FI108245B - Process for producing fibre raw material and fibre raw material - Google Patents

Description

108245

The present invention relates to a process for the manufacture of a fibrous raw material and to a process for the manufacture of a fibrous product. The method comprises a process for treating a fibrous raw material such that the web-based products thereof are more fluffy than the corresponding products made by known methods. The fibrous raw material is fiber produced by the method.

10 In this application, the dry matter content as a percentage is used to indicate the degree of dryness of wood fibers. Percentages are by weight unless otherwise stated.

It is clear that the fiber used affects the quality of paper products. In some grades of paper, eucalyptus fibers have been found to be superior to other wood fibers because of their fiber properties which give paper the desired properties. Eucalyptus fibers are relatively short, the fibers are relatively thick relative to the fiber diameter, and the fiber diameter is small. Compared to eucalyptus fiber, other hardwood fibers, such as birch fibers, and coniferous fibers are relatively thinner in fiber. To illustrate the difference in fiber properties between different wood species, Table 1 shows typical fiber properties of some wood species.

25 Table 1. Typical fiber properties of some wood species.

Wood species- »Eucalyptus Birch Spruce Pine

Feature 4_____

Length (mm) _J ^ O_JJ_3J_3 ^) _

Diameter (pm) 16_22_20 - 60 20 - 70

Fiber Wall Package 3.0 3.0 5.5 6.0 Mouth (pm) _____

Some grades of paper have the advantage of being made from fibers that give the paper structure a fluffy appearance, i.e. an open structure and a product that is thicker than dry matter. Such paper grades include e.g. some grades of fine paper, crepe paper and dry paper. Openness and the resulting sheet thickness of 2 108245 give copy paper, for example, a good edge, opacity and convenience for fast two-sided copying. For products requiring a fluffy structure, the properties of eucalyptus fiber are naturally more appropriate than those of, for example, birch or softwood. The manufacture of bulk products requires just such a fiber which has a high ratio of fiber wall thickness to fiber diameter. In this case, the fibers do not flatten in the papermaking process, but retain their circular tubular cross-section, increasing the paper thickness and stiffness. In order to successfully produce bulky products from non-eucalyptus fibers, wood fibers may be modified to achieve the desired properties.

There are several known methods for changing the properties of wood fibers. It is generally known that wood fiber swollen by the action of water curls as it dries and that grinding can enhance this effect.

US 4,464,224 discloses a method in which dry fibers are added to the papermaking process just before the headbox, for example on the suction side of the feed pump. The dry fibers added to the process are fluff pulp and when used, the paper becomes very fluffy. The method is utilized, for example, in the production of crepe paper.

US 5,190,563 discloses a process in which wood fibers are mechanically separated from each other into single fibers, treated with polycarboxylic acid, first dried by flake drying and then allowed to be at a suitable high temperature until crosslinking occurs.

30

US 4,888,093 discloses a process wherein the individual wood fibers are treated with dialdehydes, preferably glutaraldehyde, and allowed to be at the temperature at which the crosslinking occurs. Maximum cross-linking is achieved when the moisture content of the fibers is less than 5%.

US 5,366,591 discloses a method in which cross-linking is carried out with an N-sulfatoimide ring structure. After chemical treatment 35 3 108245, the fibers are first dried and then roasted at a hot temperature to allow crosslinking.

US 4,889,595 discloses a method in which individual wood fibers are treated with dialdehydes, preferably glutaraldehyde, and allowed to be at a temperature at which the crosslinking takes place and the fiber is washed with an alkaline solution to remove residual crosslinking agents from the fiber.

US 5,779,857 discloses a method in which cellulose fibers are impregnated with a crosslinking agent and at least one polyfunctional alcohol, dried cellulose fibers, defibrated and crosslinked hot. The crosslinking agent is dihydroxyethyleneurea, dimethyldihydroxyethyleneurea, and derivatives thereof.

The above-mentioned known methods involve treatment of wood fibers with a crosslinking chemical and drying, after which the fibers have to be further treated at a suitable high temperature for the crosslinking to take place. After such treatment, the wood fibers have a very high dry matter content and may cause problems e.g. because the water absorbency of the dried cellulose is impaired by corneal desaturation. The methods proposed for industrial utilization are relatively complex.

By the process of the invention, the fibers can be processed so that the fluffiness of the web-formed products thereof is greater than that of the products produced by the conventional methods, and the process is simpler than the technique disclosed in the prior art. To accomplish this, the process according to the invention is characterized in that the wood fibers are dried separately from each other in such a way that no bonding between the fibers 30 occurs and the dry matter content of said wood fibers after drying is 50-90%. The fiber raw material thus obtained is characterized in that it has a dry matter content of 50-90%. The process utilizing the fibrous raw material in question to produce the product is characterized in that 35 separately dried fibers having a dry matter content of 50-90% at the end of the drying are added to the web making process. The drying process is readily industrially applicable and can be applied to both ground and unground fibers. The fibers can be dried either as such or treated with locking chemicals. However, the most bulky products are obtained when the fiber raw material preparation comprises the following steps: 5 - high consistency grinding -1 u ction of chemical treatment - flake drying

The purpose of the milling is to modify the fiber to the desired paper product 10. The fiber is first milled by high-consistency milling, which serves to soften the fibrous structure of the fiber wall and cause the fibers to absorb water to the fiber wall. Grinding milling also causes the fibers to curl. The degree of high-consistency milling is described by the SR number, for example, the SR number 25 represents mild grinding and the SR-15 number 40 represents moderate grinding.

After or during milling, a locking chemical treatment is performed in which the locking chemical penetrates between the loose fibrils in the fiber wall. During drying, the chemical locks the fibrils together so that the fiber does not lose its posture when wet. As locking chemicals, for example, wet-cell resins, starch, fatty acid derivatives, cyanuric halides or derivatives thereof may be used. Colloidal hemicellulose formed between the fibrils can also act as a sufficient locking agent. In chemothermomechanical pulp 25 (CTMP), lignin acts as a locking chemical.

• • 1 · - Next, the fibers are dried so that when they dry they are allowed to shrink, whereupon they become curled and the drying chemical activated locking chemical locks the completely dried form of the fiber. The separated wood fibers are dried by flake drying so that their dry matter content at the end of the drying is 50-90% by weight. The optimum solids content depends on e.g. grinding degree and locking chemical, but adjusting the dry matter content can achieve maximum foam for each grinding degree and locking chemistry-35 L. With most process values and locking chemistry, the optimum is achieved with a solids content of 60-80%. Foam does not reach its maximum value of 5 108245 if the dry matter content is too low and, on the other hand, the foam decreases if the dry matter content of the fibers is too high.

The treated fibers are used in different grades of fine and dry paper. In fine paper making, the fibrous raw material is added to the suction side of the headbox feed pump, and the wet mass in the form of an aqueous suspension is formed in a papermaking machine to a continuous paper web, which is dried and finished with the necessary finishing operations. In dry papermaking, the addition is made to the air stream of 10 dry webs and the fiber raw material is formed into a continuous web by a dry process. The product may be formed solely from the fibers of the invention or may be blended with conventional fibers in fine or dry paper making.

The invention will now be described by way of illustration and examples. The figure shows the basic operation of the drying apparatus.

As shown, the drying gas passes through the tube 1 at a certain flow rate, and the wet fibers separated are fed through, for example, compressed air through valve 2. Sufficiently dried fibers are separated from the gas stream in cyclone 3. The fibers can be dried using either a hot air stream or superheated steam.

The friability of sheets formed from fibers treated in accordance with the invention has been compared with sheets made from conventionally manufactured fibers. Conventionally prepared sheets are those sheets which are made from pulp, which is commonly used in papermaking and is generally known in the art. The fiber used in the examples is bleached birch sulfate pulp.

30

Example 1.

A total of six samples were wetted to a dry solids content of 35% and three samples were milled to SR number 25. Cyanuric chloride was used as the locking chemical. Cyanuric chloride is chemically bonded to the OH groups of cellulose to form internal fiber bonds. Two 108245 6 non-milled and two milled samples were treated with cyanuric chloride. The following samples were obtained: - Unground and untreated 5 - Unground and containing 2% cyanuric chloride - Unground and 4% cyanuric chloride - Powdered and untreated - Powdered and 2% cyanuric chloride - Powdered and 4% cyanuric chloride 10 the samples had a dry solids content of 30-40%. The loose fibers were fed to a flake drying apparatus using hot air as the drying gas. The fibers were dried using various temperatures and hot air flow rates. The dry solids content of the fibers at the end of drying was different due to both the process parameters and the changed properties of the fiber due to the treatments. The results of the experiments are shown in Tables 2-7.

20 Table 2. Flake Drying Process Conditions, Dry Fiber Content of Wood Fibers, and Density of Sheets of Dried, Non-Grinded and Non Chemically Treated Fibers. increase in bulk compared to sheets made from conventionally unground pulp (bulk density 1.97 to 25 cm3 / g).

•

Flake-Drying - ^ - Powder. Paper Sheet Flux — Dry Man Flow (%) Dry Flow (%) Temperature Speed - At the End - (cm3 / g) (° C) (m / s) 140_JJ_68T) _2.05_ + 4_ 157_20_95 ^ 3_2 ^ 2_ + 3_ 207_22_82 ^ 4_2 ^ 07_ + 5_ 210_Vj_72J> _2 ^) 5_ + 4_ 215__11_704_2J1_ + 7_ 215 | 21 172.8 12.13 [+8 7 108245

Table 3. Flake Drying Process Conditions, Dry Fiber Content of Wood Fibers, and Fluffiness and Flow Increase of Flaked Dried, Paperless Fibers containing 2% Cyanuric Chloride as compared to 1.97 cm3 / cm3 of conventionally unground pulp.

Flake Dryer Dry Dry Paper Sheet Flow Drying Man Flow (%) Drying Dry Elevation (%) Temperature Speed End (cm3 / g) m_M§} ____ 140_JJ_68J_OJJ_ + Z_ 157_20_82,5_008_ + 6_ 207_22_64J) \ _787_2J1_ ± L_ 215_JJ_606_2J6_ + 10_ 215 | 21 | 81.1 | 2.16 1 + 10

Table 4. Flake Drying Process Conditions, Dry Fiber Content of Wood Fibers, and Fluffiness and Flux Increase of Flaked Dried, Paperless Fibers Containing 4% Cyanuric Chloride Compounds relative to 1.97 g / cm3 of non-ground pulp.

15 ______

Flake Dryer Dry Dry Paper Sheet Drying Flow Rate (% J Dry Dry Increase (%) Temperature Speed End thereof "(cm3 / g) (° C) _ (m / s) ~ ____ 140 11_617_OJ2_ + 8_ 157_20_68J_2J9_ + 11_ 207_ 22_67 ^ _2J5_ + 11_ 210_JJ_73J_030_ + Y7_ 215_JJ_61 ^ 6_026_ + 15_ 215 121 89.7 2.21 1 + 12 8 108245

Table 5. Flake Drying Process Conditions, Dry Fiber Content of Wood Fibers, and Fluffiness and Increase Foam of Paper Sheets Made from Flake-Dried, SR-25 Pulp and Non-Chemically Treated Wood Fibers Compared to Conventional SR Number 5 to 25 g / kg Pulp Sheets ).

Flake Dry Dry Dry Paper Sheet Flow Drying Flow (%) Dry Dry Increase (%) Temperature at its End (cm3 / g) (° C) (m / s) ____ 140_JM__62J_JJJ__ + 34_ 157_20_69,5 2, 16 + 57_ 207_22_605_2,04_ + 48_ 210_JM_ 68.8__ 2.04 + 48_ 215_JM__ 73.6 2.33_ + § £ _ 215 | 21 [75.7 | 2.14 [+60

Table 6. Flake Drying Process Conditions, Dry Fiber Content of Wood Fibers, and Fluffiness and Increase Foaming of Paper Sheets Made from Flake Dried, SR Number 25 and 2% Cyanuric Chloride Compared to Conventional SR Number 25 / Cd g).

15

Flake Drying Drying Paper Sheet Flow Drying Man Flow (%) Drying Dry Elevation (%) Temperature Speed End thereof (cm3 / g) m_Ms) ____ 65_ 215_JM_504_016_ + 57_ 215 21 78.8 12.46 +78 9 108245

Table 7. Flake Drying Process Conditions, Dry Fiber Content of Wood Fibers, and Fluffiness and Increase in Density of Paper Sheets Made from Flake Dried, SR Number 25 and 4% Cyanuric Chloride Compared to Conventional SR Number 5 to 25 W / g).

Flake Dryer Dry Dry Paper Sheet Flow Drying Flow (%) Drying Dry Elevation (%) Temperature Speed End (cm3 / g) (° C) (m / s) ___ 140_JM_56.6 1,82 + 32_ 157_20_65J_j2j09_ + 51_ 207_22_65J5_2 / 16_ + 57_ 210_JM_6903_2j47_ + 79_ 215_JM_54J5_2j2g_ + 59_ 215 I2I | 74.9 2.45 | +78

Example 2.

10

The wood fibers were dried separately with a plate having a surface temperature of 95 ° C. Paper sheets were prepared from the differently treated fibers (treatments in Table 8), with the fluff and tensile index measured (results in Table 8). It was found that the fluffiness is slightly reduced when the fibers are treated with starch, but at the same time the tensile index is improved. The increase in bulk is clear for all samples compared to conventionally prepared sheets of paper.

10108245

Table 8. Density of paper sheets made from individually dried wood fibers, increase in dampness relative to conventional sheets and tensile index (standard sheets: 1.91 cm3 / g unground, 1.45 cm3 / g for SR and 1.40 for SR 34 5 cc / g). The starch content is 1,5% by weight of the fiber, traditionally known as Raisamyl 145.

Mass Density Density Tensile Index _ (cm3 / g) _increase (%) (Nm / g) _

Powder-free, chemical-free 2.0 +5 19.4 dirt treatment ____

Ground mat, treated with 1.97 +3 27.5 starch powdered to ____ SR number 25, not 2.2 +52 18.5 chemical treatment ____ powdered to SR number 25, 1.97 +36 28.1 starch powdered to SR number 34, no 1,93 +38 26,2 chemical treatments ____ powdered to SR 34, 1,86 +33 32,2 starch treated | ___

Example 3.

10 -

Both hot air and superheated steam were used as the drying medium. The effect of different process parameters on fluff was tested. ........ - '- H 108245

Table 9. Process conditions for flake drying, dry solids content of non-chemically treated, non-chemically treated wood fibers, and fluffiness and fluffiness of paper sheets made from such wood fibers compared to conventionally manufactured paper sheets (g / cm3).

Drying - Media Mass - Dry - Foaming Foaming temperature Flow rate Flow rate (%) (cm3 / g) Increase in temperature (° C) Speed (m / s) (kg / h) Drying (%)

Curing medium for drying ___ bag___ 200 19.6 - - 2.44 +40 air______ 200 8.8 - 56 2.33 +34 air______ 200 7.7 - 66 2.22 +28 air______ 260 8.4 - 63 2, 24 +29 air_______ 330 9.3 - 77 2.36 +36 air______ 200 7.7 - 66 2.20 +26 steam ______ 210 48 165 79 2.77 +59 steam _______ 220 - - 59 2.38 +37 steam ______ 250 53 165 69 2.28 +31 steam _______ 265 - - - 2.75 +58 steam ______ 265 - - 77 2.25 +29 steam ______ 335 61 165 89 2.60 +49 steam ______: 336 82 2.43 +40 steam ______ 403 - - 84 2.31 +33 Steam _____

Example 4.

12108245

The fibers were ground to an SR of 25. The drying medium used both 5 hot air and superheated steam. The effect of various process parameters on foaming was tested.

Table 10. Flake drying process conditions, dry matter content of non-chemical wood fibers pulverized to SR number 25 at the end of drying, and fluffiness and fluffiness of paper sheets made from such wood fibers compared to conventionally produced sheets of paper / cm3.

Drying- Media Mass- Dry- Foaming Foaming temperature Flow rate Flow rate (%) (cm3 / g) Increase in temperature (° C) Length (m / s) (kg / h) Drying (%) Medium at end ___of the bag___ 292 11 10.8 68 2.28 +31 air_______ 350 10 9.6 60 2.18 +25 air______ 375 10 9.6 70 2.53 +46 air______ 270 33 100 59 2.36 +36

IfiH________ 298 35 100 75 2.51 +44 Ä ______ 333 37 100 73 2.52 +45 steam ______ 346 37 100 61 2.24 +29 steam ______ 387 39 100 63 2.10 +21 steam ______ 394 40 100 70 2.46 +42 steam _____

Example 5.

13 1 08 2 4 * 5

The fibers were milled to SR 40. The drying medium used was both 5 hot air and superheated steam. The effect of various process parameters on foaming was tested.

Table 1. Process conditions for flake drying, dry matter content of non-chemical wood fibers pulverized to SR 40 at the end of drying, and fluffiness and fluffiness of paper sheets made from these wood fibers compared to conventionally manufactured paper sheets (1.5 g / cm3 paper).

Drying- Media Mass- Dry- Foaming Foaming temperature Flow rate Flow rate (%) (cm3 / g) Increase (° C) Length (m / s) (kg / h) Drying (%) Medium at end ___of the bag___ 292 11 10.8 53 2.80 +79 air______ 350 10 9.6 45 2.47 +57 air______ 375 10 9.6 55 2.60 +66 air______ 270 33 100 45 2.41 +54 steam ______: - 298 35 100 50 2.77 +77 steam _______ 333 '37 100 57 2.75 +75 ~ "steam ______' 346 37 100 55 2.53 +61 steam ______ 387 39 100 52 2.64 +68 steam ______ 394 40 100 60 2.63 + 67 steam _____ 14

Example 6. 108245

The fibers were milled to SR number 25 and treated with wet bone resin. Both hot air and superheated steam were used as the drying medium.

5 The effect of different process parameters on fluff was tested.

Table 12. Process conditions for pulverized, wet-resin treated and individually dried wood fibers and the pulverulence and increase in pulverity of paper sheets made from such fibers as compared to conventionally dried pulp and pulp SRR 25 is 1.74 cm 3 / g). The wet scrub resin used is an epichlorohydrin modified polyamide resin under the trade name Kymene SLX2.

15 __________

Drying- Media Mass- Dry- Foaming Foaming temperature Flow rate Flow rate (%) (cm3 / g) Increase (° C) Length (m / s) (kg / h) Drying (%) Medium at end ___of the bag___ 350 10 9.6 59 2.22 +28 air______ 200 32 100 59 3.10 +78 steam ______ 266 35 100 69 3.05 +75 steam ______ · 270 33 100 53 3.18 +83 steam ______ 321 37 100 66 2.88 +66 steam _____; __ 346 36 100 61 2.83 +63 steam ______ 387 39 100 65 2.82 +62 steam ______ 420 41 100 66 2.93 +68 steam ______ 420 41 100 71 3.13 +80 steam _____ 15 108245

The above examples do not limit the invention, but the process and the fiber raw material according to the invention may vary within the scope of the claims. Fiber grinding and / or locking chemical treatment is not always necessary. The apparatus used for drying may be very different from the principle diagram shown in this application. The main thing is that the fibers are dried separately and the dry matter content of the wood fibers after drying is 50-90%.

Λ

Claims (15)

1. A method for increasing bulk of products made from wood fibers, characterized in that the process comprises drying the wood fibers separately from each other, so that it does not sever bonds between fibers and the drying content of ifr. wood cut in weight percent after drying is 50-90%. Process according to claim 1, characterized in that the wood fibers are flake dried in an air or meadow stream. Process according to any of the preceding claims, characterized in that the wood fibers are ground by high-consistency grinding prior to drying to a suitable SR number. 15 Method according to claim 3, characterized in that the wood fibers are ground to the SR number 25-40. Process according to any of the preceding claims, characterized in that, in connection with or after the high-consistency grinding, the wood fibers are treated with a reading chemical. Process according to any of the preceding claims, characterized in that the reading chemical is hydrogen resin, starch, acid anuric halide or a derivative of anic anuric halide. Process according to claim 6, characterized in that the reading chemical is acid urea halide or its derivatives. 8. Fiber raw material, characterized in that it consists of separately dried wood fibers from each other, the dry content of which is 50-90%. * 9. A fiber raw material according to claim 8, characterized in that it is ground to a suitable SR number. 35 10. A fiber raw material according to claim 9, characterized in that the wood fibers are main to the SR number 25-40. • · 108245 Fiber raw material according to any of the preceding claims, characterized in that it has been treated with a reading chemical. Fiber raw material according to claim 11, characterized in that it has been treated with hydrogen-rich resin, starch, cyanuric halide or a cyanuric halide derivative. Fiber raw material according to claim 12, characterized in that it has been treated with cyanuric halide or a derivative of cyanuric halide. 10 14. A process for the manufacture of a wood fiber product, characterized in that, separately from each other, dried wood fibers, whose dry weight content is 50-90%, are blended into the web manufacturing process. 15. A method according to claim 14, characterized in that said wood fibers are measured in the inlet of the paper machine or in the air stream in the fiber web manufacture by a dry process method. »· • m · i · *