Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reissue Patent
1999-05-04
2001-03-13
Foelak, Morton (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C264S045300, C264S045900, C264S051000, C264S053000, C521S155000, C521S917000
Reissue Patent
active
RE037095
ABSTRACT:
BACKGROUND OF THE INVENTION
1. 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.
2. Description of the Prior Art
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. Pat. 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 foam-augmenting gas such as Freon is used as the foaming agent. Richie uses an expansion space of transverse cross-sectional area which increases in size gradually in the direction of travel of the extruded product.
U.S. Pat. No. 5,149,722 (Soukup) and U.S. Pat. No. 4,795,763 (Gluck) describe 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 conjunction with extrusion proximate the extruder head, either in the last extruder barrel or the extruder head itself as a final mixing step. After the catalyst is introduced, the mixture immediately exits the extruder onto a conveyor so that the foaming and 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. Paper liners may be applied to both sides of the foam as it travels on the conveyor.
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. Ammonium phosphate can improve flame-retardant properties. Overall, the addition of filler particles makes 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, ammonium phosphate and calcium carbonate are preferred filler materials, used either as the sole filler material or with carbon black. Other filler materials include carbon black, fly ash, diatomaceous earth, polyiso powder, barium sulfate, melamine 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.
Ammonium phosphate is also useful as a filler particle. This includes ammonium phosphate and ammonium polyphosphate compounds, including ammonium phosphate, primary ammonium phosphate, secondary ammonium phosphate and other like phosphate compounds. Monobasic ammonium phosphate has been found especially useful as a filler particle.
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. Preferably, the filler particles have a Tyler Mesh size of 20 or smaller where only about 4% of the filler is 20 mesh. More preferably, the size of the filler particles are between 50-300 mesh, and most preferably 80-300 mesh.
The foaming agent, which is preferably a hydrochlorofluorocarbon (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 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 7 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 single-screw or 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.
REFERENCES:
patent: 3466705 (1969-09-01), Richie
patent: 3625872 (1971-12-01), Ashida
patent: 3892686 (1975-07-01), Woo
patent: 3933701 (1976-01-01), Puig et al.
patent: 4046849 (1977-09-01), Lever et al.
patent: 4094829 (1978-06-01), Shearing
patent: 4097400 (1978-06-01), Wortmann et al.
patent: 4129693 (1978-12-01), Cenker et al.
patent: 4153764 (1979-05-01), Blount
patent: 4165411 (1979-08-01), Marans et al.
patent: 4284826 (1981-08-01), Aelony
patent: 4307203 (1981-12-01), Blount
patent: 4341876 (1982-07-01), Kreuer et al.
patent: 4349494 (1982-09-01), Fulmer
patent: 4377646 (1983-03-01), Blount
patent: 4395214 (1983-07-01), Phipps et al.
patent: 4451583 (1984-05-01), Chesler
patent: 4504603 (1985-03-01), Hicks
patent: 4506040 (1985-03-01), Raes et al.
patent: 4551483 (1985-11-01), Hicks
patent: 4569952 (1986-02-01), Radovich et al.
patent: 4597927 (1986-07-01), Zeitler et al.
patent: 4607
Burgess James H.
Glorioso Sammie J.
Apache Products Company
Foelak Morton
Volpe and Koenig P.C.
LandOfFree
Extruded polymer foam with filler particles and method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Extruded polymer foam with filler particles and method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Extruded polymer foam with filler particles and method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2462058