FI85389B - FOERFARANDE FOER TILLVERKNING AV MASSA. - Google Patents

Description

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METHOD FOR THE PRODUCTION OF PULP - FÖRFARANDE FÖR TILLVERK-NING AV MASS

The present invention relates to a method for producing a mechanical pulp from a fibrous product.

The production of a fibrous product, such as whole wood, wood chips, shavings or pulp ground one or more times into mechanical pulp, is carried out mainly by mechanical methods. The production of mechanical pulp is based on the use of friction. Energy is transferred to the wood in a compression-firing process, whereby the structure of the wood is softened due to the frictional heat and the individual fibers can be removed.

The aim of pulping is to break down the structure of wood into fibers and to make the fibers suitable for the production of paper or board. The natural function of the fibers is the complete opposite, to form a support structure that is as strong as possible.

The fibers are bound together by an intermediate lamella, which is mainly lignin. In the production of chemical pulp, the interlayer is dissolved with chemicals. The fibers are separated intact, but in addition to lignin, hemicellulose is also soluble in wood. Only about half of the wood is recovered as pulp fibers, i.e. the yield is about 50%. In mechanical methods, lignin is softened by water, heat, and repetitive mechanical stress so that the fibers can be "torn" apart. The fibers do not come off very intact, but the yield is high, 96-98%.

Mechanical pulps are made by separating the fibers bound together by wood, either by grinding the wood against an abrasive stone or by grinding the chips with a disc grinder. The former mass is commonly referred to as groundwood and the latter as grit. More advanced forms of the milling process use heat (TMP) and possibly also chemicals: (CTMP).

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Mechanical pulps are obtained in high yields, only a few percent of the weight of the wood is lost. The cost of wood per tonne of pulp will therefore remain low. Instead, energy consumption is high and energy cost is an important factor. Strong mechanical treatment also causes fiber damage and the strength properties of the paper remain relatively low, which is why the use of mechanical pulp is limited to certain products of a lower quality standard.

Previous studies have found that the strength properties of mechanical pulp can be affected by the degree of grinding as well as by the addition of binders or softwood sulphate pulp to the pulp.

The disadvantages of increasing the degree of grinding are the increasing manufacturing costs and the poor processability (dewatering) of the highly ground product. The addition of sulphate pulp to the mechanical pulp is minimized for cost reasons.

The use of binders is intended to increase the bonds between the fibers. The strength properties of the paper depend to a large extent on these bonds. By far the most widely used dry glue is cationic starch. Wood-containing, run-; saving pulps containing fine fibers and fillers requires 0.5-2% starch. It has hardly been possible to use higher amounts of starch without compromising machine runnability and paper quality.

The object of the present invention is thus to provide a solution by which the strength properties of a mechanical mass can be increased from its current level. The invention is characterized in that the fibrous product is treated chemically and / or enzymatically, whereby a binder binds to the lignin of the fibrous product. According to the invention, it has now been observed that the enzyme ·; and / or a suitable molecule could be attached to the lignin-free, easily oxidizable groups by means of a chemical. When the binder is bonded to the surface of the fiber by a chemical reaction, the binder can provide further improved strength properties, as well as increase the amount of binder used, if desired, without side effects. The bond between the binder and the fiber is provided either by oxidizing enzymes or by oxidizing radical-generating chemicals.

The strength properties can be increased by performing enzymatic treatment of the mechanical pulp with enzymes acting on lignin in the presence of certain hydrophilic group-containing substances, such as carbohydrates and proteins. The formation of a chemical bond can be carried out on differently prepared mechanical pulps, provided that the reaction is successful in the presence of lignin or its derivatives in the reaction mixture.

The purpose of either an enzymatic or chemical oxidation treatment is to provide a radical to the lignin of the fiber to which the binder is chemically bonded so that the strength properties of the pulp are substantially increased. The radical scavenger to be used is preferably laccase, lignin peroxidase, manganese peroxidase or an oxidizing radical-generating chemical such as chlorine dioxide, ozone or hydrogen peroxide together with ferro-ions. The temperature of the enzyme treatment may be in the range of 10-90 ° C, more preferably in the range of 40-70 ° C and the pH in the range of 2.0-10.0, more preferably 4.0-8.0 In addition, the redox potential must be relatively high, enzyme in the treatment of about 100-600 mV more suitably 300-500 mV and correspondingly in the treatment of chemicals more than 200 mV.

The invention is described in more detail below by means of exemplary embodiments based on laboratory experiments.

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Example 1.

20 g (ahs.k.) of waste paper and waste paperboard pulp was diluted with water to a consistency of 2.5%.

The mixture was heated to 40 ° C. Then 5% starch (Ami ring 202) was added to the mixture and mixed well. 0.5% by weight of chlorine dioxide diluted in water was added to the reaction mixture and allowed to react at 40 ° C for two hours.

The pulp was then mailed with 20 times the amount of water, thickened and analyzed.

The results describing the strength of the pulp are shown in Table 1.

In addition to the experiment illustrating the invention described above (Experiment 5), three comparative experiments (Experiments 1, 2 and 3) and additional experiments (Experiment 4 and Experiment 6) were performed, the results of which are also shown in the following Table 1. The experiments were performed as follows:

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Experiment 1 (Comparative Experiment): The pulp was not treated with chlorine dioxide. No starch was added to the pulp. In other respects, the performance and analysis of the experiment were as described above (Experiment 5).

Experiment 2 (Comparative Experiment): The pulp was not subjected to chlorine dioxide treatment. In other respects, the performance and analysis of the experiment were as described above (Experiment 5).

Experiment 3 (Comparative Experiment): The pulp was not subjected to chlorine dioxide treatment. Starch was added to the pulp in an amount of 10% of the pulp.

Experiment 4: The pulp was treated with chlorine dioxide without the addition of starch to the pulp. In other respects, the performance and analysis of the experiment were as described above (Experiment 5). The procedure of this experiment is within the scope of the present invention.

Experiment 6: The pulp was treated with chlorine dioxide by adding 10% of the amount of starch to the pulp. In other respects, the performance and analysis of the experiment were as described above (Experiment 5). The procedure of this experiment is within the scope of the present invention.

Example 2.

The unbleached TMP pulp was washed with deionized water and centrifuged. The mass was buffered with Na-citrate buffer, diluted to 2.5% consistency and heated to 40 ° C. 5% starch (oxidized, middle cationic starch) was added to the pulp and mixed well. Laccase (activity 630 U / ml) was added to the mixture in an amount of 0.1%, diluted in water and mixed thoroughly. The enzyme reaction was allowed to proceed for two hours at 40 ° C with occasional stirring. At the end of the reaction, the mass was washed.

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After washing, the enzyme activity was destroyed by heat treatment at 80-85 ° C for 10 min. Finally, the pulp was thickened, centrifuged and homogenized.

The pulps were made into 100 g sheets (SCAN-67) and tumble dried. The paper specifications of the sheets were determined according to SCAN standards.

The results describing the strength of the pulp are shown in Table 2.

In addition to the experiment illustrating the invention (Experiment 2) described above, a comparative experiment (Experiment 1) and two additional experiments (Experiment 3 and Experiment 4) were performed, the results of which are also shown in the following Table 2. The experiments were performed as follows:

Experiment 1 (Comparative Experiment): The pulp was not subjected to enzyme treatment and no starch was added to the pulp. For pulp washing and analyzes, the experiment was as described above (Experiment 2).

Experiment 3: The pulp was subjected to enzyme treatment by adding 5% (by weight of) peptone to the reaction solution instead of starch. In all other respects, the treatment was as described above (Experiment 2). The procedure of this experiment is within the scope of the present invention.

Experiment 4: Instead of enzyme treatment, the pulp was subjected to an oxidative treatment with chlorine dioxide, which was added in an amount of 0.1% of the pulp. In all other respects, the treatment was as described above (Experiment 2). The procedure of this experiment is within the scope of the present invention.

The results show that the strength can be increased in the same way when using both chlorine dioxide and the enzyme laccase as an oxidant. The results also show that pa-! si starch also peptone together with oxidation treatment increases the strength of the pulp.

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It can be seen from the results that the strength increased with the addition of the starch, which presumably acts as a binder, but the increase in strength is clearly better when the mixture was further subjected to the oxidation treatment according to the invention.

It will be clear to a person skilled in the art that the invention is not limited to the above-mentioned application example, but can be modified within the scope of the appended claims.

TABLE 2 I TEST 1 TEST 2 TEST 3 TEST 4

I I I I I I

J_ 1 (comparison) | _j_j_j_

I I I I I I

| % by weight of laccase - | 0.1 | 0.1 | |

I I I I I I

I C102% by weight | - I - I 0.1 | | starch% by weight I 5 | - | 5 |

I I I I I I

| peptone% by weight - | - | 5 | - |

I I I I I I

| freeness CSF (ml) 40 | 39 | 30 | 45 | | vetoind. Nm / g 44.6 | 55.0 | 53.3 | 54.0 |

I I I I I I

strength increase (%) | _ | 23.3 | 19.5 | 21.1 I;

Claims (9)

9 85389 A method for producing a mechanical pulp from a fibrous product, characterized in that the fibrous product is treated chemically and / or enzymatically, whereby a binder binds to the lignin of the fibrous product. Process according to Claim 1, characterized in that the chemical and / or enzymatic treatment of the fibrous product produces radicals in the lignin of the fibrous product to which the binders are attached by means of chemical bonds. Process according to Claim 1 or 2, characterized in that the binder is hydrophilic, preferably a carbohydrate and / or a protein. Process according to one of the preceding claims, characterized in that the radical generator is an oxidizing enzyme and / or an oxidizing radical-generating chemical, preferably laccase, lignin peroxidase, manganese peroxidase, hydrogen peroxide together with ferrous ions, chlorine dioxide or ozone, either alone or in mixtures. Process according to one of the preceding claims, characterized in that the enzyme treatment is carried out at a temperature in the range from 10 to 90 ° C, preferably in the range from 40 to 70 ° C, and at a pH of 2.0 to 10.0, preferably 4.0 to 8, 0. 6. Use of enzymes and / or chemicals acting on lignin together with binders to increase the strength properties in the production of mechanical pulp. Use of an enzyme and / or a chemical according to claim 6 for increasing its strength properties in the production of mechanical pulp using oxidizing enzymes and / or oxidizing radical generating chemicals. 10 85389 Use of a binder according to claim 6 for increasing the strength properties in the production of mechanical pulp, preferably using carbohydrates and / or proteins as binders. Hydrogen peroxide of laccase, lignin peroxidase, manganese peroxidase according to claims 6-8 together with Ferro ions, use of chlorine dioxide, ozone or mixtures thereof to increase the strength properties in the production of mechanical pulp. I; 11 8 5 389