Claims:WE CLAIM:
1. A process for recycling a postconsumer high density polyethylene (HDPE), comprising:
cleaning the postconsumer HDPE;
mixing one or more colors and at least one additive to a preheated and cleaned postconsumer HDPE,
wherein the at least one additive comprises organic peroxide containing 0.1% of 40% dicumyl peroxide,
wherein the mixing of the additive imparts enhancement in mechanical strength and decrease in Melt Flow Index (MFI) of the postconsumer HDPE; and
processing a preheated postconsumer HDPE to obtain a recycled postconsumer HDPE.
2. The process as claimed in claim 1, wherein the cleaning the postconsumer HDPE comprises
colleting a group of postconsumer plastics,
wherein the group of postconsumer plastics comprises polyethylene terephthalate, high-density polyethylene, polyvinyl chloride (PVC), low-density polyethylene (LDPE) polypropylene (PP) and polystyrene;
segregating postconsumer HDPE from the group of postconsumer plastics;
grinding a separated postconsumer HDPE into flakes;
washing the postconsumer HDPE flakes using water and detergent to remove at least one of deeply soaked dirt, volatile and solid impurities from the postconsumer HDPE flakes; and
drying a washed postconsumer HDPE flakes to obtain the cleaned postconsumer HDPE.
3. The process as claimed in claim 1, wherein the processing the preheated postconsumer HDPE comprises
extruding the preheated postconsumer HDPE; and
pelletizing an extruded postconsumer HDPE to obtain the recycled postconsumer HDPE.
4. The process as claimed in claim 1, wherein the postconsumer HDPE being preheated at temperature between 100°C to 115°C.
5. The process as claimed in claim 2, wherein the postconsumer HDPE flakes comprise range of size of the flakes from 10 mm to 25 mm.
6. The process as claimed in claim 3, wherein the extruding of the preheated postconsumer HDPE being carried at temperature between 170°C to 240°C.

Dated this 20th day of May 2020

Signature

Vidya Bhaskar Singh Nandiyal
Patent Agent (IN/PA-2912)
Agent for the Applicant
, Description:FIELD OF INVENTION

[0001] Embodiments of a present invention relates to recycling plastic waste, and more particularly to a process for recycling a postconsumer high density polyethylene (HDPE).

BACKGROUND

[0002] Plastics are derived from petroleum sources and are generally non-biodegradable. The unprecedented use of plastic has made them a major component of solid, non-environment friendly waste from industries as well as consumers. High-density polyethylene (HDPE) or polyethylene high-density is a thermoplastic polymer produced from the monomer ethylene. HDPE is used in the production of plastic bottles, corrosion-resistant piping, geomembranes and plastic lumber.

[0003] Most of the post-industrial or postconsumer plastic waste goes to landfill sites contributing to serious environmental problems such as land, water, and air pollution. In addition, the disposal costs for the post-industrial plastic waste poses an extra burden on the manufacturers.

[0004] In recent years, regeneration of polymer waste materials has been attracting attention. Products made from HDPE recycled plastic are considered Eco-friendly because they are made mainly from post-consumer products and are recyclable at the end of their useful life. HDPE plastic is the most environmentally stable of all plastics giving off no harmful fumes into the environment.

[0005] However, the conventional processes for extrusion of recycled plastic material include significant and costly pre-process steps such as segregating and beading. The commercial viability of these processes being challenged when the product of extrusion process i.e. the recycled material is not of a quality as of a virgin material. While doing mechanical recycling of postconsumer HDPE the mechanical properties like tensile strength, elongation at break decreases due to chain scission mechanism due to which the recycled material is not used in applications having strict quality parameters.

[0006] Hence, there is a need for an improved and cost-effective process for the recycling of the postconsumer HDPE.

SUMMARY

[0007] In accordance with an embodiment of the invention, a process for recycling a postconsumer high density polyethylene (HDPE) is provided. The process includes cleaning the postconsumer HDPE. The process also includes mixing one or more colors and at least one additive to a preheated and cleaned postconsumer HDPE. The at least one additive comprises organic peroxide containing 0.1% of 40% dicumyl peroxide. The mixing of the additive imparts enhancement in mechanical strength and decrease in Melt Flow Index (MFI) of the postconsumer HDPE. The process further includes processing a preheated postconsumer HDPE to obtain a recycled postconsumer HDPE. The present invention provides an improved and cost-effective process for recycling the HDPE. The process provides the recycled HDPE with enhanced mechanical properties such as increased tensile strength and elongation at break.

[0008] To further clarify the advantages and features of the present disclosure, a more particular description of the disclosure will follow by reference to specific embodiments thereof, which are illustrated in the appended figures. It is to be appreciated that these figures depict only typical embodiments of the disclosure and are therefore not to be considered limiting in scope. The disclosure will be described and explained with additional specificity and detail with the appended figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The disclosure will be described and explained with additional specificity and detail with the accompanying figures in which:
[0010] FIG. 1 is a flow diagram (100) representing steps of a process for recycling a postconsumer high density polyethylene (HDPE) in accordance with an embodiment of the present disclosure; and
[0011] FIG. 2 is a flow diagram (200) representing steps of the a process for cleaning the postconsumer HDPE in accordance with an embodiment of the present disclosure.
[0012] Further, those skilled in the art will appreciate that elements in the figures are illustrated for simplicity and may not have necessarily been drawn to scale. Furthermore, in terms of the method steps, chemical compounds, and parameters used herein may have been represented in the figures by conventional symbols, and the figures may show only those specific details that are pertinent to understanding the embodiments of the present disclosure so as not to obscure the figures with details that will be readily apparent to those skilled in the art having the benefit of the description herein.
DETAILED DESCRIPTION
[0013] For the purpose of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiment illustrated in the figures and specific language will be used to describe them. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended. Such alterations and further modifications in the illustrated biosynthesis of magnesium oxide nanostructures, and such further applications of the principles of the disclosure as would normally occur to those skilled in the art are to be construed as being within the scope of the present disclosure.
[0014] The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such a process or method. Similarly, one or more components, compounds, and ingredients preceded by "comprises... a" does not, without more constraints, preclude the existence of other components or compounds or ingredients or additional components. Appearances of the phrase "in an embodiment", "in another embodiment" and similar language throughout this specification may, but not necessarily do, all refer to the same embodiment.
[0015] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this disclosure belongs. The system, methods, and examples provided herein are only illustrative and not intended to be limiting.
[0016] In the following specification and the claims, reference will be made to a number of terms, which shall be defined to have the following meanings. The singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise.
[0017] Embodiments of the present invention relates to a process for recycling a postconsumer high density polyethylene (HDPE). The process mainly comprises addition of organic peroxide to postconsumer HDPE to enhance mechanical strength of a recycled HDPE.
[0018] FIG. 1 is a flow diagram (100) representing steps of the process for recycling the postconsumer high density polyethylene (HDPE) in accordance with an embodiment of the present disclosure. As the HDPE is non-biodegradable and non-environment friendly, recycling of the HDPE contributes in avoiding environmental hazards.
[0019] The process for recycling the postconsumer high density polyethylene (HDPE) begins with cleaning the postconsumer HDPE at step 102. The cleaning the postconsumer HDPE before recycling ensures removal of adherent particles present on the postconsumer HDPE thereby leading to efficient recycling.
[0020] The cleaning the postconsumer HDPE in step 102 is carried using steps depicted by a flow diagram as provided in FIG.2, according to an embodiment.
[0021] The process for cleaning the postconsumer HDPE begins with colleting a group of postconsumer plastics at step 202. The group of postconsumer plastics may include Low Density Polyethylene (LDPE ), High Density Polyethylene (HDPE), Polypropylene (PP), Polystyrene (PS), Polyethylene Terephthalate (PET), Polyvinyl chloride (PVC), Polyoxymethylene (POM), Polymethyl methacrylate (PMMA), High Impact Polystyrene (HIPS), Acrylonitrile-Butadiene-Styrene (ABS), Hard polyvinyl chloride (HPVC), Soft polyvinyl chloride (SPVC) and likes.
[0022] The group of postconsumer plastics may be received recycling plants, garbage disposal units or waste management plants. The percentage or proportion of the Low Density Polyethylene (LDPE ), High Density Polyethylene (HDPE), Polypropylene (PP), Polystyrene (PS), Polyethylene Terephthalate (PET), Polyvinyl chloride (PVC), Polyoxymethylene (POM), Polymethyl methacrylate (PMMA), High Impact Polystyrene (HIPS), Acrylonitrile-Butadiene-Styrene (ABS), Hard polyvinyl chloride (HPVC), Soft polyvinyl chloride (SPVC) may vary significantly in different batches.
[0023] The process for cleaning the postconsumer HDPE includes segregating postconsumer HDPE from the group of postconsumer plastics at step 204. The segregating the HDPE from different types of polymer waste represents one of major problematic process. Different plastic polymers have different characteristics and mixing them together would alter those characteristics. Hence, segregating the postconsumer HDPE from different plastic polymers is a vital step in the process. A typical process to segregate discarded or the postconsumer plastic would be first to sort them based on color and sometimes on size. Manual segregating is suitable when HDPE component are present in large amount, but it is a labour intensive process. Hence, various automated processes being used for the segregating the HDPE such as X-Rays, NIR (near infrared), air sorting, electrostatic sorting technique, mechanical sorting, sorting by melting etc.
[0024] The process for cleaning the postconsumer HDPE includes grinding a separated postconsumer HDPE into flakes at step 206. The grinding the separated postconsumer HDPE before washing provides effective cleaning of the postconsumer HDPE, because the washing the postconsumer HDPE components while in one piece does not yield good results. In an embodiment, a plastic shredders and plastic grinders being used for the grinding of the separated postconsumer HDPE. The postconsumer HDPE flakes comprise range of size of the flakes from 10 mm to 25 mm.
[0025] As used herein the terms ‘plastic shredder’ and ‘plastic grinder’ refer to machines that are used to cut the plastic in small pieces to make it granular. The plastic shredders and plastic grinders are specially designed for large plastic waste such as very large objects for car bumpers, pipe, drums, plastic cane, PET bottles, plastic jars, blister packs of medicines, and LDPE containers etc.
[0026] The process also includes the washing the postconsumer HDPE flakes using water and detergent to remove at least one of deeply soaked dirt, volatile and solid impurities from the postconsumer HDPE flakes at step 208. The washing of the postconsumer HDPE flakes also helps in avoiding contamination in the recycling process and ensures effective recycling of HDPE.
[0027] The process includes drying a washed postconsumer HDPE flakes to obtain the cleaned postconsumer HDPE at step 210. The drying process is designed to remove substances, which are absorbed or adsorbed into/onto the flakes. In an embodiment, the drying of the washed postconsumer HDPE flakes includes thermal drying.
[0028] In an embodiment, one or more colors and at least one additive being mixed to a preheated and cleaned postconsumer HDPE at step 104. Preheating the cleaned postconsumer HDPE further reduce the contamination. The at least one additive mixed herewith comprises organic peroxide containing 0.1% of 40% dicumyl peroxide. The mixing of the additive imparts enhancement in mechanical strength and decrease in Melt Flow Index (MFI) of the postconsumer HDPE. Molecular formula and molecular weight of dicumyl peroxide are [C6H5C(CH3)2]2O2 and 270.37, respectively. The dicumyl peroxide is also known by IUPAC names such as Bis (1-methyl-1-phenylethyl) peroxide and Bis (a, a-dimethylbenzyl) peroxide. The dicumyl peroxide has a structure as represented below by formula (I):

----------- (I)

[0029] A selection of specific percentage of the dicumyl peroxide to the preheated and cleaned postconsumer HDPE plays very crucial role in imparting the desired physical and chemical properties for effective recycling of the postconsumer HDPE.
[0030] In such an embodiment, a preheated postconsumer HDPE being processed to obtain a recycled postconsumer HDPE at step 106. The postconsumer HDPE being preheated at temperature between 100°C to 115°C. The processing of the preheated postconsumer HDPE includes extruding the preheated postconsumer HDPE. The extruding of the preheated postconsumer HDPE being carried using a single screw extruder at temperature between 170°C to 240°C. As used herein the term ‘single screw extruder’ refers to a machine used to form a plastic product into the required shape. The machine heats the postconsumer HDPE to its melting point, after which it is pushed through a die that gives the material its shape.
[0031] The processing also includes pelletizing an extruded postconsumer HDPE to obtain the recycled postconsumer HDPE. The pelletizing the extruded postconsumer HDPE being carried using one of a simple strand pelletizer and a die face cutter. In the pelletizing, loose material is converted into compressed material. This results in great advantages in handling the waste, better storage, and significant savings in transportation costs.
[0032] As used herein the term ‘simple strand pelletizer’ refers to a machine which converts the product into pellets of different shapes and sizes, is frequently attached to an extruder or a gear pump. As used herein the term ‘die face cutter’ refers to a machine used to process PET and polyethylene plastic waste to recover the scraps and by products at the end of plastic fabrication.
[0033] The present invention provides an improved and cost-effective process for recycling the HDPE. The process provides the recycled HDPE with enhanced mechanical properties such as increased tensile strength and elongation at break. The process enables partial crosslinking of the postconsumer HDPE which contributes in decreasing Melt Flow Index (MFI) making the postconsumer HDPE stronger. This makes the recycled HDPE suitable for applications having strict quality parameters.
[0034] While specific language has been used to describe the disclosure, any limitations arising on account of the same are not intended. As would be apparent to a person skilled in the art, various working modifications may be made to the method in order to implement the inventive concept as taught herein.
[0035] The figures and the foregoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. Moreover, the actions of any flow diagram need not be implemented in the order shown; nor do all of the acts need to be necessarily performed. Also, those acts that are not dependant on other acts may be performed in parallel with the other acts. The scope of embodiments is by no means limited by these specific examples.