Thermoplastic polyester elastomer resin composition and molded article

Abstract

The present invention relates to a thermoplastic polyester elastomer resin composition capable of giving molded objects which have a satisfactory appearance and highly excellent wear resistance. The thermoplastic polyester elastomer resin composition comprises a thermoplastic polyester elastomer (A) including a hard segment comprising a polyester formed from an aromatic dicarboxylic acid and an aliphatic and / or alicyclic diol as constituent ingredients and, bonded thereto, at least one soft segment selected from among aliphatic polyethers, aliphatic polyesters, and aliphatic polycarbonates and a silicone / acrylic copolymer (B). When injection-molded, the thermoplastic polyester elastomer resin composition gives a molded article in which the silicone / acrylic copolymer (B), which is dispersed in the thermoplastic polyester elastomer (A) serving as a matrix, has an average dispersion area of 0.3 μm2 or less.

Description

[Technical Field]

[0001] The present invention relates to a thermoplastic polyester elastomer resin composition that can give molded articles having good appearance and extremely excellent abrasion resistance. [Background technology]

[0002] Conventionally, methods for improving the abrasion resistance of resin compositions have been known, such as adding long-chain organic acid compounds (e.g., organic acid esters, organic acid salts, and organic acid amides) or silicone oils as lubricants. However, particularly for soft compositions with a durometer type D hardness of 60 or less, a large amount of lubricant must be added to achieve sufficient abrasion resistance. However, adding a large amount of lubricant can result in poor dispersibility and incomplete compatibility with the resin, leading to the lubricant separating and accumulating near the surface over time, potentially causing problems such as bleeding and blooming. Furthermore, long-chain organic acid compounds are prone to deterioration at high temperatures, resulting in the problem of discoloration and foreign matter (e.g., burnt spots) occurring during melt molding.

[0003] On the other hand, a method of improving abrasion resistance by adding solid particles that do not melt even at high temperatures, such as silicone powder or Teflon (registered trademark) powder, is also known. However, since the solid particles act as fillers, they have a negative effect on moldability and surface properties, and in addition, they have poor adhesion to the resin component of the composition, which makes them prone to peeling at the interface, and if used in large quantities, they reduce the strength of the composition itself.

[0004] To address these challenges, copolymers have been developed that combine structural moieties that are compatible with resin components with structural moieties that improve wear resistance, and attempts have been made to apply them to various thermoplastic resins. However, while these copolymers offer the benefits of improved heat resistance and weather resistance, they often have the drawback of worsening melt flow and moldability. The reason for this is thought to be that graft copolymers and block copolymers, which combine different structures, act as pseudo-crosslinking points in thermoplastic resins.

[0005] Patent Document 1 discloses an invention relating to a thermoplastic elastomer composition containing a silicone-modified (meth)acrylic polymer and an epoxy-based thickener containing styrene, in combination with a thermoplastic polyester elastomer. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-79228 Summary of the Invention [Problem to be solved by the invention]

[0007] Patent Document 1 proposes blending a silicone-modified acrylic polymer to solve the above problems, but it was found that the appearance of molded articles made from the thermoplastic polyester elastomer composition was not fully satisfactory. An object of the present invention is to provide a thermoplastic polyester elastomer resin composition that can give molded articles having even better appearance and extremely excellent abrasion resistance, as well as a molded article made from the same. [Means for solving the problem]

[0008] In order to achieve the above object, the present inventors discovered that it is possible to achieve both good appearance and good abrasion resistance by blending a specific silicone-acrylic copolymer with a thermoplastic polyester elastomer, and thus completed the present invention.

[0009] That is, the present invention has the following features (1) and (2). (1) A thermoplastic polyester elastomer resin composition comprising a thermoplastic polyester elastomer (A) formed by bonding a hard segment made of a polyester having an aromatic dicarboxylic acid and an aliphatic and / or alicyclic diol as constituent components to at least one soft segment selected from aliphatic polyethers, aliphatic polyesters, and aliphatic polycarbonates, and a silicone-acrylic copolymer (B), wherein the silicone-acrylic copolymer (B) is a graft copolymer having a silicone main skeleton to which an acrylic polymer is bonded in the form of a side chain, and the polymerization ratio of silicone to acrylic polymer in the silicone-acrylic copolymer (B) is 60 / 40 to 75 / 25 by mass ratio. ,heat The weight loss rate of the silicone-acrylic copolymer (B) at 250°C is 3.3% or more and 4.0% or less, measured using a thermogravimetric analyzer (SII EXSTAR6000, TG6200 / DTA) installed in a test room at 23°C and 50% RH with a sample weight of 5 mg and a heating rate of 10°C / min from 23 to 250°C. and the content of the silicone-acrylic copolymer (B) in the resin composition is 1.5 to 15 parts by mass per 100 parts by mass of the thermoplastic polyester elastomer (A). A thermoplastic polyester elastomer resin composition characterized by: (2) A molded article obtained from a thermoplastic polyester elastomer resin composition containing a thermoplastic polyester elastomer (A) formed by bonding a hard segment made of a polyester having an aromatic dicarboxylic acid and an aliphatic and / or alicyclic diol as constituent components to at least one soft segment selected from aliphatic polyethers, aliphatic polyesters, and aliphatic polycarbonates, and a silicone-acrylic copolymer (B), wherein the silicone-acrylic copolymer (B) is a graft copolymer having a silicone main skeleton and an acrylic polymer bonded to the main skeleton in the form of a side chain, and the polymerization ratio of silicone to acrylic polymer in the silicone-acrylic copolymer (B) is 60 / 40 to 75 / 25 by mass ratio. ,heatThe weight loss rate of the silicone-acrylic copolymer (B) at 250°C is 3.3% or more and 4.0% or less, measured using a thermogravimetric analyzer (SII EXSTAR6000, TG6200 / DTA) installed in a test room at 23°C and 50% RH with a sample weight of 5 mg and a heating rate of 10°C / min from 23 to 250°C. and the content of the silicone-acrylic copolymer (B) in the resin composition is 1.5 to 15 parts by mass per 100 parts by mass of the thermoplastic polyester elastomer (A). A molded body characterized by: [Effects of the Invention]

[0010] The thermoplastic polyester elastomer resin composition of the present invention has good moldability, and molded articles obtained from the thermoplastic polyester elastomer resin composition have good appearance and are extremely excellent in abrasion resistance, and therefore can be suitably used in components that are subjected to repeated wear, such as automobile interior parts. DETAILED DESCRIPTION OF THE INVENTION

[0011] The thermoplastic polyester elastomer resin composition of the present invention will be described in detail below. The thermoplastic polyester elastomer resin composition of the present invention is a thermoplastic polyester elastomer resin composition comprising a thermoplastic polyester elastomer (A) and a silicone-acrylic copolymer (B), wherein in a molded article obtained by injection molding the thermoplastic polyester elastomer resin composition, the silicone-acrylic copolymer (B) dispersed in the thermoplastic polyester elastomer (A) forming a matrix has an average dispersion area of ​​0.3 μm 2 The following is the result.

[0012] The thermoplastic polyester elastomer (A) is formed by bonding a hard segment made of a polyester having an aromatic dicarboxylic acid and an aliphatic and / or alicyclic diol as constituent components to at least one soft segment selected from aliphatic polyethers, aliphatic polyesters, and aliphatic polycarbonates. The thermoplastic polyester elastomer (A) preferably comprises, as its main components, a hard segment made of a crystalline polyester composed of an aromatic dicarboxylic acid and an aliphatic or alicyclic diol, and at least one soft segment selected from the group consisting of aliphatic polyethers, aliphatic polyesters, and aliphatic polycarbonates, and the content of the soft segment component is preferably 95 to 5 mass%. The content of the soft segment component is more preferably 90 to 10 mass%, even more preferably 85 to 15 mass%, and particularly preferably 75 to 25 mass%. Furthermore, two or more types of thermoplastic polyester elastomer (A) with different soft segment component contents may be used in combination to adjust the soft segment content to the above range.

[0013] In the thermoplastic polyester elastomer (A), the aromatic dicarboxylic acid constituting the polyester hard segment is generally a typical aromatic dicarboxylic acid, and is not particularly limited. However, the primary aromatic dicarboxylic acid is preferably terephthalic acid or naphthalenedicarboxylic acid. Among the isomers of naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid is preferred. Other acid components include aromatic dicarboxylic acids such as diphenyldicarboxylic acid, isophthalic acid, and 5-sodium sulfoisophthalic acid; alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid and tetrahydrophthalic anhydride; and aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, dimer acid, and hydrogenated dimer acid. These acids are used in amounts that do not significantly lower the melting point of the resin, and the amount used is less than 35 mol %, preferably less than 30 mol %, of the total acid components.

[0014] In the thermoplastic polyester elastomer (A), the aliphatic or alicyclic diol constituting the polyester of the hard segment is generally a common aliphatic or alicyclic diol, and is not particularly limited, but is preferably an alkylene glycol having 2 to 8 carbon atoms. Specific examples include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, and 1,4-cyclohexanedimethanol. 1,4-butanediol and 1,4-cyclohexanedimethanol are most preferred.

[0015] As the component constituting the polyester of the hard segment, those composed of butylene terephthalate units (units consisting of terephthalic acid and 1,4-butanediol) or butylene naphthalate units (units consisting of 2,6-naphthalenedicarboxylic acid and 1,4-butanediol) are preferred in terms of physical properties, moldability, and cost performance.

[0016] The soft segment of the thermoplastic polyester elastomer (A) used in the present invention is at least one selected from aliphatic polyethers, aliphatic polyesters, and aliphatic polycarbonates.

[0017] Examples of aliphatic polyethers include poly(ethylene oxide) glycol, poly(propylene oxide) glycol, poly(tetramethylene oxide) glycol, poly(hexamethylene oxide) glycol, poly(trimethylene oxide) glycol, copolymers of ethylene oxide and propylene oxide, ethylene oxide adducts of poly(propylene oxide) glycol, copolymers of ethylene oxide and tetrahydrofuran, etc. Among these, poly(tetramethylene oxide) glycol and ethylene oxide adducts of poly(propylene oxide) glycol are preferred from the viewpoint of elastic properties.

[0018] Examples of aliphatic polyesters include poly(ε-caprolactone), polyenantholactone, polycaprylolactone, polybutylene adipate, etc. Among these, poly(ε-caprolactone) and polybutylene adipate are preferred from the viewpoint of elasticity.

[0019] The aliphatic polycarbonate is preferably composed primarily of aliphatic diol residues having 2 to 12 carbon atoms. Examples of these aliphatic diols include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 2,2-dimethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,9-nonanediol, and 2-methyl-1,8-octanediol. In particular, aliphatic diols having 5 to 12 carbon atoms are preferred in terms of the flexibility and low-temperature properties of the resulting thermoplastic polyester elastomer. These components may be used alone or in combination of two or more types as necessary, based on the examples described below.

[0020] The aliphatic polycarbonate diol having good low-temperature properties and constituting the soft segment of the thermoplastic polyester elastomer (A) used in the present invention preferably has a low melting point (for example, 70°C or less) and a low glass transition temperature. In general, the aliphatic polycarbonate diol made from 1,6-hexanediol used to form the soft segment of the thermoplastic polyester elastomer has a low glass transition temperature of about -60°C and a melting point of about 50°C, resulting in good low-temperature properties. In addition, an aliphatic polycarbonate diol obtained by copolymerizing an appropriate amount of, for example, 3-methyl-1,5-pentanediol with the above aliphatic polycarbonate diol has a slightly higher glass transition temperature than the original aliphatic polycarbonate diol, but has a lower melting point or is amorphous, and therefore corresponds to an aliphatic polycarbonate diol with good low-temperature properties. Furthermore, for example, an aliphatic polycarbonate diol made of 1,9-nonanediol and 2-methyl-1,8-octanediol has a melting point of about 30°C and a glass transition temperature of about -70°C, which are sufficiently low, and therefore corresponds to an aliphatic polycarbonate diol with good low-temperature properties.

[0021] From the viewpoint of solving the problems of the present invention, the soft segment of the thermoplastic polyester elastomer (A) used in the present invention is preferably an aliphatic polyether.

[0022] The thermoplastic polyester elastomer (A) used in the present invention is preferably a copolymer primarily composed of terephthalic acid, 1,4-butanediol, and poly(tetramethylene oxide) glycol. Among the dicarboxylic acid components constituting the thermoplastic polyester elastomer (A), terephthalic acid preferably accounts for 40 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and particularly preferably 90 mol% or more. Among the glycol components constituting the thermoplastic polyester elastomer (A), the sum of 1,4-butanediol and poly(tetramethylene oxide) glycol is preferably 40 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and particularly preferably 90 mol% or more.

[0023] The number average molecular weight of the poly(tetramethylene oxide) glycol is preferably 500 to 4000. If the number average molecular weight is less than 500, it may be difficult to exhibit elastomeric properties. On the other hand, if the number average molecular weight exceeds 4000, compatibility with the hard segment component may decrease, making it difficult to copolymerize in a block form. The number average molecular weight of the poly(tetramethylene oxide) glycol is more preferably 800 to 3000, and even more preferably 1000 to 2500.

[0024] The reduced viscosity of the thermoplastic polyester elastomer (A) is preferably from 0.5 to 3.5 dl / g, more preferably from 1.0 to 3.0 dl / g, from the viewpoint of maximizing the effects of the present invention.

[0025] The thermoplastic polyester elastomer (A) can be produced by a conventionally known method, for example, a method of transesterifying a lower alcohol diester of a dicarboxylic acid, an excess amount of a low-molecular-weight glycol, and a soft segment component in the presence of a catalyst, followed by polycondensation of the resulting reaction product, or a method of esterifying a dicarboxylic acid, an excess amount of a glycol, and a soft segment component in the presence of a catalyst, followed by polycondensation of the resulting reaction product.

[0026] The silicone-acrylic copolymer (B) has a structure containing at least one silicone (polysiloxane) moiety and at least one (meth)acrylic acid polymer moiety. Copolymers having such a structure are known, for example, (acrylates / ethylhexyl acrylate / dimethicone methacrylate) copolymer (trade name: KP578) manufactured by Shin-Etsu Silicone Co., Ltd., wax-type (acrylates / stearyl acrylate / dimethicone methacrylate) copolymer (trade name: KP561P), (acrylates / behenyl acrylate / dimethicone methacrylate) copolymer (KP562P), and Chaline manufactured by Nissin Chemical Industry Co., Ltd., and have a variety of structures and properties.

[0027] Among these, the silicone-acrylic copolymer (B) is preferably a graft copolymer having a main skeleton of silicone (polysiloxane) and a side chain of an acrylic polymer bonded to the main skeleton. With this structure, the acrylic polymer portion, which has excellent compatibility with the matrix resin, becomes a branched chain, improving entanglement with the resin, making it less likely to bleed out and resulting in excellent dispersibility during kneading. The acrylic polymer is a (co)polymer of (meth)acrylic acid ester and / or (meth)acrylic acid hydroxyalkyl ester. When producing the polysiloxane portion, the number of grafting starting points of the acrylic polymer can be adjusted by appropriately blending a silane monomer having an unsaturated group. In the silicone-acrylic copolymer (B), both the polysiloxane portion and the acrylic polymer portion may be linear or branched. The (meth)acrylic acid ester and the (meth)acrylic acid hydroxyalkyl ester may be used in combination, or either one may be used alone. The silicone-acrylic copolymer (B) may be partially modified, and may have a core-shell structure.

[0028] In the silicone-acrylic copolymer (B), a higher proportion of silicone (polysiloxane) moieties tends to improve the sliding properties of the composition, while a higher proportion of acrylic polymer tends to improve dispersibility in the composition. From these viewpoints, the polymerization ratio of the silicone to the acrylic polymer (silicone / acrylic polymer) is preferably 5 / 95 to 85 / 15, more preferably 30 / 70 to 80 / 20, and even more preferably 60 / 40 to 75 / 25, by mass.

[0029] When the silicone-acrylic copolymer (B) is solid at room temperature (23°C), it is preferably granular. The area-based average particle diameter of the particles is preferably 0.5 to 120 μm, more preferably 1 to 100 μm, even more preferably 5 to 80 μm, and even more preferably 20 to 50 μm. The particle shape can be directly observed using an electron microscope. At least 30 randomly selected particles are measured for their major and minor axes, normalized to an ellipse, and the cross-sectional area is calculated to calculate the area-based average particle diameter. When the silicone-acrylic copolymer (B) has such a particle shape, it is easy to handle as a pellet or powder raw material. Furthermore, when kneaded into the composition of the present invention, it disperses quickly in the composition due to its good dispersibility, imparting good sliding properties to the composition.

[0030] In a molded article obtained by injection molding the thermoplastic polyester elastomer resin composition of the present invention, the silicone-acrylic copolymer (B) dispersed in the thermoplastic polyester elastomer (A) forming the matrix has an average dispersion area of ​​0.3 μm 2 The means for satisfying the following will be described.

[0031] Injection molding is a molding method that produces large orientation in the shear orientation layer. Generally, domains (particles) are stretched during injection, and the domain size of the molded product tends to gradually decrease as it approaches the surface layer. However, if the difference in surface energy between the matrix (resin) and the domains (particles) is large, the domains (particles) are stretched during injection, but if the matrix is ​​a thermoplastic polyester elastomer with a slow solidification rate (low crystallization temperature, Tc2), the domains are likely to re-aggregate. Therefore, domains with long molecular chains and high surface energy (large energy difference with the resin) tend to return to their original size, failing to micro-disperse and resulting in poor appearance. Therefore, to improve compatibility with the resin (reducing the energy difference) and disentangle the core-shell structure of the particles during injection molding to micro-disperse them, a low molecular weight particle is desirable.

[0032] In other words, a small molecular weight of the silicone-acrylic copolymer (B) is preferable from the viewpoint of facilitating fine dispersion and improving abrasion resistance. If the molecular weight of the silicone-acrylic copolymer (B) is too large, the dispersion of the silicone-acrylic copolymer (B) becomes non-uniform, and particles with large particle sizes tend to remain. This reduces the proportion of silicone-acrylic copolymer (B) particles present on the surface of the molded article, and the effect of improving abrasion resistance itself tends to be difficult to achieve. Furthermore, an increase in particles with large particle sizes and an increase in the average dispersion area can cause poor appearance such as whitening in the molded article.

[0033] Examples of graft copolymers with a silicone (polysiloxane) main skeleton and acrylic polymers attached to the main skeleton as side chains include Chaline R-175S, Chaline R-170S, and Chaline R-170HS manufactured by Nissin Chemical Industry Co., Ltd. As explained above, even for graft copolymers with the same structure, the molecular weight is a very important measure, and the weight loss rate at 250°C measured by thermogravimetric analysis (TGA) is used as a measure of molecular weight.

[0034] Generally, in a polymer compound, as the molecular weight increases, the force attracting molecule to molecule becomes stronger, so deformation due to the influence of heat becomes less likely to occur, and thus the softening temperature and thermal decomposition temperature tend to increase. For the silicone-acrylic copolymer (B) used in the present application, since the softening point is around 100°C and the thermal decomposition temperature is around 250°C, it is possible to simply grasp the molecular weight difference from the weight loss rate at these temperatures. Table 1 shows the weight loss rate (%) at each temperature as a result of performing thermogravimetric analysis (TGA) on Charine R-175S, Charine R-170S, and Charine R-170HS. The measurement conditions of TGA are as described in the examples below.

[0035]

Table 1

[0036] The weight loss rate at 100°C is 0.9% for R-175S, 0.6% for R-170S, and 0.5% for R-170HS. The molecular weight of R-175S is the lowest, and as the order of molecular weight, it can be said that R-175S < R-170S < R-170HS. Also, the weight loss rate at 250°C is 3.5% for R-175S, 3.2% for R-170S, and 3.2% for R-170HS. The molecular weight of R-175S is the lowest, and as the order of molecular weight, it can be said that R-175S < R-170S ≒ R-170HS. This relationship between the weight loss rate and the molecular weight is also consistent with the manufacturer information (relationship of molecular weight: R-175S << R-170S < R-170HS) and the description in JP-A-2019-64281 (Charine R-175S average molecular weight 200,000 [paragraph 0090], Charine R-170 average molecular weight 400,000 [paragraph 0095]).

[0037] The silicone-acrylic copolymer (B) used in the present invention preferably has a weight loss rate of 3.3% or more at 250°C as measured by thermogravimetric analysis (TGA). The weight loss rate is more preferably 3.4% or more, and even more preferably 3.5% or more. The upper limit of the weight loss rate at 250°C is about 4.0%.

[0038] The content of the silicone-acrylic copolymer (B) is preferably 1 to 20 parts by mass, more preferably 1.5 to 15 parts by mass, and even more preferably 2 to 12 parts by mass, per 100 parts by mass of the thermoplastic polyester elastomer (A).

[0039] Other lubricants may be used in combination with the silicone-acrylic copolymer (B). The silicone-acrylic copolymer (B) is compatible with not only resin components but also lubricants such as organic silicone lubricants, thereby preventing problems such as bleeding and discoloration caused by other lubricants. However, if the amount of other lubricants is too large, the effect of the silicone-acrylic copolymer (B) will be reduced. Therefore, when other lubricants are used in combination, the amount used is preferably 90 parts by mass or less, more preferably 5 to 70 parts by mass, per 100 parts by mass of the silicone-acrylic copolymer (B). It is also a preferred embodiment that no other lubricants are used.

[0040] The thermoplastic polyester elastomer resin composition of the present invention can be blended with various additives depending on the purpose, as long as they do not impair the effects of the present invention. Examples of additives include known hindered phenol, sulfur, phosphorus, and amine antioxidants; hindered amine, triazole, benzophenone, benzoate, nickel, and salicylic acid light stabilizers; antistatic agents; lubricants (lubricants other than the silicone-acrylic copolymer (B)); molecular modifiers such as peroxides; compounds having reactive groups (compatibilizers) such as epoxy compounds, isocyanate compounds, and carbodiimide compounds; metal deactivators; organic and inorganic nucleating agents; neutralizing agents; antacids; antibacterial agents; fluorescent brighteners; fillers; flame retardants; flame retardant aids; and organic and inorganic pigments. The total amount of these additives can be up to 10 parts by weight per 100 parts by weight of the thermoplastic polyester elastomer (A). In particular, in order to uniformly disperse the silicone-acrylic copolymer (B) in the thermoplastic polyester elastomer (A) that forms the matrix, it is preferable to contain a compatibilizer, preferably in an amount of 0.5 to 3 parts by mass per 100 parts by mass of the thermoplastic polyester elastomer (A).

[0041] The thermoplastic polyester elastomer resin composition of the present invention can be produced by mixing the thermoplastic polyester elastomer (A), silicone-acrylic copolymer (B), and other components in a predetermined ratio, followed by melt-kneading. Mixing can be performed using a Henschel mixer, ribbon blender, V-type blender, or the like, and melt-kneading can be performed using a Banbury mixer, kneader-type heater, single-screw or twin-screw melt-kneading extruder, or the like.

[0042] The MFR (g / 10 min) of the thermoplastic polyester elastomer resin composition of the present invention is not particularly limited so that it can be applied to a wide range of molding methods.

[0043] In a molded article obtained by injection molding the thermoplastic polyester elastomer resin composition of the present invention, the silicone-acrylic copolymer (B) dispersed in the thermoplastic polyester elastomer (A) forming the matrix has an average dispersion area of ​​0.3 μm 2 The average dispersion area of ​​the silicone-acrylic copolymer (B) is measured by the method described in the Examples below. The average dispersion area of ​​the silicone-acrylic copolymer (B) is 0.25 μm 2 Preferably, it is 0.2 μm or less. 2 The lower limit of the average dispersion area of ​​the silicone-acrylic copolymer (B) is preferably 0.005 μm or less. 2 However, taking into account various manufacturing conditions, it is estimated that 2 It is preferable that this is equal to or greater than this.

[0044] The molding method for the thermoplastic polyester elastomer resin composition of the present invention is not limited, and various molding methods such as injection molding, blow molding, extrusion molding, foam molding, profile molding, calendar molding, and the like can be suitably used. Among these, injection molding is preferred.

[0045] A molded article obtained from the thermoplastic polyester elastomer resin composition described above, wherein the silicone-acrylic copolymer (B) dispersed in the thermoplastic polyester elastomer (A) forming the matrix in the molded article has an average dispersion area of ​​0.3 μm 2 The following molded article is also one aspect of the present invention.

[0046] The molded article of the thermoplastic polyester elastomer resin composition of the present invention is produced as described above, and therefore has a good appearance and good abrasion resistance. Therefore, the molded article of the present invention can be suitably used in components that are subjected to repeated wear, such as automobile interior parts. Furthermore, when the molded article has a grain, it exhibits even better abrasion resistance. [Example]

[0047] The present invention will be specifically explained below using examples and comparative examples, but the present invention is not limited to the following examples, and modifications can be made within the scope of the above-mentioned intent, and all of these modifications are included in the technical scope of the present invention. The evaluation methods are as follows.

[0048] 1) Average dispersion area and number of large particles of silicone-acrylic copolymer (B): Microscopic observation A 10mm x 10mm molded part with a thickness of 2mm was injection molded. A cross section of the sample was prepared using a cryomicrotome, starting near the center of the molded part, so that a plane perpendicular to the flow direction could be observed. Images were then taken using a Nikon ECLIPSE LV150N industrial microscope at a 100x objective lens. The image was taken at the center of the molded part's cross section, where the particle dispersion diameter was stable. The captured image was analyzed using a Nikon NIS-Elements BR, and the average area (average dispersion area) of the observed dispersed particles of silicone-acrylic copolymer (B) was calculated. Coarse particles, as described below, were excluded from the area calculation. Furthermore, an image was taken at the same location using a Nikon industrial microscope ECLIPSE LV150N with a 20x objective lens, and the image was enlarged to 131mm vertically and 185mm horizontally. The area of ​​the dispersed particles was visually determined to be 100μm 2 The number of large particles equivalent to the above was measured. The image analysis area was 0.29 mm 2 and is expressed as the number of particles contained in this area. The molded articles used for the measurements were molded using an injection molding machine (Toshiba Machine IS-80G-2AIS) with a cylinder temperature set to 250°C for Example 4 and 220°C for the others, and an injection speed of 30%. In addition, when the particles are finely dispersed and the average dispersion area cannot be calculated by the above detection method, the average dispersion area is calculated using a transmission electron microscope (TEM), which is a more accurate analytical method described below. Frozen sections were prepared from injection-molded molded articles measuring 10 mm x 10 mm and 2 mm thick using a cryomicrotome, from near the center of the article, so that a plane perpendicular to the flow direction could be observed. These sections were stained with an electron stain (ruthenium tetroxide, osmium tetroxide, or phosphotungstic acid), and then observed and photographed using a JEOL JEM2100 transmission electron microscope at an accelerating voltage of 200 kV. The photographs were taken at a magnification of 2,000–5,000x. The TEM images were binarized using ImageJ (free software developed by the National Institutes of Health) to determine the average area (average dispersed area) of the dispersed particles of the silicone-acrylic copolymer (B). The coarse particles were excluded from the area calculation.

[0049] 2) Wear resistance: Thrust wear test Under the same conditions as in 1) above, a SUS cylinder was placed on a 10mm x 10mm molded product with a thickness of 2mm, which had been injection molded, and a wear test was carried out under a load of 0.37MPa, a sliding speed of 65rpm, and a test time of 10 minutes. The mass was compared before and after the test, and the loss in mass was taken as the amount of wear. If the amount of wear was less than 0.3g, it was evaluated as ◯; if it was 0.3g or more but less than 0.35g, it was evaluated as △; if it was 0.35g or more, it was evaluated as ×.

[0050] 3) Whitening of appearance: Visual evaluation Under the same conditions as in 1) above, 10mm x 10mm molded products with a thickness of 2mm were injection molded and visually inspected to evaluate whether the proportion of the area where whitening was observed was less than 25% as ◯, 25% or more but less than 50% as △, or 50% or more as ×.

[0051] The raw materials used in the examples and comparative examples are as follows. [Thermoplastic polyester elastomer (A)] A-1: Thermoplastic polyester elastomer (A-1) was produced according to the method described in JP-A-9-59491, with a molar ratio of terephthalic acid / 1,4-butanediol / polyoxytetramethylene glycol (PTMG: number average molecular weight 2000) of 100 / 78.8 / 21.2. The soft segment (PTMG) content was 68% by mass, and the reduced viscosity was 1.9 dl / g.

[0052] A-2: Thermoplastic polyester elastomer (A-2) was produced according to the method described in JP-A-9-59491, with a molar ratio of 2,6-naphthalenedicarboxylic acid / 1,4-butanediol / polyoxytetramethylene glycol (PTMG: number average molecular weight 1000) of 100 / 87.8 / 12.2. The soft segment (PTMG) content was 32% by mass, and the reduced viscosity was 1.3 dL / g.

[0053] The reduced viscosity was measured at 30°C using an Ubbelohse viscometer after dissolving 0.02 g of the thermoplastic polyester elastomer in 10 ml of a mixed solvent of phenol / tetrachloroethane (mass ratio 6 / 4).

[0054] [Silicone-acrylic copolymer (B)] B-1: Chaline R-175S, silicone / acrylic polymer = 70 / 30 (mass ratio), area-based average particle size 30 μm, weight loss rate at 250 ° C 3.5% B-2: Chaline R-170S, silicone / acrylic polymer = 70 / 30 (mass ratio), area-based average particle size 30 μm, weight loss rate at 250 ° C 3.2% B-3: Chaline R-170HS, silicone / acrylic polymer = 70 / 30 (mass ratio), area-based average particle size 30 μm, weight loss rate at 250 ° C 3.2% B-4: Silicone-modified (meth)acrylic polymer A (acrylic polymer having polyalkylsiloxane in the side chain) described in JP 2016-79228 A was prepared. The silicone / acrylic polymer ratio was 70 / 30 (mass ratio), and the area-based average particle size was 50 μm.

[0055] Thermogravimetric analysis (TGA) The weight loss rate at 250°C was measured using a thermogravimetric analyzer (SII EXSTAR6000, TG6200 / DTA) with a sample weight of 5 mg at a heating rate of 10°C / min from 23 to 550°C. The apparatus was placed in a test room at 23°C and 50% RH.

[0056] [Other additives] UV absorber: CHISORB 234 (BASF) HALS (hindered amine light stabilizer): CHIMASORB 944 (manufactured by BASF) Hindered phenolic antioxidant: SONGNOX 245 (manufactured by SONGWON) Phosphorus-based antioxidant: HOSTANOX P-EPQ (Clariant) Compatibilizer: BF-7M, ethylene / glycidyl methacrylate / methyl acrylate copolymer (Sumitomo Chemical Co., Ltd.)

[0057] Examples 1 to 5, Comparative Examples 1 to 4 The thermoplastic polyester elastomer (A) and silicone-acrylic copolymer (B) were dry-blended according to the formulation shown in Table 2, and the mixture was melt-kneaded and extruded into strands using a 35mm diameter twin-screw extruder (manufactured by Toshiba Machine Co., Ltd.) at a temperature setting of 200 to 220°C (240 to 250°C in Example 4). The extruded strands were then water-cooled and pelletized using a pelletizer. The resulting pellets were dried under reduced pressure at 100°C for 5 hours to obtain a thermoplastic polyester elastomer resin composition. The evaluation results are shown in Table 2.

[0058] [Table 2]

[0059] As is clear from the results in Table 2, the thermoplastic polyester elastomer resin compositions of Examples 1 to 5 have excellent appearance and good abrasion resistance. In Comparative Examples 1 to 4, the dispersion state of the silicone-acrylic copolymer (B) is inappropriate, so that the results are inferior to those of the Examples in terms of any of the properties. [Industrial Applicability]

[0060] The thermoplastic polyester elastomer resin composition of the present invention has excellent appearance and abrasion resistance, and therefore can be suitably used as an automobile interior member that is subjected to repeated abrasion.

Claims

1. The thermoplastic polyester elastomer resin composition contains a thermoplastic polyester elastomer (A) in which a hard segment made of a polyester having an aromatic dicarboxylic acid and an aliphatic and / or alicyclic diol as constituent components is bonded to at least one soft segment selected from aliphatic polyethers, aliphatic polyesters, and aliphatic polycarbonates, and a silicone-acrylic copolymer (B), wherein the silicone-acrylic copolymer (B) is a graft copolymer having a silicone main skeleton and an acrylic polymer bonded to the main skeleton in the form of a side chain, and the polymerization ratio of the silicone to the acrylic polymer in the silicone-acrylic copolymer (B) is 60 / 40 to 75 / 25 by mass ratio, and the thermogravimetric analysis (TGA) is carried out using a thermogravimetric analyzer (SII) installed in a test room at 23°C and 50% RH. A thermoplastic polyester elastomer resin composition characterized in that the weight loss rate of the silicone-acrylic copolymer (B) at 250°C is 3.3% or more and 4.0% or less, as measured using a thermoplastic elastomer (EXSTAR6000, TG6200 / DTA) with a sample weight of 5 mg at a temperature rise rate of 10°C / min from 23 to 250°C, and the content of the silicone-acrylic copolymer (B) in the resin composition is 1.5 to 15 parts by mass per 100 parts by mass of the thermoplastic polyester elastomer (A).

2. A molded article obtained from a thermoplastic polyester elastomer resin composition containing a thermoplastic polyester elastomer (A) in which a hard segment made of a polyester having an aromatic dicarboxylic acid and an aliphatic and / or alicyclic diol as constituent components is bonded to at least one soft segment selected from aliphatic polyethers, aliphatic polyesters, and aliphatic polycarbonates, and a silicone-acrylic copolymer (B), wherein the silicone-acrylic copolymer (B) is a graft copolymer having a silicone main skeleton and an acrylic polymer bonded to the main skeleton in the form of a side chain, and the polymerization ratio of the silicone to the acrylic polymer in the silicone-acrylic copolymer (B) is 60 / 40 to 75 / 25 by mass ratio, and the molded article is obtained from a thermogravimetric analysis (TGA) using a thermogravimetric analyzer (SII) installed in a test room at 23°C and 50% RH. The molded article is characterized in that the weight loss rate of the silicone-acrylic copolymer (B) at 250°C is 3.3% or more and 4.0% or less, as measured using a thermoplastic elastomer (EXSTAR6000, TG6200 / DTA) with a sample weight of 5 mg at a temperature rise rate of 10°C / min from 23 to 250°C, and the content of the silicone-acrylic copolymer (B) in the resin composition is 1.5 to 15 parts by mass per 100 parts by mass of the thermoplastic polyester elastomer (A).

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