JPH078829B2 - Method for producing hydroxypentivalate neopentyl glycol diacrylate compound - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention produces a hydroxypivalic acid neopentyl glycol di (meth) acrylate by transesterification of a lower alkyl (meth) acrylate and neopentyl glycol hydroxypivalate. On how to do.

The resulting di (meth) acrylate polymerizes when exposed to a small amount of ionizing radiation or ultraviolet light, or when a free radical catalyst is added to produce a substance having extremely strong resistance to stains (meth). It is an acrylic monomer.

Also, these cured materials show excellent resistance to the most severe dirt test, good scratch strength,
It has extremely excellent properties such as scratch resistance and has a wide range of industrial uses.

[Prior Art] As a method for producing neopentyl glycol di (meth) acrylate hydroxypivalate, a method of producing by esterification reaction of (meth) acrylic acid and neopentyl glycol hydroxypivalate is known (Japanese Patent Publication No. Sho 48). -Four
No. 014).

As the catalyst, an acid catalyst such as sulfuric acid, p-toluenesulfonic acid, phosphoric acid or hydrochloric acid is used.

However, the reaction product obtained by this method contains 15% by-product neopentyl glycol di (meth) acrylate.
~ 20% amount included.

Those containing these by-products have strong skin irritation,
The handling process is prone to health problems such as skin inflammation, making handling difficult and dangerous.

As a method of indicating the strength of skin irritation, a primary skin irritation value, that is, Primary Irritation Index-abbreviation PII is known, and it is composed of the following 6 stages. There is.

The primary skin irritation test method adopted here is a method widely practiced by those skilled in the art, and is the Consumer Product. Safety Commission of the You.
S. A in the Code Off Federal Regulations. Title 16. Section 1500.41 (Th
e Consumer product.Safety commision of the USA i
n the coad of federal regulations.Title 16.Section
1500.41).

The PII value of neopentyl glycol diacrylate by-produced by the method of Japanese Patent Publication No. 48-4014 described above is 8,
It has extremely strong skin irritation.

Further, due to these by-products, the odor of the esterification product is terrible, causing health disorders such as hepatitis, and it is desired to pay attention to the prevention thereof, and it cannot be said to be a preferable production method.

[Problems to be solved by the invention]

As described above, the conventional production method cannot avoid the by-production of neopentyl glycol di (meth) acrylate.

However, the present invention provides a highly pure hydroxypivalic acid neopentyl glycol di (meth) acrylate that has significantly less side reaction products than conventional production methods, a low PII value, and has no health problems due to odor. Intended to be manufactured.

[Means for Solving Problems] That is, according to the present invention, as a result of extensive studies to solve these problems, when a transesterification method is adopted under a specific catalyst, neopentyl glycol which is a side reaction product. By significantly reducing the amount of di (meth) acrylate, the primary skin irritation is reduced to below a certain level, and the odor is also reduced to the same level, and the excellent curability during polymerization, which is the original feature of this type of compound, is reduced. The inventors have found that a high-purity target product can be obtained, and completed the present invention.

That is, in the present invention, an alkyl tin oxide is used as a catalyst when a lower alkyl (meth) acrylate is transesterified with neopentyl glycol hydroxypivalate to produce neopentyl glycol di (meth) acrylate hydroxypivalate. And a method for producing hydroxypentavalic acid neopentyl glycol di (meth) acrylate.

The present invention will be described in detail below.

In the practice of the present invention, the alkyl tin oxide used as a catalyst is typically di-n-butyltin oxide, dioctyltin oxide, or the like.

The amount of the catalyst used is usually 0.1 to 5 mol%, preferably 0.5 to 3 mol%, based on the raw material neopentyl glycol hydroxypivalate.

The amount of lower alkyl (meth) acrylate used is preferably in the range of 2.5 to 8 mol, particularly preferably 4 to 1 mol of neopentyl glycol hydroxypivalate as a raw material.
It is more than a mole.

In the transesterification reaction, a polymerization inhibitor is added to the reaction system in order to prevent the polymerization of the raw material lower alkyl (meth) acrylate and the target product hydroxypivalic acid neopentyl glycol di (meth) acrylate.

Hydroquinone, a polymerization inhibitor usually used,
Hydroquinone monomethyl ether, p-phenylenediamine, diphenylamine and the like can be mentioned, and hydroquinone is a particularly preferable polymerization inhibitor.

It is also desirable to supply air into the reaction system in order to prevent popcorn polymerization.

The reaction temperature is usually 40 to 130 ° C, preferably 70 to 120
℃.

If the temperature is lower than 40 ° C, the activity of the catalyst is low, and if it is higher than 130 ° C, side reactions such as polymerization rapidly increase, which is not preferable.

The reaction can be carried out at normal pressure, but it is advantageous to carry out the reaction at a slightly reduced pressure because the by-product alcohol can be rapidly distilled out of the system.

In carrying out the reaction, it is not necessary to separately supply the catalyst in a divided manner, and the required amount may be added all at once at the start of the reaction.

A reaction solvent is not usually required, but may be used.

Examples of the type of solvent used include n-hexane, benzene, toluene and the like.

Since the alcohol by-produced by the reaction is azeotroped with unreacted lower alkyl (meth) acrylate, the azeotrope is led to a distillation column during the reaction, and part of it is refluxed in the reaction system at an appropriate reflux ratio. Pull out of the system.

The reflux ratio at this time is usually set between 0.5: 1 and 20: 1.

A general embodiment of the present invention will be described.

First, a reactor equipped with a thermometer and a distillation column is charged with a predetermined amount of raw material,
Charge a catalyst, a polymerization inhibitor, and a solvent if necessary, and heat while passing a specified amount of air under full reflux (liquid temperature 85
(Around ℃) for a while, and when the reflux becomes vigorous, set the reflux ratio to 0.5: 1 to 20: 1 and part of the azeotrope of the alcohol and lower alkyl (meth) acrylate by-produced outside the system. Pull out.

Although the column top temperature and the temperature of the reaction solution increase with the progress of the reaction, it is desirable to keep the temperature of the reaction solution at 130 ° C. or lower in order to prevent side reaction and formation of a polymer.

The reaction time varies depending on the raw material molar ratio, the reflux ratio, etc.,
Usually within 20 hours.

The transition of the reaction may be checked by quantifying the alcohol of the azeotropic substance taken out by gas chromatography and checking the reaction rate.

After the reaction, unreacted lower alkyl (meth) acrylate is distilled off, and if necessary, the catalyst and unreacted neopentyl glycol hydroxypivalate are removed by washing with alkali and water to remove water and a trace amount of lower alkyl (meth). The acrylate is distilled off under reduced pressure to obtain the target product, hydroxypivalic acid neopentyl glycol di (meth) acrylate.

〔Example〕

Next, the present invention will be described in more detail with reference to Examples. The parts are parts by weight.

Example 1 516 parts of methyl acrylate, 306 parts of neopentyl glycol hydroxypivalate, 1.55 parts of hydroquinone as a polymerization inhibitor and di-n as a catalyst were placed in a flask equipped with a stirrer, a thermometer, and a distillation column having 20 stages of Oldershaw.
Add 7.5 parts of butyltin oxide and heat in an oil bath at 100 ° C. with stirring.

At this time, air was supplied into the system at a rate of 200 ml / min to prevent polymerization.

The azeotrope of by-produced methanol and the raw material methyl acrylate was totally refluxed for about 20 minutes, and then reacted at a reflux ratio of 20: 1 while removing a part of the azeotrope out of the system.

During the reaction, the overhead temperature of the distillation column was maintained at 65 to 85 ° C.

The transesterification reaction proceeded 95% in 20 hours.

After the reaction, the reaction mixture was distilled under reduced pressure to remove unreacted methyl acrylate.

An equal amount of n-hexane was added to the distillation residual liquid, a 5% aqueous sodium hydroxide solution was added, and the mixture was stirred, the catalyst was transferred to an aqueous layer, and washed with water to remove an alkali content.

The n-hexane was distilled off under reduced pressure to obtain 435 parts of the desired product.

The actual yield was 93%.

The analysis results of the obtained target substance are as follows.

Example 2 569 parts of n-butyl methacrylate in a flask equipped with a stirrer, a thermometer, and a distillation column with 20 stages of Oldersio,
204 parts of neopentyl glycol hydroxypivalate,
Add 1.7 parts of hydroquinone as a polymerization inhibitor and 7.1 parts of dioctyltin oxide as a catalyst, and stir 120
Heat in oil bath at ° C.

The pressure in the reaction system is controlled to a reduced pressure of 200 mmHg.

By-produced n-butanol is distilled out of the system.

During the reaction, the overhead temperature of the distillation column was maintained at 82 to 85 ° C.

The transesterification reaction proceeded 89% in 20 hours.

After the reaction, the reaction mixture was distilled under reduced pressure to remove unreacted n-butyl methacrylate.

The distillation residue was treated as in Example 1 to give the desired product.
I got 266 copies.

The actual yield was 85%.

The analysis results of the obtained target substance are as follows.

Comparative Example 1 In a flask equipped with a stirrer, a thermometer, and a distillation column with 20 stages of Oldersio, 161 parts of acrylic acid, 204 parts of neopentyl glycol hydroxypivalate, 0.34 parts of hydroquinone as a polymerization inhibitor, and cyclohexane as an azeotropic solvent.
Add 96 parts and 4.2 parts of sulfuric acid as a catalyst and heat with stirring.

At this time, air was supplied into the system at a rate of 200 ml / min to prevent polymerization.

The water generated as the esterification reaction proceeds is azeotropically distilled with cyclohexane and led to a water separator, and the separated water is taken out of the system.

The temperature of the reaction kettle liquid is maintained at 70 to 110 ° C to complete the reaction.

The reaction rate can be known from the amount of water produced as a by-product.

The esterification reaction proceeded 95% in 10 hours.

After the reaction, the reaction mixture was washed with 20% aqueous sodium hydroxide solution,
After separating the two layers, the lower layer is taken out and the upper layer is distilled under reduced pressure,
The azeotropic solvent cyclohexane was removed to obtain 274 parts of the desired product.

The actual yield was 88%.

The analysis results of the obtained target product are as follows.

Comparative Example 2 430 parts of methyl acrylate, 204 parts of neopentyl glycol hydroxypivalate, 0.43 parts of hydroquinone as a polymerization inhibitor and 3.4 parts of tetrabutoxy titanate as a catalyst were placed in a flask equipped with a stirrer, a thermometer and a distillation column with 20 stages of Oldersiod. Add and heat while stirring in an oil bath at 100 ° C.

At this time, air was supplied into the system at a rate of 200 ml / min to prevent polymerization.

The azeotrope of by-produced methanol and the raw material methyl acrylate was totally refluxed for about 20 minutes, and then the reaction was carried out while removing a part of the azeotrope from the system at a reflux ratio of 20: 1.

During the reaction, the overhead temperature of the distillation column was maintained at 65 to 85 ° C.

The transesterification reaction proceeded 20% in 10 hours.

Further, the catalyst tetrabutoxy titanate was added to the 3.4 parts reaction system.

The transesterification reaction had a reaction rate of at most 25% in 20 hours.

Claims (2)

[Claims] 1. An alkyl tin oxide is used as a catalyst when a lower alkyl (meth) acrylate is transesterified with neopentyl glycol hydroxypivalate to produce neopentyl glycol hydroxypivalate di (meth) acrylate. A process for producing hydroxypentivalic acid neopentyl glycol di (meth) acrylate, which comprises: 2. The lower alkyl (meth) acrylate is one or a mixed ester lower alkyl (meth) acrylate selected from methyl, ethyl, propyl, isopropyl, butyl or isobutyl (meth) acrylate. A method for producing the hydroxypivalic acid neopentyl glycol di (meth) acrylate according to the first item.