JP7652076B2 - Polyester elastomer resin composition - Google Patents

Description

The present invention relates to a polyester elastomer resin composition. More specifically, the present invention relates to a resin composition that can provide a good appearance with few irregularities when molten resin (parison) is injected at high speed from an accumulator in a blow molding process, and that has excellent thermal stability when retained in a cylinder.

Generally, polyester elastomers produced by the melt polycondensation method have a relatively low melt viscosity, so the melt tension of the parison extruded from the molding machine is insufficient, and the parison cannot withstand the drawdown of the parison itself or the air pressure when blow molding a hollow container, resulting in the problem that blow moldability cannot be ensured.

For this reason, a crosslinking agent such as an epoxy compound and a reaction catalyst such as an imidazole catalyst (tertiary amine) are blended with the polymer produced by the melt polycondensation method to increase the melt viscosity of the polyester elastomer to a level suitable for blow molding (Patent Document 1).

In addition, by blending crosslinking agents such as epoxy compounds and isocyanate compounds, polyester elastomers can be modified to have a melt viscosity high enough for blow molding and to have improved impact resistance (Patent Document 2).

In addition to reactive compounds, it is also known that the addition of a small amount of sodium type ionomer generates an interaction due to ionic crosslinking at the interface between the polyester elastomer matrix and the ionomer, thereby significantly improving the melt viscosity (Patent Document 3).

Furthermore, by blending a sodium type ionomer with a polyolefin resin having an epoxy group, the melt viscosity can be further improved significantly (Patent Document 4).

However, with the method described in Patent Document 1, although a melt viscosity suitable for blow molding is achieved, the reactivity between the carboxylic acid end of the polyester elastomer and the epoxy compound is insufficient, and a reaction occurs when the material remains in the molding machine, resulting in variations in melt viscosity and uneven thickness of the molded product.

In addition, in the method described in Patent Document 2, the melt viscosity is insufficient for application to blow molding, and the drawdown and extensibility of the parison tend to decrease, so sufficient modification effects are not observed. Therefore, it is easy to predict that the range of conditions for blow molding is narrow, and the thickness deviation of the obtained hollow molded product will be significant.

Although the method described in Patent Document 3 can increase the melt viscosity to a level suitable for blow molding without requiring a reactive compound, the dispersibility of the ionomer changes during heat retention, and the sodium ions contained in the ionomer exhibit nucleophilicity toward the molecular chains of the polyester elastomer, causing decomposition and making the melt viscosity unstable.

In a method such as that described in Patent Document 4, although the melt viscosity is stable during thermal retention, when the parison is ejected from the accumulator at high speed, the melt viscosity is too high in the high shear rate region, resulting in an uneven pattern caused by melt fracture on the surface of the parison, making it impossible to obtain a good appearance.

Japanese Patent Application Publication No. 11-323110 Japanese Patent Application Publication No. 5-302022 JP 2008-201866 A Patent No. 4114118

The object of the present invention is to provide a polyester elastomer resin composition that can provide a good appearance with minimal unevenness due to melt fracture when a parison is injected from an accumulator at high speed in a blow molding process, and that has excellent thermal stability when retained in a cylinder.

In order to achieve the above object, the inventors conducted extensive research and discovered that by selecting and blending optimal components of a bifunctional or higher epoxy compound, an epoxy group-containing polyolefin resin, and an unmodified olefin elastomer, it is possible to obtain a polyester elastomer resin composition with excellent blow moldability, leading to the proposal of the present invention. That is, the present invention is as follows.

[1] A polyester elastomer resin composition comprising 100 parts by mass of a thermoplastic polyester elastomer (A), 0.1 to 5 parts by mass of a bifunctional or higher epoxy compound (B) having an epoxy value exceeding 0.5 meq/g, 0.1 to 5 parts by mass of an epoxy group-containing polyolefin resin (C) having an epoxy value of 0.01 to 0.5 meq/g, and 0.1 to 15 parts by mass of an unmodified olefin elastomer (D), and having a melt viscosity measured in accordance with JIS K7199 of 6,800 Pa s or more at 230°C and 160 Pa s or less at a shear rate of 6.08 sec ^{- 1} .
[2] The polyester elastomer resin composition according to [1], wherein the hard segment of the thermoplastic polyester elastomer (A) is polybutylene terephthalate and the soft segment is an ethylene oxide addition polymer of poly(tetramethylene oxide) glycol and/or poly(propylene oxide) glycol.
[3] The polyester elastomer resin composition according to [1] or [2], wherein the number average molecular weight of the soft segment constituting the thermoplastic polyester elastomer (A) is 500 to 4,000, and the copolymerization amount is 3 to 50 mol% based on the total glycol component.
[4] The polyester elastomer resin composition according to any one of [1] to [3], wherein the unmodified olefin-based elastomer (D) is at least one selected from the group consisting of a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms, a copolymer of ethylene and styrene, and a copolymer of ethylene and an unsaturated compound other than an α-olefin.
[5] The polyester elastomer resin composition according to any one of [1] to [4], wherein the unmodified olefin-based elastomer (D) has a melt flow rate of 0.1 to 15 g/10 min at 190° C. under a load of 2.16 kg.
[6] The polyester elastomer resin composition according to any one of [1] to [5], wherein the thermoplastic polyester elastomer (A) is copolymerized with an aromatic tricarboxylic acid in an amount of 0.01 to 3 mol % based on the total acid components.

The polyester elastomer resin composition of the present invention reduces the melt viscosity in the high shear rate region when the parison is injected at high speed in a blow molding process, thereby suppressing the disruption of resin flow caused by friction between the parison surface and the cylinder wall surface due to melt fracture, and making it possible to obtain a blow molded product with improved surface smoothness.The resin composition also has excellent thermal stability during molten retention, and does not cause drawdown of the parison or a significant increase in viscosity.

[Thermoplastic polyester elastomer (A)]
The thermoplastic polyester elastomer (A) is composed of a hard segment and a soft segment. In general, the main components are a hard segment composed of a polyester composed of an aromatic dicarboxylic acid and an aliphatic or alicyclic diol, and at least one soft segment selected from an aliphatic polyether, an aliphatic polyester, and an aliphatic polycarbonate. In the present invention, the soft segment is preferably an aliphatic polyether. As the hard segment, the polyester composed of an aromatic dicarboxylic acid and an aliphatic or alicyclic diol is preferably 70% by mass or more, more preferably 80% by mass or more. As the soft segment, the aliphatic polyether is preferably 70% by mass or more, more preferably 80% by mass or more.

In the thermoplastic polyester elastomer (A) used in the present invention, the aromatic dicarboxylic acid constituting the polyester of the hard segment is generally a normal aromatic dicarboxylic acid, and is not particularly limited, but it is desirable that the main aromatic dicarboxylic acid is terephthalic acid or 2,6-naphthalenedicarboxylic acid. Terephthalic acid or 2,6-naphthalenedicarboxylic acid is preferably 70 mol% or more of the total acid components, more preferably 80 mol% or more. Other acid components include aromatic dicarboxylic acids such as diphenyldicarboxylic acid, isophthalic acid, trimellitic acid, trimesic acid, pyromellitic 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. The other acid components are used in an amount that does not significantly lower the melting point of the thermoplastic polyester elastomer, and the amount thereof is preferably 30 mol % or less, more preferably 20 mol % or less, of the total acid components.

The thermoplastic polyester elastomer (A) used in the present invention may contain an aromatic tricarboxylic acid as an acid component in addition to an aromatic dicarboxylic acid. By using an aromatic tricarboxylic acid, the number of branching points in the molecular structure of the polyester elastomer increases, which lengthens the relaxation time of the molecular chains when left standing due to entanglement, and the melt viscosity is significantly improved in the low shear rate region. In that case, the relaxation time under flow is not significantly affected in the high shear rate region, so the melt viscosity can be maintained low.

The aromatic tricarboxylic acid used in the present invention is not particularly limited, but among them, trimellitic acid, trimesic acid, and hemimellitic acid, which can be purchased inexpensively on the market, are preferred. The copolymerization amount is preferably 0.01 to 3 mol% when the total acid components constituting the thermoplastic polyester elastomer (A) are taken as 100 mol%, more preferably 0.05 to 1 mol%, and even more preferably 0.08 to 0.5 mol%. If it is less than 0.01 mol%, the expected effect cannot be obtained, and if it exceeds 3 mol%, gelation occurs, and in batch polymerization, machine cleaning is required, and the yield during polymerization and continuous productivity decrease.

In the thermoplastic polyester elastomer (A) of the present invention, the aliphatic or alicyclic diol constituting the polyester of the hard segment is generally 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.

As the components constituting the polyester of the hard segment, those consisting 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. Those consisting of butylene terephthalate units are particularly preferred.

In addition, aromatic polyesters suitable as polyesters constituting the hard segments in the thermoplastic polyester elastomer (A) of the present invention can be easily obtained according to ordinary polyester manufacturing methods. In addition, when using this polyester as a raw material for the thermoplastic polyester elastomer, it is desirable for such polyesters to have a number average molecular weight of 10,000 to 40,000.

The aliphatic polyethers that are the soft segment components in the thermoplastic polyester elastomer (A) used in the present invention include poly(ethylene oxide) glycol, poly(propylene oxide) glycol, poly(tetramethylene oxide) glycol, poly(hexamethylene oxide) glycol, copolymers of ethylene oxide and propylene oxide, ethylene oxide addition polymers of poly(propylene oxide) glycol, copolymers of ethylene oxide and tetrahydrofuran, and other poly(alkylene oxide) glycols. Among the poly(alkylene oxide) glycols, it is particularly preferable to use those that have a side chain, a hydrocarbon structure with 3 or more carbon atoms, and have steric hindrance, such as propylene oxide.

The reason why sterically hindered poly(alkylene oxide) glycols with hydrocarbon structures in the side chains are preferred is not clear, but it is thought that when the molecular chains become entangled, fine entanglements occur, lengthening the relaxation time, or that intermolecular interactions occur, dramatically improving the melt viscosity in the low shear rate region.

Among the above aliphatic polyethers, poly(tetramethylene oxide) glycol, ethylene oxide addition polymers of poly(propylene oxide) glycol, and copolymer glycols of ethylene oxide and tetrahydrofuran are preferred, and poly(tetramethylene oxide) glycol and ethylene oxide addition polymers of poly(propylene oxide) glycol are more preferred. The number average molecular weight of these soft segments in the copolymerized state is preferably about 500 to 4,000.

If the number average molecular weight of the soft segment is less than 500, it may be difficult to develop elastomeric properties. On the other hand, if the number average molecular weight exceeds 4000, the compatibility with the polyester portion of the hard segment may decrease, making it difficult to copolymerize in blocks. The number average molecular weight of the soft segment is more preferably 800 to 3500, and even more preferably 1000 to 3500.

In the thermoplastic polyester elastomer (A), the copolymerization amount of the soft segment is preferably 3 to 50 mol % relative to the total glycol component (the sum of the aliphatic or alicyclic diol constituting the hard segment and the aliphatic polyether of the soft segment), more preferably 3 to 30 mol %, even more preferably 3 to 20 mol %, and particularly preferably 3 to 15 mol %.

In the thermoplastic polyester elastomer (A) used in the present invention, the mass ratio of hard segments to soft segments (hard segments:soft segments) is generally preferably in the range of 30:70 to 95:5, more preferably 40:60 to 90:10, even more preferably 45:55 to 87:13, and particularly preferably 50:50 to 85:15.

The melting point of the thermoplastic polyester elastomer (A) is preferably 150 to 230°C, and more preferably 175 to 225°C. If the melting point of the thermoplastic polyester elastomer (A) is less than 150°C, the amount of soft segments is large and heat resistance is likely to decrease, and if it exceeds 230°C, the amount of hard segments is large and flexibility is likely to decrease.

The thermoplastic polyester elastomer (A) used in the present invention can be produced by known methods (e.g., JP-A-10-182954, WO 2007/072748, etc.). For example, any of the following methods may be used: a method of transesterifying a lower alcohol diester of a dicarboxylic acid, an excess of a low molecular weight glycol, and a soft segment component in the presence of a catalyst, and polycondensing the resulting reaction product; a method of esterifying a dicarboxylic acid, an excess of a glycol, and a soft segment component in the presence of a catalyst, and polycondensing the resulting reaction product; a method of randomizing a hard segment by transesterification by adding a soft segment component to the hard segment; a method of connecting the hard segment and the soft segment with a chain linking agent; and, when poly(ε-caprolactone) is used for the soft segment, a method of adding an ε-caprolactone monomer to the hard segment.

[Epoxy compound (B)]
The epoxy compound (B) used in the present invention is a bifunctional or higher epoxy compound having an epoxy value of more than 0.5 meq/g. In other words, it is a compound having two or more epoxy groups, and is preferably one having good compatibility with the thermoplastic polyester elastomer (A). In order to react with the end group of the thermoplastic polyester elastomer (A) and thicken the resin composition to an extent that the blow moldability is satisfactory, the epoxy compound (B) needs to have an epoxy value of more than 0.5 meq/g and contain two or more epoxy groups. The weight average molecular weight (Mw) of the epoxy compound (B) is preferably 100 or more, and the epoxy value is preferably 1.0 meq/g or more. The weight average molecular weight (Mw) of the epoxy compound (B) is more preferably 200 to 10,000, and even more preferably 200 to 1,000. The epoxy value of the epoxy compound (B) is more preferably 5.0 to 20 meq/g.
When a commercially available epoxy compound (B) is used, the weight average molecular weight (Mw) is the value measured by the manufacturer. When the epoxy compound (B) is a single compound, the weight average molecular weight is considered to be the molecular weight of that compound.
When a commercially available epoxy compound (B) is used, the epoxy value is the value measured by the manufacturer. When the epoxy compound (B) is a single compound, the epoxy value can be calculated from its structure.

Specific examples of epoxy compounds (B) having two or more functionalities include 1,6-dihydroxynaphthalene diglycidyl ether, 1,3-bis(oxiranylmethoxy)benzene, 1,3,5-tris(2,3-epoxypropyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione and diglycerol triglycidyl ether having three epoxy groups, and 1-chloro-2,3-epoxypropane-formaldehyde-2,7-naphthalene diol polycondensate and pentaerythritol polyglycidyl ether having four epoxy groups. Among these, polyfunctional epoxy compounds having heat resistance in the skeleton are preferred. In particular, bifunctional or tetrafunctional epoxy compounds having a naphthalene structure as the skeleton, or trifunctional epoxy compounds such as tris(2,3-epoxypropyl)isocyanurate having a triazine structure as the skeleton are preferred. Considering the degree of increase in the solution viscosity of the thermoplastic polyester elastomer (A), the effect of efficiently reducing the acid value of the thermoplastic polyester elastomer (A), and the degree of gelation caused by aggregation and solidification of the epoxy itself, a difunctional or trifunctional epoxy compound is preferred.

As the difunctional or higher epoxy compound (B), a polymer containing a glycidyl group can also be used. For example, a glycidyl group-containing styrene-based polymer can be mentioned.

The blending ratio (content ratio) of the thermoplastic polyester elastomer (A) and the epoxy compound (B) in the resin composition of the present invention is (A)/(B) = 100/0.1 to 5 by mass. If the epoxy compound (B) is more than 5 parts by mass, it may cause gelation due to reaction with the thermoplastic polyester elastomer. Furthermore, if the epoxy compound (B) is less than 0.1 parts by mass, the thickening effect is reduced, which is not preferable. The mass ratio (A)/(B) is preferably 100/0.1 to 3, and more preferably 100/0.2 to 2. In the present invention, the blending amount (blending ratio) of each component is the content (content ratio) in the polyester elastomer resin composition.

When the difunctional or higher functional epoxy compound (B) is a single compound having a molecular weight of 200 to 1000, its mass ratio is preferably 0.1 to 0.33 parts by mass, and more preferably 0.2 to 0.32 parts by mass, per 100 parts by mass of the thermoplastic polyester elastomer (A).

[Epoxy group-containing polyolefin resin (C)]
The epoxy group-containing polyolefin resin (C) used in the present invention is a polyolefin resin modified with an epoxy group, and has an epoxy value of 0.01 to 0.5 meq/g. The epoxy group-containing polyolefin resin (C), like the epoxy compound (B), reacts with the end group of the thermoplastic polyester elastomer (A) to thicken the resin composition to an extent that the blow moldability is satisfactory, and also plays the role of a compatibilizer that makes the thermoplastic polyester elastomer (A) and the unmodified olefin elastomer (D) compatible. In addition, the epoxy group-containing polyolefin resin (C) contributes to stabilizing the melt viscosity of the resin composition during melt retention due to its moderate epoxy value. The epoxy value of the epoxy group-containing polyolefin resin (C) is preferably 0.05 to 0.45 meq/g, more preferably 0.1 to 0.3 meq/g. If the epoxy value is less than 0.01 meq/g, the compatibility with the thermoplastic polyester elastomer (A) decreases, causing pulsation in the strand state before cutting.If the epoxy value exceeds 0.5 meq/g, the melt viscosity increases during heat retention, and the crosslinking points themselves gradually become coarse, causing gelation.

As the epoxy group-containing polyolefin copolymer (C), a ternary copolymer consisting of an α-olefin, an unsaturated compound other than an α-olefin, and a glycidyl ester of an α,β-unsaturated acid is preferred. Examples of α-olefins include ethylene, propylene, 1-butene, etc., with ethylene being the most preferred. Examples of unsaturated compounds other than α-olefins include vinyl ethers, vinyl acetate, vinyl propionate, and other vinyl esters, acrylic acid and methacrylic acid methyl, ethyl, propyl, butyl, and other esters, acrylonitrile, and styrene, with butyl acrylate, methyl acrylate, and methyl methacrylate being the most preferred. Examples of glycidyl esters of α,β-unsaturated acids include acrylic acid glycidyl ester, methacrylic acid glycidyl ester, and ethacrylic acid glycidyl ester, with methacrylic acid glycidyl ester being the most preferred.

The amount of epoxy group-containing polyolefin resin (C) blended (content) is 0.1 to 5 parts by mass, preferably 0.3 to 4 parts by mass, more preferably 0.5 to 3 parts by mass, and even more preferably 0.8 to 2.5 parts by mass, per 100 parts by weight of thermoplastic polyester elastomer (A). If the blended amount is less than 0.1 part by mass, it will not be effective as a compatibilizer, and if it exceeds 5 parts by mass, the acid terminals of the thermoplastic polyester elastomer (A) will react with the epoxy groups during retention, causing gelation.

[Unmodified olefin-based elastomer (D)]
The unmodified olefin elastomer (D) (hereinafter, sometimes referred to as olefin elastomer (D)) is an olefin elastomer having no reactive groups such as epoxy groups, carbodiimide groups, oxazoline groups, and carboxyl groups. The olefin elastomer is preferably at least one selected from a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms, a copolymer of ethylene and styrene, and a copolymer of ethylene and an unsaturated compound other than an α-olefin. The present inventors have found, through extensive research, a mechanism in which, by blending an unmodified olefin elastomer (D), the melt viscosity is improved under static conditions such as in a low shear rate range, even in the absence of molecular chain extension, due to tension at the interface between the matrix thermoplastic polyester elastomer (A) and the olefin elastomer (D), and further, the melt viscosity is reduced under flow conditions such as in a high shear rate range.

The copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms used in the present invention is a copolymer having as its constituents ethylene and at least one α-olefin having 3 to 20 carbon atoms. Specific examples of α-olefins having 3 to 20 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, and 3-methyl-1-butene. , 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 9-methyl-1-decene, 11-methyl-1-dodecene, 12-ethyl-1-tetradecene, and combinations thereof. Among these α-olefins, copolymers using α-olefins having 3 to 12 carbon atoms are preferred.

The copolymer of ethylene and styrene used in the present invention is not particularly limited, but hydrogenated one is preferable. For example, hydrogenated styrene-conjugated diene block copolymer can be mentioned. Styrene-conjugated diene block copolymer is a block copolymer consisting of a styrene block and a diene block, and includes diblock copolymer, triblock copolymer, radial block copolymer, etc. In addition, diene block components include butadiene block and isoprene block. Specific examples of hydrogenated styrene-diene block copolymer include styrene-ethylene-butylene-styrene block copolymer (SEBS), which is a hydrogenated product of styrene-butadiene-styrene block copolymer (SBS), styrene-ethylene-propylene-styrene block copolymer (SEPS), which is a hydrogenated product of styrene-isoprene-styrene block copolymer (SIS), and styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS), which is a hydrogenated product of styrene-butadiene/isoprene-styrene block copolymer (SBIS). As explained above, the copolymer of ethylene and styrene does not necessarily need to use ethylene as a raw material monomer, and it is sufficient that the copolymer obtained is equivalent to a copolymer obtained using ethylene as a raw material.

The copolymer of ethylene and an unsaturated compound other than an α-olefin used in the present invention is not particularly limited, but examples of unsaturated compounds other than an α-olefin include vinyl ethers, vinyl esters such as vinyl acetate and vinyl propionate, methyl, ethyl, propyl, butyl and other esters of acrylic acid and methacrylic acid, acrylonitrile and styrene, among which butyl acrylate, methyl acrylate, and methyl methacrylate are preferred.

The olefin-based elastomer (D) used in the present invention preferably has a melt flow rate in the range of 0.1 to 15 g/10 min at 190°C under a load of 2.16 kg. More preferably, it is 2 to 10 g/min. If the melt flow rate exceeds 15 g/min, the compatibility with the thermoplastic polyester elastomer (A) of the matrix decreases, and the strands begin to pulsate.

The blending (content) amount of the unmodified olefin-based elastomer (D) is 0.1 to 15 parts by mass, preferably 1 to 12 parts by mass, more preferably 2 to 10 parts by mass, and further preferably 3 to 9 parts by mass, based on 100 parts by weight of the thermoplastic polyester elastomer (A). If the blending amount is less than 0.1 part by mass, the melt viscosity of the polyester elastomer resin composition at a shear rate of 6.08 sec ^-1 is not improved, and if it exceeds 15 parts by mass, the unmodified olefin-based elastomer (D) is not compatible and separates from the thermoplastic polyester elastomer (A), resulting in poor appearance and unstable behavior of the melt viscosity during retention.

Furthermore, the polyester elastomer resin composition of the present invention can be blended with various additives according to the purpose, within a range that does not impair the effects of the present invention. As additives, known phenol-based, sulfur-based, phosphorus-based, hindered amine-based, triazole-based, benzophenone-based, benzoate-based, nickel-based, salicylic light stabilizers, antistatic agents, lubricants, molecular regulators such as peroxides, metal deactivators, organic and inorganic nucleating agents, neutralizing agents, antacids, antibacterial agents, fluorescent brighteners, fillers, flame retardants, flame retardant assistants, organic and inorganic pigments, etc. can be added. The polyester elastomer resin composition of the present invention preferably comprises 80% by mass or more of the thermoplastic polyester elastomer (A), the bifunctional or higher epoxy compound (B), the epoxy group-containing polyolefin resin (C), and the unmodified olefin elastomer (D) in total, more preferably 90% by mass or more, and even more preferably 95% by mass or more.

The polyester elastomer resin composition of the present invention has the above-mentioned configuration, and in the melt viscosity measured in accordance with JIS K7199, the melt viscosity at 230°C at a shear rate of 6.08 sec ^-1 is 6800 Pa·s or more, and the melt viscosity at a shear rate of 6080 sec ^-1 is 160 Pa·s or less. The melt viscosity at a shear rate of 6.08 sec ^-1 is preferably 7000 Pa·s or more, and more preferably 7200 Pa·s or more. The melt viscosity at a shear rate of 6080 sec ^-1 is preferably 158 Pa·s or less, and more preferably 156 Pa·s or less. The upper limit of the melt viscosity at a shear rate of 6.08 sec ^-1 is not particularly limited, but is preferably 9000 Pa·s or less. The lower limit of the melt viscosity at a shear rate of 6080 sec ⁻¹ is not particularly limited, but is preferably 100 Pa·s or more.

The polyester elastomer resin composition of the present invention preferably has a melt flow rate of ±1.0 g/10 min after 6 minutes of residence at 240°C under a load of 5.0 kg and a melt flow rate of ±1.0 g/10 min after 26 minutes of residence at 240°C under a load of 5.0 kg. The polyester elastomer resin composition preferably has a melt flow rate of 2.0 to 5.5 g/10 min after 6 minutes of residence at 240°C under a load of 5.0 kg, and more preferably has a melt flow rate of 2.5 to 5.0 g/10 min.

The polyester elastomer resin composition of the present invention is preferably such that the surface hardness of an injection molded or blow molded article made from it is within the range of Shore D hardness 40 to 65. The surface hardness is more preferably 45 to 60 Shore D hardness.

The polyester elastomer resin composition of the present invention can be produced by melt-kneading the composition using a conventional thermoplastic resin mixer, such as a single-screw or twin-screw melt-kneader or a kneader heater, followed by pelletizing the composition through a granulation process.

The following examples are provided to further explain the present invention, but the present invention is not limited to these examples. The measurements described in the examples were measured by the following methods.

Melting Point:
Using a differential scanning calorimeter "DSC220" manufactured by Seiko Electronics Co., Ltd., 5 mg of the measurement sample was placed in an aluminum pan, the lid was pressed down to seal, and the sample was held at 250°C for 5 minutes to completely melt the sample, then quenched with liquid nitrogen, and then measured at a heating rate of 20°C/min from -150°C to 250°C. The endothermic peak of the obtained thermogram curve was taken as the melting point.

Reduced Viscosity:
0.10 g of the thoroughly dried resin was dissolved in 25 ml of a mixed solvent of phenol/tetrachloroethane (mass ratio 6/4), and the viscosity was measured at 30° C. using an Ubbelohse viscometer.

Acid Number:
0.2 g of the sample was precisely weighed, dissolved in 20 ml of chloroform, and titrated with 0.01 N potassium hydroxide (ethanol solution). Phenolphthalein was used as the indicator.

The following raw materials were used:
[Thermoplastic polyester elastomer (A)]
・Polyester elastomer A1
According to the method described in Reference Example 1 of paragraph 0017 of JP-A-9-59491, a polyester elastomer having a molar ratio of terephthalic acid/1,4-butanediol/poly(tetramethylene oxide) glycol (PTMG; number average molecular weight 1000) of 100/88/12 was produced.
This polyester elastomer A1 had a melting point of 200° C., a reduced viscosity of 1.86 dl/g, and an acid value of 45 eq/t.
・Polyester elastomer A2
According to the method described in Reference Example 1 of paragraph 0017 of JP-A-9-59491, a polyester elastomer having an ethylene oxide addition polymer of terephthalic acid/1,4-butanediol/poly(propylene oxide) glycol (PPG-PEG; number average molecular weight 3,100, propylene oxide/ethylene oxide 60/40 (molar ratio)) of 100/96.2/3.8 (molar ratio) was produced.
This polyester elastomer A2 had a melting point of 218° C., a reduced viscosity of 1.40 dl/g, and an acid value of 33 eq/t.
・Polyester elastomer A3
According to the method described in Reference Example 1 of paragraph 0017 of JP-A-9-59491, a polyester elastomer having an ethylene oxide addition polymer of terephthalic acid/trimellitic acid/1,4-butanediol/poly(propylene oxide)glycol (PPG-PEG; number average molecular weight 3,100, propylene oxide/ethylene oxide 60/40 (molar ratio)) of 99.9/0.1/96.2/3.8 (molar ratio) was produced.
This polyester elastomer A3 had a melting point of 217° C., a reduced viscosity of 1.38 dl/g, and an acid value of 35 eq/t.

[Epoxy group-containing compound (B)]
・B-1 (TEPIC-S)
N-substituted triisocyanurate (tris(2,3-epoxypropyl)isocyanurate) TEPIC-S (manufactured by Nissan Chemical Industries, Ltd., molecular weight 297, epoxy value 10.1 meq/g)
・B-2 (UG-4070)
Glycidyl group-containing styrene acrylic polymer: ARUFON UG-4070 (manufactured by Toa Gosei Co., Ltd., Mw: 9700, epoxy value: 1.4 meq/g)

[Epoxy group-containing polyolefin resin (C)]
・C-1 (BF-7L)
Epoxy group-containing olefin copolymer: Bondfast BF-7L, manufactured by Sumitomo Chemical Co., Ltd., epoxy value: 0.2 meq/g
・C-2 (BF-7M)
Epoxy group-containing olefin copolymer: Bondfast BF-7M, manufactured by Sumitomo Chemical Co., Ltd., epoxy value: 0.4 meq/g
C-3 (AX8900) [An epoxy group-containing polyolefin resin for comparison.]
Epoxy group-containing olefin copolymer: Rotader AX8900, manufactured by Arkema, epoxy value: 0.6 meq/g

[Unmodified olefin-based elastomer (D)]
・D-1 (29MA03T)
Ethylene-methyl methacrylate copolymer: Lotril 29MA03T, manufactured by Arkema, ethylene/methyl methacrylate ratio = 71/29 (mass ratio), MFR (190 ° C, 2.16 kg) = 3.0 g / 10 min
・D-2 (H1221)
Styrene-ethylene-butylene-styrene block copolymer: Tuftec H1221, manufactured by Asahi Kasei Corporation, styrene/ethylene-butylene ratio = 12/88 (mass ratio), MFR (190°C, 2.16 kg) = 4.5 g/10 min
・D-3 (A-4050S)
Ethylene-butene copolymer: Tafmer A-4050S, manufactured by Mitsui Chemicals, ethylene/butene ratio = 80/20 (mass ratio), MFR (190 ° C, 2.16 kg) = 6.5 g/10 min
・D-4 (35BA40T)
Ethylene/methyl methacrylate copolymer: Lotril 35BA40T, manufactured by Arkema, ethylene/methyl methacrylate ratio = 65/35 (mass ratio), MFR (190 ° C, 2.16 kg) = 35 g/10 min
D-5 (M1943) [An olefin-based elastomer for comparison.]
Styrene-ethylene-butylene-styrene block copolymer: Tuftec M1943, manufactured by Asahi Kasei Corporation, styrene/ethylene-butylene ratio = 20/80 (mass ratio), MFR (190°C, 2.16 kg) = 8.0 g/10 min, modified with maleic acid, acid value = 10 eq/t

[Other additives]
Release agent: Licowax E, manufactured by Clariant Antioxidant: Irganox 1010, manufactured by BASF

Examples 1 to 8, Comparative Examples 1 to 10
The above components were dry blended in the ratios shown in Table 1, and kneaded and pelletized in a twin-screw extruder. The pellets of the polyester elastomer resin composition were used to carry out the following evaluations. The results are shown in Table 1.

Compatibility:
The strand state before pelletization was visually inspected.
◯: The strand is drawn without any problems, and no coarse resin is generated near the die.
△: The strands pulsate slightly.
×: The strand pulsates and large resin deposits are generated near the die.

Surface hardness:
The surface hardness was measured in an environment of 23° C. according to the test method (Shore D) described in ASTM D2240. The test pieces were injection molded at a cylinder temperature of 240° C., and three 100 mm square test pieces of 100 mm × 100 mm × 2 mm (thickness) were stacked on top of each other, and the instantaneous value of Shore D when a needle tip was dropped on them was read to measure the surface hardness.

Melt Viscosity:
According to JIS K7199, using a capillary rheometer (F-1 manufactured by Toyo Seiki Seisakusho), melt viscosity was measured while changing the shear rate from 0.5 mm/min (6.08 sec ^-1 ) to 500 mm/min (6080 sec ^-1 ). The melt viscosity was measured at a shear rate of 6.08 sec ^-1 and at a shear rate of 6080 ^sec-1 at a measurement temperature of 230°C. The nozzle shape was: capillary diameter: 1.0 mm, capillary length: 10 mm.

Melt Flow Rate:
According to the test method (Method A) described in JIS K7210, the melt flow rate (MFR: g/10 min) was measured at a measurement temperature of 240° C. and a load of 5000 g for residence times of 6 and 26 minutes. A composition with a moisture content of 0.1 mass% or less was used for the measurement.

[Evaluation of blow moldability]
The cylinder temperature of the direct blow molding machine (single screw extruder: L/D=25, full flight screw, screw diameter 65 mm) was set to 180-240°C to produce a direct blow molded product. A die lip for forming a parison was attached to the tip of the cylinder, and equipment capable of sealing blow air in the mold was required. The speed at which the parison was injected from the accumulator was controlled to a shear rate of around 6080 sec ^-1 by adjusting the air valve. The inner and outer surfaces of the molded product at this time were observed to confirm whether a molded product with good surface smoothness was obtained.
○: No surface irregularities due to melt fracture, and smoothness is good. ×: Surface irregularities are severe due to melt fracture. -: Not rated.

[Retention stability]
Using the above-mentioned blow molding machine, a molten resin composition was retained in the cylinder, the screw was rotated, and a purging state was established, and confirmation was performed from the viewpoint of shape retention and drawdown of the parison.
◯: No drawdown of the parison or significant increase in viscosity occurs after retention. ×: Drawdown of the parison and/or significant increase in viscosity occurs after retention. -: Not evaluated.

Examples 1 to 8 are resin compositions in which a thermoplastic polyester elastomer (A) is mixed with an epoxy compound (B), an epoxy group-containing polyolefin resin (C), and an unmodified olefin-based elastomer (D) in the prescribed manner, and the resin compositions have excellent direct blow moldability during high-speed injection and excellent retention stability in a cylinder. In addition, the hardness of the molded product obtained has a desirable elastic modulus.
Furthermore, in Examples 1 to 6 and 8, the component (D) having a specific MFR is used compared to Example 7, so the compatibility of the resin composition is good and there is no pulsation of the strand during production.

In Comparative Example 1, only the epoxy compound (B) was blended, and the melt viscosity in the low shear rate region was insufficient, so that drawdown occurred during retention.
In Comparative Example 2, only the epoxy compound (B) was blended. The melt viscosity was high in the low shear rate region but was high in the high shear rate region, causing melt fracture during blow molding and failing to provide a good appearance.
Comparative Example 3 has excellent melt viscosity in the low shear rate and high shear rate regions, but since the epoxy group-containing polyolefin resin (C) is not added, the melt viscosity cannot be maintained during retention, and the product lacks robustness in terms of thickness stability.
In Comparative Example 4, since the unmodified olefin-based elastomer (D) is not added as in the prior art, the melt viscosity in the low shear rate region is low.
Comparative Example 5 has excellent melt viscosity in the low shear rate and high shear rate regions, but since the epoxy group-containing polyolefin resin (C) is not added, the melt viscosity cannot be maintained during retention, and the product lacks robustness in terms of thickness stability.
In Comparative Example 6, since an epoxy group-containing polyolefin resin with a high epoxy value was added, the melt viscosity improved in the low shear rate region, but the melt viscosity increased in the high shear rate region, resulting in a lack of inner surface smoothness during blow molding.
In Comparative Example 7, the amount of epoxy group-containing polyolefin resin (C) added was too large, so that the melt viscosity increased in the high shear rate region, and the inner surface smoothness during blow molding was poor.
In Comparative Example 8, the amount of the unmodified olefin-based elastomer (D) added was too large, so that the molded article produced by injection molding had a hardness that was too soft and was not an optimum hardness for an actual molded article.
In Comparative Example 9, a maleic acid-modified olefin elastomer was added, which reacted with the epoxy compound or the epoxy group-containing polyolefin resin, increasing the melt viscosity in the low shear rate region and the high shear rate region, resulting in a lack of inner surface smoothness during blow molding.
In Comparative Example 10, the epoxy group-containing polyolefin resin (C) reacted too much with the polyester elastomer (A) and the compatibility progressed too much, so that the effect of adding the unmodified olefin elastomer (D) was not obtained.

In the present invention, it is possible to obtain a blow molded article having excellent surface smoothness with few irregularities on the inner and outer surfaces, and to obtain a molded article having excellent robustness against variations in wall thickness. As a result, it is possible to manufacture an intake pipe with little pressure loss and good fuel efficiency for use in an automobile intake pipe equipped with a turbocharger system. In addition, it is useful for other automobile parts applications, home appliance parts applications, etc. that require the above-mentioned excellent properties.

Claims (4)

The composition contains, relative to 100 parts by mass of a thermoplastic polyester elastomer (A), 0.1 to 5 parts by mass of a bifunctional or higher functional epoxy compound (B) having an epoxy value of more than 0.5 meq/g, 0.1 to 5 parts by mass of an epoxy group-containing polyolefin resin (C) having an epoxy value of 0.01 to 0.5 meq/g, and 0.1 to 15 parts by mass of an unmodified olefin elastomer (D),
the thermoplastic polyester elastomer (A) has a hard segment that is polybutylene terephthalate and a soft segment that is an ethylene oxide addition polymer of poly(tetramethylene oxide) glycol and/or poly(propylene oxide) glycol;
the number average molecular weight of the soft segment constituting the thermoplastic polyester elastomer (A) is 500 to 4,000, and the copolymerization amount is 3 to 50 mol % based on the total glycol component;
A polyester elastomer resin composition characterized in that, in terms of melt viscosity measured in accordance with JIS K7199, the melt viscosity at 230°C at a shear rate of 6.08 sec ^{- 1} is 6,800 Pa·s or more and the melt viscosity at a shear rate of 6,080 sec-1 is 160 Pa·s or less. The polyester elastomer resin composition according to claim 1, wherein the unmodified olefin-based elastomer (D) is at least one selected from the group consisting of a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms, a copolymer of ethylene and styrene, and a copolymer of ethylene and an unsaturated compound other than an α-olefin. 3. The polyester elastomer resin composition according to claim 1 , wherein the unmodified olefin-based elastomer (D) has a melt flow rate of 0.1 to 15 g/10 min at 190° C. under a load of 2.16 kg. 4. The polyester elastomer resin composition according to claim 1 , wherein the thermoplastic polyester elastomer (A) is copolymerized with an aromatic tricarboxylic acid in an amount of 0.01 to 3 mol % based on the total acid components.