JP2003043027A - Method for measuring hydroxyl value - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydroxyl value measurement method capable of easily measuring even a hydroxyl group which is bound to a second carbon atom or a third carbon atom without using any chloride-based organic solvents in the hydroxyl value measurement method by changing the hydroxyl group of a specimen into urethane. SOLUTION: A hydroxyl group which a specimen has is changed into urethane by adding a specific amount of an isocyanate compound so that it is excessive to the hydroxyl group in the presence of a urethane reaction catalysts in a non-chlorine-based solvent, and then unreacted isocyanate group is quantitatively determined to determine the hydroxyl value in the method for measuring the hydroxyl value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a hydroxyl value, and more particularly to a method for measuring a hydroxyl value by quantifying a hydroxyl group by subjecting the hydroxyl group of a sample to urethane.

[0002]

2. Description of the Related Art Conventionally, as a method for measuring a hydroxyl value, a method in which acetic anhydride in pyridine is used to acetylate a hydroxyl group of an analyte has been widely used.
However, depending on the compound, there are problems that gelation occurs during acetylation and that the hydroxyl value cannot be measured by this method when the analyte has an acidic group such as a carboxyl group. In addition, this method requires high temperature of about 100 ° C., has a long reaction time, and has a strong odor of pyridine and acetic anhydride, which is liable to cause deterioration of working environment.

As a method for measuring the hydroxyl value in place of the conventional acetic anhydride-pyridine method, there is a method for measuring the hydroxyl value by urethane-converting the hydroxyl groups of a test sample by Bernd Dreher (FA
RBE UND LACK, Nr. 11, 1961). This was reported as a method for quantifying hydroxyl groups in unsaturated polyester. After reacting the hydroxyl groups of the analyte with an excess of an isocyanate compound in a mixed solvent of chlorobenzene / acetone = 1: 1, unreacted isocyanate It is a hydroxyl value measuring method for quantitatively analyzing a group. It was simpler than the conventional method in that the urethanization reaction could be completed in a short time at room temperature, and the carboxyl group in the chemical structure could be measured at the same time, so that the acid value could be omitted. However, according to this method, the first
The reaction of the hydroxyl group bonded to the carbon atom proceeds relatively quickly, but the urethanization reaction of the hydroxyl group bonded to the second or third carbon atom hardly progresses.
In addition, although chlorobenzene used as a solvent is preferable from the viewpoint of reactivity, it is now recognized that many of such chlorine-containing solvents exhibit mutagenicity,
It is not preferable to use a large amount on a daily basis for product quality control, testing and research, etc., as it may seriously affect the health of workers. In addition, it is obligatory to manage mutagenic chemical substances, create personal work records and keep them for 30 years.
This is not preferable because it is clumsy in terms of business.

[0004]

The problem to be solved by the present invention is to provide a method for measuring a hydroxyl value in which a hydroxyl group of an analyte is urethanized, without using a chlorine-containing organic solvent. It is an object of the present invention to provide a method for measuring a hydroxyl value that allows even a hydroxyl group bonded to a carbon atom to be easily measured.

[0005]

Means for Solving the Problems In the method for measuring a hydroxyl value, the present inventors have determined that the hydroxyl group of a test sample is excessive with respect to the hydroxyl group in a chlorine-free solvent in the presence of a urethane-forming reaction catalyst. The above problem was solved by providing a method for measuring a hydroxyl value by determining a hydroxyl value by quantifying an unreacted isocyanate group after adding a predetermined amount of an isocyanate compound to form a urethane.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The contents of the present invention will be described in more detail below. In the hydroxyl value measurement method of the present invention, so as to be excessive with respect to the hydroxyl group of the analyte, after urethanization by adding a known amount of an isocyanate compound, the unreacted isocyanate group is titrated with an amine solution of known concentration. To quantify the amount of hydroxyl groups. In the present invention, at the time of the urethanization reaction, by using a urethanization reaction catalyst and heating as necessary, the conventional
The hydroxyl group bonded to the second carbon atom or the third carbon atom, which cannot be accurately quantified by the hydroxyl value measuring method for quantifying the hydroxyl group by the urethanization reaction, can also be accurately quantified. Further, even if the subject has an acidic group such as a carboxyl group, the measurement is not hindered.

The amount of the test substance used in the method for measuring the hydroxyl value of the present invention is not particularly limited, but it is preferably in the range of 0.05 to 10 g depending on the hydroxyl value. If the amount of the analyte exceeds 10 g, the amount of the isocyanate compound used and the amount of the titration reagent and the like used will be very large, and the workability and the economical efficiency will be substantially lowered. On the other hand, when the amount is less than 0.05 g, the measurement error becomes large and the measurement accuracy decreases. The reaction temperature for the urethanization is preferably 5 to 100 ° C, generally 10 to 60 ° C. When the reaction temperature is high, volatilization of the isocyanate compound and secondary reaction are likely to occur, resulting in a large measurement error.

The organic solvent used for the urethanization reaction includes
It can be used as long as it has no reaction activity with respect to isocyanate groups, but chlorine-based solvents have mutagenicity and may generate toxic substances during waste treatment and cause air pollution. , Not used in the present invention. As the solvent used in the present invention, specifically, for example,
Examples thereof include aromatic hydrocarbons such as toluene and xylene, esters such as ethyl acetate and butyl acetate, and ketones such as acetone and methyl ethyl ketone. These may be used alone or in combination of two or more depending on the solubility of the analyte. Moisture contained in the solvent,
Alternatively, since water absorbed from the reaction atmosphere into the reaction system causes an error, it is preferable to use a solvent having low hydrophilicity or a solvent having low volatility. Although aromatic hydrocarbons satisfy such conditions, toluene is most preferably used in consideration of solubility, compatibility with other solvents, ease of handling, and the like.

In the present invention, it is preferable to use a monoisocyanate compound as the isocyanate compound used as the urethane-forming agent. Specifically, for example, octadecyl isocyanate, octyl isocyanate, butyl isocyanate, t-butyl isocyanate, cyclohexyl isocyanate, adamantyl isocyanate, ethyl isocyanate acetate, ethoxycarbonyl isocyanate, phenyl isocyanate, alphamethylbenzyl isocyanate, 2-phenylcyclopropyl isocyanate, 2-ethylphenyl isocyanate, benzoyl isocyanate, methatolyl isocyanate, paratolyl isocyanate, 2-
Methoxyphenyl isocyanate, 3-methoxyphenyl isocyanate, 4-methoxyphenyl isocyanate, ethyl 4-isocyanate benzoate, 2,6-
There are dimethylphenyl isocyanate, 1-naphthyl isocyanate, naphthylethyl isocyanate and the like. Among these, it is preferable to use phenyl isocyanate, which has a high reactivity with hydroxyl groups.

It is advisable to use, as the urethane-forming agent, one of these isocyanate compounds previously diluted with the above-mentioned organic solvent used as a solvent for the urethane-forming reaction so as to have a predetermined isocyanate group concentration. In order to obtain high measurement accuracy, the concentration is 0.1 to 1 mol /
It is preferable that it is 1. The ratio of the amount of hydroxyl groups of the sample and the amount of isocyanate groups of the urethane-forming agent is 1: 2 in molar ratio.
It is preferably in the range of 1:10.

In the urethanization reaction, a commonly used known urethanization reaction catalyst can be used. Specifically, for example, a tetraalkylammonium hydroxide such as tetraethylammonium, monoethyltriethylammonium, diethyldimethylammonium, tetraethylammonium, tetrabutylammonium, or an organic weak acid salt, for example, trimethylhydroxypropylammonium, triethylhydroxypropylammonium, triethyl. Hydroxyalkyl ammonium hydroxides such as hydroxyethyl and weak organic acid salts, for example, alkali metal salts of alkylcarboxylic acids such as acetic acid, caproic acid, octylic acid, and misphosphoric acid, for example, metals such as tin, zinc and lead of the above alkylcarboxylic acids. A salt, for example, one of aminosilyl group-containing compounds such as hexamethyldisilazane, or a mixture thereof. Among the above-mentioned urethanization reaction catalysts, it is preferable to use an organic tin catalyst such as dibutyltin laurate since it has high catalytic activity. The amount of these urethanization reaction catalysts used is preferably 0.0005 to 1 mass% with respect to the isocyanate compound.

According to the present invention, a urethane agent, which has been adjusted to a predetermined isocyanate group concentration in advance, is added in a predetermined amount such that the isocyanate groups are excessive with respect to the hydroxyl groups of the test substance, and the hydroxyl groups are urethanized. Unreacted isocyanate groups remaining in the reaction system are quantified to calculate the hydroxyl value of the analyte.

The quantification of the isocyanate group may be carried out by a known and commonly used method for quantifying the isocyanate group, which comprises titrating with a titration reagent which is an amine solution having a known concentration and prepared in advance. Monoamines are preferably used as the amine for the titration reagent. For example, triethylamine, methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, t-butylamine, isobutylamine, pentylamine (such as n-, iso, t-), (n-, iso, t-). Hexylamine, (n)
-, Iso, t-, etc.) octylamine, diethylamine, di (n-isopropyl) amine, diisopropylamine, di (n-butyl) amine, diisobutylamine,
Di-t-butylamine, di (n-, iso, t-, etc.) pentylamine, di (n-, iso, t-, etc.) hexylamine, di (n-, iso, t-, etc.) octylamine, etc. One type is selected from the aliphatic amines and the like for use. It is preferable to use diisobutylamine, which has a high boiling point and is relatively inexpensive, because highly volatile substances are prone to measurement errors. The titration reagent is prepared by dissolving the above amino compound in the organic solvent used for the urethanization reaction so as to have a predetermined concentration. The concentration of amino groups in the titration reagent is preferably in the range of 0.05 to 0.5 mol / l. The end point of the titration is determined visually by checking the color change of the titration indicator. As a titration indicator,
Known and conventional ones such as bromophenol blue can be used.

A typical procedure for measuring the hydroxyl value is shown below. The main test and blank test are required to obtain the hydroxyl value. This test is to subject an analyte having a hydroxyl group in its chemical structure to urethanization with an excess urethane agent for the hydroxyl group, and then titrate the amount of unreacted isocyanate group remaining in the system with the titration reagent. This is an operation for quantifying by performing the following steps. The sample is precisely weighed and uniformly dissolved in a predetermined amount of the organic solvent. After the urethanization reaction catalyst is added and a predetermined amount of the urethanizing agent is added, the mixture is heated and stirred at a predetermined temperature to complete the urethanization reaction. Bromophenol blue is added as a titration indicator and titrated with a titration reagent to quantify unreacted isocyanate groups. The blank test means that the same operation is performed under the same conditions as the main test, except that the subject is not used. The blank test is performed in order to cancel the measurement error due to the reagent other than the test sample or the water content in the solvent, and is performed by the procedure omitting only the procedure of the main test.

The hydroxyl value of the test sample is determined from the titration reagent amount T (ml) required in this test and the amine solution amount BR (ml) required in the blank test by the following formula. Hydroxyl value = {(T-BR) × N × F × 56.1} ÷ S In the above formula, N is the amine concentration (mol / l) of the titration reagent,
F represents the titer of the amine solution, and S represents the weighed amount (g) of the subject. The hydroxyl value measurement method of the present invention, quality control of synthetic products,
It can be used for characterization purposes.

[0016]

EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples. <Example 1> Polypropylene glycol having a number average molecular weight of 400 (“SANNIX P” manufactured by Sanyo Kasei Co., Ltd.)
P-400 "; hydroxyl value in the manufacturer test table: 28
2) 0.2095 g was weighed into a 100 ml Erlenmeyer flask with a stopper and completely dissolved in 10 ml of toluene. One drop of dibutyltin laurate was added with a Pasteur pipette, 5 ml of a phenylisocyanate-toluene solution with a concentration of 0.5 mol / l was added, and the mixture was stoppered.
The reaction was allowed for 0 minutes. After completion of the reaction, a bromophenol blue indicator was added, and titration was performed with a diisobutylamine-toluene solution having a concentration of 0.1 mol / l to obtain a titration value of this test.

On the other hand, a titration value was obtained by performing a titration on a sample which was subjected to the same operation except that polypropylene glycol was not added, and a titration value in a blank test was obtained. The hydroxyl value calculated from the difference between the titration value in this test and the titration value in the blank test was 282.

<Example 2> Polytetramethylene glycol having a number average molecular weight of 250 ("polyTHF manufactured by BASF")
-250 "; hydroxyl value by pyridine-acetylation method:
474) 0.1996 g was weighed in a 100 ml Erlenmeyer flask with a stopper and completely dissolved in 10 ml of dehydrated toluene. One drop of dibutyltin laurate was added with a Pasteur pipette, 5 ml of a phenylisocyanate-toluene solution having a concentration of 0.5 mol / l was added, and the mixture was stoppered. The mixture was reacted for 30 minutes at room temperature while stirring. After completion of the reaction, a bromophenol blue indicator was added, and titration was performed with a diisobutylamine-toluene solution having a concentration of 0.1 mol / l to obtain a titration value of this test.

On the other hand, a titration value was obtained by performing a titration on a sample which was subjected to the same operation as above except that polytetramethylene glycol was not added, and a titration value in a blank test was obtained. The hydroxyl value calculated from the difference between the titration value of this test and that of the blank test is 47.
It was 0.

<Comparative Example 1> This Comparative Example is based on the above-mentioned Ber.
nd Dreher (FARBE UND LACK,
Nr. 11, 1961), and the method for measuring the hydroxyl value by urethanization of hydroxyl groups.
Polypropylene glycol having a number average molecular weight of 400 (“SANNIX PP-400” manufactured by Sanyo Kasei Co., Ltd .;
Hydroxyl value shown in the manufacturer test table: 282) 0.2083
g was weighed into a 100 ml Erlenmeyer flask with a stopper, and completely dissolved in 10 ml of dehydrated mixed solvent of chlorobenzene / acetone = 1: 1. 5 ml of a phenylisocyanate-chlorobenzene solution having a concentration of 0.5 mol / l was added and the mixture was stoppered, and the mixture was reacted at room temperature for 5 minutes while stirring. After completion of the reaction, add bromophenol blue indicator,
Titration was performed with a diisobutylamine-chlorobenzene solution having a concentration of 0.1 mol / l to obtain the titration value of this test.

On the other hand, titration was carried out for all the same operations as above except that polypropylene glycol was not added, and titration values of blank test were obtained. The hydroxyl value calculated from the difference between the titration value of this test and the titration value of the blank test was 17. The urethanization reaction was carried out for 1 hour in the same manner,
The calculated hydroxyl value was 40.

The polypropylene glycol used in Example 1 and Comparative Example 1 ("SANNIX PP-400" manufactured by Sanyo Kasei Co., Ltd.) has a hydroxyl group bonded to the second carbon atom in its chemical structure. . From the results shown in Examples and Comparative Examples, by using the hydroxyl value measurement method of the present invention using a urethanization reaction catalyst,
It is clear that the hydroxyl value can be accurately measured without using a chlorine-based solvent. In particular, it is a feature of the present invention that even if the hydroxyl group is bonded to the second carbon atom or the third carbon atom, which cannot be achieved by the conventional method, it can be easily quantified.

[0023]

EFFECTS OF THE INVENTION In the hydroxyl value measuring method of the present invention for urethanizing a hydroxyl group of an analyte, by using a urethanization reaction catalyst, not only when the hydroxyl group of the analyte is bonded to the first carbon atom, Even if it is bonded to the second carbon atom or the third carbon atom, it can be accurately measured, and since it does not use a mutagenic or toxic chlorine solvent,
It has a remarkable effect that cannot be achieved by conventional techniques, that is, it can reduce adverse effects on health and environmental load.

Claims (4)

[Claims] 1. In the method for measuring a hydroxyl value, a predetermined amount of an isocyanate compound is added so that the hydroxyl group of a test substance is excessive in the presence of a urethanization reaction catalyst in a non-chlorine solvent. A method for measuring a hydroxyl value, which comprises determining the hydroxyl value by quantifying unreacted isocyanate groups after urethanization with urethane. 2. The hydroxyl value measuring method according to claim 1, wherein a non-chlorine solvent containing toluene is used as the non-chlorine solvent. 3. The hydroxyl value measuring method according to claim 1, wherein phenyl isocyanate is used as the isocyanate compound. 4. The method for measuring a hydroxyl value according to claim 1, wherein an organotin compound is used as the urethane-forming reaction catalyst.