JP3034027B2 - Composite and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a composite and a method for producing the same.

This application is based on CIP of US Patent Application Serial No. 149,573, entitled "Carbon Fibrils," filed January 28, 1988, by Snyder et al., Assigned to the same assignee as the present application. (Included here for reference).

(Background technology)

Various methods exist for dispersing a solid filler (eg, a fibrous or particulate filler) in a solid or liquid matrix to form a composite structure. These methods include formulating the filler / matrix mixture using a vane mixer, high shear whirling mixer, roll mill, compaction mixer, or internal Brabender mixer.

Reaction injection molding (RIM) is a molding method as follows.
One or more liquids or mixing reactants are separately metered into a mixing head and they are mixed, for example, by high impact mixing. The mixture is then poured into a mold and polymerized,
Form a molded part. In structural reaction injection molding (SRIM), often referred to as reinforcement reaction injection molding (RRIM), a reinforcing agent such as chopped glass fiber or particulate mineral filler is added to the mixture before molding. In another type of SRIM process, a low viscosity, especially polymerized, RIM composition is injected into a mold filled with a textile mat and the resulting composition is shaped. In both the RIM and SRIM methods, the molded parts are coated prior to use to provide protection against UV radiation and to balance with other parts.

A second type of molding involves a premix. The pre-mixture is a molding composition prepared separately from the molding operation before the molding operation, and includes all components necessary for molding, for example, a resin,
It contains reinforcing agents, fillers, catalysts, mold release agents, and the like. One type of premix is called a sheet molding compound (SMC). SMC is a semi-sticky thin sheet of thermoplastic resin, typically reinforced with chopped glass fibers or continuous glass fiber yarns. The sheet can be formed using, for example, a combination die forming method to form various parts. A second type of premix is called a bulk molding compound (BMC). BMC is prepared in the form of putty that can be molded directly. It can be extruded into rods or logs for ease of handling. RIM
And, like SRIM molded articles, molded pre-blend products are often coated before use.

Various types of compositions are also known. For example, polymeric conductive composites (eg, in the form of a coating or ink)
It has been known. These compositions are made conductive by incorporating a conductive additive.

A hybrid composite is a structure in which the matrix is reinforced with two or more reinforcing agents. The reinforcement present at the highest volume fraction (compared to other reinforcements) is called the primary reinforcement and the remaining reinforcements are called secondary reinforcements.

Elastomers have also been filled with various materials. Such materials have been used to improve the mechanical or electrical properties of the elastomeric matrix or to reduce costs.

A friction material is a material that converts an applied force into heat to dissipate the force. Applications of such materials include brakes, automatic shifting discs, and clutches. Reinforced organic polymers have been used as friction materials.

Carbon fibrils are single carbon fibers having a diameter of less than 500 nm. Examples of special carbon fibrils and methods of making them are described in US Patent Application Serial No. 149,573 (Carbon Fibrils) filed January 28, 1988 by Snyder et al .; US Patent No. 4,663,230 to Tennent.
No. 871,676, filed on June 6, 1986 by Tennet et al. (A novel carbon fibril, its production method and its composition). US Patent Application Serial No. 871,675, filed June 6, 1986 by Tenet et al. (New carbon fibrils, methods for their preparation, and encapsulation catalysts); Mandevil
ille) et al., U.S. Patent Application Serial No. 285,817, filed December 16, 1988; fibrils; and McCar-thy et al., U.S. Patent Application Serial No. 285,817, filed May 15, 1989. 351, 967 (Surface treatment of carbon microfibers), all of which are assigned to the same assignee as the present application and which are incorporated herein by reference in their entirety.

[Disclosure of the Invention]

The compounding method The present invention introduces one or more types of fillers and matrix materials into a stirring ball mill, and sets the fillers and matrix materials such that the particle size of the aggregate formed by the filler is smaller than a predetermined value. For the production of composites comprising the steps of subjecting the combined forces of shear and impact under reaction conditions, including reaction times sufficient to reduce the value, to dispersing the filler throughout the matrix material. Is characterized as an invention.

In a preferred embodiment, the predetermined value of the particle size of the aggregate is 1000 times or less, more preferably 100 times or less, even more preferably 10 times or less of the filler particle size. Preferably, one or more of the characteristic axes of the filler (a measure of its particle size) is smaller than 1 μm, more preferably smaller than 0.1 μm.

Preferably, a viscosity modifier (ie, a material that changes the intrinsic viscosity of the matrix-filler mixture to facilitate dispersion) is added to the stirred ball mill. Preferred viscosity modifiers include both materials that are removed after the dispersion step, e.g., solvents, and materials that are maintained after the dispersion step, an example of the latter type of viscosity modifier being one that chemically reacts with the matrix material. Reactive diluent. In a more preferred embodiment, one or more grinding media (ie, a particulate material that promotes dispersion by applying additional impact) is added to the stirred ball mill.

Preferred fillers include whiskers (ie, single crystal fibers), discontinuous fibers, granular fibers, and carbon fibrils. The fibrils are preferably tubes having a graphite layer substantially parallel to the fibril axis. One feature of substantial parallelism is the US patent application by Snyder et al.
As described in Serial No. 149,573, the length of the graphite layer projected on the fibril axis extends over a relatively long distance with respect to the outer diameter of the fibril (for example, at least two fibril diameters). Times, preferably at least 5 times its diameter). These fibrils preferably do not include a continuous pyrolytic carbon outer coating (ie, pyrolytically attached carbon resulting from pyrolysis of the gas feed used to make the fibrils). Fibrils 3.5
It preferably has a diameter of 7575 nm (inclusive) and a length to diameter ratio of at least 5. Having this form,
The outer surface of the graphite layer has a plurality of oxygen-containing groups (e.g., carbonyl, carboxylic acid, carboxylate, epoxy, vinyl ester, hydroxy, alkoxy, isocyanate, or amine groups) or derivatives thereof (e.g., sulfhydryl, amino, Or an imino group).

Preferred matrix materials include metal powders, ceramic powders (eg, glass powders), thermoplastics, thermosets, and elastomers, and matrix materials in liquid form. Preferred thermoplastics include thermoplastic polyesters (eg, polyethylene terephthalate), polyurethanes, polyether ether ketones, polyether sulfones, polyether imides,
Polyamide (eg, nylon) and polyurea resins are included. Preferred thermosets include phenolics, epoxies, thermoset polyurethanes, thermoset polyesters (eg, alkyds), polyimides, bismaleimides, polycyclopentadiene, and vinylacrylimides (Ashland Chemical Company, Columbus, Ohio). (Ashl
and Arimix (Ar
imix) like a resin]. Preferred elastomers include styrene-butadiene rubber, natural rubber, ethylene propylene diene monomer (EPDM) rubber, silicone rubber, polybutadiene (cis and trans 1,4 and 1,2-polybutadiene), polyisoprene, neoprene, chloroprene, fluoro Elastomers (eg, fluorinated polyethylene) and urethane elastomers are included.

If the matrix material is a thermoplastic resin, the compounding method preferably comprises cooling the contents of the stirred ball mill to a temperature at which the matrix material becomes brittle before the dispersion step, and maintaining that temperature during the dispersion step.

The present invention also features a complex produced according to the above method as an invention.

The present invention provides that the filler is distributed throughout the matrix material,
Disperses substantially uniformly even when the average filler diameter is on the order of 1 micron or less, producing a composite with improved composite properties, such as electrical, optical, mechanical, and magnetic properties I do. The degree of homogeneity (measured by the particle size of the filler agglomerates) can be tailored to the particular application for which the composite is intended by adjusting the milling time.

The present invention also provides that various fillers having different diameters and shapes can be simultaneously dispersed in the matrix. Further, in accordance with the present invention, there is no need to pre-treat the filler surface or apply a chemical dispersant to better disperse the filler throughout the matrix.

The present invention also features composites comprising a matrix impregnated with carbon fibrils, wherein the fibril material is applied directly to the composite (i.e., first applying a primer coat). (Without) an amount sufficient to be electrostatically overcoated.

In one embodiment, the composite comprises a reaction injection molded matrix loaded with carbon fibrils.

In a second embodiment, the composite comprises a molded product of a premix comprising a resin matrix impregnated with carbon fibrils.

In a preferred embodiment, the premix is a sheet-forming composition or a bulk-forming composition. Preferably, the electrical conductivity of the composite is greater than the electrical conductivity of a composite in which the same matrix is filled with the same amount of carbon black. Preferably, the amount of fibrils in the composite is sufficient to provide the composite with a high enough electrical conductivity to allow direct electrostatic coating to the surface. Complexes in which the amount of fibrils is sufficient to dissipate static electricity are also preferred. The amount is preferably equal to or less than 20% by weight (based on resin), more preferably equal to or less than 4% by weight.

Preferably, the fibrils are tubes having a substantially average graphite layer on the fibril axis. One feature of substantial parallelism is that of US Patent Application Serial
As described in No. 149,573, the length of the graphite layer projected on the fibril axis extends over a relatively long distance relative to the outer diameter of the fibril (eg, at least twice the fibril diameter). , Preferably at least five times its diameter). These fibrils preferably do not include a continuous pyrolytic carbon outer coating (ie, pyrolytically attached carbon resulting from pyrolysis of the gas feed used to make the fibrils). Fibrils 3.5-75nm
It preferably has a diameter (including both numbers) and a length to diameter ratio of at least 5. In this form, the outer surface of the graphite layer has a plurality of oxygen-containing groups (eg, carbonyl,
It is also preferred that the fibrils are linked to a carboxylic acid, carboxylic acid ester, epoxy, vinyl ester, hydroxy, alkoxy, isocyanate, or amide group) or a derivative thereof (eg, a sulfhydryl, amino, or imino group).

Preferred matrix materials include thermoplastics (eg, polyamide, polyurethane, polyurea, or elastomer) and thermosetting resins (eg, polydicyclopentadiene, polyester, thermosetting polyurethane, epoxy resin, or vinyl acrylimide resin) (Such as the Alimix resin available from Ashland Chemical Company of Columbus, Ohio). A resin mixture may be used, and any composite may be used in the form of an automobile, truck, or bus autopart. Preferably, it is molded.

In a third aspect, the invention features a composite in a form suitable for reaction injection molding comprising one or more liquid reactants capable of polymerizing to form a reaction injection molded matrix and carbon fibrils. It is to add.

In a fourth aspect, the invention features a pre-mix comprising a resin loaded with carbon fibrils.

In a preferred embodiment, the liquid reactant comprises one or more polyols, polyisocyanates, or polyamines. Preferably, the premix is a bulk or sheet molding composition. The amount of fibrils is preferably equal to or less than 20% by weight, more preferably equal to or less than 4% by weight. Preferred fibrils and resins have been described above.

The present invention also features a method for producing the above-described complex as an invention.

The reaction injection molded composite is prepared by mixing a fibril with a liquid reactant capable of polymerizing to form a matrix, introducing the mixture into a mold, and molding the mixture under reaction conditions including pressure and temperature. And manufactured by a method comprising manufacturing a composite in the form of a molded part.

The compound composite for sheet-like molding is manufactured by a method including mixing fibrils and a resin, and forming the mixture into a sheet. The bulk-forming compound composite is produced by a method comprising mixing fibrils and a resin to form a putty suitable for molding. Both methods,
Preferably, it comprises a molding step in which the composite is produced in the form of molded parts under reaction conditions including temperature and pressure.

Preferably, the molded parts produced by the above method are directly electrostatically coated once the molding is completed.

The present invention relates to reaction injection molded composites and molded composites made from premixes (e.g., sheet or bulk molding compounds) that are electrically conductive with relatively low fibril content. give. This allows molded parts made from these composites to be electrostatically coated, as is currently done for metal parts,
This eliminates the need to apply a conductive undercoat as a separate step. Still other advantages provided by fibrils include good mechanical properties (eg, hardness and impact strength) and the ability to use less additives, such as flame retardants. Fibrils also provide inherent EMI shielding.

The use of fibrils offers some processing advantages as well, including better consistency in electrical and mechanical properties across batches. In the case of the RIM process, the small fibril content used does not block small tubes and holes in the processing equipment because of the small size of the fibrils. Furthermore, the fibrils need not be largely oriented during processing, and thus they do not contribute to partial distortion. SMC
In this case, the increase in viscosity due to the fibrils allows the thickening agent necessary to form a viscous sheet to be omitted.

Electrically Conductive Coatings and Inks The present invention features, as an invention, an electrically conductive composite in a form suitable for application to a surface of a substrate comprising a polymeric binder loaded with carbon fibrils.

In a preferred embodiment, the composite is in the form of a powder or liquid coating. The amount of fibrils in the coating is preferably large enough so that the substrate to which the coating is applied is directly electrostatically coated. Its amount is preferably 15% by weight
Less than or equal to (based on resin), more preferably 0.5 to 10% by weight. Even more preferred is
Coatings with 1-4% by weight fibrils. The coating may include one or more pigments.

In another preferred embodiment, the coating is in the form of a resistive ink suitable for screen printing on the surface of a substrate to form an electronic component. The amount of fibrils in the resistive ink, when applied to a substrate, is between 10 ^{-2 and} 10 ⁶
It is an amount sufficient to reduce the bulk resistivity of the binder to a value of Ωcm (more preferably 10 ^-1 to 10 ⁴ Ωcm). The preferred amount of fibrils is 1-30% by weight
It is.

In another preferred embodiment, the coating further comprises electrically conductive graphite or metal particles (e.g., silver foil pieces, metal coated shredded fibers,
Or a metal powder) in the form of a conductive ink suitable for printing on the surface of a substrate. The amount of fibrils in the ink is sufficient to reduce the volume resistivity of the particle-filled binder (measured without carbon fibrils) by a predetermined amount when applied to a substrate. is there. Preferably, the volume resistivity of the particle-filled binder is greater than 1 ohm-cm and the amount of fibrils is an amount sufficient to reduce the volume resistivity to less than 1 ohm-cm. Even more preferred are conductive inks wherein the volume resistivity of the particle-filled binder is greater than 10 ^-1 Ωcm and the amount of fibrils is sufficient to reduce the volume resistivity to a value less than 10 ^-1 Ωcm. . The preferred amount of fibrils is between 20 and 50% by weight.

The fibrils are preferably tubes having a graphite layer substantially parallel to the fibril axis. One feature of substantial parallelism is that of US Patent Application Serial
As described in No. 149,573, the length of the graphite layer projected on the fibril axis extends over a relatively long distance relative to the outer diameter of the fibril (eg, at least twice the fibril diameter). , Preferably at least five times its diameter). These fibrils preferably do not have a continuous pyrolytic carbon outer coating (ie, pyrolytically attached carbon resulting from the pyrolysis of the gas feed used to make the fibrils). Fibrils 3.5
It preferably has a diameter of ~ 75 nm (inclusive) and a length to diameter ratio of at least 5.

Preferred polymer binders include thermoplastic resins (eg,
Includes polyethylene, polypropylene, polyamide, polyurethane, polyvinyl chloride, or thermoplastic polyester resins, such as polyethylene terephthalate), and thermosetting resins (eg, thermosetting polyester resins or epoxy resins).

The invention also features a substrate coated with a fibril-filled electrically conductive composite as an invention. The conductivity of the composite is preferably large enough to directly electrostatically coat the surface of the coated substrate. Also, the composite is a resistive ink printed on the substrate in the form of an electronic component (eg, a resistor), or on a substrate in the form of a conductive trace for electrically connecting the electronic component. It is preferably a substrate for a printed circuit board, which is a conductive ink printed on the substrate. Methods for making coated substrates, which can be directly electrostatically coated, and for screen-printing fibril-filled inks on substrates are also featured as inventions.

Fibril-filled composites are electrically conductive at low fibril contents. As a result, coatings and inks having a predetermined resistivity value can be produced without excessive viscosity increase due to added fibrils.
Such increases are undesirable because they make them difficult to apply. The properties of the composite also do not change significantly from batch to batch. This is because fibrils exhibit good resistance to shear degradation caused by the shear mixing used to make the composite. Furthermore, the resistivity of the composite is relatively insensitive to temperature fluctuations.

When used as a primer to subsequently electrostatically coat surfaces on molded parts (e.g., automotive parts), those coatings can directly electrostatically coat the surface with lower energy, thereby reducing corona effects To provide uniform coverage. Further, the fibril-filled composite can be overcolored so that the finished composite does not have a black appearance. The coating also has sufficient electrical conductivity to be used in combination with a sacrificial anode material to help prevent corrosion on exposed surfaces of metal or molded plastic parts. When applied to plastic substrates, the coatings show good mechanical adhesion and allow the metal to be plated directly on the plastic.

Fibril-filled composites in the form of resistive or conductive inks provide yet another advantage. When printed on a substrate,
The resistance of the ink and its ability to adhere to the substrate is not degraded by folding or bending of the substrate. The ink is also resistant to abrasion and scratching. In the case of conductive inks, fibril-filled inks are lighter than inks in which the conductive filler is 100% metal particles (which makes it easier to apply) and exhibit improved corrosion resistance. In addition, fibrils allow the resistivity of conductive inks containing metal particles to be finely tuned for special applications and applications, thereby providing resistivity values that cannot be easily obtained using metal particles alone. Can be obtained.

Elastomer The present invention features a composite in which carbon fibrils are incorporated into an elastomer matrix. In one embodiment, the fibrils do not have a continuous pyrolytic carbon outer coating (ie, pyrolytically attached carbon resulting from the pyrolysis of the gas feed used to make the fibrils) and have a fibril shaft attached to them. It has the feature of having a configuration consisting of a tube having a substantially parallel graphite layer. One feature of substantial parallelism is that of U.S. patent application Ser.
As described in rial No. 149,573, the length of the graphite layer projected on the fibril axis extends over a relatively long distance relative to the outer diameter of the fibril (for example, at least two fibril diameters). Times, preferably at least five times its diameter). These fibrils are preferably smaller than 100 nm, more preferably 3.5 to
It preferably has a diameter of 75 nm (inclusive) and a length to diameter ratio of 5 to 100.

In a second aspect, the fibrils have the characteristic of having a crystalline graphite structure and a morphology defined as a fishbone arrangement of graphite layers along the fibril axis. Examples of such fibrils are described in U.S. Patent Application Serial No. 149,573 by Snyder et al. And in European Patent Application No. 10/22/1986 published by Geus et al.
0 198 558. These fibrils are 100
Preferably it has a diameter smaller than nm.

The amount of fibrils in the composite may be such that the composite can be cured by resistance or induction heating, or at least one of the physical properties of the composite may be monitored electrically.
r) Preferably, it is in an amount sufficient to be able to do so. This amount is preferably less than 25 parts per 100 parts of elastomer, more preferably 100 parts of elastomer.
Less than 10 parts per part. However, in the case of a masterbatch (i.e., a fibril-filled elastomer precursor that is subsequently mixed with an additional elastomer to produce the final composite structure), the amount of fibrils is preferably greater than 25 parts per 100 parts of elastomer.

Preferred elastomeric matrices include natural rubber,
Styrene-butadiene rubber (both random and block copolymers), polyisoprene, neoprene, chloroprene polybutadiene (cis and trans 1,4 and 1,2-
(Both polybutadienes), fluoroelastomers (eg, fluorinated polyethylene), silicone rubber, and urethane elastomers. Outside fibrils,
The elastomer preferably comprises one or more fillers, for example, carbon black, silica, or a combination thereof. The ratio of the amount of fibrils in the complex to the total amount of filler is at least 1: 4 or more (e.g., 1: 5, 1:
6 etc.). The composite may be a tire or a component thereof (eg,
It is preferably provided in the form of a tire tread or casing), sealant, solution, or adhesive.

In a third aspect, the present invention produces a composite by incorporating carbon fibrils in an elastomeric matrix, the amount of fibrils being sufficiently large to permit resistance or induction heating. An amount sufficient to impart conductivity to the composite and characterizes an elastomeric curing process that includes steps of curing the composite by resistance or induction heating.

In a fourth aspect, the present invention produces a composite by incorporating an electrically conductive additive into an elastomer matrix, the amount of which is electrically monitored to detect the physical state of the elastomer. An amount sufficient to impart sufficient electrical conductivity to the composite to allow for the electrical properties (eg, resistivity) of the composite to be an indicator of the physical state of the elastomer. It features a method for monitoring and detecting the physical state of an elastomer including the steps of monitoring and detecting. In a preferred embodiment of this aspect, the electrically conductive additive comprises carbon fibrils. In another preferred embodiment, the composite is in the form of a tire,
The internal pressure of the tire is monitored and detected. The method is also preferably used to monitor elastomers (eg, in the form of a conveyor belt or hose) for the presence of cuts, tears, or holes.

In a preferred embodiment of the third and fourth aspects, the amount of fibrils in the composite is less than 25 parts per 100 parts elastomer, more preferably 10% per 100 parts elastomer.
Less than a part. Preferred fibrils are those described above.

In a fifth aspect, the present invention provides a method for producing a masterbatch by dispersing at least 25 parts of fibrils per 100 parts of elastomer in an elastomer, wherein the masterbatch is produced in a predetermined portion of the masterbatch. The present invention characterizes a method for producing an elastomer composite, which comprises various steps of producing a composite by adding an additional amount of the same or different elastomer to the elastomer used in the above. Preferably the amount of fibrils in the final composite is less than 25 parts per 100 parts of elastomer, more preferably less than 10 parts. Preferred fibrils are as described above. Carbon black may be added to the composite during the production of the masterbatch or during the compounding process.

In a sixth aspect, the invention features a method of reinforcing an elastomer, which comprises incorporating a sufficient amount of carbon fibrils into an elastomer masterbatch to improve the mechanical properties of the elastomer. The fibrils are similar to those described above for the first and second aspects of the invention.

The present invention provides fibril reinforced elastomeric composites that exhibit good toughness, tensile strength, tear strength, cream and die swell resistance, and raw resistance (ie, strength before cure).
These composites also exhibit good cure, stress / strain properties, and abrasion resistance (even with a relatively soft elastomeric matrix) and low specific gravity. Due to the improved wear resistance, an advantageous balance of traction, rolling resistance, and tread wear can be achieved for articles made from the composites. Furthermore, these advantages are achieved with a low fibril content.

Further advantages are obtained from the electrical properties of fibrils. Because fibrils are electrically conductive, they are elastomeric
It can be used to reinforce the matrix while serving the dual function of making the matrix electrically conductive. The electrically conductive composite can be cured by resistance or induction heating, thereby avoiding the problems of heat transfer and increased costs often associated with conventional heat curing. The ability to be electrically cured allows the fibril-filled composite to be bonded to a variety of rubber-to-rubber bonds (e.g., when bonding a tire tread to a tire casing), rubber-to-metal bonds, and rubber-to-ceramic bonds. And can be particularly useful as an adhesive in rubber repair systems for products such as tires and conveyor belts.

The electrical conductivity of the composite is also useful in applications such as extrusion of rubber tubes, tires, treads, and related products. Further, the composites are partially electrically cured,
The composite can be provided with additional shape stability. The present invention also provides a design product that can electrically monitor and detect physical changes in the complex, such as internal pressure. For example, the condition of tires, air springs, hoses, or conveyor belts can be amazed and effectively monitored and detected.

Friction Material In a first aspect, the invention features a brake or component thereof made from a friction material that includes a matrix loaded with carbon fibrils.

In a second aspect, the invention features a clutch or component thereof made from a friction material that includes a matrix with carbon fibrils.

In a third aspect, the invention features an automatic variable speed disk or component thereof made from a friction material including a matrix loaded with carbon fibrils.

In a fourth aspect, the invention features a composite in the form of a friction material that includes a matrix impregnated with carbon fibrils.

In a preferred embodiment, the amount of fibrils is 20% by weight.
Less than or equal to (based on resin), more preferably 5 to 10% by weight.

The fibrils are preferably tubes having a graphite layer substantially parallel to the fibril axis. One feature of substantial parallelism is that of US Patent Application Serial
As described in No. 149,573, the length of the graphite layer projected on the fibril axis extends over a relatively long distance relative to the outer diameter of the fibril (eg, at least twice the fibril diameter). , Preferably at least five times its diameter). These fibrils preferably do not have a continuous pyrolytic carbon outer coating (ie, pyrolytically attached carbon resulting from the pyrolysis of the gas feed used to make the fibrils). Fibrils 3.5
It preferably has a diameter of ~ 75 nm (inclusive) and a length to diameter ratio of at least 5. In this form, the outer surface of the graphite layer has a plurality of oxygen-containing groups (for example, carbonyl, carboxylic acid, carboxylic acid ester, epoxy, vinyl ester, hydroxy, alkoxy, isocyanate, or amide group) or derivatives thereof ( Also preferred are fibrils which are linked to, for example, a sulfhydryl, amino or imino group).

Preferred matrix materials are carbon and thermoset resins, such as phenolic, polyester, and epoxy resins. It is also preferred to add one or more additional fillers as well. Examples of preferred fillers include metal, glass, ceramic, carbon, or polyaramid fibers, or graphite, clay, barium sulfate, diatomaceous earth, silica,
Includes particulates such as magnesia, beryllia, alumina, silicon carbide, boron carbonate, titanium dioxide, or carbon black. Examples of preferred applications for friction materials include clutches, automatic shifting discs, and brakes (eg, backing for brake pads and shoes).

Articles made from friction materials made from fibril-containing composites have good friction properties and fades.
Indicates resistance. These properties are maintained at elevated temperatures, a quality that is particularly useful for heavy duty applications, such as outdoor vehicles, racing cars, armored vehicles, and motor vehicle disc brakes, which are often subjected to such temperatures.
In addition, the friction materials are resistant to spalling and cracking at elevated temperatures.

Hybrid Composite As a first aspect, the present invention incorporates a primary fiber reinforcing agent and a secondary reinforcing agent randomly oriented with respect to the primary reinforcing agent and uniformly dispersed throughout the matrix. It characterizes a hybrid complex containing a matrix.

In a preferred embodiment, the average diameter of the primary reinforcement is at least 10 times, more preferably at least 100 times the average diameter of the secondary reinforcement. Most of the aggregates formed by the secondary reinforcing agent in the matrix are preferably 10μ
m, preferably 0.5 μm or less.

The secondary reinforcing agent is preferably a carbon fine fiber (ie, 1 μm).
m), whiskers (i.e., single crystal fibers), chopped fibers (i.e., discontinuous fibers having a length on the order of 1/16 to 2 in), and particulate materials; For example, silica or carbon black is included.
Preference is also given to carbon fibrils, preferably carbon fibrils which are tubes having a graphite layer substantially parallel to the fibril axis. One feature of substantial parallelism is that, as described in U.S. Patent Application Serial No. 149,573 to Snyder et al., The length of the graphite layer projected onto the fibril axis is relatively small relative to the outer diameter of the fibril. Extending over a long distance (eg, at least twice the fibril diameter, preferably at least five times its diameter).
These fibrils preferably do not have a continuous pyrolytic carbon outer coating (ie, pyrolytically attached carbon resulting from the pyrolysis of the gas feed used to make the fibrils). The fibrils have a diameter of 3.5 to 75 nm (inclusive) and preferably have a length to diameter ratio of at least 5. The amount of secondary reinforcing agent incorporated into the matrix is preferably equal to or less than 20% by volume, more preferably 1 to 10% by volume.

Preferred primary reinforcements include continuous fibers. Examples of preferred continuous fibers include carbon, glass, ceramic (eg, boron, alumina, or silicon carbide), and polyaramid (eg, Kevlar) fibers. These fibers may be woven, biased, crimped, or straight. Primary reinforcements comprising discontinuous fibers made from the same type of material as the continuous fibers are also preferred.

Preferred matrix materials include organic thermosets and thermoplastics. Examples of preferred thermosetting resins include epoxy, bismaleimide, polyimide, and polyester resins. Examples of preferred thermoplastic resins include polyethylene, polypropylene, polyamide (eg, nylon), polyurethane, polyvinyl chloride, thermoplastic polyester resin, polyether ether ketone, polyether sulfone, polyetherimide, oriented polyethylene, liquid crystal polymer, And reaction injection molding resins. Other preferred matrix materials include inorganic polymers (eg, polymeric inorganic oxides such as glass), metals (eg, aluminum or titanium alloys), ceramics (eg, Portland cement or concrete),
And carbon.

In a second aspect, the invention relates to a hybrid comprising a primary fiber reinforcing agent and a secondary fiber reinforcing agent, wherein the primary reinforcing agent comprises a matrix having an average diameter of at least 1000 times the average diameter of the secondary reinforcing agent. It characterizes the complex.

In a preferred embodiment of the second aspect, the secondary reinforcement is uniformly dispersed in the matrix and is randomly oriented with respect to the primary reinforcement. Preferred secondary reinforcing agents are carbon fibrils as described above. Preferred matrix material,
The amounts of primary reinforcing agent, aggregate particle size, and secondary reinforcing agent are as described above.

The present invention also features a method for producing a hybrid composite as an invention.

The present invention provides hybrid composites having properties that cannot be obtained with composites containing only primary reinforcing agents. The secondary reinforcing agent is randomly oriented with respect to the primary reinforcing agent and is evenly dispersed in the matrix (as measured by the small agglomerate particle size throughout the matrix) so that the primary reinforcing agent is Rather, the lateral and internal lamellarity normally governed by the matrix is improved. Furthermore, since the secondary reinforcement is substantially smaller than the primary reinforcement, its incorporation into the matrix does not impair the properties of the primary reinforcement. Further, by dispersing the secondary reinforcing agent throughout the matrix, rather than between the layers of the primary reinforcing agent, breakage or deformation of the weave or laminate of the primary reinforcing agent can be avoided.

Other features and advantages will be apparent from the following description of the preferred embodiments, and from the claims.

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the drawings are briefly described.

The drawing is a schematic cross-sectional view of a two-dimensional hybrid composite embodying the present invention.

Compounding method The composite is preferably produced as follows. The matrix material and one or more fillers are placed in a stirred ball mill of the type conventionally used for powder milling. In the mill, these materials are subjected both to the shearing force of the mechanical rotor by the action of agitation and to the impact of the granular grinding media of the kind conventionally used for powder grinding added to the mill during agitation. . After the grinding operation is completed, the particulate matter is removed. However, in the case of metal and ceramic matrices, it is not necessary to add a separate grinding media, as the matrix itself (which is added in powder form) can generate an impact force.

A viscosity modifier is added to the viscous matrix-filler mixture to reduce its inherent viscosity to a value low enough to facilitate grinding. Viscosity modifiers are particularly useful when the matrix material is a high molecular weight thermoplastic or partially cured thermosetting resin. Examples of suitable viscosity modifiers include solvents such as water, toluene, acetone, methyl ethyl ketone (MEK), isopropanol, or mineral oil. Following the milling operation, the solvent is removed, for example, by vacuum drying, steam purge, or freeze drying. The viscosity modifier may be a material that becomes part of the matrix or filler when milling is completed. Examples of such modifiers include monomers called reactive diluents that chemically react with the matrix material during milling (eg, styrene,
Triallyl cyanurate, diallyl cyanurate, polyfunctional acrylates, and divinylbenzene). Viscosity modifiers may be incorporated into the matrix. In such a case, the viscosity modifier may be present during the production of the matrix, for example in the solution of the solution-polymerized SBR and in the solution of the thermoplastic obtained from the polymerization reaction.

Suitable fillers include discontinuous fibers (eg, chopped glass or carbon fibers), whiskers (eg, carbon or silicon carbide whiskers), granular fibers (eg, silica or carbon black), carbon fibrils, or any of these fillers. Or all combinations. Preferably, the average diameter of the filler (ie, the diameter of the individual particles or fibers that make up the filler) is on the order of 1 micron or less. Preferred fibrils are those having a small diameter (preferably 3.5-75 nm) and a layer of graphite substantially parallel to the fibril axis and having substantially no continuous pyrolytic carbon outer coating. No. 4,663,230 to Tennent;
U.S. Patent Application Serial No. 871,675 by Tenet et al;
U.S. Patent Application Serial No. 871,676 by Tenet et al .;
U.S. Patent Application Serial No. 149,57 by Snyder et al.
3; and U.S. Patent Application Serial No. 285,817 to Mandeville et al. These fibrils are manufactured as described in the earlier patents and patent applications. The fibrils may be treated to introduce oxygen-containing functional groups on the fibril surface, as described in U.S. Patent Application Serial No. 351,967 to McCarthy et al. Preferred matrix materials include metal and ceramic (eg, glass) powders and organic matrices, such as thermoplastics, thermosets, and elastomers, as described in the disclosure of the invention above. The manufacture of carbon fibril-filled elastomers is described in U.S. Pat. No. 5,086,086 entitled "Fibril-Filled Elastomers" by Barber et al., Filed concurrently herewith and assigned to the same assignee herewith.
al No. 386,828, which is incorporated herein by reference in its entirety. In the case of thermoplastics, the complex is to put the resin and filler into a stirred ball mill, then add dry ice to the mill and cool the contents to a temperature at or near the temperature at which the resin turns into a brittle solid. It is preferred to be manufactured by In this form, the resin is more easily ground during milling, resulting in a more uniform dispersion. Dry ice evaporates during milling and therefore does not remain in the final dispersion.

Final size of filler agglomerates depending on milling time,
Thus, the degree of dispersion is determined, which in turn depends on the end use intended for the complex. For example, electrical applications that require internal interparticle contact to establish a conductive network can tolerate larger agglomerates than mechanical applications where the agglomerates act as reduced strength defects.

A composite in which carbon fibrils (produced as described above) are dispersed in a styrene-butadiene rubber (SBR) matrix is prepared using the above-described stirred ball mill method, and the properties thereof are determined by conventional internal mixing and roll milling. It was compared with fibril reinforced SBR matrix manufactured using compounding method. The results, shown in Table 1, indicate that composites made using a stirred ball mill have superior properties.

The compounding process is described in US Patent Serial No. 38 entitled "Hybrid Complex" by Creehan et al., Filed concurrently with the present application and assigned to the same assignee as the present application.
6,822 (it is included here entirely for reference)
Prepreg for the hybrid complex described in
reg) can also be used.

Composites for Electrostatic Outer Coating The following examples show that carbon fibrils are incorporated into sheet-form compounding (SMC) composites, bulk compounding (BMC) composites, and reaction injection molding ( RIM) Describe the complex. Preferred fibrils are disclosed in US Pat. No. 4,663,230 to Tennet; US Patent Application Ser.
ial No. 871,675; US patent application Ser.
ial No. 871,676; U.S. Patent Application S by Snyder et al.
erial No. 149,573; as described in U.S. Patent Application Serial No. 285,817 to Mandeville et al., having a graphite layer of small diameter (preferably 3.5-75 nm), substantially parallel to the fibril axis, and continuous pyrolysis. It has substantially no carbon outer coating. These fibrils are manufactured as described in the aforementioned patents and patent applications. As described in U.S. Patent Application Serial No. 351,967 by McCarthy et al.
The fibril surface may be treated to introduce an oxygen-containing functional group.

Example 1-RIM A fibril-containing RIM complex is manufactured using a conventional RIM processor. Such devices typically include a material conditioning system, a high pressure metering system, a mixing head, a mold, and a mold console.

The material conditioning system includes a tank for holding the reactants for making the composite (each reactant is stored in a separate tank) and for maintaining uniform temperature and composition conditions throughout the tank. It has a stirrer and a temperature control system to maintain the proper level of gas dissolved in the reactants. Preferably, the fibrils are premixed with one or more reactants in an amount sufficient to provide 1-4% by weight fibrils in the final molded product. Additional tanks store optional additional reinforcing agents, such as pigments and catalysts, as well as shredded glass fibers. Preferred reactants include polyols and polyisocyanates (to make a polyurethane matrix) and polyamines and polyisocyanates (to make a polyurea matrix).

Typically, a metering system consisting of, for example, an axial or radial high pressure piston pump or lance displacement cylinder meteres the appropriate amount of reactants, fibrils, and additional filler into the mixing head. I do. The mixing head is
It has a chamber where the reactants and the filler are mixed by direct impingement at a pressure of, for example, 1500-3500 psi. When mixing is complete, the mixture is transferred to a mold where the reactants are polymerized to form the final part. Suitable mold structures include machined steel or aluminum, cast aluminum, kirksite, spray metal, or electroplated, and filled epoxy. Typical mold internal pressure during polymerization is 25-100 psi. Molding temperatures will vary with the particular reactants used, as will be readily apparent to those skilled in the art. For polyurethane forming reactants, the mold temperature is about 130 ° F. (± 70 ° F.). The mold operation table orients the mold, gives a clamping force to withstand the mold internal pressure, opens and closes the mold
Place the mold to remove the finished part, clean it, and prepare it for the next molding operation.

Fibril-containing RIM composites are useful in a variety of industrial and consumer molded products. They are particularly useful for automotive parts, automobiles, trucks or buses, such as bumpers, interior parts, instrument panels, integral window sealants, handles, armrests, protective coverings, body panels. The parts are coated before use. By incorporating carbon fibrils, the parts can be electrostatically coated, making their manufacture compatible with the processing of metal parts.

Example 2-SMC A fibril-containing SMC composite was produced using a conventional SMC processor. This device without a continuous belt or belt typically has a mixing system, a paste metering system, a squeezing system, and a removal system.

In a mixed system, the uncured resin (typically an unsaturated thermoset polyester or epoxy resin, which cures upon application of heat) and catalysts, fillers, thickeners, release agents, pigments, Thermoplastic polymers (eg, polyvinyl chloride polymers and copolymers to minimize shrinkage during molding,
And additives such as a flame retardant and an ultraviolet absorber to form a paste having the viscosity of a soft mass suitable for forming into a sheet. The paste also contains carbon fibrils. Mixed system is batch,
It may be batch / continuous or continuous.

The paste is transferred from the mixing system to a paste reservoir and weighed into a predetermined thickness of paste on upper and lower plastic (eg, polyethylene) carrier films using adjustable doctor blades. The doctor blade height determines the amount of resin paste in the final SMC composite. A sandwich is formed by applying a reinforcing agent, such as chopped glass thread, or continuous glass roving, between the two paste coated sheets. Additional carbon fibrils may be added at this stage. The total amount of carbon fibrils (i.e., the sum of the fibrils added during the formulation of the paste and the fibrils applied directly to the paste-coated sheet) is preferably 1 to 4% by weight based on the resin.

The press squeezes the sandwich so that the resin paste wets the fibrils and any other reinforcing agents. Typically, the press comprises a series of serrated steel rollers or a two wire mesh belt pressing mechanism.
The sheet emerging from the press is then picked up, for example, by a winding turret and formed into a roll. Once a complete roll of the composite has been made, the sheet (typically 2-5 f
(t width) and transfer it to the second winding turret. The roll is then taped to prevent unwinding and a vapor barrier sleeve is applied to prevent contamination by ultraviolet light or moisture. The rolls are stored in an aging room maintained at about 85-90 ° F for about 1-7 days to provide a uniform and reproducible molding viscosity. The sheet is then cut and formed into the desired part using, for example, squeezing or mating die forming.

The molded parts produced in this way are useful for various applications. In the automotive industry, they are components of heating and ventilation equipment, hoods, trunks, side walls, fenders,
Useful as shingles, front end plates including fender extensions, mounting members for headlamps and grills, and cab parts (eg, hoods) for trucks. The molded composites are also useful as electrical switchgear containers, containers for manual power tools such as electric drills, and containers for appliances such as air conditioners and dishwashers. Contains fibrils
The components can be electrostatically coated, as in the case of the RIM composite.

Example 3-BMC Fibril-containing BMC composites are made using a conventional BMC processor. Typically, this device consists of two mixers. Using a first mixer, for example a simple propeller type or a dissolver or disperser of the type used in the paint industry, the resin (eg, unsaturated thermoset polyester or epoxy as in the case of SMC composites) Resin) and particulate fillers, release agents, colorants, catalysts, thickeners, and low profile additives. It is also preferred to add carbon fibrils to the resin mixture. The ingredients are mixed well to disperse the additives and fibrils throughout the resin. The resulting mixture is then transferred to a second high-load mixer, such as a mulling or twin-screw mixer, where glass fibers (in the form of chopped yarn or chopped spun roving), asbestos, sisal hemp And additional reinforcing agents such as organic fibers. An additional amount of carbon fibrils may be added at this time. The total amount of carbon fibrils (i.e., the sum of the fibrils added in both mixing stages) is 1-4% by weight based on the resin.

The components are mixed by a second mixer until the resulting mixture has the viscosity of the putty. The putty is then aged (eg, about 4 hours at 77 ° F). When ripening is complete, the putty is formed directly or stored in a sealed frozen plastic bag until needed. The putty may be extruded into bars or logs before aging for ease of handling and storage.

The fibril reinforced BMC premix is molded using conventional thermoset molding methods, such as pressing, transfer, or thermoset injection molding, at a pressure sufficient to allow the premix to flow into the details of the mold. Typical molding pressures range from about 100 to 1500 psi. Molded parts are useful in many of the same applications as SMC molded parts. Additional applications include automotive heater vessels and associated conduits. As with RIM and SMC molded parts, BMC molded parts can be electrostatically coated without prior application of an electrically conductive undercoat.

In addition to the examples described above, fibrils are incorporated into many types of matrices (such as thermoplastic and thermoset matrices) and the resulting composite is directly electrostatically coated on the surface. Sufficient electrical conductivity can be provided.

Conductive Coatings and Inks A. Powder and Liquid Coating Both powder and liquid coatings consist of a polymeric binder loaded with carbon fibrils. Preferred binders for powder coating include the following thermosets: urethane polyesters, epoxies, epoxy polyesters, polyester triglycidyl isocyanurates, and urethane or epoxy type polyesters. Suitable thermoplastics include polyethylene, polypropylene, polyamide (eg, nylon), polyvinyl chloride, and thermoplastic polyester (eg, polyethylene terephthalate). The molecular weight of the binder is high enough so that it becomes solid at room temperature. For liquid coatings, preferred resins are thermoplastic polyesters and polyurethanes. The molecular weight of the binder is low enough so that it is liquid at room temperature.

To form an electrically conductive coating, it is preferred to incorporate 1-4% (based on the weight of the resin) of carbon fibrils in the binder. Such a content is sufficient to directly electrostatically form the outer coating of the dielectric component (eg, plastic) to which the coating is applied. The resistivity of such coatings after application is typically on the order of 10 ⁶ Ωcm or less.

Preferred fibrils are disclosed in U.S. Pat.
No. 663,230; US patent application Serial by Tenet et al.
No.871,675; U.S. Patent Application Serial by Tenet et al.
No.871,676; U.S. Patent Application by Snyder et al. Seria
l No.149,573; U.S. Patent Application Ser by Mandeville et al.
and a graphite layer having a small diameter (preferably 3.5-75 nm), substantially parallel to the fibril axis, as described in U.S. Patent Application Serial No. 351,967 to McCarthy et al. It has substantially no pyrolytic carbon outer coating. These fibrils are manufactured as described in the aforementioned patents and patent applications. The fibrils may be treated to introduce oxygen-containing functional groups on the fibril surface, as described in U.S. Patent Application Serial No. 351,967 to McCarthy et al.

The coatings are made by combining additives such as binders, fibrils, and pigments by shear mixing.
When mixing is complete, the coatings can be applied directly to metal or molded plastic parts or stored until needed.

The coating is electrostatically applied in a mold to sheet molding compounds (SMC) and bulk molding compounds (BMC) pressed parts, such as automotive body panels. The coated part is then used as is, or the surface is electrostatically coated with a second coating, such as a finish coating. In either case, the surface can be electrostatically coated directly by adding fibrils to the binder to make the coating electrically conductive.

B. Inks Preferred polymer binders for resistive and conductive inks are thermoset epoxy resins and thermoplastic polyester resins (eg, polyethylene terephthalate). The ink may be provided in the form of a solution or a solvent dispersion.

Preferred fibrils are those described above for the powder and liquid coating cases. The amount of fibrils incorporated in the binder is a function of the desired resistivity level, which in turn depends on the intended use of the inks. Generally, for resistive inks having a resistivity in the range of 10 ^-2 to 10 ⁶ Ωcm, 1 to 30% by weight of fibrils is incorporated. For example, for conductive inks that already have a relatively low resistivity due to the presence of the metal foil, fibrils are used to fine tune the resistivity of the ink and cannot be obtained by simply adjusting the amount of silver foil. Or, it becomes possible to obtain an impractical resistivity value. Thus, the amount of fibrils incorporated depends on the resistivity of the silver-filled binder and the value of the target resistivity. Generally, 20-50% by weight of fibrils is
It is incorporated to reduce the resistivity of silver filled binders having a resistivity greater than Ωcm to values less than 1 Ωcm.

The ink is made using the same procedure as described above for the conductive powder and liquid coating. They are then screen printed by conventional screen printing methods on substrates, such as printed circuit boards, or disposable donor sheets for such substrates, to form resistors (for resistive inks) or electronic components. Is formed to form a conductive line (in the case of conductive ink) for connecting. Due to the constant conductivity of the inks, there is no need to perform laser cutting and the inks can be used in multilayer molded circuit boards.

The composite is made by dispersing the elastomeric fibrils in an elastomeric matrix. Preferred fibrils are U.S. Pat. As described in application Serial No. 285,817, small diameters (preferably 3.5-7
5 nm), having a graphite layer substantially parallel to the fibril axis and having substantially no continuous pyrolytic carbon outer coating. These fibrils are manufactured as described in the aforementioned patents and patent applications. These fibrils are disclosed in U.S. Patent Application Serial No. 351, by McCarthy et al.
As described in 967, the fibril surface may be treated to introduce oxygen-containing functional groups. Preferred elastomer matrices include natural comb, styrene
Butadiene rubber (both random and block copolymers), polyisoprene, neoprene, chloroprene, polybutadiene (both cis and trans 1,4 and 1,2-polybutadiene), fluoroelastomer (eg, fluorinated polyethylene), silicone rubber , And urethane
Elastomer (for example, Spandex)
Is included.

Low fibril content is preferred. Generally 1 to 10 parts of fibrils are added per 100 parts of elastomer. Fillers such as carbon black and silica may also be added. Preferably 4 parts of filler are used for each 1 part of fibril.

The particular compounding method used to make the fibril-filled elastomer composite depends on the final properties sought, the type of elastomer matrix, the degree of dispersion required, and the type of filler added outside of the fibrils.
For example, in the absence of a separately added reinforcing agent, in the case of rubber matrices, such as natural rubber, having significant strength values, composites can be prepared using conventional compounding equipment, such as Banbury and twin roll mills. can do. However, if a highly uniform dispersion is desired, the fibrils are first ground using a method such as a ball mill.
A particularly effective method for obtaining a well-dispersed mixture is disclosed in US Patent Application Serial No. Serial "Creating a uniform dispersion" by Creehan, filed concurrently with the present application and assigned to the same assignee as the present application. No. 386,912, the description of which is incorporated herein by reference in its entirety, fibrils, elastomeric matrices, and any other fillers are added to low viscosity additives (eg, oils or liquids). Solvent) and grinding accelerator (eg, abrasive particles)
And forming a slurry, and then stirring the slurry at high speed, such as in a stirred ball mill or attritor. Viscosity modifiers may also be added to the matrix, for example in the case of solution weight SBR. Once stirring is complete, the solvent can be removed, for example, by vacuum drying, steam purge, or freeze drying. The mixture may then be molded as is or subjected to further high shear mixing, for example on a Banbury or twin-roll mill, and then molded.

During compounding, the amount of fibrils is selected to match the desired amount of fibrils in the final composite and may be added directly to the elastomeric matrix. However, the fibril-filled composite may be manufactured as follows. The elastomer and a large amount (25 parts) of fibrils are first combined to form a masterbatch. Next, an appropriate amount of masterbatch designed to obtain the desired amount of fibrils in the final composite (eg, 5-10 parts) is mixed with the additional elastomer as described above and the final composite Form the body.

The composites can be formed into various articles by the application of heat or resistance or induction heating using conventional elastomer molding techniques. Particularly useful articles include tires and tire articles such as treads and casings, sealants, and vibration absorbers. Uncured composites are useful as adhesives and binders, for example, as repair formulations for tires and conveyors. The adhesive can be cured in place by induction or resistive heating. Physical properties (e.g., tire pressure) of articles made from fibril-filled elastomers can be monitored and detected electrically.

In addition to the above-mentioned carbon fibrils, for example, Gias
s) as defined by others in European Patent Application 0 198 558, published October 22, 1986, as having a crystalline graphite structure and a graphite layer arranged along a fibril axis in a fishbone configuration. Fibrils having a morphology that is optimized are also suitable. These fibrils are produced by depositing hydrocarbon gas at a temperature of from 250 to 800 ° C. on a single crystal metal particle catalyst (eg iron) having a diameter of at least 5 nm.

Friction Material A preferred friction material comprises an organic resin binder loaded with carbon fibrils and other fillers. The relative amounts of the components will depend on the particular application for which the friction material is intended. For high load applications, such as, for example, brake shoes for large trucks where fade resistance and stopping power are a concern, more fibrils will be used compared to a disc brake pad in a motor vehicle. Typically, the amount of fibrils is up to 20% by weight of the composition, based on the resin.

The resin binder must be able to withstand the elevated temperatures encountered during use. Phenolic resins are preferred because they have excellent resistance to thermal degradation and are relatively inexpensive. In addition to fibrils, preferred fillers include metal (eg, brass) fibers, polyaramid fibers (eg, EI
Kevlar fibers commercially available from Dupont de Numer and Company), mineral fillers such as diatomaceous earth and barium sulfate, graphite, and chopped carbon fibers. By incorporating fibrils, the amount of these additives can be reduced compared to conventional friction material compositions.

Preferred fibrils are disclosed in U.S. Pat.
No. 663,230; US patent application Serial by Tenet et al.
No.871,675; U.S. Patent Application Serial by Tenet et al.
No.871,676; U.S. Patent Application by Snyder et al. Seria
l No. 149,573; and U.S. Patent Application Serial No. 285,817 to Mandeville et al., having a graphite layer of small diameter (preferably 3.5-75 nm), substantially parallel to the fibril axis; It has substantially no pyrolytic carbon outer coating. These fibrils are manufactured as described in the aforementioned patents and patent applications. As described in U.S. Patent Application Serial No. 351,967 by McCarthy et al.
The fibril surface may be treated to introduce an oxygen-containing functional group.

The friction material is obtained by dry mixing the resin, fibrils, and other additives under shear, and then subjecting the resulting mixture to conventional thermoset molding methods at elevated temperatures, such as pressing or combined die molding. It is manufactured by molding using. A friction material containing 8% by weight of carbon fibrils (as described above) in phenolic resin, and also including metal fibers, diatomaceous earth, barium sulfate, Kevlar polyaramid fibers, graphite, and carbon fibers, is formed into a disk brake backing plate. Manufactured. The brakes exhibited lower fade (as measured by the Dynomometer test) compared to the composition without fibrils, and improved friction at elevated temperatures. The brakes also exhibited improved resistance to cracking and spalling at elevated temperatures (750 ° F).

Hybrid Composites Preferred hybrid composites are those wherein the primary reinforcing agent comprises continuous or discontinuous fibers having an average diameter on the order of about 1-10 microns and the secondary reinforcing agent comprises carbon fibrils. Preferred fibrils are disclosed in U.S. Pat.
No. 0; US Patent Application Serial No. 87 by Tenet et al.
1,675; U.S. Patent Application Serial No. 87 by Tenet et al.
1,676; U.S. Patent Application Serial No.
149,573; and U.S. Patent Application Seri by Mandeville et al.
al. No. 285,817, having a small diameter (preferably 3.5-75 nm), a graphite layer substantially parallel to the fibril axis, and having substantially no continuous pyrolytic carbon outer coating. It is. These fibrils are manufactured as described in the aforementioned patents and patent applications. The fibrils may be treated to introduce oxygen-containing functional groups on the fibril surface, as described in U.S. Patent Application Serial No. 351,967 to McCarthy et al.

Composites are unidirectional composites (i.e. composites in which the primary reinforcing agent is individual continuous fibers, all of which are arranged parallel to each other, so that they are reinforced primarily in the matrix in only one direction). Two-dimensional layers or laminates of unidirectional tapes or fabrics (i.e., a composite in which the primary reinforcing agent is a continuous fiber and reinforces the matrix in more than one direction in a single plane) ), Multidimensional layers or laminates (i.e., composites in which reinforcement by continuous fibers are not limited to a single surface), and discontinuous fiber reinforced isotropic composites (i.e., as primary reinforcing agents) Discontinuous fibers, such as chopped glass or carbon fibers, or composites in which carbon whiskers are randomly oriented throughout the matrix to provide uniform reinforcement). Thermosetting resins are preferred when the primary reinforcing agent is continuous fibers, but both thermoplastic and thermosetting resins are suitable for discontinuous fibers.

The figure shows a two-dimensional textile laminate 10 in which the epoxy matrix 12 is reinforced with layers of primary reinforcing fibers 14 and carbon fibrils 16. The primary fibers 12 are polyacrylonitrile-based carbon fibers. Each layer of primary fiber is woven in a single plane in two mutually perpendicular directions with an epoxy matrix
12 are reinforced. Carbon fibrils 16 are matrix 12
It is uniformly distributed throughout and randomly oriented with respect to the primary fibers 14.

The composite is manufactured as follows. The fibrils are dispersed throughout the resin (in the form of a viscous liquid, paste, or melt for ease of mixing) to form a prepreg. A particularly effective method for obtaining a well-dispersed prepreg in which the majority of the fibril aggregates have an average diameter of less than 0.5 μm is described in the “Uniform Fibrils, matrices, and any other fillers, as described in U.S. Patent Application Serial No., entitled "Preparation of Dispersions," which is incorporated herein by reference in its entirety. Combine with a low viscosity additive (eg, an oil or liquid solvent) and a grinding aid (eg, abrasive particles such as grit particles) to form a slurry, and then slurry the slurry at high speed, eg, a stirred ball mill or attrition. Including stirring in the machine. Once stirring is complete, the solvent can be removed, for example, by vacuum drying, steam purge, or freeze drying. If the primary reinforcing agents are discontinuous fibers, they can be added to the resin together with the fibrils. If the primary reinforcing agent is a continuous fiber, apply the resin-fibril mixture to the primary reinforcing agent using conventional impregnation techniques and take care that the resin-fibril mixture properly wets the primary reinforcing agent. The composite is then molded and cured using conventional molding techniques. The composite shown in the drawing was produced as follows.

9 parts of N, N, N ', N'-tetraglycidyl-4,4'-methylenebisbenzeneamine (MY720 from Ciba-Geigy)
1 part bisphenol A and epichlorohydrin (commercially available as epoxy) (GY60 from Ciba Geigy)
10 epoxy) and 5 parts of 4,4 '
A diaminodiphenyl sulfone hardener (commercially available as HT976 hardener from Ciba Geigy) with a volume of carbon fibrils (produced as described in the application by Snyder et al.); The fibrils were mixed (as described in the Creeham application) using a stirred ball mill until homogeneously dispersed throughout the resin. The fibril volume fraction of the prepared samples was in the range of 0.01 to 0.05 based on total resin content. The mixture was then coated with a woven polyacrylonitrile-based carbon fiber fabric [24 × 23 (± 1) yarn number and 10.7 oz / square yard (± 1) area density of Celion (Ce).
lion) 3K yard Techniweave 8 Harness Satin Weave 8HS style
3K-175-8H] was applied by hand to a six-ply laminate. The volume fraction of the composite fabric was 0.60 ± 0.02. The resulting composite was then molded and cured to form the final composite structure. The properties of the composite with a fibril volume fraction of 0.025 were measured and compared to a control sample without fibril. The results show that randomly oriented, uniformly dispersed fibrils have matrix-driven properties such as compressive strength, short-range shear strength, in-plane shear strength, trans-layer resistivity,
And improved matrix component driven properties, such as flexural strength and modulus, without interfering with continuous fiber driven properties, such as tensile strength and modulus.

 Other aspects are included in the following claims.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI C08J 5/18 C08J 5/18 C08L 101/16 C09D 11/00 C09D 11/00 H01B 1/20 H01B 1/20 C08L 101/00 // B29K 105: 06 (31) Priority claim number 386,912 (32) Priority date July 27, 2001 (July 27, 1989) (33) Priority claim country United States (US) (31) Priority claim number 386,822 (32) Priority date July 27, 2001 (July 27, 1989) (33) Priority claiming country United States (US) (31) Priority claim number 386,829 (32) Priority date Heisei 1 July 27, 1989 (July 27, 1989) (33) Priority country United States (US) (31) Priority number 386,828 (32) Priority date July 27, 2001 (July 27, 1989) 27) (33) Priority Countries United States (US) (72) Inventor Barber, James, Jay. Kimball Road, Arlington, Mass. 02174 United States 24 (72) Kuriha, Inventor United States 02174 Arlington, Mass., Sutherland Road 66 (72) Inventor Snyder, Carl, E. United States 44224 Silver Lake, Ohio Silverview Drive 2978 (56) References JP 60 JP-A-125612 (JP, A) JP-A-58-201829 (JP, A) JP-A-55-157672 (JP, A) JP-A-56-107053 (JP, A) JP-A-62-299412 (JP, A) JP-A-54-8251 (JP, A) JP-A-61-218669 (JP, A) JP-A-3-55709 (JP, A) JP-A-62-500943 (JP, A) (58) Field (Int. Cl. ⁷ , DB name) C08K 7/06 C09D 11/00

Claims (49)

(57) [Claims] 1. The composition according to claim 1, wherein said dispersion is 0.5 to 20% by weight, uniformly dispersed,
An electrically conductive molded composite comprising a reaction injection molded polymer matrix comprising carbon fibrils having a diameter of 75 nm (inclusive) and having a length to diameter ratio of at least 5. wherein said fibrils are: In the form of aggregates,
An electrically conductive molded composite having a diameter of 1000 times or less the diameter of the fibril. 2. The composition according to claim 1, wherein said dispersion is from 0.5 to 20% by weight, uniformly dispersed.
An electrically conductive composite comprising a molded product of a premix comprising a polymer resin matrix comprising carbon fibrils having a diameter of 75 nm (inclusive) and a length to diameter ratio of at least 5. The electrically conductive composite, wherein the fibrils are in the form of an aggregate, the diameter of which is 1000 times or less the diameter of the fibrils. 3. The composite of claim 1 or 2, wherein the amount of fibrils is sufficient to provide the composite with sufficient electrical conductivity to directly electrostatically coat the surface. . 4. The composite according to claim 1, wherein the electrical conductivity of the composite is higher than that of a composite of the same matrix filled with the same amount of carbon black. 5. The composite of claim 1 or 2, wherein the amount of fibrils is sufficient to impart sufficient electrical conductivity to the composite to dissipate static electricity. 6. The composite of claim 1 or 2, wherein the fibrils comprise a tube having a graphite layer substantially parallel to the fibril axis and have substantially no continuous pyrolytic carbon outer coating. 7. The method according to claim 7, wherein the outer surface of the graphite layer comprises a plurality of
Or the complex according to claim 6, which is bound to a derivative thereof. 8. The composite according to claim 1, wherein the matrix is made of a thermoplastic material. 9. The composite according to claim 1, wherein the matrix comprises a thermosetting material. 10. An electrically conductive composite composition in a form suitable for reaction injection molding, comprising one or more liquid reactants that can be injected into a mold, polymerize therein, and form a reaction injection molded polymer matrix. Wherein the complex is 0.5
-20% by weight of uniformly dispersed carbon fibrils having a diameter of 3.5-75 nm (inclusive of the figures at both ends) and having a length to diameter ratio of at least 5, wherein said fibrils are formed of aggregates. Form, whose diameter is 10 times the diameter of the fibril
An electrically conductive composite composition that is not more than 00 times. 11. A resin and having a diameter of 3.5 to 75 nm (inclusive), uniformly dispersed of 0.5 to 20% by weight,
A pre-mixture composition comprising carbon fibrils having a length to diameter ratio of at least 5 wherein said fibrils are in the form of agglomerates and wherein the diameter is 10 times the diameter of the fibrils.
A pre-mix composition of up to 00 times. 12. The composition of claim 10 wherein the fibrils comprise a tube having a graphite layer substantially parallel to the fibril axis and substantially free of a continuous pyrolytic carbon outer coating. 13. The composition according to claim 12, wherein the outer surface of the graphite layer is bonded to a plurality of oxygen-containing groups or derivatives thereof. 14. The liquid reactant is one or more polyols,
11.A polyisocyanate or a polyamine.
A composition according to claim 1. 15. The composition according to claim 11, wherein the resin comprises a thermosetting resin. 16. A method for producing a conductive composite comprising a reaction injection molded matrix in which 0.5 to 20% by weight of carbon fibrils are uniformly dispersed in a matrix material, wherein the matrix can be formed by polymerization. Mixing fibrils with one or more liquid reactants to obtain a mixture, introducing the mixture into a mold, and molding the mixture under reaction conditions including pressure and temperature to form a composite in the form of a molded part Wherein the fibrils are in the form of agglomerates, and the step of mixing the fibrils and the matrix material comprises reducing the diameter of the aggregates formed by the fibrils to 1000 times the diameter of the fibrils.
A method for producing a conductive composite, which comprises applying a combined force of shear and impact under reaction conditions including a reaction time sufficient to reduce by a factor of two or less. 17. A method for producing a conductive composite comprising a sheet-like molding compound in which 0.5 to 20% by weight of carbon fibrils is uniformly dispersed in a matrix material, wherein the fibrils are mixed with a resin, and the mixture is mixed. Obtaining, and forming the mixture into a sheet, wherein the fibrils are in the form of agglomerates, and the step of mixing the fibrils and the matrix material reduces the diameter of the aggregates formed by the fibrils to the diameter of the fibrils. 1000
A method for producing a conductive composite, which comprises applying a combined force of shear and impact under reaction conditions including a reaction time sufficient to reduce by a factor of two or less. 18. The method of claim 16, further comprising forming the composite under reaction conditions including pressure and temperature to produce the composite in the form of a molded part. 19. A method for producing a composite comprising a bulk molding compound in which 0.5 to 20% by weight of carbon fibrils are uniformly dispersed in a matrix material, wherein the fibrils are mixed with a resin and are suitable for molding. Forming a putty, wherein the fibrils are in the form of agglomerates, and the step of mixing the fibrils and the matrix material reduces the diameter of the aggregates formed by the fibrils to 1000 times the diameter of the fibrils.
A method for producing a conductive composite, wherein a combined force of shear and impact is applied under reaction conditions including a reaction time sufficient to reduce the concentration to less than two-fold. 20. The method of claim 19, further comprising molding the composite under reaction conditions including pressure and temperature to produce the composite in the form of a molded part. 21. The method according to claim 16, further comprising direct electrostatic coating of the surface of the molded part. 22. A brake or component thereof comprising a friction material comprising a matrix comprising 0.5 to 20% by weight of uniformly dispersed carbon fibrils, said matrix comprising a group consisting of a phenolic resin, a polyester resin and an epoxy resin. Or a component thereof, wherein the fibril is in the form of an agglomerate having a diameter less than 1000 times the diameter of the fibril. 23. A clutch or component comprising a friction material comprising a matrix comprising 0.5 to 20% by weight of uniformly dispersed carbon fibrils, said matrix comprising a phenolic resin, a polyester resin and an epoxy resin. Or a component thereof, wherein the fibril is in the form of an agglomerate having a diameter of 1000 times or less the diameter of the fibril. 24. An automatic transmission disc or component thereof comprising a friction material comprising a matrix comprising 0.5 to 20% by weight of uniformly dispersed carbon fibrils, said matrix comprising a phenolic resin, a polyester resin and an epoxy resin. An automatic transmission disc or part thereof comprising a resin selected from the group consisting of: wherein said fibrils are in the form of agglomerates having a diameter less than 1000 times the diameter of the fibrils. 25. The fibril according to claim 22, 23 or 24, wherein the fibril comprises a tube having a layer of graphite substantially parallel to the fibril axis, wherein the fibril has a length to diameter ratio of at least 5. Goods. 26. The article of claim 25, wherein the fibrils have a diameter of 3.5-75 nm (inclusive) and are substantially free of a continuous pyrolytic carbon outer coating. 27. An outer surface of a graphite layer comprising a plurality of oxygen-containing groups,
26. The article of claim 25, wherein the article is bound to a derivative thereof. 28. The matrix of claim 22, wherein the matrix comprises carbon.
Or the article according to any one of 24. 29. The article according to claim 22, further comprising one or more fillers selected from the group consisting of metal, glass, ceramic, carbon, or polyaramid fibers. 30. A filler comprising graphite, clay, barium sulfate,
30. The article according to claim 29, comprising one or more of diatomaceous earth, silica, magnesia, beryllia, alumina, silicon carbide, titanium dioxide, and carbon black. 31. A composite in the form of a friction material comprising a matrix material and 0.5-20% by weight of uniformly dispersed carbon fibrils, wherein said matrix is a group consisting of a phenolic resin, a polyester resin and an epoxy resin. A composite in the form of a friction material, wherein the fibril is in the form of an agglomerate having a diameter no greater than 1000 times the diameter of the fibril. 32. The fibril comprises a tube having a graphite layer substantially parallel to the fibril axis, said fibril having a length to diameter ratio of at least 5 and a diameter of 3.5 to 75 nm (inclusive). 32. The composite of claim 31, wherein said composite is substantially free of a continuous pyrolytic carbon outer coating. 33. A composite comprising an elastomeric matrix and carbon fibrils in the form of aggregates, wherein the fibrils have no continuous pyrolytic carbon outer coating;
A composite comprising a tube having a graphite layer substantially parallel to a fibril axis, wherein the aggregate has a diameter of 1000 times or less the diameter of the fibril. 34. The complex according to claim 33, wherein the diameter of the fibrils is 3.5 to 75 nm (including the numbers at both ends). 35. A composite comprising an elastomeric matrix and carbon fibrils in the form of agglomerates, wherein the fibrils have a crystalline graphite structure and are defined as a fishbone-like array of graphite layers along a fibril axis. A fibril having a diameter of less than 100 nm, wherein the aggregate has a diameter of 1000 times or less the diameter of the fibril. 36. The method according to claim 33, wherein the matrix of the elastomer is selected from the group consisting of natural rubber, styrene-butadiene rubber, polyisoprene, neoprene, chloroprene, polybutadiene, fluoroelastomer, silicone rubber, and urethane estomer. The conjugate of claim 1. 37. The method further comprising at least one filler.
The composite according to claim 33 or 35, wherein the filler is carbon black, silica, or a combination thereof. 38. The composite of claim 37, wherein the ratio of the amount of fibrils to the total amount of filler is at least 1: 4. 39. The composite of claim 33 or 35, wherein the amount of fibrils in the composite is less than 25 parts per 100 parts of elastomer. 40. The composite according to claim 33, wherein the amount of fibrils in the composite is sufficiently higher than the amount capable of curing the composite by resistance or induction heating. 41. The composite according to claim 33, wherein the amount of fibrils in the composite is sufficient to cure the composite by resistance or induction heating. 42. The amount of fibrils in the complex is sufficiently higher than the amount capable of electrically monitoring and detecting at least one of the physical properties of the complex.
The complex according to any one of the above. 43. The conjugate according to claim 33, wherein the amount of fibrils in the conjugate is sufficient to electrically monitor and detect at least one of the physical properties of the conjugate. . 44. The composite according to claim 33, wherein the composite is in the form of an elastomer solution. 45. A tire or a part thereof comprising the composite according to claim 33 or 35. 46. A sealant comprising the composite according to claim 33. 47. An adhesive comprising the composite according to claim 33 or 35. 48. A process for uniformly dispersing a sufficient amount of carbon fibrils in an elastomer matrix to improve the mechanical properties of the elastomer, wherein the fibrils have a crystalline graphite structure and have a fibril axis. A method of reinforcing an elastomer having a morphology defined as a fishbone-like array of graphite layers along which said fibrils are in the form of agglomerates having a diameter less than 1000 times the diameter of the fibrils. 49. mixing at least one filler and a matrix material to produce a mixture; and combining the filler with the matrix material to determine the diameter of agglomerates formed by the filler. Manufactured by a compounding method that includes the step of subjecting the filler to disperse throughout the matrix material under combined reaction of shear and impact under reaction conditions including reaction time sufficient to reduce the diameter to less than 100 times. Complex.