Thermoplastic polyester resin compositions and extruded articles formed therefrom

Abstract

This invention relates to a thermoplastic polyester resin composition having characteristic resin viscosity properties required for extrusion molding, excellent extrusion stability and extrusion moldability, and optimal flexibility for automotive hoses and flexible tubing; relative to 100 parts by weight of the polyester resin component containing polyester elastomer (a), this thermoplastic polyester resin composition comprises 0.2 to 1.0 parts by weight of a thermoplastic polyester resin composition having two epoxy groups (b), the thermoplastic polyester resin composition having a z-average molecular weight Mz of 250,000 or more, and a Shore D hardness of 60 to 85.

Description

Technical Field

[0001] This invention relates to a thermoplastic polyester resin composition suitable for extrusion molding. More specifically, it relates to a thermoplastic polyester resin composition exhibiting very good extrudability due to its characteristic wide molecular weight distribution. Background Technology

[0002] Many hollow products, such as fuel lines and brake hoses, are used in vehicles. Metal pipes and hoses are of extremely high quality and are used in important parts such as around the engine, but their increased weight is a disadvantage in terms of fuel efficiency in automobiles, and they also present problems such as high cost and poor continuous production.

[0003] Therefore, research is underway to convert automotive hoses and flexible tubes from metal to resin. For example, fluoropolymers such as polytetrafluoroethylene (PTFE) are used for fuel hoses due to their excellent chemical resistance and stability. However, due to the characteristics of fluoropolymers, continuous production rates are low, and their cost as resins is high, limiting their use to specialized products.

[0004] On the other hand, rubber has long been used as a material for low-cost general-purpose products. However, like the materials mentioned above, rubber also presents a major problem of poor continuous productionability due to the characteristics associated with its cross-linking.

[0005] Compared to the materials mentioned above, thermoplastic resins, which offer significant advantages in continuous production rates, are used for automotive hoses and tubing. Thermoplastic resins can be continuously extruded after a single melt, enabling mass production.

[0006] As a thermoplastic resin used in pipes and hoses, thermoplastic polyester resins with excellent durability such as heat resistance and oil resistance are selected according to their required characteristics. Furthermore, in the case of extrusion molding, the viscosity characteristics of the resin are improved and optimized to ensure the dimensional stability and good extrudability of the extruded products. However, the viscosity characteristics that are particularly effective for extrusion molding have not been studied in detail.

[0007] For example, in Patent Document 1, a study was conducted on making the resin skeleton branched while taking into account both softness and extrudability. However, this study was limited to soft materials and did not conduct an in-depth study on the viscosity characteristics that are effective for extrusion molding.

[0008] In addition, in Patent Document 2, research was conducted on the use of epoxy compounds, but the crystallization melting point and Vicat softening point of the resulting composition were studied, and no viscosity characteristics that are important for extrusion molding properties were found.

[0009] Furthermore, Patent Document 3 investigated compositions that were effective for blow molding by combining multifunctional epoxy compounds and carbodiimide compounds, but excessively increased the viscosity of the resin composition, making it unsuitable for good extrusion molding properties.

[0010] Existing technical documents

[0011] Patent documents

[0012] Patent Document 1: Japanese Patent No. 4907779

[0013] Patent Document 2: Japanese Patent Application Publication No. 2000-159985

[0014] Patent Document 3: International Publication No. WO2018 / 174129 Summary of the Invention

[0015] The problem that the invention aims to solve

[0016] The purpose of this invention is to provide a thermoplastic polyester resin composition that has the characteristic resin viscosity properties required for extrusion molding, excellent extrusion stability and extrusion moldability, and the flexibility most suitable for automotive pipes and hoses.

[0017] Methods for solving problems

[0018] The inventors of this invention achieved their invention by studying thermoplastic resin compositions containing a polyester elastomer and a compound having two epoxy groups (i.e., a bifunctional epoxy compound) and increasing the z-average molecular weight Mz, an indicator of the viscosity of the resin composition, to 250,000 or more. They discovered that these compositions exhibit excellent dimensional stability during extrusion molding, possess flexibility, and have excellent extrudability and viscosity characteristics most suitable for automotive hoses and tubing.

[0019] That is, the present invention is as follows.

[0020] [1] A thermoplastic polyester resin composition, characterized in that, relative to 100 parts by weight of a polyester resin component containing a polyester elastomer (a), it comprises 0.2 to 1.0 parts by weight of a compound (b) having two epoxy groups, the thermoplastic polyester resin composition has a z-average molecular weight Mz of 250,000 or more and a Shore D hardness of 60 to 85.

[0021] [2] According to the thermoplastic polyester resin composition of [1], wherein the polyester elastomer (a) is a block copolymer formed by bonding hard segments of polyester with aromatic dicarboxylic acid components and aliphatic and / or alicyclic diol components as constituent components and soft segments with polyalkylene diol components as constituent components.

[0022] In the polyester resin composition, the content of polyalkylene glycol is 1-24% by mass.

[0023] [3] The thermoplastic polyester resin composition according to [1] or [2] further comprises 0.05 to 0.5 parts by mass of a reaction promoter (c) relative to 100 parts by mass of the polyester resin component.

[0024] [4] The thermoplastic polyester resin composition according to any one of [1] to [3], wherein the melt flow rate according to (JISK7210, at 230°C) is 2 to 8 g / 10 min.

[0025] [5] The thermoplastic polyester resin composition according to any one of [1] to [4] is used for extrusion molding.

[0026] [6] An extruded article comprising the thermoplastic polyester resin composition described in [5].

[0027] Invention Effects

[0028] The thermoplastic polyester resin composition of the present invention has the characteristic resin viscosity characteristics required for extrusion molding, and is a thermoplastic polyester resin composition with excellent extrusion stability and extrusion molding properties. It has the flexibility most suitable for automotive hoses and tubing and is suitable for these applications. Detailed Implementation

[0029] The thermoplastic polyester resin composition of the present invention comprises, relative to 100 parts by weight of a polyester resin component containing a polyester elastomer (a), 0.2 to 1.0 parts by weight of a compound (b) having two epoxy groups, and the thermoplastic polyester resin composition has a z-average molecular weight Mz of 250,000 or more and a Shore D hardness of 60 to 85.

[0030] The main component of the thermoplastic polyester resin composition of the present invention is a polyester resin component. In the thermoplastic polyester resin composition, the polyester resin component preferably accounts for 70% or more by mass, more preferably 90% or more by mass, and particularly preferably 95% or more by mass. This polyester resin component contains a polyester elastomer (a). By including the polyester elastomer (a), the thermoplastic polyester resin composition of the present invention can impart the required softness for use as an extruded article for automotive applications.

[0031] The polyester elastomer (a) is preferably a block copolymer formed by bonding hard segments of polyester with aromatic dicarboxylic acid components and aliphatic and / or alicyclic diol components as constituents and soft segments with polyalkylene diol components as constituents.

[0032] The polyester elastomer (a) used in this invention can be polymerized by conventional methods for manufacturing polyester elastomers. There are no particular limitations on the catalyst used in the polymerization process, and conventional catalysts can be used.

[0033] In the polyester elastomer (a) used in this invention, the aromatic dicarboxylic acid component is not particularly limited. Examples of main aromatic dicarboxylic acids include terephthalic acid, and examples of other aromatic dicarboxylic acids include isophthalic acid, naphthalene-2,6-dicarboxylic acid, etc. These aromatic dicarboxylic acid components can be copolymerized in two or more forms.

[0034] When the total acid content constituting the polyester elastomer (a) is set to 100 mol%, the aromatic dicarboxylic acid is preferably 70 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more.

[0035] In addition, when the total acid content of the polyester elastomer (a) used in this invention is set to 100 mol%, terephthalic acid is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 85 mol% or more, and may also be 100 mol%.

[0036] Aliphatic dicarboxylic acids and / or alicyclic dicarboxylic acids may also be used as acid components constituting polyester elastomer (a) if the amount is less than 30 mol%.

[0037] In the polyester elastomer (a) used in this invention, the aliphatic and / or alicyclic diol component is not particularly limited, but is preferably mainly alkylene diols with 2 to 8 carbon atoms. Specifically, examples include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, and 1,4-cyclohexanediol. Among these, for imparting heat resistance, either ethylene glycol or 1,4-butanediol is preferred, and 1,4-butanediol is more preferred.

[0038] In the polyester elastomer (a) used in this invention, the polyalkylene glycol component is preferably a polyalkylene glycol with a number average molecular weight of 500 to 3000. When the number average molecular weight is less than 500, the blockiness of the polyester elastomer (a) decreases, and there is a tendency for its low-temperature properties to decrease. On the other hand, when it exceeds 3000, there is a tendency for the compatibility between hard and soft segments to decrease, and for physical properties to decrease. A more preferred range of number average molecular weight is 800 to 2400, and even more preferably 800 to 2000. The number average molecular weight of the polyalkylene glycol can be calculated by quantitatively analyzing the end groups.

[0039] In the polyester elastomer (a) used in this invention, the preferred hard segment is a polyester with terephthalic acid as the aromatic dicarboxylic acid component and 1,4-butanediol as the aliphatic and / or alicyclic diol component, namely polybutylene terephthalate.

[0040] Furthermore, in the polyester elastomer (a) used in this invention, the polyalkylene glycol component can be a conventional polyalkylene glycol. Examples include polyethylene glycol (PEG), polypropylene glycol (PPG), polytetramethylene glycol (PTMG), polyhexamethyleneoxy glycol, and polypentylene glycol. Block copolymers of these can also be used; examples of block copolymers typically include polyoxyethylene polyoxypropylene glycol (a copolymer of polyethylene glycol and polypropylene glycol), a copolymer of polypentylene glycol and polyethylene glycol, and polymers with ethylene oxide added to the ends of polypropylene glycol. Among these, polytetramethylene glycol is preferred for imparting heat resistance. Alternatively, they can be used in combination.

[0041] The polyester resin component in this invention may be only polyester elastomer (a). In this case, only one type of polyester elastomer may be used, or two or more types of polyester elastomers may be used.

[0042] As a polyester resin component, thermoplastic polyester resins other than polyester elastomer (a) may also be mixed in. In this case, the type of thermoplastic polyester resin is not particularly limited, but a thermoplastic polyester resin that is the same as the polyester constituting the hard segment of polyester elastomer (a) is preferred, and polybutylene terephthalate is particularly preferred.

[0043] In all the above-mentioned cases, the polyester resin component of the present invention preferably has a polyalkylene glycol content of 1 to 24% by mass in the polyester elastomer (a) of the polyester resin component. More preferably, the polyalkylene glycol content is 3 to 22% by mass or less. When it is less than 1% by mass, the softness of the extruded product decreases; when it exceeds 24% by mass, the crystallinity of the resin decreases excessively, which may result in a decrease in oil resistance.

[0044] The thermoplastic polyester resin composition of the present invention comprises a compound (b) having two epoxy groups. Generally, compounds containing two or more epoxy groups are used to increase the viscosity and molecular weight of the thermoplastic polyester resin composition by utilizing the chain-lengthening effect resulting from the reaction with the acid terminator of the polyester resin component containing the polyester elastomer (a). However, the inventors have discovered through in-depth research that using only compounds (b) having two epoxy groups results in the formation of specific high molecular weight components. This is believed to be because compounds (b) having two epoxy groups, in particular, readily form long-chain branches due to secondary hydroxyl groups. While compounds having three or more epoxy groups readily increase the number of branches in their molecular structure, they are less likely to form long-chain branches due to steric hindrance.

[0045] The inventors have conducted in-depth research on the mixing amount of compound (b) having two epoxy groups. The mixing amount of the compound having two epoxy groups is preferably 0.2 parts by mass or more and 1.0 parts by mass or less, more preferably 0.3 parts by mass or more and 0.7 parts by mass or less, relative to 100 parts by mass of the polyester resin component. When the amount is less than 0.2 parts by mass, sufficient extrudability cannot be obtained; when the amount is greater than 1.0 parts by mass, it is unsuitable due to gelation.

[0046] For the compound (b) having two epoxy groups, various compounds can be used. As the compound (b) having two epoxy groups, compounds with a molecular weight of 500 or less are preferred, and compounds with a molecular weight of 150 to 400 are more preferred. Examples include diglycidyl diethylene glycol, bisphenol F type epoxy compounds, etc. Furthermore, in addition to the compound (b) having two epoxy groups, any compound having three or more epoxy groups can be used, without impairing the effects of the present invention.

[0047] Furthermore, the inventors discovered that the improvement in extrudability is attributed to the molecular weight of the thermoplastic polyester resin composition, particularly significantly influenced by Mz (z-average molecular weight: a weighted average weighted by the square of the molecular weight). When Mz is 250,000 or higher, extrudability is significantly improved. More preferably, Mz is 300,000 or higher, and even more preferably, Mz is 350,000 or higher. There is no particular upper limit to Mz, but it is preferably 800,000 or lower, and more preferably 700,000 or lower. When Mz is less than 250,000, it can cause drawdown during molding and reduce the dimensional stability of the molded article. Mz is measured using the method described in the examples below.

[0048] In order to make the Mz of the thermoplastic polyester resin composition within the above range, it is important to mix the compound (b) having two epoxy groups in an appropriate amount based on the compound, and to use the reaction promoter (c) described later as needed.

[0049] The surface hardness of the thermoplastic polyester resin composition of the present invention is 60 to 85 on a Shore D hardness scale, preferably 65 to 82. A hardness less than 60 may result in reduced heat resistance and deformation due to its low hardness; a hardness greater than 85 may result in excessive kinking due to its high hardness. The surface hardness (Shore D hardness) is measured by the method described in the following examples.

[0050] Furthermore, regarding other molecular weights of the thermoplastic polyester resin composition, the weight-average molecular weight Mw is preferably 100,000 or more, more preferably 110,000 or more. Mw is preferably 150,000 or less, more preferably 140,000 or less. The number-average molecular weight Mn is preferably 16,000 or more. Mn is preferably 20,000 or less.

[0051] Furthermore, regarding the molecular weight distribution expressed as Mw / Mn, if it is 5.5 or higher, the influence of high molecular weight components is greater, and therefore it is preferred, more preferably 6.0 or higher. Mw / Mn is preferably 8.5 or lower.

[0052] In the thermoplastic polyester resin composition, in order to promote the reaction between the epoxy groups and the acid terminals of the polyester resin component, thereby increasing the molecular weight, it is preferable to include 0.05 to 0.5 parts by mass of a reaction-promoting substance (c) relative to 100 parts by mass of the polyester resin component. The content of the reaction-promoting substance (c) is more preferably 0.05 to 0.4 parts by mass, further preferably 0.05 to 0.3 parts by mass, and particularly preferably 0.15 to 0.3 parts by mass.

[0053] The reaction promoter (c) between the epoxy groups and the acid terminator can be a conventional product. Examples include phenylimidazoline, triphenylphosphine, phosphonium metal salt, and alkali metal salt compounds. Among these, phenylimidazoline and triphenylphosphine compounds are preferred. In particular, phenylimidazoline compounds facilitate the reaction between epoxy groups to generate specific high molecular weight components, which is highly effective in increasing the molecular weight of thermoplastic polyester resin compositions.

[0054] Regarding the melt flow rate of the thermoplastic polyester resin composition, from the viewpoint of flowability related to extrusion stability, it is preferably 2 g / 10 min or more and 8 g / 10 min or less, more preferably 3 g / 10 min or more and 8 g / 10 min or less, and even more preferably 4 g / 10 min or more and 8 g / 10 min or less. When the melt flow rate is less than 2 g / 10 min, the flowability is too low, which may lead to a decline in the appearance of the product due to melt fracture. When it exceeds 8 g / 10 min, the flowability is too high, and sometimes good extrusion stability cannot be obtained. The melt flow rate is determined by the method described in the examples described later.

[0055] In this invention, the method for increasing the molecular weight (thickening) of the polyester resin component is not particularly limited. Examples include the method described above of mixing the reaction promoter (c) and using melt-blending extrusion, as well as methods using solid-state polymerization.

[0056] For example, in the case of melt-mixing extrusion using a twin-screw extruder in the same direction, the barrel temperature is set to 250°C for melt-mixing, and the resulting wire is water-cooled and granulated.

[0057] The thermoplastic polyester resin composition of the present invention can also be used as a resin composition mixed with various additives described later. In the thermoplastic polyester resin composition of the present invention, a polyester resin component containing a polyester elastomer (a) and a compound having two epoxy groups (b) are present in a post-reaction state. The thermoplastic polyester resin composition may also contain unreacted polyester resin component, unreacted compound having two epoxy groups (b), reaction promoter (c), and various additives.

[0058] In the thermoplastic polyester resin composition of the present invention, it is preferable to mix in commonly used antioxidants such as aromatic amines, hindered phenols, phosphorus compounds, and sulfur compounds. The antioxidants can be mixed during the polymerization stage or after the polyester resin composition is obtained, through melt compounding and extrusion.

[0059] Various other additives can be mixed into the thermoplastic polyester resin composition of the present invention. As additives, resins other than polyester, inorganic fillers, stabilizers, and anti-aging agents can be added without impairing the effects of the present invention.

[0060] In addition, as other additives, mold release agents, coloring pigments, inorganic / organic fillers, coupling agents, viscosity modifiers, quenchers, metal passivators, and other stabilizers and flame retardants can also be added.

[0061] The thermoplastic polyester resin composition of the present invention can be extruded into pipes and hoses for vehicle use.

[0062] Example

[0063] To further illustrate the invention in detail, the following embodiments are provided, but the invention is not limited to any of these embodiments. Furthermore, the measured values ​​described in the embodiments were determined using the following methods.

[0064] Melt Flow Rate (MFR):

[0065] The melt flow index was determined using a Toyo Seiki F-B01 melt flow indexer according to JIS K7210, at a load of 2160g and a measurement temperature of 230℃. The unit is g / 10 minutes.

[0066] Melting point:

[0067] According to the test method described in JIS K7121, a DuPont V4.0B2000 differential scanning calorimeter was used in an argon atmosphere. The sample mass was 10 mg, the initial heating temperature was 30 °C, and the heating rate was 20 °C / min. The obtained endothermic peak temperature was taken as the melting point.

[0068] Surface hardness (Shore D hardness):

[0069] The surface hardness was determined according to the test method (Shore D) described in ASTM D2240 at 23°C. Three injection-molded parts (100 mm wide, 100 mm long, and 2.0 mm thick), produced at a barrel temperature of 20°C above the melting point of the resin (or resin composition) and a mold temperature of 50°C, were stacked together. The instantaneous Shore D value was recorded when the needle tip was dropped to determine the surface hardness.

[0070] z-average molecular weight, weight-average molecular weight, number-average molecular weight:

[0071] The molecular weights of the resin composition were determined as follows. 16 mg of the resin composition was weighed, dissolved in 8 ml of chloroform, filtered through a 0.2 μm membrane filter, and the resulting sample solution was subjected to gel permeation chromatography.

[0072] The molecular weight was calculated using standard polystyrene.

[0073] The apparatus used was a TOSOH HLC-8320GPC, with a chloroform / hexafluoroisopropanol mixture of 98 / 2 (volume ratio) as the solvent. The measurements were performed at a flow rate of 0.6 ml / min, a concentration of 0.05%, an injection volume of 20 μl, a temperature of 40 °C, and a UV detector of 254 nm.

[0074] Evaluation of extrusion moldability

[0075] The barrel temperature of a single-screw extruder (L / D=28, all screw, screw diameter 30mm) was set to the measurement temperature of MFR and extrusion molding was performed. The following evaluations of formability (product appearance, sag, dimensional stability) were judged based on the following criteria.

[0076] The mold uses a T-type mold (mold clearance: 1.5mm).

[0077] Product appearance

[0078] ◎: The surface of the product is very smooth and the appearance is excellent.

[0079] ○: The surface of the product has a slight unevenness, but the appearance is good.

[0080] △: The surface of the product has unevenness and ripples.

[0081] ×: The surface of the product has many bumps and ripples, and the surface has lost its luster.

[0082] drooping

[0083] ◎: Very little drooping, maintaining its shape for a long time.

[0084] ○: Small drooping, maintaining shape.

[0085] △: Large sag, the shape is slightly collapsed but can be extruded and molded.

[0086] ×: The sag is too large, and the shape collapses, making it impossible to extrude and form.

[0087] Dimensional stability

[0088] ◎: The wall thickness remains unchanged, and the product dimensions are very stable.

[0089] ○: The wall thickness changes only slightly, and the product dimensions remain stable.

[0090] △: The wall thickness varies greatly, and the product dimensions are unstable.

[0091] ×: The wall thickness varies greatly, and the product dimensions are very unstable.

[0092] The mixed components used in the examples and comparative examples are shown below.

[0093] [Polyester elastomer (a)]

[0094] (a-1) Polyester elastomer:

[0095] According to the method described in Japanese Patent Application Publication No. 9-59491, a polyester elastomer resin with a terephthalic acid / 1,4-butanediol / polytetramethylene glycol (PTMG, number average molecular weight 1000, manufactured by Mitsubishi Chemical) ratio of 100 / 93 / 7 (mol%) was manufactured. The polyester elastomer has a PTMG content of 24.9% by mass, a melting point of 212°C, a specific viscosity of 1.52 dl / g, and a surface hardness of 57D.

[0096] (a-2) Polyester elastomer:

[0097] According to the method described in Japanese Patent Application Publication No. 9-59491, a polyester elastomer resin with a terephthalic acid / 1,4-butanediol / polytetramethylene glycol (PTMG, number average molecular weight 1000, manufactured by Mitsubishi Chemical) ratio of 100 / 81 / 19 (mol%) was manufactured. The polyester elastomer has a PTMG mass ratio of 48.8%, a melting point of 172°C, a specific viscosity of 1.82 dl / g, and a surface hardness of 44D.

[0098] (a-3) Polyester elastomers:

[0099] According to the method described in Japanese Patent Application Publication No. 9-59491, a polyester elastomer resin with a terephthalic acid / 1,4-butanediol / polytetramethylene glycol (PTMG, number average molecular weight 1000, manufactured by Mitsubishi Chemical) ratio of 100 / 96 / 4 (mol%) is manufactured. The polyester elastomer has a PTMG mass ratio of 15.3%, a melting point of 217°C, a specific viscosity of 1.33 dl / g, and a surface hardness of 68D.

[0100] [Compounds with epoxy groups (b)]

[0101] (b-1) Diglycidyl diethylene glycol (DENACOL EX-850, manufactured by Nagase ChemteX, contains 2 epoxy groups, molecular weight 218)

[0102] (b-2) Bisphenol F type epoxy resin (EPICLON 830, manufactured by DIC, containing 2 epoxy groups, molecular weight 330-354)

[0103] (b-3) Tris(2,3-epoxypropyl)isocyanurate (TEPIC-S, manufactured by Nissan Chemical, containing 3 epoxy groups)

[0104] (b-4) Styrene-acrylic polymers containing polyfunctional glycidyl groups (UG-4050, manufactured by Dong-A Synthetic, containing multiple epoxy groups)

[0105] [Reaction-promoting substance (c)]

[0106] (c-1)2-Phenylidene imidazoline (CUREZOL 2PZL, manufactured by Shikoku Chemical Industry)

[0107] (c-2) Triphenylphosphine (manufactured by NACALAI TESQUE)

[0108] (c-3) Quaternary phosphonium bromide (U-CAT5003, manufactured by San-Apro)

[0109] (c-4) Sodium stearate (manufactured by NACALAI TESQUE)

[0110] [Other polyester resin components (d)]

[0111] (d-1) Polybutylene terephthalate resin: IV (intrinsic viscosity) = 1.28 dl / g, acid value = 40 eq / ton, melting point 225℃

[0112] Examples 1-9, Comparative Examples 1-8

[0113] Each thermoplastic polyester resin composition was prepared according to the composition ratios recorded in Tables 1 and 2. The mixture was melt-mixed and granulated using a twin-screw compounding extruder TEM-35B (manufactured by Shibaura Machinery Co., Ltd.) with the barrel temperature set at 250°C, the ejection rate at 15 kg / hr, and the screw speed at 100 rpm.

[0114] The obtained thermoplastic polyester resin compositions were used for various evaluations. The results are shown in Tables 1 and 2.

[0115] [Table 1]

[0116]

[0117] [Table 2]

[0118]

[0119] Examples 1-9 are thermoplastic polyester resin compositions comprising a polyester elastomer (a) and a compound having two epoxy groups (b), and are examples of thermoplastic polyester resin compositions with a z-average molecular weight Mz of 250,000 or more. Examples 1-9 show that they have sufficient article strength and very good extrudability because they meet the surface hardness requirement, which is important for articles.

[0120] Comparative Examples 1-8 show examples of properties that do not meet the requirements for extrusion moldability and product characteristics.

[0121] Comparative Example 1 does not contain polyester elastomer. Although it has excellent extrusion moldability, its high surface hardness makes it unable to handle the bending of the product.

[0122] In contrast to Comparative Example 1, Comparative Example 2 has a low surface hardness, making it unable to maintain its shape when bent, especially for long strip-shaped products. The heat resistance of the product may also be reduced.

[0123] Comparative Example 3 does not contain compounds with epoxy groups. Due to its high MFR and very small z-average molecular weight, although it has a good appearance, it is very prone to drooping and has very low dimensional stability.

[0124] Comparative Examples 4 and 5 are examples of compounds with more than three epoxy groups, which have low z-average molecular weights and therefore show insufficient extrudability.

[0125] In Comparative Example 6, the z-average molecular weight of the polyester resin component did not increase sufficiently, making it an example of poor extrusion moldability.

[0126] In Comparative Example 7, the amount of the compound with two epoxy groups added was too small to obtain a sufficient z-average molecular weight, which is an example of poor extrudability.

[0127] Comparative Example 8 is an example of excessive addition of a compound with two epoxy groups. Due to excessive thickening of the resin caused by the epoxy group-containing compound, the molecular weight of the thermoplastic polyester resin composition becomes too large. As a result, the surface smoothness of the product is lost and the appearance deteriorates due to the formation of gels and melt fracture during extrusion molding, failing to meet the product characteristics.

[0128] Industrial availability

[0129] The thermoplastic polyester resin composition of this invention is excellent for the extrusion molding of resin tubes and hoses, and therefore makes a great contribution to industry as a resin composition applicable to the anticipated further increase in automotive hollow components.

Claims

1. A thermoplastic polyester resin composition, characterized in that, Compared to 100 parts by weight of a polyester resin component containing polyester elastomer (a), the thermoplastic polyester resin composition contains 0.2 to 1.0 parts by weight of a compound (b) having two epoxy groups, and has a z-average molecular weight Mz of 250,000 or more and a Shore D hardness of 60 to 85. Polyester elastomer (a) is a block copolymer formed by combining hard segments of polyester with aromatic dicarboxylic acid components and aliphatic and / or alicyclic diol components with soft segments with polyalkylene diol components. In the polyester resin composition, the content of polyalkylene glycol is 1-24% by mass.

2. The thermoplastic polyester resin composition according to claim 1, wherein, In the polyester resin component, the content of the polyalkylene glycol component is 3-22% by mass.

3. The thermoplastic polyester resin composition according to claim 1 or 2, wherein, Relative to 100 parts by weight of the polyester resin component, it further comprises 0.05 to 0.5 parts by weight of a reaction promoter (c).

4. The thermoplastic polyester resin composition according to claim 1 or 2, wherein the melt flow rate at 230°C is 2 to 8 g / 10 minutes according to JIS K7210.

5. The thermoplastic polyester resin composition according to claim 1 or 2, used for extrusion molding.

6. An extruded article comprising the thermoplastic polyester resin composition of claim 5.

Images