Manufacturing method of building meterials from recycled waste resin

Abstract

The present invention provides a method for manufacturing a building material recycled from waste resin, comprising: a) a step of preparing a mixture comprising waste resin, a compatibilizer, and a binder; b) a step of extruding the prepared mixture; c) a step of air-cooling the molded product; and d) a step of water-cooling the air-cooled molded product.

Description

Technology Field

[0001] The present invention relates to a method for manufacturing construction materials using recycled waste resin, and more specifically, to a method for manufacturing civil engineering construction materials with improved mechanical properties by extruding and molding a mixture comprising waste resin, a compatibilizer, and a binder, followed by sequentially performing air cooling and water bath cooling. Background Technology

[0002] With the recent development of the petrochemical industry, various resin products have been developed and are widely used. In particular, as the usage of plastics has increased exponentially due to their low cost and excellent physical properties, the amount of waste plastic generated after use has also increased significantly.

[0003] Therefore, although large amounts of waste plastic are disposed of through landfill or incineration, landfilling is not only inefficient due to its large volume but also hinders early stabilization due to its non-biodegradability. Furthermore, while some thermal energy is utilized through incineration, low efficiency results in significant economic losses and causes problems such as the emission of toxic gases like dioxins.

[0004] As such, the recycling of waste plastics has a significant impact on the nation's industry, so there is an urgent need for the technological development of recycled products to address this issue.

[0005] Meanwhile, although research on construction materials made from recycled waste plastics is underway, there is a problem where using waste plastics mixed with various types as the main raw material leads to poor compatibility, resulting in degraded physical properties, particularly mechanical properties. Prior art literature

[0006] Republic of Korea No. 10-1543124 (2015.08.03) The problem to be solved

[0007] The present invention was devised to solve the above-mentioned problems, and the objective of the present invention is to provide a method for manufacturing construction materials using recycled waste resin that can solve environmental problems by manufacturing civil engineering construction materials using waste resin mixed with various types of resins, and to exhibit improved mechanical properties by performing a two-stage cooling process after extrusion and molding. means of solving the problem

[0008] The present invention provides a method for manufacturing a building material recycled from waste resin, comprising: a) a step of preparing a mixture comprising waste resin, a compatibilizer, and a binder; b) a step of extruding the prepared mixture; c) a step of air-cooling the molded product; and d) a step of water-cooling the air-cooled molded product.

[0009] According to one embodiment, the mixture may further include one or more additives selected from the group consisting of crosslinking agents, flame retardants, heat stabilizers, and UV stabilizers.

[0010] According to one embodiment, the binder may include one or more selected from the group consisting of polyvinyl acetate (PVAc), ethylene vinyl acetate (EVA), acrylic, melamine, urethane, and urea.

[0011] According to one embodiment, step c) may be characterized by being performed by spraying air at -10 to 10°C for 1 to 30 seconds. Effects of the invention

[0012] The present invention can solve environmental problems and secure economic efficiency by enabling the effective recycling of waste resins, which were previously difficult to process and had low economic efficiency due to regeneration, without a separate separation process.

[0013] In addition, the mechanical properties of the manufactured building materials can be improved through an optimized cooling process, enabling the provision of high-quality building materials. Specific details for implementing the invention

[0014] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described in detail below. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms; these embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. "And / or" includes each of the mentioned items and all combinations of one or more.

[0015] Unless otherwise defined, all terms used in this specification (including technical and scientific terms) may be used in a meaning that is commonly understood by those skilled in the art to which the present invention pertains. Throughout the specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Furthermore, the singular form includes the plural form unless specifically stated otherwise in the text.

[0017] The present invention provides a method for manufacturing a building material recycled from waste resin, comprising: a) a step of preparing a mixture comprising waste resin, a compatibilizer, and a binder; b) a step of extruding the prepared mixture; c) a step of air-cooling the molded product; and d) a step of water-cooling the air-cooled molded product.

[0018] a) Prior to step a), a pretreatment step may be performed in which the collected waste resin is first shredded and fed into a mesh structure that rotates and vibrates to remove foreign substances from the surface.

[0019] Waste resin basically refers to a mixture of various waste plastics and waste vinyl known to be recyclable, and may include two or more selected from the group consisting of polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), polyvinyl chloride (PVC), and acrylonitrile (ABS).

[0020] The above pretreatment step involves cutting the waste resin into an appropriate size to facilitate processing, feeding it into a horizontally positioned cylindrical mesh structure made of a wire mesh, and then rotating the mesh structure so that the waste resin is uniformly well mixed, thereby minimizing the phase separation phenomenon.

[0021] Meanwhile, by installing a vibration motor on the frame that supports the rotation of the mesh structure and applying intermittent vibration during rotation, foreign substances on the surface of the waste resin introduced inside can be efficiently removed. At this time, it is preferable that the size of the cut waste resin is larger than the mesh specifications of the mesh structure, and since bulky and heavy foreign substances have already been removed during the separate collection process, foreign substances that were not removed during the collection process, particularly clumps of soil attached to agricultural waste vinyl collected in rural areas, can be removed as much as possible.

[0022] In order to remove liquid components, including moisture, remaining in the waste resin introduced above and to minimize the deterioration of compatibility and physical properties in the subsequent mixing step of the compatibilizer and binder, hot air at 60 to 80°C can be supplied into the rotating mesh structure for 10 to 15 hours to dry it.

[0023] a) In step, a mixture comprising the above-mentioned pretreated waste resin, a compatibilizer, and a binder is prepared.

[0024] Compatibilizers are added to increase the compatibility of various resins within waste resins. They exist at the interfaces of separated phases to lower interfacial tension and enhance adhesion between interfaces. To this end, the compatibilizer may include one or more selected from the group consisting of ethylene-propylene rubber (EPR) and styrene-ethylene butylene-styrene block copolymer (SEBS).

[0025] Meanwhile, in order to uniformly improve the compatibility between various resins in a multi-component waste resin containing a mixture of various types of resins (LDPE, HDPE, PP, PS, PET, PVC, ABS) and to improve impact resistance, it is preferable that the compatibilizer simultaneously contains EPR and SEBS, and the weight ratio of EPR:SEBS may be 20:80 to 45:55, more preferably 30:70 to 40:60.

[0026] The binder can improve the mechanical strength of the final manufactured building material by providing excellent adhesion by adhering various resin particles within the waste resin well to each other, while also adhering the resin particles within the mixture and the additives described below. To this end, it is preferable that the binder include a water-soluble binder, and specifically, it may include one or more selected from the group consisting of polyvinyl acetate (PVAc), ethylene vinyl acetate (EVA), acrylic, melamine, urethane, and urea.

[0027] In order to impart an adhesion effect by the binder described above while suppressing the decrease in phase stability of the mixture due to increased viscosity, the mixture may contain 1 to 20 parts by weight, preferably 2 to 18 parts by weight, and more preferably 5 to 10 parts by weight of the binder per 100 parts by weight of the waste resin.

[0028] Meanwhile, the binder may be introduced in a solution state having a solid content of 20 to 60 weight%, preferably 30 to 50 weight%, to improve dispersibility within the mixture. The solvent used at this time may be at least one selected from the group consisting of water, pure water, deionized water, distilled water, ethanol, isopropanol, methanol, and acetone, but is not limited thereto.

[0029] The mixture according to the present embodiment can exhibit a synergistic effect by simultaneously including the aforementioned compatibilizer and binder, thereby simultaneously increasing the compatibility and adhesion of various resins included in the waste resin while ensuring phase stability, so that a building material with improved mechanical properties can be manufactured through a series of processes described later. To this end, it is advantageous for the weight ratio of the compatibilizer and the binder in the mixture to satisfy 2:1 to 5:1, preferably 2:1 to 4:1, and more preferably 2.5:1 to 4:1.

[0030] The above mixture may further include one or more additives selected from the group consisting of crosslinking agents, flame retardants, heat stabilizers, and UV stabilizers. In this case, in order to efficiently express the functional enhancement effect by said additives without causing a decrease in workability and physical properties, the amount of said additive may be less than 15 parts by weight, preferably 0.5 to 15 parts by weight, and more preferably 1 to 10 parts by weight, based on 100 parts by weight of said waste resin. Meanwhile, the content of said additive refers to the total content of said additives included in said mixture.

[0031] A crosslinking agent connects the molecules of a linear polymer compound to each other through chemical bonds to form a three-dimensional network-shaped polymer compound, thereby increasing the number of crosslinks and increasing resistance to external stress. It is preferable that the crosslinking agent comprises one or more selected from the group consisting of dicumyl peroxide (DCP), ditert-butyl peroxyisopropyl benzene (DTBPIB), and ditert-butyl peroxyhexane (DTBPH).

[0032] The above-mentioned waste resin may contain 0.5 to 5.5 parts by weight of the crosslinking agent, preferably 1 to 5 parts by weight, and more preferably 1 to 3 parts by weight, per 100 parts by weight of the above-mentioned waste resin. Accordingly, while maximizing the effects described above, the mixture can be extruded in a crosslinked state by a dynamic reaction, thereby increasing wear resistance and friction resistance.

[0033] The flame retardant is intended to impart flame retardancy and may preferably include one or more selected from the group consisting of sodium carbonate (Na2CO3), potassium carbonate (K2CO3), calcium carbonate (CaCO3), magnesium carbonate (MgCO3), barium carbonate (BaCO3), and aluminum carbonate (Al2(CO3)3).

[0034] By including 0.5 to 5.5 parts by weight, preferably 1 to 5 parts by weight, and more preferably 1 to 3 parts by weight of the flame retardant per 100 parts by weight of the waste resin, excellent flame retardancy is imparted, and at the same time, carbon dioxide is produced by thermal decomposition upon contact with a flame, thereby providing an initial fire suppression effect due to the reduction in oxygen concentration.

[0035] The heat stabilizer is intended to increase thermal stability and, specifically, may include one or more selected from the group consisting of diphenyl isooctyl phosphite and distearyl pentaeryl diphosphite. In this case, the heat stabilizer may be included in an amount of 0.5 to 5.5 parts by weight, preferably 1 to 5 parts by weight, and more preferably 1 to 3 parts by weight, per 100 parts by weight of the waste resin.

[0036] The UV stabilizer is intended to impart light resistance to ultraviolet rays and may include one or more selected from the group consisting of UV absorbers, quenchers, and hindered amine light stabilizers (HALS). In this case, the UV stabilizer may be included in an amount of 0.5 to 5.5 parts by weight, preferably 1 to 5 parts by weight, and more preferably 1 to 3 parts by weight, per 100 parts by weight of the waste resin.

[0037] The above mixture may further include one or more functional materials selected from the group consisting of lubricants, antioxidants, release agents, pigments, antistatic agents, antibacterial agents, processing aids, metal inerts, flame suppressants, fluorine-based anti-dripping agents, anti-friction agents, anti-wear agents, and coupling agents. The functional materials are not significantly limited as long as they are materials commonly used in the field.

[0038] b) In step, the above-described mixture is extruded. Specifically, the mixture comprising the aforementioned waste resin, compatibilizer, and binder is melt-fed and extruded into a specific shape.

[0039] The melting above can be performed at 180 to 260°C, preferably 180 to 250°C, and more preferably 190 to 230°C. If the melting temperature is below 180°C, there is a problem of poor moldability due to high viscosity and low density after molding, whereas if it exceeds 260°C, corrosive gases such as hydrogen chloride are generated.

[0040] Meanwhile, in order to secure excellent fluidity of the molten mixture obtained under the above melting conditions, it is preferable that the waste resin contains 40% by weight or more of a thermoplastic resin, preferably 50% to 90% by weight. Accordingly, it is possible to produce a molten mixture in which the liquid portion is 50% to 90% and the solid or low-fluidity portion is 10% to 50% during the melting process described above, thereby increasing adhesion and uniformity during subsequent extrusion molding and enabling the production of a high-density molded product.

[0041] The above molten mixture may contain hydrogen chloride gas generated as a result of the decomposition of some waste resin components, air introduced during the waste resin pretreatment process, and gases generated as liquid components attached to the waste resin evaporate. If extrusion molding is performed immediately in this state, pores may form in the manufactured molded product, which may lead to a decrease in density after cooling; therefore, a gas removal process may be performed after the melting process. At this time, the gas removal method is not significantly limited as long as it is a gas removal method commonly used in the industry, but preferably, the gas removal process may be performed using a vacuum or compressed nitrogen.

[0042] Next, the molten mixture is extruded. Specifically, a screw rotating inside a screw pressure molding machine advances in a uniaxial direction to pressurize the molten mixture in a paste state and extrude it into a mold. Accordingly, it becomes possible to manufacture various building materials that can be produced by extrusion, such as paving blocks, bricks, braille blocks, street tree gutters, manhole covers, landscaping walls, etc.

[0043] c) In step, the molded product is air-cooled. The air-cooling can be performed by installing an air-cooling device on the front of the mold and spraying air at -10 to 10°C, preferably -8 to 5°C, more preferably -5 to 0°C, for 1 to 30 seconds, preferably 2 to 20 seconds, more preferably 3 to 15 seconds, immediately after the molten mixture is extruded into the mold.

[0044] The above molten mixture can recover high viscosity by being rapidly air-cooled immediately after extrusion. Accordingly, binder migration occurring during the water bath cooling process for the subsequent manufacture of the final molded product can be suppressed, thereby maintaining a uniform distribution of binder within the manufactured molded product and reducing the problem of reduced mechanical strength. On the other hand, if the air-cooling conditions deviate from the aforementioned range, the binder migration suppression effect intended by the present invention may be negligible, or severe thermal shrinkage may occur in the manufactured molded product, causing deformation of its external shape.

[0045] In step d), the air-cooled molded product is cooled in a water bath. The water bath cooling is performed by immediately immersing the air-cooled molded product from step c) into a water bath. At this time, the water bath cooling can be performed for 1 to 30 minutes in a water bath in which water circulates at a temperature of 10 to 80°C, preferably 15 to 80°C, more preferably 20 to 60°C.

[0046] The method for manufacturing a building material using recycled waste resin according to the present invention can provide a building material having excellent mechanical strength while minimizing external deformation of the molded product due to thermal shrinkage by performing the aforementioned air cooling and water bath cooling in stages.

[0047] Furthermore, the building material manufactured according to one embodiment of the present invention is environmentally friendly and economical by recycling waste resin, and in particular, can provide a high-quality building material by solving the problem of reduced mechanical strength caused by the migration of materials such as binders within the molten mixture during the manufacturing process, resulting in uneven distribution in the thickness or plane direction of the molded product.

[0049] The present invention will be described in detail below through examples, but these are intended to explain the invention in more detail and the scope of the present invention is not limited by the following examples.

[0051] Examples

[0052] (Example 1)

[0053] According to a survey on the generation status of mixed waste plastics by the Korea Resource Recycling Corporation, the types and average composition of mixed waste plastics collected from each business site were found to be PE 26%, PP 3.8%, PS 14.6%, PET 23.4%, and others 11.7%.

[0054] In the case of PET, separate disposal treatment is currently being carried out, and since the added value from the recycling of PET itself is high, the recycling rate is relatively high. Therefore, in the embodiment of the present invention, a mixed waste resin consisting of five components excluding PET—LDPE, HDPE, PP, PS, and ABS—was utilized, and a waste resin mixed with LDPE, HDPE, PP, PS, and ABS in a weight ratio of 20:20:30:20:10 was utilized.

[0055] Using the above waste resin, a mixture of the compositions listed in Table 1 below was melt-mixed at 200°C, and after extrusion molding, paving blocks were manufactured by sequentially performing air-spray cooling and water bath immersion cooling under the conditions listed in Table 2 below. At this time, the content listed in Table 1 below is the content of each composition based on 100 parts by weight of waste resin; the binder content (parts by weight) is controlled by adding a binder solution in which the solvent is water and the solid content is 40% by weight.

[0057] furtherance Content (parts by weight) Commercialization agent EPR 20 bookbinder EVA 6 crosslinking agent Dicumyl peroxide 2 UV stabilizer HALS 1.5

[0058] (In Table 1, the content of each composition is based on 100 parts by weight of waste resin.)

[0060] (Example 2)

[0061] A paving block was manufactured by carrying out the same procedure as in Example 1 above, except that a compatibilizer mixed with EPR:SEBS in a 1:1 weight ratio was used instead of the compatibilizer EPR.

[0063] (Examples 3 to 4)

[0064] The above Example 2 was carried out in the same manner, except that the cooling process was performed under the conditions listed in Table 2 below.

[0066] (Example 5)

[0067] A paving block was manufactured by carrying out the same procedure as in Example 2 above, except that a mixture containing 1 part by weight of diphenyl isooctyl phosphite was additionally used.

[0069] (Comparative Example 1)

[0070] A paving block was manufactured by carrying out the same procedure as in Example 2 above, except that water tank cooling was performed immediately without performing the air cooling process.

[0072] (Comparative Example 2)

[0073] A paving block was manufactured by carrying out the same procedure as in Example 2 above, except that a mixture not containing a compatibilizer was used.

[0075] (Comparative Example 3)

[0076] A paving block was manufactured by carrying out the same procedure as in Example 2 above, except that a mixture not containing a binder was used.

[0078] air cooling Water tank cooling Example 1 -3℃, 8 seconds 40℃, 20 minutes Example 2 -3℃, 8 seconds 40℃, 20 minutes Example 3 -8℃, 5 seconds 40℃, 20 minutes Example 4 1℃, 10 seconds 40℃, 20 minutes Example 5 -3℃, 8 seconds 40℃, 20 minutes Comparative Example 1 - 40℃, 20 minutes Comparative Example 2 -3℃, 8 seconds 40℃, 20 minutes Comparative Example 3 -3℃, 8 seconds 40℃, 20 minutes

[0080] Experimental Example: Evaluation of Mechanical Properties

[0081] Tensile strength and elongation measurement

[0082] The tensile strength and elongation of the paving blocks manufactured according to Examples 1 to 5 and Comparative Examples 1 to 3 were measured according to ASTM D638 standards, and the results are shown in Table 3 below.

[0084] *Flexibility strength measurement

[0085] The flexural strength of the paving blocks manufactured according to Examples 1 to 5 and Comparative Examples 1 to 3 was measured according to the KS F 4419 standard, and the results are shown in Table 3 below.

[0087] Tensile strength (MPa) Growth Rate (%) Flexural strength ((MPa) Example 1 10.6 20.4 5.1 Example 2 13.2 38.2 6.2 Example 3 11.2 28.4 5.1 Example 4 12.4 29.1 5.6 Example 5 13.1 38.3 6.0 Comparative Example 1 7.8 14.6 2.4 Comparative Example 2 9.6 12.3 4.3 Comparative Example 3 8.6 10.9 3.6

[0088] As can be seen in Table 3 above, the building material according to the present invention exhibited excellent mechanical properties by performing a two-stage cooling process including air cooling and water bath cooling after extrusion molding using a mixture of a specific composition including waste resin.

[0089] Meanwhile, it can be confirmed that the embodiments (Examples 1, 2, and 5) satisfying the most preferred air cooling conditions presented in the present invention exhibited higher mechanical properties compared to Examples 3 and 4, which did not. This suggests that differences in the mechanical properties of the molded article produced occur depending on the cooling method of the molten mixture.

[0090] In addition, in the case of Comparative Examples 2 and 3, which do not contain a compatibilizer or binder, it can be confirmed that the tensile strength and elongation values ​​were significantly reduced despite performing the same cooling method as in the example. These results suggest that the cooling method of the molten mixture according to the present invention does not have significance in isolation, but rather exhibits a synergistic effect by acting in combination with the composition of the molten mixture.

Claims

Claim 1 a) A mixture comprising 100 parts by weight of a raw material, which is entirely composed of waste resin and is a mixture of Low Density Polyethylene (LDPE), High Density Polyethylene (HDPE), Polypropylene (PP), Polystyrene (PS), and Acrylonitrile (ABS) in a weight ratio of 20:20:30:20:10, 20 parts by weight of a compatibilizer formed by mixing ethylene-propylene rubber (EPR) and styrene-ethylene butylene-styrene block copolymer (SEBS) in a 1:1 weight ratio, 6 parts by weight of a binder formed of ethylene vinyl acetate (EVA), 2 parts by weight of a crosslinking agent formed of dicumyl peroxide (DCP), and a hindered amine light stabilizer (HALS). A method for manufacturing a building material recycled from waste resin, comprising: a) preparing a mixture consisting of 1.5 parts by weight of a UV stabilizer; b) extruding the prepared mixture at a melting temperature of 190 to 230°C; c) air-cooling the molded product by spraying it with air at -3°C for 8 seconds; and d) water-cooling the air-cooled molded product in a water bath where water at 40°C is circulated for 20 minutes. Claim 2 delete Claim 3 delete Claim 4 delete

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