KR102372243B1 - Manufacturing method of composite material containing various waste plastics - Google Patents

Abstract

According to the present invention, a method for manufacturing a composite material including various kinds of waste plastics includes: determining an appropriate range of a process by recognizing a size of an extrusion nozzle disposed in an extrusion molding device, a viscosity inside the extrusion nozzle, and a shear rate; improving a shape of a material recycling composition by controlling a temperature, a pressure, and an injection speed; analyzing a process variable condition through analysis of the pressure and the viscosity, which are elements required for a resin physical property measurement system; and performing a compounding process by mixing graphene by using SRF and RDF plastics obtained by mixing recycled PE (LDPE, HDPE), PP, PS, and PET, and materials recycled into waste plastic PE (rPE) and waste plastic PP (rPP). Accordingly, an optimal process condition is provided.

Description

Manufacturing method of composite material containing various waste plastics

The present invention relates to a method for manufacturing a composite material containing multiple types of waste plastics, and through thermal analysis, the temperature and pressure conditions necessary for the recycling process of materials are secured according to different materials and viscosities, etc., thereby improving the process through analysis of the properties of recycled raw materials it's about the room.

Plastics enrich our daily life with excellent processability, physical properties and low prices, but vinyl, styrofoam, and plastic containers are not properly separated, collected and recycled, and environmental pollution problems occur due to incineration or landfill.

The methods of recycling waste plastics can be broadly divided into 'material recycling', 'chemical recycling', and 'thermal recycling'. It is a technology that recycles plastics that can be reused through processes such as crushing and mixing.

Regarding 'material recycling', waste plastics, which are mainly generated in daily life, go through a recycling process to make them into recycled raw materials through material selection and foreign material removal process. Various mechanical classification methods are being developed. The waste plastic pieces that have undergone material selection and cleaning processes are made into pellets through a regenerated extruder and used as recyclable materials.

'Chemical recycling' is a method of recycling plastics as raw materials by changing the chemical structure itself, does not require advanced separation by type, is not very sensitive to polluted waste, and has the advantage of being more advantageous than the material recycling process in terms of energy consumption. It is mainly achieved through pyrolysis and chemical reaction processes.

'Thermal recycling' refers to a technology that efficiently converts waste plastics into thermal energy through an eco-friendly process as a thermal energy recovery method.

Plastic waste has a high calorific value and can be converted into fuel because the raw material is petroleum. The technologies for converting waste plastic into fuel include 'RDF (Refuse Derived Fuel)', 'SRF (Solid Refuse Fuel)' and 'RPF (Refuse Plastic Fuel)'. there is. RDF, SRF, and RPF are all new and renewable energy manufactured by selecting combustibles from waste, but there is a difference in quality because RDF uses general household waste and RPF uses industrial waste such as plastic or wood as raw materials. will come out

The most difficult problem in the production of recycled plastics is that not only the same type of plastic is collected during collection, but heterogeneous plastics are mixed and collected.

Meanwhile, at present, the process cycle is performed assuming the state of the collected plastic to be inputted as a specific condition. In the case of the quality of recycled plastic produced through this process, it is difficult to immediately determine the quality, and if a problem occurs after delivery to the consumer, it is discarded or The return cycle repeats itself.

In consideration of the above, there is a need for a process optimization technology that can detect changes in the quality of plastics manufactured during the production of recycled composites and take immediate action.

As a document providing a waste plastic treatment method and apparatus capable of environmentally friendly treatment of waste plastics and recovering energy and inorganic substances, reference may be made to Patent Registration No. 10-0981851.

The present invention identifies process improvement factors through physical property analysis of recycled raw materials to be input, identifies process optimal conditions, and secures temperature and pressure conditions necessary for the recycling process of materials according to different materials and viscosities through thermal analysis. It relates to a method for improving a manufacturing method of a composite material containing a variety of waste plastics.

The method for manufacturing a composite material containing multiple types of waste plastics according to the present invention for achieving the above object is a step of determining the appropriate range of the process by identifying the size of the extrusion nozzle disposed in the extrusion machine, the viscosity and the shear rate in the extrusion nozzle ; improving the shape of the material recycling composition through temperature, pressure, and injection speed control; and analyzing the process variable conditions through pressure and viscosity analysis, which are elements required for the resin property measurement system.

The method uses recycled PE (LDPE, HDPE), PP, PS, and PET mixed SRF and RDF plastics, and materials recycled as waste plastics PE (rPE) and waste plastics PP (rPP) to mix graphene It may be preferable to further include a compounding process step.

According to the present invention, it may be desirable to optimize the temperature, pressure and speed conditions in order to keep the quality change in the mixing and injection process small according to the dissimilar material ratio.

As described above, the present invention analyzes raw material properties by identifying process improvement factors through physical property analysis on waste plastics, a recycled raw material, and provides experimentally established optimal conditions for the process.

In the case of an extruder or an extruder having a structure similar to a capillary viscometer in order to grasp the physical properties of the raw material, it is possible to grasp the change of the internal physical properties by a simple measurement principle.

In addition, the appropriate size of the extrusion nozzle constituting the extruder and the viscosity and shear rate in the extrusion nozzle are identified, and the appropriate range of the process is determined.

The present invention is to improve the shape of a material recycling composition through temperature, pressure, and injection speed control for the supplied waste plastic, and analyzes process variable conditions through pressure and viscosity analysis, which are elements required for a resin property measurement system, and injection /In the press process, it optimizes the temperature, pressure, and speed conditions required for molding each material and provides the established process optimum conditions by analyzing the correlation with the raw material properties.

Figure 1 shows that in the case of an extruder or extruder having a structure similar to that of a capillary viscometer, changes in internal physical properties are grasped by a simple measurement principle.
2 shows the results of thermogravimetric analysis (TGA) of waste plastic, which is a recycled raw material.
3 shows a comparison of flowability and viscosity through melt index (MI) measurement results.
4 shows a graph of viscosity according to shear rate for SRF, rPP, rPE and MR.
Figure 5 shows the srf and mr main recycled plastic content ratio (relative comparison).
6 shows the shear rate generated inside the nozzle according to the inner nozzle diameter of the extrusion nozzle.
7 shows a graph of the extrusion pressure according to the extrusion speed.
8 is a graph showing the viscosity according to the shear rate in various temperature states.
9 shows the tensile strength changes for SRF, rPP, rPE and SRF + graphene.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only these embodiments allow the disclosure of the present invention to be complete, and the scope of the invention to those of ordinary skill in the art It is provided for complete information. In the drawings, like reference numerals refer to like elements.

Waste plastics used in the present invention collectively refer to recycled plastics using packaging plastics discharged from industry and life, and SRF is waste using synthetic resin single and composite film or sheet-type packaging materials and their parts (eggs, labels, miscellaneous materials, etc.) specified as plastic.

The method for manufacturing a composite material containing multiple types of waste plastics according to the present invention comprises: determining the appropriate range of the process by identifying the size of the extrusion nozzle disposed in the extrusion machine, the viscosity and shear rate in the extrusion nozzle; improving the shape of the material recycling composition through temperature, pressure, and injection speed control; and analyzing the process variable conditions through pressure and viscosity analysis, which are elements required for the resin property measurement system.

In addition, the present invention provides recycled PE (LDPE, HDPE), PP, PS, PET mixed SRF and RDF plastics, and recycled materials as waste plastics PE (rPE) and waste plastics PP (rPP) (often a single material). It further includes a compounding process step of mixing graphene by utilizing it.

Through this, a graphene composite material with enhanced tensile strength is realized.

Graphene is mixed with 1 wt% to 10 wt%.

1 shows that the change of internal physical properties is grasped by a simple measurement principle in the case of an extruder or an extruder having a structure similar to that of a capillary viscometer.

Referring to FIG. 1 , in the case of an extruder or an extruder having a structure similar to a capillary viscometer in order to standardize raw material properties and improve reliability, changes in internal physical properties can be identified by a simple measurement principle.

Capillary viscometer and extruder have structural similarity, and by using this similarity, the quality change of the molded article of the extruder can be measured.

That is, process monitoring is carried out by identifying the appropriate extrusion nozzle and viscosity and shear rate in the nozzle. Specifically, the raw materials are analyzed and classified according to the melt index and pressure using the formula for calculating the viscosity in the extruder using a capillary viscometer and a similar structure.

For the extrusion nozzle, 0.5mm ~ 2.0mm is applied to calculate the shear rate that occurs inside the nozzle, and 1.0mm, which is the most commonly used and shows an appropriate shear rate, is used. measure

2 shows the results of thermogravimetric analysis of waste plastics, which are recycled raw materials.

rPE requires a process pressure of 190 ℃ and 5 kgf or more, and it is judged that a process below 230 ℃ for rPP is suitable.

When multiple plastics are mixed, higher processing temperature and pressure are required.

Both rPE and rPP require a high process temperature by mixing 2~5 wt% of different materials.

Depending on the dissimilar material ratio, it optimizes high temperature, pressure and speed conditions to keep quality variations small in the mixing and injection process.

3 shows a comparison of flowability and viscosity through the melt index (MI) measurement results.

Melt index (MI) measurement is carried out by measuring process variables for flow viscosity according to temperature for each material.

Specifically, the unit of measurement is the amount of a resin that is weighed out by temperature in 10 minutes.

Through this result, it is judged whether the melt fluidity is excellent, the moldability is excellent, and the surface gloss is excellent. On the other hand, when the MI is low, it is judged that the strength, elongation, impact resistance, and abrasion resistance are lowered.

When processing SRF material into fine powder, the flowability is significantly improved by more than 10 times even at the same temperature and pressure.

It shows that energy efficiency and CO2 emission reduction are possible through optimization of processing/molding process conditions according to specific regional materials.

According to the MI value, the product characteristics can be improved. Specifically, 0.5 shows microformed products, 1.5 shows sheets and rods, and 2 or more shows simple bulk.

As a result, molding conditions such as temperature and pressure, which are process conditions according to each SRF material, are improved.

Figure 5 shows the srf and mr main recycled plastic content ratio (relative comparison).

Specifically, the relative content ratio according to the type of mixed material waste plastic is calculated through thermal analysis and chemical analysis.

6 shows the shear rate generated inside the nozzle according to the inner nozzle diameter of the extrusion nozzle.

Specifically, the viscosity and shear rate in the nozzle under the proper extrusion nozzle size and process condition are identified, and the process monitoring and system are titrated.

The shear rate occurring inside the nozzle is calculated for each nozzle size currently used (0.5mm, 1.0mm, 1.5mm, 2.0mm), and a nozzle with a nozzle diameter of 1mm, which is the most used as a verification model, is used.

In the present invention, both rPP and rPE measure the pressure in the nozzle according to the injection rate and the viscosity according to the shear rate in the temperature range of 200 ° C to 260 ° C. Analyze process conditions.

7 shows a graph of the extrusion pressure according to the extrusion speed.

As a result of the SRF, looking at the graph of the extrusion pressure according to the extrusion speed, it can be seen that the extrusion pressure increases as the extrusion temperature and extrusion speed increase.

Specifically, the extrusion pressure and extrusion speed at each temperature condition were (a) 5 mm/s, (b) 10 mm/s, (c) 30 mm/s, (d) 60 mm/s (e) 100 mm Shows the equivalent of /s .

8 is a graph showing the viscosity according to the shear rate in various temperature states.

As a result of the SRF, looking at the viscosity graph according to the shear rate, it can be seen that the viscosity decreases as the extrusion temperature and shear rate increase.

Referring to FIGS. 7 and 8 , the pressure and viscosity according to the speed were analyzed as above for SRF. The temperature and injection rate can be determined by comparing the viscosity, shear rate, and nozzle pressure measured according to the shape of the molded product (micro-molding, simple shape, bulk shape).

In the case of SRF (PS 5%, PP 11%, PE 83% relative ratio), in the case of a bulk shape or a simple shape, the process of molding with an injection speed of several seconds (1-10 sec) at a temperature of 200℃ ~ 230℃ is optimal, For fine molding beyond that, a temperature of 260°C is required, but the effect of reducing the viscosity (increasing flowability) by mixing different materials may not be so great.

9 shows the tensile strength changes for SRF, rPP, rPE and SRF + graphene.

The present invention is to improve the shape of a material recycling composition through temperature, pressure, and injection speed control for the supplied waste plastic, and analyzes process variable conditions through pressure and viscosity analysis, which are elements required for a resin property measurement system, and injection /In the press process, it optimizes the temperature, pressure, and speed conditions required for molding each material and provides the established process optimum conditions by analyzing the correlation with the raw material properties.

The above description is merely illustrative of the technical spirit of the present invention, and various modifications and variations will be possible without departing from the essential characteristics of the present invention by those skilled in the art to which the present invention pertains. Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. The protection scope of the present invention should be construed by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

Claims (3)

Determining the appropriate range of the process by identifying the shear rate generated inside the compression nozzle according to the size of the extrusion nozzle disposed in the extrusion molding machine, the viscosity in the extrusion nozzle, and the inner diameter of the extrusion nozzle;
performing temperature, pressure, and injection speed control;
Analyzing pressure and viscosity, which are process variables as elements necessary for a resin property measurement system; and
1 wt% ~ 10% of graphene by using recycled materials from recycled PE (LDPE, HDPE), PP, PS, and PET mixed SRF and RDF plastics, waste plastics PE (rPE), and waste plastics PP (rPP) The step of mixing by wt%; further comprising,
The size of the extrusion nozzle uses a nozzle having a diameter of 1 mm,
The SRF is characterized in that molding is carried out at a temperature of 200 ° C to 230 ° C and an injection speed of 1 to 10 sec.
A method for manufacturing a composite material containing multiple types of waste plastics.
delete The method of claim 1,
Characterized in controlling the temperature, pressure and speed conditions in the mixing and injection process according to the ratio of different materials,
A method for manufacturing a composite material containing multiple types of waste plastics.

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