JP2018172535A - Ester-based elastomer foam molding and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ester-based elastomer foam molding having high shape freedom, and excellent shape recovery property and rebound resistance.SOLUTION: An ester-based elastomer foam molding is formed of a fused body of foam particles containing an ester-based elastomer containing a hard segment formed of a dicarboxylic acid component and a diol component and a soft segment formed of aliphatic polyether and/or polyester as a base material resin, and has a thickness of 5-1,000 mm, a density of 0.02-0.4 g/cmand an average air bubble diameter of 10-300 μm.SELECTED DRAWING: None

Description

  The present invention relates to an ester-based elastomer foam molding and a method for producing the same. More specifically, the present invention relates to an ester elastomer foamed molded article having a high degree of freedom in shape and having excellent shape recovery and rebound resilience and a method for producing the same.

Conventionally, as a cushioning material, a foam molded body of polyurethane resin or ethylene-vinyl acetate copolymer resin has been widely used. A foamed molded article using these resins is formed, for example, by foaming a mixture of a resin and a foaming agent in a mold. Since these resins have excellent flexibility, it is said that the properties can be imparted to the foamed molded product. However, there is a problem that it is difficult to use in applications that require high impact resilience.
Further, a foamed sheet obtained by extrusion foaming an ester-based elastomer that is a kind of elastomer resin has been proposed (Japanese Patent Laid-Open No. 2000-327822: Patent Document 1). Since ester elastomer itself has high strength and high resilience, it is said that these properties can be imparted to the foam sheet.

JP 2000-327822 A

  The foam sheet is relatively thin and has a relatively simple shape. Therefore, in order to obtain a three-dimensional and thick cushion material, midsole, and the like from the foam sheet, it is necessary to laminate a plurality of foam sheets or to bond them together. For this reason, there are problems in terms of shape flexibility and cost.

The inventors of the present invention have a high degree of freedom in shape when a foamed molded body composed of a fused product of foamed particles using an ester-based elastomer as a base resin has a specific thickness, density and average cell diameter. The present invention has been found to provide a foamed molded article having excellent shape recoverability and rebound resilience.
Thus, according to the present invention, foamed particles using as a base resin an ester elastomer containing a hard segment composed of a dicarboxylic acid component and a diol component and a soft segment composed of an aliphatic polyether and / or polyester. There is provided an ester-based elastomer foam-molded article having a thickness of 5 to 1000 mm, a density of 0.02 to 0.4 g / cm ³ , and an average cell diameter of 10 to 300 μm. The
Moreover, according to the present invention, there is provided a method for producing the ester elastomer foamed molded article,
It includes a step of foaming expandable particles containing a foaming agent using an ester-based elastomer as a base resin to obtain foamed particles, and a step of obtaining a foamed molded product by foaming the foamed particles in a mold. A method for producing an ester-based elastomer foam molding is provided.

  ADVANTAGE OF THE INVENTION According to this invention, it can provide the ester-type elastomer foaming molding which has a high shape freedom degree, and has the outstanding shape recovery property and rebound resilience, and its manufacturing method.

Also, in any of the following cases, an ester elastomer foamed molded article having a higher degree of freedom in shape and having better shape recovery and rebound resilience and a method for producing the same can be provided.
(1) The ester elastomer foamed molded article has a compression set of 0 to 15%, a rebound resilience of 50 to 100%, and a closed cell ratio of 60 to 100%.
(2) An ester-based elastomer foam molding is used as a cushioning material.
Furthermore, in the method for producing an ester-based elastomer foam molded article, the base resin has an MFR of 0.1 to 30 g / 10 min (temperature: 190 ° C., load: 21.18 N) and / or a melt tension of 0.1 to 20 cN. When it has, it can manufacture an ester elastomer foaming molding more simply.

The ester elastomer foamed molded product of the present invention (hereinafter simply referred to as foam molded product) is composed of a fused product of foamed particles using an ester elastomer as a base resin.
(1) Ester-based elastomer The ester-based elastomer is not particularly limited as long as it provides a foamed molded article exhibiting high resilience and low density. For example, an ester elastomer containing a hard segment and a soft segment can be mentioned.

The hard segment is composed of, for example, a dicarboxylic acid component and a diol component.
Examples of the dicarboxylic acid component include aliphatic dicarboxylic acids such as oxalic acid, malonic acid, and succinic acid, and derivatives thereof, and components derived from aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, and derivatives thereof.
Examples of the diol component include C _2-10 alkylene glycol such as ethylene glycol, propylene glycol, and butanediol (for example, 1,4-butanediol), (poly) oxy C _2-10 alkylene glycol, and C _5-12 cycloalkanediol. Bisphenols or their alkylene oxide adducts. The hard segment may have crystallinity.

As the soft segment, a polyether type segment and / or a polyester type segment can be used.
Examples of the polyether type soft segment include a segment derived from an aliphatic polyether such as polyalkylene glycol (for example, polyoxyethylene glycol, polyoxypropylene glycol, polyoxytetramethylene glycol). The number average molecular weight of the polyether may be in the range of 200 to 10000, in the range of 200 to 6000, or in the range of 300 to 5000.
Polyester type soft segments include dicarboxylic acids (aliphatic C _4-12 dicarboxylic acids such as adipic acid) and diols (C _2-10 alkylene glycol such as 1,4-butanediol, ethylene glycol, etc. Aliphatic polyesters such as polycondensates with (poly) oxy C _2-10 alkylene glycol), polycondensates of oxycarboxylic acids and ring-opening polymers of lactones (C _3-12 lactones such as ε-caprolactone). Can be mentioned. The polyester type soft segment may be amorphous. Specific examples of the polyester as the soft segment include polyesters of C _2-6 alkylene glycol such as caprolactone polymer, polyethylene adipate, polybutylene adipate, and C _6-12 alkanedicarboxylic acid. The number average molecular weight of this polyester may be in the range of 200 to 15000, in the range of 200 to 10000, or in the range of 300 to 8000.

The soft segment includes a polyester having a polyether unit such as a copolymer of an aliphatic polyether and a polyester (polyether-polyester), a polyether such as a polyoxyalkylene glycol (for example, polyoxytetramethylene glycol). And a segment derived from polyester of an aliphatic dicarboxylic acid.
20: 80-90: 10 may be sufficient as the mass ratio of a hard segment and a soft segment, 30: 70-90: 10 may be sufficient, and 30: 70-80: 20 may be sufficient, 40: 60-80: 20 may be sufficient and 40: 60-75: 25 may be sufficient.
Further, when the dicarboxylic acid component is a terephthalic acid component and other dicarboxylic acid components, the ester elastomer contains a hard segment in a proportion of 30 to 80% by mass and contains a dicarboxylic acid component other than the terephthalic acid component. It may be included at a ratio of ˜30% by mass. The proportion of the dicarboxylic acid component other than the terephthalic acid component may be 5 to 25% by mass, 5 to 20% by mass, or 10 to 20% by mass. In addition, the ratio of the dicarboxylic acid component can be obtained by quantitatively evaluating the NMR spectrum of the resin.
The dicarboxylic acid component other than the terephthalic acid component is preferably an isophthalic acid component. By including the isophthalic acid component, the degree of crystallinity of the elastomer tends to be lowered, and the foam moldability is improved, so that a foamed article having a lower density can be obtained.
As the ester-based elastomer, a PELPLENE series or a VYLON series manufactured by Toyobo Co., Ltd. can be suitably used. In particular, it is preferable to use the perprene series.

(2) Base resin The base resin preferably has an MFR of 0.1 to 30 g / 10 min (temperature: 190 ° C., load: 21.18 N). The base resin preferably has a melt tension of 0.1 to 20 cN. If the MFR is less than 0.1 g / 10 min, the surface of the foamed molded product may not be smooth because the resin cannot be sufficiently softened during molding. If it is larger than 30 g / 10 min, shrinkage occurs during foaming, which may make molding difficult. The MFR may be in the range of 0.1 to 25 g / 10 min, may be in the range of 0.1 to 20 g / 10 min, may be in the range of 0.1 to 15 g / 10 min. The range of 3-15 g / 10min may be sufficient. When the melt tension is less than 0.1 cN, shrinkage occurs during foaming, which may make molding difficult. If it is greater than 20 cN, the surface of the foamed molded product may not be smooth because the resin cannot be sufficiently softened during molding. The range of 0.1-18 cN may be sufficient as melt tension, the range of 0.1-16 cN may be sufficient, the range of 0.1-14 cN may be sufficient, and it is the range of 0.1-12 cN. There may be.
The base resin may contain other resins in addition to the ester-based elastomer as long as the effects of the present invention are not impaired. The other resin may be a known thermoplastic resin or thermosetting resin.

In addition, the base resin may contain a flame retardant, a colorant, an antistatic agent, a spreading agent, a plasticizer, a flame retardant aid, a crosslinking agent, a filler, a lubricant, and the like.
Examples of the flame retardant include hexabromocyclododecane and triallyl isocyanurate hexabromide.
Examples of the colorant include inorganic pigments such as carbon black, graphite, and titanium oxide, organic pigments such as phthalocyanine blue, quinacridone red, and isoindolinone yellow, and special pigments such as metal powder and pearl.
Examples of the antistatic agent include polyoxyethylene alkylphenol ether and stearic acid monoglyceride.
Examples of the spreading agent include polybutene, polyethylene glycol, and silicone oil.

(3) Foam molded body The foam molded body may have a thickness of 5 to 1000 mm. When the thickness is less than 5 mm, the degree of freedom of shape of the foamed molded product may be lowered. When the thickness is larger than 1000 mm, the heat of the heating medium is not sufficiently transmitted to the mold center at the time of molding, and the strength of the foamed molded product may be reduced. The thickness may be in the range of 5 to 800 mm, in the range of 7 to 800 mm, in the range of 9 to 800 mm, or in the range of 9 to 600 mm.
The foamed molded product may have a density of 0.02 to 0.4 g / cm ³ . When the density is larger than 0.4 g / cm ³ , the lightweight property of the foamed molded product may be lowered. When the density is less than 0.02 g / cm ³ , the foamed molded product may shrink to cause poor appearance or the strength may decrease. Density may be in the range of 0.04~0.4g / cm ^3, it may be in the range of 0.06~0.4g / cm ^3, the 0.06~0.3g / cm ³ It may be a range.
The foamed molded product may have an average cell diameter of 10 to 300 μm. When the average cell diameter is smaller than 10 μm, the foamed molded product may shrink and cause poor appearance. When the average cell diameter is larger than 300 μm, the fusion between the expanded particles may be deteriorated, and the strength may be lowered. The average cell diameter may be in the range of 20 to 300 μm, in the range of 20 to 280 μm, or in the range of 20 to 260 μm.

The foamed molded product may have a compression set of 0-15%. When the compression set is larger than 15%, it becomes difficult to use in an environment where compression stress is applied. The compression set may be in the range of 0-13% or in the range of 0-11%.
The foamed molded product may have a rebound resilience of 50 to 100%. When the impact resilience is lower than 50%, it becomes difficult to use in applications where impact resilience is required.
The foamed molded product may have a closed cell ratio of 60 to 100%. When the closed cell ratio is lower than 60%, it is difficult to apply internal pressure, and moldability may be deteriorated. The closed cell ratio may be in the range of 65 to 100% or may be in the range of 70 to 100%.
Foam moldings are, for example, midsole, insole, outsole, etc. constituting the sole of shoes, core materials for sports equipment such as rackets and bats, protective equipment for sports equipment such as pads and protectors, pads and Medical / nursing / welfare / healthcare products such as protectors, tire cores such as bicycles and wheelchairs, interior materials, seat cores, shock absorbing members, vibration absorbing members, fenders, floats, etc. for transportation equipment such as automobiles It can be used for shock absorbing materials, toys, floor base materials, wall materials, railway vehicles, airplanes, beds, cushions and the like. The foamed molded product of the present invention can be used for any or all of a midsole, an insole and an outsole. Known midsole, insole and outsole can be used for any of the midsole, insole and outsole in which the foamed molded article of the present invention is not used.
The foamed molded product can take an appropriate shape according to the use.

(4) Manufacturing method of foam molded body The foam molded body is obtained by foaming foamed particles in a mold, and is composed of a fusion product of a plurality of foamed particles. For example, foamed particles (pre-expanded particles) are filled into a closed mold having a large number of small holes, and the foamed particles are heated and foamed with pressurized steam to fill the voids between the foamed particles, and the foamed particles are fused together. And can be obtained by integrating them. At that time, for example, the density of the foamed molded product can be adjusted by adjusting the filling amount of the foamed particles in the mold.
Furthermore, the foaming particles may be impregnated with an inert gas or air (hereinafter referred to as an inert gas or the like) to improve the foaming power of the foamed particles (internal pressure application step). By improving the foaming force, the fusibility between the foamed particles is improved at the time of foaming in the mold, and the foamed molded article has further excellent mechanical strength. In addition, as an inert gas, a carbon dioxide, nitrogen, helium, argon etc. are mentioned, for example.
As a method of impregnating the expanded particles with an inert gas or the like, for example, a method of impregnating the expanded particles with an inert gas or the like by placing the expanded particles in an atmosphere of an inert gas or the like having a pressure equal to or higher than normal pressure. Is mentioned. The expanded particles may be impregnated with an inert gas before filling into the mold. Alternatively, the foamed particles may be impregnated by filling the mold with the mold and then placing the mold in an inert gas atmosphere. When the inert gas is nitrogen, the foamed particles may be left in a nitrogen atmosphere with a gauge pressure of 0.1 to 2 MPa for 20 minutes to 24 hours.

When the foamed particles are impregnated with an inert gas or the like, the foamed particles may be heated and foamed in a mold as they are. Alternatively, the foamed particles may be heated and foamed before filling into the mold to form foamed particles with low bulk density, and then filled into the mold and heated and foamed. By using such low bulk density foamed particles, a low density foamed molded article can be obtained.
Moreover, when the anti-fusing agent described below is used during the production of the expanded particles, the anti-adhesive agent may be molded while adhering to the expanded particles during the production of the foamed molded article. Further, in order to promote the fusion between the foamed particles, the anti-fusing agent may be removed by washing before the molding step, and without removing it, stearic acid or the like as a fusion accelerator during molding may be used. It may be added.

(A) Method for Producing Expanded Particles Expanded particles can be obtained through a step of foaming expandable particles (foaming step).
The expanded particles may have a bulk density in the range of 0.015 to 0.4 g / cm ³ . When the bulk density is less than 0.015 g / cm ³ , shrinkage occurs in the obtained foam molded article, the appearance is not good, and the mechanical strength of the foam molded article may be lowered. If it is larger than 0.4 g / cm ³ , the lightweight property of the foamed molded product may be lowered. The bulk density may be 0.03~0.4g / cm ^3, it may be 0.05 to 0.4 g / cm ^3.
The shape of the expanded particles is not particularly limited, and examples thereof include a true sphere, an oval sphere (egg), a columnar shape, a prismatic shape, a pellet shape, and a granular shape.
The expanded particles may have an average particle diameter of 1 to 15 mm. When the average particle diameter is less than 1 mm, it is difficult to produce foamed particles, and the production cost may increase. When it is larger than 15 mm, the filling property into the mold may be lowered when the foamed molded product is produced by in-mold foaming. Here, the average particle diameter of the foamed particles (excluding the average particle diameter of the foamed particles in the fused product) was determined by measuring the maximum value and the minimum value of the diameters of the 20 foamed particles, and (maximum value + minimum value). ) ÷ means the average value calculated from 2.
In the foaming step, the foaming temperature and the heating medium are not particularly limited as long as the foamable particles can be foamed to obtain foamed particles.

In the foaming step, an anti-fusing agent (for example, polyoxyethylene polyoxypropylene glycol) may be added to the foamable particles. The addition amount of the anti-fusing agent may be in the range of 0.03 to 0.3 parts by mass or in the range of 0.05 to 0.25 parts by mass with respect to 100 parts by mass of the expandable particles. If the anti-fusing agent is less than 0.03 parts by mass, the anti-fusing effect may not be sufficiently obtained. When the amount of the anti-fusing agent is more than 0.3 parts by mass, the strength of the foamed molded product may be reduced, or the cleaning cost may increase.
Prior to foaming, powder metal soaps such as zinc stearate, calcium carbonate, and aluminum hydroxide may be applied to the surface of the foamable particles. By this application, the bonding between the expandable particles in the foaming process can be reduced. Moreover, you may apply | coat surface treatment agents, such as an antistatic agent and a spreading agent.

(B) Manufacturing method of expandable particle Expandable particle can be obtained through the process (impregnation process) which makes a resin particle impregnate a foaming agent and obtains expandable particle.
The foaming agent may be an organic gas or an inorganic gas. Examples of the inorganic gas include air, nitrogen, carbon dioxide (carbon dioxide gas), and the like. Examples of the organic gas include hydrocarbons such as propane, butane, and pentane, and fluorine-based blowing agents. As for the said foaming agent, only 1 type may be used and 2 or more types may be used together.
The amount of the foaming agent contained in the base resin may be 1 to 12 parts by mass with respect to 100 parts by mass of the base resin. When the amount is less than 1 part by mass, the foaming force is low, and it is difficult to foam well. When the content of the foaming agent exceeds 12 parts by mass, the bubble film tends to be broken, the plasticizing effect becomes too large, the viscosity at the time of foaming tends to decrease, and shrinkage easily occurs. The amount of the physical foaming agent may be 5 to 12 parts by mass. Within this range, the foaming power can be sufficiently increased, and foaming can be made even better.
As a method of impregnating the resin particles with a physical foaming agent, a known method can be used. For example, a wet impregnation method and a dry impregnation method are mentioned. In the wet impregnation method, resin particles, a dispersant and water are supplied into an autoclave and stirred to disperse the resin particles in water to produce a dispersion, and a foaming agent is injected into the dispersion. In this method, resin particles are impregnated with a foaming agent. The dry impregnation method is a method in which a foaming agent is press-fitted into resin particles in an autoclave, and the resin particles are impregnated with the foaming agent.
The dispersant is not particularly limited, and examples thereof include poorly water-soluble inorganic substances such as calcium phosphate, magnesium pyrophosphate, sodium pyrophosphate, magnesium oxide, and sodium linear alkylbenzene sulfonate (for example, sodium dodecylbenzene sulfonate). Surfactant is mentioned.

When the impregnation temperature of the physical foaming agent into the resin particles is low, the time required for impregnating the resin particles with the physical foaming agent becomes long, and the production efficiency may decrease. On the other hand, when the particle size is high, the resin particles may be fused to generate a bond particle. The impregnation temperature may be -20 to 120 ° C, 0 to 120 ° C, 20 to 120 ° C, or 40 to 120 ° C. You may use a foaming adjuvant (plasticizer) and a bubble regulator together with a physical foaming agent.
Examples of the foaming aid (plasticizer) include diisobutyl adipate, toluene, cyclohexane, and ethylbenzene.

Examples of the bubble regulator include higher fatty acid amides, higher fatty acid bisamides, higher fatty acid salts, and inorganic cell nucleating agents. These bubble regulators may be used in combination.
Examples of higher fatty acid amides include stearic acid amide and 12-hydroxystearic acid amide.
Examples of higher fatty acid bisamides include ethylene bis stearamide and methylene bis stearamide.
An example of the higher fatty acid salt is calcium stearate.
Examples of inorganic cell nucleating agents include talc, calcium silicate, synthetic or naturally produced silicon dioxide, and the like.
In addition to the above, a bubble adjusting agent that also serves as a chemical bubble agent may be used. Examples of such a bubble regulator include sodium bicarbonate citric acid, sodium hydrogen carbonate, azodicarbonamide, dinitrosopentamethylenetetramine, benzenesulfonyl hydrazide, hydrazodicarbonamide and the like.
The content of the cell regulator may be 0.005 to 2 parts by mass or 0.01 to 1.5 parts by mass with respect to 100 parts by mass of the expandable particles. When there are few bubble regulators than 0.005 mass part, control of a bubble diameter may become difficult. When the amount of the air conditioner is more than 2 parts by mass, the physical properties of the resin may change, and for example, the strength of the molded body may decrease.

(C) Resin Particle The shape of the resin particle is not particularly limited, and examples thereof include a true sphere, an elliptical sphere (egg), a columnar shape, a prismatic shape, a pellet shape, and a granular shape.
As the resin particles, raw material pellets may be used as they are, or they may be repelleted into any size and shape.
The resin particles may have a length of 0.5 to 5 mm and an average diameter of 0.5 to 5 mm. When the length is less than 0.5 mm and the average diameter is less than 0.5 mm, gas retention may be reduced when foamable particles are used, and foaming may be difficult. When the length is larger than 5 mm and the average diameter is larger than 5 mm, since heat is not transferred to the inside when foamed, the fused foamed particles may be cored. Here, the length L and the average diameter D of the resin particles are measured using a caliper as follows. The length of the resin particles in the extrusion direction at the time of re-pelletization is defined as length L, and the average value of the minimum diameter (minimum diameter) and maximum diameter (maximum diameter) of the resin particles in the direction orthogonal to the extrusion direction is defined as average diameter D. When the raw material pellets are used as they are, the longest diameter of the resin particles is the length L, and the average value of the minimum diameter and the maximum diameter in the direction orthogonal to the diameter direction is the average diameter D.

EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these. Various measurement methods are described below.
<Melt Mass Flow Rate (MFR)>
MFR is measured by using “Semi-auto melt indexer 2A” manufactured by Toyo Seiki Seisakusho Co., Ltd., JIS K 7210: 1999 “Plastics—Test methods for melt mass flow rate (MFR) and melt volume flow rate (MVR) of thermoplastics”. It was carried out by the method of measuring the time required for the piston to move a predetermined distance b) described in the method B. The measurement conditions are 3 to 8 g of the sample that was vacuum-dried at 90 ° C. for 3 hours and stored immediately before the measurement, preheating 5 minutes, load hold 30 seconds, test temperature 190 ° C., test load 21.18 N, piston travel distance (interval) ): 25 mm. The number of test of the sample was 3 times, and the average was the value of MFR (g / 10 min).

<Melting tension>
Melt tension was measured using a twin bore capillary-rheometer-Rheological 5000T (Chiast, Italy). That is, after filling a 15 mm diameter barrel heated to an endothermic peak temperature in DSC with a diameter of 15 mm and preheating for 5 minutes, the capillary die (caliber: 2.00 mm, length: 20 mm, inflow angle: While the piston descending speed (0.14667 mm / s) is kept constant from the flat) and extruded into a string, the string is passed through a tension detection pulley located 27 cm below the capillary die, and then wound. Using a take-up roll, the take-up speed is gradually increased at an initial speed of 8.3 mm / s and an acceleration of 12 mm / s ² , and the tension when the take-up speed is 50 mm / s. The average value of the maximum tension and the minimum tension around the winding speed of 50 mm / s was taken as the melt tension.
In addition, the endothermic peak temperature in DSC of melt tension measurement was measured by the method described in JIS K7121: 1987 and JIS K7121: 2012 "Plastic transition temperature measuring method". However, the sampling method and temperature conditions were as follows. The sample was filled with 5.5 ± 0.5 mg so that there was no gap at the bottom of the aluminum measurement container, and then the lid was made of aluminum. Subsequently, using a differential scanning calorimeter (DSC7000X AS-3, manufactured by Hitachi High-Tech Science Co., Ltd.), the temperature was raised from 30 ° C. to 250 ° C. under a nitrogen gas flow rate of 20 mL / min (1st heating), and after holding for 10 minutes, 250 ° C. The DSC curve was obtained when the temperature was lowered from -30 ° C. to -30 ° C., held for 10 minutes and then raised from -30 ° C. to 250 ° C. (2nd heating). All temperature increases / decreases were performed at a rate of 10 ° C./min, and alumina was used as a reference material. The endothermic peak temperature in DSC for melt tension measurement was a value obtained by reading the temperature at the top of the largest melting peak in the 2nd heating process using the analysis software attached to the apparatus.

<Bulk density of expanded particles>
Arbitrary mass W (g) was measured using the expanded particles as a measurement sample. After this measurement sample was naturally dropped into the graduated cylinder, the volume was made constant by tapping the bottom of the graduated cylinder, and the apparent volume V (cm ³ ) of the sample was measured. The bulk density of the expanded particles was calculated based on the following formula.
Bulk density (g / cm ³ ) = mass W of measurement sample / volume V of measurement sample

<Density of foam molding>
Immediately after molding, the foamed molded article was dried at a temperature of 40 ° C. for 12 hours, and after drying, the condition was adjusted for 72 hours in an environment of a temperature of 23 ± 2 ° C. and a humidity of 50 ± 5%. Measure the mass a (g) of the foamed molded product to the second decimal place, measure the outer dimension to 1/100 mm with a Digimatic caliper (Mitutoyo), and determine the apparent volume b (cm ³ ). Asked. The density of the foamed molded product was calculated by the following formula.
Foam molded body density (g / cm ³ ) = a / b

<Average cell diameter of foam molded article>
The average cell diameter of the foam molded article was measured by the following method. Specifically, three test pieces (thickness 1 mm) were cut out from the foamed molded article using a razor, and the cut surface was scanned with an electron microscope (S-3000N, manufactured by Hitachi, Ltd. or S-3400N, manufactured by Hitachi High-Technologies Corporation). The photo was taken at 15x magnification. The photographed image was printed on A4 paper, and expanded particles having a cross-sectional area as large as possible were selected from the printed image. An arbitrary straight line in contact with 20 or more bubbles was drawn in the selected expanded particles, the length L of the straight line was measured, and the number N of bubbles in contact with the straight line was counted. When a straight line in contact with 20 bubbles could not be drawn, the longest straight line was drawn in the region. Arbitrary straight lines were not touched only at the contact points as much as possible, and when they touched, they were included in the number of bubbles. If the bubbles are small and difficult to count, a photograph magnified 15 times or more may be used, and if the expanded particles are not included in a photograph 15 times larger, a photograph reduced to 15 times or less may be used. From the measurement results, the average chord length t and the bubble diameter D were calculated by the following formula.
Average chord length t = line length L / (number of bubbles N × photo magnification)
Bubble diameter D = average chord length t / 0.616
Each test piece was similarly performed, and the arithmetic average of these was taken as the average cell diameter.

<Closed cell ratio of foam molded article>
The foamed molded product was cut into 25 × 25 × thickness 20 mm so as not to leave the skin layer of the foamed molded product, and after conditioned for 16 hours in a JIS K7100: 1999 symbol 23/50, second grade environment, JIS K7100: 1999 Symbol 23/50 (Temperature 23 ° C., Relative Humidity 50%) Measurement was performed in a second grade environment. However, when the thickness was less than 20 mm, the measurement was performed in a thickness of 20 mm or less. First, the mass (g) of the obtained test piece is measured to two decimal places, and the outer dimension is measured to 1/100 mm with a digimatic caliper (manufactured by Mitutoyo Corporation) to determine the apparent volume A (cm ³ ). Asked. Next, the volume B (cm < ³ >) of the measurement sample was calculated | required by the 1-1 / 2-1 atmospheric pressure method using the air comparison type hydrometer (1000 type | mold, Tokyo Science company make). The closed cell ratio (%) was calculated by the following formula, and the average value of the five test pieces was defined as the closed cell ratio (%). The air comparison type hydrometer was corrected with a standard ball (large 28.96 cc, small 8.58 cc). The resin density was 1.17 g / cm ^{3 for} Perprene GP-475 and 1.18 g / cm ^{3 for} the resin composition of Example 3.
Closed cell ratio (%) = (B− (test piece mass / resin density)) / A × 100

<Rebound resilience of foam molding>
It measured based on JISK6400-3: 2011. At least one skin layer from the same foam that was conditioned for 72 hours or more in an environment of temperature 23 ± 2 ° C. and humidity 50 ± 5% on a rebound resilience tester (FR-2, manufactured by Kobunshi Keiki Co., Ltd.) Two 50 × 50 × 20 mm thick samples cut out so as to remain are set in a stack, and a copper ball (φ5 / 8 inch, 16.3 g) is applied to the skin layer of the foam molded body from a height (a) of 500 mm. It dropped freely, the height (b) at the time of reaching the maximum resilience was read, and the resilience elastic modulus (%) was calculated by the formula (b) / (a) × 100. However, when the thickness was less than 20 mm, measurement was performed by laminating without gap so that the thickness would be 40 mm. In addition, it measured 3 times using the same test piece, and made these average values the rebound resilience.

<Compression set of foam molding>
It conformed to JIS K6767: 1999 “Foamed plastics-polyethylene test method”. Moreover, the thickness was measured by 10 kPa of the dimension measurement A method of JIS K6250: 2006. The foamed molded product is cut into 50 × 50 × 20 mm thickness so that no skin layer remains, and after conditioning for 16 hours under JIS K 7100: 1999 symbol 23/50, second grade standard atmosphere, the same standard atmosphere Measurements were made below. However, when the thickness was less than 20 mm, the measurement was performed in a thickness of 20 mm or less. First, the thickness A (mm) of the test piece was measured to two decimal places. Next, the test piece is compressed to a state in which the thickness of the test piece is 25% distorted by a compression set tester (FCS-1 type, manufactured by Kobunshi Keiki Co., Ltd.) and left for 22 hours. The thickness B (mm) 30 minutes after completion of compression was measured to two decimal places. The compression set (%) was calculated by the following formula. The number of tests was three times, and the average value of these was the compression set (%).
Compression set (%) = (A−B) / A × 100

<Impregnated gas amount of expandable particles (butane gas)>
The mass W1 (g) of the obtained expandable particles was immediately measured and allowed to stand for 24 hours in an environment of a temperature of 23 ± 2 ° C. and a humidity of 50 ± 5%. After standing, the mass W2 (g) of the expandable particles was measured, and the amount of impregnation gas was calculated by the following formula.
Amount of impregnated gas of expandable particles (mass%) = (W1-W2) / W1 × 100

<Amount of impregnated gas of expanded particles (nitrogen gas)>
First, the mass W1 (g) of the expanded particles before application of internal pressure was measured. Next, the mass W2 (g) of the expanded particles containing nitrogen gas after application of internal pressure was measured. The amount of impregnated gas of the expanded particles was calculated by the following formula.
Impregnated gas amount (mass%) of expanded particles = (W2−W1) / W2 × 100

<Example 1>
(1) Resin particles Ester elastomer dried at 100 ° C. for 4 hours (trade name: “Perprene GP-475”, manufactured by Toyobo Co., Ltd., hard segment: polybutylene terephthalate, soft segment: aliphatic polyether, melting point: 150 ° C.) 100 parts by mass and 0.3 part by mass of an organic foam regulator (ethylene bis stearamide, trade name: “Kao Wax EBFF”, manufactured by Kao Corporation) are supplied to a single screw extruder and melted at 180 to 280 ° C. Kneaded. Next, after the molten ester-based elastomer is cooled to adjust the viscosity, the resin is supplied from each nozzle of a multi-nozzle mold (having 8 holes of 1.3 mm in diameter) attached to the front end of the single screw extruder. Extruded and cut in water at 30-50 ° C. The obtained resin particles had a particle length L of 1.4 to 1.8 mm and an average particle diameter D of 1.4 to 1.8 mm.
(2) Expandable particles A pressure-resistant rotary mixer with an internal volume of 43 L that can be heated and sealed, and 15 kg (100 parts by mass) of resin particles, an anti-fusing agent (polyoxyethylene polyoxypropylene glycol, trade name: “Epan 450 “Daiichi Kogyo Seiyaku Co., Ltd.) 0.25 parts by weight and 0.3 parts by weight of distilled water were sealed and sealed, and then 16 parts by weight of the blowing agent butane (normal butane: isobutane = 7: 3) in a rotating state. Was press-fitted. Next, after heating the mixer at 85 ° C. for 2 hours in a rotating state, the mixer was cooled to 25 ° C. and the mixer was depressurized to obtain expandable particles. The amount of the impregnated gas of the expandable particles was 6.1% by mass.

(3) Foamed particles 1.5 kg of expandable particles are put into a cylindrical pre-foaming machine with a stirrer having an internal volume of 50 L, heated with water vapor with a gauge pressure of 0.12 MPa while stirring, and a bulk density of 0.172 g / cm. ³ expanded particles were obtained.
(4) Foamed molded body The foamed particles were put into an autoclave and nitrogen gas having a gauge pressure of 0.5 MPa was press-fitted and then allowed to stand at 30 ° C. for 18 hours to impregnate the foamed particles with nitrogen gas (giving internal pressure). The amount of nitrogen gas impregnated was 0.7% by mass.
The foamed particles were taken out from the autoclave, immediately filled into a molding cavity having a water vapor pore size of 400 mm × 300 mm × thickness 10 mm, and heat-molded with water vapor having a gauge pressure of 0.22 MPa to obtain a foam molded product. .

<Example 2>
A foam molded article was obtained in the same manner as in Example 1 except that the water vapor gauge pressure during preliminary foaming was changed to 0.13 MPa and the size of the molding cavity was changed to 400 mm × 300 mm × thickness 30 mm. The obtained resin particles had a particle length L of 1.4 to 1.8 mm and an average particle diameter D of 1.4 to 1.8 mm. The amount of impregnated gas of the expandable particles was 6.3% by mass, and the bulk density of the obtained expanded particles was 0.105 g / cm ³ . The amount of nitrogen gas impregnation after applying the internal pressure was 0.9% by mass.

<Example 3>
(1) Resin particles 100 mass parts of perprene GP-475 (manufactured by Toyobo Co., Ltd., hard segment: polybutylene terephthalate, soft segment: aliphatic polyether), perprene GP-600 (Toyobo), dried at 100 ° C. for 4 hours. 100% by mass, hard segment: polybutylene terephthalate, soft segment: aliphatic polyether, melting point: 167 ° C., and organic foam regulator (ethylene bis stearamide, trade name: “Kao Wax EBFF”, Kao Corporation (Made) 0.6 mass part was supplied to the single screw extruder, and it melt-kneaded at 180-280 degreeC. Next, after the molten ester-based elastomer is cooled to adjust the viscosity, the resin is supplied from each nozzle of a multi-nozzle mold (having 8 holes of 1.3 mm in diameter) attached to the front end of the single screw extruder. Extruded and cut in water at 30-50 ° C. The obtained resin particles had a particle length L of 1.4 to 1.8 mm and an average particle diameter D of 1.4 to 1.8 mm.
(2) Expandable particles In an autoclave with a stirrer having an internal volume of 5 L, 1.5 kg (100 parts by mass) of resin particles, 3 L of distilled water, a surfactant (sodium linear alkylbenzene sulfonate, trade name: “Nurex R”) 4 g of Yuka Sangyo Co., Ltd. was charged and sealed, and then 16 parts by mass of blowing agent butane (normal butane: isobutane = 7: 3) was injected under stirring. The autoclave was then heated at 100 ° C. for 2 hours and cooled to 25 ° C. After completion of cooling, the autoclave was depressurized, and the surfactant was immediately washed with distilled water and dehydrated to obtain expandable particles. The amount of the impregnating gas of the expandable particles was 7.5% by mass.

(3) Foamed particles 1.5 kg (100 parts by mass) of expandable particles, anti-fusing agent (polyoxyethylene polyoxypropylene glycol, trade name: “Epan 450”, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 0.25 parts by mass Was applied to a cylindrical pre-foaming machine with a stirrer having an internal volume of 50 L, and heated with water vapor with a gauge pressure of 0.20 MPa while stirring to obtain expanded particles having a bulk density of 0.077 g / cm ³ . .
(4) Foamed molded body The foamed particles were put into an autoclave and nitrogen gas having a gauge pressure of 0.5 MPa was press-fitted and then allowed to stand at 30 ° C. for 18 hours to impregnate the foamed particles with nitrogen gas (giving internal pressure). The amount of nitrogen gas impregnated was 1.2% by mass.
The foamed particles were taken out from the autoclave, immediately filled into a molding cavity having a size of 400 mm × 300 mm × thickness 20 mm having water vapor holes, and heat-molded with water vapor having a gauge pressure of 0.34 MPa to obtain a foam molded product. .

<Comparative Example 1>
Ester elastomer (trade name: “Perprene P-90BD”, manufactured by Toyobo Co., Ltd., hard segment: polybutylene terephthalate, soft segment: aliphatic polyether, melting point: 203 ° C.), acrylic, dried for 4 hours at 100 ° C., acrylic 5 parts by mass of lubricant (trade name: “Metabrene L-1000”, manufactured by Mitsubishi Rayon Co., Ltd.), hard clay (trade name: “ST-301”, manufactured by Shiraishi Calcium Co., Ltd., surface-treated with a silane coupling agent) 1 Parts by mass, 5 parts by mass of carbon black (trade name: “Asahi # 35”, manufactured by Asahi Carbon Co., Ltd.) and an epoxy modifier (epoxy-modified acrylic polymer, weight average molecular weight: 50000, epoxy equivalent: 1.2 kg / eq, viscosity: 2850 mPa · s) 2 parts by mass is melt kneaded with a twin screw extruder, extruded into a strand, To obtain resin pellets by cutting later. In addition, the measurement of melt tension used this resin pellet vacuum-dried at 90 degreeC for 3 hours.
The resin pellets are dried at 100 ° C. for 4 hours, and then supplied to the first extruder of a tandem extruder in which the second extruder having a diameter of 75 mm is connected to the tip of the first extruder having a diameter of 65 mm. Melt kneaded. Further, 17 MPa carbon dioxide was injected from the middle of the first extruder and melt-kneaded, and the molten resin composition containing this foaming agent was continuously supplied to the second extruder and cooled to a temperature suitable for foaming. . The obtained melt-kneaded product was supplied to a circular die (diameter: 36 mm) and subjected to extrusion foaming. Then, the molten kneaded product is extruded into the atmosphere as a cylindrical body from the die outlet, and the cylindrical body is taken out while being foamed, and is formed into a cylindrical shape by a mandrel on a cylinder in which cooling water is circulated inside. A part of the foam was cut open and wound in a sheet form.

<Comparative example 2>
100 parts by mass of a polyolefin-based resin (trade name: “E110G”, manufactured by Prime Polymer Co., Ltd., melting point: 161 ° C.) dried at 100 ° C. for 4 hours, non-crosslinked ethylene-propylene-diene copolymer elastomer dried at 100 ° C. for 4 hours (Product name: “Thermorun Z101N”, manufactured by Mitsubishi Chemical Corporation, melting point: 170 ° C.) 67 parts by mass and talc (average particle size: 12 μm) 12 parts by mass were mixed in a tumbler. 100 parts by mass of this resin composition was supplied to the first extruder of a tandem extruder in which the second extruder having a diameter of 75 mm was connected to the tip of the first extruder having a diameter of 65 mm, and melt kneaded. Further, 4.2 parts by mass of supercritical carbon dioxide (foaming agent) is injected from the middle of the first extruder and melt-kneaded, and a molten resin composition containing the foaming agent is continuously supplied to the second extruder. Cooled to a temperature suitable for foaming. The obtained melt-kneaded product was supplied to a circular die (diameter: 36 mm) and subjected to extrusion foaming. Then, the molten kneaded product is extruded into the atmosphere as a cylindrical body from the die outlet, and the cylindrical body is taken out while being foamed, and is formed into a cylindrical shape by a mandrel on a cylinder in which cooling water is circulated inside. A part of the foam was cut open and wound in a sheet form.

<Comparative Example 3>
100 parts by mass of an ester-based elastomer (trade name: “Perprene GP-475”, manufactured by Toyobo, hard segment: polybutylene terephthalate and polybutylene isophthalate, soft segment: aliphatic polyether) dried at 100 ° C. for 4 hours; 1 part by mass of talc was mixed with a tumbler. Extrusion foaming was carried out in the same manner as in Comparative Example 2 except that the foaming agent was changed to 2 parts by mass of isobutane. As a result, an ester elastomer foam sheet could not be obtained.

<Comparative example 4>
100 parts by mass of an ester elastomer was added to 50 parts by mass of perprene GP-475 (manufactured by Toyobo Co., Ltd., hard segment: polybutylene terephthalate, soft segment: aliphatic polyether) and perprene GP-600 (manufactured by Toyobo Co., Ltd., hard segment: polybutylene terephthalate). , Soft segment: aliphatic polyether, melting point: 167 ° C.) Extrusion foaming was carried out in the same manner as in Comparative Example 3 except that the content was changed to 50 parts by mass. As a result, an ester elastomer foam sheet could not be obtained.
Table 1 summarizes the MFR and melt tension, thickness, density, average cell diameter, compression set, rebound resilience, and closed cell rate of the resin particles of Examples 1 to 3 and Comparative Examples 1 to 4. .

  From Table 1, it can be seen that the foamed molded products of Examples 1 to 3 have a high degree of shape freedom and exhibit excellent shape recovery and rebound resilience.

Claims (6)

It is composed of a fused product of expanded particles whose base resin is an ester elastomer containing a hard segment composed of a dicarboxylic acid component and a diol component and a soft segment composed of an aliphatic polyether and / or polyester. An ester elastomer foamed molded article having a thickness of 5 to 1000 mm, a density of 0.02 to 0.4 g / cm ³ and an average cell diameter of 10 to 300 μm.   The ester elastomer foam molded article according to claim 1, wherein the ester elastomer foam molded article has a compression set of 0 to 15%, a rebound resilience of 50 to 100%, and a closed cell ratio of 60 to 100%.   The ester elastomer foam molding according to claim 1 or 2, wherein the ester elastomer foam molding is used as a buffer material. It is a manufacturing method of the ester system elastomer foaming object according to any one of claims 1 to 3,
It includes a step of foaming expandable particles containing a foaming agent using an ester-based elastomer as a base resin to obtain foamed particles, and a step of obtaining a foamed molded product by foaming the foamed particles in a mold. A method for producing an ester-based elastomer foam molding.   The manufacturing method of the ester elastomer foaming molding of Claim 4 in which the said base resin has MFR (temperature: 190 degreeC, load: 21.18N) of 0.1-30 g / 10min.   The method for producing an ester elastomer foam molded article according to claim 4 or 5, wherein the base resin has a melt tension of 0.1 to 20 cN.