Polyisocyanate composition and preparation method thereof

Abstract

The invention discloses a polyisocyanate composition and a preparation method thereof, and the polyisocyanate composition is derived from an aliphatic / alicyclic diisocyanate monomer and contains an isocyanurate structure. The polyisocyanate composition contains a trimolecular polymer, and when the polyisocyanate composition is stored at 100 DEG C for 24 hours, the change rate of the content of the trimolecular polymer is less than 10%. By controlling the change rate of the trimolecular polymer stored at high temperature, the high-temperature storage stability of the polyisocyanate can be effectively improved, and the polyisocyanate composition can be stored for 1 month at 50 DEG C, and the viscosity growth rate is less than or equal to 10%. Meanwhile, the polyisocyanate composition provided by the invention is simple in preparation process and easy to industrialize.

Description

Technical Field

[0001] This invention relates to a polyisocyanate composition, and more particularly to a polyisocyanate composition and its preparation method. Background Technology

[0002] Aliphatic / cyclic diisocyanates have irreplaceable advantages in the synthesis of anti-yellowing coatings, adhesives, and synthetic resins, and are therefore widely used. However, the low vapor pressure of monomeric aliphatic isocyanates limits their applications. Therefore, it is more common to convert them into polyisocyanates through polymerization to increase their tolerance to processing, improve their functionality and crosslinking degree, and further obtain products with superior performance.

[0003] Aliphatic polyisocyanates containing isocyanurate structures have excellent weather resistance, chemical resistance, and heat resistance, and are widely used in high-end fields such as automotive original paint, repair paint, and clear coat.

[0004] US4040992A, US4288586A, US4419513A, US673062A, etc. reported polyisocyanate compositions synthesized using quaternary ammonium bases or quaternary ammonium salts as catalysts.

[0005] Numerous reports, such as US4412073A and US7288213B1, document the synthesis of polyisocyanate compositions using nitrosilanes as catalysts.

[0006] Other types of catalysts, such as alkylphosphine, quaternary phosphine salts, tertiary amines, and manniene bases, have also been reported in patents and literature for their use in the synthesis of polyisocyanate compositions.

[0007] Due to long-distance transportation and the diversity of product storage environments, products with longer shelf lives are often required, which places higher demands on the storage stability of polyisocyanate compositions, especially their viscosity and high-temperature stability.

[0008] CN111072917A reports a method for preparing viscosity-stable isocyanates by controlling the ratio of urethane to (isocyanurate + ureadione) in the system. The basic principle is that substances with active hydrogen inhibit the formation of 1-nylon compounds. However, this method is only applicable to polyisocyanate compositions with a certain ureadione content, and many factors contribute to the increase in viscosity of the composition, not just the formation of 1-nylon compounds.

[0009] CN 113265037A reports that by end-capping a polyisocyanate composition with methanol and then controlling the pH of the aqueous extract to 6.5-7.5, a viscosity increase of less than 10% can be achieved after 15 months of storage at 30°C. However, the preparation of this composition requires treatment with ionic liquids or phosgene, which is a complex process and poses relatively significant safety risks.

[0010] Although numerous literature and patent reports describe adding equivalent or excess catalyst poisons to terminate the synthesis of polyisocyanate compositions, the termination of the synthesis reaction and the long-term storage stability of the isolated polyisocyanate composition are not the same concept. Currently, there are no universally applicable methods or guidelines for effectively improving the long-term storage stability of polyisocyanate compositions.

[0011] Therefore, it is particularly important to explore ways to improve the high-temperature stability (especially viscosity stability) of polyisocyanates during storage. Summary of the Invention

[0012] One of the objectives of this invention is to provide a polyisocyanate composition, particularly a polyisocyanate composition capable of long-term storage, especially a polyisocyanate composition containing isocyanurate groups capable of long-term storage, wherein the polyisocyanate composition has good storage stability and slow viscosity increase under high-temperature storage.

[0013] To achieve this objective, the present invention adopts the following technical solution:

[0014] One of the objectives of this invention is to provide a polyisocyanate composition derived from aliphatic and / or alicyclic diisocyanate monomers and containing an isocyanurate structure, wherein the polyisocyanate composition contains a three-molecule polymer, and the change rate of the content of the three-molecule polymer is less than 10% when the polyisocyanate composition is stored at 100°C for 24 hours.

[0015] Typically, polyisocyanate compositions containing isocyanurate structures mainly comprise a mixture of polymers of different molecular weights generated by the polymerization of diisocyanate monomers in the presence of a catalyst, including tri-molecular polymers, penta-molecular polymers, hepto-molecular polymers, and polymers with higher molecular weights. In addition, they may also contain urethane or urethane esters of different molecular weights obtained by alcohol modification. The tri-molecular polymer mentioned in this invention refers to a polymer generated by the polymerization reaction of three diisocyanate monomers.

[0016] According to the polyisocyanate composition provided by the present invention, the content of the three polymer molecules in the polyisocyanate composition is 30%-75%, preferably 45%-60%.

[0017] In a preferred embodiment of the present invention, the aliphatic and / or alicyclic diisocyanate monomer is selected from one or more of tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (HMDI), cyclohexane dimethylene diisocyanate (HXDI), and lysine diisocyanate, preferably pentamethylene diisocyanate and / or hexamethylene diisocyanate.

[0018] The polyisocyanate composition of the present invention contains, in addition to isocyanurate groups, any one or at least two combinations of ureidone groups, ureocarbamate groups, and iminooxadiazine dione groups;

[0019] Furthermore, the isocyanurate group is a functional group of a polyisocyanate formed by three diisocyanate monomers, and its specific structure is shown in formula (Ⅰ):

[0020]

[0021] Furthermore, the urea-formate group is a functional group of a polyisocyanate formed by two molecules of diisocyanate monomer and one molecule of alcohol, and its specific structure is shown in formula (II):

[0022]

[0023] Furthermore, the iminooxadiazine dione group is a functional group of a polyisocyanate formed from 3 molecules of diisocyanate monomers, and its specific structure is shown in formula (Ⅲ):

[0024]

[0025] Furthermore, the urea diketone group is a functional group of a polyisocyanate formed by two diisocyanate monomers, and its specific structure is shown in formula (Ⅳ):

[0026]

[0027] In this context, the dashed lines represent the connecting bonds of functional groups;

[0028] Preferably, in the polyisocyanate composition, the total molar amount of ureidone groups, urea carbamate groups, and iminooxadiazine dione groups is in the ratio of the molar amount of isocyanurate groups to 1%-10%.

[0029] The polyisocyanate composition provided according to the present invention has a viscosity of 1000-4000 mPa·s when measured at 25°C.

[0030] Preferably, the viscosity increase rate of the polyisocyanate composition is ≤10% after storage at 50°C for 1 month.

[0031] Another object of the present invention is to provide a method for preparing the polyisocyanate composition, the method comprising the following steps:

[0032] S1: To enable the isocyanate monomer to undergo a polymerization reaction in the presence of a catalyst;

[0033] S2: Add a terminator to terminate the reaction and obtain the product with the target conversion rate;

[0034] S3: Separate and remove the isocyanate monomers that did not participate in the reaction from the product of step S2;

[0035] S4: Add a certain amount of acidic substance to the isocyanate monomer;

[0036] S5: Mix the product separated in step S3 with the isocyanate monomer with acidic substance added in step S4, and react.

[0037] S6: Separate the product from step S5 to remove unreacted isocyanate monomers, and obtain the polyisocyanate composition.

[0038] In the preparation method, in step S1, the catalyst includes any one or at least two combinations of quaternary ammonium catalysts, silazane catalysts, alkylphosphine catalysts, tertiary amine catalysts or manniene base catalysts;

[0039] The amount of catalyst used relative to the total amount of isocyanate is 10-1000 ppm, preferably 20-500 ppm.

[0040] The polymerization reaction temperature is 30-120℃, preferably 40-100℃.

[0041] Preferably, the quaternary ammonium catalyst comprises any one or at least two combinations of choline hydroxide, trimethylhydroxyethylammonium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, tetraethylammonium formate, tetraethylammonium acetate, tetrabutylammonium decanoate, trimethylhydroxypropylammonium formate, trimethylhydroxypropylammonium acetate, trimethylhydroxypropylammonium decanoate, and trimethylhydroxyethylammonium formate, and more preferably benzyltrimethylammonium hydroxide and tetrabutylammonium decanoate;

[0042] Preferably, the silazane catalyst comprises hexamethyldisilazane and / or heptamethyldisilazane;

[0043] Preferably, the alkylphosphine catalyst comprises tributylphosphine and / or triphenylphosphine;

[0044] Preferably, the tertiary amine catalyst includes triethylamine;

[0045] Preferably, the manniene base catalyst includes DMP-30.

[0046] Preferably, in step S1, the catalyst is added in the form of an alcohol solution, wherein the mass concentration of the catalyst in the alcohol solution is 0.25%-50%;

[0047] Preferably, in step S1, the alcohol is a monohydric alcohol and / or a dihydric alcohol;

[0048] Preferably, the monohydric alcohol comprises any one or at least two combinations of ethanol, 1-propanol, 2-propanol, 1-butanol, 2-methyl-1-propanol, 2-butanol, 1-pentanol, 3-methyl-1-butanol, 2-methyl-1-butanol, 2,2-dimethyl-1-propanol, 2-pentanol, 3-methyl-2-butanol, 3-pentanol, 2-methyl-2-butanol, 1-hexanol, 2-hexanol, 3-hexanol, 3-methyl-2-pentanol, 4-methyl-2-pentanol, 2-methyl-3-pentanol, 1-heptanol, 2-heptanol, 3-heptanol, 4-heptanol, 1-octanol, isooctanol, 6-methyl-1-heptanol, and 2-ethylhexanol.

[0049] Preferably, the diol comprises any one or at least two combinations of ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, neopentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, diethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylenediol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, and 2-ethyl-1,3-hexanediol.

[0050] Preferably, in step S2, the terminator includes an organic acid and / or an acylation agent, preferably any one or at least a combination of two of formic acid, benzoic acid, benzoyl chloride, di-n-butyl phosphate or diisooctyl phosphate, and the amount of the terminator is 100%-150% of the molar amount of the catalyst.

[0051] Preferably, in step S2, the conversion rate is 20%-60%. Preferably, in step S3, the separation method includes thin-film evaporation, and the mass percentage of unreacted isocyanate monomers in the product after separation and removal is 1%-5%.

[0052] Preferably, in step S4, the acidic substance added to the isocyanate monomer is an organic acid or an acidic phosphate ester, including any one or at least two combinations of formic acid, acetic acid, propionic acid, butyric acid, monobutyl phosphate, di-n-butyl phosphate, and diisooctyl phosphate.

[0053] Preferably, in step S4, the amount of acidic substance added is 1%-5% of the mass of the isocyanate monomer.

[0054] Preferably, in step S5, the mass ratio of the separated product in S3 to the isocyanate monomer with added acidic substance in S4 is 10:(1-5), the reaction temperature is 60-100℃, and the reaction time is 30-60min.

[0055] Preferably, in step S6, the separation and removal method includes short-path evaporation, and the mass percentage of unreacted isocyanate monomers in the polyisocyanate composition obtained after separation and removal is ≤0.2%.

[0056] The beneficial effects of this invention are as follows:

[0057] By controlling the change rate of the three polymer molecules in the polyisocyanate composition to less than 10% after storage at 100°C for 24 hours, the high-temperature storage stability of the polyisocyanate can be effectively improved, achieving a viscosity increase rate of ≤10% after storage at 50°C for one month. Furthermore, the preparation process of the polyisocyanate composition provided by this invention is simple and easily industrialized. Detailed Implementation

[0058] The present invention will be further illustrated below with specific embodiments. These embodiments are merely illustrative and do not limit the scope of the invention.

[0059] <Main Raw Material Information>

[0060] HDI: Hexamethylene diisocyanate, Wanhua Chemical Co., Ltd.

[0061] PDI: Pentamethylene diisocyanate, Wanhua Chemical Co., Ltd.

[0062] N,N,N-Trimethylbenzylammonium hydroxide, Aladdin Reagent Platform

[0063] Isooctyl alcohol, Aladdin Reagent Platform

[0064] di-n-butyl phosphate, Aladdin Reagent Platform

[0065] <Determination of Product Viscosity>

[0066] The viscosity of the products in the examples and comparative examples was measured using a Brookfield RC / S rheometer with a CC-40 rotor, in a constant temperature water bath at 25 ± 0.1 °C. The shear rate was 25 s⁻¹. -1 ~250S -1 .

[0067] <Product viscosity growth rate>

[0068] The polyisocyanate composition was stored in a 50°C oven for one month under nitrogen protection, and viscosity tests were conducted before and after storage.

[0069] The viscosity growth rate of the polyisocyanate composition in this invention = (viscosity of the composition before storage - viscosity of the composition after storage) / viscosity of the composition before storage × 100%;

[0070] <Reaction Conversion Rate>

[0071] The reaction conversion rate refers to the mass ratio of diisocyanate that has been reacted and converted, based on the mass of the initial diisocyanate feedstock. The conversion rate is monitored by quantitative analysis of diisocyanate monomers using size exclusion liquid chromatography.

[0072] The size exclusion liquid chromatography instrument was an Agilent 1260, and the chromatographic columns were Pl1113-6520 and Pl113-6325 (Agilent); the mobile phase was tetrahydrofuran; the flow rate was 1.0 mL / min; the detection method was a differential detector; the sample concentration was 3 wt%; the analysis time was 40 min; and the column temperature was 35 °C.

[0073] <Change rate of three-molecule polymer content during high-temperature storage>

[0074] GPC was used to determine the content of the polyisocyanate composition. The mass fraction of the three polymer molecules in the polyisocyanate composition was determined by the area normalization method. Subsequently, 100 g of the polyisocyanate composition was weighed into a 150 mL glass bottle and protected with N2. The sample was placed in an oven at 100 °C and heated for 24 h. The mass fraction of the three polymer molecules in the heated product was also determined by GPC.

[0075] Change rate of terpolymer content = (mass fraction of terpolymer before heating - mass fraction of terpolymer after heating) / mass fraction of terpolymer before heating × 100%;

[0076] The liquid phase size exclusion chromatography polymer testing conditions used are as follows:

[0077] GPC equipment: Agilent 1260

[0078] GPC pillars: PL1113-6520 and PL113-6325 (Agilent)

[0079] Sample concentration: 3wt%

[0080] Mobile phase: Tetrahydrofuran

[0081] Detection method: Differential detector

[0082] Flow rate: 1 ml / min

[0083] Column temperature: 35℃

[0084] <Determination of Free Diisocyanate Monomer Content>

[0085] This invention is based on the method of GB / T18583-2008, and uses an Agilent GC-7890B gas chromatograph manufactured by Agilent to determine the content of residual monomers in the reaction system.

[0086] <Determination of the molar ratio of urea-formate group, iminooxadiazine dione group, urea-dione group and isocyanurate group>

[0087] In this invention, the molar ratio of iminooxadiazine dione groups, ureidone groups, and isocyanurate groups in the polyisocyanate composition is quantified by the composition. 13 The result is obtained through CNMR testing. The specific test conditions are as follows:

[0088] 13 C-NMR equipment: AVANCE 600 (Bruker); BBO probe (Bruker); Sample concentration: 30 wt%; Resonance frequency: 150 MHz; Shift reference: 77.0 ppm (CDCl3); Pulse program: zgig30; Spectral width: 240 ppm; Spectral center: 100 ppm

[0089] Isocyanurate group: integral value around 148.5 ppm / 3; Urea carbamate group: integral value around 154 ppm / 1; Iminooxadiazine dione group: integral value around 145.5 ppm / 1; Urea dione group: integral value around 157.5 ppm / 2.

[0090] The ratio of the total molar amount of urea diketone, urea carbamate, and iminooxadiazine diketone to the molar amount of isocyanurate is denoted as T, i.e., T = (urea carbamate + iminooxadiazine diketone + urea diketone) / isocyanurate.

[0091]

Example

[0092] Different polyisocyanate compositions were prepared according to the following methods and the distinguishing parameters in Table 1. The physical properties and evaluation data of the products are shown in Tables 1 and 2.

[0093] Step S1: Add 1500g of diisocyanate monomer to a 2L four-necked flask A, heat to 65℃ under nitrogen protection, add 3g of 5% N,N,N-trimethylbenzylammonium hydroxide isooctyl alcohol solution under stirring, and start timing, controlling the reaction temperature at 65-70℃.

[0094] Step S2: When the reaction reaches a certain conversion rate, add 0.24g of di-n-butyl phosphate to terminate the reaction and obtain reaction solution X.

[0095] Step S3: Remove unreacted monomers from the reaction solution X obtained in step S2 by thin-film evaporation to obtain a polyisocyanate composition Y with a free monomer content of 1%-5%.

[0096] Step S4: Add 20g of n-butyl phosphate to 1000g of diisocyanate monomer to obtain reaction solution Z.

[0097] Step S5: Mix Y obtained in step S3 with Z obtained in step S4 in a certain proportion, heat at 80°C for 45 minutes to react, and obtain reaction solution M.

[0098] Step S6: Separate the reaction solution M obtained in step S5 using a short-path evaporator to obtain the target polyisocyanate composition with a monomer content of less than 0.2%.

[0099] Table 1. Process parameters and physical property data of examples / comparative examples

[0100]

[0101] The present invention has been illustrated with the above embodiments to explain the detailed method of the present invention. However, the present invention is not limited to the detailed method described above, that is, it does not mean that the present invention must rely on the detailed method described above to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A polyisocyanate composition derived from aliphatic and / or cycloaliphatic diisocyanate monomers and containing isocyanurate structures, characterized in that, The trimer content of the polyisocyanate composition is less than 10% after the polyisocyanate composition is stored at 100℃ for 24h.

2. The polyisocyanate composition according to claim 1, characterized in that, The trimer content of the polyisocyanate composition is 30%-75%, preferably 45%-60%.

3. The polyisocyanate composition according to any of claims 1 to 2, characterized in that The aliphatic / alicyclic diisocyanate monomer is selected from one or more of tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, cyclohexane dimethylene diisocyanate, lysine diisocyanate.

4. The polyisocyanate composition according to any of claims 1 to 3, characterized in that The polyisocyanate composition further comprises any one or a combination of at least two of uretdione groups, allophanate groups, iminooxadiazinedione groups; Preferably, the total molar amount of uretdione groups, allophanate groups, iminooxadiazinedione groups in the polyisocyanate composition is 1%-10% relative to the molar amount of isocyanurate groups.

5. The polyisocyanate composition according to any of claims 1 to 4, characterized in that The viscosity is 1000-4000mPa·s when measured at 25℃; Preferably, the viscosity growth rate of the polyisocyanate composition is ≤10% after the polyisocyanate composition is stored at 50℃ for 1 month.

6. A process for the preparation of the polyisocyanate composition according to any one of claims 1 to 5, characterized in that The preparation method comprises the following steps: S1: polymerizing the isocyanate monomer in the presence of a catalyst; S2: adding a terminating agent to terminate the reaction to obtain a product with a target conversion rate; S3: separating and removing the isocyanate monomer that does not participate in the reaction from the product of step S2; S4: adding a certain amount of an acidic substance to the isocyanate monomer; S5: mixing the product separated in step S3 with the isocyanate monomer to which the acidic substance is added in step S4, and reacting; S6: separating and removing the unreacted isocyanate monomer from the product of step S5 to obtain the polyisocyanate composition.

7. The production method according to claim 6, wherein In step S1, the catalyst comprises any one or a combination of at least two of quaternary ammonium catalysts, silazane catalysts, alkyl phosphine catalysts, tertiary amine catalysts, or mannich base catalysts; Preferably, the amount of catalyst is 10-1000ppm relative to the total amount of isocyanate; Preferably, the catalyst is added in the form of an alcohol solution, the mass concentration of the catalyst in the alcohol solution is 0.25%-50%, and the type of alcohol is monohydric alcohol and / or dihydric alcohol; Preferably, the polymerization reaction temperature is 30-120℃, preferably 40-100℃.

8. The preparation method according to claim 6, characterized in that, In step S2, the terminating agent comprises any one or a combination of at least two of organic acids and / or acylating agents, preferably formic acid, benzoic acid, benzoyl chloride, di-n-butyl phosphate, or diisooctyl phosphate, and the amount of the terminating agent is 100%-150% of the molar amount of the catalyst; Preferably, in step S2, the conversion rate is 20%-60%; Preferably, in step S3, the mass fraction of the isocyanate monomer that does not participate in the reaction in the product after separation and removal is 1%-5%.

9. The preparation method according to claim 6, characterized in that, In step S4, the acidic substance added to the isocyanate monomer is an organic acid or an acidic phosphate ester, and the amount of addition is 1%-5%.

10. The method of claim 6, wherein, In step S5, the mass ratio of the separated product in S3 to the isocyanate monomer with added acidic substance in S4 is 10:(1-5), the reaction temperature is 60-100℃, and the time is 30-60min. Preferably, in the polyisocyanate composition obtained after separation and removal in step S6, the mass percentage of unreacted isocyanate monomers is ≤0.2%.

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