Recycled plastic plate material and manufacturing method thereof

Abstract

To provide a recycled plastic plate material having excellent durability and an environmentally friendly manufacturing method thereof for recycling waste plastic without a secondary environmental pollution.SOLUTION: The present invention provides: a manufacturing method of recycled plastic plate material including a) a step for preparing a formwork with a gasket installed between a pair of mold plates, b) a step for injecting a plate material composition to the formwork, c) a primary polymerization reaction step for heating the formwork with the plate material composition having been injected therein in a water tank filled with a heating medium having a specific gravity higher than that of water, d) a secondary polymerization reaction step for heating the formwork at a temperature higher than that of the primary polymerization reaction, and e) a formwork removing step for cooling the formwork after the secondary polymerization reaction step and removing the formwork, the plate material composition including a binder composition and a waste plastic pulverization product obtained by classification according to color tones and pulverization; and a recycled plastic plate material manufactured by this method.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a recycled plastic sheet using waste plastic and a method for manufacturing the same.

Background Art

[0002] Environment issues are becoming increasingly felt globally, and the waste problem of petrochemical products has emerged in line with the trend towards carbon neutrality. Therefore, regarding waste, forming a circular economy of petrochemical products through reduction and recycling has become an important issue to be solved.

[0003] However, in the current plastic treatment methods, when most are incinerated and some are recycled, the physical properties deteriorate and it is difficult to manufacture products with the desired hue, so the development of recycled products is limited.

[0004] Also, since a large amount of heat and electrical energy are used by melting during recycling, an environmentally friendly recycling method and manufacturing method are proposed that minimize energy and do not cause environmental pollution and secondary pollution during recycling. On the other hand, as a similar prior art document regarding plastic recycling, Korean Patent No. 10-1379284 is presented.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present invention is to provide a recycled plastic sheet excellent in durability and an environmentally friendly manufacturing method thereof that recycle waste plastic without secondary environmental pollution. However, the above object is exemplary, and the technical idea of the present invention is not limited thereto.

Means for Solving the Problems

[0007] One aspect of the present invention for achieving the above object is a) preparing a mold in which a gasket is installed between a pair of mold plates; b) injecting a plate material composition into the mold; c) a primary polymerization reaction step of heating the mold injected with the plate material composition by placing it in a water tank filled with a heating medium having a specific gravity higher than that of water; d) a secondary polymerization reaction step of heating at a temperature higher than that of the primary polymerization reaction; e) a demolding step of cooling after the secondary polymerization reaction step and removing the mold, and includes The plate material composition includes a binder composition and pulverized waste plastic classified by hue and pulverized, and provides a method for manufacturing a recycled plastic plate. In one aspect of the present invention, the specific gravity of the heating medium can be 1.1 to 2.

[0008] In one aspect of the present invention, the heating medium includes water and a water-soluble inorganic salt, and the water-soluble inorganic salt is one or more selected from the group consisting of sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride, barium chloride, sodium nitrate, potassium nitrate, lithium nitrate, calcium nitrate, magnesium nitrate, barium nitrate, sodium sulfate, potassium sulfate, lithium sulfate, magnesium sulfate, sodium carbonate, potassium carbonate, and lithium carbonate. In one aspect of the present invention, the plate material composition can include 5 to 50 parts by weight of a binder composition and 95 to 50 parts by weight of pulverized waste plastic.

[0009] In one aspect of the present invention, the binder composition may include one or more selected from the group consisting of an acrylic monomer, an acrylic resin, an unsaturated polyester resin, an epoxy resin, and a polystyrene resin.

[0010] In one aspect of the present invention, the waste plastic pulverized material may include one or more materials selected from the group consisting of polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polycarbonate (PC), and acrylonitrile-butadiene-styrene (ABS). In one aspect of the present invention, the heating temperatures of the primary polymerization reaction and the secondary polymerization reaction may be independently less than 50 to 130 °C. In one aspect of the present invention, the heating times of the primary polymerization reaction and the secondary polymerization reaction may be 30 minutes to 2 hours. In one aspect of the present invention, the size of the waste plastic pulverized material may be 0.1 to 30 mm. Another aspect of the present invention provides a recycled plastic sheet produced by the method for producing a recycled plastic sheet described above.

Advantages of the Invention

[0011] The method for producing a recycled plastic sheet according to the present invention does not produce a sheet by melt extrusion or injection, but injects a sheet composition between a pair of mold plates arranged at regular intervals, and cures and dries it by vertical and horizontal molding methods to produce a recycled plastic sheet. By doing so, the surface and thickness of the product are constant, and the quality of the product can be improved. The produced recycled plastic sheet can ensure excellent physical properties.

[0012] Also, when processing conventional polymethyl methacrylate (PMMA) resin, processing is performed at a temperature of 230 °C or higher. However, by polymerizing PMMA using methyl methacrylate (MMA), processing can be performed at a temperature of less than 130 °C, and a carbon reduction effect can be obtained by energy saving and simplification of the recycled plastic circulation process.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0014] Hereinafter, the recycled plastic sheet and its manufacturing method according to the present invention will be described in detail. The drawings introduced below are provided as examples so that the idea of the present invention can be sufficiently conveyed to those skilled in the art. Therefore, the present invention is not limited to the drawings presented below, and may be embodied in other forms. The drawings presented below may be exaggerated to clarify the idea of the present invention. At this time, in the technical terms and scientific terms used, unless otherwise defined, they have the meanings commonly understood by those having ordinary knowledge in the technical field to which the present invention pertains, and descriptions of well-known functions and configurations that may unnecessarily obscure the gist of the present invention in the following description and the accompanying drawings are omitted.

[0015] The conventional method of utilizing waste plastics is a method in which waste plastics are pulverized, melt-extruded into pellets, and then injected for use. Such a method has the drawback that a large amount of electrical energy must be used in the process, resulting in a large energy loss.

[0016] The present invention is devised to solve the above-mentioned drawbacks. The method for manufacturing a recycled plastic sheet according to the present invention comprises: a) preparing a mold frame in which a gasket is installed between a pair of mold plates; b) injecting a sheet composition into the mold frame; c) a primary polymerization reaction step of heating the mold frame injected with the sheet composition by placing it in a water tank filled with a heating medium having a specific gravity higher than that of water; d) a secondary polymerization reaction step of heating at a temperature higher than that of the primary polymerization reaction; and e) a demolding step of cooling and removing the mold frame after the secondary polymerization reaction step. The sheet composition may include a binder composition and pulverized waste plastics classified by hue and pulverized.

[0017] Thus, the method for manufacturing a recycled plastic sheet according to the present invention does not manufacture the sheet by melt extrusion or injection, but injects the sheet composition between a pair of mold plates arranged at regular intervals, and cures and dries it by vertical and horizontal molding methods to manufacture a recycled plastic sheet, so that the surface and thickness of the product are constant and the quality of the product can be improved, and the manufactured recycled plastic sheet can ensure excellent physical properties.

[0018] Hereinafter, the method for manufacturing a recycled plastic sheet according to an example of the present invention will be described in more detail. First, step a) of preparing a mold frame in which a gasket is installed between a pair of mold plates can be performed. As a preferred example, the mold plates can be made of glass plates or metal plates and consist of a pair having the same shape and size.

[0019] The gasket serves to seal the liquid sheet composition injected between the mold plates and is installed in consideration of the shape and thickness of the sheet to be manufactured. Then, a number of clamps can be attached at regular intervals along the outer peripheral tip of the mold plates to fix the mold plates. The mold plate frame can be installed vertically or horizontally. An antifoaming agent capable of removing air bubbles in the sheet or a separate crimping machine can be used. Next, step b) of injecting the plate material composition into the formwork can be performed.

[0020] As described above, the plate material composition can include a binder composition and waste plastic pulverized materials classified and pulverized by hue. Specifically, it can include 5 to 50 parts by weight of the binder composition and 95 to 50 parts by weight of the waste plastic pulverized materials. Within such a range, a recycled plastic plate excellent in mechanical strength can be manufactured.

[0021] In an example of the present invention, the binder composition is for making the waste plastic pulverized materials be firmly bonded, and the binder composition can include one or more selected from the group consisting of an acrylic monomer, an acrylic resin, an unsaturated polyester resin, an epoxy resin, and a polystyrene resin.

[0022] Preferably, the binder composition can include an acrylic monomer. When processing a conventional polymethyl methacrylate (PMMA) resin, processing is performed at a temperature of 230°C or higher. However, by polymerizing with PMMA using a monomer of methyl methacrylate (MMA), processing can be performed at a temperature of less than 130°C, and thus a carbon reduction effect can be obtained by energy saving and simplification of the recycled plastic circulation process.

[0023] As a specific example, the acrylic monomer may be one or more selected from the group consisting of alkyl (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and n-octyl (meth) acrylate; hydroxyalkyl (meth) acrylates such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, and hydroxyhexyl (meth) acrylate; aminoalkyl (meth) acrylates such as aminoethyl (meth) acrylate, N,N-dimethylaminoethyl (meth) acrylate, and t-butylaminoethyl (meth) acrylate; alkoxyalkyl (meth) acrylates such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate; carboxy group-containing monomers such as (meth) acrylic acid and carboxyethyl (meth) acrylate; epoxy-containing monomers such as glycidyl (meth) acrylate; glycol-based monomers such as ethylene glycol (meth) acrylate, propylene glycol (meth) acrylate, methoxyethylene glycol (meth) acrylate, and methoxypropylene glycol (meth) acrylate; and the like.

[0024] In addition, the binder composition may further contain one or more of a silane coupling agent, an antifoaming agent, a wetting dispersant, a chain transfer agent, an initiator, and an inorganic filler, etc., as necessary. Of course, the contents of these can be added in an amount of 0.01 to 5 parts by weight based on 10 parts by weight of the binder composition.

[0025] In an example of the present invention, the waste plastic crushed material is obtained by crushing waste plastics classified by hue into an appropriate size. The method for manufacturing a recycled plastic sheet according to an example of the present invention does not perform steps such as melt extrusion or injection, so that it is not necessary to perform a material classification step for using the same material, and only the steps of classifying and crushing waste plastics according to the hue of the target sheet can be performed. FIG. 1 shows a recycled plastic sheet manufactured from blue waste plastics, which can be classified into various hue systems and, of course, two or more hues can also be mixed. The material of the waste plastic is not particularly limited, and may be, for example, one or more selected from the group consisting of polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polycarbonate (PC), and acrylonitrile-butadiene-styrene (ABS), but is not limited thereto.

[0026] The waste plastics classified by hue can be crushed using a crusher, and the size of the crushed waste plastic crushed material is 0.1 to 30 mm, more preferably 0.5 to 25 mm, and even more preferably 1 to 10 mm. Within such a range, a recycled plastic sheet excellent in mechanical properties can be manufactured.

[0027] On the other hand, when injecting the sheet composition, the waste plastic and the binder composition can be mixed and injected, or the waste plastic crushed material can be injected first and then the binder composition can be injected. Next, c) A primary polymerization reaction step can be performed in which the mold filled with the sheet composition is placed in a water tank filled with a heating medium having a specific gravity higher than that of water and heated.

[0028] In the primary polymerization reaction step, the mold filled with the sheet composition is placed vertically or horizontally in a water tank filled with a heating medium having a specific gravity higher than that of water and polymerized at an appropriate temperature. When polymerizing and processing by placing it vertically or horizontally in the water tank, the precipitation and deviation phenomena of the waste plastic due to the specific gravity difference are prevented, so that the thickness of the product can be adjusted to be constant.

[0029] Specifically, the specific gravity of the heating medium is 1.1 to 2, and more preferably can be 1.3 to 1.8. More specifically, the heating medium can contain water and water-soluble inorganic salts, and the water-soluble inorganic salts can be one or more selected from the group consisting of sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride, barium chloride, sodium nitrate, potassium nitrate, lithium nitrate, calcium nitrate, magnesium nitrate, barium nitrate, sodium sulfate, potassium sulfate, lithium sulfate, magnesium sulfate, sodium carbonate, potassium carbonate, lithium carbonate, and lithium.

[0030] Also, using a water tank is for evenly applying temperature to the mold. In the primary polymerization reaction step, the temperature and time can be adjusted according to the size and thickness. Specifically, a primary polymerization reaction can be carried out at 50 to 80 °C for 10 minutes to 1 hour. Next, d) A secondary polymerization reaction step of heating at a temperature higher than the primary polymerization reaction can be carried out.

[0031] By secondary heating the mold injected with the plate composition after the primary polymerization reaction step at a higher temperature, the monomers in the binder composition can be maximally reacted to further improve the mechanical properties of the recycled plastic plate. Specifically, the secondary polymerization reaction can be carried out at 80 to 130 °C for 1 to 2 hours. Finally, e) A demolding step of cooling after the secondary polymerization reaction step and removing the mold can be carried out.

[0032] After going through the secondary polymerization reaction step, through a demolding step of cooling to room temperature and removing the mold plate and gasket, a plate with well-dispersed waste plastic crushed products and a constant product thickness distribution can be completed.

Example

[0033] Hereinafter, the recycled plastic sheet material according to the present invention and its manufacturing method will be described in more detail by way of examples. However, the following examples are merely one reference for explaining the present invention in detail, and the present invention is not limited thereto and can be realized in various forms. Also, unless otherwise defined, all technical terms and scientific terms have the same meaning as generally understood by those skilled in the art to which the present invention pertains. The terms used in this specification are for effectively explaining specific examples and are not intended to limit the present invention. Also, the unit of the additive not specifically described in the specification may be % by weight.

[0034] [Example 1] 10 parts by weight of methyl methacrylate monomer (MMA), 3 parts by weight of ethylene glycol dimethacrylate (EGDMA), 1.5 parts by weight of methacryloxypropyltrimethoxysilane (A-174), 0.2 parts by weight of wetting dispersant (BYK-W980), 0.1 parts by weight of defoaming agent (DC-1400), 0.3 parts by weight of alumina inorganic filler (BW-153), 0.3 parts by weight of cumyl peroxyneodecanoate (CPN) as an initiator, and 90 parts by weight of waste plastic pulverized material were blended to prepare a liquid sheet material composition, and this sheet material composition was poured into a mold frame composed of a mold plate and a gasket (mold). Next, calcium chloride was added to water, and the mold frame into which the sheet material composition was poured was vertically placed in a water tank filled with a heating medium having a specific gravity of 1.3 or more, and primary polymerization reaction was carried out at a temperature of 80 °C for 30 minutes, and then secondary polymerization reaction was carried out at a temperature of 100 °C for 30 minutes. Thereafter, the mold frame was taken out from the water tank, cooled to room temperature, and then the mold plate and the gasket were removed to manufacture a sheet material with a size of 300 mm × 300 mm × 10 mm.

[0035] [Examples 2 to 8] All processes were carried out in the same manner as in Example 1 except that the contents of each component were varied as described in Table 1 below.

[0036] [Comparative Example 1] For the water tank of the comparative example, all processes were carried out in the same manner as in Example 1, except that only water was filled as the heating medium.

[0037]

Table 1

[0038]

Table 2

[0039] Referring to Table 1 and Table 2 above, it was found that when a polymerization reaction was carried out in a water tank filled with a heating medium having a specific gravity higher than that of water according to the present invention, a recycled plastic sheet material having more excellent mechanical properties could be produced.

[0040] As described above, the present invention has been described by way of examples limited to specific matters, but this is merely provided to assist in a more general understanding of the present invention, and the present invention is not limited to these examples. Those having ordinary knowledge in the technical field to which the present invention pertains can make various modifications and deformations from such descriptions.

[0041] Therefore, the idea of the present invention should not be limited to the described examples, and not only the scope of the following claims, but also all those having modifications equivalent or equivalent to this scope of claims should belong to the scope of the idea of the present invention.

Claims

1. a) preparing a mold in which a gasket is installed between a pair of mold plates; b) injecting a sheet material composition into the mold; c) a primary polymerization reaction step of heating the mold filled with the sheet material composition by placing it in a water tank filled with a heating medium having a specific gravity higher than that of water; d) a secondary polymerization reaction step of heating at a temperature higher than that of the primary polymerization reaction; e) a demolding step of cooling after the secondary polymerization reaction step and removing the mold, comprising: The sheet material composition includes a binder composition and pulverized waste plastic classified by hue and pulverized, and a method for manufacturing a recycled plastic sheet.

2. The method for manufacturing a recycled plastic sheet according to claim 1, wherein the specific gravity of the heating medium is 1.1 to 2.

3. The method for manufacturing a recycled plastic sheet according to claim 2, wherein the heating medium includes water and a water-soluble inorganic salt.

4. The water-soluble inorganic salt is at least one selected from the group consisting of sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride, barium chloride, sodium nitrate, potassium nitrate, lithium nitrate, calcium nitrate, magnesium nitrate, barium nitrate, sodium sulfate, potassium sulfate, lithium sulfate, magnesium sulfate, sodium carbonate, potassium carbonate, and lithium carbonate. The method for manufacturing a recycled plastic sheet according to claim 3.

5. The method for manufacturing a recycled plastic sheet according to claim 1, wherein the sheet material composition includes 5 to 50 parts by weight of a binder composition and 95 to 50 parts by weight of pulverized waste plastic.

6. The method for manufacturing a recycled plastic sheet according to claim 1, wherein the binder composition includes at least one selected from the group consisting of an acrylic monomer, an acrylic resin, an unsaturated polyester resin, an epoxy resin, and a polystyrene resin.

7. The method for manufacturing a recycled plastic sheet according to claim 1, wherein the pulverized waste plastic includes at least one material selected from the group consisting of polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polycarbonate (PC), and acrylonitrile-butadiene-styrene (ABS).

8. The method for manufacturing a recycled plastic sheet according to claim 1, wherein the heating temperatures of the primary polymerization reaction and the secondary polymerization reaction are independently less than 50 to 130 °C.

9. The heating time of the primary polymerization reaction and the secondary polymerization reaction is 30 minutes to 2 hours. The method for manufacturing a recycled plastic sheet according to claim 1.

10. The size of the waste plastic pulverized material is 0.1 to 30 mm. The method for manufacturing a recycled plastic sheet according to claim 1.

11. A recycled plastic sheet manufactured by the method for manufacturing a recycled plastic sheet according to any one of claims 1 to 10.

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