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Process for production of a paper or paperboard product

a technology product, which is applied in the field of paper or paperboard product production, can solve the problems of reducing strength, limiting the amount of cationic starch which can be added to the slurry, and fibers which are made cationic by excessive cationic starch addition will not be able to absorb other cationic additives, etc., to achieve easy and cost-effective, improve strength and density, and increase the strength of the product

Inactive Publication Date: 2012-09-27
STORA ENSO OYJ
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0009]It is an object of the present invention to provide a process which in an easy and cost efficient way will be able to produce a paper or paperboard with improved strength and density.
[0010]These objects and other advantages are achieved by the paper or paperboard product according to claim 1. The present invention relates to a process for producing a paper or paperboard product which process comprises the steps of; providing a furnish comprising fibers, adding starch to the furnish, adding microfibrillated cellulose to the furnish and conducting the furnish to a wire in order to form a web, wherein the starch and microfibrillated cellulose is added separately to the furnish. It has been shown that a product comprising both starch and microfibrillated cellulose (MFC) increases the strength of the product since the amount of starch can be increased without increasing the density of the paper or paperboard product.
[0011]It is preferred that the furnish comprises 2-15% by weight of starch and 1-15% by weight of microfibrillated cellulose. The amount of starch respectively MFC of the product depends on the end use and the corresponded desired properties of the product. High amounts of starch will increase the strength of the product and it has been shown that the combination of MFC and starch makes it possible for the product to retain larger amounts of starch.

Problems solved by technology

However, large amount of fillers in the product decreases the strength.
When adding large amounts of cationic starch to a papermaking furnish, in order to achieve high resulting paper strength, two major problems arise.
The first is that the cationic starch molecules tend to saturate the anionic charge on the cellulose fibers, thus setting a limit to the amount of cationic starch which can be added to the slurry.
A second problem is that fibers which are made cationic by excessive cationic starch addition will not be able to adsorb other cationic additives which are commonly added to the pulp slurry, such as sizing agents and retention aids.
Furthermore, high amounts of starch often cause problems with runnability, microbiology and foaming during the production process.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0031]The dried BCTMP were soaked in water over night and then dispersed in hot water. The BCTMP suspension was thereafter diluted to a concentration of 0.3%.

[0032]The produced MFC was also diluted to a concentration of 0.3% and dispersed using a kitchen mixer.

[0033]A formette sheet former was used to prepare the sheets for testing. The sheets were prepared according to the following procedure; Pulp suspension measured to produce a 150 gsm sheet was added to the stock tank. During agitation, starch if used, and MFC if used, was added. After 30 seconds, 500 g / t C-PAM was added and after another 30 seconds was 300 g / t BMA added to the stock and the sheet forming was thereafter started.

[0034]The formed sheet was wet pressed and dried while the shrinkage was constrained. The dried sheet was tested for structural density according to SCAN P 88:01, z-strength according to SCAN P 80:88 and tensile strength index according to ISO 1924-3.

TABLE 1Results of strength and density tests.Tensile s...

example 2

[0036]Tests were also performed where MFC and cationic starch either was pre-mixed or added separately to the stock.

[0037]When pre-mixed, the MFC and cationic starch was well mixed before addition to the stock. When added separately, cationic starch was first added and well mixed with the stock for 5 minutes followed by addition of MFC.

[0038]MFC in an amount of 25 kg / t and cationic starch in an amount of 20 kg / t were added in both samples, both the pre-mixed and the separately added.

[0039]After addition of the MFC and cationic starch to the stock, a formette sheet former was used in the same manner as described in Example 1.

[0040]As a reference the stock without any MFC and cationic starch was used.

[0041]Scott Bond was measured according to TAPPI UM-403.

TABLE 2Results of strength and density tests.Structuraldensityz-strengthScott BondSample(kg / m3)(kPa)(J / m2)Reference310170100Pre-mixed sample320210125Separately added sample320225145

[0042]As can be seen from Table 2, both z-strength a...

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PUM

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Abstract

The present invention relates to a process for producing a paper or paperboard product which process comprises the steps of, providing a furnish comprising fibers, adding starch to the furnish, adding microfibrillated cellulose to the furnish, conducting the furnish to a wire in order to form a web, wherein the starch and microfibrillated cellulose is added separately to the furnish.

Description

FIELD OF THE INVENTION[0001]The present invention relates to a process for production of a paper or paperboard product comprising a furnish which comprises starch and microfibrillated cellulose.BACKGROUND[0002]In papermaking processes there is an ongoing concern to find ways to produce paper or paperboard at reduced costs without impairing the properties of the product, e.g. without decreasing the strength of the product.[0003]One way to reduce the cost is to increase the filler content of a paper or paperboard product and thus be able to reduce the amount of fibers in the paper or paperboard. Besides being economically beneficial, fillers also improve the opacity and printability properties of the product. However, large amount of fillers in the product decreases the strength. Thus, there is a balance between the possible amount of fillers added and the required strength of the paper or paperboard produced.[0004]Furthermore, during production of paperboard there is a desire to prod...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): D21H23/04D21H17/28
CPCD21H11/18D21H27/30D21H21/18D21H17/28B82Y30/00D21H17/25D21H21/50
Inventor AXRUP, LARSHEISKANEN, ISTORIIKONEN, MIKA
Owner STORA ENSO OYJ
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