A method of manufacturing a fibrous sheet material for corrugated cardboard

 

(57) Abstract:

Method for manufacturing paper for corrugation and/or planar layers in the manufacture of corrugated cardboard. In the original fibrous suspension of milled waste injected cationic starch soluble in cold water, with a degree of substitution of 0.03-0.07 per 4-20 min before dilution mass of circulating water. After that add cationic polyacrylamide with a molecular mass 5-9106while the degree of grinding diluted wastepaper pulp exceeds the degree of grinding in the beginning reflux for 2-6oSHR. The method can significantly improve the properties of paper and paperboard, in particular to increase the resistance to punching shear and in-plane compression while reducing consumption of cationic starch, and also allows you to increase the speed paper and Board machines. 2 C.p. f-crystals.

The invention relates to the manufacture of paper for corrugation and/or planar layers in the manufacture of corrugated cardboard.

A known method of manufacturing a fibrous sheet material for wrapping paper for corrugated cardboard by drawing on a base paper, with, poverhnostnogo layer made from starch-containing adhesive based product castelsilano starch and protein, obtained by grinding wheat, roots, Taro or cassava, cleaning, mixing with water, milling, processing the mixture with steam at a temperature of 50-120oC and a pressure of 1.6 bar under stirring, followed by the separation, filtration or centrifugation insoluble fibrous material (see SU, 931113,, 23.05.1987).

However, this method is very difficult technologically, requires surface treatment of the paper base and does not provide manufactured corrugated Board required physical and mechanical properties (podavlyayushee force, Wisepilot in Denison, compressive strength, and so on). In addition, this method requires a very large consumption of starch and reduce the speed of the paper machine.

There is also known a method of manufacturing a fibrous sheet material for corrugated cardboard by mixing wastepaper pulp with a hardening substance, a cationic potato starch with a degree of substitution 0,114-0,342, a sizing substance - dimer alkylbetaine or anhydrides of succinic acid, W canvas pressing and drying.

However, this method does not provide custom corrugated Board high resistance to punching shear and in-plane compression, which is caused, first of all, a high degree of substitution of cationic starch with a low molecular weight and high consumption of cationic polyacrylamide.

The closest analogue of the present invention is a method for preparing a sheet of fibrous material for corrugated cardboard, including the introduction of a fibrous suspension of milled paper strengthening agent, a cationic starch, the addition of the flocculant is a cationic polyacrylamide, dilution of the mass, the low tide paintings, his pressing and drying (see Fr. A, 28.09.2001). According to this method using cationic polyacrylamide with a molecular weight of 5104- 3,5106take it in the number of 0,005 0,050% of the mass of absolutely dry paper in the form of a mixture with clay (bentonite) and a binder (negationism starch) and enter it into the fibrous slurry prior to its dilution.

As cationic starch used is the introduction of a special sizing agent, this method does not allow for, and cationic starch only performs the role of a hardening agent. This method requires a very large number of cationic starch (2-3%) of the mass of absolutely dry paper and does not provide the received paper for corrugation and cardboard for flat layers of corrugated cardboard, and made of them corrugated Board required complex physico-mechanical properties (resistance to punching shear, resistance to in-plane compression and so on).

New technical result from the use of the present invention is to improve the physico-mechanical - increase resistance to punching shear and in-plane compression, which increased requirements in the manufacture of paper for corrugation and flat layers of cardboard in the production of corrugated cardboard, as well as reducing consumption of starch and increase speed paper and Board machines.

Specified new technical result is achieved in that in the method of manufacturing a fibrous sheet material for corrugated cardboard, including the introduction of a fibrous suspension of milled paper strengthening agent, a cationic starch added is ku, according to the invention as cationic polyacrylamide use the named polyacrylamide with a molecular weight (5-9)106and as cationic starch used the specified starch soluble in cold water, with a degree of substitution of 0.03-0.07 respectively, while the dilution of the mass are circulating water, cationic starch is introduced into the fibrous suspension for 4-20 minutes before dilution mass of circulating water in an amount of 0.6-1.2% of the mass of absolutely dry paper, and a cationic polyacrylamide add to the resulting mass after dilution of the circulating water in an amount of 0,0025-0,0040% of the mass of absolutely dry paper when the degree of grinding of dilute waste slurry in excess of the degree of grinding it at the beginning of low tide paintings (in the pressure box) 2-6oSHR.

In the original fibrous suspension of milled paper introduced a sizing agent.

As a sizing agent used rosin in the form of glue-paste, white glue or dispersion of the adhesive. As cationic starch is preferable to use starch, esterified Quaternary ammonium compounds. In the fibrous suspension is injected, preferred is the ora of the present invention was installed, the use of cationic polyacrylamide with high molecular weight, component (5-9)106and reduced his consumption, comprising 0,0025-0,0040% of the mass of absolutely dry paper, does not lead to a sharp drop in the resistivity in-plane compression and reduction of resistance to punching shear. Combined with a relatively low molecular weight cationic starch (degree of substitution is 0,03-0,07) on the grid is formed fabric with optimal structure, providing high resistance to in-plane compression and burst.

The use of cationic starch with a specified degree of substitution, exactly soluble in cold water, with the introduction of it into the fibrous suspension from the ground up and recycled paper for 4-20 minutes before low tide paper web allows you to get the flocculated mass, in which the cationic starch is almost completely adsorbed, and the resulting fibrous mass after hydrodynamic impact cleaners deflowered on thin flocculi that during the subsequent reaction with the above reduced consumption of cationic polyacrylamide and high molecular weight form of the WTO is the s-formed sheet material is paper or paperboard drops, but at the same time reducing sagasti mass (the difference in degrees of grinding) should not be too large. The decline of sagasti weight due to the excess of the degree of grinding milled paper adding cationic polyacrylamide 2-6oSHR compared with the degree of grinding of waste paper at the beginning of low tide leads to the formation of small-scale heterogeneity of not exceeding critical. The invention is illustrated by the following examples of its implementation.

Example 1. In the paper on the basis of old corrugated boxes, ground to 26oSHR, enter rosin in the form of white glue in the amount of 0.6% by weight of absolutely dry paper and aluminum sulfate to pH 5.5. Then in the resulting fibrous mass injected cationic potato starch in the amount of 12 kg per tonne of waste (1.2% of the mass of absolutely dry paper) with a degree of substitution of 0.03, after 20 minutes, the mass is diluted working register water to form a pulp (slurry) with a beating degree of the 36oSHR and in the fibrous mass is injected cationic polyacrylamide with a molecular mass of 5-106the number 0,0025% of the mass of absolutely dry waste paper. The mass is fed into the headbox, in which the degree of grinding before low tide on the net boom is ing the mass of the circulating water and the beginning of low tide paintings in the pressure box is 2%). Then spend ebb paintings, his pressing and drying. Get the paper for corrugation.

The increase of the resistance to punching shear resistance and in-plane compression of the paper is at the expense of the proposed method in comparison with the closest analogue to respectively 10 and 15%. Consumption of cationic starch is reduced at 50%.

Example 2. The method is carried out analogously to example 1 with the only difference that they take the original ground waste paper with the degree of grinding of the 36oSHR, rosin take in the form of the adhesive paste in the amount of 0.8% by weight of absolutely dry pulp, cationic starch is administered for 12 minutes before diluting the pulp circulating water. Use of cationic starch with a degree of substitution of 0.05 in the amount of 9 kg per tonne of paper (0,9% of the mass of absolutely dry paper). Take cationic polyacrylamide with a molecular mass of 7106the number 0,0040% of the mass of absolutely dry waste paper.

The beating degree of the pulp by adding cationic polyacrylamide is 42oSHR, and the beating degree of the pulp at the beginning of low tide paintings (in the pressure box) - 38oSHR. The difference of grinding equal to 4oSHR.

Izhota is the Lebanon cardboard for flat layers of corrugated cardboard from the use of the proposed method compared with the method according closest analogue is 14%. Consumption of cationic starch decreases by 40% in comparison with the method according closest analogue.

Example 3. The method is carried out analogously to example 1 with the only difference that they take the original paper with the degree of grinding 52oSHR, rosin take the form of a dispersion of the adhesive in the amount of 1.0% by weight of absolutely dry pulp, cationic starch is administered in an amount of 0.6% by weight of absolutely dry paper for 4 minutes to dilute the pulp circulating water. Use of cationic starch with a degree of substitution of 0.07. Take cationic polyacrylamide with a molecular mass of 9106the number 0,0035% of the mass of absolutely dry waste paper. The beating degree of the pulp by adding cationic polyacrylamide is 46oSHR, and at the beginning of low tide paintings (in the pressure box) 40oSHR. The difference of grinding when adding a cationic polyacrylamide to dilute the pulp circulating water and the beginning of low tide blade is 6oSHR, the pH of the mass in the pressure box is 6.5. Made as a corrugating paper and cardboard for flat layers of corrugated cardboard the same composition. The increase soprotivlenie 11,9 and 14.7%, and increase resistance to in-plane compression fluting - 12%. Consumption of cationic starch decreases by 32%.

As can be seen from the examples, the proposed method can significantly improve physical and mechanical properties of paper and paperboard, in particular, to increase the punching shear resistance and resistance to in-plane compression while reducing consumption of cationic starch, which, in turn, leads to increased speed paper and Board machines.

1. A method of manufacturing a fibrous sheet material for corrugated cardboard, including the introduction of a fibrous suspension of milled paper strengthening agent, a cationic starch, the addition of the flocculant is a cationic polyacrylamide, dilution of the mass, the low tide paintings, his pressing and drying, characterized in that the cationic polyacrylamide use the named polyacrylamide with a molecular weight (5-9)106and as cationic starch used the specified starch soluble in cold water, with a degree of substitution of 0.03-0.07 respectively, while the dilution of the mass are circulating water and the cation of the dry waste paper, and cationic polyacrylamide add to the resulting mass after dilution of the circulating water in an amount of 0,0025-0,0040% of the mass of absolutely dry paper when the degree of grinding of the diluted mass is greater than the degree of grinding it at the beginning of low tide paintings on 2-6oSHR.

2. The method according to p. 1, characterized in that the source of the fibrous suspension of milled paper introduced a sizing agent.

3. The method according to p. 1, characterized in that as a sizing agent use rosin in the form of glue-paste, white glue or dispersion of the adhesive.

 

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