JPH0551416A - Production of maleic anhydride-alkylvinyl ether copolymer - Google Patents

Abstract

PURPOSE:To obtain the subject copolymer at a low cost without affecting human bodies, by employing a dialkyl carbonate as a solvent. CONSTITUTION:For example, maleic anhydride or its solution and a dialkyl carbonate (e.g. diethyl carbonate or dimethyl carbonate) as a solvent are charged in a reactor so that the content of the produced copolymer is 5-30wt.% in the reaction solution after the copolymerization, and further a radical polymerization initiator (e.g. benzoyl peroxide) and an alkylvinyl ether (e.g. methylvinyl ether) are continuously or intermittently charged in the reactor, followed by subjecting the monomers to a precipitation polymerization reaction preferably at 40-90 deg.C to obtain the objective copolymer.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a maleic anhydride-alkyl vinyl ether copolymer by precipitation polymerization.

Maleic anhydride-alkyl vinyl ether copolymers are linear, water-soluble polyelectrolyte compounds. Recently, it is excellent in non-toxicity to human body, stability over a long period of time, adhesiveness, cohesiveness, water retention, peelability, etc.
It is used in a wide range of industrial fields as a spray-type hair fixative and a builder for synthetic detergents. Further, those obtained by reacting this copolymer with various alcohols are also used for these purposes.

[0003]

2. Description of the Related Art Conventionally, alkyl vinyl ether is often polymerized with maleic anhydride in the presence of a radical initiator in various solvents to give a maleic anhydride-alkyl vinyl ether copolymer. Are known.

At this time, a method of reacting by precipitation polymerization in a solvent in which the raw material maleic anhydride is dissolved but the maleic anhydride-alkyl vinyl ether copolymer is not dissolved, or the raw material maleic anhydride and maleic anhydride are used. There is known a method of reacting by solution polymerization in a solvent that dissolves both of an alkyl vinyl ether copolymer.

An example of precipitation polymerization is benzene (US-2
782182, US-3030343, US-3499.
876, US-3532771, US-355318.
3, DE-3302495, JP-A-1-204910,
JP-A-1-204911, JP-A-1-204912, U
S-4900809 etc.), toluene, xylene (US
-3499876, US-35332771, US-35.
53183, DE-3302495, JP-A-1-204
910, JP-A-1-204911, and JP-A-1-2049.
12) etc., aromatic hydrocarbons, hexane, heptane,
Aliphatic hydrocarbons such as octane (US-3532771), dichloroethane (GB-1117515, US-3
499876, DE-3302495), trichloroethane, carbon tetrachloride (DE-3302495), 1,
1,2-Trichloro-1,2,2-trifluoroethane / dichloromethane mixture (JP-A-55-145714)
And other halogenated aliphatic hydrocarbons, esters having 5 or more carbon atoms (DE-3736996), isopropyl acetate, methyl propionate (JP-A-1-204910, JP-A-1-204910,
204911, esters such as JP-A-1-204912, and allyl vinyl ether (GB-906230, DE).
-371265, DE-3108100), and sterically bulky ether such as monoether (WO-9012817). (US-49
48848, JP-A-1-204910, JP-A 1-20
4911, JP-A-1-204912, acetone (US
It is known to carry out the reaction using methyl ethyl ketone (US-3499876), US Pat.

[0006]

However, when the reaction is carried out using a solvent which adversely affects the human body, such as benzene, toluene, xylene, carbon tetrachloride, dichloroethane, trichloroethane, etc. in the prior art, the drying step after the reaction is performed. Even with careful drying, it was difficult to reach zero concentration in the product. Since a detergent using a maleic anhydride-alkyl vinyl ether copolymer is used by directly contacting the human body (skin etc.), it is necessary to develop a reaction method using a solvent that does not adversely affect the human body. there were.

Although reaction methods using solvents other than those mentioned above are also known, they have the following drawbacks.

When esters such as ethyl formate, isopropyl acetate, butyl acetate and methyl propionate are used,
During the reaction, the copolymer easily sticks to the wall of the reaction vessel,
There is a problem in handling. When the reaction is carried out by solution polymerization using methyl acetate, ethyl acetate, acetone, methyl ethyl ketone, etc., a large amount of energy is required for removing the solvent as compared with precipitation polymerization. Also, when using only aliphatic hydrocarbons such as hexane, heptane, octane,
The monomer is difficult to dissolve in the solvent and the reaction is difficult to proceed.

An object of the present invention is to provide a production method for solving the above-mentioned problems, that is, a production method capable of obtaining a copolymer by precipitation polymerization in a solvent that does not adversely affect the human body. is there.

[0010]

That is, the present invention is
"A method for producing a maleic anhydride-alkyl vinyl ether copolymer characterized by using a dialkyl carbonate as a solvent".

The "method for producing a maleic anhydride-alkyl vinyl ether copolymer" of the present invention will be described in detail below.

The reaction formula for producing the maleic anhydride-alkyl vinyl ether copolymer is shown below.

[0013] In the formula, n is in the range of 10 to 100,000, and it can be controlled by adjusting the charged amount of the polymerization initiator, the addition rate of the alkyl vinyl ether monomer, the polymerization temperature, and the like. R ₁ is the carbon number 1 to 4, straight chain,
A branched or alicyclic alkyl group is shown.

In the copolymerization in the method of the present invention, maleic anhydride, which is a starting material monomer, or a solution thereof is charged in a reactor, and a radical polymerization initiator and an alkyl vinyl ether are continuously or intermittently fed during the reaction. It can be carried out by a semi-batch method in which it is charged in a batch. It is also possible to charge all the reaction raw materials in a lump from the beginning, and then heat and react them.

In the precipitation polymerization, a maleic anhydride-alkyl vinyl ether copolymer is precipitated with the progress of the reaction. Therefore, by filtering and drying the maleic anhydride-alkyl vinyl ether copolymer,
You can get the product.

The present invention is characterized in that a dialkyl carbonate is used as a solvent. The dialkyl carbonate referred to in the present invention is represented by the following general formula (R ² O) ₂ C═O [wherein R ² has 1 to 5 carbon atoms, and is linear, branched or alicyclic. Represents an alkyl group of],
Specifically, dimethyl carbonate, diethyl carbonate
, Di-n-propyl carbonate, diisopropyl carbonate, di-n-butyl carbonate, di-t-butyl carbonate, diisobutyl carbonate, di-s
ec-Butyl carbonate, di-n-pentyl carbonate, dineopentyl carbonate, and the like can be mentioned.

There are no particular restrictions on the amount of solvent used,
The ratio of the copolymer in the reaction crude liquid at the end of the reaction is 5 to 3
It is preferably set to 0% by weight. If it is less than 5% by weight, the production efficiency will be too low. Also, 30
If it is more than 10% by weight, the copolymer may stick to the wall of the reactor during the reaction, which is not preferable.

Next, the method of the present invention will be described.

Alkyl vinyl ether used in the present invention
Ter is represented by the following general formula R ¹ —O—CH═CH ₂ [wherein R ¹ represents a linear, branched or alicyclic alkyl group having 1 to 4 carbon atoms]. It is a thing. Specifically, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, t-butyl vinyl ether, sec-butyl vinyl ether, etc. Can be mentioned. It is particularly preferred to use methyl vinyl ether.

The reaction may be carried out at normal pressure or under pressure using a closed vessel. The reaction temperature depends on the amount of the solvent used, but it is usually in the range of 40 to 120 ° C., which is the temperature for radical polymerization, preferably in the range of 40 to 90 ° C.

Although there are many kinds of polymerization initiators, organic peroxides and azo compounds are generally used because of their ease of handling.

The reactivity of a polymerization initiator is generally expressed by its half-life. Among the polymerization initiators, those having a one-hour half-life of 60 to 100 ° C. are desirable. Since a polymerization initiator having a one-hour half-life of less than 60 ° C. has a low decomposition temperature and is very active, it needs to be refrigerated or frozen during storage and must be handled with extreme caution. A polymerization initiator having a one-hour half-life of more than 100 ° C. has a very slow decomposition rate at a suitable polymerization temperature for producing a maleic anhydride-alkyl vinyl ether copolymer and has a long polymerization time. Not at all.

Specific examples of the polymerization initiator having a one-hour half-life of 60 to 100 ° C. include benzoyl peroxide and 4-
Chlorobenzoylperoxide, 2,4-dichlorobenzoylperoxide, 2-methylbenzoylperoxide, octanoylperoxide, decanoylperoxide, lauroylperoxide, stearoylperoxide, t-butylperoxypivalate, t-butylperoxide. −
Oxy-2-ethylhexanate, t-butylperoxyneodecaneate, t-butylperoxyisobutyrate, bis (2-ethylhexyl) peroxydica carbonate, bis (4-t-butylcyclohexyl) peroxydica -Bonate, diisopropylperoxydicarbonate, di-sec-butylperoxydicarbonate, diisopropylbenzene hydroperoxide, 2,
2'-azobisisobutyronitrile, 2,2'-azobis-2,4-dimethylvaleronitrile, 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile and the like can be mentioned.

When the polymerization initiator is continuously charged during the reaction,
The charging rate varies depending on the molecular weight of the target maleic anhydride-alkyl vinyl ether copolymer, the type of the polymerization initiator, the chain transfer constant of the polymerization initiator or the growing radical to the reaction solvent, the amount of the reaction solvent, etc. But 0.0
It is preferably from 01 to 3.0 meq / hour.

In the detailed description of the present invention, the charging rate of the polymerization initiator or methyl vinyl ether is such that the number of moles of the polymerization initiator or methyl vinyl ether charged in the reactor per unit time is used for the reaction. It is represented by the molar ratio of maleic anhydride to the total number of moles, and the unit of "equivalent / hour" will be used.

The amount of the polymerization initiator charged is 0.001 continuously.
When it is less than milliequivalent / hour, the reaction time becomes long and the productivity deteriorates, which is inconvenient. Further, if it continuously exceeds 3.0 milliequivalents / hour, the amount of the polymerization initiator remaining in the product increases, which is not convenient. Furthermore, it is better not to interrupt the addition of the polymerization initiator until the stage of 2 to 3 hours before the completion of the polymerization reaction.

Depending on the case, a charging method may be used in which a fixed amount of a polymerization initiator is added at the start of the reaction and then the addition is continued at a rate of 0.001 to 3.0 meq / hour.

When alkyl vinyl ether is continuously charged during the reaction, the charging rate is the molecular weight of the intended maleic anhydride-alkyl vinyl ether copolymer, the kind of the polymerization initiator, and the initiation of polymerization for the reaction solvent. Although it varies depending on the chain transfer constant of the agent and the growing radical, the amount of the reaction solvent, etc., 0.01 to 2.0 equivalents / hour, preferably 0.02 to 0.
8 equivalents / hour is recommended. When the charging rate of the alkyl vinyl ether is 0.01 equivalent / hour or less, the reaction time becomes long, which is not convenient.

On the other hand, if it exceeds 2.0 equivalents / hour, the amount of the alkyl vinyl ether copolymer which is vaporized from the surface of the liquid phase without participating in the reaction is increased, which is not economically preferable.
When the amount is less than 0.01 equivalent / hour, it takes a long time to complete the reaction.

When the alkyl vinyl ether is charged all at once, the amount used is 1.0 to 3.0 equivalents, preferably 1.0 to 1.5 equivalents, of the maleic anhydride used. Is preferred.

The progress of the polymerization reaction can be tracked by analyzing the amount of maleic anhydride by gas chromatography.

The molecular weight of the maleic anhydride-alkyl vinyl ether copolymers described in this invention is actually expressed by the specific viscosity measured in methyl ethyl ketone. The method for measuring the specific viscosity is as follows.

A 1% (weight / volume, 25 ° C.) concentration solution using the copolymer methyl ethyl ketone as a solvent was prepared.
Using a capillary viscometer specified by ISK6726, 2
The fall time at 5 ° C. is measured and calculated by the following calculation formula.

Specific viscosity = (A−B) / B However, in the above formula, A = measured value of drop time for copolymer solution B = measured value of drop time for solvent

Since the value of the specific viscosity increases as the molecular weight of a polymer having the same structural unit increases, it is generally widely used as a standard for relatively expressing the molecular weight of the polymer.

After the completion of the polymerization, the copolymer is taken out of the reactor in the form of a slurry, and after undergoing steps such as filtration and drying, it becomes a white powdery or fine granular dry copolymer product.

Regarding the molecular weight of the copolymer, any one can be obtained by changing the charged amounts of the alkyl vinyl ether and the polymerization initiator.

[0038]

According to the reaction method of the present invention, a copolymer can be obtained by precipitation polymerization in a solvent that does not adversely affect the human body, without the copolymer sticking to the wall of the reaction vessel during the reaction. it can.

The method of the present invention will be described below with reference to examples and comparative examples, but these do not limit the present invention. Further, in any of the examples, the reaction was completed within a predetermined time.

[0040]

Example 1 Maleic anhydride 188 g in a 5 liter reaction can equipped with a stirrer, a reflux condenser and an internal temperature controller.
Then, 2432 g of dimethyl carbonate was poured and dissolved, and then the internal temperature was maintained at 81.5 ° C. Lauroylperoxide 0.456 as a polymerization initiator from the upper part of the reactor
A solution of 400 g of dimethyl carbonate in 400 ml of dimethyl carbonate was added at a rate of 50 ml per hour (0.075
(Milli-equivalent / hour), and methyl vinyl ether was continuously charged from the bottom of the reactor at a rate of 90 ml per hour until the reaction was completed. After the reaction was carried out for 5.0 hours, the inside of the reaction tube was cooled to cool the copolymer slurry.
Got When the solvent was removed from this slurry, a white powder was obtained. The specific viscosity of this copolymer was 3.32.

[0041]

Example 2 188 g of maleic anhydride and 2458 g of diethyl carbonate were charged into a 5 liter reaction vessel similar to that used in Example 1 and dissolved therein.
Maintained at. From the top of the reactor, 0.456 g of lauroyl peroxide as a polymerization initiator was added to diethyl carbonate 4
A solution dissolved in 00 ml was continuously charged at a rate of 50 ml per hour (0.075 meq / hour), and 1 methyl vinyl ether was added from the bottom of the reactor.
It was continuously charged at a rate of 90 ml per hour until the end of the reaction. After reacting for 3.0 hours, the inside of the reaction tube was cooled to obtain a copolymer slurry. When the solvent was removed from this slurry, a white powder was obtained. The specific viscosity of this copolymer was 0.96.

[0042]

Example 3 The reaction was carried out in the same manner as in Example 2 except that 0.152 g of lauroyl peroxide was used, and the reaction was completed in 3.7 hours. When the solvent was removed from the copolymer slurry, a copolymer having a specific viscosity of 1.64 was obtained.

[0043]

Example 4 The reaction was carried out in the same manner as in Example 2 except that 0.076 g of lauroyl peroxide was used, and the reaction was completed in 4.4 hours. When the solvent was removed from the copolymer slurry, a copolymer having a specific viscosity of 2.20 was obtained.

[0044]

Example 5 The reaction was carried out in the same manner as in Example 2 except that 0.038 g of lauroyl peroxide was used, and the reaction was completed in 5.7 hours. When the solvent was removed from the copolymer slurry, a copolymer having a specific viscosity of 2.60 was obtained.

[0045]

Example 6 The reaction was carried out in the same manner as in Example 2 except that 0.024 g of lauroyl peroxide was used, and the reaction was completed in 5.8 hours. When the solvent was removed from the copolymer slurry, a copolymer having a specific viscosity of 2.51 was obtained.

[0046]

Example 7 The reaction was carried out in the same manner as in Example 2 except that 0.012 g of lauroyl peroxide was used, and the reaction was completed in 6.2 hours. When the solvent was removed from the copolymer slurry, a copolymer having a specific viscosity of 2.96 was obtained.

[0047]

Example 8 188 g of maleic anhydride and 2743 g of di-n-butyl carbonate were charged into a 5 liter reaction vessel similar to that used in Example 1 and dissolved therein, and then the internal temperature was maintained at 75 ° C. A solution prepared by dissolving 0.456 g of lauroyl peroxide as a polymerization initiator in 400 ml of di-n-butyl carbonate was continuously added from the top of the reactor at a rate of 50 ml per hour (0.075 meq / hour). Then, n-butyl vinyl ether was continuously charged from the bottom of the reactor at a rate of 75 ml per hour until the reaction was completed. After reacting for 3.0 hours, the inside of the reaction tube was cooled to obtain a copolymer slurry.

When the solvent was removed from this slurry, a white powder was obtained. The specific viscosity of this copolymer was 1.09.

Claims (4)

[Claims] 1. A method for producing a maleic anhydride-alkyl vinyl ether copolymer, which comprises using a dialkyl carbonate as a solvent. 2. The dialkyl carbonate is diethyl carbonate.
The manufacturing method according to claim 1, wherein the manufacturing method is a bonnet. 3. A dialkyl carbonate is dimethyl carbonate.
The manufacturing method according to claim 1, wherein the manufacturing method is a bonnet. 4. The method according to claim 1, wherein the alkyl vinyl ether is methyl vinyl ether.