FIELD OF INVENTION
[0001] Embodiments of a present disclosure relate to a polypropylene compositions. More particularly, the present disclosure relates to a high melt strength polypropylene composition and a process for preparing the same.
BACKGROUND
[0002] It is known that the melt strength of a polymer is very crucial in applications like film blowing, tape formation as well as fiber spinning, and the polypropylene is widely used in such applications. However, being a linear polymer, polypropylene exhibits inferior melt strength and stain hardening behavior.
[0003] The polypropylene grade which goes for high line-speed tape extrusion process often shows inferior properties in terms of tape breakage and low filler loading.
[0004] To improve melt strength of a polymer, generally several molecules can be grafted using peroxide initiators, the improper dosage of which promotes cleavage of the polymer main chain resulting in deterioration of mechanical as well as other properties.
[0005] Hence, there is a need for a high melt strength polypropylene composition and process for preparation of the same to satisfy the existing needs, as well as others, and generally overcomes the deficiencies found in the prior art.
SUMMARY OF THE INVENTION
[0006] In accordance with an embodiment of the present invention, a polypropylene composition having a high melt strength, the composition comprises of a polypropylene in a percentage range of 98.4% wt to 99.5% wt; and one or more additives selected from an additive package present by weight in a percentage range of 0.5% to 1.6% of total weight of the polypropylene composition.
[0007] According to an embodiment of the present invention, the additive package comprises one or more additives selected from the group consisting of a pentaerythritol

tetrakis [3-[3,5-di-tert-butyl-4-hydroxyphenyl] propionate), tris (2,4-di-tertiary butylphenyl) phosphite, synthetic hydrotalcite, a 2,5-Bis(tert-butylperoxy)-2,5-dimethylhexane, a Zn-Acrylate, a benzophenone and the combination thereof.
[0008] According to an embodiment of the present invention, the one or more additives selected from the group consisting of the pentaerythritol tetrakis [3-[3,5-di-tert-butyl-4-hydroxyphenyl] propionate) present in a percentage range of 0.04% wt to 0.05%) wt of the additive package, the tris (2,4-di-tertiary butylphenyl) phosphite present in a percentage range of 0.08%> wt to 0.1%> wt of the additive package, the synthetic hydrotalcite present in a percentage range of 0.025%> wt to 0.035%) wt of the additive package, the 2,5-Bis(tert-butylperoxy)-2,5-dimethylhexane in a percentage range of 0.002%) wt to 0.006%) wt of the additive package, the Zn-Acrylate in a percentage range of 0.1%) wt to 0.9%o wt of the additive package and the benzophenone in a percentage range of 0.25% wtto 0.55% wt of the additive package; and the mixtures thereof of the additive package.
[0009] In accordance to an embodiment of the present invention, a process for preparing a polypropylene composition comprises of compounding one or more additives with a polypropylene in a percentage range of 98.4%> wt to 99.5% wt, wherein the one or more additives selected from an additive package present by weight in a percentage range of 0.5% to 1.6% of total weight of the polypropylene composition 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.
[0010] 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

[0011 ] The disclosure will be described and explained with additional specificity and detail with the accompanying figures in which:
[0012] FIG. 1 is a flow chart illustrating a process for preparing a polypropylene composition with one or more additives, in accordance with an embodiment of the present invention.
[0013] FIG. 2 is a table illustrating a plurality of polypropylene compositions with the one or more additives, in accordance with an embodiment of the present invention.
[0014] FIG. 3 is a graphical chart illustrating a melt strength and a melt flow index of the plurality of polypropylene compositions with the one or more additives at different loads, in accordance with an embodiment of the present invention.
[0015] FIG. 4 is a graphical chart illustrating a rheological behavior of the plurality of polypropylene compositions with the one or more additives, in accordance with an embodiment of the present invention.
[0016] FIG. 5 is a table illustrating a zero shear viscosity of the plurality of polypropylene compositions with the one or more additives, in accordance with an embodiment of the present invention.
[0017] FIG. 6 is a graph illustrating a stress relaxation study of the plurality of polypropylene composition with the one or more additives, in accordance with an embodiment of the present invention.
[0018] FIG. 7 is a bar graph illustrating a stress relaxation study of the polypropylene compositions with the one or more additives, 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 comprises of a polypropylene composition having a high melt strength, wherein the composition comprises of a polypropylene in a percentage range of 98.4% wt to 99.5% wt and one or more additives selected from an additive package present by weight in a percentage range of 0.5% to 1.6% of total weight of the polypropylene composition.
[0026] According to an embodiment of the present invention, the additive package comprises one or more additives selected from the group consisting of a pentaerythritol tetrakis [3-[3,5-di-tert-butyl-4-hydroxyphenyl] propionate), tris (2,4-di-tertiary butylphenyl) phosphite, synthetic hydrotalcite, a 2,5-Bis(tert-butylperoxy)-2,5-dimethylhexane, a Zn-Acrylate, a benzophenone and the combination thereof.
[0027] According to such embodiment of the present invention, the one or more additives selected from the group consisting of the pentaerythritol tetrakis [3-[3,5-di-tert-butyl-4-hydroxyphenyl] propionate) present in a percentage range of 0.04% wt to 0.05%) wt of the additive package, the tris (2,4-di-tertiary butylphenyl) phosphite present in a percentage range of 0.08%> wt to 0.1%> wt of the additive package, the synthetic hydrotalcite present in a percentage range of 0.025%> wt to 0.035%) wt of the additive package, the 2,5-Bis(tert-butylperoxy)-2,5-dimethylhexane in a percentage range of

0.002% wt to 0.006% wt of the additive package, the Zn-Acrylate in a percentage range of 0. P/o wt to 0.9%) wt of the additive package, the benzophenone in a percentage range of 0.25%o wt to 0.55%) wt of the additive package and the mixtures thereof of the additive package.
[0028] The polypropylene composition of the present invention exhibits improved melt strength of the polypropylene composition.
[0029] FIG. 1 is a flow chart illustrating a process for preparing a polypropylene composition with one or more additives, in accordance with an embodiment of the present invention. According to an embodiment of the present invention, the process for preparing the polypropylene composition comprises of compounding the one or more additives with the polypropylene in a percentage range of 98.4%> wt to 99.5% wt, wherein the one or more additives selected from the additives package present by weight in a percentage range of 0.5% to 1.6% of total weight of the polypropylene composition 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.
[0030] According to the embodiment of the present invention, the additive package comprises one or more additives selected from the group consisting of a pentaerythritol tetrakis [3-[3,5-di-tert-butyl-4-hydroxyphenyl] propionate), tris (2,4-di-tertiary butylphenyl) phosphite, synthetic hydrotalcite, a 2,5-Bis(tert-butylperoxy)-2,5-dimethylhexane, a Zn-Acrylate, a benzophenone and the combination thereof.
[0031] According to the embodiment of the present invention, the one or more additives selected from the group consisting of the pentaerythritol tetrakis [3-[3,5-di-tert-butyl-4-hydroxyphenyl] propionate) present in a percentage range of 0.04% wt to 0.05%) wt of the additive package, the tris (2,4-di-tertiary butylphenyl) phosphite present in a percentage range of 0.08% wt to 0.1% wt of the additive package, the synthetic hydrotalcite present in a percentage range of 0.025%> wt to 0.035%) wt of the additive package, the 2,5-Bis(tert-butylperoxy)-2,5-dimethylhexane in a percentage range of 0.002%) wt to 0.006%) wt of the additive package, the Zn-Acrylate in a percentage range of 0.1%) wt to 0.9%) wt of the additive package, and the benzophenone in a percentage

range of 0.25% wt to 0.55% wt of the additive package; and the mixtures thereof of the additive package.
[0032] FIG. 2 is a table illustrating a plurality of polypropylene compositions with the one or more additives, in accordance with an embodiment of the present invention. According to an embodiment of the present invention, the one or more additives are compounded with raffia grade Polypropylene in a Twin screw extrude having L/D of 25, 30 mm diameter and temperature profile of 190 to 220°C. Considering lower residence time, 300 rpm screw speed is selected.
[0033] FIG. 3 is a graphical chart illustrating a melt strength using a melt flow index of the plurality of polypropylene compositions with the one or more additives at different loads, in accordance with an embodiment of the present invention. According to the embodiment of the present invention, to understand the improvement of the melt strength, the melt flow index (MFI) was measured at 230°C and at two different load 2.16 Kg and 21.6 Kg, wherein the melt flow index (MFI) was measured as the amount of material extrudes through a capillary die in 10 mins interval. It may be noted that higher the melt strength, higher is the resistance to flow causing lower melt flow index (MFI).
[0034] According to the embodiment of the present invention, the melt strength improvement was found with addition of Zn acrylate and Benzophenone.
[003 5] The addition of Zn-acrylate was found to enhance the stiffness of the material. Although, the prior art claims deterioration in impact properties with increase in stiffness of material, the polypropylene composition with the one or more additives exhibits enhanced stiffness without sacrificing impact properties and even, an increase in impact strength was found with increase in stiffness exhibited a good balance of stiffness-toughness.
[0036] FIG. 4 is a graphical chart illustrating a rheological behavior of the plurality of polypropylene compositions with the one or more additives, in accordance with an embodiment of the present invention. According to an embodiment of the present

invention, to understand the improvement in melt strength of the polypropylene composition, a high shear capillary rheology was performed at 230°C covering a shear rate of 10 to 4000 s"1. At a low shear rate region, composition 4 (RMSI Form-1) and composition 5 (RMSI Form-5) exhibited a similar shear viscosity, whereas the composition 5 (RMSI Form-5) showed a viscosity on the higher side, wherein higher viscosity is an indication of higher melt strength.
[0037] FIG. 5 is a table illustrating a zero shear viscosity of the plurality of polypropylene compositions with the one or more additives, in accordance with an embodiment of the present invention. Also, a zero shear viscosity derived from capillary rheology using Carreau-Yasuda model is also an indication of the melt strength. It may be noted that the higher the zero shear viscosity, higher is the melt strength.
[0038] FIG. 6 is a graph illustrating a stress relaxation study of the plurality of polypropylene composition with the one or more additives, in accordance with an embodiment of the present invention. According to an embodiment of the present invention, the melt strength of the polypropylene composition was also measured using the stress relaxation study.
[0039] According to an embodiment of the present invention, a moulded tensile specimen was stretched at 5mm/min speed at 1% strain, wherein the specimen was held at this strain and the reduction of force was measured with respect to time. It may be noted that higher the melt strength, higher is the time to relax the polymer chain resulting a delayed reduction in force with time.
[0040] FIG. 7 is a bar graph illustrating a stress relaxation study of the polypropylene compositions with the one or more additives, in accordance with an embodiment of the present invention, wherein the 'Drop in Force' implies difference in maximum force to force at lOmins time. Among the plurality of polypropylene composition, the composition 5 (RMSI Form-5) exhibited slower relaxation followed by the composition 4 (RMSI Form-4) and the composition 6 (RMSI Form-6).

[0041] To improve melt strength of a polymer, generally several molecules can be grafted using peroxide initiators, the improper dosage of which promotes cleavage of the polymer main chain resulting deterioration of mechanical as well as other properties. Due to lower activation energy of the Zinc Acrylate salt, no peroxide is required to graft it on polymer backbone. While compounding, the temperature as well as shear break the weakly bound acrylic '7t' bond to form free radicals which combine with the free radical on Polypropylene tertiary carbon and form stable covalent bond. The free Zinc ion sites of all the polymer chains form ionic clusters which act as cross-linking site and increases the melt strength of the Polypropylene. However, the advantage of the composition of the present disclosure is that the cross-link formed is not permanent, it is dynamic in nature. During processing in presence of higher temperature, the ionic bonds dissociate which helps in processability of the material. While cooling, the material reforms the ionic clusters. The performance of Zinc Acrylate also been found to increase in presence of Benzophenone (UV absorber) in a ratio of 1:1. The activated Benzophenone (UV absorber) enhances the grafting of acrylate salt on polymer backbone without deteriorating the molecular weight of the polymer.
[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 polypropylene composition having a high melt strength, the composition
comprising:
a polypropylene in a percentage range of 98.4% wt to 99.5% wt;
one or more additives selected from an additive package present by weight in a percentage range of 0.5% to 1.6% of total weight of the polypropylene composition.
2. The polypropylene composition as claimed in claim 1, wherein the additive package comprises one or more additives selected from the group consisting of a pentaerythritol tetrakis [3-[3,5-di-tert-butyl-4-hydroxyphenyl] propionate), tris (2,4-di-tertiary butylphenyl) phosphite, synthetic hydrotalcite, a 2,5-Bis(tert-butylperoxy)-2,5-dimethylhexane, a Zn-Acrylate, a benzophenone and the combination thereof.
3. The polypropylene composition as claimed in claim 1, wherein the one or more additives selected from the group consisting of:
the pentaerythritol tetrakis [3-[3,5-di-tert-butyl-4-hydroxyphenyl] propionate) present in a percentage range of 0.04% wt to 0.05% wt of the additive package;
the tris (2,4-di-tertiary butylphenyl) phosphite present in a percentage range of 0.08% wt to 0.1% wt of the additive package;
the synthetic hydrotalcite present in a percentage range of 0.025%) wt to 0.035%) wt of the additive package;
the 2,5-Bis(tert-butylperoxy)-2,5-dimethylhexane in a percentage range of 0.002% wt to 0.006% wt of the additive package;

the Zn-Acrylate in a percentage range of 0.1% wt to 0.9% wt of the additive package; and
the benzophenone in a percentage range of 0.25% wt to 0.55% wt of the additive package; and the mixtures thereof of the additive package.
4. The polypropylene composition as claimed in claim 1, wherein the polypropylene composition exhibits improved melt strength of the polypropylene composition.
5. A process for preparing a polypropylene composition comprises of:
compounding one or more additives with a polypropylene in a percentage range of 98.4% wt to 99.5% wt, wherein the one or more additives selected from an additive package present by weight in a percentage range of 0.5%) to 1.6% of total weight of the polypropylene composition; 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.
6. The process as claimed in claim 1, wherein the additive package comprises one or more additives selected from the group consisting of a pentaerythritol tetrakis [3-[3,5-di-tert-butyl-4-hydroxyphenyl] propionate), tris (2,4-di-tertiary butylphenyl) phosphite, synthetic hydrotalcite, a 2,5-Bis(tert-butylperoxy)-2,5-dimethylhexane, a Zn-Acrylate, a benzophenone and the combination thereof.
7. The process composition as claimed in claim 1, wherein the one or more additives selected from the group consisting of:
the pentaerythritol tetrakis [3-[3,5-di-tert-butyl-4-hydroxyphenyl] propionate) present in a percentage range of 0.04% wt to 0.05% wt of the additive package;
the tris (2,4-di-tertiary butylphenyl) phosphite present in a percentage range of 0.08% wt to 0.1% wt of the additive package;

the synthetic hydrotalcite present in a percentage range of 0.025%) wt to 0.035%) wt of the additive package;
the 2,5-Bis(tert-butylperoxy)-2,5-dimethylhexane in a percentage range of 0.002% wt to 0.006% wt of the additive package;
the Zn-Acrylate in a percentage range of 0.1%> wt to 0.9% wt of the additive package; and
the benzophenone in a percentage range of 0.25% wt to 0.55% wt of the additive package; and the mixtures thereof of the additive package.