KR102350652B1 - Method for recycling acryl scrap - Google Patents

Abstract

The present invention relates to a method for recycling acrylic scrap. In one embodiment, the acrylic scrap recycling method comprises the steps of: pyrolyzing acrylic scrap at 800° C. or higher to separate vaporized decomposition products; preparing a decomposition solution by liquefying the vaporized decomposition product; and distilling the decomposition solution to obtain an acrylic monomer.

Description

How to recycle acrylic scrap {METHOD FOR RECYCLING ACRYL SCRAP}

The present invention relates to a method for recycling acrylic scrap.

Acrylic materials are being used in various ways throughout the industry. Examples of such acrylic materials include polymethyl methacrylate (PMMA), and PMMA is a synthetic resin manufactured using methyl methacrylate (MMA) as a main raw material. It is used in all industries including electronic parts. The methyl methacrylate (MMA) is produced by oxidizing isobutylene extracted from C ₄ -resid in a gas phase to prepare methacrylic acid (MAA), and then performing an esterification reaction using alcohol.

On the other hand, the acrylic material remaining after manufacturing a product using an acrylic material in the form of a sheet or the like is called scrap, and conventional acrylic scrap has been discarded without separate recycling. These acrylic scraps are generated throughout the industry, such as light guide plates for optical display devices such as LCD TVs, automobiles, signs, and artificial marble production, and the amount of acrylic scrap is also increasing. Accordingly, problems such as an increase in waste disposal cost and environmental pollution are exacerbated.

Recently, an increase in crude oil prices and an increase in the cost of petroleum-related products have adversely affected the overall domestic industry, and acrylic, one of the petroleum-related products, is also affected. Therefore, research is being actively conducted to recycle acrylic scraps that are conventionally disposed of.

A conventional technique for recycling such acryl-based scrap is a technique for collecting, collecting, crushing and melting the acrylic scrap, then pelletizing and extruding the acrylic scrap for recycling. However, since the acrylic material recycled in this way contains colorants and other components other than the acrylic component, there is a problem that yellowing occurs or the color is discolored, so that the usefulness thereof is low.

Background art related to the present invention is disclosed in Republic of Korea Patent Publication No. 10-1048268 (published on Jul. 8, 2011, title of the invention: recycling method of waste acrylic resin).

One object of the present invention is to provide a method for recycling acrylic scrap having high purity of recycled acrylic material and excellent mechanical properties.

Another object of the present invention is to provide an acrylic scrap recycling method capable of preventing yellowing and color change of the recycled acrylic material.

Another object of the present invention is to provide a method for recycling acrylic scrap having excellent productivity, economy, and eco-friendliness.

One aspect of the present invention relates to a method for recycling acrylic scrap. In one embodiment, the acrylic scrap recycling method comprises the steps of: pyrolyzing acrylic scrap at 800° C. or higher to separate vaporized decomposition products; preparing a decomposition solution by liquefying the vaporized decomposition product; and distilling the decomposition solution to obtain an acrylic monomer.

In one embodiment, the thermal decomposition may be carried out at 800 ~ 1100 ℃.

In one embodiment, after obtaining the acrylic monomer, preparing a polymer by polymerizing a first composition comprising the acrylic monomer, water, a colorant and a reaction initiator; and manufacturing the molded article by molding the polymer.

In one embodiment, the first composition may include 100 parts by weight of the acrylic monomer, 10 to 200 parts by weight of water, 1 to 30 parts by weight of a colorant, and 0.1 to 30 parts by weight of a reaction initiator.

In one embodiment, the polymerization is to prepare a primary product by primary polymerization of the first composition in a reactor at 75 ~ 90 ℃; Secondary polymerization of the primary product at 95 ~ 110 ℃ to prepare a secondary product; cooling the secondary product; And dehydrating and drying the cooled secondary product; may be made to include.

The recycled acrylic material manufactured according to the acrylic scrap recycling method of the present invention has high purity, excellent mechanical properties, can prevent yellowing and color change, has excellent productivity and economy, and prevents environmental pollution due to waste. Eco-friendliness may be excellent.

1 shows a method for recycling acrylic scrap according to an embodiment of the present invention.
Figure 2 is a photograph showing the acrylic scrap recycling process of the embodiment.
3 is a photograph showing a polymer prepared by polymerizing the acrylic monomer of Example.

In describing the present invention, if it is determined that a detailed description of a related known technology or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

And the terms described below are terms defined in consideration of functions in the present invention, which may vary depending on the intention or custom of the user or operator, and the definition should be made based on the content throughout this specification describing the present invention.

As used herein, the term “(meth)acryl” may refer to acryl and/or methacryl.

How to Recycle Acrylic Scrap

One aspect of the present invention relates to a method for recycling acrylic scrap. 1 shows a method for recycling acrylic scrap according to an embodiment of the present invention.

Referring to FIG. 1 , the method for recycling acrylic scrap includes (S10) thermal decomposition; (S20) liquefaction step; and (S30) a distillation step. More specifically, the acrylic scrap recycling method includes the steps of (S10) pyrolyzing acrylic scrap at 800° C. or higher to separate vaporized decomposition products; (S20) preparing a decomposition solution by liquefying the vaporized decomposition product; and (S30) distilling the decomposition solution to obtain an acrylic monomer.

Hereinafter, the acrylic scrap recycling method of the present invention will be described in detail step by step.

(S10) pyrolysis step

The step is a step of separating the vaporized decomposition product by thermally decomposing the acrylic scrap at 800° C. or higher.

In one embodiment, the acrylic scrap may be a polymer including a methyl methacrylate unit. For example, it may include a polymer of 60 to 100% by weight of methyl methacrylate and 0 to 40% by weight of an alkyl (meth)acrylate. For example, the acrylic scrap may further include additives such as a physical property improving agent, a stabilizer, and a colorant based on 100 parts by weight of the polymer. As another example, the acrylic scrap may include polymethyl methacrylate.

In one embodiment, the acrylic scrap may be pyrolyzed in the form of a crushed product crushed to a size of 0.01 to 20 mm. The "size" may mean the "maximum length" of the crushed material.

The pyrolysis is carried out at a temperature of 800 °C or higher. When the thermal decomposition is carried out at a temperature of less than 800 ° C., the thermal decomposition of the acrylic scrap is not performed properly, and the yield of the acrylic monomer is lowered, the mechanical strength of the manufactured acrylic molded article is lowered, or the color such as yellowing on the surface may be discolored. have. For example, the thermal decomposition may be performed at 850 to 1100 °C. For example, the thermal decomposition may be performed at 850 to 1100° C. for 1 hour to 15 hours.

(S20) liquefaction step

The step is a step of preparing a decomposition solution by liquefying the vaporized decomposition product. The liquefaction may be carried out by a conventional method. For example, after recovering the vaporized decomposition product, the decomposition liquid may be prepared by liquefying the vaporized decomposition product using cold water and a cooling condenser.

(S30) distillation step

The step is a step of distilling the decomposition solution to obtain an acrylic monomer. For example, the distillation can be recovered by heating the decomposition solution to vaporize the acrylic monomer. During the distillation, the purity of the acrylic monomer is increased, the mechanical properties of the prepared acrylic molded article are excellent, and color discoloration such as yellowing can be prevented.

In one embodiment, the distillation may be carried out at a temperature of 85 to 100 °C. Under the above conditions, the acrylic monomer can be easily separated from water. The vaporized acrylic monomer can be obtained by cooling and liquefying it in a conventional manner. In one embodiment, the distillation may be carried out under reduced pressure conditions. Under the above conditions, the purity of the acrylic monomer may increase.

In one embodiment, the acrylic monomer may include methyl methacrylate.

Referring to FIG. 1 , the acrylic scrap recycling method includes: after the distillation step (S30), (S40) a polymerization step; and (S50) forming step; may further include.

(S40) polymerization step

This is a step of preparing a polymer by polymerizing the first composition including the acrylic monomer, water, a colorant, and a reaction initiator.

In one embodiment, the first composition may include 100 parts by weight of the acrylic monomer, 10 to 200 parts by weight of water, 1 to 30 parts by weight of a colorant, and 0.1 to 30 parts by weight of a reaction initiator.

The water may be included in an amount of 10 to 200 parts by weight based on 100 parts by weight of the acrylic monomer. The polymerization reaction can easily occur under the above conditions. For example, pure water may be used as the water.

The colorant may be included to prevent yellowing of the polymer. In one embodiment, the colorant is a phycocyanin-based pigment (ice colorant), a phthalocyanine-based pigment, an azo-based pigment, an anthraquinone-based pigment, a perylene-based pigment, Indigo pigment, dioxazine pigment, quinacridone pigment, isoindolyline pigment, isoindolinone pigment, carbon black pigment , may include at least one of an extender pigment, a titanium oxide-based pigment, an iron oxide-based pigment, and a spinel pigment.

The colorant may be included in an amount of 1 to 30 parts by weight based on 100 parts by weight of the acrylic monomer. When included in the above range, yellowing or discoloration can be easily prevented when manufacturing a molded article using the polymer.

In one embodiment, the reaction initiator includes at least one of ammonium persulfate, potassium persulfate, sodium hydrosulfite, sodium persulfate and sodium hydrogen sulfate. can do. When the above type of reaction initiator is included, polymerization is facilitated, and the mechanical properties of the acrylic molded body may be excellent.

In one embodiment, the reaction initiator may be included in an amount of 0.1 to 30 parts by weight based on 100 parts by weight of the acrylic monomer. When included in the above range, polymerization can be easily accomplished.

In one embodiment, the first composition may further include 1 to 30 parts by weight of an additive based on 100 parts by weight of the acrylic monomer.

In one embodiment, the additive may include at least one of a dispersant, a chain transfer agent, and a stabilizer.

In one embodiment, the chain transfer agent may include at least one of mercaptopropyl triethoxysilane, γ-mercaptopropyl, trimethoxy silane, and mercaptomethyl methyl dimethoxysilane.

In one embodiment, the dispersing agent is methyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, polyethylene glycol, polyvinylpyrrolidone polyacrylamide, organic material of polystyrene sulfonate, calcium phosphate, carbonic acid It may include at least one of calcium, glycerin fatty acid ester, sorbitan fatty acid ester, and propylene glycol fatty acid ester. When the dispersing agent is used, the dispersibility of the polymer may be excellent.

In one embodiment, the stabilizer may include at least one of a colloidal compound and an inorganic salt. The colloidal compound may include at least one of gelatin, starch, carboxymethyl cellulose and polyvinyl alcohol. The inorganic salt may include at least one of barium sulfate (BaSO ₄ ), calcium sulfate (CaSO ₄ ), magnesium carbonate (MgCO ₃ ), diatomaceous earth, and bentonite.

In one embodiment, during the polymerization, the first composition is first polymerized at 75-90° C. in a reactor to prepare a primary product; Secondary polymerization of the primary product at 95 ~ 110 ℃ to prepare a secondary product; cooling the secondary product; And a step of dehydrating and drying the cooled secondary product; including; a polymer can be prepared.

In one embodiment, prior to the primary polymerization, nitrogen (N ₂ ) It may be carried out by removing oxygen in the reactor to which the first composition is introduced through purging. In the case of polymerization under the above conditions, the generation of by-products can be minimized.

In one embodiment, the primary polymerization may be carried out at 75-90° C. for 1 to 10 hours. In the case of primary polymerization under the above conditions, mechanical properties of the primary product may be excellent.

In one embodiment, the secondary polymerization may be carried out at 95 ~ 110 ℃ for 10 minutes to 3 hours. In the case of secondary polymerization under the above conditions, mechanical properties of the secondary product may be excellent.

In one embodiment, during the dehydration, the water content of the secondary product may be adjusted to 7% by weight. When molding the polymer under the above conditions, the moldability may be excellent. For example, the water content of the secondary product during dehydration may be 7 to 10% by weight.

In one embodiment, the drying may be performed using a fluidized bed dryer. In one embodiment, the drying may control the water content of the secondary product to 0.5% by weight. Formability may be easy when molding the polymer under the above conditions. For example, the water content of the polymer produced during drying may be 0.5 to 1.5 wt%.

In one embodiment, the polymer may be in the form of a bead, but is not limited thereto. For example, the polymer may be packaged and sold in a polyvinyl chloride (PVC) bag in units of 1 ton.

In one embodiment of the present invention, wastewater generated in the polymerization process of the first composition may be filtered through a filter and used instead of water (pure water) of the first composition. As described above, by recycling water to prevent the discharge of wastewater when used, it can be excellent in eco-friendliness.

(S50) forming step

The step is a step of preparing a molded article by molding the polymer. For example, in the molding, the polymer is put into an extruder, and after extrusion, it is pelletized by a method such as water cooling cutting, and the pelletized polymer is injected into a molded body of a predetermined shape by a method such as injection.

In the conventional acrylic (PMMA) molded body manufacturing process (normal casting) using an acrylic monomer, a polymer is prepared by primary polymerization of an acrylic monomer, and the polymer is injected into a mold made of glass and then cured in the vertical direction using water. It was prepared by drying and masking. However, the manual work as described above requires more than 15 people to produce 130-150 tons per month, so production is low and labor costs are high, making it difficult to produce. There was a problem with this degradation.

On the other hand, according to the acrylic scrap recycling method of the present invention, when manufacturing an acrylic molded body, the purity is high, mechanical properties are excellent, yellowing and color change can be prevented, productivity and economy are excellent due to process automation, and the environment caused by waste By preventing pollution, it can be excellent in eco-friendliness.

Hereinafter, the configuration and operation of the present invention will be described in more detail through preferred embodiments of the present invention. However, this is presented as a preferred example of the present invention and cannot be construed as limiting the present invention in any sense. Content not described here will be omitted because it can be technically inferred sufficiently by a person skilled in the art.

Examples and Comparative Examples

Example

(1) Preparation of acrylic monomer: As shown in FIG. 2(a), acrylic scrap including polymethyl methacrylate was recovered and pulverized to a size of 1 mm to prepare a pulverized product. As shown in FIG. 2(b), the pulverized product was put into a melting furnace, and the vaporized separated product was separated by thermal decomposition at a temperature of 850 to 1100° C. for 8 hours. The vaporized separation product was recovered through a pipe provided on one side of the melting furnace, and the vaporized decomposition product was liquefied to prepare a decomposition solution. Then, as shown in FIG. 2(c), the decomposition solution was distilled under reduced pressure to obtain about 2 kg of an acrylic monomer.

(2) Preparation of molded article: A first composition comprising 100 parts by weight of the acrylic monomer, 50 to 200 parts by weight of water (pure water), 1 to 5 parts by weight of a colorant, and 0.5 to 5 parts by weight of a reaction initiator was prepared. In a stainless steel reactor as shown in Fig. 3(a), nitrogen (N ₂ ) is purged to remove oxygen inside the reactor to which the first composition is introduced and preheated, and then the first composition is added and at 82 to 83 ° C. Reacted for 3 hours to prepare a primary product by primary polymerization, and secondary polymerization of the primary product at 105° C. for 30 minutes to prepare a secondary product. Then, the secondary product is transferred to a dehydration line and dehydrated to a moisture content of 7% by weight, and then transferred to a drying line as shown in FIG. 3(b) and dried to a moisture content of 0.5% by weight or less, FIG. 3(c) Polymers in the form of beads were prepared, such as Then, the polymer was put into a twin-screw extruder and extruded, and then cut into pellets by water cooling, and then injection molded to prepare an acrylic molded body in the form of a sheet.

Wastewater generated in the polymerization process of the first composition was filtered through a filter and used instead of water (pure water) of the first composition.

comparative example

An acrylic molded body was manufactured in the same manner as in the above example, except that the acrylic scrap was pyrolyzed at a temperature of 700° C. for 8 hours.

The physical properties of the acrylic molded articles of Examples and Comparative Examples were evaluated in the following manner.

(1) Appearance evaluation of molded body

Examples and Comparative Examples The appearance of the molded article was visually observed to evaluate whether yellowing and discoloration occurred, and it was determined according to the following criteria. (double-circle: yellowing or discoloration did not occur, △: yellowing or discoloration slightly occurred, X: yellowing or discoloration occurred very severely).

Referring to the results of Table 1, in the case of the acrylic molded article prepared in Examples, discoloration such as yellowing did not occur. However, in the case of the acrylic molded article of Comparative Example outside the thermal decomposition temperature of the present invention, it was found that yellowing occurred and the appearance quality was deteriorated.

Up to now, the present invention has been looked at focusing on examples. Those of ordinary skill in the art to which the present invention pertains will understand that the present invention can be implemented in modified forms without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments are to be considered in an illustrative rather than a restrictive sense. The scope of the present invention is indicated in the claims rather than the foregoing description, and all differences within the scope equivalent thereto should be construed as being included in the present invention.

Claims (5)

Separating the vaporized decomposition product by thermally decomposing the acrylic scrap at 800° C. or higher;
preparing a decomposition solution by liquefying the vaporized decomposition product;
distilling the decomposition solution to obtain an acrylic monomer;
preparing a polymer by polymerizing a first composition including the acrylic monomer, water, a colorant, and a reaction initiator; and
It is an acrylic scrap recycling method comprising; manufacturing the molded body by molding the polymer;
The polymerization is, to prepare a primary product by primary polymerization of the first composition at 75 ~ 90 ℃ inside the reactor; Secondary polymerization of the primary product at 95 ~ 110 ℃ to prepare a secondary product; cooling the secondary product; and dehydrating and drying the cooled secondary product.
The method of claim 1, wherein the pyrolysis is performed at 800 to 1100°C.
delete The method of claim 1, wherein the first composition comprises 100 parts by weight of the acrylic monomer, 10 to 200 parts by weight of water, 1 to 30 parts by weight of a colorant, and 0.1 to 30 parts by weight of a reaction initiator.

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