US 11,814,795 B2
Coating for recyclable paper
John T. Mattingly, Fox Island, WA (US); and Paul Snowwhite, Dexter, MI (US)
Assigned to JL Darling LLC, Tacoma, WA (US)
Filed by JL Darling LLC, Tacoma, WA (US)
Filed on Apr. 2, 2018, as Appl. No. 15/942,906.
Claims priority of provisional application 62/481,009, filed on Apr. 3, 2017.
Prior Publication US 2018/0282947 A1, Oct. 4, 2018
Int. Cl. D21H 21/16 (2006.01); D21H 19/22 (2006.01); D21H 19/84 (2006.01); D21H 19/20 (2006.01); D21H 11/14 (2006.01); D21H 17/37 (2006.01); D21H 17/35 (2006.01); D21H 19/56 (2006.01)
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
OG exemplary drawing
 
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.
 
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.