CN110878033B - Functional color reducing agent and method for stabilizing color number of diisocyanate product - Google Patents
Functional color reducing agent and method for stabilizing color number of diisocyanate product Download PDFInfo
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- CN110878033B CN110878033B CN201911234924.7A CN201911234924A CN110878033B CN 110878033 B CN110878033 B CN 110878033B CN 201911234924 A CN201911234924 A CN 201911234924A CN 110878033 B CN110878033 B CN 110878033B
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- C07—ORGANIC CHEMISTRY
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- C07C263/00—Preparation of derivatives of isocyanic acid
- C07C263/18—Separation; Purification; Stabilisation; Use of additives
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C263/00—Preparation of derivatives of isocyanic acid
- C07C263/18—Separation; Purification; Stabilisation; Use of additives
- C07C263/20—Separation; Purification
Abstract
The invention belongs to the technical field of diisocyanate production, and particularly relates to a functional color reducing agent and a method for stabilizing the color number of a diisocyanate product, wherein the functional color reducing agent comprises the following components: (a) hindered amine substances, (b) hindered phenolic substances and/or ester substances. The method for stabilizing the color number of the diisocyanate product comprises the steps of mixing the functional color reducing agent with the diisocyanate, and freezing, crystallizing and re-melting the mixture to form liquid to obtain the diisocyanate product with stable APHA color number. The method can avoid the generation of yellow green salt substances in the processes of freezing, crystallizing and remelting the diisocyanate product, realize the color number stability of the diisocyanate product and keep the low color number of the product after freezing, crystallizing and remelting.
Description
Technical Field
The invention belongs to the technical field of diisocyanate production, and particularly relates to a functional color reducing agent and a method for stabilizing the color number of a diisocyanate product.
Background
Diisocyanate is generally prepared by condensation of amine as a raw material to prepare polyamine and then phosgenation of the polyamine. Therefore, the prepared diisocyanate basically contains acyl chloride substances and urea impurities. Research shows that in the process of low-temperature freezing crystallization of diisocyanate products, due to the change of a temperature field, contained acyl chloride substances and urea impurities gradually migrate to the core of a packaging barrel through pores of crystals to be enriched; and along with the increase of the concentration, the acyl chloride substances and the urea substances are combined with each other irreversibly to form salts, so that the diisocyanate crystal at the barrel core is yellow green, the whole barrel of liquid diisocyanate product after being dissolved is also yellow green, the color number is obviously increased, and the use is influenced.
The production process of diisocyanates is complicated and color-causing substances, such as aldehydes, ketones, chlorides and nitrogen-containing substances, are formed in ppm levels. There have been many processes for reducing the color number of diisocyanates (e.g., diphenylmethane diisocyanate MDI, toluene diisocyanate TDI, dicyclohexylmethane diisocyanate HMDI, isophorone diisocyanate IPDI, naphthalene 1, 5-diisocyanate NDI, hexamethylene diisocyanate HDI, p-phenylene diisocyanate PPDI, 1, 4-cyclohexane diisocyanate CHDI) so as to obtain a low color number diisocyanate product. These methods include the following aspects:
1. treatment or purification of the starting polyamine materials or oligomers thereof
For example, patent document EP0546398A discloses the acidification of polymethylene polyphenylene polyamines prior to phosgenation, followed by the production of isocyanate products of low color number.
For example, patent document EP446781A discloses a process in which polymeric MDA (monomeric and oligomeric polymethylene polyphenylene polyamines) are first treated with hydrogen and subsequently phosgenated to give a lighter color MDI.
For example, patent document CN 103319372A discloses a method for preparing light-colored or colorless dicyclohexylmethane diisocyanate (HMDI) by operations such as phosgenation, distillation, and rectification after controlling the content of alcohol compounds in dicyclohexylmethane diamine as a raw material to be less than 0.2%.
For example, patent document CN1356980A discloses a process for preparing isocyanates having a light color by first controlling the content of bromine or iodine-containing molecules or mixtures thereof in phosgene to less than 25ppm and then preparing isocyanates having a light color by phosgenating amines of the diphenylmethane diamine series or mixtures of a plurality of these amines with the above-mentioned phosgene.
2. Solution for researching color reduction in phosgenation process
For example, patent document US5364958A discloses that it is possible to prepare isocyanates having a light color by completely removing phosgene at low temperature after completion of the phosgenation reaction and subsequently treating the product while it is hot with HCl gas.
For example, patent document DE19817691.0 describes a process for preparing MDI/PMDI mixtures having a lower content of hydrogen chloride by-products and a lower iodine color value by optimizing the parameters in the phosgenation reaction.
3. After phosgenation and before separation and rectification treatment, the crude product containing isocyanate is added with color-reducing additive
For example, patent document EP0581100A discloses a process for preparing polyisocyanates in which a chemical reducing agent is added after phosgenation and before removal of the solvent to prepare a light-colored product.
For example, U.S. Pat. Nos. 4465639A, 538500A, EP0445602A and EP0467125A describe the addition of water, carboxylic acids, alkanols or polyether polyols, respectively, to the crude seed after the phosgenation for the purpose of reducing color.
4. The post-treatment stage of the final product is subjected to color reduction treatment
For example, EP0133528A discloses the extractive purification of isocyanates to give a light-colored MDI product.
For example, patent document EP0561225A discloses a process for preparing light-colored isocyanates or isocyanate mixtures in which the isocyanates or solutions obtained after phosgenation of the corresponding amines are subjected to a hydrogenation reduction treatment at a pressure of from 1 to 150bar and a temperature of from 100 to 180 ℃.
For example, patent document CN108864402A discloses a modified isocyanate excellent in storage stability and low in color number, and a method for producing the same. The antioxidant is selected from one or more of hindered phenol antioxidant, hindered amine antioxidant and phosphite antioxidant. By adding the antioxidant, the problem that the color number of unsaturated bonds of benzene rings in a diphenylmethane diisocyanate structure is higher due to thermal oxidation aging and free radical oxidation is mainly solved. In addition, the antioxidants selected are all of a very conventional structure in the art.
In summary, the present inventors have achieved the production of low color number diisocyanate products by innovative technical means, but none of the prior patents or technologies address the following needs: the diisocyanate product after freezing crystallization at-30 ℃ to 5 ℃ is melted again, the color number is obviously increased and the product is yellow-green. Therefore, it is highly desirable to develop a method for maintaining the physical properties of low color numbers of low-color-number diisocyanate products after freezing, crystallizing and resolubilizing.
Disclosure of Invention
The invention aims to provide a functional color reducing agent and a method for stabilizing the color number of a diisocyanate product aiming at the problem that the color number of the diisocyanate product is obviously increased after low-temperature freezing and remelting.
Diisocyanate is generally prepared by condensation of amine as a raw material to prepare polyamine and then phosgenation of the polyamine. Therefore, the prepared diisocyanate basically contains acyl chloride substances and urea impurities. For commercial diisocyanate products, the content of the acid chloride is generally in the range of 25-250ppm, and the content of the urea impurity is generally in the range of 400-1500 ppm. When the diisocyanate product undergoes low-temperature freezing crystallization, substances of the type gradually migrate to the packaging barrel core through pores of the crystals to be enriched, and as the concentration rises, the acyl chloride substances and the urea substances are combined with each other irreversibly to form salts, so that the diisocyanate crystals at the barrel core are yellow-green, the liquid diisocyanate product in the whole barrel after being dissolved is also yellow-green, and the color number is obviously increased. Thus, freezing crystallization and remelting make the color number of the diisocyanate product high.
The applicant finds that after a functional color reducing agent is added into the prepared diisocyanate product, irreversible combination of an acyl chloride substance and a urea substance in the low-temperature freezing and crystallization process of the diisocyanate product can be destroyed, and then a yellow-green salt substance is avoided, so that the color number of the diisocyanate product is stable, and the problem of the increase of the color number of the product is avoided.
In order to achieve the purpose, the technical scheme provided by the invention is as follows:
in one aspect, a functional color reducing agent is provided, which comprises the following components:
(a) a hindered amine-type substance, wherein the hindered amine-type substance,
(b) hindered phenolic and/or ester species;
wherein the mass ratio of component (a) to component (b) is 1:1 to 5:1 (e.g., 1.5:1, 2.5:1, 3.5:1, 4:1, 4.5:1), preferably 1:1 to 3:1, more preferably 2: 1.
The functional color reducing agent is a mixture, and can be a mixture of a hindered amine substance and a hindered phenol substance, or a mixture of a hindered amine substance and an ester substance, or a mixture of a hindered amine substance, a hindered phenol substance and an ester substance. In the research of the applicant, the hindered amine substance in the mixture is necessarily added, because the urea impurities contained in the diisocyanate product are combined with the acyl chloride substance in the freezing and crystallization process, and after the functional color reducing agent is added, the hindered amine substance in the diisocyanate product can be preferentially combined with the acyl chloride substance to destroy the irreversible combination of the urea substance and the acyl chloride substance. The hindered phenol substances or ester substances in the functional color reducing agent need to exert a synergistic effect with the hindered amine substances; the addition of the hindered phenol substance or ester substance can promote or accelerate the combination of the hindered amine substance and the acyl chloride substance, and the combination process is completely carried out. Therefore, the selection of the types of the component (a) and the component (b) and the amount ratio thereof in the functional color reducing agent of the present invention have an influence on the effect of color number stabilization.
The applicant also found in the research that the effect of stabilizing the color number of the diisocyanate is better when the content of the hindered amine substances is higher than the content of the hindered phenolic substances and/or ester substances in the functional color reducing agent. If the content of the hindered phenolic substances and/or ester substances is higher, the effect of stabilizing the color number of the diisocyanate is weakened; in addition, the addition amount of the hindered amine substance also needs to be controlled, and the effect of color reduction cannot be achieved easily when the amount is too small or too large.
According to the functional type color reducing agent provided by the invention, in some examples, the functional type color reducing agent is in a liquid state at normal temperature (at 25 ℃), and the viscosity of the functional type color reducing agent is 500-2000 mPas (at 25 ℃), preferably 1000-1500 mPas (at 25 ℃), and more preferably 1200 mPas (at 25 ℃). The viscosity of the functional color reducing agent is influenced by the ratio of the component (a) to the component (b).
According to the functional color reducing agent provided by the invention, in some examples, the molecular structure of the hindered amine substance is shown as the formula (I):
R2—NH—R1， (I)
in the formula, R1And R2The structural groups are the same or different and are respectively and independently selected from the structural groups shown in the formulas (i) to (v);
in a preferred embodiment, R1And R2The same, more preferably a structural group represented by the formula (iv).
For example, when R is1And R2The hindered amine is 4, 4' -bis- (2,3, 3-trimethyl-1-butenyl) diphenylamine; when R is1And R2The hindered amine substance is 4, 4' -bis (phenylisopropyl) diphenylamine; when R is1And R2And (b) the same, and is a structural group shown in formula (i), then the hindered amine substance is 4, 4' -di-tert-butyl diphenylamine.
In some preferred embodiments, the hindered amine species is selected from one or more of 4,4 '-bis- (2,3, 3-trimethyl-1-butenyl) diphenylamine, 4' -bis (phenylisopropyl) diphenylamine, 4 '-di-tert-butyldiphenylamine, and 4, 4' -di-sec-butyldiphenylamine, and more preferably from 4,4 '-bis- (2,3, 3-trimethyl-1-butenyl) diphenylamine and/or 4, 4' -bis (phenylisopropyl) diphenylamine.
According to the functional color reducing agent provided by the invention, in some examples, the molecular structure of the hindered phenol substance is shown as formula II:
R4—HN—(CH2)n—NH—R3， (II)
in the formula, R3And R4The structural groups are the same or different and are respectively and independently selected from the structural groups shown in the formulas (vi) to (vii); n is a positive integer, and the value of n is 1-8, preferably 4-8, and more preferably 6;
in the formulae (vi) to (vii), k is a natural number and has a value of 0 to 4, preferably 1 to 3, and more preferably 2.
In a preferred embodiment, R3And R4Also, the structural group represented by the formula (vi) is more preferable. For example, when R is3And R4The same as above and is a structural group represented by the formula (vi), the hindered phenol substance may be one or more selected from N, N ' -bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) diamine, N ' -bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) acetyl) diamine and N, N ' -bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) formyl) diamine.
In some preferred embodiments, the hindered phenolic is selected from the group consisting of N, N ' -bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) butanediamine, N ' -bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) pentanediamine, N ' -bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine, N ' -bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) heptanediamine, N ' -bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) octanediamine, N, one or more of N ' -bis- (2- (3, 5-di-tert-butyl-4-hydroxyphenyl) acetyl) hexamethylenediamine and N, N ' -bis- (4- (3, 5-di-tert-butyl-4-hydroxyphenyl) butyryl) hexamethylenediamine, and more preferably N, N ' -bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexamethylenediamine.
According to the functional color reducing agent provided by the invention, in some examples, the molecular structure of the ester substance is shown as the formula (III):
in the formula, R5And R6The structural groups are the same or different and are respectively and independently selected from the structural groups shown in the formulas (viii) to (ix); n is a positive integer, and the value of n is 1-8, preferably 4-8, and more preferably 8;
in the formulae (viii) to (ix), k is a natural number and has a value of 0 to 2, preferably 0 to 1, and more preferably 0.
In a preferred embodiment, R5And R6The same; more preferably a structural group represented by the formula (viii). For example, when R is5And R6And (viii), the ester is selected from one or more of bis (1,2,2,6, 6-pentamethyl-4-piperidyl) diacid ester, bis (1,2,2,6, 6-pentaethyl-4-piperidyl) diacid ester and bis (1,2,2,6, 6-pentapropyl-4-piperidyl) diacid ester.
In some preferred embodiments, the ester is selected from the group consisting of bis (1,2,2,6, 6-pentamethyl-4-piperidinyl) adipate, bis (1,2,2,6, 6-pentamethyl-4-piperidinyl) pimelate, bis (1,2,2,6, 6-pentamethyl-4-piperidinyl) suberate, one or more of bis (1,2,2,6, 6-pentamethyl-4-piperidinyl) azelate, bis (1,2,2,6, 6-pentamethyl-4-piperidinyl) sebacate and bis (1,2,2,6, 6-pentaethyl-4-piperidinyl) sebacate, more preferably bis (1,2,2,6, 6-pentamethyl-4-piperidinyl) sebacate.
In another aspect, a method for stabilizing the color number of a diisocyanate product is provided, wherein the diisocyanate product is mixed with the functional color reducing agent, and then is frozen, crystallized and re-melted to form a liquid, so as to obtain the APHA color number-stabilized diisocyanate product.
In the method, when the functional color reducing agent is mixed with the diisocyanate, the mixing time is the reference standard of ensuring uniform mixing. For example, the mixture may be stirred at 200 rpm for 30 minutes.
In some examples, the functional color-reducing agent is added in an amount of 0.001 wt% to 0.2 wt% (e.g., 0.002 wt%, 0.004 wt%, 0.005 wt%, 0.006 wt%, 0.008 wt%, 0.012 wt%, 0.015 wt%, 0.02 wt%, 0.04 wt%, 0.06 wt%, 0.1 wt%, 0.15 wt%), more preferably 0.01 wt% to 0.08 wt%, and still more preferably 0.02 wt% to 0.04 wt% based on the weight of the diisocyanate.
In addition, the addition amount of the functional color reducing agent needs to be controlled, and too small (less than 0.001%) or too large (more than 0.2%) is not favorable for the color reduction.
According to the method provided by the present invention, in some examples, the diisocyanate is selected from one or more of diphenylmethane diisocyanate (MDI), Toluene Diisocyanate (TDI), dicyclohexylmethane diisocyanate (HMDI), isophorone diisocyanate (IPDI), 1, 5-Naphthalene Diisocyanate (NDI), Hexamethylene Diisocyanate (HDI), p-phenylene diisocyanate (PPDI) and 1, 4-cyclohexane diisocyanate (CHDI), preferably selected from diphenylmethane diisocyanate (MDI) and/or Toluene Diisocyanate (TDI), more preferably diphenylmethane diisocyanate (MDI).
According to the method provided by the invention, the Toluene Diisocyanate (TDI) can exist in various isomers. In some examples, the Toluene Diisocyanate (TDI) has a 2, 4-isomer content of 65 to 99.5 wt%, preferably 79 to 81 wt%, based on the total weight (e.g., 100 wt%) of the Toluene Diisocyanate (TDI).
The diphenylmethane diisocyanate (MDI) may exist in a variety of isomers. In some examples, the diphenylmethane diisocyanate (MDI) has a 4, 4-isomer content of 10 to 99.5 wt%, preferably 44.5 to 49 wt%, based on the total weight (e.g., 100 wt%) of the diphenylmethane diisocyanate (MDI).
According to the method provided by the invention, the temperature of the freezing crystallization is preferably-30 ℃ to 5 ℃ (for example, -28 ℃, -25 ℃, -20 ℃, -15 ℃, -12 ℃, -8 ℃, -5 ℃, -1 ℃, 0 ℃,2 ℃), and more preferably-18 ℃ to-10 ℃. Preferably, the temperature of the remelting is 60-80 ℃ (e.g., 65 ℃, 72 ℃, 74 ℃), more preferably 70-75 ℃.
According to the method provided by the invention, the difference of APHA color numbers of the diisocyanate before and after freezing crystallization and remelting treatment is preferably no more than 3# (for example, the difference is 2#, 0#), and preferably no more than 1 #.
The time of the freezing crystallization and remelting treatment is not limited herein.
The "APHA color number difference" as used herein means the absolute value of the difference between the APHA color number of the diisocyanate measured after the freezing crystallization and remelting treatments and the APHA color number of the diisocyanate product measured before the freezing crystallization and remelting treatments. The process conditions of the freezing crystallization and the remelting are as described above; the procedures and equipment for the freeze crystallization and the remelting are well known to those skilled in the art and will not be described further herein.
The functional color reducing agent comprises at least one hindered amine substance, and additionally comprises a hindered phenolic substance, an ester substance or a mixture of the hindered phenolic substance and the ester substance. The hindered amine substance can be preferentially combined with the acyl chloride substance to destroy the irreversible combination of the urea substance and the acyl chloride substance. The hindered phenol substance or ester substance can exert a synergistic effect with the hindered amine substance, promote or accelerate the combination of the hindered amine substance and the acyl chloride substance, and ensure that the combination process is carried out completely. According to the invention, the functional color reducing agent is mixed with the prepared diisocyanate finished product, and the frozen and crystallized diisocyanate product is re-melted at the temperature of-30-5 ℃, so that the problems of obvious color number increase and yellow green color appearance can be avoided, and finally the color number of the melted diisocyanate product is stable.
Compared with the prior art, the beneficial effect of this application technical scheme lies in:
after the functional color reducing agent is added, the irreversible combination of the acyl chloride substance and the urea substance in the low-temperature freezing and crystallizing process can be destroyed, and then the generation of yellow-green salt substances is avoided, so that the color stability of the liquid diisocyanate product obtained after the dissolution is ensured. After the diisocyanate is mixed with the functional color reducing agent, the obtained diisocyanate product can ensure that the APHA color number is basically unchanged or cannot be increased after being frozen, crystallized and re-dissolved at the temperature of between 30 ℃ below zero and 5 ℃, and has excellent color stability within a certain storage time.
Detailed Description
In order that the technical features and contents of the present invention can be understood in detail, preferred embodiments of the present invention will be described in more detail below. While the preferred embodiments of the present invention have been described in the examples, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein.
< sources of raw materials >
For commercial diisocyanate products, the impurities present include acid chlorides, urea impurities, and the like. Wherein, the content of the acyl chloride substances is usually in the range of 25-250ppm, and the content of the urea impurities is usually in the range of 400-1500 ppm; the impurity content in the finished diisocyanate product is qualified as long as the national standard is met. The various types of diisocyanates have different color numbers due to various reasons, such as load adjustment of production facilities, process fluctuations, equipment performance fluctuations, photo-oxidation and thermal oxidation occurring during the reaction, and the like.
Toluene Diisocyanate (TDI) and diphenylmethane diisocyanate (MDI) from TDI and MDI units, respectively, of Wanhua chemical cigarette bench industry park;
4, 4' -bis- (2,3, 3-trimethyl-1-butenyl) diphenylamine, shanghai yi chen chemical company, ltd;
4, 4' -bis (phenylisopropyl) diphenylamine, shanghai yi chen chemical company, ltd;
bis (1,2,2,6, 6-pentamethyl-4-piperidinyl) sebacate, shanghai-chen chemical company, ltd;
n, N' -bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexamethylenediamine, Shanghai Yichen chemical Co., Ltd.
< detection method >
APHA color number detection of diisocyanate product: a digital display colorimeter (manufacturer, BYK company, Germany) is adopted, and the detection standard is GB/T605-.
Example 1
A method of stabilizing the color number of a diisocyanate product comprising the steps of:
(1) preparing a closed galvanized barrel (the volume is 210L) filled with a toluene diisocyanate TDI-80 industrial product, and detecting that the APHA color number of the TDI-80 industrial product is 7 #;
(2) preparing a mixture of 4, 4' -bis- (2,3, 3-trimethyl-1-butenyl) diphenylamine and bis (1,2,2,6, 6-pentamethyl-4-piperidyl) sebacate, wherein the mass ratio of the two in the mixture is 2:1, and stirring and mixing the mixture for 30 minutes at the rotating speed of 200 revolutions per minute to prepare the functional color reducing agent. The viscosity of the obtained functional color reducing agent was 1325 pas (at 25 ℃).
(3) Adding the prepared functional color reducing agent into a prepared closed galvanized barrel filled with a toluene diisocyanate TDI-80 industrial product, wherein the addition amount of the functional color reducing agent is 0.0300 percent of the mass of TDI-80; after shaking up with a bucket shaker, it was stored in a freezer at-18 ℃ for 1.5 months.
Then opening the closed galvanized barrel, observing the color of TDI-80 in a crystalline state, and observing that the product at the barrel core presents a snow-white appearance; melting the product in the barrel in 70 deg.C water bath to obtain liquid TDI-80, which is colorless and transparent, and has APHA color number of 7 #.
The difference of APHA color number of the diisocyanate product before and after freezing crystallization and remelting is 0 #.
Example 2
A method of stabilizing the color number of a diisocyanate product comprising the steps of:
(1) preparing a closed galvanized barrel (the volume is 210L) filled with a toluene diisocyanate TDI-80 industrial product, and detecting that the APHA color number of the TDI-80 industrial product is 5 #;
(2) preparing a mixture of 4,4 '-bis (phenylisopropyl) diphenylamine and N, N' -bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine, wherein the mass ratio of the two in the mixture is 4:1, and stirring and mixing the mixture for 30 minutes at the rotating speed of 200 revolutions per minute to prepare the functional color reducing agent. The viscosity of the obtained functional toner was 1200 pas (at 25 ℃).
(3) Adding the prepared functional color reducing agent into a prepared closed galvanized barrel filled with a toluene diisocyanate TDI-80 industrial product, wherein the addition amount of the functional color reducing agent is 0.0200% of the mass of TDI-80; after shaking up with a bucket shaker, the mixture was stored in a freezer at-30 ℃ for 2.0 months.
Then opening the closed galvanized barrel, observing the color of TDI-80 in a crystalline state, and observing that the barrel core presents a snow-white appearance; melting the product in the barrel in 70 deg.C water bath to obtain liquid TDI-80, which is colorless and transparent, and has APHA color number of # 5 by detection.
The difference of APHA color number of the diisocyanate product before and after freezing crystallization and remelting is 0 #.
Example 3
A method of stabilizing the color number of a diisocyanate product comprising the steps of:
(1) preparing a closed galvanized barrel (the volume is 210L) filled with a diphenylmethane diisocyanate MDI-50 industrial product, wherein the APHA color number of the MDI-50 industrial product is 9# through detection;
(2) preparing a mixture of 4, 4' -bis (phenylisopropyl) diphenylamine and bis (1,2,2,6, 6-pentamethyl-4-piperidyl) sebacate, wherein the mass ratio of the two in the mixture is 2.5:1, and stirring and mixing the mixture for 30 minutes at the rotating speed of 200 revolutions per minute to prepare the functional color reducing agent. The viscosity of the obtained functional toner was 1287 pas (at 25 ℃).
(3) Adding the prepared functional color reducing agent into a prepared closed galvanized barrel filled with a diphenylmethane diisocyanate MDI-50 industrial product, wherein the addition amount of the functional color reducing agent is 0.0250% of the mass of MDI-50; shaking with a barrel shaker, and storing in a freezer at-10 deg.C for 1.0 month.
Then opening the closed galvanized barrel, observing the color of MDI-50 in a crystalline state, and observing that the barrel core presents a snow-white appearance; melting the product in the barrel in 70 deg.C water bath to obtain liquid MDI-50, which is colorless and transparent, and has APHA color number of 9# by detection.
The difference of APHA color number of the diisocyanate product before and after freezing crystallization and remelting is 0 #.
Example 4
A method of stabilizing the color number of a diisocyanate product comprising the steps of:
(1) preparing a closed galvanized barrel (the volume is 210L) filled with a diphenylmethane diisocyanate MDI-50 industrial product, wherein the APHA color number of the MDI-50 industrial product is 8# through detection;
(2) preparing a mixture of 4,4 '-bis- (2,3, 3-trimethyl-1-butenyl) diphenylamine and N, N' -bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine, wherein the mass ratio of the two in the mixture is 3:1, and stirring and mixing the mixture for 30 minutes at the rotating speed of 200 revolutions per minute to prepare the functional color reducing agent. The viscosity of the obtained functional toner was 1155 pas (at 25 ℃).
(3) Adding the prepared functional color reducing agent into a prepared closed galvanized barrel filled with diphenylmethane diisocyanate MDI-50 industrial products, wherein the addition amount of the functional color reducing agent is 0.0400% of the mass of MDI-50; after shaking up with a bucket shaker, it was stored in a freezer at 5 ℃ for 6.0 months.
Then opening the closed galvanized barrel, observing the color of MDI-50 in a crystalline state, and observing that the barrel core presents a snow-white appearance; melting the product in the barrel in 70 deg.C water bath to obtain liquid MDI-50, which is colorless and transparent, and has APHA color number of 8# by detection.
The difference of APHA color number of the diisocyanate product before and after freezing crystallization and remelting is 0 #.
Example 5
A method of stabilizing the color number of a diisocyanate product comprising the steps of:
(1) preparing a closed galvanizing barrel (the volume is 210L) filled with a toluene diisocyanate TDI-80 industrial product, and detecting that the APHA color number of the TDI-80 industrial product is 6 #;
(2) preparing a mixture of 4,4 '-bis- (2,3, 3-trimethyl-1-butenyl) diphenylamine and N, N' -bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine, wherein the mass ratio of the two in the mixture is 5:1, and stirring and mixing the mixture for 30 minutes at the rotating speed of 200 revolutions per minute to prepare the functional color reducing agent. The viscosity of the obtained functional toner was 1356 pas (at 25 ℃).
(3) Adding the prepared functional color reducing agent into a prepared closed galvanized barrel filled with a toluene diisocyanate TDI-80 industrial product, wherein the addition amount of the functional color reducing agent is 0.001 percent of the mass of TDI-80; after shaking up with a bucket shaker, the mixture was stored in a freezer at-30 ℃ for 2.0 months.
Then opening the closed galvanized barrel, observing the color of TDI-80 in a crystalline state, and observing that the barrel core presents a snow-white appearance; melting the product in the barrel in 70 deg.C water bath to obtain liquid TDI-80, which is colorless and transparent, and has APHA color number of 8# by detection.
The difference of APHA color number of the diisocyanate product before and after freezing crystallization and remelting is 2 #.
Example 6
A method of stabilizing the color number of a diisocyanate product comprising the steps of:
(1) preparing a closed galvanized barrel (the volume is 210L) filled with a toluene diisocyanate TDI-80 industrial product, and detecting that the APHA color number of the TDI-80 industrial product is 8 #;
(2) preparing a mixture of 4, 4' -bis (phenylisopropyl) diphenylamine and bis (1,2,2,6, 6-pentamethyl-4-piperidyl) sebacate, wherein the mass ratio of the two in the mixture is 1:1, and stirring and mixing the mixture for 30 minutes at the rotating speed of 200 revolutions per minute to prepare the functional color reducing agent. The viscosity of the obtained functional color reducing agent was 1027 pas (at 25 ℃).
(3) Adding the prepared functional color reducing agent into a prepared closed galvanized barrel filled with a toluene diisocyanate TDI-80 industrial product, wherein the addition amount of the functional color reducing agent is 0.08 percent of the mass of TDI-80; after shaking up with a bucket shaker, it was stored in a freezer at 5 ℃ for 3.0 months.
Then opening the closed galvanized barrel, observing the color of TDI-80 in a crystalline state, and observing that the barrel core presents a snow-white appearance; melting the product in the barrel in 70 deg.C water bath to obtain liquid TDI-80, which is colorless and transparent, and has APHA color number of 10 #.
The difference of APHA color number of the diisocyanate product before and after freezing crystallization and remelting is 2 #.
Example 7
A method of stabilizing the color number of a diisocyanate product comprising the steps of:
(1) preparing a closed galvanized barrel (the volume is 210L) filled with a diphenylmethane diisocyanate MDI-50 industrial product, wherein the APHA color number of the MDI-50 industrial product is No. 6 through detection;
(2) preparing a mixture of 4, 4' -bis- (2,3, 3-trimethyl-1-butenyl) diphenylamine and bis (1,2,2,6, 6-pentamethyl-4-piperidyl) sebacate, wherein the mass ratio of the two in the mixture is 5:1, and stirring and mixing the mixture for 30 minutes at the rotating speed of 200 revolutions per minute to prepare the functional color reducing agent. The viscosity of the obtained functional toner was 1287 pas (at 25 ℃).
(3) Adding the prepared functional color reducing agent into a prepared closed galvanized barrel filled with a diphenylmethane diisocyanate MDI-50 industrial product, wherein the addition amount of the functional color reducing agent is 0.01 percent of the mass of MDI-50; after shaking up with a bucket shaker, it was stored in a freezer at 5 ℃ for 6.0 months.
Then opening the closed galvanized barrel, observing the color of MDI-50 in a crystalline state, and observing that the barrel core presents a snow-white appearance; melting the product in the barrel in 70 deg.C water bath to obtain liquid MDI-50, which is colorless and transparent, and has APHA color number of 9# by detection.
The difference of APHA color number of the diisocyanate product before and after freezing crystallization and remelting is 3 #.
Example 8
A method of stabilizing the color number of a diisocyanate product comprising the steps of:
(1) preparing a closed galvanized barrel (the volume is 210L) filled with a diphenylmethane diisocyanate MDI-50 industrial product, wherein the APHA color number of the MDI-50 industrial product is 5# through detection;
(2) preparing a mixture of 4,4 '-bis (phenylisopropyl) diphenylamine and N, N' -bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine, wherein the mass ratio of the two in the mixture is 1:1, and stirring and mixing the mixture for 30 minutes at the rotating speed of 200 revolutions per minute to prepare the functional color reducing agent. The viscosity of the obtained functional toner was 1314 Pa.s (at 25 ℃).
(3) Adding the prepared functional color reducing agent into a prepared closed galvanized barrel filled with a diphenylmethane diisocyanate MDI-50 industrial product, wherein the addition amount of the functional color reducing agent is 0.20 percent of the mass of MDI-50; after shaking up with a bucket shaker, it was stored in a freezer at 5 ℃ for 3.0 months.
Then opening the closed galvanized barrel, observing the color of MDI-50 in a crystalline state, and observing that the barrel core presents a snow-white appearance; melting the product in the barrel in 70 deg.C water bath to obtain liquid MDI-50, which is colorless and transparent, and has APHA color number of 8# by detection.
The difference of APHA color number of the diisocyanate product before and after freezing crystallization and remelting is 3 #.
Comparative example 1
The process for stabilizing the color number of the diisocyanate product refers to the procedure in example 1, except that:
preparing a closed galvanizing barrel filled with a toluene diisocyanate TDI-80 industrial product, wherein the APHA color number of the TDI-80 industrial product is 10# through detection;
the step (2) of preparing the functional color reducing agent is not needed, and the functional color reducing agent is not added into a closed galvanized barrel filled with toluene diisocyanate TDI-80 industrial products.
In the step (3), the closed galvanized barrel filled with the toluene diisocyanate TDI-80 industrial product is placed in a refrigeration house at the temperature of-18 ℃ for storage for 1 month.
Then opening a closed galvanized barrel, observing the color of TDI-80 in a crystalline state, and finding that the solid barrel core is yellow green; dissolving in 70 deg.C water bath to obtain liquid TDI-80 with yellow-green color, and detecting to obtain liquid TDI-80 with APHA color number of 30 #.
The difference of APHA color number of the diisocyanate product before and after freezing crystallization and remelting is 20 #.
Comparative example 2
The process for stabilizing the color number of the diisocyanate product refers to the procedure in example 3, except that:
preparing a closed galvanized barrel filled with a diphenylmethane diisocyanate (MDI-50) industrial product, wherein the APHA color number of the MDI-50 industrial product is 10# through detection;
the step (2) of preparing the functional color reducing agent is not needed, and the functional color reducing agent is not added into a closed galvanized barrel which is well filled with diphenylmethane diisocyanate MDI-50 industrial products.
In the step (3), the closed galvanized barrel filled with the industrial product MDI-50 of diphenylmethane diisocyanate is placed in a refrigeration house at the temperature of minus 10 ℃ for storage for 1.0 month.
Then opening the closed galvanized barrel, observing the color of MDI-50 in a crystalline state, and observing that the solid barrel core is yellow green; dissolving in 70 deg.C water bath to obtain liquid MDI-50 with yellow-green color and APHA color number of 30# by detection.
The difference of APHA color number of the diisocyanate product before and after freezing crystallization and remelting is 20 #.
Comparative example 3
The process for stabilizing the color number of the diisocyanate product refers to the procedure in example 1, except that:
the following 4 functional color reducing agents are prepared in the step (2): the functional color reducing agent a is 4,4 ' -bis- (2,3, 3-trimethyl-1-butenyl) diphenylamine, the functional color reducing agent b is 4,4 ' -bis (phenylisopropyl) diphenylamine, the functional color reducing agent c is bis (1,2,2,6, 6-pentamethyl-4-piperidyl) sebacate, and the functional color reducing agent d is N, N ' -bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine.
And (3) respectively adding 4 functional color reducing agents into 4 prepared closed galvanized barrels filled with toluene diisocyanate TDI-80 industrial products, wherein the addition amount of the 4 functional color reducing agents is 0.0300% of the mass of TDI-80. After shaking up with a bucket shaker, it was stored in a freezer at-18 ℃ for 1 month.
Then opening the closed galvanizing barrel, observing the TDI-80 color of the crystalline state, and observing that the products at 4 barrel cores are all in yellow green; respectively melting the products in 4 barrels in a water bath at 70 ℃ to obtain liquid TDI-80, wherein the products in 4 barrels are yellow green, and the APHA color numbers of the products in 4 barrels are respectively 21#, 23#, 27# and 25# through detection.
The APHA color number difference values of diisocyanate products in 4 barrels are respectively 14#, 16#, 20# and 18# in sequence before and after freezing crystallization and remelting.
Comparative example 4
The process for stabilizing the color number of the diisocyanate product refers to the procedure in example 1, except that:
preparing a mixture of 4, 4' -bis- (2,3, 3-trimethyl-1-butenyl) diphenylamine and bis (1,2,2,6, 6-pentamethyl-4-piperidyl) sebacate, wherein the mass ratio of the two in the mixture is 2: 1; stirring and mixing for 30 minutes at the rotating speed of 200 revolutions per minute to prepare the functional color reducing agent. The viscosity of the obtained functional toner was 2427Pa · s (at 25 ℃).
In the step (3), the addition amount of the functional color reducing agent is 0.0005% by mass of TDI-80. After shaking up by using a bucket shaker, the mixture is stored in a refrigeration house at the temperature of 18 ℃ below zero for 2 months.
Then opening the closed galvanizing barrel, observing the color of TDI-80 in a crystalline state, and observing that a product at the barrel core is yellow-green; dissolving in 70 deg.C water bath to obtain liquid TDI-80 with yellow-green color, and detecting to obtain liquid TDI-80 with APHA color number of 29 #.
The difference of APHA color number of the diisocyanate product before and after freezing crystallization and remelting is 22 #.
Comparative example 5
The process for stabilizing the color number of the diisocyanate product refers to the procedure in example 2, except that:
and (2) preparing a mixture of 4,4 '-bis (phenylisopropyl) diphenylamine and N, N' -bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexamethylenediamine, wherein the mass ratio of the two in the mixture is 0.5:1, and mixing for 30 minutes at the rotating speed of 200 revolutions per minute to prepare the functional color reducing agent. The viscosity of the obtained functional toner was 2569 pas (at 25 ℃).
In the step (3), the addition amount of the functional color reducing agent is 0.02 percent of the mass of MDI-50. After shaking up with a bucket shaker, it was stored in a freezer at-18 ℃ for 1 month.
Then opening the closed galvanizing barrel, observing the color of TDI-80 in a crystalline state, and observing that a product at the barrel core is light yellow green; after being dissolved in a water bath at 70 ℃, the liquid TDI-80 is light yellow green, and the APHA color number of the liquid TDI-80 is detected to be 19 #.
The difference of APHA color number of the diisocyanate product before and after freezing crystallization and remelting is 14 #.
Comparative example 6
The process for preparing a low color number diisocyanate product is as in example 2, except that:
and (2) preparing a mixture of 4,4 '-bis (phenylisopropyl) diphenylamine and N, N' -bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexamethylenediamine, wherein the mass ratio of the two in the mixture is 0.5:1, and mixing for 30 minutes at the rotating speed of 200 revolutions per minute to prepare the functional color reducing agent. The viscosity of the obtained functional toner was 2569 pas (at 25 ℃).
The amount of the functional color reducing agent added in the step (3) was 0.0005% by mass of TDI-80. Shaking with a bucket shaker, and storing in a freezer at-18 deg.C for 3 months.
Then opening the closed galvanizing barrel, observing the TDI-80 color of the crystalline state, and observing that the product at the barrel core is obviously yellow-green; after being dissolved in a water bath at 70 ℃, the liquid TDI-80 presents obvious yellow-green color and is detected to have an APHA color number of 35 #.
The difference of APHA color number of the diisocyanate product before and after freezing crystallization and remelting is 30 #.
The test data of the examples and the comparative examples show that:
according to the invention, through reasonably controlling the mass ratio of the component (a) to the component (b) in the functional color reducing agent and the addition amount of the functional color reducing agent and the synergistic effect of the two factors, the problems that the color number of a frozen and crystallized diisocyanate product is obviously increased and is yellowish green after being re-melted at the temperature of-30 ℃ to 5 ℃ can be solved, and finally the color number of the melted diisocyanate product is stable.
The mass ratio of the component (a) to the component (b) affects the viscosity of the obtained functional type color reducing agent to some extent, for example, in comparative examples 5 to 6, when the mass ratio of the two components is out of the range of 1:1 to 5:1, the viscosity is greatly increased, increasing the difficulty of the operation process.
The mass ratio of the component (a) to the component (b) needs to be more than or equal to 1:1, and the color reducing effect of the functional color reducing agent can be exerted. If the mass of component (a) is smaller than that of component (b), as shown in comparative example 5, the color stabilizing effect on diisocyanate is not good even if the addition amount of the functional color reducing agent is within the required range.
The addition amount of the functional color reducing agent also affects the storage color stability to diisocyanate, and as shown in comparative example 4, even if the ratio of the mass of component (a) to the mass of component (b) is within the required range, the addition amount of the functional color reducing agent is insufficient and the color stabilizing effect to diisocyanate is not good.
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.
Claims (32)
1. A method for stabilizing the color number of a diisocyanate product is characterized in that diisocyanate and a functional color reducing agent are mixed, and then are frozen, crystallized and re-dissolved to form liquid, so that the diisocyanate product with stable APHA color number is obtained; based on the weight of the diisocyanate, the addition amount of the functional color reducing agent is 0.001-0.2 wt% of the weight of the diisocyanate;
the functional color reducing agent comprises the following components:
(a) a hindered amine-type substance, wherein the hindered amine-type substance,
(b) hindered phenolic and/or ester species;
wherein the molecular structure of the hindered amine substance is shown as the formula (I):
R2—NH—R1，(I)
in the formula, R1And R2The structural groups are shown in the following formulas (i) to (v);
the molecular structure of the hindered phenolic substance is shown as the formula (II):
R4—HN—(CH2)n—NH—R3，(II)
in the formula, R3And R4The structural groups are shown in the following formulas (vi) to (vii); n is a positive integer and takes the value of 1-8;
in the formulas (vi) to (vii), k is a natural number and takes a value of 0 to 4;
the molecular structure of the ester substance is shown as the formula (III):
in the formula, R5And R6The structural groups are the same and are respectively and independently selected from the structural groups shown in the formulas (viii) to (ix); n is a positive integer and takes the value of 1-8;
in the formulas (viii) to (ix), k is a natural number and takes a value of 0 to 2;
the mass ratio of the component (a) to the component (b) is 1:1-5: 1.
2. The process according to claim 1, wherein the mass ratio of component (a) to component (b) is from 1:1 to 3: 1.
3. The process according to claim 2, wherein the mass ratio of component (a) to component (b) is 2: 1.
4. The method according to claim 1, wherein the functional color-reducing agent is in a liquid state at normal temperature, and has a viscosity of 500-2000 mPa-s at 25 ℃.
5. The method according to claim 4, wherein the functional color reducing agent is in a liquid state at normal temperature, and has a viscosity of 1000-1500 mPa-s at 25 ℃.
6. The method according to claim 5, wherein the functional color-reducing agent is in a liquid state at normal temperature, and has a viscosity of 1200 mPa-s at 25 ℃.
7. The method according to claim 1, wherein in the formula (I), R is1And R2The same is the structural group shown in the formula (iv).
8. The method according to claim 1, wherein the hindered amine-based substance is selected from one or more of 4,4 '-bis- (2,3, 3-trimethyl-1-butenyl) diphenylamine, 4' -bis (phenylisopropyl) diphenylamine, 4 '-di-tert-butyldiphenylamine and 4, 4' -di-sec-butyldiphenylamine.
9. The method according to claim 8, wherein the hindered amine species is selected from 4,4 '-bis- (2,3, 3-trimethyl-1-butenyl) diphenylamine and/or 4, 4' -bis (phenylisopropyl) diphenylamine.
10. The method of claim 1, wherein in formula (II), n has a value of 4 to 8;
in the formulae (vi) to (vii), k is 1 to 3.
11. The method of claim 10, wherein n has a value of 6 in formula (II).
12. The method of claim 10, wherein k has a value of 2 in formulas (vi) to (vii).
13. The method according to claim 1, wherein in the formula (II), R3And R4The structural group is represented by the formula (vi).
14. The method of claim 1, wherein the hindered phenolic is selected from the group consisting of N, N ' -bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) butanediamine, N ' -bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) pentanediamine, N ' -bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine, N ' -bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) heptanediamine, N ' -bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) octanediamine, and mixtures thereof, One or more of N, N '-bis- (2- (3, 5-di-tert-butyl-4-hydroxyphenyl) acetyl) hexanediamine and N, N' -bis- (4- (3, 5-di-tert-butyl-4-hydroxyphenyl) butyryl) hexanediamine.
15. The method of claim 14, wherein the hindered phenolic is N, N' -bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propanoyl) hexanediamine.
16. The process of claim 1, wherein in formula (III), n has a value of 4 to 8;
in the formulae (viii) to (ix), k is 0 to 1.
17. The method of claim 16, wherein in formula (III), n has a value of 8.
18. The method of claim 16, wherein k has a value of 0 in formulae (viii) to (ix).
19. The process according to claim 1, wherein in the formula (III), R5And R6The same is the structural group shown in the formula (viii).
20. The method of claim 1 wherein the ester is selected from one or more of bis (1,2,2,6, 6-pentamethyl-4-piperidinyl) adipate, bis (1,2,2,6, 6-pentamethyl-4-piperidinyl) pimelate, bis (1,2,2,6, 6-pentamethyl-4-piperidinyl) suberate, bis (1,2,2,6, 6-pentamethyl-4-piperidinyl) azelate, bis (1,2,2,6, 6-pentamethyl-4-piperidinyl) sebacate, and bis (1,2,2,6, 6-pentaethyl-4-piperidinyl) sebacate.
21. The method of claim 20, wherein the ester is bis (1,2,2,6, 6-pentamethyl-4-piperidinyl) sebacate.
22. The method according to claim 1, wherein the functional color reducing agent is added in an amount of 0.01 wt% to 0.08 wt% based on the weight of the diisocyanate.
23. The method of claim 22, wherein the functional color reducing agent is added in an amount of 0.02 wt% to 0.04 wt% based on the weight of the diisocyanate.
24. A method according to any one of claims 1 to 23, wherein the diisocyanate is selected from one or more of diphenylmethane diisocyanate, toluene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, 1, 5-naphthalene diisocyanate, hexamethylene diisocyanate, p-phenylene diisocyanate and 1, 4-cyclohexane diisocyanate.
25. A method according to claim 24, wherein the diisocyanate is selected from diphenylmethane diisocyanate and/or toluene diisocyanate.
26. The method of claim 25, wherein the diisocyanate is diphenylmethane diisocyanate.
27. The method of claim 24, wherein the toluene diisocyanate has a 2, 4-isomer content of 65 to 99.5 wt.%, based on the total weight of the toluene diisocyanate; and/or
The content of 4, 4-isomer in the diphenylmethane diisocyanate is 10-99.5 wt% based on the total weight of the diphenylmethane diisocyanate.
28. The method of claim 27, wherein the toluene diisocyanate has a 2, 4-isomer content of 79 to 81 weight percent, based on the total weight of the toluene diisocyanate; and/or
The content of 4, 4-isomer in the diphenylmethane diisocyanate is 44.5-49 wt% based on the total weight of the diphenylmethane diisocyanate.
29. The method of any one of claims 1-23, 25-28, wherein the temperature of the freeze crystallization is from-30 ℃ to 5 ℃; the temperature of the re-melting is 60-80 ℃.
30. The method of claim 29, wherein the temperature of the freezing crystallization is from-18 ℃ to-10 ℃; the temperature of the re-melting is 70-75 ℃.
31. The method according to any one of claims 1 to 23, 25 to 28 and 30, wherein the difference in APHA color number between the diisocyanate before and after the freezing crystallization and the remelting treatment is 3 #.
32. The method of claim 31, wherein the difference in APHA color numbers of the diisocyanates before and after the freezing crystallization and remelting treatments is no greater than # 1.
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