Compositions having increased concentrations of carboxymethylcellulose
Embodiments of the present description provide methods for increasing the concentration of carboxymethylcellulose alkali solutions that are particularly suitable for use in a high solids paper coating, barrier materials, etc. Generally described, the method includes dissolving carboxymethylcellulose (CMC) and an alkali salt in water to obtain an alkali solution of CMC. The CMC desirably has a degree of substitution less than about 0.9. The alkali solution of CMC includes CMC in a concentration greater than about 9.8% by weight, has a pH from about 7.5 to about 11, and is characterized as having a viscosity of less than about 5,000 mPa.
1. A method for increasing the concentration of a CMC stock solution comprising:
dissolving a CMC, having a degree of substitution of less than about 0.9, and a sodium carbonate in water to obtain an alkali solution of CMC,
wherein the alkali solution of CMC comprises the CMC in a concentration greater than about 9.8% by weight and the sodium carbonate in a concentration from about 0.1% to about 1.0% by weight, and
wherein the alkali solution of CMC has a pH from about 7.5 to about 11 and has a viscosity of less than about 5,000 mPa when measured at a temperature from about 50 ° C. to about 60 ° C.
2. The method of claim 1 , wherein the CMC has a degree of substitution of from about 0.4 to about 0.9.
3. The method of claim 1 , wherein the CMC has a molecular weight of less than about 300 kD.
4. The method of claim 1 , wherein the CMC has a pH of less than about 9 for a 1% solution of the CMC.
5. The method of claim 1 , wherein the CMC has a pH of less than about 8 for a 1% solution of the CMC.
6. The method of claim 1 , wherein the alkali solution of CMC comprises the CMC in a concentration greater than about 9.8% up to about 25% by weight.
7. The method of claim 1 , wherein the alkali solution further comprises sodium sulfite, sodium bicarbonate, or a combination thereof, and wherein sodium sulfite, sodium bicarbonate, or a combination thereof is present in the alkali solution of CMC in a concentration from about 0.1% to about 2% by weight.
8. The method of claim 1 , wherein the alkali solution of CMC has a viscosity that is substantially reduced as compared to a comparable solution of CMC without the sodium carbonate.
9. The method of claim 1 , wherein the viscosity of the alkali solution of CMC comprising the sodium carbonate is less than about 50% of the viscosity of a comparable solution of CMC without the sodium carbonate.
10. A high solids paper coating composition comprising:
a pigment; and
an alkali solution of CMC that comprises water, a CMC in a concentration greater than about 9.8% by weight, and an alkali salt in a concentration of at least about 0.05% by weight,
wherein the CMC has a degree of substitution less than about 0.9, and
wherein the alkali salt is selected from the group consisting of sodium carbonate, sodium bicarbonate, sodium sulfite, sodium hydroxide, sodium silicate, potassium hydroxide, potassium bicarbonate, calcium hydroxide, and combinations thereof.
11. The high solids paper coating composition of claim 10 , wherein the CMC has a molecular weight of less than about 300 kD.
12. The high solids paper coating composition of claim 10 , wherein the CMC has a pH of less than about 9 for a 1% solution of the CMC.
13. The high solids paper coating composition of claim 10 , wherein the CMC has a pH of less than about 8 for a 1% solution of the CMC.
14. The high solids paper coating composition of claim 10 , wherein the alkali solution of CMC comprises the CMC in a concentration greater than about 9.8% up to about 25% by weight.
15. The high solids paper coating composition of claim 10 , wherein the alkali salt comprises sodium carbonate, and the alkali solution of CMC comprises sodium carbonate in a concentration from about 0.1% to about 1.0% by weight.
16. The high solids paper coating composition of claim 15 , wherein the alkali salt further comprises sodium sulfite, sodium bicarbonate, or a combination thereof, and wherein sodium sulfite, sodium bicarbonate, or a combination thereof is present in the alkali solution of CMC in a concentration from about 0.1% to about 2% by weight.
17. The high solids paper coating composition of claim 10 , wherein the total concentration of the alkali salt in the alkali solution of CMC is less than about 5% by weight.
18. The high solids paper coating composition of claim 10 , wherein the alkali solution of CMC has a pH of from about 7.5 to about 11.
19. The high solids paper coating composition of claim 10 , wherein the alkali solution of CMC has a viscosity that is substantially reduced as compared to a comparable solution of CMC without the alkali salt.
20. The high solids paper coating composition of claim 10 , wherein the alkali solution of CMC comprising the alkali salt has a viscosity that is less than about 50% of the viscosity of a comparable solution of CMC without the alkali salt.
21. A CMC stock solution comprising:
an alkali solution of CMC comprising water, a CMC in a concentration greater than about 9.8% by weight, and an alkali salt in a concentration greater than about 0.05% by weight,
wherein the CMC has a degree of substitution less than about 0.9 and a molecular weight less than about 300 kD,
wherein the alkali salt is selected from the group consisting of sodium carbonate, sodium bicarbonate, sodium sulfite, sodium hydroxide, sodium silicate, potassium hydroxide, potassium bicarbonate, calcium hydroxide, and combinations thereof, and
wherein the alkali solution of CMC has a pH from about 7.5 to about 11, and has a viscosity of less than about 5,000 mPa when measured at a temperature from about 50° C. to about 60 ° C.
22. The CMC stock solution of claim 21 , wherein the concentration of the alkali salt is from about 0.1% to about 2.0% by weight and the concentration of the CMC is greater than about 9.8% up to about 20% by weight.
23. The CMC stock solution of claim 21 , wherein the concentration of the alkali salt is from about 0.1% to about 1.5% by weight and the concentration of the CMC is greater than about 12% up to about 20% by weight.
24. The CMC stock solution of claim 21 , wherein the CMC has a pH of less than about 9 for a 1% solution of the CMC.
25. The CMC stock solution of claim 21 , wherein the CMC has a pH of less than about 8 for a 1% solution of the CMC.
26. The CMC stock solution of claim 21 , wherein the alkali solution of CMC comprises the CMC in a concentration greater than about 9.8% up to about 25% by weight.
27. The CMC stock solution of claim 21 , wherein the alkali salt comprises sodium carbonate, and the alkali solution of CMC comprises sodium carbonate in a concentration from about 0.1% to about 1.0% by weight.
28. The CMC stock solution of claim 27 , wherein the alkali salt further comprises sodium sulfite, sodium bicarbonate, or a combination thereof, and wherein sodium sulfite, sodium bicarbonate, or a combination thereof is present in the alkali solution of CMC in a concentration from about 0.1% to about 2% by weight.
29. The CMC stock solution of claim 21 , wherein the total concentration of the alkali salt in the alkali solution of CMC is less than about 5% by weight.
30. The CMC stock solution of claim 21 , wherein the alkali solution of CMC has a viscosity that is substantially reduced as compared to a comparable solution of CMC without the alkali salt.
31. The CMC stock solution of claim 21 , wherein the viscosity of the alkali solution of CMC comprising the alkali salt is less than about 50% of the viscosity of a comparable solution of CMC without the alkali salt.