EP1255638A2 - Plastiques renforces et leur fabrication - Google Patents

Plastiques renforces et leur fabrication

Info

Publication number
EP1255638A2
EP1255638A2 EP01910592A EP01910592A EP1255638A2 EP 1255638 A2 EP1255638 A2 EP 1255638A2 EP 01910592 A EP01910592 A EP 01910592A EP 01910592 A EP01910592 A EP 01910592A EP 1255638 A2 EP1255638 A2 EP 1255638A2
Authority
EP
European Patent Office
Prior art keywords
reinforcing fiber
cellulosic
molded
additionally
composite
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP01910592A
Other languages
German (de)
English (en)
Inventor
Tommy K. Thrash
Richard W. Tock
Daniel W. A'hern
Lyle V. Cox
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Impact Composite Tech Ltd
Original Assignee
Impact Composite Tech Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Impact Composite Tech Ltd filed Critical Impact Composite Tech Ltd
Publication of EP1255638A2 publication Critical patent/EP1255638A2/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M15/00—Arrangements for metering, time-control or time indication ; Metering, charging or billing arrangements for voice wireline or wireless communications, e.g. VoIP
    • H04M15/83—Notification aspects
    • H04M15/85—Notification aspects characterised by the type of condition triggering a notification
    • H04M15/854—Available credit
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
    • B29C70/06—Fibrous reinforcements only
    • B29C70/10—Fibrous reinforcements only characterised by the structure of fibrous reinforcements, e.g. hollow fibres
    • B29C70/12—Fibrous reinforcements only characterised by the structure of fibrous reinforcements, e.g. hollow fibres using fibres of short length, e.g. in the form of a mat
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M17/00—Prepayment of wireline communication systems, wireless communication systems or telephone systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M17/00—Prepayment of wireline communication systems, wireless communication systems or telephone systems
    • H04M17/10—Account details or usage
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M17/00—Prepayment of wireline communication systems, wireless communication systems or telephone systems
    • H04M17/20—Prepayment of wireline communication systems, wireless communication systems or telephone systems with provision for recharging the prepaid account or card, or for credit establishment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2311/00—Use of natural products or their composites, not provided for in groups B29K2201/00 - B29K2309/00, as reinforcement
    • B29K2311/10—Natural fibres, e.g. wool or cotton
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M2215/00—Metering arrangements; Time controlling arrangements; Time indicating arrangements
    • H04M2215/81—Notifying aspects, e.g. notifications or displays to the user
    • H04M2215/815—Notification when a specific condition, service or event is met
    • H04M2215/8166—Available credit

Definitions

  • the present invention relates to apparatus and methods, and the resulting product, for manufacturing reinforced plastics. More particularly, the present invention relates to the use of cellulosic reinforcing fiber for modifying composite plastics.
  • thermoplastic polypropylene, polyethylene, polystyrene, ABS, nylon, polycarbonate, thermoplastic polyester, polyphenylene oxide, polysulfone, and PEEK, for example
  • thermoset unsaturated polyester, vinyl ester, epoxy, urethane, and phenolic, for example
  • So-called "spray-up" in one-sided molds is a common fabrication process for making fiberglass composite products.
  • Typical fiberglass products made by this method include boat hulls and decks, components for trucks, automobiles, recreational vehicles, spas, tubs, showers, and septic tanks.
  • the mold is waxed and sprayed with gel coat and, after the gel coat cures, catalyzed thermoset resin (usually polyester or vinyl resin) is sprayed into the mold.
  • a chopper gun chops roving fiberglass directly into the resin spray so that both materials are simultaneously applied to the mold and the spray-up may then be rolled out to compact the laminate.
  • Wood, foam, or other core material may then be added and a secondary spray-up layer is applied to imbed the core between the laminates. The part is then cured, cooled and removed from the reusable mold.
  • thermoplastic resin use is growing dramatically. Automated injection molding of thermoplastic composites has allowed the use of such composites in many applications previously held by metal casting manufacturers. Typical products include electrical and automotive components, appliance housings, and plastic lumber. Thermoplastic composites are compounded by melt blending the resin with additives and reinforcements and the resin, additive(s), and reinforcement(s) are fed through an extruder where they are combined, exiting the extruder in a strand that is cooled and cut into pellets for subsequent injection molding.
  • thermoplastic and thermoset plastic composites that are modified with cellulosic materials, such as from plant byproducts, with improved physical characteristics compared to currently available reinforced plastics.
  • the present invention is directed to methods of manufacturing reinforced thermoplastic and thermoset plastics and the apparatus for manufacturing such plastics.
  • the present invention is directed to a cellulosic material for use as a modifier for thermoplastic and thermoset plastics.
  • the present invention is directed to methods for manufacturing composite articles from such plastics and the resulting products of such methods.
  • the present invention provides a molded, composite plastic article comprising a polymeric resin and a cellulosic reinforcing fiber, the cellulosic reinforcing fiber a cellulosic material having a lignin content between about 20 and about 50 weight per cent and an inorganic content between about 5 and about 15 per cent by weight.
  • the present invention provides an improved method of molding plastic articles from both thermoplastic and thermoset resins that reduces emissions of volatile organic carbons wherein the improvement comprises applying a coating of a cellulosic reinforcing fiber to the molded plastic article before curing the polymeric resin comprising the molded plastic article.
  • the present invention provides a composite reinforced panel comprising a styrene resin and a cellulosic reinforcing fiber in a ratio of from about one part styrene resin to about one quarter to about three parts cellulosic reinforcing fiber wherein the cellulosic reinforcing fiber comprises a cellulosic material having a lignin content between about 20 and about 50 weight per cent and ' an inorganic content between about 5 and about 15 per cent by weight.
  • the present invention comprises a process for making a composite reinforced panel comprising mixing a styrene resin and a cellulosic reinforcing fiber in a ratio of from about one part styrene resin to about one quarter to about three parts cellulosic reinforcing fiber wherein the cellulosic reinforcing fiber comprises a cellulosic material having a lignin content between about 20 and about 50 weight per cent and an inorganic content between about 5 and about 15 per cent by weight, introducing the mixture of styrene resin and cellulosic reinforcing fiber into a mold, curing the mixture in the mold at elevated temperature, removing the cured mixture from the mold, and cutting the cured mixture to the desired size to form a reinforced panel.
  • the present invention provides an apparatus for molding an expanded thermoplastic polymer comprising an oven, a rack sized to fit the oven, at least two molds sized to fit into the rack, and a plurality of beams, at least one of the beams being located between the molds and at least one of the beams being located between one of the molds and the rack for transferring force caused by expansion of the thermoplastic polymer in the oven from the molds to the rack.
  • the present invention provides a method of producing a filled plastics article involving the use as a reinforcing fiber of scrap material produced as a by-product of the processing of an agricultural product and comprising by weight between about 20 and about 50 per cent by weight, treated to reduce the material to particulate form and which has an ash content in the range of 5 to 15 per cent by weight and a lignin content in the range 20 to 50 per cent by weight.
  • Figure 1 is a schematic diagram of a preferred method of preparing a cellulosic material for use as a modifier for thermoplastic and thermoset plastics.
  • Figure 2 is a schematic diagram of a preferred method of molding a thermoplastic composite article in accordance with the present invention.
  • Figure 3 is a detail drawing of the molds for molding a thermoplastic composite board in accordance with the method of Fig. 2.
  • Figures 4 A, 4B, and 4C are top, end and side views, respectively, of a rack for holding the molds of Fig. 3 for use in a method of producing a composite thermoplastic board in accordance with the method of Fig. 2.
  • Figures 5A, 5B, and 5C are top, end, and side views, respectively, of a preferred embodiment of an oven for use in producing a composite thermoplastic board in accordance with the method of Fig. 2.
  • Figure 6 is a side elevational view of a production line for producing a scored sheet for use in, for instance, spray-up molding using the composite thermoplastic board produced in accordance with the method of Fig. 2.
  • cotton burrs As a filler for such plastics.
  • the cotton burr is the woody or fibrous portion of the cotton boll that is neither lint nor seed, but does not include the bract, leaves, or stems as more fully described in U.S. Patent No. 4,670,944, that comprises a portion of what is commonly referred to as cotton gin by-product waste.
  • the use of cotton burrs as a filler or modifier for such plastics is described in U.S. Patent No. 4,818,604, and both that patent and the aforementioned Patent No.
  • Patent No. 4,670,944 is hereby incorporated herein in their entireties by these specific references to those patents.
  • Patent No. 4,670,944 describes a method of classifying lignocellulose materials for a variety of uses, including the use of the lignocellulose materials as a filler for plastics as described in Patent No. 4,818,604.
  • raw gin trash is cleaned of sand and fine leaf and bract particles in a spiral cut flight conveyor, pulverized in a hammer mill or equivalent, fed through a lint separator in the form of a tube formed of screen with a spike conveyor as the center shaft, the comminuted burrs, stems, and bracts falling through the screen and the lint remaining in the tube.
  • a lint separator in the form of a tube formed of screen with a spike conveyor as the center shaft, the comminuted burrs, stems, and bracts falling through the screen and the lint remaining in the tube.
  • the method described in Patent No. 4,670,944 is modified as follows. Referring to Fig. 1, the cotton burr is separated and readily available at a cotton gin where the incoming seed cotton from the field has been harvested or stripped from the stalk by a stripper as described in Patent No.
  • the burrs are preferably (but not required to be) compressed into ricks in the field (step 14) and are then loaded into a spiral cut flight conveyor for cleaning the sand and fine leaf and bract particles from the burrs, the latter as described in Patent No. 4,670,944, at step 16.
  • the burrs are then pulverized in a hammer mill or equivalent apparatus as described in that prior patent at step 18 to increase bulk density and conveyed to a series of lint beaters, also of the type described in Patent No. 4,670,944, where as much cotton lint as possible is removed at step 20.
  • the burrs are then moved by conveyor, truck and front end loader, or other means as known in the art to a hopper 22 which serves as the intake feed for a dryer 24, preferably a tower drier, for reducing the water content of the burrs to below about 15%, and preferably below 10%.
  • the tower drier also serves as a conveyor for moving the feedstock from the hopper 22 to a second series of lint beaters 26 for removing any remaining lint from the burrs.
  • the burrs fall through the screen of the lint beaters 26 onto a conveyor that feeds the burrs to one or more grinders 28 that grind the feedstock to a very fine material.
  • the ground feedstock is then augured to another series of lint beaters 30 that remove even more lint and then to a series of bower shakers 32 for screening the feedstock to remove more lint and any oversized feedstock (the latter being returned to grinders 28).
  • the remaining feedstock is then conveyed to a series of bower shakers/sifters 34 where the feedstock is screened to selected sizes, each sifter being provided with a conveyor for moving the sized reinforcing fiber to a separate holding bin 36.
  • the stored burrs 14 may be dessicated, and remain dessicated, by spreading a bed of dessicant on supporting structure and then covering the dessicant with a mesh and placing the burrs over the mesh.
  • Calcium chloride about two inches thick, is an acceptable bed.
  • a 16 mesh or smaller wire screen is a satisfactory boundary.
  • moisture does not penetrate very far into ricks of the stored cotton burrs such that it generally is not necessary to treat the stored burrs with fumed silica if the burrs are compressed into ricks.
  • Another example of a modification to the above-described process is when the process is modified for use with other cellulosic materials.
  • An example of such a material is the stalk, stems, and leaves of the cotton plant.
  • cotton is customarily harvested by stripping the cotton bolls from the plant. Stripping usually involves stripping the leaves, sticks, and limbs, as well as the bolls, and leaves the stalk standing in the field.
  • the lignin which is a by-product of making paper pulp from trees and is available commercially under such brand names as LIGNOCITE (Georgia Pacific); is absorbed onto the cellulose fiber so that the fiber more readily bonds with such polymers as polyesters, polystyrene, polyethylene, polyvinyl chloride, polypropylene, and other polymers.
  • the lignin also helps bond the cellulosic material to fiberglass and other polymeric constructs.
  • the lignin is preferably absorbed onto the cellulosic material at step 22 of the above-described method by mixing the cellulosic material with the liquid lignin in a mill or other suitable apparatus that serves as the inlet feed to the drier 24. It is preferred that enough lignin be added to the cellulosic material to bring the final lignin content of the reinforcing fiber to approximately 20 - 50 weight per cent of the reinforcing fiber, and preferably 30 - 45 weight per cent. Those skilled in the art will recognize from this disclosure that the amount of lignin that is added to the cellulosic material will vary depending upon the lignin content of the raw cellulosic material.
  • Acceptable performance of the reinforcing fiber can also be obtained, depending upon the end use of the reinforcing fiber, by absorbing one or more of the primary precursors of lignin, trans-coniferyl, trans-sinapyl, and/or trans-p-coumaryl alcohol, onto the cellulosic material. Any one or more of these precursors may also be used, in generally smaller proportions, in addition to commercially available lignin, to optimize desirable physical parameters of the final product molded with the cellulosic reinforcing fiber of the present invention.
  • the ash content of the reinforcing fiber of the present invention be in the range of from about 5 to about 15 weight per cent, and preferably, about 7 to about 13 weight per cent.
  • the silica into the cellulosic feedstock. For instance, analysis has shown that the ash content of the stalks of certain strains of cotton is so low (on the range of 2 - 3%) that silica must be added to the raw stalks to produce a satisfactory reinforcing fiber for making composite plastics.
  • a -325 sized or smaller silica sand and silica flour be absorbed onto the cellulosic material in mineral oil, tall oils, vegetable oils such as soy oil, cotton oil, or palm oil, and/or hydrocarbon and other petroleum products.
  • Water can also be used to introduce the silica into the fibers by, for instance, soaking the cellulosic material in a slurry of water and silica sand and/or flour for times ranging from about 15 minutes up to about 6 hours.
  • Another method for penetrating the interior fiber is to pull a vacuum in a container filled with the raw cellulosic material, introduce the liquid water- or oil-based silica into the container, and then open the container to the atmosphere to drive the silica into the interior of the fiber.
  • the addition of silica can be accomplished at step 22 of the above-described process and may or may not be accomplished simultaneously with the addition of lignin, if necessary.
  • the reinforcing fiber made by the method of the present invention is utilized for reinforcement of both thermoplastic and thermoset plastics.
  • the fiber is used as either the main body of the construct or to modify the structure and/or physical behavior of the resulting construct.
  • the addition of as little as 2 per cent of the reinforcing fiber (weight or volume) into some thermosetting resins will result in sufficient modification of the physical behavior of the resulting construct to adapt the construct for use in certain applications.
  • the amino resins of melamine and urea likewise display structural behavior, tailored to the cellulosic content of the fiber.
  • the reinforcing fiber is utilized as both a blowing agent for polyurethanes and for improving the strength of the resulting molded composite article.
  • the epoxy groups characterized by a three-membered ring structure, with the addition of compounds containing active hydrogen atoms such as amines, acids, phenols, and alcohols, that react by opening the ring to form a hydroxyl group also react with the lignin groups within the fiber.
  • a modification that is peculiar to the behavior of these epoxy families occurs with the addition of the fiber, stabilizing the exothermic reaction, to inhibit "critical mass” behavior normally exhibited beyond fifty gram weight mass.
  • thermoset resins may be utilized in many know manufacturing methods, including all forms of lay-up, spray-up laminated coatings, bulk castings, bulk molding compounds (BMC), sheet molding compounds (SMC), and other such method of molding and manufacturing as l ⁇ iown to those skilled in the art.
  • BMC bulk molding compounds
  • SMC sheet molding compounds
  • resins including the reinforcing fiber of the present invention are molded at temperatures ranging from ambient and up and at pressures above and below ambient, all as l ⁇ iown in the art.
  • the ground reinforcing fiber manufactured in accordance with the above-described method is mixed with an expandable thermoplastic polymer, a tackifier is added to produce a non-pre-blown mixture, and the mixture is heated in a mold to a temperature above the glass transition temperature of the polymer for a period of time sufficient to permit expansion of the polymer beads and bonding of the expanded beads with the reinforcing fiber to form a molded, composite article such as a composite board.
  • the molded, composite article is, for instance, a board or panel
  • the composite board may be laminated by a solvent-based adhesive or by thermal insult coating to form rigid macro-voids between the laminate and the composite board surface.
  • the molded composite may also be coated with a layer of the cellulosic reinforcing fiber of the present invention as described in more detail below.
  • an additional polymer may be applied to the coating of the cellulosic reinforcing fiber to produce a molded, laminated composite with greatly increased toughness characteristics.
  • the composite panel is used, for instance, to increase the bulk and/or thickness of an open molded article, it does so with minimal increase in weight and improves many of the desirable properties of the resulting molded article such as resistance to moisture, fungus, compressive force, tensile strength, and other physical parameters.
  • thermoplastic polymer such polystyrene, available commercially in bead form
  • a thermoplastic polymer such polystyrene, available commercially in bead form
  • a quantity of surface active agent comprising approximately 1% by weight of the total polystyrene bead content is added to this mixture at step 42 to promote uniform dispersion of the two components and to promote adhesive bonding between the reinforcing fiber and the polymer when molding.
  • the polymer, reinforcing fiber, and surface agent mixture is then introduced into a mold as at step 44 shaped to the size of the desired molded product and the mold heated at step 46 to a temperature in excess of the glass transition temperature of the polymer for sufficient time to expand the polymer to the shape of the mold.
  • the mold is then cooled as at step 48 to cure the expanded polystyrene.
  • a reduction from atmospheric pressue be utilized during the heating step 46 to cause the polymer beads to swell or "blow" more quickly and at a lower temperature. It is desirable to avoid high temperatures to avoid degenerating the strength of the composite article.
  • thermoplastic melt processable polymers such as polypropylene, polyethylene, polyvinyl chloride, copolymers, tertiary polymers, including interpenetrating polymer networks, and their admixtures.
  • additives including antioxidants, thermal stabilizers, nucleators, coupling agents, lubricants, and other processing modifiers are also utilized to advantage in connection with the molding of thermoplastic polymers in accordance with the teachings of the present invention.
  • the reinforcing fiber described herein is comprised of cellulosic material, temperatures above about 400 - 450° F will oxidize the reinforcing fiber, but the addition of one or more of these processing modifiers allows the cellulosic reinforcing fiber described herein to be melt processed at temperatures in excess of 500° F with satisfactory results.
  • thermosetting polymers may be substituted, in part or in whole, into the substituted polymer matrix or as an included modifier to a selected percentage ratio to the primary polymer to adjust the desired physical properties of the resulting molded product, the method of manufacturing that molded product, of the value benefit of the final product.
  • the polymers and methods described herein are exemplary and that a wide range of possible combinations of polymers, combinations of polymers, modifiers and stabilizing additives, and methods of manufacturing may be utilized to achieve the desired results.
  • the ratio of cellulosic reinforcing fiber to polymer is varied in accordance with the desired properties of the resulting product, it being contemplated that, in the case of the polystyrene polymer described herein, a ratio of about one part reinforcing fiber to about one part polymer is as high as is likely to be useful in most applications because, if a higher ratio is utilized, the resulting molded article is more rigid and brittle.
  • the method of the present invention contemplates a ratio of reinforcing fiber to polymer that may be as high as about one part reinforcing fiber to about 0.25 parts polymer.
  • a lower ratio of reinforcing fiber to polymer for instance, about one part reinforcing fiber to about three parts polymer, generally results in a molded article that is more pliable.
  • that pliability is desirable such that the method of the present invention contemplates that the reinforcing fiber and polymer may be blended in a ratio as low as about one part reinforcing fiber to about thirty parts polymer.
  • the ratios set out herein also depend on the particular polymer that is being blended with the reinforcing fiber.
  • the resulting molded article may be brittle even when reinforcing fiber and polymer are utilized in a ratio of, for instance, about 1 :5 such that the present invention contemplates that those skilled in the art will find it beneficial to alter the ratio of reinforcing fiber to polymer experimentally to arrive at an optimum ratio for a particular application.
  • the physical properties of the resulting molded composite article are also affected by the particular cellulosic reinforcing fiber that is utilized.
  • the reinforcing fiber that is utilized may be a mixture of about equal parts of ground reinforcing fiber that passes through a 30 mesh screen and an 80 mesh screen.
  • larger particle sizes are utilized, including particle sizes up to as much as about half an inch.
  • the present invention contemplates the use of particles of cellulosic reinforcing fiber of different shapes as described in U.S. Patent No. 4,818,604 to optimize certain properties. As disclosed in that patent, for instance, if the strength and toughness of the molded composite article is important, particles shaped as flakes help achieve those properties.
  • the molded composite article is to be painted or coated for appearance such that the smoothness of the surface of the article is important, not only is it desirable to use a small size particle, but it is also desirable to use particles that are of the same, preferably round shape.
  • These different shapes can be obtained by the use of hammer mills or other types of grinders to pulverize the cellulosic feedstock as l ⁇ iown in the art.
  • the reinforcing fiber may optionally be mixed with fumed silica before mixing with the polymer. Between about one half of one part to about one part of fumed silica is added to about 100 parts of the ground reinforcing fiber for this purpose.
  • lignin for instance, LIGNOCITE (Georgia Pacific) may be added to the cellulosic reinforcing fiber in a ratio of about one half of one part to about one part per 100 parts of the mixture of reinforcing fiber and polymer.
  • FIG. 3 there is shown a preferred embodiment of a mold for molding a composite board in accordance with the present invention.
  • a plurality of molds 50 is shown in Fig. 3, each mold 50 being comprised of thin gauge metal top and bottom surfaces 52, 54 having a mold cavity 56 therebetween.
  • the use of thin gauge material as the mold surfaces 52, 54 allows a greater degree of control over convection heat transfer on both heating and cooling of the mold 50, as well as a reduction in cooling time.
  • a series of beams 58 preferably I-beams running along the long axis of the molds 50, is used above and below the surfaces 52, 54 and a plurality of molds 50 and beams 58 are stacked in a rack 60 with a screw press 62 bearing against the stack 64.
  • a series of beams 58 preferably I-beams running along the long axis of the molds 50, is used above and below the surfaces 52, 54 and a plurality of molds 50 and beams 58 are stacked in a rack 60 with a screw press 62 bearing against the stack 64.
  • the number, size, and shape of the molds 50 will vary in accordance with the size and shape of the particular composite article being molded and that the specific arrangement of the molds 50 in rack 60 is therefore a matter of routine optimization of the molding process.
  • FIG. 5 there is shown a preferred embodiment of an oven, indicated generally at reference numeral 70, for use in raising the temperature of the mixture of polymer and reinforcing fiber above the glass transition temperature of the polymer.
  • the particular oven 70 shown in Fig. 5 is designed for use in molding composite panels of the type described above such that it is shaped to accommodate a plurality of the mold racks 60 described above.
  • the size and shape of an oven can either be optimized to the size and shape of the particular composite article being molded or that an oven in accordance with the present invention may be designed to accommodate a variety of mold shapes and numbers for use in molding different shaped composite articles.
  • oven 70 Depending upon the size and shape of oven 70, however, means must be provided to circulate sufficient heated air, and subsequently, cool air to achieve uniform temperatures for heating and cooling the molds contained in the oven cavity 72.
  • the oven 70 shown in Fig. 5 is heated (for instance, with natural gas) at about 350,000 BTU/hour and an airflow circulation of about 3000 cubic feet of air per minute is provided to maintain a relatively constant temperature throughout the oven chamber 72 during molding.
  • An intake duct 74 within oven chamber 72 acquires the air for circulation through a plurality of louvers 76 for controlling the volume of circulating air and feeds a blower 78.
  • the outlet duct 80 from blower 78 preferably directs the recycled air to impinge on the super heated air entering the oven cavity 72 from the burner 82 and the resulting mixture of recycled and superheated air is forced through a choke point 84 to prevent stratification and out into the mold cavity 72 through an expansion chamber 86.
  • the oven cavity 72 can be provided with a plurality of baffles for directing the air flow evenly throughout the oven cavity.
  • the outlet of expansion chamber 86 is shaped and positioned in the oven cavity 72 to direct the heated air into the oven cavity 72 in a vortex that reduces the likelihood of "dead air space" in the oven cavity 72 to assure adequate heat transfer and temperature control throughout the oven cavity 72.
  • the outlet of expansion chamber 86 is shaped and positioned in the oven cavity 72 to direct the heated air into the oven cavity 72 in a vortex that reduces the likelihood of "dead air space" in the oven cavity 72 to assure adequate heat transfer and temperature control throughout the oven cavity 72.
  • circulation time is, like the other factors listed above, a function of the size and shape of the oven, the particular polymer that is mixed with the reinforcing fiber of the present invention for molding, the temperatures required for molding, and many other factors such that the recycle time set out herein is only illustrative of the particular oven 70 shown in the figures for molding a composite panel and that many other recycle rates are contemplated by the present disclosure.
  • VOCs volatile organic carbons
  • the oven 70 described above and shown in Fig. 5 is designed to produce approximately 100 cubic feet of molded composite panels per hour, and at that production rate, approximately 60 pounds of pentane gas is generated each hour. VOCs are harmful to the environment and cannot safely be released into the atmosphere; consequently, the design of oven 70 is such that almost none of the 60 pounds of pentane gas per hour that is generated is released to the atmosphere. This reduction in VOC emission is accomplished by the recycling of the air in the oven cavity, and specifically, by the burning of the pentane gas pulled from the oven cavity 72 during molding in the expansion chamber 86 of the air circulating means.
  • a vent 88 is provided at a low point in the wall of oven 70 for venting any pentane gas (or other VOCs) and the vent 88 directs the VOCs to a flare stack 90 where final combusion, if necessary, is accomplished to further reduce VOC emission.
  • Another aspect of the present invention also relates to the harmful effect of VOC emission.
  • the addition of the reinforcing fiber of the present invention to certain polymers has the effect of decreasing VOC emission.
  • Application of the reinforcing fiber to, for instance, uncured polyester resin (PER) has the effect of reducing VOC emission compared to VOC emission from molding of PERs that do not include the reinforcing fiber of the present invention.
  • the reinforcing fiber is mixed with the PER in the form of the liquid resin rather than the beads described above.
  • the reinforcing fiber is added in an amount comprising about 10% by weight to a general purpose PER such as STYOL 20-4221 or 40-4232 (Cook Composites and Polymers Company, Kansas City, MO) and catalyzed with 0.9 to 2.0% methyl-ethyl ketone peroxide (MEKP), the resulting mixture contains about 50 - 60% solids and the balance is liquid styrene, and when this mixture is molded in the manner described above, free styrene vapor emissions are reduced by the absorption of about 2.2 to 2.8 times the weight of the liquid styrene component in the resin, with a reduction of vapor emissions by as much as 50%.
  • a general purpose PER such as STYOL 20-4221 or 40-4232 (Cook Composites and Polymers Company, Kansas City, MO) and catalyzed with 0.9 to 2.0% methyl-ethyl ketone peroxide (MEKP)
  • MEKP methyl-ethyl ketone
  • the addition of about 10% by volume of the reinforcing fiber of the present invention to polyester resins results in a weight loss reduction of styrene of approximately 43%. It appears that the reduction in styrene vapors (VOCs) from polyester resins is a transient phenomenon and that at least three factors are involved in this method of reducing VOC emissions from PER production.
  • VOCs styrene vapors
  • the reinforcing fiber appears to physically absorb styrene from the PER solution and effectively reduce initial vaporization. This absorption is selective to styrene because of the relatively low molecular weight of styrene compared to the molecular weight of the polyester component of the resin solution.
  • the styrene absorbed into the reinforcing fiber is still driven off by elevated temperature such that, at or about the peak temperature, the vapor pressure of the styrene and, hence, the styrene emissions, will also peak and then subside.
  • This effect is most noticeable for large molded composite articles in which the heat of the polymerization process builds rapidly in the mold due to a decrease in the thermal conductivity of the cured resin.
  • the free styrene in the PER solution also reacts to become a portion of the polymer structure during cure. This reaction effectively removes and/or prevents the styrene monomer from becoming a part of the VOC that is generated.
  • styrene vapor emission is best reduced by mixing the reinforcing fiber with the PER to temporarily "lock up" the styrene monomer by absorption into the reinforcing fiber as described above.
  • rapid curing processes that avoid excursions into high temperatures provides the best opportunity for locking the styrene monomer into high molecular weight polymers and eliminating the migration and loss of the monomer to the vapor phase.
  • rapid PER cure rates also produce high peak cure temperatures, the present invention contemplates optimization of the cure rate, followed by the cooling of the molds, in a manner known to those skilled in the art to reduce VOC emissions.
  • a further reduction in VOC emission is achieved by spraying or otherwise applying a cover coating of the reinforcing fiber described above to the molded composite article.
  • the preferred method of application of the cover coat is by the use of a so-called "particle pump” such as that manufactured by Venus- 1 Magnum Corporation (St. Russia, FL).
  • the reinforcing fiber is loaded into a storage hopper that is coupled to a compressed air stream venturi outlet and the reinforcing fiber is mixed into the compressed air stream and propelled through an application nozzle to be deposited onto the surface of the still wet molded composite article.
  • the dry stream of reinforcing fiber appears to bond to the wet surface via capillary attraction, providing further absorption of styrene monomer and functioning in a manner similar to a physical barrier to prevent escape of VOCs by evaporation of these objectionable emissions.
  • this airflow cover coating of the reinforcing fiber of the present invention is the final surface of the molded composite article, this coating is left intact as a barrier to further emissions during the final exothermic cure of the article.
  • the process is then repeated, several times if necessary, overcoating the dry sprayed layer of reinforcing fiber with a new wet coating of resin. Care must be taken that a sufficient volume of resin is applied to the dry coat of reinforcing fiber to avoid formation of voids in the interior of the laminate.
  • the saturated layer of reinforcing fiber appears to function in a manner similar to the core of a laminate, providing both bulk volume without requiring the use of more expensive resins and reinforcing materials and performing a coupling and performance role that increases the physical performance characteristics of the final article.
  • these laminated structural cores appear to function according to the teachings of the so-called Milewski packing theory (H.S. Katz and JN. Milewski, Handbook of Fillers for Plastics, New York: Chapman and Hall (1987)) to enhance the ultimate physical performance of the final molded composite article.
  • the use of a combination of reinforcing shapes and sizes of particles as provided by the cellulosic reinforcing fiber of the present invention completes the matrix structure of the polymer, reinforcing and allowing stress transfer behavior throughout the entire structure, reinforcing the what would have otherwise been unprotected resin deposits, and filling the spaces between the reinforcing fibers.
  • the combination of the cellulosic reinforcing fiber of the present invention and the resulting reinforcement provides a more ductile molded composite that is more forgiving of the more normal "micro-cracking" failure modes.
  • the present invention makes possible the substitution of what would have otherwise been the non- performing portion of the fibrous glass materials with the less expensive cellulosic reinforcing fiber without a direct percentage loss in physical properties, yet increasing other desirable properties of behavior such as impact resistance.
  • the expected physical properties of these composite molded articles can be tested and expressed alone, for instance, as tensile strength, flexural strength, compressive strength, and impact stength, or in a resulting combination that is necessary to produce a specific designed combination of properties or behavior when exposed to certain stresses. Testing by accelerating the speed of the stress that is applied to the composite, molded article in a uniaxial direction combines all these forces and stengths, noting a ductile vs. brittle failure model. Long term flexural fatigue can, for instance, be reasonably predicted with this model while the rate of failure by instant impact loadings can be shown in a "better or worse" behavior model, thus establishing a composite design guidance reflecting these combinations of forces to the entire model.
  • Adjusting the performance behavior of the molded, composite article can be accomplished with a high degree of confidence by following this model and by doing so, testing indicates that properly applied and void free, lamination of the molded, composite article in this manner can result in a doubling of the ultimate impact strength of the finished article.
  • the above-described molded, composite panels may be molded in an infinite number of shapes and sizes for use in such applications as construction components such as siding and/or structural members and decorative trim, concrete forming, outdoor playground equipment, protective structures and/or buildings, and many other purposes, the composite panels are also used in the above-described open mold process for producing such useful articles as shower and tub enclosures, boat hulls, and many other molded articles.
  • Fig. 6 showing a production line for final processing of the molded composite panel produced from the molds 50 shown in Figs. 3 and 4.
  • the production line comprises a flat conveyor 100 on which the panels are placed flat and which carries the panels past a station 102 at which a scrim is adhered to one side of the panel and then to a linear scoring saw 104 that cuts part way through and from the other side of the panels.
  • the conveyor 100 next carries the panels through a cross-cut scoring saw, or cuber, 106 that cross-cuts partly through each panel and past a series of spring-loaded, spaced rollers that serves as a score cracker 108 to break the scored panel into a plurality of strips of approximately equal width.
  • the strips are then carried past a pair of parallel, horizontally spaced rollers 110 that break the scored strips into an array of approximately equally sized tiles or cubes that is held together by the scrim and can be applied to the first layer of a thermoset resin (usually, polyester or vinyl ester) in the spray-up process.
  • a thermoset resin usually, polyester or vinyl ester
  • the scrim allows the array of tiles to conform to the shape of the open mold for subsequent application of a second spray-up layer to produce a shaped laminate that is lighter and stronger than conventional glass molded structures.
  • Continuous loading, pre-heat conditioning, temperature processing, and repeat are accomplished on a continuous transfer line using radio frequency of 50 -- 100 megahertz or microwave energy in the 915 megahertz range to heat the process moisture in the reinforcing fiber.
  • This heat transfer is used to blow the EPS beads in a moving belt conveyor of stainless steel ribbon as the top and bottom surfaces of, the mold with moving edge guides encapsulating the expanding polymer and the resulting continuous sheet is cut to length by a cross-cut scoring saw upon exiting the process line.
  • the thickness of the sheet is changed by opening or closing the gap between the endless ribbons.
  • the percentage volume and particle size of the reinforcing fiber is adjusted to provide high compressive strength and to assist in adhesion to the structural laminates. If the molded, composite panel is to be converted to scored sheet, mounted on scrim cloth in the manner described above in connection with the description of the production line shown in Fig. 6, the percentage volume and particle size of reinforcing fiber is reduced to assist in the ductile behavior required for contoured laminates.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Computer Security & Cryptography (AREA)
  • Textile Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Composite Materials (AREA)
  • Mechanical Engineering (AREA)
  • Reinforced Plastic Materials (AREA)

Abstract

Une nouvelle fibre de renforcement organique destinée aux polyesters insaturés et autres résines thermodurcissables et thermoplastiques a été mise au point à partir d'un sous-produit agricole. La fibre de renforcement génère des avantages mécaniques et de coûts souhaitables lors de la production d'articles, par exemple, dans l'industrie du polyester et des fibres de verre. Cette invention concerne aussi de nouveaux procédés de production d'articles composites, moulés au moyen de cette fibre de renforcement organique, un appareil de production de tels articles et des procédés de réduction de l'émission de carbones organiques volatiles pendant la production de tels articles.
EP01910592A 2000-02-11 2001-02-12 Plastiques renforces et leur fabrication Withdrawn EP1255638A2 (fr)

Applications Claiming Priority (7)

Application Number Priority Date Filing Date Title
US18172900P 2000-02-11 2000-02-11
US181729P 2000-02-11
US22097600P 2000-07-26 2000-07-26
US220976P 2000-07-26
US26302501P 2001-01-19 2001-01-19
US263025P 2001-01-19
PCT/US2001/004551 WO2001058674A2 (fr) 2000-02-11 2001-02-12 Plastiques renforces et leur fabrication

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EP1255638A2 true EP1255638A2 (fr) 2002-11-13

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EP (1) EP1255638A2 (fr)
AU (1) AU2001238183A1 (fr)
CA (1) CA2401045A1 (fr)
MX (1) MXPA02007702A (fr)
WO (1) WO2001058674A2 (fr)

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Publication number Priority date Publication date Assignee Title
US20020151622A1 (en) * 2001-02-12 2002-10-17 Tock Richard W. Cellulose fibers and their use in reducing VOC emissions
NO325706B1 (no) * 2006-02-15 2008-07-07 Elkem As Kompositt plastmateriale
JP7117227B2 (ja) * 2018-11-15 2022-08-12 パナソニックホールディングス株式会社 成形品およびその製造方法

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DE3120459A1 (de) * 1981-05-22 1982-12-09 Lentia GmbH Chem. u. pharm. Erzeugnisse - Industriebedarf, 8000 München Leicht verklebbares und anschaeumbares laminat
US4474852A (en) * 1983-05-23 1984-10-02 Thomas B. Crane Hydrophobic colloidal oxide treated core material, method of production and composition comprised thereof
DE3412660C2 (de) * 1984-04-02 1987-01-02 Günter H. 1000 Berlin Kiss Verfahren zur Herstellung von Formteilen aus faserigem Material
GB8623323D0 (en) * 1986-09-29 1986-11-05 Harper A R Injecting liquid resin
US4818604A (en) * 1987-03-27 1989-04-04 Sub-Tank Renewal Systems, Inc. Composite board and method
US4983453A (en) * 1987-09-04 1991-01-08 Weyerhaeuser Company Hybrid pultruded products and method for their manufacture
US5082605A (en) * 1990-03-14 1992-01-21 Advanced Environmental Recycling Technologies, Inc. Method for making composite material
US5342597A (en) * 1990-11-14 1994-08-30 Cabot Corporation Process for uniformly moisturizing fumed silica
JP2851244B2 (ja) * 1994-02-09 1999-01-27 児玉化学工業株式会社 多層積層体および多層積層体パネルを製造する方法
DE29714267U1 (de) * 1997-08-09 1997-11-13 Asglawo Gmbh Stoffe Zum Daemme Naturfaserverstärkter, tiefziehfähiger Kunststoff
TW557315B (en) * 1998-03-27 2003-10-11 Azdel Inc Filled composite material
DE19815783A1 (de) * 1998-04-08 1999-10-14 Schock & Co Gmbh Faserverstärkter Kunststofformkörper

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WO2001058674A3 (fr) 2002-04-18
AU2001238183A1 (en) 2001-08-20
MXPA02007702A (es) 2004-09-10
CA2401045A1 (fr) 2001-08-16
WO2001058674A2 (fr) 2001-08-16

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