CN116284642B - Yellowing-resistant isocyanate composition and preparation method thereof - Google Patents

Yellowing-resistant isocyanate composition and preparation method thereof Download PDF

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CN116284642B
CN116284642B CN202310558770.7A CN202310558770A CN116284642B CN 116284642 B CN116284642 B CN 116284642B CN 202310558770 A CN202310558770 A CN 202310558770A CN 116284642 B CN116284642 B CN 116284642B
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reaction
isocyanate composition
stirring
yellowing
titanium dioxide
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CN116284642A (en
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武淑勇
薛斌
杜光涛
韩兵
吴孟
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Plain Bester Chemical Co ltd
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    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08GMACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00Polymeric products of isocyanates or isothiocyanates
    • C08G18/06Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/30Low-molecular-weight compounds
    • C08G18/38Low-molecular-weight compounds having heteroatoms other than oxygen
    • C08G18/3855Low-molecular-weight compounds having heteroatoms other than oxygen having sulfur
    • C08G18/3863Low-molecular-weight compounds having heteroatoms other than oxygen having sulfur containing groups having sulfur atoms between two carbon atoms, the sulfur atoms being directly linked to carbon atoms or other sulfur atoms
    • C08G18/3865Low-molecular-weight compounds having heteroatoms other than oxygen having sulfur containing groups having sulfur atoms between two carbon atoms, the sulfur atoms being directly linked to carbon atoms or other sulfur atoms containing groups having one sulfur atom between two carbon atoms
    • C08G18/3868Low-molecular-weight compounds having heteroatoms other than oxygen having sulfur containing groups having sulfur atoms between two carbon atoms, the sulfur atoms being directly linked to carbon atoms or other sulfur atoms containing groups having one sulfur atom between two carbon atoms the sulfur atom belonging to a sulfide group
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    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08GMACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00Polymeric products of isocyanates or isothiocyanates
    • C08G18/06Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/30Low-molecular-weight compounds
    • C08G18/32Polyhydroxy compounds; Polyamines; Hydroxyamines
    • C08G18/3203Polyhydroxy compounds
    • C08G18/3206Polyhydroxy compounds aliphatic
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    • C08KUse of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00Use of inorganic substances as compounding ingredients
    • C08K3/18Oxygen-containing compounds, e.g. metal carbonyls
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    • C08KUse of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K9/00Use of pretreated ingredients
    • C08K9/04Ingredients treated with organic substances
    • C08K9/06Ingredients treated with organic substances with silicon-containing compounds
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    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08KUse of inorganic or non-macromolecular organic substances as compounding ingredients
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    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08KUse of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00Use of inorganic substances as compounding ingredients
    • C08K3/18Oxygen-containing compounds, e.g. metal carbonyls
    • C08K3/20Oxides; Hydroxides
    • C08K3/22Oxides; Hydroxides of metals
    • C08K2003/2237Oxides; Hydroxides of metals of titanium
    • C08K2003/2241Titanium dioxide
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    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
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    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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    • Y02E10/50Photovoltaic [PV] energy

Abstract

The invention relates to the technical field of isocyanate composition preparation, and discloses a yellowing-resistant isocyanate composition and a preparation method thereof. The preparation method comprises the following steps: 3, 5-di-tert-butyl-4-hydroxybenzaldehyde and ethanolamine are used for reaction to prepare 2, 6-di-tert-butyl-4-hydroxyethylaminomethyl phenol; preparing modified hindered phenol by reacting 2, 6-di-tert-butyl-4-hydroxyethylamino methyl phenol with dimethyl thiodipropionate; mixing modified hindered phenol, surface modified silicon dioxide coated nano titanium dioxide and isocyanate composition for reaction to prepare grafted modified isocyanate; the grafting modified isocyanate, the micromolecular monohydric alcohol, the micromolecular polyol, the acid compound and the isocyanate composition are mixed to obtain the yellowing-resistant isocyanate composition. The isocyanate composition prepared by the invention has good yellowing resistance and storage stability, can effectively inhibit yellowing and self-polymerization of the isocyanate composition, and can be used for synthesizing polyurethane materials with various required appearance qualities.

Description

Yellowing-resistant isocyanate composition and preparation method thereof
Technical Field
The invention relates to the technical field of isocyanate composition preparation, in particular to a yellowing-resistant isocyanate composition and a preparation method thereof.
Background
Isocyanates are a class of compounds having high reactivity, which are the main raw materials for the synthesis of polyurethane materials, and have highly unsaturated isocyanate groups in their molecular structures, which tend to yellow and self-polymerize during storage, and therefore stabilizers are often added to isocyanate compositions to inhibit their yellowing and self-polymerization.
Chinese patent CN109627422B discloses a preparation method of butanone oxime blocked polyisocyanate, wherein butanone oxime reacts with isocyanate groups of isocyanate to protect isocyanate groups, so as to inhibit yellowing of isocyanate, but the method is suitable for aliphatic polyisocyanate, has poor effect on aromatic polyisocyanate, and if the viscosity of the product is high in the preparation process, a solvent is needed to be added to regulate the viscosity of the product, on the other hand, the isocyanate groups in the product react with butanone oxime, the free isocyanate groups have less content, and the isocyanate content capable of participating in the reaction in the product is less. Chinese patent CN115073323a discloses an isocyanate stabilizer, which is obtained by compounding an acidic compound, an antioxidant and a sulfonamide compound, and has a simple preparation method, but needs to be used in an inert gas atmosphere, and the range of applicable isocyanate types is small.
Disclosure of Invention
In order to solve the problems, the invention provides a preparation method of a yellowing-resistant isocyanate polymer, which can effectively inhibit the yellowing and self-polymerization of an isocyanate composition.
In order to achieve the above object, the present invention provides a method for preparing a yellowing-resistant isocyanate composition, comprising the steps of:
uniformly mixing ethanol, 3, 5-di-tert-butyl-4-hydroxybenzaldehyde and ethanolamine, stirring, heating for reaction, heating, continuing the reaction, cooling after the reaction, adding sodium borohydride, reacting at a low temperature, and purifying after the reaction to obtain the 2, 6-di-tert-butyl-4-hydroxyethylaminomethyl phenol;
step (2) uniformly mixing dimethyl thiodipropionate and 2, 6-di-tert-butyl-4-hydroxyethylamino methyl phenol, adding dibutyltin dilaurate, stirring and heating in an inert gas atmosphere for reaction, and performing rotary evaporation to obtain modified hindered phenol;
uniformly mixing the isocyanate composition, the modified hindered phenol and the surface modified silicon dioxide coated nano titanium dioxide according to the mass ratio of (400-600) (250-300) (100-150), and stirring for reaction to obtain grafted modified isocyanate;
and (4) uniformly mixing the grafting modified isocyanate, the micromolecular monohydric alcohol, the micromolecular polyhydric alcohol, the acid compound and the isocyanate composition prepared in the step (3) according to the mass ratio of (3-13) (1-4) (4-14) (10000) to obtain the yellowing-resistant isocyanate composition.
Preferably, in the step (1): the mass ratio of the ethanol to the 3, 5-di-tert-butyl-4-hydroxybenzaldehyde to the ethanolamine to the sodium borohydride is (80-100), 21-25, 6-8 and 2.5-3.5; stirring and heating reaction conditions are that the stirring speed is 150r/min, and the reaction is carried out for 1-1.5h at the temperature of 55-60 ℃; the reaction is continued for 3.5 to 4.5 hours at the temperature of 75 to 85 ℃; the reaction condition of low temperature is that the reaction is carried out for 0.5 to 1 hour at the temperature of-5 to 0 ℃.
Preferably, the purification specifically comprises the steps of adjusting the pH value to 1-2 by using a hydrochloric acid aqueous solution, removing ethanol by rotary evaporation, adjusting the pH value to 8-9 by using a sodium hydroxide aqueous solution, extracting by using dichloromethane, drying by using anhydrous magnesium sulfate, filtering to remove the anhydrous magnesium sulfate, and performing column chromatography separation by using petroleum ether and ethyl acetate with the volume ratio of 5:1 as mobile phases after removing the dichloromethane by rotary evaporation of filtrate.
Preferably, the aqueous hydrochloric acid solution comprises 5% by weight aqueous hydrochloric acid; the aqueous sodium hydroxide solution comprises 10% by weight aqueous sodium hydroxide solution.
Preferably, in the step (2): the mass ratio of the dimethyl thiodipropionate to the 2, 6-di-tert-butyl-4-hydroxyethylamino methyl phenol to the dibutyltin dilaurate is (200-220): (560-620): (5-10); the condition of stirring and heating reaction is that the reaction is carried out for 3-5h at the temperature of 130-150 ℃ under the stirring speed of 180 r/min.
Preferably, the inert gas comprises nitrogen.
Preferably, in the step (3): the condition of stirring reaction is that the stirring speed is 180r/min, and the reaction is carried out for 1-1.5h at the temperature of 5-25 ℃.
Preferably, in the step (3): the isocyanate composition comprises a mixture of at least 2 of diphenylmethane diisocyanate, toluene diisocyanate, 1, 6-hexamethylene diisocyanate, isophorone diisocyanate, and isophthalene diisocyanate.
Preferably, in the step (3): the surface modified silicon dioxide coated nano titanium dioxide is prepared by the following steps:
uniformly mixing nano titanium dioxide with deionized water, adding sodium hexametaphosphate as a dispersing agent, performing ultrasonic dispersion, stirring and heating, dropwise adding a sodium silicate aqueous solution, dropwise adding a hydrochloric acid aqueous solution while dropwise adding the sodium silicate aqueous solution to enable the pH value of a reaction system to be 8-10, aging, purifying, and drying to obtain the silicon dioxide coated nano titanium dioxide;
uniformly mixing the silicon dioxide coated nano titanium dioxide with toluene, performing ultrasonic dispersion, adding a silane coupling agent, stirring, heating, reacting, curing, purifying and drying to obtain the surface modified silicon dioxide coated nano titanium dioxide;
Preferably, when preparing the silica coated nano titania: the mass ratio of the nano titanium dioxide, deionized water, sodium hexametaphosphate and sodium silicate aqueous solution is (20-60) 2000 (1-3) 100-500; ultrasonic dispersion is carried out for 20-40min under the frequency of 20-40 kHz; stirring and heating at a speed of 300r/min and a temperature of 80-90 ℃; the aqueous sodium silicate solution comprises 40% by weight of aqueous sodium silicate solution; when preparing the silicon dioxide coated nano titanium dioxide: the mass ratio of the nano titanium dioxide, deionized water, sodium hexametaphosphate and sodium silicate aqueous solution is (20-60) 2000 (1-3) 100-500; ultrasonic dispersion is carried out for 20-40min under the frequency of 20-40 kHz; stirring and heating at a speed of 300r/min and a temperature of 80-90 ℃; the aqueous sodium silicate solution comprises 40% by weight of aqueous sodium silicate solution; the dripping time of the sodium silicate aqueous solution is 30-90min; the aqueous hydrochloric acid solution comprises 1% by weight of aqueous hydrochloric acid solution; the aging condition is that the pH value is 8-10 and the aging is 4-5 hours at the temperature of 80-90 ℃.
Preferably, the purification comprises suction filtration, washing.
Preferably, when preparing the surface modified silica coated nano titania: the mass ratio of the silicon dioxide coated nano titanium dioxide to the toluene to the silane coupling agent is (15-35): 600-1000): 5-25; the silane coupling agent comprises a 3-aminopropyl triethoxy silane coupling agent; ultrasonic dispersion is carried out for 20-40min under the frequency of 20-40kHz, and the condition of stirring and heating reaction is that the reaction is carried out for 3-4h under the stirring speed of 300r/min and the temperature of 75-85 ℃.
Preferably, the purification comprises suction filtration, washing.
Preferably, in the step (4): the small molecular monohydric alcohol comprises at least one of methanol and ethanol; the small molecular polyalcohol comprises at least one of glycol and glycerol; the acidic compound comprises at least one of perchloric acid and trifluoromethanesulfonic acid; the isocyanate composition comprises a mixture of at least 2 of diphenylmethane diisocyanate, toluene diisocyanate, 1, 6-hexamethylene diisocyanate, isophorone diisocyanate, and isophthalene diisocyanate.
The invention provides a yellowing-resistant isocyanate composition prepared by adopting the preparation method of the yellowing-resistant isocyanate composition.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention selects nano titanium dioxide as an ultraviolet absorber, reduces the photocatalysis effect of the titanium dioxide by coating the silicon dioxide on the surface of the titanium dioxide, modifies the coated surface by using a silane coupling agent to increase the compatibility of the titanium dioxide in isocyanate compositions, and simultaneously the modified titanium dioxide can be chemically bonded into a polymer system synthesized by subsequent isocyanate to continuously act as the ultraviolet absorber.
2. According to the invention, the hindered phenol compound is selected as the main antioxidant, so that the color problem of most hindered amine main antioxidants is avoided, and the hindered phenol compound is connected with the dimethyl thiodipropionate through the transesterification, so that on one hand, the synergistic effect of the hindered phenol compound and the thioester compound exists, the antioxidation effect is improved, and on the other hand, secondary amino groups exist in the molecule and can react with isocyanate groups to be connected into an isocyanate composition system, and the compatibility of the antioxidants is improved.
3. Titanium dioxide is an inorganic ultraviolet absorbent, can form good synergistic effect with a hindered phenol antioxidant, has relatively weak inhibition effect on photoaging compared with a hindered amine oxidant, and most of organic ultraviolet absorbers contain proper chromophores of a conjugated pi electron system, so that the ultraviolet shielding performance can be reduced and yellowing can occur after long-term use, and titanium dioxide and the hindered phenol antioxidant are selected for use in a compounding way.
Drawings
FIG. 1 is a process flow for preparing the yellowing resistant isocyanate composition of the present invention;
FIG. 2 is a schematic representation of the synthesis of 2, 6-di-tert-butyl-4-hydroxyethylaminomethyl phenol according to the present invention;
FIG. 3 is a schematic representation of the synthesis of a modified hindered phenol of the present invention;
FIG. 4 is a schematic representation of the synthesis of a graft modified isocyanate in accordance with the present invention;
FIG. 5 is a bar graph showing the results of the yellowing resistance test for the yellowing resistant isocyanate compositions of examples 1 to 5 and comparative examples 1 to 3 of the present invention;
FIG. 6 is a bar graph showing the results of storage stability tests of yellowing resistant isocyanate compositions of examples 1 to 5 and comparative examples 1 to 3 of the present invention.
Detailed Description
Example 1 this example discloses a process for the preparation of a yellowing-resistant isocyanate composition comprising the steps of:
uniformly mixing nano titanium dioxide, deionized water and sodium hexametaphosphate, performing ultrasonic dispersion for 40min under the condition of 20kHz, stirring and heating to 80 ℃ at the stirring speed of 300r/min, dropwise adding 40% wt sodium silicate aqueous solution, dropwise adding 1% wt hydrochloric acid aqueous solution while dropwise adding sodium silicate aqueous solution to enable the pH value of a reaction system to be 8, aging for 5h under the condition of keeping the temperature to be 80 ℃ and the pH value to be 8, cooling, performing suction filtration, washing with distilled water, and drying for 5h under the condition of 120 ℃ to obtain the silicon dioxide coated nano titanium dioxide;
wherein the mass ratio of the nano titanium dioxide to the deionized water to the sodium hexametaphosphate to the 40%wt sodium silicate aqueous solution is 20:2000:1:100;
Uniformly mixing the silicon dioxide coated nano titanium dioxide and toluene, performing ultrasonic dispersion for 40min under the condition of 20kHz, adding a 3-aminopropyl triethoxy silane coupling agent, stirring and heating to 75 ℃ at the stirring speed of 300r/min, keeping the temperature at 75 ℃ for reaction for 4h, standing and curing for 12h at room temperature after the reaction, performing suction filtration, washing with ethanol, and drying for 4h at the temperature of 110 ℃ to obtain the surface modified silicon dioxide coated nano titanium dioxide;
wherein, the mass ratio of the silicon dioxide coated nano titanium dioxide to the toluene to the 3-aminopropyl triethoxy silane coupling agent is 15:600:5;
uniformly mixing ethanol, 3, 5-di-tert-butyl-4-hydroxybenzaldehyde and ethanolamine, stirring and heating to 55 ℃ at a stirring speed of 150r/min, keeping the temperature at 55 ℃ for reacting for 1.5 hours, heating to 75 ℃, keeping the temperature at 75 ℃ for reacting for 4.5 hours, cooling to-5 ℃ at a speed of 5 ℃/min after the reaction, adding sodium borohydride in five times on average, keeping the temperature at-5 ℃ for reacting for 1 hour, adjusting the pH value to 2 by using 5% wt of aqueous hydrochloric acid solution, removing ethanol by rotary evaporation, adjusting the pH value to 9 by using 10% wt of aqueous sodium hydroxide solution, extracting for 3 times by using dichloromethane, drying by using anhydrous magnesium sulfate, filtering to remove anhydrous magnesium sulfate, and performing column chromatographic separation by using petroleum ether and ethyl acetate with a volume ratio of 5:1 as mobile phases after the filtrate is rotary evaporated to obtain 2, 6-di-tert-butyl-4-hydroxyethylaminomethyl phenol;
Wherein the mass ratio of the ethanol to the 3, 5-di-tert-butyl-4-hydroxybenzaldehyde to the ethanol to the sodium borohydride is 80:21:6:2.5;
uniformly mixing dimethyl thiodipropionate, 2, 6-di-tert-butyl-4-hydroxyethylamino methyl phenol and dibutyltin dilaurate according to the mass ratio of 200:560:5, stirring and heating to 130 ℃ in a nitrogen atmosphere at the stirring speed of 180r/min, keeping the temperature at 130 ℃ for reaction for 5 hours, and removing methanol by rotary evaporation after the reaction to obtain modified hindered phenol;
uniformly mixing the isocyanate composition, the modified hindered phenol and the surface modified silicon dioxide coated nano titanium dioxide according to the mass ratio of 400:250:100, and stirring at the temperature of 5 ℃ and the stirring speed of 180r/min for reacting for 1.5 hours to obtain grafted modified isocyanate;
wherein the isocyanate composition is a mixture of diphenylmethane diisocyanate and 1, 6-hexamethylene diisocyanate, and the mass ratio of the diphenylmethane diisocyanate to the 1:1;
step (6), uniformly mixing the grafting modified isocyanate, the micromolecular monohydric alcohol, the micromolecular polyhydric alcohol, the acid compound and the isocyanate composition prepared in the step (5) according to the mass ratio of 3:1:1:4:10000 to obtain a yellowing-resistant isocyanate composition;
Wherein the micromolecular monohydric alcohol is methanol, the micromolecular polyhydric alcohol is glycerol, the acid compound is perchloric acid, the isocyanate composition is a mixture of diphenylmethane diisocyanate and 1, 6-hexamethylene diisocyanate, and the mass ratio of the two is 1:1.
Example 2 this example discloses a process for the preparation of a yellowing-resistant isocyanate composition comprising the steps of:
uniformly mixing nano titanium dioxide, deionized water and sodium hexametaphosphate, performing ultrasonic dispersion for 20min under the condition of 40kHz, stirring and heating to 90 ℃ at the stirring speed of 300r/min, dropwise adding 40%wt sodium silicate aqueous solution, dropwise adding 1%wt hydrochloric acid aqueous solution while dropwise adding sodium silicate aqueous solution to enable the pH value of a reaction system to be 10 after the dropwise adding is completed within 30min, aging for 4h under the condition that the temperature is 90 ℃ and the pH value is 10, cooling, performing suction filtration, washing with distilled water, and drying for 4.5h under the condition of 125 ℃ to obtain the silicon dioxide coated nano titanium dioxide;
wherein the mass ratio of the nano titanium dioxide to the deionized water to the sodium hexametaphosphate to the 40%wt sodium silicate aqueous solution is 30:2000:1.5:100;
uniformly mixing the silicon dioxide coated nano titanium dioxide and toluene, performing ultrasonic dispersion for 20min at 40kHz, adding a 3-aminopropyl triethoxy silane coupling agent, stirring and heating to 85 ℃ at a stirring speed of 300r/min, keeping the temperature at 85 ℃ for reaction for 3h, standing and curing for 12h at room temperature after the reaction, performing suction filtration, washing with ethanol, and drying for 3.5h at 115 ℃ to obtain the surface modified silicon dioxide coated nano titanium dioxide;
Wherein, the mass ratio of the silicon dioxide coated nano titanium dioxide to the toluene to the 3-aminopropyl triethoxy silane coupling agent is 20:700:10;
uniformly mixing ethanol, 3, 5-di-tert-butyl-4-hydroxybenzaldehyde and ethanolamine, stirring and heating to 60 ℃ at a stirring speed of 150r/min, keeping the temperature at 60 ℃ for reaction for 1h, heating to 85 ℃, keeping the temperature at 85 ℃ for reaction for 3.5h, cooling to 0 ℃ at a speed of 5 ℃/min after reaction, adding sodium borohydride in five times on average, keeping the temperature at 0 ℃ for reaction for 0.5h, adjusting the pH value to 1 by using 5% wt of aqueous hydrochloric acid solution, removing ethanol by rotary evaporation, adjusting the pH value to 8 by using 10% wt of aqueous sodium hydroxide solution, extracting 3 times by using dichloromethane, drying with anhydrous magnesium sulfate by using the mass of the dichloromethane for each extraction, filtering to remove the anhydrous magnesium sulfate, and performing column chromatography separation by using petroleum ether and ethyl acetate with a volume ratio of 5:1 as mobile phases after the dichloromethane is removed by rotary evaporation of filtrate to obtain 2, 6-di-tert-butyl-4-hydroxyethylaminomethyl phenol;
wherein the mass ratio of the ethanol to the 3, 5-di-tert-butyl-4-hydroxybenzaldehyde to the ethanol to the sodium borohydride is 85:22:6.5:2.8;
uniformly mixing dimethyl thiodipropionate, 2, 6-di-tert-butyl-4-hydroxyethylamino methyl phenol and dibutyltin dilaurate according to the mass ratio of 205:575:6, stirring and heating to 135 ℃ in a nitrogen atmosphere at the stirring speed of 180r/min, keeping the temperature at 135 ℃ for reaction for 4.5 hours, and removing methanol by rotary evaporation after the reaction to obtain modified hindered phenol;
Uniformly mixing the isocyanate composition, the modified hindered phenol and the surface modified silicon dioxide coated nano titanium dioxide according to the mass ratio of 450:270:120, and stirring at the temperature of 10 ℃ and the stirring speed of 180r/min for reacting for 1.4 hours to obtain grafted modified isocyanate;
wherein the isocyanate composition is a mixture of diphenylmethane diisocyanate, toluene diisocyanate and 1, 6-hexamethylene diisocyanate, and the mass ratio of the diphenylmethane diisocyanate to the toluene diisocyanate to the 1:1:2;
step (6), uniformly mixing the grafting modified isocyanate, the micromolecular monohydric alcohol, the micromolecular polyhydric alcohol, the acid compound and the isocyanate composition prepared in the step (5) according to the mass ratio of 6:1:1:6:10000 to obtain the yellowing-resistant isocyanate composition;
wherein the micromolecular monohydric alcohol is methanol, the micromolecular polyhydric alcohol is glycerol, the acid compound is perchloric acid, the isocyanate composition is a mixture of diphenylmethane diisocyanate, toluene diisocyanate and 1, 6-hexamethylene diisocyanate, and the mass ratio of the three is 1:1:2.
Example 3 this example discloses a process for the preparation of a yellowing-resistant isocyanate composition comprising the steps of:
uniformly mixing nano titanium dioxide, deionized water and sodium hexametaphosphate, performing ultrasonic dispersion for 30min under the condition of 30kHz, stirring and heating to 85 ℃ at the stirring speed of 300r/min, dropwise adding 40% wt sodium silicate aqueous solution, dropwise adding 1% wt hydrochloric acid aqueous solution while dropwise adding sodium silicate aqueous solution to enable the pH value of a reaction system to be 9 after the dropwise adding is completed within 60min, aging for 4.5h under the condition that the temperature is 85 ℃ and the pH value is 9, cooling, performing suction filtration, washing with distilled water, and drying for 4h under the condition of 130 ℃ to obtain the silicon dioxide coated nano titanium dioxide;
Wherein the mass ratio of the nano titanium dioxide to the deionized water to the sodium hexametaphosphate to the 40%wt sodium silicate aqueous solution is 40:2000:1:300;
uniformly mixing the silicon dioxide coated nano titanium dioxide and toluene, performing ultrasonic dispersion for 30min under the condition of 30kHz, adding a 3-aminopropyl triethoxy silane coupling agent, stirring and heating to 80 ℃ at the stirring speed of 300r/min, keeping the temperature at 80 ℃ for reaction for 3.5h, standing and curing for 12h at room temperature after the reaction, performing suction filtration, washing with ethanol, and drying for 3h under the condition of 115 ℃ to obtain the surface modified silicon dioxide coated nano titanium dioxide;
wherein, the mass ratio of the silicon dioxide coated nano titanium dioxide to the toluene to the 3-aminopropyl triethoxy silane coupling agent silicon dioxide coated nano titanium dioxide to the 3-aminopropyl triethoxy silane coupling agent is 25:800:15;
uniformly mixing ethanol, 3, 5-di-tert-butyl-4-hydroxybenzaldehyde and ethanolamine, stirring and heating to 58 ℃ at a stirring speed of 150r/min, keeping the temperature at 58 ℃ for reaction for 1.2 hours, heating to 80 ℃, keeping the temperature at 80 ℃ for reaction for 4 hours, cooling to-3 ℃ at a speed of 5 ℃/min after reaction, adding sodium borohydride in five times on average, keeping the temperature at-3 ℃ for reaction for 0.7 hour, adjusting the pH value to 1.5 by using 5% wt hydrochloric acid aqueous solution after reaction, removing ethanol by rotary evaporation, adjusting the pH value to 8.5 by using 10% wt sodium hydroxide aqueous solution, extracting for 3 times by using dichloromethane, wherein the mass of dichloromethane for each extraction is 60% of the mass of ethanol, drying by using anhydrous magnesium sulfate, filtering to remove anhydrous magnesium sulfate, and performing column chromatography separation by using petroleum ether and ethyl acetate with a volume ratio of 5:1 as mobile phases after filtering to remove the dichloromethane, thereby obtaining 2, 6-di-tert-butyl-4-hydroxyethylaminomethyl phenol;
Wherein the mass ratio of the ethanol to the 3, 5-di-tert-butyl-4-hydroxybenzaldehyde to the ethanol to the sodium borohydride is 90:23:7:3;
uniformly mixing dimethyl thiodipropionate, 2, 6-di-tert-butyl-4-hydroxyethylamino methyl phenol and dibutyltin dilaurate according to the mass ratio of 210:590:7, stirring and heating to 140 ℃ at the stirring speed of 180r/min in a nitrogen atmosphere, keeping the temperature at 140 ℃ for reaction for 4 hours, and removing methanol by rotary evaporation after the reaction to obtain modified hindered phenol;
uniformly mixing the isocyanate composition, the modified hindered phenol and the surface modified silicon dioxide coated nano titanium dioxide according to the mass ratio of 500:280:130, and stirring at 15 ℃ and a stirring speed of 180r/min for reaction for 1.3 hours to obtain grafted modified isocyanate;
wherein the isocyanate composition is a mixture of diphenylmethane diisocyanate, toluene diisocyanate and 1, 6-hexamethylene diisocyanate, and the mass ratio of the diphenylmethane diisocyanate to the toluene diisocyanate to the 1:1:2;
step (6) uniformly mixing the grafting modified isocyanate, the micromolecular monohydric alcohol, the micromolecular polyhydric alcohol, the acid compound and the isocyanate composition prepared in the step (5) according to the mass ratio of 8:2:2:9:10000, and sealing and preserving to obtain the yellowing-resistant isocyanate composition;
The small molecular monohydric alcohol is a mixture of methanol and ethanol, the mass ratio of the small molecular monohydric alcohol to the mixture of glycol and glycerol is 1:1, the mass ratio of the small molecular polyhydric alcohol to the mixture of glycol and glycerol is 1:1, the acidic compound is trifluoromethanesulfonic acid, the isocyanate composition is a mixture of diphenylmethane diisocyanate, toluene diisocyanate and 1, 6-hexamethylene diisocyanate, and the mass ratio of the three is 1:1:2.
Example 4 this example discloses a process for the preparation of a yellowing-resistant isocyanate composition comprising the steps of:
uniformly mixing nano titanium dioxide, deionized water and sodium hexametaphosphate, performing ultrasonic dispersion for 30min under the condition of 30kHz, stirring and heating to 85 ℃ at the stirring speed of 300r/min, dropwise adding 40% wt sodium silicate aqueous solution at the same time, dropwise adding 1% wt hydrochloric acid aqueous solution at the same time when the dropwise adding of the sodium silicate aqueous solution is completed within 90min, enabling the pH value of a reaction system to be 9, aging for 4.5h under the condition that the temperature is 85 ℃ and the pH value is 9, cooling, performing suction filtration, washing with distilled water, and drying for 3.5h under the condition of 135 ℃ to obtain the silicon dioxide coated nano titanium dioxide;
wherein the mass ratio of the nano titanium dioxide to the deionized water to the sodium hexametaphosphate to the 40%wt sodium silicate aqueous solution is 50:2000:1:400;
Uniformly mixing the silicon dioxide coated nano titanium dioxide and toluene, performing ultrasonic dispersion for 30min under the condition of 30kHz, adding a 3-aminopropyl triethoxy silane coupling agent, stirring and heating to 85 ℃ at the stirring speed of 300r/min, keeping the temperature at 85 ℃ for reaction for 3.5h, standing and curing for 12h at room temperature after the reaction, performing suction filtration, washing with ethanol, and drying for 2.5h under the condition of 115 ℃ to obtain the surface modified silicon dioxide coated nano titanium dioxide;
wherein, the mass ratio of the silicon dioxide coated nano titanium dioxide to the toluene to the 3-aminopropyl triethoxy silane coupling agent is 30:900:20;
uniformly mixing ethanol, 3, 5-di-tert-butyl-4-hydroxybenzaldehyde and ethanolamine, stirring and heating to 59 ℃ at a stirring speed of 150r/min, keeping the temperature at 59 ℃ for reaction for 1.2 hours, heating to 82 ℃ and keeping the temperature at 82 ℃ for reaction for 4.2 hours, cooling to-3 ℃ at a speed of 5 ℃/min after the reaction, adding sodium borohydride in five times on average, keeping the temperature at-3 ℃ for reaction for 0.6 hours, regulating the pH value to 1.5 by using 5% wt of hydrochloric acid aqueous solution, removing ethanol by rotary evaporation, regulating the pH value to 8.5 by using 10% wt of sodium hydroxide aqueous solution, extracting 3 times by using dichloromethane, wherein the mass of dichloromethane for each extraction is 60% of the mass of ethanol, drying by using anhydrous magnesium sulfate, filtering to remove anhydrous magnesium sulfate, performing column chromatography separation by using petroleum ether and ethyl acetate with a volume ratio of 5:1 as mobile phases after the filtrate is subjected to rotary evaporation to obtain 2, 6-di-tert-butyl-4-hydroxyethylaminomethyl phenol;
Wherein the mass ratio of the ethanol to the 3, 5-di-tert-butyl-4-hydroxybenzaldehyde to the ethanol to the sodium borohydride is 95:24:7.5:3.2;
uniformly mixing dimethyl thiodipropionate, 2, 6-di-tert-butyl-4-hydroxyethylamino methyl phenol and dibutyltin dilaurate according to the mass ratio of 215:605:9, stirring and heating to 145 ℃ at the stirring speed of 180r/min in a nitrogen atmosphere, keeping the temperature at 145 ℃ for reaction for 3.5 hours, and removing methanol by rotary evaporation after the reaction to obtain modified hindered phenol;
uniformly mixing the isocyanate composition, the modified hindered phenol and the surface modified silicon dioxide coated nano titanium dioxide according to the mass ratio of 550:290:140, and stirring at 20 ℃ and a stirring speed of 180r/min for reacting for 1.2 hours to obtain grafted modified isocyanate;
wherein the isocyanate composition is a mixture of diphenylmethane diisocyanate, toluene diisocyanate, 1, 6-hexamethylene diisocyanate and isophorone and isocyanate, and the mass ratio of the four is 1:1:1:1;
step (6), uniformly mixing the grafting modified isocyanate, the micromolecular monohydric alcohol, the micromolecular polyhydric alcohol, the acid compound and the isocyanate composition prepared in the step (5) according to the mass ratio of 11:3:3:11:10000 to obtain a yellowing-resistant isocyanate composition;
The small molecular monohydric alcohol is a mixture of methanol and ethanol, the mass ratio of the small molecular monohydric alcohol to the mixture of glycol and glycerol is 1:2, the mass ratio of the small molecular polyhydric alcohol to the mixture of glycol and glycerol is 1:2, the acidic compound is trifluoromethanesulfonic acid, the isocyanate composition is a mixture of diphenylmethane diisocyanate, toluene diisocyanate, 1, 6-hexamethylene diisocyanate and isophorone diisocyanate, and the mass ratio of the four is 1:1:1:1.
Example 5 this example discloses a process for the preparation of a yellowing-resistant isocyanate composition comprising the steps of:
uniformly mixing nano titanium dioxide, deionized water and sodium hexametaphosphate, performing ultrasonic dispersion for 30min under the condition of 30kHz, stirring and heating to 85 ℃ at the stirring speed of 300r/min, dropwise adding 40% wt sodium silicate aqueous solution at the same time, dropwise adding 1% wt hydrochloric acid aqueous solution at the same time when the dropwise adding of the sodium silicate aqueous solution is completed within 90min, enabling the pH value of a reaction system to be 9, aging for 4.5h under the condition that the temperature is 85 ℃ and the pH value is 9, cooling, performing suction filtration, washing with distilled water, and drying for 3h under the condition of 140 ℃ to obtain the silicon dioxide coated nano titanium dioxide;
wherein the mass ratio of the nano titanium dioxide to the deionized water to the sodium hexametaphosphate to the 40%wt sodium silicate aqueous solution is 60:2000:1:500;
Uniformly mixing the silicon dioxide coated nano titanium dioxide and toluene, performing ultrasonic dispersion for 20min at 40kHz, adding a 3-aminopropyl triethoxy silane coupling agent, stirring and heating to 80 ℃ at a stirring speed of 300r/min, keeping the temperature at 80 ℃ for reaction for 3.5h, standing and curing for 12h at room temperature after the reaction, performing suction filtration, washing with ethanol, and drying for 2h at 120 ℃ to obtain the surface modified silicon dioxide coated nano titanium dioxide;
wherein, the mass ratio of the silicon dioxide coated nano titanium dioxide, toluene and the 3-aminopropyl triethoxy silane coupling agent is 35:1000:25;
uniformly mixing ethanol, 3, 5-di-tert-butyl-4-hydroxybenzaldehyde and ethanolamine, stirring and heating to 60 ℃ at a stirring speed of 150r/min, keeping the temperature at 60 ℃ for reaction for 1h, heating to 85 ℃, keeping the temperature at 85 ℃ for reaction for 3.5h, cooling to 0 ℃ at a speed of 5 ℃/min after reaction, adding sodium borohydride in five times on average, keeping the temperature at 0 ℃ for reaction for 0.5h, regulating the pH value to 1.5 by using 5% wt of aqueous hydrochloric acid solution, removing ethanol by rotary evaporation, regulating the pH value to 8.5 by using 10% wt of aqueous sodium hydroxide solution, extracting 3 times by using dichloromethane, drying by using anhydrous magnesium sulfate each time, filtering to remove anhydrous magnesium sulfate, and performing column chromatographic separation by using petroleum ether and ethyl acetate with a volume ratio of 5:1 as mobile phases after filtering to remove the dichloromethane, thereby obtaining 2, 6-di-tert-butyl-4-hydroxyethylaminomethyl phenol;
Wherein the mass ratio of the ethanol to the 3, 5-di-tert-butyl-4-hydroxybenzaldehyde to the ethanol to the sodium borohydride is 100:25:8:3.5;
uniformly mixing dimethyl thiodipropionate, 2, 6-di-tert-butyl-4-hydroxyethylamino methyl phenol and dibutyltin dilaurate according to the mass ratio of 220:620:10, stirring and heating to 150 ℃ at the stirring speed of 180r/min in a nitrogen atmosphere, keeping the temperature at 150 ℃ for reaction for 3 hours, and removing methanol by rotary evaporation after the reaction to obtain modified hindered phenol;
uniformly mixing the isocyanate composition, the modified hindered phenol and the surface modified silicon dioxide coated nano titanium dioxide according to the mass ratio of 560:300:150, and stirring at 25 ℃ and a stirring speed of 180r/min for reacting for 1h to obtain grafted modified isocyanate;
wherein the isocyanate composition is a mixture of diphenylmethane diisocyanate, toluene diisocyanate, 1, 6-hexamethylene diisocyanate and isophorone and isocyanate, and the mass ratio of the four is 1:1:2:2;
step (6), uniformly mixing the grafting modified isocyanate, the micromolecular monohydric alcohol, the micromolecular polyhydric alcohol, the acid compound and the isocyanate composition prepared in the step (5) according to the mass ratio of 13:4:4:14:10000, and sealing and preserving to obtain the yellowing-resistant isocyanate composition;
The small molecular monohydric alcohol is a mixture of methanol and ethanol, the mass ratio of the small molecular monohydric alcohol to the mixture of glycol and glycerol is 1:1, the mass ratio of the small molecular polyhydric alcohol to the mixture of glycol and glycerol is 1:1, the acidic compound is trifluoromethanesulfonic acid, the isocyanate composition is a mixture of diphenylmethane diisocyanate, toluene diisocyanate, 1, 6-hexamethylene diisocyanate and isophorone diisocyanate, and the mass ratio of the four is 1:1:2:2.
Comparative example 1
The comparative example discloses a preparation method of a yellowing-resistant isocyanate composition, which comprises the following steps:
uniformly mixing ethanol, 3, 5-di-tert-butyl-4-hydroxybenzaldehyde and ethanolamine, stirring and heating to 58 ℃ at a stirring speed of 150r/min, keeping the temperature at 58 ℃ for reaction for 1.2 hours, heating to 80 ℃, keeping the temperature at 80 ℃ for reaction for 4 hours, cooling to-3 ℃ at a speed of 5 ℃/min after reaction, adding sodium borohydride in five times on average, keeping the temperature at-3 ℃ for reaction for 0.7 hour, adjusting the pH value to 1.5 by using 5% wt hydrochloric acid aqueous solution after reaction, removing ethanol by rotary evaporation, adjusting the pH value to 8.5 by using 10% wt sodium hydroxide aqueous solution, extracting for 3 times by using dichloromethane, wherein the mass of dichloromethane for each extraction is 60% of the mass of ethanol, drying by using anhydrous magnesium sulfate, filtering to remove anhydrous magnesium sulfate, and performing column chromatography separation by using petroleum ether and ethyl acetate with a volume ratio of 5:1 as mobile phases after filtering to remove the dichloromethane, thereby obtaining 2, 6-di-tert-butyl-4-hydroxyethylaminomethyl phenol;
Wherein the mass ratio of the ethanol to the 3, 5-di-tert-butyl-4-hydroxybenzaldehyde to the ethanol to the sodium borohydride is 90:23:7:3;
uniformly mixing dimethyl thiodipropionate, 2, 6-di-tert-butyl-4-hydroxyethylamino methyl phenol and dibutyltin dilaurate according to the mass ratio of 210:590:7, stirring and heating to 140 ℃ at the stirring speed of 180r/min in a nitrogen atmosphere, keeping the temperature at 140 ℃ for reaction for 4 hours, and removing methanol by rotary evaporation after the reaction to obtain modified hindered phenol;
uniformly mixing the isocyanate composition and the modified hindered phenol according to the mass ratio of 500:410, and stirring at 15 ℃ and a stirring speed of 180r/min for reaction for 1.3 hours to obtain grafted modified isocyanate;
wherein the isocyanate composition is a mixture of diphenylmethane diisocyanate, toluene diisocyanate and 1, 6-hexamethylene diisocyanate, and the mass ratio of the diphenylmethane diisocyanate to the toluene diisocyanate to the 1:1:2;
uniformly mixing the grafting modified isocyanate, the micromolecular monohydric alcohol, the micromolecular polyhydric alcohol, the acid compound and the isocyanate composition prepared in the step (3) according to the mass ratio of 8:2:2:9:10000, and sealing and preserving to obtain the yellowing-resistant isocyanate composition;
The small molecular monohydric alcohol is a mixture of methanol and ethanol, the mass ratio of the small molecular monohydric alcohol to the mixture of glycol and glycerol is 1:1, the mass ratio of the small molecular polyhydric alcohol to the mixture of glycol and glycerol is 1:1, the acidic compound is trifluoromethanesulfonic acid, the isocyanate composition is a mixture of diphenylmethane diisocyanate, toluene diisocyanate and 1, 6-hexamethylene diisocyanate, and the mass ratio of the three is 1:1:2.
Comparative example 2
The comparative example discloses a preparation method of a yellowing-resistant isocyanate composition, which comprises the following steps:
uniformly mixing nano titanium dioxide, deionized water and sodium hexametaphosphate, performing ultrasonic dispersion for 30min under the condition of 30kHz, stirring and heating to 85 ℃ at the stirring speed of 300r/min, dropwise adding 40% wt sodium silicate aqueous solution, dropwise adding 1% wt hydrochloric acid aqueous solution while dropwise adding sodium silicate aqueous solution to enable the pH value of a reaction system to be 9 after the dropwise adding is completed within 60min, aging for 4.5h under the condition that the temperature is 85 ℃ and the pH value is 9, cooling, performing suction filtration, washing with distilled water, and drying for 4h under the condition of 130 ℃ to obtain the silicon dioxide coated nano titanium dioxide;
wherein the mass ratio of the nano titanium dioxide to the deionized water to the sodium hexametaphosphate to the 40%wt sodium silicate aqueous solution is 40:2000:1:300;
Uniformly mixing the silicon dioxide coated nano titanium dioxide and toluene, performing ultrasonic dispersion for 30min under the condition of 30kHz, adding a 3-aminopropyl triethoxy silane coupling agent, stirring and heating to 80 ℃ at the stirring speed of 300r/min, keeping the temperature at 80 ℃ for reaction for 3.5h, standing and curing for 12h at room temperature after the reaction, performing suction filtration, washing with ethanol, and drying for 3h under the condition of 115 ℃ to obtain the surface modified silicon dioxide coated nano titanium dioxide;
wherein, the mass ratio of the silicon dioxide coated nano titanium dioxide to the toluene to the 3-aminopropyl triethoxy silane coupling agent silicon dioxide coated nano titanium dioxide to the 3-aminopropyl triethoxy silane coupling agent is 25:800:15;
uniformly mixing the isocyanate composition and the surface modified silicon dioxide coated nano titanium dioxide according to the mass ratio of 500:410, and stirring at 15 ℃ and a stirring speed of 180r/min for reaction for 1.3 hours to obtain grafted modified isocyanate;
wherein the isocyanate composition is a mixture of diphenylmethane diisocyanate, toluene diisocyanate and 1, 6-hexamethylene diisocyanate, and the mass ratio of the diphenylmethane diisocyanate to the toluene diisocyanate to the 1:1:2;
uniformly mixing the grafting modified isocyanate, the micromolecular monohydric alcohol, the micromolecular polyhydric alcohol, the acid compound and the isocyanate composition prepared in the step (3) according to the mass ratio of 8:2:2:9:10000, and sealing and preserving to obtain the yellowing-resistant isocyanate composition;
The small molecular monohydric alcohol is a mixture of methanol and ethanol, the mass ratio of the small molecular monohydric alcohol to the mixture of glycol and glycerol is 1:1, the mass ratio of the small molecular polyhydric alcohol to the mixture of glycol and glycerol is 1:1, the acidic compound is trifluoromethanesulfonic acid, the isocyanate composition is a mixture of diphenylmethane diisocyanate, toluene diisocyanate and 1, 6-hexamethylene diisocyanate, and the mass ratio of the three is 1:1:2.
Comparative example 3
The comparative example discloses a preparation method of a yellowing-resistant isocyanate composition, which comprises the following steps:
uniformly mixing nano titanium dioxide, deionized water and sodium hexametaphosphate, performing ultrasonic dispersion for 30min under the condition of 30kHz, stirring and heating to 85 ℃ at the stirring speed of 300r/min, dropwise adding 40% wt sodium silicate aqueous solution, dropwise adding 1% wt hydrochloric acid aqueous solution while dropwise adding sodium silicate aqueous solution to enable the pH value of a reaction system to be 9 after the dropwise adding is completed within 60min, aging for 4.5h under the condition that the temperature is 85 ℃ and the pH value is 9, cooling, performing suction filtration, washing with distilled water, and drying for 4h under the condition of 130 ℃ to obtain the silicon dioxide coated nano titanium dioxide;
wherein the mass ratio of the nano titanium dioxide to the deionized water to the sodium hexametaphosphate to the 40%wt sodium silicate aqueous solution is 40:2000:1:300;
Uniformly mixing the silicon dioxide coated nano titanium dioxide and toluene, performing ultrasonic dispersion for 30min under the condition of 30kHz, adding a 3-aminopropyl triethoxy silane coupling agent, stirring and heating to 80 ℃ at the stirring speed of 300r/min, keeping the temperature at 80 ℃ for reaction for 3.5h, standing and curing for 12h at room temperature after the reaction, performing suction filtration, washing with ethanol, and drying for 3h under the condition of 115 ℃ to obtain the surface modified silicon dioxide coated nano titanium dioxide;
wherein, the mass ratio of the silicon dioxide coated nano titanium dioxide to the toluene to the 3-aminopropyl triethoxy silane coupling agent silicon dioxide coated nano titanium dioxide to the 3-aminopropyl triethoxy silane coupling agent is 25:800:15;
uniformly mixing ethanol, 3, 5-di-tert-butyl-4-hydroxybenzaldehyde and ethanolamine, stirring and heating to 58 ℃ at a stirring speed of 150r/min, keeping the temperature at 58 ℃ for reaction for 1.2 hours, heating to 80 ℃, keeping the temperature at 80 ℃ for reaction for 4 hours, cooling to-3 ℃ at a speed of 5 ℃/min after reaction, adding sodium borohydride in five times on average, keeping the temperature at-3 ℃ for reaction for 0.7 hour, adjusting the pH value to 1.5 by using 5% wt hydrochloric acid aqueous solution after reaction, removing ethanol by rotary evaporation, adjusting the pH value to 8.5 by using 10% wt sodium hydroxide aqueous solution, extracting for 3 times by using dichloromethane, wherein the mass of dichloromethane for each extraction is 60% of the mass of ethanol, drying by using anhydrous magnesium sulfate, filtering to remove anhydrous magnesium sulfate, and performing column chromatography separation by using petroleum ether and ethyl acetate with a volume ratio of 5:1 as mobile phases after filtering to remove the dichloromethane, thereby obtaining 2, 6-di-tert-butyl-4-hydroxyethylaminomethyl phenol;
Wherein the mass ratio of the ethanol to the 3, 5-di-tert-butyl-4-hydroxybenzaldehyde to the ethanol to the sodium borohydride is 90:23:7:3;
uniformly mixing dimethyl thiodipropionate, 2, 6-di-tert-butyl-4-hydroxyethylamino methyl phenol and dibutyltin dilaurate according to the mass ratio of 210:590:7, stirring and heating to 140 ℃ at the stirring speed of 180r/min in a nitrogen atmosphere, keeping the temperature at 140 ℃ for reaction for 4 hours, and removing methanol by rotary evaporation after the reaction to obtain modified hindered phenol;
uniformly mixing the isocyanate composition, the modified hindered phenol and the surface modified silicon dioxide coated nano titanium dioxide according to the mass ratio of 500:280:130, and stirring at 15 ℃ and a stirring speed of 180r/min for reaction for 1.3 hours to obtain grafted modified isocyanate;
wherein the isocyanate composition is a mixture of diphenylmethane diisocyanate and toluene diisocyanate, and the mass ratio of the diphenylmethane diisocyanate to the toluene diisocyanate is 1:1.
Step (6) uniformly mixing the grafting modified isocyanate, the micromolecular monohydric alcohol, the micromolecular polyhydric alcohol, the acid compound and the isocyanate composition prepared in the step (5) according to the mass ratio of 8:2:2:9:10000, and sealing and preserving to obtain the yellowing-resistant isocyanate composition;
The small molecular monohydric alcohol is a mixture of methanol and ethanol, the mass ratio of the methanol to the ethanol is 1:1, the small molecular polyhydric alcohol is a mixture of glycol and glycerol, the mass ratio of the glycol to the glycerol is 1:1, the acidic compound is trifluoromethanesulfonic acid, the isocyanate composition is a mixture of diphenylmethane diisocyanate and toluene diisocyanate, and the mass ratio of the glycol to the glycerol is 1:1.
The nano titanium dioxide in all the examples and the comparative examples is from Jiangsu Xianfeng nano technology Co., ltd, and the CAS number is 13463-67-7; sodium hexametaphosphate is from Hubei Xin bonus chemical industry Co., ltd, and the CAS number is 10124-56-8; the sodium silicate aqueous solution is from Shandong Bai Jia river chemical engineering Co., ltd, and the CAS number is 1344-09-8; toluene is from Tianjin Fuyu fine chemical Co., ltd, and the CAS number is 108-88-3; the 3-aminopropyl triethoxysilane coupling agent is from Nanjing BiSi chemical Co., ltd, with CAS number 919-30-2;3, 5-di-tert-butyl-4-hydroxybenzaldehyde is from Shanghai Seiyaka leaf Biotechnology Co., ltd, CAS number 1620-98-0; sodium borohydride is from Shanghai Ala Biochemical technology Co., ltd, with CAS number 16940-66-2; methylene dichloride is from Nanjing chemical reagents, inc., CAS number 75-09-2; dimethyl thiodipropionate is from Shanghai Ala Biochemical technology Co., ltd, with CAS number 4131-74-2; perchloric acid is available from Nanjing chemical reagents, inc., CAS number 7601-90-3; the trifluoro methanesulfonic acid is from Jiangxi national practice Co., ltd, and the CAS number is 1493-13-6.
Further, the yellowing-resistant isocyanate compositions obtained in examples 1 to 5 and comparative examples 1 to 3 were subjected to performance test:
test one, yellowing resistance test: the yellowing resistance test was carried out according to GB/T3143-1982 liquid chemical product color measurement method for examples 1-5 and comparative examples 1-3 under the conditions of standing for 60 days at 50℃under nitrogen and air, and the test results are shown in Table 1:
TABLE 1
Example 1 Example 2 Example 3 Example 4 Example 5 Comparative example 1 Comparative example 2 Comparative example 3
Hazen color number (Nitrogen) 5 5 5 5 5 5 10 5
Hazen color number (air) 10 10 5 5 5 10 15 10
As can be seen from the test results in Table 1, the isocyanate compositions prepared in examples 1 to 5 of the present invention had good yellowing resistance, which was significantly superior to the isocyanate compositions prepared in comparative examples 1 to 3. It can be seen from example 3 and comparative examples 1 and 2 that the oxidation resistance of titanium dioxide is obviously weaker than that of hindered phenol antioxidants under the condition of no direct irradiation of ultraviolet rays, and more plays a role in assisting in oxidation resistance, and from example 3 and comparative example 3, the isocyanate compound of the invention has better yellowing resistance effect on aromatic isocyanate compositions, and from examples 1-5, the yellowing resistance of the isocyanate composition is more excellent along with the increase of the contents of the hindered phenol antioxidants and the modified titanium dioxide.
Test II, storage performance test: storage property tests were carried out according to GB/T3143-1982 liquid chemical product colour assay for examples 1-5, comparative examples 1-3 under nitrogen at 30℃and air until isocyanate was yellow, the test results are shown in Table 2:
TABLE 2
Example 1 Example 2 Example 3 Example 4 Example 5 Comparative example 1 Comparative example 2 Comparative example 3
Color number is greater than 20hazen weeks (nitrogen) 22 23 27 32 36 26 22 25
Color number is greater than 20hazen weeks (air) 15 15 19 22 25 18 14 17
As can be seen from the test results of Table 2, the isocyanate compositions prepared in examples 1 to 5 of the present invention had good storage stability, which was significantly superior to the isocyanate compositions prepared in comparative examples 1 to 3. It can be seen from example 3 and comparative examples 1 and 2 that the hindered phenol antioxidant plays a major role in the storage of isocyanate, and from example 3 and comparative example 3, it can be seen that the yellowing period of the pure aromatic isocyanate composition after the addition of the stabilizer is shorter than that of the aromatic, aliphatic mixed isocyanate composition because the aromatic isocyanate composition is easily oxidized due to the direct connection of the benzene ring to the isocyanate group to form a conjugated system, and thus the storage stability is relatively weaker than that of the aliphatic isocyanate composition.
Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims (8)

1. A process for preparing a yellowing-resistant isocyanate composition comprising the steps of:
uniformly mixing ethanol, 3, 5-di-tert-butyl-4-hydroxybenzaldehyde and ethanolamine, stirring, heating for reaction, heating, continuing the reaction, cooling after the reaction, adding sodium borohydride, reacting at a low temperature, and purifying after the reaction to obtain the 2, 6-di-tert-butyl-4-hydroxyethylaminomethyl phenol;
step (2) uniformly mixing dimethyl thiodipropionate and 2, 6-di-tert-butyl-4-hydroxyethylamino methyl phenol, adding dibutyltin dilaurate, stirring and heating in an inert gas atmosphere for reaction, and performing rotary evaporation to obtain modified hindered phenol;
wherein the mass ratio of the dimethyl thiodipropionate to the 2, 6-di-tert-butyl-4-hydroxyethylamino methyl phenol to the dibutyltin dilaurate is (200-220): 560-620): 5-10;
Uniformly mixing the isocyanate composition, the modified hindered phenol and the surface modified silicon dioxide coated nano titanium dioxide according to the mass ratio of (400-600) (250-300) (100-150), and stirring for reaction to obtain grafted modified isocyanate;
the isocyanate composition comprises a mixture of at least 2 of diphenylmethane diisocyanate, toluene diisocyanate, 1, 6-hexamethylene diisocyanate, isophorone diisocyanate and m-xylylene diisocyanate;
the surface modified silicon dioxide coated nano titanium dioxide is prepared by the following steps:
uniformly mixing nano titanium dioxide with deionized water, adding sodium hexametaphosphate as a dispersing agent, performing ultrasonic dispersion, stirring and heating, dropwise adding a sodium silicate aqueous solution, dropwise adding a hydrochloric acid aqueous solution while dropwise adding the sodium silicate aqueous solution to enable the pH value of a reaction system to be 8-10, aging, purifying, and drying to obtain the silicon dioxide coated nano titanium dioxide;
wherein the mass ratio of the nano titanium dioxide to the deionized water to the sodium hexametaphosphate to the sodium silicate aqueous solution is (20-60): 2000 (1-3): 100-500); the aqueous sodium silicate solution comprises 40% by weight of aqueous sodium silicate solution;
uniformly mixing the silicon dioxide coated nano titanium dioxide with toluene, performing ultrasonic dispersion, adding a silane coupling agent, stirring, heating, reacting, curing, purifying and drying to obtain the surface modified silicon dioxide coated nano titanium dioxide;
Wherein, the mass ratio of the silicon dioxide coated nano titanium dioxide to the toluene to the silane coupling agent is (15-35): 600-1000): 5-25; the silane coupling agent comprises a 3-aminopropyl triethoxy silane coupling agent;
step (4) uniformly mixing the grafting modified isocyanate, the micromolecular monohydric alcohol, the micromolecular polyhydric alcohol, the acid compound and the isocyanate composition prepared in the step (3) according to the mass ratio of (3-13): 1-4): 4-14): 10000 to obtain the yellowing-resistant isocyanate composition;
the isocyanate composition comprises a mixture of at least 2 of diphenylmethane diisocyanate, toluene diisocyanate, 1, 6-hexamethylene diisocyanate, isophorone diisocyanate, and isophthalene diisocyanate.
2. The method for producing a yellowing resistant isocyanate composition according to claim 1, wherein in said step (1): the mass ratio of the ethanol to the 3, 5-di-tert-butyl-4-hydroxybenzaldehyde to the ethanolamine to the sodium borohydride is (80-100), 21-25, 6-8 and 2.5-3.5; stirring and heating reaction conditions are that the stirring speed is 150r/min, and the reaction is carried out for 1-1.5h at the temperature of 55-60 ℃; the reaction is continued for 3.5 to 4.5 hours at the temperature of 75 to 85 ℃; the reaction condition of low temperature is that the reaction is carried out for 0.5 to 1 hour at the temperature of-5 to 0 ℃.
3. The method for producing a yellowing resistant isocyanate composition according to claim 1, wherein in said step (2): the condition of stirring and heating reaction is that the reaction is carried out for 3-5h at the temperature of 130-150 ℃ under the stirring speed of 180 r/min.
4. The method for producing a yellowing resistant isocyanate composition according to claim 1, wherein in said step (3): the condition of stirring reaction is that the stirring speed is 180r/min, and the reaction is carried out for 1-1.5h at the temperature of 5-25 ℃.
5. The method for preparing the yellowing-resistant isocyanate composition according to claim 1, wherein when preparing the silica coated nano titanium dioxide: ultrasonic dispersion is carried out for 20-40min under the frequency of 20-40 kHz; stirring and heating at a speed of 300r/min and a temperature of 80-90 ℃; the dripping time of the sodium silicate aqueous solution is 30-90min; the aqueous hydrochloric acid solution comprises 1% by weight of aqueous hydrochloric acid solution; the aging condition is that the pH value is 8-10 and the aging is 4-5 hours at the temperature of 80-90 ℃.
6. The method for preparing the yellowing-resistant isocyanate composition according to claim 1, wherein when preparing the surface-modified silica-coated nano titanium dioxide: ultrasonic dispersion is carried out for 20-40min under the frequency of 20-40kHz, and the condition of stirring and heating reaction is that the reaction is carried out for 3-4h under the stirring speed of 300r/min and the temperature of 75-85 ℃.
7. The method for producing a yellowing resistant isocyanate composition according to claim 1, wherein in said step (4): the small molecular monohydric alcohol comprises at least one of methanol and ethanol; the small molecular polyalcohol comprises at least one of glycol and glycerol; the acidic compound includes at least one of perchloric acid and trifluoromethanesulfonic acid.
8. A yellowing-resistant isocyanate composition prepared by the method of preparing the yellowing-resistant isocyanate composition of any one of claims 1 to 7.
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