or more kinds of dicarboxylic acid units, the number of carbon atoms of the carboxylic acid unit is the sum of the values obtained by multiplying the number of carbon atoms of each dicarboxylic acid unit by the molar fraction. In the present embodiment, such a difference in the number of carbon atoms greatly contributes to the effects of the present invention.

[0042] The difference (Tmb-Tma) between the melting point Tmb of polyamide resin B, determined by differential scanning calorimetry (DSC), and the melting point Tma of polyamide resin A, determined by differential scanning calorimetry (DSC), is 35 to 150°C. Setting it above the lower limit tends to promote more effective crystallization of the resin composition. It also tends to improve the transparency of the resulting molded product. Setting it below the upper limit tends to improve the moldability of the resin composition. The difference in melting points (Tmb-Tma) is preferably 40°C or higher, more preferably 45°C or higher, even more preferably 50°C or higher, even more preferably 55°C or higher, even more preferably 60°C or higher, even more preferably 66°C or higher, even more preferably 68°C or higher, particularly preferably 70°C or higher, and also preferably 100°C or lower, more preferably 90°C or lower, and even more preferably 80°C or lower. The melting point is measured according to the examples described later.

[0043] <Coloring Agent> The resin composition of this embodiment contains a coloring agent. By including a coloring agent, the resulting molded product can be given color. The type of coloring agent is not particularly specified and may be a chromatic coloring agent or an achromatic coloring agent. The coloring agent may also be a pigment, a dye, or a mixture of a pigment and a dye. In this embodiment, even if only a pigment is used as the coloring agent, a molded product with excellent color vibrancy can be obtained.

[0044] In this embodiment, a black coloring agent is preferred, and carbon black is more preferred. There are no restrictions on the type, raw material, or manufacturing method of the carbon black; furnace black, channel black, acetylene black, Ketjen black, etc., can be used. Among these, furnace black is preferred.

[0045] DBP oil absorption capacity of carbon black (unit: cm) ３ (100g) is 40-300cm ３ It is preferable that it be / 100g. The upper limit is 300cm ３It is preferably 100 g or less, and more preferably 200 cm ３ / 100 g or less. The lower limit is preferably 40 cm ３ / 100 g or more, more preferably 80 cm ３ / 100 g or more, even more preferably 100 cm ３ / 100 g or more, still more preferably 120 cm ３ / 100 g or more may also be acceptable. By setting within the above upper and lower limits, the appearance of the obtained molded product tends to be improved. The DBP oil absorption amount (unit: cm ３ / 100 g) can be measured in accordance with JIS K6217-4.

[0046] The nitrogen adsorption specific surface area of carbon black (unit: m ２ / g) is preferably 100 to 200 m ２ / g. The nitrogen adsorption specific surface area is measured in accordance with JIS K6217-2.

[0047] The number average particle diameter of carbon black (unit: nm) is preferably 5 to 60 nm. The upper limit is preferably 60 nm or less, more preferably 40 nm or less, even more preferably 30 nm or less, and still more preferably 25 nm or less. The lower limit is preferably 10 nm or more, more preferably 13 nm or more, even more preferably 16 nm or more, and still more preferably 19 nm or more. By setting within the above upper and lower limits, the appearance of the obtained molded product tends to be improved. The number average particle diameter can be obtained by acquiring an aggregate enlarged image according to the procedure described in ASTM D3849 standard (Standard Test Method for Carbon Black - Morphological Characterization by Electron Microscopy), measuring the particle diameters of 3,000 particles as unit constituent particles from this aggregate image, and calculating the arithmetic mean.

[0048] It is preferable that carbon black is blended as a masterbatch premixed with a thermoplastic resin because the dispersion degree of carbon black increases and the mechanical physical properties of the obtained molded product tend to be improved.

[0049] The colorant content in the resin composition of this embodiment is 0.01 parts by mass or more, preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and even more preferably 0.3 parts by mass or more, based on 100 parts by mass of the total of polyamide resin A and polyamide resin B. By setting the amount above the lower limit, the resulting molded product can be given sufficient color. The upper limit of the colorant content is 10 parts by mass or less, preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and even more preferably 1 part by mass or less, based on 100 parts by mass of the total of polyamide resin A and polyamide resin B. By setting the amount below the upper limit, the various physical properties of the resulting molded product tend to improve further. The resin composition of this embodiment may contain only one type of colorant or two or more types. When two or more types are included, it is preferable that the total amount is within the above range.

[0050] The resin composition of this embodiment may also be substantially free of dyes. Specifically, the proportion of dyes in the colorants contained in the resin composition is preferably less than 10% by mass, more preferably less than 7% by mass, even more preferably less than 5% by mass, even more preferably less than 3% by mass, may be less than 1% by mass, may be less than 0.1% by mass, or may be 0% by mass.

[0051] <Reinforcement Fibers> The resin composition of this embodiment may contain reinforcement fibers. By including reinforcement fibers, the mechanical strength of the resulting molded product can be improved. Examples of reinforcement fibers include carbon fibers and glass fibers, and it is preferable to include glass fibers.

[0052] In this embodiment, the reinforcing fiber refers to a fibrous inorganic material, and more specifically, a chopped shape is preferred, which is obtained by bundling 1,000 to 10,000 reinforcing fibers and cutting them to a predetermined length. In this embodiment, the reinforcing fiber has a number-average fiber length of 0.5 to 10 mm, and more preferably 1 to 5 mm. By using reinforcing fibers with such a number-average fiber length, the mechanical strength can be further improved. The number-average fiber length is calculated by randomly selecting the reinforcing fiber to be measured from an image obtained by observation with an optical microscope, measuring its long side, and then calculating the number-average fiber length from the obtained measurement value. The observation magnification is set to 20x, and the number of fibers measured is 1,000 or more. It roughly corresponds to the cut length. Furthermore, the cross-section of the reinforcing fiber may be circular, elliptical, oblong, rectangular, a shape with semicircles on both short sides of a rectangle, or cocoon-shaped, but circular or elliptical is preferred. Here, circular includes not only a circle in the mathematical sense, but also what is commonly referred to as circular in the technical field of this embodiment. The number-average fiber diameter of the reinforcing fibers is preferably 4.0 μm or more at the lower limit, more preferably 4.5 μm or more, and even more preferably 5.0 μm or more. The number-average fiber diameter of the reinforcing fibers is preferably 15.0 μm or less, and more preferably 12.0 μm or less at the upper limit. The number-average fiber diameter of the reinforcing fibers is calculated by randomly selecting glass fibers to be measured from an image obtained by observation with an electron microscope, measuring the fiber diameter near the center, and obtaining the measured values. The observation magnification is 1,000x, and the number of measurements is 1,000 or more. For glass fibers with a cross-section other than circular, the number-average fiber diameter is the number-average fiber diameter when converted to a circle with the same area as the cross-sectional area.

[0053] Next, glass fibers preferably used in this embodiment will be described. The glass fibers used are generally supplied as E-glass (Electric glass), C-glass (Chemical glass), A-glass (Alkali glass), S-glass (High strength glass), D-glass, R-glass, and alkali-resistant glass.

[0054] The glass fibers used in this embodiment are preferably surface-treated with a surface treatment agent such as a silane coupling agent, such as γ-methacrylateoxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, or γ-aminopropyltriethoxysilane. The amount of surface treatment agent applied is preferably 0.01 to 1% by mass of the glass fibers. Furthermore, if necessary, glass fibers may be surface-treated with a lubricant such as a fatty acid amide compound or silicone oil, an antistatic agent such as a quaternary ammonium salt, a resin with film-forming ability such as epoxy resin or urethane resin, or a mixture of a resin with film-forming ability and a heat stabilizer or flame retardant.

[0055] The content of reinforcing fibers (preferably glass fibers) in the resin composition of this embodiment is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 30 parts by mass or more, and may be 40 parts by mass or more, or even 45 parts by mass or more, based on 100 parts by mass of the total of polyamide resin A and polyamide resin B. Setting the content above the lower limit tends to further improve the mechanical strength of the resulting resin molded product. Furthermore, the content of reinforcing fibers (preferably glass fibers) in the resin composition of this embodiment is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, even more preferably 60 parts by mass or less, and even more preferably 50 parts by mass or less, based on 100 parts by mass of the total of polyamide resin A and polyamide resin B. Setting the content below the upper limit tends to further improve the appearance of the resulting molded product.

[0056] Furthermore, the content of reinforcing fibers (preferably glass fibers) in the resin composition of this embodiment is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and may be 25% by mass or more. Setting it above the lower limit tends to further improve the mechanical strength of the resulting resin molded product. Furthermore, the content of reinforcing fibers (preferably glass fibers) in the resin composition of this embodiment is preferably 50% by mass or less, more preferably 40% by mass or less, and may be 35% by mass or less. Setting it below the upper limit tends to further improve the appearance of the resulting molded product. The resin composition of this embodiment may contain only one type of reinforcing fiber, or it may contain two or more types. When two or more types are included, it is preferable that the total amount is within the above range.

[0057] <Other Components> The resin composition of this embodiment may contain components other than those listed above. Examples of other components include thermoplastic resins other than polyamide resins and resin additives. Examples of resin additives include nucleating agents, mold release agents, heat stabilizers, light stabilizers, antioxidants, UV inhibitors, alkalis, hydrolysis resistance improvers, matting agents, plasticizers, dispersants, antistatic agents, gelation inhibitors, flame retardants, etc. The total amount of resin additives is preferably 20.0% by mass or less of the resin composition, more preferably 10.0% by mass or less, even more preferably 5.0% by mass or less, and most preferably 1.0% by mass or less. Only one type of other additive may be used, or two or more types may be used in combination.

[0058] Details of other additives can be found in paragraphs 0130 to 0155 of Japanese Patent No. 4894982, and these contents are incorporated herein by reference. Furthermore, the resin composition of this embodiment may incorporate additives described in paragraphs 0047 to 0103 of International Publication No. 2021 / 241471, without departing from the spirit of the present invention, and these contents are incorporated herein by reference. The resin composition of this embodiment may also be substantially free of inorganic nucleating agents and organic nucleating agents other than polyamide resin. Specifically, the total amount of inorganic nucleating agents and organic nucleating agents other than polyamide resin contained in the resin composition is preferably less than 10% by mass of the polyamide resin content, more preferably less than 7% by mass, even more preferably less than 5% by mass, even more preferably less than 3% by mass, and may be less than 1% by mass.

[0059] An example of the total amount of polyamide resin A, polyamide resin B, and colorant in the resin composition of this embodiment is 90% by mass or more, preferably 95% by mass or more, more preferably 97% by mass or more, and even more preferably 98% by mass or more, based on 100% by mass of the resin composition. Another example of the total amount of polyamide resin A, polyamide resin B, colorant, and reinforcing fiber in the resin composition of this embodiment is 90% by mass or more, preferably 95% by mass or more, more preferably 97% by mass or more, and even more preferably 98% by mass or more, based on 100% by mass of the resin composition.

[0060] In this embodiment, the resin composition is prepared such that the total amount of each component is 100% by mass, with adjustments made to the content of polyamide resin A, polyamide resin B, colorants, and other components added as needed.

[0061] <<Antioxidants>> The resin composition of this embodiment may further contain antioxidants. By including antioxidants, molded articles with excellent heat resistance can be obtained. Examples of antioxidants include phenolic antioxidants (preferably hindered phenolic antioxidants), amine antioxidants, phosphorus antioxidants, sulfur antioxidants, copper compounds, and alkali halides. As antioxidants, the antioxidants described in paragraphs 0025 to 0030 of Japanese Patent Publication No. 6466632, the antioxidants described in paragraphs 0017 to 0020 of Japanese Unexamined Patent Publication No. 2016-074804, the antioxidants described in paragraphs 0044 to 0048 of Japanese Unexamined Patent Publication No. 2021-038370, the antioxidants described in paragraphs 0043 to 0056 of Japanese Unexamined Patent Publication No. 2012-179911, the antioxidants described in paragraphs 0045 to 0056 of Japanese Unexamined Patent Publication No. 2020-033539, and the antioxidants described in paragraphs 0030 to 0038 of International Publication No. 2010 / 143638 can be used, and the contents of these are incorporated herein.

[0062] If the resin composition of this embodiment contains an antioxidant, its content is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, even more preferably 0.1 parts by mass or more, even more preferably 0.2 parts by mass or more, and even more preferably 0.4 parts by mass or more, per 100 parts by mass of polyamide resin (total of polyamide resin A and polyamide resin B). Setting the content above the lower limit tends to improve the retention rate of mechanical strength. Furthermore, the content is preferably 10.0 parts by mass or less, more preferably 5.0 parts by mass or less, even more preferably 3.0 parts by mass or less, even more preferably 2.0 parts by mass or less, and even more preferably 1.5 parts by mass or less, per 100 parts by mass of polyamide resin (total of polyamide resin A and polyamide resin B). Setting the content below the upper limit tends to reduce outgassing during molding, thus reducing mold contamination and improving continuous productivity. The resin composition of this embodiment may contain only one type of antioxidant, or it may contain two or more types. If two or more types are included, it is preferable that the total amount falls within the above range.

[0063] <<Release Agent>> The resin composition of this embodiment may contain a release agent. Examples of release agents include aliphatic carboxylic acids, salts of aliphatic carboxylic acids, esters of aliphatic carboxylic acids and alcohols, aliphatic hydrocarbon compounds with a number average molecular weight of 200 to 15,000, polysiloxane-based silicone oils, ketone waxes, and light amides. Aliphatic carboxylic acids, salts of aliphatic carboxylic acids, and esters of aliphatic carboxylic acids and alcohols are preferred, and salts of aliphatic carboxylic acids are more preferred. Details of the release agent can be found in paragraphs 0055 to 0061 of Japanese Patent Application Publication No. 2018-095706, and these contents are incorporated herein. When the resin composition of this embodiment contains a release agent, its content is preferably 0.05 to 3% by mass, more preferably 0.1 to 0.8% by mass, and even more preferably 0.2 to 0.6% by mass. The resin composition of this embodiment may contain only one type of release agent, or it may contain two or more types. If two or more types are included, it is preferable that the total amount falls within the above range.

[0064] <Physical properties of the resin composition> The resin composition of this embodiment has a color difference L ＊ It is preferable that the L is small. Specifically, it is preferable that the color difference measured according to JIS Z 8722 when the resin composition of this embodiment is molded into a plate with a thickness of 2 mm be less than 4.0, and preferably 3.5 or less. ＊ The lower limit is practically 0.1 or higher. The resin composition of this embodiment preferably has high hardness. Specifically, it is preferable that the pencil hardness measured according to ISO 15184 when the resin composition of this embodiment is molded into a 2 mm thick plate is H or higher. The upper limit of the pencil hardness is practically 3H or lower. Details of the methods for measuring color difference and pencil hardness will be described in the examples below.

[0065] The resin composition of this embodiment preferably has high gloss. Specifically, the resin composition of this embodiment (or the resin composition excluding reinforcing fibers if it contains reinforcing fibers) is molded into a plate measuring 100 mm in length, 100 mm in width, and 2 mm thick, and it is preferable that the gloss at 20 degrees Celsius, according to JIS Z 8741, is 95 or higher, and preferably 100 or higher. There is no particular upper limit to the gloss, but 120 or lower is practical. In this embodiment, the gloss can be significantly increased by using polyamide resin A.

[0066] <Method for Manufacturing the Resin Composition> In this embodiment, the method for manufacturing the resin composition is not particularly specified, and a wide range of known methods for manufacturing thermoplastic resin compositions can be used. Specifically, the resin composition can be manufactured by pre-mixing each component using various mixers such as tumblers and Henschel mixers, and then melt-kneading them using a Banbury mixer, rolls, brabender, single-screw extruder, twin-screw extruder, kneader, etc.

[0067] Furthermore, for example, a resin composition can be manufactured by supplying the components to an extruder using a feeder and melt-kneading them, either without pre-mixing each component or by pre-mixing only some of the components. In addition, for example, a composition obtained by pre-mixing some of the components and supplying it to an extruder for melt-kneading can be used as a masterbatch, and pellets can be manufactured by mixing this masterbatch with the remaining components again and melt-kneading it. In particular, it is preferable to incorporate pigments as a masterbatch. Also, it is preferable to side-feed the reinforcing fibers.

[0068] <Uses of the Resin Composition and Molded Articles> The molded articles of this embodiment are formed from the resin composition or pellets of this embodiment. There is no particular method for manufacturing the molded articles of this embodiment. As an example, an injection-molded article formed by injection molding is provided. For example, the molded articles of this embodiment may be formed by melting and kneading each component and then directly molding them using various molding methods, or the components may be melted and kneaded to form pellets, then melted again and molded using various molding methods.

[0069] The method for molding the molded product is not particularly limited, and conventionally known molding methods can be used. Examples include injection molding, injection compression molding, extrusion molding, shape extrusion, transfer molding, hollow molding, gas-assisted hollow molding, blow molding, extrusion blow molding, IMC (in-mold coating) molding, rotational molding, multilayer molding, two-color molding, insert molding, sandwich molding, foam molding, and pressure molding. The method for manufacturing the molded product in this embodiment preferably includes injection molding of the resin composition. Furthermore, it is more preferable that the cylinder temperature during injection molding is 20°C or higher above the melting point of polyamide resin A and below the melting point of polyamide resin B. By setting the temperature within this range, injection molding can be performed without the polyamide resin B melting, and the crystallization of the resulting molded product can be more effectively promoted. The cylinder temperature is preferably 20°C or higher above the melting point of polyamide resin A and 20°C or lower below the melting point of polyamide resin B.

[0070] There are no particular restrictions on the shape of the molded product in this embodiment, and it can be appropriately selected according to the application and purpose of the molded product. Examples include plate-shaped, rod-shaped, sheet-shaped, film-shaped, cylindrical, annular, circular, elliptical, gear-shaped, polygonal, irregularly shaped, hollow, frame-shaped, box-shaped, and panel-shaped products.

[0071] The resin composition, pellets, and molded articles of this embodiment are not particularly limited in their application fields and are widely used in automobile and other transport equipment parts, general machine parts, precision machine parts, electronic and electrical equipment parts, office automation equipment parts, building materials and housing equipment related parts, medical devices, leisure and sports goods, play equipment, medical supplies, daily necessities such as food packaging films, defense and aerospace products, etc. The resin composition of this embodiment is also preferably used in hollow structures such as hoses and tubes. Further details can be found in paragraphs 0077 to 0079 of International Publication No. 2022 / 219988, which are incorporated herein by reference.

[0072] The present invention will be described in more detail below with reference to examples. The materials, amounts used, proportions, processing content, processing procedures, etc., shown in the following examples can be modified as appropriate, as long as they do not depart from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below. If the measuring instruments, etc., used in the examples are difficult to obtain due to discontinuation or other reasons, measurements can be taken using other instruments with equivalent performance.

[0073] 1. Raw Materials MP12 (30): Polyamide resin obtained in the synthesis example below MP10 (30): Polyamide resin obtained in the synthesis example below MXD6: Polyamide resin synthesized from metaxylylenediamine and adipic acid, manufactured by Mitsubishi Gas Chemical Co., Ltd., #6000 PXD10: Polyamide resin obtained in the synthesis example below PA66: Polyamide 66, manufactured by Toray Industries, Ltd., Amiran CM3001-N Glass fiber (GF): Circular cross-section glass fiber, E-glass, manufactured by Nippon Electric Glass Co., Ltd., T-756H, chopped strand, number average fiber diameter 10 μm, refractive index 1.57 Carbon black: Manufactured by Mitsubishi Chemical, Carbon Black #45 Dye: Manufactured by Sumika Chemitex, Sumiplast Black HB

[0074] <Example of synthesis of MP12 (30)> In a jacketed reaction vessel equipped with a stirrer, partial condenser, condenser, thermometer, dropping tank, and nitrogen gas inlet tube, 60 mol of accurately weighed dodecanediolate was placed, and the mixture was thoroughly purged with nitrogen. The temperature was then raised to 180°C under a small stream of nitrogen gas to dissolve the dodecanediolate and achieve a uniform fluid state. To this, 60 mol of para / metaxylylenediamine, in which 30 mol% of the diamine component was paraxylylenediamine and 70 mol% was metaxylylenediamine, was added dropwise over 160 minutes under stirring. During this time, the internal pressure of the reaction system was kept at atmospheric pressure, and the internal temperature was continuously raised to 240°C. Water distilled off with the addition of para / metaxylylenediamine was removed from the system through the partial condenser and condenser. After the addition of para / metaxylylenediamine was completed, the liquid temperature was maintained at 240°C and the reaction was continued for 10 minutes. Subsequently, the pressure inside the reaction system was continuously reduced to 600 Torr over 10 minutes, and the reaction was continued for 20 minutes. During this time, the reaction temperature was continuously raised to 250°C. After the reaction was complete, the reaction vessel was pressurized with nitrogen gas to 0.3 MPa, and the polymer was removed as strands from a nozzle at the bottom of the polymerization tank. After water cooling, the strands were cut into pellets to obtain pellets.

[0075] <Example of synthesis of MP10 (30)> In a jacketed reaction vessel equipped with a stirrer, partial condenser, condenser, thermometer, dropping tank, and nitrogen gas inlet tube, 60 mol of accurately weighed sebacic acid was placed and thoroughly purged with nitrogen. The temperature was then raised to 180°C under a small stream of nitrogen gas to dissolve the sebacic acid and achieve a uniform fluid state. To this, 60 mol of para / metaxylylenediamine, in which 30 mol% of the diamine component was paraxylylenediamine and 70 mol% was metaxylylenediamine, was added dropwise over 160 minutes under stirring. During this time, the internal pressure of the reaction system was kept at atmospheric pressure, and the internal temperature was continuously raised to 240°C. Water distilled off with the addition of para / metaxylylenediamine was removed from the system through the partial condenser and condenser. After the addition of para / metaxylylenediamine was completed, the liquid temperature was maintained at 240°C and the reaction was continued for 10 minutes. Subsequently, the pressure inside the reaction system was continuously reduced to 600 Torr over 10 minutes, and the reaction was continued for 20 minutes. During this time, the reaction temperature was continuously raised to 250°C. After the reaction was complete, the reaction vessel was pressurized with nitrogen gas to 0.3 MPa, and the polymer was removed as strands from a nozzle at the bottom of the polymerization tank. After water cooling, the strands were cut into pellets to obtain pellets.

[0076] <Example of PXD10 Synthesis> In a jacketed reaction vessel equipped with a stirrer, partial condenser, condenser, thermometer, dropping tank, and nitrogen gas inlet tube, 60 mol of accurately weighed sebacic acid was placed and thoroughly purged with nitrogen. The temperature was then raised to 180°C under a small stream of nitrogen gas to dissolve the sebacic acid and achieve a uniform fluid state. To this, 60 mol of paraxylylenediamine was added dropwise over 160 minutes with stirring. During this time, the internal pressure of the reaction system was maintained at atmospheric pressure, and the internal temperature was continuously raised to 295°C. Water distilled off with the addition of paraxylylenediamine was removed from the system through the partial condenser and condenser. After the addition of paraxylylenediamine was complete, the reaction was continued for 10 minutes while maintaining the liquid temperature at 295°C. Subsequently, the internal pressure of the reaction system was continuously reduced to 600 Torr over 10 minutes, and the reaction was continued for 20 minutes. During this time, the reaction temperature was continuously raised to 300°C. After the reaction was complete, the reaction vessel was pressurized with nitrogen gas at 0.3 MPa, and the polymer was removed as strands from a nozzle at the bottom of the polymerization tank. After water cooling, the strands were cut into pellets to obtain pellets.

[0077] <Measurement of Melting Point (Tm)> The melting point (Tm) was measured according to differential scanning calorimetry (DSC) in accordance with ISO 11357. Using a differential scanning calorimeter, the resin was placed in the measurement pan of the differential scanning calorimeter, heated to a temperature above the melting point at a heating rate of 10°C / min under a nitrogen atmosphere, and then rapidly cooled before measurement. The measurement conditions were: heating at a heating rate of 10°C / min, held at 300°C for 5 minutes, and then cooled to 100°C at a cooling rate of -5°C / min to determine the melting point (Tm). The unit is shown in °C. The differential scanning calorimeter used was the "DSC-60" manufactured by Shimadzu Corporation. In Tables 1 to 4 described later, Tma represents the melting point of polyamide resin A, Tmb represents the melting point of polyamide resin B, and Tmb-Tma represents the difference between the melting points of polyamide resin A and polyamide resin B.

[0078] 2. Examples 1-2, Comparative Examples 1-4 <Compound> Each component was weighed and blended in a tumbler to obtain the composition shown in Tables 1 and 2 below. The mixture was then fed into a twin-screw extruder (Shibaura Machinery Co., Ltd., TEM26SS) from the base and melted to produce pellets. The temperature settings for the twin-screw extruder are shown in Table 1 or Table 2. The values ​​of each component in Tables 1 and 2 are shown in mass percent.

[0079] <Injection Molding> After drying the pellets obtained above at 120°C for 8 hours, plates measuring 100 mm in length, 100 mm in width, and 2 mm thick were injection molded using an injection molding machine (Sumitomo Heavy Industries SE130DU) under the cylinder temperature and mold temperature conditions of 80°C as described in Tables 1 to 4.

[0080] <Color difference L ＊ > Regarding the above plate, in accordance with JIS Z 8722, a colorimeter (ZE-2000 manufactured by Nippon Denshoku Industries Co., Ltd.) was used under the following measurement conditions: L ＊ The values ​​were measured. Measurement conditions: Reflectance measurement, D65 light source, SCE method, field of view 10Φ

[0081] <Glossiness Gs> For the above plate, the glossiness (Gs20) of the molded product at 20 degrees was measured in accordance with JIS Z 8741. A VG8000 manufactured by Nippon Denshoku Industries Co., Ltd. was used as the measuring instrument.

[0082] <Visual Appearance Evaluation> The test specimens for which the above color difference was measured were visually evaluated for their appearance. The evaluation was conducted by five experts and decided by majority vote. The evaluation was based on the graininess, streaky patterns, color unevenness, scratch-like patterns, and overall darkness of the test specimens. Comparative Example 1 was given an evaluation of 3, and the evaluation was made on a 5-point scale. A higher numerical value indicates a better appearance.

[0083] <Pencil Hardness> The above plates were annealed at 150°C for 1 hour, and then their pencil hardness was measured according to ISO 15184.

[0084] 3. Examples 3 to 5, Comparative Examples 5 to 8 <Compound> Each component was weighed to obtain the composition shown in Tables 3 to 4 below. The components excluding glass fibers were blended in a tumbler, and the mixture was fed into a twin-screw extruder (Shibaura Machinery Co., Ltd., TEM26SS) from the base. After melting, glass fibers were side-fed to produce pellets. The temperature settings for the twin-screw extruder are shown in Table 3 or Table 4. The values ​​of each component in Tables 3 to 4 are shown in mass percent.

[0085] Color difference L ＊ The glossiness Gs and pencil hardness were evaluated in the same manner as in Example 1.

[0086] <Visual Appearance Evaluation> The test pieces for which the above color difference was measured were visually evaluated for appearance. The evaluation was conducted by five experts and decided by majority vote. Surface roughness was evaluated. Comparative Example 5 was given a rating of 3, and the evaluation was judged on a 5-point scale. A higher numerical value indicates a better appearance.

[0087]

[0088]

[0089]

[0090]

[0091] As is clear from the above results, molded articles formed from the resin composition of the present invention exhibited a sharp blackness and excellent appearance. Furthermore, the resin composition of the present invention yielded molded articles with high hardness.

[0092] Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications are possible without departing from the intent and scope of the invention.

Claims

1. A resin composition comprising polyamide resin A, polyamide resin B, and a colorant, wherein polyamide resin A comprises diamine units and dicarboxylic acid units, the diamine units comprise 70 mol% or more of xylylenediamine units, and the dicarboxylic acid units comprise 70 mol% or more of α,ω-linear aliphatic dicarboxylic acid units having 11 to 20 carbon atoms, the polyamide resin B is present in a quantity of 0.5 to 20 parts by mass per 100 parts by mass of the total of polyamide resin A and polyamide resin B, and the difference (Tmb - Tma) between the melting point Tmb of polyamide resin B determined by differential scanning calorimetry (DSC) and the melting point Tma of polyamide resin A determined by differential scanning calorimetry (DSC) is 35 to 150°C.

2. The resin composition according to claim 1, wherein 70 mol% or more of the dicarboxylic acid units of the polyamide resin A are dodecanediic acid units.

3. The resin composition according to claim 1 or 2, wherein 20 to 100 mol% of the diamine units of the polyamide resin A are metaxylylenediamine units and 80 to 0 mol% are paraxylylenediamine units.

4. The resin composition according to any one of claims 1 to 3, wherein the melting point Tmb of the polyamide resin B, as determined by differential scanning calorimetry (DSC), is 260 to 320°C.

5. The resin composition according to any one of claims 1 to 4, wherein 70 mol% or more of the diamine units of the polyamide resin B are para-xylylenediamine units, and 70 mol% or more of the dicarboxylic acid units are sebacic acid units.

6. The resin composition according to any one of claims 1 to 5, comprising 1 to 6 parts by mass of polyamide resin B with respect to a total of 100 parts by mass of polyamide resin A and polyamide resin B.

7. The resin composition according to any one of claims 1 to 6, wherein the coloring agent comprises a black coloring agent.

8. The resin composition according to any one of claims 1 to 7, further comprising reinforcing fibers.

9. The resin composition according to claim 8, wherein the reinforcing fibers include glass fibers.

10. The resin composition according to any one of claims 1 to 9, wherein 70 mol% or more of the dicarboxylic acid units of the polyamide resin A are dodecanedioic acid units, 20 to 100 mol% of the diamine units of the polyamide resin A are metaxylylenediamine units and 80 to 0 mol% are paraxylylenediamine units, the melting point Tmb of the polyamide resin B determined by differential scanning calorimetry (DSC) is 260 to 320°C, 70 mol% or more of the diamine units of the polyamide resin B are paraxylylenediamine units and 70 mol% or more of the dicarboxylic acid units are sebacic acid units, the polyamide resin B is contained in 1 to 6 parts by mass per 100 parts by mass of the total of the polyamide resin A and the polyamide resin B, the coloring agent contains a black coloring agent and further contains reinforcing fibers, and the reinforcing fibers contain glass fibers.

11. A molded article formed from the resin composition according to any one of claims 1 to 10.

12. A method for manufacturing a molded article, comprising injection molding a resin composition according to any one of claims 1 to 10.

13. The method for manufacturing a molded article according to claim 12, wherein the cylinder temperature during injection molding is 20°C or higher than the melting point of polyamide resin A and less than the melting point of polyamide resin B.

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