DESC:CROSS REFERENCE TO RELATED APPLICATION
This application is based on and derives the benefit of Indian Provisional Application 202141010980 filed on 15/03/2021, the contents of which are incorporated herein by reference.

TECHNICAL FIELD
[001] The present invention relates to a polymer-based composition for automotive bumper lower aprons and appliques.

BACKGROUND
[002] Challenges in the automotive industry are increasing as laws for new vehicle designs are getting stiffer in terms of vehicle safety, fuel efficiency, customer perceived quality, recyclability and environmental friendliness. Material selection is of core focus while designing a vehicle. Steel, aluminum and polymer composites are the most widely used material for automotive parts. Of these, polymer composites such as polypropylene, offer excellent flowability, mechanical characteristics, weatherability, and chemical resistance. Polypropylene in automobile exterior parts such as bumpers are steadily substituting plastics due to the advantage of high cost performance.
[003] Front/rear bumper lower aprons plays a pivotal role as a shielding protection for the vehicle. They should provide pedestrian slow speed impact safety requirement, customer perceived quality requirement in terms of high-quality silver finish, dimensional stability under sun load condition, resistance against scratch loads, resistance against soiling agents, gap and flushness requirements.
[004] Conventionally, automotive front/rear bumper lower apron and exterior appliques are made from regular compounded polypropylene copolymer material. However, with limiting engineering and high surface quality silver finish requirements, painting is recommended after applying these polymeric compositions.
[005] One of the challenges for developing a polymeric composition for automotive bumper lower apron and exterior appliques is to eliminate surface painting along with maintaining mechanical and thermal properties and dimensional stabilities. In order to simplify the process, it is desirable to develop a polymeric composition that can obviate the aforementioned challenges.

OBJECTS
[006] The principal object of the embodiments disclosed herein is to provide a polymer-based composition suitable for use in producing aprons and appliques, for e.g. lower aprons and exterior appliques, for bumpers of automobiles, especially at pedestrian impact zones.
[007] Another object of the embodiment disclosed herein is to provide a polymer-based composition that is used for producing a front bumper lower apron.
[008] An object of the embodiment disclosed herein is to provide a polymer-based composition that is used for producing a rear bumper lower apron.
[009] Another object of the embodiment disclosed herein is to provide a polymer-based composition that is used for producing a bumper exterior applique.
[0010] Another object of the embodiments disclosed herein is to provide polymer-based composition having enhanced flowability.
[0011] An object of the embodiment disclosed herein is to provide a polymer-based composition that overcomes limitations of conventional material compositions such as lack of balance in high quality silver surface finish, stiffness, surface finish, and slow speed impact requirement.
[0012] An object of the embodiments disclosed herein is to provide a polymer-based composition having high surface quality silver finish with slow speed pedestrian impact.
[0013] Another object of the embodiment disclosed herein is to provide front bumper lower apron, rear bumper lower apron, /or exterior appliques having high surface finish, balanced mechanical and thermal properties and dimensional stability.
[0014] Further an object of the embodiments disclosed herein is to achieve reduction in overall production energy footprint, reduction in scrap with no requirement of secondary painting, and reduction in cost of final part by eliminating secondary operations.
[0015] Another object of the embodiments disclosed herein is to provide lower bumper and exterior appliques that are environment friendly, easily recycled, and achieve faster part production because intended color is achieved in single step during molding.
[0016] These and other objects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.

BRIEF DESCRIPTION OF DRAWINGS
[0017] The embodiments of the invention are illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:
[0018] Fig. 1 is a graphical representation depicting Melt flow index (MFI) comparison of a front / rear bumper lower apron prepared from conventional regular compounded material composition (also referred to as Sample A) and front / rear bumper lower apron prepared from reactor grade (Polypropylene copolymer) PPCP composition (also referred to as Sample C) with pre-colored finish;
[0019] Fig. 2 is a graphical representation depicting stiffness (flexural modulus) comparison of a front / rear bumper lower apron prepared from conventional regular compounded material composition (Sample A) and front/rear bumper lower apron prepared from reactor grade PPCP composition (Sample C) with pre-colored finish; and
[0020] Fig. 3 is a graphical representation of density comparison of a front/rear bumper lower apron prepared from conventional regular compounded material composition (Sample A) and front/rear bumper lower apron prepared from reactor grade PPCP composition (Sample C) with pre-colored finish.

DETAILED DESCRIPTION
[0021] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[0022] The embodiments herein disclose a polymer-based composition for use in automobiles. The polymer-based composition, according to embodiments herein, is suitable for use in producing bumper accessories, such as lower aprons and exterior appliques for bumpers of automobiles, for eg: appliques at pedestrian impact zones. In an embodiment, the composition is having enhanced flowability and is capable of achieving high surface finish, balanced mechanical and thermal properties and dimensional stabilities in automobile aprons and appliques. The embodiments disclosed herein also provide a polymer-based composition having high surface quality silver finish with slow speed pedestrian impact. It further overcomes B surface dog house engineering constraints and gate at A class surface edge periphery mold design constraints. In an embodiment, the polymer-based composition is used for producing front bumper lower apron. In another embodiment, the polymer-based composition is used for producing rear bumper lower apron. In an embodiment, the polymer-based composition is used for producing bumper appliques. Embodiments herein achieve automobile bumper lower apron and exterior appliques, capable of overcoming various limitations of conventional material compositions for e.g.: lack of balance in high quality silver surface finish, stiffness, surface finish, slow speed impact requirement, etc. Accordingly, embodiments herein, achieve bumper aprons and appliques having silver finish with high surface quality, and balanced mechanical, thermal properties and dimensional stabilities. Further, embodiments herein achieve reduction in overall production energy footprint, reduction in scrap with no requirement of secondary painting, and reduction in final part cost by eliminating secondary operations. Further, embodiments herein are environment friendly, easily recycled, and achieve faster part production because intended color is achieved in single step during molding.
Polymer-based composition
[0023] Embodiments herein include a polymer-based composition for aprons and appliques for bumpers of automobiles. In an embodiment, the composition is used to produce front bumper lower aprons, rear bumper lower aprons, and/or exterior appliques, particularly at pedestrian impact zones. The composition, according to embodiments herein, is a polypropylene based composition. In an embodiment, the composition includes polypropylene copolymer (PPCP) compound; Aluminum particles and filler comprising talc. In an embodiment, the composition includes compounded polypropylene copolymer, Aluminum particles and talc fillers.
[0024] In an exemplary embodiment, the composition includes reactor grade PPCP compound in the range of 90 to 95 wt% of the total composition. In other embodiments the amount of reactor grade PPCP compound is about 90 wt%, 90.5 wt%, 91 wt%, 91.5 wt%, 92 wt%, 92.5 wt%, 93 wt%, 93.5 wt%, 94 wt%, 94.5 wt% or 95 wt% of the total composition.
[0025] The polypropylene copolymer (PPCP), according to embodiments herein, includes copolymer comprising propylene and any other monomer. The other monomer, as referred to herein, includes any monomer, or monomer combinations, capable of copolymerizing with propylene such as, but not limited to, ethane, ethylene, diene monomers, a-olefins, cyclic olefins, etc. Examples of such monomers include, but are not limited to, ethylene, butene, isobutene, pentene, hexene, octene, decene, or derivatives thereof such as acyclic and cyclic derivatives, or combination thereof, such as 2-methyl-1-pentene, 2,3-dimethyl-1-pentene, 4-methyl-1-pentene, 2-methyl-1-butene, cyclopentene, cyclobutene, cyclobutadiene, dicyclopentadiene, hexadiene, etc. The polypropylene copolymer may include propylene and other monomer at suitable proportions or concentrations. For example, the copolymer may comprise about 45 to 95% of propylene content while the other monomer content may vary from 55% to 5% of the total copolymer. In an embodiment, the copolymer includes about 45%, 55%, 65%, 75%, 80%, 85%, or 90% of propylene content. The polypropylene copolymer may be block copolymers, alternate copolymers, random copolymers, and/or graft copolymers, or combinations thereof. The embodiments herein include polypropylene copolymer compound having high or ultra-high flow MFI. In an embodiment, the polypropylene copolymer is compounded copolymer. Various grades of polypropylene copolymers are available commercially, e.g.: compound grade, reactor grade, etc. In an embodiment, the polypropylene copolymer is reactor grade. In an embodiment, the reactor grade polypropylene copolymer is having high flow or ultra-high MFI. The polypropylene copolymer, according to embodiments herein, may be produced by methods generally known in the art. Examples of commercially available reactor grade polypropylene copolymer include, but are not limited to, Repol® B300MN and B650MN.
[0026] The embodiments of composition, as disclosed herein, further includes Aluminium (Al) particles. Fine and coarse particles of Al are used in various embodiments herein. Particle size of fine Al particles may vary. In an embodiment, the size of fine Al particles is in the range of 20µ to 50µ. Examples include, but are not limited to, 20µ, 25µ, 30µ, 35µ, 40µ, 45µ, 50µ, or combinations thereof. Particle size of coarse Al particles may vary. In an embodiment, the size of coarse Al particles is in the range of 50µ to 200µ. Examples include, but are not limited to, 50µ, 55µ, 60µ, 65µ, 70µ, 75µ, 80µ, 85µ, 90µ, 95µ, 100µ, 105µ, 110µ, 115µ, 120µ, 125µ, 130µ, 135µ, 140µ, 145µ, 150µ, 155µ, 160µ, 165µ, 170µ, 175µ, 180µ, 185µ, 190µ, 195µ, 200µ, or combinations thereof. The ratio of fine Al particles to coarse Al particles may suitably vary. In an embodiment, the ratio of 20µ to 50µ size Al fine particles to 50µ to 200µ size Al coarse particles in the composition may be in the range of 1:2 to 1:4. Example includes 1:2, 1:1.5, 1:3, 1:3.5, 1:4, etc. In an embodiment, the ratio is 1:2.
[0027] In an exemplary embodiment, the composition includes Al coarse particles having a size of about 50µ to 200µ, in the range of 0.5 to 2 wt% of the total composition. In other embodiments the amount of Al coarse particles is about 0.5 wt%, 1 wt%, 1.5 wt% or 2 wt% of the total composition. Further in an exemplary embodiment, the composition also includes Al fine particles of 20µ to 50µ size, in the range of 0.5 to 1 wt% of the total composition. In other embodiments the amount of Al fine particles is about 0.5 wt%, 0.75 wt% or 1 wt% of the total composition.
[0028] The embodiments of composition, as disclosed herein, further includes fillers. Examples of fillers which may be used include, but are not limited to, talc, calcium carbonate, mineral fibers, quartz, silica, glass beads, chalk, feldspar, titanium dioxide, wollastonite, calcium carbonate crystal whisker, barium sulfate, barium sulfate crystal whisker, mica powder, magnesium hydroxide etc. Fillers provide an improvement to physical-mechanical properties in a polymeric composition, such as Flexural Modulus, Heat Distortion Temperature (HDT) and nucleating effect. In a preferable embodiment, the filler is talc. In an exemplary embodiment, the talc filler is in the range of 4 to 7 wt% of the total composition. In other embodiments the amount of talc filler is about 4 wt%, 4.5 wt%, 5 wt%, 5.5 wt%, 6 wt%, 6.5 wt% or 7 wt% of the total composition.
[0029] In an embodiment, the composition comprises of reactor based PPCP compound in the range of 90 to 95 wt%, filled Al fine particles having particle size of about 20µ, in the range of 0.5 to 1 wt% and Al coarse particles, having particle size of about 50 µ, in the range of 0.5 to 2 wt% and talc filler in the range of 4 to 7 wt%, of the total composition. In another embodiment, the composition comprises of reactor based PPCP compound in the range of 90 to 95 wt%; filled Al fine particles, having particle size of about 20µ to 50µ, in the range of 0.5 to 1 wt% and Al coarse particles, having particle size of about 50µ to 200µ size, in the range of 0.5 to 2 wt% and talc filler in the range of 4 to 7 wt%.
[0030] The composition may further include other additives such as nucleating agents, antistatic agents, antioxidants, stabilizers, colouring agents, viscosity modifiers, slip or mold release agents, coupling agents, etc. It is understood that various modifications and alterations to the material and composition would be apparent to a person skilled in the art, in light and, within the spirit and scope of the disclosure made herein.
[0031] Embodiments disclosed herein also provide pre-colored silver polypropylene material for bumper lower aprons and exterior appliques. Concentration of Al fine particles, having particle size of about 20µ to 50µ, in the range of 0.5 to 1 wt% and Al coarse particles, having particle size of about 50µ to 200µ size, in the range of 0.5 to 2 wt% provides silver finish in the applications.
[0032] The various ingredients or components, according to embodiments herein, may be mixed, blended and/or kneaded by methods and equipments generally known in the art. A homogenous or heterogenous blend of the composition is prepared by mechanically blending the individual components using conventional compounding processes. In an embodiment, the polypropylene copolymer is compounded with the other components such as fine and coarse aluminum and talc filler, either individually or simultaneously.
[0033] The compounded polypropylene copolymer may then be extruder, and/or molded to obtain front/ rear bumper lower apron. Examples of such molding processes include blow molding, injection molding, casting rotational molding, compression molding, etc. In preferred embodiments, injection molding processes are used. Conventional injection molding processes may be used, examples include metal injection molding, over molding, insert molding, gas-assisted injection molding, thin wall molding, thermoplastic injection molding, liquid silicone injection molding, hot runner molding, etc. The disclosed polymer-based composition may be molded or extruded to achieve different shapes or sizes based on requirement. In an embodiment, the method for producing the bumper lower apron or applique comprises molding the disclosed polymer-based composition to obtain bumper lower apron or applique. In a preferred embodiment, the molding is performed by injection molding.
[0034] Embodiments herein provide a polymer-based composition suitable for use in producing, bumper lower apron and appliques for automobiles, particularly at pedestrian impact zones. The term “appliques” as used herein refers to a cover fastened to a vehicle surface for aesthetically styling and/or functionally covering impact zones or manufacturing imperfections in a vehicle. Conventionally appliques are made of metal and/or plastic. The term “apron” as used herein refers to a frame which is welded to the body of the vehicle and holds the struts. These are the inner fender areas under the hood of the car. Front bumper and rear bumper are functional components with slow speed impact and aerodynamic requirements. Front bumper also provides aesthetic requirements in an automobile such as mold-in-color finish as well as painted finish. Bumpers are designed to increase pedestrian protection along with maintaining weight at the extremities. Examples of lower bumper apron include front bumper lower apron, rear bumper lower apron. While embodiments herein are preferably directed towards bumper lower aprons, the composition may very well be adapted or employed in other automotive structures with silver theme such as bumpers, cladding, etc.
[0035] The composition, according to embodiments disclosed herein, is such that it achieves ultra-flow behavior, balanced tensile strength, modulus, impact strength, thermal properties, excellent surface finish, scratch resistance and impregnated silver particles. Further, the composition provides the aforementioned qualities without affecting any performance factors such as sustainability drive. Painting process consists of paint, primer, thinner, additives, fumes generation due to oven curing and over spray of paint chemicals. All these aspects are very hazardous, which generates pollution. Level of volatile organic compounds (VOC’s) are also very high. When VOC’s react with oxygen, they can form ‘bad’ ozone in the presence of sunlight. This is a contributory factor to the greenhouse effect and a cause of global warming. Triple bottom line theory was targeted to eliminate painting process for the selected auto exterior applications as a sustainable solution.
[0036] The present disclosure is further described in light of the following experiments which are set forth for illustration purpose only and not to be construed for limiting the scope of the disclosure. The following experiments can be scaled up to industrial/commercial scale and the results obtained can be extrapolated to industrial scale.
[0037] Exemplary embodiments of the composition, according to embodiments herein, and its constituents are depicted in the following examples.
Example 1
[0038] Table 1: List of ingredients in sample composition 1.
No. Ingredients Composition 1
1 Reactor grade PPCP 90 wt%
2 50µ to 200µ size Al coarse particles 2 wt%
3 20µ to 50µ size Al fine particles 1 wt%
4 Talc filler 7 wt%

Example 2
[0039] Table 2: List of ingredients in sample composition 2.
No. Ingredients Composition 2
1 Reactor grade PPCP 90.5 wt%
2 50µ to 200µ size Al coarse particles 2 wt%
3 20µ to 50µ size Al fine particles 1 wt%
4 Talc filler 6.5 wt%

Example 3
[0040] Table 3: List of ingredients in sample composition 3.
No. Ingredients Composition 3
1 Reactor grade PPCP 91 wt%
2 50µ to 200µ size Al coarse particles 2 wt%
3 20µ to 50µ size Al fine particles 1 wt%
4 Talc filler 6 wt%

Example 4
[0041] Table 4: List of ingredients in sample composition 4.
No. Ingredients Composition 4
1 Reactor grade PPCP 91.5 wt%
2 50µ to 200µ size Al coarse particles 2 wt%
3 20µ to 50µ size Al fine particles 1 wt%
4 Talc filler 5.5 wt%

Example 5
[0042] Table 5: List of ingredients in sample composition 5.
No. Ingredients Composition 5
1 Reactor grade PPCP 92 wt%
2 50µ to 200µ size Al coarse particles 1 wt%
3 20µ to 50µ size Al fine particles 0.5 wt%
4 Talc filler 6.5 wt%

Example 6
[0043] Table 6: List of ingredients in sample composition 6.
No. Ingredients Composition 6
1 Reactor grade PPCP 92.5 wt%
2 50µ to 200µ size Al coarse particles 1 wt%
3 20µ to 50µ size Al fine particles 0.5 wt%
4 Talc filler 6 wt%

Example 7
[0044] Table 7: List of ingredients in sample composition 7.
No. Ingredients Composition 7
1 Reactor grade PPCP 93 wt%
2 50µ to 200µ size Al coarse particles 1.5 wt%
3 20µ to 50µ size Al fine particles 0.75 wt%
4 Talc filler 4.75 wt%

Example 8
[0045] Table 8: List of ingredients in sample composition 8.
No. Ingredients Composition 8
1 Reactor grade PPCP 93.5 wt%
2 50µ to 200µ size Al coarse particles 1.5 wt%
3 20µ to 50µ size Al fine particles 0.75 wt%
4 Talc filler 4.25 wt%

Example 9
[0046] Table 9: List of ingredients in sample composition 9.
No. Ingredients Composition 9
1 Reactor grade PPCP 94 wt%
2 50µ to 200µ size Al coarse particles 1 wt%
3 20µ to 50µ size Al fine particles 0.5 wt%
4 Talc filler 4.5 wt%

Example 10
[0047] Table 10: List of ingredients in sample composition 10.
No. Ingredients Composition 10
1 Reactor grade PPCP 94.5 wt%
2 50µ to 200µ size Al coarse particles 1 wt%
3 20µ to 50µ size Al fine particles 0.5 wt%
4 Talc filler 4 wt%

Example 11
[0048] Table 11: List of ingredients in sample composition 11.
No. Ingredients Composition 11
1 Reactor grade PPCP 95 wt%
2 50µ to 200µ size Al coarse particles 0.5 wt%
3 20µ to 50µ size Al fine particles 2 wt%
4 Talc filler 2.5 wt%

[0049] Comparative study of the present composition (Sample C) with various combination was performed. Sample A composition comprises of 88 to 91.5 wt % regular compounded PPCP with 1.5 to 4 wt% of 50µ to 200µ size Aluminium coarse particles and 6 to 8 wt% of talc fillers. Sample B composition comprises of 92 to 94.5 wt % regular compounded PPCP with 1.5 to 4 wt% of 50µ to 200µ size Aluminium coarse particles and 2 to 4 wt% of talc fillers. The polymer-based composition according to embodiments herein i.e. Sample C, comprises of 90 to 95 wt% reactor based PPPC, with 0.5 to 1 wt% of 20µ to 50µ size Al fine particles and 0.5 to 2 wt% of 50µ to 200µ size Al coarse particles and 4 to 7 wt% of talc filler. Sample C exhibited improved flow, balance in mechanical and thermal properties as compared to other samples. Table 12 provides list of ingredients of the compositions compared with the present composition.
[0050] Table 12: List of ingredients in sample composition
Ingredients Sample A Sample B Sample C
Regular compounded PPCP 88 to 91.5 wt % 92 to 94.5 wt % 0 wt %
Reactor grade PPCP compound 0 wt % 0 wt % 90 to 95 wt %
50µ to 200µ size Al coarse particles 1.5 to 4 wt% 1.5 to 4 wt% 0.5 to 2 wt%
20µ to 50µ size Al fine particles 0 wt % 0 wt % 0.5 to 1 wt%
Talc filler 6 to 8 wt% 2 to 4 wt% 4 to 7 wt%

[0051] The embodiments herein were further tested on various parameters such as component level test, long term heat aging test, humidity aging test, cold impact test, serviceability test, vehicle level test, structural durability test and slow speed pedestrian. It was observed that abnormalities like crack, deformation, softening, warpage, visual discoloration and loosening were absent for the polymer-based composition according to embodiments herein (Sample C). The long-term heat and humidity aging tests performed at 80 degrees Celsius for 500 hours and 40±2 degrees Celsius at 95±5% relative humidity for 168 hours, respectively. No cracks were found in any of the points on front bumper lower apron made from the polymer-based specification of the present disclosure when subjected to cold impact test, performed at -30 degrees Celsius for 5 hours. It was further observed that no crack was found on the polymer-based specification of the present disclosure when subjected to serviceability test. Further, after completion of 100 cycles no cracks were seen on front bumper lower apron made from the polymer-based specification of the present disclosure when subjected to vehicle durability test. Embodiments herein were further subjected to structural durability CAE analysis and it was observed that stress versus deflection were well within the limit.
[0052] Slow speed pedestrian impact analysis was performed for the specification of the present invention and it was observed that the intended part made of present specification meets criteria. The compositions were tested for physical, mechanical, thermal and weathering properties such as balanced flow, tensile strength, modulus, impact strength, and thermal properties. Melt flow index or melt flow rate (MFI or MFR) was determined by ASTM D1238, Density was determined by ASTM D792, Tensile strength was determined by ASTM D638, Elongation at yield was determined by ASTM D638, Flexural modulus was determined by ASTM D790, Notched Izod impact strength at 23 Degrees Celsius was determined by ASTM D256, Heat deflection temperature (HDT) was determined by ASTM D648, Coefficient of Linear Thermal Expansion (CLTE) was determined by ASTM E831, Specular gloss at 20 degrees Celsius was determined by ASTM D523, accelerated weathering up to 3000 h was determined using SAE J2527. Table 13 depicts the results and properties of the compositions.
[0053] The MFI, or melt flow index, is a measure of the ease of flow of the melt of a thermoplastic polymer. It is generally defined as the weight of a polymer in grams flowing in 10 min through a die of specific diameter and length by a pressure applied by a given weight at a given temperature. In the study, it is observed that Sample C showed MFI of about 27 g/10min, while Sample A and Sample B showed 11 g/10 min and 15 g/10 min, respectively. Fig. 1 is a graphical representation depicting MFI comparison of front/rear bumper lower apron prepared from conventional regular compounded material composition (Sample A) and front/rear bumper lower apron prepared from reactor grade PPCP composition (Sample C) with pre-colored finish,; wherein sample A includes 88 to 91.5 wt % regular compounded PPCP with 1.5 to 4 wt% of 50µ to 200µ size Aluminium coarse particles and 6 to 8 wt% of talc fillers; and sample C includes 90 to 95 wt% reactor based PPPC, with 0.5 to 1 wt% of 20µ to 50µ size Al fine particles and 0.5 to 2 wt% of 50µ to 200µ size Al coarse particles and 4 to 7 wt% of talc filler.
[0054] Tensile strength or maximum load that a material can support without fracture when being stretched, divided by the original cross-sectional area of the material, of each polymer composition was tested. A minimum of 18 Mpa tensile strength was seen for all the three samples tested.
[0055] The notched Izod impact tests was performed at 23 degrees Celsius. Notched Izod Impact test is a single point test that measures a materials resistance to impact from a swinging pendulum. Izod impact is defined as the kinetic energy needed to initiate fracture and continue the fracture until the specimen is broken. Notched Izod impact strength tests for Sample C was observed to be minimum 50 kJ/m2 while for both Sample A and B, minimum 50 kJ/m2, Notched Izod impact strength was observed respectively.
[0056] The Flexural modulus of a material is a physical property denoting the ability for that material to bend. In mechanical terms, it is the ratio of stress to strain during a flexural deformation or bending. Sample C showed a higher Flexural modulus of 950 Mpa as compared to Sample A and B (900 Mpa, respectively).
[0057] Fig. 2 is a graphical representation depicting stiffness (flexural modulus) comparison of a front/rear bumper lower apron prepared from conventional regular compounded material composition (Sample A) and front/rear bumper lower apron prepared from reactor grade PPCP composition (Sample C) with pre-colored finish. Density of Sample C was observed to be 0.94 gm/cc as compared to Sample A and B (0.98, 0.93, respectively).
[0058] As depicted in Fig. 3, the density of sample C is lesser and more suitable as compared to that of a sample A. The Heat deflection temperature (HDT) is the temperature at which a polymer or plastic sample deforms under a specified load. HDT of Sample C and B was observed to be 90 degrees Celsius while Sample A showed an HDT of 95 degrees Celsius.
[0059] The coefficient of linear thermal expansion (CLTE) is a material property that is indicative of the extent to which a material expands upon heating. CLTE of 100 to 120 µm/°C was observed for all the three samples. ASTM D523 is a standard test method for specular gloss. Specular gloss is used to measure the capacity of a surface to reflect more or less light. Accelerated weathering test simulates extreme weather conditions in order to observe change in color, cracking, corrosion and deterioration of a product's exterior and interior. SAE J2527 is a performance-based standard for accelerated weathering that uses a Xenon Arc as a light source to simulate outdoor exposure to sunlight on an accelerated basis. Accelerated weathering upto 3000 h was performed for all the three samples. Table 13 depicts the results and properties of the compositions.
[0060] Table 13: Physical, mechanical, thermal and weathering properties.
Properties Standard Units Sample A Sample B Sample C
MFI ASTM D1238 g/10min Min 11 Min 15 Min 27
Density ASTM D792 gm /cc Max 0.98 Max 0.93 Max 0.94
Tensile strength ASTM D638 Mpa Min 18 Min 18 Min 18
Flexural modulus ASTM D790 Mpa Min 900 Min 900 Min 950
Notched Izod impact strength at 23 ° C ASTM D256 kJ/m2 Min 50 Min 50 Min 30
HDT ASTM D648 ° C Min 95 Min 90 Min 90
CLTE ASTM E831 µm/°C 100 to 120 100 to 120 100 to 120
Gloss @ 20° ASTM D523 - As per design team requirement
Accelerated weathering up to 3000 h SAE J2527 dE =3
GSR (Gray scale rating) 4 or better

[0061] In an embodiment, the polymer-based composition has MFI not lesser than 27 g/10 mins. In another embodiment, density of the polymer-based composition is not more than 0.94 gm /cc. In another embodiment, the tensile strength of the polymer-based composition is not lesser than 18 Mpa. In yet another embodiment, the polymer-based composition has a heat deflection temperature of not lesser than 90 degree Celsius. In an embodiment, the Notched Izod Impact strength of said polymer-based composition at is not lesser than 30 kJ/m2. The flexural modulus of said polymer-based composition, according to embodiments herein is not lesser than 950 Mpa. In an embodiment, the polymer-based composition has CLTE in the range of 100 to 120 µm/°C. In another embodiment, the polymer-based composition has an excellent color retention in terms of dE and Gray scale rating for a testing period of 3000 h.
[0062] The polymer-based composition of the present invention was found to have ultra-flow behaviour, balanced tensile strength, higher impact strength, thermal properties, excellent surface finish, scratch resistance and weathering resistance, as evidently seen in Table 13, compared to other conventional combinations.
[0063] The embodiments disclosed herein, offer technical advantages of the polymer-based composition for automotive bumper aprons and appliques, e.g.: front/ rear bumper lower aprons and exterior appliques as compared to the conventional polymer-based compositions. The materials, i.e. front/ rear bumper lower aprons and exterior appliques, manufactured from the disclosed embodiments with respect to intended part design meets slow speed pedestrian impact requirement. Further, the materials also meet dimensional stability requirement under sun load conditions. The composition, according to embodiments herein, lowers final part cost by eliminating secondary operations thereby providing a net cost reduction of up to 40% i.e. a cost saving of INR 400 per vehicle. Further, the composition according to embodiments herein, also provides high quality, longer lasting, brilliant colour and finish, thus enhancing the overall aesthetics of the automotive. Embodiments herein attain a polymer-based composition, that avoids paint peeling issues as coloring is integral to the plastic moulded part. Also, the manufactured material is highly ergonomic to utilize in existing part and mould design complexities which saves new mould investments. Further, with no secondary painting required, less scrap is generated. Faster part production is attained as colour achieved in one step during moulding. The composition, according to embodiments herein, offers an environmentally friendly manufacturing process that eliminates environmental issues of painting, can be easily recycled, and lowers overall production energy footprint.
[0064] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
,CLAIMS:We claim:
1. A polymer-based composition for automotive bumper apron and/or applique, said composition comprising reactor grade polypropylene copolymer compound; fine particles of aluminium, wherein particle size of said fine particles is in the range of 20µ to 50µ; coarse particles of aluminium, wherein particle size of said coarse particles is in the range of 50µ to 200µ; and filler comprising talc.

2. The polymer-based composition as claimed in claim 1, wherein said polypropylene copolymer is ultra-flow reactor grade polypropylene copolymer, present in an amount ranging from 90 wt% to 95 wt% of the total composition.

3. The polymer-based composition as claimed in claim 1, wherein ratio of said fine particles of aluminium and said coarse particles of aluminium is in the range of 1:2 to 1:4.

4. The polymer-based composition as claimed in claim 1, wherein said filler is present in an amount ranging from 4 % to 7 % by weight of the total composition.

5. The polymer-based composition as claimed in claim 1, wherein melt flow index of said composition is not less than 27 g/10 mins.

6. The polymer-based composition as claimed in claim 1, wherein density of said composition is not more than 0.94 gm /cc.

7. The polymer-based composition as claimed in claim 1, wherein tensile strength of said composition is not less than 18 Mpa.
8. The polymer-based composition as claimed in claim 1, wherein heat deflection temperature of said composition is not less than 90 degree Celsius, flexural modulus of said composition is not less than 950 Mpa, CLTE of said composition is in the range of 100 to 120 µm/°C, and/or Notched Izod Impact strength of said composition at 23 degrees Celsius temperature is not less than 50 kJ/m2.

9. The polymer-based composition as claimed in claim 1, wherein said composition provides a silver colour and/or finish to said bumper apron and/or applique.

10. A method for producing automotive bumper apron and/or applique, said method comprising molding the composition claimed in claim 1 to obtain said apron and/or applique, wherein said molding is performed by injection molding.