Modified asparagus resin and emulsion

Abstract

The invention provides a modified asparagus resin and an emulsion, and relates to the technical field of hydrophilic polymer synthesis. The modified aspartic resin is obtained by reacting a hydrophilic isocyanate compound with hydrophobic aspartic ester resin; the molar ratio of an NH group in the hydrophobic aspartic ester resin to an NCO group in the hydrophilic isocyanate compound is not less than 1.2 and less than 3. The modified asparagus resin can be self-emulsified and dispersed in water to form a stable emulsion, and a cured coating is high in glossiness, good in water resistance and good in adhesiveness.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrophilic polymer synthesis and relates to a modified asparagus resin and an emulsion. Background Art

[0002] Water-based coatings are an important development direction for coatings and a requirement for coatings development in response to economic and social development. Aspartame polyurea coatings feature high solids content and rapid curing speed, resulting in coatings with excellent corrosion resistance and weathering resistance. The development of water-based aspartame polyurea coatings is also an important development direction for this field. Water-based aspartame polyurea coatings are generally prepared by self-emulsifying a self-emulsifying hydrophilic aspartic acid ester resin in water to form an emulsion, which is then mixed with an isocyanate curing agent. The self-emulsifying hydrophilic aspartic acid ester resin has a significant impact on the performance of water-based aspartic acid polyurea coatings. Several methods for preparing hydrophilic aspartic acid ester resins have been reported in the prior art. For example, Chinese patent CN116285616A discloses reacting a modified polyaspartic acid ester with hexamethylene diisocyanate to form an isocyanate-terminated polyaspartic acid ester polyurea oligomer, which is then chain-extended with isophorone diisocyanate and 2,2-dimethylolpropionic acid, and neutralized with triethylamine to obtain a hydrophilic polyaspartic acid ester resin. However, the hydrophilicity of the hydrophilic aspartic acid ester resin obtained by the above method is relatively high, resulting in problems such as insufficient water resistance and poor corrosion resistance of the water-based aspartic acid polyurea coating.

[0003] Therefore, it is necessary to further study and improve the preparation method of hydrophilic aspartic acid ester resin. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a modified asparagus resin and emulsion.

[0005] The technical solutions of the present invention are as follows:

[0006] A modified aspartic acid resin is obtained by reacting a hydrophilic isocyanate compound with a hydrophobic aspartic acid ester resin;

[0007] The molar ratio of the NH groups in the hydrophobic aspartic acid ester resin to the NCO groups in the hydrophilic isocyanate compound is not less than 1.2 and less than 3.

[0008] Preferably, the hydrophilic isocyanate compound contains a chemically bonded hydrophilic structure, and the content of NCO groups in the hydrophilic isocyanate compound is not less than 5 wt %.

[0009] More preferably, the hydrophilic structure is selected from one or a combination of two or more of a polyether segment, a carboxylate, a sulfonate, a phosphate, a quaternary ammonium salt and a sulfate.

[0010] More preferably, the structure of the polyether segment is as shown in the following formula (1):

[0011] -(CH2CH2O) a (CH2CHCH3O) b R1(1)

[0012] Wherein, a≥5, b≥0, ab≥5, and R1 is selected from C1-C4 alkyl.

[0013] More preferably, the hydrophilic isocyanate compound is obtained by reacting a polyisocyanate monomer with a hydrophilic compound;

[0014] The hydrophilic compound contains 1-2 active hydrogen atoms in its structure, and the remaining structure of the hydrophilic compound after losing the active hydrogen atoms contains the hydrophilic structure.

[0015] More preferably, the molecular weight of the polyisocyanate monomer is no more than 300, and the structure of the polyisocyanate monomer contains 2-3 NCO groups.

[0016] Preferably, the structure of the hydrophobic aspartic acid ester resin is shown in the following formula (2):

[0017]

[0018] wherein X is selected from a nonionic m-valent organic group having a number average molecular weight of 50-5000 and no more than 2 heteroatoms and being inert to reaction with isocyanate groups at 100° C., and R2 and R3 are independently selected from C1-C8 hydrocarbon groups, with m=2-4.

[0019] Preferably, the molar ratio of the NH groups in the hydrophobic aspartic acid ester resin to the NCO groups in the hydrophilic isocyanate compound is 1.5-2.8:1.

[0020] An emulsion is obtained by dispersing raw material components containing the modified asparagus resin described in any one of the above technical solutions in water.

[0021] Preferably, the solid content of the emulsion is 10-60 wt%.

[0022] The beneficial effects of the present invention are:

[0023] (1) The present invention obtains a modified aspartic acid resin having good hydrophilicity by reacting a hydrophilic isocyanate compound with a hydrophobic aspartic acid ester resin and controlling the molar ratio of the NCO group to the NH group, which can be self-emulsified and dispersed in water to obtain an emulsion with good stability.

[0024] (2) The modified asparagus resin of the present invention has good self-emulsification properties while also avoiding excessive hydrophilicity. The obtained emulsion is combined with an isocyanate curing agent and the cured film layer has good water resistance and good gloss properties. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is further illustrated and described below through specific implementation methods.

[0026] In order to solve the problem that the hydrophilic preference of hydrophilic aspartic acid ester resins in the prior art leads to insufficient water resistance of emulsions or water-based coatings, the present invention proposes a modified aspartic acid resin obtained by reacting a hydrophilic isocyanate compound and a hydrophobic aspartic acid ester resin;

[0027] The molar ratio of the NH groups in the hydrophobic aspartic acid ester resin to the NCO groups in the hydrophilic isocyanate compound is not less than 1.2 and less than 3.

[0028] To realize the hydrophilicity of aspartic acid ester resin, a hydrophilic structure must be introduced into its structure. The structure, type, quantity, etc. of the hydrophilic structure introduced will affect the hydrophilicity of the hydrophilic aspartic acid ester resin and the performance of the subsequent emulsion and water-based paint prepared, such as stability, water resistance, glossiness, etc. In the present invention, a method of reacting a hydrophilic isocyanate compound containing a hydrophilic structure with a hydrophobic aspartic acid ester resin is adopted to introduce a hydrophilic structure into the aspartic acid ester resin structure, thereby improving the hydrophilicity of the aspartic acid ester resin. The modified aspartic acid ester resin obtained has self-emulsifying properties, and because the hydrophilic structure is not introduced much, some properties after the emulsion or water-based paint is cured, such as water resistance, adhesion, etc., are improved. In addition, by adjusting the molar ratio of the NH group and the NCO group within a certain range, the hydrophilicity of the modified aspartic acid ester resin obtained is relatively suitable. If the molar ratio of NH groups to NCO groups is too high, such as a molar ratio of 3.5:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, etc., too few hydrophilic structures are introduced, and the hydrophilicity of the modified asparagine resin is insufficient. Although it can be emulsified and dispersed in water to form an emulsion or aqueous dispersion, the stability may be insufficient, and the glossiness of the film layer after the obtained water-based coating is cured is not high enough; if the molar ratio of NH groups to NCO groups is too low, such as a molar ratio of 1, 1.1, etc., too many hydrophilic structures are introduced, the hydrophilicity of the modified asparagine resin is too high, the water resistance of the film layer obtained after the emulsion is cured is insufficient, and the NH groups on the modified asparagine resin will be too few, which is not conducive to subsequent curing.

[0029] For example, the molar ratio of the NH groups in the hydrophobic aspartic acid ester resin to the NCO groups in the hydrophilic isocyanate compound can be any value among 1.2, 1.3, 1.5, 1.6, 1.8, 2, 2.2, 2.3, 2.5, 2.7, 2.8, 2.9, etc., without particular limitation. Furthermore, the molar ratio of the NH groups in the hydrophobic aspartic acid ester resin to the NCO groups in the hydrophilic isocyanate compound can be 1.2-2.8:1, or further, the molar ratio can be 1.2-2.5:1.

[0030] In some embodiments, the hydrophilic isocyanate compound contains a chemically bonded hydrophilic structure, and the NCO group content in the hydrophilic isocyanate compound is not less than 5wt%. If the NCO content in the hydrophilic isocyanate compound is low, the NCO activity is low, which is not conducive to the reaction with the hydrophobic aspartic acid ester resin. For example, the NCO group content in the hydrophilic isocyanate compound can be any value among 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 7.5wt%, 8wt%, 8.5wt%, 9wt%, 9.5wt%, 10wt%, 10.5wt%, 11wt%, 11.5wt%, 12wt%, 12.5wt%, 13wt%, 13.5wt%, 14wt%, 14.5wt%, 15wt%, etc., without special limitation. The chemically bonded hydrophilic structures can be selected from one or a combination of two or more of the following: polyether segments, carboxylates, sulfonates, phosphates, quaternary ammonium salts, and sulfates. All of the aforementioned hydrophilic structures exhibit good hydrophilicity and, when incorporated into the asparagine resin structure, can significantly enhance the hydrophilicity of the modified asparagine resin.

[0031] In some embodiments, the structure of the polyether segment is shown in the following formula (1):

[0032] -(CH2CH2O) a (CH2CHCH3O) b R1(1)

[0033] Where a ≥ 5, b ≥ 0, ab ≥ 5, and R1 is selected from a C1-C4 alkyl group. In the polyether segment, the -(CH2CH2O)- segment (represented by the EO segment) is more hydrophilic than the -(CH2CHCH3O)- segment (represented by the PO segment). Therefore, for the above-mentioned polyether segment, b can be 0, in which case the polyether segment is generally referred to as a polyethylene glycol segment. For example, a can be any value of 5, 6, 7, 8, 9, 10, 12, 15, 17, 18, 20, 22, 25, etc. Of course, the polyether segment can also contain a PO segment, such as a = 7, b = 1, a = 10, b = 2, a = 10, b = 4, a = 15, b = 3, etc., without particular limitation. From the perspective of the reactivity of the terminal hydroxyl groups of the polyether corresponding to the polyether segment, the value of a+b should not exceed 150, otherwise the activity of the terminal hydroxyl groups of the polyether will be low, which will be unfavorable for reaction with the isocyanate group or the reaction rate with the isocyanate group will be slow, which will be unfavorable for industrial implementation or affect production efficiency.

[0034] In some embodiments, the hydrophilic isocyanate compound is obtained by reacting a polyisocyanate monomer with a hydrophilic compound;

[0035] The structure of the hydrophilic compound contains 1-2 active hydrogens. After the hydrophilic compound loses the active hydrogens, the remaining structure contains the above-mentioned hydrophilic structure, wherein the active hydrogen refers to H that can react with NCO groups at 100°C, such as H on -OH, -NH-, -NH2, etc. For example, the hydrophilic compound can be a polyether shown in the following formula (3), which is a non-ionic hydrophilic compound.

[0036] HO(CH2CH2O) a (CH2CHCH3O) b R1(3)

[0037] Wherein, a, b, and R1 have the same meanings as above. For example, commonly used ones include polyethylene glycol monomethyl ether and polyethylene glycol monobutyl ether with number average molecular weights of 200, 250, 300, 350, 400, 600, 800, 1000, and 1200. Polyethylene glycol monomethyl ether with a number average molecular weight of 300 can be expressed as MPEG-300, and polyethylene glycol monomethyl ethers with other molecular weights can be expressed similarly.

[0038] The hydrophilic compound can also be tetramethylammonium 2-aminoethanesulfonate, tetramethylammonium 3-amino-1-propanesulfonate, sodium 3-amino-1-propanesulfonate, tetramethylammonium 3-cyclohexylaminopropanesulfonate, sodium 3-cyclohexylaminopropanesulfonate, triethylamine dimethylolpropionic acid, triethylamine dimethylolbutyric acid, etc. The hydrophilic isocyanate compound obtained by reacting these hydrophilic compounds with polyisocyanate monomers contains highly polar and highly hydrophilic groups such as sulfonates and carboxylates.

[0039] The reaction of polyisocyanate monomers with hydrophilic compounds is well known to those skilled in the art. For example, the following operation can be performed: the polyisocyanate monomers and the hydrophilic compound are added to a reaction vessel, reacted at 20-60° C. for 2 hours, and then heated to about 80-100° C. to react until the NCO group content reaches the theoretical content. Alternatively, unreacted polyisocyanate monomers can be removed by methods such as short-path molecular distillation.

[0040] In some embodiments, the molecular weight of the polyisocyanate monomer does not exceed 300, and the polyisocyanate monomer contains 2-3 NCO groups. For example, the polyisocyanate monomer can be a diisocyanate monomer such as HDI, IPDI, HMDI, TDI, MDI, PDI, NDI, TXDI, or XDI, or a derivative of a diisocyanate monomer, or a trimer of a diisocyanate monomer, such as HDI trimer or IPDI trimer, without particular limitation.

[0041] In some embodiments, the structure of the hydrophobic aspartic acid ester resin is shown in the following formula (2):

[0042]

[0043] Wherein, X is selected from a nonionic m-valent organic group having no more than two heteroatoms and a number average molecular weight of 50-5000 that is inert to isocyanate groups at 100°C, and R2 and R3 are independently selected from C1-C8 hydrocarbon groups, with m = 2-4. Furthermore, the number average molecular weight of X can be 50-300.

[0044] The hydrophobic aspartic acid ester resin can be prepared from the corresponding polyamine compound X(NH2) m With dialkyl maleate R2OCOCH=CHCOOR3, Michael addition reaction occurs to obtain. For polyamine compound X(NH2) m For example, it can be a diamino compound, such as aliphatic diamine, alicyclic diamine, aromatic diamine, etc., specifically, it can be 4,4'-diaminodicyclohexylmethane, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, 1,4-cyclohexanediamine, 1,3-cyclohexanediamine, 2-methyl-1,4-cyclohexanediamine, isophoronediamine, 1,6-hexanediamine, neopentyldiamine, 1,3-cyclopentanediamine, bis(4-amino The polyamine compound may also be a triamino compound or a tetraamino compound, such as 4-(aminomethyl)octane-1,8-diamine, 2,2',2"-triaminotriethylamine, 1,3,5-tris(aminomethyl)-2,4,6-triethylbenzene, 1,1-triaminoethylethane, 1,2,3-triaminopropane, tris(3-aminopropyl)amine and N,N,N',N'-tetrakis(2-aminoethyl)ethylenediamine.

[0045] Furthermore, the above X does not contain heteroatoms, and X is composed only of C and H. For example, hydrophobic aspartic acid ester resins can be directly obtained from the market, such as F420 resin and F520 resin from Feiyang Junyan Company.

[0046] The present invention also proposes an emulsion, which is obtained by dispersing the raw material components comprising the modified asparagus resin described in any of the above technical solutions in water. When preparing the emulsion of the present invention, water can be added to the modified asparagus resin or the raw material components comprising the modified asparagus resin while stirring, or the modified asparagus resin can be gradually added to the stirred water. The obtained emulsion or aqueous dispersion has good stability. After the emulsion and the aqueous isocyanate curing agent are combined and film-formed, a film layer with good water resistance and high gloss can be obtained. The aqueous isocyanate curing agent can be an emulsion form obtained by adding an emulsifier to the isocyanate curing agent, or a hydrophilic structure can be introduced into the isocyanate curing agent and then self-emulsified in water, such as Covestro XP2655 aqueous isocyanate curing agent, Tianjin Liyang New Materials' CA4507WH, Wanhua Chemical's Aquolin 268 water-dispersible isocyanate curing agent, Asahi Kasei's Duranate WL72-100 water-dispersible polyisocyanate, etc.

[0047] In some embodiments, the solid content of the emulsion is 10-60 wt %. For example, the solid content of the emulsion can be any value of 10 wt %, 15 wt %, 20 wt %, 25 wt %, 30 wt %, 35 wt %, 40 wt %, 45 wt %, 50 wt %, 55 wt %, 60 wt %, etc., without particular limitation.

[0048] The technical solution of the present invention is further described and illustrated below based on various embodiments.

[0049] Preparation Example 1-5 Preparation of hydrophilic isocyanate compound

[0050] Preparation Example 1

[0051] 182.6 g of TPA100 (NCO content 23 wt%, NCO content 1 mol) and 60 g of MPEG-300 (OH content 0.2 mol) were mixed and reacted at 40° C. for 2 h, then heated to 80° C. to react until the reaction was complete, and cooled to obtain a water-based isocyanate compound with an NCO content of 13.1 wt%.

[0052] Preparation Example 2

[0053] 182.6 g of TPA100 and 75 g of MPEG-500 (OH content 0.15 mol) were mixed and reacted at 40° C. for 2 h, then heated to 90° C. for reaction until the reaction was complete, and cooled to obtain a water-based isocyanate compound with an NCO content of 13.8 wt%.

[0054] Preparation Example 3

[0055] 182.6 g of TPA100 and 150 g of MPEG-1000 (OH content 0.15 mol) were mixed and reacted at 30° C. for 2 h, then heated to 90° C. to react until the reaction was complete, and cooled to obtain a water-based isocyanate compound with an NCO content of 10.7 wt%.

[0056] Preparation Example 4

[0057] 182.6 g of TPA100, 66.3 g of 3-cyclohexylaminopropanesulfonic acid (NH content 0.3 mol), and 38.1 g (0.3 mol) of N,N-dimethylcyclohexylamine were mixed, and the mixture was heated to 60° C. for complete reaction to obtain an aqueous isocyanate compound having an NCO content of 10.2%.

[0058] Preparation Example 5

[0059] 0.5 mol IPDI and 90 g MPEG-300 (OH content 0.3 mol) were mixed and reacted at 30° C. for 2 h, then heated to 95° C. for reaction until the reaction was complete, and cooled to obtain a water-based isocyanate compound with an NCO content of 14.2 wt%.

[0060] Example 1-9 Preparation of modified asparagus resin

[0061] Example 1

[0062] The aqueous isocyanate compound (NCO content: 1 mol) obtained in Preparation Example 1 and F420 resin (NH content: 1.2 mol) were mixed, stirred and reacted at 35°C for 1 h, heated to 80°C, and continued to stir and react for 2 h, then heated to 120°C and reacted until no NCO group was detected in the reaction system to obtain modified asparagus resin.

[0063] The modified asparagus resin was gradually added to the stirred water, and the stirring was continued for 10 minutes after the addition was complete to obtain an emulsion with a concentration of 50 wt%.

[0064] Example 2

[0065] The difference between this embodiment and embodiment 1 is that in embodiment 1, the F420 resin is adjusted from 1.2 mol to 1.5 mol according to the NH content, and the other steps remain unchanged.

[0066] Example 3

[0067] The difference between this embodiment and embodiment 1 is that in embodiment 1, the F420 resin is adjusted from 1.2 mol to 2 mol according to the NH content, and the other steps remain unchanged.

[0068] Example 4

[0069] The difference between this embodiment and embodiment 1 is that in embodiment 1, the F420 resin is adjusted from 1.2 mol to 2.5 mol according to the NH content, and the other steps remain unchanged.

[0070] Example 5

[0071] The difference between this embodiment and embodiment 1 is that in embodiment 1, the F420 resin is adjusted from 1.2 mol to 2.8 mol according to the NH content, and the other steps remain unchanged.

[0072] Comparative Example 1

[0073] The difference between this comparative example and Example 1 is that in Example 1, the F420 resin is adjusted from 1.2 mol to 1.1 mol according to the NH content, and the other steps remain unchanged.

[0074] Comparative Example 2

[0075] The difference between this comparative example and Example 1 is that in Example 1, the NH content of F420 resin is adjusted from 1.2 mol to 5 mol, and the other steps remain unchanged.

[0076] Comparative Example 3

[0077] The difference between this comparative example and Example 1 is that in Example 1, the NH content of F420 resin is adjusted from 1.2 mol to 10 mol, and the other steps remain unchanged.

[0078] Comparative Example 4

[0079] The aqueous isocyanate compound (NCO content: 1 mol) obtained in Preparation Example 1 and F420 resin (NH content: 1.2 mol) were mixed and directly added to the stirred water. After the addition, stirring was continued for 10 minutes to obtain an emulsion with a concentration of 50 wt%.

[0080] After the emulsion of this comparative example was left at room temperature for 24 hours, it was found that obvious floccules and stratification appeared in the emulsion.

[0081] Comparative Example 5

[0082] Aqueous polyaspartic acid ester resin was prepared according to the method of Example 1 of Chinese Patent CN111303368A and added to stirred water. After the addition, stirring was continued for 10 minutes to obtain an emulsion with a concentration of 50 wt%.

[0083] Example 6

[0084] The aqueous isocyanate compound (NCO content is 1 mol) obtained in Preparation Example 2 and F520 resin (NH content is 2 mol) were mixed, stirred and reacted at 40°C for 1 h, heated to 80°C, and continued to stir and react for 2 h, then heated to 120°C and reacted until no NCO group was detected in the reaction system to obtain modified asparagus resin.

[0085] The modified asparagus resin was gradually added to the stirred water, and the stirring was continued for 10 minutes after the addition was complete to obtain an emulsion with a concentration of 60 wt%.

[0086] Example 7

[0087] The difference between this example and Example 6 is that in Example 6, the aqueous isocyanate compound obtained in Preparation Example 2 is replaced by the aqueous isocyanate compound obtained in Preparation Example 3 in an equimolar ratio of NH, and the other steps remain unchanged.

[0088] Example 8

[0089] The difference between this example and Example 6 is that in Example 6, the aqueous isocyanate compound obtained in Preparation Example 2 is replaced by the aqueous isocyanate compound obtained in Preparation Example 4 in an equimolar ratio of NH, and the other steps remain unchanged.

[0090] Example 9

[0091] The difference between this example and Example 6 is that in Example 6, the aqueous isocyanate compound obtained in Preparation Example 2 is replaced by the aqueous isocyanate compound obtained in Preparation Example 5 in an equimolar ratio of NH, and the other steps remain unchanged.

[0092] Performance Testing

[0093] Emulsion stability test: stored at 40°C for 6 months.

[0094] Emulsion particle size test: tested by Malvern laser particle size analyzer.

[0095] Coating gloss test: The emulsion to be tested was mixed with curing agent WL72-100 at a molar ratio of NH to NCO of 1:1.1. The mixture was diluted with purified water to 45% solid content and then sprayed onto a clean tinplate. After curing at room temperature for 7 days, the gloss of the coating was tested at 60°.

[0096] Coating water resistance test: The emulsion to be tested is mixed with curing agent WL72-100 at a molar ratio of NH to NCO of 1:1.1. The mixture is then diluted with pure water to a solid content of 45% and sprayed onto a clean tinplate. The mixture is cured at room temperature for 7 days. Half of the tinplate is immersed in 38°C water. After 48 hours, the coating on the water surface is observed for bubbling, shedding, edge lift, and other abnormalities.

[0097] Coating Adhesion Test: The emulsion to be tested was mixed with curing agent WL72-100 at a molar ratio of NH to NCO of 1:1.1. The mixture was diluted with purified water to a 45% solids content and sprayed onto a clean tinplate. The coating was cured at room temperature for 7 days and tested for adhesion using the 100-grid method. Adhesion was graded on a scale of 0-5, with 0 being the best and 5 being the worst.

[0098] The results are shown in Table 1 below.

[0099] Table 1

[0100]

[0101] As shown in Table 1, when the molar ratio of NH groups in the aspartic acid ester resin to NCO groups in the hydrophilic isocyanate compound is within an appropriate range, a stable emulsion can be obtained, and the cured coating exhibits high gloss, good water resistance, and good adhesion. If the NH group content is high, as in Comparative Examples 2 and 3, the emulsion particle size is large, the hydrophilicity of the modified aspartic acid ester resin is poor, and the coating gloss is low. If the NH group content is low, the hydrophilicity of the modified aspartic acid ester resin is very good, as in Comparative Example 1, but the water resistance may be deviated.

[0102] As described above, the basic principles, main features, and advantages of the present invention are shown and described. Those skilled in the art should understand that the present invention is not limited to the above-described embodiments. The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. In other words, equivalent changes and modifications made within the scope of the present invention and the contents of the specification should still fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A modified asparagus resin, characterized in that Obtained by the reaction of a hydrophilic isocyanate compound and a hydrophobic aspartic acid ester resin; The molar ratio of the NH groups in the hydrophobic aspartic acid ester resin to the NCO groups in the hydrophilic isocyanate compound is not less than 1.2 and less than 3.

2. The modified asparagus resin according to claim 1, characterized in that The hydrophilic isocyanate compound contains a chemically bonded hydrophilic structure, and the content of NCO groups in the hydrophilic isocyanate compound is not less than 5 wt %.

3. The modified asparagus resin according to claim 2, characterized in that The hydrophilic structure is selected from one or a combination of two or more of a polyether segment, a carboxylate, a sulfonate, a phosphate, a quaternary ammonium salt and a sulfate.

4. The modified asparagus resin according to claim 3, characterized in that The structure of the polyether segment is shown in the following formula (1): -(CH2CH2O) a (CH2CHCH3O) b R1(1) Wherein, a≥5, b≥0, ab≥5, and R1 is selected from C1-C4 alkyl.

5. The modified asparagus resin according to claim 2, characterized in that The hydrophilic isocyanate compound is obtained by reacting a polyisocyanate monomer with a hydrophilic compound; The hydrophilic compound contains 1-2 active hydrogen atoms in its structure, and the remaining structure of the hydrophilic compound after losing the active hydrogen atoms contains the hydrophilic structure.

6. The modified asparagus resin according to claim 5, characterized in that The molecular weight of the polyisocyanate monomer does not exceed 300, and the structure of the polyisocyanate monomer contains 2-3 NCO groups.

7. The modified asparagus resin according to claim 1, characterized in that The structure of the hydrophobic aspartic acid ester resin is shown in the following formula (2): wherein X is selected from a nonionic m-valent organic group having a number average molecular weight of 50-5000 and no more than 2 heteroatoms and being inert to reaction with isocyanate groups at 100° C., and R2 and R3 are independently selected from C1-C8 hydrocarbon groups, with m=2-4.

8. The modified asparagus resin according to claim 1, characterized in that The molar ratio of the NH groups in the hydrophobic aspartic acid ester resin to the NCO groups in the hydrophilic isocyanate compound is 1.5-2.5:

1.

9. An emulsion, characterized in that The method is obtained by dispersing raw material components comprising the modified asparagus resin according to any one of claims 1 to 8 in water.

10. The emulsion according to claim 9, characterized in that The solid content of the emulsion is 10-60 wt%.

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