FI117715B - A method for improving the economy of manufacture and use of a filler - Google Patents

Description

117715

The present invention relates to a process for improving the economy of the manufacture and use of a filler for use in the manufacture of paper and board, in particular calcium carbonate. The invention also relates to a process for making and / or producing said filler in a form that can be directly used for paper and board applications. It is a further object of the invention to provide a process for making paper and / or board which utilizes pulp having said filler dried in pulp bales.

15 Recent vigorous efforts have been made to develop calcium carbonate-based fillers and methods for their manufacture in order to meet the ever-increasing demands for high-quality paper, reduce environmental load and energy consumption, and improve paper and board machine runnability. Traditionally, in the manufacture of paper and board, the mechanical pulp or chemical pulp, or a combination thereof, is formed into a stock to which the necessary fillers and other additives may be added, and further produced by a suitable process of paper or board of desired quality.

Patent FI100729 discloses a calcium carbonate based filler which provides 25 paper with better strength properties and lower basis weight than previously known and which generally can reduce the cost of papermaking. The calcium carbonate-based filler is prepared by precipitating calcium carbonate on the surface of the fine fiber fibrils made from cellulosic and / or mechanical pulp. This results in the formation of bead-like calcium carbonate aggregates held together by fine fib-30 grills, i.e. fine strands, in which the calcium carbonate particles are deposited on the fine strands. The diameter of the calcium carbonate particles in the aggregates is about 0.2 to 3 µm. This filler, also known as SuperFill®, is preferably calcium carbonate based and provides the paper with a markedly improved combination of light scattering and strengths compared to conventional calcium carbonate based fillers. Of particular note is the ability of SuperFill® filler to give the paper an extremely uniform distribution of light scattering material.

Kaisi um carbonate-based SuperFill® filler can be prepared on an industrial scale, mainly in the form of dilute suspensions, which significantly limits the use of the filler. This also means that SuperFill® filler can only be used in locations where the SuperFill® filler plant is located, because the high water content of the filler makes transportation very uneconomical and difficult. In addition, if SuperFill® 15 filler is only produced in small quantities, the manufacturing cost is high, which in turn may result in the filler price being too high for some product applications. Further, the SuperFill® filler manufacturing process requires special commodities such as a sufficiently good source of carbon dioxide, which is not always available in the paper or board manufacturing region 11a.

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From the foregoing it can be seen that there is an obvious need for a process for the preparation and / or production of SuperFill® filler, preferably calcium carbonate based SuperFill® filler in the form of · ·, · ··. can be directly used for paper and board applications and can bypass or at least substantially reduce the problems of prior art solutions described above.

«« · • · * • · · .1. It is an object of the present invention to provide a process for preparing pulp with a suitable amount of SuperFill® filler, preferably calcium carbonate-based SuperFill® filler, dried, for each paper and board application. pulp, preferably for bales, and where SuperFill® 3 117715 filler can also be used in plant locations that do not have a production facility for said filler.

It is also an object of the invention to provide pulp thus prepared with a suitable amount of SuperFill® filler suitable for paper and board applications.

It is a further object of the present invention to provide a process for improving the economy of manufacture and use of SuperFill® filler, preferably SuperFill® calcium carbonate based filler.

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It is a further object of the invention to provide a process for the production of paper and / or board, which utilizes pulp with a SuperFill® filler, preferably a calcium carbonate-based SuperFill® filler, dried in pulp bales.

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The features of the inventive methods and pulp are set forth in the claims.

It has been found that the problems of the prior art can be substantially reduced or avoided by the solution of the invention wherein SuperFill® * · filler, preferably SuperFill® filler based on calcium carbonate, is made by precipitation from cellulosic fibers and / or mechanical pulp fiber. · • · ♦! by grinding calcium carbonate on the surface of the fines, • ♦ ... (found as a dilute suspension of pulp in a pulp drying machine. In addition to or in place of calcium carbonate, 25% other light-scattering fines, such as organic or inorganic, can be used , ··· salt, examples of which are gypsum, calcium oxalate and barium sulfate, The filler may optionally also contain a dispersant such as sodium hexametaphosphate.

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The SuperFill® filler is passed as an aqueous suspension having a dry solids content of 0.1-35 wt.%, Preferably 2-6 wt.%, To the pulp dryer and further to the pulp. .

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Optionally, a separate filler drying line may be used in which the SuperFill® filler is dried, recovered and then mixed at a desired concentration between 1 and 70 wt.%, Preferably 1 to 50 wt.%, Before the pulp is dried. Thereafter, the pulp is dried in a conventional manner, preferably in the form of pulp. Drying the filler several times does not substantially reduce its binding potential.

The result is pulp, preferably pulp bales containing the desired amount of SuperFill filler evenly distributed throughout the pulp. The pulp may be ground if necessary, but it may also be ground.

Bale pulp containing SuperFill® can be pulverized in the conventional manner in a paper or board mill and added to any conventional pulp mill. . like a massascose. Pulp containing SuperFill® filler can be used to make paper and board according to methods known per se, which now omit • · · ··· the conventional filler addition step.

··· · · * In the case of coated grades, the differences between the pig, * · * that accompany the wreck. The amount of ment can be suitably compensated, for example, by two SuperFill®

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25 with a different concentration of pulp.

The process of the invention and the pulp thus produced have significant advantages over prior art solutions. The invention significantly improves the production potential of the technology associated with SuperFill® filler, thus improving both manufacturing economy and the number of applications. According to the invention, pulp containing an appropriate amount of filler for each paper and board application can be prepared. The method avoids the transport of large volumes of water and thus saves energy, costs and space. The pulp containing SuperFill * thus prepared can also be used in such sites and product applications as long as there are no commodities necessary for the construction of the PCC plant, such as a sufficient source of carbon dioxide or suitable pulp processing equipment. It can also be used to produce consistent pulp containing a predetermined amount of SuperFill® filler, which can produce more consistent paper and board. The invention enables a centralized SuperFill®-10 filler manufacturing plant with high capacity and filler production at a lower cost. The production plant may optionally also have its own drying line for the filler.

The process of the invention is illustrated by the following Examples 15, however, which are not intended to be limiting.

Example 1

Preparation of pulp containing SuperFill® filler • * ·: 20 «· * ... a) SuperFill® filler suspension is prepared by a known method described, inter alia, in patent FI 100729.

• · m * \ b) Pulp containing SuperFill filler is prepared by passing 625 kg of dry solids, calculated on the basis of a) SuperFill® filler suspension prepared in a), e 25 containing 500 kg of CaCl 2 and 125 kg of fine fibrils, pulp (375 kg ..., · unirradiated or slightly milled birch pulp), which is then dried as usual. 1000 kg SuperFill® pulp, ··· calculated as dry matter.

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Example 2

Use of Pulp Containing SuperFill® Filler in Paper Production 5 Pulp containing SuperFill® Filler according to Example 1 is made in the conventional manner on a paper machine with Un paper containing: 600 kg SuperFill® Filler pulp containing 300 kg CaCO 3 225 kg Birch pulp 10 75 kg of fine fibrils 250 kg of birch pulp 150 kg of softwood pulp 1000 kg 15

The pulp containing SuperFill® filler is added such that the paper contains 30% by weight of CaCO3 and the pulp in the paper is 76% by weight of birch pulp and 24% by weight of softwood pulp. The paper produced in this way has better opacity, brightness, smoothness and formatting than the corresponding conventionally manufactured paper, which is separately supplemented. 20 In addition, the runnability of the paper machine remains unchanged.

Claims (10)

117715 A process for preparing a pulp containing filler, characterized in that the filler is prepared by precipitating a light-scattering organic or inorganic salt on the surface of the fine pulp fibrils made from cellulosic and / or mechanical pulp fibers, and the excipient thus prepared is drying said filler, mixing it with the pulp before drying the pulp and drying the pulp. 1 ° Process according to Claim 1, characterized in that the light-scattering organic or inorganic salt is calcium carbonate, gypsum, calcium oxalate or barium sulphate or a combination thereof. Process according to claim 1 or 2, characterized in that the light-scattering organic or inorganic salt is calcium carbonate. »· 1 • f · jt The process according to any one of claims 1 to 3, characterized in that the dry solids content of the filler in the suspension is 0.1 to 35% by weight, and when added, the amount of filler in the pulp is 1 to 1%. 70 wt%. • · · 1 ·· The process according to claim 4, characterized in that the concentration of the filler in the suspension is 2-6% by weight. Method according to one of Claims 1 to 5, characterized in that • 1 '! pulp is ground. ·· 1 • * · Process according to one of Claims 1 to 6, characterized in that the filler contains a dispersing agent. 30 • · ··· · · - - 117715 Process for producing paper or board, characterized in that the filler containing pulp or filler-containing pulp made by the process according to any one of claims 1 to 7 is added to a pulp mixture for the production of paper or board, from which 5 paper or board are made. Process according to Claim 8, characterized in that the filler-containing pulp or the combination of pulp-containing pulp is pulverized and added to the pulp mixture used in the manufacture of paper or board, where paper or board is made. Use of a filler-containing pulp or a combination of filler-containing pulps produced by the process of any one of claims 1 to 7 in the manufacture of paper and board. 15 t • · - • · • · • * • · • ·· * »·» * • · ♦ · ···· '. t t • ... • · - - • · ·· * ·· • 9 • · '♦. ♦ * «« * • · ··· ··· 117715