JP2002059449A - Method for manufacturing foamed resin molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a foamed molding previously molded in a required shape by enabling easy setting of an expansion ratio. SOLUTION: The method for manufacturing the foamed resin molding comprises the steps of sealing a thermoplastic resin 12 in a pressure container 10, then supplying a supercritical fluid of carbon dioxide from a supply source 14 to the container to impregnate the resin with the fluid, heating the resin to an intrinsic crystallization temperature Tc or higher, and then opening the container to expansion foam the resin. The method further comprises the steps of filling the resin in a mold 20 having a cavity 24 and perforating a fluid introducing/escaping hole, clamping the mold, sealing the mold in the container, contacting the fluid supplied from the supply source to the container with the resin via the hold to impregnate the resin with the fluid, heating the resin to the crystallization temperature or higher, then opening the container to expansion foam the resin, specifying a profile of the resin in the cavity, cooling the mold, and then releasing the molding from the mold to manufacture the final molding 22 foamed from the resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a resin foam molded article, and more particularly, to a method of forming a thermoplastic resin in a molding die in a required shape in advance, and in accordance with the size of the resin used. The present invention relates to a method for producing a foamed molded article that can control the expansion ratio arbitrarily.

[0002]

2. Description of the Related Art In order to produce a foam obtained by foaming a thermoplastic resin such as polypropylene (PP) or polyethylene terephthalate (PET), a method using a chemical foaming agent or a physical foaming agent is generally known. Have been. For example, a chemical foaming method mixes an appropriate thermoplastic resin and an organic foaming agent that decomposes at a required molding temperature to generate a gas,
The foaming is carried out by heating the foaming agent at a temperature higher than the decomposition temperature of the core foaming agent. By performing the foaming reaction in a mold, a required three-dimensional shape can be provided. The physical foaming method is to supply a low-boiling organic compound such as butane and pentane to a thermoplastic resin melted in a closed molding machine,
After sufficiently kneading physically, the molded article is obtained by releasing the hermetic seal and releasing the mixture into a low pressure region.

[0003] However, regardless of whether a chemical or physical foaming method is employed, the foaming agent used in the method has a high running cost and has a risk of handling such as flammability and toxicity. Therefore, the impact on the human body and nature on environmental problems is pointed out. In order to cope with such a problem, various methods for foaming by forcibly blowing an inert gas such as carbon dioxide gas or nitrogen gas have been proposed as alternatives to the use of a foaming agent. However, since the inert gas generally has low affinity for resin and poor solubility, the foam of the foam obtained tends to be nonuniform and have a large cell diameter. In addition, since the cell density is small, there is still a problem in producing a foam that satisfies various aspects such as appearance, mechanical strength, heat insulation, and expansion ratio.

In recent years, resin foamed with extremely fine bubbles has been used for various purposes such as a fuel gauge for a vehicle, a gauge for a drinking water tank, and a float valve for opening and closing a flow path of a precision instrument using a fluid. There is a need for foam molded articles. As a method for producing this kind of resin foam molded article having fine cells, a batch-type foaming method utilizing carbon dioxide (CO ₂ ) as a supercritical fluid is known. There are various types of batch type foaming methods using carbon dioxide in a supercritical state, and an example is shown in FIG.

In FIG. 2A, for example, a polypropylene is placed in a pressure vessel 10 capable of controlling a heating temperature within a required range.
After storing the thermoplastic resin 12 such as (PP), the pressure vessel 10 is sealed. Carbon dioxide controls temperature and pressure
(To be described later), the fluid becomes a supercritical fluid, and is stored in a fluid supply source 14 such as a cylinder.
And the pressure vessel 10 via a valve body 17. Then, as shown in (2) of FIG. 2, the valve element 17 is opened to release the supercritical fluid of carbon dioxide into the pressure vessel 1.
Introduce during 0.

Here, the supercritical will be briefly described.
Increasing the temperature and pressure of a substance producing a gas phase and a liquid phase causes a supercritical state in which the gas phase and the liquid phase cannot be distinguished in a certain temperature range and pressure range. The temperature and pressure at this time are called a critical temperature and a critical pressure, respectively. In a supercritical state, a substance has both characteristics of a gas and a liquid, and a fluid generated in this state is called a supercritical fluid.
This supercritical fluid has such characteristics that it has a higher density than a gas, has a lower viscosity than a liquid, and is extremely easy to diffuse in a substance. And carbon dioxide has a critical temperature of 3
At a temperature of 1.2 ° C. or more and a critical pressure of 7.47 MPa or more, a supercritical state is obtained, and the fluid exhibits a behavior. In the initial stage when the supercritical fluid is introduced into the pressure vessel 10, the pressure inside the vessel is at normal pressure, so that the critical pressure of the supercritical fluid temporarily drops and immediately before the supercritical state. Presents a "subcritical state" or "critical state" or even a "normal state"
Although it becomes gaseous carbon dioxide, the critical pressure is quickly reached by continuously supplying the supercritical fluid into the container.

In FIG. 2B, the supercritical fluid supplied to the pressure vessel 10 comes into contact with the thermoplastic resin 12 accommodated in the vessel, whereby the supercritical fluid is
It penetrates into zero. This is because the supercritical fluid has a property that the density is higher than the gas and the viscosity is lower than the liquid as described above, and it is extremely easy to diffuse in the substance. The time required for permeation of this supercritical fluid differs depending on how to set the temperature and pressure above the critical value,
The expansion ratio of the foam obtained in (3) of FIG. 2 changes depending on the length of the time. When the thermoplastic resin 12 is heated in the pressure vessel 10, a supercritical fluid can be made to permeate into the resin with high efficiency. However, if the viewpoint of productivity is excluded, it is not a requirement to heat the supercritical fluid when the resin is infiltrated into the thermoplastic resin 12.

While maintaining the above-described supercritical fluid permeation time for the required time and heating the pressure vessel 10, the thermoplastic resin 12 is heated to a temperature higher than the crystallization temperature inherent to the resin. This heating is necessary for expanding and foaming (described later) the thermoplastic resin 12 after infiltrating the supercritical fluid, and is necessary for infiltrating the supercritical fluid into the resin as described above. Not something. After the thermoplastic resin 12 is heated to a temperature higher than the crystallization temperature as shown in FIG.
As shown in (3), when the pressure vessel 10 is opened to release the internal pressure, the supercritical fluid permeated into the thermoplastic resin 12 in the vessel expands rapidly with the vaporization.
That is, the thermoplastic resin 12 foams internally due to the vaporization of carbon dioxide, and the foam 18 having extremely fine bubbles is taken out of the pressure vessel 10.

[0009]

As described above, a supercritical fluid of carbon dioxide is supplied into the pressure vessel 10 so that the supercritical fluid permeates the thermoplastic resin 12 and the thermoplastic resin 1
According to the batch-type foaming method in which 2 is heated to a crystallization temperature or higher and then the pressure is released and then foamed, a foam having extremely fine cells (i.e., cells having a uniform cell diameter and a small cell density) is obtained, In addition, there is an advantage that satisfaction can be obtained in terms of mechanical strength and heat insulation. However, on the other hand, in this method, the expansion ratio easily changes depending on factors such as temperature conditions, permeation time, and pressure, and the thermoplastic resin expands in a free direction at the time of foaming. It was impossible at all.

[0010]

SUMMARY OF THE INVENTION The present invention has been proposed in order to suitably solve the above-mentioned problems, and employs a batch type foaming method in which carbon dioxide as a supercritical fluid is permeated into a thermoplastic resin and foamed. It is an object of the present invention to provide a method capable of easily setting a desired expansion ratio and manufacturing a foam molded article in a form preliminarily formed into a required shape in a mold.

[0011]

SUMMARY OF THE INVENTION In order to overcome the above-mentioned problems and achieve the intended object, a method for producing a resin foam molded article according to the present invention comprises the steps of placing a required thermoplastic resin to be foam molded in a pressure vessel. After containing and sealing, a supercritical fluid obtained by controlling the temperature and pressure of carbon dioxide is supplied from the supply source of the fluid into the pressure vessel, and the supercritical fluid is brought into contact with the thermoplastic resin. The supercritical fluid is allowed to penetrate into the resin, and the thermoplastic resin is further heated to a crystallization temperature or more specific to the resin, and then the pressure vessel is opened to the atmosphere, whereby the thermoplastic resin is released. A method for producing a foamed resin article by expanding and foaming the resin accompanying the vaporization of a supercritical fluid permeating into a foam, comprises a cavity for regulating the outer shape of the final foamed molded article, and a suitable fluid introduction / escape In front of the mold with a hole Mold and clamping houses a thermoplastic resin,
After accommodating the mold in the pressure vessel, the pressure vessel is sealed, and the supercritical fluid supplied from the fluid supply source into the pressure vessel is subjected to the molding through the fluid introduction / release hole. By contacting the supercritical fluid in the resin by contacting the thermoplastic resin in the mold, by opening the pressure vessel after heating the thermoplastic resin in the mold to a crystallization temperature or more, The resin is expanded and foamed with the vaporization of the supercritical fluid permeating the thermoplastic resin, the outer shape of the resin is regulated by the cavity of the mold, and then the mold is cooled and then released. Thus, a final molded product obtained by foaming the thermoplastic resin is manufactured.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a method for producing a resin foam molded article according to the present invention will be described with reference to the accompanying drawings, with reference to preferred embodiments. It should be noted that components used to carry out the method of the present invention, which are the same as or equivalent to those already described with respect to FIG. 2, are designated by the same reference numerals.
In addition, since the premise technology is a batch type foaming method in which carbon dioxide as a supercritical fluid is permeated into a thermoplastic resin, the concepts of terms such as a supercritical state, a critical state, and a subcritical state are the same as those described above. .

FIG. 1 is an explanatory view showing step by step a method of manufacturing a resin foam molded article according to an embodiment of the present invention. FIG.
In (1), reference numeral 20 indicates a molding die, and the molding die 2
Numeral 0 defines a cavity 24 for regulating the outer shape of the final foam molded article 22 shown in FIG. 1 (4), and is configured as a box-shaped structure capable of withstanding a required internal pressure. The molding die 20 has a lid member 26, the upper opening of which can be closed and opened by the lid member 26, and an appropriate number of fluid introduction holes 28 and fluid escape holes 30. .
In addition, even if it says the fluid introduction hole 28 and the fluid escape hole 30,
This is a mere through hole communicating between the inside and outside of the molding die 20, and the fluid introduction hole 28 can be used for fluid escape, and the fluid escape hole 30 can be used for fluid introduction. It is relative in meaning.

After a thermoplastic resin 12 such as polypropylene (PP) is charged into the molding die 20 through an upper opening, it is closed by a lid member 26. As the thermoplastic resin 12, in addition to the polypropylene, polyethylene terephthalate (PET), low density polyethylene (LD)
PE), high density polyethylene (HDPE), linear low density polyethylene (L-LDPE) and the like are preferably used. The thermoplastic resin 12 may be in the form of a pellet or a powder, but since it is easy for air to be entrained during melting, the thermoplastic resin 12 is formed into a block having a smaller volume than the cavity 24 of the molding die 20. Is preferred. In this case, it is more preferable that the shape of the block-shaped thermoplastic resin 12 accommodated in the cavity 24 be a similar shape smaller than the internal shape of the cavity 24. For example, if the internal shape of the cavity 24 is a rectangular box shape, the resin block also has a corresponding box shape, and if the cavity has a conical shape, the resin block also has a conical shape, and further, the cavity has a dumbbell shape. In other words, the resin block also has a dumbbell shape. In addition, as shown in Experimental Example 3 to be described later, the expansion ratio of the final molded product 22 can be controlled by selecting the size of the thermoplastic resin 12 charged into the molding die 20.

The molding die 20 containing the thermoplastic resin 12 therein is accommodated in the pressure vessel 10 as shown in FIG. 1 (2), and then the opening and closing lid 32 is closed. A seal is made. The pressure vessel 10 is connected to the above-described carbon dioxide supercritical fluid supply source 14 via a pipe 16 and a valve element 17 and is provided with a heating means (not shown) such as an electric heater. Can be controlled within a predetermined range. When the valve 17 is opened, a supercritical fluid of carbon dioxide is introduced from the fluid supply source 14 into the pressure vessel 10. As mentioned earlier,
In the initial stage when the supercritical fluid is introduced into the pressure vessel 10, the critical pressure of the supercritical fluid temporarily drops to carbon dioxide in a gaseous state, but the supercritical fluid is continuously supplied into the vessel. As a result, the pressure reaches the critical pressure and is filled with the supercritical fluid.

The carbon dioxide as a supercritical fluid introduced into the pressure vessel 10 as described above passes through the fluid introduction / exit holes 28 and 30 of the mold 20 housed in the vessel 10 to form the mold 20. And comes into contact with the thermoplastic resin 12 housed therein. As described above, the supercritical fluid has a higher density than a gas, has a lower viscosity than a liquid, and is very easily diffused in a substance. Therefore, the fluid in contact with the thermoplastic resin 12 is easily dispersed in the resin. Penetrate. At this time, heating the pressure vessel 10 by the above-described heating means and also heating the molding die 20 to heat the thermoplastic resin 12 therein can increase the efficiency of penetrating the supercritical fluid into the resin. Is preferred. However, this heating is not a requirement so long as the supercritical fluid is only allowed to penetrate into the resin.

In a stepwise manner, the supercritical fluid is
After sufficient penetration, the above-mentioned heating may be performed. In this case, the heating temperature is equal to or higher than the crystallization temperature specific to the thermoplastic resin 12. The specific crystallization temperature depends on the type of the thermoplastic resin 12, and for example, when linear low-density polyethylene (L-LDPE) is used, the temperature is selected to be about 109 ° C. The rate at which this supercritical fluid permeates the thermoplastic resin 12 depends on the pressure,
Depends heavily on temperature and time functions. The expansion ratio of the final foam molded product 22 also depends on the function of pressure, temperature and time. Tables 1 and 2 below show changes in the expansion ratio due to differences in pressure and temperature, and Table 3 shows changes in the expansion ratio due to differences in time.

As described above, the supercritical fluid is infiltrated into the thermoplastic resin 12, and simultaneously with or after the infiltration,
By heating the pressure vessel 10 as described above, the resin 12 in the mold 20 is heated to a crystallization temperature specific to the resin or more. Next, as shown in (3) of FIG. 1, when the opening / closing lid 32 of the pressure vessel 10 is gradually opened to the atmosphere at a required pressure, for example, at 1 MPa / sec, the supercritical fluid in the mold 20 becomes the fluid. Escape from the introduction / escape holes 28, 30. When the pressure is released, the supercritical fluid of carbon dioxide permeating the thermoplastic resin 12 undergoes a phase change (vaporization) to a normal gas. With the vaporization of the supercritical fluid, the thermoplastic resin 12 expands and foams to generate extremely fine bubbles inside, and the outer shape of the thermoplastic resin 12 is regulated by the cavity 24 of the mold 20 with the expansion. Is done.

After the foaming of the thermoplastic resin 12 in the molding die 20 is completed, the molding die 20 is taken out of the pressure vessel 10 and cooled by water cooling or air cooling as shown in FIG. Then, by opening the lid member 26 of the mold 20 and removing the mold, a final molded product 22 in which the thermoplastic resin 12 is expanded and expanded is obtained.

[0020]

[Experimental example 1] Linear low density polyethylene (L-LDPE)
As a sample, an experiment was conducted to confirm the shape due to the difference in foaming conditions. (1) Linear low-density polyethylene (NUCG-7641) manufactured by Nippon Unicar Co., Ltd. was used as a sample. Its properties were as follows: Melting temperature (Tm): 119 ° C. Crystallization temperature (Tc): 109 ° C. Melt index (MI): 0.7 g / min Specific gravity: 0.92 (2) The following values were selected as operating conditions of the pressure vessel. Osmotic pressure: 8 MPa, 15 MPa, 20 MPa Osmotic temperature: 100 ° C, 105 ° C, 110 ° C, 115 ° C,
120 ° C, 125 ° C Penetration time: 2 hours, 45 minutes (3) Result 1

[Table 1] Table 1 shows the change in the expansion ratio due to the difference in the penetration pressure and the penetration temperature when the penetration time was set to 2 hours. In the table, "F" indicates an example in which the pressure was released rapidly at 1 MPa / sec, and "S" indicates that the pressure was released at 1 MPa.
This shows an example where the measurement was performed slowly for / 5 seconds. By the way, at a permeation temperature of 125 ° C., the sample was judged to be unobservable because the linear low-density polyethylene sample was reconstituted after foaming. According to Table 1, the permeation pressure is 15M at the permeation temperature of 110 ° C.
In the case of Pa / sec, a foaming ratio of 92 was obtained, and it was found that foaming was most excellent. It is not necessary to heat the sample in order for the supercritical fluid to penetrate into the sample, but it is necessary to heat the sample to the crystallization temperature in order to cause foaming, which further leads to melting of the sample. It was found that heating to temperature was not allowed. That is, the upper limit of the heating is the melting temperature of the thermoplastic resin as the sample, and the lower limit of the heating is the crystallization temperature specific to the sample. (4) Result 2

[Table 2] Table 2 shows the quality of the appearance and shape of the molded product depending on the difference in the penetration pressure and the penetration temperature when the penetration time was set to 45 minutes. At an infiltration temperature of 110 ° C, an infiltration pressure of 20 MPa /
In the case of 5 seconds, and at an infiltration temperature of 115 ° C. and an infiltration pressure of 20 M
In the case of Pa / 5 seconds, a product having perfect appearance and shape was obtained. In order to make foaming as clean as possible in as short a time as possible, the higher the permeation pressure, the more carbon dioxide permeates the sample and the smaller the cell diameter after foaming.

[0021]

[Experimental example 2] Linear low density polyethylene (L-LDPE)
Was used as a sample, an experiment was conducted to confirm a change in expansion ratio due to a difference in foaming conditions. (1) Linear low-density polyethylene (NUCG-7641) manufactured by Nippon Unicar Co., Ltd. was used as a sample. Its properties were as follows: Melting temperature (Tm): 119 ° C. Crystallization temperature (Tc): 109 ° C. Melt index (MI): 0.7 g / min Specific gravity: 0.92 (2) The following values were selected as operating conditions of the pressure vessel. Penetration pressure: 15MPa Penetration temperature: 110 ° C Penetration time: 2 hours, 1 hour, 30 minutes, 15 minutes, 5 minutes Mold size: Box shape (20 × 20 × 20) Input sample weight: 0.74 g Dimension ≒ 9 × 9 × 9 Cylindrical (φ20 × 20) Input sample weight: 0.57 g Size ≒ 8.5 × 8.5 × 8.5 Cylindrical (φ10 × 50) Input sample weight: 0.36 g Size ≒ 4.5 × 4.5 × 20 (3) Result

[Table 3] Table 3 shows the change in the expansion ratio due to the difference in the permeation time when the permeation pressure is set to 15 MPa and the permeation temperature is set to 110 ° C. Under these conditions, regardless of the size of the mold, the best expansion ratio of 15.3 can be obtained with a permeation time of 30 minutes, and there is no effect even if the permeation time is increased to 1 hour or 2 hours. I understood. When the expansion ratio becomes 20 times or more, the molded product shrinks.

[0022]

[Experimental example 3] Linear low density polyethylene (L-LDPE)
Was used as a sample, an experiment was conducted to confirm the change in the expansion ratio due to the difference in the size of the sample. That is, since the molding die 20 is used in the method of the present embodiment, the inner volume of the cavity 24 is regulated to be constant. Therefore, the sample put into the cavity 24 of the mold 20 does not become larger than the internal volume of the cavity 24 even by the expansion and foaming. Therefore, by changing the size of the sample put into the molding die 20, the expansion ratio can be adjusted within a certain range. (1) Linear low-density polyethylene (NUCG-7641) manufactured by Nippon Unicar Co., Ltd. was used as a sample. Its properties were as follows: Melting temperature (Tm): 119 ° C Crystallizing temperature (Tc): 109 ° C Melt index (MI): 0.7 g / min Specific gravity: 0.92 (2) The following values were selected as operating conditions. Mold size: 20mm x 20mm x 20mm Cavity volume: 8000mm ³ Input sample weight: 8g → L-LDPE 7.36g (3) Result

[Table 4] Table 4 shows that the expansion ratio can be controlled in proportion to the weight (volume) of the thermoplastic resin sample to be charged. Therefore, if the internal volume of the cavity in the mold is 100
, The volume of which is 10 times smaller
When the sample is charged and foamed, a product having a foaming ratio of 10 times can be obtained. Also, the volume becomes 1/5
If the sample of No. 0 is foamed, a product having a foaming ratio of 5 times can be obtained. Table 4 shows that the time required for infiltration to the center varies depending on the size of the sample to be charged.

[0023]

As described above, according to the present invention, when adopting a batch type foaming method in which carbon dioxide as a supercritical fluid is permeated into a thermoplastic resin and foamed, a required shape is previously formed in a molding die. There is an advantage that a final foam molded article can be manufactured in a molded form. In addition, by appropriately selecting the size, pressure, temperature, and time of the thermoplastic resin to be injected into the molding die, the expansion ratio of the final foamed molded product can be freely controlled, and the supercritical fluid of carbon dioxide is permeated. Since it is foamed later, it has many excellent advantages such as obtaining a uniform and fine cell-shaped foam.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing step by step a method for suitably manufacturing a resin foam molded article according to an embodiment of the present invention.

FIG. 2 is a schematic explanatory view showing an example of a batch type foaming method using carbon dioxide in a supercritical state.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Pressure vessel 12 Thermoplastic resin 14 Gas supply source 20 Mold 22 Final foaming molded product 24 Cavity 28, 30 Fluid introduction / exit hole

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F212 AA04 AA11 AA25 AC01 AG20 UA01 UF01 UL08 UN11

Claims (9)

[Claims] 1. The required thermoplastic resin to be foamed (12)
Is sealed in a pressure vessel (10), and then a supercritical fluid obtained by controlling the temperature and pressure of carbon dioxide is supplied from the fluid supply source (14) into the pressure vessel (10). By contacting the supercritical fluid with the thermoplastic resin (12), the supercritical fluid penetrates into the resin, and further the thermoplastic resin (1
2) is heated to a crystallization temperature (Tc) or more specific to the resin, and then the pressure vessel (10) is opened to the atmosphere, whereby the supercritical fluid permeating the thermoplastic resin (12) is A method for producing a resin foamed product by expanding and foaming the resin with the vaporization of a fluid, comprising a cavity (24) for regulating the outer shape of the final foamed molded product (22) inside, and a suitable fluid introduction / escape The thermoplastic resin (12) was housed in a mold (20) having holes (28, 30), and the mold was clamped.The mold (20) was housed in the pressure vessel (10). Later, the pressure vessel (10) is sealed, and the supercritical fluid supplied into the pressure vessel (10) from the fluid supply source (14) is passed through the fluid introduction / exit holes (28, 30). The supercritical fluid permeates into the resin by contacting the thermoplastic resin (12) in the molding die (20), and the crystallization temperature of the thermoplastic resin (12) in the molding die (20). (Tc)
By opening the pressure vessel (10) after heating as described above, the resin (12) is expanded and foamed with the vaporization of the supercritical fluid permeating the thermoplastic resin (12), and the molding is performed. The outer shape of the resin (12) is regulated by the cavity (24) of the mold (20), and then the mold (20) is cooled and then demolded,
A method for producing a resin foam molded article, characterized by producing a final molded article (22) obtained by foaming the thermoplastic resin (12). 2. A resin foam molded article according to claim 1, wherein a critical point temperature required to convert the carbon dioxide into a supercritical fluid is 31.2 ° C. or more, and a critical point pressure is 7.47 MPa or more. Method. 3. The resin according to claim 1, wherein the time required for permeating carbon dioxide as a supercritical fluid into the thermoplastic resin (12) in the mold (20) is in the range of 5 minutes to 2 hours. A method for producing a foam molded article. 4. The resin foam molded article according to claim 1, wherein the pressure vessel (10) supplied with the supercritical fluid is preferably gradually opened, and a release pressure at that time is, for example, 1 MPa / sec. Production method. 5. The supercritical fluid in the mold (20) escapes from the fluid inlet / outlet holes (28, 30) as a carbon dioxide gas by opening the pressure vessel (10). 5. The method for producing a resin foam molded article according to 4. 6. The thermoplastic resin (12) is, for example, polypropylene (PP), polyethylene terephthalate (PE).
T), low density polyethylene (LDPE), high density polyethylene (HDPE), linear low density polyethylene (L-LDP
The method for producing a resin foam molded article according to claim 1, wherein E) is suitably used. 7. The method according to claim 6, wherein the thermoplastic resin (12) is contained in the molding die (20) in the form of pellets, powder, other blocks, or the like. 8. The method for producing a resin foam molded article according to claim 6, wherein the temperature of the mold (20) in which the thermoplastic resin (12) is accommodated is set to a temperature higher than a crystallization temperature specific to the resin. . 9. The crystallization temperature specific to the thermoplastic resin (12) is 1 in linear low-density polyethylene (L-LDPE).
The method for producing a resin foam molded article according to claim 8, wherein the temperature is 09 ° C.