Anti-doodling acrylic emulsion as well as preparation method and application thereof

Abstract

The invention discloses an anti-doodling acrylic emulsion as well as a preparation method and application thereof. The emulsion is prepared from the following monomer components in percentage by weight through an emulsion polymerization method and then steam stripping: a) 15-70% of ester monomers; b) 1.3%-10% of an olefinic unsaturated monomer containing an acetoacetic acid group; c) 0.5%-5% of an unsaturated hydrophilic monomer; d) 0.2%-5% of a reactive silane coupling agent; e) 10 to 50% of styrene; f) 14 to 25 percent of an anti-graffiti monomer; wherein the total mass of the components a), b), c), d), e) and f) is 100%. In the formula, the anti-doodling emulsion can be compounded with a skin-feeling polyurethane emulsion for use, so that a paint film is endowed with an anti-doodling skin-feeling effect.

Description

Technical Field

[0001] The invention relates to the field of coatings, in particular to an acrylic emulsion, and in particular to an anti-graffiti acrylic emulsion and a preparation method and application thereof. Background Art

[0002] With the development of society and the improvement of people's living standards, people are increasingly pursuing a high quality of life and clean walls. They not only pursue a smooth wall effect, but also hope that the wall can be kept clean. The wall will inevitably be stained with some stains in life, such as black tea, vinegar, water-based pen graffiti, etc., which seriously affect the wall effect and sensory experience.

[0003] At present, the anti-graffiti products on the market are mainly two-component products, which have problems such as strong odor, complex construction, slow drying speed, high cost, etc. We need a one-component product with low odor and simple construction.

[0004] Patent CN115181442A introduces a skin-feel coating that is cured by UV light, but this method requires UV light, which is complicated to operate and difficult to be practical for indoor coatings.

[0005] Patent CN111763471A achieves skin-feeling effect by using polyurethane microspheres, but the anti-graffiti effect of large-particle polyurethane microspheres is not outstanding, and it is difficult to achieve both anti-graffiti and skin-feeling effects. Summary of the invention

[0006] In order to solve the above technical problems, according to one aspect of the present invention, firstly, an anti-graffiti acrylic emulsion is provided, to which an anti-graffiti monomer is added, which contains a double bond similar to that of maleic acid. This type of monomer has a very high tendency to copolymerize with styrene and can participate in the copolymerization in large quantities, effectively avoiding the problem that large steric hindrance monomers are difficult to polymerize. At the same time, triphenylsilane has extremely strong hydrophobicity, and the incorporation of this structure into the polymer effectively improves the hydrophobicity of the polymer, further improving the anti-graffiti performance of the coating.

[0007] According to another aspect of the present invention, a method for preparing a skin-feel anti-graffiti emulsion system is also provided. By batch mixing an anti-graffiti acrylic emulsion with a large-particle polyurethane emulsion, and utilizing the characteristic of the large-particle polyurethane emulsion having a skin-feel effect, the paint film has a strong anti-graffiti effect while having a skin-feel effect.

[0008] According to another aspect of the present invention, there is also provided a use of an anti-graffiti acrylic emulsion in a coating.

[0009] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0010] An anti-graffiti acrylic emulsion is prepared by emulsion polymerization, comprising the following monomer components in weight ratio:

[0011] a) 15-70%, preferably 44-66% of ester monomers;

[0012] b) 1.3-10%, preferably 2-4%, of an ethylenically unsaturated monomer containing an acetoacetate group;

[0013] c) 0.5-5%, preferably 1-5%, of an unsaturated hydrophilic monomer;

[0014] d) 0.2-5%, preferably 0.5-2% of a reactive silane coupling agent;

[0015] e) 10-50%, preferably 20-30%, of styrene;

[0016] f) 14-25%, preferably 10-15%, of an anti-graffiti monomer;

[0017] The total mass of components a), b), c), d), e), and f) is 100%.

[0018] In a preferred embodiment of the present invention, component a) is selected from alkyl acrylates, allyl esters, vinyl acetate and methyl substitutes thereof having 1 to 16 carbon atoms, preferably selected from alkyl acrylates, vinyl acetate and methyl substitutes thereof having 1 to 8 carbon atoms, more preferably selected from one or more of methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, methyl 2-methacrylate, isopentyl methacrylate and heptyl methacrylate.

[0019] Preferably, component b) is selected from one or more of ethyl acetoacetoxyacrylate, propoxy acetoacetate acrylate, butoxy acetoacetate acrylate, vinyl acetoacetate, allyl acetoacetate and methyl substitutes thereof, preferably one or two of ethyl acetoacetoxyacrylate and allyl acetoacetate.

[0020] Preferably, component c) is selected from unsaturated monomers containing hydrophilic groups, and the hydrophilic groups are selected from carboxyl groups, hydroxyl groups, amide groups, sulfonic acid groups, phosphate groups, urea groups, sulfonate groups, sulfate groups, and phosphate groups; preferably, the component c) is preferably one or more of acrylic acid, methacrylic acid, hydroxyethyl acrylate, acrylamide, methacrylamide, ethyl ethylene urea, vinyl alkoxy phosphate, and sodium 2-acrylamide-2-methylpropane sulfonate.

[0021] Preferably, component d) is selected from silane coupling agents containing vinyl or epoxy functional groups, preferably one or more of vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-glycidyloxypropyltrimethoxysilane, and mercaptopropyltrimethoxysilane.

[0022] In a preferred embodiment of the present invention, component f) is as shown in formula I:

[0023]

[0024] The preparation method of the component f) of the present invention comprises the following steps: triphenylsilane reacts with maleic acid.

[0025] The reaction formula is as follows:

[0026]

[0027] In the preparation method of component f), the molar ratio of triphenylsilane to maleic acid is 1:(1.2-1.5).

[0028] In a preferred embodiment of the present invention, the raw materials for preparing the emulsion optionally include an emulsifier, an initiator, a neutralizer, a post-treatment agent, a pH regulator, and water.

[0029] In a preferred embodiment of the present invention, the emulsifier is selected from one or more of sodium dodecyl sulfate, sodium p-styrene sulfonate, sodium dodecylbenzene sulfonate, alcohol ether sulfosuccinate, alkyl alcohol ether sulfate, and alkyl alcohol ether phosphate, preferably sodium dodecyl sulfate and / or sodium dodecylbenzene sulfonate.

[0030] Preferably, the amount of the emulsifier used is 1-5%, preferably 1-2%, of the total mass of components a)-f).

[0031] The initiator is selected from one or more of sodium persulfate, potassium persulfate and ammonium persulfate, preferably sodium persulfate and / or potassium persulfate.

[0032] Preferably, the total amount of the initiator is 0.2-0.6%, preferably 0.2-0.4%, of the total mass of components a)-f).

[0033] The neutralizing agent is selected from one or more of sodium bicarbonate, diethylenetriamine, diethanolamine, and ethanolamine, preferably sodium bicarbonate.

[0034] Preferably, the neutralizing agent is used in an amount of 0.1-4%, preferably 0.1-0.3%, of the total mass of the monomer components a)-f).

[0035] The post-treatment agent includes an oxidant and / or a reducing agent, wherein the oxidant is selected from one or more of tert-butyl hydroperoxide, hydrogen peroxide, sodium persulfate, potassium persulfate, and ammonium persulfate, preferably tert-butyl hydroperoxide and / or hydrogen peroxide; the reducing agent is selected from one or more of sodium bisulfite, sodium pyrosulfite, and vitamin C, preferably sodium bisulfite and / or sodium pyrosulfite.

[0036] Preferably, the total amount of the post-treatment agent is 0.15-0.6%, preferably 0.2-0.4%, of the total mass of components a)-f).

[0037] The pH regulator is selected from one or more of diethylenetriamine, diethanolamine, and ethanolamine, preferably diethylenetriamine and / or ethanolamine;

[0038] Preferably, the end point of the pH regulator addition is to adjust the system pH to 7-9.

[0039] Preferably, the total amount of water used is 1-1.5 times, preferably 1-1.3 times, the total mass of components a)-f).

[0040] The acrylic ester emulsion of the present invention has a solid content of 41-45%, a pH of 7-9, and an emulsion particle size of 69-80 nm.

[0041] According to another aspect of the present invention, a method for preparing the anti-graffiti acrylic emulsion is provided, comprising the following steps:

[0042] 1) uniformly mixing components a), b), c), d), e), f), water, and part of the emulsifier to prepare a pre-emulsion;

[0043] 2) The initiator is divided into two parts and dissolved in water respectively to obtain a dropwise initiator and a bottom initiator;

[0044] 3) Mix the neutralizer, the remaining emulsifier and water and add them into the reactor, stir them thoroughly, and heat them to 80-90°C; add part of the pre-emulsified liquid, stir them evenly, then add all the initiator at the bottom of the reactor, and react for 10-20 minutes to obtain the seed emulsion;

[0045] 4) Control the temperature in the reactor to 80-90°C, continue to add the remaining pre-emulsion and all the dropwise initiator to the seed emulsion for 2-4 hours, and then keep warm for 20-60 minutes;

[0046] 5) Cool the reactor to 70-80°C, gradually add the post-treatment agent to the reactor for 2-4 hours, and then keep warm for 30-60 minutes;

[0047] 6) Cool down to below 45°C, add pH adjuster to adjust the pH of the system to 7-9, and perform steam stripping and filter to discharge the material.

[0048] In a preferred embodiment of the present invention, the amount of the partial emulsifier in step 1) accounts for 90-99.5% of the mass of the total emulsifier.

[0049] Preferably, the amount of water used in step 1) accounts for 25-35% of the total water mass.

[0050] In a preferred embodiment of the present invention, the amount of initiator used to prepare the dropwise initiator in step 2) accounts for 25-50% of the total mass of the initiator, and the amount of initiator used to prepare the bottom initiator accounts for 50-75% of the total mass of the initiator.

[0051] Preferably, the amount of water used to prepare the dropwise initiator in step 2) accounts for 1-6% of the total mass of water, and the amount of water used to prepare the bottom initiator accounts for 1-6% of the total mass of water.

[0052] Preferably, the amount of the pre-emulsion used to prepare the seed emulsion in step 3) is 1-8% of the total mass of the pre-emulsion in step 1).

[0053] In a preferred embodiment of the present invention, in step 6), the stripping temperature is 55-85°C, and the pressure is controlled at -75Kpa to -95Kpa.

[0054] Component f) contains a double bond similar to maleic acid. This type of monomer has a very high tendency to copolymerize with styrene and can participate in the copolymerization in large quantities, effectively avoiding the problem that large steric hindrance monomers are difficult to polymerize. At the same time, triphenylsilane has extremely strong hydrophobicity. Introducing this structure into the polymer effectively improves the hydrophobicity of the polymer and further improves the anti-graffiti performance of the coating. At the same time, the polymer in the emulsion contains maleimide with polyphenyl silicon substituents. On the one hand, silicone has strong hydrophobicity and is often used in super-hydrophobic materials. On the other hand, the polyphenyl substitution structure increases the hydrophobicity of the monomer, making it more difficult for hydrophilic stains to invade the polymer surface. The double bond structure on maleic acid is to provide a carrier that is extremely easy to polymerize on the polymer. The hydrophobic substance is polymerized on the polymer and is more stable and will not be washed away by hydrates. Therefore, the polymer of this system has better stain resistance and is easy to clean.

[0055] According to another aspect of the present invention, there is also provided an application of the anti-graffiti acrylic emulsion or the anti-graffiti acrylic emulsion prepared by the method in coatings.

[0056] The acrylic emulsion of the present invention has good film-forming effect and low MFFT (minimum film-forming temperature) without adding a film-forming aid, has the advantages of excellent scrub resistance and freeze-thaw stability, low VOC content, good environmental performance, etc., and is particularly suitable for use in the field of building interior wall coatings.

[0057] The acrylic emulsion provided by the invention is a water-based emulsion, has the characteristics of low VOC, safety and environmental protection, excellent anti-graffiti performance and simple construction. DETAILED DESCRIPTION

[0058] The present invention is further described below by means of specific examples. The examples described in the present invention are only used to illustrate the present invention and do not limit the scope of the present invention.

[0059] The raw materials used in the following examples are shown in Table 1. Other raw materials are common commercially available unless otherwise specified:

[0060] Table 1 Raw material information

[0061]

[0062]

[0063] The following processing procedures are adopted in the following embodiments:

[0064] Stripping: The emulsion is placed in a buffer kettle and preheated to 55°C, and then passed into a stripping tower for stripping (stripping temperature 55°C); the emulsion is fed at the top of the tower, and the air and steam are fed at the bottom of the tower. The two are in countercurrent contact and mixed at high speed in a short time. The steam and air carry VOC components and separate from the emulsion through the vacuum tail gas pipeline, and the emulsion is discharged from the bottom. During the stripping process, the relative flow rates of air, steam and emulsion are 1:0.5:10.

[0065] Watercolor pen resistance evaluation: Scrape 100μ wet film on black and white cardboard, dry at room temperature for 1 day, draw lines with 12-color washable watercolor pens of Morning Light, wipe with a wet cloth immediately, 1 day, and 3 days later, and observe the erasure situation. Evaluation criteria:

[0066] 5 points: Erase all.

[0067] 4 points: All parts except the red part containing solvent are erased, and the red pen leaves a slight mark.

[0068] 3 points: All except the red color containing solvent are erased, and the red pen leaves a clear mark.

[0069] 2 points: The watercolor pen leaves a slight mark, and the red pen leaves a clear mark.

[0070] 1 point: The watercolor pen leaves a clear mark.

[0071] 0 points: The paint film is damaged and not wiped off at all.

[0072] Water resistance evaluation: Determine the water resistance of latex paint according to HG / T 5065-2016.

[0073] VOC: Volatile substances with a boiling point below 250°C tested according to GB / T 18582.

[0074] SVOC: Volatile substances with a boiling point of 250-400°C tested according to GB / T 18582.

[0075] Olfactory level: 10 people are randomly selected as the scoring standard to score the smell of the same period samples, among which:

[0076] 0 points: no odor

[0077] 1 point: Slight odor, hardly noticeable.

[0078] 2 points: Slight odor, pleasant smell.

[0079] 3 points: slight odor, pungent smell.

[0080] 4 points: There is a very obvious odor.

[0081] 5 points: The odor is very obvious and discomfort such as dizziness occurs.

[0082] Scrub resistance: The scrub resistance of the paint film is tested according to HG / T 5065-2016.

[0083] [Preparation Example]

[0084] Triphenylsilane reacts with maleic acid to generate an anti-graffiti monomer

[0085] In step A of the above-mentioned synthesis process, the molar ratio of triphenylsilane to maleic acid is 1:1.2, the reaction temperature is 15-25 degrees Celsius, and the reaction is stirred overnight. After the reaction is completed, dichloromethane is used to dissolve it, and water is used to extract the unreacted maleic acid. Then, it is dried overnight with anhydrous sodium sulfate, and the dichloromethane is distilled to obtain monomer Q.

[0086]

[0087] 1 H NMR (300MHz, DMSO, 298K): 2.81 (4H, -CH2-), 5.83 (2H, -CH=CH-), 7.5 (15H, -C6H5-)

[0088] [Example 1]

[0089] Prepare the ingredients according to the following recipe:

[0090] a) 609g of BA

[0091] b) 38g of AAEM

[0092] c) 14g of AA

[0093] d) 5G A171

[0094] e) 167 g styrene

[0095] f) 167g anti-graffiti monomer Q.

[0096] Separately, prepare 9.19 g of emulsifier SDS, 9 g of SSS, 3 g of initiator APS, 2 g of neutralizer sodium bicarbonate, post-treatment agent (2 g of t-BHP and 40 g of 5 wt % aqueous sodium bisulfite solution), 1323 g of water, and pH adjuster diethylenetriamine.

[0097] Prepare the acrylic emulsion as follows:

[0098] 1) Components a), b), c), d), e), f) and 433 g of water, 9 g of emulsifier SDS, and 9 g of emulsifier SSS were mixed uniformly to prepare a pre-emulsion;

[0099] 2) 1 g of initiator APS was fully mixed with 38 g of water to obtain a dropwise initiator; 2 g of initiator APS was fully mixed with 21 g of water to obtain a bottom initiator;

[0100] 3) 2g of sodium bicarbonate, 0.19g of emulsifier SDS and 831g of water were mixed and added to the reactor, stirred thoroughly, and heated to 85°C; 50g of pre-emulsion was added, and after stirring evenly, all the initiators at the bottom of the reactor were added, and the mixture was reacted for 10 minutes to obtain a seed emulsion;

[0101] 4) Control the temperature in the reactor to 85°C, continue to add the remaining pre-emulsion and all the dropwise initiators to the seed emulsion at the same time, the total dropwise addition time is 4 hours, and then keep warm for 2 minutes;

[0102] 5) Cool the reactor to 75°C, gradually add post-treatment agent (2 g t-BHP and 40 g 5 wt% sodium bisulfite aqueous solution) into the reactor for 2 h, and then keep warm for 30 min;

[0103] 6) Cool down to below 45°C, add pH adjuster diethylenetriamine to adjust the pH of the system to 8, steam strip, filter with a 100-mesh filter, and discharge.

[0104] [Example 2-8]

[0105] Acrylic emulsions were prepared according to the same method as in Example 1, except that the raw material selection and dosage in Table 2 were different; at the same time, the amount of pre-emulsion added in step 3) accounted for 5% of the total mass.

[0106] Table 2 Selection and dosage of raw materials in Examples 1-8 (unit: g)

[0107]

[0108]

[0109] The coatings were prepared according to the formulation in Table 3.

[0110] Table 3 Coating formula

[0111]

[0112]

[0113] The test results of the coating properties obtained in the examples are shown in Table 4.

[0114] Table 4 Performance test results of coatings obtained from emulsions in the examples

[0115]

[0116] [Comparative Example 1]

[0117] An acrylic emulsion was prepared in substantially the same manner as in Example 1, except that component f was not added.

[0118] [Comparative Example 2]

[0119] An acrylic emulsion was prepared in substantially the same manner as in Example 1, except that component f was replaced with maleic anhydride of the same mass.

[0120] [Comparative Example 3]

[0121] An acrylic emulsion was prepared in substantially the same manner as in Example 1, except that 3102 in the coating formulation was replaced by water.

[0122] The coating properties of Comparative Examples 1-3 are shown in Table 5.

[0123] Table 5 Coating properties of comparative examples 1-3

[0124] Comparative Example 1 Comparative Example 2 Comparative Example 3 Finish paint container status No caking No caking No caking Finishing coating properties good good good Does the coating feel skin-friendly? yes yes no Paint film drying time (surface dry, h) 2h 2h 2h Watercolor pen resistance 0 0 4 Water resistance Failed Failed Failed VOC <500ppm <500ppm <500ppm SVOC <500ppm <500ppm <500ppm Smell level 1 1 1 Scrub resistance (times) 323 274 656

Claims

1. An anti-graffiti acrylic emulsion, comprising the following monomer components in weight ratios prepared by emulsion polymerization: a) 15-70%, preferably 44-66% of ester monomers; b) 1.3-10%, preferably 2-4%, of an ethylenically unsaturated monomer containing an acetoacetate group; c) 0.5-5%, preferably 1-5%, of an unsaturated hydrophilic monomer; d) 0.2-5%, preferably 0.5-2% of a reactive silane coupling agent; e) 10-50%, preferably 20-30%, of styrene; f) 14-25%, preferably 10-15%, of an anti-graffiti monomer; in, The total mass of components a), b), c), d), e), f) is 100%.

2. The anti-graffiti acrylic emulsion according to claim 1, characterized in that: Component a) is selected from alkyl acrylates, allyl esters, vinyl acetate and methyl substitutes thereof having 1 to 16 carbon atoms, preferably selected from alkyl acrylates, vinyl acetate and methyl substitutes thereof having 1 to 8 carbon atoms, more preferably selected from one or more of methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, methyl 2-methacrylate, isopentyl methacrylate and heptyl methacrylate.

3. The anti-graffiti acrylic emulsion according to claim 1 or 2, characterized in that: Component b) is selected from one or more of ethyl acetoacetoxyacrylate, propoxy acetoacetate acrylate, butoxy acetoacetate acrylate, vinyl acetoacetate, allyl acetoacetate and methyl substitutes thereof, preferably one or two of ethyl acetoacetoxyacrylate and allyl acetoacetate.

4. The anti-graffiti acrylic emulsion according to any one of claims 1 to 3, characterized in that: Component c) is selected from unsaturated monomers containing hydrophilic groups, and the hydrophilic groups are selected from carboxyl groups, hydroxyl groups, amide groups, sulfonic acid groups, phosphate groups, urea groups, sulfonate groups, sulfate groups, and phosphate groups; preferably, the component c) is preferably one or more of acrylic acid, methacrylic acid, hydroxyethyl acrylate, acrylamide, methacrylamide, ethyl ethylene urea, vinyl alkoxy phosphate, and sodium 2-acrylamide-2-methylpropane sulfonate.

5. The anti-graffiti acrylic emulsion according to any one of claims 1 to 4, characterized in that: Component f) is shown in formula I:

6. The anti-graffiti acrylic emulsion according to any one of claims 1 to 5, characterized in that: a method for preparing the component f), The method comprises the following steps: triphenylsilane reacts with maleic acid; the molar ratio of triphenylsilane to maleic acid is 1:(1.2-1.5).

7. A method for preparing the anti-graffiti acrylic emulsion according to any one of claims 1 to 6, comprising the following steps: 1) uniformly mixing components a), b), c), d), e), f), water, and part of the emulsifier to prepare a pre-emulsion; 2) Dividing the initiator into two parts and dissolving them in water respectively to obtain a dropwise initiator and a bottom initiator; 3) Mix the neutralizer, the remaining emulsifier and water and add them into the reactor, stir them thoroughly, and heat them to 80-90°C; add part of the pre-emulsified liquid, stir them evenly, then add all the initiator at the bottom of the reactor, and react for 10-20 minutes to obtain the seed emulsion; 4) Control the temperature in the reactor to 80-90°C, continue to add the remaining pre-emulsion and all the dropwise initiator to the seed emulsion for 2-4 hours, and then keep warm for 20-60 minutes; 5) Cool the reactor to 70-80°C, gradually add the post-treatment agent to the reactor for 2-4 hours, and then keep warm for 30-60 minutes; 6) Cool down to below 45°C, add pH adjuster to adjust the pH of the system to 7-9, and perform steam stripping and filter to discharge the material.

8. The method according to claim 7, characterized in that The amount of the emulsifier used in step 1) accounts for 90-99.5% of the total mass of the emulsifier; preferably, the amount of water used in step 1) accounts for 25-35% of the total mass of the water.

9. The method according to claim 7, characterized in that: The amount of initiator used to prepare the dropwise initiator in step 2) accounts for 25-50% of the total mass, and the amount of initiator used to prepare the bottom initiator accounts for 50-75% of the total mass; preferably, the amount of the pre-emulsion used to prepare the seed emulsion in step 3) accounts for 1-8% of the total mass.

10. Use of the anti-graffiti acrylic emulsion according to any one of claims 1 to 6 or the anti-graffiti acrylic emulsion prepared by the method according to any one of claims 7 to 9 in coatings.

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