WO2025108924A1

WO2025108924A1 - Water-dispersible blocked isocyanate prepolymer system, method for preparing the same, and application thereof

Info

Publication number: WO2025108924A1
Application number: PCT/EP2024/082809
Authority: WO
Inventors: Hongchao Li; Dongming Wu; Chenyu Zheng; Jiapei LIU
Original assignee: Covestro Deutschland AG
Current assignee: Covestro Deutschland AG
Priority date: 2023-11-21
Filing date: 2024-11-19
Publication date: 2025-05-30
Anticipated expiration: 2026-05-21

Abstract

The present application relates to a water-dispersible blocked isocyanate prepolymer system, a method for preparing the same, and an application thereof. The blocked isocyanate prepolymer system is prepared by reaction of an isocyanate comprising two or more isocyanate groups, a blocking agent, a non-hydrophilic polyhydroxyl compound and an active hydrogen compound comprising a hydrophilic group. The blocked isocyanate prepolymer system of the present invention is water- dispersible, and can be processed into various products for a wide range of applications.

Description

WATER-DISPERSIBLE BLOCKED ISOCYANATE PREPOLYMER SYSTEM, METHOD FOR PREPARING THE SAME, AND APPLICATION THEREOF

TECHNICAL FIELD

The present invention relates to the technical field of isocyanate. In particular, the present invention relates to a water-dispersible blocked isocyanate prepolymer system, a method for preparing the same, and an application thereof.

BACKGROUND ART

Epoxy resins are widely used in machinery, home appliances, transportation, and construction fields and the like, due to their good thermal stability, excellent adhesiveness and adhesion, and chemical resistance. However, epoxy systems are brittle, especially the case under low temperatures. To improve and enhance their flexibility, polyurethane may be incorporated to achieve desirable and long-lasting elastification of epoxy resins.

CN115427472 discloses a blocked isocyanate prepolymer obtained by using a blocking agents comprising cardanol and cardol can be used to improve and enhance impact resistance, shock resistance, and flexibility of epoxy resin systems.

Due to the structural characteristics of epoxy resins per se, waterborne epoxy resins form a highly cross-linked rigid network structure after curing, which may still lead to unsatisfactory impact resistance, shock resistance, and flexibility of the final product. CN109651922 discloses improving mechanical properties of waterborne epoxy resins by introducing a waterborne polyurethane dispersion comprising active hydrogen. CN110845938 discloses using a rubber-modified waterborne polyurethane as a toughening agent of waterborne epoxy resins. CN108949000 discloses preparing a water-dispersible polyurethane-epoxy resin by reacting a water-dispersible resin first with cardanol and epoxy vegetable oil, and then with diisocyanate, and finally with a hydrophilic diol. The prior art mostly achieves toughening by using a polyurethane comprising active hydrogen or by introducing a polyurethane segment without active functional groups. There are no reports about a waterborne epoxy toughening agent comprising potential isocyanate active functional groups. For example, the blocked isocyanate prepolymer disclosed in CN115427472 cannot be applied to a waterborne epoxy resin system, as it cannot be dispersed in the aqueous phase. Therefore, there is a need for a water-dispersible blocked isocyanate prepolymer system in the art.

SUMMARY OF THE INVENTION

One objective of the present invention is to provide a water-dispersible blocked isocyanate prepolymer system.

Another objective of the present invention is to provide a method for preparing a water-dispersible blocked isocyanate prepolymer system.

Therefore, according to a first aspect of the present invention, there is provided a water-dispersible blocked isocyanate prepolymer system, characterized in that: it is prepared by reaction of an isocyanate comprising two or more isocyanate groups, a blocking agent, a non-hydrophilic polyhydroxyl compound, and an active hydrogen compound comprising a hydrophilic group, wherein the molar ratio of the non-hydrophilic polyhydroxyl compound to the active hydrogen compound comprising a hydrophilic group is in a range of 0.1 to 25.0, the molar ratio of all of the groups in the non-hydrophilic polyhydroxyl compound and the active hydrogen compound comprising a hydrophilic group that can react with the isocyanate to all isocyanate groups of the isocyanate is in a range of 0.30 to 0.80, and the molar ratio of all of the groups in the non-hydrophilic polyhydroxyl compound, the active hydrogen compound comprising a hydrophilic group and the blocking agent that can react with the isocyanate to all isocyanate groups of the isocyanate is in a range of 0.90 to 1.10.

According to a second aspect of the present invention, there is provided a method for preparing the above-mentioned water-dispersible blocked isocyanate prepolymer system, comprising the steps of:

A. reacting an isocyanate comprising two or more isocyanate groups with a blocking agent to obtain a partially blocked isocyanate intermediate; and

B. reacting the resulting partially blocked isocyanate intermediate with an active hydrogen compound comprising a hydrophilic group and a non-hydrophilic polyhydroxyl compound until the amount of free isocyanate groups is less than 0.5% by weight, preferably less than 0.2% by weight, more preferably less than 0.1% by weight, relative to the total weight of the entire reaction system, to obtain a water- dispersible blocked isocyanate prepolymer system. According a third aspect of the present invention, there is provided a method for preparing the above-mentioned water-dispersible blocked isocyanate prepolymer system, comprising the steps of: reacting an isocyanate comprising two or more isocyanate groups first with a non- hydrophilic polyhydroxyl compound and an active hydrogen compound comprising a hydrophilic group, and then with a blocking agent, until the amount of free isocyanate groups is less than 0.5 % by weight, preferably less than 0.2 % by weight, more preferably less than 0.1 % by weight, to obtain a water-dispersible blocked isocyanate prepolymer system.

According a fourth aspect of the present invention, there is provided a blocked isocyanate prepolymer aqueous dispersion prepared from the above-mentioned water- dispersible blocked isocyanate prepolymer system.

According to a fifth aspect of the present invention, there is provided use of the above-mentioned water-dispersible blocked isocyanate prepolymer system or blocked isocyanate prepolymer aqueous dispersion for preparing polyurethane plastics, adhesives, sealing materials, encapsulating materials, fiber sizing materials or coating materials.

According to a sixth aspect of the present invention, there are provided polyurethane plastics, adhesives, sealing materials, encapsulating materials, fiber sizing materials or coating materials comprising the above-mentioned water- dispersible blocked isocyanate prepolymer system.

The blocked isocyanate prepolymer system of the present invention is water- dispersible, and can be processed into various products for a wide range of applications.

DETAILED DESCRIPTION OF THE INVENTION

Some specific embodiments of the present invention will be described below for the purpose of illustration rather than limitation.

Water-dispersible Blocked Isocyanate Prepolymer System

According to a first aspect of the present invention, there is provided a water- dispersible blocked isocyanate prepolymer system, characterized in that: it is prepared by reaction of an isocyanate comprising two or more isocyanate groups, a blocking agent, a non-hydrophilic polyhydroxyl compound, and an active hydrogen compound comprising a hydrophilic group, wherein the molar ratio of the non-hydrophilic polyhydroxyl compound to the active hydrogen compound comprising a hydrophilic group is in a range of 0.1 to 25.0, the molar ratio of all of the groups in the non-hydrophilic polyhydroxyl compound and the active hydrogen compound comprising a hydrophilic group that can react with the isocyanate to all isocyanate groups of the isocyanate is in a range of 0.30 to 0.80, and the molar ratio of all of the groups in the non-hydrophilic polyhydroxyl compound, the active hydrogen compound comprising a hydrophilic group and the blocking agent that can react with the isocyanate to all isocyanate groups of the isocyanate is in a range of 0.90 to 1.10.

The molar ratio of the non-hydrophilic polyhydroxyl compound to the active hydrogen compound comprising a hydrophilic group is preferably in a range of 0.1 to 23.0, more preferably in a range of 0.2 to 15.0.

All isocyanate groups of the isocyanate refer to all those contained in an isocyanate comprising two or more isocyanate groups prior to reaction with a non- hydrophilic polyhydroxyl compound or an active hydrogen compound comprising a hydrophilic group or an blocking agent.

The molar ratio of all of the groups in the non-hydrophilic polyhydroxyl compound and the active hydrogen compound comprising a hydrophilic group that can react with the isocyanate to all isocyanate groups of the isocyanate is preferably in a range of 0.40 to 0.60, more preferably in a range of 0.45 to 0.55.

The molar ratio of all of the groups in the non-hydrophilic polyhydroxyl compound, the active hydrogen compound comprising a hydrophilic group and the blocking agent that can react with the isocyanate to all isocyanate groups of the isocyanate is in a range of 0.95 to 1.05.

The blocked isocyanate prepolymer of the present invention is water-dispersible, which means it can be easily dispersed in water.

Isocyanate

The isocyanate used in the present invention can be any diisocyanate and/or polyisocyanate having isocyanate groups with aliphatic, alicyclic, aromatic-aliphatic and/or aromatic linkage.

As used herein, the term “polyisocyanate” refers to an isocyanate having an isocyanate group functionality greater than 2. Suitable diisocyanates include any diisocyanate that can be obtained by various ways (e.g., by phosgenation in the liquid or gas phase, or by a phosgene-free route such as thermal cleavage of carbamate).

Preferred diisocyanates are those having isocyanate groups with aliphatic, alicyclic, aromatic-aliphatic and/or aromatic linkage and having a molecular weight in the range of 140 to 400 g/mol. Examples of such diisocyanates include 1,4-butane diisocyanate, 1,5-pentane diisocyanate (PDI), 1,6-hexane diisocyanate (HDI), 2- methyl-l,5-pentane diisocyanate, l,5-diisocyanato-2,2-dimethylpentane, 2,2,4- or

2.4.4-trimethyl-l,6-hexane diisocyanate, 1,10-decane diisocyanate, 1,3- and 1,4- cyclohexane diisocyanate, 1,3- and l,4-bis(isocyanatomethyl)cyclohexane, 1- isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI), 4,4'-dicyclohexylmethane diisocyanate, 1-isocyanato-l-methyl- 4(3)isocyanatomethylcyclohexane, bis(isocyanatomethyl)norbornane, 1,3- and 1,4- bis(2-isocyanatopropan-2-yl)benzene (TMXDI), toluene diisocyanate (toluene 2,4- and 2,6-diisocyanate, TDI), 2,4'- and 4,4'-diphenylmethane diisocyanate (MDI), 1,5- naphthalene diisocyanate (NDI), norbomane diisocyanate (NBDI) or any mixture of these diisocyanates.

More preferred diisocyanates are those having isocyanate groups with different reactivity, such as 2-methyl-l,5-pentane diisocyanate, l,5-diisocyanato-2,2- dimethylpentane, 2,2,4- or 2,4,4-trimethyl-l,6-hexane diisocyanate, 1-isocyanato-

3.3.5-trimethyl-5-isocyanato-methylcyclohexane (isophorone diisocyanate, IPDI), 1- isocyanato-1 -methyl -4(3 )isocyanato-methylcyclohexane, toluene diisocyanate (toluene 2,4- and 2,6-diisocyanate, TDI), 2,4'-diphenylmethane diisocyanate (MDI) or any mixture of these diisocyanates.

Particularly suitable diisocyanates are l-isocyanato-3,3,5-trimethyl-5-isocyanato- methylcyclohexane (isophorone diisocyanate, IPDI), toluene diisocyanate (toluene 2,4- and 2,6-diisocyanate, TDI), 2,4'-diphenylmethane diisocyanate (MDI) or any mixture of these diisocyanates. Among them, toluene diisocyanate (toluene 2,4- and 2,6-diisocyanate, TDI), in particular, the 2,4- and 2,6- isomers and a technical mixture of these two isomers, are preferred.

Especially suitable aromatic diisocyanates are toluene 2,4-diisocyanate and a technical mixture thereof comprising 70 to 90% of toluene 2,4-diisocyanate and 30 to 10% of toluene 2,6-diisocyanate.

Suitable isocyanates may also include any polyisocyanate having a urea diketone, isocyanuronate, allophanate, biuret, imino-oxadiazine dione and/or oxadiazine trione structure, prepared by simply modifying aliphatic, alicyclic, aromatic-aliphatic and/or aromatic diisocyanates and/or polyisocyanates, such as those of the types mentioned above, as described for example in J. Prakt. Chem. 336 (1994) 185-200, DE-A 1 670 666, DE-A 1 954 093, DE-A 2 414 413, DE-A 2 452 532, DE-A 2 641 380, DE-A 3 700 209, DE-A 3 900 053 and DE-A 3 928 503 or EP-A 0 336 205, EP-A 0 339 396 and EP-A 0 798 299, or any mixture of these isocyanates.

Blocking Agent

The blocking agent suitable for use in the present invention includes, for example, pyrazole, alcohol, oxime, lactam, P-dicarbonyl compounds and phenolic compounds.

As an example of the pyrazole compound, mention may be made of 3,5- dimethylpyrazole.

As examples of the alcohol compound, mention may be made of methanol, ethanol, 2 -propanol, n-butanol, sec-butanol, 2-ethyl-l -hexanol, 2-m ethoxy ethanol, 2- ethoxy ethanol and 2 -butoxy ethanol.

As examples of the oxime compound, mention may be made of butanone oxime, acetone oxime, formaldehyde oxime, acetaldehyde oxime and cyclohexanone oxime.

As examples of the lactam compound, mention may be made of s-caprolactam, 5- valerolactam and y-butyrolactam.

As examples of the P-dicarbonyl compound, mention may be made of dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, di-n-propyl malonate, di-isopropyl malonate, di-n-butyl malonate and di-isobutyl malonate.

As examples of the phenolic compound, mention may be made of phenol, nonylphenol, cardanol, bisphenol A and bisphenol F.

Preferably, the blocking agent is selected from phenolic compounds. More preferably, the blocking agent is selected from phenolic compounds having an OH value of 184 to 206 mg KOH/g, preferably 184 to 200 mg KOH/g, more preferably 186 to 192 mg KOH/g.

Even more preferably, the blocking agent is selected from nonylphenol, cardanol, or a mixture of them, with a further preference for cardanol.

The cardanol has the following structure:

wherein R represents C15H31-11, in which n=0, 2, 4 and 6. NQ Hydrogen Compounds Comprising A Hydrophilic Group

As used in the present application, an active hydrogen compound comprising a hydrophilic group refers to an organic compound comprising in the molecular structure both hydrophilic groups and active hydrogen groups that can react with isocyanate groups.

Preferably, the active hydrogen compound comprising a hydrophilic group has an average active hydrogen functionality of at least 1, preferably an average active hydrogen functionality of at least 2. Advantageously, the active hydrogen compound with an average active hydrogen functionality of at least 2 provides a blocked prepolymer system which leads to finished products having a better mechanical performance.

Preferably, the hydrophilic group is on a side chain, so that the resulting water- dispersible polymer system exhibits better water dispersibility.

Preferably, the active hydrogen compound comprising a hydrophilic group is selected from organic alcohol compounds, organic amine compounds, mercapto compounds and mixtures thereof.

The hydrophilic groups may be ionic hydrophilic groups, non-ionic hydrophilic groups or mixtures thereof.

As used herein, ionic hydrophilic groups may be understood as functional groups that, when interacting with an aqueous medium, may result in pH-dependent dissociation equilibrium, and thus may be negatively charged, positively charged, or neutral, such as -COOY, -SO3Y, -P0(0Y)2 (wherein Y = H, NH , or metal cation), - NR.2, and -NR3⁺ (wherein R = H, alkyl, or aryl).

Preferably, the ionic hydrophilic groups are -COOY, -SO3Y, and -P0(0Y)2, which may be present in the form of internal salts (amphoteric ions, betaines, ylides) or metal salts or ammonium salts.

As used herein, non-ionic hydrophilic groups refer to those groups or molecular segments that do not contain ionic hydrophilic groups but instead achieve affinity for water by forming interm olecular H-bonds with water. For example, the non-ionic hydrophilic groups may be polyalkylene oxide polyether groups, including pure poly(ethylene oxide) poly ether or mixed polyalkylene oxide poly ether, the unit content of ethylene oxide being not less than 30 mol%, preferably not less than 40 mol%.

Advantageously, the active hydrogen compound comprising an ionic hydrophilic group is selected from dihydroxymethylpropionic acid, dihydroxymethylbutyric acid, dihydroxypropanesulfonic acid, dimercaptopropanesulfonic acid, sodium dihydroxypropanesulfonate, sodium dimercaptopropanesulfonate, sodium ethylenediamine ethanesulfonate, sodium diaminobenzenesulfonate, hydroxypivalic acid, N-(2-aminoethyl)-P-alanine, 2-(2-aminoethylamino)ethanesulfonic acid, ethylenediamine propanesulfonic acid or ethylenediamine butanesulfonic acid, 1,2- or 1,3-propanediamine-P-ethylsulfonic acid, lysine, 3,5-diaminobenzoic acid, and compounds containing structural units capable of converting into cationic groups (e.g., amine-based structural units) as hydrophilic structural components, such as N- methyldiethanolamine. In addition, cyclohexylaminoalkylsulfonic acid (e.g., cyclohexylaminopropanesulfonic acid, cyclohexylaminobutanesulfonic acid, etc.), N- (2-aminoethyl)-P-alanine, 2-(2-aminoethylamino)ethanesulfonic acid, or hydrophilic reagents such as those in Example 1 of EP-A0916647 and metal salts or ammonium salts thereof, may also be used. Preferably, the active hydrogen compound comprising an ionic hydrophilic group is selected from dihydroxymethylpropionic acid, dihydroxymethylbutyric acid, dihydroxypropanesulfonic acid, dimercaptopropanesulfonic acid, sodium dihydroxypropanesulfonate, sodium dimercaptopropanesulfonate, sodium ethylenediamine ethanesulfonate, sodium diaminobenzenesulfonate, cyclohexylaminoalkanesulfonic acid (e.g. cyclohexylaminopropanesulfonic acid, cyclohexylaminobutanesulfonic acid and the like), N-(2-aminoethyl)-P-alanine, and 2-(2-aminoethylamino)ethanesulfonic acid.

Preferably, the active hydrogen compound comprising a nonionic hydrophilic group is selected from monohydric alcohols comprising a methyl-terminated poly(ethylene oxide) polyether segment or diols comprising a polyethylene oxide) polyether segment on aside chain, wherein the poly(ethylene oxide) polyether segment preferably have a number-average molar mass of 300 to 4,000 g/mol, preferably 300 to 2,500 g/mol. Examples of the monohydric alcohol comprising a methyl-terminated poly(ethylene oxide) polyether segment include MPEG 350, MPEG 500, MPEG 750, and MPEG 1000. Examples of the diol comprising a poly(ethylene oxide) poly ether segment on a side chain include Ymer N90, Ymer N1200, and Ymer N180 from Perstorp Company.

Preferably, the active hydrogen compound comprising a nonionic hydrophilic group has a water solubility of at least 500 g/litre, more preferably a complete water solubility as determined at 20°C.

Non-hydrophilic Polyhydroxyl Compound As used in the present application, non-hydrophilic polyhydroxyl compounds refer to hydroxyl compounds not comprising an ionic hydrophilic group or non-ionic hydrophilic group.

The non-hydrophilic polyhydroxyl compound suitable for use in the present invention can be, for example, polymer polyols known in polyurethane chemistry, such as polyether polyols, polyester polyols, polycarbonate polyols, polyurethane polyols, and/or polyacrylate polyols.

Non-hydrophilic polyhydroxyl compounds typically have an average functionality of 1.8 to 6.0, preferably 1.8 to 4.0, more preferably 1.9 to 2.2. These polymer polyols typically have a number average molecular weight (determined according to DIN 55672-1:2016-03) in the range of 1,000 to 10,000 g/mol, preferably 1,000 to 8,000 g/mol, more preferably 1,000 to 4,000 g/mol. Any mixture of these polymer polyols may be used as well.

Preferably, the non-hydrophilic polyhydroxyl compounds are polyether polyols or a mixture of polymer polyols comprising at least one polyether polyol.

More preferably, the non-hydrophilic polyhydroxyl compounds are selected from polyether polyols, insofar as they meet the requirements of the above-mentioned functionality and molecular weight.

Particularly preferably, merely polyether polyols, in particular addition products of ethylene oxide and/or propylene oxide under 1,2-propanediol, 1,3 -propanediol, dipropylene glycol, diethylene glycol, glycerol, trimethylolpropane, triethanolamine, ethylenediamine and/or pentaerythritol initiated polymerization, or polytetramethylene ether glycol with the molecular weight falling within the above range, for example, obtainable by polymerization of tetrahydrofuran according to Angew. Chem. 72, 927 (1960), are used.

Especially preferred are addition products of ethylene oxide and/or propylene oxide under 1,2-propanediol, 1,3 -propanediol, dipropylene glycol and/or diethylene glycol initiated polymerization. Even more particularly preferred are addition products of ethylene oxide and/or propylene oxide under 1,2-propanediol initiated polymerization, said poly ether polyols comprising 80 wt.% of 1,2-propanediol, more preferably 90 wt.% of 1,2-propanediol, most preferably 100 wt.% of 1,2-propanediol.

Preferably, the non-hydrophilic polyhydroxyl compound has a water solubility of no more than 100 g/litre, more preferably a complete insolubility in water as determined at 20°C. Method for Preparing a Blocked Isocyanate Prepolymer System

B. reacting the resulting partially blocked isocyanate intermediate with an active hydrogen compound comprising a hydrophilic group and a non-hydrophilic polyhydroxyl compound until the amount of free isocyanate groups is less than 0.5% by weight, preferably less than 0.2% by weight, more preferably less than 0.1% by weight, relative to the total weight of the entire reaction system, to obtain a water- dispersible blocked isocyanate prepolymer system.

The non-hydrophilic polyhydroxyl compound and the active hydrogen compound comprising a hydrophilic group may collectively react with the partially blocked isocyanate intermediate to obtain a water-dispersible blocked isocyanate prepolymer system, or separately react with the partially blocked isocyanate intermediate, followed by mixing the resulting products, to obtain a water-dispersible blocked isocyanate prepolymer system.

In some embodiments, the method comprises the steps of: reacting an isocyanate comprising two or more isocyanate groups with a blocking agent to obtain a partially blocked isocyanate intermediate; and reacting a portion of the partially blocked isocyanate intermediate with a non- hydrophilic polyhydroxyl compound until the amount of free isocyanate groups is less than 0.5 % by weight, preferably less than 0.2 % by weight, more preferably less than 0.1 % by weight, to obtain a non-hydrophilic blocked isocyanate prepolymer, reacting the remaining portion of the partially blocked isocyanate intermediate with an active hydrogen compound comprising a hydrophilic group until the amount of free isocyanate groups is less than 0.5% by weight, preferably less than 0.2 % by weight, more preferably less than 0.1 % by weight, to obtain a hydrophilic blocked isocyanate prepolymer, and mixing the non-hydrophilic blocked isocyanate prepolymer with the hydrophilic blocked isocyanate prepolymer, to obtain a water-dispersible blocked isocyanate prepolymer system.

In some embodiments, the method comprises the steps of: reacting an isocyanate comprising two or more isocyanate groups with a blocking agent to obtain a partially blocked isocyanate intermediate; and collectively reacting the partially blocked isocyanate intermediate, a non- hydrophilic polyhydroxyl compound and an active hydrogen compound comprising a hydrophilic group, until the amount of free isocyanate groups is less than 0.5 % by weight, preferably less than 0.2 % by weight, more preferably less than 0.1 % by weight, to obtain a water-dispersible blocked isocyanate prepolymer system.

According a third aspect of the present invention, there is provided a method for preparing the above-mentioned water-dispersible blocked isocyanate prepolymer system, comprising the steps of: reacting an isocyanate comprising two or more isocyanate groups first with a non- hydrophilic polyhydroxyl compound and an active hydrogen compound comprising a hydrophilic group, and then with a blocking agent, until the amount of free isocyanate groups is less than 0.5 % by weight, preferably less than 0.2 % by weight, more preferably less than 0.1 % by weight, to obtain a water-dispersible blocked isocyanate prepolymer system.

The non-hydrophilic polyhydroxyl compound and the active hydrogen compound comprising a hydrophilic group may collectively or successively react with the isocyanate to obtain a mixture of a non-hydrophilic isocyanate prepolymer and a hydrophilic isocyanate prepolymer, or separately react with the isocyanate to obtain a non-hydrophilic isocyanate prepolymer and a hydrophilic isocyanate prepolymer, respectively.

The non-hydrophilic polyhydroxyl compound and the hydrophilic isocyanate prepolymer may collectively react with the blocking agent to obtain a water- dispersible blocked isocyanate prepolymer system, or separately react with the blocking agent, followed by mixing the resulting products, to obtain a water- dispersible blocked isocyanate prepolymer system.

In some embodiments, the method comprises the step of: reacting an isocyanate comprising two or more isocyanate groups with a non- hydrophilic polyhydroxyl compound to obtain a non-hydrophilic isocyanate prepolymer, reacting the isocyanate comprising two or more isocyanate groups with an active hydrogen compound comprising a hydrophilic group to obtain a hydrophilic isocyanate prepolymer, separately reacting the non-hydrophilic isocyanate prepolymer and the hydrophilic isocyanate prepolymer with a blocking agent, until the amount of free isocyanate groups is less than 0.5 % by weight, preferably less than 0.2 % by weight, more preferably less than 0.1 % by weight, to obtain a non-hydrophilic blocked isocyanate prepolymer and a hydrophilic blocked isocyanate prepolymer, and mixing the non-hydrophilic blocked isocyanate prepolymer with the hydrophilic blocked isocyanate prepolymer, to obtain a water-dispersible blocked isocyanate prepolymer system.

In some embodiments, the method comprises the steps of: reacting an isocyanate comprising two or more isocyanate groups with a non- hydrophilic polyhydroxyl compound to obtain a non-hydrophilic isocyanate prepolymer, reacting the isocyanate comprising two or more isocyanate groups with an active hydrogen compound comprising a hydrophilic group to obtain a hydrophilic isocyanate prepolymer, and collectively reacting the non-hydrophilic isocyanate prepolymer and the hydrophilic isocyanate prepolymer with a blocking agent, until the amount of free isocyanate groups is less than 0.5 % by weight, preferably less than 0.2 % by weight, more preferably less than 0.1 % by weight, to obtain a water-dispersible blocked isocyanate prepolymer system.

In some embodiments, the method comprises the steps of: collectively reacting a non-hydrophilic polyhydroxyl compound, an active hydrogen compound comprising a hydrophilic group and an isocyanate comprising two or more isocyanate groups, to obtain a mixture of a non-hydrophilic isocyanate prepolymer and a hydrophilic isocyanate prepolymer, and reacting the mixture of a non-hydrophilic isocyanate prepolymer and a hydrophilic isocyanate prepolymer with a blocking agent, until the amount of free isocyanate groups is less than 0.5 % by weight, preferably less than 0.2 % by weight, more preferably less than 0.1 % by weight, to obtain a water-dispersible blocked isocyanate prepolymer system.

In some embodiments, the method comprises the steps of: successively reacting a non-hydrophilic polyhydroxyl compound and an active hydrogen compound comprising a hydrophilic group with an isocyanate comprising two or more isocyanate groups, to obtain a mixture of a non-hydrophilic isocyanate prepolymer and a hydrophilic isocyanate prepolymer, and reacting the mixture of a non-hydrophilic isocyanate prepolymer and a hydrophilic isocyanate prepolymer with a blocking agent, until the amount of free isocyanate groups is less than 0.5 % by weight, preferably less than 0.2 % by weight, more preferably less than 0.1 % by weight, to obtain a water-dispersible blocked isocyanate prepolymer system.

In the method of the present invention, the isocyanate, the blocking agent, the non- hydrophilic polyhydroxyl compound and the active hydrogen compound comprising a hydrophilic group are as previously defined in the first aspect of the present invention.

In the method of the present invention, as defined in the first aspect of the present invention, the molar ratio of the non-hydrophilic polyhydroxyl compound to the active hydrogen compound comprising a hydrophilic group is in a range of 0.1 to 25.0, the molar ratio of all of the groups in the non-hydrophilic polyhydroxyl compound and the active hydrogen compound comprising a hydrophilic group that can react with the isocyanate to all isocyanate groups of the isocyanate is in a range of 0.30 to 0.80, and the molar ratio of all of the groups in the non-hydrophilic polyhydroxyl compound, the active hydrogen compound comprising a hydrophilic group and the blocking agent that can react with the isocyanate to all isocyanate groups of the isocyanate is in a range of 0.90 to 1.10.

In the present application, the blocking reaction and the urethane reaction can be carried out at a temperature of 0 to 250°C, preferably 20 to 140°C, more preferably 40 to 100°C.

The reaction may also involve the addition of suitable reaction catalysts to expedite the reaction, thereby shortening the reaction time. The catalysts can be those known in polyurethane chemistry, for example, metal-organic compounds such as Stannous (II) octanoate (also named tin(II)octanoate), dibutyltin(II) diacetate, dibutyltin(II) laurate, 2,3-dimethyl-3,4,5,6-tetrahydropyrimidine, tertiary amines such as triethylamine, diazabicyclooctane, l,8-diazabicyclo[5.4.0]undec-7-ene, and a mixture comprising two or more of the above compounds.

The amount of suitable catalysts is in the range of 0.01% to 0.5%, preferably 0.02% to 0.3%, more preferably 0.02% to 0.2%.

The blocking reaction and/or the urethane reaction can also be carried out in a suitable solvent that is inert to the reactive groups of the starting components.

Examples of suitable solvents include, but are not limited to, ethyl acetate, butyl acetate, ethylene glycol monomethyl ether or monoethyl ether acetate, 1 -methoxy -2- propyl acetate (MPA), 3 -m ethoxy -n-butyl acetate, acetone, 2-butanone, 4-methyl-2- pentanone, cyclohexanone, toluene, xylene, chlorobenzene, white spirit, more highly substituted aromatic hydrocarbons, such as those types sold under the names Solvent naphtha, Solvesso, Isopar, Nappar (ExxonMobil Chemical Central Europe GmbH, Cologne, Germany) and Shellsol (Shell Deutschland Oil GmbH, Hamburg, Germany), and solvents such as propylene glycol diacetate, diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, diethylene glycol ethyl ether and butyl ether acetate, N-methyl pyrrolidone and N-methyl caprolactam, or any mixture of these solvents.

Blocked Isocyanate Prepolymer Aqueous Dispersion

The blocked isocyanate prepolymer aqueous dispersion is prepared by dispersing the blocked isocyanate prepolymer system of the present invention into water. Suitable dispersion methods may involve gradually adding distilled water while performing high-speed stirring of the blocked isocyanate prepolymer system, or gradually adding the blocked isocyanate prepolymer system while performing high-speed stirring of distilled water.

The dispersion method can also be carried out at a temperature of 25 to 60°C, preferably 30 to 50°C.

Prior to dispersion, the blocked isocyanate prepolymer system may also be diluted with a suitable solvent to reduce the viscosity and thereby facilitate dispersion. Examples of the suitable solvent include conventional solvents known to be miscible with water, such as acetone, 2-butanone, 4-methyl-2-pentanone, cyclohexanone, tetrahydrofuran, dimethyl ether, methanol, ethanol, ethyl acetate, ethylene glycol monomethyl ether or monoethyl ether acetate, 1 -methoxy -2 -propyl acetate (MPA), 3 -m ethoxy -n-butyl acetate, and solvents such as propylene glycol diacetate, diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, diethylene glycol ethyl ether and butyl ether acetate, N-methylpyrrolidone, N,N dimethylformamide, dimethylsulfoxide and N-methylcaprolactam and the like, or any mixture of these solvents. Preferred are solvents with low boiling points and miscible with water, such as acetone, 2-butanone, 4-methyl-2-pentanone, cyclohexanone, tetrahydrofuran, dimethyl ether, methanol, ethanol, ethyl acetate, ethylene glycol monomethyl ether or monoethyl ether acetate, and 1 -methoxy -2 -propyl acetate (MPA). Particularly preferred are acetone, tetrahydrofuran, dimethyl ether, methanol, ethanol, ethyl acetate, ethylene glycol monomethyl ether or monoethyl ether acetate, and 1- methoxy -2 -propyl acetate (MPA). If a solvent is used to facilitate dispersion, the above method for preparing a blocked isocyanate prepolymer aqueous dispersion may further comprise a step of removing the solvent, such as evaporation by heat, vacuum extraction, or vacuum extraction under heating.

Use of Water-Dispersible Blocked Isocyanate Prepolymer System and Product Comprising the Same

The water-dispersible blocked isocyanate prepolymer system or blocked isocyanate prepolymer aqueous dispersion of the present invention can be processed into various products such as polyurethane plastics, adhesives, sealing materials, encapsulating materials, fiber sizing materials or coating materials. The application fields include, but not limited to, hydraulic engineering, shipbuilding (e.g., ballast tanks), transportation, green energy, piping and flooring etc.

Therefore, according to a sixth aspect of the present invention, there are provided polyurethane plastics, adhesives, sealing materials, encapsulating materials, fiber sizing materials or coating materials comprising the above-mentioned water- dispersible blocked isocyanate prepolymer system or blocked isocyanate prepolymer aqueous dispersion. In some embodiments, there is provided a blocked isocyanate prepolymer-epoxy reactive aqueous dispersion system, comprising the above-mentioned water- dispersible blocked isocyanate prepolymer system or blocked isocyanate prepolymer aqueous dispersion, polyamines and an epoxy resin aqueous dispersion.

Preferably, the polyamines are those having at least two primary per molecule and optionally also secondary amino groups and preferably having an average molecular weight of 60 to 500 g/mol. As examples of such polyamines, mention may be made of ethylenediamine, 1,2- and 1,3 -diaminopropane, 1,4-diaminobutane, 2,2,4- and/or 2,4,4-trimethylhexanediamine, isomeric dimethylbenzenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, 1,4-diaminocyclohexane, 4,4'- diaminodi cyclohexylmethane, 1,3-diaminocyclopentane, 4, 4'-diaminodi cyclohexyl sulfone, 4,4'-diaminodicyclohexylpropane-l,3-, or -4,4'- diaminodicyclohexylpropane-2,2-, or -3,3'-dimethyl-4,4 '- diaminodi cyclohexylmethane, 3-aminomethyl-3,3,5-trimethylcyclohexylamine

(isophorone diamine), 3 (4)-aminom ethyl- 1 -methylcyclohexylamine, technical grade bis(aminomethyl)tri cyclodecane, octahydro-4, 7-methyleneindene-l,5-dimethylamine, and phenolic amine curing agents synthesized from phenol-formaldehyde resins and amine compounds, or polyamines having a secondary amine in addition to at least two primary amines, such as diethylene-triamine or diethylene-tetraamine.

Particularly preferred are polyamines, especially diamines containing one or more alicyclic rings with the molecular weight falling within the range described above. Examples of such polyamines include 1,4-diaminocyclohexane, 4,4'- diaminodicyclohexylmethane, 1,3-diaminocyclopentane, 4,4'- diaminodicyclohexylsulfone, 4,4'-diaminodicyclohexyl propane-1,3-, or -4,4'- diaminodicyclohexylpropane-2,2-, or -3,3'-dimethyl-4,4'- diaminodi cyclohexylmethane, 3-aminomethyl-3,3,5-trimethylcyclohexylamine

(isophorone diamine), 3- and 4-aminom ethyl- 1 -methylcyclohexylamine or technical grade bis(aminomethyl)tricyclodecane.

It is also possible to use the adducts prepared by reacting an excess of said poly amines with epoxy resins of the types described below as ingredients of the amine component.

The poly amines may also include poly etheramines prepared by reacting poly ether polyols with ammonia, and sold, for example, under the trade name Jeffamine ® by Huntsman.

The epoxy resin aqueous dispersion is an aqueous dispersion prepared from at least one epoxy resin having a functionality of more than 0.8 epoxy groups/molecule on the basis of an external emulsifier or an internal emulsifier. The epoxy resin may be a saturated or unsaturated, linear or branched, aliphatic, cycloaliphatic, arylene or heterocyclic epoxy resin.

The external emulsifier refers to those compounds that can be physically added to an epoxy resin system to facilitate dispersion of the epoxy resin. Examples of the external emulsifier include, but are not limited to, one or a combination of two or more of nonylphenol ethoxylate, alkylphenol -initiated poly(ethylene oxide) ethanol, alkylphenol-initiated polypropylene oxide)poly(ethylene oxide) ethanol, and a block copolymer comprising one endo-poly(ethylene oxide) block and two exo- poly(ethylene oxide) ethanol blocks, sodium alkyl polyoxyethylene ether sulfate, sodium dodecyl sulfate, and sodium dodecylbenzenesulfonate.

The internal emulsifier refers to those groups contained in the structure of the epoxy resin that can facilitate emulsification and dispersion, which may be ionic hydrophilic groups, nonionic hydrophilic groups, or a mixture thereof. Ionic hydrophilic groups may be understood as functional groups that, when interacting with an aqueous medium, may result in pH-dependent dissociation equilibrium, and thus may be negatively charged, positively charged, or neutral, such as -COOY, -SO3Y, - PO(OY)2 (wherein Y = H, NELf, or metal cation), -NR2, and -NR.3 (wherein R = H, alkyl, or aryl). Non-ionic hydrophilic groups refer to those groups or molecular segments that do not contain ionic hydrophilic groups but instead achieve affinity for water by forming interm olecular H-bonds with water. For example, the non-ionic hydrophilic groups may be polyalkylene oxide polyether groups, including pure poly(ethylene oxide) poly ether or mixed polyalkylene oxide poly ether, the unit content of ethylene oxide being not less than 30 mol%, preferably not less than 40 mol%.

Examples of the preferred epoxy resin aqueous dispersion include epoxy resins based on bisphenol A or bisphenol F, having a molecular weight of 350 to 10,000 g/mol, dispersed in a non-ionic form in water with or without a glycol ether co-solvent.

Commercially available examples of the epoxy resin aqueous dispersion include: bisphenol A resins, such as EPI-REZ Resin 3510-W-60 (emulsion), EPI-REZ Resin 3520-WY-55, EPI-REZ Resin 3521-WY-53, EPI-REZ Resin 3523-WH-53, EPI-REZ Resin 6520-WH-53, and EPI-REZ Resin 3540-WY-55, all available from Hexion Specialty Chemicals, Inc.

The blocked isocyanate prepolymer-epoxy reactive aqueous dispersion system can be cured at room temperature, for use as coating materials. The coatings made from the reactive system have superior impact resistance and shock resistance, while exhibiting flexibility and elasticity. The descriptions of various features in the present application may be combined with each other where there is no contradiction, and all fall within the protection scope of the present application.

As used in the present application, “and/or” refers to one or all of the elements mentioned.

All percentages in the present application are percentages by weight, unless otherwise specified.

The analytical measurements described in the present application were all carried out at 23°C, unless otherwise specified.

The weight average molecular weight and the number average molecular weight of the isocyanate (including the fully blocked isocyanate) described in the present application were determined according to DIN 55672-1 :2016-03 with a HLC-8320 EcoSEC-type gel chromatograph from TOSOH, using polystyrene standards, a high- performance universal chromatographic 4x column set (TSKgel G2000HXL, TSKgel G2500HXL, TSKgel G3000HXL and TSKgel G4000HXL, the chromatographic columns packing material is styrene-divinylbenzene copolymer) and a differential refraction detector, using tetrahydrofuran as eluent, a flow rate of 1.0 ml/min, the pressure 6.4 of MPa and the column temperature of 40°C.

The content of isocyanate groups (NCO) was determined titrimetrically according to DIN-EN ISO 11909:2007-05, and the data measured include the content of free and potentially free NCO groups.

The potentially free NCO groups may convert into free NCO groups under such conditions as heating.

The average particle size of the dispersion was determined by diluting the sample with deionized water and then using laser correlation spectroscopy for measurement at 23°C according to ISO 13321-1996 (Instrument: Malvern Zetasizer Nano ZS 3600, Malvern Inst. Limited).

The solid content was determined by heating the weighed sample to 120°C. After reaching a constant weight, the sample was weighed again to determine the solid content.

The viscosity was measured by using a HAAKE VT550 Viscometer according to DIN EN ISO 3219: 1994-10.

The impact resistance was measured according to ASTM 2794-1993 as follows: a 120 pm wet film was applied onto a tinplate substrate, and after sufficient curing and maintenance, a reverse impact test was performed with the paint film facing downward. The test data was characterized as the maximum drop height (cm) that the paint film could withstand without rupture.

The flexibility test was carried out according to DIN EN ISO 1519-201 las follows: a 120 pm wet film was applied onto a tinplate substrate, and after sufficient curing and maintenance, a bending test was performed using a flexometer. The test data was characterized as the minimum bending diameter (mm) that the paint film can withstand without rupture.

The pendulum hardness test method was carried out according to DIN EN ISO 1522-2007 as follows: a 120 pm wet film is applied onto a glass plate substrate, and after sufficient curing and maintenance, the pendulum swing time (in seconds) is measured on a pendulum tester. The pendulum swing time in the pendulum test result can represent hardness of the paint film. The longer the pendulum swing time, the higher the hardness of the paint film.

The other undescribed tests were carried out through conventional methods in the art.

The terms “comprising” and “including” described in the present application cover the circumstances which further comprise or include other elements not specifically mentioned and the circumstances consisting of the elements mentioned.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by a person skilled in the field the present invention belongs to. When the definition of a term in the present description conflicts with the meaning as commonly understood by a person skilled in the field the present invention belongs to, the definition described herein shall apply.

Unless otherwise specified, all numerical values expressing the amount of ingredients, reaction conditions and the like used in the description and claims are to be understood as being modified by the term “about”. Accordingly, unless indicated to the contrary, the numerical values and parameters described herein are approximate values which are subject to change according to the performance as required.

Examples

The conception, specific structures and technical effects of the present invention will be further described below in conjunction with the Examples, so that a person skilled in the art can fully understand the objectives, features and effects of the present invention. It will be easily appreciated by a person skilled in the art that the Examples are for illustrative purposes only and the scope of the present invention is not limited thereto. The main materials used in the following examples are stated below:

DESMODUR® T 80: comprising about 80 wt.% of 2,4-toluene diisocyanate and 20 wt.% of 2,6-toluene diisocyanate, available from Covestro Polymers (China) Co., Ltd.

NX 2026: Cardanol, available from the company Cardolite Specialty Chemicals Europe N. V.

DP 1000: Polyether diol with an OH value of 110 to 114 mg KOH/g, available from Kukdo Chemical Co., Ltd. - non-hydrophilic polyhydroxyl compound with a water solubility of <22.5 g/ IL

DP 2000E: Poly ether diol with an OH value of 54 to 58 mg KOH/g, available from Kukdo Chemical Co., Ltd. - non-hydrophilic polyhydroxyl compound with a water solubility of <14.0 g/ IL

Ymer N120: Polyether diol with an OH value of 100 to 120 mg KOH/g, available from Perstorp Company. - active hydrogen compound comprising a hydrophilic group with a water solubility of >500 g/ IL

MPEG 500: Methoxypolyethylene glycol with an OH value of about 112 mg KOH/g, available from INEOS NV. - active hydrogen compound comprising a hydrophilic group with a water solubility of >500 g/ IL

Sumiphen 1468: Poly ether diol with an OH value of about 28 mg KOH/g, available from Covestro Japan. - non-hydrophilic polyhydroxyl compound

Stannous octanoate (II): available from Shanghai Aladdin Biochemical Technology Co., Ltd.

2,2-Dihydroxymethylbutyric acid: available from Shanghai Aladdin Biochemical Technology Co., Ltd. - active hydrogen compound comprising a hydrophilic group

Triethylamine: available from Shanghai Aladdin Biochemical Technology Co., Ltd.

EPIKOTE™ Resin 6529-WH-57A: Nonionic aqueous dispersion of solid bisphenol A epoxy resin, with an epoxy equivalent of 480 to 600 g/mol (by solid content) and a solid content of 55% to 59%, available from Hexion Chemicals Co., Ltd.

EPIKURE™ 6870-W-53: Nonionic aqueous dispersion modified on the basis of amine adducts, with an amine value of 235 to 265 mg KOH/g and a solid content of 51% to 54%, available from Hexion Chemicals Co., Ltd. Example 1: Preparation of Cardanol-blocked Toluene Diisocyanate

420.0 g of toluene diisocyanate (DESMODUR® T 80, containing about 80 wt.% of 2,4-toluene diisocyanate and 20 wt.% of 2,6-toluene diisocyanate) was added into a reaction flask and heated while stirring to 90°C. Then, 766.8 g of cardanol (NX 2026) was slowly added dropwise to the reaction solution through a dropping funnel over a period of about 4 hours. After the addition was completed, the reaction continued with stirring at 90°C and cooled down when the NCO content reached 8.6%, to produce a cardanol-blocked toluene diisocyanate.

Example 2: Non-hydrophilic Blocked Isocyanate Prepolymer 1

600.0 g of polyether diol (Sumiphen 1468, with an OH value of about 28 mg KOH/g) was placed into a reaction flask and heated while stirring to 60°C, and 1.6 g of catalyst Stannous (II) octanoate was added. Then, 150.0 g of the cardanol-blocked toluene diisocyanate obtained in Example 1 was slowly added dropwise through a dropping funnel into the reaction flask. After the addition was completed, the reaction continued until the NCO% was <0.3%. Next, 2.1 g of benzoyl chloride was added and stirred for an additional 30 minutes. Upon cooling, a non-hydrophilic blocked isocyanate prepolymer was obtained, with a measured viscosity of 12,860 mPas. A solution with acetone diluted to 80 wt.% was added in an appropriate amount to obtain a non-hydrophilic blocked isocyanate prepolymer 1.

Example 3: Non-hydrophilic Blocked Isocyanate Prepolymer 2

30.0 g of isophorone diisocyanate (IPDI) was placed into a reaction flask and heated while stirring to 65°C. Then, 0.1 g of catalyst Stannous (II) octanoate was added, and 48.6 g of cardanol was slowly added dropwise through a dropping funnel for reaction for about 1 hour. Next, 135.2 g of poly ether diol DP 2000E was added for continued reaction until the infrared spectrum showed that NCO absorption peaks basically disappeared. Subsequently, 0.2 g of benzoyl chloride was added and stirred for an additional 30 minutes. Upon cooling, a non-hydrophilic blocked isocyanate prepolymer 2 was obtained, with a measured viscosity of 8,830 mPas.

Example 4: Non-hydrophilic Blocked Isocyanate Prepolymer 3

31.0 g of toluene diisocyanate was placed into a reaction flask, and heated while stirring to 80°C. Then, 0.2 g of catalyst Stannous (II) octanoate was added, and 89.0 g - 1 - of DP 1000 was slowly added dropwise through a dropping funnel for reaction for about 2 hours, followed by cooling to 65°C. Next, 59.4 g of cardanol was added dropwise for continued reaction until the infrared spectrum showed that NCO absorption peaks basically disappeared. Subsequently, 0.2 g of benzoyl chloride was added and stirred for an additional 30 minutes. Upon cooling, a water-dispersible blocked isocyanate prepolymer 3 was obtained, with a measured viscosity of 70,880 mPas.

Example 5: Hydrophilic Blocked Isocyanate Prepolymer 4

375.0 g of polyether diol (YmerN120, with an OH value of 100 to 120 mg KOH/g) was placed into a reaction flask, and heated while stirring to 60°C. Then, 360.0 g of the cardanol-blocked toluene diisocyanate obtained in Example 1 was slowly added dropwise through a dropping funnel into the reaction flask. After the addition was completed, the reaction continued until the NCO% was <0.5%, and about 184 g of acetone was added. Upon cooling while stirring, a hydrophilic blocked isocyanate prepolymer 4 was obtained, with a measured viscosity of 865 mPas.

Example 6: Hydrophilic Blocked Isocyanate Prepolymer 5

89.0 g of the cardanol-blocked toluene diisocyanate obtained in Example 1 was placed into a reaction flask, and heated while stirring to 50°C. Then, 13.8 g of 2,2- dihydroxymethylbutyric acid and 30 g of acetone were slowly added. After the addition was completed, the reaction continued until the NCO% was <0.5%. Next, about 7.2 g of triethylamine was added for continued reaction while stirring for 1 hour. Upon cooling, a hydrophilic blocked isocyanate prepolymer 5 was obtained.

Example 7: Hydrophilic Blocked Isocyanate Prepolymer 6

100.0 g of the cardanol-blocked toluene diisocyanate obtained from Example 1 was placed into a reaction flask, and heated while stirring to 60°C. Then, 96.1 g of MPEG 500 was slowly added dropwise through a dropping funnel. After the addition was completed, the reaction continued until the NCO% was <0.5%. Upon cooling, a hydrophilic blocked isocyanate prepolymer 6 was obtained, with a measured viscosity of 2,030 mPas.

Example 8: Preparation of Blocked Isocyanate Prepolymer Aqueous Dispersion 1 20 g of blocked isocyanate prepolymer 1 was evenly mixed with 80 g of hydrophilic blocked isocyanate prepolymer 4, and about 120 g of deionized water was slowly added while stirring to form a white emulsion. The emulsion was stirred and heated to 40°C, and acetone was removed under reduced pressure, to obtain a blocked isocyanate prepolymer aqueous dispersion 1.

Example 9: Preparation of Blocked Isocyanate Prepolymer Aqueous Dispersion 2

30 g of blocked isocyanate prepolymer 1 was evenly mixed with 70 g of hydrophilic blocked isocyanate prepolymer 4, and about 120 g of deionized water was slowly added while stirring to form a white emulsion. The emulsion was stirred and heated to 40°C, and acetone was removed under reduced pressure, to obtain a blocked isocyanate prepolymer aqueous dispersion 2.

Example 10: Preparation of Blocked Isocyanate Prepolymer Aqueous Dispersion 3

70 g of blocked isocyanate prepolymer 1 was evenly mixed with 30 g of hydrophilic blocked isocyanate prepolymer 4, and about 120 g of deionized water was slowly added while stirring to form a white emulsion. The emulsion was stirred and heated to 40°C, and acetone was removed under reduced pressure, to obtain a blocked isocyanate prepolymer aqueous dispersion 3.

Example 11: Preparation of Blocked Isocyanate Prepolymer Aqueous Dispersion 4

90 g of blocked isocyanate prepolymer 1 was evenly mixed with 10 g of hydrophilic blocked isocyanate prepolymer 5, and about 120 g of deionized water was slowly added while stirring to form a white emulsion. The emulsion was stirred and heated to 40°C, and acetone was removed under reduced pressure, to obtain a blocked isocyanate prepolymer aqueous dispersion 4.

Example 12: Preparation of Blocked Isocyanate Prepolymer Aqueous Dispersion 5

95 g of blocked isocyanate prepolymer 2 was evenly mixed with 5 g of hydrophilic blocked isocyanate prepolymer 4, and about 75 g of deionized water was slowly added while stirring to form a white emulsion. The emulsion was stirred and heated to 40°C, and acetone was removed under reduced pressure, to obtain a blocked isocyanate prepolymer aqueous dispersion 5.

Example 13: Preparation of Blocked Isocyanate Prepolymer Aqueous Dispersion 6

90 g of blocked isocyanate prepolymer 2 was evenly mixed with 10 g of hydrophilic blocked isocyanate prepolymer 6, and about 300 g of deionized water was slowly added while stirring to form a white emulsion. As a result, a blocked isocyanate prepolymer aqueous dispersion 6 was prepared.

Example 14: Preparation of Blocked Isocyanate Prepolymer Aqueous Dispersion 7

95 g of blocked isocyanate prepolymer 3 was evenly mixed with 5 g of hydrophilic blocked isocyanate prepolymer 4, and about 149 g of deionized water was slowly added while stirring to form a white emulsion. The emulsion was stirred and heated to 40°C, and acetone was removed under reduced pressure, to obtain a blocked isocyanate prepolymer aqueous dispersion 7.

The molar ratio of the non-hydrophilic polyhydroxyl compound to the active hydrogen compound comprising a hydrophilic group contained in the above- mentioned aqueous dispersion, and the particle size and solid content of said aqueous dispersion are summarized in Table 1.

Example 15: Blocked Isocyanate Prepolymer 7

18.3 g of toluene diisocyanate was placed into a reaction flask, and heated while stirring to 80°C. Then, 52.6 g of polyether diol DP 1000 was slowly added dropwise into the reaction flask for reaction. After 2 hours, the mixture was cooled to 50°C. 37.5 g of acetone dilution solution was added, 0.3 g of catalyst Stannous (II) octanoate was added, and 26.8 g of Ymer N120 (the DP 1000/Ymer N120 molar ratio being about 2.0) was added dropwise while stirring for continued reaction for 2 hours. Next, 17.4 g cardanol was slowly added dropwise through a dropping funnel for reaction until the infrared spectrum showed that NCO absorption peaks basically disappeared. Subsequently, 0.5 g of benzoyl chloride was added and stirred for an additional 30 minutes. Upon cooling, a water-dispersible blocked isocyanate prepolymer 7 was obtained, with a solid content of about 78% and a viscosity of about 2,725 mPas. 100 g of the above-mentioned blocked isocyanate prepolymer 7 was taken, and added with 95 g of water under high-speed stirring. After filtering, the resulting milky white filtrate was heated while stirring to 40°C, and acetone was removed under reduced pressure, to obtain a blocked isocyanate prepolymer aqueous dispersion 8 with a solid content of 43% and a particle size of 146 nm.

Table 1

* DI to D7 refer to Dispersion 1 to Dispersion 7.

Example 16

17.14 g of blocked isocyanate prepolymer aqueous dispersion 3 was added to 57.14 g of aqueous epoxy emulsion EPIKOTE™ Resin 6529-WH-57A with stirring until a homogeneous mixture was formed. Then, 25.71g of EPIKURE™ 6870-W-53 aqueous epoxy resin curing agent was added and stirred again to mix evenly. The resulting emulsion was applied to a glass plate and a tinplate for molding, and baked at 60°C for half an hour. After curing at room temperature for 7 days, a paint film with mechanical features in Table 2 was obtained.

Comparative Example 17

31.03 g of EPIKURE™ 6870-W-53 aqueous epoxy resin curing agent was added to 68.97 g of aqueous epoxy emulsion EPIKOTE™ Resin 6529-WH-57A with stirring until a homogeneous mixture was formed. Then, the resulting emulsion was applied to a glass plate and a tinplate for molding, and baked at 60°C for half an hour. After curing at room temperature for 7 days, a paint film with mechanical features in Table 2 was obtained.

Table 2

The above disclosure merely describes exemplary embodiments or Examples of the present invention, and is not intended to limit the present invention. For a person skilled in the art, the present invention may be modified or changed in various ways. Any amendment, equivalent substitution, improvement and the like without departing from the spirit and principles of the present invention all fall within the scope of the claims of the present application.

Claims

Claims:

1. A water-dispersible blocked isocyanate prepolymer system, characterized in that: it is prepared by reaction of an isocyanate comprising two or more isocyanate groups, a blocking agent, a non-hydrophilic polyhydroxyl compound, and an active hydrogen compound comprising a hydrophilic group, which active hydrogen compound has an average active hydrogen functionality of at least 2, wherein the molar ratio of the non-hydrophilic polyhydroxyl compound to the active hydrogen compound comprising a hydrophilic group is in a range of 0.1 to 25.0, the molar ratio of all of the groups in the non-hydrophilic polyhydroxyl compound and the active hydrogen compound comprising a hydrophilic group that can react with the isocyanate to all isocyanate groups of the isocyanate is in a range of 0.30 to 0.80, and the molar ratio of all of the groups in the non-hydrophilic polyhydroxyl compound, the active hydrogen compound comprising a hydrophilic group and the blocking agent that can react with the isocyanate to all isocyanate groups of the isocyanate is in a range of 0.90 to 1.10.

2. The blocked isocyanate prepolymer system of claim 1, characterized in that the molar ratio of the non-hydrophilic polyhydroxyl compound to the active hydrogen compound comprising a hydrophilic group is in a range of 0.1 to 23.0, more preferably in a range of 0.2 to 15.0.

3. The blocked isocyanate prepolymer system of claim 1 or 2, characterized in that the molar ratio of all of the groups in the non-hydrophilic polyhydroxyl compound and the active hydrogen compound comprising a hydrophilic group that can react with the isocyanate to all isocyanate groups of the isocyanate is in a range of 0.40 to 0.60, more preferably in a range of 0.45 to 0.55.

4. The blocked isocyanate prepolymer system of any one of claims 1 to 3, characterized in that the isocyanate is selected from diisocyanates and/or polyisocyanates having isocyanate groups with aliphatic, alicyclic, aromatic-aliphatic and/or aromatic linkage; preferably, the isocyanate is selected from diisocyanates having isocyanate groups with aliphatic, alicyclic, aromatic-aliphatic and/or aromatic linkage.

5. The blocked isocyanate prepolymer system of any one of claims 1 to 4, characterized in that the blocking agent is selected from pyrazole, alcohol, oxime, lactam, P-dicarbonyl compounds and phenolic compounds; preferably, the blocking agent is selected from phenolic compounds; more preferably, the blocking agent is selected from phenolic compounds having an OH value of 184 to 206 mg KOH/g, preferably 184 to 200 mg KOH/g, more preferably 186 to 192 mg KOH/g; even more preferably, the blocking agent is selected from phenol, nonylphenol, cardanol, bisphenol A and bisphenol F; still more preferably, the blocking agent is selected from nonylphenol and cardanol.

6. The blocked isocyanate prepolymer system of any one of claims 1 to 5, characterized in that the non-hydrophilic polyhydroxyl compound is selected from polymer polyols having a number average molecular weight of 1,000 to 10,000 g/mol, preferably 1,000 to 8,000 g/mol, more preferably 1,000 to 4,000 g/mol.

7. The blocked isocyanate prepolymer system of any one of claims 1 to 6, characterized in that the non-hydrophilic polyhydroxyl compound is selected from polymer polyols having an average functionality of 1.8 to 6.0, preferably 1.8 to 4.0, more preferably 1.9 to 2.2; preferably, the non-hydrophilic polyhydroxyl compound is selected from addition products of ethylene oxide and/or propylene oxide under 1,2- propanediol, 1,3-propanediol, glycerol, trimethylolpropane, ethylenediamine and/or pentaerythritol initiated polymerization; more preferably, the non-hydrophilic polyhydroxyl compound is selected from addition products of ethylene oxide and/or propylene oxide under 1,2-propanediol, 1,3-propanediol, dipropylene glycol and/or diethylene glycol initiated polymerization.

8. The blocked isocyanate prepolymer system of any one of claims 1 to 7, characterized in that the active hydrogen compound comprising a hydrophilic group is selected from organic alcohol compounds, organic amine compounds, mercapto compounds and mixtures thereof; preferably, the active hydrogen compound comprising a hydrophilic group have a hydrophilic group on a side chain; more preferably, the active hydrogen compound comprising a hydrophilic group is selected from dihydroxymethylpropionic acid, dihydroxymethylbutyric acid, dihydroxypropanesulfonic acid, dimercaptopropanesulfonic acid, sodium dihydroxypropanesulfonate, sodium dimercaptopropanesulfonate, sodium ethylenediamine ethanesulfonate, sodium diaminobenzenesulfonate, cyclohexylaminoalkylsulfonic acid (e.g., cyclohexylaminopropanesulfonic acid, cyclohexylaminobutanesulfonic acid, etc.), N-(2-aminoethyl)-P-alanine, 2-(2- aminoethylamino)ethanesulfonic acid, monohydric alcohols comprising methyl- terminated poly(ethylene oxide) polyether segments and diols comprising poly(ethylene oxide) polyether segments on a side chain.

9. A method for preparing the blocked isocyanate prepolymer system of any one of claims 1 to 8, comprising the steps of:

A. reacting the isocyanate comprising two or more isocyanate groups with the blocking agent to obtain a partially blocked isocyanate intermediate; and

10. A method for preparing the blocked isocyanate prepolymer system of any one of claims 1 to 8, comprising the steps of: reacting an isocyanate comprising two or more isocyanate groups first with a non- hydrophilic polyhydroxyl compound and an active hydrogen compound comprising a hydrophilic group, and then with a blocking agent, until the amount of free isocyanate groups is less than 0.5 % by weight, preferably less than 0.2 % by weight, more preferably less than 0.1 % by weight, to obtain a water-dispersible blocked isocyanate prepolymer system.

11. The blocked isocyanate prepolymer aqueous dispersion prepared from the blocked isocyanate prepolymer system of any one of claims 1 to 8.

12. Use of the blocked isocyanate prepolymer system of any one of claims 1 to 8 or the blocked isocyanate prepolymer aqueous dispersion of claim 11 for preparing polyurethane plastics, adhesives, sealing materials, encapsulating materials, fiber sizing materials or coating materials.

13. Polyurethane plastics, adhesives, sealing materials, encapsulating materials, fiber sizing materials or coating materials comprising the blocked isocyanate prepolymer of any one of claims 1 to 8 or the blocked isocyanate prepolymer aqueous dispersion of claim 11.