Processes and compositions for brightness improvement in paper production
AssigneeEcolab USA Inc.
InventorsPrasad Y. Duggirala, Sergey M. Shevchenko
Life of this patent
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Abstract
Compositions and methods that preserve and enhance the brightness of pulp, and also improve the color of pulp or paper, when applied during different stages of a papermaking process, are disclosed. The compositions and methods maintain or enhance brightness, prevent yellowing, and enhance the performance of paper products. The compositions can include a mixture of reducing agents and can also include optical brighteners, chelants, polycarboxylates, or other additives. The mixture of reducing agents can include a borohydride, such as sodium borohydride, and any other reducing agent, such as a sulfite or bisulfite.
Claims20
A method for preparing a bleached pulp material having enhanced brightness and enhanced resistance to thermal yellowing comprising:
- i) providing bleached pulp material;
- and
- ii) contacting the bleached pulp material with an effective amount of a mixture of reducing agents comprising a borohydride.
A method of preventing brightness loss and yellowing of a bleached pulp material during storage comprising adding an effective amount of a mixture of reducing agents comprising a borohydride to the bleached pulp material, and optionally further comprising the step of adding one or more chelants, one or more polycarboxylates, or a combination thereof, to the bleached pulp material, and optionally wherein the mixture of reducing agents and optional one or more chelants, and optional one or more polycarboxylates are added to the bleached pulp after a bleaching stage in a storage, blending, or transfer chest.
A composition comprising a mixture of reducing agents, the mixture of reducing agents comprising a borohydride and optionally a sulfite and/or a bisulfite, the composition further comprising one or more optical brightening agents and, optionally, the composition further comprising one or more chelants, one or more polycarboxylates, or any combination of the one or more chelants and the one or more polycarboxylates.
Dependencies are inferred from the claim text.