JP2941036B2 - Method for preventing coloration of epoxidized (meth) acrylate - Google Patents

Description

The present invention relates to a method for preventing coloration in a process for producing an epoxidized (meth) acrylate compound.

(Meth) acrylate compounds can be easily homopolymerized or copolymerized with other unsaturated group-containing compounds in the presence of heat, ultraviolet rays, ionizing radiation, and radical polymerization initiators. Is also useful.

<< Conventional Technology >> Conventionally, various acrylic acid ester monomers have been known.

For example, monofunctional monomers such as methyl acrylate, ethyl acrylate and 2-ethylhexyl acrylate, and polyfunctional monomers such as trimethylolpropane triacrylate and pentaerythritol triacrylate are generally known.

However, when monofunctional monomers are used in printing inks and paints, the odor of the unreacted monomers after curing becomes a serious problem.

Further, when a polyfunctional monomer is used as a diluent for paints and printing inks, it must be used in a large amount with respect to the resin, and thus has the disadvantage that the properties of the resin are lost.

That point [Wherein R represents a hydrogen atom or a methyl group] obtained by epoxidizing a cyclohexenylmethyl (meth) acrylate compound represented by the following formula: [Wherein R represents a hydrogen atom or a methyl group] has a low viscosity, a low odor, and a wide range of solubility in a resin, such as an ink, a paint, an adhesive, a coating agent, It is useful as a raw material or a modifier for molding resins.

<< Problems to be Solved by the Invention >> However, the epoxidized (meth) acrylate represented by the general formula (II) (hereinafter referred to as AETHB when R is a hydrogen atom and METHB when R is a methyl group) Is abbreviated to coloration and is known to frequently color during production, storage and transport due to air oxidation and other factors.

This is thought to be due to the fact that the monomer itself is rich in reactivity, so that a small amount of polymerization or side reaction occurs in the production process to cause coloration.

If colored, the commercial value may be lost depending on the application.

For example, a typical example is a case in which the paint is used as an automatic paint.

In other words, the reactivity of the monomer, even if useful, may not be industrially usable due to the ease of coloring.

Usually, the hue of the epoxy group-containing (meth) acrylate that is commercially available is at least 200 or less in APHA value, and is preferably 100 or less in APHA value in order to suit all uses.

Distillation is the most common method for preventing coloration or for removing a color-causing substance.

However, when the boiling point of the monomer is high, the monomer must be distilled at a high temperature, and the monomer having originally high reactivity may be polymerized.

In addition, since the product has a high boiling point, it is difficult to separate it from a high-boiling-point colored substance in the case where a product is produced while removing only low-boiling-point substances.

Therefore, in such a case, it is preferable to employ a chemical treatment, an adsorption treatment method, or the like, rather than a distillation separation.

Examples of the chemical treatment include oxidizing agents such as molecular oxygen and hydrogen peroxide, reducing agents such as sodium borohydride and sodium bis (2-methoxyethoxy) aluminum, and polymerization inhibitors such as hydroquinone and hydroquinone monomethyl ether. , An antioxidant such as BHT and BHA, and a sequestering agent such as EDTA and trioctyl phthalate are added during the process to prevent coloring.

Further, as the adsorption treatment method, a method of using activated clay, zeolite, a high-porous polymer, or the like in addition to activated carbon, which is the most common, is well known.

Attempts were made with these conventional methods, but no effective bleaching effect was found.

Also, the present inventors, as described in JP-A-2-191267,
By using a hydrotalcite compound, although a decolorizing effect was obtained, when a long-term storage test was performed,
Color reversion occurred and was not complete.

Therefore, the present inventors have determined that decolorization by distillation or adsorption treatment is difficult, and have repeated research on chemical treatment, and have finally completed the present invention.

<< Constitution of the Invention >> That is, the present invention provides a compound represented by the following general formula (I) [Wherein R represents a hydrogen atom or a methyl group] The cyclohexenylmethyl (meth) acrylate compound represented by the following formula is epoxidized with an oxidizing agent to obtain a compound represented by the general formula (II): [Wherein R represents a hydrogen atom or a methyl group] In the process of producing a compound having both an epoxy group and a (meth) acrylate group represented by the following formula: [However, in the formula (III), R ^{1 to} R ⁸ are hydrogen, halogen, or a monovalent aliphatic or aromatic substituent having 1 to 10 carbon atoms, and R ^{1 to} R ⁸ may be the same or different. Coloring of a compound having both an epoxy group and a (meth) acrylate group, characterized in that 0.001 to 1 part of the phosphaphenanthrene compound represented by the formula (1) is allowed to coexist with 100 parts of the compound (II). Prevention method ".

Hereinafter, the method for preventing coloring of AETHB (METHB) of the present invention will be described in detail.

 First, the epoxidation manufacturing process will be described.

That is, the (meth) acrylate compound represented by the general formula (I) is epoxidized with an oxidizing agent.

The oxidizing agent used at this time may be anything that can epoxidize the unsaturated bond, such as formic acid, peracetic acid, perpropionic acid,
Various hydroperoxides such as m-chloroperbenzoic acid, trifluoroperacetic acid, perbenzoic acid, tertiary butyl hydroperoxide, cumyl hydroperoxide, tetralyl hydroperoxide, diisopropylbenzene hydroperoxide, and peroxides Hydrogen and the like can be mentioned as examples.

The oxidizing agent may be used in combination with a catalyst. For example, when an organic peracid is used, an alkali such as sodium carbonate or an acid such as sulfuric acid may be used in combination as a catalyst.

Similarly, when using the above various hydroperoxides, those having a known catalytic activity such as molybdenum hexacarbonyl can be used, and when using hydrogen peroxide, a mixture of tungstic acid and caustic soda can be used in combination.

When the reaction is carried out in batch, first, a predetermined amount of silcohexenylmethyl (meth) acrylate is charged into a reactor, and a catalyst and a stabilizer are dissolved therein if necessary, and the oxidizing agent is added dropwise thereto. Do.

Although the reaction molar ratio of the oxidizing agent to cyclohexenylmethyl (meth) acrylate is theoretically 1/1, in the method of the present invention, it is in the range of 0.1 to 10, preferably in the range of 0.5 to 10,
More preferably, the range is 0.8 to 1.5.

When the molar ratio of the oxidizing agent to cyclohexenylmethyl (meth) acrylate exceeds 10, the conversion of cyclohexenylmethyl (meth) acrylate and the reaction time are shortened,
Although it is preferable in terms of reduction of loss due to polymerization of (meth) acrylate, it has disadvantages such as side reactions due to excess oxidizing agent, selectivity of oxidizing agent, and large cost in recovering unreacted oxidizing agent. is there.

Conversely, when the molar ratio of the reaction between the oxidizing agent and cyclohexenylmethyl (meth) acrylate is 0.1 or less, it is preferable in terms of the selectivity of the oxidizing agent, the conversion, and the suppression of side reactions caused by the oxidizing agent. There are drawbacks such as loss due to polymerization of acrylate, and high cost in recovering unreacted cyclohexenyl (meth) acrylate.

The reaction temperature is lower than the upper limit such that the epoxidation reaction takes precedence over the decomposition reaction of the oxidizing agent.For example, when peracetic acid is used, the reaction temperature is 70 ° C or lower, and when tertiary butyl hydroperoxide is used, the temperature is 150 ° C or lower. preferable.

If the reaction temperature is low, it takes a long time to complete the reaction. Therefore, when peracetic acid is used, the reaction is preferably performed at a lower limit of 0 ° C. or tertiary butyl hydroperoxide at 20 ° C. or more.

In addition, during the epoxidation reaction, an organic acid due to a by-product from the oxidizing agent, an alcohol, and a side reaction in which the epoxy group is opened with water occurs. Select from the appropriate temperature range.

The reaction pressure is generally operated under normal pressure, but it can also be carried out under elevated or low pressure.

 The reaction can also be performed in the presence of a solvent.

The reaction in the presence of a solvent is preferable because it has the effects of lowering the viscosity of the reaction crude liquid and stabilizing by diluting the oxidizing agent.

Examples of the solvent used include aromatic compounds such as benzene, toluene and xylene, halides such as chloroform, dimethyl chloride, carbon tetrachloride, and chlorobenzene; esterified compounds such as ethyl acetate and butyl acetate; ketone compounds such as acetone and methyl ethyl ketone. 1,
An ether compound such as 2-dimethoxyethane can be used.

The amount of the solvent used is preferably 0.5 to 5 times the amount of cyclohexenylmethyl (meth) acrylate.

When the amount is less than 0.5 times, the effect of stabilization by diluting the oxidizing agent is small. Conversely, when the amount is more than 5 times, the stabilizing effect does not increase so much and a large cost is required for solvent recovery. So it's wasted.

When performing the epoxidation reaction as described above, a specific polymerization inhibitor must be used in combination with the molecular oxygen-containing gas.

Air is usually used as molecular oxygen and is blown into the reactor.

A predetermined effect can be obtained by blowing directly into the liquid or into the gas phase.

The blowing amount can be arbitrarily selected, but if it is too large, solvent loss is not preferred.

In addition, nitrogen is usually blown into the system together with air to avoid the formation of an explosive mixture in the system. In this case, the oxygen concentration in the blown gas is 0.01% (by volume) or more, preferably 3%. (Capacity) or more. The higher the oxygen concentration, the better the effect, but the upper limit is the lower limit oxygen concentration under explosion in the system, and the value varies depending on the solvent used.

Nitrogen injection is not always required to be at the same position as air, but it is important for safety to take measures on equipment so that explosive air-fuel mixture is not locally formed in the system.

The reaction is carried out continuously or batchwise. In the case of continuous reaction, a piston flow type is preferred.

The same applies to the case of the batch system, but the semi-batch system in which the oxidizing agent is charged sequentially is desirable.

After the reaction is completed, the crude epoxidation reaction solution can be purified by removing a solvent, a low-boiling substance, unreacted raw materials, a catalyst, etc., neutralizing, treating with an adsorbent or an ion exchange resin, or the like.

In particular, when an organic peracid is used as the oxidizing agent, it is preferable that the reaction crude liquid is washed with neutralized water.

This is because polymerization is extremely easy if low boiling components such as a solvent are removed without neutralization.

As an aqueous alkaline solution used for neutralization, for example, NaOH,
An aqueous solution of an alkaline substance such as KOH, K ₂ CO ₃ , Na ₂ CO ₃ , NaHCO ₃ , KHCO ₃ , NH ₃ and the like can be used.

The concentration at the time of use can be freely selected within a wide range.

From the viewpoint of liquid separation, it is preferable to use an aqueous solution of NaOH, an aqueous solution of Na ₂ CO _{3, or an} aqueous solution of NaHCO ₃ .

The neutralization and washing with water are preferably performed at a temperature in the range of 10 to 90 ° C, preferably 10 to 50 ° C.

In the neutralized water washing step, it is important to remove the residual organic peracid while neutralizing and removing the organic acid.

In order to operate the following low boiling point component removing step stably,
It is necessary to repeatedly wash with neutralized water until the residual organic peracid content in the neutralized upper layer solution becomes 0.1% or less, preferably 0.01% or less.

Therefore, when washing with neutralized water in a continuous manner, it becomes a multi-stage type,
Usually, if the number of stages is 3 to 5, the concentration of the organic peracid can be reduced to a specified value or less.

In the case of a multi-stage system, it is preferable that the final stage be completely washed with water or an alkaline aqueous solution of at most about 1%.

This is because, in the case where the bottom liquid after removing the low-boiling components is converted into a product as it is, the ant metal is mixed into the product and affects the quality.

The same applies to the case where the neutralization is repeated in batches. When the neutralized water is washed in a continuous manner, it is not problematic to use the lower layer water for pre-neutralization in a countercurrent manner, and it is more economical.

The amount of alkali used in the neutralized water washing is 0.5 to 3 times, preferably 1.1 to 1.5 times, the equivalent ratio to the total amount of the organic peracid and the organic acid in the reaction crude liquid. Increasing the amount is not economical.

In addition, if the equivalent ratio is reduced more than necessary, a large amount of water is required to remove the organic peracid or the organic acid, so it is not advisable, and the loss of dissolution in lower water such as a solvent increases.

The point of the present invention is to add a specific coloring inhibitor.

As an example of the organic phosphorus compound represented by the general formula (III) in the present invention, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (for example, HCA manufactured by Sanko Chemical Co., Ltd.) 6.8-Dichloro-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-
Oxide, 6,8-di- (tert-butyl) -9,10
-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and the like, and the organic phosphorus compound represented by the general formula (IV) is a hydrate thereof.

The amount of the coloring inhibitor used is determined by the general formula (II) in the neutralized upper layer solution.
It is essential to add 0.001 to 1 part of the organic phosphorus compound represented by the general formula (III) or (IV) to 100 parts of the compound, preferably in the range of 0.01 part to 0.2 part, more preferably 0.01 part. It is in the range of 0.1 part.

If the amount is too small, the coloring prevention efficiency is poor. If the amount is too large, not only is it economically disadvantageous, but also the epoxy group is opened, which is not preferable.

The addition position may be in the neutralized upper layer liquid before the de-boiling or in the bottom liquid after the de-boiling.

The addition method may be a powder as it is, or may be added after being dissolved in a solvent.

The reaction is carried out continuously or batchwise. In the case of continuous reaction, a piston flow type is preferred.

 After the neutralizing washing step, the solvent is removed.

A thin film evaporator is usually used for low boiling removal, but the heating temperature is preferably 50 to 180 ° C, preferably 60 to 100 ° C, from the viewpoint of preventing polymerization.

The pressure can be arbitrarily selected depending on the physical properties of the low-boiling components, but it is common practice to operate under reduced pressure in relation to the heating temperature.

The place where the molecular oxygen is introduced into the evaporator can be arbitrarily selected, but is usually blown from the line from which the bottom liquid distills.

The injection amount can be selected arbitrarily, but the upper limit is naturally determined from the viewpoint of the vacuum system capacity, whether the bottom liquid flows down stably, or the recovery loss when collecting the distilled low-boiling components with a condenser. Limited. A product having a purity of 94 to 96% can be obtained from the bottom liquid obtained in the de-boiling step.

<< Effect of the Invention >> As a result of the present invention, the product obtained in this way has a hue (APHA) of 40 to 60, but is hardly colored even if stored for 3 months.

It is thought that the application range of the compound of the general formula (II) is expanded by such a great improvement in the coloring of the product.

Hereinafter, the effects of the present invention will be described in more detail using examples.

Example 1 Cyclohexenylmethyl methacrylate was placed in a 15-volume glass reactor equipped with a stirrer and a cooling jacket.
1500 g, ethyl acetate 5500 g, hydroquinone monomethyl ether 0.45 gr, sodium 2-ethylhexyl tripolyphosphate 4.5 g were added, and a gas mixture of oxygen / nitrogen (10/90% by volume) was blown at 32 Nl / Hr from the insertion tube into the reactor. I was crowded.

Then, the reaction temperature was maintained at 40 ° C., and 30% peracetic acid solution 2593 gr
Was charged with a metering pump over 4 hours.

After completion of the charging, the reaction was terminated after further aging for 5 hours [the above was the synthesis step].

After cooling the reaction crude solution to room temperature, 10% NaOH
After stirring for 30 minutes, the mixture is allowed to stand for 30 minutes to separate the layers.

After removing the lower layer water, the same operation is performed by adding 4125 gr of 10% NaOH.

At this time, the concentration of residual peracetic acid in the upper layer solution was 0.02%, and acetic acid had completely disappeared.

Then, 0.5% NaOH (7600 gr) was added, and the same operation was performed. As a result, the peracetic acid concentration was 0.01% or less (the above was a neutralization step).

0.45 g of hydroquinone monomethyl ether was added to 5.93 kg of the neutralized upper layer solution, and the mixture was subjected to deboiling with a SUS Smith thin film evaporator.

The operating conditions were as follows: a heating temperature of 60 ° C. and a pressure of 150 mmHg, a mixed gas of oxygen / nitrogen (10/90 vol.
Injected at 2Nl / Hr.

A gas mixture of oxygen / nitrogen (10/90% by volume) was blown into the bottom liquid at a heating temperature of 60 ° C. and a pressure of 40 mmHg from the bottom liquid distillation line at 32 Nl / Hr.

 The obtained amount of the bottom liquid was 1480 g.

Further, the composition was examined by gas chromatography analysis. The result was 96.2% of MHTHB and the color of APHA was 40 [the above was the deboiling step].

To this product, 1.4 gr of HCA as a coloring inhibitor was added and stored at 30 ° C.

 The hue after 3 months was 50 by APHA.

Comparative Example-1 The bottom liquid obtained in the same manner as in Example-1 was stored at 30 ° C without adding HCA.

 The hue after 3 months was 400 by APHA.

Example 2 Cyclohexenyl methyl acrylate 15 was placed in a 15-volume glass reactor equipped with a stirrer and a cooling jacket.
00 g, 5500 g of ethyl acetate, 0.45 gr of hydroquinone monomethyl ether and 4.5 g of sodium 2-ethylhexyl tripolyphosphate were added, and a mixed gas of oxygen / nitrogen (10/90% by volume) was blown at 32 Nl / Hr from the insertion tube into the reactor. I was crowded.

Then, the reaction temperature was maintained at 40 ° C., and 30% peracetic acid solution 2812 gr
Was charged with a metering pump over 4 hours. After the preparation,
After further aging for 5 hours, the reaction was terminated (the above was the synthesis step).

After the reaction crude liquid was cooled to room temperature,
After stirring for 30 minutes, the mixture is allowed to stand for 30 minutes to separate the layers.

After removing the lower layer water, the same operation is performed by further adding 5000 gr of 10% NaOH.

At this time, the concentration of residual peracetic acid in the upper layer solution was 0.02%, and acetic acid had completely disappeared.

Next, 5000% of 1% NaOH was added and the same operation was carried out. As a result, the peracetic acid concentration was 0.01% or less [the above was a neutralization step].

0.45 g of hydroquinone monomethyl ether was added to 6060 kg of the neutralized upper layer solution, and the mixture was deboiling-reduced with a SUS Smith thin film evaporator.

The operating conditions were as follows: a heating temperature of 60 ° C. and a pressure of 150 mmHg, a mixed gas of oxygen / nitrogen (10/90 vol.
Injected at 2Nl / Hr.

A gas mixture of oxygen / nitrogen (10/90% by volume) was blown into the bottom liquid at a heating temperature of 60 ° C. and a pressure of 40 mmHg from the bottom liquid distillation line at 32 Nl / Hr.

 The obtained amount of the bottom liquid was 1480 g.

Further, the composition was examined by gas chromatography analysis, and it was found that AETB was 96.2% and the hue was 70 by APHA [the above was the deboiling step].

This product was subjected to adsorption treatment with Kyoward 1000 (Kyowa Chemical Industry Co., Ltd.) having a structural formula of Mg _4.5 Al ₂ (OH) ₁₃ CO ₃ · 3.5 H ₂ O, and as a result, the hue was 30 with APHA.

To this product, 1.4 gr of HCA as a coloring inhibitor was added and stored at 30 ° C.

 After 3 months, the hue was 30 at APHA.

Comparative Example-2 BHT, which is an antioxidant, was added to the bottom solution obtained in the same manner as in Example-2, instead of HCA, and stored at 30 ° C.

 The hue after 3 months was 150 for APHA.

Comparative Example-3 The bottom liquid obtained in the same manner as in Example-2 was stored at 30 ° C without adding HCA.

 The hue after 3 months was 180 at APHA.

Claims (1)

(57) [Claims] 1. The compound of the general formula (I) [Wherein R represents a hydrogen atom or a methyl group] The cyclohexenylmethyl (meth) acrylate compound represented by the following formula is epoxidized with an oxidizing agent to obtain a compound represented by the general formula (II): [Wherein R represents a hydrogen atom or a methyl group] In the process of producing a compound having both an epoxy group and a (meth) acrylate group represented by the following formula: [However, in the formula (III), R ^{1 to} R ⁸ are hydrogen, halogen, or a monovalent aliphatic or aromatic substituent having 1 to 10 carbon atoms, and R ^{1 to} R ⁸ may be the same or different. Coloring of a compound having both an epoxy group and a (meth) acrylate group, characterized in that 0.001 to 1 part of the phosphaphenanthrene compound represented by the formula (1) is allowed to coexist with 100 parts of the compound (II). How to prevent