Blocked isocyanate prepolymer system as well as preparation method and application thereof

Abstract

The invention relates to a blocked isocyanate prepolymer system as well as a preparation method and application thereof. The blocked isocyanate prepolymer system is prepared by reacting isocyanate with two or more isocyanate groups with a sealing agent and a polyhydroxy compound in sequence. The blocked isocyanate prepolymer system disclosed by the invention can be processed into various products, is wide in application field, has relatively low viscosity even if being not diluted by a solvent, and is beneficial to subsequent use.

Description

Technical Field

[0001] The present invention belongs to the technical field of isocyanate, and specifically relates to a blocked isocyanate prepolymer system and a preparation method and application thereof. Background Art

[0002] Epoxy resins are widely used in machinery, home appliances, transportation, construction and other fields due to their good thermal stability, excellent bonding and adhesion, and chemical resistance. However, epoxy systems are brittle, especially at low temperatures. In order to improve and increase flexibility, good and permanent elasticization of epoxy resins can be achieved by combining polyurethane.

[0003] DE 2338256 A1 discloses the production of high molecular weight, amine-terminated polyetherurethaneureas by reacting prepolymers containing free isocyanate groups with amines in highly diluted solutions and then curing with epoxy resins. However, the use of solvents required for this is practically disadvantageous from both a technical and a physiological point of view. On the other hand, the viscosity of the solvent-free reaction products that have been produced is too high for practical use.

[0004] DE 2152606 A1 discloses reactive systems based on alkylphenol-blocked polyisocyanates and polyamines, which can optionally also be cured in combination with epoxy resins. These reactive systems also have several disadvantages with regard to application technology, for example, the reactive systems have a relatively high viscosity and the released blocking agents have a relatively low molecular weight, which leads to their migration out of the coating over time and poor adhesion of the coating to the substrate.

[0005] US 6060574 A discloses a reactive composition consisting of a reversibly blocked organic polyisocyanate and at least one polyamine having at least two primary amino groups, optionally further comprising a compound containing an epoxy group. The blocking agent used as the organic polyisocyanate is a hydrocarbon resin having a phenolic OH group. Compared with the polyisocyanates blocked by alkylphenols, this blocked polyisocyanate is characterized in that the reactivity to polyamines is significantly reduced. The organic polyisocyanate used can be a prepolymer obtained by reacting a polyol with an excess of diisocyanates or polyisocyanates. However, the viscosity of the blocked polyisocyanates is generally high, and sometimes even requires dilution with an organic solvent.

[0006] All reversibly blocked isocyanate prepolymers described in the prior art, which are prepared by reacting isocyanate prepolymers containing isocyanate groups with blocking agents, have hitherto had high viscosities due to the intermolecular hydrogen bonding of the urethane groups, which is a significant disadvantage for the processing of the corresponding reactive systems comprising polyamines and optionally epoxides. Due to the high viscosity of these systems, spray application is generally not possible.

[0007] Therefore, there is a need in the art for a low viscosity blocked isocyanate prepolymer system. Summary of the invention

[0008] It is an object of the present invention to provide a low viscosity blocked isocyanate prepolymer system.

[0009] Another object of the present invention is to provide a method for preparing a low-viscosity blocked isocyanate prepolymer system.

[0010] Therefore, according to a first aspect of the present invention, there is provided a blocked isocyanate prepolymer system, characterized in that:

[0011] It is prepared by reacting an isocyanate having two or more isocyanate groups with a blocking agent and a polyol.

[0012] in:

[0013] The molar ratio of the active groups of the blocking agent that can react with isocyanate to the total isocyanate groups of the isocyanate is 1:1.8 to 1:2.5.

[0014] The molar ratio of the OH groups of the polyhydroxy compound to the isocyanate groups remaining after the blocking reaction is 1:0.8 to 1:1.2.

[0015] According to a second aspect of the present invention, there is provided a method for preparing the above-mentioned blocked isocyanate prepolymer system, characterized in that it comprises the following steps:

[0016] A. reacting an isocyanate having two or more isocyanate groups with a blocking agent, wherein the molar ratio of the active groups of the blocking agent that can react with isocyanate to the total isocyanate groups of the isocyanate is 1:1.8 to 1:2.5; and

[0017] B. allowing the remaining isocyanate groups to further react with a polyol until the content of free isocyanate groups is less than 0.5% by weight relative to the total weight of the entire reaction system, wherein the molar ratio of the OH groups of the polyol to the isocyanate groups remaining after the blocking reaction is 1:0.8 to 1:1.2.

[0018] According to a third aspect of the present invention, there is provided use of the blocked isocyanate prepolymer system for preparing polyurethane plastics, adhesives, sealing materials, potting materials, fiber sizing agents or coatings.

[0019] According to a fourth aspect of the present invention, there is provided a polyurethane plastic, adhesive, sealing material, potting material, fiber sizing agent or coating comprising the above-mentioned blocked isocyanate prepolymer system.

[0020] The blocked isocyanate prepolymer system of the present invention can be processed into various products and has a wide range of application fields. Moreover, the blocked isocyanate prepolymer system of the present invention has a relatively low viscosity even without solvent dilution, which is beneficial for subsequent use. DETAILED DESCRIPTION

[0021] Certain specific embodiments of the invention will now be described for purposes of illustration and not limitation.

[0022] Closed isocyanate prepolymer system

[0023] According to a first aspect of the present invention, there is provided a blocked isocyanate prepolymer system, characterized in that:

[0024] It is prepared by reacting an isocyanate having two or more isocyanate groups with a blocking agent and a polyol.

[0025] in:

[0026] The molar ratio of the active groups of the blocking agent that can react with isocyanate to the total isocyanate groups of the isocyanate is 1:1.8 to 1:2.5,

[0027] The molar ratio of the OH groups of the polyhydroxy compound to the isocyanate groups remaining after the blocking reaction is 1:0.8 to 1:1.2.

[0028] The blocked isocyanate prepolymer of the present invention has a low viscosity, and the viscosity measured at 23° C. according to DIN EN ISO 3219:1994-10 is usually lower than 24000 mPas. Even without solvent dilution, the blocked isocyanate prepolymer has a low viscosity, which is beneficial for subsequent use.

[0029] Preferably, the blocked isocyanate prepolymer has a viscosity of not more than 20,000 mPas measured at 23° C. according to DIN EN ISO 3219:1994-10.

[0030] The system contains fully blocked isocyanate in addition to the blocked isocyanate prepolymer formed by partially blocked isocyanate and polyol.

[0031] The term "fully blocked isocyanate" as used herein refers to a product formed by the reaction of all isocyanate groups contained in an isocyanate molecule with a blocking agent.

[0032] Preferably, the weight average molecular weight of the fully blocked isocyanate is in the range of 380-1400.

[0033] Preferably, the molar ratio of the active groups of the blocking agent that can react with isocyanate to the total isocyanate groups of the isocyanate is 1:1.9 to 1:2.5, more preferably the molar ratio is 1:1.95 to 1:2.5, and most preferably the molar ratio is 1:2.0 to 1:2.5.

[0034] Preferably, the fully blocked isocyanate accounts for 1%-30% of the total weight of the blocked isocyanate prepolymer system, more preferably, the fully blocked isocyanate accounts for 5%-22%, and even more preferably, the fully blocked isocyanate accounts for 8%-15%. This ratio can be determined by GPC testing and the corresponding component peak area ratio.

[0035] Preferably, the blocked isocyanate prepolymer system does not contain a solvent.

[0036] Isocyanate

[0037] The isocyanates used in the present invention may be any diisocyanates and / or polyisocyanates having aliphatically, cycloaliphatically, araliphatically and / or aromatically bonded isocyanate groups.

[0038] As used herein, the term "polyisocyanate" refers to isocyanates having an isocyanate group functionality greater than two.

[0039] Suitable diisocyanates are any diisocyanates which are obtainable in any manner, for example by phosgenation in the liquid or gas phase or by a phosgene-free route, for example by thermal cleavage of carbamate compounds.

[0040] Preferred diisocyanates are those with aliphatically, cycloaliphatically, araliphatically and / or aromatically bonded isocyanate groups, with a molecular weight in the range from 140 to 400, for example 1,4-butane diisocyanate, 1,5-pentane diisocyanate (PDI), 1,6-hexane diisocyanate (HDI), 2-methyl-1,5-pentane diisocyanate, 1,5-diisocyanato-2,2-dimethylpentane, 2,2,4- or 2,4,4-trimethyl-1,6-hexane diisocyanate, 1,10-decane diisocyanate, 1,3- and 1,4-cyclohexane diisocyanate, 1,3- and 1,4-bis(isocyanatomethyl)cyclohexane, 1-isocyanato-3-diisocyanato-2,2-dimethylpentane. , 3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI), 4,4'-dicyclohexylmethane diisocyanate, 1-isocyanato-1-methyl-4(3)isocyanatomethylcyclohexane, bis(isocyanatomethyl)norbornane, 1,3- and 1,4-bis(2-isocyanatoprop-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), norbornane diisocyanate (NBDI) or any mixture of these diisocyanates.

[0041] Preferred diisocyanates are diisocyanates having isocyanate groups of different reactivities, for example 2-methyl-1,5-pentane diisocyanate, 1,5-diisocyanato-2,2-dimethylpentane, 2,2,4- or 2,4,4-trimethyl-1,6-hexane diisocyanate, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI), 1-isocyanato-1-methyl-4(3)isocyanatomethylcyclohexane, toluene diisocyanate (toluene 2,4- and 2,6-diisocyanate, TDI), 2,4′-diphenylmethane diisocyanate (MDI) or any mixtures of these diisocyanates.

[0042] Particularly suitable are 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI), toluene diisocyanate (toluene 2,4- and 2,6-diisocyanate, TDI), 2,4'-diphenylmethane diisocyanate (MDI) or any mixtures of these diisocyanates. Preference is given to toluene diisocyanate (toluene 2,4- and 2,6-diisocyanate, TDI), in particular the 2,4- and 2,6-isomers and technical mixtures of these two isomers.

[0043] Very particularly suitable aromatic diisocyanates are toluene 2,4-diisocyanate and technical mixtures thereof consisting of 70 to 90% of toluene 2,4-diisocyanate and 30 to 10% of toluene 2,6-diisocyanate.

[0044] Suitable isocyanates are also any polyisocyanates having a uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione and / or oxadiazinetriaone structure which are prepared by modification of simple aliphatic, cycloaliphatic, araliphatic and / or aromatic diisocyanates and / or polyisocyanates, for example those of the type mentioned above, such as, for example, 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 mixtures of these isocyanates.

[0045] Blocking agent

[0046] The blocking agents that can be used in the present invention include, for example, pyrazoles, alcohols, oximes, lactams, β-dicarbonyl compounds, and phenolic compounds.

[0047] As an example of pyrazole compounds, 3,5-dimethylpyrazole may be mentioned.

[0048] As examples of alcohol compounds, mention may be made of methanol, ethanol, 2-propanol, n-butanol, sec-butanol, 2-ethyl-1-hexanol, 2-methoxyethanol, 2-ethoxyethanol and 2-butoxyethanol.

[0049] As examples of oxime compounds, butanone oxime, acetone oxime, formaldehyde oxime, acetaldehyde oxime and cyclohexanone oxime may be mentioned.

[0050] As examples of lactam compounds, mention may be made of ε-caprolactam, δ-valerolactam and γ-butyrolactam.

[0051] As examples of β-dicarbonyl compounds, mention may be made of dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, di-n-propyl malonate, diisopropyl malonate, di-n-butyl malonate and diisobutyl malonate.

[0052] As examples of phenolic compounds, phenol, nonylphenol, cardanol, bisphenol A and bisphenol F may be mentioned.

[0053] 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 mgKOH / g, preferably 184 to 200 mgKOH / g, more preferably 186 to 192 mgKOH / g.

[0054] Still more preferably, the blocking agent is selected from one of nonylphenol and cardanol or a mixture thereof, and cardanol is further preferred.

[0055] Cardanol has the following structure:

[0056]

[0057] Where R represents C 15 H 31-n , where n=0, 2, 4 and 6.

[0058] Polyhydroxy compound

[0059] The polyols which can be used in the present invention can be any polyols, for example the polymer polyols known in polyurethane chemistry, for example polyether polyols, polyester polyols, polycarbonate polyols, polyurethane polyols and / or polyacrylate polyols.

[0060] The polyols generally have an average functionality of 1.8 to 6.0, preferably 1.8 to 4.0, more preferably 1.9 to 2.2. The number average molecular weight of these polyols (determined according to DIN 55672-I: 2016-03) is generally 1000 to 10000 g / mol, preferably 1000 to 4000 g / mol, more preferably 2000 to 4000 g / mol. Any mixture of these polyols can also be used.

[0061] Preferably, the polyol is a polyether polyol or a mixture of polymer polyols comprising at least one polyether polyol.

[0062] More preferably, the polyol is selected from polyether polyols, for example those of the type mentioned in DE 26 22 951 B, column 6, line 65 to column 7, line 26, EP-A 0 978 523, page 4, line 45 to page 5, line 14 or WO 2011 / 069966, page 4, line 20 to page 5, line 23, provided that they comply with the above instructions regarding functionality and molecular weight.

[0063] Particularly preferred polyether polyols are addition products of ethylene oxide and / or propylene oxide on 1,2-propanediol, 1,3-propanediol, dipropylene glycol, diethylene glycol, glycerol, trimethylolpropane, triethanolamine, ethylenediamine and / or pentaerythritol, or polytetramethylene ether glycols in the above molecular weight range obtainable, for example, by polymerization of tetrahydrofuran according to Angew. Chem. 72, 927 (1960).

[0064] Very particularly preferred are addition products of ethylene oxide and / or propylene oxide under the initiation of polymerization of 1,2-propanediol, 1,3-propanediol, dipropylene glycol and / or diethylene glycol, and further particularly preferred are addition products of ethylene oxide and / or propylene oxide under the initiation of polymerization of 1,2-propanediol, wherein the polyether polyol contains 80% by weight of 1,2-propanediol, more preferably 90% by weight of 1,2-propanediol, and most preferably 100% by weight of 1,2-propanediol.

[0065] Method for preparing a closed isocyanate prepolymer system

[0066] According to a second aspect of the present invention, there is provided a method for preparing the above-mentioned blocked isocyanate prepolymer system, which is characterized in that it comprises the following steps:

[0067] A. React an isocyanate having two or more isocyanate groups with a blocking agent, wherein the molar ratio of the reactive groups of the blocking agent capable of reacting with the isocyanate to all the isocyanate groups of the isocyanate is 1:1.8 to 1:2.5; and

[0068] B. Further react the remaining isocyanate groups with a polyhydroxy compound until the content of free isocyanate groups in the total weight of the whole reaction system is less than 0.5% by weight, wherein the molar ratio of the OH groups of the polyhydroxy compound to the remaining isocyanate groups after the blocking reaction is 1:0.8 to 1:1.2.

[0069] The isocyanate, blocking agent and polyhydroxy compound are as defined above for the first aspect of the present invention.

[0070] Preferably, the molar ratio of the reactive groups of the blocking agent capable of reacting with the isocyanate to all the isocyanate groups of the isocyanate is 1:1.9 to 1:2.5, more preferably the molar ratio is 1:1.95 to 1:2.5, and most preferably the molar ratio is 1:2.0 to 1:2.5.

[0071] Preferably, the reaction of the isocyanate with the blocking agent in step A is carried out at a temperature of 0 to 150 °C, preferably 20 to 140 °C, more preferably 40 to 100 °C.

[0072] Preferably, step B is performed when the amount of residual isocyanate (NCO) reaches the range of ±0.5% of the theoretical calculated amount of NCO.

[0073] The reaction of isocyanate and blocking agent can be carried out in the presence of a catalyst to accelerate the reaction and thus shorten the reaction time.

[0074] Suitable catalysts may be the catalysts known in polyurethane chemistry, for example metal organic compounds, such as tin(II) octoate, dibutyltin(II) diacetate, dibutyltin(II) laurate, 2,3-dimethyl-3,4,5,6-tetrahydropyrimidine, tertiary amines such as triethylamine, diazabicyclooctane, 1,8-diazabicyclo[5.4.0]undec-7-ene and mixtures containing two or more of the above compounds.

[0075] The suitable amount of catalyst is 0.01% to 0.5%, preferably 0.02% to 0.3%, more preferably 0.02% to 0.2%.

[0076] Preferably, the molar ratio of the OH groups of the polyol to the isocyanate groups remaining after the blocking reaction is 1:0.9 to 1:1.1.

[0077] The reaction of the isocyanate groups and the polyol can be carried out under conditions well known in the polyurethane art.

[0078] For example, the reaction of the isocyanate group and the polyol in step B may be carried out at a temperature of 0 to 250°C, preferably 20 to 140°C, more preferably 40 to 100°C.

[0079] Preferably, step B is terminated when the content of free isocyanate groups is less than 0.2% by weight.

[0080] More preferably, step B is terminated when the content of free isocyanate groups is less than 0.1 wt %.

[0081] The reaction of the isocyanate group and the polyol may be carried out in the presence of a catalyst to accelerate the reaction and thereby shorten the reaction time.

[0082] Suitable catalysts can be the same as or different from the catalysts for the reaction of isocyanate with blocking agent and are selected from known catalysts in polyurethane chemistry, in particular the compounds or mixtures thereof listed above for the reaction of isocyanate with blocking agent, preferably the same catalyst as the catalyst for the reaction of isocyanate with blocking agent. Suitable catalyst amounts are 0.01% to 0.5%, preferably 0.02% to 0.3%, more preferably 0.02% to 0.2%.

[0083] The reactions of steps A and B can also be carried out by using a solvent which is inert to the reactive groups of the starting components.

[0084] 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-methoxy-n-butyl acetate, acetone, 2-butanone, 4-methyl-2-pentanone, cyclohexanone, toluene, xylene, chlorobenzene, white spirit, more highly substituted aromatic hydrocarbons, such as those sold under the names solvent naphtha, Solvesso, Isopar, Nappar (ExxonMobil Chemical Central Europe, 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-methylpyrrolidone and N-methylcaprolactam, or any mixtures of these solvents.

[0085] Preferably, steps A and B are carried out without using a solvent to obtain a solvent-free blocked isocyanate prepolymer.

[0086] Use of the closed isocyanate prepolymer system and products containing the same

[0087] According to a third aspect of the present invention, there is provided use of the blocked isocyanate prepolymer system for preparing polyurethane plastics, adhesives, sealing materials, potting materials, fiber sizing agents or coatings.

[0088] The blocked isocyanate prepolymer system of the present invention can be processed into various products, such as polyurethane plastics, adhesives, sealing materials, potting materials, fiber impregnation agents or coatings, and its application fields include but are not limited to water conservancy projects, shipbuilding (such as ballast tanks), transportation vehicles, green energy, pipes and floors, etc.

[0089] Therefore, according to a fourth aspect of the present invention, there is provided a polyurethane plastic, adhesive, sealing material, potting material, fiber sizing or coating comprising the above-mentioned blocked isocyanate prepolymer system.

[0090] In some embodiments, a solvent-free reactive system is provided, comprising the blocked isocyanate prepolymer system described above, a polyamine, and optionally an epoxide.

[0091] Preferably, the polyamines are polyamines having at least two primary and optionally also secondary amino groups per molecule and preferably having an average molecular weight of 60 to 500. Examples which may be mentioned include ethylenediamine, 1,2- and 1,3-diaminopropane, 1,4-diaminobutane, 2,2,4- and / or 2,4,4-trimethylhexanediamine, isomeric xylenediamine, diaminodiphenylmethane, diaminodiphenyl sulfone, 1,4-diaminocyclohexane, 4,4′-diaminodicyclohexylmethane, 1,3-diaminocyclopentane, 4,4′-diaminodicyclohexylsulfone, 4,4′-diaminodicyclohexylpropane, 1,3-diaminodicyclopentane, 4,4′-diaminodicyclohexylpropane, 4,4′-diaminodicyclohexylpropane, 1,4-diaminodicyclohexylpropane, 4,4′-diaminodicyclohexylpropane, 4,4′-diaminodicyclohexylpropane, 4,4′-diaminodicyclohexylpropane, 4,4′-diaminodicyclohexylpropane, 4,4′-diaminodicyclohexylpropane, 4,4′-diaminodicyclohexylpropane, 4,4′-diaminodicyclohexylpropane. 2,2,3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, 3-aminomethyl-3,3,5-trimethylcyclohexylamine (isophoronediamine), 3(4)-aminomethyl-1-methylcyclohexylamine, technical grade bisaminomethyltricyclodecane, octahydro-4,7-methyleneindene-1,5-dimethylamine, and phenol-formaldehyde amine curing agents synthesized from phenol-formaldehyde resins and amine compounds, or polyamines having secondary amino groups in addition to at least two primary amino groups, such as diethylenetriamine or triethylenetetramine.

[0092] Particularly preferred are polyamines, especially diamines, within the abovementioned molecular weight range which contain one or more cycloaliphatic rings. Examples include, for example, 1,4-diaminocyclohexane, 4,4'-diaminodicyclohexylmethane, 1,3-diaminocyclopentane, 4,4'-diaminodicyclohexylsulfone, 4,4'-diaminodicyclohexylpropane-1,3, 4,4'-diaminodicyclohexylpropane-2,2, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, 3-aminomethyl-3,3,5-trimethylcyclohexylamine (isophoronediamine), 3- and 4-aminomethyl-1-methylcyclohexylamine or technical-grade bisaminomethyltricyclodecane.

[0093] It is also possible to use, as a component of the amine component, an adduct prepared by reacting an excess of the polyamine described above with an epoxy resin of the type described below.

[0094] The polyamines may also comprise polyether polyols prepared by reacting polyether polyols with ammonia and available, for example, from Huntsman Polyetheramines sold under the trade name ANTIQUALINE®.

[0095] The epoxide is a compound having an epoxy group. Suitable compounds having epoxy groups are epoxy resins containing an average of not less than one epoxy group per molecule. Examples of suitable epoxy resins are glycidyl ethers of polyols such as butanediol, hexanediol, glycerol, hydrogenated diphenolyl propane or polyphenols such as resorcinol, diphenolyl propane-2,2 (bisphenol A), diphenolyl methane (bisphenol F) or phenolic condensates. Polycarboxylic acids such as glycidyl esters of hexahydrophthalic acid or dimer fatty acids can be used.

[0096] Particular preference is given to using liquid epoxy resins based on epichlorohydrin and diphenolylpropane-2,2 (bisphenol A) or diphenolylmethane (bisphenol F) or mixtures thereof. If desired, the viscosity of the mixture can be reduced with monofunctional epoxy compounds, thereby improving processing. Examples of these are aliphatic and aromatic glycidyl ethers, such as butyl glycidyl ether, phenyl glycidyl ether, or glycidyl esters, such as versatyl glycidyl ester, or epoxides, such as styrene oxide or 1,2-decene oxide.

[0097] The solvent-free reactive systems can be cured at room temperature and can be used as coatings. Coatings made from these reactive systems have excellent impact resistance and shock resistance, while being flexible and elastic.

[0098] The descriptions of various features in this application can be combined with each other if they are not contradictory, and all fall within the scope of protection requested by this application.

[0099] The term "and / or" used in the present application means one or all of the mentioned elements.

[0100] All percentages in this application are by weight unless otherwise stated.

[0101] The analytical measurements described in this application were all performed at 23°C unless otherwise stated.

[0102] The weight average molecular weight and number average molecular weight of the isocyanate described in the present application (including fully blocked isocyanate) are measured according to DIN 55672-1:2016-03 by TOSOH HLC-8320EcoSEC type gel chromatograph using polystyrene standards, high-performance general chromatographic columns 4-column set (TSKgel G2000HXL, TSKgel G2500HXL, TSKgel G3000HXL and TSKgel G4000HXL, chromatographic column filler is styrene-divinylbenzene copolymer) and differential refractive index detector, the eluent is tetrahydrofuran, the flow rate is 1.0 ml / min, the pressure is 6.4 MPa, and the column temperature is 40 ° C.

[0103] The isocyanate group (NCO) content is determined by titration according to DIN-EN ISO 11909: 2007-05, and the determined data include the content of free and potentially free isocyanate groups.

[0104] Latent free isocyanate groups can become free isocyanate groups under conditions such as heating.

[0105] Viscosity measurements were performed using a HAAKE VT550 viscometer according to DIN EN ISO 3219:1994-10.

[0106] Impact resistance is tested according to ASTM 2794-1993. A 120 μm wet film is applied on a tinplate substrate. After sufficient curing and maintenance, the film is subjected to a reverse impact test with the film facing downward. The test data is represented by the maximum drop height (cm) that the film can withstand without cracking.

[0107] The breaking stress and breaking elongation are determined according to DIN EN ISO 527-2:2012-06. A 250 μm wet film is scraped onto a glass plate coated with a release agent. After sufficient curing and maintenance, the dry film is peeled off and cut into dumbbell II shape. The breaking stress and breaking elongation are measured using a tensile testing machine at room temperature.

[0108] The Shore hardness D is tested according to DIN 53505:2000-08. A film with the required thickness is prepared according to the standard. After sufficient curing and maintenance, it is tested on a Shore hardness tester to obtain the result.

[0109] The pendulum hardness test method is carried out according to DIN EN ISO 1522-2007. After a 120μm wet film is applied to a glass substrate and fully cured, the pendulum swing time (in seconds) is measured on a pendulum tester. The pendulum time in the pendulum test result can indicate the hardness of the paint film. The longer the pendulum time, the higher the hardness of the paint film.

[0110] The terms “comprising” and “including” described in the present application encompass a case where the component also includes or comprises other elements not explicitly mentioned as well as a case where the component consists of the mentioned elements.

[0111] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the invention belongs. When the definition of a term in this specification conflicts with the meaning commonly understood by those skilled in the art to which the invention belongs, the definition described in this article shall prevail.

[0112] Unless otherwise indicated, all numerical values ​​expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as modified by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth herein are approximations that can vary depending upon the desired properties desired to be obtained.

[0113] Example

[0114] The following will further illustrate the concept, specific structure and technical effects of the present invention in combination with the embodiments, so that those skilled in the art can fully understand the purpose, characteristics and effects of the present invention. It is not difficult for those skilled in the art to understand that the embodiments herein are only for illustrative purposes, and the scope of the present invention is not limited thereto.

[0115] Main raw materials

[0116] The main raw materials used in the following examples are as follows.

[0117] T 80: contains about 80 wt % toluene 2,4-diisocyanate and 20 wt % toluene 2,6-diisocyanate, from Covestro Polymers (China) Co., Ltd.

[0118] IPDI: Isophorone diisocyanate, from Covestro Polymers (China) Co., Ltd.

[0119] NX 2026: Cardanol, from Cardolite Specialty Chemicals Europe NV.

[0120] DP 2000E: polyether diol, OH value 54-58 mg KOH / g, from Guodu Chemical Co., Ltd.

[0121] EG 1000: polyether diol, OH value 110-114 mg KOH / g, from Shandong Bluestar Dongda Co., Ltd.

[0122] DP 4000E: polyether diol, OH value 26-30 mg KOH / g, from Guodu Chemical Co., Ltd.

[0123] Acol Polyol 1026: Polyether diol, OH value 28 mgKOH / g, from Covestro Polymers (China) Co., Ltd.

[0124] Zirconium 18: Catalyst zirconium octanoate, from Borcher OM Group.

[0125] Tin(II) octoate: catalyst, from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0126] DER 331: Bisphenol A epoxy resin, epoxy equivalent weight is 180-200 g / mol, from Dow Chemical.

[0127] Desmocap 14CNB: Blocked isocyanate, viscosity 30200mPas, from Covestro Polymers (China) Co., Ltd.

[0128] IPDA: isophorone diamine, amine value 550-580 mgKOH / g, from Covestro Polymers (China) Co., Ltd.

[0129] Invention Example 1

[0130] 420.0 g of toluene diisocyanate ( T 80) was added into a reaction bottle, heated to 90°C with stirring, and 766.8 g of cardanol (NX 2026) was slowly added dropwise into the reaction solution through a dropping funnel over about 4 hours. After the addition was completed, the reaction was continued at 90°C with stirring until the NCO content was 8.6% (theoretical NCO content was about 8.1%), and then cooled to obtain cardanol-blocked toluene diisocyanate.

[0131] 200.0 g of the cardanol-blocked toluene diisocyanate prepared above was placed in a reaction bottle, heated to 80° C. under stirring, and then 435.4 g of polyether diol (DP 2000E) was slowly added dropwise through a dropping funnel. After the addition was completed, the reaction was continued at 80° C. until NCO% <0.4%. After cooling, a blocked isocyanate prepolymer 1 was obtained, the measured viscosity was 17200 mPas, and the fully blocked isocyanate content was 14.9%.

[0132] Comparative Example 1

[0133] 172.4 g of polyether diol (DP 2000E) and 30.0 g of toluene diisocyanate ( T 80) was prepolymerized at 90° C. for about 3 hours until a theoretical NCO content of 3.7% was reached.

[0134] Then 61.5 g of cardanol (NX 2026) and 0.2 g of catalyst tin (II) octoate were added and stirred at 65° C. until the NCO content was less than 0.4%. Then 0.26 g of benzoyl chloride was added and stirred for another 30 minutes, and after cooling, blocked isocyanate prepolymer 2 was obtained with a viscosity of 173300 mPas and a fully blocked isocyanate content of 0%.

[0135] Invention Example 2

[0136] 500.0 g of polyether diol (EG 1000) was placed in a reaction bottle, heated to 60° C. under stirring, and then 495.6 g of cardanol-blocked toluene diisocyanate obtained in Example 1 was slowly added to the reaction bottle through a dropping funnel. After the addition was completed, the reaction was continued at 60° C. until NCO% <0.5%. After cooling, a blocked isocyanate prepolymer 3 was obtained, the measured viscosity was 23900 mPas, and the fully blocked isocyanate content was 14.7%.

[0137] Invention Example 3

[0138] 600.0 g of polyether diol (DP 4000E) was placed in a reaction bottle, heated to 70° C. under stirring, 0.4 g of catalyst zirconium isooctanoate (Zirconium 18) was added, and then 140.0 g of cardanol-blocked toluene diisocyanate obtained in Example 1 was slowly added dropwise to the reaction bottle through a dropping funnel. After the addition was completed, the reaction was continued at 70° C. until NCO% <0.3%. After cooling, a blocked isocyanate prepolymer 4 was obtained, the measured viscosity was 9900 mPas, and the fully blocked isocyanate content was 8.8%.

[0139] Invention Example 4

[0140] 120.0 g of isophorone diisocyanate (IPDI) was added to the reaction bottle, heated to 80°C with stirring, 0.3 g of catalyst tin (II) octoate and 171.6 g of phenol blocking agent (NX2026) were slowly added dropwise to the reaction solution through a dropping funnel over 3 hours, and after the addition was completed, the reaction was continued to stir at 80°C until the NCO was 7.2%, and then cooled to obtain cardanol-blocked isophorone diisocyanate.

[0141] 290.0 g of polyether diol (DP 4000E) was placed in a reaction bottle, heated to 60° C. under stirring, and then 80.0 g of cardanol-blocked isophorone diisocyanate was added dropwise to the reaction bottle through a dropping funnel. After the addition was completed, the reaction was continued at 60° C. until NCO% <0.4%. After cooling, a blocked isocyanate prepolymer 5 was obtained, the measured viscosity was 14400 mPas, and the fully blocked isocyanate content was 12.2%.

[0142] Invention Example 5

[0143] 100.0 g of polyether diol (Acol Polyol 1026) was placed in a reaction bottle, heated to 90° C. with stirring, 0.5 g of tin (II) octoate catalyst was added, and then 24.0 g of cardanol-blocked toluene diisocyanate obtained in Example 1 was slowly added dropwise to the reaction bottle through a dropping funnel. After the addition was completed, the reaction was continued at 90° C. until NCO% <0.3%. Then 0.7 g of benzoyl chloride was added and stirred for another 30 minutes. After cooling, blocked isocyanate prepolymer 6 was obtained, the measured viscosity was 13900 mPas, and the fully blocked isocyanate content was 9.2%.

[0144] Invention Example 6

[0145] 30.0 g of isophorone diisocyanate (IPDI) was added to a reaction bottle, heated to 65°C with stirring, 0.1 g of catalyst tin (II) octoate and 48.6 g of phenolic blocking agent (NX 2026) were slowly added to the reaction solution through a dropping funnel within 1 hour, and the reaction was continued at 65°C for about 1 hour after the addition was completed. 135.2 g of polyether diol (DP 2000E) was added dropwise, and the reaction was continued at 65°C for about 1 hour after the addition was completed until NCO% < 0.4%. After cooling, a blocked isocyanate prepolymer 6 was obtained, the measured viscosity was 8832 mPas, and the fully blocked isocyanate content was 21.3%.

[0146] Comparative Example 2

[0147] 287.4 g of polyether diol (Acol Polyol 1026) and 25.0 g of toluene diisocyanate ( T 80) was prepolymerized at 90°C for 3 hours until a theoretical NCO content of 1.9% was reached. Then 43.0 g of cardanol (NX 2026) and 1.6 g of catalyst tin (II) octoate were added and stirred at 65°C until the NCO content was less than 0.4%. Then 2.1 g of benzoyl chloride was added and stirred for another 30 minutes. After cooling, a blocked isocyanate prepolymer 7 was obtained, which had a high viscosity and could not be measured, and a fully blocked isocyanate content of 0%.

[0148] Comparative Example 3

[0149] 216.0 g of toluene diisocyanate ( T 80) was added to the reaction bottle, stirred and heated to 70°C, 413.5 g of polyether diol (Acol Polyol 1026) was slowly added to the reaction solution through a dropping funnel over three hours, and after the addition was completed, the reaction was continued at 70°C with stirring until the NCO was 14.1%, and then cooled, and then the excess toluene diisocyanate was removed by two-stage thin film evaporation (the first and second stage evaporator temperatures were 145°C and 140°C, respectively, and the vacuum degree was 0.2 mbar), to obtain 449 g of toluene diisocyanate prepolymer. The NCO% of the prepolymer was about 3.3%, and the viscosity was 5300 mPas.

[0150] 280.0 g of the toluene diisocyanate prepolymer obtained in the above step was placed in a reaction bottle, heated to 60° C. under stirring, 0.08 g of tin (II) octoate catalyst was added, and then 68.3 g of cardanol (NX2026) was slowly added dropwise through a dropping funnel. After the addition was completed, the reaction was continued at 60° C. until NCO% <0.5%. After cooling, a blocked isocyanate prepolymer 8 was obtained, the measured viscosity was 26500 mPas, and the fully blocked isocyanate content was 0%.

[0151] The isocyanates and polyols used in the above inventive examples and comparative examples and the viscosities of the resulting prepolymer systems at room temperature and the fully blocked isocyanate contents are summarized in Table 1.

[0152] Table 1

[0153]

[0154] N / A: Not available because it is above the upper measurement limit of the test instrument.

[0155] Invention Example 7

[0156] 28.46 g of the blocked isocyanate prepolymer 1 from Example 1 was added to 56.92 g of bisphenol A epoxy resin DER 331, and stirred to form a uniform mixture. Then, 14.63 g of IPDA (isophorone diamine) was added and stirred again to form a uniform mixture. The mixture was used to prepare a film, and various properties were tested after curing at room temperature for 7 days. The test results are summarized in Table 2.

[0157] Comparative Example 4

[0158] 18.5 g of IPDA (isophorone diamine) was added to 81.5 g of bisphenol A epoxy resin DER 331 and stirred to mix evenly. The mixture was used to prepare a film. After curing at room temperature for 7 days, various properties were tested. The test results are summarized in Table 2.

[0159] Comparative Example 5

[0160] 28.56 g of Desmocap 14CNB was added to 57.11 g of bisphenol A epoxy resin DER 331, and the mixture was stirred to a uniform mixture. Then, 14.33 g of IPDA (isophorone diamine) was added and stirred again to uniformly mix. The mixture was used to prepare a film. After curing at room temperature for 7 days, various properties were tested. The test results are summarized in Table 2.

[0161] Table 2

[0162]

[0163] As can be seen from Table 2, compared with Comparative Example 4 in which no blocked isocyanate prepolymer was added, the product obtained in Inventive Example 7 has a transparent, highly elastic and tough material. Compared with Comparative Example 5 (existing commercial product Desmocap 14CNB), the product obtained in Inventive Example 7 has the advantage of low viscosity while improving and enhancing the elasticity and toughness of the epoxy system.

[0164] The above only describes exemplary embodiments or embodiments of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention can be modified and varied in various ways. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention are included in the scope of the claims of this application.

Claims

1. A blocked isocyanate prepolymer system, It is characterized in that It is prepared by reacting an isocyanate having two or more isocyanate groups with a blocking agent and a polyol. in: The molar ratio of the active groups of the blocking agent that can react with isocyanate to the total isocyanate groups of the isocyanate is 1:1.8 to 1:2.5, The molar ratio of the OH groups of the polyhydroxy compound to the isocyanate groups remaining after the blocking reaction is 1:0.8 to 1:1.

2.

2. The blocked isocyanate prepolymer system according to claim 1, It is characterized in that The blocked isocyanate prepolymer has a viscosity measured at 23° C. according to DIN EN ISO 3219:1994-10 of not more than 24,000 mPas, preferably not more than 20,000 mPas.

3. The blocked isocyanate prepolymer system according to claim 1 or 2, It is characterized in that It also contains fully blocked isocyanate. Preferably, the weight average molecular weight of the fully blocked isocyanate is from 380 to 1400. More preferably, based on the total weight of the blocked isocyanate prepolymer system, the fully blocked isocyanate component accounts for 1%-30%, preferably 5%-22%, more preferably 8%-15%.

4. The blocked isocyanate prepolymer system according to any one of claims 1 to 3, It is characterized in that The isocyanate is selected from diisocyanates and / or polyisocyanates having aliphatic, alicyclic, araliphatic and / or aromatic isocyanate groups, preferably, the isocyanate is selected from diisocyanates having aliphatic, alicyclic, araliphatic and / or aromatic isocyanate groups, more preferably, from diisocyanates having isocyanate groups of different reactivity, for example, 2-methyl-1,5-pentane diisocyanate, 1,5-diisocyanato-2,2-diisocyanate, Methylpentane, 2,2,4- or 2,4,4-trimethyl-1,6-hexane diisocyanate, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane, 1-isocyanato-1-methyl-4(3)isocyanatomethylcyclohexane, toluene diisocyanate (toluene 2,4- and 2,6-diisocyanate, TDI), 2,4'-diphenylmethane diisocyanate (MDI) or any mixtures of these diisocyanates.

5. The blocked isocyanate prepolymer system according to any one of claims 1 to 4, It is characterized in that The blocking agent is selected from pyrazoles, alcohols, oximes, lactams, β-dicarbonyl compounds and phenolic compounds. Preferably, the blocking agent is selected from phenolic compounds; more preferably, it is selected from phenolic compounds having an OH value of 184 to 206 mgKOH / g, preferably 184 to 200 mgKOH / g, more preferably 186 to 192 mgKOH / g; more preferably, it is selected from phenol, nonylphenol, cardanol, bisphenol A and bisphenol F; and even more preferably, it is selected from nonylphenol and cardanol.

6. The blocked isocyanate prepolymer system according to any one of claims 1 to 5, It is characterized in that The polyol is selected from polyols having an average functionality of 1.8 to 6.0, preferably 1.8 to 4.0, more preferably 1.9 to 2.2 and a number average molecular weight of 1000 to 10000 g / mol, preferably 1000 to 4000 g / mol, more preferably 2000 to 4000 g / mol; preferably, the polyol is a polyether polyol or a mixture of polymer polyols comprising at least one polyether polyol, more preferably, the polyether polyol is selected from ethylene oxide and / or addition products of propylene oxide on 1,2-propylene glycol, 1,3-propylene glycol, dipropylene glycol, diethylene glycol, glycerol, trimethylolpropane, triethanolamine, ethylenediamine and / or pentaerythritol. Further preferably, the polyether polyol is selected from the addition products of ethylene oxide and / or propylene oxide on 1,2-propylene glycol, 1,3-propylene glycol, dipropylene glycol and / or diethylene glycol. Most preferably, the polyether polyol is selected from the addition products of ethylene oxide and / or propylene oxide on 1,2-propylene glycol.

7. The blocked isocyanate prepolymer system according to any one of claims 1 to 6, It is characterized in that It contains no solvent.

8. A method for preparing a blocked isocyanate prepolymer system according to any one of claims 1 to 7, It is characterized in that It includes the following steps: A. reacting an isocyanate having two or more isocyanate groups with a blocking agent, wherein the molar ratio of the active groups of the blocking agent that can react with isocyanate to the total isocyanate groups of the isocyanate is 1:1.8 to 1:2.5; and B. allowing the remaining isocyanate groups to further react with a polyol until the content of free isocyanate groups is less than 0.5% by weight relative to the total weight of the entire reaction system, wherein the molar ratio of the OH groups of the polyol to the isocyanate groups remaining after the blocking reaction is 1:0.8 to 1:1.

2.

9. The method according to claim 8, It is characterized in that The reaction of the isocyanate with the blocking agent in step A is carried out at a temperature of 0 to 150°C, preferably 20 to 140°C, more preferably 40 to 100°C.

10. The method according to claim 8 or 9, It is characterized in that When the amount of residual isocyanate (NCO) reaches the range of ±0.5% of the theoretically calculated amount of NCO, step B is performed.

11. The method according to any one of claims 8 to 10, It is characterized in that The preferred molar ratio of the active groups of the blocking agent that can react with isocyanate to the total isocyanate groups of the isocyanate is 1:1.9 to 1:2.5, more preferably 1:1.95 to 1:2.5, most preferably 1:2.0 to 1:2.

5.

12. The method according to any one of claims 8 to 11, It is characterized in that The preferred molar ratio of the OH groups of the polyol to the isocyanate groups remaining after the blocking reaction is 1:0.9 to 1:1.1, more preferably 1:0.95 to 1:1.

05.

13. The method according to any one of claims 8 to 12, It is characterized in that The reaction of the isocyanate groups and the polyol in step B is carried out at a temperature of 0 to 150°C, preferably 20 to 140°C, more preferably 40 to 100°C.

14. The method according to any one of claims 8 to 13, It is characterized in that Steps A and B are carried out without using a solvent.

15. Use of the blocked isocyanate prepolymer according to any one of claims 1 to 7 for preparing polyurethane plastics, adhesives, sealing materials, potting materials, fiber sizings or coatings.

16. A polyurethane, adhesive, sealant, potting material, fiber sizing or coating comprising the blocked isocyanate prepolymer system according to any one of claims 1 to 7.

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