KR101780557B1

KR101780557B1 - Recycling PVC pipe for thermal fluid

Info

Publication number: KR101780557B1
Application number: KR1020150154509A
Authority: KR
Inventors: 계형산; 이용무; 이종태; 이일행
Original assignee: 목원대학교 산학협력단
Priority date: 2015-11-04
Filing date: 2015-11-04
Publication date: 2017-09-20
Also published as: KR20170052263A

Abstract

The present invention relates to a piping excellent in heat insulation by recycling waste plastic containing PVC.
The piping for cooling and heating using recycled PVC according to the present invention comprises an inner layer 110 and an outer layer 130 which are made by extruding a PVC resin; 2 to 30 parts by weight of azodicarbonamide (ADCA) as a foaming agent, 2 to 30 parts by weight of dicumyl peroxide (DCP) as an initiator and 2 to 30 parts by weight of zinc stearate as a heat stabilizer, based on 100 parts by weight of recycled PVC resin A foam layer 120 composed of 10 to 35 parts by weight of an acrylic copolymer, a maleic anhydride compound or a mixture thereof as a reactive agent and 2 to 10 parts by weight of a pigment is formed between the inner layer 110 and the outer layer 130 .

Description

{Recycling PVC pipe for thermal fluid}

The present invention relates to a piping excellent in heat insulation by recycling waste plastic containing PVC.

Plastics are very good and useful substances that replace wood, metal and other materials with industrialization and economic growth. They are widely used in life and industry as a result of industrialization and economic growth.

However, since the recycling rate is low, a large amount of waste plastic is being treated by landfill or incineration. Solid industrial wastes that can be incinerated and screened are generally incinerated and buried. However, in the case of waste plastics, due to some components and a large amount of additives, the incineration or landfill is damaging the treatment facilities or discharging dioxin and toxic gas, which is a macro cause of environmental pollution. In addition, waste plastics can not be recycled, resulting in economic losses. Therefore, considering the economic and environmental aspects, it is necessary to recycle waste plastics with efficient processing technology.

Particularly, PVC (polyvinyl chloride) is the biggest problem in recycling waste plastics.

PVC makes it difficult to recycle plastic in all areas, including RPF, incineration, emulsification, and material regeneration, as well as environmental issues. In terms of environment, toxic gas and dioxin are generated when incinerating organic matter containing mainly Cl (chlorine) as an organic chloride. In the case of PVC, about 57% by weight is composed of Cl, which is the largest dioxin emission source among plastic materials.

In addition, PVC is a thermoplastic plastic, but due to a large amount of additives, pyrolysis occurs severely or new compounds are produced. Therefore, in the case of waste plastics containing PVC, it is necessary to use not only PET (Polyethyleneterephthalate) (Polystyrene), HDPE (High Density Polyethylene), LDPE (Low Density Polyethylene) and the like, and even if it is regenerated, its value as a product or a raw material is lost.

PVC pipes with high content in PVC-containing wastes have a high PVC content and are easy to recycle. On the other hand, wastes with low PVC content such as wire coatings and laminate are high in content of other additives such as rubber and olefin Recycling is not properly performed and is being discarded.

Literature 1. Korea Patent Office Registration No. 10-0388448, "PVC foam and heat-insulating pipe using the same" Document 2: Korean Patent Registration No. 10-0436430, "Method of Manufacturing Recycled Pvc / EBS Mixed Scrap Sheet"

Disclosure of the Invention The present invention has been made in order to solve the above problems, and it is an object of the present invention to provide a method for recycling waste materials containing PVC by reacting with other additives of wastes having a low PVC content, It is an object of the present invention to provide a hot / cold water pipe for cooling and heating which is excellent in heat insulation and an intake / exhaust pipe.

To achieve the above object, the present invention provides a cooling and heating pipe using recycled PVC, comprising an inner layer (110) and an outer layer (130) by extruding a PVC resin; 2 to 30 parts by weight of azodicarbonamide (ADCA) as a foaming agent, 2 to 30 parts by weight of dicumyl peroxide (DCP) as an initiator and 2 to 30 parts by weight of zinc stearate as a heat stabilizer, based on 100 parts by weight of recycled PVC resin A foam layer 120 composed of 10 to 35 parts by weight of an acrylic copolymer, a maleic anhydride compound or a mixture thereof as a reactive agent and 2 to 10 parts by weight of a pigment is formed between the inner layer 110 and the outer layer 130 .

At this time, the foam layer 120 is formed by mixing talc, calcium carbonate, or a mixture thereof in an amount of 5 to 30 parts by weight as a small strengthening agent.

The foamed layer 120 may further include 20 to 35 parts by weight of an EVA resin.

The azodicarbonamide (ADCA) is mixed in an amount of 3 to 8 parts by weight.

The zinc stearate is mixed with 3 to 7 parts by weight of zinc stearate.

The outer layer 130 may further comprise 5 to 9 parts by weight of a butyl-acrylic copolymer and 2 to 10 parts by weight of an alkyl acrylate copolymer based on 100 parts by weight of the PVC resin.

The pipe for cold and heating using the recycled PVC according to the present invention having the above-described structure is a pipe for reforming and foaming a waste material having a low PVC content such as a long plate to form a pipe having a foam layer, It is excellent in heat insulating property and strength by foaming into cells of size of 100 μm or less.

1 is a perspective view showing a pipe for cooling and heating using recycled PVC according to the present invention.
2 is a sectional view taken along the line AA in Fig.
3 is an enlarged photograph of a foam cell of a foam layer

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to preferred embodiments and accompanying drawings.

It is to be understood that when an element is referred to as being "comprising" another element in the description of the invention or in the claims, it is not to be construed as being limited to only that element, And the like.

1 and 2, the piping for cold and heating using the recycled PVC according to the present invention is a pipe having a triple-sectioned cross-section, in which a foam layer 120 is provided between the inner layer 110 and the outer layer 130 .

The inner layer 110 and the outer layer 130 are formed by molding a PVC resin having a molecular weight of 1,000 or more and recycled waste resources having a high PVC content such as waste PVC pipe to a high strength so that the pipe is not damaged by external impact .

A foam layer 120 is formed between the inner layer 110 and the outer layer 130. The foam layer 120 is formed by modifying and foaming waste materials such as wire coverings and long sheets having a low PVC content, Thereby increasing the heat insulation of the pipe.

Since the inner layer 110 and the outer layer 130 are formed by a known technique for recycling waste resources having a high PVC content, a detailed description of the inner layer 110 and the outer layer 130 will be omitted.

5 to 9 parts by weight of a butyl-acrylic copolymer as an impact modifier and 2 to 10 parts by weight of an alkyl acrylate copolymer are mixed with 100 parts by weight of PVC which recycles waste materials having a high PVC content such as pulverized perfume, The strength and miscibility of the resin constituting the outer layer 130 are increased.

The foaming layer 120 of the piping for cooling and heating using the recycled PVC according to the present invention is prepared by mixing 2 to 30 parts by weight, preferably 3 to 8 parts by weight, of azodicarbonamide (ADCA) as a foaming agent with respect to 100 parts by weight of recycled PVC resin And 2 to 30 parts by weight of dicumyl peroxide (DCP) as an initiator is mixed. 2 to 30 parts by weight, preferably 3 to 7 parts by weight of zinc stearate as a heat stabilizer is mixed, and inorganic particle talc (Talc ), Calcium carbonate (CaCO ₃ ), or a mixture thereof, and 20 to 35 parts by weight of an EVA resin are mixed, 10 to 35 parts by weight of an acrylic copolymer, a maleic anhydride compound or a mixture thereof, And 2 to 10 parts by weight of a pigment are mixed.

Plastic wastes such as waste wire cladding and laminates include PVC resins, olefin compounds such as PE, PP, EPDM, EVA and PU, as well as polyester fibers and glass fibers as strength reinforcements.

A phthalate copolymer, a maleic copolymer or an epoxy copolymer, which is a reactive material, is added to waste materials containing a low amount of PVC as described above to accelerate the reaction to the PVC structure. Such phthalate copolymer, A copolymer or an epoxy-based copolymer is reacted with a rubber or an olefin contained in waste resources to improve strength and miscibility and is used as a base resin for molding the foam layer 120.

The foamed processing aid is added to the modified PVC resin so that the recycled PVC resin is foamed during the extrusion process. The foaming processing aid is mixed with the modified PVC resin, and in the process of extruding in the extruder, a foam is formed in which numerous cells of a rubber-like structure, such as olefin or elastomer, are formed.

At this time, in order to adjust the cell size of the foam, the cell size of the foam can be adjusted by adjusting the temperature and pressure distribution in the extruder. The PVC resin is foamed at a temperature of about 180 ° C. By mixing the A foam agent (azodicarbonamide, ADCA), the foaming temperature of the PVC resin is lowered to form the foaming cell into a smaller size and increase the strength of the foam .

The recycled PVC resin promotes the thermal reaction of the dechlorination product generated by the dechlorination of PVC by heat during extrusion processing with the olefinic and rubbery resins contained in the recycled PVC.

The PVC resin recycled by the known PVC recycling technology is extruded through a T-die capable of manufacturing a double-walled pipe, and the recycled PVC resin modified between the inner layer 110 and the outer layer 120 is foamed in a T-die mold The temperature and the pressure of the resin are adjusted and foam extrusion is performed to form a foam layer 120 in which a number of cells are formed while adjusting the cell size of the foam layer 120 to produce a pipe for cooling and heating.

The foam layer 120 as described above is constituted as follows.

The PVC resin is foamed during the extrusion process by adding an acrylate copolymer, a reaction initiator, a processing aid, and a foaming initiator to the olefin resin and the rubber-like resin contained in the recycled PVC, and a number of cells are formed and cured, (120) is formed.

The foaming agent is an azo-type in which nitrogen gas is generated by a thermal decomposition reaction due to heat, and a sulfur-type foam that generates sulfur gas requires a radical-generating agent by adding a foaming agent to radicals at a temperature above a certain temperature other than heat , The composition does not swell in the absence of such a radical-generating agent.

In the present invention, when a radical initiator is not used, a foaming agent (azodicarbonamide, ADCA) does not promote a chemical reaction and foams at a temperature above the foaming temperature of the foaming agent, so that a good foaming product can be obtained.

The azodicarbonamide (ADCA) generates a large amount of decomposition gas and decomposition heat upon heating. Therefore, when azodicarbonamide which does not generate any radicals is used as a blowing agent, it is foamed at a temperature higher than the foaming temperature by a large amount of heat of decomposition generated in the azodicarbonamide (ADCA), so that a good foamed layer 120 is produced It is possible.

As described above, azodicarbonamide has a large amount of heat of decomposition. The use of azodicarbonamide alone at temperatures sufficient to decompose and foam the azodicarbonamide in the general known process (e.g., at a pressurization temperature of 175 占 폚) leads to decomposition of the PVC due to its high thermal decomposition.

In order to gel the PVC, the gelation temperature of the PVC can be lowered by adding a material having a lower melting temperature than PVC. As described above, by adding a substance having a lower melting temperature than PVC, it is possible to suppress the decomposition reaction of PVC and maintain the physical strength and the like of the produced pipe.

In an embodiment of the present invention, the EVA is added as a material having a low melting temperature in order to lower the melting temperature and to activate the plasticizing function, thereby mixing the foaming agent with a material having a low melting temperature, It is possible to adjust the foaming temperature of the foaming agent after it is mixed with the recycled PVC powder and then injected into the extruder, and it is possible to secure a large amount of closed cells closed by the rising wall at the time of foaming,

The foaming agent is foamed at a low temperature, the foaming gas cell is lost, and the foaming cell is difficult to be contained in the material, so that the foaming gas is lost to the outside of the material, so that a large amount of the foaming agent enters.

The present invention makes it possible to press mold the composition at a low temperature of 150-170 DEG C in the cylinder temperature of the extruder to prevent thermal decomposition of the PVC.

When dicumyl peroxide (DCP), an initiator, is added, radicals are generated from 60 to 80 ° C. to generate foaming gas at a low temperature. However, since many foaming cells are formed as an open type, It is preferable to set the temperature at which the foaming gas is easily stored and add the initiator in an appropriate amount to adjust the foaming temperature. When the foaming agent is mixed with the heat stabilizer or when the foaming agent is mixed with the processing aid, The stability of the cell can be brought about, and the temperature of the decomposition reaction of the blowing agent is adjusted by adjusting the temperature of the extruder.

In the present invention, it is preferable to mix azocarbonamide (ADCA) as a blowing agent with a zinc-containing compound as a heat stabilizer. This is because the heat of fusion of PVC generated with the gas from the foaming agent during pyrolysis can be greatly reduced.

The zinc compound is decomposed during the foaming process of the rigid PVC in which azodicarbonamide is used to generate radicals at the time of gas evolution, so that some residue of the decomposed azodicarbonamide which promotes deterioration of PVC is suppressed by the zinc compound.

As the zinc-containing pressure-reducing material, there are inorganic and organic compounds containing zinc.

For example, zinc bromate, basic zinc carbonate, zinc sulfide, zinc phosphate, zinc stearate, and zinc octanoate. These zinc-containing compounds may be used alone or in combination.

The amount of the zinc-containing compound used is generally from 5 to 20 parts by weight per 100 parts by weight of PVC. The amount of the zinc-containing inorganic compound used is 5 to 20 parts by weight, preferably 7 to 15 parts by weight based on 100 parts by weight of PVC, and the zinc-containing organic compound used is added to accelerate the gelation of PVC.

In an embodiment of the present invention, zinc-stearate is used as the zinc-containing substance.

When the content of zinc-stearate is less than the above range, the olefin resin melts in the recycled PVC resin during melting, thereby reducing the heat generated in the PVC decomposition reaction, so that the use of the zinc stearate content has little effect. Use in excess of the above range may result in an increase in production cost, and a phenomenon of inhibiting foaming of the foaming agent due to a decrease in temperature upon melting may occur, and it may be impossible to form the foam layer 120.

The amount of the decomposing foaming agent used is determined by the desired expansion ratio, the type of foaming agent, the inorganic fibers, the inorganic granular particles, the solvent and the like. 2 to 30 parts by weight, preferably 3 to 8 parts by weight, of a decomposing foaming agent is preferably added to 100 parts by weight of PVC. When the decomposition type foaming agent is used in an amount less than 2 parts by weight, the resulting foamed product is insufficient to obtain a desirable expansion ratio. When the amount is more than 30 parts by weight, an excessive amount of gas is decomposed at the time of expansion so that decomposition pressure in the extruder is high. The effect of heat insulation is deteriorated.

In order to prevent the decomposition of the recycled PVC resin upon contact with the cylinder wall of a high-temperature extruder, it is possible to delay the temperature and the time at which the foamed cell is formed by mixing the foaming agent with an olefin resin having a low melting temperature such as a core cell .

Alternatively, the foaming agent may be used by mixing with a foaming promoter such as polystyrene containing pentane, and may be used by mixing with a foaming promoter such as a foaming promoter such as polyurethane.

In the present invention, the heat stabilizer is used for the purpose of preventing deterioration of PVC.

Thermal stabilizers include dibasic Pb-stearate, dibasic Pb-phosphate, tribasic Pb-sulfite, Zn-stearate, Ca-stearate and the like.

The amount of the heat stabilizer used is 2 to 20 parts by weight, preferably 3 to 7 parts by weight based on 100 parts by weight of PVC. If the amount exceeds 20 parts by weight, the stabilizing effect is not sufficiently improved as compared with the amount of the heat stabilizer to be mixed, and softening may affect the basic physical properties of PVC.

The composition containing the blowing agent is difficult to exhibit the performance of the blowing agent because the foaming agent is prematurely foamed because the temperature of the cylinder wall surface in the extruder is high when the blowing agent is mixed with the PVC raw material by the conventional method. The PVC raw material may not be melted and a non-uniform product may be generated.

In order to adjust the foaming conditions and the expansion ratio of the foaming agent, it is necessary to mix the foaming agent with other materials, such as the effect of the coating, so that the foaming conditions of the foaming agent by external heat can be adjusted and then mixed with the PVC raw material. The size of the cell and the like can be easily adjusted.

Since the olefin resin of the foamed composition, the resin containing rubber particles, the rubber and the like have a high shearing force, the foaming agent is mixed into the mixer at the time of mixing and sufficiently mixed until the respective materials are uniformly dispersed.

Here, the resin is uniformly mixed only by applying a certain temperature at a high shear force. The high shear force of the resin must be applied at a certain temperature to bring about uniform mixing. Until the foam composition is homogeneously dispersed.

If necessary, the composition is heated, heating is continued at a temperature lower than the decomposition temperature of the foaming agent, and mixing is continued. When mixing at a high temperature, the foaming agent is decomposed and mixed with the raw material, so that the performance of the foaming agent can not be exhibited at the time of processing. When each material of the composition generates a chain reaction such as a radical reaction, the decomposition type foaming agent accelerates the decomposition of the foaming agent by the attack of the radical and can decompose even at a low temperature. The temperature control of each raw material should be adjusted appropriately when mixing the composition.

The foaming composition and the PVC raw material are mixed again at a temperature lower than the decomposition point of the foaming agent, the mixed raw material is put into a hopper which is a raw material input port of an extruder equipped with a foam core tube to be manufactured and the temperature of the cylinder in the extruder is adjusted The foaming structure of the foaming jumbo tube should be stabilized by extrusion.

Foam center tube Expands and shrinks the foaming gas according to the heating temperature of the mold. If the temperature of the mold is high, the foaming gas expands and the viscosity of the molten resin is lowered to break the diaphragm of the cell and the cell, thereby increasing the size of the cell. Since the open cell is larger than the close cell, In order to prevent cell wall collapse, cell wall collapse and cell wall collapse are prevented by reinforcing strength by crystallization or crosslinking reaction of cell outer wall.

The temperature should be maintained so that the proper viscosity of the PVC resin can be maintained so that the foaming gas does not leak due to the collapse of the cell membrane when the foaming gas expands.

The temperature of the resin rises up to a suitable temperature at which the foaming agent is foamed, and then the foaming agent is decomposed to generate foaming gas to form a close cell by the viscosity of the resin. As the foaming cells are dispersed in the cylinder, (160 ~ 200 ℃) should be maintained in order to maintain the proper temperature.

When the temperature in the mold is maintained, expansion of the foaming gas is continued and the size of the cell is enlarged. Therefore, when the temperature of the mold is lowered to an appropriate temperature, the cell shrinks and pressure is maintained in the mold.

The foam layer 120 is rapidly cooled while being discharged from the metal mold to maintain the size of the cell.

The expansion ratio of the rigid foam is preferably 30 times or more, preferably 60 times or more, and more preferably 50 times or more when it is used as a thermally conductive material satisfying the requirements of the rigid foam.

Typical close cells having expansion ratios of 100 times or more are difficult to manufacture, and open cells can show deterioration such as mechanical strength. Therefore, the expansion ratio of the rigid foam is preferably 100 times or less.

Example

- 100 parts by weight of resin (PVC) recycled from waste materials having a PVC resin content of 30%

- Azodicarbonamide (ADCA) as a foaming agent: 5 parts by weight

- Dicumylperoxide (DCP) as initiator: 13 parts by weight

- 2 parts by weight of zinc stearate as heat stabilizer

- mixture of talc and calcium carbonate as minor coagulant: 5 parts by weight

EVA resin: 21 parts by weight

- a mixture of an acrylic copolymer and a maleic anhydride compound as reactants: 13 wt%

- Pigment: 2 parts by weight

The foam tube (thickness 5 mm) was extruded from the extruder at the mixing ratio as described above.

Thermal Conductivity Test (Insulation Effect)

To maintain the temperature in the tube, 50 ml of iso propyl alcohol is mixed with distilled water (50 ml), and the mixture solution is kept at a constant temperature for a predetermined time after adding dry ice to the mixed solution. The temperature of the gel was kept at -29.9 ℃.

The temperature of the tube surface over time was measured by placing the liquid in the tube and observing the surface temperature and surface condition.

time
(min) Tube surface temperature (℃) General Playground Regenerated bridge tube Reclaimed plastic pipe 0 22 22 22 10 13 15.4 16.7 30 5.7 9.1 12.7 60 1.9 5.9 9.9 90 -2.7 3.6 7.5 120 -5.8 1.1 5.4 180 -6.7 0 4.3 300 -7.2 -0.9 3.8 600 -8.2 -2.3 3.2

- General regeneration tube: A PVC tube extruded to a thickness of 5 mm of PVC resin reproduced by a known technique

- Regeneration tube: A PVC tube obtained by extruding the foaming agent from the composition according to the present invention and extruding it

- Recycled steel pipe: A PVC pipe extruded and foamed with the composition according to the present invention

As shown in Table 1 and the graph, the PVC general pipe is composed of a uniform material of a single material, and when the low temperature liquid is injected, the heat conduction is maintained at a constant speed and the temperature of the tube surface is lowered. It can be seen that the dew point is formed on the tube surface

At this time, the temperature of the gelled liquid inside the tube was -29.9 ℃. After 30 minutes, it was seen that the surface was found to have sexual intercourse and the surface temperature was below -5 ℃.

In the case of a triple pipe containing a rubber-like material and an olefin material in the pipe, the pipe is manufactured by crosslinking about 2 to 3% in order to adjust the viscosity of the material and to improve the physical strength. The rate of degradation of the catalyst is low.

This phenomenon is attributed to the fact that the thermal degradation rate is low due to the low thermal conductivity of rubber and olefin materials compared to PVC. The dew point of the material is about 60 minutes. As a result of measuring the thermal conductivity of the tube with the foamed core tube, the rate of decrease was maintained at the initial stage, and the rate of temperature decrease after a certain period of time decreased. There was almost no change in the temperature of the tube surface after one hour, . It is considered that the foam cell structure is maintained in the center pipe in the pipe, and thus the pipe has a thermal insulation effect.

Particle Size of Foam: The surface of the foam was plated with gold on the fractured surface with a scanning electron microscope so that the electromagnetic wave travels well. The surface was observed and the results were as follows.

Extrusion amount in extrusion of foam (g / min): Nitrogen of molded product processed in an extruder for 1 minute during expansion molding

Foam cell size (mm) at the time of foaming extrusion: Average value of 10 cell sizes measured using an electron microscope.

division talk(%) Extrusion amount (g / min) Foaming Specific Gravity (g / cc) Foam cell size (㎛) Example 1 89 158.3 0.399 98 Example 2 114 188.7 0.466 87

As shown in Table 2, in the case of Example 1, when the torque pressure of the extruder is low, the foam cell has a large size due to a low viscosity, and when the torque value of the extruder is high, the viscosity of the resin increases, Is relatively small in size.

In order to form the core tube and the tube, the temperature of the exit of the mold must be lowered to maintain the stable foaming cell and lower the viscosity of the surface layer, so that the solidification rate increases and the pressure of the foaming gas can be maintained, .

As a means for adjusting the size of the foaming cell, a decomposition reaction is initiated while the foaming agent is brought into contact with the wall surface of the cylinder of the heated extruder, and it is difficult to maintain the foam in the resin. To solve this problem, In order to delay the time, the blowing agent is kneaded in an olefin resin or a rubber-like resin which is melted at a temperature considerably lower than the foaming temperature of the foaming agent so as to adjust the temperature rising rate of the foaming agent in the resin to further increase the dispersibility of the foaming agent, The foaming temperature of the foaming gas was delayed to maintain a constant foaming cell in the extruder.

In order to adjust the foaming rate of the foaming agent, a radical generating material is added to adjust the foaming rate by the radical to increase the tie-up relationship with the resin and to add a small amount of dicumylperoxide to delay the foaming rate of the foaming agent, And the temperature of the extruder is adjusted to secure the stability of the foamed cell.

It is difficult to maintain the shape and surface characteristics of the final mold at a temperature of 170 ° C or lower of the final mold. It is easy to form the foam and facilitates the processing during the foaming extrusion process, And the proportion of products is low.

The pipe for cooling and heating according to the present invention having the above-described structure is constructed by modifying and foaming waste resources having a low PVC content such as a long plate, thereby forming a pipe having a foam layer at the center. As shown in FIG. 3, Foamed in cells of 100 탆 or less in size.

The technical idea of the present invention has been described above with reference to the embodiments.

It will be apparent to those skilled in the art that various changes and modifications may be made to the embodiments described above from the description of the present invention.

Also, although not explicitly shown or described, a person having ordinary skill in the art can make various modifications including the technical idea of the present invention from the description of the present invention. Which is still within the scope of the present invention.

The above-described embodiments described with reference to the accompanying drawings are for the purpose of illustrating the present invention, and the scope of the present invention is not limited to these embodiments.

110: inner layer
120: foam layer
130: outer layer

Claims

An inner layer 110 of PVC resin extruded;
An outer layer (130) composed of 100 parts by weight of a PVC resin, 5 to 9 parts by weight of a butyl-acrylic copolymer and 2 to 10 parts by weight of an alkyl acrylate copolymer with respect to 100 parts by weight of the PVC resin;
2 to 30 parts by weight of azodicarbonamide (ADCA) as a foaming agent, 2 to 30 parts by weight of dicumyl peroxide (DCP) as an initiator and 2 to 30 parts by weight of zinc stearate as a heat stabilizer, based on 100 parts by weight of recycled PVC resin A foam layer 120 composed of 10 to 35 parts by weight of an acrylic copolymer, a maleic anhydride compound or a mixture thereof as a reactive agent and 2 to 10 parts by weight of a pigment is formed between the inner layer 110 and the outer layer 130 Features of recycled PVC pipes for heating and cooling.

The method according to claim 1,
The foam layer (120)
Wherein the mixture is further mixed with 5 to 30 parts by weight of talc, calcium carbonate or a mixture thereof.

The method according to claim 1,
The foam layer (120)
And 20 to 35 parts by weight of an EVA resin are further mixed together.

The method according to claim 1,
Wherein the azodicarbonamide (ADCA) is mixed with 3 to 8 parts by weight of the azodicarbonamide (ADCA).

The method according to claim 1,
Wherein the zinc stearate is mixed with 3 to 7 parts by weight of the zinc stearate.

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