CN111749047A

CN111749047A - Alkenyl succinic anhydride sizing agent and preparation method and application thereof

Info

Publication number: CN111749047A
Application number: CN201910806814.7A
Authority: CN
Inventors: 于得海; 胡晓秋; 张海光; 王哲; 崔磊; 逄嘉瑞; 刘铭宇; 李新才; 李国栋; 刘温霞; 王慧丽; 宋兆萍
Original assignee: Qilu University of Technology
Current assignee: Qilu University of Technology
Priority date: 2019-08-29
Filing date: 2019-08-29
Publication date: 2020-10-09

Abstract

The invention belongs to the technical field of papermaking, and particularly relates to an alkenyl succinic anhydride sizing agent, and a preparation method and application thereof. Mixing alkenyl succinic anhydride and cellulose nanocrystal dispersion liquid, and performing first emulsification to obtain ASA-1 emulsion; and carrying out ultrasonic treatment on the ASA-1 emulsion, mixing the obtained emulsion with the nanocellulose fibers, and carrying out second emulsification to obtain the alkenyl succinic anhydride sizing agent. The results of the examples show that the ASA sizing agent emulsion prepared by the invention can not generate particle aggregation and precipitation after being placed for 30 days, has no phase body precipitation and demulsification phenomenon, and has good stability; the paper sizing degree of the sizing paper is 224-332 seconds, and the sizing performance of the ASA sizing agent emulsion is good; the sizing degree of sizing paper after the ASA sizing agent emulsion is placed for 72 hours is 210-325 seconds, and the emulsion has good hydrolysis resistance.

Description

Alkenyl succinic anhydride sizing agent and preparation method and application thereof

Technical Field

The invention relates to the technical field of papermaking, in particular to an alkenyl succinic anhydride sizing agent and a preparation method and application thereof.

Background

The emulsion is a dispersion system formed by dispersing a liquid in another liquid immiscible with the liquid, is mostly formed by mixing a water-insoluble oil phase and a water phase, and is widely applied to industries of papermaking, food, cosmetics, medicines and the like. Emulsions are thermodynamically unstable systems and in order to maintain the relative stability of the emulsion (kinetic stability) emulsifiers or stabilizers have to be added during the preparation of the emulsion. Most of the traditional emulsifiers or stabilizers are surfactants and high molecular polymers with surface activity, and the stability of the emulsion is maintained by reducing the interfacial tension between oil-water two-phase liquid, providing a stable interfacial film and improving the viscosity of a continuous phase. In recent years, solid particles have been receiving more and more attention because they can avoid adverse effects of surfactants on the environment, stabilize highly concentrated dispersed phase emulsions, and are less affected by changes in pH, salt concentration, temperature, and oil phase composition. For example, in the paper industry, water-insoluble sizing agents for papermaking need to be emulsified into an oil-in-water emulsion to be compatible with the papermaking system using water as a medium, and the purpose of sizing for papermaking is to increase the water resistance of paper, and the presence of surfactants generally reduces the water resistance of paper in addition to causing adverse effects on the environment, which can be avoided by using solid particle stabilized sizing agent emulsions.

The paper making industry in the twentieth century changes from an acid paper making system to medium-alkaline paper making, is an innovative change of a paper making process, greatly improves the paper quality, expands the filler range, reduces the pulp consumption and the energy consumption, lightens the environmental pollution and prolongs the service life of equipment. China adopts medium and alkaline sizing in production since 1989, and gradually popularizes in recent years, so that Alkyl Ketene Dimer (AKD) and Alkenyl Succinic Anhydride (ASA) are mainly used at present, and ASA is gradually adopted in large and medium-sized paper mills. In particular, in recent years, ASA sizing agents have been widely used for internal sizing of fine paper and board, particularly for large high-speed paper machines for internal coating, due to their high reactivity, low sizing cost, and high curing rate. However, ASA is a neutral sizing agent for papermaking with high reactivity, the hydrolysis speed is high, the sizing effect is reduced after the emulsion is stored for more than 1 hour at room temperature, the hydrolysate can cause paper making obstruction and the sizing efficiency is reduced, so when ASA is used, the ASA is required to be emulsified quickly, and the emulsified emulsion is required to be used as soon as possible. Alkenyl Succinic Anhydride (ASA) is very easy to hydrolyze, alcoholysis and ammonolysis, so alcohol, carboxylic acid and ammonia compounds are not suitable for being used as an emulsifier for ASA. At present, the emulsification of ASA sizing agents is mainly carried out on site by using cationic starch and low molecular surfactant, and the ASA sizing agents are used immediately. However, starch needs to be gelatinized and cooled before use, which makes the ASA emulsification process rather complicated, difficult to control, and often causes problems with deposition, felt blockage, etc. In addition, the surfactant in the sizing agent has certain adverse effects and certain pollution to the environment.

At present, the research and the achievement of the emulsification preparation aspect of the ASA sizing agent are gradually enriched. US patent US6346554 discloses a method for stabilizing ASA emulsions using natural vegetable gums which purportedly increase ASA sizing efficiency by increasing ASA retention on the fibers, reducing ASA hydrolysis and consequent deposition problems, and forming a more uniform film on the fiber surface. US5962555 discloses a method for emulsifying ASA using a mixture of ionene polymers which not only increase sizing efficiency but also have a bactericidal effect and polyethyleneimine. Although these inventions eliminate the inconvenience of starch gelatinization in handling, they still require the addition of about 2% surfactant to obtain a stable ASA emulsion. US6284099 discloses a method for stabilizing ASA emulsions using anionic microparticle retention aids such as bentonite, colloidal silica, organic microparticles, and small amounts of surfactants and chelating agents for papermaking, which combines the microparticle retention aid with a sizing agent, simplifies the operation, and reduces the amount of surfactant used; however, the adverse effect of the surfactant cannot be completely avoided, and the addition amount of the particulate component is too large, so that the concentration of the prepared ASA emulsion is low, the storage of the emulsion is not facilitated, and the ASA is hydrolyzed seriously. Chinese patent 201510417679.9 discloses a biodegradable solid particle emulsifier based on modified cellulose nanocrystal particles and an emulsified ASA sizing agent thereof, the emulsified emulsion has good stability and can meet the general production requirements, but the emulsion has general stability, the sizing activity can only be kept for about 3 hours, and the limitation of ASA used in field emulsification still can not be removed.

In conclusion, the ASA sizing agent emulsion prepared by the method needs to be prepared at present, and the ASA stability is poor.

Disclosure of Invention

The invention aims to provide an alkenyl succinic anhydride sizing agent, a preparation method and application thereof, a surfactant does not need to be added, and the prepared sizing agent has high stability and strong hydrolysis resistance.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a preparation method of an alkenyl succinic anhydride sizing agent, which comprises the following steps:

mixing alkenyl succinic anhydride and cellulose nanocrystal dispersion liquid, and performing first emulsification to obtain ASA-1 emulsion;

and carrying out ultrasonic treatment on the ASA-1 emulsion, mixing the obtained emulsion with the nanocellulose fibers, and carrying out second emulsification to obtain the alkenyl succinic anhydride sizing agent.

Preferably, the volume ratio of the alkenyl succinic anhydride to the cellulose nanocrystal dispersion is 1: 1-20.

Preferably, the mass fraction of the cellulose nanocrystal dispersion is 0.05-1%.

Preferably, the diameter of the cellulose nanocrystal is 3-10 nm, and the length of the cellulose nanocrystal is 100-500 nm.

Preferably, the alkenyl succinic anhydride is at least one of alkenyl succinic anhydride monomers of dodecyl to octadecyl.

Preferably, the nano cellulose fiber is carboxylated nano cellulose fiber with the diameter of 3-100 nm and the length of 1-10 mu m.

Preferably, the temperature of the ultrasonic treatment is 55-80 ℃, the power is 600-3000W, and the time is 5-20 min.

Preferably, the temperature of the first emulsification is 5-50 ℃, the time is 2-10 min, and the shearing rate is 2000-10000 rpm; the temperature of the second emulsification is 5-50 ℃, the time is 2-5 min, and the shearing rate is 2000-10000 rpm.

The invention provides the alkenyl succinic anhydride sizing agent prepared by the preparation method in the technical scheme.

The invention provides an application of the alkenyl succinic anhydride sizing agent in the technical scheme in papermaking.

The invention provides a preparation method of an alkenyl succinic anhydride sizing agent, which comprises the steps of mixing alkenyl succinic anhydride and a cellulose nanocrystalline dispersion liquid, and carrying out first emulsification to obtain an ASA-1 emulsion; and carrying out ultrasonic treatment on the ASA-1 emulsion, mixing the obtained emulsion with the nanocellulose fibers, and carrying out second emulsification to obtain the alkenyl succinic anhydride sizing agent.

The Alkenyl Succinic Anhydride (ASA) sizing agent is prepared by using the Cellulose Nanocrystalline (CNC) and the nano cellulose fiber (CNF) as the emulsifiers for synergistic emulsification and stabilization, so that organic surfactant substances which are easy to generate bubbles and pollute the environment can be completely avoided, and the emulsifiers are green and environment-friendly renewable resource materials, so that the environment pollution is avoided, the production cost and the sizing cost are low;

the ASA sizing agent emulsion prepared under the CNF-induced vacancy stabilizing effect has ultrahigh stability and strong hydrolysis resistance, and the embodiment shows that the ASA sizing agent emulsion prepared by the invention can not generate particle aggregation and precipitation, has no phase body precipitation, has no emulsion breaking phenomenon after being placed for 30 days, and has good stability; the paper sizing degree of the sizing paper is 224-332 seconds, and the sizing performance of the ASA sizing agent emulsion is good; the sizing degree of sizing paper after the ASA sizing agent emulsion is placed for 72 hours is 210-325 seconds, and the emulsion has good hydrolysis resistance; the method can solve the problems of the on-site emulsification and on-site sizing process commonly adopted by the prior ASA papermaking sizing process and the sizing process limitation caused by ASA hydrolysis; compared with ASA emulsions with stable emulsification of traditional surfactants (such as starch) and ASA emulsions with stable emulsification of solid particles (such as clay nanoparticles and modified particles thereof), the ASA emulsions prepared by the method have the advantages that the surface sizing performance is remarkably improved, and the hydrolysis resistance of ASA can be greatly improved;

the ASA sizing agent emulsion is prepared by utilizing irreversible adsorption renewable resources, namely bio-based nano solid particle materials (CNC, CNF), and has certain biodegradability;

the ASA sizing agent emulsion has simple preparation process, small using amount of the emulsifier and low emulsification cost.

Drawings

FIG. 1 is a microscope picture (400 times, 100 μm scale) of a CNC/CNF emulsion-stabilized Pickering ASA size emulsion prepared in example 2;

FIG. 2 is a diagram showing the mechanism of an ASA sizing agent prepared according to the present invention;

FIG. 3 is an SEM image of a surface sized paper of the ASA emulsion prepared in example 3, with the SEM image of the paper before surface sizing on the left and the SEM image of the paper after surface sizing and contact angle on the right.

Detailed Description

In the present invention, unless otherwise specified, all the starting materials required for the preparation are commercially available products well known to those skilled in the art.

The method mixes alkenyl succinic anhydride and cellulose nanocrystalline dispersion liquid for first emulsification to obtain ASA-1 emulsion. In the present invention, the Alkenyl Succinic Anhydride (ASA) is preferably at least one of alkenyl succinic anhydride monomers of dodecyl to octadecyl; more preferably at least one of tetradecyl to hexadecyl alkenyl succinic anhydride monomers; when the alkenyl succinic anhydride is a mixture, the ratio of the dodecyl to octadecyl alkenyl succinic anhydride monomer is not particularly limited, and the dodecyl to octadecyl alkenyl succinic anhydride monomer can be mixed according to any ratio. The invention utilizes alkenyl succinic anhydride as a base stock for sizing agents.

In the invention, the diameter of the Cellulose Nanocrystal (CNC) is preferably 3-10 nm, and the length is preferably 100-500 nm; the cellulose nanocrystals are present as whisker-like particles. In the present invention, the CNC is preferably sulfonated CNC (CNC-S), hydrochloric acid prepared CNC or carboxylated CNC (CNC-C); more preferably sulfonated CNC. In the present invention, the CNC is preferably a commercially available product.

In the invention, the cellulose nanocrystal dispersion is preferably prepared by dispersing CNC (computerized numerical control) in deionized water, and the mass fraction of the cellulose nanocrystal dispersion is preferably 0.05-1%, more preferably 0.1-0.8%, and most preferably 0.3-0.5%.

In the invention, the volume ratio of the alkenyl succinic anhydride to the cellulose nanocrystal dispersion is preferably 1: 1-20, more preferably 1: 5-15, and most preferably 1: 8-12. The mixing process is not particularly limited, and the alkenyl succinic anhydride and the cellulose nanocrystal dispersion can be mixed.

In the invention, the first emulsification is preferably carried out at a temperature of 5-50 ℃, more preferably at a temperature of 15-30 ℃ for 2-10 min, and more preferably at a time of 5-8 min.

After the ASA-1 emulsion is obtained, the ASA-1 emulsion is subjected to ultrasonic treatment, the obtained emulsion is mixed with the nano cellulose fibers, and second emulsification is carried out to obtain the alkenyl succinic anhydride sizing agent.

In the invention, the temperature of ultrasonic treatment is preferably 55-80 ℃, more preferably 60-75 ℃, the power is preferably 600-3000W, more preferably 800-2500W, most preferably 1200-2000W, and the time is preferably 5-20 min, more preferably 8-15 min. The ultrasonic treatment equipment is not particularly limited, and the power condition can be achieved.

In the present invention, the nanocellulose fibers (CNF) are preferably carboxylated nanocellulose fibers having a diameter of 3 to 100nm and a length of 1 to 10 μm, and more preferably carboxylated nanocellulose fibers having a diameter of 3 to 10nm and a length of 1 to 3 μm. In the present invention, the CNF is preferably a commercially available product.

In the present invention, the mass fraction of the CNF is preferably 0.2 to 1.5% (mass percentage with respect to the CNC dispersion), and more preferably 0.6 to 1.2%.

The mixing process is not particularly limited, and the emulsion obtained by ultrasonic treatment can be mixed with the nanocellulose fibers.

In the invention, the temperature of the second emulsification is preferably 5-50 ℃, more preferably 15-30 ℃, and the time is preferably 2-5 min, more preferably 3-4 min.

In the present invention, the shear force required in the dispersion, first emulsification and second emulsification steps may be provided by any stirring and shearing equipment, in embodiments of the present invention, specifically a high shear disperser. The type of the high-speed dispersion shearing machine is not particularly limited, and the type known to those skilled in the art can be selected. In the invention, the shearing rate is preferably 2000-10000 r/min, and more preferably 5000-8000 r/min.

FIG. 2 is a mechanism diagram of an ASA sizing agent prepared by the present invention, wherein the present invention employs CNC nanoparticles to form an interfacial particle film at the ASA-water interface to form Pickering ASA emulsion droplets to prevent coalescence between ASA droplets; after high-temperature ultrasonic treatment, part of CNC nano particles at the oil-water interface and ASA generate esterification reaction to form a layer of hydrophobic CNC-ASA particle film, and the CNC-ASA particle film can further prevent water molecules from permeating at the oil-water interface, so that the hydrolytic stability of the ASA emulsion is greatly improved; after the CNF is added, a vacancy stabilizing effect is generated under the action of vacancy stabilization (when large particles are placed in a solution of smaller particles and are spatially restricted to avoid the small particles, vacancy stabilization is generated in colloid), and the stability of the CNC emulsified and stabilized ASAPickering emulsion is sharply improved under the vacancy stabilizing effect; meanwhile, a small part of CNF and ASA molecules generate esterification reaction at an oil-water interface to generate partially hydrophobic CNF, and as shown in FIG. 2, the partially hydrophobic CNF cooperates with CNC with hydrolysis reaction at the oil-water interface to further improve the water resistance of the interface particle film and the water resistance of ASA. Finally, the surface of the paper is coated and sized by using the CNC/CNF emulsion-stabilized ASAPickering emulsion, the hydrophobicity and the sizing performance of the sized paper are excellent, as shown in figure 3, because the CNC and CNF serving as the emulsion stabilizer have certain hydrophobicity, and the part of the CNC and CNF with hydrophobicity is combined with the cellulose on the surface of the sized paper, so that the sizing effect of the ASA is further improved.

The invention provides the alkenyl succinic anhydride sizing agent prepared by the preparation method in the technical scheme. The alkenyl succinic anhydride sizing agent finally prepared by the method is Pickering type ASA sizing agent emulsion, wherein ASA is distributed in a water phase in the form of spherical dispersed liquid drops, and the ASA liquid drops exist in the form of dispersed phases of emulsion products; the CNC is adsorbed on the surface of the ASA liquid drop in the form of solid particles; CNC-ASA (CNC partially reacted with ASA) is adsorbed on the ASA droplet surface in the form of solid particles; the CNF is homogeneously dispersed in the emulsion continuous phase (water) in the form of solid particles.

The invention provides an application of the alkenyl succinic anhydride sizing agent in the technical scheme in papermaking. The method for applying the alkenyl succinic anhydride sizing agent in papermaking is not particularly limited in the present invention, and a method well known to those skilled in the art can be adopted.

The alkenyl succinic anhydride sizing agent and the preparation method and use thereof provided by the present invention will be described in detail with reference to the following examples, but they should not be construed as limiting the scope of the present invention.

Example 1

Dispersing CNC (CNC prepared by a hydrochloric acid method) in deionized water, dispersing by using a high-speed shearing dispersion machine under the condition of 5000rpm to prepare CNC dispersion liquid with the mass fraction of 0.05%, then adding ASA (dodecenyl succinic anhydride) into the CNC dispersion liquid according to the volume ratio of 1:20, and continuing to perform first emulsification for 2min by using the high-speed shearing dispersion machine under the conditions of 2000r/min rotation speed and 5 ℃; performing ultrasonic treatment at 55 ℃ for 5min, then adding 1.5% (relative to the mass fraction of the CNC dispersion liquid) of CNF, and performing secondary emulsification for 2min by using a high-speed shearing dispersion machine at the rotating speed of 5000r/min and at the temperature of 5 ℃ to obtain the Pickering ASA sizing agent emulsion with stable CNC/CNF emulsification.

Example 2

Dispersing CNC (CNC-S) into deionized water, dispersing by using a high-speed shearing dispersion machine under the condition of 8000rpm to prepare CNC dispersion liquid with the mass fraction of 0.5%, then adding ASA (mixture of dodecenyl succinic anhydride and octadecenyl succinic anhydride, 50% of each) into the CNC dispersion liquid according to the volume ratio of 1:10, and continuing to perform first emulsification for 5min at the rotating speed of 5000r/min and the temperature of 25 ℃ by using the high-speed shearing dispersion machine; performing ultrasonic treatment for 8min at 75 ℃, then adding 1.0% of CNF, and performing second emulsification for 3min by using a high-speed shearing dispersion machine at the rotating speed of 8000r/min and the temperature of 25 ℃ to obtain the Pickering ASA papermaking sizing agent emulsion with stable CNC/CNF emulsification.

FIG. 1 is a microscope picture (400 times, 100 μm scale) of a CNC/CNF emulsion-stabilized Pickering ASA size emulsion prepared in example 2; as can be seen from the figure, the obtained emulsion droplets are uniform and stable spherical emulsion, no phase body is separated out, no emulsion breaking phenomenon is caused, and the emulsion stability is good.

Example 3

Dispersing CNC (CNC-C) into deionized water, dispersing by using a high-speed shearing dispersion machine under the condition of 8000rpm to prepare CNC dispersion liquid with the mass fraction of 1%, then adding ASA (mixture of tetradecenyl succinic anhydride and hexadecenyl succinic anhydride, 50% of each) into the CNC dispersion liquid according to the volume ratio of 1:1, and continuing to perform first emulsification for 5min at the rotating speed of 10000r/min and the temperature of 35 ℃ by using the high-speed shearing dispersion machine; performing ultrasonic treatment for 3min at 80 ℃, then adding 0.5 percent of CNF, and performing second emulsification for 2min by using a high-speed shearing dispersion machine at the rotating speed of 10000r/min and the temperature of 35 ℃ to obtain the Pickering ASA papermaking sizing agent emulsion with stable CNC/CNF emulsification.

FIG. 3 is an SEM image of a surface sized paper of the ASA emulsion prepared in example 3, with the SEM image of the paper before surface sizing on the left and the SEM image of the paper after surface sizing and contact angle on the right. As can be seen from the figure, the CNC and CNF as the emulsion stabilizer has certain hydrophobicity, and the CNC and CNF with the hydrophobicity can be combined with the cellulose on the surface of the sizing paper, so that the sizing effect of the ASA sizing agent is further improved; thereby improving the hydrophobicity and sizing performance of the sized paper.

Example 4

Dispersing CNC (CNC-S) into deionized water, dispersing by using a high-speed shearing dispersion machine under the condition of 10000rpm to prepare CNC dispersion liquid with the mass fraction of 0.8%, then adding ASA (hexadecenyl succinic anhydride) into the CNC dispersion liquid according to the volume ratio of 1:3, and continuing to perform first emulsification for 3min by using the high-speed shearing dispersion machine under the conditions of 5000r/min rotation speed and 50 ℃; performing ultrasonic treatment at 65 ℃ for 5min, then adding 0.25% CNF, and performing second emulsification for 5min by using a high-speed shearing dispersion machine at the rotating speed of 2000r/min and at 50 ℃ to obtain the Pickering ASA papermaking sizing agent emulsion with stable CNC/CNF emulsification.

Performance testing

The ASA sizing emulsions prepared in examples 1-34 were tested for performance:

1) the sizing method comprises the following specific steps:

before sizing, the ASA sizing agent emulsion was diluted to 0.2%, the pulp concentration was adjusted to 1%, and 1% aluminum sulfate (relative to the pulp) was added to the pulp at a 500rpm stirring rateMass percent of oven dry paper pulp), adjusting the pH value of the pulp to 7.5-8.5 by using 1mol/L sodium hydroxide solution, sequentially adding ASA emulsion and CPAM with the use amount of 0.03%, stirring for 2min at the shear rate of 500rpm by using a stirrer, standing for 30s, and making handsheets by using a PTI paper sheet maker (RK3AKWT, Austria), wherein the quantitative amount of the handsheets is 60g/m²(T205 om-88, TAPPI), the sheet making system selects a Kaiser method manual sheet making mode to make sheets according to the ISO5289/2 and DIN54358 standards. The handsheets produced were dried at 105 ℃ and then the moisture of the paper was equilibrated at room temperature for 24h with an ambient humidity of 50%. The invention uses a coating machine to glue the surface of paper, the paper is hardwood pulp paper without any additive, and the ration is 60g/m²。

2) The sizing degree measuring method comprises the following steps:

sizing performance was evaluated by measuring the degree of sizing of paper made (GB/T5405-2002). Before measurement, the paper is cut into square paper sheets of 30X 30mm, and the paper sheets are placed in an environment with 25 ℃ and 50% humidity to balance moisture for 24 hours. The paper is folded at four sides to form a boat-shaped structure with the bottom surface area of about 20 multiplied by 20mm, then the boat-shaped structure floats in ammonium thiocyanate dilute solution with the concentration of 2 percent, 0.5 mu L of ferric chloride solution with the mass concentration of 1 percent is dripped on the upper part of the boat-shaped paper by a rubber head dropper, and the timing is ended by a stopwatch when red spots appear in the middle of the ferric chloride solution, and the timing is the sizing degree of the paper sample. The front and back sides of the test sample were measured 10 times each and the average value was taken.

3) Method for measuring average particle diameter of liquid droplets: the diameters of 100 emulsion droplets observed under a microscope are counted by using particle size counting software carried by an optical microscope, and the average value is taken, namely the average particle size of the droplets.

TABLE 1 Properties of ASA sizing agent emulsions prepared in examples 1-4

According to the table 1, the average diameter of the emulsion droplets of the ASA sizing agent prepared by the invention is 2.2-3.2 μm, and the emulsion is free of phase body precipitation and emulsion breaking phenomenon after being placed for 30 days, which shows that the emulsion has good stability; the paper sizing degree of the sized paper is 224-332 seconds, which shows that the sizing performance of the emulsion is good; the sizing degree of the sizing paper after the emulsion is placed for 72 hours is 210-325 seconds, which shows that the ASA emulsion has good hydrolysis resistance.

The embodiment shows that the alkenyl succinic anhydride sizing agent provided by the invention has excellent sizing performance of the ASA emulsion, and good hydrolysis resistance of the ASA, and the good sizing performance of paper can be still kept after the emulsion is placed for 72 hours; and the ASA emulsion can not generate particle aggregation, precipitation or phase body precipitation in 30 days, and has good stability.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. The preparation method of the alkenyl succinic anhydride sizing agent is characterized by comprising the following steps:

2. The method according to claim 1, wherein the volume ratio of the alkenyl succinic anhydride to the cellulose nanocrystal dispersion is 1:1 to 20.

3. The method according to claim 1, wherein the cellulose nanocrystal dispersion liquid is contained in an amount of 0.05 to 1% by mass.

4. The method according to claim 1, wherein the cellulose nanocrystals have a diameter of 3 to 10nm and a length of 100 to 500 nm.

5. The method according to claim 1, wherein the alkenyl succinic anhydride is at least one of alkenyl succinic anhydride monomers of dodecyl group to octadecyl group.

6. The method according to claim 1, wherein the nanocellulose fibers are carboxylated nanocellulose fibers having a diameter of 3 to 100nm and a length of 1 to 10 μm.

7. The preparation method according to claim 1, wherein the ultrasonic treatment is performed at a temperature of 55-80 ℃, at a power of 600-3000W, and for a time of 5-20 min.

8. The method according to claim 1, wherein the first emulsification is carried out at a temperature of 5 to 50 ℃ for 2 to 10min at a shear rate of 2000 to 10000 rpm; the temperature of the second emulsification is 5-50 ℃, the time is 2-5 min, and the shearing rate is 2000-10000 rpm.

9. An alkenyl succinic anhydride sizing agent prepared by the method of any one of claims 1 to 8.

10. An alkenyl succinic anhydride sizing agent prepared by the preparation method of any one of claims 1 to 8 or an alkenyl succinic anhydride sizing agent of claim 9, for use in papermaking.