Water-soluble acrylic solid resin, acrylic emulsion and preparation methods of water-soluble acrylic solid resin and acrylic emulsion

Abstract

The invention discloses a water-soluble acrylic solid resin, an acrylic emulsion and preparation methods of the water-soluble acrylic solid resin and the acrylic emulsion, and the water-soluble acrylic solid resin comprises the following components in parts by weight: 30-55 parts of a solvent; 10 to 25 parts of styrene; 5 to 25 parts of alpha-methyl styrene; 10 to 23 parts of acrylic acid; 0 to 15 parts of other monomers; 0.5 to 3 parts of diacetone acrylamide; 0.5 to 2 parts of a polyether monomer; 0.05 to 1.5 parts of an initiator; the initiator is a peroxide initiator. According to the invention, diacetone acrylamide and polyether monomers are successfully introduced into a molecular chain of the water-soluble acrylic solid resin, so that the Tg of the water-soluble acrylic solid resin is reduced, the flexibility of the water-soluble acrylic solid resin is improved, the rear section of the water-soluble acrylic solid resin can be cross-linked, and when the water-soluble acrylic solid resin is used for preparing an acrylic emulsion, the alcohol solubility resistance of the emulsion and the adhesive force to a non-absorbent substrate can be remarkably improved; the problems caused by introduction of diacetone acrylamide and polyether monomers during emulsion synthesis are avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of emulsion production, and in particular relates to a water-soluble acrylic acid solid resin, an acrylic acid emulsion and a preparation method thereof. Background Art

[0002] Water-soluble acrylic solid resins have been maturely used in the market as a binder for water-based inks and a protective glue for synthesizing styrene-acrylic emulsions. Compared with the natural rosin used in the early days, water-soluble acrylic solid resins have better wettability on pigments, and the stability, color development, drying speed and other properties of the synthesized inks have been greatly improved. In emulsion synthesis, compared with styrene-acrylic emulsions synthesized using emulsifiers, water-soluble acrylic solid resins can replace emulsifiers as protective glue for emulsions. The synthesized emulsions have better stability and transferability, higher gloss, and simpler synthesis processes.

[0003] At present, the preparation of water-soluble acrylic solid resin mainly uses acrylic acid, styrene, and α-methylstyrene as the main monomers, introduces some functional monomers, and uses initiators for polymerization synthesis. The synthesis methods are mainly divided into solution method and continuous bulk method. The continuous bulk method requires high temperature and high pressure to produce water-soluble acrylic solid resin. The production conditions are relatively harsh, the production equipment and process are complex, and the conversion rate is limited. However, solvents are not used, and the material can be directly discharged and formed, which is more environmentally friendly. The production temperature of solution-based water-soluble acrylic solid resin is relatively low. Since high temperature and high pressure are not required, the production equipment and process are relatively simple. However, because the polymerization reaction is carried out in a solvent, high temperature and negative pressure are required for devolatilization after the reaction, which makes the product prone to solvent residues and unstable quality.

[0004] At present, the water-soluble acrylic solid resins used as protective adhesives in the market for synthesizing latexes generally have high Tg (glass transition temperature), which is above 110°C. The amount added when synthesizing latexes with such solid resins generally accounts for 8% to 20% of the total amount. The latex particles of this type of latex are more like a core-shell structure. The hard solid resin in the shell of the latex particles has an impact on the adhesion of the substrate during the film formation process, and will significantly affect the adhesion of the latex to the substrate. It is usually necessary to introduce cross-linking monomers or functional monomers when synthesizing the latex to improve its adhesion and other properties. A considerable number of cross-linking agents and functional monomers are very water-soluble and can only participate in the polymerization reaction to a limited extent during the synthesis of the emulsion, which may cause problems such as incomplete emulsion reaction, excessive residue, whitening, and even demulsification during the reaction. Therefore, whether it is possible to introduce cross-linking monomers and functional monomers when synthesizing water-soluble acrylic solid resins is a question worth exploring. Summary of the invention

[0005] In view of the defects and application requirements of existing water-soluble acrylic solid resins, the present invention provides a water-soluble acrylic solid resin and a preparation method thereof, which can significantly improve the alcohol solubility resistance and adhesion to non-absorbent substrates of acrylic emulsions when used to prepare acrylic emulsions.

[0006] In order to achieve the above object, the first aspect of the present invention provides a water-soluble acrylic solid resin, which comprises the following components in parts by weight:

[0007] Solvent: 30-55 parts;

[0008] Styrene: 10-25 parts;

[0009] α-Methylstyrene: 5-25 parts;

[0010] Acrylic acid: 10-23 parts;

[0011] Other monomers: 0-15 parts;

[0012] Diacetone acrylamide: 0.5-3 parts;

[0013] Polyether monomer: 0.5-2 parts;

[0014] Initiator: 0.05-1.5 parts;

[0015] The initiator is a peroxide initiator.

[0016] Preferably, the Tg of the water-soluble acrylic solid resin is 50-110°C.

[0017] Preferably, the polyether monomer is selected from one or more combinations of the following substances:

[0018] 2-ethoxyethyl acrylate, 2-ethoxyethyl methacrylate and methoxy polyethylene glycol acrylate.

[0019] Preferably, the solvent is selected from one or more combinations of the following substances:

[0020] Toluene, xylene, diethylene glycol methyl ether, diethylene glycol ethyl ether, ethylene glycol monobutyl ether, diethylene glycol dimethyl ether and dipropylene glycol dimethyl ether;

[0021] Preferably, the other monomers are selected from one or more combinations of the following substances:

[0022] Methacrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isooctyl acrylate, maleic acid, diethyl maleate, dibutyl maleate and dioctyl maleate;

[0023] Preferably, the initiator is selected from one or more combinations of the following substances:

[0024] Dibenzoyl peroxide, dimethylbenzoyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxyisobutyrate, di-tert-butyl peroxycyclohexane, tert-amyl peroxyacetate, and tert-butyl peroxyisobutyrate.

[0025] On the other hand, the present application also provides a method for preparing the above-mentioned water-soluble acrylic solid resin, comprising the following steps:

[0026] S1. Heat part of the solvent to 100°C to 150°C;

[0027] S2. Take the remaining part of the solvent and mix it with other substances, then slowly add the mixture to the heated solvent under 0.3MpaPa ~ 2MPa conditions, and then keep the pressure and temperature to react for 1h ~ 3h;

[0028] S3. After the reaction, continue heating to 150℃~200℃, and devolatilize under negative pressure for 1h~3h. After the devolatilization is completed, pass inert gas to pressurize and discharge the material.

[0029] Preferably, the amount of the solvent in step S1 is 3 to 10 parts;

[0030] Preferably, the mixture in step S2 is added for 1 h to 4 h.

[0031] Preferably, the devolatilization pressure in step S3 is -40 kPa to -90 kPa, and the discharge pressure is 0.2 to 1 MPa.

[0032] On the other hand, the present application also provides an acrylic emulsion using the above-mentioned water-soluble acrylic solid resin, comprising the following components in percentage by weight:

[0033] Acrylic monomer: 20-40%;

[0034] 8% to 20% of the water-soluble acrylic solid resin as described above;

[0035] Alkali: 3% to 5%;

[0036] Emulsifier: 0.1%~2%;

[0037] Adipic acid dihydrazide: 0.1% ~ 1.5%;

[0038] Initiator: 0.1%~0.5%;

[0039] Water: Balance.

[0040] Preferably, the acrylic monomer is a combination of a soft monomer and a hard monomer; the soft monomer is selected from at least one of methyl acrylate, ethyl acrylate, butyl methacrylate, butyl acrylate, isooctyl methacrylate, isooctyl acrylate, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, hydroxybutyl methacrylate or isobornyl acrylate; the hard monomer is selected from at least one of methyl methacrylate, isobornyl methacrylate or ethyl methacrylate;

[0041] Preferably, the copolymer of the acrylic monomer combination has a Tg of -30°C to 0°C;

[0042] Preferably, the base is selected from at least one of aqueous ammonia, sodium hydroxide or monoethanolamine;

[0043] Preferably, the emulsifier is at least one selected from anionic emulsifiers and nonionic emulsifiers;

[0044] Further preferably, the anionic emulsifier is selected from at least one of sodium dodecyl sulfate, sodium dodecyl sulfonate or sodium dodecylbenzene sulfonate; the nonionic emulsifier is fatty alcohol polyoxyethylene ether;

[0045] Preferably, the initiator is selected from at least one of potassium persulfate, sodium persulfate or ammonium persulfate.

[0046] On the other hand, the present application also provides a method for preparing the acrylic emulsion as described above, comprising the following steps:

[0047] S1. Mix part of water, water-soluble acrylic solid resin and alkali, heat to 80 ℃ ~ 90 ℃ to dissolve; mix acrylic monomer, emulsifier and another part of water and stir to pre-emulsify;

[0048] S2. After the water-soluble acrylic solid resin is completely dissolved, add the initiator and the remaining water solution, and then slowly add the pre-emulsified monomer in step S1, the addition time is 1h~3h, and then keep the reaction warm for 1h~2h;

[0049] S3. Cool down to below 40°C, add adipic acid dihydrazide and disperse evenly, then discharge.

[0050] The present invention successfully introduces diacetone acrylamide and polyether monomers into the molecular chain of water-soluble acrylic solid resin, thereby reducing its Tg, improving its flexibility, and enabling post-crosslinking. When preparing acrylic emulsion, the alcohol solubility resistance of the emulsion and its adhesion to non-absorbent substrates can be significantly improved, thereby avoiding the problems existing in the introduction of diacetone acrylamide and polyether monomers during emulsion synthesis.

[0051] At the same time, the present application also optimizes the synthesis process of acrylic solid resin by introducing diacetone acrylamide and polyether monomers, reduces the occurrence of high-temperature side reactions, improves the reaction activity and reactivity rate, and successfully prepares water-soluble acrylic solid resin and acrylic emulsion with performance that meets the requirements. DETAILED DESCRIPTION

[0052] The present application provides a water-soluble acrylic solid resin, which comprises the following components in parts by weight:

[0053] Solvent: 30-55 parts;

[0054] Styrene: 10-25 parts;

[0055] α-Methylstyrene: 5-25 parts;

[0056] Acrylic acid: 10-23 parts;

[0057] Other monomers: 0-15 parts;

[0058] Diacetone acrylamide: 0.5-3 parts;

[0059] Polyether monomer: 0.5-2 parts;

[0060] Initiator: 0.05-1.5 parts;

[0061] The initiator is a peroxide initiator.

[0062] Conventional water-soluble acrylic solid resins generally only use hard monomers, which results in a harder latex shell, affecting the demulsification, accumulation and cross-linking of latex particles during the subsequent emulsion film-forming process, further affecting the leveling and adhesion to the printing substrate.

[0063] On this basis, the present application successfully introduces diacetone acrylamide and polyether monomers into the molecular chain of water-soluble acrylic solid resin, wherein the introduction of diacetone acrylamide into the shell layer of latex particles can make it easier for latex particles to crosslink during the film-forming process of the emulsion, achieve higher crosslinking density and crosslinking efficiency, and thus improve the adhesion of the emulsion. Introducing a small amount of polyether monomers on the basis of not changing the resin structure (i.e., not adversely affecting the compatibility and stability with ink) can significantly improve the flexibility of the molecular chain and reduce Tg. The Tg of the water-soluble acrylic solid resin obtained in the present application can be reduced to below 110°C, making it easier for latex particles to demulsify, making the emulsion have a better leveling effect on the printing substrate, and can be more closely attached to the printing substrate, while crosslinking is more sufficient, further improving the adhesion of the resin; in addition, the ether bonds in the polyether monomers have good compatibility with alcohol solvents, and can also provide a certain alcohol solubility for the emulsion, reducing the risk of demulsification when adding alcohol solvents to the emulsion.

[0064] Therefore, further, the present application synthesizes diacetone acrylamide and polyether monomers into a water-soluble acrylic solid resin in advance, and uses the synthesized acrylic emulsion to effectively improve the adhesion of such products, and also avoids the problems of incomplete emulsion reaction, excessive residue, whitening, and even demulsification caused by introducing a large amount of diacetone acrylamide and polyether monomers during emulsion synthesis.

[0065] However, it has been found through experiments that diacetone acrylamide and polyether monomers are prone to produce side reactions at high temperatures when synthesizing water-soluble acrylic solid resins, and the polymerization reaction needs to be controlled in a relatively low temperature environment. Therefore, the present application uses an initiator with a relatively low initiation temperature and a relatively low reaction temperature. In addition, α-methylstyrene has a relatively poor reactivity. After the introduction of diacetone acrylamide and polyether monomers, in a low-temperature environment where the system polymerization rate is relatively low, it is necessary to extend the reaction time, increase the reaction pressure, and increase the insulation time to improve its reactivity and reactivity ratio, so that the polymer molecular segments obtained by polymerization are more uniform and the molecular weight distribution is narrower. The specific process is described below.

[0066] Preferably, the polyether monomer is selected from one or more combinations of the following substances:

[0067] 2-Ethoxyethyl acrylate, 2-ethoxyethyl methacrylate, methoxy polyethylene glycol acrylate.

[0068] Preferably, the solvent is selected from one or more combinations of the following substances:

[0069] Toluene, xylene, diethylene glycol methyl ether, diethylene glycol ethyl ether, ethylene glycol monobutyl ether, diethylene glycol dimethyl ether and dipropylene glycol dimethyl ether.

[0070] Preferably, the other monomers are selected from one or more combinations of the following substances:

[0071] Methacrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isooctyl acrylate, maleic acid, diethyl maleate, dibutyl maleate and dioctyl maleate;

[0072] Preferably, the initiator is selected from one or more combinations of the following substances:

[0073] Dibenzoyl peroxide, dimethylbenzoyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxyisobutyrate, di-tert-butyl peroxycyclohexane, tert-amyl peroxyacetate, and tert-butyl peroxyisobutyrate.

[0074] The present application also provides a method for preparing the above-mentioned water-soluble acrylic acid solid resin, comprising the following steps:

[0075] S1. Heat part of the solvent to 100°C to 150°C;

[0076] S2. Take the remaining part of the solvent and mix it with other substances, then slowly add the mixture to the heated solvent under 0.3MPa~2MPa, and then keep the pressure and temperature to react for 1h~3h;

[0077] S3. After the reaction, continue to heat to 150℃~200℃, and devolatilize under negative pressure for 1h~3h. After the devolatilization is completed, pass inert gas to pressurize and discharge the material. Inert gas can be nitrogen, etc.

[0078] Preferably, the amount of solvent used in step S1 is 3 to 10 parts.

[0079] Preferably, the mixture is added in step S2 for 1 h to 4 h.

[0080] Preferably, the devolatilization pressure is -40 kPa to -90 kPa, and the discharge pressure is 0.2 to 1 MPa.

[0081] Since diacetone acrylamide and polyether monomers are introduced in this application, the reaction is relatively complicated, and the production conditions of the conventional continuous bulk method cannot meet the production. Therefore, this application adopts a semi-continuous solution method for production. By lowering the reaction temperature, reducing the occurrence of side reactions, and correspondingly increasing the reaction pressure and time to increase the reaction rate, the obtained polymer molecular segments are uniform, the molecular weight distribution is narrow, and the product uniformity is good.

[0082] On the other hand, the present application also provides an acrylic emulsion synthesized using the above-mentioned water-soluble acrylic solid resin, which includes the following components in percentage by weight:

[0083] Acrylic monomer: 20% to 40%;

[0084] 8% to 20% of the water-soluble acrylic solid resin as described above;

[0085] Alkali: 3% to 5%;

[0086] Emulsifier: 0.1%~2%;

[0087] Adipic acid dihydrazide: 0.1% ~ 1.5%;

[0088] Initiator: 0.1%~0.5%;

[0089] Water: Balance.

[0090] As described above, after using the water-soluble acrylic solid resin provided by the present application, it is no longer necessary to introduce crosslinking monomers and functional monomers into the emulsion, and the emulsion reaction is more complete without problems such as excessive residue, whitening, or even demulsification. Moreover, it has a better leveling effect and adhesion to the printing substrate.

[0091] Preferably, the acrylic monomer is a combination of a soft monomer and a hard monomer; the soft monomer is selected from at least one of methyl acrylate, ethyl acrylate, butyl methacrylate, butyl acrylate, isooctyl methacrylate, isooctyl acrylate, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, hydroxybutyl methacrylate or isobornyl acrylate; and the hard monomer is selected from at least one of methyl methacrylate, isobornyl methacrylate or ethyl methacrylate.

[0092] Preferably, the Tg of the copolymer of the acrylic monomer combination is -30°C to 0°C.

[0093] Preferably, the base is selected from at least one of aqueous ammonia, sodium hydroxide or monoethanolamine.

[0094] Preferably, the emulsifier is at least one selected from anionic emulsifiers and nonionic emulsifiers.

[0095] More preferably, the anionic emulsifier is selected from at least one of sodium dodecyl sulfate, sodium dodecyl sulfonate or sodium dodecylbenzene sulfonate; and the nonionic emulsifier is fatty alcohol polyoxyethylene ether.

[0096] Preferably, the initiator is selected from at least one of potassium persulfate, sodium persulfate or ammonium persulfate.

[0097] The present application also provides a method for preparing the acrylic emulsion, comprising the following steps:

[0098] S1. Mix a portion of water (preferably 75% to 90% of the total amount of water), a water-soluble acrylic solid resin and a base, and heat to 80°C to 90°C to dissolve; mix and stir an acrylic monomer, an emulsifier and another portion of water (preferably 5% to 20% of the total amount of water) to pre-emulsify;

[0099] S2. After the water-soluble acrylic solid resin is completely dissolved, add the initiator and the remaining water (2% to 5%) solution, and then slowly add the pre-emulsified monomer in step S1 for 1h to 3h, and then keep the reaction warm for 1h to 2h;

[0100] S3. Cool down to below 40°C, add adipic acid dihydrazide and disperse evenly, then discharge.

[0101] Example 1

[0102] A water-soluble acrylic solid resin, in which the proportions of the components are as follows in parts by weight:

[0103]

[0104]

[0105] The preparation process of the above-mentioned water-soluble acrylic acid solid resin is divided into the following steps:

[0106] (1) Add 8 parts of solvent into the reaction kettle at one time and heat it to 120°C.

[0107] (2) Slowly drop the mixture of all monomers, the remaining solvents, and the initiator using a high-level tank. The mixture is added at a pressure of 0.7 MPa for 2.5 hours. After the addition is completed, the pressure and temperature are maintained for 1.5 hours.

[0108] (3) Heating to 195°C, performing vacuum devolatilization for 1.5 hours, and then passing nitrogen gas to pressurize the material for discharge after the devolatilization is completed.

[0109] The prepared water-soluble acrylic resin has a weight average molecular weight of 9000-10000, an acid value of 220-240 mgKOH / g, and a Tg of 95-100°C.

[0110] Example 2

[0111] A water-soluble acrylic solid resin, in which the proportions of the components are as follows in parts by weight:

[0112]

[0113] The preparation process of the above-mentioned water-soluble acrylic acid solid resin is divided into the following steps:

[0114] (1) Add 5 parts of solvent into the reaction kettle at one time and heat it to 130°C.

[0115] (2) Slowly drop the mixture of all monomers, the remaining solvents, and the initiator using a high-level tank. The mixture is added at a pressure of 1 MPa for 3 hours. After the addition is completed, the pressure and temperature are maintained for 2 hours.

[0116] (3) Heating to 180°C, performing vacuum devolatilization for 1.5 hours, and then passing nitrogen gas to pressurize the material for discharge after the devolatilization is completed.

[0117] The prepared water-soluble acrylic resin has a weight average molecular weight of 7000-8500, an acid value of 215-225 KOH / g, and a Tg of 100-105°C.

[0118] Example 3

[0119] An acrylic emulsion, the total amount of raw materials is 100 parts by weight and the proportions of each component are as follows:

[0120] 11 parts of water-soluble acrylic acid solid resin prepared in Example 1

[0121] 8 parts of butyl acrylate

[0122] 9 parts of 2-ethylhexyl acrylate

[0123] 13 parts of methyl methacrylate

[0124] 2 parts of Hydroxyethyl Acrylate

[0125] 4 parts ammonia

[0126] Fatty alcohol polyoxyethylene ether (EO value: 9) 0.6 parts

[0127] 0.2 parts of adipic acid dihydrazide

[0128] Potassium persulfate 0.4 parts

[0129] Water balance.

[0130] The Tg of the copolymer of the acrylic monomer combination is -15 to -10°C.

[0131] The preparation process of the above acrylic emulsion is divided into the following steps:

[0132] (1) Add 80% water, water-soluble acrylic solid resin and alkali into a reaction kettle at once according to the above components, heat to 83°C to dissolve, add monomer, emulsifier and 18% water into a high-level tank and stir for pre-emulsification.

[0133] (2) After the resin is completely dissolved, add the initiator and 2% water solution into the reactor at one time, and slowly add the pre-emulsified monomer dropwise using a high-level tank for 2 hours. After the addition is completed, keep the temperature for 1 hour.

[0134] (3) Cool down to 30°C, add adipic acid dihydrazide and disperse evenly, then discharge.

[0135] Example 4

[0136] A water-based acrylic emulsion, the total amount of raw materials is 100 parts by weight and the proportions of each component are as follows:

[0137] 14 parts of water-soluble acrylic acid solid resin prepared in Example 2

[0138] 5 parts of butyl methacrylate

[0139] 12 parts of 2-ethylhexyl acrylate

[0140] 13 parts of methyl methacrylate

[0141] 2 parts of ethyl acrylate

[0142] 1 part Hydroxypropyl Methacrylate

[0143] 5 parts ammonia

[0144] 0.8 parts of sodium dodecylbenzene sulfonate

[0145] 0.5 parts of adipic acid dihydrazide

[0146] Potassium persulfate 0.4 parts

[0147] Water Remaining

[0148] The Tg of the copolymer of the acrylic monomer combination is -20 to -15°C.

[0149] The preparation process of the above-mentioned aqueous acrylic emulsion is divided into the following steps:

[0150] (1) Add 75% water, water-soluble acrylic solid resin and alkali into a reaction kettle at once according to the above components, heat to 85°C to dissolve, add monomer, emulsifier and 20% water into a high-level tank and stir for pre-emulsification.

[0151] (2) After the resin is completely dissolved, add the initiator and 5% water solution into the reactor at one time, and slowly add the pre-emulsified monomer dropwise using a high-level tank for 2.5 hours. After the addition is completed, keep the temperature for 1.5 hours.

[0152] (3) Cool down to 30°C, add adipic acid dihydrazide and disperse evenly, then discharge.

[0153] The emulsion prepared by using conventional 0663 water-based acrylic solid resin (the resin does not introduce diacetone acrylamide and polyether monomers) produced by Guangdong Tianlong Ink Company to replace the water-soluble acrylic solid resin in Example 3 was used as a comparative example.

[0154] The emulsions prepared in the above Examples 3, 4 and the comparative example were respectively compounded with the quick-drying water-based color pastes TLAY998 black, TLAY6 blue, TLAY23 red and ethanol (80% concentration) produced by Guangdong Tianlong Ink Co., Ltd. in a weight ratio of 2:2:1 to prepare a high-adhesion surface printing ink, and the performance test was performed on it. The results are as follows:

[0155] Ink viscosity stability: After the high adhesion surface printing ink is left to stand for a long time, its viscosity change is tested. The test is carried out using a GB / T13217.4 coated No. 4 cup. The change results are shown in Table 1.

[0156] Table 1 Changes in static viscosity of surface printing ink

[0157]

[0158] Adhesion: The high adhesion surface printing ink was printed on different substrates and its adhesion was tested using the tape method. The results are shown in Table 2.

[0159] Table 2: Surface printing ink adhesion test

[0160]

[0161] As can be seen from the above two tables, the high-adhesion surface printing ink prepared by the emulsions synthesized in Examples 3 and 4 using the water-soluble acrylic solid resin provided by the present invention has good alcohol solubility and stability, and has strong adhesion to various substrates.

[0162] Although preferred embodiments of the present invention have been described, additional changes and modifications may be made to these embodiments by those skilled in the art once the basic inventive concepts are known. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention. Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A water-soluble acrylic solid resin, characterized in that: By weight, it includes the following components: Solvent: 30-55 parts; Styrene: 10-25 parts; α-Methylstyrene: 5-25 parts; Acrylic acid: 10-23 parts; Other monomers: 0-15 parts; Diacetone acrylamide: 0.5-3 parts; Polyether monomer: 0.5-2 parts; Initiator: 0.05-1.5 parts; The initiator is a peroxide initiator.

2. The water-soluble acrylic solid resin according to claim 1, characterized in that The Tg of the water-soluble acrylic solid resin is 50°C to 110°C.

3. The water-soluble acrylic solid resin according to claim 1, characterized in that The polyether monomer is selected from one or more combinations of the following substances: 2-ethoxyethyl acrylate, 2-ethoxyethyl methacrylate and methoxy polyethylene glycol acrylate.

4. The water-soluble acrylic solid resin according to claim 1, characterized in that The solvent is selected from one or more combinations of the following substances: Toluene, xylene, diethylene glycol methyl ether, diethylene glycol ethyl ether, ethylene glycol monobutyl ether, diethylene glycol dimethyl ether and dipropylene glycol dimethyl ether; Preferably, the other monomers are selected from one or more combinations of the following substances: Methacrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isooctyl acrylate, maleic acid, diethyl maleate, dibutyl maleate and dioctyl maleate; Preferably, the initiator is selected from one or more combinations of the following substances: Dibenzoyl peroxide, dimethylbenzoyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxyisobutyrate, di-tert-butyl peroxycyclohexane, tert-amyl peroxyacetate, and tert-butyl peroxyisobutyrate.

5. The method for preparing a water-soluble acrylic solid resin according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Heat part of the solvent to 100°C to 150°C; S2. Take the remaining part of the solvent and mix it with other substances, then slowly add the mixture to the heated solvent under 0.3MpaPa ~ 2MPa conditions, and then keep the pressure and temperature to react for 1h ~ 3h; S3. After the reaction, continue heating to 150℃~200℃, and devolatilize under negative pressure for 1h~3h. After the devolatilization is completed, pass inert gas to pressurize and discharge the material.

6. The method for preparing a water-soluble acrylic acid solid resin according to claim 5, wherein: The amount of the solvent in step S1 is 3 to 10 parts; Preferably, the mixture in step S2 is added for 1 h to 4 h.

7. The method for preparing a water-soluble acrylic acid solid resin according to claim 5, wherein: The devolatilization pressure in step S3 is -40 kPa to -90 kPa, and the discharge pressure is 0.2 to 1 MPa.

8. An acrylic emulsion, characterized in that: Includes the following components in percentage by mass: Acrylic monomer: 20% to 40%; 8% to 20% of the water-soluble acrylic solid resin according to any one of claims 1 to 4; Alkali: 3% to 5%; Emulsifier: 0.1%~2%; Adipic acid dihydrazide: 0.1% ~ 1.5%; Initiator: 0.1%~0.5%; Water: Balance.

9. The acrylic emulsion according to claim 8, characterized in that The acrylic monomer is a combination of a soft monomer and a hard monomer; the soft monomer is selected from at least one of methyl acrylate, ethyl acrylate, butyl methacrylate, butyl acrylate, isooctyl methacrylate, isooctyl acrylate, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, hydroxybutyl methacrylate or isobornyl acrylate; the hard monomer is selected from at least one of methyl methacrylate, isobornyl methacrylate or ethyl methacrylate; Preferably, the copolymer of the acrylic monomer combination has a Tg of -30°C to 0°C; Preferably, the base is selected from at least one of aqueous ammonia, sodium hydroxide or monoethanolamine; Preferably, the emulsifier is at least one selected from anionic emulsifiers and nonionic emulsifiers; Further preferably, the anionic emulsifier is selected from at least one of sodium dodecyl sulfate, sodium dodecyl sulfonate or sodium dodecylbenzene sulfonate; the nonionic emulsifier is fatty alcohol polyoxyethylene ether; Preferably, the initiator is selected from at least one of potassium persulfate, sodium persulfate or ammonium persulfate.

10. The method for preparing an acrylic emulsion according to any one of claims 8 to 9, characterized in that: The following steps are involved: S1. Mix part of water, water-soluble acrylic solid resin and alkali, heat to 80 ℃ ~ 90 ℃ to dissolve; mix acrylic monomer, emulsifier and another part of water and stir to pre-emulsify; S2. After the water-soluble acrylic solid resin is completely dissolved, add the initiator and the remaining water solution, and then slowly add the pre-emulsified monomer in step S1, the addition time is 1h~3h, and then keep the reaction warm for 1h~2h; S3. Cool down to below 40°C, add adipic acid dihydrazide and disperse evenly, then discharge.

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