Modified aspartate resin and aqueous dispersion

Abstract

The invention provides a modified aspartate resin and an aqueous dispersion, and relates to the technical field of aqueous emulsions. The modified aspartic ester resin is obtained by reacting hydrophilic aspartic ester resin with a polyisocyanate compound and then reacting with hydrophobic aspartic ester resin, has moderate hydrophilicity and can be self-emulsified and dispersed in water to form an aqueous dispersion, and a coating cured by the aqueous dispersion is relatively good in water resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of aqueous emulsions and relates to a modified aspartic acid ester resin and an aqueous dispersion. Background Art

[0002] The development of water-based aspartic acid polyurea coatings is an important direction in the field of aspartic acid polyurea, which can combine the characteristics and advantages of water-based coatings and aspartic acid polyurea coatings. Water-based polyurea coatings are generally obtained by mixing a water-based aspartic acid ester resin emulsion and an isocyanate curing agent. The prior art reports a number of preparation methods for water-based aspartic acid ester resins, all of which introduce hydrophilic polyethylene glycol segments into the ester structure of the aspartic acid ester resin, such as grafting polyethylene glycol monoalkyl ether onto the aspartic acid ester resin through an ester exchange reaction, or using maleic acid polyethylene glycol monoalkyl ester and a polyamine compound to undergo a Michael addition reaction to obtain it. For example, Chinese patent CN111635519A reports that maleic acid ester and polyethylene glycol monomethyl ether are subjected to an ester exchange reaction to synthesize hydrophilic maleic acid ester, which is then reacted with primary amine substances to obtain a water-based aspartic acid resin, which is then mixed with an isocyanate curing agent to obtain a water-based aspartic acid polyurea coating. However, the hydrophilicity of the water-based aspartic acid ester resin obtained by this method is relatively high, resulting in problems such as insufficient water resistance and poor corrosion resistance of the coating after the water-based aspartic acid polyurea coating is cured.

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

[0004] Based on the above purpose, the present invention provides an emulsion.

[0005] The invention also provides a water-based paint.

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

[0007] A modified aspartic acid ester resin, wherein the preparation method of the modified aspartic acid ester resin comprises the following steps:

[0008] S1, a hydrophilic aspartic acid ester resin and a polyisocyanate compound react to obtain a first resin containing an NCO group,

[0009] The hydrophilic aspartic acid ester resin contains polyethylene glycol segments;

[0010] S2. The first resin described in step S1 is reacted with a hydrophobic aspartic acid ester resin to obtain the modified aspartic acid ester resin.

[0011] Preferably, the structure of the hydrophilic aspartic acid ester resin in step S1 is as shown in the following formula (1):

[0012]

[0013] 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 an isocyanate group at 100° C., at least one of R1 and R2 contains a polyethylene glycol segment, and m=2-4.

[0014] More preferably, the structure of the polyethylene glycol segment is as shown in the following formula (2):

[0015] -(CH2CH2O) p (CH2CHCH3O) q R3(2)

[0016] Wherein, p≥5, q≥0, pq≥5, and R3 is selected from C1-C8 alkyl.

[0017] More preferably, both R1 and R2 contain the polyethylene glycol segment;

[0018] Alternatively, the R1 contains the polyethylene glycol segment, and the R2 is selected from a C1-C8 hydrocarbon group.

[0019] Preferably, the molecular weight of the polyisocyanate compound in step S1 is no more than 2500, and the structure of the polyisocyanate compound contains 2-3 isocyanate groups.

[0020] More preferably, the polyisocyanate compound is obtained by reacting a diisocyanate monomer with at least one of polyester diol, polyether diol and polyether polyamine.

[0021] Preferably, in step S1, the molar ratio of the NH groups in the hydrophilic aspartic acid ester resin to the NCO groups in the polyisocyanate compound is 1:1.2-3.

[0022] Preferably, the structure of the hydrophobic aspartic acid ester resin in step S2 is as shown in the following formula (3):

[0023]

[0024] Wherein, Y is selected from a nonionic n-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., R4 and R5 are independently selected from C1-C8 hydrocarbon groups, and n=2-4.

[0025] Preferably, in step S2, the molar ratio of the NCO groups in the first resin to the NH groups in the hydrophobic aspartic acid ester resin is 1:0.8-1.3.

[0026] An aqueous dispersion is obtained by emulsifying and dispersing the modified aspartic acid ester resin according to any one of the above embodiments in water.

[0027] The beneficial effects of the present invention are:

[0028] (1) The present invention uses a hydrophilic aspartic acid ester resin and a polyisocyanate compound to react to obtain a first resin containing an NCO group, and the first resin is then reacted with a hydrophobic aspartic acid ester resin to obtain a modified aspartic acid ester resin with relatively suitable hydrophilicity. The modified aspartic acid ester resin can be self-emulsified and dispersed in water to form a stable aqueous dispersion. After curing, the aqueous dispersion has good water resistance, adhesion and other properties.

[0029] (2) The modified aspartic acid ester resin of the present invention can have a relatively high molecular weight, and the resulting aqueous dispersion can form a film without the addition of a curing agent. Furthermore, the film exhibits good adhesion and water resistance. If the molecular weight of the modified aspartic acid ester resin is not high enough, an isocyanate curing agent can be added to the aqueous dispersion to cure the film. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is further illustrated and described below through specific implementation methods.

[0031] In one aspect, the present invention provides a modified aspartic acid ester resin. The preparation method of the modified aspartic acid ester resin comprises the following steps:

[0032] S1, a hydrophilic aspartic acid ester resin and a polyisocyanate compound react to obtain a first resin containing an NCO group,

[0033] The hydrophilic aspartic acid ester resin contains polyethylene glycol segments;

[0034] S2. The first resin of step S1 is reacted with a hydrophobic aspartic acid ester resin to obtain a modified aspartic acid ester resin.

[0035] The modified aspartic acid ester resin of the present invention comprises a hydrophilic group derived from the hydrophilic group (polyethylene glycol segment) in the hydrophilic aspartic acid ester. The hydrophilic aspartic acid ester resin reacts with a polyisocyanate compound and then with a hydrophobic aspartic acid ester resin. The resulting modified aspartic acid ester resin has the following characteristics: a larger molecular weight and a lower but moderate hydrophilicity. The higher molecular weight means that the aqueous dispersion has better film properties (such as improved water resistance and adhesion) after curing and can be made into a single component. The lower but moderate hydrophilicity means that it can be self-emulsified and dispersed in water, and the film layer has better water resistance.

[0036] In some embodiments, the structure of the hydrophilic aspartic acid ester resin in step S1 is shown in the following formula (1):

[0037]

[0038] 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 an isocyanate group at 100° C., at least one of R1 and R2 contains a polyethylene glycol segment, and m=2-4.

[0039] In the present invention, the hydrophilic group of the hydrophilic aspartic acid ester resin is obtained by chemically bonding a polyethylene glycol segment to the ester group. The preparation method of the hydrophilic aspartic acid ester resin is not particularly limited, for example, the polyamine compound X (NH2) can be prepared. m It can be obtained by Michael addition reaction with polyethylene glycol maleate (monoester or diester), or by transesterification reaction of aspartic acid ester resin (such as F420 resin, F520 resin, etc. of Feiyang Junyan Company) with polyethylene glycol monoalkyl ester (such as polyethylene glycol monomethyl ether MPEG). In the present invention, X is not particularly limited, for example, it can be etc. structures.

[0040] In some embodiments, the structure of the polyethylene glycol segment is shown in the following formula (2):

[0041] -(CH2CH2O) p (CH2CHCH3O) q R3(2)

[0042] Wherein, p≥5, q≥0, pq≥5, and R3 is selected from C1-C8 alkyl.

[0043] The above-mentioned polyethylene glycol chain segment has good hydrophilicity. For example, the values of p and q can be p=5, q=0, p=8, q=0, p=10, q=2, p=10, q=4, p=15, q=3, p=15, q=8, p=20, q=0, p=20, q=6, p=20, q=10, etc., without any special restrictions.

[0044] In some embodiments, both R1 and R2 contain polyethylene glycol segments;

[0045] Alternatively, R1 contains a polyethylene glycol segment, and R2 is selected from a C1-C8 hydrocarbon group.

[0046] When both R1 and R2 contain polyethylene glycol segments, the hydrophilicity of the hydrophilic aspartic acid ester resin is higher; when only R1 contains a polyethylene glycol segment, and R2 is, for example, an ethyl group, the hydrophilicity of the hydrophilic aspartic acid ester resin varies according to the hydrophilicity of the polyethylene glycol segment. The higher the hydrophilicity of the polyethylene glycol segment, the better the hydrophilicity of the hydrophilic aspartic acid ester resin.

[0047] In certain embodiments, the molecular weight of polyisocyanate compound in step S1 is no more than 2500, and the structure of polyisocyanate compound contains 2-3 isocyanate groups.If the molecular weight of polyisocyanate compound is too large, the activity of the NCO group of the end group will be on the low side, and the reactivity with hydrophilic aspartic acid resin will be relatively low. In the present invention, polyisocyanate compound has no particular restrictions, and can be a diisocyanate monomer, such as IPDI, HMDI, HDI, MDI, etc., or can be obtained by reacting at least one of the above-mentioned diisocyanate monomers with polyester diols, polyether diols and polyether polyamines, such as the adducts of IPDI and polycarbonate diol (number-average molecular weight can be 400-2000), the adducts of HMDI and polycaprolactone diol (number-average molecular weight can be 400-2000), the adducts of IPDI and polytetramethylene ether diol, the adducts of IPDI and polyoxypropylene ether diol, the adducts of HDI and polyetheramine, etc., and the preparation method of the adduct is well known to those skilled in the art.

[0048] In some embodiments, the molar ratio of the NH groups in the hydrophilic aspartic acid ester resin to the NCO groups in the polyisocyanate compound in step S1 is 1:1.2-3. The NCO groups in the polyisocyanate compound are in excess relative to the NH groups in the hydrophilic aspartic acid ester resin, and the obtained first resin contains unreacted NCO groups, which can continue to react with the hydrophobic aspartic acid ester resin to obtain a modified aspartic acid ester resin. For example, the molar ratio of the NH groups in the hydrophilic aspartic acid ester resin to the NCO groups in the polyisocyanate compound can be any value in 1:1.2, 1:1.4, 1:1.5, 1:1.7, 1:1.8, 1:2, 1:2.2, 1:2.3, 1:2.5, 1:2.7, 1:2.8, 1:3, etc., without particular limitation. Further, the molar ratio can be 1:1.2-1.8.

[0049] In some embodiments, the hydrophobic aspartic acid ester resin in step S2 does not contain a hydrophilic structure, such as a polyethylene glycol segment, a sulfonate, a sulfate, a carboxylate, a quaternary ammonium salt structure, a phosphate structure, etc. The structure of the hydrophobic aspartic acid ester resin is shown in the following formula (3):

[0050]

[0051] Wherein, Y is selected from a nonionic n-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., R4 and R5 are independently selected from C1-C8 hydrocarbon groups, and n=2-4.

[0052] The hydrophobic aspartic acid ester resin can be prepared according to existing technology or directly obtained from the market, such as F420 resin, F520 resin, F421 resin, F220 resin, F330 resin, F2850 resin, etc. produced by Feiyang Junyan Company.

[0053] In some embodiments, the molar ratio of the NCO groups in the first resin to the NH groups in the hydrophobic aspartic acid ester resin in step S2 is 1:0.8-1.3. For example, the molar ratio can be any value of 1:0.8, 1:0.82, 1:0.85, 1:0.87, 1:0.9, 1:0.92, 1:0.95, 1:0.97, 1:0.98, 1:1, 1:1.02, 1:1.05, 1:1.07, 1:1.08, 1:1.1, 1:1.12, 1:1.15, 1:1.18, 1:1.2, 1:1.22, 1:1.25, 1:1.27, 1:1.3, etc., without particular limitation. By adjusting the molar ratio of the NCO group in the first resin and the NH group in the hydrophobic aspartic acid ester resin, modified aspartic acid ester resins of different molecular weights can be obtained, and the modified aspartic acid ester resin has certain hydrophilicity, can be preferably self-emulsified and dispersed in water, to form a stable emulsion. Further, the molar ratio of the NCO group in the first resin and the NH group in the hydrophobic aspartic acid ester resin can be 1: 0.8-0.9, and the modified aspartic acid ester obtained contains NCO groups. After emulsification and dispersion in water, the NCO group reacts with water and produces primary amino groups, and the primary amino groups can continue to react with the NCO groups, and the multi-modified aspartic acid ester resin plays a chain extension effect, increases molecular weight, and therefore can be made into a single-component aqueous dispersion. Further, the molar ratio of the NCO group in the first resin and the NH group in the hydrophobic aspartic acid ester resin can be 1: 1.1-1.3, and the modified aspartic acid ester obtained contains NH groups. After emulsification and dispersion in water, it can continue to react and solidify with an isocyanate curing agent, and therefore can be made into a two-component aqueous dispersion.

[0054] In another aspect, the present invention further provides an aqueous dispersion obtained by emulsifying and dispersing the modified aspartic acid ester resin described in any of the above embodiments in water. In the present invention, the aqueous dispersion may have a solids content of 10-60 wt % and may be a single-component or two-component aqueous dispersion.

[0055] The aqueous dispersion of the present invention can be further prepared into a water-based coating. The raw materials for the water-based coating may include, by weight, 100 parts of the aqueous dispersion of the present invention, 0-100 parts of pigments and fillers, and 1-10 parts of additives. The aqueous dispersion of the present invention utilizes the modified aspartic acid ester resin as the main resin, exhibiting both good hydrophilicity and self-emulsification properties. Furthermore, the cured film exhibits excellent water resistance, adhesion, and other properties. In the water-based coating, the pigments and fillers are not particularly limited. Pigments may be organic or inorganic, such as phthalocyanine blue, phthalocyanine green, titanium dioxide, carbon black, and iron oxide red. Fillers may be inorganic or organic. Inorganic fillers may include talc, kaolin, silica powder, cerium oxide, silicon dioxide, and aluminum oxide, while organic fillers may include PE micropowder and PTFE micropowder. Additives may include leveling agents, dispersants, anti-settling agents, thixotropic agents, wetting agents, defoamers, antioxidants, UV inhibitors, and anti-yellowing agents. Based on the molecular weight and the groups carried by the modified aspartic acid ester resin, it can be a one-component water-based paint or a two-component water-based paint.

[0056] The technical solution of the present invention is further described and illustrated below based on various preparation examples and embodiments.

[0057] Preparation Example 1-3 Preparation of hydrophilic aspartic acid ester resin

[0058] Preparation Example 1

[0059] 554 g F420 resin (1 mol) and 1000 g MPEG-500 (2 mol) were added to a four-necked flask, and 1 g of butyltin oxide catalyst was added. The temperature was raised to 120° C. and the vacuum degree was -0.098 MPa to complete the reaction to obtain a hydrophilic aspartic acid ester resin, which was recorded as hydrophilic monomer 1.

[0060] Preparation Example 2

[0061] 460 g F220 resin (1 mol) and 1000 g MPEG-1000 (1 mol) were added to a four-necked flask, and 1 g of butyltin oxide catalyst was added. The temperature was raised to 120° C. and the vacuum degree was -0.098 MPa to complete the reaction to obtain a hydrophilic aspartic acid ester resin, which was recorded as hydrophilic monomer 2.

[0062] Preparation Example 3

[0063] 554 g F420 resin (1 mol) and 400 g MPEG-200 (2 mol) were added to a four-necked flask, and 1 g of butyltin oxide catalyst was added. The temperature was raised to 120° C. and the vacuum degree was -0.098 MPa to complete the reaction, resulting in a hydrophilic aspartic acid ester resin, which was recorded as hydrophilic monomer 3.

[0064] Preparation Example 4-7 Preparation of polyisocyanate compounds

[0065] Preparation Example 4

[0066] 109.2 g HDI (eq: 1.3 mol) and 250 g (eq: 1 mol) polycaprolactone diol having a hydroxyl value content of 224.4 mgKOH / g were reacted at 100° C. for 6 h to obtain a polyisocyanate compound having an NCO content of 3.5 wt %, which was recorded as isocyanate 1.

[0067] Preparation Example 5

[0068] 1680 g (eq: 20 mol) of HDI and 1500 g (eq: 1.5 mol) of polyetheramine D2000 having an amine value content of 56.1 mgKOH / g were reacted at 80° C. for 1 h to obtain a polyisocyanate compound having an NCO content of 24.4 wt %, which was recorded as isocyanate 2.

[0069] Preparation Example 6

[0070] 227.5 g (eq: 2.5 mol) of IPDI and 500 g (eq: 1 mol) of polytetramethylene glycol having a hydroxyl value of 112.2 mgKOH / g were reacted at 80° C. for 12 h to obtain a polyisocyanate compound having an NCO content of 8.1 wt %, which was designated as isocyanate 3.

[0071] Preparation Example 7

[0072] 327.5 g (eq: 2.5 mol) of HMDI and 500 g (eq: 0.5 mol) of polypropylene carbonate diol having a hydroxyl value of 56.1 mgKOH / g were reacted at 80° C. for 12 h to obtain a polyisocyanate compound having an NCO content of 10.2 wt %, which was designated as isocyanate 4.

[0073] Example 1

[0074] Under nitrogen protection, the hydrophilic monomer 1 (eq: 1 mol) obtained in Preparation Example 1 and the isocyanate 1 (eq: 1.4 mol) obtained in Preparation Example 4 were reacted at 90-100° C. until the NH group disappeared (FT-IR detection) to obtain a first resin.

[0075] Under nitrogen protection, the first resin (eq: 1 mol) and F420 resin (eq: 1.3 mol) were reacted at 100-110° C. until the NCO group could not be detected, thereby obtaining a modified aspartic acid ester resin.

[0076] The modified aspartic acid ester resin was added to water, stirred and dispersed for 30 minutes to prepare an aqueous dispersion with a concentration of 50 wt%.

[0077] Example 2

[0078] The difference between this example and Example 1 is that in Example 1, the amount of F420 resin added is adjusted to 1.1 molar equivalents. The remaining steps remain unchanged.

[0079] Comparative Example 1

[0080] A water-based polyaspartic acid ester resin was prepared according to the method of Example 1 of Chinese Patent CN111303368A and added to stirred water. Stirring was continued for 10 minutes after the addition to obtain a 50 wt% emulsion. The aqueous dispersion obtained in this comparative example exhibited obvious flocculent formation and stratification after standing at room temperature for 24 hours.

[0081] Comparative Example 2

[0082] The difference between this comparative example and Example 1 is that when preparing the aqueous dispersion, the modified aspartic acid ester resin in Example 1 is replaced by an equal weight of the first resin obtained in Example 1.

[0083] Comparative Example 3

[0084] This comparative example differs from Example 1 in that the modified aspartic acid ester resin in Example 1 was replaced with an equal weight combination of the first resin (eq. 1 mol) and F420 resin (eq. 1.3 mol) from Example 1 during the preparation of the aqueous dispersion. The aqueous dispersion obtained in this comparative example exhibited noticeable floccules and stratification after standing at room temperature for 24 hours.

[0085] Example 3

[0086] The difference between this example and Example 1 is that in Example 1, the amount of F420 resin added is adjusted to 0.8 molar equivalents. The remaining steps remain unchanged.

[0087] Example 4

[0088] The difference between this example and Example 1 is that in Example 1, the amount of F420 resin added is adjusted to 0.9 molar equivalents. The remaining steps remain unchanged.

[0089] Example 5

[0090] Under nitrogen protection, the hydrophilic monomer 2 (eq: 1 mol) obtained in Preparation Example 2 and the isocyanate 2 (eq: 1.2 mol) obtained in Preparation Example 5 were reacted at 90-100° C. until the NH group disappeared to obtain a first resin.

[0091] Under nitrogen protection, the first resin (eq: 1 mol) and F420 resin (eq: 1.2 mol) were reacted at 100-110° C. until no NCO group was detected, thereby obtaining a modified aspartic acid ester resin.

[0092] The modified aspartic acid ester resin was added to water, stirred and dispersed for 30 minutes to prepare an aqueous dispersion with a concentration of 40 wt%.

[0093] Example 6

[0094] Under nitrogen protection, the hydrophilic monomer 3 (eq: 1 mol) obtained in Preparation Example 3 and the isocyanate 3 (eq: 1.8 mol) obtained in Preparation Example 6 were reacted at 80-90° C. until the NH group disappeared to obtain a first resin.

[0095] Under nitrogen protection, the first resin (eq: 1 mol) and F520 resin (eq: 1.3 mol) were reacted at 100-110° C. until the NCO group could not be detected, thereby obtaining a modified aspartic acid ester resin.

[0096] The modified aspartic acid ester resin was added to water, stirred and dispersed for 30 minutes to prepare an aqueous dispersion with a concentration of 40 wt%.

[0097] Example 7

[0098] Under nitrogen protection, the hydrophilic monomer 3 (eq: 1 mol) obtained in Preparation Example 3 and the isocyanate 4 (eq: 1.4 mol) obtained in Preparation Example 6 were reacted at 80-90° C. until the NH group disappeared to obtain a first resin.

[0099] Under nitrogen protection, the first resin (eq: 1 mol) and F330 resin (eq: 0.85 mol) were reacted at 100-110° C. until no NCO group was detected, thereby obtaining a modified aspartic acid ester resin.

[0100] The modified aspartic acid ester resin was added to water, stirred and dispersed for 30 minutes to prepare an aqueous dispersion with a concentration of 50 wt%.

[0101] Performance testing

[0102] Aqueous dispersion stability test: The aqueous dispersion to be tested is stored at 40°C for 6 months to observe whether there are any abnormalities such as stratification, demulsification, and oil floating.

[0103] Particle size test of water dispersion: tested by Malvern laser particle size analyzer.

[0104] Coating Gloss Test: The aqueous dispersions to be tested (excluding Comparative Example 1, Examples 3, 4, and 7) were mixed with curing agent WL72-100 at a NH:NCO molar ratio of 1:1.1. The mixture was diluted with purified water to 45% solids before spraying onto clean tinplate. After curing at room temperature for 7 days, the coating gloss at 60° was measured. The aqueous dispersions of Examples 3, 4, and 7 were directly sprayed onto clean tinplate. After curing at room temperature for 7 days, the coating gloss at 60° was measured.

[0105] Coating Water Resistance Test: The aqueous dispersion to be tested (excluding Comparative Example 1, Example 3, Example 4, and Example 7) was mixed with curing agent WL72-100 at a molar ratio of NH to NCO of 1:1.1, diluted with purified water to 45% solids, and then sprayed onto clean tinplate. Cured at room temperature for 7 days. The aqueous dispersions of Examples 3, 4, and 7 were directly sprayed onto clean tinplate and cured at room temperature for 7 days. Half of the coated tinplate was immersed in 38°C water. After 48 hours, the coating at the water surface was observed for abnormalities such as bubbling, shedding, and edge lifting.

[0106] Coating Adhesion Test: The aqueous dispersions to be tested (excluding Comparative Example 1, Examples 3, 4, and 7) were mixed with curing agent WL72-100 at a NH:NCO molar ratio of 1:1.1. The mixture was diluted with purified water to 45% solids before spraying onto clean tinplate and curing at room temperature for 7 days. The aqueous dispersions of Examples 3, 4, and 7 were directly sprayed onto clean tinplate and cured at room temperature for 7 days. Adhesion was tested using the 100-grid method. Adhesion was graded on a scale of 0-5, with 0 being the best and 5 being the worst.

[0107] The results are shown in Table 1 below.

[0108] Table 1

[0109]

[0110] From the data results in Table 1, it can be seen that the aqueous dispersion obtained by self-emulsification of the modified polyaspartic acid ester resin of the present invention has good stability, and the coating after curing has high gloss, good water resistance and high adhesion.

[0111] 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 aspartic acid ester resin, characterized in that: The preparation method of the modified aspartic acid ester resin comprises the following steps: S1, a hydrophilic aspartic acid ester resin and a polyisocyanate compound react to obtain a first resin containing an NCO group, The hydrophilic aspartic acid ester resin contains polyethylene glycol segments; S2. The first resin described in step S1 is reacted with a hydrophobic aspartic acid ester resin to obtain the modified aspartic acid ester resin.

2. The modified aspartic acid ester resin according to claim 1, characterized in that The structure of the hydrophilic aspartic acid ester resin in step S1 is shown in the following formula (1): 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 an isocyanate group at 100° C., at least one of R1 and R2 contains a polyethylene glycol segment, and m=2-4.

3. The modified aspartic acid ester resin according to claim 2, characterized in that The structure of the polyethylene glycol segment is shown in the following formula (2): <h2 style=";text-align:left;direction:ltr">-(CH2CH2O)<h2 style=";text-align:left;direction:ltr"> p <h2 style=";text-align:left;direction:ltr"> (CH2CHCH3O)<h2 style=";text-align:left;direction:ltr"> q <h2 style=";text-align:left;direction:ltr"> R3(2) Wherein, p≥5, q≥0, pq≥5, and R3 is selected from C1-C8 alkyl.

4. The modified aspartic acid ester resin according to claim 2, characterized in that Both R1 and R2 contain the polyethylene glycol segment; Alternatively, the R1 contains the polyethylene glycol segment, and the R2 is selected from a C1-C8 hydrocarbon group.

5. The modified aspartic acid ester resin according to claim 1, characterized in that The molecular weight of the polyisocyanate compound in step S1 does not exceed 2500, and the structure of the polyisocyanate compound contains 2-3 isocyanate groups.

6. The modified aspartic acid ester resin according to claim 5, characterized in that The polyisocyanate compound is obtained by reacting a diisocyanate monomer with at least one of polyester diol, polyether diol and polyether polyamine.

7. The modified aspartic acid ester resin according to claim 1, characterized in that In step S1, the molar ratio of the NH group in the hydrophilic aspartic acid ester resin to the NCO group in the polyisocyanate compound is 1:1.2-3.

8. The modified aspartic acid ester resin according to claim 1, characterized in that The structure of the hydrophobic aspartic acid ester resin in step S2 is shown in the following formula (3): Wherein, Y is selected from a nonionic n-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., R4 and R5 are independently selected from C1-C8 hydrocarbon groups, and n=2-4.

9. The modified aspartic acid ester resin according to claim 1, characterized in that In step S2, the molar ratio of the NCO groups in the first resin to the NH groups in the hydrophobic aspartic acid ester resin is 1:0.8-1.

3.

10. An aqueous dispersion, characterized in that The modified aspartic acid ester resin according to any one of claims 1 to 9 is emulsified and dispersed in water.

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