KR101808736B1 - Manufacturing method of expanded polystyrene foam - Google Patents

Abstract

The present invention relates to a method for manufacturing a foamed polystyrene foam, which comprises the following steps: adding 85 to 105 wt% of a polystyrene powder, 3 to 7 wt% of a flame retardant, 1 to 5 wt% of an expanded graphite powder or a loess powder, and 0.5 to 2 wt% of a nucleating agent to an extruder and melting the mixture to manufacture a molten material; and adding a foaming agent to the molten material and extruding the mixture, wherein the foaming agent is a mixed foaming agent in which a liquid foaming agent and a gas foaming agent are mixed. It is an object of the present invention to provide the method for manufacturing a foamed polystyrene foam having uniform size and shape by foaming to improve a heat insulating property and the strain rate by applying the mixed foaming agent to the foaming process.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for manufacturing expanded polystyrene foam,

The present invention relates to a method for producing expanded polystyrene foam, and more particularly, to a method for producing foamed polystyrene foam including graphite or loess to improve the heat insulating performance.

In general, the polystyrene foam used for thermal insulation optimizes the expansion density and the additive material of the foam in order to improve the heat insulation performance.

For example, Korean Patent Publication Nos. 10-0750626 and 10-1484615 disclose a method for producing a polystyrene foam containing graphite and a nucleating agent and a foaming agent to form a foam having a low thermal conductivity and excellent in heat insulation property have.

In the prior art, it is described that any one of water, alcohol, pressurized and liquefied HCFCs, butane, CO ₂ and DMC can be used as a blowing agent. By using such a blowing agent, a density of 30 g / have.

In Korean Patent Laid-Open Publication No. 10-2017-0055437, expanded graphite powder coated with a resin composition for coating is used in order to improve the heat insulation. In Korean Patent Registration No. 10-1179943, expanded graphite and expanded polystyrene A method of producing a foam is disclosed.

However, the polystyrene foam according to the related art has a problem that the uniformity of the pores formed by the foaming is low and the shape is irregular so that the overall heat insulation performance of the foam or the variation of the heat insulation performance depending on the manufacturing process conditions is large, have.

Korean Patent Publication No. 10-0750626 Korean Patent Publication No. 10-1484615 Korean Patent Publication No. 10-2017-0055437 Korean Patent Publication No. 10-1179943

SUMMARY OF THE INVENTION The present invention has been conceived in view of the above-mentioned prior art, and provides a method for manufacturing a foamed polystyrene foam having excellent heat insulation and low strain by mixing graphite powder or loess powder and mixing it with a liquid and a gas foaming agent The purpose of that is to do.

It is another object of the present invention to provide a method for producing a foamed polystyrene foam having a foamed foam having uniform size and shape and improved heat insulation and low strain rate by applying a mixed foaming agent to a foaming process.

In order to accomplish the above object, the present invention provides a method for producing expanded polystyrene foam, which comprises: mixing 85 to 105 parts by weight of polystyrene powder, 3 to 7 parts by weight of a flame retardant, 1 to 5 parts by weight of expanded graphite powder or loess powder, To produce a melt to be melted; And injecting the blowing agent into the melt and extruding the blowing agent, wherein the blowing agent is a mixed blowing agent in which a liquid blowing agent and a gas blowing agent are mixed.

At this time, the polystyrene powder may contain 30 to 40 parts by weight of the recovered polystyrene powder.

The mixed foaming agent can be produced by heating and vaporizing the liquid foaming agent, and simultaneously injecting the vaporized liquid foaming agent and the gas foaming agent into the extruder.

The gas foaming agent constituting the mixed foaming agent is any one of carbon dioxide, methane, propane and cyclopentane, and the liquid foaming agent is any one of ethanol, propanol and isopropanol.

According to the method for producing a foamed polystyrene foam according to the present invention, a foamed polystyrene foam having excellent heat insulation and low strain can be produced by mixing graphite powder or loess powder and mixing the liquid and gas blowing agents and applying it to the foaming process.

Further, by applying the mixed foaming agent to the foaming step, it is possible to produce a foamed polystyrene foam having a uniform size and shape of bubbles formed by foaming and having improved heat insulation and low strain rate.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a process diagram showing a production process of a foamed polystyrene foam according to the present invention. FIG.

Hereinafter, a method for producing expanded polystyrene foam according to the present invention will be described in detail.

The manufacturing process of the foamed polystyrene foam according to the present invention is as shown in FIG.

First, a raw material for producing a foam is put into an extruder, and a melt is produced through mixing and melting. In this state, a blowing agent is injected to perform a foaming step. The foaming agent is a mixed foaming agent in which a liquid foaming agent and a gas foaming agent are mixed.

The shape of the foams and pores is influenced by the process conditions such as the amount of the foaming agent and the temperature, and it is known that the effect depends on the type of the foaming agent. The blowing agent used in the conventional foaming process was a freon gas (CFC type). However, since the use thereof is strictly regulated due to environmental problems, the blowing agent is replaced with another gas.

As the foaming gas, carbon dioxide, hydrocarbons such as methane and propane, and inert gases such as helium and argon can be used. However, such a foaming gas has a disadvantage in that the foaming efficiency is lower than that of the existing freon gas. There is a problem that the shape of the polystyrene foam product becomes uneven, and this affects the heat insulating property of the polystyrene foam product.

The lowering of the foaming efficiency is not limited to the size and shape of the pores of the foam. If the gas other than the freon gas is used, the thickness of the foam must be thicker in order to form the foam of the same density, And that when the foam of the same volume is produced, the density can not be obtained as much as when the Freon gas is used as the blowing agent.

As a result of various experiments to optimize the foaming process in order to solve such a problem, it has been found that the foaming efficiency of the polystyrene foam can be improved when the composite foaming agent is used, thereby completing the present invention.

The composite foaming agent to be used in the foaming step of the present invention is a mixture of a gas foaming agent and a liquid foaming agent. The gas foaming agent is any one of carbon dioxide, methane, propane and cyclopentane. The liquid foaming agent is any one of ethanol, propanol, and isopropanol The optimum foaming process can be performed.

Particularly, when a composite foaming agent is used, the same degree of density can be ensured even when the thickness of the foaming agent of the same component is reduced by about 20% compared with the foaming agent produced by using the foaming agent as a foaming agent. It is possible to reduce the volume of the container by weight.

Accordingly, the raw material for producing the foam is put into an extruder, the temperature of the blowing agent to be fed into the extruder is controlled in a state where the melt is produced through mixing and melting, and the liquid foaming agent and the gas foaming agent are heated to vaporize the liquid foaming agent At the same time, they are introduced into an extruder and mixed to perform a foaming process.

Of course, water, alcohol, freon gas, butane, carbon dioxide, and DME are listed as blowing agents in the prior art Korean Patent Registration No. 10-0750626 and Korean Patent Registration No. 10-1484615, and both gas foaming agent and liquid foaming agent are included, But they are not aware of the unique solution of the present invention for improving the foaming performance by combining them.

The raw material for producing the foam in the present invention is composed of 85 to 105 parts by weight of polystyrene powder, 3 to 7 parts by weight of a flame retardant, 1 to 5 parts by weight of expanded graphite powder and 0.5 to 2 parts by weight of a nucleating agent, A color system product can be finally obtained. Therefore, 0.2 to 0.9 parts by weight of pigment may be blended for controlling the hue, and 1 to 2 parts by weight of an ultraviolet screening agent may be blended to impart ultraviolet shielding property depending on the application .

The polystyrene powder may contain 30 to 40 parts by weight of the recycled polystyrene powder. That is, 55 to 65 parts by weight of polystyrene powder and 30 to 40 parts by weight of recovered polystyrene powder can be mixed and used. In this case, waste can be recycled while lowering the unit cost of raw materials, so that environmentally friendly products can be produced.

The regenerated polystyrene powder accounts for 45 to 70% by weight of the total polystyrene powder. If too much regenerated polystyrene powder is used, the heat insulating property of the product varies greatly. If the regenerated polystyrene powder is used in an excessively small amount, It is suitable to use within the above range.

In addition, expanded graphite in the present invention is widely used in the prior art as a component used for improving the heat insulating property. In the present invention, expanded graphite powder having a particle size of 1000 to 1300 mesh is used, which not only improves the heat insulating property but also improves the uniformity of pore size and shape in the process of using the mixed foaming agent of the present invention. That is, when the pores are formed in the foaming process, the expanded graphite powder plays a role of blocking the gas exhaust holes of the pores formed therein, and thus it has a great effect on the size and shape uniformity of the pores after foaming.

The expanded graphite showed the most optimized results in the size and shape of the pores as well as the improvement of the heat insulating properties when used in the range of 1 to 5 parts by weight.

Further, Korean Patent Publication No. 10-1179943 discloses that flame-retardant properties can be improved by blending yellow loam.

In the present invention, the loess having a particle size of 400 to 500 mesh is used to improve the heat insulating property. This is to improve not only the adiabatic property but also the uniformity of the pore size and shape in the process of using the mixed blowing agent of the present invention. That is, when the pores are formed in the foaming process, it plays a role of blocking the gas exhaust holes of the pores formed with the ocher powder, and thus it has a great influence on the size and shape uniformity of the pores after foaming.

It was found that the use of the loess in the range of 1 to 5 parts by weight improves the adiabatic property and the most optimized result in the size and shape of the pores.

Further, a flame retardant is used as a raw material for producing the foam of the present invention, because flame retardant properties are simultaneously required when foamed polystyrene foam is used as an insulation material.

Examples of such flame retardants include bisphenol A-bis (diphenyl phosphate), TPP (triphenyl phosphate), TCPP (tris (2-chloro isopropyl) phosphate), TDCP (tris (1,3-dichloro- (PTFE), decabromodiphenyl oxide (DBDPE), tetrabromobisphenol A bis (2,3-dibromopropyl ether), HBCD (hexabromocyclododecane), TBBA (tetrabromobisphenol A), brominated polystyrene (BPS), and the like can be used.

If the content of the flame retardant is too large, defects may occur in the foaming step or the molding step. When the content is too small, sufficient flame retardancy characteristics can not be obtained.

The nucleating agent is used to induce the foaming of polystyrene. Any one or more of zinc stearic acid, titanium dioxide, Accra wax C and ethenyl benzene homopolymer may be used. The amount of the nucleating agent used is 0.5 to 2 parts by weight Do. That is, if the amount of the nucleating agent used is too small, the foaming becomes insufficient, and if it is too much, loss of the foaming agent occurs and deformation may occur or the surface uniformity of the foam may be deteriorated.

The raw material for producing the foam is injected into an extruder to be mixed and melted. The melting temperature is in the range of 180 to 220 ° C and the pressure in the extruder is 190 to 210 MPa. The melting temperature is a temperature at which all the raw materials to be mixed are uniformly melted. If the temperature is too low, the mixing and melting become uneven. If the temperature is too high, the raw materials may be lost or uniformly mixed. Also, if the pressure is too low, the mixing and melting become uneven, and if the pressure is too high, the life of the extruder is shortened and the process cost is increased.

Through this process, the foaming agent is injected into the molten raw material. Since the foaming agent is put into the heated raw material, the foaming agent is put in a heated state. In addition, the liquid foaming agent should be heated to a temperature higher than the vaporization temperature since it is necessary to vaporize. The heating temperature applicable to the liquid foaming agent used in the present invention is 180 to 220 ° C, and the gas blowing agent is also heated to the same temperature and then introduced into the extruder.

The foaming agent is mixed in the extruder and mixed with the raw material, and foaming takes place in this process. The amount of the blowing agent used is suitably from 1 to 15 parts by weight. If the amount of the blowing agent is too small, the foaming becomes insufficient, and if the amount of the blowing agent is too large, the surface uniformity or strain of the foam becomes poor.

The volume ratio of the gas blowing agent and the liquid foaming agent is preferably 1: 1 to 1: 0.5, and the volume ratio is based on the temperature at which the foaming agent is heated, but the heating temperature of the foaming agent should be the same in consideration of mixing. If the mixing amount of the liquid foaming agent is too small, there is no difference in the foaming efficiency between the foaming agent and the gas foaming agent alone. If the mixing amount of the liquid foaming agent is too large, the size and shape uniformity of the pore are decreased, Is essential for optimal foaming process.

In order to confirm the effect of the manufacturing method of expanded polystyrene foam according to the present invention, a prototype of foamed polystyrene foam was prepared and the characteristics thereof were compared.

Polystyrene powder, flame retardant, expanded graphite powder and nucleating agent were put into an extruder in the same ratio as in Table 1, heated, melted and mixed. Polystyrene powder, flame retardant, loess powder and nucleating agent were added to the extruder at the same ratios as in Table 2, heated, melted and mixed.

The foaming agent was added to the prepared molten raw materials as shown in Tables 1 and 2, foamed, and molded and cooled to prepare foams. BDDP was used as a flame retardant and zinc stearate was used as a nucleating agent. In addition, the expanded graphite powder was pulverized to 1300 mesh. In Table 1, the unit is parts by weight. The prepared foam was cut to a thickness of 50 mm and a length and a width of 1,000 mm, respectively.

Production Example 1 Production Example 2 Production Example 3 Production Example 4 Production Example 5 Production Example 6 Production Example 7 won
Ryo PS 60 55 65 60 60 60 60 Play PS 35 40 30 35 35 35 35 Flame retardant 5 5 5 5 5 5 5 Expanded graphite 3 3 3 3 3 - 10 Nucleating agent One One One One One One One foot
artillery
My CO ₂ 5 - - - - 5 5 CH ₄ - 5 - - - - - propane - - 6 - - - - cyclopentane - - - - - - - Ar - - - - 5 - - HCFC22 - - - 10 - - - DME - - - - - - - EtOH 5 - 4 - 5 5 5 PrOH - 5 - - - - - i-PrOH - - - - - - -

Production Example 8 Production Example 9 Production Example 10 Production Example 11 Production Example 12 Production Example 13 Production Example 14 won
Ryo PS 60 55 65 60 60 60 60 Play PS 35 40 30 35 35 35 35 Flame retardant 5 5 5 5 5 5 5 ocher 3 3 3 3 3 - 10 Nucleating agent One One One One One One One foot
artillery
My CO ₂ 5 - - - - 5 5 CH ₄ - 5 - - - - - propane - - 6 - - - - cyclopentane - - - - - - - Ar - - - - 5 - - HCFC22 - - - 10 - - - DME - - - - - - - EtOH 5 - 4 - 5 5 5 PrOH - 5 - - - - - i-PrOH - - - - - - -

The results of analyzing the physical properties of the foam thus prepared are shown in Tables 3 and 4. In Table 3 and Table 4, the thermal conductivity was measured according to KS L 9016 at an average temperature of 20 ± 5 ° C. The strain was determined by measuring the warpage (the difference between the center of the foam and the edge length) after the foam was irradiated with a 30 W ultraviolet lamp for 100 hours, As a percentage. Further, after cutting the cross section of the foam, an average diameter between the wall and the pores was measured with respect to 100 pores with an optical microscope. In addition, the closed cell ratio was measured according to ASTM D-2856 using an Ultra Peakometer (Quantachrome). It is known that the closed cell ratio is a fraction of the closed cells among the cells formed in the unit area, and the durability of the cells with a low closed cell ratio is decreased.

Production Example 1 Production Example 2 Production Example 3 Production Example 4 Production Example 5 Production Example 6 Production Example 7 Density (g / l) 30 30 30 30 30 30 30 Thermal conductivity (W / mK) 0.026 0.026 0.027 0.027 0.027 0.029 0.026 Strain (%) 2.3 2.2 2.4 3.4 4.6 3.8 4.2 Average pore diameter (占 퐉) 120 122 120 124 125 142 158 Pore diameter deviation (탆) 46 48 52 63 95 62 78 Percentage of closed cells (%) 82.2 81.3 82.4 78.4 77.5 78.2 77.2

Production Example 8 Production Example 9 Production Example 10 Production Example 11 Production Example 12 Production Example 13 Production Example 14 Density (g / l) 30 30 30 30 30 30 30 Thermal conductivity (W / mK) 0.027 0.027 0.026 0.027 0.026 0.028 0.026 Strain (%) 2.2 2.3 2.1 3.3 4.8 4.1 4.5 Average pore diameter (占 퐉) 125 127 124 125 128 148 160 Pore diameter deviation (탆) 44 45 50 68 98 70 74 Percentage of closed cells (%) 81.8 82.0 81.6 77.8 74.8 74.6 76.2

In Examples 1 to 3 in which the mixed foaming agent according to the present invention was applied, both the thermal conductivity and the strain were excellent, and the size variation of the pores was relatively small, and it was found that the durability was improved. This can be confirmed from the fact that the rate of independent air bubbles is high.

In Production Example 4 using Freon gas as a foaming agent, both the density and the thermal conductivity were favorable, but the strain was relatively increased and the closed cell ratio was also relatively low, indicating that the foam was less durable than the foam of the present invention. That is, in order to obtain the same durability as in the present invention, the thickness of the foam must be increased by about 20%.

In Production Example 5 using argon gas and ethanol as a foaming agent, the density and the thermal conductivity were all good, but it was understood that the pore size variation was relatively large and the adiabatic characteristics were lowered. In particular, it has been found that the durability of the foam of the present invention is lower than that of the foam of the present invention.

Production Example 6 shows that the expanded graphite is not contained but the strain is increased and the average pore diameter and the deviation are increased, so that the durability is degraded. This is because the effect of blocking the gas vent holes of the pores due to the addition of the expanded graphite does not occur, and it can be estimated from the result that the closed cell ratio is remarkably lowered.

In Production Example 7, even when a large amount of expanded graphite was contained, there was no difference in the thermal conductivity, and the average pore became larger and the pore size deviation became larger. In addition, it was found that the strain was increased due to such foaming characteristics.

Therefore, the foamed polystyrene foam according to the present invention can be produced by the production of foamed polystyrene foam, which is excellent in heat insulation properties and durability of the foamed product. Thus, even if the foamed foam is relatively thin, It was confirmed that the foam could be produced.

In addition, in Examples 8 to 10 in which the mixed foaming agent according to the present invention was applied, both the thermal conductivity and the strain were excellent, and the size variation of the pores was relatively small, and the durability was improved. This can be confirmed from the fact that the rate of independent air bubbles is high.

In Production Example 11 using Freon gas as a foaming agent, both the density and the thermal conductivity were favorable, but the strain was relatively increased and the closed cell ratio was also relatively low, indicating that the foam was less durable than the foam of the present invention. That is, in order to obtain the same durability as in the present invention, the thickness of the foam must be increased by about 20%.

In Production Example 12 using argon gas and ethanol as a foaming agent, both the density and the thermal conductivity were good, but it was found that the pore size variation was relatively large and the adiabatic characteristics were lowered. In particular, it has been found that the durability of the foam of the present invention is lower than that of the foam of the present invention.

Production Example 13 shows that the durability is deteriorated due to the increase of the strain and the increase of the average pore diameter and the deviation, which are not contained in the loess. This is considered to be because the effect of blocking the gas vent holes of the pores due to the addition of the loess does not occur, and this can be inferred from the result that the closed cell ratio is remarkably lowered.

Even in the case of containing a large amount of yellow clay in Production Example 14, there was no difference in the thermal conductivity, and it was found that the average pore became larger and the pore size deviation became larger. In addition, it was found that the strain was increased due to such foaming characteristics.

Therefore, the foamed polystyrene foam according to the present invention can be produced by the production of foamed polystyrene foam, which is excellent in heat insulation properties and durability of the foamed product. Thus, even if the foamed foam is relatively thin, It was confirmed that the foam could be produced.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken in conjunction with the present invention. Variations and changes are possible. Such variations and modifications are to be considered as falling within the scope of the invention and the appended claims.

Claims (5)

85 to 105 parts by weight of a polystyrene powder, 3 to 7 parts by weight of a flame retardant, 1 to 5 parts by weight of expanded graphite powder or loess powder, and 0.5 to 2 parts by weight of a nucleating agent into an extruder to produce a melt to be melted;
Introducing a foaming agent into the melt and extruding the melt;
A method for producing expanded polystyrene foam,
Wherein the foaming agent is a mixed foaming agent in which a liquid foaming agent and a gas foaming agent are mixed,
Wherein the mixed foaming agent is produced by heating and vaporizing the liquid foaming agent and simultaneously injecting the vaporized liquid foaming agent and the gas foaming agent into the extruder.
The method according to claim 1,
Wherein the polystyrene powder comprises 30 to 40 parts by weight of regenerated polystyrene powder.
delete The method according to claim 1,
Wherein the gas foaming agent is any one of carbon dioxide, methane, propane, and cyclopentane.
The method according to claim 1,
Wherein the liquid foaming agent is any one of ethanol, propanol, and isopropanol.

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