KR100719487B1 - Manufacturing method for polyolefin forming material using supercritical fluid - Google Patents

Abstract

The present invention relates to a method for producing a polyolefin foam (polyolefin forming material) using a supercritical fluid, and more particularly, in the production of a conventional polyolefin foam, by applying a foaming agent containing a supercritical fluid to a polyolefin foam It relates to a manufacturing method.

In the method for preparing a polyolefin foam using the supercritical fluid of the present invention, in the preparation of a polyolefin foam, a polyolefin, water, and a first foaming agent are added to a main reactor and heated, and a second foaming agent in a pretreatment reactor after the main reactor is heated. Injecting the critical fluid into the main reactor, and injecting the supercritical fluid into the main reactor, followed by foaming under the main reactor.

The method for producing a polyolefin foam using the supercritical fluid of the present invention has a high productivity per unit time by simplifying the foam manufacturing process using the supercritical fluid, and has a large energy saving effect, and thus has an economical ripple effect. In addition to polyolefin resin, it is possible to expand the technology in other synthetic resin parts.

Description

Manufacturing method for polyolefin forming material using supercritical fluid

Figure 1 is a block diagram of the apparatus used in the production of polypropylene foam in Example 1.

2 (a) to 2 (d) are SEM images of polypropylene foams prepared by varying the content of isobutane in Example 1. FIG.

3 (a) and 3 (e) are SEM images of the respective polypropylene foams prepared in Example 2. FIG.

4 (a) and 4 (d) are SEM images of the respective polypropylene foams prepared in Example 3. FIG.

5 (a) and 5 (d) are SEM images of each polypropylene foam prepared in Example 4. FIG.

6 (a) and 6 (c) are SEM images of the respective polypropylene foams prepared in Example 5. FIG.

7 (a) and 7 (c) are SEM images of the respective polypropylene foams prepared in Example 6. FIG.

8 (a) and 8 (d) are SEM images of the respective polypropylene foams prepared in Example 7. FIG.

9 (a) and 9 (b) are SEM images of the respective polypropylene foams prepared in Example 8. FIG.

10 (a) to 10 (c) are SEM images of the respective polypropylene foams prepared in Example 9. FIG.

11 (a) to 11 (c) are SEM images of the respective polypropylene foams prepared in Example 10.

12 (a) and 12 (b) are SEM images of the respective polypropylene foams prepared in Example 11. FIG.

13 (a) to 13 (c) are SEM photographs of the respective polypropylene foams prepared in Example 12. FIG.

14 (a) to 14 (c) are SEM images of the respective polypropylene foams prepared in Example 13. FIG.

15 (a) to 15 (c) are SEM images of the respective polypropylene foams prepared in Example 14. FIG.

<Explanation of symbols for the main parts of the drawings>

1: supercritical carbon dioxide storage 5: isobutane storage tank

6: water storage tank 7: heater

8: main reactor 14: pretreatment reactor

13: foam storage 16: vacuum pump

The present invention relates to a method for producing a polyolefin foam (polyolefin forming material) using a supercritical fluid, and more particularly, in the production of a conventional polyolefin foam, by applying a foaming agent containing a supercritical fluid to a polyolefin foam It relates to a manufacturing method.

At normal temperatures and pressures, the materials that become gas and liquid also exceed the limits of a certain high temperature and high pressure, called the supercritical point, so that the evaporation process does not occur and the gas and liquid cannot be distinguished. Is called supercritical fluid.

For example, when water is made into 374 degreeC or more and 220 atmospheres or more, it becomes a supercritical material which is neither liquid nor gas.

Supercritical fluids are characterized by large molecular density changes. The density of the molecule is close to liquid, but the viscosity is low, close to gas. In addition, the diffusion is fast, the thermal conductivity is as high as water.

In general, the gas as a blowing agent penetrates into the polymer particles to form a cell by controlling temperature, pressure, and time, which are process operating variables, in a state in which a polymer plastic, which is a reactant of a foam, and a blowing agent, which are gases, are simultaneously included.

The purpose of the foam is to reduce the weight, cushioning, flotation, absorbency, decoration, touch, cost reduction and dimensional stability of the product.

The foaming agent used to obtain the foam is classified into a physical foaming agent and a chemical foaming agent, and the chemical foaming agent is further divided into an inorganic chemical foaming agent and an organic chemical foaming agent.

Exemplary physical foaming agents include low molecular hydrocarbons such as butane and pentane, and chemical foaming agents include inorganic blowing agents such as sodium hydrogen carbonate (NaHCO ₃ ) and organic blowing agents such as ADAC, OBSH, and Toluene Sulfonyl Hydrazide (TSH). However, most chemical foaming agents are mostly organic foaming agents, and inorganic foaming agents make up about 2 to 3% of the total.

The polyolefin resin foam appears in a form developed through the process of melting a solid resin and dispersing and swelling a gaseous blowing agent therein. This synthetic resin foam has a large energy saving effect due to its excellent heat insulating ability, light weight, and shock absorption ability, and is used in various industries such as general industry, construction, and daily life.

In the preparation of the polyolefin resin foam, the blowing agent is mainly used isobutane (isobutane), but isobutane is expensive and not environmentally friendly, a new blowing agent is required to solve this problem.

On the other hand, looking at the domestic and international related technology related to the present invention, domestic polyolefin foam manufacturers are about three companies introduced in Japan and do not have their own technology. At present, production is in the early stages of small-scale production, and production is expected to increase rapidly when process technology development and various product developments take place. In addition, the more severe the environmental regulations, the more difficult the existing process will be, and the scope of application of this technology will be further expanded.

Therefore, since this technology development is in its infancy, it is easier to access than other technologies at the present time, and the necessity of related technology development is increasing as the scope of application is expanded. Overseas, two Japanese companies dominate the world market and establish a monopoly system.

The domestic and international patents related to these technologies are registered as general technical patents that swell under high pressure, but there is no technology for manufacturing a light-insulating lightweight structure in a supercritical state while having a low environmental impact.

In the existing process, carbon dioxide, which is harmless to the environment, is used as a blowing agent, making it difficult to manufacture ultra-low density resins, which eventually requires a two-step process. This makes the manufacturing process complicated and economics low.

Therefore, when the supercritical process for manufacturing the heat insulation lightweight structure is developed, the process is simplified, so that the productivity per unit time is high, and the energy saving effect is large, and the economic ripple effect is large due to the technology spread. In addition, as the technology can be expanded in other synthetic resins, the potential market size is expected to be very large.

An object of the present invention is to provide a method for producing an environmentally friendly polyolefin foam including a supercritical fluid of a kind harmless to the environment when preparing a conventional polyolefin foam as a blowing agent.

Since supercritical fluid is in a state where gas and liquid properties coexist, foaming is performed because molecular motion, which is an advantage of gas, is active and diffusion is rapid, and solubility of supercritical fluid is increased in polyolefin resin, which is a material of foam, which is an advantage of liquid. The time required for shortening increases productivity.

Therefore, the method for producing a polyolefin foam using the supercritical fluid of the present invention has a high productivity per unit time by simplifying the foam manufacturing process using the supercritical fluid, and the energy saving effect is large, and the economic ripple effect is large due to the technology spread. In addition to polyolefin resin, it is possible to expand the technology in other synthetic resin parts.

The method for producing a polyolefin foam using the supercritical fluid of the present invention for achieving the above-mentioned object is a step of adding a polyolefin, water, a first foaming agent to the main reactor in the production of a polyolefin foam, heating the inside of the pretreatment reactor Injecting the supercritical fluid of the second foaming agent into the main reactor, heating the main reactor and the pretreatment reactor to react at a desired temperature and pressure, and foaming in the lower part of the main reactor after the reaction.

In the present invention, when the polyolefin foam is produced, the polyolefin foamed by the foaming agent to be a foam is a copolymer of a polyolefin polymerized with an olefin monomer, a polyolefin copolymer polymerized with another type of olefin monomer, a copolymer of an olefin monomer and a non-olefin monomer such as vinyl acetate and styrene. Any one or more selected from one polyolefin copolymer may be used. Examples of such polyolefins in the present invention include polyethylene, polypropylene, polyisobutylene, ethylene-propylene copolymer, ethylene-propylene-butene copolymer, ethylene-propylene-butadiene copolymer, ethylene-styrene copolymer, ethylene-propylene- Any one or more selected from styrene copolymer and propylene-styrene copolymer may be used.

In the present invention, after the polyolefin, the first foaming agent and the water in the main reactor, the heating is preferably heated to a temperature before the polyolefin is completely melted while having fluidity. That is, when the polyolefin is melted, the blowing agent is difficult to penetrate into the polyolefin evenly, and therefore, it is preferable to heat the polyolefin until it is completely melted while having fluidity. Such heating temperature may be appropriately performed by those skilled in the art according to the type of polyolefin. For example, in the production of polypropylene foam, heating may be performed at room temperature (25 ° C.) to a set temperature of 120 to 140 ° C. and maintained at the set temperature for 5 to 30 minutes.

In the present invention, in the preparation of the polyolefin foam, the blowing agent uses two types of first and second foaming agents at the same time.

In the above, the first foaming agent can be used any foaming agent conventionally used in the manufacture of conventional polyolefin foam. In the present invention, one or more selected from isobutane, butane, propane, and pentane may be used as an example of the first foaming agent used in manufacturing such a conventional polyolefin foam.

The second foaming agent uses a supercritical fluid. At this time, the supercritical fluid may be used as long as it is a supercritical state of a fluid that can be used as a blowing agent. As an example of the supercritical fluid which is a second foaming agent that can be used in the production of polyolefin in the present invention, any one or more selected from supercritical carbon dioxide, supercritical isobutane, supercritical butane, supercritical propane, and supercritical pentane may be used.

In the present invention, the second foaming agent may be used in an amount of 1 to 20 times that of the first foaming agent.

Meanwhile, in the preparation of the polyolefin foam of the present invention, the method further includes adding magnesium carbonate (MgCO ₃ ), which is a dispersant, in the addition of polyolefin and water to the reactor.

In the present invention, 200 to 2000 parts by weight of water, 5 to 50 parts by weight of the first foaming agent, and 50 to 1000 parts by weight of the second foaming agent may be used in the preparation of the polyolefin foam. At this time, the supercritical fluid as the second foaming agent may be supplied at a pressure of 20 to 100 kgf / cm ² . In addition, when the magnesium carbonate is further added to the water, the first foaming agent, and the second foaming agent, the magnesium carbonate may be used in an amount of 20 to 50 parts by weight based on 100 parts by weight of the polyolefin.

Since the polyolefin foam is prepared with various components and contents with respect to the present invention, it is preferable to prepare the polyolefin foam with the components and contents described above in order to prepare a foam that meets the purpose of the present invention.

Hereinafter, the content of the present invention will be described in detail through examples and test examples. However, these are intended to explain the present invention in more detail, and the scope of the present invention is not limited thereto.

<Example 1>

Hereinafter will be described in more detail with reference to the accompanying drawings, an example of the production of polyolefin foam of the present invention.

1 is an example of a device used in the production of the polyolefin foam of the present invention.

First, 100 g of polypropylene (SEP-740), 1000 g of water (H ₂ O), and 50 g of magnesium carbonate (MgCO ₃ , Showa Chemical INC) are added to the main reactor 8 to prevent leakage. Sealed.

Thereafter, the main reactor 8 and the pretreatment reactor 14 were vacuumed with a vacuum pump 16, and then 25-50 g of isobutane was injected into the main reactor from the isobutane storage tank 5.

After isobutane was placed in the main reactor, the heater 7 was used to heat the material at 25 ° C. to 120 ° C. at a rate of 5 ° C./min and from 120 ° C. to 126 ° C. at a rate of 1 ° C./min.

The temperature of the pretreatment reactor was heated to be the same as the temperature of the main reactor, and supercritical carbon dioxide of the supercritical carbon dioxide reservoir 1 was supplied to the inside of the pretreatment reactor in twice the amount of isobutane.

When heating is completed until the temperature inside the pretreatment reactor 14 reaches a temperature of 126 ° C. from room temperature, the supercritical carbon dioxide of the pretreatment reactor 14 is supplied into the main reactor 8 so that the pressure of the main reactor is 23.8∼. 24.8 kgf / cm ² .

When the internal temperature of the main reactor is 126 ° C and the pressure is 23.8-24.8kgf / cm ² , after maintaining the internal temperature and pressure of the main reactor for 10 minutes, open the valve 10-1 provided in the lower part of the main reactor and pretreatment at the same time. A valve (10-2) connected to the reactor and the main reactor was opened to stably obtain a polypropylene foam. By opening the valve (10-2) connected to the pretreatment reactor and the main reactor in the above, the supercritical fluid of the pretreatment reactor (14) continuously pressurizes the main reactor (8) and the valve (10-) below the main reactor (8). 1) It helps to stably produce foam in the product storage 13 outside the main reactor by suppressing sudden decompression inside the main reactor due to the opening.

Foamed polypropylene foam was attached to magnesium carbonate, washed with water and dried.

The description of the reference numerals in FIG. 1 is as follows.

2: regulator, 3: on / off valve, 4: valve, 6: water reservoir, 9: agitator, 10-1 to 10-4: valve, 11-1 to 11-4 temperature indicator, 12-1 to 12-3: pressure gauge, 15: air compressor

The polypropylene foam prepared above measured the pore shape and size formed by SEM (Scanning Electron Microscope) analysis and the results are shown in FIGS. 1 (a) to 1 (d).

2 (a) to 2 (d), the polypropylene foam of FIG. 2 (a) having an isobutane content of 25 g has a uniform pore shape but a small pore size of 20 to 30 μm.

2 (b) polypropylene foam having an isobutane content of 35 g shows a non-uniform pore form in which pores with small pore sizes and large pores of about 400 μm are formed together. However, as shown in FIGS. 2 (c) and 2 (d), it can be seen that as the content of isobutane increases, pores having a size of 300 to 400 μm and a uniform shape are generated.

In addition, the foaming ratio (Foaming ratio) and DSC (Differential Scanning Calorimetry) characteristics of the polypropylene foam prepared above were measured and the results are shown in Table 1 below.

Measuring the foaming ratio (foaming ratio), first select the foam to measure the mass by balance. This is placed in a mass cylinder containing a volume of water, which causes the foam to float on the water. It is a volumetric rod that sinks below the surface of the water and measures the total volume of water and foam. From this value, the volume of water and rod volume is subtracted to determine the volume of the pure foam, and divided by the initially measured mass to determine the foam volume per gram. This value was divided by the volume value per gram of polymer before foaming to determine the foaming ratio.

Table 1. Foam ratio of the polypropylene foam prepared in Example 1, DSC results

Foam Pressure (Kgf / cm ² ) Temperature (℃) Isobutane Content (g) Foam ratio DSC E (J / g) T _min (℃) T _max (℃) Figure 2a 24.6 126 25 3.757 46.131 130.0 145.96 Figure 2b 23.8 126 35 26.453 56.21 133.13 150.22 Figure 2c 24.9 126 45 56.774 61.97 134.62 151.04 Figure 2d 24.8 126 50 68.722 55.41 133.57 135.17

<Example 2>

20 g of isobutane was added to the inside of the main reactor, except that the temperature of the main reactor was maintained at 128 ° C. and the internal pressure of the main reactor by injection of supercritical carbon dioxide was 36.8˜64.5 kgf / cm ² . Polypropylene foams were prepared using the same method as in step 1.

SEM pictures of the polypropylene foam prepared above are shown in Figures 3 (a) to 3 (e), and the foaming ratio and DSC characteristics of each polypropylene foam were measured and the results are shown in Table 2 below. .

Table 2. Foam ratio of the polypropylene foam prepared in Example 2, DSC results

Foam Pressure Kgf / cm ² ) Temperature (℃) Isobutane Content (g) Foam ratio DSC E (J / g) T _min (℃) T _max (℃) Figure 3a 36.8 128 20 9.793 70.93 133.8 146.59 Figure 3b 41.7 128 20 9.012 71.51 130.44 145.33 Figure 3c 49 128 20 12.774 71.56 129.64 144.39 Figure 3d 50 128 20 8.516 78.83 130.4 144.76 Figure 3e 64.5 128 20 26.492 74.22 131.31 143.59

<Example 3>

Example 1, except that 20 g of isobutane was added to the inside of the main reactor, and the temperature of the main reactor was maintained at 130 ° C. and the internal pressure of the main reactor was 39 to 60 kgf / cm ² by injection of supercritical carbon dioxide. Polypropylene foams were prepared using the same method as described above.

SEM pictures of the polypropylene foam prepared above are shown in Figs. .

Table 3. Foam ratio of the polypropylene foam prepared in Example 3, DSC results

Foam Pressure (Kgf / cm ² ) Temperature (℃) Isobutane Content (g) Foam ratio DSC E (J / g) T _min (℃) T _max (℃) Figure 4a 39 130 20 15.177 83.86 130.63 146.77 Figure 4b 47.5 130 20 14.477 62.67 135.2 146.12 Figure 4c 49 130 20 20.225 66.75 130.32 144.88 Figure 4d 60 130 20 27.250 75.89 133.22 146.58

<Example 4>

Example 1 except that 20 g of isobutane was added to the inside of the main reactor, and the temperature of the main reactor was maintained at 132 ° C. and the internal pressure of the main reactor was 42.5 to 72 kgf / cm ² by injection of supercritical carbon dioxide. Polypropylene foams were prepared using the same method as described above.

SEM pictures of the polypropylene foam prepared above are shown in Figs. .

Table 4. Foam ratio of the polypropylene foam prepared in Example 4, DSC results

Foam Pressure (Kgf / cm ² ) Temperature (℃) Isobutane Content (g) Foam ratio DSC E (J / g) T _min (℃) T _max (℃) Figure 5a 42.5 132 20 23.608 66.26 131.4 147.08 Figure 5b 53.2 132 20 38.575 61.38 134.52 149.5 Figure 5c 59.5 132 20 35.820 44.39 134.42 149.6 Figure 5d 72 132 20 36.824 48.76 135.22 150.6

Example 5

30 g of isobutane was added to the inside of the main reactor, except that the temperature of the main reactor was maintained at 126 ° C. and the internal pressure of the main reactor by injection of supercritical carbon dioxide was 34.2 to 63.3 kgf / cm ² . Polypropylene foams were prepared using the same method as in step 1.

SEM pictures of the polypropylene foam prepared above are shown in FIGS. 6 (a) to 6 (c), and the foaming ratio and DSC characteristics of each polypropylene foam were measured and the results are shown in Table 5 below. .

Table 5. Foam ratios of the polypropylene foams prepared in Example 5, DSC results

Foam Pressure (Kgf / cm ² ) Temperature (℃) Isobutane Content (g) Foam ratio DSC E (J / g) T _min (℃) T _max (℃) Figure 6a 34.2 126 30 7.460 61.83 129.20 140.84 Figure 6b 42 126 30 15.805 58.61 135.0 145.99 Figure 6c 63.3 126 30 13.101 64.86 131.4 146.39

<Example 6>

30 g of isobutane was added to the inside of the main reactor, and the temperature of the main reactor was maintained at 128 ° C and the internal pressure of the main reactor by injection of supercritical carbon dioxide was 18 to 33.2 kgf / cm ² . Polypropylene foams were prepared using the same method as in step 1.

SEM pictures of the polypropylene foam prepared above are shown in Figs. .

Table 6. Foam ratios of the polypropylene foams prepared in Example 6, DSC results

Foam Pressure (Kgf / cm ² ) Temperature (℃) Isobutane Content (g) Foam ratio DSC E (J / g) T _min (℃) T _max (℃) Figure 7a 18 128 30 18.735 63.45 134.76 148.8 Figure 7b 14.5 128 30 21.289 77.74 129.62 144.58 Figure 7c 33.2 128 30 37.469 72.96 132.62 148.58

<Example 7>

30 g of isobutane was added to the inside of the main reactor, and the temperature of the main reactor was 130 ° C., except that the internal pressure of the main reactor was maintained at 19.6 to 38.6 kgf / cm ² by injection of supercritical carbon dioxide. Polypropylene foams were prepared using the same method as in step 1.

SEM pictures of the polypropylene foam prepared above are shown in Figs. .

Table 7. Foam ratio of the polypropylene foam prepared in Example 7, DSC results

Foam Pressure (Kgf / cm ² ) Temperature (℃) Isobutane Content (g) Foam ratio DSC E (J / g) T _min (℃) T _max (℃) Figure 8a 19.6 130 30 6.080 63.90 - 137.38 Figure 8b 23.7 130 30 6.642 78.76 132.7 145.82 Figure 8c 30 130 30 14.549 66.74 133.21 147.71 Figure 8d 38.6 130 30 27.710 73.03 132.33 145.71

<Example 8>

5 g of isobutane was added to the inside of the main reactor, and the temperature of the main reactor was 130 ° C., except that the internal pressure of the main reactor was maintained at 72.2 to 100.1 kgf / cm ² by injection of supercritical carbon dioxide. Polypropylene foams were prepared using the same method as in step 1.

SEM pictures of the polypropylene foam prepared above are shown in Figs. .

Table 8. Foam ratios of the polypropylene foams prepared in Example 8, DSC results

Foam Pressure (Kgf / cm ² ) Temperature (℃) Isobutane Content (g) Foam ratio DSC E (J / g) T _min (℃) T _max (℃) Figure 9a 72.2 130 5 7.664 88.39 - 146.49 Figure 9b 100.1 130 5 13.625 73.72 133.61 147.54

Example 9

Example 1 except that 5 g of isobutane was added to the inside of the main reactor, and the temperature of the main reactor was maintained at 134 ° C. and the internal pressure of the main reactor was 44.7 to 64 kgf / cm ² by injection of supercritical carbon dioxide. Polypropylene foams were prepared using the same method as described above.

SEM pictures of the polypropylene foam prepared above are shown in Figs. .

Table 9. Foam ratio, DSC results of polypropylene foam prepared in Example 9

Foam Pressure (Kgf / cm ² ) Temperature (℃) Isobutane Content (g) Foam ratio DSC E (J / g) T _min (℃) T _max (℃) Figure 10a 44.7 134 5 3.406 84.50 128.41 149.12 Figure 10b 60.7 134 5 11.922 101.5 130.70 148.37 Figure 10c 64 134 5 12.348 104.6 130.45 148.18

<Example 10>

5 g of isobutane was added to the inside of the main reactor, except that the temperature of the main reactor was maintained at 138 ° C. and the internal pressure of the main reactor was 37.9 to 51.6 kgf / cm ² by injection of supercritical carbon dioxide. Polypropylene foams were prepared using the same method as in step 1.

SEM pictures of the polypropylene foam prepared above are shown in FIGS. 11 (a) to 11 (c), and the foaming ratio and DSC characteristics of each polypropylene foam were measured, and the results are shown in Table 10 below. .

Table 10. Foam ratio of the polypropylene foam prepared in Example 10, DSC results

Foam Pressure (Kgf / cm ² ) Temperature (℃) Isobutane Content (g) Foam ratio DSC E (J / g) T _min (℃) T _max (℃) Figure 11a 37.9 138 5 14.477 85.23 133.98 152.52 Figure 11b 44.6 138 5 17.031 87.61 134.43 150.60 Figure 11c 51.6 138 5 20.438 86.06 134.03 152.60

<Example 11>

Example 1 except that 5 g of isobutane was added to the inside of the main reactor, and the temperature of the main reactor was maintained at 140 ° C., and the internal pressure of the main reactor was maintained at 19.5 to 30 kgf / cm ² by injection of supercritical carbon dioxide. Polypropylene foams were prepared using the same method as described above.

SEM pictures of the polypropylene foam prepared above are shown in FIGS. 12 (a) to 12 (b), and the foaming ratio and DSC characteristics of each polypropylene foam were measured and the results are shown in Table 11 below. .

Table 11. Foam ratio of the polypropylene foam prepared in Example 11, DSC results

Foam Pressure (Kgf / cm ² ) Temperature (℃) Isobutane Content (g) Foam ratio DSC E (J / g) T _min (℃) T _max (℃) Figure 12a 19.5 140 5 9.367 81.83 134.15 151.13 Figure 12b 30 140 5 15.328 95.28 133.81 150.57

<Example 12>

Example 1, except that 10 g of isobutane was added to the inside of the main reactor, and the temperature of the main reactor was maintained at 126 ° C. and the internal pressure of the main reactor by injection of supercritical carbon dioxide was 84 to 101 kgf / cm ² . Polypropylene foams were prepared using the same method as described above.

SEM pictures of the polypropylene foam prepared above are shown in FIGS. 13 (a) to 13 (c), and the foaming ratio and DSC characteristics of each polypropylene foam were measured and the results are shown in Table 12 below. .

Table 12. Foam ratio of the polypropylene foam prepared in Example 12, DSC results

Foam Pressure (Kgf / cm ² ) Temperature (℃) Isobutane Content (g) Foam ratio DSC E (J / g) T _min (℃) T _max (℃) Figure 13a 84 126 10 8.516 98.33 133.74 147.64 Figure 13b 93.9 126 10 9.367 87.42 131.33 147.42 Figure 13c 101 126 10 10.219 83.91 133.35 146.64

Example 13

10 g of isobutane is added to the inside of the main reactor, and the temperature of the main reactor is 130 ° C., except that the internal pressure of the main reactor is maintained at 50.6 to 66.2 kgf / cm ² by injection of supercritical carbon dioxide. Polypropylene foams were prepared using the same method as in step 1.

SEM pictures of the polypropylene foam prepared above are shown in FIGS. 14 (a) to 14 (c), and the foaming ratio and DSC characteristics of each polypropylene foam were measured, and the results are shown in Table 13 below. .

Table 13. Foam ratio of the polypropylene foam prepared in Example 13, DSC results

Foam Pressure (Kgf / cm ² ) Temperature (℃) Isobutane Content (g) Foam ratio DSC E (J / g) T _min (℃) T _max (℃) Figure 14a 50.6 130 10 6.813 95.45 127.47 148.25 Figure 14b 67.2 130 10 13.625 73.48 130.78 147.18 Figure 14c 69.2 130 10 11.922 50.15 128.82 147.93

<Example 14>

10 g of isobutane was added to the inside of the main reactor, except that the temperature of the main reactor was maintained at 134 ° C. and the internal pressure of the main reactor by injection of supercritical carbon dioxide was 32.1 to 63.4 kgf / cm ² . Polypropylene foams were prepared using the same method as in step 1.

SEM pictures of the polypropylene foam prepared above are shown in Figure 15 (a) to Figure 15 (c), the foaming ratio and DSC characteristics of each polypropylene foam was measured and the results are shown in Table 14 below. .

Table 14. Foam ratio of the polypropylene foam prepared in Example 14, DSC results

Foam Pressure (Kgf / cm ² ) Temperature (℃) Isobutane Content (g) Foam ratio DSC E (J / g) T _min (℃) T _max (℃) Figure 15a 32.1 134 10 6.292 91.16 130.23 148.25 Figure 15b 50.5 134 10 19.318 78.24 133.13 148.55 Figure 15c 63.4 134 10 27.781 86.10 133.32 150.08

<Example 15>

Example 1, except that 10 g of isobutane was added to the inside of the main reactor, and the temperature of the main reactor was maintained at 138 ° C. and the internal pressure of the main reactor was 25.6 to 60 kgf / cm ² by injection of supercritical carbon dioxide. Polypropylene foams were prepared using the same method as described above.

The foaming ratio for each polypropylene foam prepared above was measured and the results are shown in Table 15 below.

Table 15. Foam ratio of the polypropylene foam prepared in Example 15, DSC results

Pressure (Kgf / cm ² ) Temperature (℃) Isobutane Content (g) Foam ratio DSC E (J / g) T _min (℃) T _max (℃) 25.6 138 10 13.625 73.79 133.97 151.89 42.8 138 10 22.141 68.58 134.63 151.88 60 138 10 30.657 70.59 136-17 152.19

As described above, although described with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and modified within the scope of the present invention without departing from the spirit and scope of the invention described in the claims below. It will be appreciated that it can be changed.

When manufacturing a polyolefin foam including a supercritical fluid as a blowing agent in the production of the polyolefin foam of the present invention, the process is simplified compared to the manufacture of a foam without a supercritical fluid, thereby increasing productivity per unit time and increasing energy savings. The economic ripple effect is great. In addition, the potential market size is expected to be very large because the technology can be expanded in the synthetic resin portion using foam materials in addition to polyolefins.

Claims (7)

In preparing polyolefin foams, Adding and heating a polyolefin, water, a first blowing agent to the main reactor, Injecting a supercritical fluid, which is a second blowing agent inside the pretreatment reactor, into the main reactor, Heating and reacting the main reactor and the pretreatment reactor, maintaining the desired temperature and pressure; Method for producing a polyolefin foam using a supercritical fluid, characterized in that it comprises the step of foaming in the lower part of the main reactor after the reaction. The method of claim 1, wherein the polyolefin is a supercritical, characterized in that at least one selected from polyethylene, polypropylene, polyisobutylene, ethylene-propylene copolymer, ethylene-propylene-butene copolymer, ethylene-propylene-butadiene copolymer Method for producing a polyolefin foam using a fluid. The method of claim 1, wherein the first blowing agent is any one or more selected from isobutane, propane, butane and pentane. The polyolefin foam according to claim 1, wherein the supercritical fluid as the second foaming agent is any one or more selected from supercritical carbon dioxide, supercritical isobutane, supercritical butane, supercritical propane, and supercritical pentane. Manufacturing method. The method of claim 1, further comprising adding magnesium carbonate (MgCO ₃ ) when the polyolefin and water are added to the reactor. The method for producing a polyolefin foam using a supercritical fluid according to claim 1, wherein the heating is performed at a temperature of 120 to 140 ° C and a supercritical fluid is supplied at a pressure of ²⁰ to 100 kgf / cm ² . The method according to claim 1, wherein 200 to 1000 parts by weight of water, 5 to 50 parts by weight of the first foaming agent and the second foaming agent are used up to 1 to 20 times the content of the first foaming agent with respect to 100 parts by weight of polyolefin. Method for producing polyolefin foam using a critical fluid.

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