DESC:FIELD OF INVENTION
The present invention relates to a braking system consisting of brake shoe and brake lining riveted together for use in vehicles. Particularly, the present invention relates to a non-asbestos brake lining composition without recycled materials and more particularly to non-asbestos composite layer composition, which exhibits high strength and good friction performance suitable for servicing up to durability of the brake lining.

BACKGROUND OF INVENTION
Generally brake shoe is a part of a braking system which carries a brake lining in a drum brake used on a vehicle. The brake shoe carries the brake lining, which is riveted or glued to the brake shoe. When the brake is applied, the brake shoe moves and presses the brake lining against the inside of the drum, friction generated between the brake lining and the drum provides the braking effort. The brake linings are composed of a relatively soft but tough and heat-resistant material with a high coefficient of dynamic friction, which is mounted to a solid metal backing using high-temperature adhesives or rivets. The complete assembly including the brake lining and the solid metal backing is then often called a brake shoe.

Since the brake lining is the portion of the braking system which converts vehicle's kinetic energy into heat, the brake lining must be capable of surviving high temperatures without excessive wear leading to frequent replacement or out gassing which causes brake fade and a decrease in the stopping power of the brake. Conventionally, asbestos based brake linings are used as friction material for vehicles such as bus, trucks, trailers, tippers for speed control and stopping the vehicle. High dosage of the asbestos in a product gives very high strength to the matrix.

Due to health concerns on usage of asbestos, non-asbestos brake linings are used. The conventional non-asbestos composition includes fibers, fillers, abrasives, lubes and within each type, two or multiple materials are added to meet the functional requirement of the friction material which otherwise are largely contributed by one material asbestos which has multifunctional property in a friction material.

The conventional non-asbestos brake lining composition which are generally lower in strength compared to asbestos based brake lining, during retro fitment to brake shoes by using rivet leads to cracks due to improper surface on the shoe plate or improper riveting forces which results in performance issues including rivet hole enlargement when said cracked liners are continued in service.

Although conventional non-asbestos composition has better friction performance and gives more stable friction at higher temperature in service than asbestos based composition, deterioration in service due to cracks etc. during retro fitment leads to premature removal before end of product life. The conventional non-asbestos composition has more of fillers than fibrous materials and hence its matrix is structurally weak though functionally good and meets the performance requirement of friction and wear.

Some of the prior arts are:
US20140190777 discloses using a recycled friction material and a fresh mix of friction material to form a multilayered brake lining with each layer being formed in a wavelike irregular pattern of crest and trough to give good resistance to shear generated during braking action and the product thus has varying density to give improved friction performance through low density material and low wear through high density material.

US20130228403 discloses a non-asbestos frictional material composition containing a binder, an organic filler, an inorganic filler, and a fiber base material includes: copper in a content of 5 mass % or less as a copper element; a metal fiber other than a copper fiber and a copper alloy fiber in a content of 0.5 mass % or less; and mica and graphite with a particle size of 90 µm or less but not containing graphite with a particle size of more than 90 µm.

US20070117881 discloses a non-asbestos friction member provided with a friction material containing a thermosetting resin binder, reinforcing fibers, and a friction modifier is integrally formed with a pressure plate. The friction material has a first layer friction material on a side of a friction surface and a second layer friction material on a side of the pressure plate. A pre-mix containing an elastomer and a cross-linker is blended in the second layer friction material. The premix preferably contains fibers, and the premix preferably contains 10 to 97 vol % of an elastomer blended therewith. The disadvantage of the friction material is the pressure plate support is required for making the friction material. Also, an adhesive is used for bonding of pressure plate to friction material.

CN1258050 discloses an automobile high-strength non-asbestos brake friction plate, characterized in that: it is a polymer compound as a binder to, inorganic and organic fibers as a reinforcing component to the friction properties of the filler or with the modifier agent, components and weight percentages as follows: two metal-modified phenolic resin fibers 8-25% 3-10% 10-30% organic fibers mineral fibers 8-18%, 5-15% graphite, barium sulfate, 8-18% alumina 1- obtained after the double-modified phenolic resin is a phenolic resin to the styrene-butadiene rubber and terephthaloyl mixed amine diacetate roll mill; 5% filler margin.

KR1020050078707 discloses a non-asbestos friction material which is obtained by molding and heat treating a composition comprising: non-asbestos fibers, 14-20 vol% of a binder, 1.5-3 vol% of zircon, 13-18 vol% of cashew dust, a solid lubricant and inorganic fillers. Particularly, the non-asbestos fiber is selected from the group consisting of organic fiber, glass fiber, ceramic fiber, metal fiber and mixtures thereof. The non-asbestos friction material may further comprise magnesium oxide or iron oxide (Fe3O4).

Known in the prior art is incorporating metallic fibers such as steel fiber into brake lining composition to increase the mechanical strength and performance of brake lining but suffers from following disadvantages such as noise during brake applications due to metal to metal contact with mating part and higher density leading to more input weight which results in reduced fuel efficiency of vehicle, higher product cost etc.

Another known in the prior art is adding inorganic fibers like glass, ceramic, mineral etc., which are common in non-asbestos composition to provide good mechanical strength to the matrix and does not significantly increase the product density. However, said inorganic fibers have a high moh hardness of 6 to 7 and hence have limitations of higher dosage to get high strength and because high dosage leads to more wear debris which are generated during every brake application, which affects braking performance due to third layer formation between friction material and mating surface.

Accordingly, there exists a need for a non-asbestos brake lining composition without recycled materials, which exhibits good friction performance suitable for servicing up to durability of the brake lining.

OBJECTS OF INVENTION
One or more of the problems of the conventional prior art may be overcome by various embodiments of the system and method of the present invention.

It is the primary object of the present invention to provide a non-asbestos brake lining composition without recycled materials, which exhibits good friction performance suitable for servicing up to durability of the brake lining.

It is another object of the present invention to provide a non-asbestos composite layer composition, which exhibits high strength and good friction performance suitable for servicing up to durability of the brake lining.

It is another object of the present invention, wherein the non-asbestos brake lining overall composition comprising of:
Composite layer of high strength- upto 40% by volume; and
Friction layer- upto 60% by volume.

It is another object of the present invention, wherein the high strength composite layer composition further comprising of:
Inorganic fiber-5% to 50% by mass of the composite layer;
Inorganic filler-5% to 40% by mass of the composite layer; and
Common binder-5% to 20% by mass of the composite layer,
wherein the inorganic fiber includes but not limited to glass,
wherein the inorganic filler consisting of calcite 0% to 40%; wollastonite 0% to 40%, and vermiculite 0% to 20%, and
wherein the common binder is resin.

It is another object of the present invention, wherein the composite layer and friction layer are integrally molded together in-situ under pre-defined temperature and pressure for a pre-defined period of time using the resin to form a single piece brake lining.

SUMMARY OF INVENTION
Thus according to the basic aspect of the present invention there is provided a non-asbestos brake lining composition comprising of:
Composite layer of high strength- upto 40 % by volume; and
Friction layer- upto 60% by volume,
wherein the high strength composite layer composition further comprising of:
Inorganic fiber-5% to 50% by mass of the composite layer;
Inorganic filler-5% to 40% by mass of the composite layer; and
Common binder-5% to 20% by mass of the composite layer.

It is another aspect of the present invention, wherein the inorganic fiber includes but not limited to glass.

It is another aspect of the present invention, wherein the inorganic filler consisting of calcite 0% to 40%; wollastonite 0% to 40%, and vermiculite 0% to 20%.

It is another aspect of the present invention, wherein the common binder is resin.

It is another aspect of the present invention, wherein the inorganic fiber has aspect ratio greater than 100 to enhance strength of the composite layer.

It is another aspect of the present invention, wherein the composite layer and friction layer are integrally molded together in-situ under pre-defined temperature and pressure for a pre-defined period of time using the resin to form a single piece brake lining.

It is another aspect of the present invention, wherein the resin for both composite layer and friction layer ensures completeness of chemical reaction, uniform cross linking and same type of chemical bonding between the two compositions/layers without need for higher cure time during manufacture of the brake lining.

It is another aspect of the present invention, wherein the resin includes but not limited to straight phenolic or phenolics modified with acrylic, Nitrile Butadiene Rubber (NBR), Cashew, Epoxy, and Silicones etc.

It is another aspect of the present invention, wherein brake lining resulting from said composition is cured with or without hexamine under pre-defined high temperature and pressure.

DETAILED DESCRIPTION OF THE INVENTION
The present invention as discussed hereinbefore relates to a non-asbestos brake lining composition and more particularly to non-asbestos composite layer composition, which exhibits high strength and good friction performance suitable for servicing up to durability of the brake lining.

The non-asbestos brake lining composition comprising of composite layer of high strength-upto 40% by volume and friction layer – upto 60% by volume. The non-asbestos brake lining overall composition further comprising of inorganic fiber-5% to 25%; organic fiber-upto 5%; organic filler-upto 10%; abrasive-upto 10%; wear modifier-upto 12%; common binder-5% to 20%; and inorganic filler consisting of calcite-10% to 40%, wollastonite-5% to 25%, and vermiculite-5% to 15%. The organic filler particles is used without coating or coated with liquid polymers for improved performance as a friction material.
The high strength composite layer composition further comprising of inorganic fiber-5% to 50% by mass of the composite layer; inorganic filler-5% to 40% by mass of the composite layer; and common binder-5% to 20% by mass of the composite layer, said common binder is resin. The common binder includes but not limited to powder binders or liquid binders. The common binder includes but not limited to straight phenolic or phenolics modified with acrylic, Nitrile Butadiene Rubber (NBR), cashew, epoxy, and silicones etc. The inorganic fiber includes but not limited to glass and the inorganic filler consisting of calcite 0% to 40%, wollastonite 0% to 40%, and vermiculite 0% to 20%. The inorganic fiber has aspect ratio greater than 100 to enhance strength of the composite layer.

The composite layer and friction layer are integrally molded together in-situ under pre-defined temperature and pressure for a pre-defined period of time using the resin to form a single piece brake lining. The high strength of the composite layer is achieved using high dosage of the fibers which may affect friction property directly when used at high dosages in a friction material but compliments the friction layer performance with increased strength in the composite layer. The resin is common type for both composite layer and friction layer which ensures completeness of chemical reaction, uniform cross linking and same type of chemical bonding between the two compositions/layers without need for higher cure time during manufacture of the brake lining. The common type of binder for both composite layer and friction layer helps to overcome thermal stresses at bond layer and behaves as a single brake lining. The brake lining resulting from said composition is cured with or without hexamine under pre-defined high temperature and pressure.

The high strength of the composite layer helps to improve the durability of the brake lining without quality performance issue such as cracks during riveting, or rivet hole enlargement in service leading to liner loosening etc., that are predominant failure modes in the non-asbestos brake lining due to weak matrix.

The test results showing the technical effects of the present invention are annexed as Annexure-A- Summary of trials conducted with high strength composite material/layer and confirmation on the efficacy of the improvement. The efficacy of improvement from the invention as illustrated in Annexure A is an illustrative example of the invention.

Although particular components and materials are specifically identified herein, one skilled in the art may readily substitute the components and/or materials of similar function without departing from the invention as defined in the appended objects. Therefore, the above should not be construed as limiting the invention, which is defined by the appended objects.

The embodiments of the invention been disclosed in detail in this specification are purely for illustrative purposes and the present invention can be embodied in many other forms or carried out in other ways, without departing from the spirit or essential characteristics thereof. It is understood that the invention is not limited thereto, but is susceptible of numerous changes and modifications as known to those skilled in the art, and all such variations or modifications lies within the scope of the present invention.
,CLAIMS:WE CLAIM:
1. A non-asbestos brake lining composition comprising of:
Composite layer of high strength-upto 40% by volume; and
Friction layer-upto 60% by volume,
wherein the high strength composite layer composition further comprising of:
Inorganic fiber-5% to 50% by mass of the composite layer;
Inorganic filler-5% to 40% by mass of the composite layer; and
Common binder-5% to 20% by mass of the composite layer.

2. The non-asbestos brake lining composition as claimed in claim 1, wherein the inorganic fiber includes but not limited to glass.

3. The non-asbestos brake lining composition as claimed in claim 1, wherein the inorganic filler consisting of calcite-0% to 40%; wollastonite-0% to 40%, and vermiculite-0% to 20%.

4. The non-asbestos brake lining composition as claimed in claim 1, wherein the common binder is resin.

5. The non-asbestos brake lining composition as claimed in claim 2, wherein the inorganic fiber has aspect ratio greater than 100 to enhance strength of the composite layer.

6. The non-asbestos brake lining composition as claimed in anyone of claims 1 to 5, wherein the composite layer and friction layer are integrally molded together in-situ under pre-defined temperature and pressure for a pre-defined period of time using the resin to form a single piece brake lining.

7. The non-asbestos brake lining composition as claimed in claim 6, wherein the resin for both composite layer and friction layer ensures completeness of chemical reaction, uniform cross linking and same type of chemical bonding between the two compositions/layers without need for higher cure time during manufacture of the brake lining.

8. The non-asbestos brake lining composition as claimed in claim 7, wherein the resin includes but not limited to straight phenolic or phenolics modified with acrylic, Nitrile Butadiene Rubber (NBR), Cashew, Epoxy, and Silicones etc.

9. The non-asbestos brake lining composition as claimed in claim 1, wherein brake lining resulting from said composition is cured with or without hexamine under pre-defined high temperature and pressure.