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High strength paperboard and method of making same

a paperboard and high-strength technology, applied in papermaking, non-fibrous pulp addition, papermaking, etc., can solve the problems of increasing dry strength, hjalmarson does not teach adding clay to pulp stock, etc., to achieve high strength

Inactive Publication Date: 2006-01-26
SONOCO DEV INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention is about a high strength paperboard and a method of making it. The invention involves adding a high modulus filler to the aqueous pulp slurry before forming it into paper or paperboard. This high modulus filler increases the strength of the resulting paperboard. Additionally, a resin is added to improve load transfer and adhesion between the paper fibers and the high modulus filler. The invention also involves coating glass fibers with a hydrophilic resin and adding them to the aqueous pulp slurry to improve the adhesion of the glass fibers to the paper fibers. Overall, the invention provides a stronger and more durable paperboard.

Problems solved by technology

However, the inventors are aware of no reference that teaches adding high modulus fillers to pulp stock to enhance the dry strength of paper or paperboard.
Rushmere also teaches that clays, calcium carbonate, titanium oxide and / or recycled broke or other cellulosic waste may be added, but doesn't teach that they increase dry strength.
McCall teaches using clay filler for improved optical properties, but notes that “[a]dding fillers to paper has a detrimental effect on the strength properties.”
Hjalmarson does not teach adding clay to pulp stock as a strengthening agent.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0064] Demonstration that adding a high modulus filler to the pulp slurry increases the board modulus In a first example, E-glass fiber filler having a modulus of 72 GPa was added to an aqueous pulp slurry in varying concentrations prior to forming the paperboard.

[0065] The results are summarized in Table 1 below:

TABLE 1Effect of E-glass Filler Volume on Paperboard ModulusPaperboard ModulusPaperboard ModulusVolume % E-glass filler(psi)(Gpa)0406,5002.805454,0003.1310425,4002.9315442,7003.0520508,9003.51

[0066] As shown in Table 1, the modulus in the MD direction was greatest (3.51 GPa) at 20 volume % E-glass. This represented a 25 % increase in modulus in the MD direction over the unmodified paperboard. However, the observed modulus was not as high as would be expected from equation (1) at lower filler concentrations. It is expected that increases in modulus would be observed at filler concentrations greater than 20 %.

example 2

[0067] Demonstration that adding resin coated glass fibers to the pulp slurry increases the paperboard modulus

[0068] In a second example, E-glass fibers (Ef=72 GPa) were wetted with a resin matrix (Em=5.5-11.7 GPa) to form coated glass fibers, then the coated glass fibers were added to an aqueous pulp slurry prior to forming the paperboard. The volume of filler was approximately 20% and the volume of resin was approximately 10%. The modulus of the composite paperboard increased 20% in the MD (from 0.9 GPa to 1.1 GPA) and 100% in the CD (from 0.25 GPa to 0.5 GPa).

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Abstract

A method of making high strength paper or paperboard is provided, comprising the steps of adding a high modulus filler to the aqueous pulp slurry prior and forming the pulp slurry into paper or paperboard. Preferably, the filler is glass fiber that has been coated with a thermosetting resin.

Description

FIELD OF THE INVENTION [0001] This patent relates to a high strength paperboard and a method of making the same by adding a high modulus filler and / or resin to the pulp slurry prior to forming the paperboard. DESCRIPTION OF THE RELATED ART [0002] Paper and paperboard generally are manufactured by preparing an aqueous pulp slurry; depositing a layer of the pulp slurry onto a moving screen or “wire”; draining water through the screen and away from the pulp stock, leaving a wet, weak fiber mat; and pressing and drying the mat to form sheets ready for finishing and cutting. [0003] During the pulping step, various ingredients may be added to affect the properties of the paper, including fillers such as titanium oxide and calcium carbonate for improving the optical properties of the paper. A number of references teach adding polymeric or resinous materials to pulp stock to enhance wet and / or dry strength. However, the inventors are aware of no reference that teaches adding high modulus fi...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): D21H21/18D21F11/00
CPCD21F11/00D21H21/18D21H17/69D21H13/40
Inventor MORIN, JEREMY E.VARADARAJAN, KRISHNARAJU
Owner SONOCO DEV INC