Method for measuring hydroxyl value of hydroxyl-terminated organosilicon
Technical Field
The invention relates to the technical field of hydroxyl content detection. More specifically, the invention relates to a method for measuring the hydroxyl value of hydroxyl-terminated organosilicon.
Background
The hydroxyl-terminated organic silicon compound comprises hydroxyl-terminated silicone oil, hydroxyl-terminated fluorosilicone oil, polyether modified silicone oil and the like, is an extremely important chemical raw material and is widely applied to the fields of textile finishing agents, leather finishing agents, defoaming agents, cosmetics and the like, the average molecular weight of the compound can be obtained by measuring the hydroxyl value of the hydroxyl-terminated organic silicon compound, and the average molecular weight is an important index for producing organic silicon compound modified materials, so that the accurate measurement of the hydroxyl value of the hydroxyl-terminated organic silicon compound has important guiding significance for use manufacturers and manufacturers, the conventional measurement methods for the hydroxyl-terminated organic silicon compound comprise a Karl Fischer method, a Grignard reagent method, a lithium aluminum hydride method, a phenyl isocyanate method and the like, and the methods either need a higher-end test instrument or use a compound with higher toxicity and are difficult to realize for most manufacturers.
Disclosure of Invention
The invention aims to provide a method for measuring the hydroxyl value of hydroxyl-terminated organosilicon, which is used for measuring the hydroxyl value of a hydroxyl-terminated organosilicon compound by a method with low toxicity, more convenience and no dependence on instruments and solves the problems of complex detection process, high cost and high toxicity in the prior art.
To achieve these objects and other advantages in accordance with the present invention, there is provided a method for determining a hydroxyl group-terminated silicone hydroxyl value, comprising subjecting a polyisocyanate having a known content of isocyanate group to a condensation polymerization reaction with a hydroxyl-terminated silicone in the presence of a catalyst, and calculating the hydroxyl group-terminated silicone hydroxyl value by measuring the content of residual isocyanate group;
the catalyst is an organic bismuth catalyst.
Preferably, the hydroxyl-terminated silicone has the following structural formula: HO (R)1R2SiO)nR, wherein R1And R2Identical or different and are H, long chain orShort-chain saturated or unsaturated alkyl radicals, -Si (CH)3)3or-C6H5R is-OH, silicon-containing long-chain alkyl, long-chain or short-chain saturated or unsaturated alkyl and alkoxy.
Preferably, the polyisocyanate is one or more of toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate trimer.
Preferably, the weight ratio of the catalyst, the polyisocyanate and the hydroxyl-terminated organosilicon is 0.1-0.8:100-150: 50-75.
Preferably, the reaction temperature of the polycondensation reaction is 50 to 90 ℃ and the reaction time is 1 to 4 hours.
Preferably, the residual isocyanate group content is determined by the following titration method: adding a quantitative sample m into a three-neck flask, adding 10mL of acetone to dissolve the sample, transferring 10mL of 0.5mol/L di-n-butylamine-acetone solution by using a pipette, sealing a plug of the three-neck flask, fully oscillating, standing for 15min, adding 3 drops of bromocresol green indicator, titrating by using a calibrated 0.1mol/L standard hydrochloric acid solution, determining a titration end point when the solution is changed from blue to yellow, performing a blank test, and determining the content of isocyanate groups in the sample
Wherein m is the sample mass in g, c is the hydrochloric acid concentration in mol/L, V
0Hydrochloric acid volume for blank in mL, V
1The volume of hydrochloric acid used for titrating the sample is in mL.
Preferably, the content of terminal hydroxyl groups
Preferably, the organic bismuth catalyst is one of bismuth isooctanoate, bismuth laurate, bismuth neodecanoate and bismuth naphthenate.
The invention at least comprises the following beneficial effects: the method for determining the hydroxyl value of the hydroxyl-terminated organosilicon utilizes the organic bismuth catalyst, polyisocyanates with known isocyanate group content react with the hydroxyl-terminated organosilicon, the hydroxyl value of the hydroxyl-terminated organosilicon can be obtained by back calculation through determining the residual isocyanate group content, and the used raw materials are safe and nontoxic when determining the residual isocyanate group content, the testing process is simple, convenient and quick, and the obtained hydroxyl value is an effective hydroxyl value because the polycondensation reaction used by the determining method is close to the application occasion of the hydroxyl-terminated organosilicon, thereby having more important practical significance.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.
Detailed Description
The present invention is further described in detail below with reference to examples so that those skilled in the art can practice the invention with reference to the description.
It is to be noted that the experimental methods described in the following embodiments are all conventional methods unless otherwise specified, and the reagents and materials are commercially available unless otherwise specified.
The invention provides a method for measuring hydroxyl value of hydroxyl-terminated organosilicon, which comprises the steps of carrying out polycondensation reaction on polyisocyanate with known content of isocyanate group and hydroxyl-terminated organosilicon under the condition of using a catalyst, and calculating the hydroxyl value of the hydroxyl-terminated organosilicon by measuring the content of residual isocyanate group;
the catalyst is an organic bismuth catalyst.
The determination principle of the invention is as follows: the method comprises the steps of carrying out polycondensation reaction on a fixed amount of isocyanate groups and a small amount of terminal hydroxyl groups, adding one or more catalysts such as bismuth neodecanoate organic bismuth catalysts to ensure that the isocyanate groups and the terminal hydroxyl groups in a system are completely reacted, and then measuring the content of the residual isocyanate groups, so that the amount of isocyanate groups reacted with the terminal hydroxyl groups and the amount of substances consumed during the reaction of the isocyanate groups and the terminal hydroxyl groups are 1:1, and the amount of the terminal hydroxyl groups can be obtained quantitatively, thereby calculating the concentration of the terminal hydroxyl groups.
The hydroxyl value of the hydroxyl-terminated organosilicon is determined by reacting polyisocyanate with known content of isocyanate group with the hydroxyl-terminated organosilicon by using organic bismuth catalysts such as bismuth isooctanoate, bismuth laurate, bismuth neodecanoate, bismuth naphthenate and the like, wherein the organic bismuth catalysts are all environment-friendly catalysts, proper amount is selected for polycondensation reaction under proper reaction conditions, bromocresol green indicator is used and hydrochloric acid is used for titration when the content of residual isocyanate group is determined, the method is safe, non-toxic and simple, convenient and quick in test process.
Example 1:
100g of a hydroxy silicone oil (100 mPa. multidot.s) which had been subjected to vacuum treatment at 100 ℃ and-0.1 MPa for 1 hour were accurately weighed and poured into a three-necked flask, 222.3g of isophorone diisocyanate (the content of isocyanate groups of which X was 37.29% as determined by HG/T2409-92), 0.4g of a bismuth neodecanoate catalyst were added to the three-necked flask, and an inert gas N was introduced thereinto2Reacting at 80 ℃ for 3 hours, after the reaction is finished, taking a quantitative sample m, adding 10mL of acetone to dissolve the sample, transferring 10mL of 0.5mol/L di-n-butylamine-acetone solution by using a pipette, sealing by adding a plug, fully shaking, standing for 15min, then adding 3 drops of bromocresol green indicator, titrating by using a calibrated 0.1mol/L standard hydrochloric acid solution, and taking a titration end point when the solution is changed from blue to yellow, and performing a blank test. The hydroxyl content of the hydroxyl silicone oil (100 mPas) is calculated according to the formula to be 9.72g/100g of the hydroxyl silicone oil.
Example 2:
100g of a hydroxy silicone oil (500 mPa. multidot.s) which had been subjected to vacuum treatment at 100 ℃ and-0.1 MPa for 1 hour was accurately weighed and poured into a three-necked flask, 174.2g of toluene diisocyanate (the content of isocyanate groups therein was determined to be X-47.26% by the method of HG/T2409-92), 0.2g of a bismuth isooctanoate catalyst were added to the three-necked flask, and an inert gas N was introduced thereinto2Reacting at 50 deg.C for 2.5 hr, collecting a quantitative sample m according to HG/T2409-92 standard, adding 10mL acetone to dissolve the sample, and transferring 10mL 0.5m by pipetteAnd (3) adding a plug into an ol/L di-n-butylamine-acetone solution, sealing, fully oscillating, standing for 15min, adding 3 drops of bromocresol green indicator, titrating by using a calibrated 0.1mol/L standard hydrochloric acid solution, and performing a blank test when the solution is changed from blue to yellow. The hydroxyl content of the hydroxyl silicone oil (500 mPas) is calculated according to the formula to be 3.60g/100g of the hydroxyl silicone oil.
Example 3:
accurately weighing 100g of hydroxyphenyl silicone oil (300 mPa.s) which is subjected to vacuum treatment at 100 ℃ and-0.1 MPa for 1 hour, pouring the hydroxyphenyl silicone oil into a three-neck flask, adding 168.2g of hexamethylene diisocyanate (the content of isocyanate groups is determined to be X-49.44 percent according to the method of HG/T2409-92) and 0.4g of bismuth naphthenate catalyst into the three-neck flask, and introducing an inert gas N2Reacting for 3 hours at 80 ℃, after the reaction is finished, taking a quantitative sample m according to HG/T2409-92 standards, adding 10mL of acetone to dissolve the sample, transferring 10mL of 0.5mol/L di-n-butylamine-acetone solution by using a pipette, fully shaking after plugging and sealing, standing for 15min, then adding 3 drops of bromocresol green indicator, titrating by using a calibrated 0.1mol/L standard hydrochloric acid solution, and taking a titration end point when the solution is changed from blue to yellow, and performing a blank test. The hydroxyl content of the hydroxyl silicone oil (300 mPas) is calculated according to a formula and is 3.22g/100g of hydroxyphenyl silicone oil.
Example 4:
100g of hydroxyphenyl silicone oil (100 mPa. multidot.s) which had been subjected to vacuum treatment at 100 ℃ and-0.1 MPa for 1 hour was accurately weighed and poured into a three-necked flask, 168.2g of hexamethylene diisocyanate (the content of isocyanate group therein was determined to be X-49.44% according to HG/T2409-92), 0.4g of bismuth laurate catalyst was added to the three-necked flask, and an inert gas N was introduced thereinto2Reacting for 3 hours at 70 ℃, after the reaction is finished, taking a quantitative sample m according to HG/T2409-92 standards, adding 10mL of acetone to dissolve the sample, transferring 10mL of 0.5mol/L di-n-butylamine-acetone solution by using a pipette, fully shaking after plugging and sealing, standing for 15min, then adding 3 drops of bromocresol green indicator, titrating by using a calibrated 0.1mol/L standard hydrochloric acid solution, and taking a titration end point when the solution is changed from blue to yellow, and performing a blank test. Calculating according to a formula to obtain hydroxylThe hydroxyl group content of the silicone oil (300 mPas) was 9.74g/100g of hydroxyphenyl silicone oil.
Example 5:
100g of hydroxyphenyl silicone oil (300 mPa. multidot.s) which had been subjected to vacuum treatment at 100 ℃ and-0.1 MPa for 1 hour was accurately weighed and poured into a three-necked flask, 174.2g of toluene diisocyanate (the content of isocyanate group in the toluene diisocyanate was determined to be X-47.26% by HG/T2409-92 method) and 0.5g of bismuth naphthenate catalyst were added into the three-necked flask, and an inert gas N was introduced thereinto2Reacting for 2.5 hours at 50 ℃, after the reaction is finished, taking a quantitative sample m according to HG/T2409-92 standards, adding 10mL of acetone to dissolve the sample, transferring 10mL of 0.5mol/L di-n-butylamine-acetone solution by using a pipette, fully shaking after plugging and sealing, standing for 15min, then adding 3 drops of bromocresol green indicator, titrating by using a calibrated 0.1mol/L standard hydrochloric acid solution, and taking a titration end point when the solution is changed from blue to yellow, and performing a blank test. The hydroxyl content of the hydroxyl silicone oil (300 mPas) is calculated according to a formula and is 3.22g/100g of hydroxyphenyl silicone oil.
Comparative example 1:
accurately weighing 100g of hydroxy silicone oil (100 mPa. s) after vacuum treatment at 100 ℃ and-0.1 MPa for 1 hour, pouring into a three-necked flask, adding 250.2g of diphenylmethane diisocyanate (MDI) (the isocyanate group content of which is 33.6% according to HG/T2409-92), 0.4g of bismuth neodecanoate catalyst into the three-necked flask, and introducing an inert gas N2Reacting at 80 ℃ for 3 hours, after the reaction is finished, taking a quantitative sample m, adding 10mL of acetone to dissolve the sample, transferring 10mL of 0.5mol/L di-n-butylamine-acetone solution by using a pipette, sealing by adding a plug, fully shaking, standing for 15min, then adding 3 drops of bromocresol green indicator, titrating by using a calibrated 0.1mol/L standard hydrochloric acid solution, and taking a titration end point when the solution is changed from blue to yellow, and performing a blank test. The hydroxyl content of the hydroxyl silicone oil (100 mPas) is calculated according to the formula to be 9.62g/100g of the hydroxyl silicone oil.
Comparative example 2:
100g of a hydroxy silicone oil (100 mPa. multidot.s) subjected to vacuum treatment at 100 ℃ and-0.1 MPa for 1 hour was accurately weighed and poured into a three-necked flask, and 262.4g of dicyclohexylmethane diisocyanate (H)MDI) (determined according to HG/T2409-92 with an isocyanate group content of 31.8%), 0.4g of bismuth laurate catalyst were added to a three-necked flask and inert gas N was passed through2Reacting at 100 ℃ for 3 hours, after the reaction is finished, taking a quantitative sample m, adding 10mL of acetone to dissolve the sample, transferring 10mL of 0.5mol/L di-n-butylamine-acetone solution by using a pipette, sealing by adding a plug, fully shaking, standing for 15min, then adding 3 drops of bromocresol green indicator, titrating by using a calibrated 0.1mol/L standard hydrochloric acid solution, and taking a titration end point when the solution is changed from blue to yellow, and performing a blank test. The hydroxyl content of the hydroxyl silicone oil (100 mPas) is calculated according to the formula to be 9.60g/100g of the hydroxyl silicone oil.
Comparative example 3:
100g of a hydroxy silicone oil (100 mPa. multidot.s) which had been subjected to vacuum treatment at 100 ℃ and-0.1 MPa for 1 hour were accurately weighed and poured into a three-necked flask, 222.3g of isophorone diisocyanate (which had been determined to have an isocyanate group content of 37.29% according to HG/T2409-92), 0.9g of a bismuth isooctanoate catalyst were charged into the three-necked flask, and an inert gas N was introduced thereinto2Reacting at 80 ℃ for 3 hours, after the reaction is finished, taking a quantitative sample m, adding 10mL of acetone to dissolve the sample, transferring 10mL of 0.5mol/L di-n-butylamine-acetone solution by using a pipette, sealing by adding a plug, fully shaking, standing for 15min, then adding 3 drops of bromocresol green indicator, titrating by using a calibrated 0.1mol/L standard hydrochloric acid solution, and taking a titration end point when the solution is changed from blue to yellow, and performing a blank test. The hydroxyl group content of the hydroxyl silicone oil (100 mPas) was calculated according to the formula to be 9.67g/100g of hydroxyl silicone oil.
Comparative example 4:
100g of a hydroxy silicone oil (100 mPas) which had been subjected to vacuum treatment at 100 ℃ and-0.1 MPa for 1 hour were accurately weighed and poured into a three-necked flask, 222.3g of isoflurone diisocyanate (which had been determined to have an isocyanate group content of X37.29% by the HG/T2409-92 method) and 0.4g of a tetramethylammonium silanol catalyst were added to the three-necked flask, and an inert gas N was introduced thereinto2Reacting at 120 ℃ for 3 hours, after the reaction is finished, taking a quantitative sample m, adding 10mL of acetone to dissolve the sample, transferring 10mL of 0.5mol/L di-n-butylamine-acetone solution by a pipette, and pluggingAnd (3) sufficiently shaking after sealing, standing for 15min, then adding 3 drops of bromocresol green indicator, titrating by using a calibrated 0.1mol/L standard hydrochloric acid solution, and taking a blank test when the solution is changed from blue to yellow. The hydroxyl content of the hydroxyl silicone oil (100 mPas) is calculated according to the formula to be 9.36g/100g of the hydroxyl silicone oil.
The results of the method provided by the invention and the Karl Fischer method are shown in Table 1:
according to the measurement results in table 1, by comparing examples 1 to 5 with comparative examples 1 and 2, the data obtained by the examples using the method of the present invention has high accuracy, the method error is stabilized within 2%, the data are all about 1% and the toxicity of the used reagents is low, the effective hydroxyl value of the terminal hydroxyl group can be measured by using a conventional instrument, and the operation is simple. Comparing example 1 with comparative example 1, it can be seen that the relative error of final measurement using isophorone diisocyanate in comparison with the diphenylmethane diisocyanate used in comparative example 1 is smaller, diphenylmethane diisocyanate (MDI) has a biphenyl ring, the molecular chain length is longer, the rigidity is higher, and the generated steric hindrance is also larger, so that the monomer itself is more difficult to contact with the catalyst to form an intermediate, the isocyanate group reaction is affected sufficiently, and the generated error is larger; compared with the embodiment 1 and the comparative example 2, the HMDI has a long-chain benzene ring rigid structure, the monomer is more difficult to contact with the catalyst to form an intermediate, the temperature required by the reaction is higher, the catalyst activity is required to be in a higher temperature range, the reaction is carried out at a higher temperature, the stability of the raw material is poorer, the stability of a product obtained by the polycondensation reaction is poorer, larger errors are generated in subsequent determination, the molecular chain of the isophorone diisocyanate is shorter, the degree of freedom of the molecule is higher, and the probability of the contact collision between the molecule and the molecule is higher. Comparing comparative example 3 with example 1, the weight ratio of the catalyst, the polyisocyanate and the hydroxyl-terminated organosilicon is 0.1-0.8:100-150:50-75, good measurement results can be obtained, on one hand, the stability of the reaction process is influenced by the excessive amount of the catalyst, and on the other hand, the calculated error caused by the excessive amount of the catalyst is larger, so that the calculated content of the hydroxyl-terminated silicone is larger. The comparative example 4 adopts other catalysts to catalyze the polycondensation reaction of the polyisocyanate and the hydroxyl-terminated organosilicon, which can not play a good catalytic effect for the polycondensation reaction, so that the relative error generated by the determination result is large.
While embodiments of the invention have been described above, it is not limited to the applications set forth in the description and the embodiments, which are fully applicable to various fields of endeavor for which the invention may be embodied with additional modifications as would be readily apparent to those skilled in the art, and the invention is therefore not limited to the details given herein and to the embodiments shown and described without departing from the generic concept as defined by the claims and their equivalents.