LU500291B1

LU500291B1 - Akd/asa composite papermaking sizing agent and preparation method and application thereof

Info

Publication number: LU500291B1
Application number: LU500291A
Authority: LU
Inventors: Dehai Yu
Original assignee: Univ Qilu Technology
Priority date: 2021-01-12
Filing date: 2021-06-17
Publication date: 2021-12-17
Also published as: CN112796157A; CN112796157B

Abstract

The present invention provides a preparation method of an AKD/ASA composite emulsion, including: mixing AKD oil with perfluorohexane, and performing uniform stirring to obtain AKD-P oil; mixing a montmorillonite aqueous dispersion with acetone, ammonia monohydrate and cetyltrimethylsiloxane, and performing uniform dispersion to obtain a mixed solution I; adding perfluorooctyltriethoxysilane into the mixed solution I, and performing ultrasonic dispersion to obtain a mixed solution II; drying the mixed solution II to obtain modified MMT powder; mixing the modified MMT powder with ASA, adding the AKD-P oil for mixing after uniform dispersion, and performing ultrasonic emulsification to obtain an AKD-P/ASA emulsion; and mixing the AKD-P/ASA emulsion with a sodium dodecyl sulfonate aqueous solution, and performing ultrasonic emulsification to obtain the ASA/AKD composite emulsion. Due to outer layer oil phase AKD coating, the emulsion avoids contact between ASA and a water phase, thus achieves the objective of avoiding ASA hydrolysis.

Description

! LU500291

DESCRIPTION AKD/ASA COMPOSITE PAPERMAKING SIZING AGENT AND PREPARATION METHOD AND APPLICATION THEREOF TECHNICAL FIELD

[0001] The present invention relates to the technical field of papermaking, in particular to an alkyl ketene dimer (AKD)/alkenyl succinic anhydride (ASA) composite papermaking sizing agent emulsion and a preparation method and application thereof.

BACKGROUND

[0002] The papermaking industry in the 20% century changed from an acidic paper-making system to a neutral-alkaline paper-making system, and it was a revolutionary change of a paper- making process, greatly improved the paper quality, expanded a filler range, reduced pulp consumption and energy consumption, reduced environmental pollution, and prolonged the service life of equipment. According to data statistics, cultural paper produced through neutral and alkaline sizing in Europe in the early 1980s accounted for 60% to 65% of the total amount of cultural paper, and reached 95% in the 1990s. In the corresponding period, the neutral and alkaline sizing proportion increased from 15% to more than 90% in American fine paper. Since 1989, China began to use neutral and alkaline sizing in production, and the neutral and alkaline sizing has been gradually popularized in recent years, and alkyl ketene dimer (AKD) and alkenyl succinic anhydride (ASA) are main sizing agents used at present.

[0003] AKD is an unsaturated lactone, is a wax-like solid insoluble in water at a normal temperature, and can be used as a papermaking sizing agent. However, it must be prepared into an emulsion before use, and it is one of the sizing agents commonly used in alkaline sizing in papermaking industry at present. Another commonly used papermaking sizing agent of the alkenyl succinic anhydride is liquid at a normal temperature, anhydride in a molecular structure of the alkenyl succinic anhydride is very easy to hydrolyze, the storage stability is poor, on-site emulsification is needed in a workshop, and hydrolysates of the alkenyl succinic anhydride are easy to deposit on a paper machine to cause papermaking obstacles, so that the application of the alkenyl succinic anhydride is limited to a certain extent. The hydrolysis speed of lactone rings in the AKD emulsion is low, emulsion drops are solid particles at a normal temperature, the storage performance of the emulsion is good, the emulsion prepared by a good emulsification process can be placed for 2 to 3 months, the sizing efficiency is high, the cost is relatively low, and these advantages promote the wide application of the AKD emulsion.

However, compared with alkenyl succinic anhydride, the AKD emulsion has a requirement on storage, needs to have performance such as long-term emulsion drop aggregation resistance, and has harsher requirements on an emulsification process.

At present, according to an AKD emulsification process, generally, the AKD is heated to be melt, then a dispersing agent, a surfactant, gelatinized cationic starch and the like are added, homogenization and emulsification are performed after premixing, and cooling and canning are performed after the homogenization is completed.

This process is very complicated, and a production period is long.

The surfactant added in the emulsification process may reduce the sizing efficiency, and bubbles are easily generated, thus bringing foam problems to the papermaking system, and even generating paper defects.

Therefore, developing of an efficient AKD emulsification system, and reducing the consumption of the surfactant or even avoiding the use of the surfactant are beneficial to AKD sizing efficiency improvement, and meet the production requirements of papermaking enterprises and green production requirements at present.

The patent application CN104499361A provides a method for preparing an AKD sizing agent containing nano microcrystalline cellulose, avoids the use of a surface sizing agent, can be used for surface sizing and internal sizing of paper pulp, and obviously improves a sizing degree of paper industry.

However, a preparation method of the nano microcrystalline cellulose at present is complicated, the cost is high, and this is unfavorable for its wide industrial application.

The patent application CN103774496A discloses an AKD emulsion jointly stabilized by glutamic acid, hydrotalcite and poly dimethyl diallyl ammonium chloride.

The patent discloses that the AKD emulsion stabilized by glutamic acid and hydrotalcite alone is unstable, the emulsion formed after the poly dimethyl diallyl ammonium chloride is added has high stability and good sizing performance, and a cationic surfactant (poly dimethyl diallyl ammonium chloride) is still used in the preparation process of the emulsion.

The patent application CN101942780A discloses a method for emulsifying AKD by chitosan and nano titanium dioxide in a combined manner. An emulsification process is simple, the AKD emulsion has high sizing efficiency and high curing speed, but the coalescence stability of emulsion drops still needs to be improved. In view of the wide use of the AKD and the existing problems, it is still necessary to further study a novel AKD emulsion preparation technology to prepare sizing agents having high sizing efficiency and adapting to modern papermaking enterprises.

[0004] The ASA sizing agent has high reaction activity, low size cost and high curing speed, is thus widely used for internal sizing of fine paper and paperboards, and is particularly applicable to sizing of large-scale high-speed paper machines for in-machine coating. However, the ASA is a neutral papermaking sizing agent with high reactivity and has high hydrolysis speed, the sizing effect is reduced after the ASA emulsion is stored at a room temperature for more than 1 hour, hydrolysates may cause papermaking obstacles and reduce the sizing efficiency, so the ASA is required to be fast emulsified when being used, and the emulsified emulsion should be used as soon as possible. The alkenyl succinic anhydride (ASA) is only very easy to take hydrolysis, but also very easy to take alcoholysis and ammonolysis, so alcohol, carboxylic acid and ammonia compounds are not suitable to be used as emulsifiers for the ASA. At present, according to the emulsification of the ASA sizing agent, cationic starch and low molecular surfactants are mainly used for in situ emulsification, and are used immediately. However, the starch needs to be gelatinized and cooled before use, so that the ASA emulsification process is very complicated and difficult to control, and the problems of deposition, blanket blockage and the like are often caused. The used surfactants also bring certain adverse influence on sizing, and cause some pollution to the environment. At present, the research and achievements in an aspect of emulsion preparation of the ASA sizing agent have been also gradually enriched. The U.S. patent application US6346554 discloses a method for stabilizing an ASA emulsion by using natural plant gum, and discloses that the sizing efficiency of the ASA can be improved by using the plant gum through increasing the retention of the ASA on the fiber, reducing the hydrolysis of the ASA and thus caused deposition problems and forming a more uniform film on a fiber surface. The U.S. patent application US5962555A discloses a method for emulsifying ASA by using a mixture of an ionene polymer and polyethyleneimine, wherein the ionene polymer can improve the sizing efficiency, and also has a bactericidal effect. Although these inventions avoid the inconvenience of starch gelatinization in operation, in order to obtain a stable ASA emulsion, about 2% of a surfactant still needs to be added. The patent application CN1214093A discloses a method for stabilizing an ASA emulsion by using papermaking anionic microparticle retention aids such as bentonite, colloidal silicon dioxide and organic microparticles, and a small number of surfactants and chelating agents, the microparticle retention aids and the sizing agent can be integrated, the operation is simplified, and the consumption of the surfactants is reduced. However, adverse influence caused by the surfactants cannot be completely avoided, the addition amount of microparticle components 1s too great, the concentration of the prepared ASA emulsion is very low, the conditions are unfavorable for the storage of the emulsion, and the hydrolysis of the ASA 1s serious. The patent application CN105056830A discloses a biodegradable solid particle emulsifier based on modified nano cellulose crystal particles and an ASA sizing agent emulsified by the biodegradable solid particle emulsifier, the emulsified emulsion has good stability and can meet general production requirements, but the emulsion has the average stability, can only maintain the sizing activity for about 3 hours, and still cannot break through the limitation of the ASA used in on-site emulsification.

SUMMARY

[0005] In order to overcome the defects in the prior art, the present invention provides a W/O/O type AKD/ASA composite emulsion using sodium dodecyl sulfonate and montmorillonite (MMT) for cooperative emulsification and stabilization. The emulsion as a papermaking sizing agent has higher stability and sizing activity.

[0006] In order to achieve the above objective, the present invention adopts the following technical solution:

[0007] A preparation method of an AKD/ASA composite emulsion includes the following steps: (1) mixing AKD oil with perfluorohexane, and performing uniform stirring to obtain AKD-P oil; (2) mixing a montmorillonite (MMT) aqueous dispersion with acetone, ammonia monohydrate and cetyltrimethylsiloxane, and performing uniform dispersion to obtain a mixed solution I;

> LU500291 adding perfluorooctyltriethoxysilane into the mixed solution I, and performing ultrasonic dispersion to obtain a mixed solution II; and drying the mixed solution II to obtain modified MMT powder; (3) mixing the modified MMT powder with ASA, adding the AKD-P oil for mixing after uniform dispersion, and performing ultrasonic emulsification to obtain an AKD-P/ASA emulsion; and (4) mixing the AKD-P/ASA emulsion with a sodium dodecyl sulfonate aqueous solution, and performing ultrasonic emulsification to obtain the ASA/AKD composite emulsion.

[0008] The AKD oil is AKD in aliquid state at a normal temperature, and the AKD in the liquid state is a branched saturated fatty acid type alkyl ketene dimer with a great number of isomers after catalytic hydroisomerization of partial unsaturated fatty acids.

[0009] A mass ratio of the AKD oil to the perfluorohexane is 1:0.05-0.5.

[0010] The MMT is flaky nanoparticles, a diameter is in a range of 25 to 100 nm, and a thickness is in a range of 2 to 10 nm.

[0011] In the mixed solution I, a mass percentage of the MMT is in a range of 0.05 to 2%, a mass percentage of the acetone is in a range of 0.1 to 1%, and a mass percentage of the ammonia monohydrate is in a range of 0.5 to 2%.

[0012] A consumption of the cetyltrimethylsiloxane is 2 to 30 % of the mass of the MMT.

[0013] A consumption of the perfluorooctyltriethoxysilane is 5 to 20% of the mass of the MMT.

[0014] A mass ratio of the modified MMT powder to the ASA is 1:20-100.

[0015] A mass ratio of the AKD-P oil to the ASA is 1:0.1-2.

[0016] A mass ratio of the AKD-P/ASA emulsion to the sodium dodecyl sulfonate aqueous solution is 1:0.5-10.

[0017] A mass percentage of the sodium dodecyl sulfonate aqueous solution is in a range of 0.1 to 2%, and preferably 0.2 to 1%. A dispersion mode is able to be mechanical stirring, and is also able to be ultrasonic dispersion, and the ultrasonic power is in a range of 500 to 3000 W.

[0018] An AKD/ASA composite emulsion obtained by using the above preparation method is provided.

[0019] Application of the above ASA/AKD composite emulsion to preparation of paper is provided.

[0020] The application refers to application of the ASA/AKD composite emulsion used as a paper sizing agent.

[0021] The present invention has the following advantages: The AKD/ASA composite papermaking sizing agent emulsion of the present invention includes cetyltrimethylsiloxane and perfluorooctyltriethoxysilane modified MMT nanoparticles, ASA oil containing perfluorohexane, AKD oil in a liquid state and a sodium dodecyl sulfonate surfactant. Through graft modification on hydroxyl groups on surfaces of the MMT nano particles, fluorocarbon-oil-phase-lipophilic groups -(CF2)>(CF2)sCF3; and hydrocarbon-oil- phase-lipophilic groups -(CH»)15CHz are obtained on the surfaces of the MMT particles, and at the same time, the AKD-P oil has fluorocarbon groups, so that the MMT nanoparticles gain the capability of emulsifying and stabilizing the AKD-P and the ASA at the same time, and an O/O emulsion is formed. Finally, the AKD-P/ASA emulsion is emulsified by sodium dodecyl sulfonate to form the W/O/O type AKD/ASA composite emulsion. The AKD is coated at an outer layer, so that an ASA oil phase in an innermost layer is prevented from being in contact with a water phase at an outermost layer, so that the emulsion has high stability and strong hydrolysis resistance. Additionally, compared with a traditional wax-like AKD papermaking sizing agent, the AKD in a liquid state does not need to be melt at a high temperature in use and can be emulsified at a normal temperature, thus greatly reducing steam consumption and lowering the production cost. The liquid AKD is a branched saturated fatty acid with a great number of isomers obtained after catalytic hydroisomerization of partial unsaturated fatty acids. Under the condition of unchanged total carbon number, its linear carbon number is decreased, the produced paper cannot easily slip, and the slippery problem of the paper can be effectively solved.

[0022] The AKD/ASA composite sizing agent finally prepared and obtained by the present invention is a W/O/O composite emulsion type emulsion. The ASA is coated with AKD, and is distributed in water in a form of spherical dispersed liquid drops. The modified MMT is adsorbed in an oil-oil interface position between the AKD and the ASA in a form of solid particles, and stabilizes the AKD-ASA interface to form an oil-oil emulsion, the liquid drops of the AKD/ASA emulsion exist in a disperse phase of the liquid drops of the emulsion, a continuous phase is the sodium dodecyl sulfonate aqueous solution, the liquid drops of the finally obtained O/O/W type AKD/ASA emulsion are coated with the outer layer oil phase AKD, and the contact between the ASA and the water phase is avoided, so that the goal of preventing ASA hydrolysis is achieved. At the same time, the AKD and ASA duplex sizing performance is realized, and the water-resistant performance of sized paper can be further improved.

BRIEF DESCRIPTION OF DRAWINGS

[0023] FIG. 1 is a micrograph of an AKD/ASA composite emulsion prepared according to Embodiment 2.

DETAILED DESCRIPTION

[0024] The present invention will be further illustrated with reference to embodiments and drawings hereafter, but the present invention is not limited to the following embodiments.

[0025] Embodiment 1 Preparation of AKD/ASA composite emulsion (1) AKD oil was mixed with perfluorohexane according to a mass ratio of 1:0.05, and uniform stirring was performed to obtain AKD-P oil. (2) 1 weight part of MMT (an average width of a single particle was 25 nm, and a thickness was 2 nm) was dispersed in water to be prepared into a dispersion with a mass percentage of

0.05%. 2 weight parts of acetone, 10 weight parts of ammonia monohydrate and 0.02 weight part of cetyltrimethylsiloxane were added for mixing. Ultrasonic treatment was performed for I h at 25°C and 500 W to obtain a mixed solution I. Then, 0.05 weight part of perfluorooctyltriethoxysilane was added. Ultrasonic treatment was continuously performed for 1 h to obtain a mixed solution II. The mixed solution II was dried at 105°C to obtain modified MMT powder. (3) 1 weight part of modified MMT powder and 20 weight parts of ASA were mixed, and ultrasonic dispersion was performed for 1 h at 500 W. Then, 200 weight parts of AKD-P oil was added for mixing. Ultrasonic emulsification was performed for 15 min at S00 W to obtain an O/O type AKD-P/ASA emulsion.

(4) 2 weight parts of AKD-P/ASA emulsion and 1 weight part of sodium dodecyl sulfonate aqueous solution with a mass centration of 0.1% were mixed. Ultrasonic emulsification was performed for 15 min at 500 W to obtain an O/O/W type ASA/AKD composite emulsion.

[0026] Embodiment 2 Preparation of AKD/ASA composite emulsion (1) AKD oil was mixed with perfluorohexane according to a mass ratio of 1:1, and uniform stirring was performed to obtain AKD-P oil. (2) 1 weight part of MMT (an average width of a single particle was 45 nm, and a thickness was 5 nm) was dispersed in water to be prepared into a dispersion with a mass percentage of 1%. 10 weight parts of acetone, 20 weight parts of ammonia monohydrate and 0.2 weight part cetyltrimethylsiloxane were added for mixing. Ultrasonic treatment was performed for 1 h at 25°C and 1000 W to obtain a mixed solution I. Then, 0.1 weight part of perfluorooctyltriethoxysilane was added. Ultrasonic treatment was continuously performed for 1 h to obtain a mixed solution II. The mixed solution II was dried at 105°C to obtain modified MMT powder. (3) 1 weight part of modified MMT powder and 60 weight parts of ASA were mixed, and ultrasonic dispersion was performed for 1 h at 1000 W. Then, 60 weight parts of AKD-P oil was added for mixing. Ultrasonic emulsification was performed for 15 min at 1000 W to obtain an O/O type AKD-P/ASA emulsion. (4) 1 weight part of AKD-P/ASA emulsion and 5 weight parts of sodium dodecyl sulfonate aqueous solution with a mass centration of 0.5% were mixed. Ultrasonic emulsification was performed for 15 min at 1000 W to obtain an O/O/W type ASA/AKD composite emulsion. The obtained composite emulsion was observed under a microscope, and a micrograph was as shown in FIG. 1: the AKD/ASA emulsion used the sodium dodecyl sulfonate aqueous solution as a continuous phase and used the AKD/ASA emulsion as a disperse phase to realize uniform distribution; and the AKD/ASA emulsion was adsorbed in an oil-oil interface position between the AKD and the ASA through modified MMT in a form of solid particles, and forms an oil-oil emulsion containing ASA coated with AKD.

[0027] Embodiment 3 Preparation of AKD/ASA composite emulsion (1) AKD oil was mixed with perfluorohexane according to a mass ratio of 1:2, and uniform stirring was performed to obtain AKD-P oil. (2) 2 weight part of MMT (an average width of a single particle was 100 nm, and a thickness was 10 nm) was dispersed in water to be prepared into a dispersion with a mass percentage of 2%. 1 weight part of acetone, 2 weight parts of ammonia monohydrate and 0.6 weight part cetyltrimethylsiloxane were added for mixing. Ultrasonic treatment was performed for 1 h at 25°C and 3000 W to obtain a mixed solution I. Then, 04 weight part of perfluorooctyltriethoxysilane was added. Ultrasonic treatment was continuously performed for 1 h to obtain a mixed solution II. The mixed solution II was dried at 105°C to obtain modified MMT powder. (3) 1 weight part of modified MMT powder and 100 weight parts of ASA were mixed, and ultrasonic dispersion was performed for 1 h at 3000 W. Then, 10 weight parts of AKD-P oil was added for mixing. Ultrasonic emulsification was performed for 15 min at 3000 W to obtain an O/O type AKD-P/ASA emulsion. (4) 1 weight part of AKD-P/ASA emulsion and 10 weight parts of sodium dodecyl sulfonate aqueous solution with a mass centration of 1% were mixed. Ultrasonic emulsification was performed for 15 min at 3000 W to obtain an O/O/W type ASA/AKD composite emulsion.

[0028] Comparative example 1 The operation was according to a method of preparing a composite ASA sizing agent emulsion in Embodiment 3 in patent 201310108087.X (preparation method of papermaking sizing agent emulsified and stabilized by solid particles). The difference was that paraffin oil was substituted by an ASA/AKD composite emulsion sizing agent prepared from AKD oil.

[0029] Application example Performance determination of AKD/ASA composite emulsion used as paper sizing agent (1) Making of sized paper with pulp An internal sizing method was adopted for sizing. Before sizing, an AKD/ASA composite papermaking sizing agent emulsion was diluted to 0.5%, a paper pulp concentration was adjusted to 1%, and 1% aluminum sulfate (relative to a mass percentage of absolute dry paper pulp) was firstly added into paper pulp at a stirring speed of 1000 rpm. Then, a pulp pH value was adjusted to 7 to 8.5 by 1 mol/L of sodium hydroxide solution. Next, the diluted AKD/ASA to LU500291 composite papermaking sizing agent emulsion (the consumption was 0.5%, a percentage of the total mass of the ASA/AKD relative to the total mass of absolute dry paper pulp) and cationic polyacrylamide with the consumption of 0.03% (a mass percentage relative to absolute dry paper pulp) were added. Next, stirring was performed by a stirrer for 2 min at a shearing speed of 1000 rpm. Still standing was performed for 30 s. Then, handsheets was made by a PTI paper making device (model: RK3AKWT, place of origin: Austria), a quantitative index of the handsheets was 60 g/m? (T205 om-88, TAPPI), and a sheet making system selected a K-then method manual papermaking mode for papermaking with pulp according to standards 1SO5289/2 and DIN54358. The made handsheets were dried at 105°C, a paper moisture content was balanced for 24 h at a room temperature, and an environment humidity was 50%.

[0030] (2) Measuring method of sizing value The sizing performance was elevated by measuring a sizing value of paper made with pulp (GB/T5405-2002). Before measurement, the paper was cut into a square paper sheet being 30x30 mm, and was put in an environment with a temperature of 25°C and a humidity of 50% for moisture content balance for 24 h. Four edges of the paper sheet were folded up to form a boat-shaped structure with a bottom surface area being about 20x20 mm. Then, the boat-shaped structure floated in an ammonium thiocyanate dilute solution with a concentration of 2%, a drop of 0.5 uL of ferric chloride solution with a mass concentration of 1% was dripped on an upper portion of the boat-shaped paper sheet by a dropper, and at the same time, timing was performed by a stopwatch. The timing was completed when a red spot occurred in a middle portion of the ferric chloride liquid drop. The time was the sizing value of this paper sample. Each of a front side and a back side of the tested sample was tested for 10 times, and an average value was taken.

[0031] (3) Measurement method of average particle size of liquid drops Diameters of 100 emulsion liquid drops observed under a microscope were counted by a particle size statistic software of an optical microscope, an average value was taken and was the average particle size of the liquid drops.

3.5+0. ve 3 100 100 100 385+15 125+8 1243 example According to Table 1, the AKD/ASA composite emulsion prepared by the present invention had the smaller average particle size of the liquid drops, the emulsion had no phase separated out and no emulsion breaking phenomenon after placement for 30 days, and this showed that the AKD/ASA composite emulsion prepared by the present invention had good stability; the paper sizing value of paper sized in an internal sizing manner was 2400 to 2600 s at a consumption of 0.2% (mass ratio of ASA/AKD to absolute dry pulp), this showed that the emulsion had excellent sizing performance; additionally, when the emulsion was used after 30 days, the sizing value of the sized paper was in a range of 2100 to 2500 s, and this showed that the emulsion had good hydrolysis resistance; and the sizing value was reduced (about 100 to 300 s) along with the placement time (within 30 days), this was because partial AKD was hydrolyzed, the sizing activity was reduced, but the inner layer ASA was effectively protected, so that the sizing activity of the sizing agent was still kept at a higher level.

Claims

CLAIMS:

1. À preparation method of an AKD/ASA composite emulsion, comprising the following steps: (1) mixing AKD oil with perfluorohexane, and performing uniform stirring to obtain AKD-P ail; (2) mixing a montmorillonite aqueous dispersion with acetone, ammonia monohydrate and cetyltrimethylsiloxane, and performing uniform dispersion to obtain a mixed solution I; adding perfluorooctyltriethoxysilane into the mixed solution I, and performing ultrasonic dispersion to obtain a mixed solution II; and drying the mixed solution II to obtain modified MMT powder; (3) mixing the modified MMT powder with ASA, adding the AKD-P oil for mixing after uniform dispersion, and performing ultrasonic emulsification to obtain an AKD-P/ASA emulsion; and (4) mixing the AKD-P/ASA emulsion with a sodium dodecyl sulfonate aqueous solution, and performing ultrasonic emulsification to obtain the ASA/AKD composite emulsion.

2. The preparation method according to claim 1, wherein the AKD oil is AKD in a liquid state at a normal temperature, and a mass ratio of the AKD oil to the perfluorohexane is 1:0.05-

0.5.

3. The preparation method according to claim 1, wherein the montmorillonite is flaky nanoparticles, a diameter is in a range of 25 to 100 nm, and a thickness is in a range of 2 to 10 nm; in the mixed solution I, a mass percentage of the montmorillonite is in a range of 0.05 to 2%, a mass percentage of the acetone is in a range of 0.1 to 1%, and a mass percentage of the ammonia monohydrate is in a range of 0.5 to 2%; and a consumption of the cetyltrimethylsiloxane is 2 to 30 % of the mass of the montmorillonite, and a consumption of the perfluorooctyltriethoxysilane is 5 to 20% of the mass of the montmorillonite.

4. The preparation method according to claim 1, wherein a mass ratio of the modified MMT powder to the ASA is 1:20-100, and a mass ratio of the AKD-P oil to the ASA is 1:0.1-2.

5. The preparation method according to claim 1, wherein a mass ratio of the AKD-P/ASA emulsion to the sodium dodecyl sulfonate aqueous solution 1s 1:0.5-10, and a mass percentage of the sodium dodecyl sulfonate aqueous solution is in a range of 0.1 to 2%.

6. The preparation method according to claim 1, wherein a dispersion mode is able to be mechanical stirring, and is also able to be ultrasonic dispersion, and the ultrasonic power is in a range of 500 to 3000 W.

7. An AKD/ASA composite emulsion obtained by using the preparation method according to any one of claims 1 to 6.

8. Application of the AKD/ASA composite emulsion according to claim 7 to preparation of paper.

9. The application according to claim 8, wherein the AKD/ASA composite emulsion is used as a paper sizing agent.