Vinyl acetate-vinyl versatate emulsion for exterior wall coating and preparation method therefor

Abstract

Provided in the present invention are a vinyl acetate-vinyl versatate emulsion for an exterior wall coating and a preparation method therefor. The vinyl acetate-vinyl versatate emulsion is obtained by means of a polymerization reaction of a pre-emulsified solution with a bottom liquid, wherein the pre-emulsified solution comprises the following monomer components in parts by weight: 18-22 parts of an acrylate soft monomer, 20-30 parts of vinyl acetate, 8-12 parts of vinyl versatate, 1-3 parts of a functional monomer, and 1-3 parts of an organosilicon monomer, the functional monomer being a hydrophilic monomer; the pre-emulsified solution comprises an emulsifier I, the emulsifier I being composed of an anionic emulsifier and a nonionic emulsifier; and the bottom liquid comprises an emulsifier II, the emulsifier II being composed of a reactive emulsifier and a nonionic emulsifier. The vinyl acetate-vinyl versatate emulsion of the present invention has good compatibility with a substrate, favorable adhesion, a relatively good paint-forming stability, fire resistance, water-induced-whitening resistance and dilution stability, and good compatibility with an alkaline substrate.

Description

A kind of vinato emulsion for exterior wall coating and preparation method thereof Technical Field

[0001] The present invention relates to the technical field of materials, and in particular to a vac-vegetal emulsion for exterior wall coatings and a preparation method thereof. Background Art

[0002] Exterior wall coatings play a crucial role in building maintenance and environmental beautification. Exterior wall coatings are continuously developing towards water-based, highly decorative, highly weather-resistant, and environmentally friendly finishes. Common exterior wall coating materials currently available on the market generally have poor paint stability, suffer from water absorption and whitening, and have a poor coefficient of expansion, which can cause cracking and bulging on the paint surface. Furthermore, existing coating materials have poor compatibility with substrates, lack significant fire protection, and exhibit suboptimal adhesion. Therefore, there is an urgent need to develop a coating material with excellent fire resistance, water whitening resistance, stability, and strong adhesion.

[0003] VAT emulsions are made from vinyl acetate plasticized with versatate, polymerized using self-crosslinking technology. Due to its environmentally friendly and glossy properties, they are increasingly becoming one of the preferred film-forming materials for decorative coatings. Vinyl acetate's low film-forming temperature reduces the amount of film-forming aids required, lowering production costs for coatings companies. However, VAT emulsions still require improvement in overall performance. In exterior wall coatings, they exhibit issues such as water absorption, whitening, poor expansion coefficient, and poor adhesion to substrates.

[0004] Summary of the Invention

[0005] In view of this, the object of the present invention is to solve the above problems and to provide a vac-vegetative emulsion for exterior wall coatings and a preparation method thereof. The vac-vegetative emulsion of the present invention has good compatibility with substrates, good adhesion, good paint stability, good fire resistance, water whitening resistance, and good compatibility with alkaline substrates.

[0006] The technical solutions of the present invention are as follows:

[0007] A vinacetic acid emulsion for exterior wall coatings, obtained by polymerization of pre-emulsion and kettle bottom liquid.

[0008] The pre-emulsion comprises the following monomer components in parts by weight: 18-22 parts of acrylic soft monomer, 20-30 parts of vinyl acetate, 8-12 parts of vinyl ester carbonate, 1-3 parts of functional monomer, and 1-3 parts of organosilicon monomer, wherein the functional monomer is a hydrophilic monomer;

[0009] The pre-emulsion liquid includes emulsifier 1, which is composed of anionic emulsifier and nonionic emulsifier; the kettle bottom liquid includes emulsifier 2, which is composed of reactive emulsifier and nonionic emulsifier.

[0010] The monomer components of the present invention are based on acrylic soft monomers, vinyl acetate, and vinyl esters, and organic silicon monomers and hydrophilic functional monomers are introduced. The organic silicon monomers and components such as vinyl acetate and vinyl esters interact through coupling, thereby improving the compatibility between the emulsion and the substrate, reducing the interfacial tension between the coating and the substrate, and improving the adhesion and stability of the coating. The hydrophilic functional monomers undergo a cross-linking reaction with the vinyl acetate and vinyl esters, forming a water-soluble or water-dispersible structure in the coating, thereby increasing the resistance of the coating to water, reducing the whitening phenomenon caused by water absorption of the coating, and improving the water-whitening resistance of the coating.

[0011] As a preferred technical solution of the present invention, the acrylic soft monomer is selected from butyl acrylate, isooctyl acrylate, or a mixture thereof. The acrylic soft monomer polymer having a glass transition temperature of -20 to -70°C imparts good elasticity, softness, and ductility to the emulsion after film formation.

[0012] As a preferred technical solution of the present invention, the functional monomer is selected from a mixture of hydrophilic monomers acrylic acid and acrylamide. Preferably, the weight ratio of acrylic acid to acrylamide is 1:1. The hydrophilic monomer helps increase the coating's resistance to water, reduces whitening caused by water absorption, and improves the coating's resistance to water whitening.

[0013] As a preferred technical solution of the present invention, the organosilicon monomer is selected from one or a combination of vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and γ-(2,3-glycidoxy)propyltrimethoxysilane. For example, it can be selected from A171 silane coupling agent, A174 silane coupling agent, and A187 silane coupling agent produced by Momentive. The organosilicon monomer acts as a crosslinking agent, crosslinking with other components in the vinanolide emulsion to increase the strength of the coating and improve the stability and durability of the finished paint.

[0014] As a preferred technical solution of the present invention, in the first emulsifier, the anionic emulsifier is selected from one or a combination of fatty alcohol polyoxyethylene ether succinate, sodium dodecyl diphenyl oxide disulfonate, and sodium allyloxyhydroxypropyl sulfonate. Furthermore, the fatty alcohol polyoxyethylene ether succinate is a sulfonate obtained by sulfonating a fatty alcohol with polyoxyethylene (EO). For example, Cytec's AEROSOL A-102 emulsion emulsifier can be used; the sodium dodecyl diphenyl oxide disulfonate can be DOWFAX 2A1 emulsifier from Dow Chemical.

[0015] The nonionic emulsifier is selected from fatty alcohol ethoxylate emulsifiers, for example, one or more of the emulsifiers LCN287, LCN407 and LCN118 produced by Clariant.

[0016] In a specific implementation process, in the emulsifier 1, the weight portion of the anionic emulsifier is 0.5-2 parts, and the weight portion of the nonionic emulsifier is 1-2 parts.

[0017] As a preferred technical solution of the present invention, in the second emulsifier, the reactive emulsifier is selected from sodium allyloxyhydroxypropane sulfonate. Further, for example, Solvay's COPS-1 emulsifier can be used.

[0018] The nonionic emulsifier is selected from fatty alcohol ethoxylate emulsifiers, for example, one or more emulsifiers of Clariant models LCN287, LCN407 and LCN118.

[0019] In a specific implementation process, in the emulsifier 2, the weight portion of the reactive emulsifier is 1-3 parts, and the weight portion of the nonionic emulsifier is 1-3 parts.

[0020] The selection of emulsifiers in the present invention plays a key role in preparing an emulsion with suitable properties. Using anionic and nonionic emulsifiers in the pre-emulsion to emulsify the monomers facilitates interaction between the monomers and improves the sufficiency of polymerization. Using a reactive emulsifier and a nonionic emulsifier in the reactor bottom liquid, the introduction of the reactive nonionic emulsifier allows the emulsion to react more fully during the cross-linking reaction and improves reaction stability. Using a single emulsifier increases the risk of experimental failure, makes the emulsion prone to demulsification, and reduces reaction stability. This combination of emulsifiers produces an emulsion with high stability and a good expansion coefficient, making the paint surface less prone to cracking or bulging during application.

[0021] As a preferred technical solution of the present invention, the pre-emulsion includes initiator 1, and the kettle bottom liquid includes initiator 2. The initiator 1 and initiator 2 are selected from one of ammonium persulfate, potassium persulfate and sodium persulfate, and the amount of the initiator is the conventional amount used in this field.

[0022] A method for preparing a vac-vegetal emulsion for exterior wall coatings comprises the following steps:

[0023] Prepare the raw materials according to the recipe; this step can be prepared separately or performed simultaneously during the preparation process;

[0024] Prepare pre-emulsion: mix water, emulsifier 1, acrylic soft monomer, vinyl acetate, vinyl ester carbonate, functional monomer, silicone monomer and initiator 1, and stir evenly to obtain pre-emulsion;

[0025] Prepare the bottom liquid: add water and emulsifier 2 into the reactor and stir evenly, heat to the reaction temperature, then add initiator 2 and keep stirring;

[0026] Take 1-5% of the total mass of the pre-emulsion and add it to the bottom liquid of the kettle. After the temperature in the reactor returns to the reaction temperature, start adding the remaining pre-emulsion dropwise at a uniform speed. After the addition is completed, adjust the pH value to obtain an emulsion.

[0027] As a preferred technical solution of the present invention, the reaction temperature is 70-75° C., and the total time of the dropwise addition reaction in step (4) is controlled to be 3-5 hours.

[0028] In the preparation process of the present invention, each monomer is first fully mixed with emulsifier 1 and initiator 1 in a pre-emulsion, and then emulsifier 2 and initiator 2 are fully mixed in a kettle bottom liquid. When the reaction time is appropriate (the reaction temperature is appropriate), a small portion of the pre-emulsion is first added to the kettle bottom liquid for reaction to generate a seed emulsion with an appropriate particle size. After the reaction is stable, the remaining pre-emulsion is added dropwise at a uniform speed to perform a stable polymerization reaction, and finally an emulsion with appropriate performance is prepared.

[0029] Compared with the prior art, the technical solution provided by the present invention has the following significant beneficial effects:

[0030] On the basis of acrylic soft monomers, vinyl acetate, and vinyl versatate, silicone monomers and hydrophilic functional monomers are introduced to improve the compatibility of the emulsion with the substrate, reduce the interfacial tension between the coating and the substrate, improve the adhesion and stability of the coating, increase the coating's resistance to water, reduce the whitening phenomenon caused by water absorption of the coating, and improve the coating's water whitening resistance.

[0031] By selecting and matching emulsifiers, anionic emulsifiers and nonionic emulsifiers are used in the pre-emulsion to fully emulsify each monomer, and reactive emulsifiers and nonionic emulsifiers are used in the reactor bottom liquid, so that the emulsion is more fully cross-linked and the reaction stability is greatly improved. In addition, in the pre-emulsion, each monomer is first fully mixed with emulsifier 1 and initiator 1. In the reactor bottom liquid, emulsifier 2 and initiator 2 are fully mixed. A small portion of the pre-emulsion is added to the reactor bottom liquid for reaction to generate a seed emulsion with an appropriate particle size. After the reaction stabilizes, the remaining pre-emulsion is added dropwise at a uniform rate to carry out a stable polymerization reaction, ultimately producing an emulsion with excellent performance and good emulsion stability.

[0032] The emulsion obtained by the present invention has excellent performance, good compatibility with substrates, good adhesion, good paint stability, good fire resistance, water whitening resistance, good dilution stability, good compatibility with alkaline substrates, and meets the use requirements of exterior wall coatings. DETAILED DESCRIPTION

[0033] To provide a clearer understanding of the technical features, objectives, and beneficial effects of the present invention, the following detailed description of the technical solution of the present invention is provided. However, this description should not be construed as limiting the scope of the present invention. The experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0034] Example 1

[0035] A method for preparing a vac-vegetal emulsion for exterior wall coatings, comprising the following steps:

[0036] Prepare the raw materials according to the formula in Table 1;

[0037] Prepare pre-emulsion: add water and emulsifier 1 to the monomer tank, stir evenly, then add acrylic soft monomer, vinyl acetate, vinyl ester carbonate, functional monomer, silicone monomer and initiator 1, stir evenly to obtain pre-emulsion.

[0038] Prepare the bottom liquid: add water and emulsifier 2 into the reactor and stir evenly, heat to about 73℃, then add initiator 2 and keep stirring;

[0039] Take about 5% of the total mass of the pre-emulsion in the monomer tank and add it to the reactor. After the temperature in the reactor rises to 73°C, start adding the remaining pre-emulsion at a uniform rate. The total addition time is controlled within 4 hours. After the addition is completed, adjust the pH value to 3 to complete the preparation of the emulsion.

[0040] Table 1

[0041] Example 2

[0042] A method for preparing a vac-vegetal emulsion for exterior wall coatings, comprising the following steps:

[0043] Prepare the raw materials according to the formula in Table 2;

[0044] Prepare pre-emulsion: add water and emulsifier 1 to the monomer tank, stir evenly, then add acrylic soft monomer, vinyl acetate, vinyl ester carbonate, functional monomer, silicone monomer and initiator 1, stir evenly to obtain pre-emulsion.

[0045] Prepare the bottom liquid: add water and emulsifier 2 into the reactor and stir evenly, heat to 72℃, then add initiator 2 and keep stirring;

[0046] Take about 4% of the total mass of the pre-emulsion in the monomer tank and add it to the reactor. After the temperature in the reactor rises to 72°C, start adding the remaining pre-emulsion at a uniform rate. The total addition time is controlled within 4 hours. After the addition is completed, adjust the pH value to 3 to complete the preparation of the emulsion.

[0047] Table 2

[0048] Example 3

[0049] A method for preparing a vac-vegetal emulsion for exterior wall coatings, comprising the following steps:

[0050] Prepare the raw materials according to the formula in Table 3;

[0051] Prepare pre-emulsion: add water and emulsifier 1 to the monomer tank, stir evenly, then add acrylic soft monomer, vinyl acetate, vinyl ester carbonate, functional monomer, silicone monomer and initiator 1, stir evenly to obtain pre-emulsion.

[0052] Prepare the bottom liquid: add water and emulsifier 2 into the reactor and stir evenly, heat to about 75°C, then add initiator 2 and keep stirring;

[0053] Take about 5% of the total mass of the pre-emulsion in the monomer tank and add it to the reactor. After the temperature in the reactor rises to 75°C, start adding the remaining pre-emulsion at a uniform rate. The total addition time is controlled within 4 hours. After the addition is completed, adjust the pH value to 3 to complete the preparation of the emulsion.

[0054] Table 3

[0055] Example 4

[0056] A method for preparing a vac-vegetal emulsion for exterior wall coatings, comprising the following steps:

[0057] Prepare the raw materials according to the formula in Table 4;

[0058] Prepare pre-emulsion: add water and emulsifier 1 to the monomer tank, stir evenly, then add acrylic soft monomer, vinyl acetate, vinyl ester carbonate, functional monomer, silicone monomer and initiator 1, stir evenly to obtain pre-emulsion.

[0059] Prepare the bottom liquid: add water and emulsifier 2 into the reactor and stir evenly, heat to about 70℃, then add initiator 2 and keep stirring;

[0060] Take about 3% of the total mass of the pre-emulsion in the monomer tank and add it to the reactor. After the temperature in the reactor rises to 70°C, start adding the remaining pre-emulsion at a uniform rate. The total addition time is controlled within 4 hours. After the addition is completed, adjust the pH value to 3 to complete the preparation of the emulsion.

[0061] Table 4

[0062] Comparative Example 1

[0063] The raw materials are shown in Table 5. Compared with Example 1, the amounts of monomer components in the pre-emulsion are different, namely, 21 parts of butyl acrylate, 15 parts of vinyl acetate, and 15 parts of vinyl ester carbonate. The rest are the same as in Example 1.

[0064] Table 5

[0065] Comparative Example 2

[0066] The raw materials are shown in Table 6. Compared with Example 1, no organosilicon monomer is added, and the rest are the same as Example 1.

[0067] Table 6

[0068] Comparative Example 3

[0069] The raw materials are shown in Table 7. Compared with Example 1, no functional monomer is added, and the rest are the same as Example 1.

[0070] Table 7

[0071] Comparative Example 4

[0072] The raw materials are shown in Table 8. Compared with Example 1, the emulsifier 1 uses a single anionic emulsifier, and the amount of DOWFAX 2A1 used is 2.5 parts. The rest are the same as in Example 1.

[0073] Table 8

[0074] Comparative Example 5

[0075] The raw materials are shown in Table 9. Compared with Example 1, the second emulsifier uses a single nonionic emulsifier, Clariant LCN287, and the amount of Clariant LCN287 is 4 parts. The rest are the same as Example 1.

[0076] Table 9

[0077] Comparative Example 6

[0078] Commercially available RS-2212F vinacetic acid emulsion.

[0079] Comparative Example 7

[0080] Commercially available Clariant Mowilith DM230 tertiary carbon emulsion.

[0081] Product performance testing

[0082] The performance tests of the emulsions of the examples and comparative examples of the present invention were carried out as follows.

[0083] The paint stability test is in accordance with GB / T 9756-2018;

[0084] Fire resistance, water whitening resistance, water resistance and expansion coefficient tests are in accordance with GB14907-2018;

[0085] Adhesion test is in accordance with GB / T 9286-1998.

[0086] The test results are shown in Table 10.

[0087] Table 10

[0088] It can be seen from Table 10 that the performance of the emulsion provided by the embodiment of the present invention is better than that of the comparative example, and is better than the common vac-veolar emulsion on the market.

[0089] In Comparative Example 1, after the monomer components were changed, the amount of vinyl acetate was reduced and the amount of versatate vinyl carbonate was increased, the expansion coefficient of the product deteriorated, and the fire resistance deteriorated; in Comparative Example 2, the product without adding silicone monomer had poor water resistance and fire resistance, and the expansion coefficient increased; in Comparative Example 3, no functional monomer was added, the product viscosity decreased, the water resistance deteriorated, the adhesion deteriorated, the fire resistance deteriorated, and the expansion coefficient deteriorated; in Comparative Example 4, emulsifier 1 used a single anionic emulsifier DOWFAX 2A1, and the storage stability deteriorated; in Comparative Example 5, emulsifier 2 used a single nonionic emulsifier Clariant LCN287, and the water resistance and adhesion deteriorated; Comparative Example 6 had poor storage stability and poor water resistance; Comparative Example 7 had poor fire resistance and water resistance.

[0090] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention (including the claims) is limited to these examples. Within the scope of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present invention as described above, which are not provided in detail for the sake of simplicity.

[0091] The embodiments of the present invention are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the scope of protection of the present invention.

Claims

1. A vinanoic acid emulsion for exterior wall coatings, characterized in that: The vinato vacce emulsion is obtained by polymerization reaction of pre-emulsified liquid and kettle bottom liquid; The pre-emulsion comprises the following monomer components in parts by weight: 18-22 parts of acrylic soft monomer, 20-30 parts of vinyl acetate, 8-12 parts of vinyl versatate, 1-3 parts of functional monomer, and 1-3 parts of silicone monomer; The functional monomer is a hydrophilic monomer; The pre-emulsion also includes emulsifier 1, which is composed of anionic emulsifier and nonionic emulsifier; The kettle bottom liquid comprises emulsifier 2, and the emulsifier 2 is composed of a reactive emulsifier and a non-ionic emulsifier.

2. The vac-velop emulsion for exterior wall coating according to claim 1, characterized in that: The acrylic soft monomer is selected from butyl acrylate, isooctyl acrylate or a mixture of the two.

3. The vac-vegetal emulsion for exterior wall coating according to claim 1, characterized in that: The functional monomer is a mixture of acrylic acid and acrylamide.

4. The vac-vegetal emulsion for exterior wall coating according to claim 1, characterized in that: The organic silicon monomer is selected from one or a combination of vinyl trimethoxysilane, γ-methacryloxypropyl trimethoxysilane, and γ-(2,3-epoxypropyloxy)propyl trimethoxysilane.

5. The vac-vegetal emulsion for exterior wall coating according to claim 1, characterized in that: In the emulsifier 1, the anionic emulsifier is selected from one or a combination of fatty alcohol polyoxyethylene ether succinate, sodium dodecyl diphenyl oxide disulfonate, and sodium allyloxy hydroxypropyl sulfonate; The nonionic emulsifier is selected from fatty alcohol ethoxylate emulsifiers.

6. The vac-vegetal emulsion for exterior wall coating according to claim 1, characterized in that: In the second emulsifier, the reactive emulsifier is selected from sodium allyloxyhydroxypropane sulfonate; and the nonionic emulsifier is selected from fatty alcohol ethoxylate emulsifier.

7. The vac-vegetal emulsion for exterior wall coating according to claim 1, characterized in that: The pre-emulsion liquid includes initiator 1, the kettle bottom liquid includes initiator 2, and the initiator 1 and initiator 2 are selected from one of ammonium persulfate, potassium persulfate and sodium persulfate.

8. The method for preparing the vac-vegetable emulsion for exterior wall coating according to any one of claims 1 to 7, comprising the following steps: Prepare pre-emulsion: water, emulsifier 1, acrylic soft monomer, vinyl acetate, tert-butyl vinyl carbonate The ester, functional monomer, silicone monomer and initiator are mixed and stirred evenly to obtain a pre-emulsion; Prepare the bottom liquid of the kettle: add water and emulsifier 2 into the reactor and stir evenly, heat up to the reaction temperature, then add initiator 2 and keep stirring; 1-5% of the total mass of the pre-emulsion is added to the bottom liquid of the reactor. After the temperature in the reactor rises to the reaction temperature, the remaining pre-emulsion is added dropwise at a uniform speed. After the addition is completed, the pH value is adjusted to obtain an emulsion.

9. The preparation method according to claim 8, characterized in that: The reaction temperature is 70-75°C.

10. The preparation method according to claim 8, characterized in that: When the remaining pre-emulsion is added dropwise at a uniform speed, the total reaction time of the addition is controlled to be 3-5 hours.

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