US 3866373 A
A pultruded shape containing hollow glass or ceramic spheres, a solventless resin, and glass roving or cloth. The shape has very low thermal conductivity and is light weight. It is particularly useful as a window sash.
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United States Patent Hudock Feb. 18, 1975 1 PULTRUDED SHAPES CONTAINING 3,100,917 8/1963 Wagner 52/309 HOLLOW GLASS CERAMIC SPHERES 3,316,139 4/1967 Alford et a1. l61/D1G. 5 3,321,414 5/1967 Vieli 161/168 X ento John 5. Hudock, Greensburg, Pa. 3,412,185 11/1968 KlEIlZle 264/338 x D 3,427,267 2/1969 Stieger et al 161/169 X Amgnee' Westmghwse Elem Corporatmn 3,709,773 1/1973 11611 ..161/170x Plttsburgh, Pa.  Filed, July 6 1972 FOREIGN PATENTS OR APPLICATIONS 1,002,243 8/1965 Great Britain 52/202 1 1 pp 269,337 511,007 1/1955 llflly 52/475 568,336 10/1957 ltaly 52/474  U S Cl 52/309 52/495 52/738 287,327 2/1965 Netherlands 52/475 161/168 51 1m. 01. E040 2/38 Fawv  Field 61 Search 52/309, 202, 400, 474, Attorney Fuerle 52/475, 495, 627, 738, 627, 738, 495; 161/168, 170, 204. D10. 4, D16. 5; 57 ABSTRACT A pultruded shape containing hollow glass or ceramic  References Cited spheres, a solventless resin, and glass roving or cloth. The shape has very low thermal conductivity and is UNITED STATES PATENTS light weight. It is particularly useful as a window sash. 2,825,941 3/1958 Lux et al 52/400 X 3,086,898 4/1963 Alford et a1. 161/168 7 Claims, 1 Drawing Figure PULTRUDED SHAPES CONTAINING HOLLOW GLASS OR CERAMIC SPHERES BACKGROUND OF THE INVENTION In making pultruded shapes glass roving or cloth is pulled through a resin bath then through a die of the shape desired. If the resin is thermosetting the die is heated so that the resin is cured in the die and the shape is solid when it emerges from the die. If the resin is thermoplastic the bath is heated to melt the, resin in it and the die is cooled so that the shape is solid when it emerges from the die. Pultrusion offers the advantages of producing endless shapes of great flexural strength quickly and inexpensively since dies can be machined fairly easily. However, in spite of these desirable properties efforts to make pultruded window sashes have not produced satisfactory results in that the sashes frequently sweat (i.e., water vapor condenses on them), even when the glass pane does not sweat.
SUMMARY OF THE INVENTION I have found the sweating of window sashes and other pultruded shapes can be greatly reduced or even eliminated if a portion of the glass cloth or roving used in making the shape is replaced with hollow glass or ceramic spheres. The pultruded shapes of this invention retain most of the desirable flexural strength and ease of manufacture of the prior art shapes, but, in addition, are light weight and have very low thermal conductivities.
DESCRIPTION OF THE INVENTION The accompanying drawing is an isometric view in section of a certain presently preferred window sash according to this invention.
In the drawing the sash 1 has two arms 2 and 3 which clasp an insulating window glass 4, which is formed from two sheets of glass 5 and 6 fused together at 7 and having air space 8 inbetween. Putty 9 seals the glass 4 to the sash. The sash has a cavity 10 to reduce weight and increase the insulating properties of the sash. Below cavity 10 are two extensions 11 and 12 which hold a sealing strip 13, usually of vinyl. A leg 14 hides the strip and acts as an additional seal.
While a window sash is the preferred shape since it makes the best use of the properties of the shapes of this invention, other shapes including bars, rods, tubes, etc. are also contemplated.
The resin composition includes any solventless resin, such as polyesters, epoxies, acrylics, acrylicepoxies, vinyls, etc. Thermosetting resins are preferred as they have been found to work quite well, and of the thermosetting resins polyester resins are preferred as they are least expensive. If the resin is thermosetting a catalyst must be included, as is well known, to initiate the cure. The catalyst is typically about to about 2 percent (based on the resin) but amounts vary with the particular catalyst and resin used. Preferably included in the composition is about I to about 5 percent (based on the resin all percentages herein are by weight) of an internal mold release, such as zinc stearate, which migrates to the surface and prevents the shape from sticking to the die. Optional ingredients include dyes, reactive diluents such as styrene, and free radical scavangers such as hydroquinone and its derivatives.
The glass must be roving or cloth in order to pull it through the die, but up to about 75 percent of the glass may be mat to strengthen the shape in the crossdirection and, if the mat is external, to provide a resinrich surface which increases the weatherability of the shape. A typical bundle of glass roving may have about 8 to about 60 strands, each of which contains about 400 fibers about 0.00052 inches in diameter. Mixtures of roving and cloth may also be used, but roving is preferred to cloth for window sashes as it is easier to work with.
The hollow glass or ceramic spheres are typically about 10 to about 300p. m in diameter, and are preferably less than about 500p. m in diameter as larger sizes may collapse under the die pressure and make the surface of the shape rough. Mixtures of glass and ceramic spheres may also be used. Glass spheres are preferred because they are less expensive.
The pultruded shape contains about 30 to about 80 percent glass roving or cloth (a portion of which is replaced by the hollow glass or ceramic spheres) and about 20 to about percent solventless resin composition. If less than about 30 percent glass is used the shape is too weak and if more than percent glass is used the shape is too thermally conductive. The best combination of high flexural strength and low thermal conductivity is obtained at about 40 to about 65 percent glass and about 35 to about 60 percent resin composition.
Glass roving or cloth equal to about 1 to about 10 percent of the shape is replaced with sufficient hollow glass or ceramic spheres to occupy the same amount of space. Preferably the space occupied by glass roving or cloth equal to about 3 to about 6 percent of the sash is replaced with hollow glass or ceramic spheres since at less than about 3 percent the effect on the thermal conductivity of the shape is significantly less and at more than 6 percent the spheres make the resin composition viscous and difficult to pultrude.
EXAMPLES The following examples further illustrate this invention.
The hollow glass spheres used in these examples are sold by Emerson & Commings, Inc. under the trademark Eccospheres. They have a bulk density of 14 lbs/cu.ft. (0.22 gms/cc), a true particle density (liquid displacement of 20 lbs/cu.ft. (0.33 gms/cc.), a particle size of 10 to 250p m, and a wall thickness of 2p. m, a temperature capability of 900F, and a thermal conductivity of 0.45 Btu/hr/F/sq.ft./in.
The roving in experiments 1 and 2 was 52 bundles of 60 strands each and the roving in experiments 3 and 4 was 40 bundles of 60 strands each.
The following resin composition and resin compositions containing hollow glass spheres were prepared: Composition I (Control) 18 lbs polyester resin sold by Koppers Co. under the trademark Koplac 1000-25 25 lbs CaCO (thickener) 2.0 lbs TiO (whitener) 0.2 lbs benzoyl peroxide (catalyst) 0.8 lbs zinc stearate (mold release) 5.0 lbs styrene (reactive diluent) Composition II 30 lbs Koplac 1000-25 polyester resin 0.2 lbs benzoyl peroxide 0.1 lbs mold release sold by DuPont Co. under the trademark Zelec UN 0.75 lbs styrene 2.0 lbs Eccospheres hollow glass spheres Composition Ill 20 lbs Koplac 1000-25 polyester resin 4 elongated extensions adjacent said leg for holding a sealing strip, said sash being constructed of materials comprising I 1. about 35 to about 60 percent solventless polyester lbs benzoyl Peroxlde resin composition about /2 to about 2 percent of 0.1 lbs Zelec UN mold release which is a catalyst, g'g ltl i h h n l h 2. about 1 to about 5 percent internal mold release, S CCOSP eras 0 0w g ass SP eres 3. about 40 to about 65 ercent lass material se- Glass roving was pulled at 5 inches/min through resin lected from the group cgnsisfinggof roving Cloth baths of the various resin compositions at room and mixtures thereof 1' a II giggg ggfg g% gg 2 4. hollow spheres selected from the group consisting dimensions. The density and thermal conductivity ofhglass cerzllmlc and i i t i (crosswise direction) of the bars were determined. Sp i ace a T; Sal g 2 g g The following are the results: .59.? g B 3 to a l percent 0 sas Percentage Experiment Resin Hollow Density Thermal Conductivity Number Composition Composition Roving Spheres gms/cu Btu/hr/ft /F/in.
l I 25.7 48.6 1.99 4.23 2 ll 35.5 61.0 3.5 L67 2.50 3 ll 46.] 49.3 4.6 1.43 1.87 4 lll 49.7 47.8 2 5 1.46 2.01
The above table shows that the small percentage of 2. A pultruded window sash according to claim 1 hollows spheres used substantially reduced the thermal wherein said mold release is zinc stearate.
conductivity, in experiments 3 and 4 by more than half.
In another experiment the window sash of the drawing was made by pulling 48 bundles of 60 strands each of glass roving through Composition ll at 5 inches/min then through a die heated to 250F. The resulting sash contained 50.8 percent roving, 44.7 percent resin composition, and 4.4 percent hollow glass spheres.
3. A pultruded window sash according to claim 1 wherein said catalyst is benzoyl peroxide.
4. A pultruded window sash according to claim I wherein all of said glass material not replaced by hollow spheres is roving.
5. A pultruded window sash according to claim 1 wherein said hollow spheres have a diameter of about 10 to 300 pm.
6. A pultruded window sash according to claim 1 including a sealing strip held between said two substantially parallel elongated extensions.
7. A pultruded window sash according to claim 1 including two sheets of glass fused together held between said two substantially parallel elongated arms.