Method for optically brightening paper

• US 6,464,832 B2
• Filed: 09/10/2001
• Issued: 10/15/2002
• Est. Priority Date: 09/16/1997
• Status: Expired due to Fees

• Current Assignee: CIBA Specialty Chemicals
• Original Assignee: CIBA Specialty Chemicals
• Inventors: Rohringer, Peter, Engelhardt, Thomas
• Primary Examiner(s): Chin, Peter
• Application Number:
  US09/949,691
• Publication Number:
  US 20020084049A1
• Time in Patent Office: 400 Days
• Field of Search: 162/162, 162/158, 162/181.6, 162/135, 106/287.2, 106/287.21, 106/467, 106/491
• US Class Current: 162/158
• CPC Class Codes: D21H 17/68 siliceous, e.g. clays
• CPC Class Codes: D21H 21/30 Luminescent or fluorescent substances, e.g. for optical bleaching D21H21/40 takes precedence

Abstract

A simplified method for the optical brightening of paper either in the pulp mass, the size or metering press or by coating by the use of a formulation of an optical brightening agent together with a swellable layered silicate.

Claims

1. A method for the optical brightening of paper, which comprises adding to a paper or pulp a formulation consisting essentially of a swellable layered silicate which is a synthetic zeolite and an optical brightener which is a derivative of 4,4′

-bis-(triazinylamino)-stilbene-2,2′

-disulfonic acid.

2. A method according to claim 1, wherein the formulation is in the form of a dry mixture or an aqueous dispersion.

3. A method according to claim 2, wherein the dry mixture contains 0.1 to 90% by weight of the optical brightener, based on the weight of the swellable layered silicate.

4. A method according to claims 2, wherein the aqueous dispersion contains0.1 to 15% by weight of optical brightener, based on the amount of the swellable layered silicate.

5. A method according to claim 4, wherein the aqueous dispersion contains 1 to 10% by weight of optical brightener, based on the amount of the swellable layered silicate.

6. A method according to claim 1, wherein the aqueous dispersion contains 2 to 60% by weight of the swellable layered silicate.

7. A method according to claim 6, wherein the aqueous dispersion contains 2 to 50% by weight of synthetic zeolite.

8. A method according to claim 1, wherein the 4,4′

-bis-(triazinylamino)-stilbene-2,2′

-disulphonic acid optical brightener is of the formula;

in which R₁ and R₂, independently, are phenylamino;

, mono- or disuiphonated phenylamino, mompholino, —

N(CH₂CH₂OH)₂, —

N(CH₃)(CH₂CH₂OH), —

NH₂, —

N(C₁-C₄alkyl)₂, —

OCH₃, —

Cl, NHCH₂CH₂SO₃H, CH₂CH₂OH or ethanolaminopropionic acid amide; and

M is H, Na, Li, K, Ca, Mg, ammonium, or ammonium that is mono-, di-, tri- or tetrasubstituted by C₁-C₄alkyl, C₁—

C₄hydroxyalkyl or a mixture thereof.

9. A method according to claim 1, wherein the optical brightener is of the formula:

or a mixture of at least two compounds of formulae (5) to (7).

10. A method according to claim 1, in which the formulation is added to the pulp mass.

11. A method according to claim 1, in which the formulation is used for paper coating.

12. A method according to claim 1, in which the formulation is added to a size press or metering press.

13. Paper which has been optically brightened by the method according to claim 9.