An interpenetrating network type pvdc emulsion

Abstract

This invention discloses an interpenetrating network type PVDC emulsion, which is prepared by weight of the following components: 650-850 parts of vinylidene chloride monomer, 20-60 parts of styrene, 2-6 parts of organosilicon monomer, 25-55 parts of acrylate phosphate monomer, 3-5.5 parts of crosslinking monomer, 10-25 parts of hydrophilic monomer, 100-150 parts of comonomer, 10-30 parts of emulsifier, 0.5-1.5 parts of initiator, and 550-750 parts of deionized water. This invention has the advantages of simple process, good product stability, high barrier performance, excellent adhesion, and good water resistance.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and more specifically, to an interpenetrating network type PVDC emulsion. Background Technology

[0002] Steel, as an important structural material, plays a vital role in our production and daily life. However, steel is highly susceptible to corrosion by corrosive media such as oxygen, moisture, and salt spray, leading to loss of strength, safety accidents, and economic losses. Statistics show that global economic losses due to steel corrosion reach as high as $250 million annually, making the exploration of simple and efficient corrosion prevention technologies crucial. Polyvinylidene chloride (PVDC) possesses good structural symmetry, resulting in high crystallinity. Combined with the strong polarity and hydrophobicity of its carbon-chlorine bonds, PVDC exhibits excellent barrier properties against water vapor and oxygen. Therefore, many industry experts are exploring the application of PVDC in the field of steel corrosion protection.

[0003] For example, CN108129926A discloses a barrier coating, its preparation method, and its application. The barrier coating, by weight, comprises the following raw material components: 10-30 parts styrene-butadiene emulsion, 60-80 parts polyvinylidene chloride emulsion, 5-10 parts ethylene-vinyl acetate copolymer, and 0.5-2 parts additives. This invention blends styrene-butadiene emulsion and ethylene-vinyl acetate copolymer in a suitable ratio 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 using this barrier coating demonstrates good water and oxygen barrier properties. However, this invention simply mixes several emulsions, resulting in poor compatibility. Furthermore, the strength and water resistance of the film need further improvement.

[0004] For example, CN105669890A discloses a polyvinylidene chloride emulsion for preparing water-based metal anti-corrosion coatings and its preparation method. Polyvinylidene chloride, acrylate monomers, hydroxyethyl methacrylate phosphate, N-hydroxymethyl acrylamide, emulsifier, and deionized water are pre-emulsified. Under the action of an initiator, a seed emulsion polymerization method is used to obtain a polyvinylidene chloride emulsion with good emulsion stability. By introducing polar monomers, the adhesion between the emulsion and the substrate is increased. The prepared water-based anti-corrosion coating uses water as the main dispersion medium, does not contain volatile organic solvents, is environmentally friendly and non-toxic, and adheres firmly to the metal substrate. The drawback is that although the introduction of acrylate phosphate monomers improves the adhesion of the coating to the steel substrate, the water resistance and film strength are relatively poor. Summary of the Invention

[0005] The present invention aims to overcome the shortcomings of existing technologies and provide an interpenetrating network type PVDC emulsion with good coating stability, high barrier performance, excellent adhesion, and good water resistance.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: an interpenetrating network PVDC emulsion, prepared by weight of the following components:

[0007]

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

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

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

[0011] In a preferred embodiment of the present invention, the crosslinking monomer is at least one of ethylene glycol diacrylate, divinylbenzene, methylenebisacrylamide, and diallyl maleate.

[0012] In 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] In a preferred embodiment of the present invention, the emulsifier is at least one of sodium dodecylbenzenesulfonate, sodium dodecyl sulfonate, sodium pentadecyl sulfate, and sodium dodecyl sulfate.

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

[0015] The interpenetrating network PVDC emulsion of this invention, through optimized formulation and the introduction of crosslinking monomers, enables the molecular chains of the shell and core layers to form an interpenetrating network structure, resulting in an interpenetrating network PVDC emulsion with good stability, high barrier properties, excellent adhesion and water resistance, and good flexibility. This interpenetrating network PVDC emulsion is particularly suitable for the field of steel corrosion protection.

[0016] In this invention, during the seed emulsion polymerization stage, the crosslinking monomer containing two double bonds reacts with seed monomers such as styrene, organosilicon monomers, vinylidene chloride monomers, phosphate acrylate monomers, comonomers, and hydrophilic monomers. The crosslinking monomer consumes one double bond, leaving one remaining. Thus, a reactive molecular chain containing one double bond is formed during the seed emulsion polymerization stage. During the feed polymerization stage, the monomers in the feed polymerization stage have a swelling effect on the latex particles formed in the previous seed emulsion polymerization stage (polymerization and swelling occur simultaneously). The reactive molecular chains in the latex particles formed during the seed emulsion polymerization stage react with the feed monomers such as vinylidene chloride monomers, phosphate acrylate monomers, crosslinking monomers, comonomers, and hydrophilic monomers from the feed polymerization stage, forming new reactive molecular chains on top of the original molecular chains. This process repeats, and combined with the swelling effect of the feed monomers on the seeds, ultimately forming an interpenetrating network structure with vinylidene chloride, styrene, organosilicon monomers, and phosphate acrylate monomers as the shell layers and vinylidene chloride, comonomers, and phosphate acrylate monomers as the core layers.

[0017] Compared with existing technologies, 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, organosilicon monomers, acrylate phosphate monomers, etc. as shell layers, and vinylidene chloride, comonomers, acrylate phosphate monomers, etc. as core layers. The network interpenetration structure between the two molecular chains significantly improves the water resistance and strength of the coating. The steel anti-corrosion coating made with 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 easy to disperse in water and less likely to settle and break down, thus losing their application performance. The PVDC emulsion of the present invention can be stored at room temperature for more than 8.5 months.

[0020] 3. The resulting coating has strong adhesion. The acrylate phosphate monomers and acrylic monomers introduced into the PVDC emulsion in this invention can interact with substrates such as steel to improve the adhesion between the coating and the substrates such as steel. The resulting coating has an adhesion level of 0 or higher.

[0021] 4. The resulting coating has excellent rust prevention effect. This invention introduces acrylic phosphate monomers into the PVDC emulsion. During the film formation process, the phosphate functional groups can form a dense phosphate protective film with the steel substrate, which passivates the steel substrate and achieves a good rust prevention effect.

[0022] 5. The resulting coating exhibits excellent barrier properties. The interpenetrating network PVDC emulsion of this invention reduces the mobility of molecular chains through cross-linking, making it more difficult for water vapor and oxygen to migrate within the coating, thus better protecting the steel substrate. The resulting coating has an oxygen permeability of 35 cm⁻¹. 3 / m 2 • For days below, the water vapor transmission rate is 11 g / m 2 • Day or less. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to the embodiments, but the present invention is not limited to the following embodiments.

[0024] Example 1

[0025] An interpenetrating network PVDC emulsion has the following raw material formulation:

[0026]

[0027] The preparation method is as follows:

[0028] (1) Preparation of emulsifier aqueous solution: Weigh 20 kg of sodium dodecyl sulfate and prepare sodium dodecyl sulfate aqueous solution with 200 kg of deionized water for later use;

[0029] (2) Prepare the polymerization initiator aqueous solution: Weigh 85g of TBHP and prepare a TBHP aqueous solution with 20Kg of deionized water for later use; Weigh 85g of SFS and prepare an SFS aqueous solution with 20Kg of deionized water for later use.

[0030] (3) Prepare the aqueous solution of the residue removal initiator: Weigh 400g of TBHP and prepare an aqueous solution of TBHP with 10KG of deionized water for later use; Weigh 400g of SFS and prepare an aqueous solution of SFS with 20KG of deionized water for later use.

[0031] (4) Seed emulsion polymerization: First, put 375Kg of deionized water into the polymerization kettle, and evacuate the polymerization kettle to -0.095Mpa. Under this vacuum, pump 10Kg of vinylidene chloride, 27.5Kg of styrene, 2.5Kg of vinyltrimethoxysilane, 2.5Kg of ethoxyethyl phosphate of 2-methacrylate, 4.85Kg of methyl acrylate, 175g of divinylbenzene, 2.5Kg of methacrylic acid and 5% of sodium dodecyl sulfate aqueous solution prepared in step (1) into the polymerization kettle. Cold disperse at a stirring speed of 90rpm for 30 minutes, maintain this speed and heat up to 55℃. Then, add 5% of TBHP aqueous solution prepared in step (2) and 5% of SFS aqueous solution prepared in step (2) at a uniform rate within 13h to react for 1h to obtain seed emulsion.

[0032] (5) Addition polymerization: Keep the temperature of the polymerization kettle at 55℃ and the stirring speed at 90 rpm. Add the remaining sodium dodecyl sulfate aqueous solution, the remaining vinylidene chloride, 47.5 kg butyl acrylate, the remaining methyl acrylate, 9.5 kg acrylic acid, the remaining ethoxyethyl phosphate of 2-methacrylate, the remaining divinylbenzene, the remaining TBHP aqueous solution and SFS aqueous solution prepared in step (2) to the seed emulsion obtained in step (4) and react for 13 h to end the reaction and obtain the reaction product;

[0033] (6) Residual removal of emulsion: Under the condition of maintaining the temperature of the polymerization reactor at 55°C and the stirring speed at 90 rpm, the TBHP aqueous solution and SFS aqueous solution prepared in step (3) are uniformly fed into the polymerization reactor within 20 minutes. After the feeding is completed, the temperature is kept at 0.5 h and then cooled to 20°C. The PVDC emulsion with a solid content of 58% is obtained by filtering with a 300 mesh filter. The properties are shown in Table 1.

[0034] Example 2

[0035] An interpenetrating network PVDC emulsion has the following raw material formulation:

[0036]

[0037] The preparation method was the same as in Example 1, and a PVDC emulsion with a solid content of 59.2% was obtained. The properties are shown in Table 1.

[0038] Example 3

[0039] An interpenetrating network PVDC emulsion has the following raw material formulation:

[0040]

[0041] The preparation method was the same as in Example 1, and a PVDC emulsion with a solid content of 58.6% was obtained. The properties are shown in Table 1.

[0042] Example 4

[0043] An interpenetrating network PVDC emulsion has the following raw material formulation:

[0044]

[0045]

[0046] The preparation method was the same as in Example 1, and a PVDC emulsion with a solid content of 59.5% was obtained. The properties are shown in Table 1.

[0047] Example 5

[0048] An interpenetrating network PVDC emulsion has the following raw material formulation:

[0049]

[0050] The preparation method was the same as in Example 1, and a PVDC emulsion with a solid content of 59.3% was obtained. The properties are shown in Table 1.

[0051] Example 6

[0052] An interpenetrating network PVDC emulsion has the following raw material formulation:

[0053]

[0054]

[0055] The preparation method was the same as in Example 1, and a PVDC emulsion with a solid content of 59.5% was obtained. The properties are shown in Table 1.

[0056] Comparative Example 1

[0057] The emulsion obtained in Comparative Example 1 was prepared according to the method described in Example 1 of CN105669890A, and its properties are shown in Table 1.

[0058] Performance testing

[0059] The PVDC emulsions obtained in Examples 1-6 and Comparative Example 1 were used to prepare anti-corrosion coatings for steel. The preparation process is as follows: 100 parts of PVDC emulsion, 30 parts of general-purpose water-based colorant (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 mixed to form an anti-corrosion coating for steel 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. A 30 μm wet film was prepared, and the performance of the coating film was tested. The performance is shown in Table 2.

[0060] Adhesion test: Performed according to the method specified in GB / T9286-1998 "Paints and varnishes, cross-cut test of paint film";

[0061] Salt water resistance test: Performed according to the method specified in GB / T10834-2008 "Determination of salt water resistance of marine paints - Salt water and hot salt water immersion method";

[0062] Flexibility test: Performed according to the method specified in GB / T1731-2020 "Test Method for Flexibility of Paint Film and Putty Film";

[0063] Pencil hardness test: The test was conducted according to the method specified in GB / T6739-2006 "Paints and varnishes - Pencil method for testing the hardness of paint film".

[0064] Oxygen barrier performance test: Performed according to the method specified in GB / T1038-2000 "Test method for gas permeability of plastic films and sheets - differential pressure method";

[0065] Water vapor barrier performance test: Performed according to the method specified in GB / T1037-1988 "Test method for water vapor permeability of plastic films and sheets - cup method".

[0066] The performance indicators of the examples and comparative examples are shown in Tables 1 and 2. Table 2 shows that 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 ester monomers, which can react with the steel substrate, resulting in better adhesion of the coating. Examples 1-6 exhibit better salt water resistance, oxygen permeability, and water vapor permeability than Comparative Example 1. This is because Examples 1-6 possess an interpenetrating network structure, exhibiting better water resistance and barrier properties, thus better delaying the penetration of salt spray, water vapor, and oxygen. Examples 1-6 have higher hardness than Comparative Example 1 because they possess an interpenetrating network structure, resulting in higher film hardness and better scratch resistance. Examples 1-6 have better flexibility than Comparative Example 1 because they possess an interpenetrating network structure, forming strong links between molecular chains, thereby improving the flexibility and strength of the molecular chains.

[0067] Table 1. Performance indicators of the emulsions from the examples and comparative examples.

[0068]

[0069]

[0070] Table 2. Primer performance indicators for the examples and comparative examples.

[0071]

[0072] Note: The dry film thickness is 20µm when conducting water permeability and oxygen permeability tests.

Claims

1. An interpenetrating network type PVDC emulsion, characterized in that, It 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 organosilicon monomer 25-55 parts of acrylate phosphate monomers 3-5.5 parts of cross-linked monomer 10-25 parts of hydrophilic monomer 100-150 parts of comonomer 10-30 parts emulsifier Initiator 0.5~1.5 parts 550-750 parts of deionized water The crosslinking monomer is methylenebisacrylamide containing two double bonds. In the seed emulsion polymerization stage, the methylenebisacrylamide containing two double bonds reacts with styrene, organosilicon monomers, vinylidene chloride monomers, phosphate acrylate monomers, comonomers, and hydrophilic monomers to form a reactive molecular chain containing one double bond. In the feed polymerization stage, the reactive molecular chains in the latex particles formed in the seed emulsion polymerization stage react with vinylidene chloride monomers, phosphate acrylate monomers, crosslinking monomers, comonomers, and hydrophilic monomers to finally form an interpenetrating network PVDC emulsion with a core-shell structure. The hydrophilic monomer is at least one of acrylic acid and methacrylic acid, and 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.

2. The interpenetrating network PVDC emulsion according to claim 1, characterized in that, The organosilicon monomer is at least one of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(2-methoxyethoxy)silane, and methylvinyldichlorosilane.

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

4. The interpenetrating network PVDC emulsion according to claim 1, characterized in that, The acrylate phosphate monomer is methacrylate phosphate.

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

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

Images