RU2317361C2 - Composition for manufacture of paper and method for increasing extent of retention and/or dehydration in the same - Google Patents

Abstract

FIELD: paper making.

SUBSTANCE: composition for manufacture of paper has flocculating cationic polymeric retention means, phenol resin, and polyethylene oxide. Cationic polymeric retention means is liquid aqueous cationic polymer dispersion free of solvent and oil phase and having viscosity of from 2,000 to 20,000 mPa˙s at concentration of 1%. Cationic polymeric retention means may be added into composition in conjunction with phenol resin or separately from it at other point. It may be also used for preliminary treatment of filler which is to be further added to composition.

EFFECT: increased extent of retention and dehydration of composition for manufacture of paper, high quality of paper sheets and reduced manufacture costs.

11 cl, 4 dwg, 5 tbl, 3 ex

Description

FIELD OF THE INVENTION

This invention relates to the manufacture of paper. More specifically, it relates to a composition for making paper, which contains a retention aid based on a solvent-free cationic polymer in combination with a phenolic resin and polyethylene oxide (PEO) to increase retention and / or dewatering of the composition.

BACKGROUND OF THE INVENTION

In the paper manufacturing process, an aqueous suspension of cellulosic fibers, possibly containing a filler and cationic starch, as well as other chemical agents for making paper, is applied to the wire or fabric, and the water is removed to form a fibrous canvas or sheet. Such an aqueous suspension or pulp is called a “paper making composition”. To effectively obtain and increase the speed of the process, as well as reduce the cost of manufacturing high quality paper, it is very important to remove water or dehydrate the composition, as well as to keep small particles, fillers and other chemical agents in the paper sheet.

It is well known to use a combination of phenolic resin and polyethylene oxide as a flocculant to increase retention and dehydration during the manufacture of paper and paper board, especially newsprint, when a mechanical pulp containing dissolved organic pollutants has a harmful effect. In such systems, the phenolic resin is usually added to the composition first to the point of shear using a vane pump, and PEO is added second, usually near the headbox of the paper machine, in order to minimize shear. As you know, shear is carried out at one or several stages of cleaning, mixing and pumping in a paper-making process, this shift leads to the destruction of fiber fragments formed by a high molecular weight polymer into microfibers, which subsequently agglomerate, for example, in the presence of cationic starch.

It is believed that the retention mechanism of the two-component phenolic resin – PEO system consists, first, in the adsorption of the phenolic resin by fibers and small particles, followed by the addition of PEO to the phenolic resin hydroxyls and also in accelerating dehydration. Examples of such two-component retention systems are described, for example, in US patent No. 4070236 and 5472570.

The two-component phenolic resin / PEO system has the advantage that it is independent of most dissolved and colloidal contaminants in the water circuit, since it acts by the mechanism of binding of hydrogen atoms. In contrast, cationic polyacrylamides, which are commonly known as retention aids, are exposed to the harmful effects of dissolved and colloidal contaminants in a mechanical pulp.

In addition, the two-component phenolic resin / PEO system has several other advantages compared to cationic polyamides, including a favorable effect on the formation of the final sheet and control of the resin, which is associated with the ability of the system to fix organic pollutants in the paper sheet, preventing their deposition on parts of the equipment in factories, which causes possible interruptions in work.

However, despite these advantages, the phenolic resin / PEO retention system and dewatering system are not used in factories where paper grades such as highly filled special pulp-containing paper or fine-grained paper are used (when softwood pulp is not a significant part of the composition ), tissue and wrapping paper. In these cases, the use of polyacrylamides predominates.

The main reason for the failure to use the phenolic resin / PEO system in the above cases is the deteriorated performance due to the absence of organic contaminants in the compositions compared to the properties of paper obtained from softwood pulp used in the manufacture of many types of newsprint. These pollutants are involved in the mechanism of formation of the mesh structure, due to which this retention system operates; and their absence in other compositions, such as sulfate pulp and recycled ink-free pulp, has led to the predominance of other retention systems, especially cationic polyacrylamides. In addition, it was found that the presence of residual silicate in the pulp after some bleaching and ink removal operations sometimes has a detrimental effect on polyethylene oxide, causing loss of retention or dehydration (see Rahman and Tay Tappi Proceedings, 1986, Papermakers Conference, p. 189- 198).

Thus, there is a need for improved phenolic resin / PEO retention systems that overcome these disadvantages and increase retention and dehydration, especially in compositions such as sulfide pulp and recycled ink-free pulp.

OBJECTS AND SUMMARY OF THE INVENTION

The purpose of this invention is to provide a composition for the manufacture of paper with an increased degree of retention and dehydration based on a retention system containing phenolic resin / PEO.

Another goal is to create a way to increase the degree of retention and dewatering of the composition for making paper while maintaining good quality sheets of paper at a reduced cost.

A further objective is to provide a paper making composition based on a retention system comprising a phenolic resin / PEO combination that is suitable for the production of highly filled pulp-containing paper, fine-grained paper, tissue paper and brown paper.

Other objectives and advantages of the invention will become apparent from the following description.

Applicants have unexpectedly discovered that a retention aid consisting of a solvent-free cationic polymer, which is in the form of an oil-free water-soluble dispersion, in combination with a phenolic resin such as phenol-formaldehyde resin provides an increased degree of retention and dehydration, as well as others benefits such as reduced cost when used with polyethylene oxide (PEO). When a solvent-free cationic polymer as a retention aid and a phenolic resin are added to the composition, they form a structure that provides a more effective reaction with polyethylene oxide when it is added to the composition. The retention, namely retention of fibers, retention of filler and retention of COD (natural resins and other organic pollutants), and dehydration increase to such an extent that such a system is used in the production of fine-grained paper, packaging paper and other types of printed products. An additional increase in the retention of fillers and fine particles is achieved, which allows the use of only a combination of PEO and phenolic resin or only a solvent-free cationic polymer.

Solvent-free cationic polymer retention agents suitable for the purposes of this invention are characterized in that they do not contain any oil phase. They are liquid, aqueous solvent-free dispersions of cationic polymers with a usual charge density of 20 to 75 mol%, a solids content of 2 to 70% and a viscosity of a 1% solution in water of 2000-20000 MPa · s.

The synthesis of such polymer dispersions is described, for example, in US patent No. 5480934, which also indicates that they can be used as retention agents in the manufacture of paper, for soil impregnation or as a dispersant. However, there is no suggestion in this patent that they can be used as a component of the phenolic resin / PEO system, providing the above advantages.

The solvent-free cationic polymer and phenolic resin can be introduced separately at two different points of addition or together at one point, that is, they are added sequentially or together, and their combination interacts more favorably with PEO than if any component is used one. A solvent-based cationic polymer retention aid and phenolic resin can be added to the composition either before or after the addition of PEO.

Solvent-free cationic polymers are suitable for the purposes of this invention, regardless of the number, type or concentration of monomers used to prepare them, they can be in the form of a liquid or powder. Examples of such polymers are manufactured by Degussa under the trade names Praestaret K-325 and Praestaret K-350, as well as Praestol E-125 and Praestor E-150.

Thus, the present invention provides a paper making composition comprising a combination of a solvent-free cationic polymeric retention aid with a phenolic resin and polyethylene oxide as a system for holding fine particles, fillers and other chemical agents in a sheet of paper.

According to a preferred embodiment, the amount of solvent-free retention aid is 0.05-10 kg / ton based on the weight of dry fibers; the amount of phenolic resin is 0.05-10 kg of resin as it is sold per tonne of dry fibers and the amount of polyethylene oxide is 5-500 g / t based on the weight of dry fibers (“t” means metric ton).

The preferred ratio of solvent-free retention aid to phenolic resin is from 200: 1 to 1: 200, the ratio of phenolic resin to PEO is from 100: 1 to 1: 100, and the ratio of solvent-free retention aid to PEO is from 1 : 2000 to 2000: 1.

The invention also includes a method of increasing retention and dehydration in a paper composition by adding to the composition an effective amount of a solvent-free cationic polymeric retention agent in combination with a phenolic resin and polyethylene oxide. The effective amount depends on the type of dehydrated pulp and other additives used. It can be easily installed empirically by trial and error. Preferred amounts are indicated above.

According to another embodiment of the present invention, it was found that a further increase in the degree of dehydration of the sheet and the speed of the machine is achieved when the solvent-free cationic polymer retention agent is added last after the introduction of PEO and after the last shear point.

According to another embodiment of the invention, the filler is pretreated with a solvent-free cationic polymer retention aid before it is introduced into the feed. This pre-treatment is pre-flocculation and leads to better dispersion of the filler in the feed, a greater degree of retention of fine particles / filler and more haze. The pre-treated filler is dosed in the feedstock to the last shear point and PEO is preferably dosed near the headbox, so that filler particles and other small particles and fibers are captured in the spatial mesh structure.

Summarizing, it can be said that the present invention utilizes synergies between a phenolic resin and a solvent-free cationic polymeric retention agent to improve combination with polyethylene oxide and to make it possible to use polyethylene oxide and phenolic resin in various fields and to improve the production of existing newsprint. Further, the synergistic combination phenolic resin / retention aid, which is a solvent-free cationic polymer, also leads to additional advantages if the solvent-free cationic polymer retention aid is pre-mixed with the filler before dosing and reaction with polyethylene oxide.

The implementation of this invention allows you to take advantage of the introduction of polyethylene oxide in more areas of paper manufacture than is currently possible. These advantages include more favorable sheet formation than polyacrylamide retention agents, the ability to fix resinous contaminants in the sheet, and a lower dosing rate compared to polyacrylamide systems, which leads to lower steam consumption in dryers due to less bound water. Other advantages obtained by using the present invention are the interaction with starch and the ability to provide a more effective flocculating pre-treatment of the filler so that the activated filler is better dispersed in the feedstock before it is captured when polyethylene oxide is added. Providing excellent flocculating pre-treatment of the filler allows the latter to achieve better hiding power, while at the same time, its "capture" by polyethylene oxide provides good retention of the filler.

Brief Description of the Drawings

Preferred embodiments of the invention will be described below with reference to the drawings, in which:

1 is a schematic illustration of a device in which a solvent-free polymer and a phenolic resin are introduced together into a paper making composition;

figure 2 presents a diagram according to which a solvent-free polymer and a phenolic resin are separately introduced into the composition for making paper;

figure 3 presents a diagram according to which the solvent-free polymer is added to the composition for making paper last;

Figure 4 shows a diagram according to which the filler is pre-treated with a solvent-free polymer.

DETAILED DESCRIPTION OF THE INVENTION

Below the invention is described with reference to the drawings, which illustrate some preferred options and in which the same elements have the same numbering.

Thus, FIG. 1 shows a papermaking process, according to which the vane pump 10 forms the last shear point, after which the composition enters the sieve 12 and from there into the head box 14. According to this embodiment, the solvent-free polymer and phenolic resin are introduced into the composition together between the pump 10 and the sieve 12 before the introduction of the PEO.

According to the embodiment of FIG. 2, a solvent-free polymer is added to the composition prior to pump 10 and before the introduction of phenolic resin and PEO, which are added at the point between pump 10 and sieve 12. The solvent-free polymer is introduced as a micropolymer of fiber pretreatment.

According to the embodiment of FIG. 3, the solvent-free polymer is added last after the sieve 12 and immediately in front of the headbox 14. It acts as a drying means.

Finally, according to the embodiment of FIG. 4, a solvent-free polymer is introduced together with a filler that is pretreated with this polymer before pump 10. In this case, the phenolic resin is also introduced before the pump, but after the pre-treated filler. PEO is added between pump 10 and sieve 12.

It should be borne in mind that the above schemes in no way limit the invention.

Examples.

The following laboratory experiments were performed to implement this invention.

To determine the degree of retention without the formation of a stack of paper and test the turbidity, a Dynamic Dehydration Vessel (DDJ) with a guide cylinder was used, the stirrer speed was 500-1000 rpm.

A Dynamic Drainage Analyzer (DDA) was used to study retention with paper stack formation, dehydration, and study sheet formation. The purpose of using the DDA was to bring the paper manufacturing environment as close as possible. DDA is designed to measure the rate of dehydration when a stack of paper is formed. As a result of the measurement, the retention was higher than when using DDJ, where a stack of paper is formed. Since a stack of paper is formed during the experiment, wet sheet formation can also be achieved.

Dehydration.

The degree of dehydration in the DDA was estimated as the time interval from the start of the experiment to the start of air intake through the sheet, and it is automatically recorded by the computer for one hundredth of a second. Many factors influence dehydration, such as grammage, vacuum, sample volume, type of raw material, temperature, wire braid and chemical agents. It is usually desirable to use the same consistency of the composition as in the factory. However, for compositions with high fluidity and rapid dehydration, the accuracy of the experiment can be improved if a higher solids content or a larger sample volume is used.

Retention.

Retention is estimated as the amount of fiber held on the wire braid compared to the amount of fiber passed through it. The degree of retention during the experiments in the DDA is higher than on a paper machine. However, it correlates very well with the values obtained in the Britt vessel. The invention is illustrated by the following non-limiting examples, however, the scope of the invention.

Example 1

A 1.06% suspension of cellulose fibers consisting of 50% TMP (thermomechanical pulp bleached with hydrosulfite), 20% DIP (pulp free of printing ink) and 30% of the waste was obtained in a newsprint factory. The suspension contained 20% filler - clay. The pH of the suspension was adjusted to 4.5.

To determine the degree of retention and hiding power, a dehydration vessel (DDJ) was used with a guide cylinder; the stirrer speed was 550 rpm. A 500 ml sample was used for determination. FPR means holding on the first pass.

To determine the dehydration, structure and retention (with the formation of a stack of paper), a dehydration analyzer (DDA) with a guide cylinder was used, the stirrer speed was 1000 rpm. A 800 ml sample was used for determination. The vacuum value was 500 mbar.

Tables 1 and 2 below show the results of comparing a conventional phenol-formaldehyde resin-polyethylene oxide retention system with a phenol-formaldehyde resin-polyethylene oxide-solvent-free cationic polymer flocculant system. In the tables, turbidity is given in nephelometric turbidity units (NTU).

Example 2

A 0.992% suspension of cellulose fiber consisting of 10% Kraft pulp and 90% TMP (thermomechanical pulp bleached with hydrosulfite) was obtained at a special newsprint factory. The suspension contained 10% filler - clay. The pH of the suspension was adjusted to 6.0.

To determine the degree of dehydration, formation and retention (with the formation of the foot), we used an experiment using a dehydration analyzer (DDA) with a guide cylinder; the stirrer speed was 1000 rpm. A 800 ml sample was taken for testing. The vacuum was equal to 500 mbar.

Table 3 below shows the results of comparing a conventional phenol-formaldehyde resin-polyethylene oxide retention system with a phenol-formaldehyde resin-polyethylene oxide-solvent-free cationic polymer flocculant system.

Example 3

A 1.12% suspension of cellulose fibers containing 5% Kraft pulp, 70% TMP (thermomechanical pulp bleached with hydrosulfite) and 25% ink-free pulp (DIP) was obtained in a special newsprint factory using recycled fibers . The clay filler content was 30%. The pH of the suspension was adjusted to 6.2.

A dehydration vessel (DDJ) with a guide cylinder was used to determine retention and turbidity. The stirrer speed was 550 rpm. For the experiment, a 500 ml sample was used. FPR means retention on the first pass, FPAR means retention of ash on the first pass.

Table 4 below shows the results of comparing a conventional phenol-formaldehyde resin-polyethylene oxide retention system with a phenol-formaldehyde resin-polyethylene oxide-solvent-free cationic polymer flocculant system.

Table 4. Experience with DDJ. The product's name Product dose (g / t) The product's name Product dose (g / t) The product's name Product dose (g / t) FPR / FPAR (%) Turbidity (NTU) Normalization cost (0-100) - 0 0 0 0 0 35.6 / 45.4 86.1 0 Solvent-free polymer flocculant was added to phenol resin and PEO Not containing. solvent cationic polymer 300 Phenolic resin 420 Polyethylene oxide 60 48.0 / 68.2 36,2 97.8 Solvent-free polymer flocculant was introduced after phenol resin and PEO Phenolic resin 420 Polyethylene oxide 60 Not containing. solvent cationic polymer 300 42.2 / 56.6 34.1 97.8 Solvent-free polymer flocculant was introduced after phenolic resin and before PEO Phenolic resin 420 Not containing. will dissolve. cation. polymer 300 Polyethylene oxide 60 46.4 / 57.8 36,2 97.8 Phenolic resin and PEO only Not containing. solvent cationic polymer 0 Phenolic resin 0
420
700 Polyethylene oxide 60
60
one hundred 37.1 / 47.8
42.9 / 64.8
41.3 / 43.3 35.7
40.7
42.6 26.2
60.1
100.0 Solvent-free polymer flocculant only Not containing. solvent cationic polymer 300 Phenolic resin 0 Polyethylene oxide 0 41.1 / 43.3 36,2 37.8

Tests were also conducted on a machine of the same factory. A solvent-free cationic flocculant was added before the introduction of phenolic resin and PEO (viscous feed). The table below shows the results of comparing a conventional phenol-formaldehyde resin-polyethylene oxide retention system with a phenol-formaldehyde resin-polyethylene oxide-solvent-free cationic polymer flocculant system.

All relevant machine parameters and polymer quantities are shown in Table 5.

Table 5. Machine parameters - before and after adding a solvent-free cationic polymer retention aid. Parameter Without solvent-free cationic polymer retention agent In the presence of a solvent-free cationic polymer retention aid Grade 643.01 643.01 Grammage (weight 1 m ² paper) (g / m ² ) 41 41 Speed (m / min) 813 855 % pulp without printing ink (DIP) 0 0 % bleached softwood pulp kraft (SBK) 25,2 25 Steam pressure in 1 section (kPa) 114 one hundred Steam pressure in the 2nd section (kPa) 177 210 Steam pressure in the 3rd section (kPa) 273 258 The concentration of paper pulp in the headbox (%) 1,154 1,02 The concentration of white paper (%) 0.686 0.537 First Jump Hold (%) 40.66 47.1 Ash content in the headbox (%) 14.87 8.43 Ash content in white paper (%) 21.1 13.23 Holding ash at the first transition (%) 12.3 17.44 % ash in the sheet 3 2,3 % Alphatex clay added to headbox 2.01 1.89 Consumption of cationic agent (IU / L) 286 213 Turbidity in the headbox (NTU) 121 43 White paper opacity (NTU) 90 32 The amount of solvent-free cationic polymer (g / t) 0 300 The amount of phenolic resin (g / t) 560 235 The amount of coagulant (g / t) 210 0 The amount of polyethylene oxide (g / t) 59 38 Cost reduction (%) - -12.60%

A 12.6% reduction in product cost is a significant advantage of the papermaking process.

The above results clearly show that the combination of solvent-free cationic polymer - phenolic resin - PEO is the best system for economic reasons. Retention systems using a combination of phenolic resin / PEO in combination with a solvent-free cationic polymer provide the highest degree of retention of fine particles using DDJ and DDA, the lowest degree of turbidity and the highest dehydration rate, which is evidence of the ability of these systems to retain fine particles and colloidal substances.

This is especially true for the following sequence of adding components: solvent free cationic polymer / phenolic resin / polyethylene oxide. In contrast, a solvent-free cationic polymer or phenolic resin / polyethylene oxide system, used alone, results in lower retention and / or higher turbidity.

Based on these results, it can be concluded that there is not only a synergy between the phenolic resin / PEO system and the solvent-free cationic polymer, but also a significant reduction in costs.

It should be noted that the specific options and examples described above do not limit the scope of the invention, it is obvious to those skilled in the art that various modifications of the invention can be made without departing from the scope of the invention, the scope of which is defined by the claims.

Claims (11)

1. A paper making composition comprising a combination of a flocculating solvent-free cationic polymer holding agent with a phenolic resin and polyethylene oxide as a system for holding small particles, fibers and other chemical agents for making paper in a paper sheet, characterized in that the flocculating does not contain solvent, the cationic polymer retention aid is a liquid aqueous, solvent-free dispersion of the cationic polymer, non / sod rzhaschuyu oil phase and having a viscosity at 1% concentration, from 2,000 to 20,000 mPas. 2. The composition for making paper according to claim 1, characterized in that the dispersion of the cationic polymer is characterized by a charge density of from 20 to 75 mol.% And a solids content of from 2 to 70 wt.%. 3. The composition for making paper according to claim 1, characterized in that the amount of solvent-free cationic retention agent is 0.05-10 kg / t based on the weight of dry fibers, the amount of phenolic resin is 0.05-10 kg / t of dry fibers and the amount of polyethylene oxide is 5-500 g / t based on the weight of dry fibers. 4. The composition for making paper according to any one of claims 1 to 3, characterized in that the ratio of the solvent-free cationic retention agent to the phenolic resin is from 200: 1 to 1: 200, the ratio of phenolic resin to polyethylene oxide is from 100: 1 up to 1: 100 and the ratio of solvent-free cationic polymeric retention to polyethylene oxide is from 1: 2000 to 2000: 1. 5. A method of increasing the degree of retention and / or dehydration in the composition for making paper by adding to the composition an effective amount of a liquid aqueous solvent-free cationic polymer flocculating agent for holding with a viscosity in water at a concentration of 1% from 2000 to 20,000 MPa · s in combination with phenolic resin and polyethylene oxide. 6. The method according to claim 5, characterized in that the solvent-free cationic polymer retention agent is added to the composition together with the phenolic resin at the same point. 7. The method according to claim 5, characterized in that the solvent-free cationic polymer retention agent is added to the composition separately from the phenolic resin at another point. 8. The method according to PP.5, 6 or 7, characterized in that the solvent-free cationic polymer retention agent and phenolic resin are added to the composition before or after the introduction of polyethylene oxide. 9. The method according to claim 7, characterized in that the solvent-free cationic polymer retention agent is added last, after the phenolic resin and polyethylene oxide and after the last shear point. 10. The method according to claim 5, characterized in that it includes adding a filler to the composition and pre-treating the filler with a solvent-free cationic polymer retention aid. 11. The method according to claim 10, characterized in that the pre-treated filler is metered into the composition to the last shear point and before the addition of polyethylene oxide.

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