EXTRUDED POLYMER FOAM WITH FILLER PARTICLES AND METHOD

Abstract: Process of extrusion of high levels of filler which is contained in a polyol and an isocyanate in a screw extruder (32) along with a catalyst, a surfactant and a blowing agent and the mixture is extruded to produce a thermoset onto a conveyor (2) and subsequently foamed.

Description: EXTRUDED POLYMER FOAM WITH FILLER PARTICLES AND METHOD Field Of The Invention The invention relates to foamed polymer material, methods for producing polymer foams, and, particularly, to a method for extruding polymer foam material, such as polyisocyanurate and polyurethane foams, using a screw-type extruder. The extruded polymer foams contain substantial amounts of filler particles. Background Of The Invention Polymer foams, such as polyisocyanurate and polyurethane foams, have not previously been able to be produced using an extruder. The foaming material "firms" in the extruder and blocks the equipment. Additionally, use of filler materials has been limited using conventional methods to produce foam sheets. U.S. Patent No. 3,466,705, (Richie) describes an apparatus for extruding foamable thermoplastic material, such as polystyrene, preferably in tubular form. Richie discloses that the apparatus can be used for thermosetting materials, such as polyurethanes, but that steam or hot water would have a damaging effect and therefore are not used. A foaπi- augmenting gas such as freon is used as the foaming agent. Richie use an expansion space of transverse cross-sectional area which increases in size gradually in the direction of travel of the extruded product. U.S. Patent No. 5,149,722 (Soukup) and U.S. Patent No. 4,795,763 (Gluck) describes the use of about 1-10% by weight of carbon black as a filler material. Gluck specifically recites the problem of cell rupture which can occur with the addition of too much filler materials. The Soukup and Gluck patents are incorporated herein by reference as if fully set forth. Summary Of The Invention Polymer foam board is disclosed which includes high levels of filler material, such as 15%-20% by weight filler particles, or higher. Polyisocyanurate or polyurethane foam is made using a screw-type extruder for mixing the components of the composition. Isocyanate and polyol are introduced into a screw of an extruder. Filler particles are also introduced in the extruder screw. The isocyanate, polyol, and filler particles are mixed together with a foaming agent and, optionally, a surfactant with the extruder to produce a high quality dispersion. The mixture is cooled via a cooling manifold of the screw extruder and the addition of the various components in the mixture. Cooling inhibits reaction of the mixed components within the screw. Catalyst is added and mixed with the polyol/isocyanate/filler particle mixture in the extruder screw as a final mixing step. After the catalyst is introduced, the mixture is almost immediately extruded onto a conveyor so that the firming occurs outside of the extruder to avoid clogging. The mixture is foamed and firmed on the conveyor in a conventional manner and, preferably, formed into a continuous flat sheet which is thereafter cut to produce boards of standard sizes. The filler particles included in the thermoset foams produced in accordance with the invention maintain the mechanical or insulative characteristics of the resultant extruded foam as compared to the properties of the extruded foam without filler particles. However, with some fillers improved characteristics result. For example, carbon black can improve the insulation properties of the foam as set forth in the Soukup and Gluck patents, supra. Overall, the addition of filler particles make the resultant foam more economical to produce and the process enables the use of more filler materials in the production of suitable foam board insulation. Different filler particles can be used in the same foam. For example, carbon black and another type filler particle, which is less expensive, can be used to gain the insulative effect of the carbon black while increasing costs savings. Aluminum trihydrate, perlite and calcium carbonate are preferred filler materials, used either as the sole filler material or with carbon black. Other filler materials include carbon black, diatomaceous earth, polyiso powder, and barium sulfate and calcium silicate. The filler particles added to the polyol/isocyanate mixture in the extruder reduce the cost of the resultant extruded thermoset foam, since the filler particles are lower in cost than polyol and/or polyisocyanate . The filler particles and/or dispersant and/or foaming agent and/or surfactant may be mixed with the isocyanate or with the polyol before introduction thereof to the extruder screw. If multiple fillers are used, they can be mixed prior to entering the extruder screw or can be introduced, simultaneously or separately, into the extruder screw and mixed therein. Entry of the filler particles, or a filler particle mixture can occur simultaneously or separately from entry of dispersing agent and/or surfactant and/or the polyol and/or the isocyanate. The foaming agent, which is preferably a hydrochloro- fluorocarbon (HCFC) or water, is preferably introduced directly into the extruder or may be mixed with one of the components, preferably the polyol, before introduction thereof to the extruder screw. If water is the foaming agent, the water is vaporized for foaming the mixture and reacts with the isocyanate to form carbon dioxide, which further foams the mixture. Other foaming agents may alternatively be used. Foam cell size is generally decreased when extruder speed is increased. A filler particle dispersion may be made in the extruder using filler particles, dispersant, optional surfactant, and isocyanate or polyol. Preferably, a catalyst is added to this dispersion for immediate extrusion and foaming. Alternatively the dispersion can be stored for future use. An extruder provides better quality dispersion, measuring 8 or more on the Hegman scale, than a dispersion made in a Kady (kinetic dispersion) mill . It is an object of the invention to provide an improved method for making polymer foams containing filler particles. It is another object of the invention to provide a method for extruding filler particle-containing thermosetting foams, such as polyisocyanurate and polyurethane foams, using a screw-type extruder, such as a twin-screw extruder. It is yet another object of the invention to provide a method for making a filler particle dispersion in an extruder. It is a further object of the invention to combine preparation of a filler particle dispersion and production of a foam using the filler particle dispersion, in a single operation. Brief Description Of The Drawings Figure 1 is a schematic illustration of an apparatus for extruding polymer foam onto a conveyor. Figure 2 is a schematic illustration of an extruder for an integrated process including preparation of a polymer premix before extruding the polymer mixture for foaming. Figure 3 is a cross-sectional view of a preferred extruder outlet . Figure 4 is a front elevational view of the outlet shown in Figure 3. Detailed Description Of The Invention Thermosetting foams, such as polyisocyanurate or polyurethane foams, are made using an extruder for mixing the foamable mixture before extruding onto a belt conveyor. Through such a continuous process, thermosetting foams are made much faster than previously possible without any decrease in quality. Additionally, the process enables the dispersion of filler particles with the polymer mixture to produce foams which include 12-15% by weight or more filler particles thereby reducing the production cost of the thermoset foams. The extruder enhances the dispersion of the polymer mixture. A twin-screw extruder is preferred. However, a single screw extruder with multiple mixing sections can also be used. The extruder can process materials for making a thermosetting polymer, such as an isocyanate polymer, in a controlled manner with independent catalyst addition and variable reactivity. High quality filler particle dispersions in isocyanate or polyol media are obtained. These dispersions exceed 8 on the Hegman scale. Moreover, higher levels of filler particles can be handled than on conventional foam mixing equipment . The foams may be blown with blowing agents such as hydro- chlorofluorocarbons (HCFC) , CFC, HFC, HC and/or water which produces C0 2 . Typical examples of hydrochlorofluorocarbon blowing agents are HCFC 141b and HCFC 22 which can be advantageously combined in preferred proportions. High viscosity isocyanates and polymer premix, which cannot be processed using a conventional Kady mill and conventional foam mixing equipment, may be used in the process described. The extruder is cooled downstream of the dispersion section of the extruder to prevent premature reaction of the foam ingredient . The low torque requirements permit use of virtually any size extruder. Flocculation of filler particle/polyol dispersions can be avoided by maintaining a high shear rate on the dispersion, through the foaming section, producing a foam with excellent filler particle dispersion. In general, the quality of the dispersion increases with increased filler particle loading and with viscosity of the starting medium. Addition of the polyol or isocyanate in the dispersion section may be accomplished in several staged injections. This is preferred for keeping the viscosity and shear high enough to ensure a high quality dispersion. The preferred dispersions were obtained when the charge of filler particles was added with the first injection of the dispersion medium to form a mixture. The final preferred filler percentage of 12% to 20% was then obtained by subsequent liquid injections in the dispersion section of the extruder. Maximum temperatures of about 50°C. in the dispersion section do not present an operational problem. The dispersion is actively cooled by cold water circulating in the barrel jackets and screws and passively cooled by injection of the remaining foam ingredients into the dispersion. A preferred extruder screw speed to provide a good foam mix is about 300-600 rpm. Speeds may range to 1000 rpm or higher. For extended use at high speed, a special hardening treatment is advantageously used on the screw element in the dispersion section due to the abrasiveness of the filler particles. Throughput is a function of both screw speed and extruder size. A desired throughput for a 30-40mm extruder is about 450-600 lb./hr. One method of extruding polyisocyanurate foam includes adding a blend of isocyanate, and filler particles at a first position of the extruder, adding polyol blend to mix with the lsocyanate blend at a second position of the extruder closer to the extrusion position than the first position, adding catalyst blend to the mixed polyol and isocyanate blend at a third position of the extruder proximate the extrusion position, and extruding the catalyzed mixture onto a belt conveyor for foaming. With reference to Figure 1, an extruder apparatus 2 suitable for practicing the invention is illustrated. The apparatus 2 includes an extruder 4 which has barrels, B1-B9 A single or twin screw extruder may be used A twin screw extruder provides better mixing and is preferred The barrels of the extruder are preferably separated by sheets of Graphoil paper, which aids in taking down the apparatus. Isocyanate solution is mixed and provided to reservoir 6 having a large capacity, preferably a 30 gallon capacity A suspension of filler particles in the isocyanate may be fed to reservoir 6 or the filler particles can be fed into barrel Bl via a hopper 8. Solution from reservoir 6 is fed, m a non-limiting example, to barrel B7 of extruder 4 Polyol is mixed with water (foaming agent) , for example in Lightning mixer 10, and fed to extruder 4 at location 12, between barrels B7 and B8. Alternatively, the isocyanate and the filler particles may be fed, for example, to hopper 8 feeding into barrel Bl, and the isocyanate and/or filler particles mixed together in the extruder before the polyol is added. The polyol and isocyanate containing filler particles are mixed in the extruder. Thereafter catalyst is fed from a reservoir 14 to barrel B9 and mixed therewith. The catalyzed mixture is fed through the discharge end of the extruder onto a belt conveyor. The discharge end 16 of the extruder suitably has an inclined discharge piece 18 or a flat discharge piece (Figure 4) , for directing the foam downward onto a conveying/forming apparatus 11. The temperature in the extruder is controlled by cooling the barrels and screws, as known in the art. Barrels B7 through B9 (at least) are cooled, generally by water cooling, to facilitate mixing the components of the reaction mixture without clogging the extruder. The conveying/forming apparatus 11 includes a conveyor 20, onto which the foam is discharged from end 16 of extruder 2. The foam, passes between a pair of rolls 23 which rotate in opposite directions and then onto a slat conveyor 24, 26 through a heated area 28 in which the foam rises. Optionally the foam is introduced between upper and lower paper liners. Appropriate location of the lining paper rolls (not shown) is apparent to one skilled in the art. The resultant product is a laminated insulation sheet . Slat conveyors typically vary from 20-100 feet in length. The slat conveyor 24 is heated to about 150°F. This portion of the conveyor is substantially closed in by enclosure 28 to conserve heat. Doors (not shown) are placed about every 10 ft. along the enclosure to allow access to the equipment. The mixture foams and firms as it passes at about 30 to 150 ft./min. along the conveyor. The foam passes onto a roller conveyor 30 about 20 to 100 ft. in length, substantially at room temperature, for curing before being cut into panels for use. A typical apparatus of this type is shown in Gluck, U.S. Patent No. 4,795,763, discussed above. In another example, shown in Figure 2, an extruder 32 having 12 barrels A1-A12 is used. Filler particles are fed to barrel Al from hopper 34, a premix of polyol and surfactant is fed from mixer 36 between barrels Al and A2 and mixed together with the filler particles in the extruder screw. The remainder of the polyol is added from a reservoir 38 to barrel A6 and mixed with the filler particle and polyol premix. Isocyanate is fed from a reservoir 40 to barrel A9 and mixed with the ingredients already in the screw of the extruder. In this example, hydro-chlorofluorocarbon blowing agent (HCFC- 141b) is used, and is added from a reservoir 42 to barrel All. Catalyst, such as potassium octoate, is added from a reservoir 44 to barrel A12 of the extruder, and mixed into the reaction mix immediately before extrusion. The mixture is extruded from die 46 onto a conveying/forming apparatus, such as illustrated in Figure 1. Where more than one type of filler material is to be used, separate feed bins 48 for each type of material are provided. The amount of filler fed to the hopper 34 from each bin is controlled to provide a desired proportion. A preferred combination of filler materials is carbon black and aluminum trihydrate, relative proportions are dependent upon the R value and physical properties desired. For making dispersions without foaming, the fillers are added via hopper 34 and the isocyanate is added from mixer 36 and reservoir 38. It is well known in the art of thermosetting foams that, in the process of making polyisocyanurate or polyurethane foams, when the mixture is prepared, there is an exothermic foaming reaction. The speed of this reaction is controllable according to the temperature at which the reaction takes place. The foaming action is described as having a "cream time, " during which foaming is initiated and the material reaches a consistency of a soft creamy foam, and a "firm time" at which the foam sets up and hardens. In a typical non- limiting example, the cream time may be 7 to 12 seconds and the firm time may be 35 to 60 seconds. The properties of the product may be changed by adjusting the concentrations of the materials, temperatures of the barrels, etc. In prior attempts to extrude thermosetting resins of this type, extrusion has not been successful because the reaction mechanism has not been controlled within the extruder and the mixture has creamed and/or foamed within the extruder and blocked the extruder, preventing extrusion. A typical extruder die which is useful in avoiding excessive build-up of foam on the die is shown in Figures 4 and 5. Discharge plate 50 of extruder 52 is attached to barrel 54. Screw 56 has a flat tip 58 and discharged material 60 falls directly between rolls 62,64 carrying lining paper 66, 68 for the conveyor (as shown in Figure 1) on which the isocyanate polymer is foamed. In making insulation boards, the extrusion process described herein allows fast, economical production. Filler particle addition reduces the cost of the insulation boards so produced. The thermal conductivity of insulation board is reduced by adding carbon black. This advantageously reduces board thickness. The thermal conductivity of polyisocyanurate foams, based on different foaming agents, in BTU per cu.ft., per hr., per °F, are as follows: isocyanurate/HCFC 0.12 isocyanurate/carbon black/HCFC 0.09-0.1 isocyanurate/water 0.14-0.19 isocyanurate/carbon black/water 0.135-0.17 isocyanurate/carbon black/HCFC/water 0.09-0.135 Use of HCFC (hydrochlorofluorocarbon) foaming agent advantageously reduces the foam's thermal conductivity. Carbon black also reduces the thermal conductivity, compensating for increased thermal conductivity when water is the foaming agent. The formulation may also include inorganic flame retardants. Inorganic flame retardants increase the isocyanurate and polyol components' viscosities. A screw extruder allows thorough mixing of higher viscosity components with better dispersion for use of higher percentage of filler materials. The mix is discharged from the extruder prior to the start of the firming reaction. A filler particle dispersion may be made in the extruder using the filler particles, carbon black, optional surfactant and isocyanate or polyol. Dispersions may be used immediately or stored for future use. Isocyanate dispersions are preferred where storage is intended, since polyol dispersions tend to become less disperse when stored. Examples 1 to 33 Carbon black dispersion made in the extruder screw Table 1 shows the composition used for each formulation and Table 2 shows the composition of each polyol premix, used as indicated in Table 1. Pelron P-344 dispersant and Cabot Black Pearls 280 carbon black were used in all the examples. The catalyst was a 3:1 blend, by weight, of potassium octoate and DMP-30. A catalyst blend of 3:1 to 6:1 may be used. The ratio of the catalyst blend is dependent upon how close the catalyst is added to the extruder outlet. The average equivalent weight of BASF 226 prepolymer (polymer/isocyanate mix) and ICI high viscosity isocyanate is about 152. The operating run schedule is shown in Table 3 and operating parameters of the extruder are shown in Table 4. The torque developed was higher for the carbon black dispersions when compared with the white controls, but was still very low relative to the capabilities of the extruder, and is not a limiting factor. Exit temperatures of the foam mix are shown to be a function of the level of carbon black and the original viscosity of the dispersion medium. The preferred exit temperature is about 25° to 32°C. Table 5 shows properties of selected test foams. Example 34 Carbon black dispersion made outside the extruder screw Component A: Polymeric methyldiisocyanate (MDI) 91% carbon black 9% (viscosity: 20,000 cps) (dispersion quality: Hegman bar - 50 microns) Component B: polyol 91% silicone surfactant 5% water 4% Component C: preblended catalyst (potassium octoate) 2% Components A, B and C were mixed in the percentage ratio A:B:C of 74:24:2, by weight. Table 1 Formulation Component Parts % Index % by Trimer Weight I Premix I 40.6 11.8 2.74 12.4 2852E Polyol 59.4 17.2 MR-200 Isocyanate 192.0 55.7 Catalyst 7.5 2.2 HCFC - 141b 45.0 13.1 II Premix II 40.6 11.2 2.93 12.8 Carbon Black 17.4 4.8 (C/B) 2852E Polyol 59.4 16.4 MR-200 Isocyanate 192.0 53.0 Catalyst 7.5 2.1 HCFC - 141b 45.0 12.4 III Premix III 63.5 17.0 3.00 12.9 Carbon Black 27.2 7.3 ( C/B ) 2852E Polyol 36.5 9.8 MR-200 Isocyanate 192.0 51.5 Catalyst 7.5 2.0 HCFC-141b 46.3 12.4 IV Premix IV 40.6 11.5 2.97 12.7 Carbon Black 17.4 4.9 (C/B) 2852E Polyol 50.0 14.2 Isocyanate (ICI, 192.0 54.5 or BASF 226 Prepolymer) Catalyst 7.5 2.1 HCFC-14lb 45.0 12.8 Table 2 Polyol Premix I II III IV pbw % pbw % pbw % pbw % 2852E Polyol 37.1 91.4 33.9 83.5 55.0 86.6 33.9 83.5 Y10222 3.5 8.6 3.5 8.6 3.5 5.5 3.5 8.6 Surfactant P-344 Dispersant - - 3.2 7.9 5.0 7.9 3.2 7.9 Table 3 RON SCHEDULE Run No. Formulation Foam Type Key Variable 1 I White Control Density Check 1.65 2 I White Control Lower 141b 1.67 3 I White Control Higher 141b 1.51 4 II Black Control Hegman 7 5 II Black Control Lower 141b 6 II Black Control ISO Adjustment 7 II Black Control Mix/Rate Study @ 600 RPM 8 II Black Control Mix/Rate Study @ 500 RPM 9 II Black Control Mix/Rate Study @ 600 RPM 10 III Black Control Mix/Rate Study @ 600 RPM 11 III Black Control Mix/Rate Study <_ ■ 500 RPM 12 III Black Control Mix/Rate Study <_ ■ 500 RPM 13, 13A IV Black, Prepol . Mix @ 500 RPM, 13A Higher ISO 14 IV Black, Prepol. Mix _> 600 RPM 15 IV Black, Prepol. Mix/Rate Study @ 600 RPM 16 IV Black, Prepol. Mix/Rate Study @ 500 RPM 17 IV Black, Prepol. Mix/Rate Study @ 500 RPM 18 IV Black, ICI Mix @ 500 RPM 19 IV Black, ICI Mix @ 600 RPM 20 ' IV Black, ICI Catalyst Adjustment 21 IV Black, ICI 141b Adjustment 22 IV Black, ICI 141b Adjustment 23 IV White, Prepol. Control 24 IV Black, Prepol. Prepol + C/B 25 IV Black, Prepol. Higher C/B @ 500 RPM 26 IV Black, Prepol. Higher C/B @ 600 RPM 27 IV Black, Prepol. Low Rate, Low on Matl. 28 IV White Control ICI High Vise. ISO 29 IV Black Control Std. % C/B 30 IV Black Control Higher C/B 31 IV Black Control Higher C/B 32 IV Black Control Higher C/B 33 IV White Control R-22 Froth Table 4 OPERATING PARAMETERS Run RPM % lbs/hr Exit % C/B Foam No. Torque Temp. Quality °C 1 500 5.1 300 28 0 Good 2 500 5 300 27 0 Good 3 500 4.9 300 28 0 Good 4 500 16 300 27 4.8 Good 5 500 15.9 300 28 4.8 Good 6 500 15.8 300 28 4.8 Good 7 600 15.2 300 29 4.8 Good 8 500 17.7 400 29 4.8 Good 9 600 16.4 400 29 4.8 Good 10 600 16.7 450 29 7.3 Good 11 500 22 450 29 7.3 Good 12 500 24 400 29 7.3 Good 13 500 14.3 300 30, 31 4.8 Good, Si. Soft 14 600 13.7 300 33 4.8 Fair 15 600 16.1 450 35 4.8 Fair 16 500 16.8 450 34 4.8 Fair 17 500 21.0 600 32 4.8 Fair 18 500 20.6 300 31 4.8 V. Good 19 600 19.8 300 32 4.8 . Good 20 600 18.0 300 32 4.8 V. Good 21 600 17.6 300 33 4.8 V. Good 22 600 17.4 300 32 4.8 V. Good 23 500 7.0 300 7 4.8 V. Good 24 500 14.0 300 14 4.7 V. Good 25 500 27.0 300 27 7 V. Good 26 600 24.8 300 25 7 V. Good 27 600 24.0 190 24 7 V. Good 28 500 6.4 300 34 0 V. Good 29 600 13.5 300 37 4.7 V. Good 3C 600 14.7 450 34 7 V. Good 31 600 29.0 300 39 7 V. Good 32 600 27.6 300 40 7 V. Good 33 600 26 300 33 0 V. Good Table 5 Run k-Init. k-Aged % Closed % Density No. Cell Friability 1 .136 - - - 1.62 2 .140 - - - 1.69 4 - .167 79 29 7 .128 - - - 9 .124 - - - 10 .131 - - - 12 .134 - - - 13 - .141 81 8 13A - .136 81 13 14 .123 - - - 15 .121 .145 86 12 16 - .138 85 13 17 - .148 87 35 18 - .155 85 18 19 .123 .146 - - 20 - .146 86 20 21 .128 - - - 22 .139 - - - 23 .132 .139 84 8 28 - .149 90 20 29 - .132 - - 33 - .177 81 12 Using apparatus of Figure 1, the process was started by injecting component A into barrel B7 until it was observed exiting the extruder. Component B was then injected to the spacer between barrels B7 and B8, followed by injection of catalyst to barrel B9. Shutdown was performed in reverse order. The machine was purged with methylene chloride. The product had a compression strength of 26 psi, a density of 2.3 lb./cu. ft. and a K factor (thermal conductivity) of 0.168 BTU/sq. ft. /°F. When the machine was taken apart, it was easy to remove the barrels separated by Graphoil paper. The internal surfaces of the barrel in the process section were coated with a thin hard layer of cured material but this was readily removable . Substantially higher concentration of isocyanate (component A) leads to hard and brittle foam. Substantially higher concentration of polyol (component B) leads to rubbery, soft foam and increased exotherm of reaction. As the speed of the machine is increased, the cell size of the foam is decreased. Variation of these parameters to provide foam having certain characteristics will be apparent to one skilled in the art. Example 35 Carbon black dispersion made in the extruder screw Component A: polymeric methyldiisocyanate (MDI) 100.00 parts carbon black 9.29 parts dispersant 1.93 parts surfactant 1.7parts Using apparatus of Figure 1, the process was started by injecting the ingredients for component A into barrel B7 until it was observed exiting the extruder. The dispersion produced was of better quality than that produced in a Kady mill and registered more than 8 on the Hegman scale. In a further embodiment of the invention, polyisocyanurate bunstock may be made using an extruder. The bun is cut from an extrudate which is passed from the die of the extruder to a conveyor belt having release-coated paper liners on the top, bottom and sides. A kraft paper liner having a polymer coating is suitable for use as a release paper. A 20 ft. conveyor may be used, moving at about 9 to 10 ft./min. The bunstock may be from 4 in. to 2 ft. or more in thickness. The foam is warm as it exits the extruder and is allowed to cure for 4 to 6 days. In a typical example of making bunstock on an extruder, the following formulation was used: Example 36 Bunstock made in the Extruder Material ppm Isocyanate (Miles - Mondur MR) 101 Polymer resin (Iso-Shield - P101) 78 R-ll (Atochem - Isotron 11 or 141B) 13.81 Catalyst #1 (Air Products - TMR-3) 1.17 Catalyst #2a (Air Products - DMEA) .312 Catalyst #2b (Ashland - DEG) .312 The foam was extruded from a die of an extruder, having a large cross-section, as shown in figures 3 and 4, onto a conveyor lined with paper on the top, bottom and sides, to form bunstock having dimensions of about 27" high x 51?_" wide. The cream time was 28 sec, the gel time was 2 min. 34 sec, the rise time was 3 min. 55 sec. and the tack free time was 4 min. 31 sec. The conveyor speed was about 9 to 10 ft./min. Bunstock may be extruded at a speed of about 200 lb. /min. A typical bun may be about 27" x 51 ^_" x 10 ft. in size and may be cut to smaller blocks, as required. Different levels of carbon black may be used, providing different K-values . The extruder may alternatively be used to make the filler particle dispersion only, which is then fed to a tank for storage and later use. When the extruder is used for making both the dispersion and the foam, the cream time and gel time are relatively slow due to the size of the bunstock. The bunstock which is liquid at extrusion onto the conveyor, is firm after reaching the end of the conveyor and being released from the paper liners. The process described allows for large volume bunstock to be made, of very high quality. Examples 37-48 High Filler Particle Content Foam A number of examples of foams having a high filler particle content were produced using the process explained in conjunction with Figure 2 above. Table 6 presents the various formulations of materials which were used in the examples and Tables 7a and 7b provide a tabulation of the characteristics of the resultant thermoset foam. The examples illustrate how polymer foams can be made using the extrusion process which can contain in excess of 15% filler material . Test runs were conducted using a ZSK-40 extruder having a 40mm wide extruder. Depending upon the type and size of the sheet to be produced, larger capacity extruders are used for commercial production such as extruders having diameters 58mm, 70mm, 92mm, or 120mm. Table 8 provides ranges of preferred processing rates for the various size extruders. Table 6 Table 7a EXAMPLE 37 38 39 40 41 42 Formulation Type A A A A B B Iso Index 2.30 2.50 2.50 2.50 2.50 2.20 Average 1.53" 1.56" 1.56" 2.12" 1.28" 1.44" Thickness Board Density 2.29 2.45 2.54 2.09 2.83 2.48 Core Density 2.10 2.39 2.39 1.86 2.61 2.17 K-Value 0.138 0.136 0.138 0.135 0.133 0.13 Compressive 22.41psi 19.6psi 26.44psi 19.34psi 32.62psi 30.4psi % Closed Cell 82.00% 84.20% 83.30% 83.30% 81.00% 77.30% Hot Dip good good good good good good Cold Aging 0.00%/ 0.58%/ 0.42%/ 0.00%/ 0.00%/ 0.00%/ (% shrink) 0.42% 0.00% 0.00% 0.00% 0.00% 0.00% machine/crosscut Humid Aging 0.93%/ 0.37%/ 0.37%/ 0.56%/ 0.37%/ 0.37%/ (% growth) 0.45% 0.69% 0.45% 0.00% 0.34% 0.34% machine/crosscut Table 7b EXAMPLE 43 44 45 46 47 48 Formulation Type C C D D E E Iso Index 2.60 2.60 2.50 2.50 2.50 2.50 Avg . Thickness 1.33 2.50 1.44 2.43 1.44 2.44 Board Density 2.42 2.33 2.38 2.33 2.89 1.99 Core Density 2.28 2.28 2.14 2.14 2.59 1.86 K-Value 0.141 0.141 0.138 0.135 0.138 0.134 Compressive 14.6ps 18. Ops 22.04ps 21.82ps 22.50p 20.66ps i i i i si i % Closed Cell 81.13% 82.17% 83.37% 82.00% 84.19% 82.63% Hot Dip good good good good good good Cold Aging (% 0.00%/ 0.09%/ 0.17%/ 0.11%/ 0.00%/ 0.08%/ shrink) 0.00% 0.12% 0.00% 0.08% 0.00% 0.00% machine/cross cut Humid Aging (% 0.06%/ 0.12%/ 0.06%/ 0.13%/ 0.00%/ 0.06%/ growth) 0.17% 0.11% 0.12% 0.17% 0.00% 0.17% machine/cross cut Table 8 Extruder Output Ranges 1 Extruder ZSK-40 ZSK-58 ZSK-70 ZSK-92 C-120 High Range lbs/hr 450 1350 2411 5500 12150 lbs/min 7.5 22.5 40 92 202.5 Low Range lbs/hr 600 1800 3215 7300 16200 lbs/min 10 30 54 122 270 f t/min - 33-44 58-78 134-177 276-391 'Calculated fc r 1" thick f oam product - 19" wide anc 1 2.0 lbs/ci j. ft. in- place density. While the invention has been described with reference to certain embodiments thereof, it will be appreciated that variations and modifications may be made without departing from the spirit and scope of the invention.

Claims: CLAIMS What is claimed is : 1. Thermoset polymer foam formed by mixing polyol, foaming agent and isocyanate with a catalyst in an extruder (4) and immediately extruding the reactants wherein the filler particles comprise at least 12% by weight of the thermoset polymer foam. 2. Thermoset polymer foam according to claim 1 wherein the filler particles are chosen from a group consisting of aluminum trihydrate, perlite, carbon black, diatomaceous earth, polyiso powders, barium sulfate, calcium silicate, and calcium carbonate . 3. Thermoset polymer foam according to claim 1 wherein the filler particles comprise between 15%-20% by weight of the thermoset polymer foam. 4. Thermoset polymer foam according to claim 1 wherein the filler particles consist essentially of carbon black and aluminum trihydrate. 5. Thermoset polymer foam according to claim 1 wherein the filler particles comprise at least 15% by weight of the thermoset polymer foam and are chosen from a group consisting of aluminum trihydrate, calcium carbonate and perlite. 6. Thermoset polymer foam according to claim 1 wherein the foam is formed into bun stock. 7. Thermoset polymer foam according to claim 1 wherein the foam is formed into sheets. 8. Laminated insulation sheets comprised of the thermoset polymer foam according to claim 1 laminated between upper and lower paper liners. 9. A method for preparing a thermosetting polymer foam comprising: introducing polyol to a screw of an extruder (4) ; introducing isocyanate to the screw of the extruder; mixing the polyol and the isocyanate in the screw of the extruder; introducing foaming agent to the screw of the extruder; introducing catalyst to the screw of the extruder at a position approximate an extruding die of the extruder; mixing the catalyst with the foaming agent, the isocyanate, the polyol, the filler particles and the foaming agent in the extruder to form a composite mixture, thereby reacting the isocyanate and polyol and initiating a foaming reaction in the composite mixture in the extruder immediately before extrusion; and extruding the composite mixture so formed onto a conveyor (11) for foaming to produce thermosetting polymer foam, whereby expansion of the composite mixture into a foam takes place outside the extruder. 10. A method according to claim 9 further comprising introducing filler particles chosen from a group consisting of aluminum trihydrate, perlite, carbon black, diatomaceous earth, polyiso powders, barium sulfate, calcium silicate, and calcium carbonate to the extruder. 11. A method according to claim 10 further comprising mixing the filler particles with the isocyanate to prepare a • particle/isocyanate mixture before introducing the particle/isocyanate mixture to the screw of the extruder. 12. A method according to claim 10 further comprising mixing finely divided carbon black with the isocyanate and filler particles to form a carbon/particle/isocyanate mixture before introducing the carbon/particle/isocyanate mixture so formed to the screw of the extruder. 13. A method according to claim 9 further comprising mixing surfactant with the polyol to prepare a surfactant/polyol mixture before introducing the surfactant/polyol mixture so formed to the screw of the extruder. 14. A method according to claim 13 further comprising mixing dispersant with the polyol and surfactant to prepare a dispersant/surfactant/polyol mixture before introducing the dispersant/surfactant/polyol mixture so formed to the screw of the extruder. 15. A method according to claim 10 wherein finely divided carbon black is mixed with the filler particles to prepare a filler particle/carbon black mixture before introducing the filler particle/carbon black mixture to the screw of the extruder. 16. A method according to claim 9 wherein the foaming agent is selected from the group consisting of hydrochlorofluorocarbon (HCFC) , HC, HFC, CFC and water. 17. A method according to claim 16 wherein the foaming agent comprises water and HCFC. 18. A method according to claim 10 wherein said filler particles comprise at least 12% by weight of said thermoset polymer foam. 19. A method according to claim 10 wherein said filler particles comprise from 15-50% by weight of said thermoset polymer foam. 20. A method according to claim 10 wherein said filler particles are introduced at a first position in the extruder, a premix of said polyol and a surfactant is mixed with said filler particles at a second position in the extruder, additional polyol is mixed at a third position in the extruder downstream from said second position, said isocyanate is introduced at a fourth position in the extruder downstream from the third position, said foaming agent is introduced at a fifth position in the extruder downstream from the fourth position, and said catalyst is introduced at a sixth position downstream from said fifth position in the extruder. 21. A method according to claim 10 wherein said polyol and filler particles are added at a first position of the extruder, said isocyanate is added at a second position of the extruder, downstream of the first position, said foaming agent is added to the extruder at a third position, downstream of the second position, and said catalyst is added to the mixed polyol, filler particles, isocyanate and foaming agent at a fourth position of the extruder proximate the extrusion die to form a catalyzed mixture, and extruding the catalyzed mixture so formed for foaming. 22. A method according to claim 9 comprising cooling the composite mixture before extruding to maintain temperature below 50oC. 23. A method according to claim 9 wherein the extruder is a twin screw extruder and is operated at 300-600 rpm. 24. A method for preparing a filler particle dispersion comprising: introducing filler particles, dispersant, optional surfactant and at least one member selected from the group consisting of polyols and isocyanates to the screw of an extruder (4) , mixing in the extruder (4) and extruding the resulting filler particle dispersion. 25. A method according to claim 24 comprising mixing in the extruder sufficiently for forming a dispersion with a reading greater than 8 on the Hegman scale . AMENDED CLAIMS [received by the International Bureau on 24 April 1996 (24.04.96); original claims 1-10, 15-21 and 23-25 amended; remaining claims unchanged (6 pages)] 1. Thermoset polymer product including a foam characterized in that the foam is formed by mixing filler particles, polyol, foaming agent and isocyanate with a catalyst in an extruder (4) and immediately extruding the reactants wherein the filler particles comprise at least 12% by weight of the thermoset polymer foam. 2. Thermoset polymer product according to claim 1 characterized in that the filler particles are chosen from a group consisting of aluminum trihydrate, perlite, carbon black, diatomaceous earth, polyiso powders, barium sulfate, calcium silicate, and calcium carbonate. 3. Thermoset polymer product according to claim 1 characterized in that the filler particles comprise between 15%-20% by weight of the thermoset polymer foam. 4. Thermoset polymer product according to claim 1 characterized in that the filler particles consist essentially of carbon black and aluminum trihydrate. 5. Thermoset polymer product according to claim 1 characterized in that the filler particles comprise at least 15% by weight of the thermoset polymer foam and are chosen from a group consisting of aluminum trihydrate, calcium carbonate and perlite. 6. Thermoset polymer product according to claim 1 characterized in that the foam is formed into bun stock. 7. Thermoset polymer product according to claim 1 characterized in that the foam is formed into sheets. 8. Thermoset polymer product according to claim 1 further comprising upper and lower paper liners characterized in that said foam is laminated between said upper and said lower paper liners. 9. A method for preparing a thermosetting polymer foam characterized by: introducing polyol to a screw of an extruder (4) ; introducing isocyanate to the screw of the extruder; mixing the polyol and the isocyanate in the screw of the extruder; introducing foaming agent to the screw of the extruder; introducing catalyst to the screw of the extruder at a position approximate an extruding die of the extruder; mixing the catalyst with the foaming agent, the isocyanate, the polyol and the foaming agent in the extruder to form a composite mixture, thereby reacting the isocyanate and polyol and initiating a foaming reaction in the composite mixture in the extruder immediately before extrusion; and extruding the composite mixture so formed onto a conveyor (11) for foaming to produce thermosetting polymer foam, whereby expansion of the composite mixture into a foam takes place outside the extruder. 10. A method according to claim 9 further characterized by introducing filler particles chosen from a group including aluminum trihydrate, perlite, carbon black, diatomaceous earth, polyiso powders, barium sulfate, calcium silicate, and calcium carbonate to the screw of the extruder for inclusion in the composite mixture. 11. A method according to claim 10 further comprising mixing the filler particles with the isocyanate to prepare a particle/isocyanate mixture before introducing the particle/isocyanate mixture to the screw of the extruder. 12. A method according to claim 10 further comprising mixing finely divided carbon black with the isocyanate and filler particles to form a carbon/particle/isocyanate mixture before introducing the carbon/particle/isocyanate mixture so formed to the screw of the extruder. 13. A method according to claim 9 further comprising mixing surfactant with the polyol to prepare a surfactant/polyol mixture before introducing the surfactant/polyol mixture so formed to the screw of the extruder. 14. A method according to claim 13 further comprising mixing dispersant with the polyol and surfactant to prepare a dispersant/surfactant/polyol mixture before introducing the dispersant/surfactant/polyol mixture so formed to the screw of the extruder. 15. A method according to claim 10 characterized in that finely divided carbon black is mixed with the filler particles to prepare a filler particle/carbon black mixture before introducing the filler particle/carbon black mixture to the screw of the extruder. 16. A method according to claim 9 characterized in that the foaming agent is chosen from the group consisting of hydrochlorofluorocarbon (HCFC) , HC, HFC, CFC and water. 17. A method according to claim 16 characterized in that the foaming agent comprises water and HCFC. 18. A method according to claim 10 characterized in that said filler particles comprise at least 12% by weight of said thermoset polymer foam. 19. A method according to claim 10 characterized in that said filler particles comprise from 15-50% by weight of said thermoset polymer foam. 20. A method according to claim 10 characterized in that said filler particles are introduced at a first position in the extruder, a premix of said polyol and a surfactant is mixed with said filler particles at a second position in the extruder, additional polyol is mixed at a third position in the extruder downstream from said second position, said isocyanate is introduced at a fourth position in the extruder downstream from the third position, said foaming agent is introduced at a fifth position in the extruder downstream from the fourth position, and said catalyst is introduced at a sixth position downstream from said fifth position in the extruder. 21. A method according to claim 10 characterized in that said polyol and filler particles are added at a first position of the extruder, said isocyanate is added at a second position of the extruder, downstream of the first position, said foaming agent is added to the extruder at a third position, downstream of the second position, and said catalyst is added to the mixed polyol, filler particles, isocyanate and foaming agent at a fourth position of the extruder proximate the extrusion die to form a catalyzed mixture, and extruding the catalyzed mixture so formed for foaming. 22. A method according to claim 9 comprising cooling the composite mixture before extruding to maintain temperature below 50°C. 23. A method according to claim 9 characterized in that the extruder is a twin screw extruder and is operated at 300- 600 rpm. 24. A method for preparing a filler particle dispersion characterized by: introducing filler particles, dispersant, optional surfactant and at least one member selected from the group consisting of polyols and isocyanates to the screw of an extruder (4) , mixing in the extruder (4) and extruding the resulting filler particle dispersion. 25. A method according to claim 24 characterized in that the dispersion is mixed in an extruder sufficiently such that the filler particles are dispersed to exceed 8 on the Hegman scale.

Inventors: BURGESS JAMES H, GLORIOSO SAMMIE J, BURGESS, JAMES, H., GLORIOSO, SAMMIE, J.
Applicants: APACHE PROD CO, APACHE PRODUCTS COMPANY
Application year: 1995
Main classification: C08G18
IPC codes: B29C44, B29C47, B29K75, B29K105, B29L7, C08G18, C08G101, C08J9, C08K3