MXPA06014287A

MXPA06014287A - Acrylic and para-aramid pulp and processes of making same.

Info

Publication number: MXPA06014287A
Application number: MXPA06014287A
Authority: MX
Inventors: Jill A Conley; Edmund A Merriman
Original assignee: Du Pont
Priority date: 2004-06-25
Filing date: 2005-06-16
Publication date: 2007-02-19
Also published as: KR20080092979A; KR100917963B1; EP1774095B1; CN1973085A; EP1774095A1; CN1973085B; KR20070030227A; JP2008503660A; CA2568016C; WO2006012040A1; DE602005013966D1; JP5209303B2; CA2568016A1; US20050287344A1; BRPI0512484A; KR100864357B1

Abstract

The present invention relates to acrylic and para-aramid pulp for use as reinforcement material in products such as seals and friction materials. The pulp comprises (a) irregularly shaped, acrylic fibrous structures, (b) irregularly shaped, para-aramid fibrous structures, and (c) water, whereby acrylic fibrils and/or stalks are substantially entangled with para-aramid fibrils and/or stalks. The invention further relates to processes for making such acrylic and aramid pulp.

Description

PULP OF ACRYLIC AND PARA-ARAMIDA AND PROCESS OF MANUFACTURE OF THE SAME FIELD OF THE INVENTION This invention relates to acrylic pulp and para-aramid to be used as reinforcement material in products, such as sealing and friction materials. The invention also relates to processes for manufacturing such pulp. BACKGROUND OF THE INVENTION Fibrous and non-fibrous reinforcing materials have been used for many years in friction products, sealing products, and other plastic or rubber products. Such reinforcing materials typically must exhibit high resistance to wear and heat. Historically, asbestos fibers have been used as reinforcement materials, but due to the health risks, replacements have been manufactured or proposed. However, many of these replacements do not perform as well as asbestos in some other way. Research Disclosure magazine 74-75, published in February 1980, describes the manufacture of pulp made of fibrillated KEVLAR® brand para-mide fibers of varying lengths and uses of the pulp such as a Ref. : 177411 reinforcement in several applications. This publication describes that pulp made from para-aramid fibers brand KEVLAR® can be used in single rolled products, or in combination with fibers from other materials, such as meta-aramid brand NOMEX®, wood pulp, cotton and other natural cellulosics, rayon, polyester, polyolefins, nylon, polytetrafluoroethylene, asbestos and other minerals, glass fibers and others, ceramics, steel and other metals, and carbon. The publication also describes the use of pulp from para-ami single fiber to KEVLAR® brand, or with short KAVLAR® para-aramid fibers, in friction materials to replace a fraction of the asbestos volumes, replacing the remaining portion of the asbestos volumes by fillers or other fibers. U.S. Patent 5,811,042 (by Hoiness) discloses a composite material for sealing or friction gaskets made with a thermosetting or thermoplastic matrix resin, fiber reinforcing material, and aramid particles substantially free of fibril. The poly (p-phenylene p-terephthalamide) and the poly (phenylene m-isophthalamide) are the preferred fiber reinforcing materials, and the fibers can have the form of flocculation or pulp. US Patent Application 2003/0022961 (by Kusaka et al.) Discloses friction materials manufactured from a friction modifier, a binder and a fibrous reinforcement made from a mixture of (a) a dry aramid pulp and (b) ) wet aramid pulp, wood pulp or acrylic pulp. The dry aramid pulp is defined as an aramid pulp obtained by the "dry fibrillation method". The method of dry fibrillation is dry milling of the aramid fibers between a rotary cutter and a mesh to prepare the pulp. The wet aramid pulp is defined as an aramid pulp obtained by "the wet fibrillation method". The wet fibrillation method is the grinding of short aramid fibers in water between rotating discs to form fibrillated fibers and then dehydrating the fibrillated fibers, in this case, the pulp. Kusaks et al also describes a method for mixing-fibrillating fibers by first mixing multiple types of organic fibers that are fibrillated at a given ratio, and then fibrillaring the mixture to produce a pulp. There is a current need to provide reinforcing materials that perform well in products, both in sealing and friction applications, and that are inexpensive. Despite the numerous descriptions that propose lower cost alternative reinforcement materials, many of these proposed products do not perform properly during use, they are more expensive than current commercial products, or have other negative attributes. Therefore, a need remains for reinforcing materials that exhibit high wear and temperature resistance, and that are comparable or less expensive than other commercially available reinforcing materials. SUMMARY OF THE INVENTION The invention relates to a first embodiment of a process for manufacturing an acrylic or para-amide pulp for use as a reinforcement material, comprising: (a) combining pulp ingredients including: (1) Acrylic fiber comprising acrylonitrile units which are at least 85% by weight of the total acrylic fiber, the fiber is from 10 to 90% by weight of the total solids in the ingredients, and have an average length no greater 10 cm; (2) para-aramid fiber which is from 10 to 90% by weight of the total solids in the ingredients, and which has an average length of not more than 10 cm; and (3) water that is 95 to 99% by weight of the total ingredients; (b) mixing the ingredients to form a substantially uniform slurry; (c) co-refine the slurry by simultaneously performing: (1) fibrillating, cutting and chewing the acrylic fiber and the para-amide fiber to obtain fibrillated fibrillated structures irregularly formed with stems and fibrils; and (2) substantially uniformly dispersing all solids in the refined slurry; and (d) extracting the water from the refined slurry to not more than 60% by weight of the total water, thereby producing an acrylic and para-amide pulp with fibrous acrylic and para-amide structures having a average maximum dimension no greater than 5 mm, an average calculated length no greater than 1.3 mm, and the fibrils and / or acrylic stems are substantially entangled with the fibrils and / or para-amide stems. The invention is further related to a second embodiment of a process for manufacturing an acrylic and para-amide pulp for use as a reinforcing material, comprising: (a) combining ingredients including water and a first fiber of the group consisting of (1) Acrylic fiber comprising acrylonitrile units which are at least 85% by weight of the total acrylic fiber, the fiber is from 10 to 90% by weight of the total solids in the ingredients; and (2) para-aramid fiber which is from 10 to 90% by weight of the total solids in the ingredients; (b) mixing the ingredients to form a substantially uniform suspension; (c) refining the suspension in a disk refiner thereby cutting the fiber to have an average length of no more than 10 cm, and fibrillating and chewing at least some of the fiber up to fibrillated fibrous structures formed irregularly; (d) combining ingredients including the refined suspension, the second fiber of the group of (a) (1 and 2), and water, if necessary, increasing the water concentration to 95-99% by weight of the total ingredients; (e) mixing the ingredients, if necessary, to form a substantially uniform suspension; (d) co-refine the mixed suspension by performing: (1) fibrillating, cutting and chewing solids in the suspension so that all or substantially all of the acrylic and para-amide fiber is converted into fibrous structures of acrylic and para-amide fibrillated irregularly formed with stems and fibrils; and (2) substantially uniformly dispersing all solids in the refined slurry; and (h) extracting water from the refined slurry to not more than 60% by weight of the total water, thereby producing an acrylic and para-amide pulp with the acrylic fibrous structures and those of para-amide having a average maximum dimension no greater than 5 mm, an average calculated length no greater than 1.3 mm, and the fibrils and / or acrylic stems are substantially entangled with the fibrils and / or para-amide stems. The invention is further directed to an acrylic and para-amide pulp for use as a reinforcing material, comprising: (a) irregularly formed acrylic fibrous structures comprising acrylonitrile units which are at least 85% by weight of the total of fibrous acrylic structures and are from 10 to 90% by weight of the total solids; (b) irregularly formed para-aramid fibrous structures that are from 10 to 90% by weight of the total solids; and (c) water which is from 4 to 60% by weight of the whole pulp, whereby the fibrous structures of acrylic and para-aramid have an average maximum dimension of not more than 5 mm, an average-calculated length not greater than 1.3 mm, and stems and fibrils wherein the fibrils and / or acrylic stems are substantially entangled with the fibrils and / or para-aramid stems. The invention is further directed to a friction material, comprising a friction modifier; optionally at least one filler; a binder; and a fibrous reinforcing material comprising the pulp of the present invention. Furthermore, the invention is directed to a sealing material, comprising a binder, optionally at least one filler; and a fibrous reinforcing material comprising the pulp of the present invention. BRIEF DESCRIPTION OF THE FIGURES The invention can be more fully understood from the following detailed description thereof in connection with the accompanying Figures described below. Figure 1 is a schematic diagram of the apparatus for developing a wet process for manufacturing "wet" pulp in accordance with the present invention. Figure 2 is a schematic diagram of an apparatus for developing a dry process for manufacturing a "dry" pulp in accordance with the present invention. Figure 3 is an image of a photomicrograph of the para-amide particles used as an optional ingredient for the process of the present invention. Figure 4 is an image of a photomicrograph of the pulp made in accordance with the process of the present invention. GLOSSARY Before describing the invention, it is useful to define certain terms in the following glossary that will have the same meaning throughout this description unless otherwise indicated. "Fiber" means a relatively flexible unit of matter that has a high ratio of length to width across its cross-sectional area perpendicular to its length. Here, the term "fiber" is used interchangeably with the term "filament" or "end". The cross section of the filaments described herein can be of any shape, but is typically circular or bean shaped. The fiber wound onto a coil in a package is referred to as a continuous fiber. The fiber can be cut into short lengths referred to as short fiber. The fiber can be cut even in shorter lengths called floculate. The yarn, the yarns or multi-filament tow comprise a plurality of fibers. The yarn may be interwoven and / or braided. "Fibrilla" means a small fiber that has a small diameter of the order that goes from a miera to a few microns and has an approximate length from 10 to 100 microns. The fibrils generally extend from the main trunk of a longer fiber that has a diameter of 4 to 50 microns. The fibrils act as hooks or clips to trap and capture adjacent material. Some fibers are fibrillar, but others are not, or can not fibrillate effectively and for the purposes of this definition such fibers are not fibrillar. The fiber of poly (para-terfeftalamide of phenylene) can easily fibrillate under abrasion, creating fibrils. The acrylic fibers of this invention are also fibrillar. "Fibrillated fibrous structures" means particles of material having lamina and fibrils extending therefrom where the stem generally has a tubular shape and of an approximate diameter of 10 to 50 microns and the fibrils are hair-like members only. a fraction of a millimeter or a few millimeters in diameter joins the stem and approximately have a length of 10 to 100 microns.

"Flocculation" means short fiber lengths, shorter than a short fiber. The length of the flocculation is about 0.5 to about 15 mm and of a diameter of 4 to 50 microns, preferably they have a length of 1 to 12 mm and with a diameter of 8 to 40 microns. Flocculation that is less than about 1 mm does not contribute significantly to the strength of the material in which it is used. Flocculation or fiber that is greater than about 25 mm often does not work well because the individual fibers can become entangled and can not be distributed properly and uniformly throughout the material or slurry. Aramid flocculation is manufactured by cutting aramid fibers in short lengths without significant or no fibrillation, such as those prepared by the process described in US Pat. Nos. 3,063,966; 3,133,138; 3,767, 756, and 3,869,430. "Average calculated-length" means the calculated length from the following formula: S [(Each individual pulp length) 2] Average-calculated length = S [Each individual pulp length] "Maximum dimension" of an object means the distance in a straight line between the two points most distal to each other in the object. "Short fiber" can be manufactured by cutting filaments in lengths no greater than 15 cm, preferably 3 to 15 cm; and most preferably from 3 to 8 cm. The short fiber can be straight (in this case not corrugated) or corrugated to have a wave in the form of sawtooth along its entire length, with any frequency of corrugation (or repetition of curve). The fibers may be uncoated, or coated, or otherwise pretreated (for example, pre-stretched or heat-treated).

DETAILED DESCRIPTION OF THE INVENTION The invention is directed to the processes for manufacturing an acrylic and para-amide pulp to be used as reinforcement material. The invention is also directed to acrylic pulp and para-aramid, which can be manufactured with the process of the present invention, to be used as a reinforcing material. The invention is further directed to products, such as sealing materials and friction materials, which incorporate the pulp of this invention, and the processes for manufacturing it. I. First Modality of the Inventive Process In a first embodiment, the process for manufacturing an acrylic and para-amide pulp comprises the following steps. First, the pulp ingredients are combined, added or put in contact together. Second, the combined pulp ingredients are blended to form a substantially uniform slurry. Third, the slurry is simultaneously refined or co-refined. Fourth, the water is extracted from the refined slurry. Combination Step In the combination step, the pulp ingredients are preferably added together in a container. The pulp ingredients include (1) acrylic fiber, (2) para-aramid fiber, (3) optionally para-aramid particles, granular, substantially or completely fibril-free, (4) optionally other minor additives, and ( 5) water. Acrylic Fiber Acrylic fiber is added to a concentration of 10 to 90% by weight of the total solids in the ingredients, preferably 25 to 60% of the total solids in the ingredients, and most preferably 25 to 55% by weight of the total solids in the ingredients. The acrylic fiber preferably has an average length of no more than 10 cm, more preferably 0.5 to 5 cm, and most preferably 0.6 to 2 cm. Prior to combining the pulp ingredients together, any of the acrylic fibers in the form of continuous filaments can be cut into shorter fibers, such as short fibers or flocculation. Acrylic Polymer The acrylic fiber that is useful in this invention includes the units which are at least 85% by weight of the total acrylic fiber. One unit of acrylonitrile is - (CH2-CHCN) -. The acrylic fiber can be made of acrylic polymers composed of up to 85% by weight or more of acrylonitrile with 15% by weight or less of an ethylenic monomer copolymerizable with acrylonitrile and mixtures of two or more of these acrylic polymers. Examples of ethylenic monomers copolymerizable with acrylonitrile include acyclic acid, methacrylic acid, and esters thereof (methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, etc.), vinyl acetate, vinyl chloride, vinylidene chloride, acrylamide, methacilamide, methacrylonitrile, allylsulfonic acid, acid methanesulfonic acid and styrenesulfonic acid. Fiber-of-Para_Aramide The para-aramid fiber is added to a concentration of 10 to 90% by weight of the total solids in the ingredients, preferably 40 to 75% by weight of the total solids in the ingredients, and most preferably from 40 to 55% by weight of the total solids in the ingredients. The para-aramid fiber preferably has a linear density of no more than 10 dtex, more preferably 0.5 to 10 dtex, and most preferably, 0.8 to 2.5 dtex. The para-aramid fiber also preferably has an average length along its longitudinal axis no greater than 10 cm, more preferably an average length of 0.65 to 2.5 cm, and most preferably an average length of 0.65 to 1.25 cm. Para-Aramid Particles Optionally, in one embodiment, the pulp ingredients further include para-aramid, granular, substantially or completely fibril-free particles. If these particles are added, they are added to a concentration of not more than 50% of the total solids in the ingredients, preferably from 20 to 50% by weight of the total solids in the ingredients, and most preferably from 25 to 35% by weight in the ingredients. weight of the total solids in the ingredients. Being composed of para-aramid, they contribute to a superior wear resistance and to the dispersion capacity of the pulp that is being produced. Because the particles are substantially free of fibril, they also function as a composition agent to assist in the dispersion of the other ingredients in the mixture and in the slurry. Particles that develop this function are often known as agents or processing aids. The para-aramid particles substantially or completely free-fibril, granular has a maximum average dimension of 0 to 2000 microns (0.05 to 2 mm), preferably 50 to 1500 microns, and most preferably 75 to 1000 microns. Particles below about 50 microns, however, lose effectiveness in friction and sealing applications. Particles above 2000 microns do not remain adequately dispersed in the water with the other ingredients when mixed. Figure 5 is an image of a photomicrograph of para-aramid particles with the ability to be used as an ingredient for the process of the present invention.

Aramid Polymer Suitable polymers for use in the manufacture of the aramid fiber and aramid particles of this invention are synthetic aromatic polyamides. The polymers must be of a molecular weight of formation-fiber for the purpose of being formed into fibers. The polymers can include polyamide homopolymers, copolymers, and mixtures thereof which are predominantly aromatic, wherein at least 85% of the amide bonds (-CONH-) are directly coupled to two aromatic rings. The rings can be unsubstituted or substituted. The polymers are para-amide when the two rings are oriented towards one another along the molecular chain. Preferably the copolymers do not have more than 10 percent of other substituted diamines for a primary diamine used in the formation of the polymer or not more than 10 percent of the other substituted diacid chlorides for a primary diacid chloride used in polymer formation. The additives can be used with aramid; and it has been found that up to 13 weight percent of the other materials can be mixed or bound with the aramid. Preferred para-aramides are poly (phenylene para-terephthalamide) (PPD-T) and its copolymers.

Other Optional Additives Optionally other additives can be added as long as they remain suspended in the solution in the mixing step and do not significantly change the effect of the refining step with respect to the indispensable solid ingredients listed above. Suitable additives include pigments, inks, anti-oxidants, flame-retardant compounds, and other processing and dispersion aids. Preferably, the pulp ingredients do not include the asbestos. In other words, the resulting pulp is free of asbestos or asbestos-free. Water Water is added to a concentration of 95 to 99% by weight of the total ingredients, and preferably 97 to 99% by weight of the total ingredients. Additionally, water can be added first. Then the other ingredients can be added in a proportion to optimize the dispersion in the water while simultaneously mixing the combined ingredients. Mixing Step In the mixing step, the ingredients are mixed to form a substantially uniform thick suspension. By "substantially uniform" it is meant that the random samples of the slurry contain the same% by weight of the concentration of each of the starting ingredients as in the total ingredients in the combination step plus or minus 10% by weight , preferably 5% by weight and most preferably 2% by weight. For example, if the concentration of the solids in the total mixture is 50% by weight of acrylic fiber plus 50% by weight of para-aramid fiber, then a substantially uniform mixture in the mixing step means that each random sample of the slurry has (1) an acrylic fiber concentration of 50% by weight more or less than 10% by weight, preferably 5% by weight and most preferably 2% by weight and (2) a concentration of fiber of Aramid of 50% by weight plus or minus 10% by weight, preferably 5% by weight and most preferably 2% by weight. The mixture can be obtained in any container that contains rotating knives or some other agitator. The mixture can occur after the ingredients are added or while the ingredients are added or combined. Refining step In the refinement step the pulp ingredients are co-refined simultaneously, converted or modified as described below. The acrylic fiber and the para-aramid fiber are fibrillated, cut and chewed to irregularly formed fibrous structures having stems and fibrils. If the para-aramid particles are added with the other ingredientsAt least some of the para-aramid particles are chewed into smaller particles, more rounded and substantially free of fibril. All solids are dispersed so that the refined slurry is substantially uniform. "Substantially uniform" according to as defined above. The step of retinating preferably comprises passing the mixed slurry through one or more disk refiners, or recycling the slurry back through an individual refiner. The term "disc refiner" should be interpreted as a refiner that contains one or more pairs of discs that rotate with respect to each other thereby refining the ingredients through the cutting action between the discs. In an appropriate type of disk refiner, the slurry that is being refined is pumped between the circular rotor and stator discs spaced very little that can rotate with respect to each other. Each disk has a surface, which is directed towards the other disk, with at least partially radially extended surface slots. A preferred disk refiner that can be used is described in U.S. Patent 4,472,241. If necessary for uniform dispersion and adequate refinement, the mixed slurry may be passed through the disk refiner more than once or through a series of at least two disk refiners. When the mixed slurry is refined in only one refiner, there is a tendency for the resulting slurry to be improperly refined and not to be uniformly dispersed. The conglomerates or aggregates entirely or substantially of one solid ingredient, or another, or both, or all three if all three are present, can form instead of being dispersed, forming a substantially uniform dispersion. Such conglomerates or aggregates have a greater tendency to separate and to disperse in the slurry when the mixed slurry is passed through the refiner more than once or is passed through more than one refiner. Because a substantially uniform thick slurry containing multiple ingredients is co-refined in this process step, any type of non-pulp ingredient (e.g., para-aramid fiber) is refined within a pulp in the presence of all other types of non-pulp ingredients (for example, pieces of para-aramid material and optionally para-aramid particles) while the other ingredients are also refined. This co-refinement of the other non-pulp ingredients forms a pulp that is superior to a mixed pulp generated by simply mixing two pulps together. Adding two pulps and then simply mixing them together does not form the substantially uniform, intimately connected fibrous components of the pulp generated by co-refining the non-pulp ingredients within the pulp according to the present invention. Extraction Step The water is then extracted from the refined slurry to not more than 60% by total water weight, preferably from 4 to 60% by total water weight, more preferably from 5 to 58% total water. The water can be extracted by collecting the pulp on a drainage device such as a horizontal filter, and if desired, additional water can be extracted by applying pressure to, or squeezing, the filter from the pulp filter. The optionally dewatered pulp can then be dried to a desired moisture content, and / or can be packed or rolled into rolls. Figures 1 and 2 This process will now be described with reference to Figures 1 and 2. Throughout this detailed description, similar reference characters refer to similar elements in all figures. With reference to Figure 1, a schematic diagram of one embodiment of a wet process for making "wet" pulp according to the present invention is shown. The pulp ingredients 1 are added to the container 2. The container 2 is conditioned with an internal mixer, similar to the mixer of a washing machine. The mixer disperses the ingredients within the water creating the substantially uniform slurry. The mixed slurry is transferred to a first refiner 3 which refines the slurry. Then, optionally, the refined slurry may be transferred to a second refiner 4, and optionally thereafter to a third refiner 5. Three refiners are illustrated but any number of refiners may be used depending on the degree of uniformity and refinement desired. After the last refiner in the series of refiners, the refined slurry optionally is transferred to a filter or a classifier 6 which allows the slurry to thicken with the dispersed solids below the size of a selected mesh or grate to pass and recirculate the dispersed solids larger than the size of the selected mesh or grid, return to one or more of the refiners such as through line 7 or to a refiner 8 dedicated to refining this recirculated slurry from which the refined slurry is passed again towards the filter or classifier 6. The appropriate refined slurry passes from the filter or classifier 6 to a vacuum horizontal water filter 9 which extracts water for which the pulp has a water concentration not greater than 75% of the total of ingredients. The slurry can be transferred point-to-point by any conventional method and apparatus such as the operation of one or more pumps 10. The pulp is then transported to a dryer 11 that extracts more water until the pulp has a water concentration not greater than 60% by weight of the total of ingredients. The pulp is then packed in a packer 12. Referring to Figure 2, a schematic diagram of a dry process embodiment for making "dry" pulp according to the present invention is observed. This dry process is the same according to the wet process except in the steps after the horizontal water filter by vacuum 9. After such a filter, the pulp is conducted through a press 13 which extracts more water until the pulp has a water concentration not greater than 20% of the total ingredients. The pulp is then led to a fluffing apparatus 14 to soften the pulp and then a rotor 15 extracts more water. Then, as in the wet process, the pulp is passed through a dryer 11 and is packed in a packer 12. II. Second Modality of the Inventive Process In a second embodiment, the process for manufacturing the acrylic fiber and the para-aramid pulp is the same as that of the first embodiment of the process described above with the following differences. Before combining all the ingredients together, either the acrylic fiber or the para-aramid fiber, or both the acrylic fiber and the para-aramid fiber, may need to be trimmed. This is done by combining water with the fiber ingredient. The water and fiber are then mixed to form a first suspension and processed through a first disk refiner to trim the fiber. The disk refiner cuts the fiber to an average length of no more than 10 cm. The disk refiner will also partially fibrillate and partially chew the fiber. The other fiber, which was not previously added, can also be trimmed in this way by forming a second processed suspension. Then the other fiber (or the second suspension, if processed in water) is combined with the first suspension. More water is added sooner or later, or when, the other ingredients are added, if necessary, to increase the water concentration to 95-99% by weight of the total ingredients. After all the ingredients are combined, these can be mixed, if necessary, to obtain a substantially uniform slurry. The ingredients in the slurry are then co-refined together, in this case, simultaneously. This refinement step includes fibrillating, cutting and chewing solids in the suspension so that all or substantially all of the acrylic fiber and para-aramid is converted to fibrillated fibrillated structures formed irregularly. This step of refining also disperses all the solids so that the refined slurry is substantially uniform. After the water is extracted as in the first mode of the process. Both processes produce the same or substantially the same acrylic and para-aramid pulp. The Inventive Pulp The resulting product produced by the process of this invention is an acrylic pulp and para-aramid to be used as a reinforcement material in products. The pulp comprises (a) irregularly formed acrylic fibrous structures, (b) irregularly formed para-aramid fibrous structures, (c) optionally para-aramid, granular, substantially fibril-free particles, (d) optionally other minor additives, and (e) water. The concentration of the separated ingredient components in the pulp corresponds, of course, to the concentrations described in advance of the corresponding ingredients used in the manufacture of the pulp. The fibrillated structures of fibrillated acrylic and para-aramid, formed irregularly have stems and fibrils. The fibrils and / or acrylic stems are substantially entangled with the fibrils and / or stems of para-aramid. The fibrils are important and act as hooks or fasteners or tentacles which adhere with / and support, the adjacent particles in the pulp and the final product thereby provide integrity to the final product. Fibrillated fibrous acrylic and para-aramid structures preferably have a maximum average dimension of no more than 5mm, more preferably 0.1 to 4mm, and most preferably 0.1 to 3mm. Fibrillated acrylic and para-aramid fibrous structures preferably have an average calculated length of no more than 1.3 mm, more preferably 0.7 to 1.2 mm, and most preferably 0.75 to 1.1 mm. If the para-aramid particles are included in the pulp, the fibrous structures of acrylic and para-aramid also additionally come into contact and are partially wrapped around at least some of these para-aramid particles, substantially free-defibrilla. These para-aramid particles preferably also have a dimension of at least 50 microns, more preferably, 50 to 100 microns, and most preferably 50 to 75 microns. The fibrils on / and along the fibrous structures of acrylic and para-aramid can come into contact and form a partial cocoon around the para-aramid particles, rounded, substantially free of fibril. The acrylic and para-aramid pulp is substantially free of aggregates or conglomerates of the same material. In addition, the pulp has a Canadian Standard Drainage Speed (CSF) as measured by the TAPPI T 227 om-92 test, which is a measure of drainage characteristics of 100 at 700 mi, and preferably 250 to 450 mi. The surface area of the pulp is a measure of the degree of fibrillation and the influences of the porosity of the product made with the pulp. Preferably, the surface area of the pulp of this invention is 7 to 11 square meters per gram. Figure 4 is an image of a photomicrograph of acrylic and para-aramid pulp made in accordance with the process of the present invention. It is considered that the aramid particles and the fibrous structures, dispersed substantially homogeneously throughout the reinforcing material, and by the friction and sealing materials, provide, by virtue of the high temperature characteristics of the para-aramid polymers and from the fibrillation propensity of para-aramid fibers, many reinforcing sites and increased wear resistance. When it is co-refined, the mixture of acrylic and para-aramid materials is so narrow that in a friction or sealing material there is always some para-aramid fibrous structures near the acrylic structures, so the efforts and Service abrasion are always shared. Sealing Material The invention is further directed to a sealing material and to the processes for manufacturing the sealing materials. Sealing materials are used in, or as a barrier to prevent the discharge of fluids and / or gases and are used to prevent the entry of contaminants where two objects are joined together. An illustrative use for sealing materials is in sealing packages. The sealing material comprises a binder; optionally at least one filler, and a fibrous reinforcing material comprising the acrylic and para-aramid pulp of this invention. Suitable binders include nitrile rubber, butadiene rubber, neoprene, styrene-butadiene rubber, nitrile-butadiene rubber, and mixtures thereof. The binder can be added with all the other starting materials. The binder is typically added in the first step of the sealing package production process, in which the dry ingredients are mixed together. The other ingredients optionally include uncured rubber particles and a rubber solvent, or a solution of rubber in solvent, to cause the binder to coat the surfaces of the fillers and the pulp. Suitable fillers include barium sulfate, clays, talc, and mixtures thereof. The appropriate processes for manufacturing sealing materials are, for example, a process of aggregation-beating or a wet process in which the sealing packaging is manufactured with a thick suspension of materials, or by what is called a calendering or dry process. wherein the ingredients are combined in an elastomeric or rubber solution. Friction Material The pulp of the present invention can be used as a reinforcement material in friction materials. By "friction materials" it refers to materials used for their friction characteristics such as a coefficient of friction to stop or transfer movement energy, stability at high temperatures, wear resistance, noise and vibration damping properties, etc. Illustrative uses for friction materials include brake pads, brake blocks, dry clutches working contact layers, clutch contact layer segments, brake pad insulation / support linings, automatic transmission papers, and friction papers. In view of this new use, the invention also additionally addresses the friction material and the processes for manufacturing the friction material. Specifically, the friction material comprises a friction modifier; optionally at least one filler; a binder, and a fibrous reinforcing material comprising the acrylic and para-aramid pulp of this invention. Suitable friction modifiers are metal powders such as iron, copper and zinc-abrasives such as magnesium and aluminum oxides; lubricants, such as synthetic and natural graphites, and sulphides of molybdenum and zirconium; and organic friction modifiers such as synthetic rubbers and cashew nut shell resin particles. Suitable binders are thermosetting resins such as phenolic resins (in this case, pure phenolic resins (100%) and various phenolic resins modified with rubber or epoxy), melamine resins, epoxy resins and polyamide resins, and mixtures of the same. Suitable fillers include barite, calcium carbonate, wollastonite, talc, various clays, and mixtures thereof. The actual steps for manufacturing the friction material may vary, depending on the type of friction material desired. For example, methods for manufacturing molded friction parts generally involve combining the desired ingredients in a mold, curing the part, and shaping, heat treating and grinding the part if desired. The automotive and friction transmission papers can generally be made by combining the desired ingredients in a slurry and making a paper in a paper machine with the use of conventional papermaking processes. TEST METHODS The following test methods were used in the following Examples. Canadian Standard Drainage Speed (CSF) is a fairly well-known measure of the ease with which water is drained from a slurry or dispersion of particles. Purity is determined by the TAPPI T227 test. The data obtained in the development of the test are expressed with Canadian Drain Speed Numbers., which represent the millimeters of water that were drained from a watery slurry under specified conditions. A large number indicates a high draining speed and a high tendency for the water to be drained. A low number indicates a tendency for the dispersion to be drained slowly. Drain-speed is inversely related to the degree of fibrillation of the pulp, since large numbers of the fibrils reduce the rate at which water is drained through a paper-forming mat. The average calculated length is measured with the use of a "FiberExpert" plaform analyzer (also known as "PulpExpertFS", available from Metso Automation of Helsinki, Finland). This analyzer takes photographic images of the pulp with a digital CCD camera as the thick slurry of pulp flows through the analyzer and then an integrated computer analyzes the fibers in these images and calculates their average-calculated lengths. Temperature: All temperatures are measured in degrees Celsius (2 C). The denier is measured in accordance with the ASTM D standard 1577 and is the linear density of a fiber that expresses the weight in grams of 9000 meters of fiber. The denier is measured on a Textechno vibroscope from Munich, Germany. A number dernier times (10/9) is equal to a decitex (dtex). EXAMPLES This invention will now be illustrated by the following specific examples. All parts and percentages are by weight unless otherwise indicated. The examples prepared in accordance with the process or processes of the present invention are indicated by numerical values.

Example 1 In this example of the invention, the pulp of this invention was produced from a raw material of para-aramid fiber and short acrylic fibers. The short acrylic fiber that has a cut length of 2 inches and has a linear filament density of 3 dpf (3.3 dtex per filament) was obtained from Solutia, Inc., with offices in San Louis, Mo. Para-amide fiber in the commercially available KEVLAR® brand flocculation form, Style 1F178, which has a cut length of 0.635 cm (1/4") cut length, was obtained from EI of Pont de Nemours and Company with offices in Wilmington, Delaware The short fiber and water together were supplied directly into a 12.4"Sprout-Waldron Single Disk Refiner with the use of setting a 0.254 mm plate space (10 mils). inch) and a pre-pulp to obtain an acceptable processing length in the range of 13 mm. The acrylic fiber in pre-pulp and the para-aramid fiber cut plus water were then combined into a highly agitated mixing tank at a solids concentration of 50% by weight of para-aramid fiber and 50% by weight of short acrylic fiber and were mixed to form a uniform slurry that can be pumped approximately 2-3% by weight of the total concentration of ingredients. The slurry was then recirculated and co-refined by means of a 12.4"Sprout-Waldron single disc refiner.The refiner simultaneously: (1) fibrillated, cut, and chewed the para-aramid fiber and also Acrylic short fiber to irregularly shaped fibrous structures having stems and fibrils (2) dispersed all solids so that the refined slurry was substantially uniform, substantially uniform as previously defined. It was filtered with the use of a filter bag and drained by means of pressure and placed in long storage bags type ZIPLOC® The fibrous structures had a maximum dimension no greater than 5 mm and a length-calculated no greater than 1.3 mm, as measured by the FiberExpert® Example 2 This example illustrates another method by which a co-refined pulp can be manufactured each from a raw material of para-aramid fiber and acrylic fiber. Acrylic short fiber, which has a cutting length of 5. 08 cm (2 inches) and having a linear filament density of 3 dpf (3.3 dtex per filament) available from Solutia, Inc., was cut with a guillotine cutter two or three times at a right angle for the purpose of producing a random-length fiber with most fibers shorter than 1.91 cm (3/4 inch) and having an approximate average length of 1.27 cm (1/2 inch). Para-aramid fiber in the form of commercially available multi-filament yarn KEVLAR®, available from E.I. from Pont de Nemours and Company in windings, was prepared by cutting the para-aramid yarn up to a nominal cut-off length of 1.27 cm (1/2 inch) in a Lummus Cutter (available from Lummus Industries with offices in Columbus, Georgia) . Another Kevlar® para-aramid fiber, which was not initially found in windings and was of multiple large lengths, was cut with a guillotine cutter two or three times at right angles for the purpose of producing a random-length fiber with most fibers shorter than 1.91 cm (3/4 inch) and having an average length of 1.27 cm (1/2 inch). The two ingredients prepared as described above plus water were then combined in a high-agitation mixing tank called a hydropulparator at a solids concentration of 50% by weight of para-aramid fiber and 50% by weight of acrylic fiber. and they were mixed to form a substantially uniform thick suspension with the pumpability which has a total solids concentration of approximately 2-3% by weight of the total ingredients. The slurry is pumped through a series of three refiners, according to what is described in the N American Patent 4,472,241. the refiners simultaneously: (1) fibrillated, cut, chewed the acrylic fiber and the para-aramid fiber into irregularly shaped fibrous structures that have stems and fibrils; and (2) dispersed all the solids so that the refined slurry was substantially uniform with substantially uniform as previously defined. The refined slurry was then drained with the use of a horizontal filter and dried in an oven to a desired moisture content of 50% total weight for the wet pulp. The wet pulp was then packaged in bales using a bale-forming packer. When measured with a FiberExpert®, the total ingredients in the pulp had an average calculated length no greater than 1.3 mm. Example 3 This example illustrates additional process steps and another embodiment of the pulp of this invention. The procedure of Example 2 was followed. However, after the pulp was drained in a horizontal filter, the pulp was pressed in a mechanical press to extract even more water; and the pulp is then mulled with the use of a mulching apparatus (available from Bepex Corporation with offices in Santa Rosa, California) to better separate the pressed wet pulp. The fluffy wet pulp is then dried in an oven to approximately 8% by total moisture weight and then further processed in an ultrarot (model IIIA available from Altenburger Machinen Jackering GmbH with offices in Voisterhauser, Germany) as described in US Patent 5,084,136 to fluff and further disperse the dried pulp. The dried pulp is then packed in bales. When measured with FiberExpert®, the total ingredients in the pulp had an average calculated length of no more than 1.3 mm. Example 4 This example illustrates another embodiment of the pulp of this invention. The process of Example 2 was conducted with the exception that one third by weight of the para-aramid fiber is replaced by para-aramid particles. The para-aramid resin particles are prepared by continuously reacting para-phenylenediamine and teraphthaloyl chloride in a screw extruder as generally described in US Patent 3,884,881, but with the use of N, methyl pyrrolidone / calcium chloride as the solvent, producing a like-like polymer that precipitates from the solvent. The solvent is removed, and the polymer lump is washed and dried to a particulate powder with a mixed particle size. The para-aramid resin particles are then treated in substantially the same way as the para-aramid fiber was treated in Example 2. However, the refiner not only refines the fibers but also cuts and / or chews the particles of para-aramid to form rounded, substantially fibril-free particles. After draining, some of the resulting pulp has a moisture content of 50 percent total weight then it is packaged in bales. The rest of the resulting pulp is further pressed to a moisture content of about 8 weight percent total and then fluffed, and packaged as in Example 3. When measured with the FiberExpert®, the total of the ingredients in the pulp had an average calculated length no greater than 1.3 mm. Example 5 The brake disc pads that incorporate the pulp of this invention were manufactured in the following manner. Approximately 20 kilograms of a non-asbestos-containing powder base compound comprising a mixture of 7% by weight of cashew nut shell resin, 17% by weight of inorganic fillers, 21% by weight graphite, coke and lubricants, 18% by weight of inorganic abrasives, and 16% by weight of soft metals, for 10 to 20 minutes in a 50-liter Littleford mixer. The mixer had two high-speed cutters with blades of the "stars and bars" configuration and a low-rotation rake. The 5 kilograms of the well-mixed powder base compound were then combined with the pulp of this invention (a co-refined pulp which is 50% by weight of para-aramid and 50% by weight of acrylic fiber) in an amount of 3.8% by weight, based on the combined weight of the powder and pulp compound. The pulp was then dispersed in the powdered base compound by mixing for an additional 5 to 10 minutes. Once blended, the composition of the resulting brake pad exhibited a normal visual appearance with the fiber well dispersed in, and completely coated with the powder base compound, without essentially detectable pulp binding or segregation of any of the constituents. The brake pad composition was then poured into a single-cavity steel mold for a front disc brake pad and cold pressed to an approximate standard thickness of 16 mm (5/8 inch) after it was Removal from the mold to form a pre-formed brake pad that has an approximate weight of 200 grams. The pre-formed did not present an excessive reverse effect or swelling, and was found robust enough for normal handling without damage. Twelve pre-formed replicas were manufactured. The pre-formed ones were then placed in two multi-cavity molds, placed in a commercial press, and cured under pressure (cross-linking and reaction of the phenolic binder) at 149 ° C (300 aF) for approximately 15 minutes, with a periodic release of pressure to allow the phenolic reaction gases to escape, followed by a light curing under bake at 1712C (340SF) for 4 hours until complete crosslinking of the phenolic binder. Subsequently, the molded and cured tablet was machined to a desired thickness of approximately 13 mm (one-half inch). When visually compared with a commercial brake pad containing an equivalent amount of total para-aramid pulp or acrylic pulp, the test tablet could not be distinguished and presented a good flow of the compound into the plate holes of the plate. support and did not have chipped edges. Subsequently, a sample of the brake pad incorporating the pulp of this invention was evaluated to determine its frictional performance. The specimens, typically 2.54 cm by 2.54 cm (one inch by one inch) and approximately 5 mm (3/16 of an inch) thick, obtained from the test pads were rated on the Chase Machine available from Link Engineering, Detroit, MI, with the use of the test protocol of the J661 standard of the Society of Automotive Engineers (SAE, for its acronym in English) to determine the coefficient of friction in hot and cold during tests of resistance of constant pressure and controlled temperature against a heated steel drum. The sample was measured periodically in terms of wear (loss of thickness). This was repeated with two more test samples of other pellet replicas. The brake pad samples incorporating the pulp of this invention exhibited a hot and cold friction performance substantially equivalent to that of commercially available pellets containing an amount substantially equivalent to the total para-aramid pulp. The test further indicated that the tablet-to-tablet uniformity and that the average friction ratio was also substantially equivalent. The pickup was then tested for friction and wear under various braking conditions with the use of a dynamometer (single-piston dynamometer with a rolling radius of 289.0 mm at Link Testing Laboratories, Inc., in Detroit, MI) with the use of the J2681 test protocol (ISO-SWG4). This test comprised seventeen application scenarios of 5 to 200 braking each, and the coefficient of friction was measured as a function of the applied braking pressure, temperature, speed speed and braking deceleration. This test also had two sections of high-temperature deterioration, during which the brake pad was subjected to high initial temperatures incrementally during a constant deceleration, and the temperatures reached exceeded 600 BC. Wear was measured in terms of reducing the thickness and weight of the pellet at the end of the test (608 braking applications). The results for the pellets made with the compound of this example showed very little deterioration and what was deteriorated was well coated (where "deteriorated" is defined as the friction loss during the higher temperature braking applications), an acceptable coefficient of friction of 0.25 to 0.4 in the non-deteriorated sections, an absence of fractured pellet surface, and acceptable wear ratios for both the pellet and the rotor. EXAMPLE 6 This example illustrates how the pulp of this invention can be incorporated into an aggregate-in-shake sealing package for sealing applications. Water, rubber, latex, fillers, chemicals, and the pulp of this invention are combined in desired amounts to form a slurry. The slurry is sufficiently drained in terms of its water content on a circulation wire screen (such as a grill or paper machine wire), is dried in a heating tunnel, and is vulcanized on hot calendering rolls to form a material that has a maximum thickness of around 2.0 mm. This material is compressed in a hydraulic press or in a two-roll calendering machine, which increases the density and improves the sealing capacity. Such aggregate-in-batter sealing packaging materials generally do not have a good seal capacity as the equivalent fiber-compressed materials and are more suitable for moderate-high-temperature pressure applications. Seal-by-aggregate-in-shake gaskets can be applied in the manufacture of auxiliary engine seal packs or, in cylinder head seals, after further processing. For this purpose, the semi-finished product is laminated on both sides of a metal sheet with bolts and is physically fixed in place with the bolts. EXAMPLE 7 This example illustrates how the pulp of this invention can be incorporated from an elaborate sealing gasket by a calendering process. The same ingredients as in Example 6, minus water, are mixed together completely dry and then mixed with a rubber solution prepared with the use of an appropriate solvent. After mixing, the compound is then generally transported in batches to a roller calendering mauine. The calendering machine consists of a small roller that is cold and a large roller that is heated. The compound is fed and carried within the roller contact line of the calendering machine by the rotary movement of the two rollers. The composite adheres and it wraps around the hot bottom roll in layers generally about 0.02 mm thick, depending on the pressure, to form a sealing packing material made with the composite layers made. By doing so, the evaporation of the solvent and the vulcanization of the elastomer begins. Once the desired thickness of the sealing packing material is obtained, the rollers are stopped and the sealing packing material is cut from the roll and cut and / or punched to a desired size. No additional pressing or heating is required, and the material is ready to function as a sealing gasket. In this way, sealing packages up to approximately 7 mm thick can be manufactured. However, most sealing gaskets manufactured in this way are much thinner, typically about 3 mm or less thick. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims

CLAIMS Having described the invention as above, the content of the following claims is claimed as property. A process for manufacturing an acrylic and para-aramid pulp for use as a reinforcing material, characterized in that it comprises: (a) combining pulp ingredients including: (1) acrylic fiber comprising acrylonitrile units which are at least 85% by weight of the total acrylic fiber, the fiber is 10 to 90% by weight of the total solids in the ingredients, and has an average length of no more than 10 cm; (2) para-aramid fiber which is from 10 to 90% by weight of the total solids in the ingredients, and which has an average length of not more than 10 cm; and (3) water that is 95 to 99% by weight of the total ingredients; (b) mixing the ingredients to form a substantially uniform slurry; (c) co-refine the slurry by simultaneo performing: (1) fibrillating, cutting and chewing the acrylic fiber and the para-amide fiber to obtain fibrillated fibrillated structures irregularly formed with stems and fibrils; and (2) dispersing all solids so that the refined slurry is substantially uniform; and (d) extracting water from the refined slurry to not more than 60% by total weight of water, thereby producing an acrylic and para-amide pulp with fibrous acryl and para-amide structures having one dimension maximum average not greater than 5 mm, an average calculated length no greater than 1.3 mm, and the fibrils and / or acrylic stems are substantially entangled with the fibrils and / or para-amide stems. 2. The process according to claim 1, characterized in that the acrylic fiber has a linear density not greater than 10 dtex; and the para-aramid fiber has a linear density of no more than 2.5 dtex. 3. The process according to claim 1, characterized in that the pulp is without substantial aggregates of the same material. 4. The process according to claim 1, characterized in that the ingredients further comprise aramid particles, granular, substantially or completely fibril-free, which are not more than 50% by weight of the total solids in the ingredients, and having a maximum average dimension of 50 to 2000 microns, and in the step of refining, chewing at least some of the para-aramid particles into smaller, rounded, substantially fibril-free particles, whereby in the pulp produced from acrylic and para-aramid, the fibrous structures of acrylic and para-aramid come into contact and are wrapped partially around at least some of the para-aramid particles, rounded, substantially free of fibril. 5. The process according to claim 1, characterized in that in the step of combining, the acrylic fiber comprises from 25 to 60% by weight of the total solids. 6. The process according to claim 1, characterized in that in the combining step, the para-aramid fiber comprises from 40 to 75% by weight of the total solids. The process according to claim 1, characterized in that after the extraction step, the water is 4 to 60% by weight of the whole pulp, and the pulp has a Canadian Standard Drainage Speed. (CSF) from 100 to 700 mi. The process according to claim 1, characterized in that the step of refining comprises passing the mixed slurry through a series of disk refiners. 9. A process for manufacturing an acrylic and para-aramid pulp for use as a reinforcing material, characterized in that it comprises: (a) combining ingredients that include water and a first fiber of the group consisting of: (1) acrylic fiber comprising acrylonitrile units which are at least 85% by weight of the total acrylic fiber, the fiber is from 10 to 90% by weight of the total solids in the pulp; and (2) para-amide fiber which is from 10 to 90% by weight of the total solids in the pulp; (b) mixing the combined ingredients to form a substantially uniform suspension; (c) refining the suspension in a disk refiner thereby cutting the fiber to have an average length of no more than 10 cm, and fibrillating and chewing at least some of the fiber up to fibrillated fibrillated structures formed irregularly; (d) combine ingredients that include the refined suspension, the second fiber of the group of (a) (1 and 2) that has an average length of no more than 10 cm, and water, if necessary, increase the water concentration to 95 -99% by weight of the total ingredients; (e) mixing the ingredients, if necessary, to form a substantially uniform suspension; (f) co-refining the mixed slurry at the same time: (1) fibrillating, cutting and chewing solids in the suspension so that all or substantially all of the acrylic and para-amide fibers are converted into fibrous structures of acrylic and paraffin. fibrillated amides formed irregularly with stems and fibrils; and (2) dispersing all solids whereby the refined slurry suspension is substantially uniform; and (h) extracting water from the refined slurry to no more than 60% by total weight of water, thereby producing an acrylic and para-amide pulp with fibrous acrylic and para-amide structures having one dimension maximum average no greater than 5 mm, an average calculated length no greater than 1.3 mm, and the fibrils and / or acrylic stems are substantially entangled with the fibrils and / or para-amide stems. The process according to claim 9, characterized in that the ingredients further comprise: para-aramid particles, granulated, substantially or completely fibril-free, which are not more than 50% by weight of the total solids in the ingredients , and that have a maximum average length of 50 to 2000 microns; and either in the first or in the second refining step, chew at least some of the para-aramid particles into smaller, rounded, substantially fibril-free particles, whereby in the pulp produced from acrylic and para-aramid, fibrous structures of acrylic and para-aramid come into contact and are partially wrapped around at least some of the aramid particles, rounded, substantially free of fibril. 11. The process according to claim 9, characterized in that after the step of extracting, fibrous structures of acrylic irregularly formed are from 25 to 60% of the total solids. 12. The process according to claim 9, characterized in that after the extraction step, the irregularly formed fibrous, para-aramid structures are from 40 to 75% by weight of the total solids. 13. The process according to claim 9, characterized in that after the extraction step, the water is from 4 to 60% by weight of the whole pulp, and the pulp has a Canadian Standard Drainage Speed (CSF) of 100 to 700 mi. 14. An acrylic and para-amide pulp for use as a reinforcing material, characterized in that it comprises: (a) irregularly formed acrylic fibrous structures comprising acrylonitrile units which are at least 85% by weight of the total structures fibrous acrylic, the structures are from 10 to 90% by weight of the total solids; (b) irregularly formed para-aramid fibrous structures that are from 10 to 90% by weight of the total solids; and (c) water which is from 4 to 60% by weight of the whole pulp, whereby the fibrous structures of acrylic and those of para-aramid have an average maximum dimension not greater than 5 mm, a length-calculated average no greater than

1. 3 mm, and stems and fibrils where the fibrils and / or acrylic stems are substantially entangled with the fibrils and / or para-aramid stems. 15. The para-aramid pulp according to claim 14, characterized in that it also comprises para-aramid particles, granulated, substantially or completely fibril-free, which are not more than 50% by weight of the total solids. The pulp according to claim 14, characterized in that the fibrous structures of acrylic, formed irregularly are from 25 to 60% by weight of the total solids. 17. The pulp according to claim 14, characterized in that the fibrous structures of para-aramid formed irregularly are from 40 to 75% by weight of the total solids. The pulp according to claim 14, characterized in that the water is from 4 to 60% by weight of the whole pulp, and the pulp has a Canadian Standard Decay Rate (CSF) of 100 to 700 ml. 19. A friction material, characterized in that it comprises: a friction modifier; a binder; and a fibrous reinforcing material comprising the pulp according to claim 14. 20. The friction material according to claim 19, characterized in that the friction modifier is selected from the group consisting of metal powders, abrasives, lubricants, organic friction modifiers, and mixtures thereof; and the binder is selected from the group consisting of thermosetting resins, melamine resins, epoxy resins and polyamide resins, and mixtures thereof. 21. A sealing material, characterized in that it comprises: a binder, and a fibrous reinforcing material comprising the pulp according to claim 14. 2

2. The sealing material according to claim 21, characterized in that the binder is selected of the group consisting of nitrile rubber, butadiene rubber, neoprene, butadiene styrene rubber, nitrile-butadiene rubber, and mixtures thereof.