JP2015021109A - Thermoplastic recycled resin material and molded body using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve properties of an obtained low-grade regenerated resin material by modifying the selection sensitivity of a near-infrared ray selector.SOLUTION: At least one selected from thermoplastic elastomers, additives selected from graft copolymers with a polyolefin as the principal chain and maleic anhydride-grafted polymers is added to a polypropylene-based resin material selected from thermoplastic resin waste materials including a plurality of substances by using a near-infrared ray selection system, and the resultant mixture is kneaded with heating.

Description

  The present invention can ensure durability, high quality, and safety when separating and sorting the target synthetic resin from the classification target that contains multiple types of synthetic resin such as used home appliances. The present invention relates to a thermoplastic recycled resin material for the purpose of obtaining a thermoplastic recycled resin.

  Recent mass production, mass consumption, and mass disposal economic activities have caused global environmental problems such as global warming and resource depletion. Under these circumstances, the Home Appliance Recycling Law was fully enforced in April 2001, and recycling of used air conditioners, TVs, refrigerators / freezers and washing machines was obliged to build a recycling-oriented society. ing.

  Conventionally, household appliances that are no longer needed are collected and recycled for each material by using magnetism, wind power, vibration, etc. after crushing at a household appliance recycling factory. In particular, by using a specific gravity sorting device or a magnetic sorting device, the metal material is recovered with high purity for each material such as iron, copper, and aluminum, and a high recycling rate is realized.

  On the other hand, for resin materials, water is used to separate low specific gravity and high specific gravity, and the water specific gravity sorting method that collects, or the sorting method that uses the absorption characteristics peculiar to the substance by irradiating electromagnetic waves such as near infrared rays. An electrostatic separation method is used in which separation is performed by using a difference in electrical properties depending on materials.

  However, various incompatible impurities are mixed in the regenerated resin material, and it has been pointed out that physical properties are deteriorated due to the mixing of impurities. Furthermore, in the future, it will be necessary to increase the use of recycled resin materials for the establishment of a recycling-oriented society, but currently, high-quality, high-purity recycled resin materials are low in distribution volume, and increasing supply without cost. Since it is very difficult, a technique for using low-quality, low-purity resin is required.

  Conventionally, in order to solve the problem of deterioration in physical properties of recycled resin selected by water specific gravity sorting, there has been one in which improvement of physical properties has been verified by adding one or more kinds of compatibilizers (for example, patents) Document 1 and Patent document 2).

JP 2004-182957 A JP 2007-130831 A

  However, in Patent Documents 1 and 2, water specific gravity sorting is used as sorting means, and it is not easy to change the purity of the obtained recycled resin material, and the production of the recycled resin material is reduced by reducing the purity of the recycled resin material. It was difficult to increase the amount. As a method of changing the purity of the recycled resin material, it is possible to add some solute to water to increase the specific gravity, or to perform selection using liquids other than water with different specific gravity. This may have a negative impact on the environment, for example, as compared to the case of using the system.

  Therefore, when the water specific gravity sorting is used, it is difficult to increase the production amount of the recycled material because it is not easy to change the purity of the obtained recycled resin material.

  An object of the present invention is to increase the supply amount of the recycled resin material by changing the sorting sensitivity of the near-infrared sorting apparatus, and to improve the physical properties of the obtained low-grade recycled resin material.

  In order to solve the above-mentioned conventional problems, the thermoplastic recycled resin of the present invention includes at least a thermoplastic elastomer in a polypropylene-based resin material selected using a near-infrared sorting system from a thermoplastic resin waste material in which a plurality of substances are mixed. An additive selected from graft copolymers having a polyolefin as a main chain and at least one selected from a maleic anhydride grafted polymer are added and kneaded by heating.

  The thermoplastic recycled resin material of the present invention can increase the supply amount of the recycled resin material, and can improve the physical properties of the obtained low-grade recycled resin material.

The figure which shows the general reproduction | regeneration process in Embodiment 1 of this invention. The figure which shows the near-infrared sorting system in Embodiment 1 of this invention The figure showing the breaking elongation of the sheet-like dumbbell in Embodiment 1 of this invention The figure which shows the transmission type | mold microscope picture of Example 1 and Comparative Example 1 in Embodiment 1 of this invention

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an example of the regeneration process of the method for recycling thermoplastic resin waste material according to Embodiment 1 of the present invention.

  The recovery process of the thermoplastic resin waste material of this invention is demonstrated using a used refrigerator as an example. Disassemble and remove the refrigerant and compressor from the used refrigerator, which is a waste home appliance, and remove resin such as cases and shelves from the vegetable compartment, freezer compartment, refrigeration compartment, etc. by manual disassembly, and crush it with a crusher. Furthermore, metal such as iron is removed from the crushed pieces mixed with metal and plastic by magnetic force, and light urethane foam or the like is removed by suction with wind force. A non-ferrous metal such as copper or aluminum is removed from a crushed piece from which iron, urethane foam or the like has been removed by an eddy current selector, and then a thermoplastic waste material mixed with a plurality of resins of 5 to 150 mm is collected by sieving.

  The obtained thermoplastic waste material is sorted into a specific type of resin material and another resin material by a near infrared identification system. In the present embodiment, a polypropylene (PP) resin is set as a specific type of resin material.

  Next, an example of a near-infrared identification system will be described.

  Since organic compounds have different light absorption wavelength bands for each atomic group in the substance, they exhibit a unique near-infrared absorption spectrum depending on the molecular structure. The near-infrared identification system is a system that identifies the material of an organic compound by utilizing the fact that the organic compound exhibits a unique near-infrared absorption spectrum depending on the molecular structure.

Specifically, the type of the synthetic resin material is specified by irradiating the synthetic resin material with near infrared rays and measuring the absorption spectrum. As a feature of the near-infrared absorption spectrum, the peak position, width, and intensity change due to hydrogen bonds and intermolecular interactions, so that a bromine-containing resin can also be identified by measuring the near-infrared absorption spectrum.

  FIG. 2 is a perspective view schematically showing the near-infrared identification system according to Embodiment 1 of the present invention.

  As shown in FIG. 2, the near-infrared identification system 20 is a near-infrared ray that is a transport device 1 that transports the pulverized mixed material and an information acquisition device that discriminates individual materials of the mixed material transported by the transport device 1. An identification device 4, a tube body 8 having a discharge port 5, an air pressure source 15 for supplying high-pressure air to the tube body 8, and an electromagnetic valve 10 for controlling high-pressure air from the air pressure source 15 to the tube body 8; A control means 14 and a sorting plate 6 are provided.

  In the first embodiment, the near-infrared identification device 4 sets polypropylene as a thermoplastic resin material to be separated, and discriminates polypropylene from the pulverized mixed material. The polypropylene resin may be a homopolymer, a block copolymer, or a random polymer.

  The operation and action of the near infrared identification system will be described below.

  The pulverized thermoplastic resin waste material 11 containing the thermoplastic resin material 2 and other synthetic resin materials 3 to be separated is sprayed on the conveying device 1 so as not to overlap each other. The conveyance device 1 conveys the thermoplastic resin waste material 11 at a speed of about 2 m / sec toward the near-infrared identification device 4 that is an information acquisition device. The near-infrared identification device 4 determines the type of the thermoplastic resin waste material 11 conveyed by the conveyance device 1 and acquires position information in each width direction (x-axis direction).

  Specifically, the near-infrared identification device 4 includes a near-infrared sensor, and based on the difference in near-infrared absorption spectrum between the thermoplastic resin material 2 and the other synthetic resin material 3, the thermoplastic resin material 2 and the other synthetic material are combined. The resin material 3 is identified. Moreover, the thermoplastic resin waste material 11 is imaged, and the positional information of the thermoplastic resin material 2 is acquired based on the analysis result of the obtained image and the identification result by the near infrared absorption spectrum.

  The conveyance device 1 conveys the thermoplastic resin waste material 11 toward the downstream side of the near-infrared identification device 4. The control means 14 controls the electromagnetic valve 10 based on the position information from the near-infrared identification device 4, and the high-pressure air (discharge pressure: from the discharge port 5 toward the thermoplastic resin material 2 falling from the end of the transport device 1. 5 bar) is jetted to jump over the sorting plate 6. When the synthetic resin material 3 other than the thermoplastic resin material 2 passes through the discharge port 5, the high pressure air is not jetted from the discharge port 5, and thus falls without jumping over the separation plate 6. Thereby, the thermoplastic resin material 2 and the other synthetic resin material 3 can be separated, and the thermoplastic resin material 2 can be efficiently recovered with the target purity.

  If the specific structure of each component of the near-infrared identification system 20 is demonstrated, the pipe body 8 can specifically illustrate a metal pipe. Specifically, the electromagnetic valve 10 is a so-called solenoid valve. The control means 14 is specifically a so-called computer. Specifically, the air pressure source 15 is a compressor that supplies air at a constant pressure.

  The thermoplastic resin material 2 separated by the near-infrared sorting system is crushed to a size of 2 to 50 mm by a crusher, and then the surface deposits are removed by a dry cleaning device as shown in the flowchart of FIG. Remove dirt and seals on the surface. After dry cleaning, further impurities may be removed by performing wind sorting, electrostatic separator sorting, metal sensing sorting, or the like.

  There are various cleaning methods such as dry cleaning and wet cleaning. In the present invention, dry cleaning that has the least influence on the environment is employed because water is not used. The dry cleaning apparatus includes means for removing surface deposits by hitting a hammer blade rotating at high speed, means for cleaning by mutual rubbing action between raw materials, and the like, and is not particularly limited.

  And an additive is added to the washed thermoplastic resin material as necessary, and the mixture is heated and kneaded and extruded at 180 to 240 ° C. By passing through a screen having a mesh size of about 30 to 100 during the heat-kneading extrusion, foreign matters such as metal components and silicon larger than the mesh can be further removed.

  In addition, in order to further improve the durability and mechanical properties of recycled materials, crystal nucleating agents, heat stabilizers, light stabilizers, antistatic agents, lubricants, fillers, copper damage prevention can be used in any process during the regeneration process. Additives such as an agent, an antibacterial agent, a colorant, an additive such as an antioxidant, and a resin other than a waste material may be added.

  In addition, it is not limited to resin derived from a refrigerator, The synthetic resin collect | recovered from the shredder dust from other goods, such as an air conditioner and a washing dryer, and the synthetic resin collect | recovered from multiple types of products may be sufficient.

  The reformed thermoplastic resin recycled material can be reused as a home appliance such as an air conditioner or a general resin molded product by performing injection molding.

  The near-infrared identification device 4 can obtain polypropylene (PP) resins having different purities by adjusting the selection sensitivity when discriminating polypropylene. Only synthetic resin materials that completely match the absorption spectrum shape of polypropylene registered in advance can be recognized as polypropylene, but the purity of the recovered polypropylene can be adjusted by adjusting the selection sensitivity and providing a wider spectrum shape to be recognized. Can be reduced, but the recovered amount of polypropylene can be increased.

Since the mixed material described in the first embodiment is waste material from a used refrigerator, in addition to polypropylene resin, polystyrene resin (PS), acrylonitrile-butadiene-styrene copolymer (ABS) resin, polyvinyl chloride (PVC) resin etc. are mainly contained. When polypropylene regenerated using a near-infrared sorting system is analyzed, the most abundant resin is polystyrene. Therefore, one of the biggest problems of the low purity recycled polypropylene resin is to suppress deterioration of physical properties by realizing compatibility between the polypropylene resin and the polystyrene resin.
(Embodiment 1)
The evaluation and physical property measurements used in the following examples and comparative examples were measured according to the tensile test defined in JIS K6251.

In addition, Examples 1 to 3 and Comparative Example 1 are heats made of polypropylene resin having a purity of about 70% by weight, which is collected and collected by using a near-infrared sorting system from the waste thermoplastic resin collected from the refrigerator as a waste home appliance. A plastic recycled resin material, which was kneaded while being heated at 180 to 220 ° C. by a twin-screw extruder to produce multipurpose pellets. A sheet having a thickness of 0.1 to 0.2 mm is formed from this multipurpose pellet with a 180 to 190 ° C. press, and a dumbbell-shaped No. 1 test piece having a shape defined in JIS K6251 is prepared to evaluate tensile elongation at break. The physical properties were evaluated.
Example 1
SEBS (styrene-ethylene / butylene-styrene block copolymer) -based compatibilizer (manufactured by JSR) was added at 10% by weight, and physical properties were evaluated.
(Example 2)
PP-g-AS (polypropylene-acrylonitrile styrene graft copolymer) -based compatibilizer (manufactured by NOF Corporation) was added at 10% by weight, and physical properties were evaluated.
Example 3
Maleic anhydride grafted polymer-based compatibilizer (manufactured by Dupont) was added at 10% by weight, and physical properties were evaluated.

(Comparative Example 1)
The additive was not added and the physical properties were evaluated.

  The results are shown in FIG. The percentage in the figure indicates a numerical value when the comparative example is 100%.

  One of the properties that is most markedly reduced by the presence of incompatible resins is tensile elongation at break. Therefore, the tensile elongation at break of the sheet dumbbell specimen was examined as a measure of physical properties.

  In Comparative Example 1, the tensile elongation at break is reduced due to the decrease in the purity of polypropylene in the recycled resin. This means that the crystalline polystyrene resin has poor compatibility with the polypropylene resin and cannot be uniformly dispersed in the matrix, resulting in a decrease in physical properties.

  In Examples 1, 2, and 3, it turns out that the physical property improved by adding a compatibilizer.

  In Example 1, a SEBS-based compatibilizer manufactured by JSR was used, and a physical property recovery about 5.3 times that of Comparative Example 1 in which no compatibilizer was added was observed.

  In Embodiment 1 of the present invention, SEBS is used as the thermoplastic elastomer, but SEPS (styrene-ethylene / propylene-styrene block copolymer) and SBS (styrene-butylene-styrene block copolymer) are also used. ), SSEBS (polypropylene / hydrogenated polystyrene-poly (styrene / butadiene) -polystyrene) and the like.

  These are not necessarily used alone. For example, SEBS, SEPS, and SSEBS may be used in combination, or even SEBS may be used by adding a plurality of types of SEBS having different styrene contents.

  In Example 2, a PP-g-AS compatibilizer made by NOF was used, and about 1.6 times physical property recovery was seen compared to Comparative Example 1 in which no compatibilizer was added. .

  In Example 3, a maleic anhydride grafted polymer-based compatibilizer was used, and a physical property recovery about twice that of Comparative Example 1 in which no compatibilizer was added was observed.

  In Example 2 and Example 3, although not as remarkable as Example 1, it was confirmed that the physical properties were improved 1.6 times or more as compared with Comparative Example 1. These are not necessarily used alone, and may be used in combination or in combination with the above thermoplastic elastomer.

  Next, in order to observe the dispersibility of the polypropylene resin and the polystyrene resin in the recycled resin and the influence on the dispersibility due to the addition of the compatibilizer, the pellet-shaped molded products prepared in Example 1 and Comparative Example 1 were used. A sample for observation with a transmission electron microscope (TEM) was prepared by staining with osmium oxide and ruthenium tetroxide and observed. The inside of the multipurpose pellet which can exclude the influence of the flow at the time of kneading | mixing was cut out and it was set as the sample for observation.

  The results are shown in FIG. In the case where the compatibilizing agent of Comparative Example 1 is not added, the polystyrene dispersed phase remains large, which is the reason why the physical properties are extremely lowered. In the case of adding SEBS-based compatibilizing agent (manufactured by JSR) of Example 1 at 10% by weight, the interfacial tension becomes small due to the effect of the compatibilizing agent covering the periphery of polystyrene, so the average dispersion diameter becomes small. From the uniform dispersion, it was confirmed that polystyrene present as a foreign substance in polypropylene was compatible.

  Moreover, the purity of the polypropylene resin regenerated using the near infrared sorting system is 99.9% at the maximum. Even in this case, by adding 0.03% by weight of a compatibilizing agent, SEBS-based compatibilizing agent (manufactured by JSR) is added by 10% by weight to a thermoplastic recycled resin material made of polypropylene resin having a purity of about 70% by weight. The compatibilizing effect similar to that when added is obtained.

  In the regeneration step, a mechanism for determining the amount and type of the compatibilizer to be added may be provided in accordance with the sorting sensitivity when sorting polypropylene.

  In this embodiment, a thermoplastic recycled resin material made of polypropylene resin having a purity of about 70% by weight was used, but the purity of the polypropylene resin is the recovery rate of the recycled resin material and the cost required for the compatibilizer to be added. Can be selected.

According to the thermoplastic resin recycled material according to the present invention, as described above, it is possible to eliminate the influence of the incompatible different resin contained in the material using the recycled material and the molded product thereof. It can be applied to the recycling of materials as a material that can be recycled into another molded product at the same time as increasing the recycling rate of household appliances and general waste.

DESCRIPTION OF SYMBOLS 1 Conveying device 2 Thermoplastic resin material 3 Other synthetic resin materials 4 Near infrared identification device 5 Discharge port 6 Separation board

Claims (6)

At least one of thermoplastic elastomer, graft copolymer having polyolefin as a main chain, and maleic anhydride grafted polymer is added to a polypropylene resin material selected from a waste thermoplastic resin mixed with a plurality of substances using a near infrared ray selection system. A thermoplastic recycled resin material obtained by adding various types of additives and heating and kneading. 2. The thermoplastic recycled resin material according to claim 1, wherein the polypropylene resin material contains at least one of polystyrene resin, acrylonitrile / butadiene / styrene resin, and polyvinyl chloride resin. 3. The thermoplastic recycled resin material according to claim 1 or 2, wherein the polypropylene resin material is contained in an amount of 70% by weight or more. The thermoplastic recycled resin material according to any one of claims 1 to 3, wherein the amount of the thermoplastic elastomer added is 0.03 to 10% by weight. The thermoplastic recycled resin material according to any one of claims 1 to 4, wherein the thermoplastic resin waste material according to claim 1 is derived from home appliances. The molded object shape | molded using the thermoplastic recycled resin material of any one of Claim 1 to 5.

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