Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
  • B27N3/00—Manufacture of substantially flat articles, e.g. boards, from particles or fibres
  • B27N3/08—Moulding or pressing
  • B27N3/28—Moulding or pressing characterised by using extrusion presses
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
  • B27N3/00—Manufacture of substantially flat articles, e.g. boards, from particles or fibres
  • B27N3/007—Manufacture of substantially flat articles, e.g. boards, from particles or fibres and at least partly composed of recycled material
• • 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
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/022—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the choice of material
• • 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
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
  • B29C48/05—Filamentary, e.g. strands
• • 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
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
  • B29C48/375—Plasticisers, homogenisers or feeders comprising two or more stages
  • B29C48/38—Plasticisers, homogenisers or feeders comprising two or more stages using two or more serially arranged screws in the same barrel
• • 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
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
  • B29C48/50—Details of extruders
  • B29C48/76—Venting, drying means; Degassing means
  • B29C48/765—Venting, drying means; Degassing means in the extruder apparatus
  • B29C48/766—Venting, drying means; Degassing means in the extruder apparatus in screw extruders
  • B29C48/767—Venting, drying means; Degassing means in the extruder apparatus in screw extruders through a degassing opening of a barrel
• • 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
  • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
  • B29K2105/06—Condition, form or state of moulded material or of the material to be shaped containing reinforcements, fillers or inserts

Definitions

• This invention relates to two-extruder combination for processing wood fiber and process for same. More specifically, this invention relates to a counter-rotating s twin screw extruder with a side injection extruder for processing wood and other fibers with polymer or similar material to make extruded profiles and process for same.
• the moisture content of wood fibers in most extrusion processes requires drying to less than one percent to obtain a maximum output rate. Dry wood fiber has the added disadvantage that it cannot be stored. Pre-drying an organic filler such as wood fiber requires additional feeding apparatus, high intensity mixers, preheaters, hot air dryers, and/or rotary furnaces. Moisture removal equipment and procedures are expensive because of their additional equipment purchase and operating costs as well as the additional time and labor required in processing. These procedures with wood fiber can also be a fire hazard.
• twin screw extruder systems currently used in the industry have numerous disadvantages.
• Counter-rotating twin screw extruders often require a drying system, a feed material size reduction system, and/or a blending system.
• Material transportation equipment used with twin screw extrusion equipment often renders it difficult to maintain a mix ratio of material or can require an additional pelletizing operation.
• the additional equipment required with known twin screw extrusion equipment requires additional floor space and higher operational costs for power, labor, and maintenance.
• Such systems are difficult to vent inherent moisture from the organic filler and, when the polymer is melted with the wood, have a significant risk of burning the organic filler.
• Co-rotating twin screw extrusion equipment has high screw speeds (RPM) and no screw cooling. This combination presents a greater risk of burning the material at the screw tips. Co-rotating twin screw extrusion equipment cannot maintain a low melt temperature with higher head pressures which can burn the fiber during melting with the polymer.
• RPM screw speeds
• U.S. Patent Number 4,915,764 to Miani discloses a method of making panels.
• the invention of this patent combines a mixture of organic filler and thermoplastic resin.
• the extrusion equipment disclosed in this patent is constructed for multiple stages of feeding thermoplastic resin charges into organic filler as it is processed. This equipment is also adapted for multiple stages of degassing.
• U.S. Patent Number 5,497,594 to Giuseppe et al. discloses an advanced polymer and wood fiber composite structural component. This patent discloses a desirable end product made from wood fiber and polymer composite which can be extruded or injection molded.
• the industry is lacking efficient, reliable, and economical extrusion equipment and a method for processing wood fiber and polymer material into a useful product.
• the industry lacks extrusion equipment and a method for processing wood fiber with polymer wherein the wood fiber has varying and/or a high concentration of moisture.
• the invention includes extrusion equipment.
• the extrusion equipment includes a first extruder.
• the first extruder has a barrel.
• a feeding means for organic filler into the barrel of the first extruder is included.
• a moisture removing means removes moisture from the barrel of the first extruder and dries the organic filler.
• the invention includes at least one secondary extruder having a polymer mixing and heating means and feeding means for the mixed, heated, and melted polymer to feed the polymer into the barrel of the first extruder.
• a mixing and heating means for the organic filler with the polymer is included in the barrel of the first extruder with a vacuum venting means for moisture and volatile removal.
• a feeding means for the mixed organic filler and polymer from the barrel of the first extruder through a die is included.
• the invention is also a process having two extruders are linked together.
• the first extruder is, desirably, a counter-rotating twin screw extruder.
• the first extruder is, desirably, a counter-rotating twin screw extruder.
• organic filler preferably wood particles, having a variable moisture content.
• Moisture is withdrawn from the fiber in the first stage of the first extruder's barrel.
• a melted polymer is injected from a second extruder into the barrel of the first extruder after the polymer is heated and mixed in the second extruder.
• the second extruder can be a single or twin screw extruder.
• the combined mixture of organic filler and polymer is further mixed, vented, and extruded through a die. Additional processing steps are optional depending upon the profile being produced.
• Figure 1 is a top plan view of the preferred embodiment of the extrusion
• Figure 2 is a side plan view of the preferred embodiment of the extrusion equipment of the invention.
• Figure 3 is a front plan view of the preferred embodiment of the extrusion equipment of the invention.
• Figure 4 is a side plan view of the barrel of the invention.
• Figure 5 is a top plan view of a large venting surface area of the extruder barrel with an air/moisture removal system.
• Figure 6 is a side view of an injection port adapter to receive hot polymer from the second extruder into the first extruder.
• the invention includes extrusion equipment and a process wherein two extruders are linked together.
• the first extruder is, desirably, a counter-rotating twin
• the first extruder receives organic filler, preferably wood particles, that can have a variable moisture content.
• the moisture content of the organic filler can vary depending on the amount of atmospheric moisture absorbed by the filler before it is fed to the extruder.
• Moisture is withdrawn from the extruder barrel.
• a melted polymer is fed from a second extruder into the barrel of the first extruder after the polymer is heated and mixed in the second extruder.
• the second extruder can be a single screw or twin screw extruder.
• the combined mixture of organic filler and polymer is further mixed, vacuum vented, and extruded through a die. Additional processing steps are optional depending upon the "profile" or extruded article being produced.
• the first extruder of the invention receives and processes organic filler, such as wood fiber.
• organic filler such as wood fiber.
• the extrusion equipment of the invention, and especially the preferred embodiment using a first extruder that is a counter-rotating twin screw extruder, is advantageous for processing wood fiber because of its ability to mix thoroughly and vent this material with a plastic or other polymer.
• a counter-rotating twin screw extruder requires minimal considerations for wood selection, does not require moisture removal, and is suitable for blending and feeding composite materials.
• the use of a twin screw extruder for the first extruder of the invention is desirable for (1) heat-sensitive polymers, such as PVC, (2) low temperature extrusion, such as wood fiber or foam, (3) noncompounded materials, such as powder blends, (4) materials that require degassing, and/or (5) difficult feeding materials.
• the extruder screw of the first extruder of the invention is, desirably, a multi- zone extruder screw.
• the invention is a combination of a "right" extruder screw and a "left" extruder screw for use in combination as counter-rotating twin extruder screws.
• the extruder screw of this invention receives organic filler, mixes the particles of the organic filler, permits the removal of moisture from the organic filler, mixes the organic filler with molten polymer, and permits the removal of moisture and volatiles desirably by a vacuum vent.
• the flights of the screw cooperate with the extruder barrel to remove moisture without the loss of organic filler from the barrel.
• Desirable embodiments of the invention include an extruder barrel with a large venting surface area subsequent to a feed port for the organic filler. This venting area is heated and has a large opening with a large upright vent stack. Air is drawn from the vent stack. The organic filler is dried by the removal of vapor.
• the invention optionally includes an extruder barrel with a large venting surface area as described above and having a small grooved cap on the downstream side.
• the grooved cap is desirably manufactured at an angle to the extruder screw.
• the cap is grooved in a manner similar to grooved feed single screw extruders. The grooved cap forces organic filler back into the extruder barrel and screw if the organic filler "fluffs" over the screws in the venting area.
• the invention desirably includes an extruder barrel with a large vent stack with at least one port for injecting air into the dried organic filler.
• the pressurized air fluidizes the dried organic filler.
• the fluidized organic filler allows consistent moisture removal from all the fiber particles.
• Desirable embodiments of the invention include an extruder barrel with an injection port adapter to receive hot polymer from the second extruder.
• the injection port adapter is desirably on top of the barrel. Molten polymer from the second extruder is injected through the injection port adapter through the top of the barrel.
• the hot polymer enters the barrel at the apex between the counter-rotating twin screws in the preferred embodiment of the invention.
• the invention desirably includes an extruder barrel with a vacuum vent zone.
• the top section of the barrel vent zone is desirably water-cooled to prevent the adherence of melted polymer that can block the vent holes.
• the geometry of the vacuum zone provides a gap above the screws. The gap allows any material that flows over the screw flights to be forced back down into the flights without blocking the vacuum vent holes.
• the vacuum section retains the mixed material in the flight of the screw.
• the invention is also a process having two extruders linked together.
• the first extruder is, desirably, a counter-rotating twin screw extruder.
• the first extruder receives organic filler, preferably wood particles, having a variable moisture content. Moisture is withdrawn from the extruder barrel.
• a melted polymer is fed from a second extruder into the barrel of the first extruder after the polymer is heated and mixed in the second extruder.
• the second extruder can be a single screw or twin screw extruder.
• the combined mixture of organic filler and polymer is further mixed, vacuum vented, and extruded through a die. Additional processing steps are optional depending upon the profile being produced.
• extrusion equipment and process of the invention require few formulation considerations and are therefore desirable for processing recycled materials of varying grades and characteristics.
• Formulation considerations involve the selection of an organic filler, polymer, and optional additional components such as stabilizers, lubricants, coupling agents, pigments, and other the like. The price and availability of any one or more of these components are common factors in the selection of the various components.
• the most common organic filler for use with the invention is wood fiber, but other organic fillers include lawn waste, agricultural waste such as pulverized corn stalks, and natural fibers from land or aqueous plants such as cotton. Suitable wood species include softwoods and/or hardwoods. The most popular wood fibers for profile formation are pine, maple, and oak.
• wood fiber for use with the invention requires a wood fiber grade that provides the interstitial strength desired for the final product. It is important to note that wood dust is a strong to severe explosive hazard if a dust "cloud" contacts an ignition source.
• the characteristics provided to the final profile by a wood fiber are determined in part by the mesh size as well as the surface and physical characteristics of the wood fiber. Desirable wood fibers have a moisture content from about four percent to seven percent by weight, but the invention can be used with wood fibers having
• Desirable wood fiber bulk density is about 12 to 18 pounds per cubic foot.
• the color of a profile can vary by the ratio of heartwood to sap wood, the consistency of particle size, color, and density.
• Desirable polymers can be natural or synthetic polymers. Desirable synthetic polymers can be thermoset or thermoplastic polymers. The most desirable polymers include a member selected from a group consisting of polyvinylchloride (PNC), polypropylene (PP), polyethylene (PE), and polystyrene (PS).
• PNC polyvinylchloride
• PP polypropylene
• PE polyethylene
• PS polystyrene
• the wood fiber is fed into the extrusion equipment of the invention.
• the preferred equipment for feeding fibrous material is to "cram" or force-feed into the first extruder of the invention.
• Cramming or force-feeding utilizes an auger to force the material into the feed zone of the extruder screws. This system will increase the efficiency of the feed zone.
• Cramming or force-feeding is necessary for low-bulk density organic filler such as wood fiber.
• Figures 1, 2, and 3 illustrate the preferred embodiment of the extrusion equipment of this invention.
• the invention includes at least two extruders linked together.
• Figure 1 is a top plan view of the preferred embodiment of the extrusion equipment 10 of the invention.
• a first extruder 11 is a counter-rotating twin screw extruder. The first extruder 11 operates by motor 12 and has organic filler feed port 13.
• a die 14 is at the exit of the first extruder 11. The die 14 is selected to provide the geometric shape desired for the profile or preform article made by the invention.
• a second extruder 15 has an exit 16 linked to the injection port 17 of the first extruder 11. The second extruder 15 operates by second motor 18.
• FIG. 2 is a side plan view of the preferred embodiment of the extrusion equipment 10 of the invention.
• An organic filler feed hopper 20 is mounted at the organic filler feed port 13 to the first extruder 11.
• the second extruder 15 is fed raw polymer through polymer hopper 21.
• a variety of alternative feed systems can be substituted for the organic feed hopper 20 and polymer hopper 21 such as a conveyer system, screw feeder, or other commercially available equipment.
• a first belt drive linkage 25 to motor 12 operates the screws (not shown) of the first extruder 11.
• a second belt drive linkage 26 to second motor 18 operates the screw (not shown) of the second extruder 15.
• Alternative belt and non-belt drive linkages or direct drive systems can be used with the invention.
• Figure 3 is a front plan view of the preferred embodiment of the extrusion equipment 10 of this invention.
• the second extruder 15 is illustrated with the polymer hopper 21 and one or more heaters 31.
• the first extruder 11 is illustrated with the organic filler feed hopper 20 having a motorized mixer 32.
• a control panel 30 controls the operation of the extrusion equipment 10.
• the first extruder 11 is, desirably, a counter-rotating twin screw extruder.
• the first extruder receives organic filler having a variable moisture content. Moisture is withdrawn from the extruder barrel.
• a melted polymer is fed from a second extruder 15 into the barrel of the first extruder 11 after the polymer is heated and mixed in the second extruder 15.
• the second extruder 15 can be a single screw or twin screw extruder.
• the combined mixture of orgamc filler and polymer is further mixed, vacuum vented, and extruded through the die 14.
• the preferred embodiment of the invention uses a left-hand screw and a right- hand screw as counter-rotating twin screws.
• the multi-zone extruder screw preferably, has a large feed and vent zone for its initial processing of organic filler.
• the extruder screws of this invention receive organic filler, mix the particles of the organic filler, permit the removal of moisture from the organic filler, mix the organic filler with molten polymer, and vacuum vent the composite material.
• the flights of the screw cooperate with the extruder barrel to remove moisture without the loss of organic filler from the barrel.
• Figure 4 illustrates an extruder barrel 40 for use with the invention.
• the extruder barrel 40 has a large venting surface area 41 subsequent to the organic filler feed port 13 for the organic filler. This venting surface area 41 is heated and desirably has a large opening with an air/moisture removal system. Air and moisture are drawn from the large opening.
• the organic filler is dried by the removal of vapor.
• a mounting plate 42 is provide for a
• FIG. 5 illustrates a top plan view of a large venting surface area 41 of the preferred extruder barrel 40.
• the venting surface area 41 is the internal portion of a venting hood, with a vent port 43 and a vent stack 44 connected to an air removal system (not shown).
• the large venting surface area 41 is, desirably, subsequent to the feed port 13 for the organic filler.
• the venting surface area 41 has a large opening at the vent stack 44 which is connected to the air removal system. Air and vapor are drawn from the large opening.
• the organic filler is dried by the removal of vapor.
• the invention optionally, includes an extruder barrel with a large venting surface area as described above having a grooved cap (not shown).
• the grooved cap is desirably manufactured at an angle to the extruder screw.
• the cap is grooved in a manner similar to grooved feed single screw extruders.
• the grooved cap forces organic filler back into the extruder barrel and screws if the organic filler fluffs over the screws in the venting area..
• Figure 6 illustrates a desirable injection port adapter 60 to receive hot polymer
• the injection port adapter 60 is, desirably, on top of the barrel 40. Molten polymer from the second extruder 15 is
• the injection port 60 of this embodiment includes a thermocouple 61, two spacer rings
• Preferred embodiments of the invention have an extruder barrel with a vacuum vent zone.
• the top section of the barrel is desirably water-cooled to prevent the
• the geometry of the vacuum zone provides a gap above
• the gap allows any material that flows over the screw flights to be forced back down into the flights without blocking the vacuum vent holes.
• section retains the mixed material in the flight of the screw.
• the invention includes an extrusion process.
• the process includes feeding
• organic filler into a barrel of a first extruder. Removing moisture from the barrel of the first extruder is performed to dry the organic filler. Mxing and heating polymer in at
• the extrusion equipment and process of the invention have the following advantages.
• the invention processes wood fiber with higher moisture content than traditional equipment and processes.
• the invention uses lower screw speeds or
• the invention uses a separate melting process of polymer from the organic fiber and provides good mixing of wood fiber and polymer. The melted polymer encapsulates fibers more easily and consistently.
• the extrusion equipment uses standard screw cooling and eliminates the risk of burning at screw tips.
• the invention is also able to maintain low melt temperatures with high head pressures.
• the extrusion equipment provides a superior venting system, prevents material from sticking and clogging vent ports, and prepares the composite melt before it reaches the vent port.
• the cost of drying, material size reduction, and preblending operations are eliminated.
• the invention resolves the material transportation/mix ratio difficulties of traditional equipment and processes.
• the invention is flexible and permits the switching of composite ratios "on the fly. " The invention permits processing of a complete range of polymers without major equipment changes.

Applications Claiming Priority (3)

Publications (1)

Family

ID=22746870

Family Applications (1)

Country Status (3)

Families Citing this family (7)

Family Cites Families (5)

• 2001
  • 2001-04-30 WO PCT/US2001/013745 patent/WO2001083195A2/en not_active Application Discontinuation
  • 2001-04-30 EP EP01932726A patent/EP1278625A2/en not_active Withdrawn
  • 2001-04-30 JP JP2001580056A patent/JP2003531750A/ja active Pending

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events