WO2023037957A1

WO2023037957A1 - Thermoplastic polyester elastomer resin composition and foam molded article

Info

Publication number: WO2023037957A1
Application number: PCT/JP2022/032961
Authority: WO
Inventors: 顕三大谷; 卓也赤石; 恵梨森尾
Original assignee: 東洋紡株式会社
Priority date: 2021-09-08
Filing date: 2022-09-01
Publication date: 2023-03-16
Also published as: TW202328335A

Abstract

[Problem] The present invention provides a thermoplastic polyester elastomer resin composition that is suitable for a foam molded article having excellent lightness of weight, impact resilience, and surface smoothness. Provided are: a thermoplastic polyester elastomer resin composition for foam molding using a counter-pressure, said thermoplastic polyester elastomer resin composition being characterized by containing 0.05-9.5 parts by mass of a crystal nucleating agent and 0-4.5 parts by mass of a thickener relative to 100 parts by mass of a thermoplastic polyester elastomer in which a hard segment that comprises a polyester including an aromatic dicarboxylic acid and an aliphatic and/or alicyclic diol as constituent components and at least one soft segment selected from an aliphatic polyether, an aliphatic polyester, and an aliphatic polycarbonate are bonded to each other such that the soft segment is contained in an amount of 25-90 mass%; and a foam molded article in which the thermoplastic polyester elastomer resin composition forms a continuous phase.

Description

THERMOPLASTIC POLYESTER ELASTOMER RESIN COMPOSITION AND EXPANDED MOLDED PRODUCT

The present invention relates to a thermoplastic polyester elastomer resin composition suitable for foam molding using counterpressure, and to a foam molded article in which the thermoplastic polyester elastomer resin composition forms a continuous phase. More specifically, the foam-molded article of the present invention is a foam-molded article excellent in rebound resilience and surface smoothness, and it is possible to provide a foam-molded article that has been expanded twice or more.

Thermoplastic polyester elastomers have excellent injection moldability and extrusion moldability, high mechanical strength, rubber-like properties such as elastic recovery, impact resistance, and flexibility, as well as excellent cold resistance. It is used in applications such as electronic parts, textiles, films, and sports parts.

Thermoplastic polyester elastomers have excellent heat aging resistance, light resistance, and wear resistance, so they are used in automotive parts, especially parts used in high-temperature environments and automotive interior parts. Furthermore, in recent years, the weight reduction of resin parts has been promoted, and one of the means for achieving the purpose is the application of foam molded articles.

As one of the methods of high-expansion expansion for weight reduction, there is a core-back injection foam molding method in which the mold is moved in the opening direction during foaming. Furthermore, since the cells in the foam layer are fine, the impact resilience is increased (Patent Document 1).

However, a foamed molded product manufactured by the core-back injection molding method has a non-foamed skin layer on the surface layer and the above-mentioned foamed layer on the inner layer, and has a sandwich structure of the non-foamed skin layer and the foamed layer in the thickness direction. The presence of the skin layer of the foam layer reduces the resilience of the foam layer, lowering the rebound resilience. In addition, defects such as swirl marks and avatars on the surface of the molded product cause unevenness, resulting in surface smoothness. inferior to

Also, with the short shot injection foam molding method, it is possible to produce a foam molded product with a thin skin layer, but there are problems such as a low foaming ratio and poor lightness (Patent Document 2).

By the way, as a foam that is suitably used for automobile seats, a highly resilient urethane foam having a modulus of rebound resilience of 60% or more is suitably employed, and Patent Document 3 proposes a method for producing the same. However, urethane foam generates cyanide gas and the like when burned, and thus poses a problem of environmental pollution.

Japanese Patent No. 6358369 JP 2011-68819 A Japanese Patent Application Laid-Open No. 2003-342343

The present invention has been made in view of the current state of the prior art described above, and an object of the present invention is to provide a thermoplastic polyester elastomer resin composition that is suitable for foamed moldings that are lightweight, have excellent impact resilience, and have excellent surface smoothness. It is in.

In order to achieve the above object, the present inventors diligently studied the composition of the thermoplastic polyester elastomer and the additives to be blended. As a result, the thermoplastic polyester elastomer has a specific ratio between the hard segment and the soft segment of the thermoplastic polyester elastomer, and is adjusted to a specific cooling crystallization temperature and melt viscosity by blending a crystal nucleating agent and a thickening agent. By using this thermoplastic polyester elastomer resin composition as a resin composition, good foam moldability with both fine foaming and surface smoothness is exhibited, and weight reduction by high expansion ratio foaming is possible, and extremely high It was found that a foam molded article having a modulus of rebound resilience can be obtained. Furthermore, by applying the foam injection molding method by the counter-pressure method in which a gas is injected into the cavity of the mold and the molten thermoplastic resin is injected under pressure, the above-mentioned high-quality polyester elastomer foam molding can be obtained. It has been found that it can be easily manufactured and provided. In other words, the properties (melt tension, crystallization temperature, gas retention, etc.) of the thermoplastic polyester elastomer resin composition are suitable for the foam molding method using the counterpressure method, and the process of pressurizing and releasing the counterpressure pressure is suitable. The inventors have found that it is possible to obtain a foam-molded article that can withstand high-expansion expansion and have the desired surface smoothness, and have completed the present invention.

That is, the present invention constitutes the following (1) to (8).
(1) A hard segment made of a polyester composed of an aromatic dicarboxylic acid and an aliphatic and / or alicyclic diol, and at least one selected from aliphatic polyethers, aliphatic polyesters, and aliphatic polycarbonates 0.05 to 9.5 parts by mass of a crystal nucleating agent (B) with respect to 100 parts by mass of a thermoplastic polyester elastomer (A) having a soft segment content of 25 to 90% by mass, and A thermoplastic polyester elastomer resin composition for foam molding using counterpressure, characterized by containing 0 to 4.5 parts by mass of a thickener (C).
(2) The thermoplastic polyester elastomer resin composition according to (1), wherein the crystal nucleating agent (B) is an alkali metal salt or alkaline earth metal salt of an organic carboxylic acid having 3 to 40 carbon atoms. .
(3) The thermoplastic polyester elastomer resin composition according to (1) or (2), wherein the thickener (C) is a reactive compound having an epoxy group.
(4) The thermoplastic polyester elastomer resin composition according to any one of (1) to (3), which has a cooling crystallization temperature TC2 of 105°C to 200°C.
(5) The thermoplastic polyester elastomer resin composition according to any one of (1) to (4), which has an MFR of 5 to 30 g/10 min at a load of 2,160 g and a measurement temperature of 230°C.
(6) The thermoplastic polyester elastomer resin composition according to any one of (1) to (5) is a foam-molded article having a continuous phase, and the surface layer of the foam-molded article to a depth of 1000 μm from the surface of the foam-molded article includes: A foamed molded article composed of a surface layer consisting only of a foamed region with no non-foamed portion having a cell density of 10% or less, or a foamed region having the non-foamed portion and the non-foamed portion. A foamed molded article having a surface layer in which non-foamed regions are mixed, and having a density of 0.01 to 0.70 g/cm ³ .
(7) The foam molding according to (6), characterized in that a flat cell layer having an average aspect ratio of cells of 4.0 to 15.0 is provided in the foamed region where the non-foamed portion of the surface layer does not exist. body.
(8) The foam molded article according to (6) or (7), further comprising a circular cell layer having an average aspect ratio of cells of 1.0 to 2.0 in the inner layer deeper than 1000 μm from the surface. .
(9) The foam molded article according to any one of (6) to (8), which has a rebound resilience of 50 to 90%.
(10) The foam molded article according to (8) or (9), wherein the cells of the circular cell layer of the inner layer have an average cell diameter of 10 to 350 μm and a maximum cell diameter of 100 to 1000 μm.

The foam molded article made of the thermoplastic polyester elastomer resin composition of the present invention is not only excellent in light weight, but also exhibits extremely high impact resilience and excellent surface smoothness. Furthermore, it has a uniform foaming state, high heat resistance, water resistance, and molding stability in spite of its high expansion ratio. can. Then, by using the foam injection molding method by the counter pressure method, even without post-processing such as cutting, by preparing a corresponding mold, it has the above-mentioned excellent characteristics. A foam molded article can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram for demonstrating an example of the manufacturing method of the foam molding of this invention. 1 is a schematic view of a foam molded article (B) of the present invention, (X) is a view from the surface, (Y) is a cross-sectional view taken along the plane ww', and (Z) is v. - It is sectional drawing cut by the plane of v'. 1 is a schematic view of a foam molded article (A) of the present invention, (X) is a view from the surface, (Y) is a cross-sectional view taken along the plane ww', and (Z) is v. - It is sectional drawing cut by the plane of v'.

The foam molded article of the present invention will be described in detail below.

[Thermoplastic polyester elastomer (A)]
The thermoplastic polyester elastomer (A) used in the present invention is formed by combining hard segments and soft segments. The hard segment consists of polyester. As the aromatic dicarboxylic acid that constitutes the polyester of the hard segment, ordinary aromatic dicarboxylic acids are widely used and are not particularly limited. 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, of the total dicarboxylic acids constituting the hard segment polyester. Other dicarboxylic acid components include aromatic dicarboxylic acids such as diphenyldicarboxylic acid, isophthalic acid and 5-sodiumsulfoisophthalic acid, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid and tetrahydrophthalic anhydride, succinic acid, glutaric acid, Aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, dimer acid, hydrogenated dimer acid, and the like are included. These can be used within a range that does not significantly lower the melting point of the resin, and the amount thereof is preferably 30 mol % or less, more preferably 20 mol % or less of the total acid component.

In addition, in the thermoplastic polyester elastomer (A) used in the present invention, general aliphatic or alicyclic diols are widely used as the aliphatic or alicyclic diol constituting the hard segment polyester, and are not particularly limited. is preferably an alkylene glycol having 2 to 8 carbon atoms. Specific examples include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol and the like. Among these, ethylene glycol or 1,4-butanediol is preferred.

The components constituting the hard segment polyester include butylene terephthalate units (units composed of terephthalic acid and 1,4-butanediol) or butylene naphthalate units (2,6-naphthalenedicarboxylic acid and 1,4-butanediol unit) is preferable from the viewpoint of physical properties, moldability and cost performance.

Further, when an aromatic polyester suitable as the polyester constituting the hard segment in the thermoplastic polyester elastomer (A) used in the present invention is produced in advance and then copolymerized with the soft segment component, the aromatic polyester is usually can be easily obtained according to the production method of polyester. Moreover, such polyester preferably has a number average molecular weight of 10,000 to 40,000.

The soft segment of the thermoplastic polyester elastomer (A) used in the present invention is at least one selected from aliphatic polyethers, aliphatic polyesters, and aliphatic polycarbonates.

Aliphatic polyethers include poly(ethylene oxide) glycol, poly(propylene oxide) glycol, poly(tetramethylene oxide) glycol, poly(hexamethylene oxide) glycol, poly(trimethylene oxide) glycol, co-polymer of ethylene oxide and propylene oxide. polymers, ethylene oxide adducts of poly(propylene oxide) glycol, copolymers of ethylene oxide and tetrahydrofuran, and the like. Among these, poly(tetramethylene oxide) glycol and ethylene oxide adducts of poly(propylene oxide) glycol are preferred from the viewpoint of elastic properties.

Aliphatic polyesters include poly(ε-caprolactone), polyenantholactone, polycaprylollactone, and polybutylene adipate. Among these, poly(ε-caprolactone) and polybutylene adipate are preferred from the viewpoint of elastic properties.

The aliphatic polycarbonate preferably consists mainly 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. In particular, aliphatic diols having 5 to 12 carbon atoms are preferred from the viewpoint of the flexibility and low-temperature properties of the resulting thermoplastic polyester elastomer. These components may be used alone, or two or more of them may be used in combination according to the cases described below.

As the aliphatic polycarbonate diol having good low-temperature properties, which constitutes the soft segment of the thermoplastic polyester elastomer (A) used in the present invention, those having a low melting point (for example, 70° C. or lower) and a low glass transition temperature are used. preferable. In general, an aliphatic polycarbonate diol composed of 1,6-hexanediol, which is used to form the soft segment of a thermoplastic polyester elastomer, has a low glass transition temperature of around -60°C and a melting point of around 50°C. Good low temperature characteristics are obtained. In addition, an aliphatic polycarbonate diol obtained by copolymerizing an appropriate amount of, for example, 3-methyl-1,5-pentanediol with the above aliphatic polycarbonate diol has a glass transition point higher than that of the original aliphatic polycarbonate diol. is slightly higher, but the melting point is lowered or becomes amorphous. In addition, for example, an 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 of about -70°C, which are sufficiently low. , which corresponds to aliphatic polycarbonate diols with good low-temperature properties.

From the viewpoint of solving the problems of the present invention, aliphatic polyethers are preferable as the soft segment of the thermoplastic polyester elastomer (A) used in the present invention.

The thermoplastic polyester elastomer (A) used in the present invention is preferably a copolymer containing terephthalic acid, 1,4-butanediol, and poly(tetramethylene oxide) glycol as main components. Among the dicarboxylic acid components constituting the thermoplastic polyester elastomer (A), terephthalic acid is preferably 40 mol% or more, more preferably 70 mol% or more, further preferably 80 mol% or more, 90 mol % or more is particularly preferred. The total amount of 1,4-butanediol and poly(tetramethylene oxide) glycol in the glycol component constituting the thermoplastic polyester elastomer (A) is preferably 40 mol% or more, more preferably 70 mol% or more. It is preferably 80 mol % or more, and particularly preferably 90 mol % or more.

The poly(tetramethylene oxide) glycol preferably has a number average molecular weight of 500-4000. If the number average molecular weight is less than 500, it may be difficult to develop elastomeric properties. On the other hand, if the number average molecular weight exceeds 4,000, the compatibility with the hard segment component may be lowered, making block-like copolymerization difficult. The number average molecular weight of poly(tetramethylene oxide) glycol is more preferably 800 or more and 3000 or less, further preferably 1000 or more and 2500 or less.

In the thermoplastic polyester elastomer (A) used in the present invention, the soft segment content is 25 to 90% by mass, preferably 40 to 90% by mass, more preferably 55 to 90% by mass, and still more preferably 65% by mass. ~90% by mass. If the content of the soft segment is less than 25% by mass, the crystallinity is high, resulting in poor impact resilience.

The thermoplastic polyester elastomer (A) used in the present invention can be produced by known methods. For example, a lower alcohol diester of a dicarboxylic acid, an excessive amount of a low molecular weight glycol, and a soft segment component are transesterified in the presence of a catalyst, and the resulting reaction product is polycondensed. A method of subjecting segment components to an esterification reaction in the presence of a catalyst and polycondensing the resulting reaction product. A hard segment polyester is prepared in advance, and a soft segment component is added to this to randomize it by transesterification. method, a method of linking the hard segment and the soft segment with a chain linking agent, and when poly(ε-caprolactone) is used for the soft segment, a method of adding the ε-caprolactone monomer to the hard segment. .

[Crystal nucleating agent (B)]
The crystal nucleating agent (B) in the present invention has the effect of forming foam nuclei, which are starting points for cell formation, and suppressing the expansion of cells in the cooling process from the molten state of the thermoplastic polyester elastomer resin composition during the foam molding process. It is not particularly limited as long as it is present, but the one that is highly effective in improving the cooling crystallization temperature (TC2) forms a large number of microcrystals of the thermoplastic polyester elastomer (A) in the foam molding process, It is particularly preferable in that expansion and connection of bubbles can be suppressed. As the crystal nucleating agent (B), an alkali metal salt or alkaline earth metal salt of an organic carboxylic acid having 3 to 40 carbon atoms or an inorganic crystal nucleating agent is used, from the viewpoint of improving foam nucleation and cooling crystallization temperature (TC2). preferred from

The alkali metal salt or alkaline earth metal salt of an organic carboxylic acid having 3 to 40 carbon atoms means an alkali metal salt or alkaline earth metal salt of an aliphatic, alicyclic or aromatic carboxylic acid having 3 to 40 carbon atoms. is. Preferred alkali metals are sodium, potassium and lithium, and preferred alkaline earth metals are magnesium and calcium. Among alkali metals and alkaline earth metals, alkali metals are preferred, and sodium is particularly preferred.
The organic carboxylic acid is preferably an aliphatic carboxylic acid, and the aliphatic group may have a linear or branched structure, and may have an unsaturated group. It may also be an organic carboxylic acid in which an aliphatic group is bonded to an alicyclic group, an aromatic group, or other substituents such as a hydroxyl group and a phosphoric acid ester group. The aliphatic carboxylic acid is more preferably a linear saturated aliphatic carboxylic acid.

Among the aliphatic carboxylic acids, propionic acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, oleic acid, linoleic acid, Montanic acid and the like are preferred, and among the alkali metal salts, sodium salts are preferred in terms of solubility in the thermoplastic polyester elastomer (A) and good crystal nucleation, as well as compatibility with the terminal carboxyl groups of the thermoplastic polyester elastomer (A). The interaction is particularly preferable from the viewpoint that a pseudo cross-linking effect is produced and the melt viscosity required for foam molding can be obtained.

The organic carboxylic acid of an alkali metal salt or an alkaline earth metal salt of an organic carboxylic acid having 3 to 40 carbon atoms is a fatty acid having 3 to 20 carbon atoms from the viewpoint of meltability and compatibility with the thermoplastic polyester elastomer (A). is preferably a group carboxylic acid, more preferably a linear saturated aliphatic carboxylic acid having 3 to 20 carbon atoms.
Among these, aliphatic carboxylic acid metal salts having less than 14 carbon atoms are preferable because they can improve the crystallization rate with a small amount.

When the crystal nucleating agent (B) is an inorganic crystal nucleating agent, it is not particularly limited as long as it is unmelted during melt processing and can form crystal nuclei in the cooling process, but talc and calcium carbonate are particularly preferred. The particle size of the inorganic crystal nucleating agent is preferably 0.1 to 10 μm, more preferably 0.5 to 6 μm. If the particle size exceeds 10 μm, it may act as a foreign substance and generate voids during foam molding, degrading the quality of the foamed product.

The content of the crystal nucleating agent (B) is 0.05 to 9.5 parts by mass, preferably 0.1 to 5 parts by mass, relative to 100 parts by mass of the thermoplastic polyester elastomer (A). It is preferably 0.1 to 3 parts by mass, more preferably 0.1 to 1.5 parts by mass.
When the content of the crystal nucleating agent (B) is less than 0.05 parts by mass, the effect of forming foam nuclei and the effect of improving the cooling crystallization temperature are small, and the desired cell size miniaturization effect is obtained. can't When the content of the crystal nucleating agent (B) exceeds 9.5 parts by mass, when the crystal nucleating agent (B) is a metal salt of an organic carboxylic acid having 3 to 40 carbon atoms, the metal salt has a pseudo-crosslinking effect on the polyester elastomer. is too high and the melt viscosity during foam molding becomes too high, resulting in poor foam moldability and making it impossible to obtain a foamed product with a low density. The specific gravity of the material increases, and the desired resilience and flexibility cannot be obtained.

[Thickener (C)]
The thickener (C) in the present invention is a reactive compound (hereinafter sometimes simply referred to as a reactive compound) having a functional group capable of reacting with the hydroxyl group or carboxyl group of the thermoplastic polyester elastomer (A). The reactive functional group is preferably at least one selected from an epoxy group (glycidyl group), an acid anhydride group, a carbodiimide group and an isocyanate group, and the functional group contains two or more per molecule. . The functional group is more preferably an epoxy group (glycidyl group). The thickener (C) in the present invention is preferably a reactive compound having an epoxy group (glycidyl group), a reactive compound having a carbodiimide group, and a reactive compound having an epoxy group (glycidyl group). is more preferred. Hereinafter, for example, a “reactive compound having an epoxy group (glycidyl group)” may be referred to as a “compound having an epoxy group”. The thickener (C) also acts as a cross-linking agent because it reacts with and bonds to the polymer chains of the thermoplastic polyester elastomer (A).

When the thickener (C) is a compound having an epoxy group, the polyfunctional epoxy compound having two or more epoxy groups, specifically 1,6-dihydroxynaphthalenediglycidyl having two epoxy groups Ether, 1,3-bis(oxiranylmethoxy)benzene, 1,3,5-tris(2,3-epoxypropyl)-1,3,5-triazine-2,4,6 with three epoxy groups (1H,3H,5H)-trione, diglycerol triglycidyl ether, 1-chloro-2,3-epoxypropane/formaldehyde/2,7-naphthalenediol polycondensate with four epoxy groups and pentaerythritol polyglycidyl ether is mentioned. Among them, a polyfunctional epoxy compound having heat resistance in its skeleton is preferable. Particularly preferred are bifunctional or tetrafunctional epoxy compounds having a naphthalene structure in the skeleton, or trifunctional epoxy compounds having a triazine structure in the skeleton. Consider the degree of increase in the solution viscosity of the thermoplastic polyester elastomer (A), the effect of efficiently lowering the acid value of the thermoplastic polyester elastomer (A), and the degree of gelation due to aggregation and solidification of the epoxy itself. Difunctional or trifunctional epoxy compounds are then preferred.

In addition, a vinyl aromatic monomer (X) containing 2 or more glycidyl groups per molecule and having a weight average molecular weight of 4000 to 25000, and 20 to 99% by mass of glycidyl (X) and 1 to 80% by mass of glycidyl (meth) A copolymer consisting of an acrylate (Y) and a vinyl group-containing monomer (Z) other than the epoxy group-free (X) in an amount of 0 to 79% by mass can be mentioned.

As the thickening agent (C) used in the present invention, a vinyl aromatic monomer (X) containing two or more glycidyl groups per molecule and having a weight average molecular weight of 4000 to 25000 and 20 to 99% by mass, 1 to 80% by mass of glycidyl (meth)acrylate (Y) and 0 to 79% by mass of a vinyl group-containing monomer (Z) other than (X) containing no epoxy group, It is preferable because it has good compatibility with the thermoplastic polyester elastomer (A) and widens the molecular weight distribution. More preferably, (X) is 20 to 99% by mass, (Y) is 1 to 80% by mass, and (Z) is 0 to 40% by mass. 10 to 75% by mass of (Y) and 0 to 35% by mass of (Z). Since these compositions affect the concentration of functional groups that contribute to the reaction with the thermoplastic polyester elastomer (A), they are preferably controlled within the above range.

Examples of the vinyl aromatic monomer (X) include styrene and α-methylstyrene. Examples of the glycidyl (meth)acrylate (Y) include glycidyl (meth)acrylate, (meth)acrylic acid esters having a cyclohexene oxide structure, and (meth)acryl glycidyl ethers. glycidyl (meth)acrylate is preferred in terms of high Examples of vinyl group-containing monomers (Z) other than (X) containing no epoxy group include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and butyl (meth)acrylate. , 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, stearyl (meth)acrylate, methoxyethyl (meth)acrylate, etc. chain) (meth)acrylic acid alkyl esters, (meth)acrylic acid polyalkylene glycol esters, (meth)acrylic acid alkoxyalkyl esters, (meth)acrylic acid hydroxyalkyl esters, (meth)acrylic acid dialkylaminoalkyl esters esters, benzyl (meth)acrylates, phenoxyalkyl (meth)acrylates, isobornyl (meth)acrylates, alkoxysilylalkyl (meth)acrylates, and the like. In addition, (meth)acrylamide, (meth)acryldialkylamide, vinyl esters such as vinyl acetate, aromatic vinyl monomers such as vinyl ethers and (meth)allyl ethers, α-olefin monomers such as ethylene and propylene can also be used as the vinyl group-containing monomer (Z) other than the epoxy group-free (X).

The weight average molecular weight of the copolymer is preferably 4,000 to 25,000. The weight average molecular weight is more preferably 5000-15000. If the weight-average molecular weight is less than 4,000, the unreacted copolymer may volatilize during the molding process or bleed out onto the surface of the molded article, causing surface contamination. On the other hand, if the weight-average molecular weight exceeds 25,000, the reaction with the thermoplastic polyester elastomer (A) will be slow, resulting in an insufficient effect of increasing the molecular weight. Since the compatibility is deteriorated, there is a high possibility that the properties inherent in the thermoplastic polyester elastomer (A), such as heat resistance, are deteriorated.

The epoxy value of the copolymer is preferably 400 to 2500 equivalents/1×10 ⁶ g, more preferably 500 to 1500 equivalents/1×10 ⁶ g, still more preferably 600 to 1000 equivalents/1×10 ⁶ g. If the epoxy value ^is less than 400 equivalents/1×10 ⁶ g, the effect of thickening may not be exhibited. May have adverse effects.

When the thickener (C) is a compound having a carbodiimide group, a polycarbodiimide compound can be used. A polycarbodiimide compound is advantageous in that it efficiently reduces the acid value.

The polycarbodiimide compound that can be used in the invention may be any polycarbodiimide having two or more carbodiimide groups (structure of -N=C=N-) in one molecule, for example, aliphatic polycarbodiimide, alicyclic polycarbodiimides, aromatic polycarbodiimides and copolymers thereof. Aliphatic polycarbodiimide compounds or alicyclic polycarbodiimide compounds are preferred.

A polycarbodiimide compound can be obtained, for example, by a decarbonization reaction of a diisocyanate compound. Diisocyanate compounds that can be used here include, for example, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, and 2,4-tolylene diisocyanate. , 2,6-tolylene diisocyanate, 1,5-naphthylene diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, methylcyclohexane diisocyanate, tetramethylxylylene diisocyanate, 1,3,5-triisopropylphenylene-2,4-diisocyanate and the like. These may be used alone, or two or more may be copolymerized and used. Also, a branched structure may be introduced, or a functional group other than a carbodiimide group or an isocyanate group may be introduced by copolymerization. Furthermore, although the terminal isocyanate can be used as it is, the degree of polymerization may be controlled by reacting the terminal isocyanate, or a portion of the terminal isocyanate may be blocked.

As the polycarbodiimide compound, alicyclic polycarbodiimides derived from dicyclohexylmethane diisocyanate, cyclohexane-1,4-diisocyanate, isophorone diisocyanate, etc. are particularly preferred, and polycarbodiimides derived from dicyclohexylmethane diisocyanate and isophorone diisocyanate are particularly preferred.

The polycarbodiimide compound preferably contains 2 to 50 carbodiimide groups per molecule in terms of stability and handleability. More preferably, it contains 5 to 30 carbodiimide groups per molecule. The number of carbodiimides in a polycarbodiimide molecule (that is, the number of carbodiimide groups) corresponds to the degree of polymerization in the case of polycarbodiimide obtained from a diisocyanate compound. For example, the degree of polymerization of polycarbodiimide obtained by connecting 21 diisocyanate compounds in a chain is 20, and the number of carbodiimide groups in the molecular chain is 20. Generally, polycarbodiimide compounds are mixtures of molecules of various lengths and the number of carbodiimide groups is expressed as an average value. If it has the number of carbodiimide groups in the above range and is solid at around room temperature, it can be pulverized, so that it has excellent workability and compatibility when mixed with the thermoplastic polyester elastomer (A), uniform reactivity, and bleed-out resistance. is also preferable. The number of carbodiimide groups can be measured, for example, by a conventional method (method of dissolving with amine and performing back titration with hydrochloric acid).

The polycarbodiimide compound preferably has an isocyanate group at its end and an isocyanate group content of 0.5 to 4% by mass in terms of stability and handleability. More preferably, the isocyanate group content is 1-3% by mass. In particular, polycarbodiimide derived from dicyclohexylmethane diisocyanate or isophorone diisocyanate and having an isocyanate group content within the above range is preferred. The isocyanate group content can be measured by a conventional method (method of dissolving with amine and performing back titration with hydrochloric acid).

When the thickener (C) is a compound having an isocyanate group, the above polycarbodiimide compound containing the isocyanate group and the isocyanate compound that is the raw material of the above polycarbodiimide compound can be mentioned.

When the thickener (C) is a compound having an acid anhydride group, a compound containing 2 to 4 anhydride groups per molecule is preferable in terms of stability and handling. Examples of such compounds include phthalic anhydride, trimellitic anhydride, and pyromellitic anhydride.

In the present invention, the thickener (C) is a component necessary for imparting the melt viscosity necessary for foam molding. , it may not contain the thickener (C).

The content of the thickener (C) is 0 to 4.5 parts by mass with respect to 100 parts by mass of the thermoplastic polyester elastomer (A), and when included, preferably 0.05 to 4.5 parts by mass. parts, more preferably 0.1 to 4 parts by mass, and still more preferably 0.1 to 3 parts by mass.
When the thickener is contained, if it is less than 0.05 parts by mass, the targeted molecular chain elongation effect is insufficient, and if it exceeds 4.5 parts by mass, the thickening effect becomes excessive and adversely affects moldability. and affect the mechanical properties of the molded product. When the thickener (C) is an epoxy compound, if it exceeds 4.5 parts by mass, the surface of the molded product may become uneven due to cohesive hardening of the epoxy compound. When the thickener (C) is a carbodiimide compound, if it exceeds 4.5 parts by mass, the thermoplastic polyester elastomer (A) is hydrolyzed due to the basicity of the polycarbodiimide compound, which tends to affect the mechanical properties. .

As the thickener (C), a compound having an epoxy group, in particular, a vinyl aromatic monomer containing two or more glycidyl groups per molecule, a weight average molecular weight of 4000 to 25000, and 20 to 99% by mass. (X), 1 to 80% by mass of glycidyl (meth)acrylate (Y), and 0 to 79% by mass of a vinyl group-containing monomer (Z) other than (X) that does not contain an epoxy group. Polymers are preferred. When a compound having a highly reactive functional group such as a carbodiimide group is used in combination with an epoxy compound, the resin composition tends to have a narrow molecular weight distribution after thickening. Therefore, there is a possibility that the injection pressure during injection molding increases, the foam nuclei disappear, and the expansion ratio decreases. Therefore, in the resin composition of the present invention, it is preferable not to use both an epoxy compound and a carbodiimide compound as the thickener (C).

[Thermoplastic polyester elastomer resin composition]
Furthermore, the thermoplastic polyester elastomer (A) used in the present invention is blended with various additives, fillers, and other polymers in addition to the crystal nucleating agent (B) and the thickening agent (C) according to the purpose. can do. The type of additive is not particularly limited, and various additives commonly used in foam molding can be used. Specifically, additives include known hindered phenol-based, sulfur-based, phosphorus-based, and amine-based antioxidants, hindered amine-based antioxidants, benzotriazole-based, benzophenone-based, benzoate-based, triazole-based, nickel-based, and salicylic acid antioxidants. light stabilizers such as systems, ultraviolet light absorbers, lubricants, fillers, flame retardants, flame retardant aids, release agents, antistatic agents, molecular modifiers such as peroxides, metal deactivators, organic and inorganic Nucleating agents, neutralizers, antacids, antibacterial agents, fluorescent whitening agents, organic and inorganic pigments and dyes, as well as organic and inorganic compounds used for flame retardancy and heat stability. Examples include inorganic phosphorus compounds. The blending amount (content) of additives, fillers, and other types of polymers can be appropriately selected within a range that does not impair the formation of air bubbles, etc., and the blending amount (content) used for molding ordinary thermoplastic resins can be adopted. In the thermoplastic polyester elastomer resin composition of the present invention, the total of the thermoplastic polyester elastomer (A), the crystal nucleating agent (B) and the thickening agent (C) preferably accounts for 80% by mass or more, and preferably 90% by mass. % or more, more preferably 95 mass % or more.

The thermoplastic polyester elastomer resin composition of the present invention can be produced by mixing the components described above and, if necessary, various additives, fillers, and other polymers, followed by melt-kneading. Any melt-kneading method known to those skilled in the art may be used, and a single-screw extruder, twin-screw extruder, pressure kneader, Banbury mixer, or the like can be used. Among them, it is preferable to use a twin-screw extruder.

As a method for determining the composition and composition ratio of the thermoplastic polyester elastomer (A) used in the present invention, it is also possible to calculate from the proton integral ratio of ¹ H-NMR measured by dissolving the sample in a solvent such as heavy chloroform. It is possible.

The cooling crystallization temperature TC2 of the thermoplastic polyester elastomer resin composition of the present invention is preferably 105°C to 200°C. TC2 is measured by the method described in the Examples section below. When TC2 is within this range, uniform fine foaming becomes possible during foam molding of the thermoplastic polyester elastomer resin composition, and the impact resilience of the obtained foam molded product can be further improved. TC2 is more preferably 108 to 190°C, even more preferably 110 to 185°C.

The MFR (melt flow rate) of the thermoplastic polyester elastomer resin composition of the present invention is 5 to 30 g when measured at a load of 2,160 g and a measurement temperature of 230° C. according to the measurement method described in ASTM D1238. /10 min is preferred. Further, since the MFR is 5 to 30 g/10 min, when the thermoplastic polyester elastomer resin composition is foam-molded, the cell walls are less likely to be broken, and a foam-molded product having a high expansion ratio and having fine cells formed therein can be obtained. Obtainable. In particular, it is effective in foam molding using counter pressure, which will be described later. When the MFR is less than 5 g/10 min, the fluidity tends to be low and the foam followability tends to be low. MFR is more preferably 8 to 30 g/10 min.

When the thickener (C) is included, the thermoplastic polyester elastomer resin composition of the present invention may contain a reaction product obtained by reacting the thermoplastic polyester elastomer (A) and the thickener (C). However, the thermoplastic polyester elastomer (A) that has not reacted with the thickener (C) or the free thickener (C) may be contained. This is because it is difficult to completely react the thermoplastic polyester elastomer (A) and the thickener (C). The relationship between the contents of the thermoplastic polyester elastomer (A) and the thickener (C) described above is such that in the thermoplastic polyester elastomer resin composition, the thickener (C ) is considered in terms of the mass derived from This content relationship is the same for the foam molded article described later.

[Foam molding]
The foam molded article of the present invention is obtained using the thermoplastic polyester elastomer resin composition described above, and is not subjected to any post-processing such as cutting. In other words, it is a compact having no cutting surface. In this case, the cut surface means the surface obtained by cutting the non-foamed skin layer, etc. from the foam molded product, and does not refer to the surface generated when unnecessary parts such as gates derived from the mold are removed. do not have.

The foamed molded article of the present invention has a surface layer (hereinafter referred to as a surface layer ( A)), or a surface layer ( Hereinafter, it is a foam molded article (B) having a surface layer (B). Here, the term "surface layer" refers to a surface layer consisting of a single surface. For example, in the case of a rectangular parallelepiped foam molded article, there are six surface layers, one of which is referred to. In the case of a cuboid-shaped foamed molded article, the foamed molded article (A) consists of the surface layer (A) on all six sides, and the foamed molded article (B) consists of the surface layer (B) on at least one side. . Therefore, it is a cuboid-shaped foamed molded product, in which the upper and lower surfaces consist only of foamed regions with non-foamed parts, and the side faces consist only of foamed regions without non-foamed parts (so-called core-back injection foam molding). The foamed molded article having a non-foamed skin layer produced by the method) does not correspond to the above foamed molded article (B). In the foamed molded article (B), the area of the foamed region where the non-foamed portion exists is preferably 60% or less, more preferably 50% or less, and even more preferably 30% or less, out of the area of the single surface. If the area of the foamed region in which the non-foamed portion exists is 0%, the foamed molded article (A) is obtained. In addition, in the foamed molded article (B), the area of the foamed region where the non-foamed portion exists is preferably 50% or less, more preferably 40% or less, and even more preferably 25% or less, relative to the total surface area of the foamed molded article. The foam molded article (A) has an improved impact resilience because the surface layer of the foam molded article does not have a non-foamed portion where no air bubbles are present. In the foamed molded article (B) described above, the foamed region in which the non-foamed portion exists has few cells, so the rebound resilience is low, and the foamed region in which the non-foamed portion does not exist has a high rebound resilience. It is possible to have different impact resilience depending on the location. The surface of the foam molded article of the present invention does not necessarily have to be flat, and may be curved or have projections. One of the points of the present invention is that a foam molded article having any desired shape can be obtained by preparing a corresponding mold.

The above-mentioned non-foamed portion refers to a phase formed of a thermoplastic polyester elastomer resin composition with almost no cells, and is a portion with a cell density of 10% or less. Here, the cell density is calculated by image-processing a cross-sectional photograph of a sample for cross-sectional observation of the surface layer of the foam molded article taken with a scanning electron microscope. Specifically, it is as described in the section of Examples. In the foamed molded article of the present invention, the portion that does not correspond to the non-foamed portion is called a foamed portion or a foamed layer. The surface of the foamed portion is made of an extremely thin resin layer (so-called skin) formed by the contact of the molten resin composition before foaming or the foamed molten resin composition with the mold surface, and the thickness thereof is 50 μm or less. be. In the present invention, the non-foamed portion with a cell density of 10% or less is measured in an area of 200 μm × 200 μm, so the thin resin layer on the surface of the foamed portion is “a non-foamed portion with a cell density of 10% or less”. does not fall under

The foamed molded article of the present invention does not have a sandwich structure in which non-foamed layers are provided on both sides of a foamed layer (in other words, a structure in which a foamed layer is sandwiched between non-foamed layers from both sides). The foam-molded article of the present invention is the foam-molded article (A) or the foam-molded article (B) described above. In other words, the foamed molded article (A) is a foamed molded article that has no non-foamed layer and is composed of a single foamed layer. It becomes a foamed molded article in which a non-foamed portion (non-foamed skin layer) exists only in the part. The size of the foam-molded article of the present invention is not particularly limited, and a foam-molded article of a desired size can be obtained as long as the mold can be manufactured.

In the present invention, bubbles with an aspect ratio of 2.0 or less are considered circular bubbles, and bubbles with an aspect ratio of more than 2.0 are considered flat bubbles.
In the foamed molded article of the present invention, it is preferable that a flat cell layer having a large average aspect ratio of cells exists in the foamed region where the non-foamed portion of the surface layer does not exist. The average aspect ratio of the flat cell layer is preferably 4.0 to 15.0, because the flat cells in the surface layer have a large aspect ratio, so that the surface of the foamed molded product becomes smooth and excellent in appearance. If it is less than 4.0, unevenness will occur on the surface of the molded product, and the surface smoothness will be impaired. and the surface smoothness tends to be impaired. In order to have excellent surface smoothness, the average aspect ratio of the flat cell layer is more preferably 4.0 to 10.0. Furthermore, it is preferable that a circular cell layer with a small average aspect ratio of cells exists in the inner layer deeper than 1000 μm from the surface. Since the circular cells in the inner layer improve rebound resilience by reducing the aspect ratio, the average aspect ratio of the circular cell layer is preferably 1.0 to 2.0. tend to decline. The reason why the cells in the surface layer become flat cells is that the resin composition flows along the surface of the mold during foam molding. The foamed molded article of the present invention preferably has a flat cell layer having an average aspect ratio of cells of 4.0 to 15.0 in the foamed region where the non-foamed portion of the surface layer does not exist. It is a preferred embodiment to have a circular cell layer with an average aspect ratio of cells of 1.0 to 2.0 in the inner layer deeper than 1000 μm.

The foam layer is composed of a resin continuous phase and independent cells. Here, the resin continuous phase means a portion having no cavities formed by the cured thermoplastic polyester elastomer resin composition. The bubbles in the circular bubble layer in the inner layer deeper than 1000 μm from the surface described above have different characteristics depending on their size, as long as their diameters (cell diameters) are uniform and without variation. A smaller cell diameter is more advantageous for developing high impact resilience, and specifically, an average cell diameter of 10 to 350 μm is preferable. When the average cell diameter is less than 10 μm, the internal pressure of the molded product is low, and the pressure during the formation of the non-foamed skin layer is insufficient, which tends to deteriorate the appearance such as sink marks. On the other hand, when the average cell diameter exceeds 350 μm, the load resistance tends to be low and the impact resilience tends to be low. In addition, even if the average cell diameter is small, the rebound resilience is inferior if the density is high. It is preferably 100-300 μm, particularly preferably 130-300 μm. Further, most of the circular bubble layer is composed of fine bubbles having an average cell diameter of 10 to 350 μm as described above, but also includes coarse bubbles having a slightly larger cell diameter. In the process of foam molding, when the molten resin composition and the foaming agent are melt-mixed in the molding machine, the melt viscosity of the molten resin composition decreases during continuous molding. It is presumed that the composition and the foaming agent are difficult to melt and mix uniformly, and that the foaming agent is unevenly dispersed. In order to develop high impact resilience, the maximum cell diameter of coarse cells is preferably 100 to 1000 μm. If the maximum cell diameter exceeds 1000 μm, the load resistance tends to be low and the impact resilience tends to be low. Also, the maximum cell diameter is more preferably 200 to 1000 μm, still more preferably 400 to 950 μm, in order to achieve a density for exhibiting high impact resilience, which will be described later.

The density of the foam molded article of the present invention is preferably 0.01 to 0.70 g/cm ³ . Since the density of general polyester elastomers is about 1.0 to 1.4 g/cm ³ , it can be said that the foamed molded article of the present invention is sufficiently lightweight. More preferably 0.1 to 0.60 g/cm ³ , still more preferably 0.1 to 0.45 g/cm ³ , particularly preferably 0.1 to 0.35 g/cm ³ . If the density is less than 0.01 g/cm ³ , sufficient strength cannot be obtained and mechanical properties tend to be poor, and if it exceeds 0.70 g/cm ³ , impact resilience tends to be poor.

The foam molded article of the present invention has an average cell diameter within a specific range and a density within a specific range, and as a result, can achieve a high impact resilience. Furthermore, by appropriately selecting the configuration described above, it is possible to achieve a higher impact resilience of 50 to 90%. In order to develop high resilience characteristics, the rebound resilience of the foam molded product is preferably 60 to 90%.

The foam molded article of the present invention is not only excellent in light weight, but also exhibits an extremely high impact resilience and is excellent in surface smoothness. Furthermore, it is intended to provide a polyester-based foam-molded article that can be applied to parts that require high reliability because it has a uniform foaming state, high heat resistance, water resistance, and molding stability in spite of its high expansion ratio. can be done. Therefore, for example, it can be used for the following purposes. However, the uses of the foamed molded article of the present invention are not limited to the following uses.
Applications include automotive materials, civil engineering supplies, building supplies, home appliances, OA equipment, sporting goods, stationery, toys, medical supplies, food containers, and agricultural materials. Specific examples include automotive mechanical members, engine components, automotive exterior materials, automotive interior materials, cushioning materials, sealing materials, car seats, deadening, door trims, sun visors, vibration damping materials, sound absorbing materials, and heat insulating materials for automobiles (heat insulation materials), anti-vibration materials, cushioning materials, civil engineering joints, icicle prevention panels, protective materials, lightweight soil, embankments, artificial soil, tatami mat core materials, construction heat insulation materials, construction joint materials, side door materials, construction curing materials, reflections materials, industrial trays, tubes, pipe covers, air conditioner insulation pipes, gasket core materials, concrete formwork, televisions, refrigerators, freezers, cooking equipment, washing machines, air conditioning equipment, lighting fixtures, computers, magneto-optical discs, copiers, facsimiles , printers, shoes, protectors, gloves, and sports equipment.

[Method for producing foam molded product]
As for the foaming method of the foamed molded article of the present invention, a foaming method of impregnating the thermoplastic polyester elastomer resin composition with a high-pressure gas and then reducing the pressure (releasing the pressure) is preferable. Among them, as a molding method for achieving molding cycleability, cost, and uniform foaming, gas is injected into the cavity of the mold when melt-mixing the foaming agent and the thermoplastic polyester elastomer resin composition and performing injection molding. A foam injection molding method based on a counterpressure method in which a molten thermoplastic polyester elastomer resin composition is injected under pressure is preferred. Specifically, as shown in FIG. 1, a pressurizing nitrogen gas is injected into a cavity 3 formed by a plurality of clamped molds 1 and 2 using a counter pressure device 8 to obtain a predetermined pressure. Pressure is applied to create a pressurized state, and a molten thermoplastic polyester elastomer resin composition is added thereto as a chemical foaming agent and/or a supercritical inert gas (hereinafter collectively referred to as "foaming agent"). Immediately after the filling of the resin composition is completed or after a predetermined period of time, the gas applied to the cavity is rapidly discharged from the electromagnetic valve 10 by counterpressure, and the thermoplastic polyester elastomer resin is injected. The composition foams. The predetermined pressure is preferably 0.01 MPa to 29.0 MPa. The pressure referred to here is gauge pressure. The predetermined time is preferably 1 to 60 seconds. Here, immediately before removing the gas applied to the cavity by the rapid counterpressure described above, at the same time as removing the gas, immediately after removing the gas, or after a predetermined time after removing the gas, one mold is 2 can be moved in the mold opening direction to expand the volume of the cavity 3, thereby combining with a core-back injection foam molding method for obtaining a foam molded product.

The thermoplastic polyester elastomer resin composition and the foaming agent can be mixed in the plasticizing region 4 a of the injection molding machine 4 before filling the cavity 3 . When performing foam molding as described above, by appropriately adjusting the counterpressure gas pressure and the filling amount of the resin composition according to the material, it is possible to obtain a foam molded article having the desired expansion ratio and impact resilience. . The gas pressure of the counter pressure affects the fineness of the bubbles and the foaming ratio, and by applying even a low pressure to the cavity, the decompression speed is improved and high foaming ratio can be achieved. In addition, when a high pressure is applied, gas escape of the foaming agent from the resin composition is suppressed, and the cells tend to become finer. . Therefore, the counter pressure is preferably 0.01 MPa to 29.0 MPa, more preferably 0.05 MPa to 15.0 MPa, still more preferably 0.5 MPa to 10.0 MPa. The pressure referred to here is gauge pressure. If the filling amount of the resin composition is large, the expansion ratio will be low, and if it is small, the expansion ratio will be high and the impact resilience will be high. Therefore, the filling amount of the resin composition is preferably 10% to 55% of the cavity volume, more preferably 10% to 50%, still more preferably 10% to 40%, and particularly preferably 10% to 30%. %. By carrying out the foam molding under the conditions as described above, it is possible to obtain a foam molded product that is lightweight and has a high impact resilience.

The reason why the foamed molded article of the present invention is the foamed molded article (A) or the foamed molded article (B) described above will be explained. FIG. 2 shows a schematic structure of the foam molded article (B). The foamed molded article (A) does not have the foamed region 25 where the non-foamed portion 21 exists in the foamed molded article (B), and has a structure consisting only of the foamed region 24 where the non-foamed portion 21 does not exist. As described above, the cavity of the mold pressurized by counter pressure is filled with the thermoplastic polyester elastomer resin composition in a molten state together with a foaming agent within a range of 10% to 55% of the cavity volume. However, at that time, a part of the molten resin composition is cooled by contact with the mold to form a non-foamed portion. Then, when the pressure in the cavity is released, foaming occurs in the thermoplastic polyester elastomer resin composition, and a foamed molded article is obtained. A compact (B) is obtained. On the other hand, when the molten resin composition does not touch the mold during filling, even if it touches, the area is very small, and even if it touches, the pressure inside the cavity is released before it is sufficiently cooled. A foam molded article (A) is obtained in which the foamed portion is not formed on the surface layer. When the thermoplastic polyester elastomer resin composition is foamed, it flows along the surface of the mold near the surface of the foamed region where the non-foamed portion of the surface layer does not exist, so the cells become flat cells.

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

When a chemical foaming agent is used as the foaming agent, the chemical foaming agent is based on a thermoplastic resin having a lower melting point than the decomposition temperature of the chemical foaming agent in order to be uniformly dispersed in the thermoplastic polyester elastomer resin composition. It can also be used as a blowing agent masterbatch. The base thermoplastic resin is not particularly limited as long as it has a melting point lower than the decomposition temperature of the chemical foaming agent. Examples thereof include polystyrene (PS), polyethylene (PE), and polypropylene (PP). In this case, the mixing ratio of the chemical foaming agent and the thermoplastic resin is preferably 10 to 100 parts by mass of the chemical foaming agent per 100 parts by mass of the thermoplastic resin. If the amount of the chemical blowing agent is less than 10 parts by mass, the amount of the masterbatch to be added to the thermoplastic polyester elastomer resin composition may become too large, resulting in deterioration of physical properties. If it exceeds 100 parts by mass, it becomes difficult to form a masterbatch due to the problem of dispersibility of the chemical blowing agent.

When using a supercritical inert gas as the foaming agent, carbon dioxide and/or nitrogen can be used as the inert gas. When supercritical carbon dioxide and/or nitrogen is used as a blowing agent, the amount thereof is preferably 0.05 to 30 parts by mass, preferably 0.1 to 20 parts by mass, per 100 parts by mass of the thermoplastic polyester elastomer resin composition. Parts by mass are more preferred. If the amount of supercritical carbon dioxide and/or nitrogen is less than 0.05 parts by mass, it will be difficult to obtain uniform and fine bubbles, and if it exceeds 30 parts by mass, the surface appearance of the molded article will tend to be impaired.

Although carbon dioxide or nitrogen in a supercritical state used as a blowing agent can be used alone, carbon dioxide and nitrogen may be mixed and used. Nitrogen tends to be suitable for forming finer cells with respect to the thermoplastic polyester elastomer resin composition, and carbon dioxide allows a relatively large amount of gas to be injected, thereby obtaining a higher expansion ratio. Therefore, they may be mixed arbitrarily depending on the state of the foamed structure prepared, and the mixing ratio in the case of mixing is preferably in the range of 1:9 to 9:1 in terms of molar ratio.

As the foaming agent used in the present invention, nitrogen in a supercritical state is more preferable from the viewpoint of uniform fine foaming.

In order to inject the molten thermoplastic polyester elastomer resin composition together with the foaming agent into the cavity 3, the molten thermoplastic polyester elastomer resin composition and the foaming agent are mixed in the plasticizing region 4a of the injection molding machine 4. do it. In particular, when supercritical carbon dioxide and/or nitrogen is used as the foaming agent, for example, as shown in FIG. A method of injecting into the injection molding machine 4 or the like can be adopted. These carbon dioxide and/or nitrogen must be in a supercritical state inside the molding machine from the viewpoint of solubility, permeability, and diffusibility in the molten thermoplastic polyester elastomer resin composition. .

Here, the supercritical state means that when the temperature and pressure of a substance that produces a gas phase and a liquid phase are increased, the distinction between the gas phase and the liquid phase can be lost in a certain temperature range and pressure range. The temperature and pressure at this time are called critical temperature and critical pressure. In other words, a substance in a supercritical state has the properties of both gas and liquid, so the fluid produced in this state is called a critical fluid. Such a critical fluid has a higher density than a gas and a lower viscosity than a liquid, so it has the property of diffusing in a substance very easily.

Examples are given below to demonstrate the effects of the present invention, but the present invention is not limited by these examples.

The following raw materials were used in the following examples and comparative examples.
thermoplastic polyester elastomer (A);
(Polyester elastomer A-1)
According to the method described in JP-A-9-59491, dimethyl terephthalate, 1,4-butanediol, and poly (tetramethylene oxide) glycol having a number average molecular weight of 2000 are used as raw materials, and the soft segment content is 76% by mass. to produce polyester elastomer A-1.
(Polyester elastomer A-2)
According to the method described in JP-A-9-59491, dimethyl terephthalate, 1,4-butanediol, and poly (tetramethylene oxide) glycol having a number average molecular weight of 2000 are used as raw materials, and the soft segment content is 83% by mass. to produce polyester elastomer A-2.
(Polyester elastomer A-3)
According to the method described in JP-A-9-59491, dimethyl terephthalate, 1,4-butanediol, and poly (tetramethylene oxide) glycol having a number average molecular weight of 1000 as raw materials, the soft segment content is 67% by mass. to produce polyester elastomer A-3.
(Polyester elastomer A-4)
According to the method described in JP-A-9-59491, using dimethyl terephthalate, 1,4-butanediol, and poly(tetramethylene oxide) glycol having a number average molecular weight of 1000 as raw materials, the soft segment content is 55% by mass. to produce polyester elastomer A-4.
(Polyester elastomer A-5)
According to the method described in JP-A-9-59491, dimethyl terephthalate, 1,4-butanediol, and poly (tetramethylene oxide) glycol having a number average molecular weight of 1000 as raw materials, the soft segment content is 28% by mass. to produce polyester elastomer A-5.

crystal nucleating agent (B);
I prepared the following:
Sodium caprylate (manufactured by Nitto Kasei Kogyo Co., Ltd., melting point 220°C)
Sodium stearate (manufactured by NOF Corporation, melting point 230°C)
Magnesium stearate (manufactured by Tannan Chemical Industry Co., Ltd., melting point 135°C)
Talc (manufactured by Hayashi Kasei Co., Ltd., KCM7500, particle size 5.8 μm)

thickener (C);
(Compound with epoxy group: styrene copolymer)
The oil jacket temperature of a 1 liter pressurized stirred tank reactor equipped with an oil jacket was kept at 200°C. On the other hand, a monomer mixture consisting of 89 parts by weight of styrene (St), 11 parts by weight of glycidyl methacrylate (GMA), 15 parts by weight of xylene (Xy) and 0.5 parts by weight of ditertiarybutyl peroxide (DTBP) as a polymerization initiator. The liquid was charged into the raw material tank. This was continuously supplied from the raw material tank to the reactor at a constant supply rate (48 g/min, residence time: 12 minutes), and the reaction liquid was discharged from the outlet of the reactor so that the content liquid mass of the reactor was constant at about 580 g. continuously extracted from The internal temperature of the reactor at that time was kept at about 210°C. After 36 minutes have passed since the temperature inside the reactor has stabilized, the extracted reaction liquid is led to a thin film evaporator kept at a pressure reduction of 30 kPa and a temperature of 250 ° C., and volatile components are continuously removed. A polymer was obtained. This styrene-based copolymer had a mass average molecular weight of 8,500 and a number average molecular weight of 3,300 according to GPC analysis (converted to polystyrene). The epoxy value is 670 equivalents/1×10 ⁶ g, the epoxy value (average number of epoxy groups per molecule) is 2.2, and two or more glycidyl groups are present in one molecule.
(Compound with epoxy group: TEPIC-S)
Commercially available epoxy compounds ("TEPIC-S" manufactured by Nissan Chemical Industries, Ltd., 1,3,5-tris(2,3-epoxypropyl)-1,3,5-triazine-2,4,6(1H,3H,5H )-trione) was prepared.
(Compound with carbodiimide group: LA-1)
A commercially available polycarbodiimide (“Carbodilite LA-1” manufactured by Nisshinbo Co., Ltd.) was prepared.

[Thermoplastic polyester elastomer resin composition]
According to the formulation shown in Table 1, a thermoplastic polyester elastomer, a crystal nucleating agent, and a thickening agent are melt-kneaded using a twin-screw extruder, and then pelletized to obtain pellets of the thermoplastic polyester elastomer resin composition. Obtained. The physical properties of each resin composition were measured by the method described later and were as shown in Table 1.

[Cooling crystallization temperature (TC2)]
With a differential scanning calorimeter "DSC220 type" manufactured by Seiko Electronics Industry Co., Ltd., 5 mg of the measurement sample is placed in an aluminum pan, the lid is pressed and sealed, melted in nitrogen at 250 ° C. for 2 minutes, and then the temperature is lowered. The exothermic peak temperature of cooling crystallization obtained when the temperature was lowered to 50° C. at 20° C./min was taken as the cooling crystallization temperature (TC2).

[MFR]
The MFR (melt flow rate) of the thermoplastic polyester elastomer resin composition was measured at a load of 2,160 g and a measurement temperature of 230° C. according to the measurement method described in ASTM D1238. For the measurement, a thermoplastic polyester elastomer resin composition dried (100° C., 3 to 5 hours) so that the moisture content was 0.1% by mass or less was used.

Examples 1-12, Comparative Examples 1-4
Next, using the thermoplastic polyester elastomer resin composition obtained above, a foam molded article was produced by the above-described counterpressure method. The mold used had a mold clamping force of 10000 kN and formed a cavity with a width of 360 mm, a length of 190 mm and a thickness of 15.0 mm when clamped. Nitrogen gas at the pressure shown in Table 1 (counterpressure pressure) was injected into the cavity of this mold using a counterpressure. In the plasticizing area of an electric injection molding machine having a screw with a screw diameter of 60 mm and a screw stroke of 300 mm, nitrogen in a supercritical state was injected into the molten thermoplastic polyester elastomer resin composition to control the surface temperature to 50°C. A short shot of the resin composition shown in Table 1 (filling amount of resin composition relative to cavity volume) was injected into the cavity of the mold from the gate (the center of the surface with a width of 360 mm and a length of 190 mm). Immediately after filling, the thermoplastic polyester elastomer resin composition was foamed to obtain a foam-molded article by quickly releasing the nitrogen gas pressurized by counter pressure.

Comparative example 5
A foam molded article was produced by a mold expansion method (core-back injection foam molding method). As for the mold, when the mold is clamped, a cavity with a width of 360 mm, a length of 190 mm, and a thickness of 3.0 mm can be formed. A mold for making a flat plate was used, which consisted of a fixed mold and a working mold capable of forming a cavity with an amount (mm). Specifically, in the plasticizing region of an electric injection molding machine having a screw with a mold clamping force of 10,000 kN, a screw diameter of 60 mm, and a screw stroke of 300 mm, nitrogen in a supercritical state was injected to bring the surface temperature to 50 ° C. After injection filling a full pack into a temperature-controlled mold, at the stage where a non-foamed skin layer of about 700 μm is formed by the external injection pressure and the foaming pressure from the inside, the working mold is moved in the mold opening direction by 12.0 mm. It was moved to expand the volume of the cavity to obtain a foamed molding.

The foam molded articles obtained in Examples 1 to 12 and Comparative Examples 1 to 5 were evaluated as follows. Table 1 shows the results.

[Composition of foam]
The surface of the foam molded article was visually observed, and the presence or absence of unevenness (sink marks) due to molding shrinkage and the occurrence of burrs were estimated as to whether or not there was a non-foamed portion. In the case of a foamed molded article that has unevenness and/or an avatar and is presumed to have a non-foamed portion, cut the foamed molded body along the plane where the non-foamed portion is in the center (the ww' plane in FIG. 2) and observe the cross section. was used as a sample. Further, the foamed molded product was cut along a plane (vv' plane in FIG. 2) perpendicular to the cut plane to obtain a sample for cross-sectional observation. In the case of a foamed molded article that is assumed to have no irregularities or avatars and no non-foamed portions, the foamed molded article is cut at the center plane of the foamed article (the ww' plane in FIG. 3) and used as a sample for cross-sectional observation. bottom. Further, the foam molded product was cut along a plane (vv' plane in FIG. 3) perpendicular to the cut plane to obtain a sample for cross-sectional observation.
Using a scanning electron microscope SU1510 manufactured by Hitachi High-Technologies Corporation, a cross-sectional photograph of a sample for cross-sectional observation of the surface layer of the foam molded product was taken. The cross-sectional photograph is image-processed, and in the surface layer from the surface of the foamed molding to a depth of 1000 μm, the cell density is calculated by the following formula in an area of 200 μm × 200 μm. It was made into a foaming part.
Bubble density (%) = [Total area of bubbles (μm ² )/40,000 (μm ² )] × 100
The observation area of 200 μm × 200 μm is the surface layer from the surface to a depth of 1000 μm in the case of a foamed molded article that is assumed to have a non-foamed portion, near the surface, near the depth of 500 μm, and near the depth of 1000 μm (surface in FIG. In the case of a foamed molded product that is assumed to have no non-foamed portions, the surface layer from the surface to a depth of 1000 μm is located near the surface, at a depth of 500 μm, and at a depth of 500 μm. Measurements were taken at five locations near 1000 μm (the depth of the white squares on the surface layer 22 in FIG. 3). When it was determined that no non-foamed portion existed in all three locations in the depth direction from the surface by this measurement, the region was defined as a region consisting only of a foamed region in which no non-foamed portion existed.
As a result, the presence or absence of non-foamed portions is determined, and the foamed molded article (A) composed of a surface layer consisting of only foamed regions without non-foamed portions, and the presence of foamed regions with non-foamed portions and non-foamed portions. Foamed molded article (B) having a surface layer with a mixture of non-foamed foamed areas (B), and foamed molded article (C) having a surface layer consisting of only foamed areas with non-foamed parts (non-foamed skin layer) bottom.

[Ratio of area of foamed region where non-foamed part exists]
In the surface layer (B) of the foamed molded article (B), a foamed region in which a non-foamed portion exists is specified by visual observation or the above cross-sectional photograph in the area of the surface of the foamed molded article, and the ratio of the area was calculated by the following formula. If the foam molded article (B) has a plurality of surfaces corresponding to the surface layer (B), the one with the larger ratio is adopted.
Ratio (%) of area of foamed region in which non-foamed portion exists = [Area of foamed region in which non-foamed portion exists (mm ² )/Area of surface of foamed molded product (mm ² )] × 100

[Ratio of area of foamed region where non-foamed part exists to total surface area]
The "area of the foamed region where the non-foamed portion exists" was specified in the same manner as in the above-mentioned "ratio of the area of the foamed region where the non-foamed portion exists". When the foam molded article (B) had a plurality of surfaces corresponding to the surface layer (B), the "areas of foamed regions where non-foamed portions exist" of all surfaces were totaled. The ratio of the area of the foamed region where the non-foamed portion exists to the total surface area of the foamed molded article (B) was calculated by the following equation.
The ratio of the area of the foamed region where the non-foamed portion exists to the total surface area (%) = [area of the foamed region where the non-foamed portion exists (mm ² )/surface area of the foamed molded product (mm ² )] × 100

[Average aspect ratio of cells in flat cell layer and circular cell layer]
Using a scanning electron microscope SU1510 manufactured by Hitachi High-Technologies Corporation, a cross-sectional photograph of a sample for cross-sectional observation of a foam molded product was taken. It was confirmed that there was a layer of flat cells in the surface layer up to a depth of 1000 μm from the surface and a layer of circular cells in the inner layer deeper than 1000 μm from the surface. Cross-sectional photographs were image processed and the major and minor axes of at least 100 adjacent flat and circular cells were measured with a vernier caliper. The average aspect ratio (long axis length/short axis length) of 100 of them is obtained, and this is performed at any three points on each layer, and the average value of the three average values obtained at three points are the average aspect ratios of the flat cell layer and the circular cell layer, respectively.

[Density (apparent density)]
The dimensions of the foam molded article were measured with vernier calipers, and the mass was measured with an electronic balance and calculated by the following formula.
Density (g/cm ³ )=mass of foamed molded article/volume of foamed molded article

[Average cell diameter/maximum cell diameter of bubbles in circular bubble layer]
When measuring the average aspect ratio of the bubbles in the circular bubble layer, the area circle equivalent diameter of the circular bubbles was taken as the cell diameter, and the average value of 100 of them was determined. This was performed at three arbitrary locations of the circular cell layer, and the average value of the three average values obtained at the three locations was taken as the average cell diameter.
In addition, the largest cell diameter among the observed cell diameters of the bubbles was taken as the maximum cell diameter.

[Rebound resilience]
Measurement was carried out by the method described in JIS K 6400. Using a manual measurement tester, a steel ball was dropped from a prescribed drop height (H) onto the foam molded body, the maximum rebound height (h) was read, and the rebound resilience was calculated using the following formula. .
Rebound resilience (%) = (maximum rebound height (h) / drop height (H)) x 100
The measurement was performed three times within one minute, the median value was obtained, and the rebound resilience was calculated. The rebound resilience of the foamed region without the non-foamed portion was defined as the rebound resilience (A), and the rebound resilience of the foamed region with the non-foamed portion was defined as the rebound resilience (B).

[Surface smoothness]
The surface smoothness of the foamed molding was visually observed and evaluated in three grades as follows.
○: Unevenness is observed on the surface of the molded article △: Unevenness is observed on part of the surface of the molded article ×: Unevenness is observed on the entire surface of the molded article

[Mold followability]
14. In the mold cavity shape of width 360 mm, length 190 mm, and thickness 15.0 mm, if the thickness of the molded product after foaming is 14.0 mm or more, it means that it can follow the mold. If it was less than 0 mm, it was regarded as "x" because it could not follow the mold.

As is clear from Table 1, any of Examples 1 to 12 within the scope of the present invention is a foamed molded article (A) composed of a surface layer consisting only of a foamed region with no non-foamed portion, or The foam molded article (B) has a surface layer in which a foamed region with a non-foamed portion and a foamed region without a non-foamed portion are mixed. Since the average cell diameter and the maximum cell diameter of the cells of the foam have predetermined sizes, the foam exhibits light weight and high impact resilience. The foamed molded articles (B) of Examples 3 to 8, 10 to 12, and Comparative Examples 1 to 4 all had a non-foamed portion with the maximum area on the surface opposite to the surface with the gate. The surface also had a non-foamed portion of approximately the same area. In addition, from Examples 3 to 8 and 10 to 12, it can be seen that the foamed regions without non-foamed portions have a higher rebound resilience than the foamed regions with non-foamed portions. Furthermore, in Examples 1, 2, and 9, the entire foamed molded article is composed only of foamed regions without non-foamed portions, and the vicinity of the surface of the entire foamed molded article is composed of flat cells, resulting in excellent surface smoothness. . On the other hand, in Comparative Example 1, a polyester elastomer containing no crystal nucleating agent or thickening agent was foam-molded, and in Comparative Example 2, a thermoplastic polyester elastomer resin composition containing a small amount of crystal nucleating agent was foam-molded. Although the coefficient of rebound resilience shows a high value, the maximum cell diameter of the cells in the circular cell layer is increased, so that compared with Examples 3 to 8 using the same polyester elastomer A-1, the rebound Elastic modulus is reduced. In Comparative Example 3 with a large amount of crystal nucleating agent and Comparative Example 4 with a large amount of thickener, the values are lower than the predetermined MFR. Mold conformability deteriorates. In Comparative Example 5, foam molding was performed by the core-back injection foam molding method, and the weight reduction was sufficiently achieved, but the entire foam molded body was composed of a sandwich structure of a non-foam layer and a foam layer. Moreover, as a result, unevenness occurs on the entire surface of the molded product, resulting in poor surface smoothness.

Possibility of industrial use

The foamed molded article of the present invention not only excels in lightness, but also exhibits an extremely high rebound resilience and excellent surface smoothness. Furthermore, it is intended to provide a polyester foam molded article that can be applied to parts that require high reliability because it has a uniform foaming state, high heat resistance, water resistance, and molding stability in spite of its high expansion ratio. can be done.

1 mold (for fixing)
2 Mold (for operation)
3 Cavity 4 Injection molding machine 4a Plasticizing region 5 Gas cylinder 6 Boosting pump 7 Pressure control valve 8 Counter pressure device 9 Intake electromagnetic valve 10 Exhaust electromagnetic valve 21 Non-foamed portion 22 Surface layer 23 Inner layer 24 Foam without non-foamed portion Region 25 Foamed region with non-foamed portions

Claims

A hard segment made of a polyester composed of an aromatic dicarboxylic acid and an aliphatic and / or alicyclic diol, and at least one soft segment selected from aliphatic polyethers, aliphatic polyesters, and aliphatic polycarbonates. 0.05 to 9.5 parts by mass of a crystal nucleating agent (B) and a thickener with respect to 100 parts by mass of a thermoplastic polyester elastomer (A) that is bonded and has a soft segment content of 25 to 90% by mass. (C) A thermoplastic polyester elastomer resin composition for foam molding using counterpressure, characterized by containing 0 to 4.5 parts by mass.
The thermoplastic polyester elastomer resin composition according to claim 1, wherein the crystal nucleating agent (B) is an alkali metal salt or alkaline earth metal salt of an organic carboxylic acid having 3 to 40 carbon atoms.
The thermoplastic polyester elastomer resin composition according to claim 1, wherein the thickener (C) is a reactive compound having an epoxy group.
The thermoplastic polyester elastomer resin composition according to claim 1, characterized in that the cooling crystallization temperature TC2 is from 105°C to 200°C.
The thermoplastic polyester elastomer resin composition according to claim 1, characterized in that the MFR at a load of 2,160 g and a measurement temperature of 230°C is 5 to 30 g/10 min.
The thermoplastic polyester elastomer resin composition according to any one of claims 1 to 5 is a foam molded article forming a continuous phase, and the surface layer of the foam molded article to a depth of 1000 µm has a cell density of 10%. A foamed molded article composed of a surface layer consisting only of a foamed region without non-foamed portions, or a foamed region with the non-foamed portion and a foamed region without the non-foamed portion. A foamed molded article having a surface layer with a density of 0.01 to 0.70 g/cm 3 .
The foamed molded article according to claim 6, wherein the foamed region of the surface layer where there is no non-foamed portion has a flat cell layer with an average aspect ratio of cells of 4.0 to 15.0.
The foamed molded article according to claim 6, further comprising a circular cell layer having an average aspect ratio of cells of 1.0 to 2.0 in an inner layer deeper than 1000 µm from the surface.
The foam molded article according to claim 6, characterized by having a rebound resilience of 50 to 90%.
9. The foam molded article according to claim 8, wherein the cells of the circular cell layer of the inner layer have an average cell diameter of 10 to 350 μm and a maximum cell diameter of 100 to 1000 μm.