Preparation method of modified acrylic hard emulsion

Abstract

The invention provides a preparation method of a modified acrylic hard emulsion. A small amount of soft monomer composition is introduced in the resin modified hard emulsion polymerization process, implosion is initiated through a high-proportion initiator, a large number of low-glass-transition-temperature active chain segments are formed, and subsequent hard monomers can continue to react on the active chain segments; the resin part of the finally formed emulsion particle structure can be closer to the outer layer and cannot be coated on the inner layer of the emulsion particle in the reaction process, so that the high-transparency resin modified acrylic hard emulsion is obtained.

Description

Technical field:

[0001] The invention relates to the field of acrylic emulsions, and in particular to a method for preparing a modified acrylic hard emulsion. Background technology:

[0002] In the process of using various substrates, due to the defects of the substrates themselves, it is often necessary to use various organic polymers to modify the surface of the substrate or add them during the application process. These polymers are usually dissolved in various solvents, but the use of solvents usually brings various pollution and dangers. Therefore, emulsion polymerization with water as the dispersion liquid has received more and more attention. Although the use of water as a dispersant can greatly improve the disadvantages of using solvents, due to the huge difference between water and polymers, the polymers usually appear milky white after being dispersed in water. For low TG soft emulsions with good film-forming properties, the final paint film will be transparent because the polymers fuse with each other during the film-forming process. However, for resin-modified hard emulsions, during the polymerization process, because the glass transition temperature of the polymer itself is near or higher than the reaction temperature, as the high-glass transition temperature polymer chains are formed, the macromolecular resin segments in the reaction system will be continuously coated by the polymer inside the latex particles, so the hydrophilic resin of the outer layer of the latex particles formed in the end will be reduced, seriously affecting the transparency of the emulsion. For application scenarios with high requirements for the transparency of the paint film, the use is greatly restricted. Compared with low TG soft emulsion, high TG hard emulsion can bring better paint film hardness, higher heat resistance and wear resistance during use. Therefore, low TG soft emulsion cannot be used alone to replace hard emulsion.

[0003] The reason why the solution has better transparency than the emulsion is that the polymer can be completely dissolved in the solvent and is in a uniform system as a whole, while the polymer in the emulsion is completely separated from the water phase, so there will be obvious light scattering, making the emulsion look turbid and opaque. Therefore, the conventional method for preparing high-transparency emulsions is basically to make the emulsion particle size very small, reducing the light scattering phenomenon, such as the patent CN111138598A, a small-particle acrylic acid aqueous dispersion and its preparation method, which is obtained by free radical-induced aqueous emulsion polymerization, and its particle size can be controlled according to the required size, and can be less than 50nm, and the finished product transmittance coefficient is greater than 15.

[0004] Another way is to improve the overall hydrophilicity of the polymer structure, so that the polymer dispersed in water can have better compatibility with water, reduce the difference between the two phases to improve the emulsion transparency. For example, patents such as CN 110167993A and CN110198960A mainly use alkali-soluble resin as the outer layer of the polymer structure design. Because the alkali-soluble resin contains more hydrophilic segments, compared with the emulsion products prepared by conventional small molecule emulsifiers, the alkali-soluble modified emulsion has better transparency. However, this method has an obvious disadvantage in the process of preparing high TG hard emulsions: during the emulsion polymerization process, due to the high TG of the formed polymer, the newly formed polymer will continuously encapsulate the hydrophilic segments of the macromolecules into the latex particles during the aggregation process on the surface of the latex particles. The hydrophilic molecular chains of the outer layer of the latex particles formed in the end will be much less than the theoretical amount, and the final hard emulsion transparency will be significantly reduced. Summary of the invention:

[0005] In view of the shortcomings of the prior art, the present invention provides a method for preparing a modified acrylic hard emulsion. In the present invention, a small amount of soft monomer composition is introduced into the polymerization process of the resin modified hard emulsion to initiate implosion through a high proportion of initiator, so as to form a large number of low glass transition temperature active segments, and the subsequent hard monomers can continue to react on the active segments, and the resin part of the latex particle structure finally formed can be closer to the outer layer and will not be coated in the inner layer of the latex particles during the reaction process, thereby obtaining a high-transparency resin modified acrylic hard emulsion.

[0006] In the present invention, the term Fox Tg refers to the glass transition temperature Tg calculated according to the Fox equation: 1 / Tg=W1 / Tg1+W2 / Tg2+···+Wn / Tgn. Wherein W1, W2, ...Wn refer to the mass fractions of monomers 1, 2, ...n in the combined monomers, respectively, and Tg1, Tg2, ...Tgn refer to the glass transition temperatures of the homopolymers of monomers 1, 2, ...n in the combined monomers, respectively. The design of the Fox Tg of the combined monomers is a well-known method in the art, and the technicians can combine and screen the existing disclosed monomers according to actual needs, and the present invention has no special requirements.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] A method for preparing a modified acrylic hard emulsion comprises the following steps:

[0009] S1: adding an alkali-soluble resin into an alkaline aqueous solution and stirring to completely dissolve the alkali-soluble resin;

[0010] S2: Preparation of active segments: The temperature in the reactor is maintained at 60-95°C, and polymerization monomer A is added to the reactor. After the polymerization monomer A is fully mixed in the reactor, initiator A is added to initiate the reaction, and the temperature is kept to allow the seeds to form stably;

[0011] S3: After the reaction in step S2 is completed, add the polymerization monomer B and the initiator B, and keep the temperature after the addition is completed;

[0012] S4: cooling the material to room temperature and discharging the material to obtain the modified acrylic hard emulsion.

[0013] Preferably, the alkali-soluble resin refers to a resin or polymer that can dissolve more than 10 grams in one liter of alkaline aqueous solution at room temperature, preferably an alkali-soluble acrylic resin, such as alkali-soluble styrene-maleic anhydride resin, alkali-soluble styrene-acrylic resin, alkali-soluble (meth)acrylate-acrylic resin, preferably alkali-soluble styrene-acrylic resin BASF678, LD713, etc.

[0014] Preferably, the weight average molecular weight Mw of the alkali-soluble solid resin is between 2000 and 20000, such as 4000, 6000, 8000, 12000, preferably 6000-15000;

[0015] Preferably, the acid value of the alkali-soluble resin is controlled between 100 and 250 mgKOH / g, such as 120 mgKOH / g, 160 mgKOH / g, 180 mgKOH / g, 200 mgKOH / g, 240 mgKOH / g, preferably 150-240 mgKOH / g;

[0016] Preferably, the glass transition temperature Tg of the alkali-soluble resin is controlled between 30 and 120°C, such as 50°C, 70°C, 90°C, 120°C, preferably 70-100°C.

[0017] Preferably, in step S1, the alkaline aqueous solution can be prepared by adding an alkaline substance into water, and the alkaline substance can be an alkali metal hydroxide, ammonia water, etc.

[0018] Preferably, in step S1, the temperature may be raised to dissolve the alkali-soluble solid resin, and the temperature may be 30-90°C.

[0019] Preferably, in step S2, the amount of initiator A is more than 5% and less than 50% of the mass of the polymerized monomer A, for example 6%, 7%, 8%, 9%, 10%, 12%, 15%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 40%, 50%, preferably 5-30%.

[0020] Furthermore, the monomer initiation method in step S2 can be a thermally initiated emulsion polymerization reaction or a redox emulsion polymerization method using a redox initiator. In this emulsion polymerization method, it can be carried out in the presence of various common initiator systems, and the initiator A includes but is not limited to a thermal initiator and / or a redox initiator;

[0021] The thermal initiator is selected from one or more of persulfates (such as ammonium sulfate, sodium persulfate, potassium persulfate), tert-butyl hydroperoxide, and hydrogen peroxide;

[0022] The redox initiator generally comprises an oxidant and a reductant; the oxidant is selected from one or more of ammonium persulfate, sodium persulfate, potassium persulfate, tert-butyl hydroperoxide, and hydrogen peroxide, preferably one or more of ammonium persulfate, sodium persulfate, and potassium persulfate;

[0023] The reducing agent is selected from one or more of alkali metal sulfites, such as potassium and / or sodium sulfites, alkali metal bisulfites, such as potassium and / or sodium bisulfites, alkali metal metabisulfites, such as potassium and / or sodium metabisulfites, formaldehyde bisulfites, such as potassium and / or sodium formaldehyde bisulfites, alkali metal salts of aliphatic sulfinic acids, such as potassium and / or sodium methylsulfinate, alkali metal hydrogen sulfides, such as potassium and / or sodium hydrogen sulfide, acetone bisulfite, such as sodium acetone bisulfite (2-hydroxy-2-propanesulfonic acid monosodium salt), ascorbic acid, and isoascorbic acid.

[0024] Preferably, the polymerizable monomer A is selected from a mixture of (meth)acrylate monomers, non-acidic (meth)propylene monomers and styrene monomers.

[0025] Further, the styrene monomer includes but is not limited to at least one of styrene or α-methylstyrene;

[0026] The (meth) acrylic acid ester monomers include but are not limited to at least one of methyl methacrylate, cyclohexyl methacrylate, ethyl methacrylate, butyl methacrylate, isooctyl methacrylate, glycidyl methacrylate, hydroxyethyl methacrylate, allyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl acrylate, lauryl acrylate, lauryl methacrylate, octadecyl acrylate, and octadecyl methacrylate;

[0027] The non-acidic (meth) acrylic monomers include but are not limited to diacetone acrylamide, acrylamide, and hydroxymethyl acrylamide.

[0028] Preferably, in step S2, the total glass transition temperature Tg of the added polymerized monomer A is calculated according to the FOX formula, and the Tg value is less than or equal to 40°C, for example, -60°C, -30°C, 0°C, 40°C, preferably -10-10°C, and more preferably 0°C.

[0029] Preferably, in step S3, the polymerizable monomers B include (meth)acrylate monomers, non-acidic (meth)propylene monomers and styrene monomers.

[0030] Further, the styrene monomer includes but is not limited to at least one of styrene or α-methylstyrene;

[0031] The (meth)acrylates include but are not limited to methyl methacrylate, cyclohexyl methacrylate, ethyl methacrylate, butyl methacrylate, isooctyl methacrylate, glycidyl methacrylate, hydroxyethyl methacrylate, allyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl acrylate, lauryl acrylate, lauryl methacrylate, octadecyl acrylate, at least one of octadecyl methacrylate;

[0032] The non-acidic (meth) acrylic monomers include but are not limited to diacetone acrylamide, acrylamide, and hydroxymethyl acrylamide.

[0033] Preferably, the polymerizable monomer A accounts for more than 1% and less than 20% of the total monomer mass, for example, 1%, 5%, 10%, 15%, 20%, preferably 5-15%.

[0034] Preferably, in step S3, according to the FOX formula, the total glass transition temperature Tg of the added polymerized monomer B is greater than or equal to 65°C, for example, 70°C, 80°C, 90°C, 100°C, preferably 80-100°C, more preferably 100°C.

[0035] The polymerizable monomers A and B are directly added to the reactor or are prepared as pre-emulsions using emulsifiers and then added to the reactor. Preferably, they are added dropwise. The emulsifier may be a non-reactive anionic and / or non-reactive non-ionic surfactant.

[0036] The non-reactive anionic surfactant includes, but is not limited to, one or more of alkyl, aryl or alkylaryl sulfates, sulfonates or phosphates, alkyl sulfonic acids, sulfosuccinates, fatty alcohol ether sulfates and fatty acids;

[0037] The non-reactive non-ionic surfactant includes, but is not limited to, alcohol or phenol ethoxylates, such as polyoxyethylene alkylphenyl ethers. More preferably, the non-reactive non-ionic surfactant includes, but is not limited to, one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, fatty alcohol polyoxyethylene ethers and salts thereof, and fatty alcohol ether phosphates and salts thereof.

[0038] The surfactant may also be a polymerizable surfactant containing at least one ethylenically unsaturated functional group, also known as a reactive surfactant; the polymerizable surfactant includes, for example, but is not limited to, allyl polyoxyalkylene ether sulfate salts such as sodium salt of allyl polyoxyethylene alkyl ether sulfate, allyl alkyl succinate sulfonate salts, allyl ether hydroxypropane sulfonate salts such as sodium salt, polyoxyethylene styrenated phenyl ether sulfate salts such as ammonium salt.

[0039] The surfactant used in the present invention may be a non-reactive surfactant, a reactive surfactant or a combination thereof.

[0040] Preferably, the total amount of the emulsifier used in the present invention is 0.2-3% of the total mass of the polymerized monomer A and the polymerized monomer B, such as 1%, 1.5%, 2%, preferably 0.2-0.5%.

[0041] More preferably, the monomers A and B are polymerized in the absence of an emulsifier.

[0042] The preparation method of the high-permeability resin modified acrylic hard emulsion is based on the total mass of polymerized monomer A, polymerized monomer B and alkali-soluble solid resin as 100%, and the mass content of the alkali-soluble solid resin is 10-90%, such as 15%, 35%, 55%, 75%, preferably 25-65%.

[0043] In a preferred embodiment, in the emulsion polymerization method of the present invention, the polymerization temperature of the entire polymerization process is 50-100° C., preferably 70-90° C. The total polymerization time can be several hours, such as 2-8 hours, preferably 3-6 hours.

[0044] Preferably, in step S3, the amount of initiator B accounts for more than 0.1% of the mass of polymerized monomer B, preferably 0.1-1%.

[0045] The initiator B includes but is not limited to a thermal initiator and / or a redox initiator;

[0046] The thermal initiator is selected from one or more of persulfate, tert-butyl hydroperoxide, and hydrogen peroxide; more preferably, the persulfate is selected from ammonium sulfate, sodium persulfate, or potassium persulfate;

[0047] The redox initiator generally comprises an oxidant and a reductant; the oxidant is selected from one or more of ammonium persulfate, sodium persulfate, potassium persulfate, tert-butyl hydroperoxide, and hydrogen peroxide, preferably one or more of ammonium persulfate, sodium persulfate, and potassium persulfate;

[0048] The reducing agent is selected from one or more of alkali metal sulfites, such as potassium and / or sodium sulfites, alkali metal bisulfites, such as potassium and / or sodium bisulfites, alkali metal metabisulfites, such as potassium and / or sodium metabisulfites, formaldehyde bisulfites, such as potassium and / or sodium formaldehyde bisulfites, alkali metal salts of aliphatic sulfinic acids, such as potassium and / or sodium methylsulfinate, alkali metal hydrogen sulfides, such as potassium and / or sodium hydrogen sulfide, acetone bisulfites, such as sodium acetone bisulfite (2-hydroxy-2-propanesulfonic acid monosodium salt), ascorbic acid, and isoascorbic acid. In step S4, optionally, after the insulation is completed, an initiator is added to consume the unreacted monomers.

[0049] In step S4, a base (such as aqueous ammonia) may be added to adjust the pH to 7-9.

[0050] The solid content of the modified acrylic hard emulsion of the present invention is 10-70wt%, preferably 30-60wt%, more preferably 40-50wt%.

[0051] The pH of the modified acrylic hard emulsion of the present invention is 7-10, preferably 7.5-9.5, more preferably 8-9.

[0052] The present invention introduces a small amount of soft monomer composition in the polymerization process of resin-modified hard emulsion to form a large amount of low glass transition temperature active segments in the presence of a large amount of initiators, and subsequent hard monomers can continue to react on the active segments. At the reaction temperature, the seed segments can drive the high TG segments to move, so that hydrophilic macromolecules can move to the surface of latex particles with less resistance, and the hydrophilic resin part can be more in contact with the water phase. Therefore, the final refractive index of the latex particles is closer to that of water, and the resin part of the formed latex particle structure can be closer to the outer layer and will not be coated in the inner layer of the latex particles during the reaction process, thereby obtaining a high-transparency resin-modified acrylic hard emulsion. The modified acrylic hard emulsion of the present invention has higher transparency while ensuring high hardness. DETAILED DESCRIPTION

[0053] 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.

[0054] The sources of the raw materials used in the following examples are shown in Table 1. Unless otherwise specified, the other raw materials are common commercially available raw materials:

[0055] Main raw materials and sources

[0056]

[0057] The Fox Tg (degrees Celsius) of each combined monomer in the embodiment of the present invention is calculated according to the following formula:

[0058]

[0059] Where W 1 , W 2 ,…W n They refer to the mass fractions of monomers 1, 2, ...n in the combined monomers, respectively, and Tg 1 , Tg 2 ,…Tg n These respectively refer to the glass transition temperatures of homopolymers of monomers 1, 2, ... n in the monomer combination.

[0060] Embodiment 1:

[0061] The high-permeability resin modified acrylic hard emulsion active chain seed polymerization monomer A is designed to have a Tg of 0°C, which accounts for 10% of the mass of the total reaction monomers. The initiator is ammonium persulfate. The mass of the initiator added during the seed preparation process is 5% of the mass of the polymerization monomer A. The Tg value of the high Tg polymer part is 100°C.

[0062] The alkali-soluble acrylic resin selected is BASF678: weight average molecular weight 8500, Tg 109°C, acid value 215 mgKOH / g;

[0063] The dissolution process of alkali-soluble acrylic resin is as follows:

[0064] Add 60g of alkali-soluble acrylic resin into the reactor, then add 200g of deionized water and start stirring, raise the temperature in the reactor to 80-85°C. After the temperature is reached, add 16g of ammonia water into the reactor through a peristaltic pump, and keep it warm for 1-3h to ensure that the alkali-soluble acrylic resin is completely dissolved;

[0065] Reaction monomer preparation:

[0066] Polymerization monomer A: 4.7 g methyl methacrylate MMA and 5.3 g butyl acrylate BA

[0067] Polymerization monomer B 90g Styrene ST

[0068] 1) Dissolve 0.5g of initiator ammonium persulfate in 20g of water to obtain polymerization monomer B and add initiator dropwise; dissolve 0.5g of initiator ammonium persulfate in 10g of water to obtain polymerization monomer A seed initiator;

[0069] 2) After the alkali-soluble acrylic resin is completely dissolved, 4.7g of methyl methacrylate MMA and 5.3g of butyl acrylate B are added to the reactor and stirred for 10-15min, and the temperature is maintained at 80-85°C. After the stirring is completed, the polymerization monomer A seed initiator is added to initiate the reaction and the temperature is kept for 0.5-2h;

[0070] 3) After the active chain segment is formed, 90 g of styrene monomer is added dropwise, and the polymerization monomer B initiator is added dropwise into the reactor through a peristaltic pump synchronously, the addition time is 2 h-5 h, and the temperature is kept for 10-60 min after the addition is completed;

[0071] 4) After the insulation is completed, the system is cooled to below 50°C, and an appropriate amount of ammonia water is added to adjust the pH to between 7 and 9. After stirring for 30 minutes, the material is discharged to obtain a high-transmittance resin-modified acrylic hard emulsion.

[0072] High-transmittance resin-modified acrylic hard emulsion, with a solid content of 40wt%, a polymer hydrated particle size of 72nm, and a pH of 8.5.

[0073] Embodiment 2:

[0074] The high-permeability resin modified acrylic hard emulsion active chain seed polymerization monomer A is designed to have a Tg of 0°C, which accounts for 10% of the mass of the total reaction monomers. The initiator is potassium persulfate. During the seed preparation process, the mass of the initiator added is 50% of the mass of the polymerization monomer A. The Tg value of the high Tg polymer part is 100°C.

[0075] The alkali-soluble acrylic resin selected is BASF678: weight average molecular weight 8500, Tg 109°C, acid value 215 mgKOH / g;

[0076] The dissolution process of alkali-soluble acrylic resin is as follows:

[0077] Add 60g of alkali-soluble acrylic resin into the reactor, then add 180g of deionized water and start stirring, raise the temperature in the reactor to 80-85°C. After the temperature is reached, add 16g of ammonia water into the reactor through a peristaltic pump, and keep it warm for 1-3h to ensure that the alkali-soluble acrylic resin is completely dissolved;

[0078] Reaction monomer preparation:

[0079] Polymerization monomer A 4.7g Methyl methacrylate MMA 5.3g Butyl acrylate BA

[0080] Polymerization monomer B 90g Styrene ST

[0081] 1) dissolving 0.5 g of initiator potassium persulfate in 20 g of water to obtain polymerization monomer B initiator; dissolving 5 g of initiator potassium persulfate in 30 g of water to obtain polymerization monomer A initiator;

[0082] 2) After the alkali-soluble acrylic resin is completely dissolved, add the polymerization monomer A into the reaction kettle and stir for 10-15 minutes, keeping the temperature at 80-85°C. After stirring, add the polymerization monomer A initiator to initiate the reaction and keep the temperature for 0.5-2 hours;

[0083] 3) After the active segment is formed, the polymerization monomer B and the initiator are added to the reactor synchronously through a peristaltic pump for 2h-5h, and the temperature is kept for 10-60min after the addition is completed;

[0084] 4) After the insulation is completed, the system is cooled to below 50°C, and an appropriate amount of ammonia water is added to adjust the pH to between 7 and 9. After stirring for 30 minutes, the material is discharged to obtain a high-transmittance resin-modified acrylic hard emulsion.

[0085] High-transmittance resin-modified acrylic hard emulsion, with a solid content of 40wt%, a polymer hydrated particle size of 62nm, and a pH of 8.5.

[0086] Embodiment 3:

[0087] The Tg of the active chain seed monomer A in the preparation of the high-permeability resin modified acrylic hard emulsion is designed to be 0°C, and its mass proportion in the total reaction monomers is 10%. The mass of the initiator added during the seed preparation process is 20% of the mass of the polymerization monomer A, and the Tg of the high Tg polymer part is 100°C.

[0088] The alkali-soluble acrylic resin selected is BASF678: weight average molecular weight 8500, Tg 109°C, acid value 215 mgKOH / g;

[0089] The dissolution process of alkali-soluble acrylic resin is as follows:

[0090] Add 60g of alkali-soluble acrylic resin into the reactor, then add 180g of deionized water and start stirring, raise the temperature in the reactor to 80-85°C. After the temperature is reached, add 16g of ammonia water into the reactor through a peristaltic pump, and keep it warm for 1-3h to ensure that the alkali-soluble acrylic resin is completely dissolved;

[0091] Reaction monomer preparation:

[0092] Polymerization monomer A 4.7g Methyl methacrylate MMA 5.3g Butyl acrylate BA

[0093] Polymerization monomer B 90g Styrene ST

[0094] 1) dissolving 0.5 g of initiator ammonium persulfate in 20 g of water to obtain polymerization monomer B initiator; dissolving 2 g of initiator ammonium persulfate in 10 g of water to obtain polymerization monomer A initiator;

[0095] 2) After the alkali-soluble acrylic resin is completely dissolved, add the polymerization monomer A into the reaction kettle and stir for 10-15 minutes, keeping the temperature at 80-85°C. After stirring, add the polymerization monomer A initiator to initiate the reaction and keep the temperature for 0.5-2 hours;

[0096] 3) After the active chain segment is formed, the polymerization monomer B and the initiator are added to the reactor synchronously through a peristaltic pump for 2h-5h, and the temperature is kept for 10-60min after the addition is completed;

[0097] 4) After the insulation is completed, the system is cooled to below 50°C, and an appropriate amount of ammonia water is added to adjust the pH to between 7 and 9. After stirring for 30 minutes, the material is discharged to obtain a high-transmittance resin-modified acrylic hard emulsion.

[0098] High-transmittance resin-modified acrylic hard emulsion, with a solid content of 40wt%, a polymer hydrated particle size of 66nm, and a pH of 8.5.

[0099] Embodiment 4:

[0100] The active chain seed monomer A for preparing the high-permeability resin modified acrylic hard emulsion is designed with a Tg of 10°C, which accounts for 20% of the mass of the total reaction monomers. The mass of the initiator added during the seed preparation is 20% of the mass of the polymerization monomer A, and the high Tg polymer part has a Tg of 80°C.

[0101] The alkali-soluble acrylic resin selected is BASF678: weight average molecular weight 8500, Tg 109°C, acid value 215 mgKOH / g;

[0102] The dissolution process of alkali-soluble acrylic resin is as follows:

[0103] Add 60g of alkali-soluble acrylic resin into the reactor, then add 180g of deionized water and start stirring, raise the temperature in the reactor to 80-85°C. After the temperature is reached, add 16g of ammonia water into the reactor through a peristaltic pump, and keep it warm for 1-3h to ensure that the alkali-soluble acrylic resin is completely dissolved;

[0104] Reaction monomer preparation:

[0105] Polymerization monomer A 5.4g methyl methacrylate MMA 4.6g butyl acrylate BA

[0106] Polymerization monomer B 83g Styrene ST 7g Butyl acrylate BA

[0107] 1) dissolving 0.5 g of initiator sodium persulfate in 20 g of water to obtain polymerization monomer B initiator; dissolving 2 g of initiator sodium persulfate in 30 g of water to obtain polymerization monomer A initiator;

[0108] 2) After the alkali-soluble acrylic resin is completely dissolved, add the polymerization monomer A into the reaction kettle and stir for 10-15 minutes, keeping the temperature at 80-85°C. After stirring, add the polymerization monomer A initiator to initiate the reaction and keep the temperature for 0.5-2 hours;

[0109] 3) After the active segment is formed, the polymerization monomer B and the initiator are added to the reactor synchronously through a peristaltic pump for 2h-5h, and the temperature is kept for 10-60min after the addition is completed;

[0110] 4) After the insulation is completed, the system is cooled to below 50°C, and an appropriate amount of ammonia water is added to adjust the pH to between 7 and 9. After stirring for 30 minutes, the material is discharged to obtain a high-transmittance resin-modified acrylic hard emulsion.

[0111] Highly transparent resin modified acrylic hard emulsion, solid content of 40wt%, polymer hydrated particle size of 63nm, pH 8.6

[0112] Embodiment 5:

[0113] The active chain seed monomer A for preparing the high-permeability resin modified acrylic hard emulsion is designed with a Tg of -10°C, which accounts for 10% of the mass of the total reaction monomers. The mass of the initiator added during the seed preparation process is 20% of the mass of the polymerization monomer A, and the high Tg polymer part has a Tg of 105°C.

[0114] The alkali-soluble acrylic resin selected is BASF678: weight average molecular weight 8500, Tg 109°C, acid value 215 mgKOH / g;

[0115] The alkali-soluble acrylic resin accounts for 50% of the total mass ratio;

[0116] The dissolution process of alkali-soluble acrylic resin is as follows:

[0117] Add 80g of alkali-soluble acrylic resin into the reactor, then add 200g of deionized water and start stirring, and raise the temperature in the reactor to 80-85°C. After the temperature is reached, add 20g of ammonia water into the reactor through a peristaltic pump and keep it warm for 1-3h to ensure that the alkali-soluble acrylic resin is completely dissolved;

[0118] Reaction monomer preparation:

[0119] Polymerization monomer A 3.2g methyl methacrylate MMA 4.8g butyl acrylate BA;

[0120] Polymerization monomer B 72g methyl methacrylate MMA;

[0121] 1) dissolving 0.5 g of initiator ammonium persulfate in 20 g of water to obtain polymerization monomer B initiator; dissolving 1.6 g of initiator ammonium persulfate in 10 g of water to obtain polymerization monomer A initiator;

[0122] 2) After the alkali-soluble acrylic resin is completely dissolved, add the polymerized monomer A into the reaction kettle and stir for 10-15 minutes, keeping the temperature at 80-85°C. After stirring, add the initiator at the bottom of the kettle to initiate the reaction, and keep the temperature for 0.5-2 hours;

[0123] 3) After the active segment is formed, the polymerization monomer B and the initiator are added to the reactor synchronously through a peristaltic pump for 2h-5h, and the temperature is kept for 10-60min after the addition is completed;

[0124] 4) After the insulation is completed, the system is cooled to below 50°C, and an appropriate amount of ammonia water is added to adjust the pH to between 7 and 9. After stirring for 30 minutes, the material is discharged to obtain a high-transmittance resin-modified acrylic hard emulsion.

[0125] High permeability resin modified acrylic hard emulsion, solid content is 40wt%, polymer hydrate particle size is 64nm, pH is 8.2

[0126] Embodiment 6:

[0127] The active chain seed polymerization monomer A for preparing the high-transmittance resin modified acrylic hard emulsion is designed to have a Tg of 39°C, which accounts for 10% of the mass of the total reaction monomers. The mass of the initiator added during the seed preparation process is 20% of the mass of the polymerization monomer A, and the high Tg polymer part has a Tg of 100°C.

[0128] The alkali-soluble acrylic resin selected is Soluryl820: weight average molecular weight 8000, Tg 118°C, acid value 205 mgKOH / g;

[0129] The dissolution process of alkali-soluble acrylic resin is as follows:

[0130] Add 60g of alkali-soluble acrylic resin into the reactor, then add 200g of deionized water and start stirring, raise the temperature in the reactor to 80-85°C. After the temperature is reached, add 16g of ammonia water into the reactor through a peristaltic pump, and keep it warm for 1-3h to ensure that the alkali-soluble acrylic resin is completely dissolved;

[0131] Reaction monomer preparation:

[0132] Polymerization monomer A 7.1g methyl methacrylate MMA 2.9g butyl acrylate BA;

[0133] Polymerization monomer B 90g styrene ST;

[0134] 1) dissolving 0.5 g of initiator ammonium persulfate in 20 g of water to obtain polymerization monomer B initiator; dissolving 2 g of initiator ammonium persulfate in 10 g of water to obtain polymerization monomer A initiator;

[0135] 2) After the alkali-soluble acrylic resin is completely dissolved, add the polymerization monomer A into the reaction kettle and stir for 10-15 minutes, keeping the temperature at 80-85°C. After stirring, add the polymerization monomer A initiator to initiate the reaction and keep the temperature for 0.5-2 hours;

[0136] 3) After the active segment is formed, the polymerization monomer B and the initiator are added to the reactor synchronously through a peristaltic pump for 2h-5h, and the temperature is kept for 10-60min after the addition is completed;

[0137] 4) After the insulation is completed, the system is cooled to below 50°C, and an appropriate amount of ammonia water is added to adjust the pH to between 7 and 9. After stirring for 30 minutes, the material is discharged to obtain a high-transmittance resin-modified acrylic hard emulsion.

[0138] Highly transparent resin modified acrylic hard emulsion, solid content of 40wt%, polymer hydrated particle size of 75nm, pH 8.6

[0139] Embodiment 7:

[0140] The Tg of the active chain seed monomer A in the preparation of the high-permeability resin modified acrylic hard emulsion is designed to be 0°C, and its mass proportion in the total reaction monomers is 1%. The mass of the initiator added during the seed preparation process is 20% of the mass of the polymerization monomer A, and the Tg of the high Tg polymer part is 100°C.

[0141] The alkali-soluble acrylic resin selected is BASF678: weight average molecular weight 8500, Tg 109°C, acid value 215 mgKOH / g;

[0142] The dissolution process of alkali-soluble acrylic resin is as follows:

[0143] Add 60g of alkali-soluble acrylic resin into the reactor, then add 200g of deionized water and start stirring, raise the temperature in the reactor to 80-85°C. After the temperature is reached, add 16g of ammonia water into the reactor through a peristaltic pump, and keep it warm for 1-3h to ensure that the alkali-soluble acrylic resin is completely dissolved;

[0144] Reaction monomer preparation:

[0145] Polymerization monomer A: 0.47 g methyl methacrylate MMA; 0.53 g butyl acrylate BA;

[0146] Polymerized monomer B 99g styrene ST;

[0147] 1) dissolving 0.5 g of initiator ammonium persulfate in 20 g of water to obtain polymerization monomer B initiator; dissolving 0.2 g of initiator ammonium persulfate in 10 g of water to obtain polymerization monomer A initiator;

[0148] 2) After the alkali-soluble acrylic resin is completely dissolved, add the seed monomer polymer A into the reactor and stir for 10-15 minutes, keeping the temperature at 80-85°C. After stirring, add the polymer A initiator to initiate the reaction and keep the temperature for 0.5-2 hours;

[0149] 3) After the active segment is formed, the polymerization monomer B and the initiator are added to the reactor synchronously through a peristaltic pump for 2h-5h, and the temperature is kept for 10-60min after the addition is completed;

[0150] 4) After the insulation is completed, the system is cooled to below 50°C, and an appropriate amount of ammonia water is added to adjust the pH to between 7 and 9. After stirring for 30 minutes, the material is discharged to obtain a high-transmittance resin-modified acrylic hard emulsion.

[0151] Highly transparent resin modified acrylic hard emulsion, solid content of 40wt%, polymer hydrated particle size of 85nm, pH 8.6

[0152] Embodiment 8:

[0153] The Tg of the active chain seed monomer A in the preparation of the high-permeability resin modified acrylic hard emulsion is designed to be 0°C, and its mass proportion in the total reaction monomers is 20%. The mass of the initiator added during the seed preparation process is 20% of the mass of the polymerization monomer A, and the Tg of the high Tg polymer part is 70°C.

[0154] The alkali-soluble acrylic resin selected is BASF678: weight average molecular weight 8500, Tg 109°C, acid value 215 mgKOH / g;

[0155] The dissolution process of alkali-soluble acrylic resin is as follows:

[0156] Add 60g of alkali-soluble acrylic resin into the reactor, then add 180g of deionized water and start stirring, raise the temperature in the reactor to 80-85°C. After the temperature is reached, add 16g of ammonia water into the reactor through a peristaltic pump, and keep it warm for 1-3h to ensure that the alkali-soluble acrylic resin is completely dissolved;

[0157] Reaction monomer preparation:

[0158] Polymerization monomer A 9.4g methyl methacrylate MMA 10.6g butyl acrylate BA;

[0159] Polymerization monomer B 70g styrene ST 10g butyl acrylate BA;

[0160] 1) dissolving 0.5 g of initiator ammonium persulfate in 20 g of water to obtain polymerization monomer B initiator; dissolving 4 g of initiator ammonium persulfate in 30 g of water to obtain polymerization monomer A initiator;

[0161] 2) After the alkali-soluble acrylic resin is completely dissolved, add the seed monomer polymer monomer A into the reactor and stir for 10-15 minutes, keeping the temperature at 80-85°C. After stirring, add the initiator at the bottom of the reactor to initiate the reaction and keep the temperature for 0.5-2 hours;

[0162] 3) After the active segment is formed, the polymerization monomer B and the initiator are added to the reactor synchronously through a peristaltic pump for 2h-5h, and the temperature is kept for 10-60min after the addition is completed;

[0163] 4) After the insulation is completed, the system is cooled to below 50°C, and an appropriate amount of ammonia water is added to adjust the pH to between 7 and 9. After stirring for 30 minutes, the material is discharged to obtain a high-transmittance resin-modified acrylic hard emulsion.

[0164] High permeability resin modified acrylic hard emulsion, solid content is 40wt%, polymer hydrate particle size is 60nm, pH is 8.3

[0165] Comparative Example 1:

[0166] The Tg of the active chain seed monomer A in the preparation of the high-transmittance resin modified acrylic hard emulsion is designed to be 0°C, and its mass proportion in the total reaction monomers is 10%. The mass of the initiator added during the seed preparation process is 4% of the mass of the polymerization monomer A, and the Tg of the high Tg polymer part is 100°C.

[0167] The alkali-soluble acrylic resin selected is BASF678: weight average molecular weight 8500, Tg 109°C, acid value 215 mgKOH / g;

[0168] The dissolution process of alkali-soluble acrylic resin is as follows:

[0169] Add 60g of alkali-soluble acrylic resin into the reactor, then add 200g of deionized water and start stirring, raise the temperature in the reactor to 80-85°C. After the temperature is reached, add 16g of ammonia water into the reactor through a peristaltic pump, and keep it warm for 1-3h to ensure that the alkali-soluble acrylic resin is completely dissolved;

[0170] Reaction monomer preparation:

[0171] Polymerization monomer A 4.7g Methyl methacrylate MMA 5.3g Butyl acrylate BA

[0172] Polymerization monomer B 90g Styrene ST

[0173] 1) dissolving 0.5 g of initiator ammonium persulfate in 20 g of water to obtain polymerization monomer B initiator; dissolving 0.4 g of initiator ammonium persulfate in 10 g of water to obtain seed polymerization monomer A initiator;

[0174] 2) After the alkali-soluble acrylic resin is completely dissolved, add the polymerized monomer A into the reaction kettle and stir for 10-15 minutes, keeping the temperature at 80-85°C. After stirring, add the initiator at the bottom of the kettle to initiate the reaction, and keep the temperature for 0.5-2 hours;

[0175] 3) After the active chain segment is formed, the polymerization monomer B and the initiator are added to the reactor synchronously through a peristaltic pump for 2h-5h, and the temperature is kept for 10-60min after the addition is completed;

[0176] 4) After the insulation is completed, the system is cooled to below 50°C, and an appropriate amount of ammonia water is added to adjust the pH to between 7 and 9. After stirring for 30 minutes, the material is discharged to obtain a high-transmittance resin-modified acrylic hard emulsion.

[0177] High-transmittance resin-modified acrylic hard emulsion, with a solid content of 40wt%, a polymer hydrated particle size of 90nm, and a pH of 8.5.

[0178] Comparative Example 2:

[0179] The Tg of the active chain seed monomer A in the preparation of the high-permeability resin modified acrylic hard emulsion is designed to be 0°C, and its mass proportion in the total reaction monomers is 10%. The mass of the initiator added during the seed preparation process is 55% of the mass of the polymerization monomer A, and the Tg of the high Tg polymer part is 100°C.

[0180] The alkali-soluble acrylic resin selected is BASF678: weight average molecular weight 8500, Tg 109°C, acid value 215 mgKOH / g;

[0181] The dissolution process of alkali-soluble acrylic resin is as follows:

[0182] Add 60g of alkali-soluble acrylic resin into the reactor, then add 180g of deionized water and start stirring, raise the temperature in the reactor to 80-85°C. After the temperature is reached, add 16g of ammonia water into the reactor through a peristaltic pump, and keep it warm for 1-3h to ensure that the alkali-soluble acrylic resin is completely dissolved;

[0183] Reaction monomer preparation:

[0184] Polymerization monomer A 4.7g Methyl methacrylate MMA 5.3g Butyl acrylate BA

[0185] Polymerization monomer B 90g Styrene ST

[0186] 1) dissolving 0.5 g of initiator ammonium persulfate in 20 g of water to obtain polymerization monomer B initiator; dissolving 5.5 g of initiator ammonium persulfate in 30 g of water to obtain seed polymerization monomer A initiator;

[0187] 2) After the alkali-soluble acrylic resin is completely dissolved, add the polymerization monomer A into the reaction kettle and stir for 10-15 minutes, keeping the temperature at 80-85°C. After stirring, add the polymerization monomer A initiator to initiate the reaction and keep the temperature for 0.5-2 hours;

[0188] 3) After the active chain segment is formed, the polymerization monomer B and the initiator are added to the reactor synchronously through a peristaltic pump for 2h-5h, and the temperature is kept for 10-60min after the addition is completed;

[0189] 4) After the insulation is completed, the system is cooled to below 50°C, and an appropriate amount of ammonia water is added to adjust the pH to between 7 and 9. After stirring for 30 minutes, the material is discharged to obtain a high-transmittance resin-modified acrylic hard emulsion.

[0190] High-transmittance resin-modified acrylic hard emulsion, with a solid content of 40wt%, a polymer hydrated particle size of 60nm, and a pH of 8.1.

[0191] Comparative Example 3:

[0192] The active segment seed of the high-transmittance resin modified acrylic hard emulsion is designed to have a Tg of 47°C, which accounts for 10% of the mass of the total reaction monomers. During the seed preparation process, the mass of the initiator added is 20% of the mass of the polymerized monomer A, and the high Tg polymer part has a Tg of 100°C.

[0193] The alkali-soluble acrylic resin selected is BASF678: weight average molecular weight 8500, Tg 109°C, acid value 215 mgKOH / g;

[0194] The dissolution process of alkali-soluble acrylic resin is as follows:

[0195] Add 60g of alkali-soluble acrylic resin into the reactor, then add 200g of deionized water and start stirring, raise the temperature in the reactor to 80-85°C. After the temperature is reached, add 16g of ammonia water into the reactor through a peristaltic pump, and keep it warm for 1-3h to ensure that the alkali-soluble acrylic resin is completely dissolved;

[0196] Reaction monomer preparation:

[0197] Polymerization monomer A 7.5g methyl methacrylate MMA 2.5g butyl acrylate BA

[0198] Polymerization monomer B 90g Styrene ST

[0199] 1) dissolving 0.5 g of initiator ammonium persulfate in 20 g of water to obtain polymerization monomer B initiator; dissolving 2 g of initiator ammonium persulfate in 10 g of water to obtain polymerization monomer A initiator;

[0200] 2) After the alkali-soluble acrylic resin is completely dissolved, add the polymerization monomer A into the reaction kettle and stir for 10-15 minutes, keeping the temperature at 80-85°C. After stirring, add the polymerization monomer A initiator to initiate the reaction and keep the temperature for 0.5-2 hours;

[0201] 3) After the active segment is formed, the polymerization monomer B and the initiator are added to the reactor synchronously through a peristaltic pump for 2h-5h, and the temperature is kept for 10-60min after the addition is completed;

[0202] 4) After the insulation is completed, the system is cooled to below 50°C, and an appropriate amount of ammonia water is added to adjust the pH to between 7 and 9. After stirring for 30 minutes, the material is discharged to obtain a high-transmittance resin-modified acrylic hard emulsion.

[0203] Highly transparent resin modified acrylic hard emulsion, solid content is 40wt%, polymer hydrate particle size is 83nm, pH is 8.4

[0204] Comparative Example 4:

[0205] The high-transmittance resin modified acrylic hard emulsion active segment seed is designed to account for 0 mass proportion of the total reaction monomers, the mass of the initiator added during the seed preparation is 0% of the mass of the polymerized monomer A, and the high Tg polymer part has a Tg of 100°C.

[0206] The alkali-soluble acrylic resin selected is BASF678: weight average molecular weight 8500, Tg 109°C, acid value 215 mgKOH / g;

[0207] The dissolution process of alkali-soluble acrylic resin is as follows:

[0208] Add 60g of alkali-soluble acrylic resin into the reactor, then add 210g of deionized water and start stirring, and raise the temperature in the reactor to 80-85°C. After the temperature is reached, add 16g of ammonia water into the reactor through a peristaltic pump and keep it warm for 1-3h to ensure that the alkali-soluble acrylic resin is completely dissolved;

[0209] Reaction monomer preparation:

[0210] Polymerization monomer A None;

[0211] Polymerization monomer B 100g styrene ST;

[0212] 1) dissolving 0.5 g of initiator ammonium persulfate in 20 g of water to obtain polymerization monomer B initiator;

[0213] 2) After the alkali-soluble acrylic resin is completely dissolved, the polymerization monomer B and the initiator are added into the reactor synchronously through a peristaltic pump for 2h-5h. After the addition is completed, the temperature is kept for 10-60min;

[0214] 4) After the insulation is completed, the system is cooled to below 50°C, and an appropriate amount of ammonia water is added to adjust the pH to between 7 and 9. After stirring for 30 minutes, the material is discharged to obtain a high-transmittance resin-modified acrylic hard emulsion.

[0215] High permeability resin modified acrylic hard emulsion, solid content is 40wt%, polymer hydrated particle size is 100nm, pH is 8.6

[0216] Comparative Example 5:

[0217] The active segment seed of the high-transmittance resin modified acrylic hard emulsion is designed with a Tg of 0°C, which accounts for 30% of the mass of the total reaction monomers. The mass of the initiator added during the seed preparation is 20% of the mass of the polymerized monomer A, and the high Tg polymer part has a Tg of 100°C.

[0218] The alkali-soluble acrylic resin selected is BASF678: weight average molecular weight 8500, Tg 109°C, acid value 215 mgKOH / g;

[0219] The dissolution process of alkali-soluble acrylic resin is as follows:

[0220] Add 60g of alkali-soluble acrylic resin into the reactor, then add 180g of deionized water and start stirring, raise the temperature in the reactor to 80-85°C. After the temperature is reached, add 16g of ammonia water into the reactor through a peristaltic pump, and keep it warm for 1-3h to ensure that the alkali-soluble acrylic resin is completely dissolved;

[0221] Reaction monomer preparation:

[0222] Polymer monomer A 14.1g Methyl methacrylate MMA 15.9g Butyl acrylate BA

[0223] Polymerization monomer B 70g Styrene ST

[0224] 1) dissolving 0.5 g of initiator ammonium persulfate in 20 g of water to obtain polymerization monomer B initiator; dissolving 6 g of initiator ammonium persulfate in 30 g of water to obtain polymerization monomer A initiator;

[0225] 2) After the alkali-soluble acrylic resin is completely dissolved, add the seed polymerization monomer A into the reactor and stir for 10-15 minutes, keeping the temperature at 80-85°C. After stirring, add the polymerization monomer A initiator to initiate the reaction and keep the temperature for 0.5-2 hours;

[0226] 3) After the active chain segment is formed, the polymerization monomer B and the initiator are added to the reactor synchronously through a peristaltic pump for 2h-5h, and the temperature is kept for 10-60min after the addition is completed;

[0227] 4) After the insulation is completed, the system is cooled to below 50°C, and an appropriate amount of ammonia water is added to adjust the pH to between 7 and 9. After stirring for 30 minutes, the material is discharged to obtain a high-transmittance resin-modified acrylic hard emulsion.

[0228] High permeability resin modified acrylic hard emulsion, solid content is 40wt%, polymer hydrate particle size is 60nm, pH is 8.4

[0229] Comparative Example 6:

[0230] The active segment seed of the high-transmittance resin modified acrylic hard emulsion is designed to have a Tg of 0°C, which accounts for 10% of the mass of the total reaction monomers. The mass of the initiator added during the seed preparation is 20% of the mass of the polymerized monomer A, and the high Tg polymer part has a Tg of 63°C.

[0231] The alkali-soluble acrylic resin selected is BASF678: weight average molecular weight 8500, Tg 109°C, acid value 215 mgKOH / g;

[0232] The dissolution process of alkali-soluble acrylic resin is as follows:

[0233] Add 60g of alkali-soluble acrylic resin into the reactor, then add 200g of deionized water and start stirring, raise the temperature in the reactor to 80-85°C. After the temperature is reached, add 16g of ammonia water into the reactor through a peristaltic pump, and keep it warm for 1-3h to ensure that the alkali-soluble acrylic resin is completely dissolved;

[0234] Reaction monomer preparation:

[0235] Polymerization monomer A 4.7g Methyl methacrylate MMA 5.3g Butyl acrylate BA

[0236] Polymerization monomer B 76g Styrene ST 14g Butyl acrylate

[0237] 1) dissolving 0.5 g of initiator ammonium persulfate in 20 g of water to obtain polymerization monomer B initiator; dissolving 2 g of initiator ammonium persulfate in 10 g of water to obtain polymerization monomer A initiator;

[0238] 2) After the alkali-soluble acrylic resin is completely dissolved, add the seed polymerization monomer A into the reactor and stir for 10-15 minutes, keeping the temperature at 80-85°C. After stirring, add the polymerization monomer A initiator to initiate the reaction and keep the temperature for 0.5-2 hours;

[0239] 3) After the active chain segment is formed, the polymerization monomer B and the initiator are added to the reactor synchronously through a peristaltic pump for 2h-5h, and the temperature is kept for 10-60min after the addition is completed;

[0240] 4) After the insulation is completed, the system is cooled to below 50°C, and an appropriate amount of ammonia water is added to adjust the pH to between 7 and 9. After stirring for 30 minutes, the material is discharged to obtain a high-transmittance resin-modified acrylic hard emulsion.

[0241] High-transmittance resin-modified acrylic hard emulsion, with a solid content of 40wt%, a polymer hydrated particle size of 73nm, and a pH of 8.4.

[0242] See the table below for specific instance conditions.

[0243]

[0244]

[0245] The performance testing method adopted by the present invention is as follows:

[0246] Temperature resistance: reference standard GB / T13217.8-91, GB / T13217.1-91;

[0247] Transparency: Apply the prepared varnish on the special paper for ink with a 10um wire rod, dry it at 100℃ for 10 seconds, and observe the transparency of the paint film;

[0248] Wear resistance: Refer to "GB1768-(79)88 Paint film wear resistance test method"

[0249] The test results of the varnish properties prepared by the resin-modified acrylic emulsions prepared in Examples 1-8 and Comparative Examples 1-5 are shown in the table

[0250] Performance Test Results

[0251] Temperature resistance Wear-resistant Transparency Example 1 +++ +++ ++ Example 2 ++ ++ +++ Example 3 +++ +++ +++ Example 4 ++ ++ +++ Example 5 +++ +++ ++ Example 6 +++ +++ ++ Example 7 ++ ++ +++ Example 8 ++ ++ +++ Comparative Example 1 +++ +++ + Comparative Example 2 * * +++ Comparative Example 3 +++ +++ * Comparative Example 4 +++ +++ * Comparative Example 5 * * +++ Comparative Example 6 * * +++

[0252] Note: "+": average; "++": good; "+++": very good. *: poor. Finally, it should be noted that the above embodiments are only used to describe the preferred implementation methods of the present invention, rather than to limit the protection scope of the present invention. Although the present invention is described in detail with reference to the preferred embodiments, those skilled in the art should understand that various modifications and improvements made by modifying or equivalently replacing the technical solution of the present invention should fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing a modified acrylic hard emulsion, It is characterized in that The following steps are involved: S1: adding the alkali-soluble resin into the alkaline aqueous solution to completely dissolve the alkali-soluble resin; S2: Preparation of active segments: The temperature in the reactor is maintained at 60-95°C, and polymerization monomer A is added to the reactor. After the polymerization monomer A is fully mixed in the reactor, initiator A is added to initiate the reaction, and the temperature is kept to allow the seeds to form stably; S3: After the reaction in step S2 is completed, add the polymerization monomer B and the initiator B, and keep the temperature after the addition is completed; S4: Cooling down to room temperature and discharging the material to obtain the modified acrylic hard emulsion.

2. The preparation method according to claim 1, It is characterized in that The weight average molecular weight Mw of the alkali-soluble resin is 2000-20000, preferably 6000-15000; Preferably, the acid value of the alkali-soluble resin is 100-250 mgKOH / g, preferably 150-240 mgKOH / g; Preferably, the glass transition temperature Tg value of the alkali-soluble resin is 30-120°C, preferably 70-100°C; Preferably, the alkali-soluble resin is a resin or polymer that can dissolve more than 10 grams in one liter of alkaline aqueous solution at room temperature, preferably an alkali-soluble acrylic resin, more preferably an alkali-soluble styrene-maleic anhydride resin, an alkali-soluble styrene-acrylic resin, an alkali-soluble (meth)acrylate-acrylic resin; Preferably, in step S1, the alkaline aqueous solution is prepared by adding an alkaline substance into water, and the alkaline substance is an alkali metal hydroxide or ammonia water.

3. The preparation method according to claim 1 or 2, It is characterized in that In step S2, the amount of initiator A accounts for more than 5% and less than 50% of the mass of polymerization monomer A; Preferably, the monomer initiation method in step S2 is thermally initiated emulsion polymerization or redox emulsion polymerization; Preferably, the initiator A includes but is not limited to a thermal initiator and / or a redox initiator; Preferably, the thermal initiator is selected from one or more of persulfate, tert-butyl hydroperoxide, and hydrogen peroxide; more preferably, the persulfate is selected from ammonium sulfate, sodium persulfate, or potassium persulfate; Preferably, the redox initiator generally comprises an oxidant and a reductant; the oxidant is selected from one or more of ammonium persulfate, sodium persulfate, potassium persulfate, tert-butyl hydroperoxide, and hydrogen peroxide, preferably one or more of ammonium persulfate, sodium persulfate, and potassium persulfate; Preferably, the reducing agent is selected from one or more of alkali metal sulfites, alkali metal bisulfites, alkali metal metabisulfites, formaldehyde bisulfite, alkali metal salts of aliphatic sulfinic acids, alkali metal hydrogen sulfide, acetone bisulfite, ascorbic acid, and isoascorbic acid.

4. The preparation method according to any one of claims 1 to 3, It is characterized in that The polymerizable monomer A is selected from a mixture of (meth)acrylate monomers, non-acidic (meth)propylene monomers and styrene monomers; Preferably, the styrene monomer includes but is not limited to at least one of styrene or α-methylstyrene; Preferably, the (meth)acrylate includes but is not limited to at least one of methyl methacrylate, cyclohexyl methacrylate, ethyl methacrylate, butyl methacrylate, isooctyl methacrylate, glycidyl methacrylate, hydroxyethyl methacrylate, allyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl acrylate, lauryl acrylate, lauryl methacrylate, octadecyl acrylate, and octadecyl methacrylate; Preferably, the non-acidic (meth) acrylic monomers include but are not limited to diacetone acrylamide, acrylamide, and hydroxymethyl acrylamide; Preferably, in step S2, the total glass transition temperature Tg of the added polymerized monomer A is calculated according to the FOX formula, and the Tg value is less than or equal to 40°C, preferably -10-10°C.

5. The preparation method according to any one of claims 1 to 4, It is characterized in that In step S3, the polymerizable monomer B includes a (meth)acrylate monomer, a non-acidic (meth)propylene monomer, and a styrene monomer; Preferably, the styrene monomer includes but is not limited to at least one of styrene or α-methylstyrene; Preferably, the (meth) acrylic acid ester monomer includes but is not limited to methyl methacrylate, cyclohexyl methacrylate, ethyl methacrylate, butyl methacrylate, isooctyl methacrylate, glycidyl methacrylate, hydroxyethyl methacrylate, allyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl acrylate, lauryl acrylate, lauryl methacrylate, octadecyl acrylate, at least one of octadecyl methacrylate; Preferably, the non-acidic (meth) acrylic monomers include but are not limited to diacetone acrylamide, acrylamide, and hydroxymethyl acrylamide.

6. The preparation method according to any one of claims 1 to 5, It is characterized in that The polymerizable monomer A accounts for more than 1% and less than 20% of the total monomer mass; Preferably, in step S3, according to the calculation of FOX formula, the total glass transition temperature Tg of the added polymerized monomer B is greater than or equal to 65°C, preferably 80-100°C.

7. The preparation method according to any one of claims 1 to 6, It is characterized in that The polymerizable monomers A and B are directly added to the reactor or a pre-emulsion is prepared using an emulsifier and then added to the reactor, wherein the emulsifier is a non-reactive anionic and / or non-reactive non-ionic surfactant; Preferably, the non-reactive anionic surfactant includes, but is not limited to, one or more of alkyl, aryl or alkylaryl sulfates, sulfonates or phosphates, alkyl sulfonic acids, sulfosuccinates, fatty alcohol ether sulfates and fatty acids; Preferably, the non-reactive nonionic surfactant includes, but is not limited to, alcohol or phenol ethoxylates, such as polyoxyethylene alkylphenyl ether, More preferably, the non-reactive nonionic surfactant includes, but is not limited to, one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, fatty alcohol polyoxyethylene ethers and salts thereof, and fatty alcohol ether phosphates and salts thereof; Preferably, the surfactant further comprises a polymerizable surfactant containing at least one ethylenically unsaturated functional group, and the polymerizable surfactant includes but is not limited to allyl polyoxyalkylene ether sulfate, allyl alkyl succinate sulfonate, allyl ether hydroxypropane sulfonate, polyoxyethylene styrenated phenyl ether sulfate; Preferably, the total amount of the emulsifier is 0.2-3% of the total mass of the polymerized monomer A and the polymerized monomer B, preferably 0.2-0.5%; More preferably, the polymerized monomer A and the polymerized monomer B are added in the absence of an emulsifier.

8. The preparation method according to any one of claims 1 to 7, It is characterized in that Taking the total mass of polymerized monomer A, polymerized monomer B and alkali-soluble solid resin as 100%, the mass content of the alkali-soluble solid resin is 10-90%. Preferably, the polymerization temperature of the entire polymerization process is 50-100° C., preferably 70-90° C. The total polymerization time is 2-8 hours, preferably 3-6 hours; Preferably, in step S3, the amount of initiator B accounts for more than 0.1% of the mass of polymerized monomer B, preferably 0.1-1%; Preferably, the initiator B includes but is not limited to a thermal initiator and / or a redox initiator; Preferably, the thermal initiator is selected from one or more of persulfate, tert-butyl hydroperoxide, and hydrogen peroxide; more preferably, the persulfate is selected from ammonium sulfate, sodium persulfate, or potassium persulfate; Preferably, the redox initiator generally comprises an oxidant and a reductant; the oxidant is selected from one or more of ammonium persulfate, sodium persulfate, potassium persulfate, tert-butyl hydroperoxide, and hydrogen peroxide, preferably one or more of ammonium persulfate, sodium persulfate, and potassium persulfate; Preferably, the reducing agent is selected from one or more of alkali metal sulfites, alkali metal bisulfites, alkali metal metabisulfites, formaldehyde bisulfite, alkali metal salts of aliphatic sulfinic acids, alkali metal hydrogen sulfide, acetone bisulfite, ascorbic acid, and isoascorbic acid.

9. The preparation method according to any one of claims 1 to 7, It is characterized in that In step S4, optionally, after the insulation is completed, an initiator is added to consume the unreacted monomers; Preferably, in step S4, a base may be added to adjust the pH to 7-9.

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