FORM 2
THE PATENT ACT 1970
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION
Polyurethane Natural Fibre Composites Foam for Automotive Application
2. APPLICANT
(a) NAME : MAHINDRA & MAHINDRA LIMITED
(b) NATIONALITY : An Indian Company registered under the Companies Act,
1956
(c) ADDRESS : R&D Center, Automotive Division,
Mahindra & Mahindra Limited,
89,M.I.D.C., Satpur, Nashik-422 007,
Maharashtra, India
2. PREAMBLE TO THE DESCRIPTION
COMPLETE
The following specification particularly describes the invention and the manner in which it is to be performed

Polyurethane Natural Fiber Composites Foam for Automotive Application
Field of invention
The present invention relates to a foam for automotive application, and more particularly, to a polyurethane natural fiber composites foam for automotive application.
Background of the present invention
Conventionally, various foam for automotive system are available. Specifically, United States Patent 4,683,246 describes a polyurethane foam-fiber composite structures comprising flexible polyurethane foam uniformly mixed with a fibrous material and bonded with a liquid flexible resinous binding agent to provide a cured foam structure. The relative amounts of materials in the foam structure are such that for each 100 parts by weight of polyurethane foam particles contains about 10 to 500 parts of fibrous material and about 10 to 250 parts of binding agent. The foam structures shows good sag factor with good resiliency for a select density.
Further, US Patent 6,649,667 B2 describes foam produced by RIM (Reaction Injection Molding) process by reacting an organic polyisocyanate with an isocyanate-reactive mixture in which a significant amount of bio based polyol is present. The foam produced by this process is characterized by improved heat sag and heat distortion temperature.
Furthermore, US patent 7,6624,69B2 discloses rigid polyurethane foam with outer layers with heat accumulator material and 50-93 % of lignocelluloses particles or lignocelluloses materials..
Moreover, the European patent EP 1 368 188 Bl discloses a composite with a binder and filler which can be used for gravel packing and sound field packing.

The EP patent covers all the natural fibers and ground coconut powder as filler with a density range 0.8 to 1.52 g/cm3. Further, the filler is of 60-80 % by volume. Further, binder used includes Novalac resins, resole resin or epoxy, and polyurethane.
However, the foam disclosed in the prior art does not provide improved mechanical as well as NVH (noise, vibration and harshness) properties along with good process ability.
Accordingly, there exists a need for foam for automotive application, which provides improved tear strength, tensile strength, sound absorption capability, flame resistance, compression strength, cyclic fatigue endurance and especially high retention of mechanical properties after water immersion.
Objects of the present invention
An object of the present invention is to provide a polyurethane natural fiber composites foam having improved tear strength, tensile strength, sound absorption, flame resistance, compression strength, and cyclic fatigue endurance.
Another object of the present invention is to provide a polyurethane natural fiber composites foam having high retention of mechanical properties after water immersion.
Summary of the invention
Accordingly, the present invention provides a flexible polyurethane natural fiber composites prepared by reaction injection molding, the flexible polyurethane natural fiber composites comprising: polyol in a range between 60-70 % w/w;

polyisocyanate in a range between 30-40 % w/w; coconut fibers in a range between 11-15% w/w; coconut shell powder in a range between 1-2.5 % w/w; wetting agent in a range between 0.5-1 % w/w; and dispersing agent in a range between 0.5-1 % w/w
wherein the polyisocyanate is reacted with polyol and thereafter coconut fibers and the coconut shell powder are added along with wetting agent and dispersing agent during the reaction of the polyisocyanate with the polyol.
Brief description of figures
Figure 1 shows a graph depicting comparison of tear strength properties of polyurethane natural fiber composites foam, in accordance with the present invention; and
Figure 2 shows a graph for sound absorption co-efficient values for different filler loading of polyurethane natural fiber composites foam, in accordance with the present invention.
Detailed description of the invention
The foregoing objects of the invention are accomplished and the problems and shortcomings associated with the prior art techniques and approaches are overcome by the present invention as described below in the preferred embodiment.
The present invention provides a polyurethane natural fiber composites foam having improved tear strength, tensile strength, sound absorption, flame resistance, compression strength, and cyclic fatigue endurance. Further, the

polyurethane natural fiber composites foam provides high retention of mechanical properties after water immersion.
The present invention describes a flexible polyurethane natural fiber composites (hereinafter 'the PUNFC) foam for reducing the noise, vibration and harshness (NVH).
The PUNFC foam is produced by reaction injection moulding process having a particular ratio of coconut fibers and coconut shell powder therein. Specifically, the flexible polyurethane natural fiber composites includes polyol in a range between 60-70 % w/w. Example of suitable biobased polyol includes but not limited to a polymerized soybean oil having a hydroxyl functionality.
Further, the PUNFC includes polyisocyanate in a range between 30-40 % W/W. In an embodiment, the polyisocyanate has isocyanate equivalent weight of 481gms.
Example of suitable polyisocyanates can be unmodified isocyanates, modified polyisocyanates, or isocyanate prepolymers. Suitable organic polyisocyanates include aliphatic, cycloaliphatic, araliphatic, aromatic, and heterocyclic polyisocyanates.
Furthermore, the PUNFC includes coconut fibers in a range between 11-15 % W/W and coconut shell powder in a range between 1-2.5 % W/W (also known as filler). In an preferred embodiment, the length of the coconut fiber ranges 3-5 cm with diameter of about 0.05 to 1.5 mm and the coconut shell powder size is in range between 50-250 microns (100 mesh particle size). Also, the density of the coconut shell powder is 0.6 to .7 g/cc.
The PUNFC also includes wetting agent and dispersing agent in a range between 0.5-1 %W/W.

Wetting agent includes suitable emulsifiers and foam stabilizers. Examples of suitable wetting agent /surfactants include any of several silicone surfactants known in the art as well as various amine salts of fatty acids (such as diethyl-amine oleate or diethanolamine stearate) and sodium salts of ricinoleic acids. The dispersing agent may be selected from any suitable dispersing agent known in the art.
In another aspect, the present invention provides a process of preparation flexible polyurethane natural fiber composites. The process is reaction injection molding (RIM) process which includes reacting the polyisocyanate the polyol derived from bio source. The coconut fibers and coconut shell powder are added along with the wetting agent and dispersing agent during the reaction of the polyol with the polyisocyanate. The developed composite formulations are tested in the lab and found test properties are given in table 1A and 1B
Table -1 A: Experiment details and results

Coconut fiber Coconut shell powder density Tear strength
Units % % (kg/M3) (Kg/mm)
Sample 1 0 2.5 144.98 0.042
Sample 2 4.7619 2.5 144.21 0.059
Sample 3 9.090 2.5 143.2 0.10038
Sample 4 13.04 2.5 146.2 0.148336
Sample 5 16.66 2.5 148.04 0.121771
Table -IB: Experiment details and results

Tear
strength
after water
ageing % water absorption flammability (burn rate) Tensile compression
data
Units (kgf/mm) % mm/min kgf/cm2 N
Sample 1 0.018 116.7 22.7 0.75 19
Sample 2 0.027 117.0 22.2 1.18 20
Sample 3 0.042 161.6 21.8 1.49 24
Sample 4 0.089 158.7 21.4 2.15 29
Sample 5 0.056 183.0 21.3 1.37 30
Table 1A and IB show that a specific percentage of the coconut fiber and the coconut shell powder gives excellent mechanical properties, along with NVH (noise, vibration and harshness) properties. The formulation of the foam is optimized based on the abovementioned results. The developed optimized flexible PLTNFC improves the tear strength for more than 250%.The tensile strength, compression strength of the composites are also improved significantly. Further, the flame resistance, the tear strength and sound absorption is improved by the combination of coconut fiber and coconut shell powder. Figure 1 shows a graph of comparison on tear strength properties of PUNFC foam in accordance with the present invention.
Furthermore, the retention of tear strength after water ageing is improved by the addition of fillers (coconut fibers and coconut shell powder) of about 15.54% of total filler content of the foam. Specifically, the prepared PUNFC foam sample is kept in water for 72 hours and thereafter the sample is removed from water. Further, the sample is kept outside for an hour, tear testing is done as per JASO M 305 and results are compared. The prepared PUNFC after immersion of 72 hours in water has a better tear strength i.e. above 300 % as compared to the

polyurethane unfilled with filler. The NVH properties of the abovementioned formulations are studied and results are shown in graph 2 as shown in figure 2.
The figure 2 shows the graph of sound absorption co-efficient values for different filler loading. On the basis of aforementioned test report, the formulation of the PUNFC foam is optimized.
Further, a dynamic durability test is carried out for the PUNFC foam of the present invention. This test is performed on the optimized formulation to get one to one comparison data on actual durability of the flexible polyurethane foam of the prior art and flexible PUNFC. Sample size of PUNFC foam used for this test is 50 X 250 X 5 mm. A universal testing machine is used for the dynamic durability test in which the heads moves cyclically at a speed of 500 mm/ min. The cycle frequency used is 2.5 cycles / min. The time taken for initial crack generation is counted as the resulted data. The developed formulation has 63 hours more durability than the unfilled foam of the prior art.
The PUNFC foam produced by the combination of the coconut shell powder and the coconut fibers of the present invention have shown the improvement in tear strength, tensile strength, sound absorption, flame resistance compression strength ,cyclic fatigue endurance and especially high retention of tear strength properties after water immersion. Specifically, at 15.5% of filler (coconut fibers and coconut shell powder) content, the PUNFC shows excellent mechanical properties along with advantages of sound absorption. Though increase in filler content increases the sound absorption co-efficient, the mechanical properties remains the same. Also up to 15.5% of the filler content in the PUNFC foam, the processability of the composition is good, and dispersion of fillers is uniform. If the filler content is more than 15.5%, dispersion of the coconut fiber is poor, and agglomeration of fiber is observed. However, increase in the filler content above 15.5% causes decrease in mechanical properties.

Example

S.No Ingredients Wt (gms)
1 Polyol 481
2 Polyisocyanate 259
3 Coconut fibers 96
4 Coconut shell powder 19
5 Wetting agent 3.5
6 Dispersing agent 3.5
Test result comparison of the optimized formulation of PUNFC foam with the
polyurethane foam of the prior art is given above.

Sr.
No Test Units Test Method Flexible
PU
Foam
(Prior
Art) Flexible Polyurethane Natural Fiber Composite
1 Density kg/m3 ASTMD3575 0.145 0.146
2 Tear strength Kg/mm JASO M 305 0.043 0.148
3 Tear strength after water soaking kg/mm M&M Test method 0.018 0.089
4 compression Strength N ASTMD1621 19.0 29.0
5 Tensile
Strength kgf/mm2 ISO 1798 0.75 2.15
6 Water
absorption % ASTMD3575
Suffix L 130.8 158.8
7 Flammability mm/min FMVSS 302 22.70 21.3
8 Dynamic durability Test in Hours M&M Test method 180 243
9 Sound
absorption
coefficientt.at
1500Hz % ASTME1050-08 60.0 72.0
In an embodiment, the PUNFC foam is developed by the combination of other particulate fillers such as rice husk, fly ash, carbon black, wood powder with the bamboo, sisal, banana, kenaf, jute, glass, carbon fibres and the like.
The above mentioned filler combination along with synthetic based polyol and isocyanate combination may be used for reaction injection molding process. The

PUNFC flexible composites can be produced by adding the fillers after or during the polyol and isocyanate reaction.
The developed PUNFC foam product can be used in the vehicle as a finished product, or with over molded polymeric structures, or as an adhesive bonded sandwich structures to meet the performance requirements.
The present invention provide the PUNFC having 15.5 % filler (coconut fibers and coconut shell powder) content which is optimum for having improved mechanical as well as tear strength, tensile strength, sound absorption, flame resistance compression strength ,cyclic fatigue endurance. Above the 15.5 % filler content, decrease in properties observed. The reason for this reduction in property at higher filler content is due to the reduction of coupling between fiber and polyol isocyanides. The same is supported by microscopy data.
Advantages of the present invention
1. The PUNFC foam of the present invention provides tear strength, tensile strength, sound absorption, flame resistance compression strength ,cyclic fatigue endurance as compared to the prior art.
2. The PUNFC foam provides improved mechanical strength and high retention of tear strength properties after water immersion.
The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, to thereby enable others skilled in the art to best utilize the present invention and

various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omission and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the spirit or scope of the present invention.

We Claim
1. A flexible polyurethane natural fiber composites prepared by reaction
injection molding, the flexible polyurethane natural fiber composites
comprising:
polyol in a range between 60-70 % w/w;
polyisocyanate in a range between 30-40 % w/w;
coconut fibers in a range between 11-15 % w/w;
coconut shell powder in a range between 1-2.5 % w/w;
wetting agent in a range between 0.5-1 % w/w; and
dispersing agent in a range between 0.5-1 % w/w,
wherein the polyisocyanate is reacted with polyol and thereafter coconut fibers and the coconut shell powder are added along with wetting agent and dispersing agent during the reaction of the polyisocyanate with the polyol.
2. The flexible polyurethane natural fiber composites as claimed in claim 1, wherein the length of the coconut fiber ranges 3-5 cm with diameter of about 0.05 to 1.5 mm.
3. The.flexible polyurethane natural fiber composites as claimed in claim 1, wherein the coconut shell powder size is in range between 50-250 microns.
4. The flexible polyurethane natural fiber composites as claimed in claim 1, wherein the density of the coconut shell powder is 0.6 to .7 g/cc.
5. The flexible polyurethane natural fiber composites as claimed in claim 1, wherein the polyisocyanate has isocyanate equivalent weight of 481gms.