Mixing method for friction material with a pre-mix in a single mixer
View Patent ↗An improved method of producing a friction material for use in the production of brake pads. A first mixing step blends binder, fiber, and filler materials together in a mixer to create a pre-mix, with one of the materials doubling as a wetting agent promoting the homogeneity of the mixture. A second non-asbestos material is added to the pre-mix in the same mixer, and the two are mixed together to produce the final friction material.
1. A method of producing a friction material, the method comprising:
adding a first non-asbestos material into a single mixer, said first non-asbestos material including a first portion of at least one of a binder material, an abrasive material and a filler material, wherein said at least one of said binder material, said abrasive material, and said filler material includes a wetting agent;
mixing said first non-asbestos material in said single mixer at a first mixing speed;
adding a second non-asbestos material into said single mixer, said second non-asbestos material including a remaining portion of said at least one of said binder material, said abrasive material and said filler material; and
mixing said first and second non-asbestos materials in said single mixer at a second mixing speed, wherein the resulting mixture forms a friction material for a brake pad.
2. The method of claim 1 , wherein said wetting agent is selected from the group consisting of a natural rubber latex, a styrene butadiene rubber latex, a acrylic rubber latex, a silicone rubber latex, a depolymerized rubber, a cashew nut shell liquid based resin, and a liquid phenolic resole resin.
3. The method of claim 1 , wherein said wetting agent is about 0.5% to about 10% by weight of said first and second non-asbestos materials.
4. The method of claim 1 , further comprising adding a chemical curative to said first non-asbestos material.
5. The method of claim 1 , further comprising adding a solvent to said first non-asbestos material to enhance effect of the wetting agent.
6. The method of claim 5 , wherein said solvent is selected from the group consisting of water and an alcohol.
7. The method of claim 1 , further comprising increasing a temperature of said first non-asbestos material.
8. The method of claim 7 , wherein said mixing of said first non-asbestos material in said single mixer at said first mixing speed increases said temperature of said first non-asbestos material.
9. The method of claim 1 , wherein said first mixing speed is greater than said second mixing speed.
10. The method of claim 1 , further comprising drying said first and second non-asbestos materials.
11. The method of claim 10 , wherein said drying includes at least one of adding heat and vacuum drying.
12. A method of producing a friction material comprising:
adding a first non-asbestos material into a single mixer, said first non-asbestos material comprising:
a first portion of a graphite material;
a first portion of a barium sulfate filler material;
a first portion of an antimony sulfide material;
a first portion of an iron oxide abrasive material;
a first portion of a magnesium oxide abrasive material;
a first portion of an iron chromite abrasive material; and
a wetting agent;
mixing said first non-asbestos material in said single mixer at a first mixing speed;
adding a second non-asbestos material into said single mixer, said second non-asbestos material comprising:
a second portion of said graphite material;
a second portion of said barium sulfate filler material;
a second portion of said antimony sulfide material;
a second portion of said iron oxide abrasive material;
a second portion of said magnesium oxide abrasive material;
a second portion of said iron chromite abrasive material;
a phenolic resin material;
a friction dust material;
an aramid pulp material;
a rubber dust material; and
a mineral fiber material; and
mixing said first and second non-asbestos materials in said single mixer at a second mixing speed, wherein the resulting mixture forms a friction material for a brake pad.
13. The method of claim 12 , wherein said wetting agent comprises a depolymerized rubber material.
14. The method of claim 13 , wherein said depolymerized rubber material is about 0.5% to about 10% by weight of said first and second non-asbestos materials.
15. The method of claim 13 , wherein said depolymerized rubber material is about 4% by weight of said first and second non-asbestos materials.
16. The method of claim 12 , wherein said first mixing speed is about equal to said second mixing speed.
17. The method of claim 12 , wherein:
said phenolic resin material is about 18% by volume of said first and second non-asbestos materials;
said friction dust material is about 14% by volume of said first and second non-asbestos materials;
said aramid pulp material is about 7% by volume of said first and second non-asbestos materials;
said graphite material is about 12% by volume of said first and second non-asbestos materials;
said magnesium oxide abrasive material is about 7% by volume of said first and second non-asbestos materials;
said iron chromite abrasive material is about 2% by volume of said first and second non-asbestos materials;
said rubber dust material is about 3% by volume of said first and second non-asbestos materials;
said barium sulfate material is about 22% by volume of said first and second non-asbestos materials;
said mineral fiber material is about 7% by volume of said first and second non-asbestos materials;
said iron oxide abrasive material is about 2% by volume of said first and second non-asbestos materials; and
said antimony sulfide material is about 2% by volume of said first and second non-asbestos materials.