Thermoplastic polyester elastomers, resin compositions containing such elastomers, and molded articles obtained therefrom.

Abstract

Provided is a thermoplastic polyester elastomer which is excellent especially in terms of extrusion moldability and extrusion molding stability and from which hollow continuous molded articles can be stably produced in even thicknesses over a long period. The polyester elastomer comprises a hard segment comprising a polyester formed from an aromatic dicarboxylic acid and an aliphatic or alicyclic diol and, bonded to the hard segment, a soft segment comprising an aliphatic polycarbonate and has terminal groups, at least some of which have been blocked with a reactive compound, the reactive compound including polycarbodiimide. The polyester elastomer has an acid value of 15 eq / ton or less. Under the conditions of 230°C, the polyester elastomer has (i) a melt viscosity, as measured after 5-minute preheating at a shear rate of 10 / sec, of 1,800 Pa·s or higher and a melt viscosity, as measured after 5-minute preheating at a shear rate of 1,000 / sec, of 800 Pa·s or less and has (ii) a ratio between the melt viscosities at a shear rate of 10 / sec respectively measured after 5-minute preheating and after 25-minute preheating of 0.7-1.3.

Description

Technical Field

[0001] The present invention relates to a thermoplastic polyester elastomer that is excellent not only in heat resistance, weather resistance, heat aging resistance, water resistance, low-temperature characteristics, etc., but also in molding processability, particularly extrusion molding processability and extrusion molding stability. The present invention also relates to a resin composition containing such an elastomer and a molded product obtained therefrom.

Background Art

[0002] In recent years, materials for parts of automobiles and home appliances such as cables and hoses have been replaced from conventional metals and rubbers to thermoplastic resins. Further, with the improvement of performance of automobiles and home appliances, the case where a plurality of parts are arranged close to each other has increased, and the opportunity for resin parts to be exposed to ultra-high temperatures more than before has increased. Therefore, the development of a resin having both heat aging resistance, flame retardancy, and hydrolysis resistance is 、 strongly desired.

[0003] Hitherto, vinyl chloride resins, olefin resins, polyester resins, etc. have been used as the constituent resins of cables. However, vinyl chloride resins and olefin resins have problems such as low melting points and poor heat resistance. Further, although polyester resins have relatively high melting points, they are inferior in hydrolysis resistance and have problems when used outdoors or in vehicles. In order to solve these problems, it has been proposed to use a thermoplastic polyester elastomer as a constituent resin of a cable.

[0004] As such thermoplastic polyester elastomers, those having a crystalline polyester such as polybutylene terephthalate (PBT) and polybutylene naphthalate (PBN) as a hard segment and a polyoxyalkylene glycol such as polytetramethylene glycol (PTMG) and / or a polyester such as polycaprolactone (PCL) and polybutylene adipate (PBA) as a soft segment have been known and commercialized (for example, see Patent Documents 1 and 2).

[0005] Polyester polyether-type elastomers using polyoxyalkylene glycols in the soft segment, as described in Patent Document 1, exhibit excellent water resistance and low-temperature properties, but poor heat aging resistance. Similarly, polyester-polyester-type elastomers using polyester in the soft segment, as described in Patent Document 2, exhibit excellent heat aging resistance, but poor water resistance and low-temperature properties. Neither of these has been able to satisfy the demands of the market in recent years.

[0006] To address these problems, thermoplastic polyester elastomers have been proposed that improve heat resistance and water resistance by using aliphatic carbonates in the soft segments (see Patent Document 3).

[0007] However, the thermoplastic polyester elastomer described in Patent Document 3 is prone to viscosity increases during extrusion molding, and controlling the melt viscosity is extremely difficult. Therefore, it has been difficult to stably produce long, hollow molded products such as cables and hoses with a uniform thickness over a long period of time by extrusion molding. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 10-17657 [Patent Document 2] Japanese Patent Publication No. 2003-192778 [Patent Document 3] Patent No. 4244067 [Overview of the project] [Problems that the invention aims to solve]

[0009] The present invention was devised to overcome the problems of the conventional thermoplastic polyester elastomers described above, and its objective is to provide a thermoplastic polyester elastomer that is excellent not only in heat resistance, weather resistance, heat aging resistance, water resistance, and low-temperature properties, but also in extrusion moldability and extrusion stability, and that can stably produce hollow, long molded products such as cables and hoses with a uniform thickness over a long period of time. [Means for solving the problem]

[0010] The present inventors diligently investigated methods to prevent the problem of viscosity increase during extrusion molding in conventional thermoplastic polyester elastomers, particularly those using aliphatic carbonates in the soft segment, in order to achieve the above objectives. As a result, they found that extrusion moldability can be improved by suitably controlling the acid value of the thermoplastic polyester elastomer, as well as the melt viscosity at low shear rates and at high shear rates, to specific ranges. Furthermore, by suitably controlling the change in melt viscosity over time (retention stability) at low shear rates to a specific range, viscosity increase during prolonged extrusion molding can be suppressed, thereby improving extrusion molding stability. They also found that in order to control the melt viscosity and its retention stability to a specific range, it is important to increase the molecular weight / add branching to the thermoplastic polyester elastomer by sealing the end groups of the thermoplastic polyester elastomer with a reactive compound having a reactive functional group, or to lower the acid value of the thermoplastic polyester elastomer to a specific range.

[0011] The present invention was completed based on the above findings and has the following configurations (1) to (5). (1) A thermoplastic polyester elastomer comprising a hard segment made of a polyester composed of an aromatic dicarboxylic acid and an aliphatic or alicyclic diol, and a soft segment mainly made of an aliphatic polycarbonate, wherein at least a portion of the terminal groups are sealed with a reactive compound, and the reactive compound contains polycarbodiimide, The acid value of the thermoplastic polyester elastomer is 15 eq / ton or less. A thermoplastic polyester elastomer characterized by satisfying the following conditions (i) and (ii) when its melt viscosity is measured at 230°C in accordance with JIS K7199: (i) The melt viscosity at a shear rate of 10 / second with a preheating time of 5 minutes is 1800 Pa·s or more, and the melt viscosity at a shear rate of 1000 / second with a preheating time of 5 minutes is 800 Pa·s or less; (ii) The ratio of melt viscosity at a shear rate of 10 / second measured with a preheating time of 5 minutes and a preheating time of 25 minutes was 0.7 to 1.3. (2) The thermoplastic polyester elastomer according to (1), further comprising a reactive compound having at least one functional group selected from the group consisting of a glycidyl group, an acid anhydride group, and an isocyanate group. (3) A resin composition characterized by containing the thermoplastic polyester elastomer described in (1) or (2) and a flame retardant. (4) A molded article characterized by being obtained by extruding the thermoplastic polyester elastomer described in (1) or (2) or the resin composition described in (3). (5) The molded article according to (4), characterized in that the molded article is a cable or a hose. [Effects of the Invention]

[0012] The thermoplastic polyester elastomer of the present invention not only meets the basic performance requirements for automotive and home appliance parts, such as heat resistance, weather resistance, heat aging resistance, water resistance, and low-temperature properties, but also exhibits excellent extrusion moldability and extrusion stability, enabling the stable production of long, hollow molded products requiring uniform thickness, such as cables and hoses, over long periods of time. [Modes for carrying out the invention]

[0013] The thermoplastic polyester elastomer of the present invention is based on a thermoplastic polyester elastomer in which a hard segment made of a polyester composed of an aromatic dicarboxylic acid and an aliphatic or alicyclic diol is bonded to a soft segment made mainly of an aliphatic polycarbonate, and at least a portion of its terminal groups are sealed with a reactive compound containing polycarbodiimide, and is characterized by having an acid value within a specific range, and further having a melt viscosity at a specific range of low shear rates, a melt viscosity at a specific range of high shear rates, and a change in the melt viscosity at a specific range of low shear rates over time (retention stability).

[0014] First, let's describe the hard segment of the thermoplastic polyester elastomer. This hard segment consists of a polyester composed of an aromatic dicarboxylic acid and an aliphatic or alicyclic diol.

[0015] Among the polyester components of the hard segment of thermoplastic polyester elastomer, ordinary aromatic dicarboxylic acids are widely used as aromatic dicarboxylic acids and are not particularly limited, but it is preferable that they be mainly terephthalic acid or naphthalenedicarboxylic acid. Other acid components include aromatic dicarboxylic acids such as diphenyldicarboxylic acid, isophthalic acid, and 5-sodium sulfisoisophthalic 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 are used in a range that does not significantly lower the melting point of the resin, and their amount is preferably less than 30 mol% of the total acid components, and more preferably less than 20 mol%.

[0016] Among the components of the polyester in the hard segment of the thermoplastic polyester elastomer, as the aliphatic or alicyclic diol, general aliphatic or alicyclic diols are widely used and not particularly limited, but mainly, alkylene glycols having 2 to 8 carbon atoms are desirable. Specifically, ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, etc. can be mentioned. Among these, 1,4-butanediol and 1,4-cyclohexanedimethanol are most preferred.

[0017] Specifically, as the component constituting the polyester of the hard segment of the thermoplastic polyester elastomer, those composed of butylene terephthalate units or butylene naphthalate units are preferable in terms of physical properties, moldability, and cost performance.

[0018] The polyester constituting the hard segment of the thermoplastic polyester elastomer can be easily obtained according to the usual polyester production method. Such a polyester preferably has a number average molecular weight of 10,000 to 40,000.

[0019] Next, the soft segment of the thermoplastic polyester elastomer will be described. This soft segment mainly consists of an aliphatic polycarbonate. Here, "mainly" means that the aliphatic polycarbonate occupies 60% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more of the soft segment.

[0020] The aliphatic polycarbonate constituting the soft segment of the thermoplastic polyester elastomer preferably mainly consists 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, 2 - methyl - 1,8 - octanediol, and the like. Particularly, from the viewpoints of the flexibility and low - temperature properties of the obtained polyester elastomer resin composition, aliphatic diols having 5 to 12 carbon atoms are preferable. These components may be used alone or, if necessary, two or more of them may be used in combination.

[0021] As the aliphatic polycarbonate diol having good low - temperature properties and constituting the soft segment of the thermoplastic polyester elastomer, those having a low melting point (for example, 70°C or lower) and a low glass transition temperature are preferable. Generally, the aliphatic polycarbonate diol composed of 1,6 - hexanediol used to form the soft segment of the thermoplastic polyester elastomer has a glass transition temperature as low as around - 60°C and a melting point of around 50°C, so it has good low - temperature properties. In addition, for example, the aliphatic polycarbonate diol obtained by copolymerizing an appropriate amount of 3 - methyl - 1,5 - pentanediol with the above - mentioned aliphatic polycarbonate diol has a slightly higher glass transition point than the original aliphatic polycarbonate diol, but since its melting point decreases or becomes amorphous, it corresponds to an aliphatic polycarbonate diol having good low - temperature properties. Also, for example, the aliphatic polycarbonate diol composed of 1,9 - nonanediol and 2 - methyl - 1,8 - octanediol has a melting point of about 30°C and a glass transition temperature as low as around - 70°C, so it corresponds to an aliphatic polycarbonate diol having good low - temperature properties.

[0022] The aliphatic polycarbonate diols described above are not necessarily composed solely of polycarbonate components, but may also be copolymerized in small amounts with other glycols, dicarboxylic acids, ester compounds, or ether compounds. Examples of copolymer components include glycols such as dimer ols, hydrogenated dimer ols, and their modified forms; dicarboxylic acids such as dimer acids and hydrogenated dimer acids; polyesters or oligoesters composed of aliphatic, aromatic, or alicyclic dicarboxylic acids and glycols; polyesters or oligoesters composed of ε-caprolactone, etc.; polyalkylene glycols such as polytetramethylene glycol and polyoxyethylene glycol, or oligoalkylene glycols.

[0023] The copolymer component can be used in an amount that does not substantially eliminate the effect of the aliphatic polycarbonate segment. Specifically, it is 40 parts by mass or less, preferably 30 parts by mass or less, and more preferably 20 parts by mass or less, per 100 parts by mass of the aliphatic polycarbonate segment. If the amount of copolymer component is too high, the resulting polyester elastomer resin composition may have poor heat aging resistance and water resistance.

[0024] In thermoplastic polyester elastomers, the mass ratio of polyester constituting the hard segment to aliphatic polycarbonate and optionally copolymer components constituting the soft segment is generally in the range of hard segment:soft segment = 30:70 to 95:5, preferably 40:60 to 90:10, more preferably 45:55 to 87:13, and most preferably 50:50 to 85:15.

[0025] Thermoplastic polyester elastomers are polyester elastomers in which a hard segment made of polyester composed of an aromatic dicarboxylic acid and an aliphatic or alicyclic diol, as described above, and a soft segment made mainly of aliphatic polycarbonate are bonded together. Here, "bonded together" means that the hard segment and the soft segment are not bonded together by a chain extender such as an isocyanate compound, but rather the units constituting the hard segment and the soft segment are directly bonded together by ester bonds or carbonate bonds. To create such a state, it is preferable to obtain a thermoplastic polyester elastomer by a blocking reaction in which the polyester constituting the hard segment, the polycarbonate constituting the soft segment, and optionally various copolymer components are melted and transesterified and depolymerized for a certain period of time.

[0026] The above blocking reaction is preferably carried out at a temperature within the range of the melting point of the polyester constituting the hard segment or the melting point + 30°C. In this reaction, the concentration of the active catalyst in the system is arbitrarily set according to the temperature at which the reaction takes place. That is, at higher reaction temperatures, the transesterification and depolymerization reactions proceed rapidly, so it is desirable for the concentration of the active catalyst in the system to be low, and at lower reaction temperatures, it is desirable for a certain concentration of the active catalyst to be present.

[0027] The catalyst can be one or more commonly used titanium compounds such as titanium tetrabutoxide and potassium titanate oxalate, or tin compounds such as dibutyltin oxide and monohydroxybutyltin oxide. The catalyst may already be present in the polyester or polycarbonate, in which case it does not need to be added. Furthermore, the catalyst in the polyester or polycarbonate may be partially or substantially completely deactivated beforehand by any method. For example, when titanium tetrabutoxide is used as the catalyst, deactivation can be carried out by adding phosphorus compounds such as phosphite, phosphorus, triphenyl phosphate, tristriethylene glycol phosphate, orthophosphoric acid, carbetoxydimethyldiethyl phosphonic acid, triphenyl phosphite, trimethyl phosphate, and trimethyl phosphite, but is not limited to these.

[0028] The above reaction can be carried out by arbitrarily determining the combination of reaction temperature, catalyst concentration, and reaction time. In other words, the reaction conditions vary depending on various factors such as the type and quantity ratio of hard and soft segments used, the shape of the apparatus used, and the stirring conditions, so the optimal values ​​should be adopted as appropriate.

[0029] The optimal value for the above reaction conditions exists when, for example, the difference between the melting point of the resulting chain-extended polymer and the melting point of the polyester used as the hard segment is between 2°C and 60°C. If the melting point difference is less than 2°C, the two segments are not mixed and / or reacted, and the resulting polymer exhibits inferior elastic properties. On the other hand, if the melting point difference exceeds 60°C, the transesterification reaction proceeds significantly, reducing the blocking properties of the resulting polymer, and consequently lowering its crystallinity, elastic properties, etc.

[0030] It is desirable to deactivate any remaining catalyst in the molten mixture obtained by the above reaction as completely as possible using conventionally known methods. If more catalyst remains than necessary, the transesterification reaction will proceed further during compounding, molding, etc., causing changes in the physical properties of the resulting polymer.

[0031] The deactivation reaction is carried out, for example, by adding phosphorus compounds such as phosphite, phosphorus, triphenyl phosphate, tristriethylene glycol phosphate, orthophosphate, carbetoxydimethyldiethyl phosphonic acid, triphenyl phosphite, trimethyl phosphate, and trimethyl phosphite, but is not limited to these methods.

[0032] Thermoplastic polyester elastomers may contain small amounts of trifunctional or higher polycarboxylic acids or polyols. For example, trimellitic anhydride, benzophenonetetracarboxylic acid, trimethylolpropane, glycerin, etc., can be used.

[0033] In this invention, the thermoplastic polyester elastomer is in a state in which at least a portion of its end groups are sealed with a reactive compound. Hereinafter, this thermoplastic polyester elastomer will be referred to as "end-group sealed thermoplastic polyester elastomer". By sealing at least a portion of the end groups of the thermoplastic polyester elastomer with reactive functional groups in the reactive compound, it is possible to increase the molecular weight / introduce branching to the thermoplastic polyester elastomer, effectively reduce the acid value of the thermoplastic polyester elastomer, and improve the melt viscosity properties and retention stability of the thermoplastic polyester elastomer.

[0034] In this invention, "at least a portion of the end groups of the thermoplastic polyester elastomer are sealed with a reactive compound" means that it is not required that "all" of the end groups of the thermoplastic polyester elastomer be sealed with a reactive compound. This invention assumes a state in which "almost" of the end groups of the thermoplastic polyester elastomer are sealed with a reactive compound, and also includes the state of a composition in which free reactive compounds are present. This is because it is difficult to seal "all" of the end groups of the thermoplastic polyester elastomer with a reactive compound, even if a reactive compound is added in excess or the method of addition is devised as described later. The sealing rate of the end groups of the thermoplastic polyester elastomer is difficult to measure directly, but it can be estimated using the acid value of the thermoplastic polyester elastomer as an indicator. As the end groups of the thermoplastic polyester elastomer are sealed, the acid value of the thermoplastic polyester elastomer decreases compared to the acid value of the original thermoplastic polyester elastomer.

[0035] In the present invention, the reactive compound has the role of imparting branching to the thermoplastic polyester elastomer by sealing the end groups of the thermoplastic polyester elastomer, or increasing the molecular weight of the thermoplastic polyester elastomer, thereby controlling the melt viscosity characteristics at low and high shear rates to a suitable range, and also the role of lowering the acid value of the thermoplastic polyester elastomer by sealing the end groups of the thermoplastic polyester elastomer, thereby improving the retention stability of the melt viscosity. In the present invention, the reactive compound is not particularly limited as long as it has a reactive functional group that can react with the end groups (hydroxyl groups or carboxyl groups) of the thermoplastic polyester elastomer, but it is necessary to include at least polycarbodiimide. Polycarbodiimide is particularly excellent at the latter of the two roles described above, which is lowering the acid value of the thermoplastic polyester elastomer, and can therefore greatly contribute to improving the retention stability of the melt viscosity. The polycarbodiimides that can be used in the present invention are any polycarbodiimides having two or more carbodiimide groups (-N=C=N- structure) in one molecule, such as aliphatic polycarbodiimides, alicyclic polycarbodiimides, aromatic polycarbodiimides, and copolymers thereof. Preferably, they are aliphatic polycarbodiimides or alicyclic polycarbodiimides.

[0036] Polycarbodiimides can be obtained, for example, by the decarbonization reaction of diisocyanate compounds. Examples of diisocyanate compounds that can be used here include 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 1,3-phenylenediisocyanate, 1,4-phenylenediisocyanate, 2,4-tolylenediisocyanate, 2,6-tolylenediisocyanate, 1,5-naphthylenediisocyanate, hexamethylenediisocyanate, dicyclohexylmethane diisocyanate, cyclohexane-1,4-diisocyanate, xylylenediisocyanate, isophorone diisocyanate, methylcyclohexanediisocyanate, tetramethylxylylenediisocyanate, and 1,3,5-triisopropylphenylene-2,4-diisocyanate. These can be used individually or copolymerized in groups of two or more. Furthermore, branched structures may be introduced, or functional groups other than carbodiimide groups and isocyanate groups may be introduced by copolymerization. In addition, while terminal isocyanates can be used as is, the degree of polymerization may be controlled by reacting the terminal isocyanates, or some of the terminal isocyanates may be sequestered.

[0037] Polycarbodiimides preferably have isocyanate groups at their terminal ends, with an isocyanate group content of 0.5 to 4% by mass, for reasons of stability and ease of handling. More preferably, the isocyanate group content is 1 to 3% by mass. In particular, polycarbodiimides derived from dicyclohexylmethane diisocyanate or isophorone diisocyanate having an isocyanate group content within the above range are preferred. The isocyanate group content can be measured using a conventional method (dissolving with an amine and back-titrating with hydrochloric acid).

[0038] Polycarbodiimides preferably contain 2 to 50 carbodiimide groups per molecule for stability and ease of handling. More preferably, they contain 5 to 30 carbodiimide groups per molecule. The number of carbodiimide groups in a polycarbodiimide molecule corresponds to the degree of polymerization if the polycarbodiimide is obtained from a diisocyanate compound. For example, a polycarbodiimide obtained by linking 21 diisocyanate compounds in a chain has a degree of polymerization of 20, and the number of carbodiimide groups in the molecular chain is 20. Since polycarbodiimides are usually mixtures of molecules of various lengths, the number of carbodiimide groups is expressed as an average value. Having a carbodiimide group number within the above range and being solid at around room temperature allows for powdering, resulting in excellent workability and compatibility when mixed with thermoplastic polyester elastomers (described later), and is also preferable in terms of uniform reactivity and bleed-out resistance. The number of carbodiimide groups can be measured, for example, using a conventional method (dissolving with an amine and performing a back titration with hydrochloric acid).

[0039] The reactive compound used in the present invention is sufficient with polycarbodiimide alone, but may further contain a reactive compound having at least one functional group selected from the group consisting of glycidyl groups (epoxy groups), acid anhydride groups, and isocyanate groups, if necessary. The number of functional groups in such a reactive compound is two or more per molecule. As described above, polycarbodiimide is excellent at reducing the acid value of thermoplastic polyester elastomers, but due to its stereostructural factors, it is inferior at imparting branching to thermoplastic polyester elastomers. Therefore, the weakness of polycarbodiimide can be compensated for by further including a reactive compound having at least one functional group selected from the group consisting of glycidyl groups (epoxy groups), acid anhydride groups, and isocyanate groups.

[0040] When the reactive compound is a compound having an epoxy group (glycidyl group), examples of polyfunctional epoxy compounds having two or more epoxy groups include, specifically, 1,6-dihydroxynaphthalenediglycidyl ether and 1,3-bis(oxyranylmethoxy)benzene, which have two epoxy groups; 1,3,5-tris(2,3-epoxypropyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione and diglycerol triglycidyl ether, which have three epoxy groups; and 1-chloro-2,3-epoxypropane-formaldehyde-2,7-naphthalenediol polycondensate and pentaerythritol polyglycidyl ether, which have four epoxy groups. Among these, polyfunctional epoxy compounds with heat resistance in their skeleton are preferred. Particularly preferred are bifunctional or tetrafunctional epoxy compounds with a naphthalene structure as the skeleton, or trifunctional epoxy compounds with a triazine structure as the skeleton. Considering the degree of increase in the solution viscosity of the thermoplastic polyester elastomer, the effect of efficiently reducing the acid value of the thermoplastic polyester elastomer, and the degree of gelation due to aggregation and solidification of the epoxy itself, bifunctional or trifunctional epoxy compounds are preferred.

[0041] Other examples include copolymers that contain two or more glycidyl groups per molecule, have a weight-average molecular weight of 4000 to 25000, and consist of (X) 20 to 99% by mass of vinyl aromatic monomers, (Y) 1 to 80% by mass of glycidyl (meth)acrylate, and (Z) 0 to 79% by mass of vinyl group-containing monomers other than (X) that do not contain epoxy groups.

[0042] When the reactive compound is a compound containing an acid anhydride group, compounds containing 2 to 4 anhydrides per molecule are preferred in terms of stability and ease of handling. Examples of such compounds include phthalic anhydrides, trimellitic anhydrides, and pyromellitic anhydrides.

[0043] When the reactive compound is a compound containing an isocyanate group, examples of isocyanate compounds that serve as raw materials for the polycarbodiimides mentioned above can be cited.

[0044] Next, a method for occluding end groups using reactive compounds will be described. To occlude the end groups of a thermoplastic polyester elastomer with a reactive compound, the thermoplastic polyester elastomer and the reactive compound should be mixed and brought into contact with each other. Upon contact, the reactive functional groups in the reactive compound react with the end groups of the thermoplastic polyester elastomer, thereby occluding the end groups of the thermoplastic polyester elastomer. The reaction between the end groups of the thermoplastic polyester elastomer and the reactive functional groups in the reactive compound can occur without a catalyst, but it is desirable to use a catalyst to accelerate the reaction. Generally, amines, imidazoles, and the like are preferred as catalysts.

[0045] When the reactive compound is polycarbodiimide, the amount blended is preferably 0.5 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, per 100 parts by mass of thermoplastic polyester elastomer. Exceeding the above upper limit may impair flexibility and reduce mechanical properties, heat resistance, and melt viscosity. Conversely, if it is below the above lower limit, the amount of -N=C=N- in the thermoplastic polyester elastomer will decrease, resulting in inferior effects on improving hydrolysis resistance and extrusion moldability. On the other hand, when the reactive compound is a reactive compound having at least one functional group selected from the group consisting of glycidyl group (epoxy group), acid anhydride group, and isocyanate group, the amount blended is preferably 0.1 to 4.5 parts by mass, more preferably 0.1 to 4 parts by mass, per 100 parts by mass of thermoplastic polyester elastomer. Exceeding the above upper limit may result in excessive thickening effect, adversely affecting moldability and the mechanical properties of the molded article. Conversely, if it is below the above lower limit, the target branching or molecular chain extension effect may be insufficient.

[0046] Furthermore, in order to ensure that the blended reactive compound can reliably come into contact with and react with the end groups of the thermoplastic polyester elastomer, it is preferable to devise a method for adding the reactive compound to the thermoplastic polyester elastomer. For example, instead of simultaneously mixing the thermoplastic polyester elastomer, the reactive compound, and additives such as flame retardants that can be added as desired as described later, as in the conventional method, it is preferable to pre-implant the reactive compound onto a portion of the thermoplastic polyester elastomer, while mixing and melting the remaining thermoplastic polyester elastomer with the additives, and then adding the thermoplastic polyester elastomer with the reactive compound implanted onto it to this molten mixture. This allows the reactive compound to be uniformly melted and kneaded, ensuring that it can reliably come into contact with and react with the end groups of the thermoplastic polyester elastomer. If the reactive compound is not uniformly melted and kneaded, not only will the end groups of the thermoplastic polyester elastomer not be sufficiently sealed, but unreacted reactive compounds may remain in the composition, potentially adversely affecting the extrusion molding process. Specifically, if there is thermoplastic polyester elastomer with unsealed ends, prolonged retention during extrusion molding can easily lead to thermal decomposition and hydrolysis, potentially resulting in a decrease in molecular weight and melt viscosity. Furthermore, the presence of unreacted reactive compounds may lead to gelation, potentially increasing the melt viscosity.

[0047] The end-group-sealed thermoplastic polyester elastomer obtained in this way has a lower acid value than the original thermoplastic polyester elastomer because the acid groups at the ends are sealed. Specifically, it can achieve a low acid value of 15 eq / ton or less, preferably 10 eq / ton or less, and more preferably 5 eq / ton or less. The lower limit of the acid value is not particularly limited, but for example, it is 0 eq / ton. When the acid value is within the above range, the retention stability of the melt viscosity during molding is improved, and in the case of extrusion molding of long hollow objects such as cables and hoses, thickness uniformity is improved. Furthermore, the acid value also contributes to heat resistance, heat aging resistance, and hydrolysis resistance, and when the acid value is within the above range, it exhibits excellent heat resistance, heat aging resistance, and hydrolysis resistance.

[0048] Regarding the specific melt viscosity characteristics, the end-group sealed thermoplastic polyester elastomer of the present invention is characterized by satisfying the following (i) and (ii) when its melt viscosity is measured under conditions of 230°C in accordance with JIS K7199: (i) The melt viscosity at a shear rate of 10 / second with a preheating time of 5 minutes is 1800 Pa·s or more, preferably 2500 Pa·s or more, and the melt viscosity at a shear rate of 1000 / second with a preheating time of 5 minutes is 800 Pa·s or less, preferably 700 Pa·s or less; (ii) The ratio of melt viscosity at a shear rate of 10 / second measured with a preheating time of 5 minutes and a preheating time of 25 minutes is 0.7 to 1.3, preferably 0.8 to 1.2. The upper limit of the melt viscosity at a shear rate of 10 / second with a preheating time of 5 minutes is not particularly limited, but for example it is 50,000 Pa·s, and the lower limit of the melt viscosity at a shear rate of 1,000 / second with a preheating time of 5 minutes is not particularly limited, but for example it is 150 Pa·s.

[0049] The melt viscosity being within the range specified by (i) provides excellent extrudeability. Specifically, when extruding end-group sealed thermoplastic polyester elastomers or resin compositions containing them, they have sufficient shape retention and sufficient fluidity to obtain thin films or fine-shaped extruded articles, enabling advanced shape design such as molded products that are hollow, long, and require uniform thickness.

[0050] The means for satisfying (i) above are not particularly limited, but for example, as mentioned above, branching can be imparted to the thermoplastic polyester elastomer by sealing the end groups of the thermoplastic polyester elastomer with a reactive compound, or the thermoplastic polyester elastomer can be made to have a high molecular weight. Another method is to impart branching to the thermoplastic polyester elastomer by copolymerizing trimethylolpropane during the polymerization of the thermoplastic polyester elastomer. Furthermore, it is also possible to separately blend a branched / high molecular weight thermoplastic polyester elastomer in addition to the thermoplastic polyester elastomer. With such branching and high molecular weight, in the low shear rate range, the entanglement of polymer chains increases, the melt viscosity increases, and deformation becomes more difficult (shape stability increases), while in the high shear rate range, the entanglement of molecular chains is relaxed, making it easier to flow, and the aforementioned thickening effect decreases. It is thought that this phenomenon improves the uniformity of thickness during extrusion molding.

[0051] On the other hand, if the melt viscosity is within the range of (ii), sufficient retention stability is achieved, enabling stable production over long periods of time. The means for satisfying (ii) are not particularly limited, but for example, as mentioned above, the acid value can be reduced by sealing the end groups of the thermoplastic polyester elastomer with a reactive compound. In this case, it is important to control the process so that as few acid groups as possible remain at the ends of the thermoplastic polyester elastomer. It is also important to minimize the amount of unreacted reactive compound remaining. If thermoplastic polyester elastomer that has not had its ends sealed is present, thermal decomposition and hydrolysis are likely to occur due to retention during prolonged extrusion molding, which may lead to a decrease in molecular weight and a decrease in melt viscosity. Furthermore, if unreacted reactive compound is present, gelation may occur, which may increase the melt viscosity.

[0052] In this invention, while the end-group-bound thermoplastic polyester elastomer can be used alone as a molding material, it is advantageous to use it in combination with a flame retardant in the form of a resin composition to improve the flame retardancy of the resulting molded article. As the flame retardant, halogen-based or non-halogen-based flame retardants and flame retardant additives can be used, and these may be used alone or in combination. Examples of flame retardants include triazine compounds / or derivatives thereof, phosphorus compounds, bromine compounds, and antimony compounds. The flame retardant can be included in the resin composition at a concentration of 1 to 40% by mass.

[0053] Examples of triazine compounds and / or derivatives thereof include melamine, melamine cyanurate, melamine phosphate, and guanidine sulfamate. Examples of phosphorus compounds include red phosphorus compounds and ammonium polyphosphate salts. Examples of brominated compounds include brominated phenoxy resins, brominated epoxy resins, brominated epoxy oligomers, TBA carbonate oligomers, ethylene bis(tetrabromophthal)imide, hexabromobenzene, and decabromodiphenyl ether. Examples of flame retardant additives include antimony trioxide, antimony tetroxide, antimony pentoxide, sodium pyroantimonate, tin dioxide, zinc metaborate, aluminum hydroxide, magnesium hydroxide, zirconium oxide, molybdenum oxide, red phosphorus compounds, ammonium polyphosphate salts, melamine cyanurate, and tetrafluoroethylene.

[0054] Furthermore, various additives can be added to the resin composition of the present invention depending on the purpose. Examples of additives include known hindered phenol, sulfur, phosphorus, and amine antioxidants; light stabilizers such as hindered amine, triazole, benzophenone, benzoate, nickel, and salicyl; antistatic agents; lubricants; molecular modifiers such as peroxides; compounds having reactive groups such as epoxy compounds and carbodiimide compounds; metal deactivators; organic and inorganic nucleating agents; neutralizing agents; antacids; antibacterial agents; fluorescent whitening agents; fillers; and organic and inorganic pigments. When these additives are added, it is preferable that they be included in total in the resin composition at a concentration of 0.1 to 10% by mass, and more preferably at a concentration of 0.5 to 5% by mass.

[0055] These additives can be incorporated using kneaders such as heated rolls, extruders, and Banbari mixers. They can also be added to and mixed into oligomers before the transesterification or polycondensation reaction when producing thermoplastic polyester elastomers.

[0056] The resin composition of the present invention can be manufactured by mixing the above-mentioned components and, if necessary, various stabilizers, pigments, etc., and then melt-kneading them. Any method known to those skilled in the art may be used for melt-kneading, and a single-screw extruder, twin-screw extruder, pressure kneader, Banbury mixer, etc., can be used. Among these, the use of a twin-screw extruder is preferred.

[0057] Furthermore, as mentioned above, in order to ensure that reactive compounds such as polycarbodiimide can reliably come into contact with and react with the end groups of thermoplastic polyester elastomer, it is preferable not to mix all the components at the same time, but rather to pre-impregnate a portion of the thermoplastic polyester elastomer with the reactive compound, while mixing and melting the remaining thermoplastic polyester elastomer with the additive, and then feeding the thermoplastic polyester elastomer with the reactive compound impregnated into this molten material from a side feeder. By adopting this feeding method, the reactive compound will not adhere to the manufacturing equipment, and the loss of reactive compound during feeding can also be prevented.

[0058] The end-group sealed thermoplastic polyester elastomer and resin composition containing the same of the present invention are configured as described above, and therefore have excellent heat resistance, weather resistance, heat aging resistance, water resistance, low-temperature properties, as well as excellent extrusion moldability and extrusion stability. For this reason, they can be used to stably produce long, hollow molded products such as cables and hoses with uniform thickness over long periods of time by extrusion molding. [Examples]

[0059] The present invention will be specifically described below using examples and comparative examples. However, the present invention is not limited by the following examples, and can be modified and implemented within the scope of the spirit described above, and all such modifications fall within the technical scope of the present invention. In this specification, each measurement was performed according to the following method.

[0060] (1) Melting point (Tm) of thermoplastic polyester elastomer Thermoplastic polyester elastomer, dried under reduced pressure at 50°C for 15 hours, was heated from room temperature at a rate of 20°C / min using a differential scanning calorimeter DSC-50 (Shimadzu Corporation). The peak temperature of endothermic melting was measured and defined as the melting point (Tm). The sample was weighed 10 mg into an aluminum pan (TA Instruments, part number 900793.901), sealed with an aluminum lid (TA Instruments, part number 900794.901), and measured under an argon atmosphere.

[0061] (2) Reduced viscosity of thermoplastic polyester elastomers 0.05 g of thermoplastic polyester elastomer was dissolved in 25 mL of a mixed solvent (phenol / tetrachloroethane = 60 / 40), and the reduced viscosity was measured at 30°C using an Ostwald viscometer.

[0062] (3) Acid value 0.5 g of thermoplastic polyester elastomer was dissolved in 100 ml of benzyl alcohol / chloroform (50 / 50 mass ratio), and the acid value was determined by titration with an ethanol solution of KOH. Phenol red was used as an indicator. The acid value was expressed as equivalents (eq / ton) per ton of resin.

[0063] (4) Melt viscosity The melt viscosity of thermoplastic polyester elastomers was measured using a "Capillograph 1D" manufactured by Toyo Seiki Seisakusho Co., Ltd. Specifically, under the conditions of a capillary with a diameter of 1.0 mm, a length of 40 mm, a cylinder diameter of 9.55 mm, and a temperature of 230°C, the melt viscosity was measured after a preheating time of 5 minutes at shear rates of 10 / sec and 1000 / sec.

[0064] (5) Retention stability of melt viscosity Similar to the measurement of melt viscosity, the melt viscosity at a shear rate of 10 / second after a preheating time of 5 minutes was measured and defined as η5. The melt viscosity at a shear rate of 10 / second after a preheating time of 25 minutes was defined as η25. The ratio of these two values, η5 / η25, was calculated to represent the residence stability of the melt viscosity. A ratio closer to 1 indicates superior residence stability.

[0065] (6) Extrusion moldability Extrusion moldability was evaluated in terms of variations in discharge volume and thickness uniformity. [Extruderability (variation in discharge volume)] The pellets, which had been melted and kneaded in a twin-screw extruder, were then extruded again from a circular die using a single-screw extruder to produce strands with a diameter of 3 mm. From this state, the extrusion moldability (variation in extrusion volume) was evaluated according to the following criteria. ○: No fluctuations in discharge volume, and extrusion properties are stable. △: While stable when being pulled at a constant speed using a pull-up machine, slight fluctuations in discharge volume are observed when it is hanging under its own weight. ×: Discharge volume fluctuates significantly, making collection impossible.

[0066] [Extruderability (Uniformity of Thickness)] Pellets, melt-kneaded in a twin-screw extruder, were then extruded again from a T-die using a single-screw extruder to produce 0.2 mm thick sheet molded products. The thickness uniformity of these sheet molded products was measured using a Mitutoyo Corporation microgauge (model number: ID-C125B, measuring probe: carbide (M2.5×0.45) with a spherical base) compressed air pressure: 0.1 MPa. Measurement points were set at 20 locations in a grid pattern with 90 mm intervals in a 450 mm × 450 mm area in the center of the sheet. Thickness uniformity was determined in two ways: initial and over time. Initial thickness uniformity was determined from the maximum and minimum thickness values ​​measured at 20 locations on the sheet 5 minutes after the start of extrusion molding, according to the following formula. Thickness uniformity over time was determined from the average maximum and average minimum thickness values ​​at 20 locations on each sheet 5 minutes, 30 minutes, and 60 minutes after the start of extrusion molding, according to the following formula. Evaluation was performed according to the following criteria. Furthermore, the uniformity of thickness over time is specifically referred to as "extrusion molding stability." Thickness uniformity = (maximum value - minimum value) / {(maximum value + minimum value) / 2} × 100 (%) ○: Thickness uniformity is less than 1% △: Thickness uniformity is less than 1% to 3% ×: Thickness uniformity is 3% or more

[0067] (7) Flame retardant A thermoplastic polyester elastomer, dried under reduced pressure at 100°C for 8 hours, was mixed with 0.5% by mass of pentaerythrityl-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 0.3% by mass of pentaerythritol tetrakis-(3-laurylthiopropionate), 0.5% by mass of 2-(3-t-butyl-5-methyl-2-hydroxyphenyl)benzotriazole, 0.5% by mass of bisphenol A, 0.3% by mass of triphenylphosphine, and the compounds described in the Examples and Comparative Examples. The mixture was then granulated using an extruder to obtain a flame-retardant polyester elastomer resin composition. The above thermoplastic polyester elastomer composition was injection molded into 1 / 32-inch test specimens conforming to UL-94 standards using an injection molding machine (Yamashiro Seiki Co., Ltd., model-SAV) at a cylinder temperature (Tm + 20°C). The flame retardancy of the test specimens obtained by the above method was evaluated in accordance with UL-94. Burn time is shown as the sum of the burn times after two exposures to flame for each of the five samples.

[0068] (8) Heat resistance / heat aging resistance Dumbbell-shaped test specimens (Type 3) were left at 170°C for an arbitrary period of time, then removed, and their tensile elongation at break was measured in accordance with JIS K6251:2010. The retention rate of tensile elongation at break was calculated according to the following formula, and the time it took for this value to become 50% (tensile elongation half-life) was used as an indicator of heat resistance and heat aging resistance. Note that the initial tensile elongation at break is the tensile elongation at break before the heat resistance and heat aging resistance test. Tensile elongation retention rate (%) = Tensile elongation after heat resistance and heat aging test / Initial tensile elongation × 100 ○: Tensile elongation half-life of 800 hours or more △: Tensile elongation half-life is less than 400-800 hours ×: Tensile elongation half-life is less than 400 hours The aforementioned dumbbell-shaped test specimen No. 3 was created by injection molding a resin, which had been dried under reduced pressure at 100°C for 8 hours, into a 100mm x 100mm x 2mm flat plate using an injection molding machine (Yamashiro Seiki Co., Ltd., model-SAV) at a cylinder temperature of Tm + 20°C and a mold temperature of 30°C. The dumbbell-shaped test specimen No. 3 was then punched out from this flat plate.

[0069] The ingredients used in the examples and comparative examples are as follows: [Thermoplastic polyester elastomer] Four types of thermoplastic polyester elastomers, A-1 to A-4, were synthesized. Thermoplastic polyester elastomer A-1: 100 parts by mass of aliphatic polycarbonate diol (UH-CARB200, manufactured by Ube Industries, Ltd., number average molecular weight 2000, 1,6-hexanediol type) and 8.6 parts by mass of diphenyl carbonate were charged and reacted at a temperature of 205°C and 130 Pa. After 2 hours, the contents were cooled to obtain an aliphatic polycarbonate diol with increased molecular weight (number average molecular weight 10000). 43 parts by mass of this aliphatic polycarbonate diol (PCD) and 57 parts by mass of polybutylene terephthalate (PBT) having a number average molecular weight of 30000 were stirred at 230°C to 245°C and 130 Pa for 1 hour. After confirming that the resin had become transparent, the contents were removed and cooled to obtain thermoplastic polyester elastomer A-1. The thermoplastic polyester elastomer A-1 had a melting point of 207°C, a reduced viscosity of 1.21 dl / g, and an acid value of 44 eq / ton. The composition and properties of the obtained thermoplastic polyester elastomer A-1 are shown in Table 1.

[0070] Thermoplastic polyester elastomer A-2: Thermoplastic polyester elastomer A-2 was synthesized in the same manner as thermoplastic polyester elastomer A-1, except that trimethylolpropane was copolymerized to impart branching. Specifically, 100 parts by mass of aliphatic polycarbonate diol (UH-CARB200, manufactured by Ube Industries, Ltd., number average molecular weight 2000, 1,6-hexanediol type) and 8.6 parts by mass of diphenyl carbonate were charged and reacted at a temperature of 205°C and 130 Pa. After 2 hours, the contents were cooled to obtain an aliphatic polycarbonate diol with increased molecular weight (number average molecular weight 10000). 43 parts by mass of aliphatic polycarbonate diol (PCD), 57 parts by mass of polybutylene terephthalate (PBT) having a number average molecular weight of 30,000, and 0.0005 parts by mass of trimethylolpropane for branching were stirred at 230°C to 245°C under 130 Pa for 1 hour. After confirming that the resin had become transparent, the contents were removed and cooled to obtain thermoplastic polyester elastomer A-2. The melting point of thermoplastic polyester elastomer A-2 was 214°C, the reduced viscosity was 1.38 dl / g, and the acid value was 39 eq / ton. The composition and physical properties of the obtained thermoplastic polyester elastomer A-2 are shown in Table 1.

[0071] Thermoplastic polyester elastomer A-3: For comparative purposes, a thermoplastic polyester elastomer A-3 was synthesized in which the soft segment was an aliphatic polyether rather than an aliphatic polycarbonate. Specifically, using the same method as described above, thermoplastic polyester elastomer A-3 was obtained with terephthalic acid, 1,4-butanediol, and polyoxytetramethylene glycol (PTMG; number average molecular weight 1000) as constituent components, and with a hard segment (polybutylene terephthalate) / soft segment (PTMG) ratio of 56 / 44 (mass%). The melting point of this thermoplastic polyester elastomer A-3 was 203°C, the reduced viscosity was 1.75 dl / g, and the acid value was 50 eq / ton. The composition and physical properties of the obtained thermoplastic polyester elastomer A-3 are shown in Table 1.

[0072] Thermoplastic polyester elastomer A-4: Thermoplastic polyester elastomer A-4 was synthesized in the same manner as thermoplastic polyester elastomer A-1, except that the molecular weight increase rate of the aliphatic polycarbonate diol was increased. Specifically, 100 parts by mass of aliphatic polycarbonate diol (UH-CARB200, manufactured by Ube Industries, Ltd., number average molecular weight 2000, 1,6-hexanediol type) and 9.6 parts by mass of diphenyl carbonate were charged and reacted at a temperature of 205°C and 130 Pa. After 2 hours, the contents were cooled to obtain an aliphatic polycarbonate diol with increased molecular weight (number average molecular weight 20000). 43 parts by mass of this aliphatic polycarbonate diol (PCD) and 57 parts by mass of polybutylene terephthalate (PBT) having a number average molecular weight of 30,000 were stirred at 230°C to 245°C under 130 Pa for 1 hour. After confirming that the resin had become transparent, the contents were removed and cooled to obtain thermoplastic polyester elastomer A-4. The melting point of this thermoplastic polyester elastomer A-4 was 207°C, the reduced viscosity was 1.25 dl / g, and the acid value was 49 eq / ton. The composition and physical properties of the obtained thermoplastic polyester elastomer A-4 are shown in Table 1.

[0073] [Table 1]

[0074] [Reactive compounds] B-1: Alicyclic polycarbodiimide (Carbodilite HMV-15CA, manufactured by Nisshinbo Chemical Co., Ltd.) B-2: Triglycidyl isocyanurate compound (TEPIC-S, manufactured by Nissan Chemical Corporation, epoxy valency (average number of epoxy groups per molecule): 3) B-3: Styrene / glycidyl acrylate copolymer (ARUFON UG-4050, manufactured by Toagosei Co., Ltd., Mw: 8500, epoxy value: 670 equivalents / 1×10⁻⁶) 6 g) B-4: Epoxy group-containing olefin copolymer (Bondfast BF-7M, manufactured by Sumitomo Chemical Co., Ltd., epoxy value: 0.4 meq / g)

[0075] [Flame retardant] C-1: Brominated polystyrene (PDBS-80, manufactured by Lanxess) C-2: Antimony trioxide (PATOX MK, manufactured by Nippon Seikou Co., Ltd.)

[0076] [Other additives] D-1: Release agent Ricowax E (manufactured by Clariant Japan Co., Ltd.) 0.2 parts by weight D-2: Hindered phenol antioxidant Irganox 1010 (BASF) 0.5 parts by weight D-3: Hindered phenol antioxidant Irganox 1098 (BASF) 0.2 parts by weight D-4: Aromatic amine antioxidant Nonflex DCD (manufactured by Seiko Chemical Co., Ltd.) 0.8 parts by weight D-5: Sulfur-based antioxidant Rasmit LG (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 0.2 parts by weight

[0077] [Examples 1-10, Comparative Examples 1-7] The thermoplastic polyester elastomer, reactive compound, flame retardant, and other additives were mixed according to the mixing ratios and reactive compound addition methods shown in Table 2 to obtain a thermoplastic polyester elastomer resin composition. The numerical values ​​indicating the mixing ratios in Table 2 represent parts by mass. The performance of the obtained thermoplastic polyester elastomer resin composition was evaluated. The results are shown in Table 2. Details of the reactive compound addition methods (Method A and Method B) in Table 2 are as follows. Method A: A reactive compound was impregnated into 3 parts by mass of thermoplastic polyester elastomer and introduced into the molten resin composition from a side feeder. Method B: The reactive compound was pre-mixed with other components and then added all at once from a hopper.

[0078] [Table 2]

[0079] As can be seen from Table 2, Examples 1 to 10, which satisfy the requirements of the present invention, all exhibited minimal fluctuation in the discharge volume during extrusion molding, excellent initial thickness uniformity, and superior extrusion moldability. They also exhibited excellent thickness uniformity over time and superior extrusion molding stability. Furthermore, they possessed excellent heat resistance and heat aging resistance, which are fundamental performance requirements for thermoplastic polyester elastomers. In particular, Example 9 exhibited stable extrusion moldability, extrusion molding stability, and heat resistance / heat aging resistance despite the addition of a flame retardant. In contrast, Comparative Example 1, although having the same blending ratio of the reactive compound as Example 1, was introduced all at once with the other components. As a result, the end groups of the thermoplastic polyester elastomer could not be sufficiently sealed by the reactive compound, the acid value could not be sufficiently reduced, and the retention stability of the melt viscosity was poor. Consequently, the viscosity increased over time, causing the thickness to fluctuate, and the extrusion molding stability was poor. It also exhibited poor heat resistance and heat aging resistance. Comparative Example 2 contained an excessive amount of the reactive compound, resulting in residual unreacted reactive compound, which caused gelation and increased viscosity. This led to unstable melt viscosity and unstable extrusion moldability from the initial stages of molding. Furthermore, because the reactive compound was added together with other components, localized thickening was more likely to occur, resulting in poor retention stability of the melt viscosity. Consequently, the thickness fluctuated over time due to increased viscosity, resulting in poor extrusion molding stability. Comparative Example 3 did not contain polycarbodiimide (B-1), which is excellent at reducing the acid value, as a reactive compound. As a result, it was unable to sufficiently reduce the acid value and had poor heat resistance and heat aging resistance. Furthermore, because the glycidyl compound (B-3) used as a reactive compound increased in viscosity over time, this was offset by the deterioration of the retention stability of the melt viscosity due to the high acid value. Although the retention stability of the melt viscosity was close to 1 and the apparent range of melt viscosity fluctuation was not large, the thickness fluctuated over time, resulting in poor extrusion molding stability. Comparative Example 4 contained almost no polycarbodiimide (B-1), which is excellent at reducing the acid value, as a reactive compound. Therefore, despite being similar to Example 1 in other respects, it was unable to sufficiently reduce the acid value and exhibited inferior heat resistance and heat aging resistance. Furthermore, because the glycidyl compound (B-2) used as a reactive compound increased in viscosity over time, this was offset by the deterioration of the retention stability of the melt viscosity due to the high acid value. As a result, the retention stability of the melt viscosity was close to 1, and the apparent range of melt viscosity fluctuation was not large. However, the thickness fluctuated over time due to the increase in viscosity, resulting in poor extrusion molding stability. Comparative Example 5, due to the large amount of polyfunctional epoxy compound (B-3) added, resulted in a thermoplastic polyester elastomer with a high molecular weight and many branches. Consequently, it had a high melt viscosity at high shear rates and poor thickness uniformity in the initial stages of molding. Although Comparative Example 6, like Example 3, used a non-branched thermoplastic polyester elastomer, unlike Example 3, it did not contain the trifunctional epoxy compound (B-2). As a result, it had low melt viscosity at low shear rates, poor shape retention, unstable thickness over time, and poor extrusion moldability. Comparative Example 7, despite being otherwise similar to Example 1, had inferior resistance to heat aging because its soft segment was an aliphatic polyether rather than an aliphatic polycarbonate. [Industrial applicability]

[0080] The thermoplastic polyester elastomer of the present invention satisfies the basic performance requirements for automotive and home appliance parts, such as heat resistance, weather resistance, heat aging resistance, water resistance, and low-temperature properties, while also exhibiting excellent extrusion moldability and extrusion stability. Therefore, it enables the stable long-length hollow molded products, such as cables and hoses, which require uniform thickness, to be produced over long periods of time. Accordingly, the present invention will greatly contribute to the relevant industry.

Claims

1. A thermoplastic polyester elastomer comprising a hard segment made of a polyester composed of an aromatic dicarboxylic acid and an aliphatic or alicyclic diol, and a soft segment mainly made of an aliphatic polycarbonate, wherein at least a portion of the terminal groups are sealed with a reactive compound, and the reactive compound contains polycarbodiimide, The acid value of the thermoplastic polyester elastomer is 15 eq / ton or less. A thermoplastic polyester elastomer characterized by satisfying the following conditions (i) and (ii) when its melt viscosity is measured at 230°C in accordance with JIS K7199: (i) The melt viscosity at a shear rate of 10 / second with a preheating time of 5 minutes is 1800 Pa·s or more, and the melt viscosity at a shear rate of 1000 / second with a preheating time of 5 minutes is 800 Pa·s or less; (ii) The ratio of melt viscosity at a shear rate of 10 / second measured with a preheating time of 5 minutes and a preheating time of 25 minutes is 0.7 to 1.

3.

2. The thermoplastic polyester elastomer according to claim 1, further comprising a reactive compound having at least one functional group selected from the group consisting of a glycidyl group, an acid anhydride group, and an isocyanate group.

3. A resin composition characterized by containing the thermoplastic polyester elastomer described in claim 1 or 2 and a flame retardant.

4. A molded article characterized by being obtained by extruding a thermoplastic polyester elastomer according to claim 1 or 2 or a resin composition according to claim 3.

5. The molded article according to claim 4, characterized in that the molded article is a cable or a hose.

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