JP5975817B2 - Thermoplastic polyurethane resin foamed particles, method for producing the same, and thermoplastic polyurethane resin foam molded article - Google Patents

Description

  The present invention relates to foamed thermoplastic polyurethane resin particles, a method for producing the same, and a foamed molded article of thermoplastic polyurethane resin. Specifically, the present invention relates to a thermoplastic polyurethane resin foamed particle capable of obtaining a thermoplastic polyurethane resin foamed molded article having a suppressed dimensional change rate, a method for producing the same, and a thermoplastic polyurethane resin foamed molded article. The thermoplastic polyurethane resin foam molded article of the present invention can be used, for example, as a lightweight molded article, a cushioning material, a vibration isolating material, a heat insulating material and the like.

Thermoplastic polyurethane resin is a resin with high wear resistance and high tensile elongation rate of resin, and excellent cold resistance. For foamed molded products using the resin, various materials such as sealing materials, fillers, and automotive parts are used. Expected to be used in the field.
Various methods can be used as a method for producing a foamed molded article using a thermoplastic polyurethane resin as a raw material. For example, there is a method described in Patent Document 1. In this method, the foamed particles before foam molding are impregnated with an inorganic gaseous foaming agent to apply internal pressure to the foamed particles, and then foam molded to obtain a foam molded article.

Japanese Patent Laid-Open No. 8-113664

  The foamed molded body is desired to have dimensions that do not greatly differ from the dimensions of the mold even after a certain amount of time has elapsed after molding. In other words, it is desired that the dimensional change rate is small. In Patent Document 1, a foam molded body having a small dimensional change rate is obtained by applying an internal pressure, but it has been desired to further reduce the dimensional change rate.

  As a result of intensive studies on a thermoplastic polyurethane resin foam molded article having a low dimensional change rate, the present inventors surprisingly include a thermoplastic polyurethane resin having a high compression set in the base resin constituting the foam molded article. Thus, the inventors have found that the above problems can be solved, and have completed the present invention.

Thus, according to the present invention, the base resin is a thermoplastic polyurethane resin, and the base resin has a high compression set thermoplastic polyurethane resin having a compression set of 40% or more as measured by JIS K6262. A thermoplastic polyurethane resin expanded particle characterized by comprising is provided.
Further, according to the present invention, a foaming agent is obtained by impregnating a foaming agent into particles of a thermoplastic polyurethane resin containing a high compression set thermoplastic polyurethane resin having a compression set of 40% or more as measured by JIS K6262. And producing a foamed thermoplastic polyurethane resin particle characterized by foaming the expandable particle.
Further, according to the present invention, there is provided a thermoplastic polyurethane resin foam molded body (hereinafter also simply referred to as a foam molded body) obtained by foam-molding the above-mentioned thermoplastic polyurethane resin expanded particles. .

  According to the present invention, since the base resin contains a high compression set thermoplastic polyurethane resin, it is possible to provide thermoplastic polyurethane resin expanded particles capable of providing a foam molded article in which the rate of dimensional change is suppressed even if internal pressure is not applied. Can be obtained. In addition, since the step of applying an internal pressure to the foamed particles before foam molding can be omitted, productivity can be improved. Furthermore, it is possible to provide a foam molded article having good dimensional stability having properties derived from a thermoplastic polyurethane resin.

Moreover, when 80-100 mass% of high compression set thermoplastic polyurethane resins exist in base resin, the foaming molding which exhibits said effect more can be provided.
In addition, when the thermoplastic polyurethane resin contains a plant-derived thermoplastic polyurethane resin having a plant degree measured by ASTM D 6866 of 1% or more, not only the above effects are exhibited, but also a general petroleum-derived resin and In comparison, there is no concern about supply due to oil depletion or bias in the mining area, and since it is a plant-derived resin, CO ₂ is not substantially discharged during incineration, and a foamed molded product that has little influence on the natural environment can be provided.

(1) Foamed particles The thermoplastic polyurethane resin foamed particles of the present invention (hereinafter also referred to as “foamed particles”) use a thermoplastic polyurethane resin as a base resin. This base resin contains a high compression set thermoplastic polyurethane resin having a compression set of 40% or more as measured by JIS K6262. The expanded particles can be used as they are for applications such as cushioning fillers, and can also be used as a raw material for in-mold foam molding for obtaining a foamed molded article by in-mold foam molding.

(1-1) High compression set thermoplastic polyurethane resin The high compression set thermoplastic polyurethane resin used in the present invention is 40% or more of compression set when measured by JIS K6262 among thermoplastic polyurethane resins. The thing which has. By including the thermoplastic polyurethane resin having a compression set of 40% or more, it is possible to provide expanded particles capable of producing a expanded molded article having a small dimensional change rate. The compression set is preferably 45% or more, and more preferably 50% or more. The upper limit of compression set is 100%.

The high compression set thermoplastic polyurethane resin used in the present invention may have a linear structure or a partially crosslinked structure.
The high compression set thermoplastic polyurethane resin is composed of a condensation polymer of an isocyanate compound and a polyol compound.
Although it does not specifically limit as an isocyanate compound, For example, tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, naphthalene diisocyanate, isophorone diisocyanate, xylene diisocyanate etc. are mentioned.

Examples of the polyol compound include ester-based, adipate-based, ether-based, lactone-based, and carbonate-based polyol compounds.
The ester-based and adipate-based polyol compounds are not particularly limited. For example, polyhydric alcohols such as ethylene glycol, propylene glycol, butanediol, butenediol, hexanediol, pentanediol, neopentyldiol, and pentanediol; Examples thereof include compounds obtained by condensation reaction with dibasic acids such as acid, sebacic acid, azelaic acid, terephthalic acid, isophthalic acid, maleic acid and aromatic carboxylic acid.

The ether-based polyol compound is not particularly limited, and examples thereof include polyethylene glycol, polypropylene ether glycol, polytetramethylene ether glycol, and polyhexamethylene ether glycol.
The lactone-based polyol compound is not particularly limited, and examples thereof include polycaprolactone glycol, polypropiolactone glycol, and polyvalerolactone glycol.
Furthermore, the carbonate-based polyol compound is not particularly limited. For example, at least one polyhydric alcohol selected from ethylene glycol, propylene glycol, butanediol, pentanediol, octanediol, nonanediol, and the like, diethylene carbonate, Examples thereof include compounds obtained by dealcoholization reaction with at least one carbonate selected from dipropylene carbonate and the like.

  The high compression set thermoplastic polyurethane resin is not particularly limited as long as it has a compression set of 40% or more as measured by JIS K6262, and a commercially available product can be used. For example, “Kuramylon” series U-1180, U-1185, U-1190, U-1195, U-1198, U-3180, U-3185, U-3195, U-3190, U-3195 manufactured by Kuraray Co., Ltd. U-3197, U-9180, U-9185, U-9190, U-9195, EF-195, “Rezamin” series P-1288, P-1090, P-1078, P-6165, manufactured by Dainichi Seika Co., Ltd. , P-7282, P-7285, P-2275, P-880 and the like.

  The thermoplastic polyurethane resin is preferably a resin having a high plant degree measured in accordance with ASTM D6866. By using a resin with a high plant degree, an environmentally friendly foamed molded article can be provided. Specifically, the plant degree is preferably 1% or more, and examples thereof include “Kuramylon” series EF-195 manufactured by Kuraray Co., Ltd.

The content of the high compression set thermoplastic polyurethane resin is preferably 80 to 100% by mass in the base resin. When the content is less than 80% by mass, the effect of suppressing the dimensional change rate may be inferior. A more preferable content is 90 to 100% by mass, and a still more preferable content is 95 to 100% by mass.
When the content of the high compression set thermoplastic polyurethane resin is not 100% by mass, other resins than the high compression set thermoplastic polyurethane resin are included.

(1-2) Other resins The other resins are not particularly limited, and examples thereof include thermoplastic polyurethane resins, polystyrene resins, and polyolefin resins having a compression set of less than 40%. Of these, a thermoplastic polyurethane resin having a compression set of less than 40% is preferred.
The thermoplastic polyurethane resin is not particularly limited, and a resin obtained by polycondensation of the isocyanate compound and the polyol compound can be used.

(1-3) Shape of expanded particles The shape of expanded particles is not particularly limited, and examples thereof include polyhedrons, spheres, and irregular shapes. The shape of the expanded particles is preferably a sphere from the viewpoint of ease of molding.

(1-4) Particle size of expanded particles The particle size of the expanded particles is preferably 2.0 to 10.0 mm. When the particle size is less than 2.0 mm, handling during molding is difficult. On the other hand, when it exceeds 10.0 mm, the filling property into the mold may be impaired. A more preferable particle size is 2.0 to 7.0 mm. When the expanded particles are not spheres, the particle diameter of the expanded particles means the particle diameter when the expanded particles are assumed to be spherical by approximation.

(1-5) Bulk density of expanded particles The bulk density of the expanded particles is preferably 0.03 to 0.6 g / cm ³ . When the bulk density is less than 0.03 g / cm ³ , the melt-bonding property may be insufficient in the in-mold foam molding, or the shrinkage of the obtained foam molded article may be increased. On the other hand, when it is larger than 0.6 g / cm ³ , the lightweight property of the foamed molded product obtained by foam-molding the foamed particles in the mold becomes insufficient. A more preferable bulk density is 0.1 to 0.4 g / cm ³ .
The bulk density measurement method is described in the following examples.

(1-6) Manufacturing method of expanded particle The manufacturing method of expanded particle is not specifically limited, For example, it can manufacture as follows.

  First, by using a kneading machine such as a Warner kneader, Banbury mixer, mixing roll, single-screw extruder, twin-screw extruder, etc., the base resin containing the high compression set thermoplastic polyurethane resin is round, elliptical -Like, pellet-like or powdery thermoplastic polyurethane resin particles are obtained. When used in a round, oval or pellet form, the particle size is preferably about 1 to 5 mm, more preferably about 1 to 3 mm.

  The surface of the thermoplastic polyurethane resin particles may be treated with a surface treatment agent before impregnating the foaming agent. As the surface treatment agent, an anti-fusing agent that prevents fusing during the production of expanded particles, a fusing accelerator that promotes fusing at the time of foam molding, a lubricant that improves the filling ability in the mold, an antistatic agent, A coloring agent etc. are mentioned. More specifically, talc, calcium carbonate, silica-alumina (colloidal and slurry), ethylene bisstearamide, higher fatty acid, higher aliphatic alcohol, edible oil, higher fatty acid triglyceride, paraffin, polyethylene wax, metal soap Examples thereof include modified polysiloxane (for example, zinc stearate). Such surface treatment is preferably performed on the particles with a ribbon blender, tumbler, nauter mixer, super mixer, Ladige mixer or the like. If the foaming agent impregnated container can be rotated or stirred, the surface treatment can be performed simultaneously with the impregnation.

  Next, the thermoplastic polyurethane resin particles are impregnated with a foaming agent. Examples of the foaming agent include inorganic gas, organic gas, and low boiling point liquid. Examples of the inorganic gas blowing agent include nitrogen, carbon dioxide gas, and air. Examples of organic gas blowing agents include hydrocarbons such as propane, methyl ether, and butane, and halogenated aliphatic hydrocarbons such as ethylene dichloride, trifluorochloromethane, dichloromethane difluoride, and F-134a. Can be mentioned. Examples of the low-boiling liquid blowing agent include ether, petroleum ether, acetone, cyclopentane, hexane, and benzene. In addition, a foaming agent can be used individually or in mixture.

  These foaming agents are selected in consideration of the type of resin, the impregnation temperature, the desired amount of impregnation, and the like. Butane, which is an organic gas, is excellent in that the amount of impregnation can be increased. The impregnation treatment varies depending on the type of foaming agent, but is generally performed in a sealed container.

When the foaming agent is an organic gas or a low boiling point liquid, a dry impregnation method, a wet impregnation method, or the like can be used.
The dry impregnation method is preferably performed at a moderate temperature at which particles do not coalesce, and varies depending on the type of foaming agent, resin, etc., but is preferably 60 to 120 ° C, more preferably 60 to 100 ° C. Further, the foaming agent is sufficiently impregnated into the particles even at normal pressure, but an appropriate pressure may be applied in order to shorten the impregnation time.

  The wet impregnation method is performed by charging water, resin particles, and a foaming agent in an airtight container and applying an appropriate impregnation temperature and pressure. The impregnation temperature is preferably a moderate temperature at which particles do not coalesce, and varies depending on the type of foaming agent, resin, etc., but is preferably 60 to 120 ° C, more preferably 60 to 100 ° C. Furthermore, the foaming agent is sufficiently impregnated into the resin particles even at normal pressure, but an appropriate pressure may be applied to shorten the impregnation time. Note that the foamable thermoplastic polyurethane resin particles produced by this method are sticky due to moisture present in the particles when left standing, and therefore, if it is desired to maintain a dry state, an appropriate dehydration treatment can be performed. preferable.

  The impregnation time in each impregnation method varies depending on the type of foaming agent, the impregnation pressure, the type of resin, the particle size of the resin, etc., but it is preferable to carry out until the foaming agent is impregnated by 1 mass% or more. The impregnation time is preferably 2 to 10 hours in the dry impregnation method and 2 to 10 hours in the wet impregnation method. In particular, in order to obtain high-quality expanded particles, it is preferable to impregnate 2 to 10% by mass of a foaming agent.

By impregnating the foaming agent, expandable thermoplastic polyurethane resin particles impregnated with the foaming agent (hereinafter, also simply referred to as “expandable particles”) can be obtained.
Thereafter, the expandable particles are subjected to a foaming process. The foamable particles are preferably subjected to foaming treatment immediately after impregnation with the foaming agent.

  The expandable particles can be expanded particles according to any expansion method known to those skilled in the art. For example, foamed particles can be obtained by charging foamable particles in a pressure foaming tank and heating them with a heating medium such as water vapor. The foaming conditions vary depending on the type of foaming agent and resin, but the foaming temperature is about 80 to 145 ° C., the foaming pressure is about 0.05 to 0.3 MPa, and the foaming time is about 10 to 120 seconds. Although it does not specifically limit as a heating medium, Water vapor | steam is preferable. When using water vapor as a heating medium, it is suitable to use water vapor having a dew point of 60 to 100 ° C. or a water vapor-air mixed medium having a dew point of 70 to 100 ° C. Water vapor with a dew point of less than 60 ° C. may make it difficult to obtain expanded particles with a high expansion ratio. Furthermore, it is preferable to stir with a rotating blade or the like in order to prevent heating uniformity and coalescence of the expanded particles.

(2) Foam molded article The foam molded article can be produced by any in-mold foam molding method known to those skilled in the art. For example, the foamed molded article is formed by filling foamed particles in a closed mold having a large number of small holes, and again heat-foaming with a heating medium to fill the voids between the foamed particles and fuse the foamed particles to each other. It can manufacture by integrating by. As the heating medium, water vapor having a dew point and a water vapor-air mixed medium can be used. The molding temperature is 80 to 160 ° C., the molding pressure is 0.05 to 0.5 MPa, and the molding time is about 20 to 180 seconds.
At that time, the multiple of the foamed molded product can be prepared, for example, by adjusting the filling amount of the foamed particles in the mold.

  Generally, when obtaining a foam-molded product from foamed particles, a step of impregnating the foamed particles with a foaming agent and applying an internal pressure (internal pressure applying step) is required before the foam-forming step. However, the foam molded article of the present invention can be obtained by subjecting the foamed particles to the foam molding process without performing such an internal pressure application process. Accordingly, the internal pressure application step can be omitted, and productivity can be increased.

  The amounts of the base resin, the high compression set thermoplastic polyurethane resin, and the like contained in the foamed molded product are substantially the same as those in the foamed particles.

(2-1) Density of foam molded article The density of the foam molded article is preferably 0.02 to 0.6 g / cm ³ . If the density of the foamed molded product is lower than 0.02 g / cm ³ , a foamed molded product having sufficient strength may not be obtained due to foam breakage. On the other hand, if it is higher than 0.6 g / cm ³ , the lightweight property of the foamed molded product may not be sufficient. A more preferable density is 0.05 to 0.5 g / cm ³ , and a more preferable density is 0.1 to 0.4 g / cm ³ .

  In the following examples, one embodiment of the present invention will be specifically described. However, this is merely an example of the present invention, and the present invention is not limited to the following examples.

(3-1) Measuring method of compression set of thermoplastic polyurethane resin The compression set of thermoplastic polyurethane resin is determined according to JIS K6262: 2006 "vulcanized rubber and thermoplastic rubber-compression set at normal temperature, high temperature and low temperature. Measured according to “How to obtain”.
Specifically, a cylindrical test piece having a diameter of 29.0 mm and a thickness of 12.7 mm was kept in a state of being compressed by 25% at 70 ° C. for 22 hours using a spacer, and the thickness of the test piece after 30 minutes after compression was released. Measure the compression set (CS (%)) by the following formula.
Compression set CS (%) = {(t0−t1) / (t0−t2) × 100}
t0: Original thickness of test piece (mm)
t1: Thickness (mm) after the test piece was taken out of the compression apparatus and 30 minutes passed
t2: Spacer thickness (mm)

(3-2) Method for Measuring Hardness of Thermoplastic Polyurethane Resin The hardness of the thermoplastic polyurethane resin is measured in accordance with JIS K7311: 1995 “Testing Method for Polyurethane Thermoplastic Elastomer”. The value measured using the A durometer is taken as the hardness.

(3-3) Method for measuring the bulk density of the expanded particles The expanded particles are filled into the graduated cylinder while visually observing the graduated cylinder from the horizontal direction, and the filling ends when the graduated cylinder reaches the 500 cm ³ scale. Next, the mass of the expanded particles filled in the graduated cylinder is weighed, rounded off, and the value with the second decimal place as a significant figure is defined as W (g). The bulk density of the expanded particles is calculated by the following formula.
Bulk density (g / cm ³ ) = W / 500

(3-4) Method for Measuring Density of Foam Molded Body The density of the foam molded body is measured according to JIS K7122: 1999 “Measurement of Foamed Plastic and Rubber—Apparent Density”.
Specifically, the density of the foamed molded product is cut to 50 cm ³ or more (100 cm ³ or more for semi-hard and soft materials) without changing the cell structure of the material, and the mass of the slice is measured. Calculated by the following equation.
Density (g / cm ³ ) = Test piece mass (g) / Test piece volume (cm ³ )

(3-5) Method for Measuring Dimensional Change Rate of Foam Molded Body In-mold foam molding is performed with a molding die having an inner dimension of 150 mm (vertical) x 150 mm (horizontal) x 30 mm (height), followed by cooling at room temperature for 15 minutes. The foamed molded product taken out from the mold is allowed to stand at room temperature, and the dimensions after 1 hour and 24 hours are measured for each side (vertical, horizontal and height). For each side, the dimensional change rate is calculated based on the following formula, and the maximum value among the obtained values is taken as the dimensional change rate of the foamed molded product.
Dimensional change rate (%) = {(in-mold dimension−measured dimension value (foam molded body)) / in-mold dimension} × 100

Example 1
A 5 liter capacity autoclave was charged with 1000 g of a thermoplastic polyurethane resin (trade name “Cramiron U-1195” (manufactured by Kuraray), 2.0 mm diameter, 2.5 mm long pellets, 55% compression set), and a foaming agent. 218 g of butane was injected under pressure, and the temperature was kept at 70 ° C. and impregnation was performed for 4 hours. The obtained expandable particles were put into a pressurized foaming tank, kept at a water vapor pressure of 0.27 MPa, and heated at 141 ° C. for 60 seconds for foaming to obtain thermoplastic polyurethane resin expanded particles. The bulk density of the obtained thermoplastic polyurethane resin expanded particles was 0.30 g / cm ³ .
A molding die having a water vapor hole (inner dimensions: 150 mm × 150 mm × 30 mm) was filled with 800 cm ³ of foamed particles and molded by heating at 152 ° C. for 60 seconds at a water vapor pressure of 0.4 MPa. After cooling at room temperature for 15 minutes, the foamed molded product was taken out of the mold. The taken-out foam molding was left at room temperature for 1 hour, and then the dimensions were measured. The obtained foamed molded product had dimensions of 148 mm × 148 mm × 29.3 mm and a density of 0.36 g / cm ³ .
Further, the dimensions of the foamed molded product after being left at room temperature for 24 hours were measured. The foam molded article had dimensions of 148 mm × 148 mm × 29.3 mm and a density of 0.36 g / cm ³ .

Example 2
A 5 liter autoclave is charged with 1000 g of a thermoplastic polyurethane resin (trade name “Cramiron U-1190” (manufactured by Kuraray Co., Ltd.), diameter 2.0 mm, length 2.5 mm pellets, compression set 55%), foaming agent 218 g of butane was injected under pressure, and the temperature was kept at 70 ° C. and impregnation was performed for 4 hours.
The obtained expandable particles were put into a pressure foaming tank, the water vapor pressure was kept at 0.07 MPa, and the foamed particles were heated and heated at 115 ° C. for 60 seconds to obtain thermoplastic polyurethane resin expanded particles. The bulk density of the obtained thermoplastic polyurethane resin expanded particles was 0.31 g / cm ³ .
A molding die having a water vapor hole (inner dimensions: 150 mm × 150 mm × 30 mm) was filled with 800 cm ³ of foamed particles, and molded by heating at 148 ° C. for 60 seconds at a water vapor pressure of 0.36 MPa. After cooling at room temperature for 15 minutes, the foamed molded product was taken out of the mold. The taken-out foam molding was left at room temperature for 1 hour, and then the dimensions were measured. The obtained foamed molded product had dimensions of 145 mm × 146 mm × 29 mm and a density of 0.38 g / cm ³ .
Further, the dimensions of the foamed molded product after being left at room temperature for 24 hours were measured. The foamed molded product had dimensions of 145 mm × 146 mm × 29 mm and a density of 0.38 g / cm ³ .

Example 3
Thermoplastic polyurethane resin (trade name “Cramiron EF-195” (manufactured by Kuraray Co., Ltd.) with a plant-derived raw material ratio of 40% in a 5 L capacity autoclave, pellets with a diameter of 2.0 mm and a length of 2.5 mm, compression set 55%) was charged in an amount of 218 g of butane as a foaming agent, and the temperature was kept at 70 ° C. for 4 hours. The obtained expandable particles were put into a pressurized foaming tank, kept at a water vapor pressure of 0.27 MPa, and heated at 141 ° C. for 60 seconds for foaming to obtain thermoplastic polyurethane resin expanded particles. The bulk density of the obtained thermoplastic polyurethane resin foamed particles was 0.32 g / cm ³ .
A molding die having a water vapor hole (inner dimensions: 150 mm × 150 mm × 30 mm) was filled with 800 cm ³ of foamed particles, and molded by heating at 152 ° C. for 60 seconds at a water vapor pressure of 0.4 MPa. After cooling at room temperature for 15 minutes, the foamed molded product was taken out of the mold. The dimension was measured after leaving the foamed molded article taken out at room temperature for 1 hour. The obtained foamed molded product had dimensions of 145 mm × 144 mm × 28.9 mm and a density of 0.40 g / cm ³ .
Further, the dimensions of the foamed molded product after being left at room temperature for 24 hours were measured. The foam molded article had dimensions of 145 mm × 144 mm × 28.9 mm and a density of 0.40 g / cm ³ .

Example 4
A 5 liter capacity autoclave is charged with 1000 g of a thermoplastic polyurethane resin (trade name “Clamiron U-3185” (manufactured by Kuraray Co., Ltd.), 2.0 mm diameter, 2.5 mm long pellets, 45% compression set), a foaming agent 218 g of butane was injected under pressure, and the temperature was kept at 70 ° C. and impregnation was performed for 4 hours. The obtained expandable particles were put into a pressure foaming tank, the water vapor pressure was kept at 0.07 MPa, and the foamed particles were heated and heated at 115 ° C. for 60 seconds to obtain thermoplastic polyurethane resin expanded particles. The bulk density of the obtained thermoplastic polyurethane resin foamed particles was 0.32 g / cm ³ .
A molding die having a water vapor hole (inner dimensions 150 mm × 150 mm × 30 mm) was filled with 800 cm ³ of foamed particles, and molded by heating at 139 ° C. for 60 seconds at a water vapor pressure of 0.25 MPa. After cooling at room temperature for 15 minutes, the foamed molded product was taken out of the mold. The dimension was measured after leaving the foamed molded article taken out at room temperature for 1 hour. The obtained foamed molded product had dimensions of 142 mm × 143 mm × 28.4 mm and a density of 0.42 g / cm ³ .
Further, the dimensions of the foamed molded product after being left at room temperature for 24 hours were measured. The foam molded article had dimensions of 142 mm × 143 mm × 28.4 mm and a density of 0.42 g / cm ³ .

Comparative Example 1
A 5 liter autoclave is charged with 1000 g of a thermoplastic polyurethane resin (trade name “Curamylon U-8165” (Kuraray Co., Ltd.), diameter 2.0 mm, length 2.5 mm pellets, compression set 37%), foaming agent 218 g of butane was injected under pressure, and the temperature was kept at 70 ° C. and impregnation was performed for 4 hours. The obtained expandable particles were put into a pressurized foaming tank, and the water vapor pressure was kept at 0.05 MPa, and the foamed particles were heated and foamed at 111 ° C. for 60 seconds to obtain thermoplastic polyurethane resin expanded particles. The bulk density of the obtained thermoplastic polyurethane resin foamed particles was 0.32 g / cm ³ .
A molding die having a water vapor hole (inner dimensions 150 mm × 150 mm × 30 mm) was filled with 800 cm ³ of foamed particles, and molded by heating at 131 ° C. for 60 seconds at a water vapor pressure of 0.18 MPa. After cooling at room temperature for 15 minutes, the contents were taken out from the mold. The fusion of the foamed particles was poor, and a foamed molded product could not be obtained.

Comparative Example 2
1000 g of thermoplastic polyurethane resin (trade name “Milactolan E-190” (manufactured by Nippon Polyurethane), pellets with a diameter of 2.6 mm and a length of 2.8 mm, compression set 32%) is charged into a 5 L autoclave and foamed. 218 g of butane was injected as an agent, and the temperature was kept at 70 ° C. for impregnation for 4 hours. The obtained expandable particles were put into a pressurized foaming tank, kept at a water vapor pressure of 0.17 MPa, heated at 130 ° C. for 60 seconds and foamed to obtain thermoplastic polyurethane resin expanded particles. The bulk density of the obtained thermoplastic polyurethane resin expanded particles was 0.30 g / cm ³ .
A molding die having a water vapor hole (inner dimensions 150 mm × 150 mm × 30 mm) was filled with 800 cm ³ of foamed particles and molded by heating at 146 ° C. for 60 seconds at a water vapor pressure of 0.33 MPa. After cooling at room temperature for 15 minutes, the contents were taken out from the mold. The fusion of the foamed particles was poor, and a foamed molded product could not be obtained.

Comparative Example 3
A 5 liter autoclave is charged with 1000 g of a thermoplastic polyurethane resin (trade name “Curamylon U-8165” (Kuraray Co., Ltd.), diameter 2.0 mm, length 2.5 mm pellets, compression set 37%), foaming agent 218 g of butane was injected under pressure, and the temperature was kept at 70 ° C. and impregnation was performed for 4 hours. The obtained expandable particles were put into a pressurized foaming tank, and the water vapor pressure was kept at 0.05 MPa, and the foamed particles were heated and foamed at 111 ° C. for 60 seconds to obtain thermoplastic polyurethane resin expanded particles. The bulk density of the obtained thermoplastic polyurethane resin foamed particles was 0.32 g / cm ³ .
The foamed particles were put in an autoclave, pressurized to 0.8 MPa (applied with internal pressure) using CO ₂ as a foaming agent, and left to impregnate at room temperature for 2 hours.
A molding die having a water vapor hole (inner dimensions: 150 mm × 150 mm × 30 mm) was filled with 800 cm ³ of the impregnated foamed particles, and molded by heating at 127 ° C. for 60 seconds at a water vapor pressure of 0.15 MPa. After cooling at room temperature for 15 minutes, the foamed molded product was taken out of the mold. The dimension was measured after leaving the foamed molded article taken out at room temperature for 1 hour. The obtained foamed molded product had a size of 123 mm × 121 mm × 24.2 mm and a density of 0.69 cm ³ .
Further, the dimensions of the foamed molded product after being left at room temperature for 24 hours were measured. The foam molded article had dimensions of 103 mm × 102 mm × 20.1 mm and a density of 1.19 g / cm ³ .

Comparative Example 4
1000 g of thermoplastic polyurethane resin (trade name “Milactolan E-190” (manufactured by Nippon Polyurethane), pellets with a diameter of 2.6 mm and a length of 2.8 mm, compression set 32%) is charged into a 5 L autoclave and foamed. 218 g of butane was injected as an agent, and the temperature was kept at 70 ° C. for impregnation for 4 hours. The obtained expandable particles were put into a pressurized foaming tank, the water vapor pressure was kept at 0.20 MPa, and the foamed particles were heated at 134 ° C. for 60 seconds to be foamed to obtain thermoplastic polyurethane resin expanded particles. The bulk density of the obtained thermoplastic polyurethane resin expanded particles was 0.30 g / cm ³ .
The foamed particles were placed in an autoclave, pressurized to 0.8 MPa (applied with internal pressure) using CO ₂ as a foaming agent, and allowed to stand for 2 hours at room temperature.
A mold for molding having water vapor holes (inner dimensions 150 mm × 150 mm × 30 mm) was filled with 800 cm ³ of the impregnated foamed particles, and molded by heating at 146 ° C. for 60 seconds at a water vapor pressure of 0.33 MPa. After cooling at room temperature for 15 minutes, the foamed molded product was taken out of the mold. The dimension was measured after leaving the foamed molded article taken out at room temperature for 1 hour. The obtained foamed molded product had dimensions of 126 mm × 123 mm × 24.8 mm and a density of 0.59 cm ³ .
Further, the dimensions of the foamed molded product after being left at room temperature for 24 hours were measured. The foamed molded product had dimensions of 111 mm × 109 mm × 21.6 mm and a density of 0.90 g / cm ³ .

The physical properties of the base resin, the expanded particles and the expanded molded body in Examples 1 to 4 and Comparative Examples 1 to 4 are shown below.

From the examples in Table 1, the foam molded body made of a thermoplastic polyurethane resin having a compression set of 40% or more can reduce the dimensional change rate without applying internal pressure to the foamable particles before foam molding. I understand that.
Further, it can be seen from Comparative Examples 1 and 2 that when a thermoplastic polyurethane resin having a compression set of 40% or more is foam-molded without applying an internal pressure, it cannot be sufficiently molded because of insufficient fusion.
Furthermore, it can be seen from Comparative Examples 3 and 4 that even if a thermoplastic polyurethane resin having a compression set of 40% or more is subjected to foam molding by applying an internal pressure, the dimensional change rate cannot be sufficiently reduced.

Claims (7)

A foaming agent is obtained by impregnating a thermoplastic polyurethane resin particle containing a high compression set thermoplastic polyurethane resin having a compression set of 40% or more as measured by JIS K6262 with a foaming agent. a method of manufacturing a by that the thermoplastic polyurethane resin foam particles be foamed, the thermoplastic polyurethane resin expanded particles without giving the internal pressure before the post-expanded beads obtaining foam molding, the following 5.3% method for producing a thermoplastic polyurethane resin foam particles, wherein the benzalkonium give a foam molded article having a dimensional change rate. The blowing agent, method for producing a thermoplastic polyurethane resin foamed particles according to claim 1 is an organic foaming agent. The method for producing foamed thermoplastic polyurethane resin particles according to claim 1 or 2, wherein the foamed thermoplastic polyurethane resin particles have a particle size of 2.0 to 10.0 mm. The method for producing expanded thermoplastic polyurethane resin particles according to any one of claims 1 to 3, wherein the high compression set thermoplastic polyurethane resin is present in an amount of 80 to 100% by mass in the base resin. The thermoplastic polyurethane resin foamed particle according to any one of claims 1 to 4, wherein the thermoplastic polyurethane resin is a plant-derived thermoplastic polyurethane resin having a plant degree measured according to ASTM D6866 of 1% or more. Manufacturing method . Method for producing a thermoplastic polyurethane resin foam thermoplastic particles that by the be mold foaming a polyurethane resin foam molded article according to any one of claims 1 to 5. Method for producing the thermoplastic density polyurethane resin foam molded article, a thermoplastic polyurethane resin foam molded article according to 0.02~0.6g / cm ³ der Ru請 Motomeko 6.