Coating composition for paper and paperboard
AssigneeStora Enso OYJ
InventorsTuula Sokka, Kaj Backfolk
Life of this patent
Estimating the term…
Abstract
The present invention relates to a coating composition for coating of paper or paperboard, said composition comprising: a pigment, a binder, an optical brightening agent (OBA), a colorant, and a sugar alcohol, and to paper or paperboard coated with at least one layer of the coating composition. The present invention further relates to a method for preparing said coating composition and to an OBA premix useful in the method of preparing the coating composition, said premix comprising an OBA, a sugar alcohol, and optionally a colorant, wherein the OBA and sugar alcohol together make up at least 10% by weight, preferably at least 20% by weight, based on the total weight of solids in the premix.
Claims21
A coating composition for coating of paper or paperboard, said composition consisting essentially of:
- a white pigment,
- a binder,
- an optical brightening agent (OBA),
- a non-white colorant comprising a colored pigment, or a colored dye, or a combination thereof, and wherein an amount of the non-white colorant in the coating composition is in a range of 1 to 5000 g/t, based on a total weight of the coating composition, and
- a sugar alcohol.
An optical brightening agent (OBA) premix for addition to a coating composition, the premix comprising:
- an OBA,
- a sugar alcohol, and
- a non-white colorant comprising a colored pigment, or a colored dye, or a combination thereof,
- wherein the OBA and sugar alcohol together make up at least 10% by weight, based on a total weight of solids in the premix.
A method of preparing a coating composition for coating of paper or paperboard, said method comprising the steps:
- a) mixing OBA, a sugar alcohol, and a non-white colorant to obtain a first mixture,
- b) mixing a white pigment with a binder to obtain a second mixture, and
- c) mixing the first mixture with the second mixture to obtain the coating composition,
- or the steps:
- a1) mixing OBA, a sugar alcohol, and a non-white colorant to obtain a first mixture,
- b1) mixing the first mixture with a white pigment to obtain a second mixture, and
- c1) mixing the second mixture with a binder to obtain the coating composition;
- wherein the non-white colorant comprises a colored pigment, or a colored dye, or a combination thereof, and wherein an amount of the non-white colorant in the coating composition is in the range of 1 to 5000 g/t, based on the total weight of the coating composition.
Dependencies are inferred from the claim text.