JP4961176B2 - Polymerization inhibitor for (meth) acrylic acid ester having oxygen-containing alcohol residue and mixture of (meth) acrylic acid ester - Google Patents

Description

  The present invention relates to a polymerization inhibitor for (meth) acrylic acid ester having an oxygen-containing alcohol residue and a mixture of the (meth) acrylic acid ester.

  (Meth) acrylic acid ester is a compound having various uses as a raw material monomer for various polymers and copolymers. Since (meth) acrylic acid ester has the property of being very easily polymerized, it causes polymerization troubles due to factors such as heat and light during its production, distillation, storage, and transportation. In particular, (meth) acrylic acid ester having an oxygen-containing alcohol residue such as 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, glycidyl methacrylate, glycidyl acrylate, etc. is very polymerized compared to other (meth) acrylic acid esters. Polymerization trouble is likely to occur during production and distillation.

In order to suppress polymerization troubles, polymerization prevention methods using various polymerization inhibitors have been proposed. As a polymerization inhibitor used in the production of (meth) acrylic acid esters, for example, compounds having an N-oxyl radical structure as shown below are known.
(I) 2,2,6,6-tetramethyl-4-hydroxypiperidine-N-oxyl, 2,2,6,6-tetramethyl-4-benzoyloxypiperidine-N-oxyl (Patent Document 1).
(Ii) 4-acetylamino-2,2,6,6-tetramethylpiperidine-N-oxyl (Patent Document 2).
(Iii) Bis (2,2,6,6-tetramethyl-N-oxylpiperidyl) succinate (Patent Document 3).
(Iv) 1-oxyl-2,2,6,6-tetramethyl-4- (2,3-dihydroxypropoxy) piperidine, 1-oxyl-2,2,6,6-tetramethyl-4-glycidyloxypiperidine Etc. (Patent Document 4).

However, an effective polymerization inhibitor for a (meth) acrylic acid ester having an oxygen-containing alcohol residue that is very easily polymerized has not been known. Therefore, a large amount of polymerization inhibitor is usually used for the (meth) acrylic acid ester having an oxygen-containing alcohol residue.
Patent Document 4 describes the use of 1-oxyl-2,2,6,6-tetramethyl-4-glycidyloxypiperidine as a polymerization inhibitor for acrylate and methacrylate. However, the only compounds exemplified as acrylates and methacrylates are butyl acrylate, methyl methacrylate, ethyl acrylate, methyl acrylate. Moreover, an Example is only acrylic acid and there is no Example of a methacrylate and an acrylate. Thus, there is no description about the effectiveness with respect to the (meth) acrylic acid ester which has an oxygen-containing alcohol residue.
JP-A-56-38301 JP-A-8-59524 Japanese Patent No. 3209607 JP-T-2002-520379

  Therefore, an object of the present invention is to provide a polymerization inhibitor, a mixture, and a polymerization prevention method capable of sufficiently suppressing the polymerization of a (meth) acrylic acid ester having an oxygen-containing alcohol residue even when added in a small amount. There is.

  The polymerization inhibitor for (meth) acrylic acid ester having an oxygen-containing alcohol residue of the present invention is a polymerization inhibitor used for suppressing polymerization of a compound represented by the following formula (1), and has the following formula ( It is a compound represented by 2).

However, R ¹ represents a hydrogen atom or a methyl group, R ² represents an alcohol residue having 2 to 6 carbon atoms with an alcohol residue or an epoxy group, having 2 to 6 carbon atoms having a hydroxy group.

However, R < ³ >, R < ⁴ > and R < ⁵ > represent a hydrogen atom or a methyl group each independently.

Mixtures of the present invention, a compound represented by the formula (1), seen containing a compound represented by the formula (2), the content of the compound represented by formula (2), the formula (1 It is 0.0001-5 mass parts with respect to 100 mass parts of compounds represented by this.

According to the polymerization inhibitor for (meth) acrylic acid ester having an oxygen-containing alcohol residue of the present invention, the polymerization of the compound represented by the formula (1) can be sufficiently suppressed even with a small amount of addition. it can.
In the mixture of the present invention, polymerization of the compound represented by the formula (1) can be sufficiently suppressed even if the amount of the compound represented by the formula (2) is small.

Hereinafter, the compound represented by Formula (1) is referred to as Compound (1). The same applies to compounds represented by other formulas.
In this specification, (meth) acrylic acid ester means methacrylic acid ester or acrylic acid ester.
In the present specification, an alcohol residue means a group obtained by removing one hydroxy group from an alcohol.
In the present specification, in the (meth) acrylic acid ester having an oxygen-containing alcohol residue, a carbon atom of an organic group containing oxygen is bonded to an oxygen atom of an acryloyloxy group or a methacryloyloxy group (meth). It means acrylic acid ester.

<Polymerization inhibitor>
The (meth) acrylic acid ester polymerization inhibitor having an oxygen-containing alcohol residue of the present invention (hereinafter referred to as a polymerization inhibitor) is a polymerization inhibitor used for suppressing the polymerization of the compound (1). Compound (2).

However, R ¹ represents a hydrogen atom or a methyl group, R ² represents an alcohol residue having 2 to 6 carbon atoms with an alcohol residue or an epoxy group, having 2 to 6 carbon atoms having a hydroxy group.

However, R < ³ >, R < ⁴ > and R < ⁵ > represent a hydrogen atom or a methyl group each independently.

  Examples of the alcohol residue having 2 to 6 carbon atoms containing one or more oxygen atoms include an alcohol residue having 2 to 6 carbon atoms having a hydroxy group, an alcohol residue having 2 to 6 carbon atoms having an epoxy group, and an alkoxy group. And an alcohol residue having 2 to 6 carbon atoms, an alcohol residue having 2 to 6 carbon atoms having a cyclic ether, and the like.

  Specific examples of the compound (1) include 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, glycidyl methacrylate, glycidyl acrylate, 3-methyl-3-methoxybutyl methacrylate, 3-methyl- 3-methoxybutyl acrylate, 2-methoxyethyl methacrylate, 2-methoxyethyl acrylate, 2-ethoxyethyl methacrylate, 2-ethoxyethyl acrylate, 4-hydroxybutyl methacrylate, 4-hydroxybutyl acrylate, 6-hydroxyhexyl methacrylate, 6- Hydroxyhexyl acrylate, tetrahydrofurfuryl methacrylate, tetrahydrofurfuryl acrylate, furfuryl Methacrylate, furfuryl acrylate, and the like.

  Compound (2) can be obtained by reacting compound (3) represented by the following formula (3) with epichlorohydrin in the presence of a basic compound such as sodium hydroxide.

However, R < ³ >, R < ⁴ > and R < ⁵ > are synonymous with Formula (2).

  Examples of basic compounds include alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal carbonates, alkali metal alkoxides, tertiary amines, pyridines, anion exchangers, and the like. In view of the purity of 2), an alkali metal hydroxide is particularly preferable. A basic compound may be used individually by 1 type, and may use 2 or more types together.

  The amount of epichlorohydrin is preferably 0.1 to 10 moles, more preferably 0.3 or more moles, and more preferably 0.5 or more moles with respect to the compound (3). preferable. The amount of epichlorohydrin is more preferably 8 times mol or less and further preferably 5 times mol or less with respect to the compound (1) from the viewpoint of side reaction inhibition and operability.

  The amount of the basic compound is preferably 0.1 to 10 moles, more preferably 0.3 or more moles, and even more preferably 0.5 or more moles, from the viewpoint of productivity. . The amount of the basic compound is more preferably 8 times mol or less and further preferably 5 times mol or less with respect to the compound (3) from the viewpoint of side reaction suppression and operability.

  A solvent may be used in the reaction. Examples of the solvent include formamide, N-methylformamide, N, N-dimethylformamide, dioxane, tetrahydrofuran, benzene, toluene, xylene, diethyl ether, acetone, methyl ethyl ketone, methyl isobutyl ketone and the like.

The amount of the solvent is preferably 0 to 1000 times the mass of the compound (3). The amount of the solvent is more preferably 100 times by mass or less, and even more preferably 50 times by mass or less with respect to the compound (3) from the viewpoint of the reaction rate and the amount of waste solvent.
The reaction solution may contain a small amount of water. The amount of water is preferably 0.1 times or less, more preferably 0.02 times or less, with respect to the reaction solution, from the viewpoint of the selectivity of the compound (3). The amount of water includes water contained in the raw material.

The reaction temperature is preferably 0 ° C. or higher and lower than the boiling point of the reaction solution. From the viewpoint of productivity, the reaction temperature is more preferably 10 ° C or higher, further preferably 20 ° C or higher, and particularly preferably 40 ° C or higher. The reaction temperature is more preferably 120 ° C. or lower, more preferably 100 ° C. or lower, and particularly preferably 80 ° C. or lower from the viewpoint of suppressing the formation of by-products.
The reaction time is preferably about 2 to 48 hours.

After completion of the reaction, the compound (2) is recovered by operations such as cooling, concentration and extraction, and purified by distillation or the like as necessary.
Examples of the extraction solvent include benzene, toluene, xylene, diethyl ether, methyl ethyl ketone, and methyl isobutyl ketone.
Compound (2) may be purified by a known method such as washing with water, an organic solvent, etc., solvent fractionation, ion exchange chromatography, recrystallization, electrodialysis, etc., if necessary.

  For example, in the case of 1-oxyl-2,2,6,6-tetramethyl-4-glycidyloxypiperidine, 1-oxyl-2,2,6,6-tetramethyl-4-hydroxypiperidine and epichlorohydrin are added. Obtained by reaction.

<Mixture>
The mixture of the present invention is a mixture containing compound (1) and compound (2).
As the compound (1), a compound in which an alcohol residue having 2 to 6 carbon atoms has a hydroxy group or an epoxy group is particularly preferable from the viewpoint that the polymerization inhibiting effect by the compound (2) is remarkably exhibited. A compound (1) may be used individually by 1 type, and may use 2 or more types together.

  The content of the compound (2) is preferably 0.0001-5 parts by mass, more preferably 0.0002-4 parts by mass, and further 0.0003-3 parts by mass with respect to 100 parts by mass of the compound (1). preferable. A compound (2) may be used individually by 1 type, and may use 2 or more types together.

The mixture of the present invention may contain other polymerization inhibitor.
Other polymerization inhibitors include, for example, phenolic compounds such as hydroquinone and p-methoxyphenol; N, N′-diisopropyl-p-phenylenediamine, N-phenyl-N ′-(1,3-dimethylbutyl)- amine compounds such as p-phenylenediamine and phenothiazine; 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine-N N-oxyl compounds such as -oxyl and 4-acetamino-2,2,6,6-tetramethylpiperidine-N-oxyl. Another polymerization inhibitor may be used individually by 1 type, and may use 2 or more types together.
The content of the other polymerization inhibitor is preferably 10,000 to 0.01 parts by mass, more preferably 8000 to 0.02 parts by mass, and 7000 to 0.03 parts by mass with respect to 100 parts by mass of the compound (2). Further preferred.

<Method for preventing polymerization>
The method for preventing polymerization of a (meth) acrylic acid ester having an oxygen-containing alcohol residue according to the present invention (hereinafter referred to as a polymerization preventing method) is a method in which compound (1) is allowed to coexist with compound (2). Specifically, the following methods are mentioned.
(A) A method in which compound (2) is allowed to coexist during the production of compound (1).
(B) A method in which the compound (2) is allowed to coexist during the distillation of the compound (1).
(C) A method in which compound (2) is allowed to coexist during storage or transportation of compound (1).

Examples of the method (a) include a method of adding the compound (2) to the raw material of the compound (1), a method of introducing the compound (2) into the reactor during the reaction of the raw material of the compound (1), and the like. It is done.
Examples of the method (b) include a method in which the compound (2) is previously added to the compound (1), a method in which the compound (2) is introduced into a distillation kettle or a rectifying column in the distillation step, and the like. .
Examples of the method (c) include a method of adding the compound (2) to the reaction product of the starting material of the compound (1), a method of adding the compound (2) to the purified compound (1), and the like.

  As a method for adding the compound (2), an addition method suitable for the compound (1) to be applied and the production process to be applied may be selected from known methods. For example, a method of adding as a solid, a method of adding by dissolving in a solvent, a method of adding by dissolving in a raw material, and the like can be mentioned.

  The amount of the compound (2) added depends on the compound (1) to be applied, the production process to be applied and the like, and thus cannot be determined unconditionally. However, in the methods (a) to (c), the compound (1) 100 0.0001-5 mass parts is preferable with respect to mass parts, 0.0002-4 mass parts is more preferable, and 0.0003-3 mass parts is still more preferable. A compound (2) may be used individually by 1 type, and may use 2 or more types together.

In the polymerization prevention method of the present invention, another polymerization inhibitor may be added. Other polymerization inhibitors are stable under the conditions of the production process of the compound (1), thermally stable under the conditions of the distillation process of the compound (1), and the compound (1) side in the distillation process. A polymerization inhibitor having a high boiling point that does not distill into the water is preferred.
Examples of other polymerization inhibitors include the other polymerization inhibitors described above. Another polymerization inhibitor may be used individually by 1 type, and may use 2 or more types together.

  When the compound (1) is allowed to coexist with the compound (2) and, if necessary, another polymerization inhibitor, at the same time, air bubbling may improve the polymerization inhibiting effect.

As described above, in the polymerization inhibitor of the present invention, the polymerization of the compound (1) can be sufficiently suppressed even with a small amount of addition. The polymerization inhibitor of the present invention is suitable as a polymerization inhibitor used in the production of compound (1), distillation, storage, transportation and the like.
Moreover, in the mixture of the present invention, the polymerization of the compound (1) can be sufficiently suppressed even if the amount of the compound (2) is small. By using the mixture of the present invention, long-term storage is possible without deteriorating the quality of the compound (1).
In the polymerization prevention method of the present invention, even when the amount of the compound (2) is small, the polymerization of the compound (1) can be sufficiently suppressed, and the compound (1) having excellent quality can be provided. .

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.
[Synthesis Example 1]
Synthesis of 1-oxyl-2,2,6,6-tetramethyl-4-glycidyloxypiperidine:

  Into a nitrogen-substituted three-necked flask, 200 g of toluene, 172 g (1.0 mol) of 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (hereinafter referred to as HO) were placed, and 70 ° C. And stirred with heating. To this, 185 g (2.0 mol) of epichlorohydrin was added dropwise and stirred for 1 hour, then the temperature was lowered to 60 ° C., and 100 g (1.2 mol) of 48% aqueous sodium hydroxide solution was added. Stir for 4 hours. Next, 300 g of water was added to the reaction system, and the separated upper layer was washed with water, dried and concentrated under reduced pressure. The crude crystals thus obtained were recrystallized with cyclohexane to give 169 g of 1-oxyl-2,2,6,6-tetramethyl-4-glycidyloxypiperidine (hereinafter referred to as GE-HO) ( 0.74 mol) was obtained.

[Example 1]
10 g of 2-hydroxyethyl methacrylate (hereinafter referred to as HEMA) to which 0.44 mmol / L of GE-HO was added was weighed into an ampule tube, the ampule tube was sealed, and heat treatment was performed in a 100 ° C. oil bath. The time until the polymerization was started was measured. The start of polymerization was judged visually. The results are shown in Table 1.

[Comparative Example 1]
The test was performed in the same manner as in Example 1 except that the compound GE-HO was changed to HO. The results are shown in Table 1.

[Comparative Example 2]
The test was conducted in the same manner as in Example 1 except that the compound GE-HO was changed to 4-benzoyloxy-2,2,6,6-tetramethylpiperidine-N-oxyl (hereinafter referred to as BZO). The results are shown in Table 1.

[Comparative Example 3]
The test was performed in the same manner as in Example 1 except that the compound GE-HO was changed to 4-acetamino-2,2,6,6-tetramethylpiperidine-N-oxyl (hereinafter referred to as AA). The results are shown in Table 1.

[Comparative Example 4]
The same as Example 1 except that the compound GE-HO was changed to 1-oxyl-2,2,6,6-tetramethyl-4- (2,3-dihydroxypropoxy) piperidine (hereinafter referred to as HP). Tested. The results are shown in Table 1.

[Example 2]
The test was conducted in the same manner as in Example 1 except that HEMA was changed to glycidyl methacrylate (hereinafter referred to as GMA). The results are shown in Table 1.

[Comparative Example 5]
The test was performed in the same manner as in Example 2 except that the compound GE-HO was changed to HO. The results are shown in Table 1.

[Reference Example 1]
The test was conducted in the same manner as in Example 1 except that HEMA was changed to n-butyl methacrylate (hereinafter referred to as BMA). The results are shown in Table 1.

[Reference Example 2]
The test was conducted in the same manner as in Example 1 except that HEMA was changed to methacrylic acid (hereinafter referred to as MAA). The results are shown in Table 1.

[Reference Example 3]
The test was conducted in the same manner as in Example 1 except that HEMA was changed to BMA and compound GE-HO was changed to HO. The results are shown in Table 1.

[Reference Example 4]
The test was conducted in the same manner as in Example 1 except that HEMA was changed to BMA and compound GE-HO was changed to HP. The results are shown in Table 1.

  Examples 1 and 2 using the compound GE-HO for (meth) acrylic acid ester (HEMA, GMA) having an oxygen-containing alcohol residue are compared to Comparative Examples 2 to 5 using other polymerization inhibitors. The effect of increasing the time until the start of polymerization by about 4 to 5 times was observed. Since there is almost no difference between Reference Example 1 using the compound GE-HO with respect to other (meth) acrylic acid esters (BMA) and Reference Examples 3 and 4 using other polymerization inhibitors, The effect of combining the (meth) acrylic acid ester having an alcohol residue with the compound (2) is based on the specific combination of the (meth) acrylic acid ester and the polymerization inhibitor described in Patent Document 4. This is a remarkable effect that cannot be predicted.

According to the polymerization inhibitor, the mixture and the polymerization prevention method of the present invention, it is possible to suppress polymerization troubles during the production and distillation of the compound (1) which is very easily polymerized as compared with other (meth) acrylic acid esters.

Claims (2)

A polymerization inhibitor used for suppressing polymerization of a compound represented by the following formula (1),
The polymerization inhibitor which is a compound represented by following formula (2).

However, R ¹ represents a hydrogen atom or a methyl group, R ² represents an alcohol residue having 2 to 6 carbon atoms with an alcohol residue or an epoxy group, having 2 to 6 carbon atoms having a hydroxy radical, R ³ , R ⁴ and R ⁵ each independently represents a hydrogen atom or a methyl group. A compound represented by the following formula (1);
Look containing a compound represented by the following formula (2), the content of the compound represented by formula (2) is the compound 100 parts by weight of the formula (1), 0.0001 A mixture that is part by weight .

However, R ¹ represents a hydrogen atom or a methyl group, R ² represents an alcohol residue having 2 to 6 carbon atoms with an alcohol residue or an epoxy group, having 2 to 6 carbon atoms having a hydroxy radical, R ³ , R ⁴ and R ⁵ each independently represents a hydrogen atom or a methyl group.