Structural mat matrix

Details Structural mat matrix Structural mat matrix

2000-09-07

2001-11-13

Dixon, Merrick (Department: 1774)

Stock material or miscellaneous articles

Structurally defined web or sheet

Physical dimension specified

C428S459000, C428S219000

Reexamination Certificate

active

06316085

ABSTRACT:

BACKGROUND OF INVENTION
This invention relates to a structural mat matrix such as a roofing shingle mat matrix.
For many years, structural articles such as roofing shingles have been comprised of fiberglass substrates coated with a binder which bonds together the fiberglass substrate fibers. Such substrates are nonwoven fiberglass mats which are desirable because they are lighter in weight than previously used mats. Fiberglass mats have also been preferred as roofing shingle substrates because of their fire resistant nature, their resistance to moisture damage, their excellent dimensional stability, their resistance to curl with temperature changes, their resistance to rot and decay, and their ability to accept more highly filled asphalt coatings.
Heretofore, efforts to optimize fiberglass roofing shingle substrates have focused on attempts at improving their tear strength and tensile strength without unduly increasing the weight of the shingle. Heavier shingles and other structural articles are generally more expensive because of greater raw material and transportation costs. Operating within such weight/cost constraints, shingle manufacturers have found that, to improve tear strength, they had to sacrifice tensile strength and vice versa.
U.S. Pat. No. 4,112,174 discloses a mat suitable in the manufacture of roofing products which includes monofilament glass fibers, glass fiber bundles and a relatively small amount of binder, e.g. binder which is 15% by dry weight of the mat. The mat has a weight of between approximately 2.00 and 2.40 lbs/100 square feet. U.S. Pat. No. 4,242,404 discloses a glass fiber mat useful for roofing products which includes individual filament glass fibers and extended glass fiber elements and a binder applied in an amount of about 3% to 45% by weight of the finished mat. The basis weight of the finished mat is described as being at least 1 lb./100 sq. ft and preferably about 2.0 to 3.0 lbs/sq. ft.
U.S. Pat. No. 4,472,243 discloses sheet type roofing material for use in built-up roofing and in the manufacture of roofing shingles. Chopped glass fibers are dispersed in a slurry of cellulosic fibers and binder is added. According to the patent, the material comprises 10-60 wt % glass fibers of varying lengths, 15-80% wt % cellulosic fiber and 5-25% binder. The patent states that the proportions and sizes of cellulosic and glass fibers described therein “provide the desired balance of structural properties” in the material to render it “suitable as substrate for roofing material” to “meet the desired standards for mechanical strength and fire resistance.” The patent further notes that the “[g]lass fiber content of the felt of the invention is important in controlling its porosity and skeletal structure. On the high end of glass fiber content the felt substrate tends to be porous with a high order of skeletal structure. Such a felt will uncontrollably absorb excessive amounts of asphaltic saturant at a very high rate during roofing shingle processing and this has a deleterious effect in the spread of flame test due to severe asphaltic filled coating slides.”
Surprisingly, the applicant has found that by producing a mat having a relatively high fiberglass content and relatively low cellulosic component and binder contents, the mat matrix has the same physical properties (such as tensile strength) of more costly heavy weight mats, with substantially increased tear strength.
SUMMARY OF THE INVENTION
The present invention is a structural mat matrix which comprises (a) a substrate which consists essentially of from 80% to 99% by weight fiberglass fibers and from 20% to 1% by weight wood pulp and (b) a binder which bonds together the fiberglass fibers and the wood pulp. The binder consists essentially of from 80% to 95% by weight urea formaldehyde resin and from 20% to 5% by weight acrylic copolymer. The binder comprises from 5% to 15% by weight of the matrix, preferably 10%.
In a preferred embodiment, (a) the substrate consists essentially of 95% by weight fiberglass and 5% by weight wood pulp and (b) the binder consists essentially of 90% by weight urea formaldehyde resin and 10% by weight acrylic copolymer.
DETAILED DESCRIPTION
Structural articles of the present invention are useful as, inter alia. roofing shingle mats, built-up roofing mats, facer mats and base plysheets. Articles produced in accordance with the invention are lighter in weight yet possess the same physical properties of tearing strength, tensile strength, wet tensile strength, porosity, and bursting strength as their prior art counterparts. Moreover, the applicant's inventive structural mat matrices achieve those results with lower raw material costs.
The structural mat matrices of the present invention comprise (a) a substrate which consists essentially of from 80% to 99% by weight fiberglass fibers and from 20% to 1% by weight wood pulp and (b) a binder which consists essentially of from 80% to 95% by weight urea formaldehyde resin and from 20% to 5% by weight acrylic copolymer. The fiberglass fibers which may be used in the substrate of the invention include wet chopped, 1″ to 1½ ″length, 14 to 18 micron diameter fibers which may be obtained from Owens Corning Fiberglas, Schuller and PPG Industries, Inc. The wood pulp may be cellulose fibers, cellulose pulp, Kraft pulp, hardwood and softwood pulps which may be obtained from, e.g. International Paper Co., Rayonier, James River and Weyerhaeuser and other market pulp manufacturers.
The urea formaldehyde resin in the binder may be a latex of about 60% solids, such as Casco Resin C511 or Casco Resin FG-413F which may be obtained from Borden Chemical, Inc.. The acrylic copolymer may be vinyl acrylic copolymer of about 49% solids such as Franklin International Covinax 830 or Rohm and Haas Rhoplex GL-618. In a preferred embodiment, the binder comprises 10% by weight of the matrix.
Structural mat matrices made in accordance with this invention may be of any shape and may be used in a variety of products including roofing shingles, built-up roofing, facers, etc. Preferably, such matrices are planar in shape.
Additionally, the structural matrices may be coated with a water repellant material. Two such water repellant materials are Aurapel 33R or Aurapel 391 available from the Auralux Corporation of Norwich, Conn. Further, structural matrices made in accordance with the invention may be coated with an antifungal material such as Micro-Chek 11P, an antibacterial material such as Micro-Chek 11-S-160, a surface friction agent such as Byk-375, and/or a coloring dye such as T-1133 A.
The materials used in the making of the matrices and the methods of their preparation are described respectively in the following trade literature: International Paper ALBACEL product literature for bleached southern pine pulp available from International Pulp Sales, 2 Manhattanville Rd., Purchase, N.Y. and International Paper SUPERCELL AO-2 product literature 0047-3/97 for fully bleached hardwood kraft pulp available from International Pulp Sales, 1290 Avenue of the Americas, New York, N.Y.; Owens Coming Product Bulletin 786 WUCS (Wet Use Chopped Strands) c. 1995 Owens Corning World Headquarters, Fiberglas Tower, Toledo, Ohio; PPG 8239 WET CHOPPED STRAND bulletin 2.3.1, Revised 2/95, PPG Fiberglass Products, One PPG Place, Pittsburgh, Pa.; Borden Casco Resin C511 DATA SHEET TDS XA-C511 06/97 and Resin FG-413F DATA SHEET TDS XA-413F 11/96, North American Resins Worldwide Packaging and Industrial Products (Div. of Borden Inc.) 520 112
th
Ave., N.E. Bellevue, Wash.; Franklin International Covinax 830 Data Sheet Mar. 20, 1995, Franklin International, 2020 Bruck Street, Columbus, Ohio; Rohm and Haas Rhoplex GL-618 product literature 20N2, September 1994, Rohm and Haas Co., Charlotte, N.C. The disclosures of each of the aforementioned trade publications are incorporated herein by reference.


REFERENCES:
patent: 3841885 (1974-10-01), Jakel
patent: 3954555 (1976-05-01), Kole et al.
patent: 4112174 (1978-09-01), Hannes et al.
patent: 4118272 (197

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