Electrophotographic recording medium and method
View Patent ↗A recording medium particularly suitable for electrophotographic copying is characterized by coated paper that for a given basis weight has proportionally less coating and proportionally more fiber than conventional coated paper made for electrophotographic processes. The base sheet of the coated paper is preferably formed square on a paper machine wet end and has on the order of 40-50% less filler than conventional sheet paper made for electrophotographic processes. After being formed and dried, the base sheet is provided with a top coat weight that is approximately 60% less than the typical coat weight used for conventional paper. The coating is formulated to have sufficient viscosity to stay more on the surface of the base sheet. The coated sheet is calendered to a medium gloss on the order of a 75° TAPPI gloss of about 45, both to preserve a degree of surface roughness to enhance runnability of the paper through an electrophotographic copier and to provide a pleasant and easily readable surface. In improving on conventional paper, the paper of the invention provides for good fusion of dried toner on the paper at marginal lower temperatures.
1. A process for making a coated paper adapted to provide improved fusion of toner on a surface thereof at marginal fusion temperatures in an electrophotographic process, comprising the steps of providing a waterborne furnish containing fiber; extruding the furnish onto a wire of a paper machine to form a paper web; pressing excess water from the web; drying the web to a moisture content less than 10%; coating each side of the paper web with a coat weight that is on the order of 2.5-5.5 pounds per side per ream; and calendering the coated paper web, said extruding and coating steps being controlled so that the coated paper has a basis weight of at least 60 pounds per ream and a coating weight/fiber weight ratio on the order of 6 %- 31 %.
2. A process as in claim 1 , wherein said coating step applies a coat weight on the order of 3.5-4.0 pounds per side per ream.
3. A process as in claim 1 , wherein said calendering step calenders the coated paper to a 75° TAPPI gloss of 35-50.
4. A process as in claim 1 , wherein said calendering step calenders the coated paper to a 75° TAPPI gloss of about 45.
5. A process as in claim 1 , wherein said extruding and coating steps are controlled so that the coated paper has a basis weight in the range of about 60-110 pounds per ream.
6. A process as in claim 1 , wherein said extruding and coating steps are controlled so that the coated paper has a basis weight of about 60 pounds per ream and a coating weight/basis ratio on the order of 8%-18%.
7. A process as in claim 1 , wherein said extruding and coating steps are controlled so that the coated paper has a basis weight of about 70 pounds per ream and a coating weight/basis weight ratio on the order of 7%-16%.
8. A process as in claim 1 , wherein said extruding and coating steps are controlled so that the coated paper has a basis weight of about 80 pounds per ream and a coating weight/basis weight ratio on the order of 6%-14%.
9. A process as in claim 1 , wherein said extruding and coating steps are controlled so that the coated paper has a basis weight of about 110 pounds per ream and a coating weight/basis weight ratio on the order of 4%-10%.
10. A process as in claim 1 , wherein said extruding and coating steps are controlled so that the coated paper has a coating weight/basis weight ratio of 33% -59% of the coating weight/basis weight ratio of conventional coated gloss paper for a given basis weight.
11. A process as in claim 1 , wherein said providing step provides a waterborne furnish containing fiber and said extruding and coating steps are controlled so that the coated paper has a basis weight of about 60 pounds per ream and a coating weight/fiber weight ratio on the order of 12%-31%.
12. A process as in claim 1 , wherein said providing step provides a waterborne furnish containing fiber and said extruding and coating steps are controlled so that the coated paper has a basis weight of about 70 pounds per ream and a coating weight/fiber weight ratio on the order of 10%-25%.
13. A process as in claim 1 , wherein said providing step provides a waterborne furnish containing fiber and said extruding and coating steps are controlled so that the coated paper has a basis weight of about 80 pounds per ream and a coating weight/fiber weight ratio on the order of 8%-21%.
14. A process as in claim 1 , wherein said providing step provides a waterborne furnish containing fiber and said extruding and coating steps are controlled so that the coated paper has a basis weight of about 110 pounds per ream and a coating weight/fiber weight ratio on the order of 6%-14%.
15. A process as in claim 1 , wherein said providing step provides a waterborne furnish containing fiber and said extruding and coating steps are controlled so that the coated paper has a coating weight/fiber weight ratio that is on the order of 27%-52% of the coating weight/fiber weight ratio of conventional coated gloss paper for a given basis weight.
16. A process as in claim 1 , wherein said providing step provides furnish that forms a paper web having on the order of 7%-15% filler.
17. A process as in claim 1 , wherein said providing step provides furnish that forms a paper web having on the order of 40%-50% less filler than is contained in a conventional paper web.
18. A process as in claim 1 , including the step, prior to said coating step, of applying a precoat of lightly pigmented coating on each side of the paper web at a weight on the order of 1-2.5 pounds per side per ream.
19. A process as in claim 1 , wherein said providing step provides furnish that is substantially groundwood free.
20. A process as in claim 1 , wherein said providing step provides a furnish containing groundwood free high brightness bleached pulp.
21. A process for adhering toner to a coated paper, comprising the steps of providing a coated paper having a paper base containing fiber and a coating on each side of the base, the coating being of a weight on the order of 2.5-5.5 pounds per side per ream and the coated paper having a basis weight of at least 60 pounds per ream and a coating weight/fiber weight ratio on the order of 6 %- 31 %; attracting toner to a surface of the coated paper; and, while the toner is attracted to the surface of the coated paper, subjecting the coated paper and toner to heat sufficient to melt and fuse the toner to the surface of the coated paper.
22. A process as in claim 21 , wherein said providing step provides a coated paper that is calendered to a 75° TAPPI gloss of 35-50.
23. A process for making a coated paper adapted to provide improved function of toner on a surface thereof at marginal fusion temperatures in an electrophotographic process, comprising the steps of providing a waterborne furnish containing fiber; extruding the furnish onto a wire of a paper machine to form a paper web; pressing excess water from the web; drying the web to a moisture content less than 10%; coating each side of the paper web with a coat weight that is on the order of 2.5-5.5 pounds per side per ream; said extruding and coating steps being controlled so that the coated paper has a basis weight of at least 80 pounds per ream and a coating weight/fiber weight ratio on the order of 5 %- 31 %.
24. A process as in claim 23 , wherein said extruding and coating steps are controlled so that the coated paper has a basis weight of at least 110 pounds per ream.
25. A process as in claim 23 , including the step of calendering the coated paper to a 75° TAPPI gloss on the order of 35-50.
26. A process as in claim 23 , wherein said extruding and coating steps are controlled so that the coated paper has a coating weight/basis weight ratio on the order of 3%-10%.
27. A process as in claim 23 , wherein said providing step provides a waterborne furnish containing fiber and said extruding and coating steps are controlled so that the coated paper has a coating weight/fiber weight ratio on the order of 5%-31%.
28. A process as in claim 23 , wherein said providing step provides furnish that forms a paper web having on the order of 7%-15% filler.
29. A process as in claim 23 , including the step, prior to said coating step, of applying a precoat of lightly pigmented coating on each side of the paper web at a weight on the order of 1-2.5 pounds per side per ream.
30. A process as in claim 23 , wherein said providing step provides furnish that is substantially groundwood free.
31. A process as in claim 23 , wherein said providing step provides a furnish containing groundwood free high brightness bleached pulp.
32. A process for making a coated paper adapted to provide improved fusion of toner on a surface thereof at marginal fusion temperatures in an electrophotographic process, comprising the steps of providing a waterborne furnish containing fiber; extruding the furnish onto a wire of a paper machine to form a paper web; pressing excess water from the web; drying the web to a moisture content less than 10%; coating each side of the paper web with a coat weight that is at least 5 pounds per side per ream; said extruding and coating steps being controlled so that the coated paper has a basis weight of at least 80 pounds per ream and a coating weight/fiber weight ratio on the order of 5 %- 31 %.
33. A process as in claim 32 , wherein said extruding and coating steps are controlled so that the coated paper has a basis weight of at least 110 pounds per ream.
34. A process as in claim 32 , including the step of calendering the coated paper to a 75° TAPPI gloss on the order of 35-50.
35. A process as in claim 32 , wherein said extruding and coating steps are controlled so that the coated paper has a coating weight/basis weight ratio on the order of 6%-10%.
36. A process as in claim 32 , wherein said providing step provides a waterborne furnish containing fiber and said extruding and coating steps are controlled so that the coated paper has a coating weight/fiber weight ratio on the order of 5%-31%.
37. A process as in claim 32 , wherein said providing step provides furnish that forms a paper web having on the order of 7%-15% filler.
38. A process as in claim 32 , including the step, prior to said coating step, of applying a precoat of lightly pigmented coating on each side of the paper web at a weight on the order of 1-2.5 pounds per side per ream.
39. A process as in claim 32 , wherein said providing step provides furnish that is substantially groundwood free.
40. A process as in claim 32 , wherein said providing step provides a furnish containing groundwood free high brightness bleached pulp.
41. A process as in claim 21 , wherein the coated paper has a basis weight to at least 110 pounds per ream.