Embodiments of a present disclosure relate to a polypropylene recycle process. More particularly, the present disclosure relates to a process for conversion of a low value polypropylene recyclate into a high value polypropylene with virgin material like properties.
BACKGROUND
[0002] It is known that the plastic feedstock consumes 3-4% of world oil and gas production. Major share (40%) of plastics goes into packaging sector. Most of packaging material is short lived and discarded in a year, which limits the use of plastic as a sustainable material. Also, significant quantity of plastics is discarded mainly due to its loss in properties.
[0003] In recent years, as a drive towards sustainability, recycling of plastics has become very important. Now-a-days, recycled plastics are being used in various applications. However, recycling of polymer mostly produces low value material due to inferior mechanical properties.
[0004] For a sustainable process, it is a trend to use recycled material as a blend with virgin material up to a certain level. However there is no process for converting common recycled plastic into a material with high value i.e., improve the mechanical properties of the recycled polypropylene and thereby enable increase in use of recycled material alone or as a blend with the virgin polypropylene.
[0005] Hence, there is a need for a process to convert the low value polypropylene recyclate into the high value polypropylene to overcome the deficiencies found in the prior art.

SUMMARY OF THE INVENTION
[0006] In accordance with an embodiment of the present invention, a process for obtaining a high value polypropylene from a polypropylene recyclate comprises of compounding one or more additives with a polypropylene recyclate in a percentage range of 98.44 %wt to 99.67 %wt and extruding the compounded polypropylene composition with the one or more additives in a twin screw extruder at a temperature in the range of 190°C to 220°C.
[0007] In accordance with an embodiment of the present invention, wherein the additives comprises of an unsaturated carboxylic acid zinc salt in a percentage range of 0.3%wt to 1.5 %wt and a phosphate ester compound in a percentage range of 0.03 %wt to 0.06 %wt.
[0008] In accordance with an embodiment of the present invention, wherein the additives are compounded with a moulding grade polypropylene in a twin screw extrude having L/D of 25, 30mm screw diameter.
[0009] In accordance with an embodiment of the present invention, wherein the compounding is carried out at 300 screw rpm for optimum residence time.
[0010] In accordance with an embodiment of the present invention, wherein the additive unsaturated carboxylic acid zinc metal salt facilitates dynamic cross-linking.
[0011] In accordance with an embodiment of the present invention, wherein the additive phosphate ester compound facilitates the effect of nucleation.
[0012] In accordance with an embodiment of the present invention, wherein the nucleation and dynamic cross-linking results in a synergistic conversion of the polypropylene recyclate into a high value material.
[0013] To further clarify the advantages and features of the present invention, a more particular description of the invention 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 invention and are therefore not to be considered limiting in scope. The invention will be described and explained with additional specificity and detail with the appended figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The disclosure will be described and explained with additional specificity and detail with the accompanying figures in which:
[0015] FIG. 1 is a flow chart illustrating a process for obtaining a high value polypropylene from a polypropylene recyclate, in accordance with an embodiment of the present invention.
[0016] FIG. 2 is a graphical chart illustrating a melt flow index of the material taken at a fifth recyclate, in accordance with an embodiment of the present invention.
[0017] FIG. 3 is a graphical chart illustrating a flexural modulus and flexural strength of the material taken at fifth recyclate, in accordance with an embodiment of the present invention.
[0018] FIG. 4 is a graph illustrating an impact strength of the material taken at fifth recyclate, in accordance with an embodiment of the present invention.
[0019] 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
[0020] 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 system, 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.
[0021] 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.
[0022] 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.
[0023] 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.
[0024] As used herein, the term "Polypropylene" refers to a type of thermoplastic polymer resin with the chemical formula C3H6. It is useful in many packaging applications as a structural plastic or as a fiber-type plastic. It is easy to customize,

lightweight and very flexible, and has high melting point and a low level of electrical conductivity.
[0025] The present disclosure relates to a process for obtaining a high value polypropylene from a polypropylene recyclate.
[0026] FIG. 1 is a flow chart illustrating a process for obtaining a high value polypropylene from a polypropylene recyclate, wherein the process comprises of compounding one or more additives with a polypropylene recyclate in a percentage range of 98.44% wt to 99.67%) at step 110 and extruding the compounded polypropylene composition with the one or more additives in a twin screw extruder at a temperature in the range of 190°C to 220°C at step 120. Due to a higher reactivity of the acrylate, no peroxide is required to graft it on polypropylene backbone.
[0027] According to an embodiment of the present invention, wherein the one or more additives comprises of an unsaturated carboxylic acid zinc salt in a percentage range of 0.3% wt to 1.5 % wt and a phosphate ester compound in a percentage range of 0.03% wt to 0.06% wt.
[0028] According to an embodiment of the present invention, wherein the additives are compounded with a moulding grade polypropylene in a twin screw extrude having L/D of 25, 30mm screw diameter.
[0029] According to an embodiment of the present invention, wherein the compounding is carried out at 300 screw rpm for an optimum residence time.
[0030] According to an embodiment of the present invention, wherein the additive unsaturated carboxylic acid zinc metal salt facilitates dynamic cross-linking.
[0031] According to an embodiment of the present invention, wherein the additive phosphate ester compound facilitates the effect of nucleation.
[0032] According to an embodiment of the present invention, wherein the nucleation and dynamic cross-linking results in a synergistic conversion of the polypropylene recyclate into a high value material. Specifically, the reaction of dynamic crosslinking

and nucleation is combined for synergistic performance and upcycle of the polypropylene-recyclate material to a high value material.
[0033] According to an embodiment of the present invention, wherein during the recycling, a high temperature and a shear results in breaking of unsaturated carboxylic acid metal salt and yield free radicals. The formed free radical further forms bond with already existing free radicals on polypropylene chain and the free metal ion forms ionomer and acts as a crosslink which is dynamic in nature. It may be appreciated by a person skilled in the art that this dynamic crosslink improves resistance for bending, tension and impact load which further enhances strength and modulus. Further this phenomenon also helps in improving the toughness of polypropylene along with increase in stiffness. The alternatives available in the market increases strength and modulus at a cost of toughness.
[0034] According to an embodiment of the present invention, the developed formulation, simultaneously modulus and toughness of the polymer can be enhanced. Further the dynamic crosslinking also counters the effect of chain scission by creating ionomer which improves some flow restriction and the nucleation efficiency of phosphate ester compound is further employed for synergistically contribute to material with dynamic cross-linking to upcycle the polypropylene recyclate.
EXAMPLE EXPERIMENT
[0035] Raw Materials Used: 12 MFI Polypropylene recyclate, Unsaturated acrylic acid zinc salt and phosphate ester compound.
[0036] Experiment: The additives unsaturated acrylic acid zinc salt and the phosphate ester compound were compounded with molding grade polypropylene in a twin screw extrude having L/D of 25, 30 mm screw diameter and temperature profile of 190°C to 220°C. All the compounds were prepared at 300 screw rpm for the optimum residence time and the compositions are presented in the following table below:

S.No Sample Description Number of recycling Cone. (Unsaturated acrylic acid zinc salt) (ppm) Phosphate ester
compound (ppm)
1 PP 0 0 0
2 PP5R 5 0 0
3 PP5R 5000M 5 5000 0
4 PP5R 10000M 5 10000 0
5 PP5R 10000M 300N 5 10000 300
Table 1 EXPERIMENTAL RESULTS
[0037] FIG. 2 is graphical chart illustrating a melt flow index of the material taken at fifth recyclate, in accordance with an embodiment of the present invention. The material is taken for study at 5th recyclate and the extrusion process has been used to develop the recyclate, wherein the 5th recyclate is modified with unsaturated acrylic acid zinc salt at two different doses. One of the prominent effect of recycling is the chain scission resulting in increase in melt flow index. After passing the polymer five time, it results in 30% increase in melt flow index (MFI). Unsaturated acrylic acid zinc salt creates dynamic crosslinks which assists polymer to overcome losses due to recycling and it can be observed that after adding of unsaturated acrylic acid zinc salt helps in 70% retention of MFI.
[0038] FIG. 3 is a graphical chart illustrating a flexural modulus and flexural strength of the material taken fifth recyclate, in accordance with an embodiment of the present invention. It was observed that the flexural modulus which defines stiffness of material, is decreased by 3.5% after recycling it five times and addition of 5000 ppm of unsaturated acrylic acid zinc salt improves overall stiffness by 11%. Further, the increase in concentration of 1000 ppm, flexural modulus is further increased to 17%, which indicates formation of ionomer which provides dynamic crosslinks resulting overall stiffness increase. Further the composition with nucleating agent shows 20% increase in stiffness and this approach upcycles the polypropylene recyclate with properties even better than the virgin polymer.

[0039] FIG. 4 is a bar graph illustrating an impact strength of the material taken at fifth recyclate, in accordance with an embodiment of the present invention. Conventionally, polymeric system exhibits increase in stiffness with decrease in toughness or impact strength and can be observed from the figure below that 5th recyclate loses its toughness due to recycling by 13%. After modification, the impact strength is improved by 7.5 to 21%. It is to be noted that the heat deflection temperature which will help material to perform at high service temperature signifies the services temperature of the final product also found to increase by 10 to 15% after the modification.
[0040] The table 2 illustrates parameters obtained from the bar graphs of Fig. 2, 3 and 4, in accordance with an embodiment of the present invention.

Sample Description Melting Point Enthalpy Crystallinity Onset of crystallization
°C J/R % °C
PP5R 165 91 45 121
PP5R 10000M 162 100 48 124
PP5R 10000M 300N 163 114 55 125
Table 2
[0041] From the above table 2, it can be observed that the present crystallinity is increased up to 22% which is contributing to increase in stiffness and after modification the onset of crystallization is increased by 4°C, which helps in reducing cycle time in processing.
[0042] The description of the present disclosure uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The above are merely exemplary and illustrative of the inventive concept by, one of ordinary skill in the art in the specific embodiments described to make various modifications or additions, or a similar alternative manner, without departing from the invention. The invention, as defined in this disclosure or beyond the scope of the claims, should belong to the scope of the present invention.

[0043] While specific language has been used to describe the invention, 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.
[0044] 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. For example, order of processes described herein may be changed and are not limited to the manner described herein. 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 dependent 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.

WE CLAIM:

1. A process for obtaining a high value polypropylene from a polypropylene
recyclate comprises of:
compounding one or more additives with a polypropylene recyclate in a percentage range of 98.44 %wt to 99.67 %wt; and
extruding the compounded polypropylene composition with the one or more additives in a twin screw extruder at a temperature in the range of 190°C to 220°C.
2. The process as claimed in claim 1, wherein the one or more additives comprises of an unsaturated carboxylic acid zinc salt in a percentage range of 0.03 %wt to 1.5 %wt and a phosphate ester compound in a percentage range of 0.03% wt to 0.06 %wt.
3. The process as claimed in claim 1, wherein the additives are compounded with a moulding grade polypropylene in a twin screw extrude having L/D of 25, 30mm screw diameter.
4. The process as claimed in claim 1, wherein the compounding is carried out at 300 screw rpm for an optimum residence time.
5. The process as claimed in claim 1, wherein the additive unsaturated carboxylic acid zinc metal salt facilitates dynamic cross-linking.
6. The process as claimed in claim 1, wherein the additive phosphate ester compound facilitates the effect of nucleation.
7. The process as claimed in claim 1, wherein the nucleation and dynamic cross-linking results in a synergistic conversion of the polypropylene recyclate into a high value material.