Weatherproof sheets for copying, printing and writing and methods related thereto
Weatherproof sheets, suitable for conventional printing, writing, photocopying, and laser printing, are prepared by impregnantly coating a cellulosic substrate on at least one side with a durable weatherproofing composition that is water-based. The composition that is used for general-purpose weatherproof sheets comprises a styrenic acrylic copolymer, a wax, a filler for blocking resistance, a filler for tooth, and a pigment. The preparation of all-purpose weatherproof sheets, usable in photocopiers and laser printers, is made possible by substantially omitting calcium carbonate and titanium dioxide from the composition. The weatherproof sheets resist falling apart, remain legible, and can be written upon when wet. They are also non-yellowing, biodegradable and recylclable. Also, disclosed are methods for making the weatherproof sheets, as well as weatherproof sheets made by those methods.
1. A weatherproof sheet suitable for use in a photocopier or laser printer and capable of fixedly and legibly bearing images printed directly thereon by means of the photocopier or laser printer, the weatherproof sheet comprising:
a cellulosic substrate having two substantially planar sides; and
a durable weatherproofing coating layer, in direct contact with and impregnantly covering at least one of the two sides of the substrate, the coating layer penetrating the surface of the at least one of the two sides of the substrate, wherein the coating layer comprises a copolymer or mixture of copolymers derived from at least one styrene or styrenic monomer and at least one acrylic monomer, a wax, a filler to provide block resistance, a filler to provide tooth for printability and writability, a pigment, and an optical brightener; with the proviso that the coating layer comprises substantially no calcium carbonate filler and substantially no titanium dioxide pigment.
2. The weatherproof sheet of claim 1 wherein the copolymer or mixture of copolymers is derived from monomers selected from the group consisting of styrene, butyl acrylate, 2-ethylhexyl acrylate, acrylic acid, and a mixture thereof.
3. The weatherproof sheet of claim 1 wherein the mixture of copolymers is an acrylic or styrene acrylic emulsion.
4. The weatherproof sheet of claim 1 wherein the weight of the coating layer ranges from about 3.7 grams to about 5.6 grams per square meter of cellulosic substrate surface area covered.
5. The weatherproof sheet of claim 1 wherein, based on the total weight of the coating layer and the coating layer having a moisture content of 5 percent by weight, the amount of the copolymer or mixture of copolymers ranges from about 30 percent to about 82 percent, and the amount of the wax ranges from about 1.5 percent to about 13 percent.
6. The weatherproof sheet of claim 1 wherein, based on the total weight of the coating layer and the coating layer having a moisture content of 5 percent by weight, the amount of the copolymer or mixture of copolymers is about 52.5 percent, and the amount of the wax is about 2.7 percent.
7. The weatherproof sheet of claim 1 wherein the filler to provide block resistance comprises barium sulfate, the filler to provide tooth for printability and writability comprises barium sulfate, and the pigment comprises barium sulfate.
8. The weatherproof sheet of claim 7 wherein the amount of the barium sulfate ranges from 0 percent to about 65 percent, based on the total weight of the coating layer and the coating layer having a moisture content of 5 percent by weight.
9. The weatherproof sheet of claim 7 wherein the amount of the barium sulfate is about 38 percent, based on the total weight of the coating layer and the coating layer having a moisture content of 5 percent by weight.
10. The weatherproof sheet of claim 1 wherein the filler to provide block resistance is clay, mica, aluminum trihydrate, or a mixture thereof.
11. The weatherproof sheet of claim 1 , further comprising an additive to enhance the wet strength of the cellulosic substrate.
12. The weatherproof sheet of claim 11 wherein the additive comprises polyamide.
13. The weatherproof sheet of claim 1 wherein the wax is paraffin wax, a polypropylene-wax mixture, a polyethylene-wax mixture, carnauba wax, microcrystalline wax, montan wax, a Fisher-Tropsch wax, beeswax, or a mixture thereof.
14. The weatherproof sheet of claim 1 wherein the coating layer further comprises a color tinting agent comprising an organic or inorganic pigment dispersed in an acrylic resin or other suitable media.
15. The weatherproof sheet of claim 1 wherein the coating layer further comprises water and wherein the moisture content associated therewith ranges from about 4 percent to about 7 percent by weight of the weatherproof sheet.
16. The weatherproof sheet of claim 1 wherein the coating layer is a compounded acrylic.
17. The weatherproof sheet of claim 1 wherein the cellulosic substrate is paper comprising cellulosic fibers.
18. The weatherproof sheet of claim 17 wherein the thickness of the paper ranges from 0.003 inches to 0.013 inches.
19. The weatherproof sheet of claim 17 wherein the thickness of the paper ranges from about 0.004 inches to about 0.006 inches.
20. The weatherproof sheet of claim 19 having dimensions of an architectural or construction drawing.