Polycarbodiimides, processes for their preparation, use thereof, compositions containing them

Abstract

This invention discloses a polycarbodiimide, its preparation method, applications, and compositions containing it. It is a compound as shown in Formula I, where R1 is C 1‑18 The alkylene group or -L1-L2-L3-; R2O- is a residue of a hydrophilic compound containing an unsaturated double bond and active hydrogen after removing a hydrogen atom; molecular weight less than 1000 g / mol; R3O- is a residue of a hydrophilic compound containing an unsaturated double bond and active hydrogen after removing a hydrogen atom; or a residue of a hydrophilic compound containing active hydrogen after removing a hydrogen atom; or a residue of a compound containing active hydrogen after removing a hydrogen atom; molecular weight less than 1000 g / mol; n is 1-10. The polycarbodiimide crosslinking agent of the present invention can effectively improve the comprehensive properties of waterborne UV coatings, such as crosslinking density, water resistance, solvent resistance, and mechanical properties.

Description

Technical Field

[0001] This invention relates to a polycarbodiimide, its preparation method, applications, and compositions containing the same. Background Technology

[0002] Driven by environmental regulations, the coatings industry is transforming towards high solids content, water-based coatings, ultraviolet (UV) curing, and powder coatings. Among these, UV coatings, with their rapid curing, low VOCs, and high hardness, have become an important and undeniable direction for coating development and are widely used in wood, plastics, and metals. Traditional UV coatings are solvent-based and have formed a complete industrial system. However, solvent-based UV coatings must be diluted with reactive diluents such as acrylate monomers or solvents during use, which produces irritating odors and VOC emissions, harming the health of construction workers. To solve these problems, water-based UV coatings have emerged.

[0003] Waterborne UV resins have a similar chemical composition to solvent-based UV resins, achieving waterborne properties by introducing nonionic or anionic units into the resin molecular chain. Waterborne UV coatings offer advantages such as environmental friendliness, non-toxicity, non-flammability, and high safety, but also some disadvantages. For example, waterborne UV systems tend to have lower crosslinking density and lower water resistance compared to solvent-based UV resins.

[0004] Carbodiimide is a class of compounds that can selectively react with carboxyl groups. Due to its environmentally friendly and low-toxicity characteristics, it is an ideal crosslinking agent for waterborne resins and has been widely used in the fields of waterborne polyurethane and acrylic. However, there is currently a lack of carbodiimide crosslinking agents suitable for waterborne UV resins on the market. Summary of the Invention

[0005] The technical problem to be solved by this invention is the poor crosslinking density, water resistance, and solvent resistance of existing waterborne UV coatings. This invention provides a polycarbodiimide, its preparation method, applications, and compositions containing the same. The polycarbodiimide crosslinking agent of this invention can effectively improve the overall performance of waterborne UV coatings, including crosslinking density, water resistance, and solvent resistance.

[0006] The present invention solves the above-mentioned technical problems through the following technical solutions.

[0007] This invention provides a compound as shown in Formula I:

[0008]

[0009] Where R1 is C 1-18 Alkylene or -L1-L2-L3- (L1 is the left end of the group, L3 is the right end of the substituent, for example, when R1 is -L 1 -L 2 When -L3-, Formula I segment In the diagram, L1 is connected to -NH-, and L3 is connected to... (connected to end a in the middle);

[0010] L1 is C 3-13 Cycloalkylene, C 1-4 The alkylene group is either absent or nonexistent (i.e., -L1-L2-L3- is -L2-L3-);

[0011] L2 is C 1-4 alkylene or C 6-10 Alpha-aryl;

[0012] L3 is C 3-13 Cycloalkylene, with one or more C 1-4 alkyl-substituted C 3-13 Cycloalkylene (e.g., 2, 3, or 4) or C 1-4 Alkylene;

[0013] R2O- is the residue after removing hydrogen atoms from a hydrophilic compound containing an unsaturated double bond and active hydrogen; its molecular weight is less than 1000 g / mol.

[0014] R3O- represents the residue after removing a hydrogen atom from a hydrophilic compound containing an unsaturated double bond and active hydrogen; or the residue after removing a hydrogen atom from a hydrophilic compound containing active hydrogen; or the residue after removing a hydrogen atom from a compound containing active hydrogen; with a molecular weight less than 1000 g / mol.

[0015] n is 1-10.

[0016] In one embodiment of the present invention, in R1, the C 1-18 The alkylene group is C 1-6 Alkylenes, such as methylene, For example

[0017] In one embodiment of the present invention, in L1, the C 3-13 The cycloalkylene group is cyclopropylene, cyclopropylbutylene, cyclopentylene, or cyclohexylene, for example...

[0018] In one embodiment of the present invention, in L1, the C 1-4 The alkylene group is For example

[0019] In one embodiment of the present invention, in L2, the C 1-4 The alkylene group is For example, methylene.

[0020] In one embodiment of the present invention, in L2, the C 6-10 The aryl group can be

[0021] In one embodiment of the present invention, in L3, the C 3-13 The cycloalkylene group is cyclopropylene, cyclopropylbutylene, cyclopentylene, or cyclohexylene, for example...

[0022] In one embodiment of the present invention, L3, the one or more C 1-4 alkyl-substituted C 3-13 C in cycloalkylene 3-13 The cycloalkylene group is cyclopropylene, cyclopropylbutylene, cyclopentylene, or cyclohexylene, for example...

[0023] In one embodiment of the present invention, L3, the one or more C 1-4 alkyl-substituted C 3-13 C in cycloalkylene 1-4 The alkyl group is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, or tert-butyl, such as methyl.

[0024] In one embodiment of the present invention, L3, the one or more C 1-4 alkyl-substituted C 3-13 The methyl-substituted cyclohexyl group in the cyclohexene alkyl group, for example

[0025] In one embodiment of the present invention, in L3, the C 1-4 The alkylene group is For example

[0026] In one embodiment of the present invention, R1 is... The better location is

[0027] In one embodiment of the present invention, R2O- and R3O- may be the same or different.

[0028] In one embodiment of the present invention, the molar ratio of R2 to R3 is 5-0.1:1, preferably 4.5-0.11:1, for example 4:1, 3:1, 2.33:1, 1.5:1, 1:1, 0.67:1, 0.43:1, 0.25:1, 0.11:1.

[0029] It is generally understood by those skilled in the art that R2O- is the residue of R2OH after losing an active hydrogen atom.

[0030] In one embodiment of the present invention, the molecular weight of R2OH is 100-900 g / mol, preferably 300-850 g / mol, for example 560 g / mol or 800 g / mol.

[0031] In one embodiment of the present invention, R2OH is... Where m is any integer from 1 to 20, such as 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 17 or 18.

[0032] In one embodiment of the present invention, R2OH is APEG580 ( m is 12) or APEG800 ( m is 17).

[0033] It is generally understood by those skilled in the art that R3O- is the residue of R3OH after losing an active hydrogen atom.

[0034] In one embodiment of the present invention, the molecular weight of R3OH is 100-900 g / mol, preferably 300-850 g / mol, for example 400 g / mol, 560 g / mol or 800 g / mol.

[0035] In one embodiment of the present invention, R3OH is... Where m is any integer from 1 to 20, such as 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 17 or 18.

[0036] In one embodiment of the present invention, R3OH is... Where p is 1-5 (e.g., 1, 2, 3 or 4), q is 1-5 (e.g., 1, 2, 3 or 4), z is 1-4 (e.g., 1, 2, 3 or 4), and R4 is a C1-4 alkyl group (e.g., methyl or ethyl).

[0037] In one embodiment of the present invention, R3OH is... Wherein, m is 1-5 (e.g., 1, 2, 3 or 4), l is 1-5 (e.g., 1, 2, 3 or 4), x is 1-4 (e.g., 1, 2, 3 or 4), and R5 is a C1-4 alkyl group (e.g., methyl or ethyl).

[0038] In one embodiment of the present invention, R3OH is APEG580 ( m is 12), APEG800 ( m is 17), TMPDE 80 or TMPME

[0039] In one embodiment of the present invention, R3OH is an ether compound, preferably polyethylene glycol monomethyl ether or polypropylene glycol monomethyl ether.

[0040] In some preferred embodiments of the present invention, R3OH is MPEG-580, that is, polyethylene glycol monomethyl ether with a molecular weight of 580.

[0041] In one embodiment of the present invention, n is any positive integer from 1 to 9, such as 1, 2, 3, 4, 5, 6, 7 or 8.

[0042] In some preferred embodiments of the present invention, R1 is The n is any positive integer from 3 to 10, preferably any positive integer from 3 to 8, such as 3, 4, 5, 6, 7 or 8.

[0043] In some preferred embodiments of the present invention, R1 is The n is any positive integer from 3 to 10, preferably any positive integer from 3 to 8, such as 3, 4, 5, 6, 7 or 8. The R2OH or R3OH is APEG580, and the molar ratio of R2OH to R3OH is 5-0.1:1, such as 4.5:1, 4:1, 3:1, 2.33:1, 1.5:1, 1:1, 0.67:1, 0.43:1, 0.25:1, 0.11:1.

[0044] In some preferred embodiments of the present invention, R1 is The n is any positive integer from 3 to 10, preferably any positive integer from 3 to 8, such as 3, 4, 5, 6, 7 or 8. The R2OH or R3OH is APEG800, and the molar ratio of R2OH to R3OH is 5-0.1:1, such as 4.5:1, 4:1, 3:1, 2.33:1, 1.5:1, 1:1, 0.67:1, 0.43:1, 0.25:1, 0.11:1.

[0045] In some preferred embodiments of the present invention, R1 is The n is any positive integer from 3 to 10, preferably any positive integer from 3 to 8, such as 3, 4, 5, 6, 7 or 8. The R2OH is APEG580, the R3OH is TMPDE80, and the molar ratio of R2OH to R3OH is 5-0.1:1, such as 4.5:1, 4:1, 3:1, 2.33:1, 1.5:1, 1:1, 0.67:1, 0.43:1, 0.25:1, 0.11:1.

[0046] In some preferred embodiments of the present invention, R1 is The n is any positive integer from 3 to 10, preferably any positive integer from 3 to 8, such as 3, 4, 5, 6, 7 or 8. The R2OH is APEG580, the R3OH is TMPME, and the molar ratio of R2OH to R3OH is 5-0.1:1, such as 4.5:1, 4:1, 3:1, 2.33:1, 1.5:1, 1:1, 0.67:1, 0.43:1, 0.25:1, 0.11:1.

[0047] In some preferred embodiments of the present invention, R1 is The n is any positive integer from 3 to 10, preferably any positive integer from 3 to 8, such as 3, 4, 5, 6, 7 or 8.

[0048] In some preferred embodiments of the present invention, R1 is The n is any positive integer from 3 to 10, preferably any positive integer from 3 to 8, such as 3, 4, 5, 6, 7 or 8; the R2OH is APEG580, the R3OH is TMPDE80, and the molar ratio of R2OH to R3OH is 5-0.1:1, such as 4.5:1, 4:1, 3:1, 2.33:1, 1.5:1, 1:1, 0.67:1, 0.43:1, 0.25:1, 0.11:1.

[0049] In some preferred embodiments of the present invention, R1 is The n is any positive integer from 3 to 10, preferably any positive integer from 3 to 8, such as 3, 4, 5, 6, 7 or 8.

[0050] In some preferred embodiments of the present invention, R1 is The n is any positive integer from 3 to 10, preferably any positive integer from 3 to 8, such as 3, 4, 5, 6, 7 or 8; the R2OH is APEG580, the R3OH is TMPME, and the molar ratio of R2OH to R3OH is 5-0.1:1, such as 4.5:1, 4:1, 3:1, 2.33:1, 1.5:1, 1:1, 0.67:1, 0.43:1, 0.25:1, 0.11:1.

[0051] In some preferred embodiments of the present invention, R1 is The n is any positive integer from 3 to 10, preferably any positive integer from 3 to 8, such as 3, 4, 5, 6, 7 or 8; the R2OH is APEG580, the R3OH is TMPDE 80, and the molar ratio of R2OH to R3OH is 5-0.1:1, such as 4.5:1, 4:1, 3:1, 2.33:1, 1.5:1, 1:1, 0.67:1, 0.43:1, 0.25:1, 0.11:1.

[0052] In some preferred embodiments of the present invention, R1 is The n is any positive integer from 3 to 10, preferably any positive integer from 3 to 8, such as 3, 4, 5, 6, 7 or 8; the R2OH or R3OH is APEG580, and the molar ratio of R2OH to R3OH is 5-0.1:1, such as 4.5:1, 4:1, 3:1, 2.33:1, 1.5:1, 1:1, 0.67:1, 0.43:1, 0.25:1, 0.11:1.

[0053] In some preferred embodiments of the present invention, R1 is The n is any positive integer from 3 to 10, preferably any positive integer from 3 to 8, such as 3, 4, 5, 6, 7 or 8; the R2OH is APEG580 and the R3OH is MPEG580; the molar ratio of R2OH to R3OH is 5-0.1:1, such as 4.5:1, 4:1, 3:1, 2.33:1, 1.5:1, 1:1, 0.67:1, 0.43:1, 0.25:1, 0.11:1.

[0054] This invention also provides a method for preparing polycarbodiimide, which includes the following steps:

[0055] S1, as shown in Formula IV, undergoes a polycondensation reaction to obtain a prepolymer as shown in Formula III;

[0056] The prepolymer described in S2 first undergoes a first end-capping reaction with R2OH, and then undergoes a second end-capping reaction with R3OH to obtain polycarbodiimide;

[0057]

[0058] The definitions of R1, R2, R3 and n are as described above.

[0059] In S1, as will be understood by those skilled in the art, the polycondensation reaction is generally carried out in the presence of a catalyst.

[0060] The catalyst can be a conventional polycondensation catalyst in the art, preferably an organophosphorus compound, more preferably one or more of 3-methyl-1-phenyl-2-cyclophosphine-1-oxide, 1-ethyl-2-cyclophosphine-1-oxide and 1-methyl-3-chloro-2-cyclophosphine-1-oxide, and even more preferably 3-methyl-1-phenyl-2-cyclophosphine-1-oxide MPPO.

[0061] The amount of catalyst used can be conventional in the art, preferably 200-10000 ppm, for example 2000 ppm, where ppm refers to the mass parts per million of the catalyst relative to the diisocyanate.

[0062] In S1, the temperature of the polycondensation reaction can be conventional in the art, preferably 120-200°C, such as 135°C, 160°C or 180°C.

[0063] In S1, the polycondensation reaction time can be conventional in the art, preferably 5-30h, for example 8h, 10h, 12h, 15h, 20h or 24h.

[0064] In S1, the polycondensation reaction is preferably carried out under a protective atmosphere. The protective atmosphere can be a gas that does not participate in the reaction, which is conventional in the art, and is generally nitrogen or an inert gas.

[0065] In S2, when the R2OH and the R3OH are the same, the temperature of the capping reaction is preferably 80-120°C, for example 100°C.

[0066] In S2, when the R2OH and R3OH are the same, the capping reaction time is preferably 1-3 h, more preferably 1.5-2.5 h, for example 2 h.

[0067] In S2, preferably, the prepolymer first undergoes a first capping reaction with R2OH, and then undergoes a second capping reaction with R3OH.

[0068] The temperature of the first capping reaction is preferably 80-140°C, for example 100°C.

[0069] The first capping reaction time is preferably 0.5-3 hours, for example, 1 hour.

[0070] The temperature of the second capping reaction is preferably 80-140°C, for example 100°C.

[0071] The time for the second capping reaction can be conventional in the art, generally reducing the -NCO- content in the system to 0, for example, 1 hour.

[0072] Preferably, the R2OH is added to the prepolymer by dropwise addition.

[0073] In this invention, the molar ratio of R2OH to the prepolymer is preferably (0.2-2):1, more preferably (0.8-1.2):1, for example 1:1.

[0074] In this invention, the molar ratio of R3OH to the prepolymer shown in formula (3) is preferably (0-1.8):1, more preferably (0.8-1.2):1, for example 1:1.

[0075] The inventors discovered in their research that adding R2OH dropwise yields more polycarbodiimide with one end capped by R2 and the other end capped by R3.

[0076] The present invention also provides a polycarbodiimide prepared by the preparation method described above.

[0077] The present invention also provides the application of the polycarbodiimide as shown in formula (I) as a crosslinking agent in a carboxyl-containing aqueous resin.

[0078] Preferably, the waterborne resin generally includes unsaturated groups, preferably acrylic resin or waterborne polyurethane, such as UCECOAT 7210Allnex.

[0079] The present invention also provides a polycarbodiimide dispersion comprising polycarbodiimide as shown in formula (I) and water.

[0080] In this invention, the amount of water used in the polycarbodiimide dispersion can be conventional in the art, generally making the solid content of the system preferably 30-50%, for example 40%.

[0081] In this invention, the water can be any conventional water in the art, but is preferably deionized water.

[0082] The present invention also provides a method for preparing the polycarbodiimide dispersion as described above, which includes the following steps: dispersing the polycarbodiimide as shown in formula (1) in water.

[0083] The dissolution can be carried out using conventional methods in the art, preferably shear dispersion.

[0084] The present invention also provides an aqueous resin composition comprising the polycarbodiimide dispersion as described above and the aqueous resin as described above.

[0085] In this invention, the polycarbodiimide dispersion is preferably 1-10% by mass in the aqueous resin composition, for example, 5%.

[0086] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0087] The reagents and raw materials used in this invention are all commercially available.

[0088] The positive and progressive effects of this invention are as follows:

[0089] The polycarbodiimide crosslinking agent of the present invention can effectively improve the comprehensive properties of waterborne UV coatings, such as crosslinking density, water resistance, solvent resistance, and mechanical properties. Detailed Implementation

[0090] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0091] The main raw material suppliers, models, and purity information used in the following examples and comparative examples are as follows:

[0092] IPDI was purchased from Wanhua Chemical, and WANNATE IPDI is ≥99.5%;

[0093] HMDI was purchased from Wanhua Chemical, and WANNATE HMDI is ≥99.5%;

[0094] The TMXDI was purchased from Zhanxin, and the CYTEC TMXDI content is ≥99.5%.

[0095] MPPO TCI ≥ 95.0% (RG);

[0096] MPEG-600 was purchased from Kelon Fine Chemicals, with a hydroxyl value of 88-95 mgKOH / g;

[0097] MPEG400 was purchased from Kelon Fine Chemicals, with a hydroxyl value of 132-142 mgKOH / g;

[0098] APEG580 was purchased from Kelon Fine Chemicals. It is a polymer of propylene alcohol and ethylene oxide (polyethylene glycol monoallyl ether), with a hydroxyl value of 88-95 mgKOH / g and an unsaturation degree greater than or equal to 1.52 mmol / g.

[0099] APEG800 was purchased from Kelon Fine Chemicals. It is a polymer of propylene alcohol and ethylene oxide with a hydroxyl value of 66-77 mgKOH / g and an unsaturation degree greater than or equal to 1 mmol / g.

[0100] TMPDE 80 was purchased from Pastor, trimethylolpropane diallyl ether, CAS 682-09-7, hydroxyl value 300 mgKOH / g;

[0101] TMPME was purchased from Pastor, trimethylolpropane monopropylene ether, CAS 682-11-1, hydroxyl value 640 mgKOH / g;

[0102] UCECOAT 7210 Allnex is a water-based, curable (UV / EB) flexible urethane acrylate supplied in water as an emulsion. It is available from Allnex.

[0103] Example 1

[0104] 1000 g of dicyclohexylmethane diisocyanate (HMDI, 3.81 mol) was added to a 5 L three-necked flask under nitrogen protection. 4 g of 3-methyl-1-phenyl-2-cyclophosphide-1-oxide (MPPO) was added, and the reaction was carried out at 160 °C for 15 hours. The NCO% of the system was 9.2%, yielding a carbodiimide prepolymer (874 g, 0.95 mol) with a degree of polymerization of approximately 3. The system temperature was then lowered to 100 °C, and 1102 g of APEG580 (molecular weight 580 g / mol, 1.9 mol) was added. The reaction was carried out for 2 hours, and the NCO% of the system decreased to 0, yielding 1976 g of polycarbodiimide.

[0105] Take 2964g of deionized water and add it to the above polycarbodiimide compound while stirring. Dissolve it completely to obtain a crosslinking agent composition with a solid content of 40%.

[0106] Example 2

[0107] 1000 g of dicyclohexylmethane diisocyanate (HMDI, 3.81 mol) was added to a 5 L three-necked flask under nitrogen protection. 4 g of 3-methyl-1-phenyl-2-cyclophosphide-1-oxide (MPPO) was added, and the reaction was carried out at 160 °C for 15 hours. The NCO% of the system was 9.2%, yielding a carbodiimide prepolymer (874 g, 0.95 mol) with a degree of polymerization of approximately 3. The system temperature was then lowered to 100 °C, and 1520 g of APEG580 (molecular weight 800 g / mol, 1.9 mol) was added. The reaction was carried out for 2 hours, and the NCO% of the system decreased to 0, yielding 2394 g of polycarbodiimide.

[0108] Take 3591g of deionized water and add it to the above polycarbodiimide compound while stirring. Dissolve it completely to obtain a crosslinking agent composition with a solid content of 40%.

[0109] Example 3

[0110] 1000 g of dicyclohexylmethane diisocyanate (HMDI, 3.81 mol) was added to a 5 L three-necked flask under nitrogen protection. 4 g of 3-methyl-1-phenyl-2-cyclophosphine-1-oxide (MPPO) was added, and the mixture was reacted at 160 °C for 15 hours. The NCO% of the system was 9.2%, yielding 874 g (0.95 mol) of carbodiimide prepolymer with a degree of polymerization of approximately 3. The system temperature was lowered to 100 °C, and 551 g of APEG580 (molecular weight 580 g / mol, 0.95 mol) was added. After reacting for 1 hour, 203 g of TMPDE 80 (molecular weight 214 g / mol, 0.95 mol) was added, and the reaction was continued for 1 hour. The NCO% of the system decreased to 0, yielding 1628 g of polycarbodiimide.

[0111] Take 2442g of deionized water and add it to the above polycarbodiimide compound while stirring. Dissolve it completely to obtain a crosslinking agent composition with a solid content of 40%.

[0112] Example 4

[0113] 1000 g of dicyclohexylmethane diisocyanate (HMDI, 3.81 mol) was added to a 5 L three-necked flask under nitrogen protection. 4 g of 3-methyl-1-phenyl-2-cyclophosphine-1-oxide (MPPO) was added, and the mixture was reacted at 160 °C for 15 hours. The NCO% of the system was 9.2%, yielding a carbodiimide prepolymer (874 g, 0.95 mol) with a degree of polymerization of approximately 3. The system temperature was lowered to 100 °C, and 551 g of APEG580 (molecular weight 580 g / mol, 0.95 mol) was added. After reacting for 1 hour, 165 g of TMPME (molecular weight 174 g / mol, 0.95 mol) was added, and the reaction was continued for 1 hour. The NCO% of the system decreased to 0, yielding 1590 g of polycarbodiimide.

[0114] Take 2385g of deionized water and add it to the above polycarbodiimide compound while stirring. Dissolve it completely to obtain a crosslinking agent composition with a solid content of 40%.

[0115] Example 5

[0116] 1000 g of tetramethylphenyl dimethyl diisocyanate (TMXDI, 4.10 mol) was added to a 5 L three-necked flask, and nitrogen gas was purged. Then, 4 g of 3-methyl-1-phenyl-2-cyclophosphine-1-oxide (MPPO) was added. The mixture was reacted at 180 °C for 15 hours. The NCO% of the system was 10.0%, yielding a carbodiimide prepolymer (865 g, 1.03 mol) with a degree of polymerization of about 3.

[0117] The system temperature was lowered to 100℃, 597g of APEG580 (molecular weight 580g / mol, 1.03mol) was added and reacted for 1 hour, then 220g of TMPDE 80 (molecular weight 214g / mol, 1.03mol) was added and reacted for 1 hour. The NCO% of the system decreased to 0, and 1682g of polycarbodiimide was obtained.

[0118] Take 2523g of deionized water and add it to the above polycarbodiimide compound while stirring. Dissolve it completely to obtain a crosslinking agent composition with a solid content of 40%.

[0119] Example 6

[0120] 1000 mol of isophorone diisocyanate (IPDI, 4.50 mol) was added to a 5 L three-necked flask, and nitrogen gas was purged. 4 g of 3-methyl-1-phenyl-2-cyclophosphine-1-oxide (MPPO) was added, and the reaction was carried out at 135 °C for 10 hours. The NCO% was 11.1%, yielding a carbodiimide prepolymer (851 g, 1.1 mol) with a degree of polymerization of about 3.

[0121] The system temperature was lowered to 100℃, 638g of APEG580 (molecular weight 580g / mol, 1.1mol) was added and reacted for 1 hour, then 191g of TMPME (molecular weight 174g / mol, 1.1mol) was added and reacted for 1 hour. The NCO% of the system dropped to 0, and 1680g of polycarbodiimide was obtained.

[0122] Take 2521g of deionized water and add it to the above polycarbodiimide compound while stirring. Dissolve it completely to obtain a crosslinking agent composition with a solid content of 40%.

[0123] Example 7

[0124] 1000 mol of isophorone diisocyanate (IPDI, 4.50 mol) was added to a 5 L three-necked flask, and nitrogen gas was purged. 4 g of 3-methyl-1-phenyl-2-cyclophosphine-1-oxide (MPPO) was added, and the reaction was carried out at 135 °C for 10 hours. The NCO% was 11.1%, yielding a carbodiimide prepolymer (851 g, 1.1 mol) with a degree of polymerization of about 3.

[0125] The system temperature was lowered to 100℃, 638g of APEG580 (molecular weight 580g / mol, 1.1mol) was added and reacted for 1 hour, then 235g of TMPDE 80 (molecular weight 214g / mol, 1.1mol) was added and reacted for 1 hour. The NCO% of the system decreased to 0, and 1724g of polycarbodiimide was obtained.

[0126] Take 2586g of deionized water and add it to the above polycarbodiimide compound while stirring. Dissolve it completely to obtain a crosslinking agent composition with a solid content of 40%.

[0127] Example 8

[0128] 1000 mol of isophorone diisocyanate (IPDI, 4.50 mol) was added to a 5 L three-necked flask, and nitrogen gas was purged. 4 g of 3-methyl-1-phenyl-2-cyclophosphine-1-oxide (MPPO) was added, and the reaction was carried out at 135 °C for 10 hours. The NCO% was 11.1%, yielding a carbodiimide prepolymer (851 g, 1.1 mol) with a degree of polymerization of about 3.

[0129] The system temperature was lowered to 100℃, 1276g of APEG580 (molecular weight 580g / mol, 2.2mol) was added, and the reaction was carried out for 2 hours. The NCO% of the system decreased to 0, and 2127g of polycarbodiimide was obtained.

[0130] Take 3191g of deionized water and add it to the above polycarbodiimide compound while stirring. Dissolve it completely to obtain a crosslinking agent composition with a solid content of 40%.

[0131] Example 9

[0132] 1000 mol of isophorone diisocyanate (IPDI, 4.50 mol) was added to a 5 L three-necked flask, and nitrogen gas was purged. 4 g of 3-methyl-1-phenyl-2-cyclophosphine-1-oxide (MPPO) was added, and the reaction was carried out at 135 °C for 10 hours. The NCO% was 11.1%, yielding a carbodiimide prepolymer (851 g, 1.1 mol) with a degree of polymerization of about 3.

[0133] The system temperature was lowered to 100℃, 638g of APEG580 (molecular weight 580g / mol, 1.1mol) was added and reacted for 1 hour, then 638g of MPEG (molecular weight 580g / mol, 1.1mol) was added and reacted for 2 hours. The NCO% of the system decreased to 0, and 2127g of polycarbodiimide was obtained.

[0134] Take 3191g of deionized water and add it to the above polycarbodiimide compound while stirring. Dissolve it completely to obtain a crosslinking agent composition with a solid content of 40%.

[0135] Example 10

[0136] 1000 mol of isophorone diisocyanate (IPDI, 4.50 mol) was added to a 5 L three-necked flask, and nitrogen gas was purged. 4 g of 3-methyl-1-phenyl-2-cyclophosphine-1-oxide (MPPO) was added, and the reaction was carried out at 135 °C for 10 hours. The NCO% was 11.1%, yielding a carbodiimide prepolymer (851 g, 1.1 mol) with a degree of polymerization of about 3.

[0137] The system temperature was lowered to 100℃, 1021g of APEG580 (molecular weight 580g / mol, 1.76mol) was added and reacted for 1 hour, then 94g of TMPDE 80 (molecular weight 214g / mol, 0.44mol) was added and reacted for 1 hour. The NCO% of the system decreased to 0, and 1966g of polycarbodiimide was obtained.

[0138] Take 2949g of deionized water and add it to the above polycarbodiimide compound while stirring. Dissolve it completely to obtain a crosslinking agent composition with a solid content of 40%.

[0139] Example 11

[0140] 1000 mol of isophorone diisocyanate (IPDI, 4.50 mol) was added to a 5 L three-necked flask, and nitrogen gas was purged. 4 g of 3-methyl-1-phenyl-2-cyclophosphine-1-oxide (MPPO) was added, and the reaction was carried out at 135 °C for 10 hours. The NCO% was 11.1%, yielding a carbodiimide prepolymer (851 g, 1.1 mol) with a degree of polymerization of about 3.

[0141] The system temperature was lowered to 100℃, 893g of APEG580 (molecular weight 580g / mol, 1.54mol) was added and reacted for 1 hour, then 141g of TMPDE 80 (molecular weight 214g / mol, 0.66mol) was added and reacted for 1 hour. The NCO% of the system decreased to 0, and 1885g of polycarbodiimide was obtained.

[0142] Take 2828g of deionized water and add it to the above polycarbodiimide compound while stirring. Dissolve it completely to obtain a crosslinking agent composition with a solid content of 40%.

[0143] Example 12

[0144] 1000 mol of isophorone diisocyanate (IPDI, 4.50 mol) was added to a 5 L three-necked flask, and nitrogen gas was purged. 4 g of 3-methyl-1-phenyl-2-cyclophosphine-1-oxide (MPPO) was added, and the reaction was carried out at 135 °C for 10 hours. The NCO% was 11.1%, yielding a carbodiimide prepolymer (851 g, 1.1 mol) with a degree of polymerization of about 3.

[0145] The system temperature was lowered to 100℃, 766g of APEG580 (molecular weight 580g / mol, 1.32mol) was added and reacted for 1 hour, then 188g of TMPDE 80 (molecular weight 214g / mol, 0.88mol) was added and reacted for 1 hour. The NCO% of the system decreased to 0, and 1775g of polycarbodiimide was obtained.

[0146] Take 2663g of deionized water and add it to the above polycarbodiimide compound while stirring. Dissolve it completely to obtain a crosslinking agent composition with a solid content of 40%.

[0147] Example 13

[0148] 1000 mol of isophorone diisocyanate (IPDI, 4.50 mol) was added to a 5 L three-necked flask, and nitrogen gas was purged. 4 g of 3-methyl-1-phenyl-2-cyclophosphine-1-oxide (MPPO) was added, and the reaction was carried out at 135 °C for 10 hours. The NCO% was 11.1%, yielding a carbodiimide prepolymer (851 g, 1.1 mol) with a degree of polymerization of about 3.

[0149] The system temperature was lowered to 100℃, 510g of APEG580 (molecular weight 580g / mol, 0.88mol) was added and reacted for 1 hour, then 282g of TMPDE 80 (molecular weight 214g / mol, 1.32mol) was added and reacted for 1 hour. The NCO% of the system decreased to 0, and 1643g of polycarbodiimide was obtained.

[0150] Take 2465g of deionized water and add it to the above polycarbodiimide compound while stirring. Dissolve it completely to obtain a crosslinking agent composition with a solid content of 40%.

[0151] Example 14

[0152] 1000 mol of isophorone diisocyanate (IPDI, 4.50 mol) was added to a 5 L three-necked flask, and nitrogen gas was purged. 4 g of 3-methyl-1-phenyl-2-cyclophosphine-1-oxide (MPPO) was added, and the reaction was carried out at 135 °C for 10 hours. The NCO% was 11.1%, yielding a carbodiimide prepolymer (851 g, 1.1 mol) with a degree of polymerization of about 3.

[0153] The system temperature was lowered to 100℃, 383g of APEG580 (molecular weight 580g / mol, 0.66mol) was added and reacted for 1 hour, then 330g of TMPDE 80 (molecular weight 214g / mol, 1.54mol) was added and reacted for 1 hour. The NCO% of the system decreased to 0, and 1564g of polycarbodiimide was obtained.

[0154] Take 2346g of deionized water and add it to the above polycarbodiimide compound while stirring. Dissolve it completely to obtain a crosslinking agent composition with a solid content of 40%.

[0155] Example 15

[0156] 1000 mol of isophorone diisocyanate (IPDI, 4.50 mol) was added to a 5 L three-necked flask, and nitrogen gas was purged. 4 g of 3-methyl-1-phenyl-2-cyclophosphine-1-oxide (MPPO) was added, and the reaction was carried out at 135 °C for 10 hours. The NCO% was 11.1%, yielding a carbodiimide prepolymer (851 g, 1.1 mol) with a degree of polymerization of about 3.

[0157] The system temperature was lowered to 100℃, 255g of APEG580 (molecular weight 580g / mol, 0.44mol) was added and reacted for 1 hour, then 377g of TMPDE 80 (molecular weight 214g / mol, 1.76mol) was added and reacted for 1 hour. The NCO% of the system decreased to 0, and 1483g of polycarbodiimide was obtained.

[0158] Take 2225g of deionized water and add it to the above polycarbodiimide compound while stirring. Dissolve it completely to obtain a crosslinking agent composition with a solid content of 40%.

[0159] Example 16

[0160] 1000 mol of isophorone diisocyanate (IPDI, 4.50 mol) was added to a 5 L three-necked flask, and nitrogen gas was purged. 4 g of 3-methyl-1-phenyl-2-cyclophosphine-1-oxide (MPPO) was added, and the reaction was carried out at 135 °C for 10 hours. The NCO% was 11.1%, yielding a carbodiimide prepolymer (851 g, 1.1 mol) with a degree of polymerization of about 3.

[0161] The system temperature was lowered to 100℃, 128g of APEG580 (molecular weight 580g / mol, 0.22mol) was added and reacted for 1 hour, then 424g of TMPDE 80 (molecular weight 214g / mol, 1.98mol) was added and reacted for 1 hour. The NCO% of the system decreased to 0, and 1403g of polycarbodiimide was obtained.

[0162] Take 2105g of deionized water and add it to the above polycarbodiimide compound while stirring. Dissolve it completely to obtain a crosslinking agent composition with a solid content of 40%.

[0163] Comparative Example 1

[0164] 1000 g of dicyclohexylmethane diisocyanate (HMDI, 3.81 mol) was added to a 5 L three-necked flask under nitrogen protection. 4 g of 3-methyl-1-phenyl-2-cyclophosphine-1-oxide (MPPO) was then added. The reaction was carried out at 160 °C for 15 hours, yielding a carbodiimide prepolymer (874 g, 0.95 mol) with a degree of polymerization of approximately 3. The system temperature was then lowered to 100 °C, and 1140 g of polyethylene glycol monomethyl ether (MPEG-600, molecular weight 600 g / mol, 1.9 mol) was added. The reaction was continued for 2 hours, until the NCO% of the system decreased to 0, yielding 2014 g of polycarbodiimide.

[0165] Take 3021g of deionized water and add it to the above polycarbodiimide compound while stirring. Dissolve it completely to obtain a crosslinking agent composition with a solid content of 40%.

[0166] Comparative Example 2

[0167] 1000 g of dicyclohexylmethane diisocyanate (HMDI, 3.81 mol) was added to a 5 L three-necked flask under nitrogen protection. 4 g of 3-methyl-1-phenyl-2-cyclophosphide-1-oxide (MPPO) was added, and the reaction was carried out at 160 °C for 15 hours. The NCO% of the system was 9.2%, yielding a carbodiimide prepolymer (874 g, 0.95 mol) with a degree of polymerization of approximately 3. The system temperature was lowered to 120 °C, and 370 g of cetyl alcohol (molecular weight 242 g / mol, 1.53 mol) was slowly added dropwise over half an hour. After 1 hour of reaction, the NCO% of the system decreased to 1.29%. 153 g of polyethylene glycol monomethyl ether (MPEG-400, molecular weight 400 g / mol, 0.38 mol) was then added, and the reaction was continued for 2 hours. The NCO% of the system decreased to 0, yielding 1397 g of polycarbodiimide compound.

[0168] Take 2095g of deionized water and add it to the above polycarbodiimide compound while stirring. Dissolve it completely to obtain a crosslinking agent composition with a solid content of 40%.

[0169] Example 1

[0170] The performance of each crosslinking agent was tested using a UCECOAT 7210 Allnex.

[0171] The evaluation method for crosslinking density is as follows: The crosslinking agent compositions prepared in Comparative Examples 1-2 and Examples 1-16 were added to UCECOAT 7210 Allnex at a mass ratio of 5% and mixed evenly to obtain an emulsion. 5 ± 0.1 g of the emulsion was weighed into a PTFE dish to form a complete liquid film. The film was then placed in a UV curing lamp box (wavelength 365 nm, light intensity 756 mJ / cm²). 2Expose the coating to a PTFE dish for 2 minutes to cure, then dry it in a 120℃ oven for 2 minutes. Remove the completely dried and cured coating from the PTFE dish and cut it into small cubes of roughly equal shape and size. Weigh 'a' of a 200-mesh stainless steel wire mesh, add 'b' of the coating sample, wrap it up, and extract using a Soxhlet extractor with toluene as solvent for 3 hours under reflux. Dry the stainless steel wire mesh in an oven and weigh the total weight 'c'. Calculate the gelation rate = 100% * (ca) / b. A higher gelation rate indicates a higher cross-linking density and better performance.

[0172] The method for evaluating water resistance is as follows: The crosslinking agent compositions prepared in Comparative Examples 1-2 and Examples 1-16 were added to UCECOAT 7210 Allnex at a mass ratio of 5% and mixed evenly to obtain an emulsion. 5 ± 0.1 g of the emulsion was weighed into a PTFE dish to form a complete liquid film. The film was then placed in a UV curing lamp box (wavelength 365 nm, light intensity 756 mJ / cm²). 2 Expose and cure in a PTFE dish for 2 minutes, then dry in a 120℃ forced-air oven for 2 minutes. Remove the completely dried and cured coating from the PTFE dish and cut it into small cubes of roughly equal shape and size. Place them in deionized water, and observe their water absorption state after 24 hours. Record the weight change of the film; m1 and m2 are the weights of the film before and after water absorption, respectively. The water absorption rate of the film is calculated using the following formula: Water absorption rate = (m2 - m1) / m1 × 100%. A lower water absorption rate indicates better water resistance.

[0173] The abrasion resistance evaluation method is as follows: The crosslinking agent compositions prepared in Comparative Examples 1-2 and Examples 1-16 were added to UCECOAT 7210 Allnex at a mass ratio of 5% and mixed evenly to obtain an emulsion. The emulsion was evenly coated onto a PET board using a wire rod, with a coating thickness of 20 μm. The board was then placed in a UV curing lamp box (wavelength 365 nm, light intensity 756 mJ / cm²). 2 Expose and cure for 2 minutes, then dry in a 120℃ forced-air oven for 2 minutes. Dry abrasion 1000 times (dry abrasion force, 500g) using a TABER abrasion tester, and visually inspect the wear of the coating on the test surface under good lighting. There are 6 grades, from grade 5 to grade 0, with grade 0 being the worst.

[0174] The evaluation method for mechanical properties is as follows: The crosslinking agent compositions prepared in Comparative Examples 1-2 and Examples 1-16 were added to UCECOAT 7210 Allnex at a mass ratio of 5% and mixed evenly to obtain an emulsion. 5 ± 0.1 g of the emulsion was weighed into a PTFE dish to form a complete liquid film. The film was then placed in a UV curing lamp box (wavelength 365 nm, light intensity 756 mJ / cm²). 2Expose and cure in a PTFE dish for 2 minutes, then dry in a 120℃ forced-air oven for 2 minutes. Remove the completely dried and cured coating from the PTFE dish, shape it into a 25mm×4mm dumbbell, and test its tensile strength at room temperature using a SANS microcomputer-controlled electronic universal testing machine at a tensile speed of 200mm / min. Take three measurements and average the results.

[0175] The test results are shown in Table 1.

[0176] Table 1

[0177]

[0178]

[0179] As can be seen from Examples 1-4, the overall effect of Examples 1-2, which used a single capping agent, was inferior to that of Examples 3-4, which used a combination of two different capping agents. Compared with Examples 4, Example 3 showed the best product performance when the ratio of capping agents APEG580 and TMPDE 80 was 1:1.

[0180] Examples 3, 5, and 7 all used APEG580 and TMPDE 80 in a 1:1 ratio as capping agents. Example 7 showed the best performance, followed by Examples 3 and 5. This demonstrates that using the monomer IPDI is superior to HMDI and TMXDI.

[0181] The crosslinking agent compositions in Examples 6-16 all use IPDI as a monomer, the difference being the use of different end-capping agents.

[0182] Among them, in Examples 6-8, the effect of Example 8, which uses a single end-capping agent, is generally worse than that of Examples 6-7, which use a combination of two different end-capping agents.

[0183] Examples 10-16 all used APEG580 and TMPDE 80 as end-capping agents. As the ratio of APEG580 to TMPDE 80 increased, the crosslinking density and water absorption of the crosslinking composition first improved and then deteriorated. Among them, Examples 13-15 showed better overall performance.

[0184] Compared with Comparative Examples 1-2, the addition of the crosslinking agent of the present invention (Examples 1-16) improves the crosslinking density, water resistance, abrasion resistance and tensile strength of waterborne UV resin.

Claims

1. A polycarbodiimide, characterized in that, Its compounds are as shown in Formula I: ； Where R1 is C 1-18 alkylene groups or -L1-L2-L3-; L1 is C 3-13 Cycloalkylene, C 1-4 Alkylene groups may not be present; L2 is C 1-4 alkylene or C 6-10 Alpha-aryl; L3 is C 3-13 Cycloalkylene, with one or more C 1-4 alkyl-substituted C 3-13 Cycloalkylene or C 1-4 Alkylene; R2O- is the residue after removing a hydrogen atom from a hydrophilic compound containing an unsaturated double bond and active hydrogen; its molecular weight is less than 1000 g / mol; the hydrophilic compound is R2OH, and R2OH is... , where m is any integer from 10 to 20; R3O- is the residue after removing a hydrogen atom from a hydrophilic compound containing an unsaturated double bond and active hydrogen; its molecular weight is less than 1000 g / mol; the hydrophilic compound is R3OH, and R3OH is an ether compound; R3OH is Where m is any integer from 1 to 20; or, R3OH is Where p is 1-5, q is 1-5, z is 1-4, and R4 is a C1-4 alkyl group; or, R3OH is... Where m is 1-5, l is 1-5, x is 1-4, and R5 is a C1-4 alkyl group; n is 1-10.

2. The polycarbodiimide as described in claim 1, characterized in that, The compounds represented by Formula I satisfy one or more of the following conditions: (1) In R1, the C mentioned 1-18 The alkylene group is C 1-6 Alkylene; (2) In L1, the C mentioned 3-13 The cycloalkylene group is cyclopropylene, cyclopropylbutylene, cyclopentylene, or cyclohexylene; (3) In L1, the C mentioned 1-4 The alkylene group is , , , , , or ; (4) In L2, the C mentioned 1-4 The alkylene group is methylene. , , , , or ; (5) In L2, the C mentioned 6-10 The aryl group is , or ; (6) In L3, the C mentioned 3-13 The cycloalkylene group is cyclopropylene, cyclopropylbutylene, cyclopentylene, or cyclohexylene; (7) In L3, the one or more C 1-4 alkyl-substituted C 3-13 C in cycloalkylene 3-13 The cycloalkylene group is cyclopropylene, cyclopropylbutylene, cyclopentylene, or cyclohexylene; (8) In L3, the one or more C 1-4 alkyl-substituted C 3-13 C in cycloalkylene 1-4 The alkyl group is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, or tert-butyl; (9) In L3, the one or more C 1-4 alkyl-substituted C 3-13 The cyclohexene group is a methyl-substituted cyclohexene group; and, (10) In L3, the C mentioned 1-4 The alkylene group is , , , , , or .

3. The polycarbodiimide as described in claim 2, characterized in that, The compounds represented by Formula I satisfy one or more of the following conditions: (1) In R1, the C mentioned 1-18 The alkylene group is methylene. , , , , , or ; (2) In L1, the C mentioned 3-13 The cycloalkylene group is ; (3) In L1, the C mentioned 1-4 The alkylene group is or ; (4) In L2, the C mentioned 1-4 The alkylene group is methylene; (5) In L3, the C mentioned 3-13 The cycloalkylene group is ; (6) In L3, the one or more C 1-4 alkyl-substituted C 3-13 C in cycloalkylene 3-13 The cycloalkylene group is ; (7) In L3, the one or more C 1-4 alkyl-substituted C 3-13 C in cycloalkylene 1-4 The alkyl group is methyl; (8) In L3, the one or more C 1-4 alkyl-substituted C 3-13 The cycloalkylene group is ;and, (9) In L3, the C mentioned 1-4 The alkylene group is or .

4. The polycarbodiimide as described in claim 3, characterized in that, In R1, the C 1-18 The alkylene group is .

5. The polycarbodiimide as described in claim 1, characterized in that, The compounds represented by Formula I satisfy one or more of the following conditions: (1) n is any positive integer from 1 to 9; (2) R1 is , , or ; (3) The molar ratio of R2 to R3 is 5-0.1:1; (4) The molecular weight of R2OH is 560-900 g / mol; (5) In R2OH, m is 11, 12, 13, 15, 17 or 18; (6) The molecular weight of R3OH is 100-900 g / mol.

6. The polycarbodiimide as described in claim 5, characterized in that, The compounds represented by Formula I satisfy one or more of the following conditions: (1) n is 1, 2, 3, 4, 5, 6, 7 or 8; (2) The molar ratio of R2 to R3 is 4.5-0.11:1; (3) The molecular weight of R2OH is 560-850 g / mol; (4) The molecular weight of R3OH is 300-850 g / mol; and, (5) R3OH is , where m is 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 17 or 18.

7. The polycarbodiimide as described in claim 6, characterized in that, The compounds represented by Formula I satisfy one or more of the following conditions: (1) The molar ratio of R2 to R3 is 4:1, 3:1, 2.33:1, 1.5:1, 1:1, 0.67:1, 0.43:1, 0.25:1, 0.11:1; (2) The molecular weight of R2OH is 800 g / mol; (3) The molecular weight of R3OH is 400 g / mol, 560 g / mol or 800 g / mol.

8. The polycarbodiimide as described in claim 1, characterized in that, In the compound shown in Formula I, R2OH is APEG580 or APEG800.

9. The polycarbodiimide as described in claim 8, characterized in that, In the compound shown in Formula I, R3OH is APEG580, APEG800, TMPDE 80 or TMPME.

10. The polycarbodiimide according to claim 1, characterized in that, The compound represented by Formula I satisfies any one of the following conditions: (1) R1 is The n is any positive integer from 3 to 10; (2) R1 is The n is any positive integer from 3 to 10, the R2OH or R3OH is APEG580, and the molar ratio of R2OH to R3OH is 5-0.1:1; (3) R1 is The n is any positive integer from 3 to 10, the R2OH or R3OH is APEG800, and the molar ratio of R2OH to R3OH is 5-0.1:1; (4) R1 is The n is any positive integer from 3 to 10, the R2OH is APEG580, the R3OH is TMPDE 80, and the molar ratio of R2OH to R3OH is 5-0.1:1; (5) R1 is The n is any positive integer from 3 to 10, the R2OH is APEG580, the R3OH is TMPME, and the molar ratio of R2OH to R3OH is 5-0.1:1; (6) R1 is The n is any positive integer from 3 to 10; (7) R1 is The n is any positive integer from 3 to 10; the R2OH is APEG580, the R3OH is TMPDE 80, and the molar ratio of R2OH to R3OH is 5-0.1:1; (8) R1 is The n is any positive integer from 3 to 10; (9) R1 is The n is any positive integer from 3 to 10; the R2OH is APEG580, the R3OH is TMPME, and the molar ratio of R2OH to R3OH is 5-0.1:1; (10) R1 is The n is any positive integer from 3 to 10; the R2OH is APEG580, the R3OH is TMPDE 80, and the molar ratio of R2OH to R3OH is 5-0.1:1; (11) R1 is The n is any positive integer from 3 to 10; the R2OH or R3OH is APEG580, and the molar ratio of R2OH to R3OH is 5-0.1:

1.

11. The polycarbodiimide as claimed in claim 10, characterized in that, The compound represented by Formula I satisfies any one of the following conditions: (1) R1 is The n is any positive integer from 3 to 8; (2) R1 is The n is any positive integer from 3 to 8, the R2OH or R3OH is APEG580, and the molar ratio of R2OH to R3OH is 5-0.1:1; (3) R1 is The n is any positive integer from 3 to 8, the R2OH or R3OH is APEG800, and the molar ratio of R2OH to R3OH is 5-0.1:1; (4) R1 is The n is any positive integer from 3 to 8, the R2OH is APEG580, the R3OH is TMPDE 80, and the molar ratio of R2OH to R3OH is 5-0.1:1; (5) R1 is The n is any positive integer from 3 to 8, the R2OH is APEG580, the R3OH is TMPME, and the molar ratio of R2OH to R3OH is 5-0.1:1; (6) R1 is The n is any positive integer from 3 to 8; (7) R1 is The n is any positive integer from 3 to 8; the R2OH is APEG580, the R3OH is TMPDE 80, and the molar ratio of R2OH to R3OH is 5-0.1:1; (8) R1 is The n is any positive integer from 3 to 8; (9) R1 is The n is any positive integer from 3 to 8; the R2OH is APEG580, the R3OH is TMPME, and the molar ratio of R2OH to R3OH is 5-0.1:

1. (10) R1 is The n is any positive integer from 3 to 8; the R2OH is APEG580, the R3OH is TMPDE 80, and the molar ratio of R2OH to R3OH is 5-0.1:1; (11) R1 is The n is any positive integer from 3 to 8; the R2OH or R3OH is APEG580, and the molar ratio of R2OH to R3OH is 5-0.1:

1.

12. The polycarbodiimide as claimed in claim 11, characterized in that, The compound represented by Formula I satisfies any one of the following conditions: (1) R1 is The n is 3, 4, 5, 6, 7 or 8; (2) R1 is The n is 3, 4, 5, 6, 7 or 8, the R2OH or R3OH is APEG580, and the molar ratio of R2OH to R3OH is 4.5:1, 4:1, 3:1, 2.33:1, 1.5:1, 1:1, 0.67:1, 0.43:1, 0.25:1, 0.11:1; (3) R1 is The n is 3, 4, 5, 6, 7 or 8, the R2OH or R3OH is APEG800, and the molar ratio of R2OH to R3OH is 4.5:1, 4:1, 3:1, 2.33:1, 1.5:1, 1:1, 0.67:1, 0.43:1, 0.25:1, or 0.11:

1. (4) R1 is The n is 3, 4, 5, 6, 7 or 8, the R2OH is APEG580, the R3OH is TMPDE 80, and the molar ratio of R2OH to R3OH is 4.5:1, 4:1, 3:1, 2.33:1, 1.5:1, 1:1, 0.67:1, 0.43:1, 0.25:1, or 0.11:

1. (5) R1 is The n is 3, 4, 5, 6, 7 or 8, the R2OH is APEG580, the R3OH is TMPME, and the molar ratio of R2OH to R3OH is 4.5:1, 4:1, 3:1, 2.33:1, 1.5:1, 1:1, 0.67:1, 0.43:1, 0.25:1, or 0.11:

1. (6) R1 is The n is 3, 4, 5, 6, 7 or 8; (7) R1 is The n is 3, 4, 5, 6, 7 or 8; the R2OH is APEG580, the R3OH is TMPDE80, and the molar ratio of R2OH to R3OH is 4.5:1, 4:1, 3:1, 2.33:1, 1.5:1, 1:1, 0.67:1, 0.43:1, 0.25:1, or 0.11:

1. (8) R1 is The n is 3, 4, 5, 6, 7 or 8; (9) R1 is The n is 3, 4, 5, 6, 7 or 8; the R2OH is APEG580, the R3OH is TMPME, and the molar ratio of R2OH to R3OH is 4.5:1, 4:1, 3:1, 2.33:1, 1.5:1, 1:1, 0.67:1, 0.43:1, 0.25:1, or 0.11:

1. (10) R1 is The n is 3, 4, 5, 6, 7 or 8; the R2OH is APEG580, the R3OH is TMPDE80, and the molar ratio of R2OH to R3OH is 4.5:1, 4:1, 3:1, 2.33:1, 1.5:1, 1:1, 0.67:1, 0.43:1, 0.25:1, or 0.11:

1. (11) R1 is The n is 3, 4, 5, 6, 7 or 8; the R2OH or R3OH is APEG580, and the molar ratio of R2OH to R3OH is 4.5:1, 4:1, 3:1, 2.33:1, 1.5:1, 1:1, 0.67:1, 0.43:1, 0.25:1 or 0.11:

1.

13. A method for preparing polycarbodiimide according to any one of claims 1-12, characterized in that, It includes the following steps: S1 The diisocyanate shown in Formula IV undergoes a polycondensation reaction to obtain the prepolymer shown in Formula III; The prepolymer described in S2 first undergoes a first end-capping reaction with R2OH, and then undergoes a second end-capping reaction with R3OH to obtain polycarbodiimide; ； The definitions of R1, R2, R3 and n are as described in any one of claims 1-12.

14. The use of polycarbodiimide as a crosslinking agent in carboxyl-containing aqueous resins, as described in any one of claims 1-12.

15. The application of polycarbodiimide as a crosslinking agent as described in claim 14 in carboxyl-containing aqueous resins, characterized in that, The waterborne resin is an acrylic resin or a waterborne polyurethane.

16. The application of polycarbodiimide as a crosslinking agent as described in claim 15 in carboxyl-containing aqueous resins, characterized in that, The aqueous resin is UCECOAT 7210 Allnex.

17. A polycarbodiimide dispersion, characterized in that, It comprises polycarbodiimide as described in any one of claims 1-12 and water.

18. The polycarbodiimide dispersion as described in claim 17, characterized in that, The solid content in the polycarbodiimide dispersion is 30-50%.

19. The polycarbodiimide dispersion as described in claim 18, characterized in that, The polycarbodiimide dispersion has a solid content of 40%.

20. A method for preparing a polycarbodiimide dispersion as described in any one of claims 17-19, characterized in that, It includes the following steps: dispersing the polycarbodiimide in water.

21. A water-based resin composition, characterized in that, It includes the polycarbodiimide dispersion and the aqueous resin as described in any one of claims 17-19.

22. The aqueous resin composition according to claim 21, characterized in that, The polycarbodiimide dispersion is 1-10% by mass in the aqueous resin composition; the aqueous resin is an acrylic resin or an aqueous polyurethane.

23. The aqueous resin composition according to claim 22, characterized in that, The polycarbodiimide dispersion is 5% by mass in the aqueous resin composition; the aqueous resin is UCECOAT 7210 Allnex.

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