KR20030002657A - Method for recycling mixed waste plastics using inorganic filler - Google Patents

Abstract

PURPOSE: Provided is a reproduction process of complex waste plastics using an inorganic filler which adds the inorganic filler to the complex waste plastics so that it improves physical property of the complex waste plastics. CONSTITUTION: The reproduction process of the complex waste plastics using the inorganic filler comprises the steps of: (i) crushing the complex waste plastics; (ii) drying red mud or activated carbon as the inorganic filler at 100-200deg.C and producing as fine powder; (iii) mixing a compatibilizer and the powdered inorganic filler with the powdered waste plastics wherein 10-40wt% of mixture is included at a weight ratio; and (iv) fusing the mixture at 240-260deg.C and molding.

Description

Method for recycling mixed waste plastics using inorganic filler

The present invention relates to a method for regenerating mixed waste plastics using inorganic fillers, and more particularly, to a method for regenerating mixed waste plastics by adding an inorganic filler of red mud or activated carbon.

Waste plastics have recently emerged as a global environmental pollutant. General methods of waste plastics include landfilling and incineration. However, except for biodegradable plastics, most plastics are not decomposed and bulky due to their weight, which makes it difficult to further construct landfills. Thus, waste plastic treatment by landfilling brings many problems. On the other hand, in the case of incineration treatment, toxic gases such as dioxins are generated and energy loss is large, so a lot of facility investment is required to be an efficient alternative. Therefore, the proper recovery and recycling of waste plastics has emerged as the best solution in terms of environmental protection and reclaiming of useful resources.

As a method of recycling waste plastics, a melt molding method, an extrusion process, a compression process, a foaming process, and the like are known, and all of them are molded after heating the waste plastic. As another example of recycling waste plastics, Japanese Unexamined Patent Publication No. 52-23179 discloses waste plastics such as polyvinyl chloride and polyethylene, and heats and dissolves them together with a compatibilizer to pelletize the pellets. Disclosed is a method of mixing and dissolving pure plastic, such as polypropylene and polyethylene, in a stepwise manner at the same dissolution temperature thereof, followed by injection or extrusion molding into a tubular or plate shape.

However, in general, waste plastics have a problem in regeneration by these methods because at least 10 kinds of plastics having different physical properties exist. That is, it is impossible to mix and dissolve some plastics in mixed waste plastics step by step with a compatibilizer, and there is a problem that a lot of manpower and cost are required to separate and recycle them by type.

In addition, when recycling the mixed waste plastic, there is a problem that each type of plastic components are mixed, so the physical properties are sharply lowered, the quality of the final product is very poor.

The present invention has been made to solve the problems of the prior art as described above to produce a high-quality recycled mixed waste plastic with significantly improved physical properties by adding a compatibilizer and a specific inorganic material to the waste plastic is mixed with various components of the plastic The goal is to provide a way to do it.

Another object of the present invention is to provide an effective recycling method of waste minerals by using red mud or waste activated carbon, which is a disposed inorganic material, to recycle mixed waste plastics.

1 is an electron micrograph (SEM) of a mixed waste plastic recycled according to a conventional method for recycling mixed waste plastic.

2 is an electron micrograph of mixed waste plastic regenerated by adding a compatibilizer.

3 is an electron micrograph of mixed waste plastic regenerated by adding red mud according to an embodiment of the present invention.

4 is an electron micrograph of mixed waste plastic regenerated by addition of activated carbon according to another embodiment of the present invention.

Waste plastic recycling method using the inorganic filler of the present invention for achieving the above object is a step of pulverizing the mixed waste plastic, drying the red mud or activated carbon at a temperature of 100 ~ 200 ℃ as an inorganic filler to a fine powder, Mixing the pulverized waste plastic with a compatibilizer and the powdered inorganic filler to 10 to 40% by weight, and melting and molding the mixture at a temperature of 240 to 260 ° C.

The mixed waste plastic is at least in the group consisting of low density polyethylene (LDPE), high density polyethylene (HDPE), polypropylene (PP), polystyrene (PS), polyester (PET) or acrylonitrile-butadiene-styrene copolymer (ABS). It is preferable to mix two or more.

The content of the red mud is preferably 5 to 25% by weight based on the mixed waste plastic, and the content of the activated carbon is 5 to 15% by weight based on the mixed waste plastic.

The compatibilizer is preferably a mixture of ethylene propylene rubber (EPR) and styrene-butadiene-styrene block copolymer (SBS).

It is preferable that the content of the said compatibilizer is 5-20 weight%.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

The present invention relates to a method for regenerating mixed waste plastic such that the tensile strength and impact resistance are greatly improved by melt-mixing an inorganic filler, which is an amount of red mud or activated carbon, with a compatibilizer during regeneration of the mixed waste plastic.

The mixed waste plastics used in the present invention are low density polyethylene, high density polyethylene, polypropylene, polystyrene, polyester and acrylonitrile, which are the main components of industrial waste plastics generated during manufacturing processes in the industry and general life waste plastics generated in general life. Butadiene-styrene copolymers, etc. may be used, and in the present invention, such waste plastics may be 25% by weight of low density polyethylene, 25% by weight of high density polyethylene, 25% by weight of polypropylene, and 20% of polystyrene based on regional and seasonal statistics. % And 5% by weight of acrylonitrile-butadiene-styrene copolymer.

In the present invention, the physical properties of the mixed waste plastic can be greatly improved by mixing the inorganic filler.

The inorganic filler used in the present invention may be red mud or activated carbon, and red mud is a residue obtained by collecting alumina from the bauxite in smelting of aluminum as an oxide of Fe ₂ O ₃ , TiO ₂ , SiO ₂ , Al ₂ O _It contains a large amount of ₃ and is red fine powder mud. Activated carbon is generally used, and waste activated carbon after use can be used.

In the present invention, the inorganic filler is preferably dried before being added to the mixed waste plastic to remove moisture, and then pulverized into fine particles using a grinder. If moisture is not removed properly, bubbles may be formed during molding, thereby deteriorating physical properties.

The pulverized inorganic filler may be added to the mixed waste plastic together with a compatibilizer, and then melt mixed and molded at 240 to 260 ° C.

The content of red mud is preferably 5 to 25% by weight based on the mixed waste plastic and 5 to 15% by weight of activated carbon. When both red mud and activated carbon are used at less than 5% by weight, the properties of the resultant mixed waste plastic are improved. The effect is weak, and when used in more than 25% by weight, 15% by weight, respectively, the physical properties are lowered.

Compatibilizers used in the present invention include ethylene propylene rubber (EPR), ethylene propylene diene rubber (EPDR), styrene-ethylene-butylene-styrene block copolymer (SEBS) and maleic anhydride modified styrene-ethylene-butylene-styrene One or more commercially available products such as block copolymers (SEBS-MA) and styrene-butadiene-styrene block copolymers (SBS) may be mixed and used, and ethylene propylene rubber and styrene-butadiene-styrene block copolymers may be mixed. Most preferably.

The content of the compatibilizer is preferably 5 to 20% by weight with respect to the mixed waste plastics. When the content of the compatibilizer is less than 5% by weight, it is not effective to improve the physical properties of the produced mixed waste plastics. Not economical

In the present invention, the mixed waste plastic recycled by mixing the inorganic filler and the compatibilizer is melt-extruded to obtain pellets and then molded into a plate shape to measure physical properties such as tensile strength, tensile modulus, elongation and impact resistance. .

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples are merely illustrative and should not be understood as limiting the scope of the invention.

Example 1

85 g of waste plastics mixed with 25% by weight of low density polyethylene, 25% by weight of high density polyethylene, 25% by weight of polypropylene, 20% by weight of polystyrene and 5% by weight of acrylonitrile-butadiene-styrene copolymer are 3 to 5 mm Trituration with. 5 g of red mud was dried in an oven at 120 ° C. to remove moisture, and then fine powder was added to the mixed waste plastic with 5 g of ethylene propylene rubber and 5 g of styrene-butadiene-styrene block copolymer as a compatibilizer. The mixture was introduced into an extruder and melt-extruded at 240 ° C. to prepare pellets, which were then compression molded into plates.

Example 2

A molded article was prepared in the same manner as in Example 1, except that 80 g of mixed waste plastic, 10 g of ethylene propylene rubber as a compatibilizer, and 5 g of styrene-butadiene-styrene block copolymer were used.

Example 3

A molded article was prepared in the same manner as in Example 1, except that 80 g of mixed waste plastic, 5 g of ethylene propylene rubber, and 10 g of styrene-butadiene-styrene block copolymer were used as a compatibilizer.

Example 4

A molded article was prepared in the same manner as in Example 1, except that 5 g of activated carbon was used as an inorganic filler, 85 g of mixed waste plastic, 5 g of ethylene propylene rubber as a compatibilizer, and 5 g of styrene-butadiene-styrene block copolymer.

Example 5

A molded article was prepared in the same manner as in Example 4, except that 80 g of mixed waste plastic, 10 g of ethylene propylene rubber, and 5 g of styrene-butadiene-styrene block copolymer were used as a compatibilizer.

Example 6

A molded article was prepared in the same manner as in Example 4, except that 80 g of mixed waste plastic, 5 g of ethylene propylene rubber, and 10 g of styrene-butadiene-styrene block copolymer were used as a compatibilizer.

Tensile test and impact resistance test specimens were prepared from the regenerated mixed waste plastics prepared, and the tensile strength, tensile modulus, and elongation were measured using a universal testing machine (LR-10K UTM), and the impact strength was measured using an impact tester (JS-303). The measurement is shown in Table 1 below.

Table 1

Tensile Strength (N / ㎡) Absorption Energy (N-mm) Tensile Modulus (N / mm2) % Elongation Impact Strength (kg-cm / cm) Example 1 13.78 1568 517.7 9.74 7.59 2 10.77 869.3 428.3 7.25 9.14 3 11.22 1489 435.2 10.58 9.07 4 13.53 1350 525.5 8.48 7.94 5 11.67 1210 448.2 9.16 11.67 6 12.03 2031 424.6 12.14 10.50

Comparative Example 1

100 g of waste plastic mixed with 25% by weight of low density polyethylene, 25% by weight of high density polyethylene, 25% by weight of polypropylene, 20% by weight of polystyrene, and 5% by weight of acrylonitrile-butadiene-styrene copolymer, using a mill Trituration with. After mixing the pulverized mixed waste plastic homogeneously, the mixture was put into an extruder and melt-extruded at 240 ℃ to prepare a pellet and compression molded into a plate shape.

Comparative Example 2

A molded article was prepared in the same manner as in Comparative Example 1, except that 90 g of mixed waste plastic, 5 g of ethylene propylene rubber, and 5 g of styrene-butadiene-styrene block copolymer were used as a compatibilizer.

Comparative Example 3

80 g of mixed waste plastic, 5 g of ethylene propylene rubber as a compatibilizer, 5 g of styrene-butadiene-styrene block copolymer, 5 g of red mud and 5 g of activated carbon were simultaneously mixed as an inorganic filler, and then a molded product was prepared in the same manner as in Example 1.

The physical properties of the produced recycled mixed waste plastics were measured in the same manner as in Example and shown in Table 2 below.

Table 2

Tensile Strength (N / ㎡) Absorption Energy (N-mm) Tensile Modulus (N / mm2) % Deformation Impact Strength (kg-cm / cm) Comparative Example 1 8.37 113.0 660.4 1.57 1.57 2 8.80 220.6 742.8 2.17 2.97 3 11.46 1103 486.9 7.56 7.10

As shown in the above Examples and Comparative Examples, when the mixed waste plastic was heated and melted by the regeneration method of the conventional mixed waste plastic (Comparative Example 1), the impact resistance of the mixed waste plastic was very low (1.57 kg-cm). / Cm), when the compatibilizer was added to improve this (Comparative Example 2), both the tensile strength and the impact resistance were improved (8.80 N / mm 2, 2.97 kg-cm / cm, respectively). However, when red mud was added as an inorganic filler to the compatibilizer according to the embodiment of the present invention and regenerated (Example 1-3), physical properties such as tensile strength and impact strength were rapidly improved by 7 to 8 times or more. It can be seen that the same result is obtained even when added (Example 4-6).

However, when the red mud and activated carbon are used together as the inorganic filler (Comparative Example 3), it can be seen that the physical properties are deteriorated.

Electron micrographs (SEM) were taken to compare the particle shapes of the mixed waste plastics recycled according to the Examples and Comparative Examples of the present invention and are shown in FIGS.

FIG. 1 shows the case of the conventional mixed waste plastic recycling method (Comparative Example 1), and FIG. 2 shows the case of adding a compatibilizer (Comparative Example 2). FIG. 3 shows the case of adding red mud according to an embodiment of the present invention (Example 1), and FIG. 4 shows the case of adding activated carbon according to another embodiment of the present invention (Example 4).

As can be seen in Figures 3 and 4, when the inorganic filler is added, the phase separation between the particles of the mixed waste plastics is significantly reduced compared to the case where the inorganic filler is not added (Figs. 1 and 2), and the particle shape is very uniform. It stabilized. It can be seen that the physical properties of the mixed waste plastic are drastically improved by the synergistic effect between the inorganic filler and the compatibilizer.

Therefore, according to the present invention, by adding an inorganic filler of red mud or activated carbon together with a compatibilizer, the phase separation of the mixed waste plastics is significantly reduced, so that recycled mixed waste plastics having greatly improved physical properties can be produced.

The present invention relates to a method for regenerating mixed waste activated carbon by adding an inorganic filler, and by adding an inorganic filler together with a compatibilizer, the physical properties can be greatly improved by mixing the mixed waste plastic having various components mixed therein.

According to the present invention, the use of red mud and activated carbon, which are left as waste minerals in the recycling of mixed waste plastics, is not only very useful in terms of recycling resources, but also prevents other environmental problems caused by waste.

In addition, the use of waste can economically recycle the mixed waste plastics, and the effect of cost reduction is also great.

Although the present invention has been described in detail only in the described embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible within the spirit of the present invention, and such modifications and variations belong to the appended claims.

Claims (6)

Pulverizing the mixed waste plastic; Drying the red mud or activated carbon at a temperature of 100-200 ° C. as an inorganic filler and then making it into a fine powder; Mixing the pulverized waste plastic with a compatibilizer and the powdered inorganic filler to 10 to 40% by weight; And Melting and molding the mixture at a temperature of 240 to 260 ° C; Mixed waste plastic recycling method using an inorganic filler comprising a. The method of claim 1, The mixed waste plastic is at least in the group consisting of low density polyethylene (LDPE), high density polyethylene (HDPE), polypropylene (PP), polystyrene (PS), polyester (PET) or acrylonitrile-butadiene-styrene copolymer (ABS). Mixed waste plastic recycling method using the inorganic filler, characterized in that two or more are mixed. The method of claim 1, The waste plastic recycling method using the inorganic filler, characterized in that the content of the red mud is 5 to 25% by weight based on the mixed waste plastic. The method of claim 1, Mixed waste plastic recycling method using the inorganic filler, characterized in that the content of the activated carbon is 5 to 15% by weight based on the mixed waste plastic. The method of claim 1, The compatibilizing agent is a mixed waste plastic recycling method using the inorganic filler, characterized in that the ethylene propylene rubber (EPR) and styrene-butadiene-styrene block copolymer (SBS). The method of claim 1, Mixed waste plastic recycling method using the inorganic filler, characterized in that the content of the compatibilizer is 5 to 20% by weight.