KR20010071446A - Friction disk assembly and method of making same - Google Patents

Abstract

The present invention relates to a friction disk assembly to be bonded to a core plate and a method of manufacturing the same. An adhesive for bonding the friction disk assembly 34 to the core plate 32 is applied to the back side of the annular friction ring 20. Pre-approved adhesives eliminate the cost and risk of handling volatile adhesives while bonding the friction ring to the core plate. The annular friction ring can be formed of at least two adjacent arc segments of the friction material. The porous backing 28 and the adhesive layer are applied to the back side of the friction material 22. Alternatively, the annular friction ring is a unitary structure. In another embodiment, adjacent arc segments of friction material are held in an annular ring by an adhesive without porous backing. Also disclosed is a method of bonding a friction disk assembly to a core plate.

Description

Friction disk assembly and manufacturing method therefor {FRICTION DISK ASSEMBLY AND METHOD OF MAKING SAME}

Friction materials are used extensively in a variety of power transmission devices such as brake linings, brake pads, torque converters in automatic transmissions, synchronizer rings for manual transmissions, and so-called "slip" clutches in new cars (variants of torque converter clutches). do. The friction material is typically bonded to one or both sides of the metal core plate that is coupled to the power transmission device.

The annular friction ring is typically blanked into a piece of ring from a continuous roll of friction material. U.S. Patent No. 4,260,047 (Nells) discloses a 90 degree arcuate segment stamped from a rectangle of pre-grooved friction material for the purpose of minimizing waste. The segments were interconnected opposite the tabs and slots to form a complete annular friction ring, which was bonded to the annular metal core plate. U.S. Patent No. 4,674,616 (Manino) discloses a fragmented core plate having interconnected ends to form an annular ring in which the fragmented friction material is joined.

U.S. Patent No. 5,332,075 (Quigley et al.) Found that the sculptural friction ring was structurally weak and could easily break during material handling. Quigley proposes a fragmented friction material bonded to each other with porous tape at the intersection of adjacent segments. The tape is placed at the rear of the fragmented friction material and sandwiched between the friction material and the annular core plate. Preferably the tape used is made of porous paper or fiber cloth with adhesive on one side. During the final bonding process, the porous tape causes the bonding adhesive to seep through the tape to bond the metal plate to the entirety of the friction material.

U. S. Patent No. 5,361, 480 (Gardner et al.) Discloses a method of manufacturing a torque converter clutch in which an annular segment of friction material is stamped from a flat sheet into a holder ring and instructed to accept the following segments until a complete annular ring is constructed. Doing. The completed annular ring and the holder ring are transferred to the stripper station so that the annular ring is peeled off on the heated metal clutch plate from the holder ring.

The process of joining the friction material to the core plate typically requires special equipment to handle the adhesive. Adhesives typically contain volatile organic compounds, incurring costs associated with controlling any emissions and safe disposal of the waste.

The present invention relates to a friction disk assembly and a method of manufacturing the same, and more particularly to a combination annular friction ring coated with a suitable adhesive for bonding a friction material to a core plate.

1 is a side cross-sectional view of a friction disk assembly according to the present invention.

2 is a perspective view of an assembled friction disk according to the present invention.

3 is a schematic view of a magazine comprising a plurality of friction disk assemblies according to the present invention.

4 is a top view of a blanking arrangement for forming segments of friction material.

5 is a side view of one embodiment of a friction material for use in the present friction disk assembly consisting of a precisely formed friction composite.

The present invention relates to a friction disk assembly for joining to a core plate and a method of manufacturing the same. In various embodiments, an adhesive for bonding the friction disk assembly to the core plate is applied to the back side of the annular friction ring. Pre-applied adhesives overcome the cost and risk of treating volatile adhesives while bonding the friction ring to the core plate.

In the first embodiment, the annular friction ring is formed of at least two adjacent arc segments of the friction material. The porous backing and the adhesive layer are constructed on the back side of the friction material. In a second embodiment, the annular friction ring is a unitary structure. In the third embodiment two adjacent arc segments of the friction material are held in the annular ring by an adhesive without porous backing.

Arc shaped segments of friction material include mutual locking ends. In another embodiment, the porous backplate comprises at least two arc segments having mutually locking ends. Preferably, in one embodiment in which the porous backplate consists of two or more arc segments, the arc segments of the backplate are preferably joined at positions other than where the arc segments of the friction material join.

Two, three or more segments of friction material can be used. In one embodiment, the arc segments of the friction material comprise unequal lengths. The porous backing may be a nonwoven knit, cotton, woven or knit of paper, a porous film of thermoplastic or thermoset material, synthetic or natural fibers. The friction material may be a conventional friction facing material, or the finely repeated, patterned friction surface has a plurality of precision shaped friction composites. Suitable adhesives include force sensing adhesives, thermosetting or thermoplastic adhesives, thermal curing adhesives, adhesives activated by solvents, mixtures thereof, and the like. The adhesive can comprise fibers. Porous backings may be laminated or impregnated with an adhesive.

In another embodiment, the annular friction ring comprises a plurality of friction particles dispersed in the assembly. Adhesive for joining the friction disk assembly to the core plate is applied directly to the back side of the annular friction ring. In one embodiment, the front friction surface comprises a plurality of precision shaped friction composites.

The invention also relates to a method of manufacturing a friction disc assembly that is directly bondable to a core plate. At least two arc segments of the friction material are stamped. Arc segments of the friction material are joined to form an annular ring. The annular ring of the porous backplate is bonded to the back side of the annular friction ring with an adhesive. The current friction disk assembly is then bonded to the core plate using an adhesive. Depending on the nature of the adhesive, the adhesive can be activated by heat and pressure, solvents, RF energy or other various activation mechanisms.

1 is a side cross-sectional view of a friction disk assembly 20 according to a first embodiment of the present invention. The friction disk assembly 20 includes a friction material 22 having a front friction surface 24 and a back surface 26. The friction material 22 can be configured as a continuous annular ring or segment. The porous backing 28 with the adhesive 30 is bonded to the back side 26 of the friction material 22. The adhesive 30 may be applied on the back side 26 of the friction material 22, applied to the porous backing 28, and may also be impregnated into the porous backing 28 combination, or a combination thereof. Can be. The pre-applied adhesive 30 is then used to bond the friction disk assembly to the core plate 32 to form the friction disk 34.

Porous backing 28 may be a nonwoven knit, cotton, woven or knit of paper, a porous film of thermoplastic and thermoset material, synthetic or natural fibers. Cotton cloth refers to a loosely woven or nonwoven fabric having a free end of a fiber or yarn. In alternative embodiments, porous backing 28 is omitted.

2 is a perspective view of a friction disk 40 according to the present invention. The annular core plate 42 typically has spline teeth 44 along the inner side 46. The friction disk assembly 48 is joined to the opposite side of the core plate 42. In the embodiment shown in FIG. 2, the friction disk assembly 48 is formed by connecting a plurality of arched segments 50 of friction material bonded to an annular ring of porous backing 52 comprising an adhesive 54. The arched segment 50 is connected by the edges 56 of the tab and slot configuration. The arched segments 50 may include an oil channel 51. Optionally, the porous backplate may be formed of arched segments at position 58 and preferably offset from the edges 56 of the tab and slot configuration. Adhesive 54 bonds friction disk assembly 48 to annular core plate 42.

In an alternate embodiment, the adhesive 54 may have sufficient tension to retain the arched segments 50 in the annular ring without the porous backing 52. Fillers comprising fibers can be added to increase the structural integrity of the adhesive body 54, thereby producing a friction disk assembly 48 suitable for mechanical processing.

Bonding the friction disk assembly 48 to the annular core plate 42 is performed by activating the adhesive 54 using various techniques, such as heating and / or pressing. Alternatively, adhesive 54 is activated with a solvent, radiation energy (including visible light, UV, radio waves, microwaves, etc.), heat and / or pressure, electron beam energy, moisture, vacuum, or combinations thereof.

3 is a schematic diagram of a magazine 60 including a plurality of friction disk assemblies 61 in accordance with the present invention. Magazine 60 includes a housing 62 that holds a friction disk assembly 61 and an ejection slot 64. The friction disk assembly 61 has sufficient structural integrity to allow high speed machining to bond to the core. Moreover, pre-applied adhesives eliminate the need for adhesive processing equipment. In some embodiments, the adhesive is not constrained by volatile organic compounds at the point of the process where the friction disk assembly 61 is to be bonded to the core plate.

4 is a top view of a blanking arrangement 70 for optimizing the production of arched segments 72 from friction material 74. Segments 72 have a length that gradually shortens to form a pie shaped wedge 76. By arranging the wedges 76 in an alternating arrangement, the amount of friction material 74 wasted is significantly reduced. The ends of the arched segment 72 may be straight line 8 or may be shaped to form a combination 79 of tabs and slots in adjacent segments. For example, segments 72 having unequal lengths may be cut to include 92 degrees, 82 degrees, 72 degrees 62 and 52 degrees (360 degrees total) or other corresponding to the area of friction material 74. It may be cut to include a configuration arrangement.

In general, the desirable properties of the friction material include toughness, strength, heat resistance, good friction and long life. Friction materials for transmissions should have normal torque curves, show no joint failure under normal use conditions, and should have torque curve levels and torque capacities. Moreover, because the smooth action of the clutch is enhanced by the friction modifying elements in the transmission fluid, the friction material must maintain or retain the proper amount of fluid at the engagement surface.

U. S. Patent No. 5,083, 650 (Zyitz et al.) Discloses a friction member having a rough surface suitable for use as a friction facing member in a transmission. The friction member of Ziez et al. Includes a heat resistant paper that supports a resin-bonded granular carbon friction particle based on and laminated on a thermosetting polymer binder including carbon filler particles. A undulating (rough) contour is formed on the surface of the friction member of Zaitz et al. Commercially available friction materials are Minnesota, Estee under the trade names FMA15 and FMM10. Available from Paul's Minnesota Mining and Manufacturing Company.

FIG. 5 illustrates a patterned friction surface of a plurality of precision shaped friction composites, as disclosed in PCT Publication No. WO97 / 38236 entitled “Patternized Surface Friction Materials, Clutch Plate Members, and Methods for Making and Using the Same”. The alternative friction material is shown. The replacement friction material 80 includes a backplate 82 and a back 86 having a front side 84 and a rear side 86. Backplate 82 optionally includes a plurality of reinforcing fibers 87, such as polyamide polymer material fibers. The friction paint 88 is bonded to the front surface 84 of the back plate 82. The friction paint 88 has an inner surface and a patterned friction surface 92 defined by a plurality of precision shaped friction composites 94.

The friction composite 94 includes an assembly 96 and a plurality of friction particles 98. The assembly 96 attaches the composite 4 to the front face 84 of the backplate 82. As shown in Figure 5, a portion of the assembly 96 and the friction particles 98 dispersed therein are separated from the backplate. An adhesive 85 for joining the friction disk assembly 91 to the core plate is applied to the back 86 according to the invention. In an alternative embodiment, the friction composite 94 is It may be formed directly on the adhesive layer 85 as described later.

In the illustrated embodiment, the precision shaped friction composite 94 is pyramidal in shape. Alternatively, the friction composite 94 may be of any shape, but preferably rectangular, conical, truncated pyramid, semicircular, circular, triangular, square, hexagonal, pyramidal, octagonal, cohesive, conical Cross-sectional or three-dimensional geometric shapes such as; Preferred shapes are triangular pyramids and square pyramids. It is desirable that the friction composite as a whole be reduced in cross-sectional area running in a direction away from the backplate toward the distal end, whether sharp or flat at the top.

Generally there are at least five friction composites 94 per cm 2, and in some cases at least 500 friction composites per cm 2. Generally, about 120 to about 1150 composites per cm 2 are appropriate but higher or lower values may be selected depending on the environment. For the application of friction material, the height H of the friction composite is generally in the range of about 88 micrometers to about 534 micrometers.

The expression "precision friction composite" as used herein is provided on a backplate and filled with a flowable mixture of friction particles and curable binder, filled in a cavity on the surface of a fabrication tool (as described herein). It is described as a friction composite having a form formed by curing. Thus, this precisely shaped friction composite has precisely the same shape as the cavity. A plurality of such composites have a three-dimensional shape that protrudes outwardly from the surface of the backplate and land portion in a pattern that is not any shape, ie opposite the pattern of the fabrication tool. Each composite is defined by a boundary, and the base portion of the boundary is generally in contact with the front side of the backplate to which the composite of precise shape is bonded. The remaining portion of the boundary is defined by the cavity on the surface of the fabrication tool where the composite cures.

glue

Suitable adhesives for bonding the friction disk assembly to the core plate include pressure sensitive adhesives, thermosetting or thermoplastic adhesives, heat radiation curing adhesives, adhesives activated by solvents, mixtures thereof, and the like. Specific examples of suitable adhesives are described in U.S. Pat.Nos. 5,436,063 (Palette et al.), 5,580,647 (outline), 5,582,672 (Palette et al.), 5,595,578 (Stubs et al.), 5,611,825 (Enzen et al. Suin), 5,681,612 (Benedict et al.) And 5,709,948 (Perez et al.).

Particularly preferred adhesives for use in the friction disk assembly of the present invention are latex phenol mixed resins used in the form of films. It is thoroughly mixed in a ratio of about 30 to about 70 of dry weight latex resin to about 70 to about 30 of dry weight resole phenolic resin, and then applied, for example, through a knife coater to form a film. Here, the resin is less than 100% solids. The coating may be applied to the release liner or may be applied to impregnate the scrim material. The coating is then dried to reach almost 100% solids and the resulting film is a handleable structure.

The latex-phenol film may then be bonded to the fragmented friction material through heat and / or pressure. Heat and / or pressure should be sufficient to bond the adhesive and scrim to the friction material but not to the final curing step. When the friction material with the adhesive thereon comes into contact with the core plate, the adhesive is preferably cured to the final stage by application of high heat and high pressure.

Another preferred adhesive for the friction disk assembly of the present invention is a mixture of thermoplastic and thermosetting resins. Preferably, such hybrid adhesives comprise a polyester resin and an epoxy resin in a ratio of polyester weight of about 10 to about 40 to epoxy weight of about 90 to about 60. The epoxy may be a mixture of various epoxy group resins. Generally, a curing agent is added to assist in curing the epoxy. The two resins, all 100% solids, are melt mixed and then coated to form a film. The coating can be applied on the release liner or scrim. The adhesive may completely or partially impregnate the cotton cloth or keep it on top of the cotton cloth without substantially wetting the cotton cloth. The coating is then condensed so that the resulting film is a handleable structure. Similar to latex phenol, the hybrid adhesive can be bonded to the crushed friction material through weak heat and / or pressure. Next, the friction material is bonded to the core plate under high temperature and high pressure.

In some cases it may be desirable to include additive curing components in the hybrid adhesive that can improve processing. For example, when added to the epoxy, the multi-group acrylic resin can reduce the flow rate of the adhesive during thermal curing. Acrylics can be cured with electron beam radiation or with the aid of UV light and photoinitiators.

In one embodiment, the adhesive cannot reverse the cured low-polymerization / polymerization material and is often used interchangeably with the term “thermoplastic” adhesive. The term “thermoplastic” adhesive is used herein to cure irreversibly upon application of heat and / or other energy sources such as electron beams, ultraviolet light, visible light, or the like, with the addition of chemical catalysts, moisture, and the like, over time. Used to refer to the reaction system. The term "reaction" means that the components of the adhesive react with each other (or by themselves) by polymerization, crosslinking or both using any of the mechanisms described above. Such components are often referred to as resins. As used herein, the term "resin" refers to multiple dispersion systems comprising monomers, oligomers, polymers or combinations thereof.

Accordingly, suitable materials for forming the adhesive include the reaction components, ie crosslinkable and / or polymerizable materials, by a wide variety of mechanisms. Examples include amino resins such as alkylate urea resins, melamine-formaldehyde resins and alkaline benzoguamine-formaldehyde resins, acrylic resins (including acrylic and methacryl), alkyl resins such as urethane alkyl resins, Polyester resins, aminoplast resins, urethane resins, phenol formaldehyde resins (i.e. phenol resins) such as resol and novolac resins, epoxy resins such as bisphenol epoxy resins, isocyanates and silicone resins And cashew nut soap resins, polyamide resins, ester resins, bismaleamide resins, and the like. Such reactive adhesive components can be cured by various mechanisms (ie, concentrated or additive polymerization) or combinations of mechanisms using, for example, thermal energy, radiant energy, and the like.

Particular preference is given to adhesives which can be cured in the form of rapidly reacting radiant energy (which requires adding less than 5 minutes or less than 5 seconds). Usable forms of radiant energy include ultraviolet / visible light, nuclear radiation, electron beams, infrared and microwave radiation. Depending on the specific curing mechanism, the adhesive may further comprise a catalyst, initiator or curing agent to assist in initiating and / or promoting polymerization and / or crosslinking.

Another particularly preferred type of initiator system is a thermal initiator that requires heat to initiate polymerization. Thermal initiators are also preferred because of their ability to penetrate largely impregnated coatings, the rate of energy applied and their efficient use, and ease of control. The thermal initiator may be used by itself or in combination with other initiators, such as UV photoinitiators, which may be used in an exothermic system compatible with the thermal initiator. In the form of such a system, UV radiation can be used to initiate the reaction and then provide the heat needed to initiate the thermal initiator. The addition of a thermal initiator to the system eliminated the need for postcuring material. Examples of commercially available thermal initiators include VAZO 52 and VAZO 64 FREE RADICAL SOURCES from DuPont, Wilmington, Delaware, and TRIGONOX 21-C50 (tert-butylperoxy-2-ethyl from Akzo Nobel, Chicago, Illinois). Hexanoate). Of course, the initiator chosen for the application depends on the chemical nature of the system and the amount of heat consumed in the reaction.

The adhesive agent components that can be cured over time with thermal energy and / or catalyst addition include, for example, phenol resins such as resol and novolac resins, epoxy resins such as bisphenol A epoxy resins, alkyl urea resins, melamines, and the like. Amino resins such as formaldehyde resin and alkaline benzoguamine-formaldehyde resin. Adhesives containing these reaction components include free radical thermal initiators, acidic catalysts and the like depending on the resin system. Examples of thermal free radical initiators include benzoyl peroxide, azo compounds, benzophenones and quinones, and the like. Typically, such reaction seal coating adhesive components are known to have room temperature curable systems, but require temperatures greater than room temperature (ie, 25-30 ° C.) to cure.

Resol phenolic resins have a mass ratio of formaldehyde to phenol, typically from about 1.5: 1.0 to about 3.0: 1.0, which is at least about 1: 1 by weight. Novolak resins have a weight ratio of formaldehyde to phenol less than about 1: 1 based on weight. Examples of commercially available phenolic resins are known under the names DUREZ and VARCUM of Occidental Chemicals Corporation, Dallas, Texas, and Montana Estee. RESINOX, Monsanto, Louis, and AEROFENE and AEROTAP, Ashland Chemical Company, Columbus, Ohio.

The epoxy resin is polymerized by oxirane ring openings. This resin can vary greatly in the properties of its center and substitution groups. For example, the center may be in any form commonly associated with epoxy resins, and the substitution group may be any group except active hydrogen atoms that react with the oxirane ring at room temperature. Representative examples of acceptable substituent groups include halogen, ester group, ether group, sulfonate group, siloxane group, nitrate group and phosphate group. In general, one of the most available epoxy resins is diphenol propane (i.e., to form 2,2-bis [4- (2,3-epoxypropoxy) phenyl] propane (the ether of diglycidyl of bisphenol A). , Bisphenol A) and epichlorindine. Such materials are commercially available under the trade names EPON (i.e. EPON 828, 1001 and 1001F) from Houston, Texas and DER (i.e., DER 331, 332 and 334) from the Dow Chemical Company of Midland, Michigan. Other suitable epoxy resins include the glycidyl ethers of phenol formaldehyde noblock resins available as DEN from Dow Chemical Company (ie DEN 431 and 428).

Amino resins are the reaction products of formaldehyde and amines. The amine is typically urea or melamine. The most common amino resins are known to be alkaline benzoguamine-formaldehyde resins, but are alkylate urea resins and melamine-formaldehyde resins. Typically, melamine-formaldehyde resins are used where outdoor durability and chemical resistance are desired. Typically, however, amino resins are not used as such because they are brittle. Therefore, they are often used in combination with other resin systems. For example, they can be combined with other resins containing functional groups that react with alkyd, epoxy or amino resins to take advantage of the superior properties of both resin systems.

In some embodiments, the adhesive may comprise at least one resin having at least one accessory acrylic group. Suitable resins having at least one accessory acrylic group are from single functional acrylic monomers, multiple possible acrylic monomers, urethane acrylics, epoxy acrylics, isobornyl acrylics, polyester acrylics, acrylic acrylics, polyester acrylics and mixtures thereof Can be selected.

As used herein, the terms "acrylic" and "acrylic function" composites include both acrylics and methacryl, whether they are monomers, oligomers, or polymers. Urethane acrylics are diacrylic esters of hydroxy terminated with isocyanates and extending to polyesters or polyethers. It may be fatty or aromatic. Examples of commercially available urethane acrylics include the trade name PHOTOMER (ie PHOTOMER 601) of Henkel Corporation, Hoboken, NJ, and EBECRYL 220 (molecular weight 1000 6-functional aromatic urethane acrylic), both available from UCB Chemical of Smina, Georgia. ), EBECRYL 284 (aliphatic urethane diacrylamide with molecular weight 1200 diluted with 1,6-hexanediol diacryl), EBECRYL 4827 (aromatic urethane acrylamide with molecular weight 1600), EBECRYL 4830 (molecular weight 1200 diluted with tetraethylene glycol diacryl) Fatty urethane diacryl), EBECRYL 6602 (trifunctional urethane acryl with a molecular weight of 1300 diluted with trimethylropropane ethoxy triacyl) and EBECRYL 8402 (fatty urethane diacryl with molecular weight of 1000) and Sartomer Company, West Chester, PA SARTOMER (ie, SARTOMER 9635, 9645, 9655, 963-B80, 966-A80, etc.) and Morton Inn in Chicago, Illinois National's UVITHANE (ie UVITHANE 782). Other useful resins having at least one accessory acrylic group include Sartomer CN 966-J75 (bifunctional aromatic urethane acrylic oligomer mixed with 25% isobornyl acrylic) from Sartomer Company, West Chester, PA, and EBECRYL from UCB Chemical. Esters of aromatic acid methacryl half mixed with 350 (silicone ester acrylic oligomer) and bifunctional (SR506) or trifunctional (SR454) monomers, both commercially available from Sartomer Co., available under the trade names SB570A20 and SB510G35. And esters of aromatic acid acrylic half mixed with single function (SR334) or trifunction (SR454) monomers available under the trade names SB520E35 and SB520M35.

Porous backplate

The choice of the particular porous backing that is adopted depends on the desired application of the friction material. Typically the backing should be heat resistant and strong. Thermal resistance and strength properties are necessary to ensure that the friction disk assembly withstands the forces and heat generated during use. In some applications, for example, when the friction disk assembly of the present invention is employed in a synchronizer ring, the porous backplate must be flexible to conform to the blocker ring (ie, synchronizer). In other applications, the porous backing should be virtually incompressible (after bonding) because the brake pads must be substantially rigid and non-compliant.

The thickness of the porous backing is preferably very constant or very uniform along its width and length. The thickness should not change greater than about 20% at any point and preferably should not exceed about 10%. The thickness of the porous backing is from about 0.05 mm to about 10 mm, and may typically range from about 0.05 mm to about 1.0 mm. A backplate thickness of about 0.13 mm is suitable for optimal application. The numerical value of the thickness of the backplate of the present invention can be measured according to the TAPPI T411 OM Test Method. The thickness chosen for the porous backing is influenced by various considerations, such as sufficient thickness for a given elasticity, as thin as possible for economical reasons, and as thick as necessary for the specific clutch environment requirements.

Porous backings typically comprise or consist of fibrous material. The fibers of the fibrous material can be organic or inorganic fibers (both artificial or natural), or a combination thereof. Examples of artificial fibers are polycarbonates, polyvinylchlorides, polyetheramides, polyethylene, polyurethanes, polyesters, polysulfones, polystyrenes, acrylonitrile-butadiene-styrene block copolymers, polypropylenes, acetal polymers, nylons, aramids, Polyamide copolymers and physical mixtures thereof, and the like. Examples of natural organic fibers include cotton, hair, silk, cellulose, rayon, hemp, kapok, flax, sisal hemp, jute, manila and combinations thereof. Examples of suitable inorganic fibers include metal fibers, aluminum fibers, glass fibers and about 60-70% aluminum, 20-30% silicon dioxide and 1-20% boron and are commercially available from 3M under the trade name "NEXTEL". Fiber made of a ceramic material such as available. Non-woven mats using these fibers are available under the trade names "NEXTEL 312" and "NEXTEL 440". Carbon fiber knits may also be used.

Where heat escapes, a material useful as a backing in the friction disk assembly of the present invention is a non-woven paper comprising aramid polymer staple fibers bonded to an acrylic latex to provide a backing with a uniform density. It has been found that great care must be taken to obtain a non-woven uniform density, uniform thickness of aramid staple fibers to provide a backing of suitable friction material. Aramid staple fibers for this purpose preferably have a length of about 0.5 cm to about 2 cm, more preferably about 1.0 to about 1.5 cm. At lengths greater than about 2 cm (such as 5 cm or more), the fibers tend to form high density areas which undeniably densify the backplate. Fibers of length shorter than about 0.5 cm (up to 0.05 cm) do not readily form a backplate with adequate handling strength. The backing also has a weight of about 5 g / m 2 to about 50 g / m 2 (more preferably about 10 g / m 2 to about 25 g / m 2) to provide sufficient structural support for the friction coating.

Suitable aramid polymers for use in producing aramid staple fibers are the Eye of Delaware Wilmington, under the trade names "KEVLAR," "KEVLAR 29," "KEVLAR 49," and "NOMEX." Commercially available from the DuPont de Newmouth Company. As used herein, the term “aramid polymer” refers to an artificial polymer resin generally indicated in the art as aromatic polyamide. Such “aramid polymers” are disclosed in US Pat. Nos. 3,652,510 (Blomberg) and 3,699,085 (Johnson) and are considered to be high molecular weight polymers having, for example, an intrinsic viscosity of at least about 0.7. Examples of polyamides include poly (p-phenylene terephthalamide), chloro substituted poly (p-phenylene terephthalamide) and copolymers thereof.

Aramid polymers or aromatic polycarbonamides may consist predominantly of polycarbonamide rings (-CONH-) and aromatic ring nuclei according to the above formula, but the polymers are, for example, meta-phenylene units, non-aromatic and nonamide groups Etc., about 20 mole%, preferably about 5 mole%, of non-compliant, wherein the ring extension bonds are on the same axis or in parallel and provide opposite polycarbonamide rings as described above, such as opposite aromatic carbonamide units It may include a comonomer unit. It is important that the aramid polymer used to obtain the unique advantages of the present invention is in the form of staples of the aramid polymer. As described above, the staple fibers are about 0.5 cm to about 2 cm in length.

The above-described aramid fiber nonwoven paper is manufactured by conventional paper making technology and the New York Tuxedo under the trade names "KEVLAR" mat series "8000050", "8000051", "8000052", "8000054", "8000065" and "8000068". Commercially available from Veratech Corporation of International Paper Zone, USA. Such papers comprise from about 8% to about 18% by weight of acrylic latex used to reinforce the fibers in an integral knit fabric.

Example 1-Friction Disc Assembly

0.4 oz / yd ² (approximately 33.8 g / m 2) KEVLAR paper available from Veratech Corporation contains 208.3 grams of HYCAR 1578X1 Latex, 13.3 grams of BOSTEX 422 zinc oxide dispersant, 2.9 grams of BOSTEX 410 sulfur dispersant, and BOSTEX 497-B It was impregnated with a 60/40/50 (aqueous) mixture of 4.0 grams of butyl zymate dispersant (all of which are available from Alcon Dispersion, Alcon, Ohio), and an aqueous petroleum coke available from Asberry under the name 4023. Was dried. The impregnated KEVLAR piece was bonded to the friction material offset by about 45 degrees using hot steel for several seconds. Friction materials are Estonia, Minnesota under the trade name FMA 15. It is available from 3M of pole material. The resulting friction disk assembly was bonded to the steel core plate in a press heated to about 205 ° C. (400 ° F.) for about 2 minutes under a ram pressure of about 5 tons.

Example 2-Piece Friction Disc Assembly

Adhesive and non-woven reinforcement adhesive films are available in DYNAPOL S1402 (Clinova, Ink, Somerset, NJ) 21, EPON 1001F (Cell Chemical, Houston, Texas) 40, EPON 828 (Cell Chemical, Houston, Texas) 30, TMPTA- A mixture prepared at a ratio of N (Yusubi Chemicals, Smina, Georgia) 9, IRGACUTRE (Ciba Specialty Chemicals, Horshon, NY) 1, and 2-Ethylimidazole (Aldrich Chemicals, Milwaukee, Wisconsin) 1 It was prepared from.

To prepare the adhesive and reinforcing adhesive films, the mixture was heated to 130 ° C. for knife coating on a common carrier film. During the coating step, the coater knife was heated to 120 ° C., the coater stage was heated to 65 ° C. and the knife spacing (distance between the top of the carrier film and the bottom of the knife) was set to 6 mils (about 0.15 mm). A nylon nonwoven reinforcement, commercially available from Serex Advanced Fabrics L.P., Pensacola, Florida, was placed between the knife and the carrier film. The heated adhesive mixture was placed on top of the CEREX reinforcement and the carrier film was pulled from the bottom of the knife to coat the adhesive. Sufficient adhesive mixture was applied so that the adhesive mixture continued to be coated on the carrier film after the end of the CEREX stiffener passed under the knife. After coating, the adhesive on the carrier film and the reinforcing adhesive film were irradiated at a rate of 50 ft / min (about 15 m / min) at the bottom of the 600 watt D bulb to partially cure the adhesive mixture.

Both adhesive and reinforcing adhesive films were cut into quadrant segments with ball and socket connections at the ends of each segment using quadrant steel ruler dies.

The adhesive segments were then joined to similarly formed frictional facing segments. The following components of the friction facing segments were made.

ingredient weight% Sartomer SR368H 24.3 Satomer CN111 24.3 Shiba IRGACURE 369 1.0 Asbury 4349 Oil Cork 20.8 US Silica Sil-Co-Sil 45 29.1 OSI Specialty A-174 Slein 0.5 Dupont Bajo 52 0.75

The ingredients in this table were combined into the slurry in the order listed by mixing and further mixed until all the ingredients were well dispersed. The dispersion slurry was coated onto a woven production tooling. The mold used to produce the friction facing fabric has a height of 14 mils (about 0.36 mm), a top of 12.5 x 12.5 mils (about 0.32 x 0.32 mm), a space of 6 mils (about 0.15 mm), and a minus angle of 10 °. It was a polypropylene sheet with a fine repeating surface of a flat truncated pyramid.

The fine repetitive mold was placed under the coating knife with the fine repetitive side up and the spacing between the mold and the knife was set to 3 mils (about 0.08 mm). The carrier film was placed under another coating knife and the gap was set to 5 mils (about 0.13 mm). The mixed slurry was applied onto the mold and carrier film in its respective coater, and the non-woven backing of 0.5 oz / yd ² (about 16.9 g / m 2) KEVLAR paper (commercially available from Veratec Division of International Paper) Was introduced between the two coated slurry layers. The two layers of the slurry composite and the nonwoven backing were pressed together by a pinch roll and UV energy was applied to cure the slurry layer. The coating line speed was 30 ft / min (about 9 m / min) and the UV energy source was two 600 Watt D bulbs. After curing the slurry, the press and carrier films were removed from the friction facings cut into quadrant segments using a quadrant steel ruler.

The friction facing segments were then joined into adhesive film segments. The two friction facing segments were positioned with the woven side down in the form of a simple circular assembly holding the segments in the desired position and the segments of the adhesive film or the reinforcing adhesive film were positioned with the adhesive side down on the two friction facing segments. Thus, about half of the adhesive segments were on each friction facing segment. The adhesive segments were joined into friction facing segments by mutual pressurization with cold steel (surface temperature of about 40 to 60 ° C. sufficient to soften the adhesive and attach the segments but not enough to cure the adhesive film anymore). The other frictional facing segment was placed in assembled form and the other adhesive segment was pressed on top of it. The final frictional facing and adhesive segments were joined to complete the circular assembly. The assembly was placed in the refrigerator to facilitate removal of the carrier film from the adhesive film. After the carrier film was removed from the adhesive film, the assembly was placed with the adhesive side down on the cleaned steel core plate. The assembly was joined in place with cold steel. The second assembly was located on the other side of the cleaned core plate and joined in place with cold steel. The thickness of the bonding assembly was measured in micrometers and the wedge was chosen to give a compression of about 1 to 2 mils (0.02 to 0.05 mm) during the bond. The bond assembly was placed in a press with a selected wedge and pressed at 205 ° C. with a total load of 5000 lbs (8900 Newtons) for 2 minutes.

Claims (11)

In a friction disc assembly for joining to a core plate, An annular friction ring formed of at least two adjacent arc segments of friction material having a front friction surface and a back surface, An annular ring of porous backplate opposite to the back side, And an adhesive for bonding the friction disk assembly to a core plate configured at the back of the annular friction ring. 2. The friction disc assembly of claim 1 wherein at least two arc segments of friction material comprise mutual locking ends. The friction disk assembly of claim 1, wherein the porous backplate comprises at least two arc segments that are joined at a position other than adjacent arc segments of the friction material. The friction disc assembly of claim 1 wherein at least two arc segments of the friction material comprise unequal lengths. The friction disc assembly of claim 1 wherein the porous backplate is impregnated with the adhesive. The friction disc assembly of claim 1 wherein the front friction surface comprises a plurality of precision shaped friction composites. The friction disc assembly of claim 1 wherein the adhesive retains a porous backplate on the back side. In a friction disc assembly for joining to a core plate, An annular friction ring formed of at least two adjacent arc segments of friction material having a front friction surface and a back surface, And an adhesive for bonding the friction disk assembly to the core plate and retaining adjacent segments of friction material in an annular friction ring configured at its rear surface. The friction disk assembly of claim 8 wherein the adhesive comprises reinforcing fibers. 10. The friction disc assembly of claim 8 wherein the front friction surface comprises a plurality of precision shaped friction composites. A method of manufacturing a friction disk assembly for bonding to a core plate, the method comprising: Stamping at least two arc segments from a friction material having a front friction surface and a back surface, Joining the arc segments of the friction material to form an annular friction ring; Retaining the annular ring of porous backplate with an adhesive on the back side of the annular friction ring for bonding the friction disc assembly to the core plate.