Process for making paper

a papermaking and paper technology, applied in the field of papermaking pulps, can solve problems such as instability of papermaking pulp, and achieve the effects of improving fine retention, drainage and formation, and long shelf li

Inactive Publication Date: 2005-07-28
BUCKMAN LAB INT INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0007] The peptizer is present in the microparticle dispersion for the purpose of maintaining the dispersion in the form of a sol and to prevent the dispersion from setting to a gel for a predetermined period of time. This permits the formation of relatively concentrated microparticle sols which can be formed off-site, which exhibit a relatively long shelf life and can be shipped to the papermaking plant for immediate or future use.
[0008] The inventor has unexpectedly found that certain microparticle dispersions which include a peptizer also provide significant improvements over microparticle dispersions which do not employ a peptizer. For example, the inventor has found that the use of a retention aid including a microparticle dispersion containing synthetic hydrous sodium lithium magnesium silicate and a peptizer significantly improves retention of fines, drainage and formation, thereby providing enhancements in the papermaking process and in the paper product.

Problems solved by technology

One problem with microparticle sols employed in papermaking pulps is instability.

Method used

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Examples

Experimental program
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Effect test

examples

[0072] In the examples below, various components used in the examples are abbreviated. In the examples, the components identified as “RD”, “RDS” and “JS” are Laponite RD, Laponite RDS and Laponite JS respectively, available from Rockwood Additives Limited. Laponite RD is a hydrous sodium lithium magnesium silicate; Laponite RDS is a hydrous sodium lithium magnesium silicate with tetrasodium pyrophosphate; and Laponite JS is a hydrous sodium lithium magnesium fluorosilicate with tetrasodium pyrophosphate. When followed by a numerical value, for example, “RDS 0.5”, the numerical value represents the amount of pounds on a dry basis of the Laponite microparticles per ton of paperstock based on the dried solids weight of the paperstock.

[0073] In the examples below, the abbreviations “B 594” and “594” represent BUFLOC™ 594, available from Buckman Laboratories International, Inc., which is a high molecular weight cationic polyacrylamide having an average molecular weight of from about 5,0...

example i

Drainage and Turbidity Tests

[0076] Tests were conducted at a paper mill. Drainage was performed using a small screen through which 500 ml samples were drained using a modified Schopper Riegler method. Mixing was carried out in a food blender.

[0077] Equipment used for the modified Shopper Riegler drainage test included the following: a Modified Schopper Riegler (MSR); a 1000 ml graduated cylinder; a stopwatch; a 5-gallon (18.9 I) plastic bucket; wires for MSR; a vacuum flask and funnel (for retention); Whatman ashless filter papers (for ash retention); a turbidity meter; a hemocytometer; and a microscope.

[0078] Samples to be tested were taken from the headbox of the papermaking apparatus. For each test, 1000 ml was required. Because temperature has an impact on drainage, each test was run immediately after the sample was taken. For lab studies with the retention aids, the furnish was kept at the same temperature as the headbox temperature.

[0079] If the MSR was cold and the sample...

example 2

Retention Tests

[0087] Britt Jar tests were performed at 1,000 rpm to evaluate performance of the retention aid system according to the invention based on increased first pass retention and increased first pass ash retention. In the Britt Jar, the furnish is under continuous movement, so no fiber mat is formed and the water can drain continuously through the wire. This simulates the stock and water dewatering occurring on the paper machine.

[0088] The furnish used in the Britt Jar tests was identical to the furnish used in Example 1.

[0089] In the Britt Jar tests, the chemicals are applied in the correct sequence and the furnish is mixed to a degree to simulate the treatment of the furnish by paper machine equipment such as fan pumps and centri-screens. As it is sheared, the stock spends a second (at the most) actually in the fan pump or the screens. Another way to simulate the shear and to represent the actual short contact time is to carry out all chemical mixing outside the Britt...

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Abstract

Methods for making paper or paperboard are described. One preferred method comprises forming a treated pulp by added to a papermaking pulp a synthetic layered silicate, a peptizer and at least one polymer. The synthetic layered silicate preferably comprises a synthetic hydrous sodium lithium magnesium silicate and the polymer is selected from cationic, nonionic and amphoteric polymers. The peptizer is preferably an inorganic polyphosphate peptizer and is contained in certain commercial synthetic layered silicate products. The inventor has surprisingly found that the peptizer provides significant improvements in drainage, retention and turbidity, thereby improving the papermaking process and the paper or paperboard product.

Description

[0001] This application claims the benefit under 35 U.S.C. §119(e) of prior U.S. Provisional Patent Application No. 60 / 538,622 filed Jan. 23, 2004, which is incorporated in its entirety by reference herein.FIELD OF THE INVENTION [0002] The present invention relates to papermaking pulps, papermaking processes employing the pulps, papermaking apparatus and paper and paperboard products made from the pulps. More particularly, the present invention relates to treating papermaking pulp with at least one microparticle-containing retention aid system. BACKGROUND OF THE INVENTION [0003] Retention aid systems containing microparticles and other particulate materials have been added to papermaking pulps as process aids to improve retention and other properties such as formation and drainage. For example, U.S. Pat. No. 5,194,120 to Peats et al., incorporated herein by reference in its entirety, describes a retention aid system comprising a cationic polymer and an amorphous metal silicate mater...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): D21H17/37D21H17/45D21H17/66D21H17/68D21H21/10D21H23/14
CPCD21H17/375D21H17/455D21H23/14D21H17/68D21H21/10D21H17/66
Inventor COVARRUBIAS, ROSA MARIA
Owner BUCKMAN LAB INT INC
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