CPC D21H 21/16 (2013.01) [D21H 11/14 (2013.01); D21H 17/35 (2013.01); D21H 17/37 (2013.01); D21H 19/20 (2013.01); D21H 19/22 (2013.01); D21H 19/56 (2013.01); D21H 19/84 (2013.01)] | 15 Claims |
1. A recyclable sheet comprising:
a substrate consisting of a 24 pound short fiber recycled paper;
a coating layer formed by directly contacting and impregnantly covering at least one of the two sides of the substrate with a mixture comprising a styrene acrylic polymer and 3 wt % of a methylene diphenyl diisocyanate and polypropylene ether glycol based prepolymer as a cross-linking agent and having a viscosity less than 1900 cP after 7 hours of mixing; and
cross-links between:
i) a plurality of cellulose fibers;
ii) a plurality of cellulose fibers and the styrene acrylic polymer; and
iii) styrene acrylic polymer molecules,
wherein the degree of cross-linking is controlled such that the recyclable sheet having the cross-links is recyclable and has a wet strength of at least 2300 newtons and maintains a writability score of 9 on a scale of 0-10 after getting wet without ink feathering or paper tearing, wherein 0 denotes unacceptable writability and 10 denotes no wicking, smearing, or paper ripping during writing based on a test using oil based ink from a ballpoint pen.
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11. A method for forming a recyclable sheet, the method comprising:
i. providing a substrate consisting of a 24 pound short fiber recycled paper; and
ii. contacting the substrate with a composition comprising a mixture of styrene acrylic polymer and 3 wt % of a methylene diphenyl diisocyanate and polypropylene ether glycol based prepolymer as a cross-linking agent and having a viscosity less than 1900 cP after 7 hours of mixing thereby forming:
a) a coating layer; and
b) cross-links between:
i) a plurality of cellulose fibers;
ii) a plurality of cellulose fibers and the styrene acrylic polymer; and
iii) styrene acrylic polymer molecules,
wherein the degree of cross-linking is controlled such that the recyclable sheet having the cross-links is recyclable and has a wet strength of at least 2300 newtons and maintains a writability score of 9 on a scale of 0-10 after getting wet without ink feathering or paper tearing, wherein 0 denotes unacceptable writability and 10 denotes no wicking, smearing, or paper ripping during writing based on a test using oil based ink from a ballpoint pen.
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