Composite Friction Lining Material

Abstract

The present invention relates to a composite friction lining material comprising a friction mix and a binder resin, wherein the binder resin comprises a carbohydrate based binder resin, the carbohydrate based binder resin being obtained from a carbohydrate component and a cross-linker, wherein the cross-linker is selected from ammonium salts of inorganic acid, carboxylic acids, salts, for example ammonium salts thereof, ester or anhydride derivatives thereof, an amine component and/or combinations thereof.

Claims

1. A composite friction lining material comprising a friction mix and a binder resin, wherein the binder resin comprises a carbohydrate based binder resin, the carbohydrate based binder resin being obtained from a carbohydrate component and a cross-linker, wherein the cross-linker is selected from ammonium salts of inorganic acid, carboxylic acids, salts, for example ammonium salts thereof, ester or anhydride derivatives thereof, an amine component and/or combinations thereof.

2. The composite friction lining material of claim 1 wherein the carbohydrate based binder resin is a polyester type resin binder obtainable from a carbohydrate component and compounds bearing carboxylic acid functional groups, or anhydride or salt derivatives thereof.

3. The composite friction lining material of claim 2 wherein the carboxylic acid functions bearing compound is selected from monocarboxylic acids as well as polycarboxylic acids, salts and anhydride derivatives thereof, the “polycarboxylic acid” being a dicarboxylic, tricarboxylic, tetracarboxylic, pentacarboxylic, or a monomeric polycarboxylic acid, as well as a polymeric polycarboxylic acid, and combinations thereof.

4. The composite friction lining material of claim 1 wherein the carbohydrate based binder resin is a melanoïdin type resin binder obtainable from a carbohydrate and a nitrogenous cross-linker, wherein the carbohydrate component includes one or more reducing sugars, such as a monosaccharide in its aldose or ketose form, including a triose, a tetrose, a pentose, a hexose, or a heptose, or yields one or more reducing sugars in situ under thermal curing conditions; or a polysaccharide; or combinations thereof, and wherein the nitrogenous cross-linker is selected from ammonium salts of inorganic acid, ammonium salts of carboxylic acids, ester or anhydride derivatives thereof, amine components or salts thereof, and/or combinations thereof.

5. The composite friction lining material of claim 4 wherein the inorganic acid is selected from phosphoric, sulphuric, nitric and carbonic acid.

6. The composite friction lining material of claim 4 wherein the amine component is selected from polyamine functional compounds comprising primary and/or secondary amine functional groups, such as a polyamine having the formula of H.sub.2N-Q-NH.sub.2, wherein Q is an alkyl, cycloalkyl, heteroalkyl, or cycloheteroalkyl, each of which may be optionally substituted, polyethyleneimine (PEI), polyninyl amine, polyether amine, polylysine or linear or branched polyetheramines, carbamates or amino acids or proteins.

7. The composite friction lining material of claim 1 wherein the dry weight ratio of carbohydrate component to cross-linker ranges from 2 to 20, preferably from 2 to 15, more preferably from 2.5 to 10.

8. The composite friction lining material of claim 1 further comprising a different resin, such as a phenolformaldehyde resin or other resin known in the art.

9. The composite friction lining material of claim 1 further comprising one or more adjuvants, for example coupling agents, waxes, dyes, release agents, antifungal and/or antibacterial agents, formaldehyde scavengers, hydrophobes, catalysts, anti-caking additives, lubricants, such as fumed silica, dedusting oils, flame retardants, fillers and/or other additives currently used in binder compositions.

10. A process for the manufacture of a composite friction lining material, comprising intimately mixing the binder components of the binder composition and particulate materials of the friction mix, subjecting the mixture to heat in order to promote the reaction between the components of the binder composition and allowing for curing of the reaction product obtained.

11. A brake pad, brake shoe or clutch disc comprising a composite friction lining material according to claim 1.

Description

EXAMPLE 1

[0036] A commonly used standard friction mix has been mixed with binder compositions exemplified below. [0037] Solid compositions: [0038] Solid binder compositions were prepared from dextrose monohydrate or 50/50 combinations of dextrose monohydrate and fructose or 34/51 combinations of dextrose monohydrate and sucrose, and ammonium sulphate or diammonium phosphate or 15/7.5 combinations of ammonium sulphate and diammonium phosphate. The solid compositions were ground together in an appropriate mill or grinder.

TABLE-US-00001 Sample DMH Fructose Sucrose AS DAP Nbre 80 85 15 Nbre 82 42.5 42.5 15 Nbr 84 85 15 Nbr 85 34 51 15 Nbr 86 77.5 15 7.5 Nbr 87 77.5 22.5
DMH stands for dextrose monohydrate
AS stands for ammonium sulphate
DAP stands for diammonium phosphate
The numbers are shown in w % of the total weight of the binder composition.

[0039] Liquid Compositions:

[0040] The liquids were heated to dissolve in the appropriate quantity of water.

TABLE-US-00002 sample DMH Fructose HMDA AS TAC DAP Nbre 53 42.5 42.5 15 Nbre 54 42.5 42.5 15 Nbre 55 42.5 42.5 15 Nbre 56 42.5 42.5 15 Nbre 70 40 40 20
HMDA stands for hexamethylene diamine
TAC stands for triammonium citrate
The compositions showed active solids concentrations of 73.9, 76.9, 75.0, 75.6 and 77.6, respectively, thus meeting the viscosity requirement close to a maximum of 500 cP at 25° C. (Brookfield DVII+Pro viscometer with small sample adapter).

[0041] The above solid binder compositions and liquid binder compositions may be used as such or in combination with one another. Combinations of liquid and solid binder compositions may advantageously vary from 5/95 to 50/50.

[0042] Alternatively, said formulations, more specifically the liquid formulations may be combined with a phenol formaldehyde based binder composition, for example a solid phenol formaldehyde binder composition or other binder resin known in the art.

[0043] The resinated friction mix may then be molded as desired for a brake pad or brake shoe and subjected to curing under temperature and pressure conditions as required.

[0044] The quality of friction lining is assessed on the basis of coefficient of friction, wear, wear of counter (friction) surface, and temperature dependence of these. Brake pads also need to be water resistant and maintain their brake force under wet conditions. Tests with relevant brake pads prepared as described above from a standard friction mix have shown results comparable to corresponding materials bonded with phenol based binder resin.

EXAMPLE 2: CURED BINDER ANALYSIS

[0045] Binder resin obtained by reacting (i) dextrose monohydrate with monoammonium phosphate and (ii) dextrose monohydrate with diammonium phosphate was subjected to a temperature resistance test.

[0046] The tested binder recipes were as follows: [0047] Binder 1: 20.13 parts dextrose monohydrate (at 90.9%); 11.70 parts monoammoniumphosphate (at 98%) in 18.17 parts water [0048] Binder 2: 24.09 parts dextrose monohydrate (at 90.9%); 8.10 parts diammoniumphosphate (at 99%) in 17.81 parts water

[0049] The liquid components were dissolved in an appropriate amount of water. The components were allowed to cure to form the relevant resin samples.

[0050] The resin samples were placed in a standard Thermogravimetric Analysis (TGA) analytical instrument and weight loss of the resin samples was measured while ramping the temperature at a rate of 10° C. per minute, under nitrogen atmosphere, as is common for testing phenolic resins and refractories. As can be seen from the graph of FIG. 1, the carbohydrate-based resin samples resist well to high temperatures. It has surprisingly been found that their temperature resistance is as good as or at least comparable to that of a commonly used PF resin.

EXAMPLE 3

[0051] A similar test was performed with the following binder compositions:

TABLE-US-00003 Ratio Dextrose Citric ac Ammonia DAP DMH/CA or Binder MH 90.9% MH 91.4% 25% 98% DMH/DAP A 99.0 10.9 12.8 90/10 B 99.0 4.0 10.2 90/10 C 93.5 16.4 19.2 85/15 D 93.5 19.2 15.3 85/15
The binder compositions were allowed to cure and prepared in binder resin samples. On the graph of FIG. 2, the temperature behaviour (loss of weight) by temperature ramp up at 10° C./min, under nitrogen atmosphere, of Binder A is shown in dotted line; Binder B in dashed line; Binder C in solid line and Binder D in dashdotted line. Again, it has been surprisingly found that the tested resins behave very well under such temperature conditions, similarly to phenolic binders.