Interpenetrating network type PVDC emulsion and preparation method therefor

Abstract

Disclosed in the present invention are an interpenetrating network type PVDC emulsion and a preparation method therefor. The PVDC emulsion is prepared from the following components in parts by weight: 650-850 parts of vinylidene chloride monomer, 20-60 parts of styrene, 2-6 parts of an organosilicon monomer, 25-55 parts of an acrylic acid phosphate monomer, 3-5.5 parts of a cross-linking type monomer, 10-25 parts of a hydrophilic monomer, 100-150 parts of a comonomer, 10-30 parts of an emulsifier, 0.5-1.5 parts of an initiator and 550-750 parts of deionized water. The present invention has the advantages of simple process, good product stability, high barrier property, excellent adhesive force, good water resistance and the like.

Description

Interpenetrating network PVDC emulsion and preparation method thereof Technical Field

[0001] The present invention relates to the technical field of polymer materials, in particular to an interpenetrating network type PVDC emulsion and a preparation method thereof. Background Art

[0002] As a key structural material, steel plays a vital role in our daily lives. However, it is susceptible to corrosion from corrosive media such as oxygen, moisture, and salt spray, causing it to lose strength, leading to safety incidents and economic losses. According to statistics, global economic losses from steel corrosion reach as much as $250 million annually, making the development of simple and effective anti-corrosion technologies crucial. Polyvinylidene chloride (PVDC) possesses excellent structural symmetry, which results in high crystallinity. Combined with the strong polarity and hydrophobicity of the carbon-chlorine bond, PVDC offers excellent barrier properties to both water vapor and oxygen. Consequently, many industry experts are exploring its application in steel corrosion protection.

[0003] For example, CN108129926A discloses a barrier coating, its preparation method, and its application. The barrier coating comprises the following raw materials, measured by weight: 10-30 parts of styrene-butadiene emulsion, 60-80 parts of polyvinylidene chloride emulsion, 5-10 parts of ethylene-vinyl acetate copolymer, and 0.5-2 parts of an additive. This invention blends styrene-butadiene emulsion and ethylene-vinyl acetate copolymer into polyvinylidene chloride emulsion in appropriate proportions to form a cross-penetrating mixed system. The resulting barrier coating exhibits strong adhesion, good flexibility, and water vapor and oxygen barrier properties. The coating applied with this barrier coating exhibits excellent water and oxygen barrier properties. However, the invention simply combines several emulsions, resulting in poor compatibility. Furthermore, the strength and water resistance of the film need to be improved.

[0004] For example, CN105669890A discloses a polyvinylidene chloride emulsion for preparing a water-based metal anticorrosive coating and its preparation method, polyvinylidene chloride, acrylate monomer, hydroxyethyl methacrylate phosphate, N-hydroxymethyl acrylamide, emulsifier and deionized water are pre-emulsified, and under the action of an initiator, a seed emulsion polymerization method is adopted to polymerize a polyvinylidene chloride emulsion with good emulsion stability. By introducing a polar monomer, the adhesion of the emulsion to the substrate is increased, and the water-based anticorrosive coating prepared is based on water as the main dispersion medium, does not contain volatile organic solvents, is environmentally friendly and non-toxic, and is firmly bonded to the metal substrate. The disadvantage is that although the monomer of acrylate phosphate is introduced, the adhesion of the coating to the steel substrate is improved, but the water resistance and the strength of the film are poor.

[0005] Summary of the Invention

[0006] The present invention aims to overcome the existing technical defects and provide an interpenetrating network PVDC emulsion with good coating stability, high barrier performance, excellent adhesion and good water resistance and a preparation method thereof.

[0007] In order to achieve the above-mentioned purpose, one of the technical solutions adopted by the present invention is: an interpenetrating network PVDC emulsion is prepared from the following components in parts by weight:

[0008] As a preferred embodiment of the present invention, the organosilicon monomer is at least one of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(2-methoxyethoxy)silane, and methylvinyldichlorosilane.

[0009] As a preferred embodiment of the present invention, the acrylic acid phosphate monomer is at least one of 2-hydroxyethyl methacrylate phosphate, methacrylate phosphate, and 2-ethoxyethyl methacrylate phosphate.

[0010] As a preferred embodiment of the present invention, the hydrophilic monomer is at least one of acrylic acid and methacrylic acid.

[0011] As a preferred embodiment of the present invention, the cross-linking monomer is at least one of ethylene glycol diacrylate, divinylbenzene, methylene bisacrylamide, and diallyl maleate.

[0012] As a preferred embodiment of the present invention, the comonomer is at least two of acrylonitrile, methyl acrylate, butyl acrylate, ethyl acrylate, hydroxymethyl acrylate, hydroxyethyl acrylate, methyl methacrylate, ethyl methacrylate, and butyl methacrylate.

[0013] As a preferred embodiment of the present invention, the emulsifier is at least one of sodium dodecylbenzenesulfonate, sodium dodecylsulfonate, sodium pentadecyl sulfate, and sodium dodecyl sulfate.

[0014] As a preferred embodiment of the present invention, the initiator is a mixture of tert-butyl hydroperoxide and Rongalite.

[0015] The interpenetrating network PVDC emulsion of the present invention, by optimizing the feed formula and introducing a crosslinking monomer, forms a network of interpenetrating molecular chains in the shell and core layers. This results in an interpenetrating network PVDC emulsion with good stability, high barrier properties, excellent adhesion and water resistance, and good flexibility. The interpenetrating network PVDC emulsion of the present invention is particularly suitable for the field of steel corrosion protection.

[0016] In the present invention, a cross-linking monomer containing two double bonds reacts with seed monomers such as styrene, organosilicon monomer, vinylidene chloride monomer, acrylic acid phosphate monomer, comonomer, and hydrophilic monomer in the seed emulsion polymerization stage. The cross-linking monomer consumes one double bond and has one double bond left, thereby forming a molecular chain containing one double bond and having reactive activity in the seed emulsion polymerization stage. In the feed polymerization stage, the monomers polymerized in the feed polymerization have a swelling effect on the latex particles formed in the previous seed emulsion polymerization stage (polymerization and swelling are carried out simultaneously). The molecular chains containing reactive activity in the latex particles formed in the seed emulsion polymerization stage react with the feed monomers such as vinylidene chloride monomer, acrylic acid phosphate monomer, cross-linking monomer, comonomer, and hydrophilic monomer in the feed polymerization stage, thereby forming new molecular chains with reactive activity on the original molecular chains. This process is repeated, and combined with the swelling effect of the feed monomers on the seed, an interpenetrating network structure is finally formed with vinylidene chloride, styrene, organosilicon monomer, acrylic acid phosphate monomer, etc. as a shell layer and vinylidene chloride, comonomer, and acrylic acid phosphate monomer, etc. as a core layer.

[0017] Compared with the existing technology, the present invention has the following advantages:

[0018] 1. The latex particles of the interpenetrating network PVDC emulsion of the present invention have an interpenetrating network structure, and have an interpenetrating network structure with vinylidene chloride, styrene, silicone monomer, acrylic acid phosphate monomer, etc. as a shell layer, and vinylidene chloride, comonomer and acrylic acid phosphate monomer, etc. as a core layer. The network interpenetrating structure between the two molecular chains significantly improves the water resistance and strength of the coating. The steel anti-corrosion coating prepared using the PVDC emulsion of the present invention has a 3.5% salt water resistance of more than 140 hours and a pencil hardness of more than 1H.

[0019] 2. The prepared PVDC emulsion has good stability. The introduction of hydrophilic monomers such as acrylic acid and methacrylic acid makes the latex particles easily dispersed in water and not easily sedimented and demulsified, thereby losing application performance. The PVDC emulsion of the present invention can be stored at room temperature for more than 8.5 months.

[0020] 3. The obtained coating has strong adhesion. The acrylic acid phosphate monomers and acrylic acid monomers introduced into the PVDC emulsion of the present invention can react with substrates such as steel to improve the adhesion of the coating to substrates such as steel. The obtained coating has an adhesion of above level 0.

[0021] 4. The obtained coating has good anti-rust effect. The present invention introduces acrylic phosphate monomers into the PVDC emulsion. During the film-forming process, the phosphate functional groups can form a dense phosphate protective film with the steel substrate, passivating the steel substrate and achieving a good anti-rust effect.

[0022] 5. The obtained coating has excellent barrier properties. The interpenetrating network PVDC emulsion of the present invention reduces the mobility of the molecular chain by cross-linking, making it more difficult for water vapor and oxygen to migrate in the coating, thereby better protecting the steel substrate. The oxygen permeability of the obtained coating is 35cm 3 / m 2 ·Days below, water vapor transmission rate is 11g / m 2 Less than one day.

[0023] The second technical solution adopted by the present invention is: the preparation method of the above-mentioned interpenetrating network type PVDC emulsion comprises the following steps:

[0024] (1) Prepare reaction raw materials

[0025] By weight, the reaction raw materials are composed of:

[0026] (2) preparing an emulsifier aqueous solution: preparing an emulsifier aqueous solution by mixing the emulsifier with 30-35% deionized water;

[0027] (3) preparing a polymerization initiator aqueous solution: preparing a polymerization initiator aqueous solution by mixing 50% of the initiator with 5.5-6.5% of deionized water;

[0028] (4) preparing an aqueous solution of residual initiator: preparing an aqueous solution of residual initiator by mixing the remaining initiator with 4-5% deionized water;

[0029] (5) Seed emulsion polymerization: adding the remaining deionized water, styrene, silicone monomer, 1-3% of vinylidene chloride monomer, 4-12% of acrylic acid phosphate monomer, 4.5-10.5% of cross-linking monomer, 2-12% of comonomer, 20-40% of hydrophilic monomer, 5-10% of emulsifier aqueous solution to a polymerization kettle, cold dispersing at a stirring speed of 80-150 rpm for 15-35 minutes, heating to 45-75° C., adding 5-10% of polymerization initiator aqueous solution to react for 0.5-2.5 hours to obtain a seed emulsion;

[0030] (6) Addition polymerization: adding the remaining vinylidene chloride monomer, the remaining acrylic acid phosphate monomer, the remaining cross-linking monomer, the remaining comonomer, the remaining hydrophilic monomer, the remaining emulsifier aqueous solution, and the remaining polymerization initiator aqueous solution to the above seed emulsion at a temperature of 45 to 75° C. and a stirring speed of 80 to 150 rpm to react for 12 to 15 hours to obtain a reaction product;

[0031] (7) Emulsion residue elimination: adding an aqueous solution of a residue elimination initiator to the reaction product obtained in step (6) at a temperature of 45 to 75° C. and a stirring speed of 80 to 150 rpm to carry out a reaction for 0.5 to 1.5 h, cooling, filtering, and obtaining the product.

[0032] The preparation method of the present invention first performs seed polymerization with seed monomers such as styrene, silicone monomers, and cross-linking monomers to synthesize seeds with reactive molecular chains, and then swells added monomers such as VDC, acrylate monomers, and cross-linking monomers and then performs addition polymerization to form a shell layer and a core layer. The network interpenetrating structure between the two molecular chains significantly improves the water resistance and strength of the coating.

[0033] Preferably, the polymerization kettle is vacuumed before the seed emulsion polymerization.

[0034] Preferably, the mesh size of the filtration in step (7) is 250 to 450 meshes.

[0035] The preparation method of the interpenetrating network PVDC emulsion of the present invention optimizes the polymerization method by optimizing the feeding formula and optimizing factors affecting the polymerization reaction, such as the polymerization process, reaction temperature and time, stirring speed, and feeding method. DETAILED DESCRIPTION

[0036] The present invention is further described in detail below with reference to the following examples, but the present invention is not limited to the following examples.

[0037] Example 1

[0038] A method for preparing an interpenetrating network PVDC emulsion comprises the following steps:

[0039] (1) Prepare reaction raw materials

[0040] The raw material formula is as follows:

[0041] (2) Preparation of emulsifier aqueous solution: Weigh 20 kg of sodium lauryl sulfate and add 200 kg of deionized water to prepare a sodium lauryl sulfate aqueous solution for later use;

[0042] (3) Preparation of polymerization initiator aqueous solution: Weigh 85 g of TBHP and add 20 kg of deionized water to prepare a TBHP aqueous solution, which is set aside; weigh 85 g of SFS and add 20 kg of deionized water to prepare an SFS aqueous solution, which is set aside;

[0043] (4) Preparation of aqueous solution of residual initiator: Weigh 400 g of TBHP and mix it with 10 kg of deionized water to prepare a TBHP aqueous solution, set aside; weigh 400 g of SFS and mix it with 20 kg of deionized water to prepare a SFS aqueous solution, set aside;

[0044] (5) Seed emulsion polymerization: first, the remaining deionized water was added to the polymerization kettle, and the polymerization kettle was evacuated to -0.095 MPa. While maintaining the vacuum degree, 10 kg of vinylidene chloride, 27.5 kg of styrene, 2.5 kg of vinyltrimethoxysilane, 2.5 kg of 2-methacrylate ethoxyethyl phosphate, 4.85 kg of methyl acrylate, 175 g of divinylbenzene, 2.5 kg of methacrylic acid and 5% of the sodium lauryl sulfate aqueous solution prepared in step (2) were pumped into the polymerization kettle, and the mixture was cold dispersed at a stirring speed of 90 rpm for 30 minutes. The mixture was heated to 55° C. while maintaining the speed. Then, 5% of the TBHP aqueous solution prepared in step (3) and 5% of the SFS aqueous solution prepared in step (3) were uniformly added within 13 hours to react for 1 hour to obtain a seed emulsion;

[0045] (6) Feed polymerization: maintaining the polymerization kettle temperature at 55° C. and the stirring speed at 90 rpm, adding the remaining sodium lauryl sulfate aqueous solution, the remaining vinylidene chloride, 47.5 kg of butyl acrylate, the remaining methyl acrylate, 9.5 kg of acrylic acid, the remaining 2-methacrylic acid ethoxyethyl phosphate, the remaining divinylbenzene, the remaining TBHP aqueous solution prepared in step (3), and the SFS aqueous solution to the seed emulsion obtained in step (5) to carry out reaction, and terminate the reaction after 13 hours to obtain a reaction product;

[0046] (7) Emulsion residue removal: The TBHP aqueous solution and the SFS aqueous solution prepared in step (4) were uniformly added to the polymerization kettle over 20 minutes while maintaining the polymerization kettle temperature at 55°C and the stirring speed at 90 rpm. After the addition, the mixture was kept warm for 0.5 h, cooled to 20°C, and filtered through a 300-mesh filter to obtain the product. The properties are shown in Table 1.

[0047] Example 2

[0048] A method for preparing an interpenetrating network PVDC emulsion comprises the following steps:

[0049] (1) Prepare reaction raw materials

[0050] The raw material formula is as follows:

[0051] (2) Preparation of emulsifier aqueous solution: Weigh 22 kg of sodium pentadecyl sulfate and add 200 kg of deionized water to prepare a sodium pentadecyl sulfate aqueous solution for later use;

[0052] (3) Preparation of polymerization initiator aqueous solution: Weigh 90 g of TBHP and add 20 kg of deionized water to prepare a TBHP aqueous solution, which is set aside; weigh 90 g of SFS and add 20 kg of deionized water to prepare an SFS aqueous solution, which is set aside;

[0053] (4) Preparation of aqueous solution of residual initiator: Weigh 420 g of TBHP and mix it with 10 kg of deionized water to prepare a TBHP aqueous solution, set aside; weigh 420 g of SFS and mix it with 20 kg of deionized water to prepare a SFS aqueous solution, set aside;

[0054] (5) Seed emulsion polymerization: first, the remaining deionized water was added to the polymerization kettle, and the polymerization kettle was evacuated to -0.095 MPa. While maintaining the vacuum degree, 10.8 kg of vinylidene chloride, 36.6 kg of styrene, 3.6 kg of vinyl triethoxysilane, 2.4 kg of methyl methacrylate phosphate, 2.76 kg of butyl acrylate, 240 g of ethylene glycol diacrylate, 3.6 kg of acrylic acid and 6% of the sodium pentadecyl sulfate aqueous solution prepared in step (2) were pumped into the polymerization kettle, and the mixture was cold dispersed at a stirring speed of 100 rpm for 20 minutes. The mixture was heated to 50° C. while maintaining the speed. Then, 6% of the TBHP aqueous solution prepared in step (3) and 6% of the SFS aqueous solution prepared in step (3) were uniformly added within 13 hours to react for 1.2 hours to obtain a seed emulsion;

[0055] (6) Feed polymerization: maintaining the polymerization kettle temperature at 50° C. and the stirring speed at 100 rpm, adding the remaining sodium pentadecyl sulfate aqueous solution, the remaining vinylidene chloride, the remaining butyl acrylate, 62.04 kg of methyl acrylate, 9.4 kg of methacrylic acid, the remaining methacrylic acid phosphate, the remaining ethylene glycol diacrylate, the remaining TBHP aqueous solution prepared in step (3), and the SFS aqueous solution to the seed emulsion obtained in step (5) to carry out reaction, and the reaction was terminated after 12.5 hours to obtain a reaction product;

[0056] (7) Emulsion residue removal: The TBHP aqueous solution and the SFS aqueous solution prepared in step (4) were uniformly added to the polymerization kettle at a speed of 100 rpm while maintaining the polymerization kettle temperature at 50°C. After the addition, the mixture was kept warm for 1 hour, cooled to 30°C, and filtered through a 350-mesh filter to obtain the product. The properties are shown in Table 1.

[0057] Example 3

[0058] A method for preparing an interpenetrating network PVDC emulsion comprises the following steps:

[0059] (1) Prepare reaction raw materials

[0060] (2) Preparation of emulsifier aqueous solution: Weigh 24 kg of sodium dodecyl sulfate and add 200 kg of deionized water to prepare a sodium dodecyl sulfate aqueous solution for later use;

[0061] (3) Preparation of polymerization initiator aqueous solution: Weigh 100 g of TBHP and add 20 kg of deionized water to prepare a TBHP aqueous solution, which is set aside; weigh 100 g of SFS and add 20 kg of deionized water to prepare an SFS aqueous solution, which is set aside;

[0062] (4) Preparation of aqueous solution of residual initiator: Weigh 430 g of TBHP and prepare a TBHP aqueous solution with 10 kg of deionized water, and set aside; weigh 430 g of SFS and prepare a SFS aqueous solution with 20 kg of deionized water, and set aside;

[0063] (5) Seed emulsion polymerization: first, the remaining deionized water was added to the polymerization kettle, and the polymerization kettle was evacuated to -0.095 MPa. While maintaining the vacuum degree, 11.64 kg of vinylidene chloride, 53.6 kg of styrene, 3.2 kg of vinyl triethoxysilane, 2.4 kg of 2-hydroxyethyl methacrylate phosphate, 4 kg of butyl acrylate, 360 g of methylene bisacrylamide, 4.8 kg of acrylic acid and 8% of the sodium dodecylsulfonate aqueous solution prepared in step (2) were pumped into the polymerization kettle, and the mixture was cold dispersed at a stirring speed of 110 rpm for 25 minutes. The mixture was heated to 60° C. while maintaining the speed. Then, 8% of the TBHP aqueous solution prepared in step (3) and 8% of the SFS aqueous solution prepared in step (3) were uniformly added within 13 hours to react for 1.5 hours to obtain a seed emulsion;

[0064] (6) Feed polymerization: maintaining the polymerization kettle temperature at 60° C. and the stirring speed at 110 rpm, adding the remaining sodium dodecylsulfonate aqueous solution, the remaining vinylidene chloride, the remaining butyl acrylate, 50.6 kg of methyl acrylate, the remaining acrylic acid, the remaining methacrylic acid-2-hydroxyethyl phosphate, the remaining methylenebisacrylamide, the remaining TBHP aqueous solution prepared in step (3), and the SFS aqueous solution to the seed emulsion obtained in step (5) to carry out reaction, and the reaction was terminated after 13 hours to obtain a reaction product;

[0065] (7) Emulsion residue removal: The TBHP aqueous solution and the SFS aqueous solution prepared in step (4) were uniformly added to the polymerization kettle over 25 minutes while maintaining the polymerization kettle temperature at 60°C and the stirring speed at 110 rpm. After the addition, the mixture was kept warm for 0.75 h, cooled to 25°C, and filtered through a 400-mesh filter to obtain the product. The properties are shown in Table 1.

[0066] Example 4

[0067] A method for preparing an interpenetrating network PVDC emulsion comprises the following steps:

[0068] (1) Prepare reaction raw materials

[0069] The raw material formula is as follows:

[0070] (2) Preparation of emulsifier aqueous solution: weigh 25 kg of sodium dodecylbenzene sulfonate and add 200 kg of deionized water to prepare sodium dodecylbenzene sulfonate aqueous solution for later use;

[0071] (3) Preparation of polymerization initiator aqueous solution: Weigh 120 g of TBHP and add 20 kg of deionized water to prepare a TBHP aqueous solution, which will be set aside; weigh 120 g of SFS and add 20 kg of deionized water to prepare an SFS aqueous solution, which will be set aside;

[0072] (4) Preparation of aqueous solution of residual initiator: Weigh 450 g of TBHP and prepare a TBHP aqueous solution with 10 kg of deionized water, and set aside; weigh 450 g of SFS and prepare a SFS aqueous solution with 20 kg of deionized water, and set aside;

[0073] (5) Seed emulsion polymerization: first, the remaining deionized water was added to the polymerization kettle, and the polymerization kettle was evacuated to -0.095 MPa. While maintaining the vacuum degree, 21 kg of vinylidene chloride, 55 kg of styrene, 5 kg of vinyltrimethoxysilane, 4 kg of 2-hydroxyethyl methacrylate phosphate, 9.5 kg of butyl acrylate, 500 g of methylenebisacrylamide, 5 kg of acrylic acid and 10% of the sodium dodecylbenzenesulfonate aqueous solution prepared in step (2) were pumped into the polymerization kettle, and the mixture was cold dispersed at a stirring speed of 120 rpm for 25 minutes. The mixture was heated to 70° C. while maintaining the speed. Then, 10% of the TBHP aqueous solution prepared in step (3) and 10% of the SFS aqueous solution prepared in step (3) were uniformly added within 13 hours to react for 2 hours to obtain a seed emulsion;

[0074] (6) Feed polymerization: maintaining the polymerization kettle temperature at 70° C. and the stirring speed at 120 rpm, adding the remaining sodium dodecylbenzenesulfonate aqueous solution, the remaining vinylidene chloride, the remaining butyl acrylate, 9 kg of methyl acrylate, the remaining acrylic acid, the remaining methacrylic acid-2-hydroxyethyl phosphate, the remaining methylenebisacrylamide, the remaining TBHP aqueous solution prepared in step (3), and the SFS aqueous solution to the seed emulsion obtained in step (5) to carry out reaction, and terminate the reaction after 14 hours to obtain a reaction product;

[0075] (7) Emulsion residue removal: The TBHP aqueous solution and the SFS aqueous solution prepared in step (4) were uniformly added to the polymerization kettle over 30 minutes while maintaining the polymerization kettle temperature at 70°C and the stirring speed at 120 rpm. After the addition, the mixture was kept warm for 1 hour, cooled to 25°C, and filtered through a 450-mesh filter to obtain the product. The properties are shown in Table 1.

[0076] Example 5

[0077] A method for preparing an interpenetrating network PVDC emulsion comprises the following steps:

[0078] (1) Prepare reaction raw materials

[0079] The raw material formula is as follows:

[0080] (2) Preparation of emulsifier aqueous solution: Weigh 22 kg of sodium pentadecyl sulfate and add 200 kg of deionized water to prepare a sodium pentadecyl sulfate aqueous solution for later use;

[0081] (3) Preparation of polymerization initiator aqueous solution: Weigh 90 g of TBHP and add 20 kg of deionized water to prepare a TBHP aqueous solution, which is set aside; weigh 90 g of SFS and add 20 kg of deionized water to prepare an SFS aqueous solution, which is set aside;

[0082] (4) Preparation of aqueous solution of residual initiator: Weigh 420 g of TBHP and mix it with 10 kg of deionized water to prepare a TBHP aqueous solution, set aside; weigh 420 g of SFS and mix it with 20 kg of deionized water to prepare a SFS aqueous solution, set aside;

[0083] (5) Seed emulsion polymerization: first, add the remaining deionized water into the polymerization kettle, evacuate the polymerization kettle to -0.095 MPa, and while maintaining the vacuum, use a pump to pump 12.6 kg of vinylidene chloride, 42.7 kg of styrene, 4.2 kg of vinyl triethoxysilane, 3.22 kg of butyl acrylate, 2.8 kg of 2-hydroxyethyl methacrylate phosphate, 4.2 kg of acrylic acid, 280 g of ethylene glycol diacrylate and 7% of the sodium pentadecyl sulfate aqueous solution prepared in step (2) into the polymerization kettle, and cold disperse at a stirring speed of 100 rpm for 20 minutes, maintain the speed and heat to 50° C., and then uniformly add 7% of the TBHP aqueous solution prepared in step (3) and 7% of the SFS aqueous solution prepared in step (3) within 13 hours to react for 1.2 hours to obtain a seed emulsion;

[0084] (6) Feed polymerization: maintaining the polymerization kettle temperature at 50° C. and the stirring speed at 100 rpm, adding the remaining sodium lauryl sulfate aqueous solution, the remaining vinylidene chloride, the remaining butyl acrylate, 65.8 kg of methyl acrylate, 9.4 kg of methacrylic acid, the remaining 2-hydroxyethyl methacrylate phosphate, the remaining ethylene glycol diacrylate, the remaining TBHP aqueous solution prepared in step (3), and the SFS aqueous solution to the seed emulsion obtained in step (5) to carry out reaction, and the reaction was terminated after 12.5 hours to obtain a reaction product;

[0085] (7) Emulsion residue removal: The TBHP aqueous solution and the SFS aqueous solution prepared in step (4) were uniformly added to the polymerization kettle at a speed of 100 rpm while maintaining the polymerization kettle temperature at 50°C. After the addition, the mixture was kept warm for 1 hour, cooled to 30°C, and filtered through a 350-mesh filter to obtain the product. The properties are shown in Table 1.

[0086] Example 6

[0087] A method for preparing an interpenetrating network PVDC emulsion comprises the following steps:

[0088] (1) Prepare reaction raw materials

[0089] The raw material formula is as follows:

[0090] (2) Preparation of emulsifier aqueous solution: Weigh 22 kg of sodium pentadecyl sulfate and add 200 kg of deionized water to prepare a sodium pentadecyl sulfate aqueous solution for later use;

[0091] (3) Preparation of polymerization initiator aqueous solution: Weigh 90 g of TBHP and add 20 kg of deionized water to prepare a TBHP aqueous solution, which is set aside; weigh 90 g of SFS and add 20 kg of deionized water to prepare an SFS aqueous solution, which is set aside;

[0092] (4) Preparation of aqueous solution of residual initiator: Weigh 420 g of TBHP and mix it with 10 kg of deionized water to prepare a TBHP aqueous solution, set aside; weigh 420 g of SFS and mix it with 20 kg of deionized water to prepare a SFS aqueous solution, set aside;

[0093] (5) Seed emulsion polymerization: first, the remaining deionized water was added to the polymerization kettle, and the polymerization kettle was evacuated to -0.095 MPa. While maintaining the vacuum degree, 16.2 kg of vinylidene chloride, 54.9 kg of styrene, 5.4 kg of vinyl triethoxysilane, 5.4 kg of acrylic acid, 3.6 kg of 2-hydroxyethyl methacrylate phosphate, 4.14 kg of butyl acrylate, 360 g of ethylene glycol diacrylate and 9% of the sodium pentadecyl sulfate aqueous solution prepared in step (2) were pumped into the polymerization kettle, and the mixture was cold dispersed at a stirring speed of 100 rpm for 20 minutes. The mixture was heated to 50° C. while maintaining the speed. Then, 9% of the TBHP aqueous solution prepared in step (3) and 9% of the SFS aqueous solution prepared in step (3) were uniformly added within 13 hours to react for 1.2 hours to obtain a seed emulsion;

[0094] (6) Feed polymerization: maintaining the polymerization kettle temperature at 50° C. and the stirring speed at 100 rpm, adding the remaining sodium pentadecyl sulfate aqueous solution, the remaining vinylidene chloride, the remaining butyl acrylate, 60.06 kg of methyl acrylate, 9.1 kg of methacrylic acid, the remaining ethylene glycol diacrylate, the remaining 2-hydroxyethyl methacrylate phosphate, the remaining TBHP aqueous solution prepared in step (3), and the SFS aqueous solution to the seed emulsion obtained in step (5) to carry out the reaction, and terminate the reaction after 12.5 hours to obtain a reaction product;

[0095] (7) Emulsion residue removal: The TBHP aqueous solution and the SFS aqueous solution prepared in step (4) were uniformly added to the polymerization kettle at a speed of 100 rpm while maintaining the polymerization kettle temperature at 50°C. After the addition, the mixture was kept warm for 1 hour, cooled to 30°C, and filtered through a 350-mesh filter to obtain the product. The properties are shown in Table 1.

[0096] Comparative Example 1

[0097] The emulsion obtained in Comparative Example 1 was prepared according to the method described in Example 1 of CN105669890A, and the properties are shown in Table 1.

[0098] Performance Testing

[0099] The PVDC emulsions prepared in Examples 1-6 and Comparative Example 1 were used to prepare steel anticorrosion coatings. The preparation process was as follows: 100 parts of PVDC emulsion, 30 parts of general water-based color paste (medium yellow), 0.5 parts of multi-branched polysiloxane, 8 parts of dipropylene glycol butyl ether, 0.3 parts of pectin, 0.4 parts of silicone defoamer, 0.8 parts of sodium bicarbonate and an appropriate amount of deionized water were prepared into a steel anticorrosion coating with a solid content of 40%. The coating was applied by spraying with a nozzle diameter of 2 mm and a spraying pressure of 0.4 MPa to prepare a 30 μm wet film. The performance of the paint film was tested. The performance is shown in Table 2, where:

[0100] Adhesion test: according to the method specified in GB / T9286-1998 "Paints and varnishes, cross-cut test of paint films";

[0101] Salt water resistance test: carried out in accordance with the method specified in GB / T10834-2008 "Determination of salt water resistance of marine paints, salt water and hot salt water immersion method";

[0102] Flexibility test: Perform according to the method specified in GB / T1731-2020 "Determination of flexibility of paint film and putty film";

[0103] Pencil hardness test: Use the method specified in GB / T6739-2006 "Paints and varnishes - Pencil method for measuring film hardness";

[0104] Oxygen barrier performance test: carried out in accordance with the method specified in GB / T1038-2000 "Plastic film and sheeting gas permeability test method pressure difference method";

[0105] Water vapor barrier performance test: Perform according to the method specified in GB / T1037-1988 "Plastic film and sheet water vapor transmission test method cup method".

[0106] The performance indicators of the embodiments and comparative examples are shown in Tables 1 and 2. As can be seen from Table 2, the adhesion of Examples 1-6 and Comparative Example 1 is relatively good. This is because Examples 1-6 and Comparative Example 1 introduce phosphate monomers, which can react with the steel substrate, so that the coating has good adhesion. The salt water resistance, oxygen permeability, and water vapor permeability of Examples 1-6 are better than those of Comparative Example 1. This is because Examples 1-6 have a network interpenetrating structure, have good water resistance, and better barrier properties, which can better delay the penetration of salt spray, water vapor, and oxygen. The hardness of Examples 1-6 is higher than that of Comparative Example 1. This is because Examples 1-6 have a network interpenetrating structure, which makes the paint film have higher hardness and better scratch resistance. The flexibility of Examples 1-6 is better than that of Comparative Example 1. This is because Examples 1-6 have a network interpenetrating structure, which forms a strong link between the molecular chains, thereby improving the flexibility and strength of the molecular chains.

[0107] Table 1 Performance indicators of the emulsions of the embodiments and comparative examples

[0108] Table 2 Primer performance indicators of Examples and Comparative Examples

[0109] Note: When conducting water and oxygen permeability tests, the dry film thickness is 20um.

Claims

1. An interpenetrating network PVDC emulsion, characterized in that: It is prepared from the following components by weight:

2. The interpenetrating network type PVDC emulsion according to claim 1, characterized in that, The organic silicon monomer is at least one of vinyl trimethoxy silane, vinyl triethoxy silane, vinyl tri (2-methoxyethoxy) silane and methyl vinyl dichloro silane.

3. The interpenetrating network type PVDC emulsion according to claim 1, characterized in that, The acrylic acid phosphate monomer is at least one of 2-hydroxyethyl methacrylate phosphate, methacrylate phosphate, and 2-methacrylate ethoxyethyl phosphate.

4. The interpenetrating network type PVDC emulsion according to claim 1, characterized in that, The hydrophilic monomer is at least one of acrylic acid and methacrylic acid.

5. The interpenetrating network type PVDC emulsion according to claim 1, characterized in that, The cross-linking monomer is at least one of ethylene glycol diacrylate, divinylbenzene, methylene bisacrylamide, and diallyl maleate.

6. The interpenetrating network type PVDC emulsion according to claim 1, characterized in that, The comonomers are at least two of acrylonitrile, methyl acrylate, butyl acrylate, ethyl acrylate, hydroxymethyl acrylate, hydroxyethyl acrylate, methyl methacrylate, ethyl methacrylate, and butyl methacrylate.

7. The interpenetrating network type PVDC emulsion according to claim 1, characterized in that, The emulsifier is at least one of sodium dodecylbenzene sulfonate, sodium dodecyl sulfonate, sodium pentadecyl sulfate and sodium dodecyl sulfate.

8. The interpenetrating network type PVDC emulsion according to claim 1, characterized in that, The initiator is a mixture of tert-butyl hydroperoxide and Rongalite.

9. The method for preparing the interpenetrating network type PVDC emulsion according to claims 1 to 8, characterized in that: The following steps are involved: (1) Prepare reaction raw materials By weight, the reaction raw materials consist of: (2) preparing an emulsifier aqueous solution: preparing an emulsifier aqueous solution by mixing an emulsifier with 30-35% deionized water; (3) preparing a polymerization initiator aqueous solution: preparing a polymerization initiator aqueous solution by mixing 50% of the initiator with 5.5-6.5% of deionized water; (4) preparing a residual initiator aqueous solution: preparing a residual initiator aqueous solution by mixing the remaining initiator with 4-5% deionized water; (5) Seed emulsion polymerization: add the remaining deionized water, styrene, silicone monomer, 1-3% of vinylidene chloride monomer, 4-12% of acrylic acid phosphate monomer, 4.5-10.5% of cross-linking monomer, 2-12% of comonomer, 20-40% of hydrophilic monomer, 5-10% of emulsifier aqueous solution to a polymerization kettle, cold disperse for 15-35 minutes at a stirring speed of 80-150 rpm, heat to 45-75° C., add 5-10% of polymerization initiator aqueous solution to react, and the reaction time is 0.5-2.5 hours to obtain a seed emulsion; (6) Adding polymerization: adding the remaining vinylidene chloride monomer, the remaining acrylic acid phosphate monomer, the remaining cross-linking monomer, the remaining comonomer, the remaining hydrophilic monomer, the remaining emulsifier aqueous solution, and the remaining polymerization initiator aqueous solution to the above seed emulsion at a temperature of 45 to 75° C. and a stirring speed of 80 to 150 rpm to react for 12 to 15 hours to obtain a reaction product; (7) Emulsion residue elimination: Add an aqueous solution of a residue elimination initiator to the reaction product obtained in step (6) at a temperature of 45 to 75° C. and a stirring speed of 80 to 150 rpm for a reaction time of 0.5 to 1.5 h, cool, and filter to obtain the product.

10. The method for preparing an interpenetrating network type PVDC emulsion according to claim 9, characterized in that: The polymerization kettle is evacuated before the seed emulsion polymerization.

11. The method for preparing an interpenetrating network type PVDC emulsion according to claim 9, characterized in that: The mesh size of the filtration in step (7) is 250 to 450 meshes.

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