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Acrylic and para-aramid pulp and processes of making sameRelated Patent Categories: Stock Material Or Miscellaneous Articles, Web Or Sheet Containing Structurally Defined Element Or Component, Noninterengaged Fiber-containing Paper-free Web Or Sheet Which Is Not Of Specified PorosityAcrylic and para-aramid pulp and processes of making same description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20050287344, Acrylic and para-aramid pulp and processes of making same. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] This invention relates to acrylic and para-aramid pulp for use as reinforcement material in products, such as seals and friction materials. The invention further relates to processes for making such pulp. [0003] 2. Description of Related Art [0004] Fibrous and non fibrous reinforcement materials have been used for many years in friction products, sealing products and other plastic or rubber products. Such reinforcement materials typically must exhibit high wear and heat resistance. [0005] Asbestos fibers have historically been used as reinforcement materials, but due to their health risks, replacements have been made or proposed. However, many of these replacements do not perform as well as asbestos in one way or another. [0006] Research Disclosure 74-75, published February 1980, discloses the manufacture of pulp made from fibrillated KEVLAR.RTM. brand para-aramid fibers of variable lengths and use of such pulp as a reinforcement material in various applications. This publication discloses that pulp made from KEVLAR.RTM. brand para-aramid fibers can be used in sheet products alone, or in combination with fibers of other materials, such as NOMEX.RTM. brand meta-aramid, wood pulp, cotton and other natural cellulosics, rayon, polyester, polyolefin, nylon, polytetrafluoroethylene- , asbestos and other minerals, fiberglass and other, ceramics, steel and other metals, and carbon. The publication also discloses the use of pulp from KEVLAR.RTM. brand para-aramid fiber alone, or with KEVLAR.RTM. brand para-aramid short staple, in friction materials to replace a fraction of the asbestos volume, with the remainder of the asbestos volume being replaced by fillers or other fibers. [0007] U.S. Pat. No. 5,811,042 (to Hoiness) discloses a composite friction or gasketing material made of a thermoset or thermoplastic matrix resin, fiber reinforcing material, and substantially fibril free aramid particles. Poly (p-phenylene terephthalamide) and poly(m-phenylene isophthalamide) are preferred fiber reinforcing materials, and the fibers can be in the form of floc or pulp. [0008] U.S. Patent Application 2003/0022961 (to Kusaka et al.) discloses friction materials made from a friction modifier, a binder and a fibrous reinforcement made of a mixture of (a) a dry aramid pulp and (b) wet aramid pulp, wood pulp or acrylic pulp. Dry aramid pulp is defined as an aramid pulp obtained by "the dry fibrillation method". The dry fibrillation method is dry milling the aramid fibers between a rotary cutter and a screen to prepare the pulp. Wet aramid pulp is defined as an aramid pulp obtained by "the wet fibrillation method". The wet fibrillation method is milling short aramid fibers in water between two rotary discs to form fibrillated fibers and then dehydrating the fibrillated fibers, i.e., the pulp. Kusaka et al further disclose a method of mix-fibrillating fibers by first mixing plural types of organic fibers that fibrillate at a definite ratio, and then fibrillating the mixture to produce a pulp. [0009] There is an ongoing need to provide alternative reinforcing materials that both perform well in products, such as seals and friction applications, and that are low in cost. Despite the numerous disclosures proposing lower cost alternative reinforcement materials, many of these proposed products do not adequately perform in use, cost significantly more than currently commercial products, or have other negative attributes. As such, there remains a need for reinforcement materials that exhibit high wear and heat resistance, and that are comparable or less expensive than other commercially available reinforcement materials. BRIEF SUMMARY OF THE INVENTION [0010] The invention relates to a first embodiment of a process for making an acrylic and para-aramid pulp for use as reinforcement material, comprising: [0011] (a) combining pulp ingredients including: [0012] (1) acrylic fiber comprising acrylonitrile units which are at least 85 wt % of the total acrylic fiber, the fiber being 10 to 90 wt % of the total solids in the ingredients, and having an average length of no more than 10 cm; [0013] (2) para-aramid fiber being 10 to 90 wt % of the total solids in the ingredients, and having an average length of no more than 10 cm; and [0014] (3) water being 95 to 99 wt % of the total ingredients; [0015] (b) mixing the ingredients to a substantially uniform slurry; [0016] (c) co-refining the slurry by simultaneously: [0017] (1) fibrillating, cutting and masticating the acrylic fiber and the para-aramid fiber to irregularly shaped fibrillated fibrous structures with stalks and fibrils; and [0018] (2) substantially uniformly dispersing all solids in the refined slurry; and [0019] (d) removing water from the refined slurry to no more than 60 total wt % water, [0020] thereby producing an acrylic and para-aramid pulp with the acrylic and the para-aramid fibrous structures having an average maximum dimension of no more than 5 mm, a length-weighted average of no more than 1.3 mm, and the acrylic fibrils and/or stalks are substantially entangled with the para-aramid fibrils and/or stalks. [0021] The invention is further related to a second embodiment of a process for making an acrylic and para-aramid pulp for use as reinforcement material, comprising: [0022] (a) combining ingredients including water and a first fiber from the group consisting of: Continue reading about Acrylic and para-aramid pulp and processes of making same... Full patent description for Acrylic and para-aramid pulp and processes of making same Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Acrylic and para-aramid pulp and processes of making same patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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