Flame-retardant thermoplastic polyester elastomer resin compositions, and molded articles obtained therefrom.

Abstract

Provided is a flame-retardant thermoplastic polyester elastomer resin composition which is excellent especially in terms of extrusion moldability and from which hollow continuous molded articles can be produced in even thicknesses with high accuracy. This resin composition comprises: 50-94 mass% thermoplastic polyester elastomer that 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 consisting mainly of an aliphatic polycarbonate and that has terminal groups, at least some of which have been blocked with polycarbodiimide; and 1-45 mass% flame retardant. The resin composition has a melt flow rate (MFR) of 2-15 g / 10 min, and the difference between the MFR measured at 35 minutes after introduction of the resin composition and the MFR measured at 5 minutes after the introduction is 0-20 g / 10 min.

Description

Technical Field

[0004]

[0001] The present invention relates to a flame-retardant thermoplastic polyester elastomer resin composition excellent in heat resistance, weather resistance, heat aging resistance, water resistance, low-temperature characteristics, etc., and in addition, excellent in molding processability, particularly extrusion moldability, and a molded article 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 in 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 an ultra-high temperature 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 constituent resins of cables. However, vinyl chloride resins and olefin resins have problems of low melting points and poor heat resistance. Further, although polyester resins have a relatively high melting point, 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 put into practical use (for example, see Patent Documents 1 and 2). <00000​​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 with improved heat and water resistance have been proposed by using aliphatic carbonates in the soft segments (see Patent Document 3). Furthermore, flame-retardant elastomer resin compositions have been proposed by blending various flame retardants with such thermoplastic polyester elastomers (see Patent Document 4). In addition, flame-retardant elastomer resin compositions with improved water resistance have been proposed by blending carbodiimide in addition to flame retardants (see Patent Document 5).

[0007] However, the resin composition described in Patent Document 4 had the problem of reduced melt viscosity due to the inclusion of a flame retardant. Furthermore, the resin composition described in Patent Document 5 was prone to increased viscosity due to the carbodiimide residue, and since both a flame retardant and carbodiimide were included, the decrease in melt viscosity and the increased viscosity effect of both were not offset, but rather the increase in viscosity became significant. Consequently, controlling the melt viscosity was extremely difficult, making it difficult to produce hollow, long molded products such as cables and hoses with a uniform thickness. [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 [Patent Document 4] Japanese Patent Publication No. 2008-308635 [Patent Document 5] Patent No. 5481916 [Overview of the project] [Problems that the invention aims to solve]

[0009] The present invention was devised to overcome the problems of the above-mentioned conventional flame-retardant thermoplastic polyester elastomer resin compositions, and its objective is to provide a flame-retardant thermoplastic polyester elastomer resin composition that not only exhibits excellent heat resistance, weather resistance, heat aging resistance, water resistance, and low-temperature properties, but also has excellent extrusion moldability, enabling the production of hollow, long molded products such as cables and hoses with uniform thickness and high precision. [Means for solving the problem]

[0010] To achieve the above objective, the inventors diligently investigated methods to prevent the problem of viscosity increase during extrusion molding in resin compositions that further incorporate a flame retardant and polycarbodiimide into conventional thermoplastic polyester elastomers, particularly those using aliphatic carbonates in the soft segment. As a result, they found that the extrusion moldability can be improved by suitably controlling the melt flow rate (MFR) and its change over time (ΔMFR) of the thermoplastic polyester elastomer resin composition within specific ranges.

[0011] The present invention was completed based on the above findings and has the following configurations (1) to (5). (1) A flame-retardant thermoplastic polyester elastomer resin composition comprising 60-84% by mass of a thermoplastic polyester elastomer having hard segments and soft segments bonded together, wherein at least a portion of the terminal groups are encapsulated with polycarbodiimide; and 11-35% by mass of a flame retardant, More than 80% by mass of the aforementioned soft segment is made of aliphatic polycarbonate. The melt flow rate (MFR) of the aforementioned flame-retardant thermoplastic polyester elastomer resin composition, when measured at 230°C and a load of 2.16 kg in accordance with the thermoplastic flow test method specified in JIS K7210, is: 2 A flame-retardant thermoplastic polyester elastomer resin composition characterized by having a load of approximately 15 g / 10 minutes, a difference (ΔMFR: MFR35-MFR5) between the MFR value after 35 minutes (MFR35) and the MFR value after 5 minutes (MFR5) being 0 to 20 g / 10 minutes, and an initial elongation at break of the flame-retardant thermoplastic polyester elastomer resin composition of 350% or more. (2) The flame-retardant thermoplastic polyester elastomer resin composition according to (1), characterized in that when a thermoplastic polyester elastomer is heated from room temperature to 300°C at a heating rate of 20°C / min using a differential scanning calorimeter, held at 300°C for 3 minutes, and then cooled to room temperature at a cooling rate of 100°C / min, the difference in melting points (Tm1-Tm3) between the melting point (Tm1) obtained in the first measurement and the melting point (Tm3) obtained in the third measurement is 0 to 50°C. (3) The flame-retardant thermoplastic polyester elastomer resin composition according to either (1) or (2), characterized in that the acid value is 15 eq / ton or less. (4) A molded article characterized by being obtained by extruding a flame-retardant thermoplastic polyester elastomer resin composition described in any of (1) to (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 flame-retardant thermoplastic polyester elastomer resin composition 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, and also exhibits excellent extrusion moldability. Therefore, it is possible to produce long, hollow molded products such as cables and hoses, which require uniform thickness, with high precision. [Modes for carrying out the invention]

[0013] The flame-retardant thermoplastic polyester elastomer resin composition of the present invention is based on a thermoplastic polyester elastomer in which a hard segment made of polyester composed of an aromatic dicarboxylic acid and an aliphatic or alicyclic diol is bonded to a soft segment mainly made of aliphatic polycarbonate, and a flame retardant is blended into the elastomer in which at least a portion of the terminal groups are sealed with polycarbodiimide, and is characterized by having a specific range of melt flow rate (MFR) and its change over time (ΔMFR).

[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] In addition, 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 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 that constitutes 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 that constitutes 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 its melting point decreases or becomes amorphous, so 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 the thermoplastic polyester elastomer used in this invention, it is important that the melting point difference (Tm1-Tm3) between the melting point (Tm1) obtained in the first measurement and the melting point (Tm3) obtained in the third measurement is between 0 and 50°C. This is achieved by using a differential scanning calorimeter to raise the temperature from room temperature to 300°C at a heating rate of 20°C / min, holding it at 300°C for 3 minutes, and then lowering it to room temperature at a cooling rate of 100°C / min, repeating this cycle three times. A melting point difference of 0 to 40°C is more preferable, and 0 to 30°C is even more preferable. This melting point difference is a measure of the blockability retention of the thermoplastic polyester elastomer; the smaller the temperature difference, the better the blockability retention. If the melting point difference exceeds 50°C, the blockability retention deteriorates, leading to greater quality variation during molding and resulting in poorer uniformity of molded product quality and reduced recyclability.

[0034] By satisfying the above characteristics, it is possible to obtain molded products that effectively utilize the excellent blocking properties of thermoplastic polyester elastomers.

[0035] While there are no limitations on the method for achieving the above-mentioned blocking properties and blocking characteristics of a thermoplastic polyester elastomer, it is preferable to optimize the molecular weight of the polycarbonate diol used as the raw material. Specifically, it is preferable to produce the thermoplastic polyester elastomer by reacting a polyester constituting the hard segment with an aliphatic polycarbonate diol having a molecular weight of 5,000 to 80,000 in a molten state. The larger the molecular weight of the aliphatic polycarbonate diol, the higher the blocking properties and blocking characteristics. The molecular weight of the aliphatic polycarbonate diol is preferably 5,000 or more in number average molecular weight, more preferably 7,000 or more, and even more preferably 10,000 or more. From the viewpoint of compatibility between the hard segment and the soft segment, the upper limit of the molecular weight of the aliphatic polycarbonate diol is preferably 80,000 or less, more preferably 70,000 or less, and even more preferably 60,000 or less. If the molecular weight of the aliphatic polycarbonate diol is too high, its compatibility decreases, leading to phase separation. This significantly affects the mechanical properties of the molded product, reducing its strength and elongation.

[0036] There are no limitations on the method for optimizing the molecular weight of aliphatic polycarbonate diols. You may purchase or prepare a diol with the optimal molecular weight, or you may use a diol whose molecular weight has been adjusted beforehand by increasing the molecular weight of a low-molecular-weight aliphatic polycarbonate diol with a chain extender such as diphenyl carbonate or diisocyanate.

[0037] For example, the above-mentioned high molecular weight aliphatic polycarbonate diol can be produced by reacting the aforementioned aliphatic diol with one of the following carbonates: dimethyl carbonate, diethyl carbonate, dipropyl carbonate, diisopropyl carbonate, dibutyl carbonate, dimethyl carbonate, diphenyl carbonate, etc.

[0038] Another method for producing high molecular weight aliphatic polycarbonate diols is to react low molecular weight aliphatic polycarbonate diols with dimethyl carbonate, diethyl carbonate, dipropyl carbonate, diisopropyl carbonate, dibutyl carbonate, dimethyl carbonate, diphenyl carbonate, and the like.

[0039] In this invention, the thermoplastic polyester elastomer is in a state in which at least a portion of its end groups are sealed with polycarbodiimide. 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 (hydroxyl groups or carboxyl groups) of the thermoplastic polyester elastomer with reactive functional groups in polycarbodiimide, it is possible to increase the molecular weight / introduce branching of the thermoplastic polyester elastomer, effectively reduce the acid value of the thermoplastic polyester elastomer, and control the MFR, ΔMFR, extrudeability, heat resistance, and heat aging resistance of the thermoplastic polyester elastomer resin composition.

[0040] In this invention, "at least a portion of the end groups of the thermoplastic polyester elastomer are sealed with polycarbodiimide" means that it is not required that "all" of the end groups of the thermoplastic polyester elastomer be sealed with polycarbodiimide. This invention assumes a state in which "almost" of the end groups of the thermoplastic polyester elastomer are sealed with polycarbodiimide, and also includes the state of a composition in which free polycarbodiimide is present. This is because it is difficult to seal "all" of the end groups of the thermoplastic polyester elastomer with polycarbodiimide, even if polycarbodiimide 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.

[0041] In the present invention, polycarbodiimide plays a role in controlling the MFR of the thermoplastic polyester elastomer resin composition to a suitable range by sealing the end groups of the thermoplastic polyester elastomer to impart branching to the thermoplastic polyester elastomer or increasing the molecular weight of the thermoplastic polyester elastomer, and also plays a role in controlling the ΔMFR of the thermoplastic polyester elastomer resin composition to a suitable range by lowering its acid value by sealing the end groups of the thermoplastic polyester elastomer, thereby improving the extrudeability, heat resistance, and heat aging resistance of the thermoplastic polyester elastomer resin composition. The polycarbodiimide that can be used in the present invention is any polycarbodiimide having two or more carbodiimide groups (-N=C=N- structure) in one molecule, such as aliphatic polycarbodiimide, alicyclic polycarbodiimide, aromatic polycarbodiimide, and copolymers thereof. Preferably, it is aliphatic polycarbodiimide or alicyclic polycarbodiimide.

[0042] 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.

[0043] 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).

[0044] 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 (i.e., the number of carbodiimide groups) 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 in an amine and performing back titration with hydrochloric acid). At these degrees of polymerization, if the material is solid at around room temperature, it offers excellent workability and compatibility when powdered and mixed with thermoplastic polyester elastomers, and is also preferable in terms of uniform reactivity and bleed-out resistance.

[0045] The thermoplastic polyester elastomer used in this invention may have some of its terminal groups encapsulated with a compound having one or more reactive groups for thermoplastic polyester elastomers, in addition to polycarbodiimide. Such reactive groups are groups that can react with the hydroxyl groups and carboxyl groups of the thermoplastic polyester elastomer, such as epoxy groups, oxazoline groups, carbodiimide groups, acid anhydrides, hydroxymethyl groups, amino groups, and cyclic imino groups. Hereinafter, polycarbodiimide and compounds having one or more reactive groups for thermoplastic polyester elastomers will be collectively referred to as "reactive compounds."

[0046] When a compound having one or more reactive groups for thermoplastic polyester elastomers is an epoxy compound, its structure is not particularly limited, but it is a compound having one or more epoxy groups in the same cell, and a compound having two to three epoxy groups is preferred. Specific examples of epoxy compounds include diglycidyl ethers of bisphenol A, bisphenol F, and bisphenol S, and their oligomers; diglycidyl ethers of hydrogenated bisphenol A, hydrogenated bisphenol F, and hydrogenated bisphenol S, and their oligomers; diglycidyl orthophthalate; diglycidyl isophthalate; diglycidyl terephthalate; diglycidyl p-oxybenzoate; diglycidyl tetrahydrophthalate; diglycidyl hexahydrophthalate; diglycidyl succinate; diglycidyl adipicate; diglycidyl sebacate; ethylene glycol diglycidyl ether; propylene glycol diglycidyl ether; 1,4-butanediol glycidyl ether; and 1,6-hexanediol diglycidyl ether. Examples include polyalkylene glycol diglycidyl ethers, trimellitic acid triglycidyl esters, triglycidyl isocyanurates, 14-diglycidyloxybenzene, diglycidylpropylene urea, glycerol triglycidyl ether, trimethylolethane triglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, polyglycidyl ethers of glycerol alkylene oxide adducts, glycidyl ether type epoxies such as cresol novolac type glycidyl ether and phenol novolac type glycidyl ether, alicyclic epoxies such as 3,4-epoxycyclohexyl methacrylate and cyclopentadiene diepoxide, oligomeric type alicyclic epoxies, and triglycidyl isocyanurates, which may be mixed as needed. Among these, those that are crystalline and can be powdered are preferred in terms of homogenizing the reaction and preventing gel formation. Particularly preferred examples include triglycidyl isocyanurate, and powders with an average particle size of 100 μm or less are preferred.

[0047] Next, a method for occluding end groups using reactive compounds such as polycarbodiimide 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.

[0048] 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 mechanical properties, heat resistance, and melt viscosity may decrease. Also, if it is below the above lower limit, the amount of -N=C=N- in the thermoplastic polyester elastomer will decrease, which may result in inferior effects on improving hydrolysis resistance and extrusion moldability. When the reactive compound is a compound having one or more reactive groups for thermoplastic polyester elastomer, the amount blended is preferably 0.01 to 5 parts by mass, more preferably 0.05 to 4 parts by mass, per 100 parts by mass of thermoplastic polyester elastomer. If it is below the above lower limit, the effects obtained by reacting such a compound, such as the effect of improving moldability due to thickening, and the effect of improving heat resistance and hydrolysis resistance, may not be significantly exhibited. Furthermore, exceeding the above upper limit may result in unreacted compounds remaining, leading to adverse effects on the quality of the molded product, such as rough surface texture and the formation of gels.

[0049] Furthermore, in order to ensure that the reactive compounds, such as polycarbodiimide, 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 compounds to the thermoplastic polyester elastomer. For example, instead of simultaneously mixing the thermoplastic polyester elastomer, the reactive compounds, and additives such as flame retardants described later, as in the conventional method, the reactive compounds can be pre-attached to a portion of the thermoplastic polyester elastomer, while the remaining thermoplastic polyester elastomer and additives can be mixed and melted. Adding the thermoplastic polyester elastomer with the reactive compounds attached to this molten mixture allows for uniform melting and kneading of the reactive compounds, ensuring that the reactive compounds can reliably come into contact with and react with the end groups of the thermoplastic polyester elastomer. As a result, excessive polycarbodiimide can be suppressed, and adjustment to the desired MFR and ΔMFR becomes easier. If the reactive compounds are 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 extrusion molding. Specifically, the presence of unsealed thermoplastic polyester elastomers can lead to thermal decomposition and hydrolysis during prolonged extrusion molding, potentially resulting in a decrease in molecular weight and melt viscosity. Furthermore, the presence of unreacted reactive compounds can cause gelation, potentially increasing the melt viscosity.

[0050] 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 increase in ΔMFR can be suppressed, 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 hydrolysis resistance, and when the acid value is within the above range, hydrolysis resistance is excellent.

[0051] In this invention, the end-group-sealed thermoplastic polyester elastomer is used in combination with a flame retardant in the form of a flame-retardant resin composition. 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 in an amount of 1 to 40% by mass.

[0052] 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.

[0053] In the resin composition of the present invention, the blending ratio of end-group sealed thermoplastic polyester elastomer to flame retardant must be 1 to 45% by mass of flame retardant to 50 to 94% by mass of end-group sealed thermoplastic polyester elastomer, preferably 11 to 35% by mass of flame retardant to 60 to 84% by mass of end-group sealed thermoplastic polyester elastomer. If the blending ratio of end-group sealed thermoplastic polyester elastomer is below the above lower limit, the heat resistance and other properties may be inferior. On the other hand, if the blending ratio of end-group sealed thermoplastic polyester elastomer exceeds the above upper limit, the blending ratio of flame retardant may be too low, resulting in inferior flame retardancy.

[0054] Furthermore, the resin composition of the present invention may contain various additives 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. The total amount of these additives in the resin composition is preferably 0 to 5% by mass, and more preferably 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 flame-retardant polyester elastomer resin composition of the present invention preferably has a melt flow rate (MFR) value of 2 to 15 g / 10 min, and more preferably 2 g to 12 g / 10 min or less, when measured at 230°C and a load of 2.16 kg in accordance with the thermoplastic flow test method specified in JIS K7210. If the MFR value is less than 2 g / 10 min or more than 15 g / 10 min, extrusion molding becomes impossible. Furthermore, the difference between the MFR value after 35 minutes (MFR35) and the MFR value after 5 minutes (MFR5) after adding the resin composition (ΔMFR: MFR35-MFR5) is preferably 0 to 20, and more preferably 0 to 15. If ΔMFR is greater than 20, the decrease in melt viscosity during molding is not suppressed, making stable extrusion molding impossible, and resulting in uneven thickness when molding cables or hoses. On the other hand, if it is less than 0, the melt viscosity increases significantly during molding, and similarly, stable moldability cannot be obtained.

[0059] The method for adjusting the MFR value and ΔMFR within the above range is not particularly limited, but it is especially preferable to blend a predetermined amount of a reactive compound such as polycarbodiimide in a specific manner, as described above. This makes it possible to control the acid value of the polyester elastomer resin composition within a predetermined range and adjust the MFR value and ΔMFR within the above range. In addition, the MFR value and ΔMFR can be appropriately adjusted according to the acid value of the polyester elastomer, the number of reactive groups of the reactive compound, the viscosity-enhancing properties such as molecular weight, the increase in acid value due to the decomposition reaction of the polyester elastomer by the flame retardant, and the reactivity with other additives. When epoxy compounds (glycidyl compounds) are used in combination with polycarbodiimide as the reactive compound, unreacted reactive compounds tend to remain in the resin composition. These unreacted reactive compounds react with the polyester elastomer during molding, increasing the molecular weight and contributing to a decrease in MFR and ΔMFR. On the other hand, the presence of unreacted reactive compounds can reduce long-term extrusion moldability, such as by increasing the difference between the initial thickness and the final thickness.

[0060] The flame-retardant resin composition containing the end-group sealed thermoplastic polyester elastomer of the present invention, as described above, 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. Therefore, it can be used to produce hollow, long molded products such as cables and hoses with a uniform thickness by extrusion molding. [Examples]

[0061] 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.

[0062] (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.

[0063] (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.

[0064] (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.

[0065] (4) Meltflow rate (abbreviation: MFR, also called meltflow index) The melt flow rate (MFR: g / 10 min) of the pellets of the flame-retardant thermoplastic polyester elastomer resin compositions obtained in the examples and comparative examples was measured at 230°C and under a load of 2.16 kg, in accordance with the test method (Method A) described in JIS K7210 (ASTM D1238). Resin compositions with a moisture content of 0.1% by weight or less were used for the measurement. In addition, the difference (ΔMFR: MFR35-MFR5) between the MFR value after 35 minutes (MFR35) and the MFR value after 5 minutes (MFR5) was measured. Resin compositions with a moisture content of 0.1 parts by weight or less were used for the measurement.

[0066] (5) Extrusion moldability Extrusion moldability was evaluated in terms of discharge volume variation and smoothness. [Extruderability (variation in discharge volume)] The pellets, which had been melt-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.

[0067] [Extruderability (smoothness)] 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 smoothness of the extruded products was evaluated from the appearance of the sheets according to the following criteria. ○: No roughness or foaming occurs, and the sheet appearance and surface smoothness are excellent. ×: Sheet irregularities (melt fracture) and foaming occur, resulting in an unsatisfactory appearance.

[0068] (6) 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.

[0069] (7) Heat resistance / heat aging resistance As test pieces, a 100mm x 100mm x 2mm flat plate was injection molded 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. Dumbbell-shaped test pieces (Type 3) were then punched out from the flat plate. These dumbbell-shaped test pieces were left in a 170°C environment for an arbitrary period of time, then removed, and the tensile elongation at break was measured in accordance with JIS K6251:2010. The tensile elongation retention rate was calculated according to the following formula, and the time at which this value became 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

[0070] (8) Tensile breaking strength and tensile breaking elongation of flame-retardant thermoplastic polyester elastomer resin composition Measurements were taken in accordance with JIS K 6251. Test pieces were injection molded 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℃ and a mold temperature of 30℃. After injection molding, dumbbell-shaped test pieces (type 3) were punched out from the flat plate.

[0071] The ingredients used in the examples and comparative examples are as follows: [Thermoplastic polyester elastomer] Three types of thermoplastic polyester elastomers, A-1 to A-3, 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 differential melting point of 20°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.

[0072] Thermoplastic polyester elastomer A-2: For comparative purposes, a thermoplastic polyester elastomer A-2 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-2 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-2 was 203°C, the differential melting point was 8°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-2 are shown in Table 1.

[0073] Thermoplastic polyester elastomer A-3: Thermoplastic polyester elastomer A-3 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-3. The melting point of thermoplastic polyester elastomer A-3 was 207°C, the differential melting point was 55°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-3 are shown in Table 1.

[0074] [Table 1]

[0075] [Polycarbodiimide] B-1: Alicyclic polycarbodiimide (Carbodilite HMV-15CA, manufactured by Nisshinbo Chemical Co., Ltd.) B-2: Aromatic polycarbodiimide (Stabaxol P, manufactured by Rhein Chemie Rheinau GmbH)

[0076] [Glycidyl compounds] B'-1: Triglycidyl isocyanurate compound (TEPIC-S, manufactured by Nissan Chemical Corporation, epoxy valency (average number of epoxy groups per molecule): 3)

[0077] [Flame retardant] C-1: Brominated polystyrene (PDBS-80, manufactured by Lanxess) C-2: Antimony trioxide (PATOX MK, manufactured by Nippon Seikou Co., Ltd.) C-3: Aluminum diethylphosphinate (EXOLIT OP1230, manufactured by Clariant Japan)

[0078] [Examples 1-7, Comparative Examples 1-6] The above-mentioned thermoplastic polyester elastomer, polycarbodiimide, and flame retardant were mixed in the proportions and by the polycarbodiimide addition method shown in Table 2 to obtain a flame-retardant thermoplastic polyester elastomer resin composition. The proportions in Table 2 represent parts by mass. The performance of the obtained flame-retardant thermoplastic polyester elastomer resin composition was evaluated. The results are shown in Table 2. Details of the polycarbodiimide addition methods (Method A and Method B) in Table 2 are as follows. Method A: Polycarbodiimide was impregnated into 3 parts by mass of thermoplastic polyester elastomer and then introduced into the molten resin composition via a side feeder. Method B: Polycarbodiimide was pre-mixed with other components and then added all at once from a hopper.

[0079] [Table 2]

[0080] As can be seen from Table 2, Examples 1 to 7, which satisfy the requirements of the present invention, all exhibited minimal fluctuation in discharge volume during extrusion molding, excellent smoothness, and superior extrusion moldability. They also exhibited excellent flame retardancy. Furthermore, they demonstrated excellent heat resistance, heat aging resistance, and tensile strength and elongation, which are fundamental performance requirements for thermoplastic polyester elastomers. In contrast, in Comparative Example 1, although the proportion of polycarbodiimide was the same as in Example 1, it was added all at once with the other components. As a result, the end groups of the thermoplastic polyester elastomer could not be sufficiently sealed with polycarbodiimide, the acid value could not be sufficiently reduced, and the △MFR became too high. Consequently, it had poor smoothness and poor extrusion moldability. It also had poor heat resistance and heat aging resistance. Comparative Example 2 contained an excessive amount of polycarbodiimide, resulting in residual unreacted polycarbodiimide, which caused gelation and increased viscosity. This led to an excessively low △MFR (Mold Factor Retention), resulting in unstable extrusion moldability from the initial stages of molding. Furthermore, because the polycarbodiimide was added together with other components, localized thickening was more likely to occur despite the excessive polycarbodiimide content, resulting in poor extrusion moldability. Comparative Example 3, lacking any polycarbodiimide (B-1), failed to sufficiently reduce the acid value, resulting in excessively high MFR and ΔMFR. Consequently, extrusion molding was impossible. Comparative Example 4, despite being similar to Example 1 in other respects because it contained almost no polycarbodiimide (B-1), failed to sufficiently reduce the acid value, resulting in an excessively high △MFR. Consequently, it exhibited poor smoothness and poor extrusion moldability. It also had poor heat resistance and heat aging resistance. In Comparative Example 5, gelation occurred due to the excessive inclusion of the polyfunctional glycidyl compound (B'-1), resulting in an excessively low MFR (Metal Fiber Rate). Consequently, extrusion molding was impossible. Comparative Example 6, using a thermoplastic polyester elastomer in which the soft segment is an aliphatic polyether instead of an aliphatic polycarbonate (A-2), exhibited inferior heat resistance and heat aging resistance despite being otherwise similar to Example 1. [Industrial applicability]

[0081] The flame-retardant thermoplastic polyester elastomer resin composition 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. Therefore, it is possible to produce long, hollow molded products such as cables and hoses, which require uniform thickness, with high precision. Accordingly, the present invention will greatly contribute to the relevant industry.

Claims

1. A flame-retardant thermoplastic polyester elastomer resin composition comprising 60 to 84% by mass of a thermoplastic polyester elastomer having hard segments and soft segments bonded together, wherein at least a portion of the terminal groups are encapsulated with polycarbodiimide; and 11 to 35% by mass of a flame retardant, More than 80% by mass of the aforementioned soft segment is made of aliphatic polycarbonate. A flame-retardant thermoplastic polyester elastomer resin composition characterized in that the melt flow rate (MFR) value of the flame-retardant thermoplastic polyester elastomer resin composition is 2 to 15 g / 10 min when measured at 230°C and a load of 2.16 kg in accordance with the thermoplastic flow test method specified in JIS K7210, the difference (ΔMFR: MFR35 - MFR5) between the MFR value after 35 minutes (MFR35) and the MFR value after 5 minutes (MFR5) after the flame-retardant thermoplastic polyester elastomer resin composition is 0 to 20 g / 10 min, and the initial elongation at break of the flame-retardant thermoplastic polyester elastomer resin composition is 350% or more.

2. The flame-retardant thermoplastic polyester elastomer resin composition according to claim 1, characterized in that when a thermoplastic polyester elastomer is heated from room temperature to 300°C at a heating rate of 20°C / min using a differential scanning calorimeter, held at 300°C for 3 minutes, and then cooled to room temperature at a cooling rate of 100°C / min, the difference in melting points (Tm1-Tm3) between the melting point (Tm1) obtained in the first measurement and the melting point (Tm3) obtained in the third measurement is 0 to 50°C.

3. A flame-retardant thermoplastic polyester elastomer resin composition according to either claim 1 or 2, characterized in that the acid value is 15 eq / ton or less.

4. A molded article characterized by being obtained by extruding a flame-retardant thermoplastic polyester elastomer resin composition according to any one of claims 1 to 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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