CN117604812A - Preparation method of efficient reinforced retention aid containing nanocellulose and application of efficient reinforced retention aid in papermaking - Google Patents

Abstract

The invention relates to the technical field of enhanced retention aids, and discloses a preparation method of an efficient enhanced retention aid containing nanocellulose and application of the efficient enhanced retention aid in papermaking, wherein the preparation method comprises the following steps of: step one: adding a nano cellulose raw material into water for pretreatment, adding a modifying reagent, and carrying out first modification treatment to obtain a modified nano cellulose solution; step two: adding a starch raw material and a starch degradation reagent into the modified nanofiber solution, and performing secondary modification treatment to obtain modified nanocellulose-containing starch solution; step three: adding a cationic reagent and a catalyst into the modified nano cellulose-containing starch solution, and performing a third modification treatment to obtain a cationic modified solution; step four: and adding a neutralizing agent, an enhancer and a bactericide into the cation modified liquid to obtain the enhanced retention aid. According to the invention, the cationization of the nanocellulose and the starch effectively improves the reaction efficiency of cations, and a more stable liquid product is obtained, so that the application effect is improved.

Description

Preparation method of highly efficient enhanced retention aid containing nanocellulose and its application in papermaking Applications in

Technical field

The present invention relates to the technical field of enhanced retention aids, and in particular to a preparation method of a highly efficient enhanced retention aid containing nanocellulose and its application in papermaking.

Background technique

Enhanced retention aids are important additives used in the papermaking process. With the development of the papermaking industry, from the aspects of saving energy, reducing pulp consumption and enhancing paper strength, enhanced retention aids require higher amounts of fine fibers and other Retention rate of additives. Cationic starch is a commonly used raw material for retention aids. Cationic starch introduces tertiary amino or quaternary ammonium groups into the starch macromolecules to give the starch cationic properties. The positive charge of cationic starch makes it combine with the negatively charged matrix and can bind the negatively charged matrix. Other additives adsorb and remain on the matrix. However, starch needs to be cooked and used. The dry basis usage of cationic starch is generally 6-10 kg. Therefore, when cationic starch is used as a single raw material for retention aids, the dosage is larger, the process is more cumbersome, and the cationicity is low. This makes it less efficient in enhancing and retaining paper. For example, the patent with publication number CN 109667193 A discloses a preparation method of a composite papermaking retention aid, using zeolite with a rich pore structure as raw material, and modifying it with carboxymethyl cellulose and sodium citrate respectively. Modified zeolite powder is obtained, and then corn starch is used as raw material to cationically modify it to obtain self-made cationic starch. Finally, the prepared modified zeolite powder is mixed with self-made cationic starch and deionized to finally prepare a composite Papermaking retention aid. However, its solid content is high and its bonding with fibers is poor, which is not conducive to improving the reinforcing effect of paper.

Nanocellulose is a nanomaterial obtained from cellulose fibers through nanonization treatment. Nanocellulose has a high specific surface area and porosity, forming more fiber contact points in the paper, enhancing the strength and durability of the paper, forming a network structure in the paper, increasing the flexibility and elasticity of the paper, and improving toughness. and folding resistance. However, nanocellulose has some problems in practical applications. For example, the adsorption force between its own particles is weak, it is not easy to disperse, and it is easy to aggregate and form clumps, resulting in a decrease in specific surface area and activity, which is not conducive to papermaking applications.

Contents of the invention

In order to solve the above technical problems, the present invention provides a preparation method of a highly efficient enhanced retention aid containing nanocellulose and its application in papermaking. Through the synergistic effect of nanocellulose and cationic starch, the retention aid has Higher cationicity can reduce the amount added in papermaking, while improving the retention rate of fine fibers and reinforcing the paper.

The purpose of the present invention is achieved through the following technical solutions:

In a first aspect, the present invention provides a method for preparing a highly efficient enhanced retention aid containing nanocellulose, which includes the following steps:

Step 1: Add the nanocellulose raw material to water for pretreatment, then add the modifying reagent, perform the first modification process, and obtain a modified nanocellulose solution;

Step 2: Add starch raw materials and starch degradation reagents to the modified nanofiber solution, perform a second modification process, and obtain a starch solution containing modified nanocellulose;

Step 3: Add cationic reagents and catalysts to the starch solution containing modified nanocellulose, perform the third modification process, and obtain a cationic modified solution;

Step 4: Add neutralizing reagent, enhancer and bactericide to the cationic modification liquid to obtain an enhanced retention aid.

Since nanocellulose has a large specific surface area and abundant surface hydroxyl groups, if it is added to pulp, it can be closely combined with pulp fibers, thus improving the binding force between pulp fibers. Therefore, nanocellulose can be used as a pulping material. Reinforcing agents, retention aids and filter aids in the papermaking process have good development prospects. However, it is not easy to disperse and easily aggregates to form clumps. The viscosity of a low-concentration nanocellulose solution will reach a high level. To address this problem, the present invention first physically disperses the nanocellulose and then chemically branches it, so that Nanocellulose is better dispersed and can also increase its strength. Natural starch is then introduced into the modified nanocellulose. The starch can give the paper strength, and can significantly reduce the dosage of retention aids, increase the solid content of the solution, and enhance the retention and drainage of the slurry.

However, modified nanofibers will form a network structure, in which the amount of starch introduced is limited. If too much is introduced, it will not be conducive to the formation of a stable liquid retention aid, nor is it conducive to the branches of exposed nanocellulose. At the same time, the nanocellulose and Starch is cationized to increase cationicity. Therefore, in order to obtain a stable liquid retention aid, the liquid molecular chain is more stretched, better combined with the paper fiber, and significantly improves the paper reinforcement and retention effect. After the introduction of starch and before cationization, the present invention first performs Starch gelatinization and degradation effectively increase the concentration of starch liquid, and because it is in a liquid state, the hydroxyl groups on starch and nanocellulose are completely exposed, which can effectively improve the cationic reaction efficiency. Moreover, by introducing cationic reagents and cationic starch liquid into modified nanocellulose, the dispersion and stability of nanocellulose can be improved, the specific surface area of nanocellulose can be increased, and the nanocellulose can form a better network in paper. structure to improve the product’s enhanced retention effect on paper. Therefore, this highly efficient enhanced retention aid containing nanocellulose has broad application prospects and can play an important role in the paper industry.

Preferably, in step one, the nanocellulose raw material is one or more of nanocellulose, softwood pulp and hardwood pulp; the mass ratio of the nanocellulose raw material and water is 1:200-400 ; The pretreatment time is 30 to 40 minutes.

Preferably, in step one, the adding amount of the modifying reagent is 100-200 ppm based on the mass of the nanocellulose raw material; the modifying reagent is one or more of enzyme, hydrochloric acid and sodium hypochlorite; the first time The modification treatment involves raising the temperature to 30-60°C and reacting for 1-2 hours.

Preferably, in step two, the addition amount of the starch raw material is 20-25% of the mass of the modified nanocellulose solution; the starch degradation reagent is 0.01-1% of the mass of the starch raw material; the second modification The treatment is to raise the temperature to 70~90℃ and react for 0.5~1h.

The ratio of starch to nanocellulose is particularly important. It cooperates with the subsequent modification condition parameters to ensure a large amount of starch introduction while balancing the amount of starch and nanocellulose so that the retention aid remains stable. In the liquid dispersion state, the degree of cationization can also reach a high level.

Preferably, in step 2, the starch raw material is one or more of corn starch, tapioca starch, waxy corn starch and potato starch; the starch degradation reagent is hydrochloric acid, sulfuric acid, phosphoric acid, sodium hypochlorite, hydrogen peroxide and β One or several types of biological enzymes.

Preferably, in step three, the added amount of the cationic reagent is 10-20% of the mass of the starch raw material; the added amount of the catalyst is 2-6% of the mass of the starch raw material; the third modification treatment is heating to 60~80℃ and react for 5~7h.

The introduction of cationic reagents in the third modification process allows starch and nanocellulose to react simultaneously, making the product more stable and thus improving the application effect. Carrying out the cationization reaction at this temperature and time is conducive to a more complete reaction of the solution.

Preferably, in step three, the cationic reagents are 3-chloro-2-hydroxypropyltrimethylammonium chloride, epoxypropyltrimethylammonium chloride and 4-chloro-2-butenyltrimethylammonium chloride. One or more of ammonium chloride; the catalyst is one or more of potassium hydroxide, calcium hydroxide, sodium hydroxide and magnesium oxyoxide.

Preferably, in step 4, the added amount of the neutralizing reagent is 1-5% of the mass of the starch raw material; the added amount of the enhancer is 0.1-0.5% of the mass of the starch raw material; the added amount of the fungicide is 0.05~0.15% of the quality of starch raw materials.

Preferably, in step 4, the neutralizing reagent is one or more of hydrochloric acid, sulfuric acid, phosphoric acid, oxalic acid and glacial acetic acid; the enhancing agent is borax, sodium trimetaphosphate, sodium tripolyphosphate and hexametaphosphate. One or more of sodium phosphate; the fungicide is one or more of isothiazolinone, benzisothiazolinone and bronopol.

In a second aspect, the present invention also provides an application of a highly efficient enhanced retention agent containing nanocellulose in papermaking.

Preferably, the application is: diluting the retention-enhancing agent with water to a dilution factor of 10 to 20 times, stirring it to uniformly disperse it, and then directly adding it to the papermaking slurry.

Compared with the prior art, the present invention has the following beneficial effects:

(1) Physical pretreatment of nanocellulose first, and then chemical reaction can disperse the fibers well and form a stable spatial network structure;

(2) After starch is modified, the concentration of starch can be effectively increased, and the increase in concentration can effectively increase the reaction efficiency of cations;

(3) Because it is in a liquid state, the hydroxyl groups on the starch and nanocellulose are completely exposed, which can effectively improve the reaction efficiency of cations;

(4) The introduction of cationic reagents allows starch and nanocellulose to react simultaneously, making the product more stable and thus improving the application effect;

(5) Liquid products can be used directly without cooking, and the use process is safe and convenient.

Detailed ways

The following specific examples are used to illustrate the technical solution of the present invention, but the protection scope of the present invention is not limited thereto:

Example 1

Step 1: Add 95g nanocellulose and 5g hardwood pulp to 20kg water, disperse at high speed in a high-speed mixer for 30 minutes, transfer to a jacketed heated stirring reactor, add 0.01g cellulase, heat to 45°C, react After 1 hour, the modified nanocellulose solution was obtained.

Step 2: Add 3200g tapioca starch, 800g corn starch, 0.4gɑ-amylase and 3.64g hydrogen peroxide (27.5wt%), raise the temperature to 80°C, and react for 50 minutes to obtain a starch liquid containing modified nanocellulose.

Step 3: Cool to 70°C, add a mixture of 881.2g 3-chloro-2-hydroxypropyltrimethylammonium chloride solution (69wt%) and 1014.3g sodium hydroxide solution (21wt%), at this temperature Reaction 5h.

Step 4: Lower the temperature to 35°C, add 400g hydrochloric acid solution (15wt%), 4g borax, 8g sodium trimetaphosphate, and 4g bronopol. After stirring evenly, a high-efficiency enhanced retention agent containing nanocellulose is obtained.

Example 2

Step 1: Add 90g nanocellulose, 5g hardwood pulp and 5g softwood pulp to 25kg water, disperse at high speed in a high-speed mixer for 35 minutes, transfer to a jacketed heated stirring reaction kettle, add 0.01g cellulase, 0.1 g of sodium hypochlorite solution (10wt%), raise the temperature to 50°C, and react for 80 minutes to obtain a modified nanocellulose solution.

Step 2: Add 5625g tapioca starch, 625g potato starch, 0.6gɑ-amylase and 0.6g β-amylase, raise the temperature to 90°C, and react for 40 minutes to obtain a starch liquid containing modified nanocellulose.

Step 3: Cool to 80°C, add 1159.4g 3-chloro-2-hydroxypropyltrimethylammonium chloride solution (69wt%), 450g epoxypropyltrimethylammonium chloride, 1000g sodium hydroxide solution ( 21wt%) and 100g calcium hydroxide, react at this temperature for 6 hours.

Step 4: Lower the temperature to 40°C, add 575g of sulfuric acid solution (20wt%), 31g of sodium tripolyphosphate, and 6g of isothiazolinone. After stirring evenly, a high-efficiency enhanced retention agent containing nanocellulose is obtained.

Example 3

Step 1: Add 92g nanocellulose and 8g softwood pulp to 40kg water, disperse at high speed in a high-speed mixer for 40 minutes, transfer to a jacketed heated stirring reactor, add 0.02g cellulase, heat to 60°C, react After 100 minutes, the modified nanocellulose solution was obtained.

Step 2: Add 8000g tapioca starch and 0.8gɑ-amylase, raise the temperature to 70°C, and react for 60 minutes to obtain a starch solution containing modified nanocellulose.

Step 3: Cool to 60°C, add 724.6g 3-chloro-2-hydroxypropyltrimethylammonium chloride solution (69wt%), 300g 4-chloro-2-butenyltrimethylammonium chloride and 1345.5g A mixture of sodium hydroxide solution (22wt%) was reacted at this temperature for 7 hours.

Step 4: Lower the temperature to 30°C, add 700g hydrochloric acid solution (15wt%), 30g borax, and 12g isothiazolinone, and stir evenly to obtain a highly efficient enhanced retention agent containing nanocellulose.

Comparative example 1

The difference from Example 1 is that the nanocellulose was not modified.

Step 1: Add 95g of nanocellulose and 5g of hardwood pulp to 20kg of water, and disperse at high speed in a high-speed mixer for 30 minutes to obtain a nanocellulose solution.

Step 2: Add 3200g tapioca starch, 800g corn starch, 0.4gɑ-amylase and 3.64g hydrogen peroxide (27.5wt%), raise the temperature to 80°C, and react for 50 minutes to obtain a nanocellulose-containing starch liquid.

Step 3: Cool to 70°C, add a mixture of 881.2g 3-chloro-2-hydroxypropyltrimethylammonium chloride solution (69wt%) and 1014.3g sodium hydroxide solution (21wt%), at this temperature Reaction 5h.

Step 4: Lower the temperature to 35°C, add 400g hydrochloric acid solution (15wt%), 4g borax, 8g sodium trimetaphosphate, and 4g bronopol. After stirring evenly, a high-efficiency enhanced retention agent containing nanocellulose is obtained.

Comparative example 2

The difference from Example 1 is that the amount of starch added is less (the amount of starch raw material added is 15% of the mass of the modified nanocellulose solution).

Step 1: Add 95g nanocellulose and 5g hardwood pulp to 20kg water, disperse at high speed in a high-speed mixer for 30 minutes, transfer to a jacketed heated stirring reactor, add 0.01g cellulase, heat to 45°C, react After 1 hour, the modified nanocellulose solution was obtained.

Step 2: Add 2400g tapioca starch, 600g corn starch, 0.3g ɑ-amylase and 2.73g hydrogen peroxide (27.5wt%), raise the temperature to 80°C, and react for 50 minutes to obtain a starch liquid containing modified nanocellulose.

Step 3: Cool to 70°C, add a mixture of 660.9g 3-chloro-2-hydroxypropyltrimethylammonium chloride solution (69wt%) and 760.7g sodium hydroxide solution (21wt%), at this temperature Reaction 5h.

Step 4: Lower the temperature to 35°C, add 300g hydrochloric acid solution (15wt%), 3g borax, 6g sodium trimetaphosphate, and 4g bronopol. After stirring evenly, a high-efficiency enhanced retention agent containing nanocellulose is obtained.

Comparative example 3

The difference from Example 1 is that the second modification reaction was not carried out.

Step 1: Add 95g nanocellulose and 5g hardwood pulp to 20kg water, disperse at high speed in a high-speed mixer for 30 minutes, transfer to a jacketed heated stirring reactor, add 0.01g cellulase, heat to 45°C, react After 1 hour, the modified nanocellulose solution was obtained.

Step 2: Add 3200g tapioca starch, 800g corn starch, 0.4gɑ-amylase and 3.64g hydrogen peroxide (27.5wt%). After stirring, a starch liquid containing modified nanocellulose is obtained.

Step 3: Raise the temperature to 70°C, add a mixture of 881.2g 3-chloro-2-hydroxypropyltrimethylammonium chloride solution (69wt%) and 1014.3g sodium hydroxide solution (21wt%). Reaction 5h.

Step 4: Lower the temperature to 35°C, add 400g hydrochloric acid solution (15wt%), 4g borax, 8g sodium trimetaphosphate, and 4g bronopol. After stirring evenly, a high-efficiency enhanced retention agent containing nanocellulose is obtained.

Comparative example 4

The difference from Example 1 is that no starch degradation reagent was added.

Step 1: Add 95g nanocellulose and 5g hardwood pulp to 20kg water, disperse at high speed in a high-speed mixer for 30 minutes, transfer to a jacketed heated stirring reactor, add 0.01g cellulase, heat to 45°C, react After 1 hour, the modified nanocellulose solution was obtained.

Step 2: Add 3200g tapioca starch and 800g corn starch, raise the temperature to 80°C, and react for 50 minutes to obtain a starch liquid containing modified nanocellulose.

Step 3: Lower the temperature to 70°C, add 881.2g 3-chloro-2-hydroxypropyltrimethylammonium chloride solution (69wt%) and 1014.3g sodium hydroxide solution (21wt%), and react at this temperature for 5 hours.

Step 4: Lower the temperature to 35°C, add 400g hydrochloric acid solution (15wt%), 4g borax, 8g sodium trimetaphosphate, and 4g bronopol. After stirring evenly, a high-efficiency enhanced retention agent containing nanocellulose is obtained.

After diluting the retention-enhancing agent in the Examples and Comparative Examples 15 times with water, it was added to the hardwood pulp to conduct a papermaking test.

Table 1

Concentration (%): The concentration is the concentration of the retention-enhancing agent prepared by the present invention. If the concentration is too low, the reaction efficiency is low, the application effect is poor, and the transportation cost is high; if the concentration is too high, the product will have high viscosity and poor fluidity, which is not conducive to application. Generally, Around 15-22%.

Viscosity (mPa·s, 25°C): The viscosity is the viscosity of the enhanced retention agent prepared by the present invention, which needs to be controlled between 800-2000 mPa·S in order to obtain better reinforcement and retention effects.

Adding amount, absolute dry (%): Adding amount refers to the added mass of liquid retention-enhancing agent (calculated as dry matter) relative to the paper. For example, 100g of paper needs to add 0.3g of absolute drying enhanced retention aid product, and the product concentration is 16.7%, that is, 0.3÷16.7% = 1.796g of product needs to be added.

Tensile strength (N·m/g): The enhanced retention agent was added to the hardwood pulp for papermaking tests, and the tensile strength of the resulting paper was tested.

Ash content (%): The enhanced retention agent was added to the hardwood pulp for papermaking tests, and the ash content of the resulting paper was tested. Low ash content indicates a low retention rate of the paper filler.

As shown in Table 1, in Comparative Example 1, because the nanocellulose was not modified, the spatial structure of the fiber was not well relaxed, and the exposed hydroxyl groups were reduced, which not only led to a reduction in the efficiency of the cationization reaction, but also caused the fiber to stretch. If it is not thorough enough, it will easily reunite again during later storage, affecting product application.

In Comparative Example 2, the added amount of starch was reduced, resulting in a reduction in system concentration, system viscosity, and cationic reaction efficiency. When the product is applied, it affects the tensile strength and paper ash content of the paper.

In Comparative Example 3, no modification reaction was carried out in step 2. During the heating process in step 3, the viscosity of the system increased sharply, and the reagents in step 2 began to react. However, after the reagents in step 3 were added, the reagents in step 2 were directly ineffective. , resulting in high final viscosity of the system, thick system, poor use effect, sharp decrease in application data tensile strength, and decrease in ash content indicating low paper filler retention rate.

In Comparative Example 4, no starch degradation reagent was added in step 2, resulting in a very high viscosity of the system, which became jelly-like after cooling and could not be used.

The above are only preferred embodiments of the present invention, and do not limit the patent scope of the present invention. The same applies to any equivalent structure or equivalent process transformation made using the description of the present invention, or directly or indirectly applied to other related technical fields. Included within the patent protection scope of the present invention.

Claims (10)

1. The preparation method of the efficient reinforcing retention aid containing nanocellulose is characterized by comprising the following steps of:

step one: adding a nano cellulose raw material into water for pretreatment, adding a modifying reagent, and carrying out first modification treatment to obtain a modified nano cellulose solution;

step two: adding a starch raw material and a starch degradation reagent into the modified nanofiber solution, and performing secondary modification treatment to obtain modified nanocellulose-containing starch solution;

step three: adding a cationic reagent and a catalyst into the modified nano cellulose-containing starch solution, and performing a third modification treatment to obtain a cationic modified solution;

step four: and adding a neutralizing agent, an enhancer and a bactericide into the cation modified liquid to obtain the enhanced retention aid.

2. The method for preparing the efficient reinforcing retention aid containing nanocellulose as claimed in claim 1, wherein in the first step, the nanocellulose raw material is one or more of nanocellulose, softwood pulp and hardwood pulp; the mass ratio of the nano cellulose raw material to the water is 1: 200-400 parts; the pretreatment time is 30-40 min.

3. The method for preparing the efficient reinforcing retention aid containing nanocellulose as claimed in claim 1 or 2, wherein in the first step, the addition amount of the modifying agent is 100-200 ppm of the mass of the nanocellulose raw material; the modifying reagent is one or more of enzyme, hydrochloric acid and sodium hypochlorite; the first modification treatment is to heat up to 30-60 ℃ and react for 1-2 h.

4. The method for preparing the efficient reinforcing retention aid containing nanocellulose as claimed in claim 1, wherein in the second step, the addition amount of the starch raw material is 20-25% of the mass of the modified nanocellulose solution; the starch degradation reagent accounts for 0.01-1% of the mass of the starch raw material; and the second modification treatment is to heat to 70-90 ℃ and react for 0.5-1 h.

5. The method for preparing the efficient reinforcing retention aid containing nanocellulose as claimed in claim 1 or 4, wherein in the second step, the starch raw material is one or more of corn starch, tapioca starch, waxy corn starch and potato powder; the starch degradation reagent is one or more of hydrochloric acid, sulfuric acid, phosphoric acid, sodium hypochlorite, hydrogen peroxide and beta biological enzyme.

6. The method for preparing the efficient reinforcing retention aid containing nanocellulose as claimed in claim 1, wherein in the third step, the addition amount of the cationic reagent is 10-20% of the mass of the starch raw material; the addition amount of the catalyst is 2-6% of the mass of the starch raw material; and the third modification treatment is to heat up to 60-80 ℃ and react for 5-7 h.

7. The method for preparing a nanocellulose-containing high-efficiency enhanced retention aid according to claim 1 or 6, wherein in the third step, the cationic reagent is one or more of 3-chloro-2-hydroxypropyl trimethylammonium chloride, epoxypropyl trimethylammonium chloride and 4-chloro-2-butenyl trimethylammonium chloride; the catalyst is one or more of potassium hydroxide, calcium hydroxide, sodium hydroxide and magnesium oxide.

8. The method for preparing the efficient reinforcing retention aid containing nanocellulose as claimed in claim 1, wherein in the fourth step, the addition amount of the neutralizing agent is 1-5% of the mass of the starch raw material; the addition amount of the reinforcing agent is 0.1-0.5% of the mass of the starch raw material; the addition amount of the bactericide is 0.05-0.15% of the mass of the starch raw material.

9. The method for preparing the efficient reinforcing retention aid containing nanocellulose as claimed in claim 1 or 8, wherein in the fourth step, the neutralizing agent is one or more of hydrochloric acid, sulfuric acid, phosphoric acid, oxalic acid and glacial acetic acid; the reinforcing agent is one or more of borax, sodium trimetaphosphate, sodium tripolyphosphate and sodium hexametaphosphate; the bactericide is one or more of isothiazolinone, benzisothiazolinone and bronopol.

10. Use of a reinforcing retention aid made by the method of any one of claims 1-9 in papermaking.