FI108240B - Method for making paper - Google Patents

Description

108240

METHOD FOR PAPER MANUFACTURE

The present invention relates to a process for making paper, whereby at least one mechanical pulp component, a binder and other components are mixed to form a pulp, the pulp is formed into a web and the web is dried and, if desired, post-treated.

In the present application, paper generally refers to web-based products containing cellulose fibers and / or ligno-cellulosic fibers, uncoated or coated, single or multiple layers, thinner or thicker products, commonly referred to as paper or board.

This patent application does not further describe the formation of a paper web from a pulp, the drying of the web, and the possible post-treatment; in this regard, reference is made to methods and literature generally known in the art.

20 Nowadays, the quality requirements of various types of paper are constantly increasing. In printing papers, rapid drying of the ink can cause the surface of the paper to roughen and form bubbles, which can cause the paper to crack while the surface remains intact. This problem: 25 occurs especially when the z-strength of the paper, the peel strength is too low. The problem is accentuated in papers made using the so-called. gritformer in web formation.

It is an object of the present invention to overcome the above drawbacks. In particular, it is an object of the invention to provide a novel process for the production of paper having a mechanical pulp in particular, so that the paper has a higher peel strength.

As regards the features which characterize the invention, reference is made to the claims.

The invention is based on research carried out, 2,108,240 'whereby it has been found that the peel strength of the paper can be increased by mixing the mechanical pulp component and the binder and adding the other pulp components to this blend only later.

Particularly good results have been obtained by refining the mechanical pulp component and mixing the binder with the post-pulverized mechanical pulp component.

Similarly, particularly good results have been achieved by post-refining the mechanical pulp component with the binder added to the pulp component.

The invention allows the binder to spread evenly and bind to the mechanical pulp component in question. At the same time, when using post-milling, 15 pulp components reveal new fiber surfaces to which the binder can effectively bind.

Post-milling is carried out at the desired mass consistency, e.g., above 2% and up to high consistency masses up to 45%; milling can thus be advantageously carried out e.g. at a consistency of 3 to 18%.

The energy consumption of post-refining can vary within wide limits and is e.g. 10-100 kWh / tonne, preferably e.g. in the order of 10-20-20 kWh / tonne. In the process according to the invention, a The refining can be accomplished by any pulp refiner, as is commonly known in the paper and pulp technology.

The mechanical pulp to be used is any mechanical pulp, e.g., ground, grit or recycled pulp containing 30 grit and / or pulp, or a mixture thereof in any desired ratio. The pulp used in printing papers, which is particularly concerned with the invention, is generally pulp, sorted and bleached pulp in a known manner.

35 The mechanical pulp may be made from any species of wood, creeper or generally any vegetable fiber, such as hardwoods, conifers, straw, reeds, etc.

The paper produced according to the invention may contain mechanical pulp in arbitrary proportions generally known in the paper industry, e.g.

10 to 80% by weight, usually 20 to 60% by weight.

The binder can be added to the mechanical pulp in a ratio generally known in the paper industry, e.g. up to 2-3%, even more up to e.g. up to 5%. The binder used can be any binder commonly used in the paper industry, e.g., anionic and cationic binders, natural xanthan gums such as gum arabic, pectin, dragacanth, ka-raya and algin, or other non-modified anionic polysaccharide compounds; starches; CMC and its derivatives 15 women; modified cationic or anionic binders, as is commonly known in the paper industry (e.g., U.S. Pat. No. 5,104,487).

In addition, any additives known per se, such as filler, agents improving certain or certain properties of the paper, colorants, pigments, etc., as known per se, may be added to the pulp.

The invention will now be described in more detail by way of exemplary embodiments and with reference to the figure. 25 1, which shows the Scott bond strength of a paper with different binders and various blending methods.

Example 1 In this experiment, the effect of a binder on the properties of paper made from hardwood pulp was investigated when the binder was added to the non-refined pulp, the binder and the pulp were ground together or when the binder was added to the post-refined pulp. The pulp used was bleached with hydrogen peroxide at a dose of 1.0%.

Post-milling was performed on an EW laboratory 4 108240 millimeter, ΕΟΚ 100 kWh / h. When the binder was added before grinding, the chemical was added to the pulp, mixed for 25 min and analyzed, pulverized, mixed for 25 min and analyzed. After chemical 5 was added after grinding, the pulp was stirred for 25 min, pulverized, binder added, stirred for 25 min, and analyzed.

The chemicals used were starch, 2%; CMC, 0.5%; and modified polysaccharide, 2%. Modify-10 with polysaccharide was also tested for 50 min of mixing time. In addition, a 0-test without binder and post-grinding without a binder were performed. The results are shown in Table 1.

15 Table 1

Scott-bond peel strength J / m2

Unbound 1 148 Mix 25 min 20 Substances 2 231 "Starch 1 385 2% 2 380 3 482 25

Modified. 1339 "polysaccharide 2 408" 2% 3,470 30 CMC 1 160 0.5% 2,216 3,231

Modified 1,346 Mix 50 min 35 Polysaccharide 2% 3,417 "

In the table, designation 1 means binder additive.

2, binder added and milled together with the pulp component, and 3 binder added after milling. The results are also shown graphically in Figure 1.

According to the test results, blending of the binder with the post-pulp or post-refining of the pulp after mixing clearly increased the bond strength of the pulp paper.

Example 2 In this experiment, the effect of post-refining power on the properties of pulp paper was investigated. In the experiment, a mass prepared similarly to that used in Example 1 was used, with a post-milling power of 15 (JJ EOK) of 0, 50 and 75 kWh / h. Mixing times were 0, 20 min, 40 min and 60 min. The additive used was a modified polysaccharide, 2%. The milling was performed on a factory-sized refiner.

The bond strengths of paper made from pulp are shown in Table 2.

Table 2

With mass 11 1 22 2 2 2 2

Binder NO NO NO NO 2% 2% 2% 2% 2% 'Mixing time / min 0 0 0 0 20 40 60 60 60 JJ EOK / kWh / hr 0 50 75 0 0 0 0 50 75

Bond Column 203,277,305 195,315,301,307,391,506 Strength J / ^ 2 25 Example 3 In this experiment, the effect of a binder on the pulp when added after powder treatment was studied as a laboratory test. In addition, starch was tested at two dose levels. The table shows the results of a pilot experiment with the same mass as a comparison; therein, the chemical was added before post-milling. The pulp used was prepared in a similar manner as in Examples 1 and 2.

The results are shown in Table 3.

Table 3 10

Laboratory test Pilot test

Binder Additives Powder + Powder

1.5% 2.0% 2.0% Chem. ref.

Importa. Importa. mod. polys. Free.

kem.

Bond strength 450,449,489,482,271 J / m2

Tensile index Nm / g 41.3 41.0 43.6 38.3 36.3

According to the test results, the addition of binder after grinding increased the bond strength and tensile index of the pulp paper sheet by more than 15 during milling.

. The exemplifying embodiments are intended only to illustrate the invention without limiting it in any way, and the invention may vary within the scope of the appended claims.

Claims (8)

108240 A process for producing paper, wherein at least one mechanical pulp component, a binder, and f other components are mixed to form a pulp, the pulp is formed into a web and the web is dried; characterized in that the mechanical pulp component and the binder are mixed together and the other components are mixed with the mechanical pulp component after mixing with the binder. Process according to Claim 1, characterized in that the mechanical pulp component is post-milled and mixed with the binder after milling. Method according to claim 1, characterized in that the mechanical pulp component is post-milled together with the binder. Method according to one of Claims 1 to 3, characterized in that the post-milling is carried out at a consistency of 2 to 45%, preferably 3 to 18%. Method according to one of Claims 1 to 4, characterized in that the post-refining energy consumption is from 10 to 100 kWh / ton. A method according to any one of claims 1 to 5, characterized in that the mechanical pulp • 25 contains a pulp, a pulp or a pulp and / or a pulp containing pulp. Process according to one of Claims 1 to 6, characterized in that the paper pulp contains 10 to 80% by weight, preferably 25 to 30% by weight, of mechanical pulp. Process according to one of Claims 1 to 6, characterized in that the paper pulp contains more than 0.5%, preferably 0.5 - 3% of binder.