RU2434091C1 - Composition to make chalk overlay paper - Google Patents

Abstract

FIELD: textile; paper.

SUBSTANCE: composition contains a fibrous mixture from chemical and thermomechanical mass and cellulose. The fibrous mixture contains birch leached chemical and thermomechanical mass with extent of grinding 60-125 ml (CSF) and cellulose with grinding extent of 350-500 ml (CSF) at the specified ratio of components. The cellulose in the fibrous mixture is a leached pine sulfate cellulose and/or pine sulphite cellulose, or pine cellulose, and/or leaf cellulose.

EFFECT: expansion of leaf-bearing soft woods due to using birch leached chemical and thermomechanical mass to prepare a fibrous semi-finished product to produce paper with high physical mechanical indices to ensure extent of whiteness.

3 cl, 1 tbl

Description

The invention relates to the pulp and paper industry, to the composition of the pulp for the production of coated grades of paper that require high quality base paper, in particular, can be used to obtain light coated paper.

Known paper pulp for the manufacture of base paper used for veneering plywood on.with. No. 1756442, D21H 11/10, 1992. The paper pulp contains 25-45% sulphate bleached softwood pulp, 5-20% thermomechanical or chemical-thermomechanical pulp from spruce or spruce and aspen chips, and sulphate bleached hardwood pulp. Grinding bleached sulfate coniferous and deciduous mass is carried out separately, to the degree of grinding ° W: coniferous 26-28, deciduous 28-32. The disadvantage is the low degree of whiteness of the resulting paper, the limited use of natural forest resources for its production.

Known pulp for the manufacture of paper intended for the packaging of food products on machines at.with. No. 996596, D21H 3/00, 1983. The pulp contains cellulose and thermo-chemical-mechanical pulp obtained by chemical treatment of wood chips with a mixture of sodium carbonate or bicarbonate, caustic soda and sodium sulfide. Thermomechanical pulp is obtained from hardwood chips, a mixture of deciduous and coniferous wood and one coniferous wood. The disadvantages are the low degree of whiteness and the strength of the paper obtained from the pulp.

As the closest analogue to the claimed technical solution, the invention was selected according to A.S. No. 632790, D21H 3/00, 1978. The pulp for the manufacture of paper intended for packaging and packaging of food products on machines, contains 30-50 wt.% Cellulose and 50-70 wt.% Deciduous chemical-thermal refiner wood pulp. Chemical-thermal wood is obtained by grinding aspen chips in a disk mill with preliminary chemical-thermal treatment. The disadvantage is the low degree of whiteness of the resulting paper due to the use of aspen chips, which gives the paper a yellow color. In addition, limiting the use of hardwood only aspen leads to insufficient use of hardwood resources in the Russian Federation. Low characteristics of the resulting mass, such as strength and brightness, prevent the use of pulp for the manufacture of coated paper.

The technical task of the invention is the expansion of a number of hardwoods used to produce paper with high physical and mechanical properties.

The technical result is to obtain the possibility of using hardwood, in addition to aspen, while ensuring a degree of whiteness and strength sufficient to produce coated paper.

The technical result is ensured by the fact that in the composition for the production of coated paper containing a fibrous mixture of chemical-thermomechanical pulp and cellulose according to the invention, the fibrous mixture contains a birch bleached chemical-thermomechanical pulp with a grinding degree of 60-125 ml (CSF) and cellulose with a degree grinding 350-500 ml (CSF) in the following ratio, wt.%:

birch bleached chemical thermomechanical mass 60-95 cellulose 5-40.

As cellulose, the composition comprises bleached softwood sulphate pulp and / or softwood sulphite pulp. Along with softwood pulp, the composition may contain hardwood pulp.

The technical result is achieved due to the fact that the paper pulp, in addition to the traditionally used softwood pulp, contains birch bleached chemical thermomechanical pulp (BHTMM), which occupies a large part - 60-95 wt.% In the total composition. The use of birch BHTMM can significantly expand the possibilities of using natural resources in Russia. The proportion of forested land with a predominance of birch in the Russian Federation is 13%, in the Urals region - 29%, including in the Kurgan region - 51%, Perm region - 24%, Chelyabinsk region - 47%, Bashkiria - 25% , Sverdlovsk region - 30% (Forest tax reference book for the forests of the Urals, 1991). It is known that paper-forming properties of conifers are higher compared to hardwood. Their fibers are longer and more flexible, have better mechanical properties. Wood fibers are hollow cylinders. The length of softwood fibers is 2-4 mm, the diameter is 25 microns, the length of birch fibers is about 1 mm, the diameter is 10 mm. The ability for interfiber bonding in coniferous fibers is higher than in birch fibers due to its greater length and flexibility. Birch fibers have a thicker cylinder wall, due to which they have a higher stiffness. The strength of birch fiber paper is lower than the strength of coniferous fiber paper. However, the degree of whiteness of paper from birch fibers is quite high due to the characteristics of the chromoform groups of birch lignin. The increase in the strength of paper made from paper pulp using birch BHTMM is ensured by the optimal degree of grinding of all components included in the composition. For a fibrous prefabricated mixture of birch bleached chemical-thermomechanical pulp, the degree of grinding is 60-125 ml (CSF), for bleached softwood sulphate pulp - 350-500 ml (CSF). At this degree of grinding, the birch fibers become flexible, elastic, due to which their adhesion area to neighboring fibers increases, in addition, small hooks, the so-called nano-fibrils, are formed on the surface of birch fibers, enhancing the degree of adhesion to adjacent birch fibers and sulphate cellulose fibers . The degree of grinding of these two components, indicated above, also contributes to the best adhesion of birch fibers. It was experimentally found that with the indicated degrees of grinding of all components, the strength of the resulting paper is maximum. Changing the degree of grinding below these values leads to worse adhesion of the fibers, increasing the degree of grinding leads to abrasion and destruction of the fibers. At the indicated degrees of grinding of all components, the content of BHTM can vary in the range of 60-95 wt.%, This achieves the required degree of brightness of the resulting coated paper. To ensure the strength of the paper, cellulose is used in the indicated amounts at given degrees of grinding. In the composition for the production of coated paper, bleached softwood sulphate pulp is mainly used. However, it can be partially or completely replaced with sulphite softwood pulp, in addition, hardwood pulp can be used along with softwood pulp.

Studies of the physicomechanical properties of the experimental images showed that the introduction of an additional grinding stage and an increase in the degree of grinding of BHTMM from 110 to 70 ml CSF leads to an increase in strength properties - tear resistance and tearing resistance, surface strength. The energy of the interfiber bonds increased from 256 to 330 J / m ² and exceeded the value of 280 J / m ² for the standard BHTMM from spruce coniferous wood. This is explained by the appearance of micro- and nanofibrils on the surface of the fibers, additional free hydroxyl groups on the surface of hemicelluloses and lignin, which are formed during the additional grinding stage, carried out using modern grinding equipment, and ensure the formation of bonds in the sheet at the level of micro- and nanofibrils. On the other hand, the shortening of the fibers during the grinding process leads to the appearance of small fibers. Fine fiber, in turn, fills the voids between long fibers, thereby reducing air permeability and roughness.

When using the inventive paper pulp in the manufacture of paper with improved optical properties, such as whiteness and opacity while maintaining high bulk and the required strength with a maximum content of birch BHTMM, the standard technology for producing coated paper is used in the composition of the semi-finished product. The proposed composition allows the production of base paper at speeds of at least 1700 m / min with good efficiency of the canvas. The strength of the paper allows you to withstand these speeds without interruption of the process due to tearing of the canvas. The whiteness of birch BHTMM is at least 80% ISO, the whiteness of bleached sulphate softwood pulp is at least 87% ISO. Their composition, used to develop the basis of light coated paper, allows you to get a product with a high degree of whiteness - more than 80% ISO, low roughness and high mechanical strength. The content of filler and hardening additives does not exceed the level in existing light coated papers.

Comparative physical and mechanical characteristics of paper obtained using birch BHTMM and using spruce BHTMM are shown in the table.

Properties The content of BHTM in the paper composition,% birch 80 birch 80 spruce 65 The degree of grinding of SCF according to the "Canadian standard", ml 110 70 110 The mass of paper with an area of 1 m ² , g 56 58 58 Thickness, microns 71 72 72 Tear Resistance, Nm / g - machine direction 60 78 82 - transverse direction twenty 25 21 Tear resistance, mNm ² / g - machine direction 6.0 8.0 5,0 - transverse direction 3.3 5,0 5,0 The energy of interfiber bonds, J / m ² 256 330 280 Bentsen Breathability, ml / min 180 160 250 Bentsen roughness, ml / min front / net 230/270 180/220 170/226 Parker PPS 10 roughness, microns front / mesh 6.5 / 5.4 5.7 / 6.1 5.1 / 6.2 Resistance to plucking according to Dennison, No. front / mesh 8/8 10/9 8/8 White ISO,% 84 86 84 Opacity,% 84 81 85

Thus, the claimed invention allows to expand the use of hardwood due to the use of birch in the preparation of a fibrous semi-finished product mixture BHTMM while providing physical and mechanical properties necessary for the manufacture of coated paper.

Claims (3)

1. Composition for the production of coated paper containing a fibrous mixture of chemothermomechanical pulp and cellulose, characterized in that the fibrous mixture contains birch bleached chemothermomechanical pulp with a degree of grinding of 60-125 ml (CSF) and cellulose with a degree of grinding of 350-500 ml (CSF) in the following ratio, wt.%:
birch bleached chemical thermomechanical mass 60-95 cellulose 5-40 2. The composition according to claim 1, characterized in that the pulp contains bleached softwood sulphate cellulose and / or softwood sulphite pulp. 3. The composition according to claim 1, characterized in that the quality of the cellulose contains softwood pulp and / or hardwood pulp.