JPH08113664A - Molded thermoplastic polyurethane foam and its production - Google Patents

Abstract

PURPOSE: To provide a novel process for producing a molded thermoplastic polyurethane foam and to produce a low-density high-resilience molded foam. CONSTITUTION: A molded foam having a density of 0.6-0.03g/cm<3> , a closed cell content of 70% or higher, and a resilience of 20% or higher is obtd. by impregnating thermoplastic polyurethane resin particles with an inorg. or org. gaseous or low-boiling-liq. blowing agent, heating the resultant foamable polyurethane resin particles to cause primary foaming, impregnating again the resultant foamed particles with an inorg. gaseous blowing agent, and thermally foaming the obtd. secondary foamable particles in a mold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic polyurethane foam molding and a method for producing the same. More specifically, the present invention relates to a uniform and fine thermoplastic polyurethane foam molded article having high mechanical properties, abrasion resistance, high impact resilience, and the like, which thermoplastic thermoplastic resin has, and a method for producing the same. . The foamed molded product of the present invention is used, for example, as a lightweight molded product, a cushioning material, a heat insulating material and the like.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
A polyurethane foam molded article is directly obtained by subjecting a liquid isocyanate compound and a polyol compound to a urethane-forming reaction and simultaneously foaming with water or a low boiling point liquid such as Freon or methylene chloride as a foaming agent. Manufactured by the method.

However, in the above method, when continuously producing molded articles, it is necessary to keep the isocyanate compound, the polyol compound and the foaming agent constant at all times, which makes it difficult to accurately control the production conditions. Moreover, since an isocyanate compound is used for the production of the molded body, there is a problem in hygiene. Furthermore, since a dedicated foam molding machine is required, the manufacturing cost cannot be reduced.

Therefore, Japanese Patent Application Laid-Open No. 1-263016,
Japanese Patent Laid-Open Nos. 1-230645 and 5-3019
Japanese Patent Laid-Open No. 88 proposes a method for producing a molded article by foam-molding a composition obtained by adding a thermal decomposition type foaming agent to a thermoplastic polyurethane resin. According to this method, it is possible to solve the problems caused by using the liquid raw material, and there is an advantage that the raw material is easy to handle.

However, the foamed molded articles using the above-mentioned decomposable foaming agents all have a large density of 0.6 g / cc, so that a foamed molded article having a low density could not be obtained. Therefore, as a result of intensive studies conducted by the present inventors to solve the above problems, a method used for producing a styrene resin or an olefin resin foam, that is, after impregnating a resin with a foaming agent, A method for obtaining a molded body by heating and foaming with steam to obtain primary expanded particles, filling the primary expanded particles into an arbitrary molding die, and performing steam heating,
The present invention has been surprisingly found to be applicable also to the production of a polyurethane foam molded article, and has led to the present invention.

[0006]

Thus, according to the present invention, primary foaming of thermoplastic polyurethane resin particles using an inorganic or organic gas or a low boiling point liquid blowing agent and inorganic gas blowing agent are used. Formed by in-mold secondary foaming, density 0.6-0.03 g / cm ³ , closed cell rate 7
There is provided a thermoplastic polyurethane foamed molded article characterized by having a rebound resilience of 0% or more and 20% or more. This foamed molded article has a high closed cell rate and a low foaming density, as compared with conventionally reported foamed molded articles.

Further, according to the present invention, thermoplastic polyurethane resin particles are impregnated with a blowing agent of an inorganic or organic gas or a low boiling point liquid to obtain expandable polyurethane resin particles, and the expandable polyurethane resin particles are heated. Then, primary foaming is performed, the obtained primary foamed resin particles are impregnated with a foaming agent of an inorganic gas, and the resulting secondary expandable resin particles are heat-foamed in a molding die to obtain a foamed molded article. A method for producing a polyurethane foam molded article is provided.

As the thermoplastic polyurethane resin usable in the present invention, any resin synthesized by subjecting an isocyanate compound and a polyol compound to a urethane reaction can be used. Examples of the isocyanate compound include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, naphthalene diisocyanate, isophorone diisocyanate, and xylene diisocyanate.

Examples of the polyol compound include ester type, adipate type, ether type, lactone type and carbonate type polyol compounds. Examples of ester-type and adipate-type polyol compounds include polyhydric alcohols such as ethylene glycol, propylene glycol, butanediol, butenediol, hexanediol, pentanediol, neopentyldiol and pentanediol, adipic acid, sebacic acid and azelaic acid. , A compound obtained by a condensation reaction with a dibasic acid such as terephthalic acid, isophthalic acid, maleic acid, and aromatic carboxylic acid.

Examples of ether type polyol compounds include polyethylene glycol, polypropylene ether glycol, polytetramethylene ether glycol and polyhexamethylene ether glycol. Furthermore, as the lactone-based polyol compound,
Examples thereof include polycaprolactone glycol, polypropiolactone glycol, polyvalerolactone glycol and the like.

As the carbonate-based polyol compound, a polyalcohol such as ethylene glycol, propylene glycol, butanediol, pentanediol, octanediol, nonanediol, etc. is dealcoholated with diethylene carbonate, dipropylene carbonate or the like. The compound obtained is mentioned. Further, the thermoplastic polyurethane resin may have a linear structure or a partially crosslinked structure. A linear structure is preferable because the foaming pressure can be close to normal pressure. Specific examples of the thermoplastic polyurethane resin include milactolane E-180, E-190, E-198, P-.
485 (adipate), E-385 (ether)
(All manufactured by Nippon Miractolan Co., Ltd.), U803 and U8
03 Kai (both manufactured by Nippon Mektron).
These products are also commonly called thermoplastic polyurethane elastomers. Of the above-mentioned thermoplastic polyurethane resins, it is preferable to use an adipate resin because the amount of the foaming agent impregnated can be increased and the foaming pressure can be lowered. Furthermore, a resin having a small resin hardness of 80 (Shore A) or less is more preferable because the foaming pressure can be set to about normal pressure.

The thermoplastic polyurethane resin is round, oval, pelletized or powdered by using a kneader such as a Warner type kneader, Banbury mixer, mixing roll, single screw extruder, twin screw extruder or the like. Shaped thermoplastic polyurethane resin particles can be used. Round,
When used in oval or pellet form, the particle size is 1
It is preferably about 5 mm.

The above thermoplastic polyurethane resin particles are
Before being impregnated with the foaming agent, it may be coated with a suitable surface treatment agent. Examples of the surface treatment agent include a lubricant, an antistatic agent, and a colorant that prevent coalescence at the time of primary foaming, promote fusion at the time of molding, and / or improve the filling property of the molding die. More specifically, talc, calcium carbonate, silica-alumina (colloidal and slurry), ethylene bis stearamide, higher fatty acid, higher aliphatic alcohol, edible oil, higher fatty acid triglyceride, paraffin, polyethylene wax, metal soap. Examples thereof include modified polysiloxane (eg zinc stearate). Such surface treatment is preferably performed on the above resin particles with a ribbon blender, a tumbler, a Nauter mixer, a super mixer, a Loedige 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.

In the present invention, the thermoplastic polyurethane resin particles are first impregnated with a foaming agent. As the foaming agent to be impregnated for the primary foaming of the present invention, an inorganic or organic gas or a low boiling point liquid foaming agent is used. Examples of the inorganic gas blowing agent include nitrogen, carbon dioxide gas and air, and examples of the organic gas blowing agent include hydrocarbon systems such as propane, methyl ether and butane, ethylene dichloride,
Trichlorofluoromethane, Dichlorodifluoromethane, F-13
And halogenated aliphatic hydrocarbons such as 4a. Examples of the low boiling point liquid foaming agent include ether, petroleum ether, acetone, cyclopentane, hexane and benzene. The foaming agents may be used alone or as a mixture.

It is necessary to appropriately select the type of these foaming agents in consideration of the type of resin particles, the impregnation temperature, the desired impregnation amount, and the like. According to the knowledge of the present inventors, it has been found that use of an inorganic gas is preferable from the viewpoint of preventing destruction of the ozone layer and air pollution such as photochemical smog.
Further, it has been found that the use of carbon dioxide gas among the inorganic gases is preferable because the bubble diameter is fine, a high expansion ratio can be obtained, and the expansion temperature and expansion pressure can be lowered. Also, butane, which is an organic gas, is excellent in that the amount of impregnation can be increased.

From the viewpoint of preventing the volumetric shrinkage of the primary expanded resin particles, it is necessary to increase the foaming pressure, but it is also possible to use a foaming agent having a relatively high boiling point. The impregnation process is
Although it depends on the type of foaming agent, it is generally performed in a closed container. If the blowing agent is an inorganic gas, the dry impregnation method is used. Such dry impregnation treatment is performed at a mild temperature at which the resin particles do not coalesce. The impregnation temperature is preferably a low temperature because the substantial impregnation amount of the inorganic gas can be increased, and the internal pressure of the pressure vessel can be set to a low value.
The following are preferred. However, if the temperature is 0 ° C. or less, energy consumption is industrially increased due to normal cooling, which is not preferable. On the other hand, high temperature is preferable from the viewpoint of gas impregnation rate. Therefore, in the case of industrially providing high foamability, carbon dioxide gas is 5 to 40 ° C. and nitrogen and air are 0.
-30 degreeC is more preferable.

Further, a suitable pressure for impregnating the inorganic gas
Is 10 kg / cm2 for carbon dioxide²G or more, preferably
20-30 Kg / cm²30 kg / g for G, nitrogen and air
cm ²G or more, preferably 40 to 70 Kg / cm²At G
is there. Impregnation pressure is 10 kg / cm²Below G, inorganic
It is difficult to fully impregnate gas, and it is 100 Kg / cm
²Above G, the closed container is required to have excessive pressure resistance.
It is not preferable for industrial production.

On the other hand, 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. When the dry impregnation method is used, it is preferably carried out at a mild temperature at which the resin particles do not coalesce, and it is preferably 80 to 120 ° C., although it varies depending on the type of the foaming agent and the resin particles. Further, 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.

The wet impregnation method is carried out by charging water, resin particles and a foaming agent in a closed container and applying an appropriate impregnation temperature and pressure. The impregnation temperature is preferably a mild temperature at which the resin particles do not coalesce, and it is preferably 80 to 120 ° C., although it varies depending on the type of the foaming agent and the resin particles. Further, 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. Incidentally, the expandable thermoplastic polyurethane resin particles produced by this method become sticky due to the moisture present in the resin particles when left to stand, so if it is desired to maintain a dry state, an appropriate dehydration treatment should be carried out. Is preferred.

The impregnation time in each of the above-mentioned impregnation methods varies depending on the type of the foaming agent, the impregnation pressure, the type of resin particles, the resin particle size, etc., but is performed until at least 1% by weight of the foaming agent is impregnated. Therefore, the impregnation time is preferably 5 to 10 hours in the dry impregnation method and 5 to 10 hours in the wet impregnation method. In particular, in order to obtain high quality primary expanded particles, it is preferable to impregnate the foaming agent with 2 to 10% by weight.

By impregnating the foaming agent, it is possible to obtain the expandable thermoplastic polyurethane resin particles uniformly impregnated with the foaming agent. Next, the expandable thermoplastic polyurethane resin particles are subjected to a primary foaming step. At this time, the amount of the foaming agent in the expandable thermoplastic polyurethane resin particles was 1% by weight.
It is desirable to perform primary foaming under the above conditions. That is, the foaming agent impregnated in the impregnated resin particles, especially the inorganic gas, is gradually dispersed into the atmosphere, and if it is less than 1% by weight, it is difficult to obtain a desired multiple number of primary expanded particles. Therefore, it is preferable to perform the primary foaming treatment immediately after the impregnation.

As the primary foaming method, any known method can be used. For example, the expandable thermoplastic polyurethane resin particles are charged in a pressure foaming tank and heated by steam or the like. The foaming conditions vary depending on the types of foaming agent and resin particles, but the foaming temperature is 80 to 140.
C., foaming time is 10 to 120 seconds. When steam is used for heating, it is suitable to use steam having a dew point of 60 to 100 ° C or a steam-air mixed medium having a dew point of 70 to 100 ° C. Water vapor having a dew point of less than 60 ° C. is not preferable because it is difficult to obtain primary expanded beads having a high expansion ratio. Further, it is preferable to stir with a rotating blade or the like in order to prevent heating uniformity and coalescence of expanded particles.

By the above primary foaming, it is possible to obtain primary expanded particles having a bulk ratio of 2 times or more. Next, the primary foamed particles are dry-impregnated with a blowing agent of an inorganic gas to apply an internal pressure to form secondary expandable particles, and further foam-molded in a desired mold to highly foam. A polyurethane foam molded article can be obtained. As the foaming agent, carbon dioxide gas, air, nitrogen or the like can be used. Of these, carbon dioxide gas is preferable because the foaming pressure can be made low and the impregnation time can be shortened.

The dry impregnation treatment varies depending on the type of foaming agent, the impregnation pressure, the type of resin particles, the resin particle size, etc.
At least 0.5% by weight of the foaming agent, preferably 1 to
It is carried out until it is impregnated with 4% by weight. The impregnation temperature can be the same as the impregnation temperature of the inorganic gas blowing agent in the production of the expandable resin particles. On the other hand, a suitable pressure for impregnating the foaming agent is 2 kg / cm ² G or more for carbon dioxide gas,
Preferably 4-8 Kg / cm ² G, 5 K for nitrogen and air
g / cm ² G or more, preferably 10 to 15 Kg / cm ²
G. When the impregnation pressure is 4 Kg / cm ² G or less, it is difficult to sufficiently impregnate the foaming agent, and 30 Kg / cm ² G
The above is not preferable in industrial production because the closed container is required to have excessive pressure resistance.

The impregnation time in each of the above impregnation methods varies depending on the type of foaming agent, the impregnation pressure, the type of resin particles, the diameter of resin particles, etc., but is preferably 1 to 5 hours. Subsequently, the secondary expandable particles are filled in a molding die having a desired shape and heated with steam or the like, whereby a polyurethane foam molded article can be manufactured. The time until the secondary expandable particles are filled in the molding die is preferably short in order to prevent dissipation of the foaming agent. Foaming conditions differ depending on the type of foaming agent and resin particles, but the foaming temperature is 110 to 150 ° C., and the foaming pressure is 0.5 to 4.5 Kg / c.
m ² , and the foaming time is 10 to 120 seconds.

In the above-mentioned foaming method, the polyurethane foam molded article is produced by the two-stage foaming. However, in order to obtain a foam molded article having a higher magnification, three or more stages of foaming can be carried out. According to the method of the present invention as described above, the density of 0.6 to
0.03 g / cm ³ , preferably 0.6 to 0.1 g / c
m ³ and the closed cell ratio is 70% or more, preferably 80%
As described above, it is possible to obtain a low-density and high-repulsion polyurethane foam molding having uniform and fine closed cells having a repulsion elasticity of 20% or more.

The polyurethane foam molded article of the present invention has excellent properties such as heat insulation, electrical insulation, mechanical properties, abrasion resistance and high impact resilience, and is uniform and fine and has a high closed cell rate. It is a foamed molded product. Therefore, various sports equipment and everyday products (sole, tennis racket, ski, sofa,
Beds, mattresses, cushions, etc., car interior and exterior products (crash pads, handles, armrests, bumpers, fascias, etc.), packing materials (for rugs, carpets, etc.), heat insulating materials (for vehicles, ships, frozen) It can be used for equipment, electric refrigerators, showcases, vending machines, heavy oil tanks, pipes, etc.).

The closed cell ratio is measured by an air-comparison hydrometer (manufactured by Beckman), and the impact resilience is JIS-
It is measured according to the method of K-6401 (repulsion elasticity test).

[0029]

The thermoplastic polyurethane foam molding of the present invention is
Formed by primary foaming using a blowing agent of an inorganic or organic gas or a low boiling point liquid from thermoplastic polyurethane resin particles, and in-mold secondary foaming using a blowing agent of an inorganic gas,
Since it is characterized by having a density of 0.6 to 0.03 g / cm ³ , a closed cell rate of 70% or more, and a repulsion elastic modulus of 20% or more, the mechanical properties, abrasion resistance, and high property of the thermoplastic polyurethane resin are high. By utilizing excellent properties such as impact resilience, a uniform and fine molded article having a high closed cell rate is provided.

Further, the thermoplastic polyurethane resin particles are
The thermoplastic polyurethane elastomer particles have a density of 0.6 to 0.1 g / cm ³ , and have a closed cell ratio of 80% or more and a repulsion elastic modulus of 20% or more, so that a molded product having better properties can be obtained. . Further, since the foaming agent used for the primary foaming is butane or carbon dioxide gas, a high foaming ratio can be obtained.

Further, since the foaming agent used for the secondary foaming is carbon dioxide gas, the foaming pressure can be lowered and the impregnation time can be shortened. Further, the method for producing a polyurethane foam molded article of the present invention is to obtain a foamable polyurethane resin particle by impregnating a thermoplastic polyurethane resin particle with a foaming agent of an inorganic or organic gas or a low boiling point liquid, the foamable polyurethane resin. Particles are heated for primary foaming, the resulting primary foamed resin particles are impregnated with an inorganic gas blowing agent, and the resulting secondary expandable resin particles are heat-foamed in a molding die to obtain a foamed molded article. Therefore, a method for easily producing a molded product having the above properties is provided.

Further, in the above-mentioned manufacturing method, the expandable polyurethane resin particles are impregnated with 1% by weight or more of the foaming agent, so that the expansion ratio is maintained in a suitable range. Further, in the above-mentioned manufacturing method, the secondary expandable resin particles are impregnated with 0.5% by weight or more of a foaming agent to provide a molded product having a suitable density. Furthermore,
In the above-mentioned manufacturing method, the foaming agent is carbon dioxide gas, so that a molded body having fine cells is provided.

[0033]

EXAMPLES Thermoplastic polyurethane resin particles used in the following examples were miractolane E-180, E-190, and E.
-198, P-485 and E-385 (all manufactured by Nippon Miractolan Co., Ltd.) were used. The characteristics of the resin particles are shown in Table 1 below.

[0034]

[Table 1]

Example 1 A test for impregnating a thermoplastic polyurethane resin particle with a foaming agent was conducted. In this example, adipate-based polyurethane elastomer particles of E-190 and P-485 and ether-based polyurethane elastomer particles of E-385 were used as the thermoplastic polyurethane resin particles. In addition,
In the elastomer, the acronym E means that the molecule has a partially crosslinked structure, and P means a resin having a linear structure and good fluidity.

As the foaming agent, butane, cyclopentane, F-134a and CO ₂ were used. The method of impregnating the elastomer particles with the foaming agent was performed as follows depending on the type of the foaming agent. Wet and dry impregnation methods were used when the blowing agent was butane. In the wet impregnation method, 5 liters of autoclave, 3 liters of water,
Charge 1 kg of elastomer and 400 ml of butane, 1
Impregnation was carried out at 00 ° C. for 6 hours. On the other hand, in the dry impregnation method, the elastomer 20 is put in a 5 liter autoclave.
0 g and 400 ml of a foaming agent were charged and impregnated at 100 ° C. for 10 hours.

The blowing agents are cyclopentane and F-134a.
In the case of, the impregnation was carried out in the same manner as in the dry impregnation method of butane. However, the impregnation temperature of F-134a was 80 ° C. When the blowing agent is CO ₂ , 5 kg of autoclave, 1 kg of elastomer, impregnation pressure of 30 kg / c
Impregnation was carried out at m ² and an impregnation temperature of 20 ° C. for 6 hours. The impregnation results are shown in Table 2 below.

[0038]

[Table 2]

From Table 2 above, it was found that the amount of impregnation differs greatly depending on the type of foaming agent, and F-134a is more easily impregnated than butane. It was also found that the amount of butane impregnated was not significantly affected by the impregnation temperature. Further, it was found that the ether-based polyurethane elastomer particles had a larger amount of butane impregnated but a smaller amount of CO ₂ impregnated than the adipate-based polyurethane elastomer particles.

Example 2 The effects of the types of thermoplastic polyurethane resin particles and the foaming agent and the foaming pressure on the foaming bulk ratio were tested. In this example, expandable thermoplastic polyurethane resin particles (the resin used was the same as in Example 1 above) were subjected to temperature and pressure using steam to produce primary expanded particles. The foaming conditions were a foaming time of 60 seconds, and other conditions are shown in Tables 3 and 4 below.

Table 3 shows the relationship between the resin type, the foaming pressure and the foaming bulk ratio when butane was used as the foaming agent, and CO ₂ was used as the foaming agent.
Table 4 shows the relationship between the resin type, the foaming pressure, and the foaming bulk ratio when the resin was used.

[0042]

[Table 3]

[0043]

[Table 4]

From the above Tables 3 and 4, the following facts were found: (1) The adipate-based polyurethane elastomer can have a foaming region on the low pressure side as compared with the ether-type polyurethane elastomer, and can be foamed under normal pressure. (2) When foaming on the low pressure side, the resin particles did not coalesce during foaming.

Example 3 Expandable resin particles and primary expanded particles were tested for blowing agent dissipation rate. In this example, the amount of residual blowing agent at 20 ° C. was measured for the resin E-190 using butane and F-134a as the blowing agent, and the results are shown in Table 5.

[0046]

[Table 5]

As is clear from Table 5, the blowing agent dissipates relatively quickly, so it has been found preferable to apply it to the next step as soon as possible. Example 4 Using E-190 resin particles, CO ₂ as a foaming agent,
The dissipation rate of the blowing agent at room temperature when the impregnation amount was fixed at 5.8% by weight was measured, and the results are shown in FIG. From this figure, it was found that it is preferable to immediately foam the primary expanded particles after taking them out, because the dissipation rate of CO ₂ is high.

Example 5 Foaming agent CO ₂ , impregnation pressure 30 Kg / cm ² , foaming time 6
The relationship between the foaming vapor pressure and the foaming bulk ratio with respect to the hardness of the resin particles is shown in FIG. 2 when 0 seconds is a common condition. The resin particles are E-180 (hardness 80), E-190.
(Hardness 90) and E-198 (Hardness 98) were used.
Here, the hardness was measured by Shore A in accordance with JIS K-731. From this figure, it was found that the lower the hardness, the more the foaming can be performed at a low pressure.

Example 6 Primary-foamed P-485 (3 times bulk ratio) and E-19
0 (bulk ratio 4 times) using CO ₂ as a foaming agent,
The impregnation amount was measured with respect to the impregnation time under the common conditions of an impregnation pressure of 6 Kg / cm ² and an impregnation temperature of 20 ° C., and the results are shown in FIG.

From FIG. 3, when the impregnated amount of the foaming agent reaches equilibrium.
The time is about 90 minutes and it is enough to impregnate for about 2 hours.
Was found. Example 7 Primary-foamed E-180 (bulk ratio 2.5 times), E-1
90 (4 times bulk ratio), E-198 (4 times bulk ratio) and P
-485 (3 times bulk ratio) as CO ₂use
And the impregnation pressure is 6 Kg / cm², Foaming time 30 seconds
As a common condition, measure secondary foamability against foaming pressure
The results are shown in FIG. Where the secondary foamability
Indicates how many times the primary expanded particles were expanded.
You.

The mold was filled with the primary foam particles in the mold,
In order to fill the space by the secondary foaming, the secondary foaming property is required to be twice or more, but it was found from FIG. 4 that all the resin particles used in this example can be molded. Also, the optimum foaming pressure is different for each resin,
It is thought that this is affected by the hardness of the resin. That is, the higher the hardness is, the higher the foaming pressure is required, and if the hardness is low, the foaming can be performed even at about normal pressure.

Based on FIG. 4, the ranges of impregnation pressure and foaming pressure required to obtain a molded product are shown in Table 6 below. The secondary foamability required for molding is 2.5 times.

[0053]

[Table 6]

Example 8 A 2-liter autoclave was charged with 500 g of thermoplastic polyurethane elastomer resin, milactolane E-190 (manufactured by Nippon Miractolan Co., Ltd.), and 500 cc of butane was injected as a foaming agent, and the temperature was kept at 100 ° C. for 15 hours. Impregnated. After the impregnation, it was cooled to 20 ° C., and the resulting expandable thermoplastic polyurethane resin particles contained 2.3% by weight of butane.
Contained.

The expandable thermoplastic polyurethane resin particles were placed in a pressure foaming tank, the steam pressure was kept at 3.0 Kg / cm ^2, and heated at 141 ° C. for 60 seconds for primary expansion. The obtained primary expanded beads had a bulk ratio of 6 times. The primary expanded beads were placed in a 2-liter autoclave, CO ₂ was used as a foaming agent, the pressure was increased to 6 Kg / cm ² , and the mixture was allowed to stand for 2 hours at room temperature for impregnation. The secondary expandable particles taken out from the autoclave contained 1.6% by weight of CO ₂ .

A molding die (200 mm × 200 mm ×) having water vapor holes within 2 minutes after taking out the secondary expandable particles.
20mm) and steam pressure (foaming pressure) 4.0K
Secondary in-mold foaming was performed by heating at 149 ° C. for 30 seconds at g / cm ² . The obtained molded product has a density of 0.19 g / c
m ³ , closed cell ratio 92% (measured by Beckman Co., Ltd., air-comparison hydrometer), impact resilience 35% (JIS K
6401 was measured according to the impact resilience test).
It was a good foamed molded product having high impact resilience.

Example 9 A 2-liter autoclave was charged with 500 g of thermoplastic polyurethane elastomer resin, miractolane E-190 (manufactured by Nippon Miractolan Co.), and CO was used as a foaming agent.
₂ under pressure of 35 Kg / cm ² was left to impregnate at room temperature for 6 hours. After impregnation, the expandable thermoplastic polyurethane resin particles obtained contained 5.1% by weight of CO ₂ .

The expandable thermoplastic polyurethane resin particles were placed in a pressure foaming tank, and the steam pressure was kept at 1.0 Kg / cm ² and heated at 119 ° C. for 60 seconds for primary expansion. The obtained primary expanded beads had a bulk ratio of 6.2 times.
The primary expanded beads were placed in a 2-liter autoclave, CO ₂ was used as a foaming agent, the pressure was increased to 6 Kg / cm ² , and the mixture was allowed to stand for 2 hours at room temperature for impregnation. The secondary expandable particles taken out from the autoclave contained 1.5% by weight of CO ₂ .

A molding die (200 mm × 200 mm ×) having water vapor holes within 2 minutes after taking out the secondary expandable particles.
20 mm) and steam pressure 4.2 Kg / cm
^{In step 2} , heating was performed at 150 ° C. for 30 seconds to perform secondary foaming in the mold. The obtained molded product had a density of 0.18 g / cm ³ , a closed cell ratio of 91% (measured by Beckman Co., Ltd., by an air-comparison hydrometer), and a repulsion elastic modulus of 38% (JIS K 6401).
Was measured in accordance with the impact resilience test of 1.), and it was a good foamed molded product having high impact resilience.

Example 10 A 2-liter autoclave was charged with 500 g of thermoplastic polyurethane elastomer resin, miractolane P-485 (manufactured by Nippon Miractolan Co.), and CO was used as a foaming agent.
₂ under pressure of 35 Kg / cm ² was left to impregnate at room temperature for 6 hours. After impregnation, the expandable thermoplastic polyurethane resin particles obtained contained 6.2% by weight of CO ₂ .

The expandable thermoplastic polyurethane resin particles were placed in a pressure foaming tank, the steam pressure was kept at 0.1 Kg / cm ^2, and heated at 101 ° C. for 60 seconds for primary expansion. The obtained primary expanded beads had a bulk ratio of 6.5 times.
The primary expanded beads were placed in a 2-liter autoclave, CO ₂ was used as a foaming agent, the pressure was increased to 6 Kg / cm ² , and the mixture was allowed to stand for 2 hours at room temperature for impregnation. The secondary expandable particles taken out from the autoclave contained 1.8% by weight of CO ₂ .

A molding die (200 mm × 200 mm ×) having a water vapor hole within 2 minutes after taking out the secondary expandable particles.
20 mm) and steam pressure 2.2 Kg / cm
^{In step 2} , heating was performed at 133 ° C. for 30 seconds to perform secondary foaming in the mold. The obtained molded product had a density of 0.17 g / cm ³ , a closed cell ratio of 90% (measured by Beckman Co., Ltd., by an air-comparison hydrometer), and a repulsion elastic modulus of 60% (JIS K 6401).
Was measured in accordance with the impact resilience test of 1.), and it was a good foamed molded product having high impact resilience.

[0063]

EFFECT OF THE INVENTION The thermoplastic polyurethane foam molded article of the present invention uses primary foaming of thermoplastic polyurethane resin particles using a blowing agent of an inorganic or organic gas or a low boiling point liquid, and an inorganic gas blowing agent. Formed by in-mold secondary foaming, density 0.6-0.03 g / cm ³ , closed cell rate 7
As it is characterized by having 0% or more and impact resilience of 20% or more, it is possible to make use of the excellent properties of thermoplastic polyurethane resin such as mechanical properties, abrasion resistance, high impact resilience, etc. It is possible to provide a molded product having a high bubble ratio.

Further, since the foaming agent used for the primary foaming is butane or carbon dioxide gas, a molded product having a high expansion ratio can be provided. Furthermore, since the foaming agent used for the secondary foaming is carbon dioxide gas, the foaming pressure can be reduced and the impregnation time can be shortened. Further, the method for producing a polyurethane foam molded article of the present invention is to obtain a foamable polyurethane resin particle by impregnating a thermoplastic polyurethane resin particle with a foaming agent of an inorganic or organic gas or a low boiling point liquid, the foamable polyurethane resin. Particles are heated for primary foaming, the resulting primary foamed resin particles are impregnated with an inorganic gas blowing agent, and the resulting secondary expandable resin particles are heat-foamed in a molding die to obtain a foamed molded article. Therefore, it is possible to provide a method for easily producing a molded product having the above properties.

Further, in the above-mentioned manufacturing method, the expandable polyurethane resin particles are impregnated with 1% by weight or more of the foaming agent, so that the expansion ratio can be maintained in a suitable range. Further, in the above-mentioned production method, the secondary expandable resin particles are impregnated with 0.5% by weight or more of the foaming agent, whereby a molded product having a suitable density can be provided.

Further, in the above manufacturing method, the foaming agent is
By using carbon dioxide gas, it is possible to provide a molded product having fine bubbles.

[Brief description of drawings]

FIG. 1 is a graph showing the dissipation rate of a blowing agent.

FIG. 2 is a graph showing the relationship between foaming pressure and foaming bulk ratio with respect to the hardness of resin particles.

FIG. 3 is a graph showing the relationship between impregnation time and impregnation amount.

FIG. 4 is a graph showing the relationship between secondary foamability and foaming pressure.

Claims (7)

[Claims] 1. Formed from thermoplastic polyurethane resin particles by primary foaming using an inorganic or organic gas or a low boiling point liquid blowing agent and in-mold secondary foaming using an inorganic gas blowing agent, and having a density of 0. A thermoplastic polyurethane foam-molded article characterized by having a proportion of from 6 to 0.03 g / cm ³ , a closed cell rate of 70% or more, and a repulsion elastic modulus of 20% or more. 2. The molded product according to claim 1, wherein the foaming agent used for the primary foaming is butane or carbon dioxide gas. 3. The molded article according to claim 1, wherein the foaming agent used for secondary foaming is carbon dioxide gas. 4. Thermoplastic polyurethane resin particles are impregnated with a foaming agent of an inorganic or organic gas or a low boiling point liquid to obtain foamable polyurethane resin particles, and the foamable polyurethane resin particles are heated for primary foaming, A polyurethane foam molded article, characterized in that the obtained primary foamed resin particles are impregnated with an inorganic gas blowing agent, and the resulting secondary expandable resin particles are heat-foamed in a molding die to obtain a foamed molded article. Production method. 5. The method according to claim 4, wherein the expandable polyurethane resin particles are impregnated with 1% by weight or more of a foaming agent. 6. The method according to claim 4, wherein the secondary expandable resin particles are impregnated with 0.5% by weight or more of a foaming agent. 7. The foaming agent is carbon dioxide gas.
The manufacturing method according to any one of claims.