Resin composition for foam molding comprising biomass resource-derived polyester elastomer

Abstract

To provide a polyester elastomer resin composition capable of maintaining excellent characteristics of a fossil fuel resource-derived polyester elastomer even when a proportion of a biomass resource-derived raw material is increased, and excellent in foam moldability. The polyester elastomer resin composition contains: a biomass resource-derived polyester elastomer in which at least one of the constituent components is derived from a biomass resource; and a heat stabilizer, and is characterized by having a biobased content of 20-100%, having a MFR value at a load of 2.16 kg measured in accordance with the flow test method of a thermoplastic specified in JIS K7210 of 0.5-20 g / 10 min, and having an acid value of 50 eq / ton or less.

Description

Foam molding resin composition using biomass-derived polyester elastomer

[0001] The present invention relates to a resin composition for foam molding that uses a polyester elastomer derived from a biomass resource with a high bio-based content, yet retains the excellent mechanical properties, retention stability, and high-precision moldability of polyester elastomers derived from fossil fuel resources. The foam-molded articles obtained from the resin composition of the present invention are lightweight, have excellent compression recovery, and a high rebound resilience, and can be produced using a simple molding method to produce high-quality foam-molded articles.

[0002] In recent years, concerns about the depletion of fossil fuel resources and the increase in atmospheric carbon dioxide have become global environmental issues, and as a result, efforts are being made to convert various polymers from biomass. As biomass resources are renewable, they are expected to become an important design concept in future polymer development from the perspectives of SDGs and carbon neutrality.

[0003] However, because biomass resource-derived raw materials contain impurities that could not be completely removed during the refining process, increasing the proportion of biomass resource-derived raw materials in an attempt to increase the bio-based content of the polyester elastomer increases the amount of impurities, which in turn inhibits the reaction and prevents the reduced viscosity from increasing, making it difficult to maintain the excellent properties of fossil fuel resource-derived polyester elastomers.

[0004] Furthermore, a large number of factors, such as impurities introduced into biomass-derived raw materials, oligomers generated by polymerization reactions using these materials, by-products, foreign matter, and undesigned polymers, make it difficult for polyester elastomers to demonstrate the excellent molding design precision that they are inherently known for. For example, in a foam molding resin composition based on a fossil fuel-derived polyester elastomer, a thickener is blended with the polyester elastomer to adjust the acid value and MFR to a specific value, thereby achieving good foam moldability and enabling weight reduction through high-expansion foaming, thereby obtaining a resin foam with extremely high rebound resilience and repeated compressive stress (see Patent Document 1).

[0005] However, when biomass-derived polyester elastomers are used as polyester elastomers, the excellent molding design precision inherent to polyester elastomers cannot be achieved due to factors such as the influence of impurities and foreign matter carried in the biomass-derived raw materials, oligomers, by-products, and undesigned polymers generated by the polymerization reaction using them. In particular, compared to fossil fuel-derived polyester elastomers, it is difficult to control the melt flowability, and coarse and open cells tend to form when foamed and molded, resulting in poor rebound resilience and 50% constant displacement repeated compression set of the foamed and molded products.

[0006] In response to this problem, a method has been proposed in which the sulfur atom content and the amount of acid end groups in polyesters made from biomass-derived dicarboxylic acids and / or diols are reduced to prevent a decline in the mechanical properties of the polyester (see Patent Document 2). While this biomass-derived polyester prevents a decline in mechanical properties to some extent, the compounding conditions used are the same as those for fossil-fuel-derived polyesters, so the thickening reaction does not proceed sufficiently and the melt viscosity does not increase, resulting in thermal degradation of the biomass-derived polyester and variations in resin properties.

[0007] Patent No. 7103003 Patent No. 5303237

[0008] The present invention was made in view of the current state of the prior art, and its object is to provide a resin composition that can retain the excellent mechanical properties, retention stability, and high-precision moldability of fossil fuel resource-derived polyester elastomers even when the proportion of biomass resource-derived raw materials used in the polyester elastomer is increased, and that has excellent foam moldability; and a foam molded article obtained from the resin composition that is lightweight, has excellent compression recovery, and has a high rebound resilience.

[0009] As a result of extensive research to achieve this object, the present inventors have found that by adjusting the production conditions of a biomass-derived polyester elastomer resin composition so that its MFR, acid value, etc. fall within predetermined ranges, it is possible to provide a resin composition that retains the excellent mechanical properties, retention stability, and high-precision moldability of fossil-fuel-derived polyester elastomers, while also exhibiting excellent foam moldability. Furthermore, they have found that foam-molded articles made from this resin composition have a high rebound resilience, a low 50% constant repeated compression set, and uniform cell diameters.

[0010] That is, the present invention was completed based on the above findings and comprises the following (1) to (8): (1) A polyester elastomer resin composition for foam molding, comprising a biomass resource-derived polyester elastomer, at least one of whose constituent components is derived from a biomass resource, and a heat stabilizer, wherein the polyester elastomer resin composition has a biobased content of 20 to 100%, an MFR value of the polyester elastomer resin composition at a load of 2.16 kg measured in accordance with the flow test method for thermoplastics specified in JIS K7210 is 0.5 to 20 g / 10 min (measurement temperature: melting point + 20°C) and an acid value of the polyester elastomer resin composition is 50 eq / ton or less. (2) The polyester elastomer resin composition for foam molding according to (1), wherein the biomass resource-derived polyester elastomer is a polyester elastomer having hard segments composed of a polyester having as its constituent components an aromatic dicarboxylic acid and an aliphatic and / or alicyclic diol, and soft segments composed of an aliphatic polyether, wherein the aromatic dicarboxylic acid and the aliphatic and / or alicyclic diol are derived from fossil fuel resources, and the aliphatic polyether is derived from a biomass resource. (3) The polyester elastomer resin composition for foam molding according to (1), wherein the biomass resource-derived aliphatic polyether of the biomass resource-derived polyester elastomer is polytetramethylene ether glycol. (4) The polyester elastomer resin composition for foam molding according to (1), wherein the biomass resource-derived polyester elastomer has a reduced viscosity of 1.2 or more. (5) A polyester elastomer foam molded article obtained from the polyester elastomer resin composition according to any one of (1) to (4), wherein the polyester elastomer foam molded article has a rebound resilience of 60% or more.(6) A polyester elastomer foam molded article obtained from the polyester elastomer resin composition according to any one of (1) to (4), wherein the polyester elastomer foam molded article has a 50% constant strain repeated compression residual strain of 10% or less. (7) A polyester elastomer foam molded article obtained from the polyester elastomer resin composition according to any one of (1) to (4), wherein the volume average cell diameter Dv and number average cell diameter Dn of the polyester elastomer foam molded article satisfy Dv / Dn≦4. (8) A footwear member comprising the polyester elastomer foam molded article according to any one of (5) to (7).

[0011] The polyester elastomer resin composition of the present invention, even when using a higher proportion of biomass-derived raw materials, can retain the excellent mechanical properties, retention stability, and high-precision moldability of fossil fuel-derived polyester elastomers, and also has excellent foam moldability. Therefore, foam-molded articles made from the polyester elastomer resin composition of the present invention can have a uniform foaming state despite a high expansion ratio, and are lightweight, have excellent compression recovery, and a high rebound resilience. Therefore, the polyester elastomer resin composition of the present invention can be suitably used as cushioning components for sports goods, such as shoe soles (preferably inner soles or midsoles), golf balls, mattresses, chairs, beds, etc., and can significantly contribute to solving global environmental problems, such as the depletion of fossil fuel resources.

[0012] The polyester elastomer resin composition of the present invention is a polyester elastomer resin composition containing a biomass resource-derived polyester elastomer with a specific high biobased content and a heat stabilizer, and is characterized in that the polyester elastomer resin composition has an MFR value under a load of 2.16 kg, measured in accordance with the flow test method for thermoplastics specified in JIS K7210, and an acid value, which are set within specific ranges.

[0013] The biomass resource-derived polyester elastomer used in the resin composition of the present invention is preferably a polyester elastomer in which a hard segment made of a polyester having as its constituent components an aromatic dicarboxylic acid and an aliphatic and / or alicyclic diol is bonded to a soft segment made of an aliphatic polyether. It is preferable that the aromatic dicarboxylic acid and the aliphatic and / or alicyclic diol are derived from fossil fuel resources, and the aliphatic polyether is derived from a biomass resource.

[0014] As the aromatic dicarboxylic acid constituting the polyester of the hard segment, ordinary aromatic dicarboxylic acids are widely used, and the main aromatic dicarboxylic acid is preferably terephthalic acid or naphthalenedicarboxylic acid (among the isomers, 2,6-naphthalenedicarboxylic acid is preferred). The content of these aromatic dicarboxylic acids is preferably 70 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more, of all the dicarboxylic acids constituting the polyester of the hard segment, and may be 100 mol%. Examples of dicarboxylic acid components other than terephthalic acid and naphthalenedicarboxylic acid include aromatic dicarboxylic acids such as diphenyldicarboxylic acid, isophthalic acid, and 5-sodiumsulfoisophthalic 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 dicarboxylic acids can be used in a range that does not significantly lower the melting point of the resin, and the amount is preferably 30 mol % or less of the total acid components, more preferably 20 mol % or less, and even more preferably 10 mol % or less, and may be 0 mol %. When these dicarboxylic acids are used as raw materials for polyester elastomers, they may be in the form of esters of the dicarboxylic acids. For example, terephthalic acid and dimethyl terephthalate can also be used as raw materials.

[0015] Furthermore, as the aliphatic or alicyclic diol constituting the polyester of the hard segment, general aliphatic or alicyclic diols are widely used and are not particularly limited, but alkylene glycols mainly having 2 to 8 carbon atoms are preferred. Specific examples include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, and 1,4-cyclohexanedimethanol. Of these, either ethylene glycol or 1,4-butanediol is preferred.

[0016] As the component constituting the polyester of the hard segment, those comprising butylene terephthalate units (units consisting of terephthalic acid and 1,4-butanediol) or butylene naphthalate units (units consisting of 2,6-naphthalenedicarboxylic acid and 1,4-butanediol) are preferred in terms of physical properties, moldability, and cost performance.

[0017] Alternatively, when an aromatic polyester suitable for forming the hard segment of the polyester elastomer is prepared in advance and then copolymerized with the soft segment component, the aromatic polyester can be easily obtained according to a conventional polyester production method. The polyester preferably has a number average molecular weight of 10,000 to 40,000.

[0018] The aliphatic polyether constituting the soft segment of the polyester elastomer is preferably a glycol compound because it bonds with the polyester of the hard segment. Specific examples include poly(ethylene oxide) glycol, poly(propylene oxide) glycol, polytetramethylene ether glycol, polytrimethylene ether glycol, poly(hexamethylene oxide) glycol, a copolymer of ethylene oxide and propylene oxide, an ethylene oxide adduct of poly(propylene oxide) glycol, and a copolymer of ethylene oxide and tetrahydrofuran. Among these, polytetramethylene ether glycol and an ethylene oxide adduct of poly(propylene oxide) glycol are preferred from the viewpoint of elastic properties.

[0019] In the present invention, the aliphatic polyether constituting the soft segment is preferably derived from a biomass resource, particularly polytetramethylene ether glycol (PTMG) derived from a biomass resource. Commercially available PTMG can be used, and preferred examples include BioPTMG1000 and BioPTMG2000 manufactured by Mitsubishi Chemical Corporation.

[0020] The polyester elastomer is preferably a copolymer primarily composed of terephthalic acid, 1,4-butanediol, and polytetramethylene ether glycol. Of the dicarboxylic acid components constituting the polyester elastomer, terephthalic acid preferably accounts for 40 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and particularly preferably 90 mol% or more. Of the glycol components constituting the polyester elastomer, the total of 1,4-butanediol and polytetramethylene ether glycol is preferably 40 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and particularly preferably 90 mol% or more.

[0021] The number-average molecular weight of the polytetramethylene ether glycol is preferably 500 to 4,000, more preferably 700 to 3,000, and even more preferably 800 to 2,500. If the number-average molecular weight is below the above range, it may be difficult to exhibit elastomeric properties. On the other hand, if the number-average molecular weight exceeds the above range, compatibility with the hard segment component may decrease, making it difficult to copolymerize in a block form.

[0022] In the present invention, the mass of the hard segment refers to the mass of the component composed of an aromatic dicarboxylic acid and an aliphatic and / or alicyclic diol, and the mass of the soft segment refers to the mass of the component composed of an aliphatic dicarboxylic acid and / or an aliphatic polyether. For example, in the case of a polyester elastomer composed of terephthalic acid, 1,4-butanediol, and polytetramethylene ether glycol (PTMG), the mass of the hard segment is the mass of butylene terephthalate units (condensation units of terephthalic acid and 1,4-butanediol), and the mass of the soft segment is the mass of polytetramethylene ether glycol (PTMG).

[0023] The mass ratio of hard segments to soft segments in the polyester elastomer is preferably 5 / 95 to 90 / 10, more preferably 10 / 90 to 85 / 15, and even more preferably 15 / 85 to 80 / 20. If the amount of hard segments is low (the amount of PTMG is high), the polyester elastomer may not have satisfactory heat aging resistance and moldability (crystallinity). Conversely, if the amount of hard segments is high (the amount of PTMG is low), the compatibility between the hard segment components and the soft segment components may decrease, making it difficult to copolymerize them into blocks.

[0024] The melting point of the polyester elastomer is preferably 150 to 230° C. If the melting point is below 150° C., the polyester elastomer may not have satisfactory heat aging resistance and moldability (crystallinity). Conversely, if the melting point is above 230° C., the polyester elastomer may contain a large amount of hard segments, resulting in a correspondingly high glass transition temperature (Tg), and may not have satisfactory impact resilience, flexibility, and low-temperature mechanical properties.

[0025] Any known method can be used to produce a polyester elastomer. For example, melt polymerization, solution polymerization, solid-state polymerization, or the like can be used as appropriate. In the case of melt polymerization, either transesterification or direct polymerization can be used. For example, a method can be used in which a dicarboxylic acid component and a diol component are reacted to form a prepolymer by transesterification or direct esterification, followed by polycondensation under reduced pressure. In this case, a catalyst for transesterification or esterification, or a catalyst for polycondensation can be used as appropriate. Furthermore, after polymerization, chain extension can be performed using an isocyanate compound, an epoxy compound, or the like. Furthermore, solid-state polymerization can improve the viscosity of the resin during the polymerization process.

[0026] To produce the polyester elastomer of the present invention, it is preferable to extend the polycondensation time compared to conventional methods. For example, in the polycondensation of polyester elastomers using butylene terephthalate units as the hard segment constituent and polytetramethylene ether glycol as the soft segment constituent, the polycondensation time for producing polyester elastomers is typically about 50 to 90 minutes. In the present invention, however, the polycondensation time is preferably 100 to 140 minutes, more preferably 105 to 135 minutes. It is also preferable to control the polycondensation temperature within a narrow range. Typically, the polycondensation temperature for producing polyester elastomers is about 235 to 260°C. In the present invention, however, the polycondensation temperature is preferably 235 to 255°C, more preferably 240 to 250°C. If the polycondensation time is too short or the polycondensation temperature is too low, the polymerization reaction may not proceed smoothly, resulting in a high oligomer content or an increased acid value of the system. Furthermore, the reduced viscosity of the polyester elastomer may not increase, and the elongation at break and tensile strength at break may not satisfy the functions required for a polyester elastomer, and the retention stability may deteriorate. Conversely, if the polycondensation time is long or the polycondensation temperature is high, thermal decomposition may cause discoloration of the polyester elastomer, worsening its appearance, and accelerating the formation of oligomers and gelation. Furthermore, the pressure is gradually reduced from the pressure used for the transesterification reaction, with the final pressure preferably being 0.1 to 3 Torr, and more preferably 0.04 to 0.2 kPa. If the pressure exceeds the upper limit, reactivity may decrease, the reaction time may be prolonged, and thermal decomposition may cause discoloration of the polyester elastomer, worsening its appearance, and accelerating the formation of oligomers and gelation. On the other hand, if the pressure is too low, there is a risk of compositional deviation due to excessive volatilization or distillation of monomers, or a delay in the polymerization reaction due to excessively reduced intermolecular collisions. The polycondensation conditions must be adjusted appropriately depending on the constituent components.

[0027] The biobased content of the polyester elastomer of the present invention, expressed as the biobased content of the resin composition including components such as a heat stabilizer, is 20 to 100%, preferably 20 to 99.9%, more preferably 20 to 99%, even more preferably 20 to 85%, and particularly preferably 20 to 80%. The biobased content of the polyester elastomer is preferably 20 to 100%, more preferably 20 to 85%, and even more preferably 20 to 80%. Conventionally, biomass-derived raw materials contain impurities that cannot be completely removed during the purification process. Therefore, increasing the proportion of biomass raw materials in an attempt to increase the biobased content has resulted in problems such as an increase in the amount of impurities, which inhibits the reaction, prevents an increase in reduced viscosity, prolongs the polymerization time, and causes discoloration. Therefore, it has been difficult to obtain a biomass-derived polyester elastomer that can maintain excellent flexibility, low-temperature mechanical properties, heat aging resistance, and water resistance while preventing discoloration without reducing production efficiency. In the present invention, as polymerization raw materials for the polyester elastomer, those derived from fossil fuel resources are used for the hard segments, and an aliphatic polyether is used as a raw material derived from biomass resources only for the soft segments. By adopting an appropriate polycondensation reaction time and temperature, it is possible to obtain a biomass resource-derived polyester elastomer that is free of coloration and that retains the excellent properties of fossil fuel resource-derived polyester elastomers.

[0028] In the present invention, the reduced viscosity (ηsp / c) of the polyester elastomer is preferably 1.2 dl / g or more, more preferably 1.3 dl / g or more, and even more preferably 1.5 dl / g or more. If the reduced viscosity (ηsp / c) is low, the molecular weight is small, and the polyester elastomer may not have sufficient long-term durability (heat aging resistance, water resistance) in some cases.

[0029] In the present invention, the glass transition temperature (Tg) of the polyester elastomer is preferably −70 to 10° C., more preferably −65 to 10° C. If the glass transition temperature is high, it may not be possible to obtain a polyester elastomer that satisfies the functions of impact resilience, flexibility, and low-temperature mechanical properties.

[0030] In the present invention, the content of oligomers having a molecular weight of less than 1,000 in the biomass resource-derived polyester elastomer used is preferably 2.5 wt% or less, more preferably 2.4 wt% or less, and even more preferably 2.3 wt% or less. If the oligomer content is high, the MFR of the polyester elastomer resin composition may not be sufficiently reduced during compounding during the production of the composition, resulting in failure to achieve high-precision moldability. Furthermore, gel formation may occur more easily when a thickener is added, which may deteriorate the appearance and properties of molded articles. Furthermore, the thermal stability and water resistance of the molten resin may deteriorate, resulting in differences in fluidity between the start and end of molding, which may impair stable productivity. Furthermore, molded articles may not have satisfactory rebound resilience, flexibility, and low-temperature mechanical properties.

[0031] The composition and composition ratio of the polyester elastomer of the present invention can be determined by dissolving a sample in a solvent such as deuterated chloroform and measuring the composition. １ It can also be calculated from the proton integral ratio of H-NMR.

[0032] The polyester elastomer resin composition of the present invention contains a heat stabilizer as an essential component in addition to the polyester elastomer described above. The polyester elastomer resin composition of the present invention may also optionally contain a thickener and / or a hydrolysis inhibitor.

[0033] Heat stabilizers are used to prevent thermal oxidative decomposition during compounding and molding. Examples of heat stabilizers that can be used include known hindered phenol-based antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants, and amine-based antioxidants. The amount of heat stabilizer added is preferably 0.1 to 5 parts by mass, more preferably 0.1 to 4 parts by mass, and even more preferably 0.2 to 3.5 parts by mass, per 100 parts by mass of polyester elastomer. If the amount of heat stabilizer is too small, the effect of preventing thermal oxidative decomposition will be insufficient, and if the amount is too large, mechanical properties may be reduced.

[0034] Hindered phenol antioxidants include 3,5-di-t-butyl-4-hydroxytoluene, n-octadecyl-β-(4'-hydroxy-3',5'-di-t-butylphenyl)propionate, tetrakis[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, 1,3,5-trimethyl-2,4,6'-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, and calcium (3,5-di-t-butyl-4-hydroxybenzyl-monoethyl-phosphate). , triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], pentaerythrityl-tetrakis[3-(3,5-di-t-butylanilino)-1,3,5-triazine, 3,9-bis[1,1-dimethyl-2-{β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl]2,4,8,10-tetraoxaspiro[5,5]undecane, bis[3,3-bis(4'-hydroxy-3'-t-butylphenyl)butyric acid]glycol ester, tripheno 2,2'-ethylidenebis(4,6-di-t-butylphenol), N,N'-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl]hydrazine, 2,2'-oxamidobis[ethyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 1,1,3-tris(3',5'-di-t-butyl-4'-hydroxybenzyl)-S-triazine-2,4,6(1H,3H,5H)-trione, 1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)isothiazolinone cyanurate, 3,5-di-t-butyl-4-hydroxyhydrocinnamic amide triester with-1,3,5-tris(2-hydroxyethyl)-S-triazine-2,4,6(1H,3H,5H), N,N-hexamethylenebis(3,5-di-t-butyl-4-hydroxy-hydrocinnaamide), 3,9-bis[2-{3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy}-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane, and the like.

[0035] Examples of sulfur-based antioxidants include dilauryl-3,3'-thiodipropionic acid ester, dimyristyl-3,3'-thiodiuropionic acid ester, distearyl-3,3'-thiodipropionic acid ester, laurylstearyl-3,3'-thiodipropionic acid ester, dilaurylthiodipropionate, dioctadecyl sulfide, and pentaerythryl-tetra(β-lauryl-thiopropionate) ester.

[0036] Examples of phosphorus-based antioxidants include tris(mixed, mono- and diolylphenyl)phosphite, tris(2,3-di-t-butylphenyl)phosphite, 4,4'-butylidene-bis(3-methyl-6-t-butylphenyl-di-tridecyl)phosphite, 1,1,3-tris(2-methyl-4-di-tridecylphosphite-5-t-butylphenyl)butane, tris(2,4-di-t-butylphenyl)phosphite, bis(2,4-di-t-butylphenyl)pentaerythritol-di-phosphite, tetrakis(2,4-di tetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylene phosphanite, bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite, tetrakis(2,4-di-t-butylphenyl)4,4'-biphenylene diphosphonite, triphenyl phosphite, diphenyldecyl phosphite, tridecyl phosphite, trioctyl phosphite, tridodecyl phosphite, trioctadecyl phosphite, trinonylphenyl phosphite, tridodecyl trithiophosphite, and the like can be mentioned.

[0037] Examples of the amine antioxidant include amines such as N,N-diphenylethylenediamine, N,N-diphenylacetamidine, N,N-diphenylformamidine, N-phenylpiperidine, dibenzylethylenediamine, triethanolamine, phenothiazine, N,N'-di-sec-butyl-p-phenylenediamine, 4,4'-tetramethyl-diaminodiphenylmethane, P,P'-dioctyl-diphenylamine, N,N'-bis(1,4-dimethyl-pentyl)-p-phenylenediamine, phenyl-α-naphthylamine, phenyl-β-naphthylamine, and 4,4'-bis(4-α,α-dimethyl-benzyl)diphenylamine, and derivatives thereof, reaction products of amines and aldehydes, and reaction products of amines and ketones.

[0038] The thickener is a reactive compound having a functional group capable of reacting with the terminal group of the polyester elastomer and a functional group capable of reacting with the hydroxyl or carboxyl group of the polyester elastomer. The reactive functional group is preferably at least one selected from the group consisting of an epoxy group (glycidyl group), an acid anhydride group, a carbodiimide group, and an isocyanate group, and two or more such functional groups are contained per molecule. The functional group is more preferably an epoxy group (glycidyl group).

[0039] When the thickener is a compound having an epoxy group, examples of polyfunctional epoxy compounds having two or more epoxy groups include 1,6-dihydroxynaphthalene diglycidyl ether and 1,3-bis(oxiranylmethoxy)benzene, each having 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, each having three epoxy groups; and 1-chloro-2,3-epoxypropane-formaldehyde-2,7-naphthalenediol polycondensates and pentaerythritol polyglycidyl ether, each having four epoxy groups. Among these, polyfunctional epoxy compounds having heat resistance in the skeleton are preferred. In particular, bifunctional or tetrafunctional epoxy compounds having a naphthalene structure as the skeleton, or trifunctional epoxy compounds having a triazine structure as the skeleton are preferred. Considering the degree of increase in the solution viscosity of the polyester elastomer, the effect of efficiently reducing the acid value of the polyester elastomer, and the degree of gelation due to aggregation and solidification of the epoxy itself, difunctional or trifunctional epoxy compounds are preferred.

[0040] When a thickener is added, the blending amount is preferably 0.1 to 5.0 parts by mass, more preferably 0.1 to 4 parts by mass, and even more preferably 0.2 to 3.5 parts by mass, per 100 parts by mass of polyester elastomer. If the amount of thickener is too small, the targeted molecular chain extension effect will be insufficient, while if the amount is too large, the thickening effect will be excessive, which will adversely affect moldability and the mechanical properties of the molded product. If the thickener is an epoxy compound, too much may cause unevenness on the surface of the molded product due to the aggregation and hardening of the epoxy compound. If the thickener is a carbodiimide compound, too much may cause hydrolysis of the polyester elastomer due to the basicity of the polycarbodiimide compound, which will tend to affect the mechanical properties.

[0041] Hydrolysis inhibitors are added to improve hydrolysis resistance and flex fatigue resistance through chain extension. Examples of hydrolysis inhibitors that can be used include compounds having functional groups capable of reacting with the terminal functional groups of polyester elastomers. The terminal functional groups of polyester elastomers are carboxyl groups and / or hydroxyl groups. Examples of functional groups capable of reacting with the terminal functional groups of polyester elastomers include carboxyl groups, acid anhydride groups, epoxy groups, hydroxyl groups, carbodiimide groups, and oxazoline groups. Among these, epoxy groups or carbodiimide groups are preferred as the functional groups in terms of changes in melt viscosity during melt retention and reactivity with the terminal functional groups of polyester elastomers. The hydrolysis inhibitor is preferably an epoxy compound and / or a carbodiimide compound.

[0042] When a hydrolysis inhibitor is added, the blending amount is preferably 0.1 to 5 parts by mass, more preferably 0.1 to 4 parts by mass, and even more preferably 0.2 to 3.5 parts by mass, per 100 parts by mass of polyester elastomer. If the amount of hydrolysis inhibitor is too small, the effect will be insufficient, while if the amount is too large, there may be a decrease in flame retardancy or a decrease in mechanical properties due to the effect of foreign matter. Note that if a high molecular weight polyester elastomer that does not require chain extension or a polyester elastomer with a sufficiently small terminal acid value is used as the polyester elastomer, the addition of a hydrolysis inhibitor is not necessary.

[0043] In addition to the above components, the polyester elastomer resin composition of the present invention can contain various additives depending on the purpose, including known light stabilizers such as hindered amines, triazoles, benzophenones, benzoates, nickel, and salicylic acids, antistatic agents, lubricants, molecular regulators such as peroxides, metal deactivators, organic and inorganic nucleating agents, neutralizing agents, antacids, antibacterial agents, fluorescent brighteners, fillers, and organic and inorganic pigments.

[0044] The acid value of the polyester elastomer resin composition of the present invention is 50 eq / ton or less. It is preferably 45 eq / ton or less, more preferably 40 eq / ton or less, and even more preferably 35 eq / ton or less. When the acid value is within the above range, the melt viscosity during foam molding is stable, and even during long-term continuous foam molding, there is little change in the state of the cells, resulting in stable foam-molded body properties. The composition also has excellent hydrolysis resistance. On the other hand, when the acid value of the polyester elastomer resin composition exceeds the above range, if a thickener is included, localized reactions with the thickener may occur, raising concerns about the formation of gelled products. Furthermore, hydrolysis is more likely to occur. Therefore, when the resin composition is compounded or molded, if the residence time is long at high temperatures, the melt viscosity of the resin composition decreases, the properties during molding may change easily, and the moist heat resistance of the resulting foam-molded body may be poor.

[0045] When a thickener is used in the polyester elastomer resin composition of the present invention, in order to set the acid value of the resin composition within the above range, it is preferable not only to set the acid value of the polyester elastomer within the same range, but also to control the reaction between the thickener to be blended and the carboxyl terminal of the polyester elastomer.

[0046] The polyester elastomer resin composition of the present invention has a melt flow rate (MFR) of 0.5 to 20 g / 10 min, measured according to the flow test method for thermoplastics specified in JIS K7210 at a melting point of 20°C, a load of 2.16 kg, and a residence time of 5 minutes. It is preferably 0.5 to 18 g / 10 min, more preferably 1 to 16 g / 10 min. If the MFR is lower than the above range, the number of cells in the foamed molded article decreases, the cell diameter does not increase, and high-expansion foaming becomes difficult. Furthermore, gel-like matter tends to form. If the MFR is higher than the above range, the closed cell ratio in the foamed molded article decreases, the cell diameter becomes nonuniform, and mechanical properties such as rebound resilience and compression recovery deteriorate. Furthermore, properties tend to fluctuate during continuous molding.

[0047] The method for adjusting the MFR value within the above range is not particularly limited, but examples include molecular weight control during polyester elastomer polymerization, chain extension during compounding, etc. In the present invention, it is preferable to add a predetermined amount of a thickener by a specific method during compounding, since this allows the MFR value to be controlled together with the acid value.

[0048] The method for producing the polyester elastomer resin composition of the present invention is not particularly limited, but it can be produced by melt-kneading each component using a single-screw extruder, twin-screw extruder, kneader, Banbury mixer, roll, or the like known to those skilled in the art.

[0049] When using a twin-screw extruder, it is preferable to appropriately select the extruder barrel temperature and screw configuration to control the resin pressure in the extruder plasticization section. When melt-kneading the above components, it is important to allow the molten components to coexist with the molten polymer phase in the polymer plasticization region, increase the polymer viscosity as the matrix phase, and use shear stress to uniformly melt the molten components into the polymer phase, while controlling internal heat generation to suppress polymer degradation and side reactions. The resin pressure is preferably about 0.1 to 1 MPa.

[0050] The melting temperature of the resin composition during melt-kneading is preferably 160 to 300° C., and more preferably 180 to 280° C. If the melting temperature is low, the resin composition will not melt sufficiently and will tend to produce a large number of unmelted gels, whereas if the resin temperature is high, the resin composition will be prone to thermal degradation.

[0051] The screw rotation speed during melt-kneading is preferably 50 to 500 rpm, more preferably 100 to 300 rpm. If the screw rotation speed is low, the components tend not to melt and react uniformly, while if it is high, shear heat generation may occur, which may cause polymer deterioration or side reactions. The discharge rate Q is preferably 5 to 1,000 kg / hr, more preferably 10 to 500 kg / hr. If the discharge rate is low, the resin filling rate in the extruder tends to decrease, resulting in uneven kneading. Conversely, if the discharge rate is high, the resin filling rate in the extruder tends to become too high, resulting in uneven kneading.

[0052] The foaming method for the polyester elastomer resin composition of the present invention is not particularly limited, but a foaming method in which the resin composition is impregnated with a high-pressure gas and then depressurized (pressure is released) is preferred. A method for obtaining a homogeneous foam with excellent molding cycle properties and cost is to melt-mix a blowing agent and the polyester elastomer resin composition of the present invention and then injection-molde the resulting foam by expanding the cavity volume to obtain a foamed molded product. The foamed molded product of the present invention typically has a sandwich structure in which non-foamed skin layers are provided on both sides of the foamed layer (in other words, a structure in which the foamed layer is sandwiched between non-foamed skin layers on both sides). The size of the foamed molded product is not particularly limited, but the thickness of the sandwich structure is expected to be approximately 1 to 30 mm.

[0053] The foam layer of the foamed molded article of the present invention is composed of a resin continuous phase and independent foam cells. Here, the resin continuous phase refers to the non-void portion formed by the cured polyester elastomer resin composition. It is preferable that the diameter of the foam cells (cell diameter) is uniform and consistent. The average cell diameter is preferably 10 to 400 μm, more preferably 50 to 400 μm, even more preferably 100 to 400 μm, and particularly preferably 150 to 300 μm. If the average cell diameter is small, the internal pressure of the molded article is low, resulting in insufficient pressure during the formation of the non-foamed skin layer, and this tends to result in poor appearance, such as sink marks. On the other hand, if the average cell diameter is large, the load-bearing capacity tends to be low.

[0054] The non-foamed skin layer is laminated on the foamed layer and preferably has a thickness of 100 to 800 μm. If the thickness of the non-foamed skin layer is small, a good appearance tends not to be obtained, while if the thickness is large, the specific gravity of the foamed layer becomes too low, and it tends not to be possible to obtain a uniform cell state throughout the foamed molded article. The thickness of the non-foamed skin layer is more preferably 200 to 600 μm, and even more preferably 300 to 400 μm.

[0055] The foamed molded article obtained from the polyester elastomer resin composition of the present invention can achieve a Dv / Dn ratio of 4, preferably 3.7, and more preferably 3, where Dv is the volume-average cell diameter and Dn is the number-average cell diameter. When Dv / Dn is within the above range, closed-cell foams are easily obtained. Furthermore, the number of coarse cells exceeding 800 μm in diameter is small, which has little effect on the physical properties of the entire foam phase, resulting in excellent rebound resilience and compression recovery. When Dv / Dn is greater than the above range, the number of coarse cells exceeding 800 μm increases, and extra-large cells of several thousand μm appear, resulting in an increase in open-cell foams, which affects the physical properties of the entire foam phase. As a result, rebound resilience and compression recovery are reduced.

[0056] As a method for controlling the Dv / Dn of the foamed molded article obtained from the polyester elastomer resin composition of the present invention, a method for controlling the cell diameter commonly used in each foam molding method can be adopted, but it is preferable to appropriately control the melt fluidity of the resin composition during foaming. If the melt fluidity is too low, the resin cannot keep up with the force that expands the cells, resulting in large variations in cell diameter and the likelihood of coarse bubbles forming. On the other hand, if the melt fluidity is too high, it is undesirable because it inhibits the generation and growth of cells. MFR can be used as an index of melt fluidity when controlling Dv / Dn.

[0057] When a foamed molded article obtained from the polyester elastomer resin composition of the present invention is subjected to continuous molding, the Dv / Dn of the foamed molded article obtained after 5 shots from the start of foam molding is (Dv / Dn) ５ The Dv / Dn of the foamed molded article obtained 30 shots after the start of foam molding was calculated as (Dv / Dn). ３０ and Δ(Dv / Dn)=(Dv / Dn) ３０ - (Dv / Dn) ５ When the ratio is Δ(Dv / Dn)≦1, it is possible to achieve Δ(Dv / Dn)≦1. More preferably, Δ(Dv / Dn)≦0.8, even more preferably, Δ(Dv / Dn)≦0.5, and particularly preferably, Δ(Dv / Dn)≦0.4. When Δ(Dv / Dn) is within the above range, there is little change in physical properties even during continuous molding, and foamed molded articles of stable quality can be obtained.

[0058] In the present invention, Dn and Dv are calculated as follows. First, the diameter of each individual cell is determined as follows. A photograph of the foam cross section of a sample for cross-section observation taken with an electron microscope is image-processed, and the equivalent circle diameters of at least 100 adjacent cells (if the cells are observed to be elliptical, the average of the major and minor diameters is used as the equivalent circle diameter) are measured with calipers to determine the diameter of each individual cell. The average of these 100 cells is calculated, and this is performed at any three locations. The average of the three average values ​​obtained at the three locations is defined as the average cell diameter di. Dn and Dv are then calculated using the following formulas: Dn = Σdi / n Dv = Σ(Vi·di) / Σ(Vi) (where n is the total number of cells measured, and Vi is the volume of each cell calculated using di, assuming that each cell is a perfect sphere.)

[0059] The chemical foaming agent used to obtain the foamed molded article of the present invention is added to the molten resin in the resin melting zone of a molding machine as a gas component or source of gas that serves as foam nuclei. Specifically, examples of chemical foaming agents that can be used include inorganic compounds such as ammonium carbonate and sodium bicarbonate, and organic compounds such as azo compounds, sulfohydrazide compounds, nitroso compounds, and azide compounds. Examples of the azo compounds include diazocarbonamide (ADCA), 2,2-azoisobutyronitrile, azohexahydrobenzonitrile, and diazoaminobenzene, with ADCA being preferred. Examples of the sulfohydrazide compounds include benzenesulfohydrazide, benzene 1,3-disulfohydrazide, diphenylsulfone-3,3-disulfonhydrazide, and diphenyloxide-4,4-disulfonhydrazide. Examples of the nitroso compounds include N,N-dinitrosopentaethylenetetramine (DNPT). Examples of the azide compounds include terephthalazide and p-tert-butylbenzazide.

[0060] The density (apparent density) of the foamed molded article obtained from the polyester elastomer resin composition of the present invention is 0.01 to 0.30 g / cm ３ The density of a typical polyester elastomer is preferably 1.0 to 1.4 g / cm. ３Therefore, if it is within the above range, it is sufficiently light. More preferably, it is 0.1 to 0.25 g / cm ３ , more preferably 0.1 to 0.20 g / cm ３ If the density is below the above range, sufficient strength cannot be obtained and the mechanical properties tend to be poor, whereas if the density exceeds the above range, sufficient flexibility cannot be obtained and the weight reduction cannot be said to be sufficient.

[0061] When the foamed molded article of the present invention has the above-mentioned Dv / Dn within the specified range, it has a uniform and fine cell structure, and as a result, it can achieve a high impact resilience of 60% or more.

[0062] The rebound resilience is a value measured by the method described in JIS K 6400. Specifically, a manual measuring tester is used to drop a steel ball onto a test piece from a specified height, and the maximum rebound height is read. The rebound resilience can be calculated by taking three measurements within one minute and finding the median value.

[0063] When the Dv / Dn ratio is within a predetermined range, the foamed molded article of the present invention has a uniform and fine cell structure, and as a result, a 50% constant displacement repeated compression set of 10% or less can be achieved. It is more preferably 8% or less, and even more preferably 6% or less. If the 50% constant displacement repeated compression set exceeds the above range, the thickness decreases with long-term use, making it unsuitable as a cushioning material. While there is no particular restriction on the lower limit of the 50% constant displacement repeated compression set, the foamed molded article obtained by the present invention has a compression set of 1% or more.

[0064] The 50% constant displacement repeated compression set is determined as follows: A sample is cut into a size of 50 mm x 50 mm, and the heights of four corners are measured with a vernier caliper. The average value is taken as the initial thickness (a). The sample whose thickness has been measured is compressed and recovered at a cycle of 1 Hz using a pressure plate of φ200 mm in an environment of 20°C ± 2°C until the thickness is 50% of the initial thickness. After 80,000 compressions, the sample is left to stand for one day, and then the heights of the four corners of the test sample are measured with a vernier caliper. The average value is taken as the post-test thickness (b). The 50% constant displacement repeated compression set is calculated using the formula {(a) - (b)} / (a) x 100.

[0065]

[0013] Because the polyester elastomer resin composition of the present invention is configured as described above, it can retain the excellent mechanical properties, retention stability, and high-precision moldability of fossil fuel-derived polyester elastomers, despite using a polyester elastomer derived from a biomass resource with a high biomass content, and has excellent foam moldability. Furthermore, foam molded articles obtained from the resin composition of the present invention are lightweight, have excellent compression recovery, and a high rebound resilience, and are therefore suitable for use in a variety of parts, such as automobile parts, electrical and electronic parts, building materials, various containers, daily necessities, household goods, cosmetic parts, sanitary products, and medical (medical and treatment) parts.

[0066] More specifically, the foamed molded article obtained from the resin composition of the present invention can be used for midsoles, insoles, outsoles, etc. that constitute the soles of shoes; core materials for hitting tools for sporting goods such as rackets and bats, and for balls such as golf balls; protective gear for sporting goods such as pads and protectors; medical, nursing care, welfare, and health care products such as pads and protectors; tire core materials for bicycles, wheelchairs, etc.; interior materials, seat core materials, shock absorbing members, and vibration absorbing members for transportation equipment such as automobiles, railway cars, and airplanes; shock absorbing materials such as fenders and floats; toys, beds, mattresses, cushions, etc.

[0067] The following examples are provided to demonstrate the effects of the present invention, but the present invention is not limited to these examples. The property values ​​were evaluated by the following methods. The raw materials used in the examples, and those not otherwise specified, are derived from fossil fuel resources.

[0068] (1) Bio-based Degree The bio-based degree of a polyester elastomer is the ratio of the biomass-derived monomer components to the total mass of the monomer components that make up the polyester elastomer, calculated from the mass of the biomass-derived monomer components. The bio-based degree is the ratio of the amount of carbon that is only contained in the biomass-derived raw materials to the total carbon contained in the polyester elastomer. １４ C carbon ( １２The biobased content (%) of the polyester elastomer was measured using an accelerator mass spectrometer (AMS) in accordance with ASTM D6866. On the other hand, the biobased content of a polyester elastomer resin composition is the proportion of monomer components derived from biomass resources, calculated from the mass of monomer components derived from biomass resources relative to the mass of all monomer components constituting the polyester elastomer resin composition. The biobased content is the ratio of the amount of monomer components derived from biomass resources that are only contained in raw materials derived from biomass resources relative to the total carbon contained in the polyester elastomer resin composition. １４ C carbon ( １２ The biobased content (%) of the polyester elastomer resin composition was measured using an accelerator mass spectrometer (AMS) in accordance with ASTM D6866.

[0069] (2) Reduced Viscosity (ηsp / c) 0.05 g of polyester elastomer was dissolved in 25 mL of a mixed solvent (phenol / tetrachloroethane=60 / 40), and the reduced viscosity (dl / g) was measured at 30° C. using an Ubbelohde viscometer.

[0070] (3) Melting Point (Tm) Using a differential scanning calorimeter "DSC220" manufactured by Seiko Instruments Inc., 5 mg of a measurement sample was placed in an aluminum pan, the pan was sealed with a lid, and the sample was melted in nitrogen at 250°C for 2 minutes. The sample was then cooled to 50°C at a rate of 20°C / min, and then heated from 50°C to 250°C at a rate of 20°C / min. The endothermic peak due to melting was determined from the obtained thermogram curve, and this was designated as the melting point (°C).

[0071] (4) Acid Value 0.2 g of sample was accurately weighed, and benzyl alcohol was added and heated to dissolve. The sample was then dissolved in 20 ml of chloroform and titrated with 0.08 N potassium hydroxide (ethanol solution). The acid value (eq / ton) was calculated from the amount of potassium hydroxide required for neutralization. Phenol red ethanol solution was used as an indicator.

[0072] (5) Oligomer Content The oligomer content in polyester elastomer (A) was measured as follows. 8 mg of the resin component was weighed and dissolved in 4 ml of 10 mM HFIP / sodium trifluoroacetate. The solution was filtered through a 0.2 μm membrane filter, and the resulting sample solution was subjected to GPC analysis under the following conditions. The molecular weight was calculated in terms of polymethyl methacrylate (PMMA). The ratio (percentage) of the peak area showing a molecular weight of 1,000 or less to the total peak area of ​​the polymer in the GPC analysis chart was calculated, and this area ratio was taken as the oligomer amount (wt %). Apparatus: TOSOH HLC-8320GPC Column: TOSOH TSKgel SuperHM-H x 2 + TSKgel SuperH2000 Solvent: HFIP / sodium trifluoroacetate 10 mM Flow rate: 0.2 ml / min Injection volume: 10 μl Temperature: 40°C Detector: RI Concentration: 0.05%

[0073] (6) MFR: The melt flow rate (MFR: g / 10 min) was measured 5 minutes after adding 2160 g of the polyester elastomer resin composition at a temperature 20°C above the melting point of the polyester elastomer (A) in accordance with the test method (Method A) described in JIS K7210. A composition with a moisture content of 0.1% by mass or less was used for the measurement.

[0074] (7) Evaluation of Gelled Matter Approximately 50 g of the polyester elastomer resin composition was weighed into an approximately 250 ml glass bottle (approximately 4 cm diameter x 20 cm high). The bottle was immersed in a silicone oil bath at 250°C and heated for 4 hours with stirring while blowing nitrogen into it from above (approximately 30 ml / min). After the treatment, the contents were dissolved in 500 ml of a mixed solvent of tetrachloroethane and phenol (1 / 1 by weight) (the glass bottle was also rinsed with some of the mixed solvent). The insoluble matter was then separated using a 100-mesh stainless steel wire mesh (weight V') of known weight, visually inspected, and evaluated according to the following criteria: ∘: No gelation was observed; ×: Some gelation was observed.

[0075] (8) Dv / Dn A photograph of the foam cross section of a sample for cross-section observation, taken with a Hitachi High-Technologies scanning electron microscope (SU1510), was processed, and the equivalent circle diameter of at least 100 adjacent bubbles (when bubbles were observed to be elliptical, the average of the major and minor diameters was used as the equivalent circle diameter) was measured with a vernier caliper. The average of these 100 bubbles was calculated, and this was repeated at three random locations. The average of the three average values ​​obtained at the three locations was used as the average bubble diameter. The volume-average bubble diameter Dv and the number-average bubble diameter Dn were then calculated using the following formulas to calculate Dv / Dn: Dn = Σdi / n, Dv = Σ(Vi·di) / Σ(Vi), where n is the total number of bubbles measured, and Vi is the volume of each bubble calculated using di, assuming that each bubble is a perfect sphere.

[0076] (9) Δ(Dv / Dn) Continuous molding was performed, and the Dv / Dn of the foamed molded product obtained 5 shots after the start of foam molding was expressed as (Dv / Dn). ５ The Dv / Dn of the foamed molded article obtained 30 shots after the start of foam molding was calculated as (Dv / Dn). ３０ From these values, Δ(Dv / Dn)=(Dv / Dn) ３０ - (Dv / Dn) ５ It was calculated using the formula:

[0077] (10) Density (Apparent Density) The dimensions of a test piece of a foamed molded product were measured with a vernier caliper, and its mass was measured with an electronic balance, and the density was calculated by the following formula: Density (g / cm ３ ) = mass of test piece / volume of test piece

[0078] (11) Rebound Resilience: Measured according to the method described in JIS K6400. Using a manual measuring tester, a steel ball was dropped onto the test piece from a specified height, and the maximum rebound height was read. Three measurements were taken within one minute, and the median value was calculated to calculate the rebound resilience.

[0079] (12) 50% Constant Displacement Repeated Compression Residual Strain The sample was cut into a size of 50 mm x 50 mm, and the height of four corners was measured with a vernier caliper. The average value was taken as the initial thickness (a). The sample whose thickness was measured was repeatedly compressed and recovered at a cycle of 1 Hz using a pressure plate φ200 mm in an environment of 20°C ± 2°C until the thickness was 50% of the initial thickness. After 80,000 cycles, the sample was left to stand for one day, and then the height of the four corners of the test sample was measured with a vernier caliper. The average value was taken as the post-test thickness (b). The 50% constant displacement repeated compression residual strain was calculated using the formula {(a) - (b)} / (a) × 100.

[0080] (13) Continuous moldability The foam molded articles obtained using the polyester elastomer resin compositions for foam molding obtained in Examples 1 to 7, Comparative Examples 1 to 8, and Reference Examples 1 to 3 were evaluated as follows. Foam molding was carried out continuously, and foam molded articles from the 5th and 30th shots from the start of foam molding were evaluated according to the following criteria. (A: Change in rebound resilience (%), B: Change in 50% constant displacement repeated compression residual strain (%)) ◎: A≦1 and B≦1 ○: A≦2 and B≦2 △: A≦3 and B≦3 ×: A≧4 or B≧4

[0081] [Polyester elastomer (A)] Polyester elastomer (A1) 2500 parts by mass of dimethyl terephthalate (DMT, manufactured by SK Petrochemical), 1300 parts by mass of 1,4-butanediol (1,4-BDO, manufactured by Mitsubishi Chemical), 1230 parts by mass of biomass-derived polytetramethylene ether glycol (BioPTMG1000, number average molecular weight 1000, manufactured by Mitsubishi Chemical), 2.4 parts by mass of tetrabutyl titanate (TBT, manufactured by Nacalai Tesque), and 6.0 parts by mass of AO-330 (manufactured by ADEKA) were charged into an autoclave, and the temperature was raised from room temperature to 220 ° C. over 150 minutes to carry out a transesterification reaction. The pressure inside the autoclave was then gradually reduced and the temperature was further raised, and the initial condensation reaction was carried out at 250 ° C. and 1 Torr or less over 70 minutes. The polymerization reaction was further carried out at 250°C under a pressure of 1 Torr or less for 130 minutes, and a polymer having a hard segment / soft segment mass ratio of 59 / 41 (mass%) was taken out in the form of pellets. The obtained polymer was designated as polyester elastomer (A1).

[0082] Polyester elastomer (A2) 1600 parts by mass of dimethyl terephthalate (DMT, manufactured by SK Petrochemical), 1150 parts by mass of 1,4-butanediol (1,4-BDO, manufactured by Mitsubishi Chemical), 2260 parts by mass of biomass-derived polytetramethylene ether glycol (BioPTMG2000, number average molecular weight 2000, manufactured by Mitsubishi Chemical), 2.4 parts by mass of tetrabutyl titanate (TBT, manufactured by Nacalai Tesque), and 6.0 parts by mass of AO-330 (manufactured by ADEKA) were charged into an autoclave, and the temperature was raised from room temperature to 200 ° C. over 165 minutes to carry out a transesterification reaction. The pressure inside the autoclave was then gradually reduced and the temperature was further raised, and the initial condensation reaction was carried out at 250 ° C. and 1 Torr or less over 85 minutes. The polymerization reaction was further carried out at 250° C. under a pressure of 1 Torr or less for 110 minutes, and a polymer having a hard segment / soft segment mass ratio of 27 / 73 (mass%) was taken out in the form of pellets. The obtained polymer was designated as polyester elastomer (A2).

[0083] Polyester elastomer (A3) 2500 parts by mass of dimethyl terephthalate (DMT, manufactured by SK Petrochemical), 1300 parts by mass of 1,4-butanediol (1,4-BDO, manufactured by Mitsubishi Chemical), 1230 parts by mass of polytetramethylene ether glycol (PTMG1000, number average molecular weight 1000, manufactured by BASF), 2.4 parts by mass of tetrabutyl titanate (TBT, manufactured by Nacalai Tesque), and 6.0 parts by mass of AO-330 (manufactured by ADEKA) were charged into an autoclave, and the temperature was raised from room temperature to 220°C over 150 minutes to carry out a transesterification reaction. The pressure inside the autoclave was then gradually reduced and the temperature was further raised, and the initial condensation reaction was carried out at 250°C and 1 Torr or less over 70 minutes. The polymerization reaction was further carried out at 250°C under a pressure of 1 Torr or less for 85 minutes, and a polymer having a hard segment / soft segment mass ratio of 59 / 41 (mass%) was taken out in the form of pellets. The obtained polymer was designated as polyester elastomer (A3).

[0084] Polyester elastomer (A4) 2500 parts by mass of dimethyl terephthalate (DMT, manufactured by SK Petrochemical), 1300 parts by mass of 1,4-butanediol (1,4-BDO, manufactured by Mitsubishi Chemical), 1230 parts by mass of biomass-derived polytetramethylene ether glycol (BioPTMG1000, number average molecular weight 1000, manufactured by Mitsubishi Chemical), 2.4 parts by mass of tetrabutyl titanate (TBT, manufactured by Nacalai Tesque), and 6.0 parts by mass of AO-330 (manufactured by ADEKA) were charged into an autoclave, and the temperature was raised from room temperature to 220 ° C. over 150 minutes to carry out a transesterification reaction. The pressure inside the autoclave was then gradually reduced and the temperature was further raised, and the initial condensation reaction was carried out at 250 ° C. and 1 Torr or less over 70 minutes. The polymerization reaction was further carried out at 250° C. and at a pressure of 1 Torr or less for 90 minutes, and a polymer having a hard segment / soft segment mass ratio of 59 / 41 (mass %) was taken out in the form of pellets. The obtained polymer was designated as polyester elastomer (A4).

[0085] Polyester elastomer (A5) 2500 parts by mass of dimethyl terephthalate (DMT, manufactured by SK Petrochemical), 1,300 parts by mass of 1,4-butanediol (1,4-BDO, manufactured by Mitsubishi Chemical), 1,230 parts by mass of biomass-derived polytetramethylene ether glycol (BioPTMG1000, number average molecular weight 1000, manufactured by Mitsubishi Chemical), 2.4 parts by mass of tetrabutyl titanate (TBT, manufactured by Nacalai Tesque), and 6.0 parts by mass of AO-330 (manufactured by ADEKA) were charged into an autoclave, and the temperature was raised from room temperature to 220 ° C. over 150 minutes to carry out a transesterification reaction. The pressure inside the autoclave was then gradually reduced and the temperature was further raised, and the initial condensation reaction was carried out at 235 ° C. and 0.7 Torr or less over 60 minutes. The polymerization reaction was further carried out at 255°C under a pressure of 0.7 Torr or less for 130 minutes, and a polymer having a hard segment / soft segment mass ratio of 59 / 41 (mass%) was taken out in the form of pellets. The obtained polymer was designated as polyester elastomer (A5).

[0086] Polyester elastomer (A6) 2010 parts by mass of dimethyl terephthalate (DMT, manufactured by SK Petrochemical), 1920 parts by mass of 1,4-butanediol (1,4-BDO, manufactured by Mitsubishi Chemical), 990 parts by mass of biomass resource-derived dimer acid (C36DiCOOH, manufactured by Croda Propol 1009), 2.4 parts by mass of tetrabutyl titanate (TBT, manufactured by Nacalai Tesque), and 6.0 parts by mass of AO-330 (manufactured by ADEKA) were charged into an autoclave, and the temperature was raised from room temperature to 220 ° C. over 120 minutes to carry out a transesterification reaction and an esterification reaction. The pressure inside the autoclave was then gradually reduced and the temperature was further raised, and the initial condensation reaction was carried out at 250 ° C. and 1 Torr or less over 70 minutes. The polymerization reaction was further carried out at 250° C. under a pressure of 1 Torr or less for 60 minutes, and a polymer having a hard segment / soft segment mass ratio of 66 / 34 (mass%) was taken out in the form of pellets. The obtained polymer was designated as polyester elastomer (A6).

[0087] The compositions of the polyester elastomers (A1) to (A6) and the evaluation results are shown in Table 1.

[0088]

[0089] [Heat stabilizer] Hindered phenol-based antioxidant: Irganox 1010 (manufactured by BASF) [Hydrolysis inhibitor] Alicyclic polycarbodiimide: Carbodilite HMV-15CA, manufactured by Nisshinbo Chemical Inc. [Thickener] Triglycidyl isocyanurate compound: "TEPIC-S", manufactured by Nissan Chemical Industries, Ltd., epoxy valence (average number of epoxy groups per molecule): 3

[0090] Resin Compositions of Examples 1, 2, 6, and 7, Comparative Examples 5 and 8, and Reference Example 3: The above components were weighed in the proportions shown in Table 2. The components other than the hydrolysis inhibitor were premixed in a mixer for 90 seconds, and then fed into the main feed port of a 58 mm screw diameter, 10-barrel co-rotating twin-screw extruder (TEM58SS, manufactured by Toshiba Machine Co., Ltd.) with an L / D ratio of 45. The extruder barrel temperature was set to 210°C to 230°C, the screw rotation speed was 200 rpm, and the output rate was 220 kg / h. When a hydrolysis inhibitor was included, it was added through the feed port on the seventh barrel from the upstream side of the extruder and melt-kneaded. Finally, the resin was drawn out of the die in the form of a strand, passed through a water bath, cooled, and solidified. It was then cut into pellets using a pelletizer to obtain polyester elastomer resin composition pellets. The resulting polyester elastomer resin composition pellets were vacuum-dried overnight at 80°C and then subjected to various tests.

[0091] Resin Compositions of Examples 3 and 4, Comparative Examples 1 to 4, 6, and 7, and Reference Examples 1 and 2: The above components were weighed in the proportions shown in Table 2 and fed into the first main feed port from upstream of a co-rotating twin-screw extruder (STS-65, manufactured by Coperion) with a screw diameter of 62 mm and an L / D ratio of 48 (13 barrels). The extruder barrel temperature was set to 180°C to 240°C, the screw rotation speed was 120 rpm, and the output rate was 150 kg / h. Melt-kneading was performed. Finally, the resin was drawn out of the die in the form of a strand, passed through a water bath, cooled, and solidified. The strand was then cut into pellets using a pelletizer to obtain polyester elastomer resin composition pellets. The resulting polyester elastomer resin composition pellets were vacuum-dried at 80°C overnight and then subjected to various tests.

[0092] Resin Composition of Example 5 The above components were weighed in the proportions shown in Table 2, premixed in a mixer for 90 seconds, and then fed into the first main feed port from the upstream end of a 51 mm screw diameter, 14-barrel co-rotating twin-screw extruder (STS-50, manufactured by Coperion) with an L / D ratio of 48. The extruder barrel temperature was set to 180°C to 200°C, the screw rotation speed was 150 rpm, and the output rate was 80 kg / h. Melt-kneading was performed. Finally, the resin was drawn out of the die in the form of a strand, passed through a water bath, cooled, and solidified. The strand was then cut into pellets using a pelletizer to obtain polyester elastomer resin composition pellets. The resulting polyester elastomer resin composition pellets were vacuum-dried overnight at 80°C and then subjected to various tests.

[0093] Next, a foam molded article was produced using the polyester elastomer resin composition obtained above by the mold expansion method described above. A flat plate mold was used, consisting of a fixed mold and a movable mold. When clamped, a cavity measuring 100 mm in width, 100 mm in length, and 3 mm in thickness was formed. When cored back in the mold opening direction, a cavity of the same width and length, but with a thickness of 3 mm plus the amount of cored back (mm), was formed. Specifically, supercritical nitrogen was injected into the plasticization zone of an electric injection molding machine with a clamping force of 1800 kN, a screw diameter of 40 mm, and a screw stroke of 180 mm. The mold was then heated to a surface temperature of 50°C. After the external injection pressure and internal foaming pressure formed a non-foamed skin layer of 100 to 800 μm, the movable mold was moved 14 mm in the mold opening direction to expand the cavity volume and obtain a foam molded article.

[0094] Table 2 shows the composition and physical properties of each resin composition of the Examples, Comparative Examples and Reference Examples, as well as the evaluation results of the foamed molded articles obtained therefrom.

[0095]

[0096] As is clear from Table 2, in Examples 1 to 7, in which the MFR and acid value of the polyester elastomer resin composition were within the ranges of the present invention, the Dv / Dn was 4 or less, no or almost no coarse bubbles were observed, and the foam molded articles were composed of closed cells, with a high rebound resilience of over 60% and excellent compression recovery, with a 50% constant displacement repeated compression residual set of 10% or less. On the other hand, in Comparative Examples 1 to 7 and Reference Example 1, in which the MFR of the polyester elastomer resin composition exceeded the upper limit of the range of the present invention, the Dv / Dn exceeded 4, and the foam molded articles exhibited poor rebound resilience and compression recovery. In Comparative Example 8, in which the MFR was below the lower limit, the melt viscosity was too high, making high-magnification foaming difficult and also prone to gel formation. Furthermore, in Comparative Examples 1, 3, 4, and 6, in which the acid value of the polyester elastomer resin composition exceeded the upper limit of the present invention, the Δ(Dv / Dn) exceeded 0.5, and significant changes in cell size and physical properties occurred during continuous molding, making it difficult to continuously mold foams of consistent quality.

[0097] As can be seen from Comparative Examples 1 and 2 and Reference Examples 1 and 2, in which raw materials derived from biomass resources were used, the thickener had a lower effect of lowering the MFR than in Reference Examples 1 and 2, which used only raw materials derived from fossil fuel resources, and the reduced viscosity was low due to an incomplete polymerization reaction. In Comparative Examples 4 and 5, which had a high acid value, the addition of the thickener produced a gel-like substance. These findings show that when raw materials derived from biomass resources are used, satisfying the MFR and acid value requires not only the use of a thickener, as in Example 1, but also advanced design in combination with the melt-kneading conditions.

[0098] The polyester elastomer resin composition of the present invention, despite using a biomass-derived polyester elastomer with a high biobased content, retains the excellent mechanical properties, retention stability, and high-precision moldability of fossil-fuel-derived polyester elastomers, and also exhibits excellent foam moldability. Furthermore, foamed articles made therefrom exhibit a uniform foaming state despite a high expansion ratio, are lightweight, have excellent compression recovery, and a high rebound resilience. Therefore, the polyester elastomer resin composition of the present invention can be advantageously used as a cushioning material for footwear and other components, replacing fossil-fuel-derived polyester elastomers. This composition significantly contributes to solving environmental problems, such as the depletion of fossil fuel resources, and is extremely useful in the industry.

Claims

1. A polyester elastomer resin composition for foam molding, comprising a biomass resource-derived polyester elastomer, at least one of whose constituent components is derived from a biomass resource, and a heat stabilizer, wherein the polyester elastomer resin composition has a biobased content of 20 to 100%, the polyester elastomer resin composition has an MFR value of 0.5 to 20 g / 10 min (measurement temperature: melting point + 20°C) at a load of 2.16 kg measured in accordance with the flow test method for thermoplastics specified in JIS K7210, and the polyester elastomer resin composition has an acid value of 50 eq / ton or less.

2. The polyester elastomer resin composition for foam molding according to claim 1, characterized in that the biomass resource-derived polyester elastomer is a polyester elastomer having a hard segment composed of a polyester having an aromatic dicarboxylic acid and an aliphatic and / or alicyclic diol as its constituent components, and a soft segment composed of an aliphatic polyether as its constituent component, wherein the aromatic dicarboxylic acid and the aliphatic and / or alicyclic diol are derived from fossil fuel resources, and the aliphatic polyether is derived from biomass resources.

3. The polyester elastomer resin composition for foam molding according to claim 1, characterized in that the biomass resource-derived aliphatic polyether of the biomass resource-derived polyester elastomer is polytetramethylene ether glycol.

4. The polyester elastomer resin composition for foam molding according to claim 1, characterized in that the reduced viscosity of the biomass resource-derived polyester elastomer is 1.2 or more.

5. A polyester elastomer foam molded product obtained from the polyester elastomer resin composition according to any one of claims 1 to 4, characterized in that the polyester elastomer foam molded product has a rebound resilience of 60% or more.

6. A polyester elastomer foam molded product obtained from the polyester elastomer resin composition according to any one of claims 1 to 4, characterized in that the polyester elastomer foam molded product has a 50% constant displacement repeated compression residual strain of 10% or less.

7. A polyester elastomer foam molded product obtained from the polyester elastomer resin composition according to any one of claims 1 to 4, wherein the volume average cell diameter Dv and number average cell diameter Dn of the polyester elastomer foam molded product satisfy Dv / Dn≦4.

8. A footwear component comprising the polyester elastomer foamed molding according to any one of claims 5 to 7.

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