CN112430295B - Dechlorinating agent, preparation method thereof and application of dechlorinating agent in reducing chlorine content and chromaticity of isocyanate - Google Patents
Dechlorinating agent, preparation method thereof and application of dechlorinating agent in reducing chlorine content and chromaticity of isocyanate Download PDFInfo
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Abstract
The invention provides a dechlorinating agent and application thereof in reducing chlorine content and chromaticity in isocyanate, belonging to the field of isocyanate manufacture. The dechlorinating agent is prepared by taking nano silicon dioxide as a substrate and carrying out graft copolymerization modification on the surface of the silicon dioxide by using vinylpyridine and 9-octadecylamine containing basic functional groups and a silane coupling agent, wherein the functional groups are pyridyl and amido. The dechlorinating agent is filled in a fixed bed adsorption tower to treat crude isocyanate, and through the action of chemical dissociation and physical adsorption, the chlorine content of crude MDI or crude TDI can be obviously reduced, and the chromaticity is obviously improved.
Description
Technical Field
The invention belongs to the field of isocyanate, and particularly relates to a dechlorinating agent, a preparation method thereof and application of the dechlorinating agent in reducing the chlorine content and chromaticity of isocyanate.
Background
MDI (diphenylmethane diisocyanate or polyphenyl methane polyisocyanate) is an isocyanate with wide application and is an important raw material for preparing polyurethane materials. At present, MDI is mainly prepared at home and abroad by a phosgene method. The process for producing MDI by the phosgene method comprises the following steps: aniline and formaldehyde are subjected to condensation reaction under the catalytic action of an acid catalyst to generate a mixture of diphenylmethylene diamine and polyphenyl polymethylene polyamine, which is called crude MDA, the crude MDA is mixed with an inert solvent and then is subjected to phosgenation reaction with phosgene to obtain photochemical reaction liquid, the photochemical reaction liquid is subjected to phosgene removal and solvent removal to obtain an isocyanate crude product, which is called crude MDI, the crude MDI is a mixture of bicyclic and polycyclic isocyanates, and the crude MDI is required to be separated and refined to obtain diphenylmethane diisocyanate (pure MDI) and polyphenyl polymethylene Polyisocyanate (PMDI).
A large amount of chlorine-containing by-products are formed during the phosgenation, which leads to high levels of hydrolysable chlorine in the crude MDI and to a darker color. The hydrolytic chlorine comprises two parts, namely free hydrogen chloride and hydrolysable acyl chloride substances, which cannot be completely removed in the subsequent separation and refining processes and are further retained in the product, so that the hydrolytic chlorine of the product is increased, and the chlorine-containing impurities are colored, so that the product has dark chroma.
The hydrolytic chlorine in pure MDI and PMDI products affects the reactivity of the product during downstream isocyanate application, while color intensity darkens the polyurethane product, both of which are undesirable results to the customer and affect the customer experience and downstream product quality.
In addition to MDI, other isocyanates prepared by phosgene methods also have the problem that hydrolytic chlorine has a high influence on downstream reactivity, such as Toluene Diisocyanate (TDI), xylylene diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate and the like.
The technologies disclosed at home and abroad mainly comprise the following technologies for reducing the chlorine content and the chromaticity in isocyanate products:
patent CN 1148056a describes that after the phosgenation is completed, the chlorine content and color of the isocyanate can be reduced by adding a certain amount of water, or a mixture of mono-or polyhydroxy polyoxyalkylene alcohols, and then removing the excess phosgene.
Patent US-A-2885420 describes that the coloration of polyisocyanates can be reduced by adding from 0.01 to 0.5% by weight, based on the weight of the isocyanate, of aromatic, cyclic aliphatic, or aliphatic ethers or thioethers.
Patent EP0561225 describes the hydrogen treatment of phosgenated isocyanates at pressures of from 1 to 150bar at 100 ℃ and 180 ℃ to give improved color and reduced free chlorine in the end product.
Patent EP0866057 describes that the isocyanate color of the end product can be lightened by treatment with a solid substance of a Lewis acid or a Bronsted acid prior to phosgenation of the diamine or polyamine.
Patent EP0446781 provides a process for pretreating amines with hydrogen before phosgenation of the amine to obtain a light-colored MDI with a low acid number.
Patent US6900348 relates to a process for preparing light-colored isocyanates by reacting diamines or polyamines with phosgene which contains less than 50ppm of bromine in molecularly bound form or other mixtures.
The above methods have a certain effect on reducing the chlorine content and color of isocyanate, but have certain limitations, on one hand, chlorine-containing impurities are mostly generated from side reactions in the phosgenation process, so that the effect of the method for treating raw materials of amines or phosgene is limited, on the other hand, the method of adding water or other organic matters into reaction liquid or isocyanate can irreversibly increase impurities in products, so that the purity and NCO content are influenced, and in addition, the corrosion of equipment is aggravated by adding water.
Disclosure of Invention
Aiming at the problems that the prior isocyanate dechlorination method mainly aims at processing raw materials for phosgene reaction and new impurities are added in the dechlorination process, the invention aims to provide a novel dechlorination agent for reducing the chlorine content and the chromaticity of isocyanate products, the dechlorination agent is directly used for processing the isocyanate products, and simultaneously, the novel impurities are not introduced, and the content and the chromaticity of hydrolysis chlorine in isocyanate can be obviously reduced.
In order to achieve the purpose and achieve the technical effect, the invention adopts the following technical scheme:
a dechlorinating agent for reducing the chlorine content of isocyanate, which grafts an organic monomer with a basic functional group on nanosilicon dioxide, wherein the basic functional group comprises an amine group and/or a pyridine group.
The dechlorinating agent takes nano silicon dioxide as a substrate, and organic monomers containing specific basic functional groups are subjected to grafting modification, so that the dechlorinating agent has the functions of adsorbing and chemically dissociating hydrogen chloride and acyl chloride. The modification method comprises the steps of firstly, carrying out pre-modification on the nano silicon dioxide by using a silane coupling agent containing double bonds, and then carrying out graft copolymerization on an organic monomer containing functional groups such as amino groups, pyridyl groups and the like and the pre-modified nano silicon dioxide to obtain the final dechlorinating agent.
In the invention, the organic monomer is vinyl pyridine and/or 9-octadecenamine, and when the organic monomer and the organic monomer contain the vinyl pyridine and/or the 9-octadecenamine, the molar ratio of the vinyl pyridine to the 9-octadecenamine is 1 (0.25-4).
In the invention, the grafting rate of organic monomer grafting modification in the dechlorinating agent is 10-40% based on the total mass of the dechlorinating agent.
Another object of the present invention is to provide a process for producing the above dechlorinating agent.
A preparation method of a dechlorinating agent comprises the following steps:
a. hydrolysis of the silane coupling agent: mixing alcohol, acid and water, and adding a silane coupling agent for hydrolysis;
b. nano SiO 2 Pre-modification: b, adding nano silicon dioxide into the hydrolysis solution obtained in the step a, stirring for reaction, centrifugally separating a reaction product, washing and drying to obtain pre-modified silicon dioxide;
c. graft copolymerization: dispersing the pre-modified silicon dioxide in a solvent, adding an organic monomer with an alkaline functional group, adding an initiator to initiate polymerization, and centrifugally separating, washing and drying a product to obtain the dechlorinating agent.
In the invention, in step a, the alcohol is absolute methanol and/or absolute ethanol, preferably absolute ethanol, and the acid is one or more of formic acid, acetic acid and oxalic acid; the molar ratio of the alcohol to the acid to the water is 100: (1-5): (1-10); the silane coupling agent is one or more of vinyl trimethoxy silane, vinyl triethoxy silane, vinyl tri (2-methoxyethoxy) silane and gamma-methacryloxypropyl trimethoxy silane; the molar ratio of the silane coupling agent to water is 1: (1-3); the hydrolysis temperature is 30 ℃, and the hydrolysis time is 1 h.
In the invention, in the step b, the molar ratio of the nano silica to the silane coupling agent is 1: (1-6); the size of the nano silicon dioxide is 30nm-100 nm; the reaction temperature is 50-90 ℃, and the reaction time is 2-5 h; the product was isolated by washing with ethanol.
In the invention, in the step c, the mass ratio of the total mass of the organic monomers of the vinylpyridine and/or the 9-octadecenylamine to the pre-modified silicon dioxide is (4-10): 1; the initiator is one or more of azodiisobutyronitrile, benzoyl peroxide, ammonium persulfate and potassium persulfate, and the addition amount of the initiator is 0.1-2% of the total mass of the organic monomer; the reaction temperature is 60-90 ℃, and the reaction time is 2-5 h; the solvent is ethanol.
Still another object of the present invention is to provide use of the above dechlorination agent and the dechlorination agent prepared by the above preparation method.
Use of a dechlorination agent, which dechlorination agent or a dechlorination agent prepared by the method, for reducing the chlorine content and the color of isocyanate.
In the invention, the isocyanate is one or more of diphenylmethane diisocyanate (MDI), Toluene Diisocyanate (TDI), xylylene diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate and isophorone diisocyanate, and is preferably diphenylmethane diisocyanate (MDI) and/or Toluene Diisocyanate (TDI); the isocyanate is a crude product or a treated product.
In the invention, the application mode of the dechlorinating agent is as follows: conveying isocyanate to a preheater through a pump, preheating to a certain temperature, and then passing through a fixed bed adsorption tower filled with a dechlorinating agent to obtain the isocyanate with low chlorine content and low chroma from an outlet of the tower. The isocyanate is fed from the bottom of the adsorption tower and discharged from the top.
In the invention, the preheating temperature of the isocyanate is 50-150 ℃, and the retention time of the isocyanate in the adsorption tower is 5-70min, preferably 20-30 min.
The invention has the following positive effects:
(1) the dechlorinating agent can adsorb chlorine in the form of HCl in isocyanate, and more importantly can chemically adsorb chlorine in the form of acyl chloride. After the dechlorinating agent is used for treatment, the hydrolysis chlorine of crude MDI can be reduced to 141ppm, the L color can be improved to 80, and the hydrolysis chlorine of TDI can be reduced to 9 ppm.
(2) When the dechlorinating agent is used, the dechlorinating agent is filled in a fixed bed adsorption tower, so that new impurities cannot be introduced into isocyanate, and the dechlorinating agent is convenient to replace.
Drawings
FIG. 1 is a schematic diagram of the internal components of a dechlorination agent adsorption tower, wherein a is a grating plate, b is a perforated plate, c is an alumina ceramic ball, d is a screen, e is a dechlorination agent;
FIG. 2 is a schematic diagram of a dechlorination process.
Detailed Description
So that the manner in which the features and aspects of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings, but it should be understood that the drawings illustrate only typical embodiments of the invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
The following examples and comparative examples refer to the starting materials:
| name(s) | Specification of | Manufacturer of the product |
| Nano silicon dioxide | 30-100nm, analytically pure | SHANGHAI JINGCHUN SCIENTIFICAL Co.,Ltd. |
| Vinyl triethoxy silane | Analytical purity | Wuda Silicone New materials Ltd |
| Vinyl tris (2-methoxyethoxy) silane | Analytical purity | Wuda Silicone New materials Ltd |
| Vinyl pyridine | Chemical purity | Baishun Biotech, Inc. of Shanghai |
| 9-octadecenylamine | Industrial grade | Xiangtan Jia leaf source biotechnology limited |
| Anhydrous ethanol | Analytical purity | SINOPHARM CHEMICAL REAGENT Co.,Ltd. |
| Acetic acid | Analytical purity | SINOPHARM CHEMICAL REAGENT Co.,Ltd. |
| Formic acid | Analytical purity | SINOPHARM CHEMICAL REAGENT Co.,Ltd. |
| Dechlorinating agent D | Industrial purity | Shanghai Yichen chemical materials Co Ltd |
| Crude MDI, TDI | Industrial grade | Wanhua chemistry |
The test instrument and the characterization method comprise the following steps:
and (3) infrared spectrum characterization: a Fourier transform infrared spectrometer, a Bruker company, Germany, with the model number Tensor27, mixes and grinds a measurement sample and KBr, tabletting, and analyzing in a transmission mode;
and (3) measuring the grafting ratio: the thermogravimetric differential thermal comprehensive thermal analyzer (TG/DTA) is a model SDTQ600 manufactured by TA of America, and the test method is N 2 The grafting rate of the organic monomer on the surface of the silicon dioxide is defined by taking the weight loss mass in the range of 150-700 ℃ to the total mass of the test sample at the temperature of between room temperature and 700 ℃ at the temperature rising speed of 10 ℃/min.
And (3) determination of hydrolysis chlorine: national standard GB/T12009.2 determination of aromatic isocyanate hydrolytic chlorine for plastic polyurethane production
L color determination: x-rite integrating sphere spectrophotometer, model Color-Eye 7000A, the instrumental measurement conditions are, light source: d15/10 °, spectrum: SPIN, color filter: open, measurement type: transmittance, color expression is expressed in terms of the GB/T5698 color terminology. Higher test values indicate lighter colors, better index values.
Example 1
(1) Hydrolysis of the silane coupling agent: adding 474g of ethanol, 14.2g of formic acid and 9.3g of deionized water into a 1000ml three-neck flask, uniformly mixing, adding 49g of vinyltriethoxysilane, and hydrolyzing for 1h at 30 ℃ under stirring;
(2) nano SiO 2 Pre-modification: adding 4.4g of nano silicon dioxide with the size of 50nm into the hydrolysis solution obtained in the step (1), controlling the temperature to be 60 ℃ under the stirring state, reacting for 3h, and centrifugally separating the reaction product (rotating speed of a centrifugal machine)4000rpm), washing the separated solid with ethanol for three times, and drying in a vacuum drying oven at the pressure of 10kPaa and the temperature of 30 ℃ for 8 hours to obtain pre-modified silicon dioxide;
(3) graft copolymerization: adding 6.84g of vinylpyridine and 17.5g of 9-octadecenylamine into 300ml of ethanol, stirring for dissolving, taking 4g of pre-modified silicon dioxide, uniformly dispersing in the ethanol, introducing nitrogen for replacement for 0.5h under stirring, adding 0.24g of initiator azobisisobutyronitrile, reacting for 4h at 90 ℃, centrifugally separating a reaction product (the rotation speed of a centrifugal machine is 4000rpm), washing the separated solid for three times by the ethanol, and drying in a vacuum drying oven at the pressure of 10kPaa and the temperature of 30 ℃ for 8h to obtain the final dechlorinating agent.
The obtained dechlorinating agent is subjected to infrared spectrum analysis at 2925cm -1 And 2854cm -1 The asymmetric and symmetric stretching vibration absorption peak of methylene in octadecenylamine appears at 3420cm -1 The expansion vibration absorption peak of amino appears at 1556cm -1 And 1600cm -1 The pyridine ring is a stretching vibration absorption peak of C ═ N in the pyridine ring, and the appearance of the characteristic peak indicates that the functional group is successfully grafted on the surface of the silicon dioxide. The measured graft ratio of the dechlorinating agent prepared above was 39%.
Example 2
The preparation method of the dechlorinating agent is the same as that of the embodiment 1, except that the reactant proportion of the step (1) is different, the addition amount of formic acid and water is respectively 7.1g and 2.8g, the addition amount of vinyl triethoxysilane is 30g, and the addition amount of silicon dioxide in the step (2) is 2.7 g; the graft ratio of the dechlorinating agent prepared in the above way is determined to be 21%.
Example 3
The preparation method of the dechlorinating agent is the same as that of the embodiment 1, except that the reactant proportion of the step (1) is different, the adding amount of formic acid and water is 23.7g and 18.5g respectively, the adding amount of vinyl triethoxysilane is 65g, and the adding amount of silicon dioxide in the step (2) is 5.9 g; the measured graft ratio of the dechlorinating agent prepared above is 35.1%.
Example 4
The preparation method of the dechlorinating agent is the same as that of the embodiment 1, but the difference is that the reactant proportion and the size of the silicon dioxide in the step (2) are different, the adding amount of the silicon dioxide is 7.7g, and the size of the silicon dioxide is 30 nm; the measured graft ratio of the dechlorinating agent prepared above is 32.6%.
Example 5
The preparation method of the dechlorinating agent is the same as that of the embodiment 1, except that the reactant proportion and the size of the silicon dioxide in the step (2) are different, the adding amount of the silicon dioxide is 2.6g, the size of the silicon dioxide is 100nm, and the measured grafting ratio of the dechlorinating agent is 33%.
Example 6
The preparation method of the dechlorinating agent is the same as that of the embodiment 1, except that the reactant proportion in the step (3) is different, the adding amount of the 9-octadecenylamine is 4.3g, and the adding amount of the pre-modified product is 1.85 g; the graft ratio of the dechlorinating agent prepared in the above way is determined to be 37.6%.
Example 7
The preparation method of the dechlorinating agent is the same as that of the embodiment 1, except that the reactant proportion in the step (3) is different, the addition amount of the 9-octadecenylamine is 61g, and the addition amount of the pre-modified product is 11.3 g; the measured graft ratio of the dechlorinating agent prepared above is 34.3%.
Example 8
The preparation method of the dechlorinating agent is the same as that of the embodiment 1, except that the reactant proportion in the step (3) is different, and the addition amount of the pre-modified product is 2.55 g; the measured graft ratio of the dechlorinating agent is 15 percent;
example 9
The preparation method of the dechlorinating agent is the same as that of the embodiment 1, except that the reactant in the step (3) is in different proportions, and the addition amount of the pre-modified product is 6 g; the measured graft ratio of the dechlorinating agent prepared above was 39.2%.
Example 10
The preparation method of the dechlorinating agent comprises the same steps as example 1, except that in the step (1), the acid is acetic acid, and the silane coupling agent is vinyl tri (2-methoxyethoxy) silane; the measured graft ratio of the dechlorinating agent prepared above is 36%.
Example 11
The preparation method of the dechlorinating agent is the same as the example 1, except that the pre-modification reaction temperature in the step (2) is 50 ℃, the reaction time is 5 hours, and the measured grafting ratio of the dechlorinating agent is 10%.
Example 12
The preparation method of the dechlorinating agent is the same as the step of the embodiment 1, except that the pre-modification reaction temperature in the step (2) is 90 ℃, and the reaction time is 2 hours; the graft ratio of the dechlorinating agent prepared by the method is 32 percent through measurement.
Example 13
The preparation method of the dechlorinating agent is the same as that of the embodiment 1, except that the grafting reaction conditions in the step (3) are different, the temperature is 80 ℃, the reaction time is 3h, the initiator is benzoyl peroxide, and the addition amount of the initiator is 2 percent (0.49g) of the monomer; the measured graft ratio of the dechlorinating agent prepared above is 21.3%.
Example 14
The procedure of the dechlorination agent was the same as that of example 1 except that azobisisobutyronitrile as an initiator was added in an amount of 0.3% (0.07g) based on the monomer at a reaction temperature of 60 ℃; the measured graft ratio of the dechlorinating agent prepared above was 11.2%.
Example 15
The dechlorination agents prepared in the above examples were used to reduce the isocyanate chlorine content and the color, dechlorination agent A was prepared for example 1, dechlorination agent B was prepared for example 5 and dechlorination agent C was prepared for example 10.
Crude MDI was treated with the above dechlorinating agent. The specific operation is as follows: the dechlorination agent prepared in the experiment is filled into a dechlorination agent adsorption tower shown in figure 1, crude MDI is preheated to 120 ℃ by a preheater, and the crude MDI is fed from the bottom of the adsorption tower and discharged from the top. After discharging, the mixture can continuously enter a subsequent separation and refining section to obtain a PMDI product and a pure MDI product. The retention time of the crude MDI in the adsorption tank is controlled by the feeding speed, and the hydrolytic chlorine content and the L color value of the crude isocyanate before and after different dechlorinating agents are treated when the retention time is 30min are shown below.
| Hydrolyzed chlorine/ppm | L color | |
| Crude MDI as such | 520 | 70 |
| Dechlorination agent A treatment | 141 | 80 |
| Dechlorination agent B treatment | 231 | 73 |
| Dechlorination agent C treatment | 155 | 78 |
From the results in the table, the dechlorinating agent prepared by the invention has remarkable effect under the same adsorption temperature and retention time, wherein the dechlorinating agent A has the best effect and can reduce the hydrolytic chlorine of crude MDI from 520ppm to 141ppm and improve the L color from 70 to 80. The large decrease in hydrolysis chlorine indicates that the dechlorinating agent adsorbs not only the chlorine present as HCl but also the chlorine present as acid chloride.
Example 16
The specific embodiment is the same as example 15, except that only dechlorinating agent A is used, the preheating temperature is 50-150 ℃, the retention time is 5-70min, and the implementation effect is as follows.
The following table shows the implementation effect when the preheating temperature is 50-150 ℃ and the retention time is 30 min:
| group of | Preheating temperature | Hydrolyzed chlorine | L color |
| 1 | Crude MDI as such | 520 | 70 |
| 2 | 50℃ | 431 | 72 |
| 3 | 80℃ | 268 | 73 |
| 4 | 120℃ | 141 | 80 |
| 5 | 150℃ | 161 | 78 |
From the above results, it can be seen that at a temperature below 120 ℃, the hydrolysis chlorine decreases with the increase of the preheating temperature, the temperature continues to increase, and the hydrolysis chlorine slightly increases, because the adsorption-desorption process is reversible, the temperature increases, and the desorption proceeds in the reverse reaction direction, and a part of the adsorbed chlorine is desorbed.
The following table shows the implementation effect of the retention time of 5-70min and the preheating temperature of 120 ℃:
| group of | Residence time | Hydrolyzed chlorine/ppm | L color |
| 1 | Crude MDI original shape | 520 | 70 |
| 2 | 5min | 390 | 72 |
| 3 | 10min | 254 | 73 |
| 4 | 30min | 141 | 80 |
| 5 | 50min | 135 | 80 |
| 6 | 70min | 132 | 80 |
From the above results, it can be seen that as the residence time is prolonged, the hydrolysis chlorine is reduced, but the reduction rate is gradually reduced, and the residence time is more suitable within 20-30min by comprehensively considering the production efficiency and the equipment investment.
Example 17
The specific embodiment is the same as example 15, except that TDI is used instead of crude MDI, the preheating temperature is 120 ℃ and the residence time is 30 min.
| Hydrolyzed chlorine/ppm | |
| Crude TDI as received | 19 |
| Dechlorination agent A treatment | 9 |
As can be seen from the results in the table above, the dechlorinating agent A can reduce TDI hydrolytic chlorine from 19ppm to 9ppm, and the effect is obvious. TDI generally does not require chroma.
Comparative example 1
The dechlorination effect of crude MDI was examined by using a common inorganic dechlorinating agent D (see raw material information table) containing magnesium oxide, calcium oxide, magnesium carbonate, calcium carbonate as effective components and white powder. And filling the inorganic dechlorinating agent D into a dechlorinating agent adsorption tower, preheating the crude MDI to a specific temperature by a preheater, feeding from the bottom of the adsorption tower, and discharging from the top. Preheating temperature 120 deg.C, residence time 10min-120min, other process conditions the same as example 15. The following are the test results:
| residence time | Hydrolyzed chlorine/ppm | L color |
| Crude MDI as such | 520 | 70 |
| 10min | 462 | 70 |
| 30min | 375 | 71 |
| 60min | 363 | 71 |
| 120min | 357 | 71 |
This comparative example, compared with examples 15 and 16, can find that the dechlorination effect of the dechlorination agent prepared by the present invention is significantly better than that of the inorganic dechlorination agent D.
Although the present invention has been described in detail by way of examples, the present invention is not limited to the above embodiments. It will be apparent to those skilled in the art that modifications may be made within the scope of the claims and that such modifications or adaptations are intended to be within the scope of the invention as defined in the claims without departing from the spirit and scope of the invention.
Claims (12)
1. Use of a dechlorination agent for reducing the chlorine content and colour of an isocyanate;
the dechlorinating agent grafts an organic monomer with a basic functional group on the nano silicon dioxide, and the basic functional group comprises an amine group and/or a pyridine group.
2. Use of a dechlorinating agent according to claim 1, wherein the organic monomer is vinylpyridine and/or 9-octadecenylamine, and the molar ratio of vinylpyridine to 9-octadecenylamine in the presence of both is 1 (0.25-4).
3. Use of a dechlorination agent according to claim 1 or2, wherein the organic monomer graft modification grafting rate in the dechlorination agent is 10-40% based on the total mass of the dechlorination agent.
4. Use of a dechlorination agent according to claim 1 or2, a process for its preparation comprising the steps of:
a. hydrolysis of the silane coupling agent: mixing alcohol, acid and water, and adding a silane coupling agent for hydrolysis;
b. nano SiO 2 Pre-modification: b, adding nano silicon dioxide into the hydrolysis solution obtained in the step a, stirring for reaction, centrifugally separating a reaction product, washing and drying to obtain pre-modified silicon dioxide;
c. graft copolymerization: dispersing the pre-modified silicon dioxide in a solvent, adding an organic monomer with an alkaline functional group, adding an initiator to initiate polymerization, and centrifugally separating, washing and drying a product to obtain the dechlorinating agent.
5. The use of the dechlorinating agent according to claim 4, wherein in step a, the alcohol is absolute methanol and/or absolute ethanol, and the acid is one or more of formic acid, acetic acid and oxalic acid; the mol ratio of the alcohol to the acid to the water is 100: (1-5): (1-10); the silane coupling agent is one or more of vinyl trimethoxy silane, vinyl triethoxy silane, vinyl tri (2-methoxyethoxy) silane and gamma-methacryloxypropyl trimethoxy silane; the molar ratio of the silane coupling agent to water is 1: (1-3).
6. The use of a dechlorinating agent according to claim 5, wherein in step a, the alcohol is absolute ethanol.
7. Use of a dechlorinating agent according to claim 4, wherein in step b, the molar ratio of nanosilica to silane coupling agent is 1: (1-6); the size of the nano silicon dioxide is 30nm-100 nm; the reaction temperature is 50-90 ℃, and the reaction time is 2-5 h; the product was isolated by washing with ethanol.
8. Use of a dechlorinating agent according to claim 4, wherein in step c, the mass ratio of the total mass of the organic monomers vinylpyridine and/or 9-octadecenylamine to the pre-modified silica is (4-10): 1; the initiator is one or more of azodiisobutyronitrile, benzoyl peroxide, ammonium persulfate and potassium persulfate, and the addition amount of the initiator is 0.1-2% of the total mass of the organic monomer; the reaction temperature is 60-90 ℃, and the reaction time is 2-5 h; the solvent is ethanol.
9. Use of a dechlorinating agent according to claim 1, wherein the isocyanate is one or more of diphenylmethane diisocyanate (MDI), Toluene Diisocyanate (TDI), xylylene diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate and isophorone diisocyanate, and the isocyanate is a crude product or a treated product.
10. Use of a dechlorination agent according to claim 1, said isocyanate being diphenylmethane diisocyanate (MDI) and/or Toluene Diisocyanate (TDI), said isocyanate being a crude or treated product.
11. Use of a dechlorination agent according to claim 1, applied by: conveying isocyanate to a preheater through a pump, preheating to a certain temperature, and then passing through a fixed bed adsorption tower filled with a dechlorinating agent to obtain isocyanate with low chlorine content and low chroma from an outlet of the tower; wherein the preheating temperature of the isocyanate is 50-150 ℃, and the retention time of the isocyanate in the adsorption tower is 5-70 min.
12. Use of a dechlorination agent according to claim 11 in a manner such that the isocyanate remains in the adsorption column for a time of 20 to 30 min.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910787875.3A CN112430295B (en) | 2019-08-26 | 2019-08-26 | Dechlorinating agent, preparation method thereof and application of dechlorinating agent in reducing chlorine content and chromaticity of isocyanate |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910787875.3A CN112430295B (en) | 2019-08-26 | 2019-08-26 | Dechlorinating agent, preparation method thereof and application of dechlorinating agent in reducing chlorine content and chromaticity of isocyanate |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN112430295A CN112430295A (en) | 2021-03-02 |
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