WO2023171862A1 - Method for regenerating everyday film sheet-shaped waste plastic - Google Patents

Abstract

The present invention relates to a method for regenerating everyday film sheet-shaped waste plastic and, specifically, comprises a step of injecting washed and dried waste plastic into a molding machine and temporarily molding same into a brittle state, and thus can facilitate process handling and quantification of waste plastic and can homogenize regenerated plastic. In addition, chlorine wash for deodorization is further included in a washing step so that the application of regenerated plastic can be further expanded to real life.

Description

Film sheet type waste plastic recycling method

The present invention relates to a method for recycling film sheet-type waste plastic from living environments, and in particular, to a method for recycling randomly collected composite waste plastic without undergoing material selection.

In the present invention, 'film sheet-type household waste plastic' refers to film-type and sheet-type plastics that are used and discarded for the purchase of goods or convenience of life in the real life of the general consumer, regardless of the specific material, and are commonly found in the surrounding environment. It should be understood to include all film-type and sheet-type plastics discarded after being used for commercial, industrial, and agricultural purposes. Hereinafter, for convenience, this will be referred to as ‘waste plastic’.

In general, waste plastic is made into recycled plastic and used through the following processes: collection/sorting, crushing/crushing, washing/drying, and melting/extrusion. In order for the waste plastic collected in this way to be used as a recycled raw material, it must first be sorted. If it is melted without being sorted, the melting point is different for each material, so for example, if the temperature is set to a high melting point, it must be melted to a low melting point. Materials with a high melting point cannot be used because they will be carbonized, and conversely, if the temperature is set to a low melting point, materials with a high melting point cannot be used because they will be processed without melting.

In addition, these different materials are not compatible with each other and the affinity between the resin polymers is low, so not only do they have poor physical properties when mixed, but they are also weak against impact, making it difficult to use them as recycled raw materials.

In particular, in the case of household waste plastic, statistics show that more than 90% of it is recycled, but in reality, not only is the rate of being made into SRF (Solid Refuse Fuel) and incinerated close to 85% of the total, but some of it is also recycled physically. It is only used in some applications such as water control valves, street tree protection pipes, and sewage pipe covers that require little impact or wear resistance.

In the case of randomly collected household waste plastic, it is made up of a combination of various materials such as polyethylene, polypropylene, polystyrene, polyamide, polyester, and polyurethane, and some of them have a multi-layer structure and even contain a printing resin mixture on the surface or aluminum. This is because its use as a recycled raw material is extremely limited because it contains materials that are coated with a thin film layer and are contaminated with food or dirt.

In the end, in order to effectively recycle the collected waste plastic, it must first be sorted by material. However, since this sorting is mechanically impossible, it requires a lot of manpower, money, and time, and is very uneconomical and unreasonable, causing many businesses to give up recycling of household film sheet-type materials.

What has been proposed is the so-called 'commercial chemical filler' disclosed in Patent Registration No. 10-0623157, Patent No. 10-1463400, etc. These patents are about producing a compatible filler for waste plastic recycling by mixing pulverized inorganic mixtures with transition metal additives, and adding and mixing this powder filler to composite waste plastics that have not been collected and sorted. This means that recycled plastic with desired physical properties can be manufactured by melting and extruding the material. After these patents, similar fillers with the same purpose have been variously proposed in many patents.

It has been confirmed through various experiments or tests that these fillers effectively act as compatibilizers in recycling waste plastic.

<Prior art literature>

Korean Patent Publication No. 10-0623157

Korean Patent Publication No. 10-1107584

Korean Patent Publication No. 10-1463400

Korean Patent Publication No. 10-1583305

However, according to the conventional waste plastic recycling technology, regardless of the use of the above filler, dried film-type and sheet-type materials are difficult to handle in process operations such as transport, input, and mixing due to their lightness and dispersibility. On the other hand, there is a problem in that composite waste plastic that has not been sorted is not evenly distributed among the recycled plastics but is lumped together by material - because that is how they are disposed of and collected in the first place.

The invention:

Mainly, providing a waste plastic recycling method that can improve the productivity and physical stability of recycled plastic by facilitating the process handling of composite waste plastic and ensuring homogeneity in recycled plastic;

On the one hand, providing a waste plastic recycling method that allows recycled plastic to be actively used in daily life by removing the bad smell of waste plastic;

For the purpose.

In order to achieve the above object, the present invention proposes a method of producing recycled plastic by pulverizing waste plastic, washing and drying it, adding a compatibilizer in a fixed amount to create recycled raw materials, and extruding the recycled material at high temperature.

Specifically, the present invention relates to a method for recycling film sheet-type waste plastic from living quarters, which method includes:

Cutting and pulverizing film sheet-type household waste plastic;

Washing the pulverized waste plastic and drying it to a moisture content of less than 20%;

Injecting 3 to 8 wt% of a compatibilizer consisting of a mixture of transition metals and inorganic materials with respect to 100 wt% of the dried waste plastic into the hopper of an extruder having a temperature of 210°C or higher;

Obtaining recycled plastic from the extruder;

Includes.

Preferably, the waste plastic input into the extruder hopper is tentatively molded in a brittle state in a molding machine after the drying step. More preferably, the waste plastic recycling method of the present invention includes:

Adding a compatibilizer to the temporarily molded waste plastic and then stirring it to prepare a recycled raw material mixed with the waste plastic from which the temporary mold is dismantled and the compatibilizer;

may further include,

At this time, the recycled raw material is input into the extruder hopper;

It is characterized by .

Specifically, the washing step is:

sequentially including a water washing step and a deodorizing chlorine washing step;

It is characterized by .

Preferably,

The living waste plastics include polyethylene, polypropylene, polystyrene, polyamide and printed film;

The compatibilizer is a powder made of a mixture of an inorganic material and a transition metal or a master batch containing the powder;

It is characterized by .

The pseudo-molded waste plastic is:

It is in the form of a lump in a brittle state, and the lump is preferably in the form of a diameter of 2 cm to 5 cm and a length of 5 cm to 10 cm.

The recycled plastic can be post-processed into pellet form.

According to the present invention, composite waste plastics are recycled through a continuous process of crushing, washing, and drying, then adding a compatibilizer in a fixed amount to create recycled raw materials, and extruding them at high temperature. Therefore, it can facilitate the handling and quantification of waste plastic during the process, and is also effective in terms of homogenization of recycled plastic. In particular, this effect is preferably doubled as the waste plastic undergoes a preforming step.

In a preferred embodiment of the present invention, the composite waste plastic is washed and dried, pre-molded in a temporary brittle state in a molding machine, and then recycled through processes such as transport, mixing of compatibilizer, stirring, disassembly of pre-molding, and extrusion. thus,

It can facilitate the process handling and quantification of waste plastic;

In addition, the physical stability of recycled plastic can be improved by ensuring that it is distributed homogeneously in the recycled plastic;

It has a special effect.

On the other hand, through the chlorine washing, the odor that the recycled raw material may have is removed in advance, so that the recycled plastic can be actively used in daily life;

There is an additional effect.

1 is a flowchart of a waste plastic recycling method according to a preferred embodiment of the present invention.

Figures 2a and 2b are views showing each cutter and shredder.

Figure 3 is a diagram showing a water washing device.

Figure 4 is a diagram showing a molding machine.

Figures 5a and 5b are views showing each powder and masterbatch.

Figure 6 is a view showing an extruder

Figure 7 is a view showing recycled plastic processed into pellet form.

[Explanation of symbols]

S10. How to play

S11. Cutting/crushing stage

S12. Washing step

S13. drying stage

S14. Molding stage

S15. Preparation stage

S16. Extrusion step

10. Cutter

11. Grinder

20. Water washing device

21. Press

22. Waste plastic

30. Molding machine

31. Molding

32. Conveyor

40. Powder

41. Masterbatch

50. Extruder

51. Recycled plastic

52. Pellets

The 'film sheet type waste plastic recycling method' (hereinafter referred to as 'recycling method') of the present invention, which may or may not be described above, will become more clear through the preferred embodiments described below with reference to the accompanying drawings. In Figure 1, symbol 'S10' indicates a playback method according to an embodiment of the present invention, and herein, it will be described in order, with reference to other drawings where necessary.

In the present invention, the living waste plastics include polyethylene (PE), polypropylene (PP), polystyrene (PS), polyamide (PA), polyester (PET), polyurethane (PU), printed film, etc. It should be understood to include all obtainable waste plastic materials, and the subject of the 'recycling method' of the present invention is premised on the fact that these materials are composite waste plastics collected randomly without selection.

[Cutting/Crushing (S11)]

This step is a process of cutting and crushing the collected waste plastic to an appropriate size. Here, cutting and disassembly reduces the volume of the collected waste plastic, facilitates the post-processing process, and contaminates the metal, stones, and dirt contained therein. Substances can be removed primarily. In this process, for example, a typical shearing cutter 10 and a waste vinyl shredder 11 shown in FIGS. 2A and 2B can be used, and the waste plastic is ultimately pulverized into a size of 10 cm to 20 cm in length.

In particular, the above-mentioned metallic contaminants are components that must be removed first when recycling waste plastic. To remove this, a metal separator may be used in advance, but this is not explained separately here.

[Washing (S12)]

This step is a process of removing contaminants by washing the waste plastic cut and pulverized in the previous process (S11) with water. The pulverized waste plastic is washed as it passes through a water tank, and only the washed waste plastic is transferred to the next process, excluding contaminants that settle during washing or waste plastic that contains a large amount of such contaminants. This water washing and water tank can be provided in plurality as needed. Figure 3 illustrates the water washing device 20, where a plurality of rotating presses 21 are installed in a longitudinal water tank so that the waste plastic 22 is pressed against the press, submerged in water, and moved forward while being washed.

At this time, contaminants such as metals that settle to the bottom of the tank or waste plastic containing large amounts of such contaminants will be removed by a separate device.

Although water washing has been described as the washing (S12) step above, a chlorine washing step is preferably further included after the water washing step. Collected household waste plastics are contaminated with various bacteria and bad odors, and when recycled, the bad smell is especially severe in the recycled plastics, making it very difficult to use them as actual household goods. Accordingly, in this embodiment, we attempt to expand the usability of recycled plastic by sterilizing and deodorizing it by washing it with chlorine in advance.

Preferably, chlorine is added and mixed in an amount of 0.4 to 1.0 mg per 1L of water, and at this stage, chlorine cleaning can be performed using a water tank method such as water washing, spraying, or water spraying.

[Drying (S13)]

This step is a process of drying waste plastic containing moisture through a washing step (S12). It would also be possible to dry in a high temperature atmosphere after washing in a general way. However, since there is a possibility that the physical properties of the plastic may be modified, in this embodiment, natural conditions are used in a dry house. At this time, the moisture content of the waste plastic after drying is less than 20%.

[Provisional molding (S14)]

This step is a process of temporarily molding the waste plastic dried through the drying step (S13) into a brittle state. In this process, the waste plastic that is put into the molding machine after drying is compression molded, but is temporarily temporarily molded and discharged in a brittle state that is easily broken by external forces. Figure 4 illustrates the molding machine 30 used in this process and is designed to discharge a brittle molding 31 in the form of a lump with a diameter of 2 cm to 5 cm and a length of 5 cm to 10 cm. At this time, the discharged molding is placed on the lower conveyor 32. It is taken off and transported to the right place.

For reference, if the size of the molded product is larger, not only is it inconvenient to handle and transport, but the process of putting it into the stirrer and stirring it in the subsequent process may not be smooth.

In general, dried film-type or sheet-type materials are difficult to handle in quantitative quantities during work processes such as transport, input, and mixing due to their lightness and dispersibility. Meanwhile, composite waste plastics that have not been sorted are not evenly distributed among the recycled plastics but are grouped together by material. Accordingly, in this embodiment, the waste plastic is temporarily temporarily molded in a brittle state in this process and the temporary mold is easily dismantled in the post-process, thereby making it easier to handle and quantify the waste plastic during the process, and also to measure the waste plastic by material. This ensures homogeneous distribution in the recycled plastic.

[Preparation (S15)]

This step is to prepare recycled raw materials by adding a fixed amount of compatibilizer to the dried or caustic waste plastic in the previous step. In this embodiment, a compatibilizer is added to the brittle molded product and then stirred to prepare a recycled raw material mixed with the dismantled waste plastic and the compatibilizer. In other words, the waste plastic that has been preformed into a brittle lump in the previous process is mixed with a compatibilizer while the preform is broken up by a stirrer in this preparation stage, thereby preparing the recycled raw material. At this time, the stirring process is not necessarily necessary, but is much more advantageous in terms of even mixing and distribution of materials and compatibilizers.

Since the above molded product is in a brittle state that is easily broken by external force, the stirrer does not need to have special power, and a normal rotary stirrer is sufficient. However, a rotating blade-type stirrer can be effectively used to quickly dismantle the molded product and mix the waste plastic material and the compatibilizer.

In this embodiment, it is assumed that the dried waste plastic is temporarily molded and stirred, but the dried waste plastic may be applied as is. The compatibilizer is a filling material that allows various waste plastic materials to melt and combine with each other. Referring to FIG. 5A, it is a material in the form of a powder 40 made of a mixture of an inorganic material and a transition metal. More specifically, the compatibilizer:

minerals containing dolomite, zeolite, and calcium carbonate;

Transition metals including aluminum oxide, iron oxide, titanium oxide, magnesium chloride, and aluminum chloride;

It is composed of.

The compatibilizer is added to the extruder hopper together with the waste plastic in an amount of 3 to 8% by weight based on 100% by weight of the waste plastic dried above.

As described above, the components of the compatibilizer are disclosed in the prior art and are not special to the present invention, nor are the present invention limited to the specific components of the compatibilizer. Meanwhile, powder-type compatibilizers are difficult to handle and quantify. Therefore, as the compatibilizer, as illustrated in FIG. 5B, masterbatch (MB) 41 obtained by mixing the powder and liquid plastic and solidifying it may be used.

[Extrusion (S16)]

This step is a process in which the recycled raw materials prepared above are put into the hopper of an extruder with a temperature of 210°C or higher and extruded to obtain solid recycled plastic. Figure 5 illustrates a plastic extruder 50 used in this process, which is no different from a typical extruder for plastic recycling. Meanwhile, the recycled plastic 51 may be post-processed into a pellet form (see symbol 52 in FIG. 7) that is convenient to transport, use, and handle.

Recycled plastic is obtained through the above steps.

Claims (9)

Cutting and pulverizing film sheet-type household waste plastic; Washing the pulverized waste plastic and drying it to a moisture content of less than 20%; Injecting 3 to 8 wt% of a compatibilizer consisting of a mixture of transition metals and inorganic materials with respect to 100 wt% of the dried waste plastic into the hopper of an extruder having a temperature of 210°C or higher; Obtaining recycled plastic by extruding it in the extruder; Including, A film sheet type waste plastic recycling method characterized by a. According to paragraph 1, A method for recycling waste plastic from the living world in the form of a film sheet, characterized in that the waste plastic fed into the extruder hopper is pre-molded in a brittle state in a molding machine after the drying step. According to paragraph 2, The waste plastic recycling method is: Adding a compatibilizer to the temporarily molded waste plastic and then stirring it to prepare a recycled raw material mixed with the waste plastic from which the temporary mold is dismantled and the compatibilizer; It further includes, Injecting the recycled raw material into the hopper of the extruder; A film sheet type waste plastic recycling method characterized by a. According to any one of claims 1 to 3, A film sheet type recycling method for living waste plastic, characterized in that the living waste plastic includes polyethylene, polypropylene, polystyrene, polyamide, and printed film. According to any one of claims 1 to 3, The washing step is a film sheet type living waste plastic recycling method, characterized in that it sequentially includes a water washing step and a deodorizing chlorine washing step. According to any one of claims 1 to 3, The washing step is a film sheet type living waste plastic recycling method, characterized in that a plurality of rotating presses are installed in a longitudinal water tank so that the waste plastic is pressed by the press and submerged in water to be washed and moved. According to paragraph 2 or 3, A method of recycling film sheet-type living waste plastic, wherein the caustic waste plastic is in the form of a brittle lump. In clause 7, A method of recycling waste plastic from the living world in the form of a film sheet, characterized in that the lump has a diameter of 2 cm to 5 cm and a length of 5 cm to 10 cm. According to paragraph 1, The compatibilizer is a powder made of a mixture of an inorganic material and a transition metal or a master batch solidified by mixing the powder with liquid plastic.

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