Composition and recording sheet with improved optical properties
A composition is provided, which comprises a water-soluble salt of a divalent metal; a complexing agent having an affinity for the divalent metal; and an optical brightening agent. Methods of using the composition, and recording sheets which include the composition, are also disclosed.
1. A recording sheet, comprising:
a paper substrate comprising a plurality of cellulosic fibers;
a composition, comprising:
from about 0.02 g/m 2 to about 4 g/m 2 of the recording sheet of a water-soluble salt of a divalent metal selected from the group consisting of calcium, magnesium, barium, or a combination thereof;
a complexing agent having an affinity for the divalent metal; and
from about 0.005 to about 4 weight percent based on the weight of the recording sheet of an optical brightening agent;
wherein when the recording sheet does not contain starch, the complexing agent is present in an amount ranging from about 0.5 Lb/ton of recording sheet to about 100 Lb/ton of recording sheet; and wherein when the recording sheet contains starch, the complexing agent is present in an amount ranging from about 0.1 Lb/100 Lb starch to about 100 Lb/100 Lb starch; and
wherein said complexing agent is selected from the group consisting of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, diethylenetriaminepentaacetic acid salt, ethylenediaminetetraacetic acid disodium salt, ethylenediaminetetraacetic acid tetrasodium salt, ethylenediaminetetraacetic acid trisodium salt, ethylenediaminetetraacetic acid disodium magnesium salt, ethylenediaminetetraacetic acid disodium calcium salt, ethylenediaminetetraacetic acid diammonium salt, ethylenediaminetetraacetic acid dipotassium salt, ethylenediaminetetraacetic acid tripotassium salt, ethylenediaminetetraacetic acid dilithium salt, ethylenediaminetetraacetic acid tetramethylammonium salt, ethylenediaminetetraacetic acid calcium salt, ethylenediaminetetraacetic acid magnesium salt, ethylenediaminetetraacetic acid aluminum salt, poly-4-styrene sulfonic acid salt, 1-butyl-3-methyl-imidazolium-thiocyanate, 1-ethyl-3-methylimidazolium thiocyanate, 1-ethyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium methyl sulfate, methyl imidazolium, salts thereof, or a combination thereof.
2. The composition of claim 1 , wherein the salt is a calcium(II) salt.
3. The composition of claim 1 , wherein the salt comprises a combination of salts of divalent metals.
4. The composition of claim 1 , which further comprises a sizing agent, and wherein the optical brightening agent is present in an amount ranging from about 10 to 100 pounds per 100 pounds of sizing agent.
5. The recording sheet of claim 1 , wherein the salt is present in an amount of about 0.04 g/m 2 to about 1.5 g/m 2 of the recording sheet.
6. The recording sheet of claim 1 , wherein the divalent metal is selected from the group consisting of calcium, magnesium, or a combination thereof.
7. The recording sheet of claim 1 , wherein the optical brightening agent is present in an amount ranging from about 0.01 to about 3 weight percent based on the weight of the recording sheet.
8. The recording sheet of claim 1 , further comprising polyvinyl alcohol.
9. The recording sheet of claim 1 , further comprising a sizing agent.
10. The recording sheet of claim 1 , further comprising from 0.25 to 6 gsm of a sizing agent.
11. The recording sheet of claim 1 , further comprising a sizing agent and polyvinyl alcohol, wherein the polyvinyl alcohol is present at an amount of from 0.001 wt % to 100 wt % based on the total weight of sizing agent.
12. The recording sheet of claim 1 , further comprising a sizing agent and polyvinyl alcohol, wherein the polyvinyl alcohol is present at an amount of from 0.01 wt % to 10 wt % based on the total weight of sizing agent.
13. The recording sheet of claim 1 , wherein when the recording sheet does not contain starch, the complexing agent is present in an amount ranging from about 0.5 Lb/ton of recording sheet to about 50 Lb/ton of recording sheet.
14. The recording sheet of claim 1 , wherein when the recording sheet contains starch, the complexing agent is present in an amount ranging from about 0.1 Lb/100 Lb starch to about 50 Lb/100 Lb starch.
15. The recording sheet of claim 1 , wherein when the recording sheet does not contain starch, the complexing agent is present in an amount ranging from about 0.5 Lb/ton of recording sheet to about 25 Lb/ton of recording sheet.
16. The recording sheet of claim 1 , wherein when the recording sheet contains starch, the complexing agent is present in an amount ranging from about 0.1 Lb/100 Lb starch to about 25 Lb/100 Lb starch.
17. The recording sheet of claim 1 , wherein when the recording sheet does not contain starch, the complexing agent is present in an amount ranging from about 0.9 Lb/ton of recording sheet to about 25 Lb/ton of recording sheet.
18. The recording sheet of claim 1 , wherein when the recording sheet contains starch, the complexing agent is present in an amount ranging from about 0.5 Lb/100 Lb starch to about 25 Lb/100 Lb starch.
19. The recording sheet of claim 1 , wherein when the recording sheet does not contain starch, the complexing agent is present in an amount ranging from about 0.9 Lb/ton of recording sheet to about 20 Lb/ton of recording sheet.
20. The recording sheet of claim 1 , wherein when the recording sheet contains starch, the complexing agent is present in an amount ranging from about 0.9 Lb/100 Lb starch to about 20 Lb/100 Lb starch.
21. The recording sheet of claim 1 , wherein when the recording sheet does not contain starch, the complexing agent is present in an amount ranging from about 0.9 Lb/ton of recording sheet to about 15 Lb/ton of recording sheet.
22. The recording sheet of claim 1 , when the recording sheet contains starch, the complexing agent is present in an amount ranging from about 0.9 Lb/100 Lb starch to about 15 Lb/100 Lb starch.
23. The recording sheet of claim 1 , wherein the optical brightening agent is present in an amount ranging from about 0.005 to about 4 weight percent based on the weight of the recording sheet; wherein the recording sheet does not contain starch; and wherein the complexing agent is present in an amount ranging from about 0.9 Lb/ton of recording sheet to about 20 Lb/ton of recording sheet.
24. The recording sheet of claim 1 , wherein the optical brightening agent is present in an amount ranging from about 0.005 to about 4 weight percent based on the weight of the recording sheet; wherein the recording sheet contains starch; and wherein the complexing agent is present in an amount ranging from about 0.9 Lb/100 Lb starch to about 20 Lb/100 Lb starch.
25. The recording sheet of claim 7 , further comprising polyvinyl alcohol.