SU887670A1 - Paper pulp production method - Google Patents

Description

(54) METHOD OF PREPARING THE PAPER MASS

The invention relates to mass treatment methods for the manufacture of hydrophobic fiber sheet materials and is intended for use in the manufacture of paper and paperboard. The classic way for dp to impart hydrophobic properties to fibrous materials is to introduce a pre-milled fibrous mass of a dispersion of a hydrophobic agent of a curing agent and to deposit particles of this dispersion on the fibers using a coagulant. drying fibrous materials necessary hydrophobicity. There is a known method for producing paper pulp, according to which polyethylene imine in an amount of 0.8-1.0% is added to a cellulosic dispersion containing dye and latex to improve the hydrophobic properties of paper. However, synthetic latex in combination with polyethylenimine does not give paper and cardboard quite high hydrophobic. However, there is a risk of the sewage becoming contaminated with latex. There is also known a method for producing paper, including the introduction of paraffin dispersion (up to 5%) and aluminum sulphate (up to 5%) into lignocellulosic fibrous material as coagulant 2. The disadvantage of this method is acidic (pH 4-5), which is necessary for the sizing process in the presence of aluminum sulphate and the low retention of the sizing dispersion. Closest to the proposed method is a method for producing paper pulp, including the introduction of paraffin dispersion into the fiber suspension, followed by the deposition of particles of this dispersion on fibers with

using polyethyleneimine copolymer with acrylonitrile GZ.

However, for a number of paper types, increased hydrophobicity is required compared to that achieved by a known method 33.

The aim of the invention is to increase the hydrophobicity and strength of paper.

This is achieved in that according to the proposed method of producing paper pulp, including the introduction of paraffin dispersion (PD) into the fiber suspension followed by cooling of its particles on the fibers with polyethyleneimine copolymer with acrylonitrile (PEI), the fiber suspension is treated with ultrasound before and / or after the introduction of steam. (US) with an oscillation frequency of 21-23 ktu for 170-190 s.

The ultrasonic treatment is further subjected to a fibrous suspension after the introduction of a copolymer of polyethyleneimine with acrylonitrile.

Ultrasonic treatment of the mass containing the sizing dispersion results in a uniform distribution of the crushed AP particles on the fibers and an improvement in the structure of the interfiber bonds of cellulose.

The choice of the frequency of ultrasound is determined by economic considerations. Obtaining an ultrasound with a low frequency is less expensive than obtaining a high-frequency ultrasound.

In order to determine the optimal treatment of the pulp of the ultrasound, the dependence of the breaking length of the paper obtained was established over time. processing pulp ultrasound (table. ij

Table I

Continued table.

From tab. 1 that when increasing the ultrasonic processing time to 180 s, a significant improvement in the breaking length of paper occurs. With a further increase in the ultrasonic treatment time, the strength of the paper increases slightly.

To prepare paper pulp, bleached sulphite pulp (SBC) is used, ground to a concentration of 1%. As a sizing agent - 5% paraffin dispersion. Coagul nt - 0.5% solution of PEI.

Example 1. 250 ml of paper pulp (5 g of dry pulp is treated with ultrasound for 180 seconds. 5 wt.% Paraffin dispersion is added and stirred for 60 with a mechanical stirrer, then 0.5 wt.% PEI is added and mixed within 30 seconds, paper samples are made from the prepared mass and are tested according to standard methods.

Example 2. The pulp is prepared analogously to example 1, only the ultrasonic treatment is carried out in two steps: before the introduction of PD (90 s) and after the introduction of PD (90 s).

Example 3. The pulp is prepared as in Example 1, the ultrasonic treatment is carried out in two steps: before the introduction of PEI (90 seconds) and after the introduction of PEI (90 seconds).

Example 4. The pulp is prepared analogously to example 1, the ultrasonic treatment is carried out in three steps: before the introduction of PD (60 s), after the introduction of PD (60 s) and after the introduction of PEI (60 s)

Laboratory samples of paper with a mass of 1 m 80 g are made on a TsBTF apparatus using a standard procedure.

Physico-mechanical properties of paper obtained by a known method Gz and processed by the proposed method, lead to table. 2

Table

Claims (2)

Claim 1. A method of producing paper pulp, comprising introducing a paraffin dispersion into a fibrous suspension followed by precipitation of its particles on the fibers by introducing polyethyleneimine-acrylonitrile copolymers into them, characterized in that, in order to increase the hydrophobicity and mechanical strength of the paper, the fibrous suspension is up to and / or after the introduction of a paraffin dispersion, they are sonicated with an oscillation frequency of 21-23 kHz for 170-190 s. 2. The method according to π. 1, characterized in that the ultrasonic treatment is additionally subjected to a fibrous suspension after the introduction of a copolymer of polyethyleneimine with acrylonitrile.