FRICTION MATERIAL

A friction material includes a friction-generating layer and a base layer. The base layer includes base fibers and presents a bonding surface. The friction-generating layer includes friction-adjusting particles deposited on the base layer and presents a friction-generating surface facing opposite the bonding surface of the base layer. A curable resin is present in the friction-generating layer and the base layer. The friction material also includes a composition including a plurality of triglycerides. The composition is present in at least one of the friction-generating layer and the base layer. The plurality of triglycerides comprises polyunsaturated fatty acid in a content of from 60 to 90% by weight based on a total weight of the plurality of triglycerides included in the composition.

FIELD OF THE DISCLOSURE

This disclosure generally relates to a friction material that may be used in a variety of different applications including in a friction plate in a clutch assembly in a transmission.

BACKGROUND

Several components of a powertrain of a motor vehicle may employ a wet clutch to facilitate the transfer of power from the vehicle's power generator (e.g. an internal combustion engine, electric motor, fuel cell, etc.) to drive wheels of the motor vehicle. A transmission located downstream from the power generator that enables vehicle launch, gear shifting, and other torque transfer events is one such component. Some form of a wet clutch is commonly found throughout many different types of transmissions currently available for motor vehicle operation.

A wet clutch is an assembly that interlocks two or more opposed, rotating surfaces in the presence of a lubricant by imposing selective interfacial frictional engagement between those surfaces. At the point of engagement, a friction material is utilized to generate the interfacial frictional engagement. The friction material is supported by a friction clutch plate, a band, a synchronizer ring, or some other part. The presence of the lubricant at the friction interface cools and reduces wear of the friction material and permits some initial slip to occur so that torque transfer proceeds gradually, although very quickly, in an effort to avoid the discomfort that may accompany an abrupt torque transfer event (i.e., shift shock).

Friction materials used in the variety of wet clutches found in motor vehicle powertrains must be able to withstand repeated forces and elevated temperatures that are typically generated during the repeated engagement and disengagement of transmissions. During use, the friction material must be able to maintain a relatively constant friction throughout engagement, maintain cohesive integrity, and, where applicable, maintain adhesion to the substrate for thousands of engagements and disengagements of such transmissions.

In view of the above, there remains an opportunity to develop a friction material with improved performance properties in a wide variety of different wet clutch applications.

SUMMARY OF THE DISCLOSURE

A friction material including a friction-generating layer and a base layer is disclosed. The base layer includes base fibers and presents a bonding surface. The friction-generating layer includes friction-adjusting particles deposited on the base layer and presents a friction-generating surface facing opposite the bonding surface of the base layer. A curable resin is present in the friction-generating layer and the base layer. The friction material also includes a composition including a plurality of triglycerides. The composition is present in at least one of the friction-generating layer and the base layer. The plurality of triglycerides comprises polyunsaturated fatty acid in a content of from 60 to 90% by weight based on a total weight of the plurality of triglycerides included in the composition.

Advantageously, this friction material, with the composition including the plurality of triglycerides, generates friction and withstands forces and elevated temperatures that are typically generated during the repeated engagement and disengagement of transmissions. Further, the friction-generating layer and the base layer exhibit excellent cohesion and strength. To this end, the friction material may be used in a wide variety of wet clutch applications and performs optimally across this wide variety of wet clutch applications.

It should be appreciated that the drawings are illustrative in nature and are not necessarily drawn to scale.

DETAILED DESCRIPTION OF THE DISCLOSURE

Referring to the Figures, wherein like numerals indicate corresponding parts throughout the several views, a friction material is shown generally at10. The friction material10includes a friction-generating layer12and a base layer14. The friction-generating layer12presents a friction-generating surface18, and the base layer14presents a bonding surface20facing opposite the friction-generating surface18of the friction-generating layer12.

In some embodiments, the friction material10has a thickness T1defined as the distance between the friction-generating surface18and the bonding surface20and in many such embodiments, the friction-generating layer12extends from the friction-generating surface18towards the bonding surface20up to 10, 20, 30, or 40% of the thickness T1, and the base layer14extends from the bonding surface20towards the friction-generating surface18up to 10, 20, 30, 40, 50, 60, or 70% of the thickness T1.

It should be appreciated that include, includes, and including are the same as comprise, comprises, and comprising when used throughout this disclosure.

The Friction Material

FIG. 1is a cross-sectional view of one example of the friction material10including the friction-generating layer12and the base layer14. The friction material10is porous with a resin16and a composition22present therein. Each of the friction-generating layer12, the base layer14, the resin16, and the composition22is described in greater detail below.

The Base Layer

As shown inFIGS. 1 and 2, the friction material10includes the base layer14. The base layer14may be alternatively described as a paper layer, a primary layer or as a porous layer. The base layer14may also be described as paper or raw paper. In some embodiments, the base layer14has a thickness T3of from 0.2 mm to 3.75 mm, from 0.3 mm to 3 mm, from 0.3 mm to 2.1 mm, from 0.3 mm to 2 mm, 0.4 mm to 1.9 mm, from 0.3 mm to 1 mm, from 0.3 mm to 0.9 mm, from 0.1 mm to 0.9 mm, from 0.4 mm to 0.8 mm, from 0.5 mm to 0.7 mm, from 0.6 mm to 0.7 mm, or from 0.2 mm to 0.35 mm. Alternatively, the thickness T3of the base layer 14 is less than 3.75 mm, less than 3 mm, less than 2 mm, less than 1 mm, less than 0.9 mm, less than 0.8 mm, less than 0.7 mm, less than 0.6 mm, less than 0.5 mm, or less than 0.4 mm, but greater than 0.1 mm. In additional non-limiting embodiments, all thickness T3values and ranges of values within and including the aforementioned range endpoints are hereby expressly contemplated. This thickness T3may refer to a thickness prior to, or after, resin16cure.

In some embodiments, the base layer14is discrete and well defined relative to edges and/or demarcation. In other embodiments, the base layer14is not discrete and well defined relative to edges and/or demarcation. In such embodiments, the base layer14is indiscrete and may blend or penetrate into the friction-generating layer12to varying degrees, as described in greater detail below. For example, the base layer14may blend into the friction-generating layer12in a gradient type of pattern.

The base layer14includes base fibers42. The base fibers42may be alternatively described as a plurality of fibers. The base fibers42may include one or more different types of fibers. The base fibers42are typically present in an amount of from 20 to 100 or from 20 to 80, % by weight based on a total weight of all non-resin and non-composition components the base layer14. In various embodiments, the base fibers42are present in an amount of from 25 to 75, 30 to 70, 35 to 65, 40 to 60, 45 to 55, or 45 to 50, % by weight based on a total weight of all non-resin and non-composition components of the base layer14. In additional non-limiting embodiments, all values and ranges of values of base fiber amounts within and including the aforementioned range endpoints are hereby expressly contemplated.

It should be appreciated that “% by weight based on a total weight of all non-resin and non-composition components” as referred to throughout this specification is a percentage calculated without consideration of the weight of resin16and composition22added to the particular layer12,14or the friction material10. For example, the % by weight base fibers42present in the base layer14would be calculated by dividing the total weight of base fibers42present in the base layer14by the total weight of the base fibers42, filler44, and any additives present in the base layer14, multiplied by 100. The weight of the resin16and the composition22in the base layer14would not be considered in the calculation. The details of the resin16and the composition22are described below.

The base fibers42are not limited in type and may be chosen from aramid fibers, carbon fibers, cellulose fibers, acrylic fibers, polyvinyl alcohol fibers, glass fibers, mineral fibers, and combinations thereof. In various embodiments, the base fibers42are one of or combinations of the aforementioned base fiber types. For example, in some embodiments, the base fibers42are aramid fibers and cellulose fibers. All weight ranges and ratios of the various combinations of the aforementioned base fiber types are hereby expressly contemplated in various non-limiting embodiments.

In various embodiments, the base fibers42include aramid. As a non-limiting example, in some embodiments, the friction material includes from about 5 to about 35, % by weight aramid fibers based the total weight of the base fibers42included in the friction material. In other embodiments, the base fibers42consist of or consist essentially of aramid. Various non-limiting examples of aramids include tradenames such as KEVLAR®, TWARON®, NOMEX®, NEW STAR® and TEIJINCONEX®. One or more types of aramids may be used. In one embodiment, the aramid is poly-paraphenylene terephthalamide. In another embodiment, the aramid is two or more types of aramids, e.g. a first poly-paraphenylene terephthalamide and a second poly-paraphenylene terephthalamide that is different from the first. In various preferred embodiments, aramid fibers of the tradename TWARON® or KEVLAR® may be used. Of course, in other embodiments, aramid fibers of other tradenames may be used.

In some embodiments, the base fibers42include cellulose, e.g. from wood, cotton, etc. In other embodiments, the base fibers42consist essentially of or consist of cellulose. The cellulose fibers may be chosen from abacá fiber, bagasse fiber, bamboo fiber, birch fiber, coir fiber, cotton fiber, fique fiber, flax fiber, linen fiber, hemp fiber, jute fiber, kapok fiber, kenaf fiber, piña fiber, pine fiber, raffia fiber, ramie fiber, rattan fiber, sisal fiber, wood fiber, and combinations thereof. In some specific embodiments, cellulose fibers that are derived from wood are used, such as birch fibers, pine fibers, and/or eucalyptus fibers. In other embodiments, cellulose fibers such as cotton fibers are used. If used, cotton fibers typically have fibrillated strands attached to a main fiber core and aid in preventing delamination of the friction material10during use.

In still other embodiments, the base fibers42include acrylic. Acrylic is formed from one or more synthetic acrylic polymers such as those formed from at least 85% by weight acrylonitrile monomers. In other embodiments, the base fibers42consist essentially of or consist of acrylic.

In various embodiments, the base fibers42have diameters from 1 μm to 500 μm and lengths from 0.1 mm to 20 mm. In additional non-limiting embodiments, all values and ranges of values of diameter within and including the aforementioned range endpoints are hereby expressly contemplated. The base fibers42may be woven, non-woven, or any other suitable construction.

In various embodiments, the base fibers42have a Canadian Standard Freeness (CSF) of greater than 40 or 50. In some embodiments, the base fibers42have a CSF of from 40 to 250 or from 40 to 125. In other embodiments, less fibrillated base fibers42are utilized which have a CSF of 250 to 750. In still other embodiments, the base fibers42have a CSF of 300 to 750 or greater than 750. In additional non-limiting embodiments, all values and ranges of values of CSF within and including the aforementioned range endpoints are hereby expressly contemplated.

The terminology “Canadian Standard Freeness” (“CSF”) is the degree of fibrillation of fibers and may be described as the measurement of freeness of the fibers. CSF is tested via the Technical Association of the Pulp and Paper Industry (“TAPPI”) test procedure T227 om-85. The CSF test procedure is an empirical procedure which gives an arbitrary measure of the rate at which a suspension of three grams of fiber in one liter of water may be drained. Therefore, less fibrillated fibers have higher freeness or higher rate of drainage of fluid from the friction material10than other fibers or pulp. Notably, CSF values can be converted to Schopper Riegler values. CSF can be an average value representing the CSF of all base fibers42in the base layer14. As such, it is to be appreciated that the CSF of any one particular base fiber42may fall outside the ranges provided above, yet the average value will fall within these ranges.

In addition, the base layer14may also include a filler44. If included, the filler44can be present in an amount of up to 80 or from 20 to 80, % by weight based on a total weight of all non-resin and non-composition components of the base layer14. In various embodiments, the filler44is present in an amount of from 25 to 75, 30 to 70, 35 to 65, 40 to 60, 45 to 55, or 45 to 50, % by weight based on a total weight of the base layer14. In additional non-limiting embodiments, all values and ranges of values of filler amounts within and including the aforementioned range endpoints are hereby expressly contemplated.

The filler44is not particularly limited and may be any known in the art. For example, the filler44may be a reinforcing filler or a non-reinforcing filler. The filler44may be chosen from cashew nut particles, silica, diatomaceous earth, graphite, carbon, alumina, magnesia, calcium oxide, titania, ceria, zirconia, cordierite, mullite, sillimanite, spodumene, petalite, zircon, silicon carbide, titanium carbide, boron carbide, hafnium carbide, silicon nitride, titanium nitride, titanium boride, and combinations thereof. In various embodiments, the filler44includes one of or combinations of the aforementioned filler44types. For example, in various embodiments, the filler44is carbon particles and/or diatomaceous earth particles. All weight ranges and ratios of the various combinations of the aforementioned filler44types are hereby expressly contemplated in various non-limiting embodiments.

The filler44may have a particle size from 0.5 μm to 250 μm, from 10 μm to 200 μm, 10 μm to 160 μm, 20 μm to 160 μm, or from 40 μm to 160 μm. In additional non-limiting embodiments, all values and ranges of values of particle size within and including the aforementioned range endpoints are hereby expressly contemplated.

In some embodiments, the base layer14includes base fibers42selected from cellulose fibers, aramid fibers and carbon fibers and filler44selected from diatomaceous earth particles and carbon particles.

In other embodiments, the base layer14consists essentially of base fibers42(and the resin16and composition22) or consists of base fibers42(and the resin16and composition22). To this end, the base layer14can be substantially free of filler44, or free of filler44.

The base layer14may further include additives known in the art.

The Friction-Generating Layer

As shown inFIGS. 1 and 2, the friction material10includes the friction-generating layer12. The friction-generating layer12may also be referred to as a “deposit”. In some embodiments, the friction-generating layer12may be disposed on the base layer14and included in the friction material10as a distinct and well-defined layer or deposit. In other embodiments, the friction-generating layer12may be on the base layer14and disposed in the friction material10in a graduated pattern measured in a direction from the friction-generating surface18into the base layer14(towards the bonding surface20) wherein a concentration of the components of the friction-generating layer12is greatest at the friction-generating surface18.

In many embodiments, the friction-generating layer12has a thickness T2of from 10 μm to 600 μm, from 12 μm to 450 μm, from 12 μm to 300 μm, from 12 μm to 150 μm, or from 14 μm to 100 μm. Alternatively, the thickness T2of the friction-generating layer12is less than 150 μm, less than 150 μm, less than 125 μm, less than 100 μm, or less than 75 μm, but greater than 10 μm. In additional non-limiting embodiments, all values and ranges of values of thickness T2within and including the aforementioned range endpoints are hereby expressly contemplated. The thickness T2may refer to a thickness of the friction-generating layer12prior to, or after, resin16cure.

The friction-generating layer12includes friction-adjusting particles32. The friction-adjusting particles32may include one or more different types of particles. The friction-adjusting particles32provide a high coefficient of friction to the friction material10. The type or types of the friction-adjusting particles32utilized may vary depending on the friction characteristics sought.

In various embodiments, the friction-adjusting particles32are chosen from any of the one or more filler particle types (the filler44) described above. The friction-generating layer12may consist essentially of or consist of the friction-adjusting particles32(and the resin16and/or the composition22).

In some embodiments, the friction-adjusting particles32are selected from carbon particles, diatomaceous earth particles, cashew nut particles, and combinations thereof.

In various embodiments, the friction-adjusting particles32have an average diameter of from 100 nm to 80 μm, from 500 nm to 30 μm, or from 800 nm to 20 μm. In additional non-limiting embodiments, all values and ranges of values of average diameter within and including the aforementioned range endpoints are hereby expressly contemplated.

In some embodiments, the friction-adjusting particles32include cashew nut particles. In yet other particular embodiments, the friction-adjusting particles32consist essentially of or consist of cashew nut particles or particles derived from cashew nut shell oil. Of course, in some such embodiments, the friction-generating layer12consists essentially of or consists of cashew nut particles (and the resin16and composition22). Those of skill in the art understand cashew nut particles to be particles formed from cashew nut shell oil. Cashew nut shell oil is sometimes also referred to as cashew nut shell liquid (CNSL) and its derivatives.

In some embodiments, the friction-adjusting particles32include diatomaceous earth particles. Of course, in other embodiments, the friction-adjusting particles32consist essentially of or consist of diatomaceous earth particles. Of course, in some such embodiments, the friction-generating layer12consists essentially of or consists of diatomaceous earth particles (and the resin16and composition22). Diatomaceous earth is a mineral comprising silica. Diatomaceous earth is an inexpensive, abrasive material that exhibits a relatively high coefficient of friction. CELITE® and CELATOM® are two trade names of diatomaceous earth that may be used.

In some embodiments, the friction-adjusting particles32include a combination of cashew nut particles and diatomaceous earth particles. Of course, in other embodiments, the friction-adjusting particles32consist essentially of or consist of a combination of cashew nut particles and diatomaceous earth particles. In some such embodiments, the friction-generating layer12consists essentially of or consists of a combination of cashew nut particles and diatomaceous earth particles (and the resin16and/or the composition22).

In various embodiments, the friction-adjusting particles32include elastomeric particles. Elastomeric particles exhibit elasticity and other rubber-like properties. Such elastomeric particles may be at least one particle type chosen from cashew nut particles and rubber particles. In some embodiments, rubber particles including silicone rubber, styrene butadiene rubber, butyl rubber, and halogenated rubbers such as chlorobutyl rubber, bromobutyl rubber, polychloroprene rubber, and nitrile rubber are used. In other embodiments, rubber particles consisting essentially of or consisting of silicone rubber, styrene butadiene rubber, butyl rubber, and halogenated rubbers such as chlorobutyl rubber, bromobutyl rubber, polychloroprene rubber, and nitrile rubber are used.

In some particular embodiments, the elastomeric particles include silicone rubber particles. In other particular embodiments, the elastomeric particles consist essentially of or consist of silicone rubber particles.

In some particular embodiments, the elastomeric particles include nitrile rubber particles. In other particular embodiments, the elastomeric particles consist essentially of or consist of nitrile rubber particles.

The friction-generating layer12may further include friction-adjusting fibers (not shown in the Figures). The friction-adjusting fibers may include different fiber types. In various embodiments, the friction-adjusting fibers are chosen from any of the one or more of the base fiber types (base fibers42) described above. Alternatively, the base fibers42may be chosen from any one or more of the friction-adjusting fibers described below.

If included, the friction-adjusting fibers are not particularly limited in type and may be chosen from aramid fibers, carbon fibers, cellulose fibers, acrylic fibers, polyvinyl alcohol fibers,

glass fibers, mineral fibers, and combinations thereof. In various embodiments, the friction-adjusting fibers include one of or a combination of the aforementioned friction-adjusting fiber types. For example, in some embodiments, the friction-adjusting fibers are cellulose fibers. As another example, in some embodiments, the friction-adjusting fibers are carbon fibers. As yet another example, in some embodiments, the friction-adjusting fibers are aramid fibers. Of course, in other examples, the friction-adjusting fibers are a combination of fiber types, e.g. are cellulose and carbon, are aramid and cellulose, etc. All weight ranges and ratios of the various combinations of the aforementioned friction-adjusting fiber types are hereby expressly contemplated in various non-limiting embodiments.

In some embodiments, the friction-generating layer12includes friction-adjusting particles32but does not include the friction-adjusting fibers. Of course, in some such embodiments, the friction-generating layer12consists essentially of or consists of friction-adjusting particles32(in addition to the resin16and/or the composition22).

The friction-generating layer12may further include additives known in the art.

In various embodiments, the components (e.g. the friction-adjusting particles32, friction-adjusting fibers, and/or any additives) of the friction-generating layer12or friction-generating deposit are utilized in an amount of from 0.5 to 100 lbs. per 3000 ft2(0.2 to 45.4 kg per 278.71 m2) of a surface of the base layer14, from 3 to 80 lbs. per 3000 ft2(1.4 kg to 36.3 kg per 278.71 m2) of the surface of the base layer14, from 3 to 60 lbs. per 3000 ft2(1.4 kg to 27.2 kg per 278.71 m2) of the surface of the base layer14, from 3 to 40 lbs. per 3000 ft2(1.4 kg to 18.1 kg per 278.71 m2) of the surface of the base layer14, from 3 to 20 lbs. per 3000 ft2(1.4 kg to 9.1 kg per 278.71 m2) of the surface of the base layer14, from 3 to 12 lbs. per 3000 ft2(1.4 kg to 5.4 kg per 278.71 m2) of the surface of the base layer14, or from 3 to 9 lbs. per 3000 ft2(1.4 kg to 4.1 kg per 278.71 m2) of the surface of the base layer14. In additional non-limiting embodiments, all values and ranges of values of amounts within and including the aforementioned range endpoints are hereby expressly contemplated. The amounts described immediately above are in units of lbs. per 3000 ft2, which are units customarily used in the paper making industry as a measurement of weight based on a surface area. Above, the units express the weight of the friction-generating layer12for every 3000 ft2of the surface of the base layer14.

It should be appreciated that the terminology “consists essentially of” as used throughout this disclosure describes embodiments that include a designated component (e.g. cellulose fibers) or components of a particular component class (e.g. base fibers42) and less than 5, 4, 3, 2, 1, 0.5, 0.1, 0.05, or 0.01% by weight of all other like components (e.g. additional aramid fibers) of the particular component class, based on the total weight of the particular component class included in the friction material10.

As a non-limiting example, the terminology “base fibers42that consist essentially of cotton fiber”, as described above, describes base fibers42that include cotton fiber and less than 5, 4, 3, 2, 1, 0.5, 0.1, 0.05, or 0.01% by weight other base fibers42, based on a total weight of the base fibers52included in the base layer14of the friction material10.

It should also be appreciated that the terminology “consists essentially of” as used throughout this disclosure describes embodiments that include a designated component (e.g. cellulose fibers) or components in a particular layer (e.g. the friction-generating layer12) and less than 5, 4, 3, 2, 1, 0.5, 0.1, 0.05, or 0.01, % by weight of other components (e.g. additional fibers, particles, additives, etc.) in the particular layer, based on a total weight of all components in the layer (excluding the resin16and the composition22in the particular layer).

As a non-limiting example, the terminology “the friction-generating layer12that consists essentially of cashew nut particles”, as described above, describes the friction-generating layer12that includes cashew nut particles and less than 5, 4, 3, 2, 1, 0.5, .1, 0.05, or 0.01% by weight of all other components included in the friction-generating layer12, based on a total weight of all components in in the friction-generating layer12(excluding any of the resin16and the composition22in the friction-generating layer12).

As a further non-limiting example, the terminology “the base layer14that consists essentially of cotton fiber”, as described above, describes the base layer14that includes cotton fiber and less than 5, 4, 3, 2, 1, 0.5, 0.1, 0.05, or 0.01% by weight of all other components included in the base layer14, based on a total weight of all components in the base layer14(excluding any of the resin16and the composition22in the friction-generating layer12). The Resin:

As shown inFIGS. 1 and 2, the resin16is present in the friction material10. The resin16may be dispersed homogeneously or heterogeneously within the friction material10. For example, the resin16may be dispersed in at least one of the base layer14and the friction-generating layer12. As yet another example, at least one of the base layer14and the friction-generating layer12may include one or more different types of the resin16. In various embodiments, the resin16is dispersed homogeneously or heterogeneously throughout the base layer14and may partially or wholly encapsulate the friction-generating layer12. In the Figures, the numeral16refers to uncured resin whereas the numeral17refers to cured resin.

The resin16may be any known in the art and may be curable. Alternatively, the resin16may be of the type that does not cure. In various embodiments, depending on the stage of formation of the friction material10, the resin16,17may be uncured, partially cured, or entirely cured.

In some embodiments, the resin16may be any thermosetting resin suitable for providing structural strength to the friction material10. Various resins16that may be utilized include phenolic resins and phenolic-based resins. A phenolic resin is a class of thermosetting resins that is produced by the condensation of an aromatic alcohol, typically a phenol, and an aldehyde, typically a formaldehyde. A phenolic-based resin is a thermosetting resin blend that typically includes at least 50% by weight of a phenolic resin based on the total weight of all resins and excluding any solvents or processing acids. It is to be understood that various phenolic-based resins may include modifying ingredients, such as epoxy, butadiene, silicone, tung oil, benzene, cashew nut oil and the like. In some embodiments, a silicone modified phenolic resin which includes 5 to 80% by weight of a silicone resin with the remainder % by weight being attributed to a phenolic resin or combination of phenolic and other different resins is used. In other embodiments, an epoxy modified phenolic resin which includes 5 to 80% by weight of an epoxy resin with the remainder % by weight being attributed to a phenolic resin or combination of phenolic and other different resins is used.

In one or more embodiments, the resin16may include, for example, 5 to 100 or 5 to 80, % by weight of a silicone resin based on the total weight of all resins and excluding any solvents or processing acids. Silicone resins that may be used may include thermal curing silicone sealants and silicone rubbers. Various silicone resins may also be used such as those that include D, T, M, and Q units (e.g. DT resins, MQ resins, MDT resins, MTQ resins, QDT resins . . . ).

In various embodiments, the resin16is present in an amount of from 20 to 90, 20 to 80, or 25 to 60, % by weight based on a total weight of all non-resin and non-composition components in the friction material10. For example, the resin16may be present in an amount of from 25 to 75, 25 to 70, 30 to 75, 30 to 70, or 30 to 55, or 35 to 65, % by weight based on a total weight of all non-resin and non-composition components in the friction material10. This value may be alternatively described as resin “pick up.” In additional non-limiting embodiments, all values and ranges of values of resin amounts within and including the aforementioned range endpoints are hereby expressly contemplated.

Once cured, the cured resin17confers strength and rigidity to the friction material10and adheres the components of the layers12,14to one another while maintaining a desired porosity for proper lubricant flow and retention, and also bonds the friction material10to the substrate62, as described below.

The Composition

As shown inFIGS. 1 and 2, the composition22is present in the friction material10. The composition22may be dispersed homogeneously or heterogeneously within the friction material10. The composition22is present in at least one of the base layer14and the friction-generating layer12. In other words, the composition22may be present in only the friction-generating layer12, only the base layer14, or both the friction-generating layer12and the base layer14. In various embodiments, the composition22is dispersed homogeneously or heterogeneously throughout the base layer14and may partially or wholly encapsulate the friction-generating layer12. In other embodiments, the composition22is dispersed homogeneously or heterogeneously throughout the friction-generating layer12and may partially or wholly penetrate into base layer14. In the Figures, the numeral22refers to uncured composition whereas the numeral23refers to cured composition.

The composition22includes a plurality of triglycerides. A triglyceride is an ester derived from glycerol and three fatty acids. The plurality of triglycerides may include different types triglycerides. That is, in various embodiments, each triglyceride of the plurality of triglycerides can include any combination of one or more of the fatty acids described below.

The plurality of triglycerides in the composition22comprises polyunsaturated fatty acid in a content of greater than 60, greater than 65, from 60 to 90, or from 65 to 85, % by weight based on a total weight of the plurality of triglycerides included in the composition22. Because the composition22includes the plurality of triglycerides having a high content of di- and tri-unsaturated esters (i.e., polyunsaturated fatty acid content in an amount of greater than 60, or greater than 65, % by weight), the plurality of triglycerides polymerize upon exposure to oxygen in air. This polymerization, which can also be referred to as “drying” or hardening, produces a reaction product that is rigid but flexible. The polymerization reaction of the plurality of triglycerides is exothermic.

The plurality of triglycerides typically comprises at least one fatty acid selected from palmitic acid, stearic acid, arachidic acid, palmitoleic acid, oleic acid, eicosenoic acid, linoleic acid, and alpha(α)-linolenic acid. In some embodiments, the plurality of triglycerides comprises alpha(α)-linolenic acid in an amount of greater than 40, greater than 45, greater than 50, greater than 55, or greater than 60, % by weight based on a total weight of the plurality of triglycerides included in the composition22. Further, in some such embodiments, the plurality of triglycerides comprises linoleic acid in an amount of greater than 12, greater than 14, greater than 25, greater than 40, or greater than 50% by weight based on a total weight of the plurality of triglycerides included in the composition22. Furthermore, in some such embodiments, the plurality of triglycerides comprises oleic acid in an amount of greater than 10% by weight based on a total weight of the plurality of triglycerides included in the composition.

In some embodiments, the plurality of triglycerides comprises alpha(α)-eleostearic acid. However, the plurality of triglycerides typically comprises less than 20, less than 10, or less than 1% α-eleostearic acid. In some embodiments, the plurality of triglycerides is substantial free of α-eleostearic acid.

In some embodiments, the composition22includes the plurality of triglycerides which are synthetic. That is, the plurality of triglycerides is produced from chemical feedstocks, e.g. is based on petroleum and other feedstocks.

In other embodiments, the composition22includes the plurality of triglycerides which are harvested from or derived from plant-based or renewable resources, e.g. the composition is a natural oil. For example, the composition22may be a natural oil selected from linseed oil, grapeseed oil, sunflower, and hemp seed oil. In other words, the composition22may consist of, or consist essentially of, a natural oil selected from linseed oil, grapeseed oil, sunflower, and hemp seed oil.

In various embodiments, the composition22is present in an amount of from 1 to 45, 2 to 35, or 3 to 25, % by weight based on a total weight of all non-resin and non-composition components in the friction material10. For example, the composition22may be present in an amount of from 25 to 75, 25 to 70, 30 to 75, 30 to 70, or 30 to 55, or 35 to 65, % by weight based on a total weight of all non-resin and non-composition components in the friction material10. This value may be alternatively described as composition22“pick up.” In additional non-limiting embodiments, all values and ranges of values of composition22amounts within and including the aforementioned range endpoints are hereby expressly contemplated.

In some embodiments, the resin16and the composition22are respectively present in a ratio, by weight, of from 20:1 to 2:1, or from 10:1 to 2:1. In many such embodiments, the resin16is a phenolic resins or phenolic-based resin.

The Physical Properties of the Friction Material

The friction material10includes a plurality of pores (not shown in the Figures). Each of the pores has a pore size.

The pores may he dispersed homogeneously or heterogeneously throughout the friction material10. For example, at least one of the base, layer14and the friction-generating layer12may include the pores (be porous). In some examples, the base layer14and the friction-generating layer12have a different porosity, average pore size, and/or median pore size. For example, in some embodiments, friction-generating layer12has a lower porosity than the base layer14as determined using ASTM test method D4404-10. In other examples, the base layer14and the friction-generating layer12have about the same porosity, average pore size, and/or median pore size.

The median pore size may be determined using American Society for Testing and Materials (“ASTM”) test method D4404-10. In various embodiments, the median pore size in the friction material10is, from 0.5 to 50, 1 to 50, 2 to 50, 2 to 45, 2 to 30, 2 to 15, or 3 to 10, μm as determined using ASTM test method D4404-10. In additional non-limiting embodiments, all values and ranges of values of median pore size within and including the aforementioned range endpoints are hereby expressly contemplated.

In other embodiments, the friction material10has a porosity of from 5 to 90 or 25 to 85, % as determined using ASTM test method D4404-10. The porosity of the friction material10may be described as a percentage of the friction material10that is open to air. Alternatively, the porosity may be described as the percentage of the friction material10, based on volume, that is air or not solid. In various embodiments, the friction material10has a porosity of from 30 to 80, or 40 to 75, % as determined using ASTM test method D4404-10. In additional non-limiting embodiments, all values and ranges of values of porosity within and including the aforementioned range endpoints are hereby expressly contemplated. In some embodiments, the friction-generating layer12has a lower porosity than the base layer14as determined using ASTM test method D4404-10. In some embodiments, the base layer14has a lower porosity than the base layer14as determined using ASTM test method D4404-10. The more porous the friction material10, the more efficiently heat is dissipated. The oil flow in and out of the friction material10during engagement of the friction material10during use occurs more rapidly when the friction material10is porous. For example, when the friction material10has a higher mean flow pore diameter and porosity, the friction material10is more likely to run cooler or with less heat generated in a transmission due to better automatic transmission fluid flow throughout the pores of the friction material10. During operation of a transmission, oil deposits on the friction material10tend to develop over time due to a breakdown of automatic transmission fluid, especially at high temperatures. The oil deposits tend to decrease the size of the pores. Therefore, when the friction material10is formed with larger pores, the greater the remaining/resultant pore size after oil deposit. Porosity of the friction material10may be further modified based on choice of the fibers (34,42), the particles, (32,44), the resin16, the composition22, the composition of the layers (12,14), and a raw paper weight.

In various embodiments, the friction material10has high porosity such that there is a high fluid permeation capacity during use. In such embodiments, it may be important that the friction material10not only be porous, but also be compressible. For example, the fluids permeated into the friction material10typically must be capable of being squeezed or released from the friction material10quickly under the pressures applied during operation of the transmission, yet the friction material10typically must not collapse. It may also be important that the friction material10have high thermal conductivity to also help rapidly dissipate the heat generated during operation of the transmission.

The initial thickness T1of the friction material10, is typically from 0.3 to 4, from 0.4 to 3, from 0.4 to 2, from 0.4 to 1.6, from 0.4 to 1.5, from 0.5 to 1.4, from 0.6 to 1.3, from 0.7 to 1.2, from 0.8 to 1.1, or from 0.9 to 1, mm. This thickness T1refers to a thickness prior to bonding to the substrate62and may be referred to as caliper thickness. This thickness T1can refer to the thickness of the friction material10with uncured resin present, or the thickness of the raw paper without resin16. In additional non-limiting embodiments, all values and ranges of values of thickness T1within and including the aforementioned range endpoints are hereby expressly contemplated.

After bonding to the substrate62and resin17cure, a total thickness T4of the friction material10is typically from 0.3 to 4, from 0.3 to 3.75, from 0.4 to 3, from 0.3 to 2, from 0.3 to 1.6, from 0.3 to 1.5, from 0.3 to 1.4, from 0.35 to 1.3, from 0.7 to 1.2, from 0.8 to 1.1, or from 0.9 to 1, mm. This thickness T4is typically measured after bonding to the substrate62. In additional non-limiting embodiments, all values and ranges of values of total thickness T4within and including the aforementioned range endpoints are hereby expressly contemplated.

In still other embodiments, the friction material10has a compression of from 2 to 30, from 4 to 15, or from 6 to 8, %, at 2 MPa. Compression is a material property of the friction material10that may be measured when the friction material10is disposed on the substrate62(i.e., measured when part of a friction plate60, described below) or when the friction material10is not disposed on the substrate62. Typically, compression is a measurement of a distance (e.g. mm) that the friction material10is compressed under a certain load. For example, a thickness of the friction material10before a load is applied is measured. Then, the load is applied to the friction material10. After the load is applied for a designated period of time, the new thickness of the friction material10is measured. Notably, this new thickness of the friction material10is measured as the friction material10is still under the load. The compression is typically related to elasticity, as would be understood by those of skill in the art. The more elastic the friction material10is, the more return that will be observed after compression. This typically leads to less lining loss and formation of less hot spots, both of which are desirable. In additional non-limiting embodiments, all values and ranges of compression values within and including the aforementioned range endpoints are hereby expressly contemplated.

In various embodiments, the friction material10is bonded to the substrate62, which is typically metal. Several examples of the substrate62include, but are not limited to, a clutch plate, a synchronizer ring, and a transmission band. The friction material10includes the friction-generating surface18and an oppositely facing bonding surface20. The friction-generating surface18experiences select interfacial frictional engagement with the opposed, rotating surface in the presence of a lubricant. The bonding surface20possess promotes adhesion to the substrate62and reduces the build-up of heat when the friction material10is in use.

When bonded to the substrate62, the bonding surface20achieves bonded attachment to the substrate62with or without the aid of an adhesive or some other suitable bonding technique. In one exemplary embodiment, which is described below, the friction material10is used in the friction plate60with the bonding surface20promoting a robust bond between the friction material10and the substrate62.

The lubricant may be any suitable lubricating fluid such as an automatic transmission fluid. The flow rate of the lubricant over the friction material10may be managed to allow the temperature at the friction-generating surface18and or the bonding surface20to exceed 350° C. for extended periods in an effort to improve fuel efficiency. In various embodiments, while the friction material10performs satisfactorily above 350° C., and up to 500° C., it is not limited only to such high-temperature environments and may, if desired, be used in a wet clutch designed to maintain a temperature at the friction-generating surface18below 350° C. In additional non-limiting embodiments, all values and ranges of values of operating temperatures within and including the aforementioned range endpoints are hereby expressly contemplated.

Friction Plate

As shown inFIG. 2, this disclosure also provides the friction plate60that includes the friction material10and the substrate62(e.g. a metal plate), as first introduced above. The substrate62has at least two surfaces64,66, and the friction material10is typically bonded to one or both of these surfaces64,66. The bonding or adherence of the friction material10to one or both surfaces64,66may be achieved by any adhesive or means known in the art, e.g. a phenolic resin or any resin16,17described above.

Referring now toFIG. 3, the friction plate60may be used, sold, or provided with a separator plate68to form a clutch pack or clutch assembly70. This disclosure also provides the friction plate60itself including the friction material10and the substrate62and a wet clutch assembly70including the friction plate60and the separator plate68.

Still referring toFIG. 3, this disclosure also provides a transmission72that includes the wet clutch assembly70. The transmission72may be an automatic transmission or a manual transmission.

All combinations of the aforementioned embodiments throughout the entire disclosure are hereby expressly contemplated in one or more non-limiting embodiments even if such a disclosure is not described verbatim in a single paragraph or section above. In other words, an expressly contemplated embodiment may include any one or more elements described above selected and combined from any portion of the disclosure.

One or more of the values described above may vary by ±5%, ±10%, ±15%, ±20%, ±25%, etc. so long as the variance remains within the scope of the disclosure. Unexpected results may be obtained from each member of a Markush group independent from all other members. Each member may be relied upon individually and or in combination and provides adequate support for specific embodiments within the scope of the appended claims. The subject matter of all combinations of independent and dependent claims, both singly and multiply dependent, is herein expressly contemplated. The disclosure is illustrative including words of description rather than of limitation. Many modifications and variations of the present disclosure are possible in light of the above teachings, and the disclosure may be practiced otherwise than as specifically described herein.