CN109337023B

CN109337023B - Emulsion for PVDC composite film prime coat and synthetic method thereof

Info

Publication number: CN109337023B
Application number: CN201811125522.9A
Authority: CN
Inventors: 董海普; 王玉春; 李珊; 戴胜杰
Original assignee: Shanghai Weikai Optoelectronic New Materials Co Ltd; Shanghai Chengying New Material Co Ltd; Jiangsu Chengying New Material Co Ltd
Current assignee: Shanghai Weikai Optoelectronic New Materials Co Ltd; Shanghai Chengying New Material Co Ltd; Jiangsu Chengying New Material Co Ltd
Priority date: 2018-09-26
Filing date: 2018-09-26
Publication date: 2021-05-28
Anticipated expiration: 2038-09-26
Also published as: CN109337023A

Abstract

The invention relates to an emulsion for PVDC composite membrane prime coat and a synthesis method thereof, wherein the emulsion comprises the following components in parts by weight: 80-100 parts of water, 1-8 parts of styrene monomer, 60-80 parts of (meth) acrylic acid and ester monomer thereof, 0.1-10 parts of (meth) acrylamide monomer, 5-10 parts of functional monomer, 0.1-5 parts of organosilicon monomer, 0.1-10 parts of emulsifier, 0.1-3 parts of initiator, 0.1-3 parts of pH value buffering agent and 0.1-10 parts of neutralizer. The invention adopts polymerizable emulsifier to participate in monomer reaction, avoids residual emulsifier from absorbing water, adopts functional monomer and (methyl) acrylamide monomer for copolymerization, generates crosslinking reaction in the film forming and drying process to enable the film to be in a net structure, and simultaneously adds siloxane monomer for further crosslinking to enable the film to be more compact, thereby achieving the purpose of improving water and oxygen resistance. In addition, the invention adopts a high-speed emulsification process, and can further improve the stability of the reaction.

Description

Emulsion for PVDC composite film prime coat and synthetic method thereof

Technical Field

The invention relates to the technical field of priming paint, in particular to emulsion for priming a PVDC composite membrane and a synthesis method thereof.

Background

Polyvinylidene chloride (PVDC) has the advantages of symmetrical molecular structure, compact structure, high molecular cohesive energy, difficult movement of molecular chains, easy crystallization of molecules, excellent barrier property to oxygen and water (steam) and the like.

The PVDC emulsion is coated on various PE \ PP \ PET \ Nylon and other plastic base material films, so that the films have better heat-sealing property, air resistance, moisture resistance, aroma retention and other properties, and are widely applied to packages of foods, cigarettes, medicines and the like.

However, the surface tension of PVDC emulsions is high, typically in the range of 40 to 70 (mN/m). When coating the PVDC emulsion, although the base material film is subjected to corona treatment, the coating requirement can not be met, technical problems of shrinkage, incapability of spreading and the like are easily caused, and meanwhile, the adhesion of the PVDC to the base material is low. Therefore, it is desirable to apply a primer emulsion to a substrate film to improve the coating leveling and adhesion of the PVDC emulsion to the substrate film.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide an emulsion for priming a PVDC composite film and a synthesis method thereof. The emulsion can improve the coating leveling property and the adhesive force of the PVDC emulsion to a matrix film.

The purpose of the invention is realized by the following technical scheme:

the invention provides an emulsion for PVDC composite membrane prime coat, which comprises the following components in parts by weight:

preferably, the styrene monomer is at least one of styrene and methyl styrene.

Preferably, the (meth) acrylic acid and ester monomers thereof are at least one of acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, methacrylic acid, methyl methacrylate, n-butyl methacrylate, and isooctyl methacrylate.

Preferably, the (meth) acrylamide monomer is at least one of acrylamide and methacrylamide.

Preferably, the functional monomer is at least one of diacetone acrylamide and acetoacetoxyethyl methacrylate.

Preferably, the organosilicon monomer is at least one of vinyl trimethoxy silane, vinyl triethoxy silane, vinyl tri (beta-methoxyethoxy) silane and methacryloxypropyl trimethoxy silane.

Preferably, the emulsifier is an emulsifier containing polymerizable double bonds, and is at least one selected from allyloxy nonylphenoxypropanol polyoxyethylene ether ammonium sulfate, allyloxy nonylphenoxypropanol polyoxyethylene ether, 1-allyloxy-3- (4-nonylphenol) -2-propanol polyoxyethylene (10) ether monophosphoric acid; the initiator is at least one of sodium persulfate, ammonium persulfate, potassium persulfate, tert-butyl hydroperoxide and sodium bisulfite.

Preferably, the pH value buffering agent is at least one of ammonium bicarbonate, sodium carbonate, disodium hydrogen phosphate and dipotassium hydrogen phosphate; the neutralizer is ammonia water; the water is deionized water.

The invention also provides a synthesis method of the emulsion for the PVDC composite membrane prime coat, which comprises the following steps:

A. adding 40-50 parts of water, 0.05-2 parts of emulsifier and 0.01-1 part of pH buffering agent into a reaction kettle, and heating to 75-85 ℃;

B. preparing a pre-emulsion: mixing 30-50 parts of water, 0.05-8 parts of emulsifier and 0.09-2 parts of pH buffer, adding a mixture of styrene monomers, (meth) acrylic acid and ester monomers thereof, (meth) acrylamide monomers and functional monomers under high-speed stirring, adding, and stirring to prepare a pre-emulsion;

C. preparing an initiator solution: 5-10 parts of water and 0.05-1 part of initiator are stirred and mixed uniformly to prepare initiator solution;

D. preparing a seed emulsion: b, adding part of initiator solution and part of pre-emulsion into the reaction kettle heated in the step A, and preserving heat after the color turns blue to prepare seed emulsion;

E. simultaneously dripping the rest pre-emulsion and the rest initiator solution into the seed emulsion, adding the organic silicon monomer into the reaction kettle after dripping the pre-emulsion, and keeping the temperature;

F. after the reaction in the step E, cooling the emulsion to below 50 ℃, adding 0.05-2 parts of initiator, and continuing the reaction;

G. and F, continuously cooling to below 30 ℃ after the reaction in the step F, adding 0.1-10 parts of neutralizing agent to adjust the pH value of the emulsion to 6-9, and discharging to obtain the emulsion for the PVDC composite membrane base coat.

Preferably, in the step B, the stirring speed adopted by the high-speed stirring is 1000-3000rpm, and the stirring time after the addition is 0.5-2 h;

in the step D, the mass content of the added initiator solution is 5-60%, and the mass content of the added pre-emulsion is 5-20%; the heat preservation time is 0.5-5 h;

in the step E, the dropping temperature is 75-85 ℃, and the dropping time of the pre-emulsion and the initiator solution is 1-4 h; the dropping time of the organic silicon monomer is 1-4h, and the heat preservation time is 1-2 h;

in the step F, the reaction time is 1-2 h.

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

the PVDC composite film has the requirements of oxygen resistance and water resistance, the polymerizable emulsifier is adopted to participate in monomer reaction, the residual emulsifier is prevented from absorbing water, the functional monomer and the acrylamide monomer are copolymerized, a cross-linking reaction is carried out in the film forming and drying process to enable a film to be in a net structure, and simultaneously, the siloxane monomer is added for further cross-linking to enable the film to be more compact, so that the purpose of improving water resistance and oxygen resistance is achieved. In addition, the invention adopts a high-speed (1000-.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.

The following embodiment provides an emulsion for PVDC composite film prime coating, which comprises the following components in parts by weight:

the styrene monomer is at least one of styrene and methyl styrene.

The (methyl) acrylic acid and the ester monomer thereof are at least one of acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, methacrylic acid, methyl methacrylate, n-butyl methacrylate and isooctyl methacrylate.

The (methyl) acrylamide monomer is at least one of acrylamide and methacrylamide.

The functional monomer is at least one of diacetone acrylamide and acetoacetoxy ethyl methacrylate.

The organic silicon monomer is at least one of vinyl trimethoxy silane, vinyl triethoxy silane, vinyl tri (beta-methoxyethoxy) silane and methacryloxypropyl trimethoxy silane.

The emulsifier is an emulsifier containing polymerizable double bonds and is selected from at least one of allyloxy nonylphenoxy propanol polyoxyethylene ether ammonium sulfate, allyloxy nonylphenoxy propanol polyoxyethylene ether and 1-allyloxy-3- (4-nonylphenol) -2-propanol polyoxyethylene (10) ether monophosphoric acid; the initiator is at least one of sodium persulfate, ammonium persulfate, potassium persulfate, tert-butyl hydroperoxide and sodium bisulfite.

The pH value buffering agent is at least one of ammonium bicarbonate, sodium carbonate, disodium hydrogen phosphate and dipotassium hydrogen phosphate; the neutralizer is ammonia water; the water is deionized water.

The synthesis method of the emulsion for the PVDC composite membrane prime coat comprises the following steps:

In the step B, the stirring speed adopted by the high-speed stirring is 1000-3000rpm, and the stirring time after the addition is 0.5-2 h;

in the step D, the mass content of the added initiator solution is 5-60%, and the mass content of the added pre-emulsion is 5-20%; the heat preservation time is 0.5-5 h.

in the step F, the reaction time is 1-2 h.

Example 1

The embodiment provides an emulsion for PVDC composite membrane prime coating, the components and the content of the emulsion are shown in Table 1, and the specific preparation method comprises the following steps:

1. adding 40 parts of deionized water, 0.05 part of allyloxy nonyl phenoxy propanol polyoxyethylene ether ammonium sulfate and 0.5 part of sodium bicarbonate into the bottom of a reaction kettle, heating to 75 ℃, and keeping the temperature constant.

2. Adding 35 parts of deionized water, 0.05 part of allyloxy nonyl phenoxy propanol polyoxyethylene ether ammonium sulfate and 1 part of sodium carbonate into a dropping kettle, adding 5 parts of styrene, 3 parts of methyl styrene, 10 parts of acrylic acid, 35 parts of n-butyl acrylate, 10 parts of methyl methacrylate, 5 parts of isooctyl methacrylate, 5 parts of acrylamide and 5 parts of diacetone acrylamide into a monomer mixture under high-speed stirring at 1000rpm, and stirring at 1000rpm for 0.5h to prepare a pre-emulsion.

3. 5 parts of deionized water and 0.05 part of ammonium persulfate are added into an initiator dropping kettle and stirred and mixed uniformly to prepare an initiator solution.

4. And when the temperature of the reaction kettle reaches 75 ℃, adding 5% of initiator solution and 5% of prepared pre-emulsion, and after the appearance turns blue, preserving the heat for 0.5h to prepare seed emulsion.

5. And simultaneously dropwise adding the rest 95% of pre-emulsion and the rest 95% of initiator solution into the reaction kettle, wherein the dropwise adding temperature is controlled at 75 ℃, and the dropwise adding time is controlled at 4 h.

6. After the dropwise addition, 3 parts of vinyltrimethoxysilane is added, the dropwise addition time is controlled for 1 hour, and the temperature is kept for 1 hour.

7. Cooling to below 50 ℃, adding 0.025 part of initiator tert-butyl hydroperoxide and 0.025 part of sodium bisulfite, and continuing to react for 2 hours.

8. And continuously cooling to below 30 ℃, adding 10 parts of ammonia water, and discharging.

Example 2

1. 50 parts of deionized water, 0.5 part of allyloxy nonyl phenoxy propanol polyoxyethylene ether ammonium sulfate and 0.01 part of sodium bicarbonate are added to the bottom of the reaction kettle, the temperature is raised to 80 ℃, and the temperature is kept constant.

2. 30 parts of deionized water, 0.25 part of allyloxy nonylphenoxypropanol polyoxyethylene ether ammonium sulfate, 0.25 part of allyloxy nonylphenoxypropanol polyoxyethylene ether and 0.09 part of ammonium bicarbonate are added into a dropping kettle, 5 parts of styrene, 5 parts of methacrylic acid, 10 parts of methyl acrylate, 10 parts of ethyl acrylate, 10 parts of n-butyl acrylate, 45 parts of n-butyl methacrylate, 5 parts of acrylamide, 5 parts of methacrylamide, 5 parts of diacetone acrylamide and 3 parts of acetoacetoxy ethyl methacrylate are added under high-speed stirring at 2000rpm, and the mixture is stirred at 2000rpm for 1 hour to prepare a pre-emulsion.

3. And (3) adding 10 parts of deionized water and 1 part of potassium persulfate into the initiator dropping kettle, and uniformly stirring and mixing to prepare an initiator solution.

4. And when the temperature of the reaction kettle reaches 80 ℃, adding 60% of initiator solution and 20% of prepared pre-emulsion, and after the appearance turns blue, preserving the heat for 2 hours to prepare seed emulsion.

5. And simultaneously dropwise adding the rest 80% of pre-emulsion and the rest 40% of initiator solution into the reaction kettle, controlling the dropwise adding temperature at 80 ℃ and controlling the dropwise adding time at 3 h.

6. After the dropwise addition, 0.1 part of vinyltriethoxysilane is added, the dropwise addition time is controlled for 2 hours, and the temperature is kept for 2 hours.

7. Cooling to below 50 ℃, adding 0.5 part of tert-butyl hydroperoxide and 0.5 part of sodium bisulfite, and continuing to react for 2 hours. 8. And continuously cooling to below 30 ℃, adding 5 parts of ammonia water, and discharging.

Example 3

1. 45 parts of deionized water, 2 parts of 1-allyloxy-3- (4-nonylphenol) -2-propanol polyoxyethylene (10) ether monophosphate and 1 part of disodium hydrogen phosphate are added to the bottom of the reaction kettle, the temperature is raised to 85 ℃, and the temperature is kept constant.

2. 50 parts of deionized water, 8 parts of allyloxy nonyl phenoxy propanol polyoxyethylene ether ammonium sulfate and 2 parts of dipotassium phosphate are added into a dropping kettle, 1 part of styrene, 1 part of acrylic acid, 5 parts of ethyl acrylate, 49 parts of n-butyl methacrylate, 10 parts of acrylic acid-2-ethylhexyl ester, 5 parts of isooctyl methacrylate, 0.1 part of methacrylamide and 10 parts of acetoacetoxy ethyl methacrylate are added into the dropping kettle under the high-speed stirring of 3000rpm, and the pre-emulsion is prepared after the monomer mixture is stirred at 3000rpm for 1 hour.

3. 5 parts of deionized water and 1 part of sodium persulfate are added into an initiator dropping kettle and stirred and mixed uniformly to prepare an initiator solution.

4. And (3) when the temperature of the reaction kettle reaches 85 ℃, adding 5% of initiator solution and 20% of prepared pre-emulsion, and preserving heat for 3 hours after the appearance turns blue to prepare seed emulsion.

5. And simultaneously dripping the rest 80% of pre-emulsion and the rest 95% of initiator solution into the reaction kettle, wherein the dripping temperature is controlled at 85 ℃, and the dripping time is controlled at 4 h.

6. After the dropwise addition, 3 parts of vinyl tri (beta-methoxyethoxy) silane and 2 parts of methacryloxypropyl trimethoxy silane are added, the dropwise addition time is controlled for 4 hours, and the temperature is kept for 2 hours.

7. And cooling to below 50 ℃, adding 1 part of initiator tert-butyl hydroperoxide and 1 part of sodium bisulfite, and continuing to react for 2 hours. 8. And continuously cooling to below 30 ℃, adding 0.1 part of ammonia water, and discharging.

Example 4

1. adding 40 parts of deionized water, 1.5 parts of allyloxy nonyl phenoxy propanol polyoxyethylene ether ammonium sulfate and 0.5 part of sodium bicarbonate into the bottom of a reaction kettle, heating to 80 ℃, and keeping the temperature constant.

2. 30 parts of deionized water, 1 part of allyloxy nonylphenoxypropanol polyoxyethylene ether ammonium sulfate, 0.5 part of 1-allyloxy-3- (4-nonylphenol) -2-propanol polyoxyethylene (10) ether monophosphate and 0.5 part of ammonium bicarbonate are added into a dropping kettle, 5 parts of methyl styrene, 1 part of acrylic acid, 5 parts of methyl acrylate, 20 parts of tert-butyl acrylate, 10 parts of methyl methacrylate, 24 parts of n-butyl methacrylate, 3 parts of acrylamide and 5 parts of acetoacetoxy ethyl methacrylate are added under high-speed stirring at 1500rpm, and the mixture is stirred at 1500rpm for 0.5h to prepare a pre-emulsion.

3. And (3) adding 10 parts of deionized water and 0.8 part of ammonium persulfate into the initiator dropping kettle, and stirring and mixing uniformly to prepare an initiator solution.

4. And when the temperature of the reaction kettle reaches 80 ℃, adding 50% of initiator solution and 10% of prepared pre-emulsion, and after the appearance turns blue, preserving the heat for 3 hours to prepare seed emulsion.

5. And simultaneously dripping the rest 90% of pre-emulsion and the rest 50% of initiator solution into the reaction kettle, wherein the dripping temperature is controlled at 80 ℃, and the dripping time is controlled at 3 h.

6. After the dropwise addition, 1 part of vinyltrimethoxysilane is added, the dropwise addition time is controlled for 4 hours, and the temperature is kept for 2 hours.

7. Cooling to below 50 ℃, adding 0.1 part of initiator tert-butyl hydroperoxide and 0.1 part of sodium bisulfite, and continuing to react for 2 hours.

8. And continuously cooling to below 30 ℃, adding 1 part of ammonia water, and discharging.

Example 5

1. adding 40 parts of deionized water, 2 parts of allyloxy nonyl phenoxy propanol polyoxyethylene ether ammonium sulfate and 1 part of sodium bicarbonate into the bottom of a reaction kettle, heating to 85 ℃, and keeping the temperature constant.

2. 40 parts of deionized water, 3 parts of allyloxy nonyl phenoxy propanol polyoxyethylene ether ammonium sulfate and 1 part of sodium carbonate are added into a dropping kettle, 2 parts of methyl styrene, 2 parts of acrylic acid, 5 parts of ethyl acrylate, 12 parts of n-butyl acrylate, 35 parts of acrylic acid-2-ethylhexyl ester, 6 parts of methacrylic acid, 10 parts of n-butyl methacrylate, 5 parts of isooctyl methacrylate, 5 parts of acrylamide and 8 parts of diacetone acrylamide are added into the dropping kettle under the high-speed stirring of 1000rpm, and the pre-emulsion is prepared after the monomer mixture of the acrylic acid, the ethyl acrylate, the n-butyl acrylate, the acrylic acid-2-ethylhexyl acrylate, the methacrylic acid, the.

3. And (3) adding 10 parts of deionized water and 1 part of initiator into the initiator dropping kettle, and uniformly stirring and mixing to prepare an initiator solution.

4. And when the temperature of the reaction kettle reaches 85 ℃, adding 30% of initiator solution and 10% of prepared pre-emulsion, and after the appearance turns blue, preserving the heat for 1h to prepare seed emulsion.

5. And simultaneously dripping the rest 90% of pre-emulsion and the rest 70% of initiator solution into the reaction kettle, wherein the dripping temperature is controlled at 85 ℃, and the dripping time is controlled at 1 h.

6. After the dropwise addition, 0.5 part of vinyltriethoxysilane, 0.5 part of vinyltris (beta-methoxyethoxy) silane and 1 part of methacryloxypropyltrimethoxysilane are added, the dropwise addition time is controlled for 4 hours, and the temperature is kept for 1 hour.

7. And cooling to below 50 ℃, adding 1 part of initiator tert-butyl hydroperoxide and 1 part of sodium bisulfite, and continuing to react for 2 hours.

8. And continuously cooling to below 30 ℃, adding 8 parts of ammonia water, and discharging.

TABLE 1

Comparative examples 1 to 4

Comparative examples 1 to 4 provide an emulsion for PVDC composite membrane priming and a preparation method thereof, the components and the contents are shown in Table 1, the preparation method of comparative examples 1 to 3 is the same as that of example 1, and the preparation method of comparative example 4 is the same as that of example 2.

Comparative example 5

The comparative example provides an emulsion for priming PVDC composite membrane and a preparation method thereof, and the components and the content are basically the same as those of the emulsion in the example 1, except that: the emulsifier used in this comparative example was sodium dodecyl diphenyl oxide disulfonate. The preparation method is the same as in example 1.

Effect verification:

the PVDC composite film primer emulsion prepared in the above examples and comparative examples is subjected to performance test, and the test method comprises the following steps:

1. leveling property: and coating the prepared emulsion on an OPP film to form a film, coating the PVDC emulsion, and observing the leveling condition of the PVDC emulsion on the prepared emulsion film. Whether the coating is uniform or not and whether the coating has coating defects such as shrinkage holes, fish eyes, pinholes and the like or not. And scoring the mixture according to the leveling result for 0-10 minutes, wherein the effect is best 10 minutes and worst 0 minute, and the requirement can be met only when the average reaches at least 9-10 minutes.

2. Adhesion force: the prepared emulsion was coated on an OPP film to form a film, then a PVDC emulsion was coated, the film was adhered to the PVDC-coated film with a 3M adhesive tape, the adhesive tape was pulled away from the film, and the adhesion of PVDC to the OPP was observed, and the PVDC film was either completely or partially peeled off. The PVDC coating is scored for 0-10 minutes according to the condition of the area of the PVDC coating remained on the OPP film, the PVDC coating can not be peeled off at all, the effect of the PVDC coating completely remained on the OPP film is preferably 10 minutes, the PVDC coating completely peeled off, the effect of the PVDC coating not remaining on the OPP film is 0 minute at worst, and the requirement of at least reaching more than 9-10 minutes can meet the requirement.

The test results are shown in table 2.

TABLE 2

	Leveling property	Adhesion force
			Example 1	10	10
Example 2	10	9
			Example 3	10	9
Example 4	9	10
			Example 5	9	10
Comparative example 1	5	3
			Comparative example 2	3	4
Comparative example 3	2	3
			Comparative example 4	5	3
Comparative example 5	6	5

The invention has many applications, and the above description is only a preferred embodiment of the invention. It should be noted that the above examples are only for illustrating the present invention, and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that various modifications can be made without departing from the principles of the invention and these modifications are to be considered within the scope of the invention.

Claims

1. The emulsion for the PVDC composite film prime coat is characterized by comprising the following components in parts by weight:

the styrene monomer is at least one of styrene and methyl styrene;

the (methyl) acrylamide monomer is at least one of acrylamide and methacrylamide;

the emulsifier is an emulsifier containing polymerizable double bonds and is at least one selected from allyloxy nonylphenoxy propanol polyoxyethylene ether ammonium sulfate, allyloxy nonylphenoxy propanol polyoxyethylene ether and 1-allyloxy-3- (4-nonylphenol) -2-propanol polyoxyethylene (10) ether monophosphoric acid.

2. The emulsion for priming the PVDC composite film according to claim 1, wherein the (meth) acrylic acid and the ester monomer thereof are at least one of acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, methacrylic acid, methyl methacrylate, n-butyl methacrylate and isooctyl methacrylate.

3. The emulsion for priming the PVDC composite membrane according to claim 1, wherein the functional monomer is at least one of diacetone acrylamide and acetoacetoxyethyl methacrylate.

4. The emulsion for priming a PVDC composite film according to claim 1, wherein the organosilicon monomer is at least one of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (beta-methoxyethoxy) silane and methacryloxypropyltrimethoxysilane.

5. The emulsion for priming the PVDC composite membrane according to claim 1, wherein the initiator is at least one of sodium persulfate, ammonium persulfate, potassium persulfate, tert-butyl hydroperoxide and sodium bisulfite.

6. The emulsion for priming the PVDC composite membrane according to claim 1, wherein the pH buffer is at least one of ammonium bicarbonate, sodium carbonate, disodium hydrogen phosphate and dipotassium hydrogen phosphate; the neutralizer is ammonia water; the water is deionized water.

7. A method for synthesizing emulsion for priming PVDC composite membrane according to any one of claims 1 to 6, which comprises the following steps:

E. simultaneously dripping the rest pre-emulsion and the rest initiator solution into the seed emulsion, adding the organosilicon monomer into the reaction kettle after dripping the pre-emulsion and the initiator solution, and preserving heat;

G. and F, continuously cooling to below 30 ℃ after the reaction in the step F, adding a neutralizing agent to adjust the pH value of the emulsion to 6-9, and discharging to obtain the emulsion for the PVDC composite membrane base coat.

8. The method for synthesizing emulsion for priming PVDC composite membrane according to claim 7, wherein in step B, the stirring speed adopted by the high-speed stirring is 1000-3000rpm, and the stirring time after the addition is 0.5-2 h;

in the step F, the reaction time is 1-2 h.