FRICTION MATERIAL

Abstract

[Object]

To provide the friction material for the disc brake pad such as an automobile, which is manufactured by forming the NAO friction material composition, enabling to restrain the brake vibration during braking in a high temperature.

[Means to Resolve]

In the friction material, which is manufactured by forming the NAO friction material composition that does not contain the copper component but contains the binder, the fiber base, the organic friction modifier, the inorganic friction modifier, and the lubricant, the friction material composition contains 5-9 weight % of the binder relative to the entire amount of the friction material composition, 1-4 weight % of the silicone rubber modified phenol resin as a part of the binder relative to the entire amount of the friction material composition, 1-4 weight % of a cashew dust as the organic friction modifier relative to the entire amount of the friction material composition, 0.5-3 weight % of a fused silica with the average particle diameter of 15-40 μm as the inorganic friction modifier relative to the entire amount of the friction material composition, and 0.1-2 weight % of the electromelting zirconium silicate beads with the average particle diameter of 10-30 μm as the inorganic friction modifier relative to the entire amount of the friction material composition.

Claims

1. A friction material for a disc brake pad, which is manufactured by forming a Non-Asbestos-Organic (NAO) friction material composition that does not contain a copper component but contains a binder, a fiber base, an organic friction modifier, an inorganic friction modifier, and a lubricant, wherein said friction material composition contains 5-9 weight % of the binder relative to the entire amount of the friction material composition, 1-4 weight % of a silicone rubber modified phenol resin as a part of the binder relative to the entire amount of the friction material composition, 1-4 weight % of a cashew dust as the organic friction modifier relative to the entire amount of the friction material composition, 0.5-3 weight % of a fused silica with an average particle diameter of 15-40 μm as the inorganic friction modifier relative to the entire amount of the friction material composition, and 0.1-2 weight % of an electromelting zirconium silicate beads with an average particle diameter of 10-30 μm as the inorganic friction modifier relative to the entire amount of the friction material composition.

2. The friction material according to claim 1, wherein said friction material composition contains 1-4 weight % of a resilient graphite cokes as the lubricant relative to the entire amount of the friction material composition.

Description

EMBODIMENTS OF THE INVENTION

[0029] This invention relates to the NAO friction material composition that does not contain the copper component but contains the binder, the fiber base, the organic friction modifier, the inorganic friction modifier, and the lubricant, which contains 5-9 weight % of the binder relative to the entire amount of the friction material composition, 1-4 weight % of the silicone rubber modified phenol resin as a part of the binder relative to the entire amount of the friction material composition, 1-4 weight % of the cashew dust as the organic friction modifier relative to the entire amount of the friction material composition, 0.5-3 weight % of the fused silica with an average particle diameter of 15-40 μm as the inorganic friction modifier relative to the entire amount of the friction material composition, and 0.1-2 weight % of the electromelting zirconium silicate beads with an average particle diameter of 10-30 μm as the inorganic friction modifier relative to the entire amount of the friction material composition.

<Binder, Silicone Rubber Modified Phenol Resin>

[0030] Adding the silicone rubber modified phenol resin as a part of the binder can enlarge the amount of a high compressibility. When the thickness difference due to the irregular adhesion of the film of the tar-like substance on the friction surface of the disc rotor occurs, if the amount of the high compressibility is large, the friction material follows and ultimately adjusts the thickness difference, so that the attachment or the contact between the friction material and the friction surface of the disc rotor becomes even, which restrains the brake vibration.

[0031] The amount of the binder contained in the friction material composition relative to the entire friction material composition is 5-9 weight %, and the amount of the silicone rubber modified phenol resin contained in the friction material composition relative to the entire friction material composition is 1-4 weight %. However, the amount of the binder contained in the friction material composition relative to the entire friction material composition is preferably 6-8 weight %, and the amount of the silicone rubber modified phenol resin contained in the friction material composition relative to the entire friction material composition is preferably 2-3 weight %. If the amount of the binder contained in the friction material composition is less than 5 weight % relative to the entire amount of the friction material composition, a sufficient wear resistance cannot be obtained, and if the amount of the binder contained in the friction material composition is over 9 weight % relative to the entire amount of the friction material composition, a sufficient fading resistance cannot be obtained.

[0032] Also, the amount of the silicone rubber modified phenol resin contained in the friction material composition is less than 1 weight % relative to the entire amount of the friction material composition, a sufficient inhibitory effect cannot be obtained, and if the amount of the silicone rubber modified phenol resin contained in the friction material composition is over 4 weight %, a fading resistance is reduced.

[0033] For the binders other than the silicone rubber modified phenol resin, either one of binders that are generally used for the friction material such as a straight phenol resin, a cashew oil modified phenol resin, an acrylic rubber modified phenol resin, a nitrile rubber (NBR) modified phenol resin, a phenol aralkyl resin (aralkyl modified phenol resin), or a fluoropolymer dispersed phenol resin, or a combination of two or more of the above-identified binders may be used.

<Cashew Dust>

[0034] As the amount of cashew dust as the organic friction modifier added to the friction material composition is reduced to a relatively small amount, a favorable braking effectiveness can be achieved while the generation of the tar-like substance during braking in a high speed is being restrained.

[0035] The amount of the cashew dust added to the friction material composition relative to the entire amount of the friction material composition is preferably 1-4 weight % and is preferably 1.5-2 weight %.

[0036] If the amount of the cashew dust added to the friction material composition relative to the entire amount of the friction material composition is less than 1 weight %, the braking effectiveness becomes insufficient, and if the amount of the cashew dust added to the friction material composition relative to the entire amount of the friction material composition is over 4 weight %, the tar-like substance transfers to irregularly adhere to the friction surface of the disc rotor during braking in a high speed, which tends to cause the brake vibration.

<Fused Silica, Electromelting Zirconium Silicate Beads>

[0037] As the predetermined amount of the fused silica with the average particle diameter of 15-40 μm and the predetermined amount of the electromelting zirconium silicate beads with the average particle diameter of 10-30 μm, both as the inorganic friction modifiers, are added to the friction material composition, the film of the tar-like substance formed on the friction surface can be cleaned moderately without over grinding the friction surface of the mating member, and therefore the occurrence of the brake vibration due to the irregular transfer and adherence of the tar-like substance to the friction surface can be prevented.

[0038] The amount of the fused silica with the average diameter of 15-40 μm added to the friction material composition relative to the entire amount of the friction material composition is 0.5-3 weight %, and the amount of the electromelting zirconium silicate beads with the average diameter of 10-30 μm added to the friction material composition relative to the entire amount of the friction material composition is 0.1-2 weight %. The amount of the fused silica with the average diameter of 15-40 μm added to the friction material composition relative to the entire amount of the friction material composition is preferably 1-2 weight %, and the amount of the electromelting zirconium silicate beads with the average diameter of 10-30 μm added to the friction material composition relative to the entire amount of the friction material composition is preferably 0.2-1 weight %.

[0039] In this invention, the average particle diameters represent 50% of the particle diameters measured by a Laser Diffraction Particle Size Analyzer.

[0040] Also, the fused silica is a silica particle made by melting pulverized raw silica rocks in a high-temperature flame to spheroidize by a surface tension. As the fused silica, a product such as Silica FB Series by Denka Co., Ltd. may be used.

[0041] Also, the electromelting zirconium silicate beads is a beads-shaped zirconium silicate that is manufactured by resolving a crystalline zirconia and an amorphous silicon oxide by an electromelting method. For the electromelting zirconium silicate beads, a product such as Micro Blast Series by Sait-Gobain Co., Ltd. may be used.

<Resilient Graphitic Carbon>

[0042] Furthermore, in this invention, it is preferable to add 1-4 weight % of a resilient graphitic carbon as the lubricant relative to the entire amount of the friction material composition.

[0043] As 1-4 weight % of the resilient graphitic carbon relative to the entire friction material composition is added to the friction material composition, the amount of the high compressibility increases, which improves the inhibitory effect of the brake vibration.

[0044] The resilient graphitic carbon is a carbon obtained through a process of expanding and foaming a carbon material made of either a carbon mesophase or cokes and then graphitizing at 1900-2700 centigrade to achieve the graphitization degree of 80-95% measured by the X-ray diffraction, which has a characteristic of a large recovery ratio of the volume when the load is removed after applying a compressive load. For the resilient graphitic carbon, a product such as RGC Series by Superior Graphite may be used.

<Other Components>

[0045] The friction material of this invention is made from the friction material composition containing materials that are normally used in the friction material such as the fiber base, the lubricant, the organic friction modifier, the inorganic friction modifier, the pH modifier, and the filler other than the binder, the cashew dust, the fused silica with the average particle diameter of 15-40 μm, the electromelting zirconium silicate beads with the average particle diameter of 10-30 μm, and the resilient graphitic carbon.

[0046] For the fiber base, either one of organic fibers that are generally used in the friction material such as an aramid fiber, a cellulose fiber, a polyparaphenylene benzobisoxazole fiber, and an acrylic fiber, or metallic fibers that are generally used for the friction material such as an aluminum fiber, an aluminum alloy fiber, and a zinc fiber, or a combination of two or more of the above-listed organic fibers or metallic fibers may be used.

[0047] The amount of the fiber base contained in the friction material composition relative to the entire amount of the friction material composition is preferably 1-5 weight % and is more preferably 1.5-3 weight %.

[0048] For the organic friction modifier, other than the above-described cashew dust, either one of the organic friction modifiers that are generally used in the friction material such as a tire tread rubber pulverized powder, a vulcanized rubbers or unvalcanized rubber such as a nitrile rubber, an acrylic rubber, a silicone rubber, a butyl rubber, and a fluorine rubber, or a combination of two or more of the above-identified friction modifiers may be used.

[0049] The amount of the organic friction modifier together with the above-described cashew dust contained in the friction material composition relative to the entire amount of the friction material composition is preferably 2-7 weight % and is more preferably 3-5 weight %.

[0050] For the inorganic friction modifier, other than the above-described fused silica with the average particle diameter of 15-40 μm and the electromelting zirconium silicate beads with the average particle diameter of 10-30 μm, either one of particle based inorganic friction modifiers that are generally used in the friction material composition such as a talc, a clay, a dolomite, a magnesia mica, a muscovite, a vermiculite, a triiron tetroxide, a calcium silicate hydrate, a glass bead, a zeolite, a mullite, a chromite, a titanium oxide, a magnesium oxide, a stabilized zirconia, a monoclinic zirconium oxide, a zirconium silicate other than the electromelting zirconium silicate beads, a γ-alumina, an α-alumina, a silicon carbide, aluminum particles, iron particles, zinc particles, tin particles, a non-whisker-like (plate-like, columnar, squamous, irregular/indefinite shape with multiple projections) titanate (potassium hexatitanate, potassium octatitanate, lithium potassium titanate, magnesium potassium titanate), or fiber based inorganic friction modifiers that are generally used in the friction material composition such as a wollastonite, a sepiolite, a basalt fiber, a glass fiber, a biosolubable artificial mineral fiber, and a rock wool, or a combination of two or more of the above-identified fibers may be used.

[0051] The amount of the inorganic friction modifier contained in the friction material composition together with the above-described fused silica with the average particle diameter of 15-40 μm and the electromelting zirconium silicate beads with the average particle diameter of 10-30 μm relative to the entire amount of the friction material composition is preferably 40-70 weight % and is more preferably 50-60 weight %.

[0052] For the lubricant, other than the above-described resilient graphitic carbon, either one of metal sulfide lubricant such as a molybdenum disulfide, a tin sulfide, a zinc sulfide, a bismuth sulfide, a tungsten sulfide, and a composite metal sulfide, or carbon based lubricants such as an artificial graphite, a natural graphite, a flake graphite, a petroleum coke, an active carbon, and a polyacrylonitrile oxide fiber pulverized powder, or a combination of two or more of the above-identified lubricants may be used.

[0053] The amount of the lubricant contained in the friction material composition together with the above-described resilient graphitic carbon relative to the entire amount of the friction material composition is preferably 5-13 weight % and is more preferably 7-11 weight %.

[0054] For the pH modifier, the pH modifiers that are generally used in the friction material such as the calcium hydroxide may be used.

[0055] The amount of the pH modifier contained in the friction material composition relative to the entire amount of the friction material composition is preferably 1-5 weight % and is more preferably 2-4 weight %.

[0056] For the remaining components of the friction material composition, the fillers such as the barium sulfide and the calcium carbonate may be used.

[0057] The friction material of this invention for the disc brake is manufactured through steps including a mixing step for mixing the predetermined amount of the friction material composition uniformly by a mixer, a heat-press-forming step for superposing the obtained raw friction material mixture on a separately pre-washed, pre-surface-treated, and adhesive-coated back plate to be positioned in a heat forming die and heat-press-forming the obtained raw friction material mixture and the back plate, a heat treatment step for heating the obtained molded item to complete curing reaction of the binder therein, an electrostatic powder coating step for coating a powder coating, a coating baking step for baking the coating, and a grinding step for grinding the friction surface by a rotary grinding wheel. Also, after the heat-press-forming step, the manufacturing process may go through the coating step, the heat treatment step including the coating baking step, and the grinding step in the respective order.

[0058] As necessary, prior to the heat-press-forming step, a granulation step for granulating the raw friction material mixture, or a kneading step for kneading the raw friction material mixture, and a pre-forming step for setting the obtained raw friction material mixture or the granulated substance obtained through the granulation step or the kneaded substance obtained through the kneading step in a pre-forming die to process the pre-forming step to produce a preformed intermediate item, may be performed and a scorching step may be performed after the heat-press-forming step.

EMBODIMENTS

[0059] In the following sections, the embodiments and the comparative examples are explained concretely; however, this invention is not limited to the following embodiments.

Manufacturing Method for Friction Material in Embodiments 1-19 and Comparative Examples 1-14

[0060] The friction material compositions having compositions shown in Table 1, Table 2, Table 3, and Table 4 are mixed for about 5 minutes by Loedige mixer and are pressed in a forming die under 30 MPa for about 10 minutes to perform the pre-forming. The obtained preformed intermediate item is superposed on the pre-washed, pre-surface-treated, and adhesive-coated back plate to be positioned together in the heat forming die for forming at the forming temperature of 150 centigrade under the forming pressure of 40 MPa for about 10 minutes and then to be heat-treated (post cured) at 200 centigrade for about 5 hours, and the friction surface is grinded to manufacture the disc brake pad for a passenger vehicle (Embodiments 1-19 and Comparative Examples 1-14).

TABLE-US-00001 TABLE 1 Embodiments 1 2 3 4 5 6 7 8 9 10 Binder Straight Phenol Resin 6.0 3.0 3.0 7.0 5.0 5.0 5.0 5.0 5.0 5.0 Silicon Rubber Modified 1.0 4.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Phenol Resin Fiber Base Aramid Fiber 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Lubricant Resilient Graphitic Carbon 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Graphite 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 Molybdenum Disulfide 4.0 4.0 4.0 4.0 4.0 4.0 4.0 4.0 4.0 4.0 Inorganic Friction Zirconium Oxide 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 Modifier Magnesia Mica 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 Potassium Hexatitanate 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 Triiron Tetroxide 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 Biosokubable Artificial 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Mineral Fiber Fused Silica (Average Particle Diameter of 10 μm) Fused Silica (Average 2.0 Particle Diameter of 15 μm) Fused Silica (Average 2.0 2.0 2.0 2.0 2.0 2.0 2.0 0.5 Particle Diameter of 25 μm) Fused Silica (Average 2.0 Particle Diameter of 40 μm) Fused Silica (Average Particle Diameter of 45 μm) Electromelting Zirconium Silicate Beads (Average Particle Diameter of 5 μm) Electromelting Zirconium Silicate Beads (Average Particle Diameter of 10 μm) Electromelting Zirconium 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Silicate Beads (Average Particle Diameter of 15 μm) Electromelting Zirconium Silicate Beads (Average Particle Diameter of 30 μm) Electromelting Zirconium Silicate Beads (Average Particle Diameter of 35 μm) Organic Friction Tire Tread Rubber Pulverized 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Modifier Powder Cashew Dust 2.0 2.0 2.0 2.0 1.0 4.0 2.0 2.0 2.0 2.0 pH Modifier Calcium Hydroxide 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 Filler Barium Sulfide 14.5 14.5 16.5 12.5 15.5 12.5 14.5 14.5 14.5 16.0 TOTAL 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0

TABLE-US-00002 TABLE 2 Embodiments 11 12 13 14 15 16 17 18 19 Binder Straight Phenol Resin 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 Silicon Rubber Modified 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Phenol Resin Fiber Base Aramid Fiber 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Lubricant Resilient Graphitic Carbon 2.0 2.0 2.0 2.0 2.0 0.5 1.0 4.0 5.0 Graphite 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 Molybdenum Disulfide 4.0 4.0 4.0 4.0 4.0 4.0 4.0 4.0 4.0 Zirconium Oxide 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 Magnesia Mica 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 Inorganic Friction Potassium Hexatitanate 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 Modifier Triiron Tetroxide 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 Biosokubable Artificial 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Mineral Fiber Fused Silica (Average Particle Diameter of 10 μm) Fused Silica (Average Particle Diameter of 15 μm) Fused Silica (Average 3.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Particle Diameter of 25 μm) Fused Silica (Average Particle Diameter of 40 μm) Fused Silica (Average Particle Diameter of 45 μm) Electromelting Zirconium Silicate Beads (Average Particle Diameter of 5 μm) Electromelting Zirconium 0.5 Silicate Beads (Average Particle Diameter of 10 μm) Electromelting Zirconium 0.5 0.1 2.0 0.5 0.5 0.5 0.5 Silicate Beads (Average Particle Diameter of 15 μm) Electromelting Zirconium 0.5 Silicate Beads (Average Particle Diameter of 30 μm) Electromelting Zirconium Silicate Beads (Average Particle Diameter of 35 μm) Organic Friction Tire Tread Rubber Pulverized 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Modifier Powder Cashew Dust 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 pH Modifier Calcium Hydroxide 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 Filler Barium Sulfide 13.5 14.5 14.5 14.9 13.0 16.0 15.5 12.5 11.5 TOTAL 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0

TABLE-US-00003 TABLE 3 Embodiments 1 2 3 4 5 6 7 Binder Straight Phenol Resin 6.5 2.0 2.0 8.0 5.0 5.0 5.0 Silicon Rubber Modified 0.5 5.0 2.0 2.0 2.0 2.0 2.0 Phenol Resin Fiber Base Aramid Fiber 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Lubricant Resilient Graphitic Carbon 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Graphite 5.0 5.0 5.0 5.0 5.0 5.0 5.0 Molybdenum Disulfide 4.0 4.0 4.0 4.0 4.0 4.0 4.0 Inorganic Friction Zirconium Oxide 20.0 20.0 20.0 20.0 20.0 20.0 20.0 Modifier Magnesia Mica 10.0 10.0 10.0 10.0 10.0 10.0 10.0 Potassium Hexatitanate 20.0 20.0 20.0 20.0 20.0 20.0 20.0 Triiron Tetroxide 5.0 5.0 5.0 5.0 5.0 5.0 5.0 Biosokubable Artificial 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Mineral Fiber Fused Silica (Average 2.0 Particle Diameter of 10 μm) Fused Silica (Average Particle Diameter of 15 μm) Fused Silica (Average 2.0 2.0 2.0 2.0 2.0 2.0 Particle Diameter of 25 μm) Fused Silica (Average Particle Diameter of 40 μm) Fused Silica (Average Particle Diameter of 45 μm) Electromelting Zirconium Silicate Beads (Average Particle Diameter of 5 μm) Electromelting Zirconium Silicate Beads (Average Particle Diameter of 10 μm) Electromelting Zirconium 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Silicate Beads (Average Particle Diameter of 15 μm) Electromelting Zirconium Silicate Beads (Average Particle Diameter of 30 μm) Electromelting Zirconium Silicate Beads (Average Particle Diameter of 35 μm) Organic Friction Tire Tread Rubber Pulverized 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Modifier Powder Cashew Dust 2.0 2.0 2.0 2.0 0.5 5.0 2.0 pH Modifier Calcium Hydroxide 3.0 3.0 3.0 3.0 3.0 3.0 3.0 Filler Barium Sulfide 14.5 14.5 17.5 11.5 16.0 11.5 14.5 TOTAL 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0

TABLE-US-00004 TABLE 4 Embodiments 8 9 10 11 12 13 14 Binder Straight Phenol Resin 5.0 5.0 5.0 5.0 5.0 5.0 5.0 Silicon Rubber Modified 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Phenol Resin Fiber Base Aramid Fiber 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Lubricant Resilient Graphitic Carbon 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Graphite 5.0 5.0 5.0 5.0 5.0 5.0 5.0 Molybdenum Disulfide 4.0 4.0 4.0 4.0 4.0 4.0 4.0 Inorganic Friction Zirconium Oxide 20.0 20.0 20.0 20.0 20.0 20.0 20.0 Modifier Magnesia Mica 10.0 10.0 10.0 10.0 10.0 10.0 10.0 Potassium Hexatitanate 20.0 20.0 20.0 20.0 20.0 20.0 20.0 Triiron Tetroxide 5.0 5.0 5.0 5.0 5.0 5.0 5.0 Biosokubable Artificial 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Mineral Fiber Fused Silica (Average Particle Diameter of 10 μm) Fused Silica (Average Particle Diameter of 15 μm) Fused Silica (Average 0.3 4.0 2.0 2.0 2.0 2.0 Particle Diameter of 25 μm) Fused Silica (Average Particle Diameter of 40 μm) Fused Silica (Average 2.0 Particle Diameter of 45 μm) Electromelting Zirconium Silicate Beads (Average Particle Diameter of 5 μm) Electromelting Zirconium 0.5 Silicate Beads (Average Particle Diameter of 10 μm) Electromelting Zirconium 0.5 0.5 0.5 0.05 3.0 Silicate Beads (Average Particle Diameter of 15 μm) Electromelting Zirconium Silicate Beads (Average Particle Diameter of 30 μm) Electromelting Zirconium 0.5 Silicate Beads (Average Particle Diameter of 35 μm) Organic Friction Tire Tread Rubber Pulverized 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Modifier Powder Cashew Dust 2.0 2.0 2.0 2.0 2.0 2.0 2.0 pH Modifier Calcium Hydroxide 3.0 3.0 3.0 3.0 3.0 3.0 3.0 Filler Barium Sulfide 14.5 16.2 12.5 14.5 14.5 14.95 12.0 TOTAL 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0

[0061] The obtained friction material is tested to evaluate the braking effectiveness in the normal use range, the fading resistance, the brake vibration during braking in a high temperature, the wear resistance, and the brake noise.

<Braking Effectiveness>

[0062] In conformity to JASO C406, “Passenger Car Brake Dynamo Meter Method”, the average value of the friction coefficient at the vehicle speed of 130 km/h and the deceleration speed of 0.3 G in the second effect test is evaluated under the following evaluation standards.

Excellent: 0.40 or higher
Good: 0.37 or higher but less than 0.40
Pass: 0.34 or higher but less than 0.37
Fail: less than 0.34

<Fading Resistance>

[0063] In conformity to JASO C406, “Passenger Car Brake Dynamo Meter Method”, the minimum friction coefficient in the first fade test is evaluated under the following evaluation standards.

Excellent: 0.3 or more
Good: 0.25 or more but less than 0.30
Pass: 0.20 or more but less than 0.25
Fail: less than 0.20

<Brake Vibration During Braking in a High Temperature>

[0064] In conformity to JASO C402, “General Brake Test Method for Passenger Cars”, the noise and vibration at the fading test are checked and evaluated under the following evaluation standards.

Excellent: no noise and vibration
Good: very slight noise and vibration
Pass: slight noise and vibration but in an acceptable range
Fail: noise and vibration not in an acceptable range

<Wear Resistance>

[0065] In conformity to JASO C427, “Automobile Parts-Brake Lining and Disc Brake Pad-Wear Test Procedure on Inertia Dynamometer”, the amount of wear of the friction material (shown by millimeter or mm) is measured at the initial speed of braking of 50 km/h and the deceleration speed of braking of 0.3 G with the suitable number of brake actions under the brake temperature before braking of 200 centigrade, and after converting the obtained measurement into the amount of wear at 1000 braking time, the value is evaluated under the following evaluation standards.

Excellent: less than 0.15 mm
Good: 0.15 mm or more and less than 0.20 mm
Pass: 0.20 mm or more and less than 0.50 mm
Fail: 0.50 mm or more

<Brake Noise>

[0066] In conformity to JASO C402, “General Brake Test Method for Passenger Cars”, the actual brake noise test is performed, and the brake noise occurrence rate is evaluated under the following evaluation standards.

Excellent: 0%

[0067] Good: more than 0% but less than 5%
Pass: 5% or more but less than 10%
Fail: more than 10%

[0068] The evaluation results are shown in Table 5, Table 6, Table 7, and Table 8.

TABLE-US-00005 TABLE 5 Embodiments 1 2 3 4 5 6 7 8 9 10 Performance Braking Effectiveness E E E E P E E E E E Evaluation Fading Resistance E P E P E G E E E E Brake Vibration at the P E E E E P P E E P Time of Braking in a High Temperature Wear Resistance E G P E E G E E G E Brake Noise G E E E G E E E P E E = Excellent G = Good P = Pass F = Fail

TABLE-US-00006 TABLE 6 Embodiments 11 12 13 14 15 16 17 18 19 Performance Braking Effectiveness E E E E E E E E E Evaluation Fading Resistance E E E E E E E E E Brake Vibration at the E P E P E P G E E Time of Braking in a High Temperature Wear Resistance G E P E P E E G P Brake Noise P E P E P G G E E E = Excellent G = Good P = Pass F = Fail

TABLE-US-00007 TABLE 7 Comparative Examples 1 2 3 4 5 6 7 Performance Braking Effectiveness E G G E F G E Evaluation Fading Resistance E F G F G P G Brake Vibration at the F E E E E F F Time of Braking in a High Temperature Wear Resistance E P F E E P E Brake Noise P E E E P E E E = Excellent G = Good P = Pass F = Fail

TABLE-US-00008 TABLE 8 Comparative Examples 8 9 10 11 12 13 14 Performance Braking Effectiveness E E E E E E E Evaluation Fading Resistance E G E G E G E Brake Vibration at the E F E F E F E Time of Braking in a High Temperature Wear Resistance P E P E F E F Brake Noise F E E E E E F E = Excellent G = Good P = Pass F = Fail

[0069] As shown in the respective tables, the friction material composition satisfying the compositions of this invention achieves preferable evaluation results with respect to the braking effectiveness, the fading resistance, the brake vibration during braking in a high temperature, the wear resistance, and the brake noise.

INDUSTRIAL APPLICABILITY

[0070] This invention provides the friction material for a disc brake pad, which is manufactured by forming the NAO friction material composition that contains the binder, the fiber base, the organic friction modifier, the inorganic friction modifier, and the lubricant, while satisfying the laws and regulations regarding the amount of copper component contained in the friction material composition, and the friction material can restrain a brake vibration during braking in a high temperature, which provides a significant practical value.