MXPA97001083A - Extrusion of mixed body of polymer and dust demad - Google Patents

Abstract

The present invention relates to: An extrusion profile of foamed plastic, including a filler of wood or wood fiber, the foamed plastic may include polyvinyl chloride, crystalline polyvinyl chloride or polystyrene in combination with the filler made of powder

Description

EXTRUSION OF MIXED BODY OF POLYMER AND DUST OF HñDERñ BACKGROUND OF THE INVENTION The present invention relates to extrusion of polymer and injection molded products and processes. The invention has particular application to an extrusion of polymer or injection molded polymer that includes an addition of wood powder as an ingredient for the mixed body material. As a result of the increasing cost of wood and the accompanying cost of wood frames, there is a demand for alternatives for solid wood construction products. Accordingly, the use of plastic extrusion profiles as substitutes for wood products in the frame area; and door frames, walls and windows and molds has increased in recent years. Injection molded plastic has also been used in the furniture industry to form chairs, sofas, plastic boards and the like. Polymer extrusions are well known for use in forming components for window and door frames. Plastic extrusion profiles are commonly formed with polymer materials such as polyvinyl chloride and crystalline polyvinyl chloride (PVC and CPVC), polyester lime, acrylonitrile or butadiene-styrene (OBS) or similar materials. Polymer materials are conventionally used in combination with a variety of fillers, lubricants and pigments. Additionally, for foaming polymers, a blowing agent is also added to the mixed body. An example of a foamed extrusion is found in the U.S. Patent. commonly assigned No. 5,508,103, entitled "Extrusion Product with decorative improvement and procedure to do the same". As a result of the increasing cost of polymer materials, there is a need for less expensive filler materials, which can be used with polymers such as PVC, but which do not adversely affect the strength or wear resistance of the resulting profile. A filler material such as that which has given rise to increase is wood dust or wood fiber. Polyvinyl chloride terrnoplastic polymer materials have been combined with wood and wood fiber to make squeezed or molded materials or ejection. Several patents and publications have proposed extrusion and injection molded materials that combine polymers and wood fibers. An example of a patent as such is the patent of E.U.A. No. 5,406,7R8, issued to Andersen Windows. The '768 patent discloses a structural component made of polymer and wood fiber in which the polymer is rigid PVC. While rigid PVC has many uses, the present invention is primarily directed to the use of a mixed body with foam PVC. Extrusion of foamed PVC, includes a blowing or foaming agent. The addition of foaming agents can also affect the ability to add * wood dust fillers. However, the use of foamed PVC has advantages over rigid PVC in that the less dense foamed material allows for substantial cost savings in the amount of PVC used in the mixed body US Patents Nos. 5,082,605 and 5,088,910 also describe mixed-body materials formed from polymers and fillers of wood or cellulose »A difficulty presented by the additions of wood dust is the absorption of moisture by wood dust.The loss of moisture within the extrusion product can retard The extrusion rate co or result of an increase in viscosity Another difficulty involves spurring or expansion of the extrusion product with the wood powder.The wood dust particles do not expand or foam and, in this way, the foam It should be done around the wood dust particles Also, unlike polymers such as PVC, the addition of heat to wood dust does not improve the fluidity of the extrusion product. The present invention overcomes these difficulties by means of two step procedures in which the wood powder particles are encapsulated by the resin and are pelleted. The pelleted pieces are then mixed with additional resin and blowing agents. It is believed that the encapsulation process prevents moisture absorption and allows sputtering of the extrusion product. Additionally, the encapsulation provides a softer skin in the final product.

BRIEF DESCRIPTION OF THE INVENTION In one embodiment, the present invention provides a mixed body of a polymer and wood powder for the formation of an extrusion profile. The profile has use in molds, window and door frames and similar types of applications. The mixed body material includes an addition of wood powder mixed with the polymer. The mixture is crushed in a profile formed through an extruder and vacuum tank or shaper. Before extrusion, the wood powder is encapsulated by polymer and then pelleted. After mixing the additional polymer with the pelleted product, and the addition of blowing agents, the product is squeezed into a final profile. The vacuum and conformer tank helps maintain the shape of the profile as the cell extrusion product expands. The mixed body of the present invention may include various types of polymers. Several examples are presented of preferred embodiments wherein the polymer comprises PVC, CPVC and irene polyes. PVC, CPVC and polystyrene are preferably added to the mixture in the form of commercially available, normal resins, including plasticizers to allow flexibility in the final product. The mixed body also includes an amount of wood powder as well as process aids, stabilizers, lubricants, and colorants and a blowing agent. The process of the present invention uses an extruder in conjunction with a vacuum tank or shaper. The extrusion material is crushed through a die and in the vacuum conformer or tank. The material expands or foam in accordance with the conformer and is cooled. The extrusion profile of the vacuum tank or former in a hardened form, which is then hardened and completely cooled.

BRIEF DESCRIPTION OF THE DRAWINGS For a more complete understanding of the present invention, one should refer to the embodiments illustrated in greater detail in the accompanying drawings and described below by way of examples of the invention. In the drawings, which are not to scale: Figure 1 is a schematic diagram showing 1 A sequence of operations in the final extrusion process of the present invention with polyvinyl chloride and wood powder extrusion material; 2 is a schematic diagram showing the sequence of operations in the fi ex extrusion process of the present invention with polystyrene and wood powder extrusion material; Figure 3 is a longitudinal sectional view of the end of an extrusion machine with a die and shaper; Figure 4 is a cross-sectional view of the profile emerging from the former of Figure 3 illustrating, schematically, the wood dust particles - Figure 5 is a perspective view of a squeezed frame with the mixed body of the present invention.

DESCRIPTION OF THE PRESENTLY PREFERRED MODALITIES The present invention provides a mixed body of a polymer and wood powder for the formation of an extrusion profile. The profile has use in molds, window and door frames and similar types of applications. The mixed body material of the present invention can include various types of polymers in combination with the addition of wood powder filler. Several examples are presented of preferred embodiments wherein the polymer comprises PVC, CPVC and polyester. PVC, OPVC and polystyrene are preferably added to the mixture in the form of commercially available, normal reams, including plasticizers to allow flexibility in the final product. The mixed body also includes an amount of wood powder as well as process aids, stabilizers, lubricants, colorants and a blowing agent. The profile material is typically used in a frame or window frame, door, wall or other mold, and thus preferably includes component materials that provide high strength and durability. The addition of wood dust is preferably hardwood in the form of sawdust. F. The wood powder is ground to a preferred particle size in which 0% to 10% is 425 microns; 35% to 80% is 250 microns; and 15% to 50% is 130 microns. The humidity is preferably controlled in the wood powder to approximately between 3% and 6%. The materials are formed into an extrudable mixture by combining several ingredients with a high density mixer at the appropriate temperature. The resins, fillers and modifiers can be added to the mixture. The extrusion mixture is then formed into a profile by pulling the mixture through an extrusion die and former. Prior to the addition of wood dust, 1 A polymer resin is mixed with additional ingredients in a normal Henschel mixer or blender »Fn a polystyrene mixed body of the present invention, glass polystyrene (CPS) and high impact polystyrene (HIPS) are added to the blender at ba ba. The mineral oil, which acts as a moisturizing agent, is added and mixed for approximately 30 seconds followed by the addition of stearic acid, which acts as a lubricant, which is added and mixed for approximately 30 seconds. Titanium dioxide, which acts as a dye, is optionally added at this time. The total mixture of this mixture with CPS requires approximately 4 minutes in total. Alternately, PVC and CPVC can be used in case they are added to the Henschel mixer at a temperature of about 37.7 ° C and mixed at alpha speed. The other ingredients are added to the PVC and CPVC mixture as explained below for CPS. The PVC and CPVC are mixed at a temperature of approximately 93.3 ° C and then cooled to approximately 65.5 ° C. In the above-described preparation of the resin mixture, the resin is added to the wood powder in a continuous mixing machine and then crushed and sealed in a pelletizing machine. In the first extrusion to form pellets, in blowing agent is not used. In this way, the initial pellet extrusion does not include spurring of the polymer mixture. The ingredients are preferably added to a conveyor hopper so that the conveyor speed can be adjusted to add the appropriate amount of each ingredient to the mix. In this way, the polymer resin composite is added to the continuous mixing machine by a conveyor while the wood powder is added to the continuous mixing machine by another conveyor. Additional conveyors can be used for additional ingredients, such as Lubricants and colorants.

The materials are mixed together in the mixing section of the continuous mixing machine. The molten material has a melting temperature of about 176.6 ° C to 232.2 ° C. It is understood that sufficient mixing is important to cause encapsulation of the wood dust particles by the polymer resin. The molten material is heated in the continuous mixing machine to the melting temperature where it forms a continuous rope and then falls into the screw extruder section in the continuous mixing machine. The control of the melting temperature of the continuous rope is important to prevent degradation of the extruder. The molten material then leaves the extruder section of the mixing machine through a chain die with approximately 210 openings, the melting proceeds through the. chain die and the chains are pellado by a dry face pellador. Once again, the temperature control through the extruder is imported to prevent the extruder from degrading. The pellets of material are preferably formed of a size approximately 0.0381 cm in length and a diameter of approximately 0.0381 c. Afterwards, the pellet size can be increased or decreased by adjusting the speed of the pellet cutter. The pellets are preferably moved from the cutting area into a cooling chamber by cooled compressed air and are discharged in storage passages. The control of the moisture content of the pellets is also important to ensure the quality of the mixed body. At the end of the pellet process, the moisture content of nella must be less than 1% moisture. As presently understood, the polymer resin (PVC, CPVC or PS) coats the surface of the wood fiber particles. While some resin can penetrate the surface of the fiber, taking into account the toothed surface of the fiber particles, the present process is understood to encapsulate or provide a coating close to the wood fiber particles with the polymer resin and prevent or minimize the moisture penetration of the fiber particle. Only a portion of the total desired amount of resin is used in making the pellets. The rest of the resins added when making the final extrusion mixed body. For example, the entire body having 100 total parts of PVC resin, only 40 parts of resin will be added to the mixture to form the pellets. The remaining 60 parts of resin will be added to form the final product. Of course, PVC is only a portion of the commercially available PVC ream. If at all, the polystyrene is a commercially available polystyrene ream portion which is used in the mixed body of the present invention. After preparation of the polymer and wood fiber pellets, the pellets are mixed in a compound with additional polymer resins for use in making the final extrusion profiles. The polyester pellet / wood fiber is added to a mixer with additional polymer resin. In the case of PS and wood dust, CPS and HIPS are added to a Henshel mixer at low speed along with the addition of the PS / PUJvo wood pellets. At intervals of 30 seconds the additions are made of mineral oil, then the blowing agents and core agents and finally the remaining ingredients. The mixture is mixed for approximately 4 minutes at low speed and then discharged into a container. In the case of PVC or CPVC and wood powder, the pellets are added to a Henshel mixer at high speed together with PVC or PVC and CPVC resin at a temperature of about 37.7 ° C. Additional ingredients are added as the temperature is increased. The stabilizers added at 65.5 ° C followed by pellador, process modifiers and process aids at 71.1 ° C and, finally, Lubricants and blowing agents at 82.2 ° C. When the mixture reaches approximately 93.30C, the mixture is discharged in a cooler and allowed to cool to approximately 65.5 ° C. The schematic diagrams illustrating two preferred final extrusion profile preparation sequences of the present invention are shown in Figures L and 2. In Figure 1, an extruder 10 is used with a vacuum tank or a tank. 20 acts to pull the. crushed profile on a cut board 22. The process sequence shown in Figure 1 is used with polyvinyl chloride and wood powder extrusion material. A second preparation sequence is shown in Figure 2. In this sequence, the extruder 24 is followed by a former 26, squeegee 34 and cut board 36. This process sequence is used with polystyrene and powder extrusion material. of wood. In each section, the squeezed profile 58 is pulled through the die and formed. As shown in more detail in Figure 3, the extrusion of the above-described mixtures is accomplished by the use of an extruder 40 with a body 42, worm 44 and given 46. The worm acts to force the extrusion material through of the die and former 48. The former includes a cylindrical sleeve 50 with a smooth guide wall. The former substantially has the same cross-sectional shape as the. dice. The former preferably includes a cover that controls heat 5? with a connection 54 to allow a temperature regulating fluid, such as water, to be contained within the cover. The squeegee, shown in Figure 1, acts to remove the squeezed profile 58 from the former. The composition of the extruded material is prepared and introduced into the extrusion machine through the channel 60. The material is pushed through the die, where it only expands lightly, and then begins to expand fully as it enters the former 48. The cover 52 of the former 48 is maintained at a lower temperature than the softening point of the extrusion material. As the material contacts the inner wall of the former, it begins to harden from the outer surface toward the inner core. The material begins to expand or froth as it passes through the die and then begins to expand comprehensively as it enters the shaper. Stretching The vacuum of the shaper helps maintain the shape of the profile as the cellular material expands. The material cools as it passes through the former and forms its desired shape. A squeegee acts to stretch the squeezed profile from the shaper. The profile achieves a cross section that is substantially the same as the cross section of the shaper outlet. The temperatures of the die and shaper as well as the speed of the extrusion profile are parameters that affect the properties of the resulting product. A space of several centimeters may be present between the die outlet and the inlet of the former to allow some expansion of the extrusion product before entering the former. Specifically, for the PS extrusion material described above, the extruder temperatures are preferably as follows: zone no. 1: 137. -154.4 ° C; areas us. 2, 3, 4: 143.3-176.6 ° C; zone no. 5: 160-182.2 and the die: 14R.8-176.6 ° C. In contrast, for the PVC and CPVC described above, the extruder temperatures are preferably as follows: zone no. 1: 143.3-165.5 ° C; areas us. 2, 3, 4: J 48.8-182, .2 ° C; zone no. 5: lbO-190.5 ° C and the die: 160-190. ° C. The temperatures of the area no. 1 must be high enough to provide strong forward movement of the extrusion material, but not too high to create slippage of the material in the extruder screw. The temperatures of zones No. 2, 3 and 4 must be adjusted to continue the proper movement towards forward of the melt as a homogeneous mixture is made to ensure an adequate density of the foamed profile. Finally, the temperature of the die is important for the foam to expand to the proper size of the former. The extrusion profile cross section of an embodiment of the present invention is shown in Figure 4. A hard skin 66, 68 may be formed in the outer portion of the profile 70. The remaining portions 72, 74 of the profile may include a hardened skin. Or they can be left if a hard skin, as desired. Figure 4 also illustrates the encapsulated wood fibers 73 within the cellular matrix 75 of the profile. An example of a completed profile for a portrait frame is shown in Figure 5. The profile includes a decorative portion 76 as well as portions of hardened skin 78, 80. After the hair is cured and hardened, several headgear may apply to the profile to improve- and highlight- the profile. For example, the profile can be painted, stained, varnished, brushed or coated. I. Hot aluminum prints can also apply for additional decorative effect. When using the procedure described above, the pellets were prepared and crushed into profiles. One PVC / wood powder was prepared by using a 1? quantity of 100 part of PVC with the following fo rmulation: The PVC / wood powder pellets were blended to form an extrudable extrusion of the remaining PVC and a blower with the following formulation: Ingredient Parts Description PVC Resin 100 Resin Mark 1924 Tin Stabilizer Process Auxiliary Kaneka K12 Acrylic Calcium Carbonate Filler Pella PVC / powder Filler fiber wood 15 to 60 wood Calcium Stearate Lubricant Laxiol 1875 Ester Lubricant AC-629A 0.1 Luboset of non-oxidized polyethylene wax Hughes HRVP 01 .2 a .7 Blowing agent Titanium dioxide 10 Whitener Pellets from a mixture of CPVC / wood powder were prepared with the following formulation: The CPVC / wooden povo pellets were mixed to form a mixed extrudable body with the following form: 1 HOUR s Strips of a mixture of polyester reindeer or polder were prepared with the following formula: 14 l s pe lias pol i est i reno / dust of unrealized strength to form a mixed extrudable body with the s i gu i in te f o r u 1 ac i on •: The following ingredients in each exercise were mixed and used to form an extrusion profile, as previously deciphered. While several embodiments of the invention are illustrated, it should be understood that the invention is not limited to these embodiments. Those skilled in the art to which the invention relates may make modifications and other modalities employing the principles of this invention, particularly when considering the following teachings.

Claims (1)

NOVEDRD DE Lñ INVENTION CLAIMS

1. A member rnixto elongated body soli ob crushing of plast LCO foam consisting essentially do, in parts (volume): beef pol Ime ro high as at January 00 fiber wood: 15-140 ostabi 1 izadoros: up to 5 one lubricant s: hast b "aid Procedural phases: up to 10 blowing agents: hast b" dye: up to 10.? .- Fl mixed body member with ormity with the Ib claim 1, further characterized in that said polymer resin is based on polyvinyl chloride. 3. The body member according to claim 1, further characterized in that said polymer resin is crystalline polyvinyl chloride resin. 4. The mixed body member of association with claim L, further characterized in that said polymer ream is poly resin resin. h. - The mixed body member in accordance with claim 1, further characterized in that the composition of said member comprises, in parts (volume);: polyvinyl chloride resin or: about 100 pound of wood: 15 60 blowing agents: .2 to 5 6. The mixed body member according to claim 1, further characterized in that the composition of 5 said member comprises, in parts (volume): polystyrene resin: approximately 100 i ra of wood: hl) - 1 0 blowing agents: .5 to 5 7 .. The mixed body member in accordance with the 10 reiication 1, further characterized in that the composition of said member comprises, on parts (volume): crystalline polyvinyl chloride resin: about 50 rsi of polyvinyl chloride: about 40 wood fiber: 15 - 65 agonfos blower-is: ..2 to 5 8. A method to form > An elongated solid member of predetermined profile of extruded foamed material of the The composition according to claim 1, further characterized in that said method includes the steps of: buying my inactive external foam label on a compression screen by passing through a hole, said orifice It has a finished network profile in a former paddle; -jr. expanding said foam material through a former, said former having a solid internal surface defining a channel for said foam material; and solidify: > ') said foam material to form an elongated soldered member. l) "The method according to claim ñ, further characterized in that said extruded foam material is formed by a process for making pellet, said process including the steps of: encapsulating wood fiber particles with said polymer resin in an oxtruible material; squeeze and cut said inatepaL extruibie par-to form pellets de d? ho material x ruihle. 10.- The method of conformity with the claim H, characterized adornas because said expansion of said foam material causes the formation of pockets of ai r-e around said particles of wood fiber.