Polyacrylic emulsion, preparation method and application thereof

Abstract

The present application relates to a kind of polyacrylic acid emulsion and its preparation method, application.The polyacrylic acid emulsion includes crosslinking agent, olefinic unsaturated monomer and unsaturated hydrophilic monomer, the structure of the crosslinking agent is: the emulsion is used in paper coating field and has excellent anti-sticking property.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of water-based resin and paint preparation technology, in particular to the field of paper coating, and specifically to a polyacrylic emulsion, a preparation method thereof and application thereof. BACKGROUND

[0002] The traditional coating scheme of paper products is PE (polyethylene) film coating, and the current alternative scheme is mainly emulsion resin replacement. Compared with PE film coating, the performance of emulsion coating film has certain defects, mainly manifested in poor adhesion. The current mainstream solution is a double-coating scheme, that is, in the case of ensuring resistance but lacking adhesion of the base coating, a layer of high-Tg emulsion is coated to separately make up for the adhesion. This scheme cannot guarantee that a single type of resin can meet all requirements at one time, and multiple coatings and drying must be performed by switching resins, which greatly reduces production efficiency. Therefore, it is of great significance to develop a new paper coating emulsion with excellent adhesion. SUMMARY

[0003] In view of the above deficiencies in the prior art, the purpose of the present application is to provide a polyacrylic emulsion and a preparation method thereof.

[0004] Another purpose of the present application is to provide application of the polyacrylic emulsion in the field of paper coating.

[0005] A polyacrylic emulsion, raw materials of which comprise the following components:

[0006] A) 4.5-15wt% of a crosslinking agent;

[0007] B) 80-93wt% of an olefinically unsaturated monomer;

[0008] C) 2-10wt% of an unsaturated hydrophilic monomer.

[0009] The total mass of component A), component B) and component C) is 100%.

[0010] The structure of the crosslinking agent is:

[0011]

[0012] R1 is -CH2CH2CH2-(OCH2CH2) p -(OCHCH3CH2) q -OH; wherein p is 8-20 and q is 3-10.

[0013] The crosslinking agent is prepared by reacting tetra(dimethylsiloxy)silane with allyl methacrylate and allyl polyether.

[0014] The preparation method of the crosslinking agent is as follows:

[0015] Tetra(dimethylsiloxy)silane and Karstedt's catalyst are added into the reactor, then allyl methacrylate and allyl polyether are added simultaneously for reaction, and the reaction temperature is controlled to be no more than 110℃.

[0016] Preferably, the allyl methacrylate and the allyl polyether are added in a dropwise manner, and after the dropwise addition is completed, the reaction is kept for a period of time.

[0017] Preferably, the molar ratio of tetra(dimethylsiloxy)silane, allyl methacrylate, and allyl polyether is 1:2.9-3.1:0.9-1.1.

[0018] The structure of the allyl polyether is CH2=CHCH2-(OCH2CH2) p -(OCHCH3CH2) q -OH, wherein p is 8-20, and q is 3-10.

[0019] Preferably, the Karstedt's catalyst includes but is not limited to 1,3-divinyl-tetramethyldisiloxane-0-platinum.

[0020] Preferably, the amount of the catalyst added is 0.01-0.2wt% of the total mass of the reaction system.

[0021] In order to facilitate the reaction, the allyl methacrylate and the allyl polyether can be preheated to a temperature of 40-70℃ before being added. The reaction is an exothermic reaction, and the temperature will rise as the reaction proceeds. The dropwise addition rate needs to be controlled so that the reaction temperature is no more than 110℃.

[0022] Preferably, the olefinically unsaturated monomer is selected from any one or at least two combinations of (methyl)styrene, (methyl) methyl acrylate, (methyl) ethyl acrylate, (methyl) butyl acrylate, (methyl) 2-ethylhexyl acrylate, (methyl) tert-butyl acrylate, (methyl) isobutyl acrylate, (methyl) isobornyl acrylate, (methyl) lauryl acrylate, and (methyl) stearyl acrylate, and preferably any one or two or more combinations of methyl methacrylate and butyl acrylate.

[0023] The unsaturated hydrophilic monomer is selected from any one or two or more combinations of (methyl) acrylic acid.

[0024] The application also provides a preparation method of the polyacrylic acid emulsion, comprising the following steps:

[0025] 1) adding component A), component B), component C), water, and part of the emulsifier into a pre-emulsification kettle to prepare a pre-emulsified solution;

[0026] The emulsifier is preferably one or more of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, alcohol ether sulfosuccinate, alkyl alcohol ether sulfate, and alkyl alcohol ether phosphate;

[0027] 2) Dissolve part of the initiator in water to obtain a dropping initiator; dissolve the remaining initiator in water to obtain a bottom initiator;

[0028] The initiator is preferably one or more of sodium persulfate, potassium persulfate, and ammonium persulfate;

[0029] 3) After mixing the remaining emulsifier with water, add it to the reaction kettle, and after stirring thoroughly, heat it to 80-90℃; add part of the pre-emulsion, and after stirring uniformly, add all the bottom initiator, and react for 10-20min to prepare a seed emulsion;

[0030] 4) Control the temperature in the reaction kettle at 80-90℃, continue to add the remaining pre-emulsion and all the dropping initiator to the seed emulsion, drop for 2-4h, and then incubate for 20-60min;

[0031] 5) Cool the reaction kettle to 70-80℃, and gradually add a post-treatment agent to the reaction kettle within 20-60min, and then incubate for 30-60min;

[0032] The post-treatment agent is an oxidizing agent and / or a reducing agent, the oxidizing agent is one or more of tert-butyl peroxide, hydrogen peroxide, sodium persulfate, potassium persulfate, and ammonium persulfate; and the reducing agent is one or more of sodium bisulfite, sodium metabisulfite, and vitamin C;

[0033] 6) Cool to below 45℃, add a pH regulator to adjust the pH of the system to 7-9, and filter the product;

[0034] The pH regulator is preferably one or more of ammonia, sodium hydroxide, diethylene triamine, diethanolamine, and ethanolamine.

[0035] The polyacrylic acid emulsion of the application is used for paper coating.

[0036] A paper coating emulsion uses the polyacrylic acid emulsion of the application as a paper coating emulsion.

[0037] Using the polyacrylic acid emulsion of the application as a paper coating emulsion has more obvious excellent anti-sticking performance. The existing double-coating scheme, i.e. coating a high-Tg emulsion on the base coating to compensate for the lack of anti-sticking performance, cannot guarantee that a single type of resin can meet all requirements at one time, and requires switching resins and multiple coating and drying, which greatly reduces production efficiency. The scheme of the application can simultaneously meet the requirements of resistance and anti-sticking performance after coating, and can greatly improve efficiency. DETAILED DESCRIPTION

[0038] The following examples will further illustrate the present application but do not limit the present application.

[0039] The raw materials used in the examples and comparative examples and their sources are shown in Table 1. Other raw materials used were commercially available and ordinary unless otherwise specified.

[0040] Table 1 Raw materials and sources

[0041]

[0042]

[0043] Product performance test method for the examples and comparative examples:

[0044] Paper coating sample preparation: The base paper was coated with a 5 μm wire bar to form a film, and then placed in a 120°C oven for 30 seconds. The coated paper was then removed and a second coating was applied using the same method, and dried under the same conditions.

[0045] Anti-blocking performance test: The coated paper and uncoated paper were cut into 5*5 cm pieces, and the blocking of the coating to the coating and the coating to the paper was tested under a 3 kg weight pressure in a 50°C oven. The blocking at different times was recorded.

[0046] Anti-blocking performance rating standards are as follows

[0047] 0 grade, no blocking, no resistance to separation, and can be separated

[0048] 1 grade, no blocking, very small resistance to separation, and cannot be separated

[0049] 2 grade, slight blocking, small resistance to separation, and no damage after separation

[0050] 3 grade, slight blocking, general resistance to separation, and no damage after separation

[0051] 4 grade, blocking, obvious resistance to separation, and no damage or 1-2 point damage after separation

[0052] 5 grade, complete blocking, and large area damage to the base material after separation.

[0053] Crosslinking agent-1

[0054] The crosslinking agent-1 of the present application is prepared as follows:

[0055] Put 328.78 g (1 mol) of tetra (dimethylsiloxy) silane and 1.8 g of Karstedt catalyst into a reaction kettle, start stirring and heating, and raise the temperature to 60°C. Simultaneously, add 378.6 g (3 mol) of allyl methacrylate and 742 g (1 mol, q=5, p=8) of allyl polyether into the reaction kettle dropwise. As the reaction proceeds, the temperature will rise. Control the dropwise addition rate to keep the reaction temperature below 110°C.

[0056] After the dropwise addition is completed, heat at 110°C for 1 hour, and then detect the residual silicon hydride, which is <10 ppm.

[0057] Crosslinking agent-2

[0058] The crosslinking agent-2 (comparative example) of the present application is prepared as follows:

[0059] Put 328.78 g (1 mol) of tetra (dimethylsiloxy) silane and 1.8 g of Karstedt catalyst into a reaction kettle, start stirring and heating, and raise the temperature to 60°C. Simultaneously, add 378.6 g (3 mol) of allyl methacrylate into the reaction kettle dropwise. As the reaction proceeds, the temperature will rise. Control the dropwise addition rate to keep the reaction temperature below 110°C.

[0060] After the dropwise addition is completed, heat at 110°C for 1 hour, and then detect the residual silicon hydride, which is <10 ppm.

[0061] Comparative example 1

[0062] Put 475 g of water, 7 g of SDS, 570 g of MMA, 820 g of BA, and 45 g of AA into a pre-emulsification kettle, and stir to prepare a pre-emulsified liquid. Dissolve 2 g of APS in 150 g of water to obtain a dropwise initiator. Dissolve 3 g of APS in 50 g of water to obtain a kettle bottom initiator. Dissolve 1 g of t-butyl hydroperoxide (t-BHP) and 0.5 g of isoascorbic acid (IAA) in 20 g of water respectively to obtain post-treatment agents.

[0063] Mix 2.5 g of SDS with 1000 g of water, and then add to a reaction kettle. After stirring thoroughly, raise the temperature to 85°C. Add 20 g of pre-emulsified liquid, and after stirring uniformly, add all of the kettle bottom initiator. React for 10-20 min to prepare a seed emulsion. Control the temperature in the reaction kettle to be 85°C, and continue to add the remaining pre-emulsified liquid and all of the dropwise initiator to the seed emulsion. Dropwise addition is performed for 4 h, and then heat for 60 min.

[0064] Lower the temperature in the reaction kettle to 70°C, and then gradually add the post-treatment agents to the reaction kettle within 30 min. Then heat for 30 min. Lower the temperature to below 45°C, add a pH adjuster to adjust the pH of the system to 7.5, and filter the product.

[0065] Comparative example 2

[0066] Into a pre-emulsification kettle, 475 g of water, 7 g of SDS, 570 g of MMA, 820 g of BA, 45 g of AA and 72 g of crosslinking agent-2 were added to prepare a pre-emulsion liquid by stirring; 2 g of APS was dissolved in 150 g of water to obtain a dropwise initiator; 3 g of APS was dissolved in 50 g of water to obtain a kettle bottom initiator; 1 g of t-BHP and 0.5 g of IAA were respectively dissolved in 20 g of water to obtain a post-treatment agent.

[0067] After 2.5 g of SDS was mixed with 1000 g of water and added to the reaction kettle, the temperature was increased to 85°C after sufficient stirring; 20 g of the pre-emulsion liquid was added, and after uniform stirring, all of the kettle bottom initiator was added, and the reaction was carried out for 10-20 min to prepare a seed emulsion; the temperature in the reaction kettle was controlled at 85°C, and the remaining pre-emulsion liquid and all of the dropwise initiator were continuously added to the seed emulsion, dropwise addition was carried out for 4 h, and then the temperature was maintained for 60 min;

[0068] The reaction kettle was cooled to 70°C, and the post-treatment agent was gradually added to the reaction kettle within 30 min, and then the temperature was maintained for 30 min; the temperature was cooled to below 45°C, a pH regulator was added to adjust the pH of the system to 7.5, and the product was filtered out.

[0069] Comparative Example 3

[0070] Into a pre-emulsification kettle, 475 g of water, 7 g of SDS, 570 g of MMA, 820 g of BA, 45 g of AA and 72 g of crosslinking agent-2 were added to prepare a pre-emulsion liquid by stirring; 2 g of APS was dissolved in 150 g of water to obtain a dropwise initiator; 3 g of APS was dissolved in 50 g of water to obtain a kettle bottom initiator; 1 g of t-BHP and 0.5 g of IAA were respectively dissolved in 20 g of water to obtain a post-treatment agent.

[0071] After 2.5 g of SDS was mixed with 1000 g of water and added to the reaction kettle, the temperature was increased to 85°C after sufficient stirring; 20 g of the pre-emulsion liquid was added, and after uniform stirring, all of the kettle bottom initiator was added, and the reaction was carried out for 10-20 min to prepare a seed emulsion; the temperature in the reaction kettle was controlled at 85°C, and the remaining pre-emulsion liquid and all of the dropwise initiator were continuously added to the seed emulsion, dropwise addition was carried out for 4 h, and then the temperature was maintained for 60 min;

[0072] The reaction kettle was cooled to 70°C, and the post-treatment agent was gradually added to the reaction kettle within 30 min, and then the temperature was maintained for 30 min; the temperature was cooled to below 45°C, a pH regulator was added to adjust the pH of the system to 7.5, and the product was filtered out.

[0073] Comparative Example 4

[0074] Into a pre-emulsification kettle, 475 g of water, 7 g of SDS, 570 g of MMA, 820 g of BA, 45 g of AA and 215 g of crosslinking agent-2 were added, and stirring was performed to prepare a pre-emulsion; 2 g of APS was dissolved in 150 g of water to obtain a dropwise initiator; 3 g of APS was dissolved in 50 g of water to obtain a kettle bottom initiator; 1 g of t-BHP and 0.5 g of IAA were respectively dissolved in 20 g of water to obtain a post-treatment agent.

[0075] After 2.5 g of SDS was mixed with 1000 g of water and added into a reaction kettle, the temperature was increased to 85°C after sufficient stirring; 20 g of pre-emulsion was added, and after uniform stirring, all of the kettle bottom initiator was added, and the reaction was performed for 10-20 min to prepare a seed emulsion; the temperature in the reaction kettle was controlled at 85°C, and the remaining pre-emulsion and all of the dropwise initiator were continuously added to the seed emulsion, dropwise addition was performed for 4 h, and then the temperature was maintained for 60 min;

[0076] The reaction kettle was cooled to 70°C, and the post-treatment agent was gradually added to the reaction kettle within 30 min, and then the temperature was maintained for 30 min; the temperature was cooled to below 45°C, a pH regulator was added, the pH of the system was adjusted to 7.5, and the material was filtered out.

[0077] Example 1

[0078] Into a pre-emulsification kettle, 475 g of water, 7 g of SDS, 570 g of MMA, 820 g of BA, 45 g of AA and 72 g of crosslinking agent-1 were added, and stirring was performed to prepare a pre-emulsion; 2 g of APS was dissolved in 150 g of water to obtain a dropwise initiator; 3 g of APS was dissolved in 50 g of water to obtain a kettle bottom initiator; 1 g of t-BHP and 0.5 g of IAA were respectively dissolved in 20 g of water to obtain a post-treatment agent.

[0079] After 2.5 g of SDS was mixed with 1000 g of water and added into a reaction kettle, the temperature was increased to 85°C after sufficient stirring; 20 g of pre-emulsion was added, and after uniform stirring, all of the kettle bottom initiator was added, and the reaction was performed for 10-20 min to prepare a seed emulsion; the temperature in the reaction kettle was controlled at 85°C, and the remaining pre-emulsion and all of the dropwise initiator were continuously added to the seed emulsion, dropwise addition was performed for 4 h, and then the temperature was maintained for 60 min;

[0080] The reaction kettle was cooled to 70°C, and the post-treatment agent was gradually added to the reaction kettle within 30 min, and then the temperature was maintained for 30 min; the temperature was cooled to below 45°C, a pH regulator was added, the pH of the system was adjusted to 7.5, and the material was filtered out.

[0081] Example 2

[0082] Into a pre-emulsification kettle, 475 g of water, 7 g of SDS, 540 g of MMA, 820 g of BA, 105 g of AA and 143 g of crosslinking agent-1 were added, and stirring was performed to prepare a pre-emulsion; 2 g of APS was dissolved in 150 g of water to obtain a dropwise initiator; 3 g of APS was dissolved in 50 g of water to obtain a kettle bottom initiator; 1 g of t-BHP and 0.5 g of IAA were respectively dissolved in 20 g of water to obtain a post-treatment agent.

[0083] After 2.5 g of SDS was mixed with 1000 g of water and added into a reaction kettle, the temperature was increased to 85°C after sufficient stirring; 20 g of pre-emulsion was added, and after uniform stirring, all of the kettle bottom initiator was added, and the reaction was performed for 10-20 min to prepare a seed emulsion; the temperature in the reaction kettle was controlled at 85°C, and the remaining pre-emulsion and all of the dropwise initiator were continuously added to the seed emulsion, dropwise addition was performed for 4 h, and then the temperature was maintained for 60 min;

[0084] The reaction kettle was cooled to 70°C, and the post-treatment agent was gradually added into the reaction kettle within 30 min, and then the temperature was maintained for 30 min; the temperature was cooled to below 45°C, a pH regulator was added, the pH of the system was adjusted to 7.5, and the product was filtered out.

[0085] Example 3

[0086] Into a pre-emulsification kettle, 475 g of water, 7 g of SDS, 570 g of MMA, 820 g of BA, 45 g of AA and 215 g of crosslinking agent-1 were added, and stirring was performed to prepare a pre-emulsion; 2 g of APS was dissolved in 150 g of water to obtain a dropwise initiator; 3 g of APS was dissolved in 50 g of water to obtain a kettle bottom initiator; 1 g of t-BHP and 0.5 g of IAA were respectively dissolved in 20 g of water to obtain a post-treatment agent.

[0087] After 2.5 g of SDS was mixed with 1000 g of water and added into a reaction kettle, the temperature was increased to 85°C after sufficient stirring; 20 g of pre-emulsion was added, and after uniform stirring, all of the kettle bottom initiator was added, and the reaction was performed for 10-20 min to prepare a seed emulsion; the temperature in the reaction kettle was controlled at 85°C, and the remaining pre-emulsion and all of the dropwise initiator were continuously added to the seed emulsion, dropwise addition was performed for 4 h, and then the temperature was maintained for 60 min;

[0088] The reaction kettle was cooled to 70°C, and the post-treatment agent was gradually added into the reaction kettle within 30 min, and then the temperature was maintained for 30 min; the temperature was cooled to below 45°C, a pH regulator was added, the pH of the system was adjusted to 7.5, and the product was filtered out.

[0089] Example 4

[0090] Into a pre-emulsification kettle, 475 g of water, 7 g of SDS, 540 g of MMA, 795 g of BA, 90 g of AA and 215 g of crosslinker-1 were added, and stirring was performed to obtain a pre-emulsion; 2 g of APS was dissolved in 150 g of water to obtain a dropwise initiator; 3 g of APS was dissolved in 50 g of water to obtain a kettle bottom initiator; 1 g of t-BHP and 0.5 g of IAA were respectively dissolved in 20 g of water to obtain post-treatment agents.

[0091] After 2.5 g of SDS was mixed with 1000 g of water and added into a reaction kettle, the mixture was fully stirred and heated to 85°C; 20 g of pre-emulsion was added, and after being fully stirred, all of the kettle bottom initiator was added, and the reaction was performed for 10-20 min to obtain a seed emulsion; the temperature in the reaction kettle was controlled at 85°C, and the remaining pre-emulsion and all of the dropwise initiator were continuously added to the seed emulsion, dropwise addition was performed for 4 h, and then the mixture was kept for 60 min;

[0092] The reaction kettle was cooled to 70°C, and the post-treatment agents were gradually added to the reaction kettle within 30 min, and then the mixture was kept for 30 min; the temperature was cooled to below 45°C, a pH regulator was added to adjust the pH of the system to 7.5, and the product was filtered.

[0093] The emulsions prepared in the examples and comparative examples were coated on paper substrates to test the anti-blocking performance, and the results are shown in the following table.

[0094] Table 2 Anti-blocking test comparison of paper coating

[0095] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Example 1 Example 2 Example 3 Example 4 Tg 10 10 10 10 10 10 10 10 Tack resistance 5 4 4 4 1 0 0 0

Claims

1. A polyacrylic emulsion, characterized in that, The raw material comprises the following components: A) 4.5-15wt% of crosslinking agent; B) 80-93wt% of olefinically unsaturated monomer; C) 2-10wt% of unsaturated hydrophilic monomer; The total mass of component A), component B), component C) is 100%; The structure of the crosslinking agent is: R1is -CH2CH2CH2-(OCH2CH2) p -(OCHCH3CH2) q -OH; wherein p is 8-20 and q is 3-10.

2. The emulsion of claim 1, wherein, The crosslinking agent is prepared by reacting tetra(dimethylsiloxy)silane with allyl methacrylate and allyl polyether.

3. The emulsion according to claim 1 or 2, characterized in that, The preparation method of the crosslinking agent is as follows: The tetra(dimethylsiloxy)silane and Karstedt catalyst are added into the reactor, and then allyl methacrylate and allyl polyether are added simultaneously for reaction.

4. The emulsion of claim 3, wherein, The allyl methacrylate and allyl polyether are added in a dropwise manner, and after the dropwise addition is completed, the reaction is kept for a period of time.

5. The emulsion of claim 3, wherein, The molar ratio of the tetra(dimethylsiloxy)silane, allyl methacrylate, and allyl polyether added is 1:2.9-3.1:0.9-1.

1.

6. The emulsion of claim 3, wherein, The Karstedt catalyst comprises 1,3-divinyl-tetramethyldisiloxane-0-platinum.

7. The emulsion of claim 3, wherein, The amount of the catalyst added is 0.01-0.2wt% of the total mass of the reaction system.

8. The emulsion of claim 3, wherein, said allyl polyether is CH2=CHCH2-(OCH2CH2) p -(OCHCH3CH2) q -OH, wherein p is 8-20 and q is 3-10.

9. The emulsion of claim 3, wherein, The allyl methacrylate and allyl polyether are preheated before being added, and the preheating temperature reaches 40-70℃; the reaction temperature is controlled to be no more than 110℃ during the reaction.

10. The emulsion of claim 1, wherein, The olefinically unsaturated monomer is selected from any one or at least two combinations of (methyl)styrene, (methyl) methyl acrylate, (methyl) ethyl acrylate, (methyl) butyl acrylate, (methyl) 2-ethylhexyl acrylate, (methyl) tert-butyl acrylate, (methyl) isobutyl acrylate, (methyl) isobornyl acrylate, (methyl) lauryl acrylate, and (methyl) stearyl acrylate.

11. The emulsion of claim 10, wherein, The olefinically unsaturated monomer is any one or more than two combinations of methyl methacrylate and butyl acrylate.

12. The emulsion of claim 1, wherein, The unsaturated hydrophilic monomer is selected from any one or two combinations of (methyl) acrylic acid.

13. A preparation method of the polyacrylic acid emulsion according to any one of claims 1-12, comprising the following steps: 1) adding component A), component B), component C), water, and part of the emulsifier into a pre-emulsification kettle to prepare a pre-emulsified solution; 2) dissolving part of the initiator in water to obtain a dropwise-added initiator, and dissolving the remaining initiator in water to obtain a kettle-bottom initiator; 3) mixing the remaining emulsifier with water, adding into the reaction kettle, and stirring well, then heating to 80-90℃, adding part of the pre-emulsified solution, and after stirring uniformly, adding all the kettle-bottom initiator, and reacting for 10-20min to prepare a seed emulsion; 4) controlling the temperature in the reaction kettle to be 80-90℃, continuously adding the remaining pre-emulsified solution and all the dropwise-added initiator into the seed emulsion, dropwise adding for 2-4h, and then keeping warm for 20-60min; 5) cooling the reaction kettle to 70-80℃, and adding the post-treatment agent into the reaction kettle gradually within 20-60min, and then keeping warm for 30-60min; 6) cooling and discharging.

14. The method of claim 13, wherein, The emulsifier is one or more of sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, alcohol ether sulfosuccinate, alkyl alcohol ether sulfate, and alkyl alcohol ether phosphate.

15. The preparation method according to claim 13, characterized in that, The initiator is one or more of sodium persulfate, potassium persulfate, and ammonium persulfate.

16. The method of claim 13, wherein, The post-treatment agent is an oxidizing agent and / or a reducing agent, the oxidizing agent is one or more of tert-butyl hydroperoxide, hydrogen peroxide, sodium persulfate, potassium persulfate, and ammonium persulfate; the reducing agent is one or more of sodium bisulfite, sodium metabisulfite, and vitamin C.

17. The method of claim 13, wherein, In step 6), the temperature is lowered to below 45℃, a pH regulator is added, the pH of the system is adjusted to 7-9, and the filtrate is obtained.

18. The method of claim 17, wherein, The pH regulator is one or more of ammonia, sodium hydroxide, diethylene triamine, diethanol amine, and ethanol amine.

19. A paper coating prepared using the emulsion of any one of claims 1-12 or the emulsion prepared by the method of claims 13-18.

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