GB2295621A - Brake pads comprising aluminium tripolyphosphate - Google Patents
Brake pads comprising aluminium tripolyphosphate Download PDFInfo
- Publication number
- GB2295621A GB2295621A GB9522433A GB9522433A GB2295621A GB 2295621 A GB2295621 A GB 2295621A GB 9522433 A GB9522433 A GB 9522433A GB 9522433 A GB9522433 A GB 9522433A GB 2295621 A GB2295621 A GB 2295621A
- Authority
- GB
- United Kingdom
- Prior art keywords
- aluminium
- tripolyphosphate
- friction
- brake pads
- brake pad
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 title claims abstract description 23
- 229910052782 aluminium Inorganic materials 0.000 title claims abstract description 23
- 235000019832 sodium triphosphate Nutrition 0.000 title claims abstract description 23
- UNXRWKVEANCORM-UHFFFAOYSA-I triphosphate(5-) Chemical compound [O-]P([O-])(=O)OP([O-])(=O)OP([O-])([O-])=O UNXRWKVEANCORM-UHFFFAOYSA-I 0.000 title claims abstract description 23
- 239000004411 aluminium Substances 0.000 title claims abstract description 20
- 239000011230 binding agent Substances 0.000 claims abstract description 11
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 8
- 239000000571 coke Substances 0.000 claims abstract description 8
- 239000010439 graphite Substances 0.000 claims abstract description 8
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 8
- 239000002783 friction material Substances 0.000 claims description 13
- 239000011248 coating agent Substances 0.000 claims description 8
- 238000000576 coating method Methods 0.000 claims description 8
- 239000000203 mixture Substances 0.000 abstract description 14
- 238000009472 formulation Methods 0.000 abstract description 11
- 239000000843 powder Substances 0.000 abstract description 4
- 239000000463 material Substances 0.000 description 7
- ILRRQNADMUWWFW-UHFFFAOYSA-K aluminium phosphate Chemical compound O1[Al]2OP1(=O)O2 ILRRQNADMUWWFW-UHFFFAOYSA-K 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 5
- 239000002245 particle Substances 0.000 description 3
- 239000011236 particulate material Substances 0.000 description 3
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 239000010425 asbestos Substances 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 229920001568 phenolic resin Polymers 0.000 description 2
- 239000005011 phenolic resin Substances 0.000 description 2
- 229910052895 riebeckite Inorganic materials 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- XGFPOHQJFNFBKA-UHFFFAOYSA-B tetraaluminum;phosphonato phosphate Chemical compound [Al+3].[Al+3].[Al+3].[Al+3].[O-]P([O-])(=O)OP([O-])([O-])=O.[O-]P([O-])(=O)OP([O-])([O-])=O.[O-]P([O-])(=O)OP([O-])([O-])=O XGFPOHQJFNFBKA-UHFFFAOYSA-B 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229940001007 aluminium phosphate Drugs 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229920001971 elastomer Polymers 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 239000011256 inorganic filler Substances 0.000 description 1
- 229910003475 inorganic filler Inorganic materials 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 239000003607 modifier Substances 0.000 description 1
- 239000012766 organic filler Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D69/00—Friction linings; Attachment thereof; Selection of coacting friction substances or surfaces
- F16D69/02—Composition of linings ; Methods of manufacturing
- F16D69/025—Compositions based on an organic binder
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Braking Arrangements (AREA)
Abstract
A brake pad which is bound by an organic binder and contains anhydrous aluminium tripolyphosphate. The aluminium tripolyphosphate is either added to the brake pad formulation as a powder or coated on to graphite or coke included in the formulation.
Description
BRAKE PADS
This invention is concerned with brake pads of the type which comprise a friction material which is formed from particulate material bonded together by an organic binder, eg a phenolic resin and/or a rubber.
Modern brake pads comprise friction material which falls into one of three main categories, these categories being "semi-metallic" materials, "low steel" materials, and "non-asbestos organic" materials. All of these materials are formed by introducing particulate material which includes an organic binder into a die cavity, pressing the material in the cavity to form a block, and curing the binder. This invention is applicable to brake pads having friction material in the semi-metallic category and may be applicable to brake pads having friction material in the low steel or non-asbestos categories.
The friction material of a brake pad bonded by an organic binder may contain a wide variety of friction modifiers and organic and inorganic fillers, the exact formulation being selected for the particular circumstances in which the brake pad is to be utilised. Formulations are usually selected to give the maximum coefficient of friction, to cause the minimum disc wear and, in some cases, to give low fade, fade being the fall off in performance of the pad at high temperatures which is particularly important for racing applications.
It is an object of the present invention to provide a brake pad comprising friction material bonded by an organic binder which has an increased coefficient of friction and causes reduced disc wear.
The invention provides a brake pad comprising friction material bonded by an organic binder, characterised in that the friction material contains anhydrous aluminium tripolyphosphate.
It is found that brake pads according to the invention have an increased coefficient of friction, cause less disc wear and, surprisingly, have reduced fade. The Applicants made this discovery while attempting to increase the coefficient of friction of a brake pad containing coke and graphite. The Applicants speculated that coating the coke and/or the graphite with an oxidation-resistant coating would increase the coefficient of friction of the material.
An oxidation-resistant coating was achieved by mixing the particles with an aqueous solution of aluminium orthophosphate, driving off the water, and heat treating at 3000C. The heat treatment caused the aluminium orthophosphate to polymerise into aluminium tripolyphosphate which coated the particles. It was found that this coating did indeed lead to an increased coefficient of friction but, surprisingly, also lead to reduced disc wear and reduced fade. These results lead the Applicants to add aluminium tripolyphosphate as a separate ingredient, ie not as a coating, and even better results were achieved.
Accordingly, the aluminium tripolyphosphate may be added as a coating on coke or graphite or as a separate particulate material. Aluminium tripolyphosphate exists in an anhydrous form and a dihydrous form. The anhydrous form gives the advantages gives the advantages mentioned above but the dihydrous form alone does not. However, the presence of the dihydrous form as well as the anhydrous form does not prevent the advantages from being obtained.
Indeed, an approximately 50:50 mix of the two forms is found to give the advantages.
The Applicants are aware that aluminium phosphate (Al(H2PO4) 3) has been suggested as an inorganic binder for brake pads (which are not bonded by an organic binder) and has been suggested as a constituent of solid lubricants for use in clutch facings or friction materials of brake pads.
They are not aware, however, of any use of aluminium tripolyphosphate (AlH2P30lo) in friction materials of brake pads.
The aluminium tripolyphosphate is preferably present in at least 1% by volume since below that percentage only small effects are achieved. Percentages in the range 1 to 20% by volume have been found to be advantageous.
There now follow two examples which are illustrative of the invention.
In the first illustrative example, aluminium tripolyphosphate was prepared by heating mono-aluminium orthophosphate to over 300 cm. The heating caused the aluminium tripolyphosphate to change into aluminium pyrophosphate (this occurred between 225 and 2900C).
Further heating caused the aluminum pyrophosphate to change into aluminum tripolyphosphate (this occurred above 2900C).
The aluminum tripolyphosphate was ground and added as a powder to a conventional brake pad formulation of the semi-metallic type. The powder was found (by testing a sample) to be an approximately 50:50 mix of the anhydrous and dihydrous forms of aluminium tripolyphosphate. The powder was added as 12% by volume based on the total volume of the formulation. The formulation also contained iron, graphite, coke, other conventional fillers, and phenolic resin binder. The formulation was pressed into brake pads, and the resin was cured.
In the second illustrative example, the same formulation was used as in the first illustrative example, the only difference being that the aluminum tripolyphosphate was coated on to the coke and graphite before those materials were incorporated into the formulation. The coating was achieved by mixing the particles of coke and graphite with an aqueous solution of aluminium orthophosphate, driving off the water, and heat treating at 300 C. The heat treatment caused the aluminium orthophosphate to go through the same changes described above in the first illustrative example to become aluminium tripolyphosphate (approximately a 50:50 mix of anhydrous and dihydrous forms).
Brake pads from the first and second illustrative examples and brake pads of the same formulation but not containing aluminium tripolyphosphate were subjected to tests. The pads with no aluminium tripolyphosphate were found to have an initial coefficient of friction of 0.4.
In a fade test, the coefficient of friction dropped from 0.37 to 0.32. During the tests, the disc against which the pad ran lost 0.44 mm due to wear. The pads from the second illustrative example had an initial coefficient of friction of 0.46. In the fade test, the coefficient of friction dropped from 0.40 to 0.39. The disc loss was 0.16 mm. The pads from the first illustrative example had an initial coefficient of friction of 0.53. In the fade test, the coefficient of friction remained at 0.46. The disc loss was 0.096 mm.
Claims (5)
1 A brake pad comprising friction material bonded by an
organic binder, characterised in that the friction
material contains anhydrous aluminium
tripolyphosphate.
2 A brake pad according to claim 1, characterised in
that the aluminium tripolyphosphate is present as a
coating on graphite or coke contained in the friction
material.
3 A brake pad according to either one of claims 1 and 2,
characterised in that the aluminium tripolyphosphate
is present in at least 1% by volume.
4 A brake pad according to claim 3, characterised in
that the aluminium tripolyphosphate is present in
between 1% and 20% by volume.
5 A brake pad substantially as hereinbefore described
with reference to the first or the second illustrative
example.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9522433A GB2295621A (en) | 1994-12-01 | 1995-11-02 | Brake pads comprising aluminium tripolyphosphate |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9424249A GB9424249D0 (en) | 1994-12-01 | 1994-12-01 | Brake pads |
| GB9522433A GB2295621A (en) | 1994-12-01 | 1995-11-02 | Brake pads comprising aluminium tripolyphosphate |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9522433D0 GB9522433D0 (en) | 1996-01-03 |
| GB2295621A true GB2295621A (en) | 1996-06-05 |
Family
ID=26306069
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9522433A Withdrawn GB2295621A (en) | 1994-12-01 | 1995-11-02 | Brake pads comprising aluminium tripolyphosphate |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2295621A (en) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62237127A (en) * | 1986-04-08 | 1987-10-17 | Onoda Cement Co Ltd | Friction material |
| EP0488159A2 (en) * | 1990-11-28 | 1992-06-03 | Akebono Brake Industry Co., Ltd. | Non-asbestos friction material |
-
1995
- 1995-11-02 GB GB9522433A patent/GB2295621A/en not_active Withdrawn
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62237127A (en) * | 1986-04-08 | 1987-10-17 | Onoda Cement Co Ltd | Friction material |
| EP0488159A2 (en) * | 1990-11-28 | 1992-06-03 | Akebono Brake Industry Co., Ltd. | Non-asbestos friction material |
Non-Patent Citations (1)
| Title |
|---|
| Derwent WPI Abstract Accession No.87-331387/47 & JP 62 237127 A * |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9522433D0 (en) | 1996-01-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |