JP3351497B2 - Method for preventing polymerization of vinyl compounds - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing polymerization of a vinyl compound, and more particularly, to a method for preventing the polymerization of a vinyl compound, particularly in a distillation system in a production process of acrylic acid or methacrylic acid, etc. On the other hand, the present invention relates to a method for preventing polymerization of a vinyl compound, which effectively suppresses the polymerization, prevents corrosion of equipment, and enables stable long-term continuous operation.

[0002]

2. Description of the Related Art Vinyl compounds such as styrene, acrylic acid, methacrylic acid, acrylates, methacrylates, and acrylonitrile are known to have a property of being easily polymerized by light or heat. In the production process of these vinyl compounds, various distillation operations are performed in order to separate and collect a desired vinyl compound, concentrate, or purify. However, since the vinyl compound is polymerized by light or heat to form a polymeric substance as described above, it causes various troubles in the distillation step, and makes stable continuous operation for a long period of time impossible. Not easy to bring about. Therefore, in order to avoid such a situation, a method of performing a distillation operation in the presence of a polymerization inhibitor has been employed. As the polymerization inhibitor, for example, hydroquinone, methoquinone (p-methoxyphenol), pt-butylcatechol, t-butylhydroquinone, phenothiazine and the like are used. However, acrylic acid, methacrylic acid, and the like are compounds that are extremely easily polymerized, and in fact, these polymerization inhibitors do not always provide a sufficient effect. by the way,
It is known that copper dibutyldithiocarbamate exhibits an excellent polymerization inhibitory effect on a liquid phase portion of acrylic acid or methacrylic acid. However, the effect of the polymerization inhibitor, such as copper dibutyldithiocarbamate, on the gas-phase condensation section is small or hardly effective. Further, the copper dibutyldithiocarbamate is
It has a drawback of corroding equipment (for example, material SUS316), and has been difficult to use in industrial plants.

[0003]

SUMMARY OF THE INVENTION Under such circumstances, the present invention provides a method for producing a vinyl compound, particularly acrylic acid or methacrylic acid, in a distillation system or the like in both a liquid phase part and a gas phase condensation part. On the other hand, an object of the present invention is to provide a method for preventing polymerization of a vinyl compound, which effectively suppresses the polymerization, prevents corrosion of equipment, and enables stable long-term continuous operation.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, a metal salt of dialkyldithiocarbamic acid represented by copper dibutyldithiocarbamate has been obtained with respect to the liquid phase. Focusing on showing an excellent polymerization inhibitory effect, by using this and N-nitrosophenylhydroxylamine and its salt in combination, it shows an excellent polymerization inhibitory effect on both the liquid phase part and the gaseous phase condensation part I found that. And it discovered that corrosion of an apparatus can be suppressed effectively by further coexisting an inorganic acid, an inorganic acid salt, and water. The present invention has been completed based on such findings. That is, in the present invention, in preventing the polymerization of a vinyl compound using a metal dialkyldithiocarbamate in a process for producing a vinyl compound, the present invention relates to (B) N-nitrosophenylhydroxylamine and / or (B) together with (A) a metal dialkyldithiocarbamate. Another object of the present invention is to provide a method for preventing polymerization of a vinyl compound, which comprises using a salt thereof and (C) at least one selected from inorganic acids, inorganic acid salts and water.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION As the vinyl compound to which the method of the present invention can be applied, for example, styrene, acrylic acid, methacrylic acid, acrylic ester, methacrylic ester,
Acrylonitrile and the like, among these,
Particularly, acrylic acid and methacrylic acid are preferred. In the present invention, as a polymerization inhibitor of the vinyl compound,
Component (A), that is, a metal salt of dialkyldithiocarbamic acid is used. Examples of the metal salt of dialkyldithiocarbamic acid include, for example, those represented by the general formula (I)

[0006]

Embedded image

The compound represented by the following formula can be used.
In the general formula (I), R ¹ and R ² are an alkyl group having 1 to 8 carbon atoms or a phenyl group, respectively. The alkyl group having 1 to 8 carbon atoms may be linear or branched, and specific examples include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group. R ¹ and R ² may be the same or different. M represents a metal, such as nickel, zinc, copper, iron, and transition metals (Mn, Co, etc.).
n shows the valence of metal M.

The metal dialkyldithiocarbamate represented by the above formula (I) includes, for example, copper dimethyldithiocarbamate, copper diethyldithiocarbamate, copper dipropyldithiocarbamate, copper dibutyldithiocarbamate, copper dipentyldithiocarbamate, dihexyldithiocarbamate. Copper acid, copper diphenyldithiocarbamate, copper methylethyldithiocarbamate, copper methylpropyldithiocarbamate, copper methylbutyldithiocarbamate, copper methylpentyldithiocarbamate, copper methylhexyldithiocarbamate, copper methylphenyldithiocarbamate, copper ethylpropyldithiocarbamate, Copper ethyl butyldithiocarbamate, copper ethylpentyldithiocarbamate, copper ethylhexyldithiocarbamate, ethyl Copper enyldithiocarbamate, copper propylbutyldithiocarbamate, copper propylpentyldithiocarbamate, copper propylhexyldithiocarbamate, copper propylphenyldithiocarbamate, copper butylpentyldithiocarbamate, copper butylhexyldithiocarbamate, copper butylphenyldithiocarbamate, copper pentylhexyldithiocarbamate Copper, pentylphenyldithiocarbamate, copper hexylphenyldithiocarbamate, and the corresponding nickel salts, zinc salts, iron salts, and various transition metals (Mn, Co, etc.)
And the like. Among these dialkyldithiocarbamic acid metal salts, copper dialkyldithiocarbamate is preferred from the viewpoint of the effect, and copper dibutyldithiocarbamate is particularly preferred. This copper dibutyldithiocarbamate can be easily obtained as a commercial product.

The above metal salts of dialkyldithiocarbamic acids may be used alone or in combination of two or more. The amount used is not particularly limited and is appropriately selected depending on various circumstances, but is usually selected within the range of 0.001 to 5% by weight based on the vinyl compound. This amount is 0.
If the amount is less than 001% by weight, the effect of preventing polymerization in the liquid phase may not be sufficiently exhibited. On the other hand, if it exceeds 5% by weight, the effect is not improved for the amount, and it is rather economically disadvantageous in many cases. From the viewpoint of the polymerization prevention effect and economical efficiency in the liquid phase portion, the preferred amount of the metal dialkyldithiocarbamate used is in the range of 0.01 to 1% by weight, particularly 0.05 to 0% by weight, based on the vinyl compound. .5
A range of weight percent is preferred.

In the present invention, as a polymerization inhibitor, together with this metal salt of dialkyldithiocarbamic acid,
Component (B), that is, N-nitrosophenylhydroxylamine or a salt thereof is used. The kind of the salt is not particularly limited, but N-nitrosophenylhydroxylamine ammonium salt is preferable from the viewpoint of the effect. These N-nitrosophenylhydroxylamine and ammonium salts thereof can be easily obtained as commercial products. In the present invention, the above-mentioned N-nitrosophenylhydroxylamine and salts thereof may be used alone or in combination of two or more. The amount used may be appropriately selected, but is usually selected in the range of 0.01 to 10 times the weight of the metal dialkyldithiocarbamate. If the amount is less than 0.01 times by weight, the effect of preventing polymerization in the vapor-phase condensation section may not be sufficiently exhibited. On the other hand, if the weight exceeds 10 times, the effect is not improved for the amount, and it is often disadvantageous economically. From the viewpoints of polymerization prevention effect and economy in the gas-phase condensing section, the preferred amount of N-nitrosophenylhydroxylamine or a salt thereof is in the range of 0.05 to 1 times the weight of the metal dialkyldithiocarbamate. .

In the method of the present invention, the component (C), that is, at least one selected from the group consisting of inorganic acids, inorganic acid salts and water, is used as a corrosion inhibitor in order to suppress corrosion of equipment. . As the inorganic acid, oxo acid is preferable, and specific examples thereof include boric acid, phosphoric acid, nitric acid, and sulfuric acid. Among these, phosphoric acid and boric acid are preferable from the viewpoint of the effect, and phosphoric acid is particularly preferable. As the inorganic acid salts, nickel salts of these inorganic acids,
Zinc salts, iron salts, manganese salts, cobalt salts and the like. In the present invention, the corrosion inhibitor of component (C) may be used alone or in combination of two or more. In addition, the amount used depends on various situations,
Although it cannot be unambiguously determined, when an inorganic acid or an inorganic acid salt is used, it is usually selected in the range of 0.001 to 5% by weight based on the vinyl compound. If this amount is less than 0.001% by weight, the effect of inhibiting corrosion may not be sufficiently exhibited,
On the other hand, if it exceeds 5% by weight, the effect is not so much improved relative to the amount, and other inconveniences may occur. The amount of the inorganic acid or the inorganic acid salt is preferably in the range of 0.01 to 3% by weight with respect to the vinyl compound, because the corrosion is effectively suppressed and other disadvantages are not caused. A range of 0.03 to 1% by weight is preferred.

When phosphoric acid is particularly used as the corrosion inhibitor, the amount of phosphoric acid used is 0.01 or more (weight ratio) based on the above-mentioned metal dialkyldithiocarbamate, especially copper dialkyldithiocarbamate. , Especially 0.
It is preferably from 1 to 3 (weight ratio). On the other hand, when water is used as the corrosion-inhibiting substance, the amount of the water may be appropriately determined, but is usually selected in the range of 0.05 to 5% by weight based on the vinyl compound. If the amount is less than 0.05% by weight, the effect of inhibiting corrosion is not sufficiently exhibited. On the other hand, if it exceeds 5% by weight, a large energy cost is required for its separation, which may be economically disadvantageous. From the viewpoints of corrosion inhibition and economy, the preferred amount of water is in the range of 0.07 to 0.5% by weight based on the vinyl compound. In the method of the present invention, other known polymerization inhibitors, for example, hydroquinone, methoquinone (p-methoxyphenol), pt-
A phenolic polymerization inhibitor such as butyl catechol and t-butyl hydroquinone, phenothiazine and the like can be added. In the method of the present invention, there is no particular limitation on the method of supplying the components (A), (B) and (C). For example, (1) a method of supplying each component separately, and (2) (A) A) a method of supplying a mixed solution containing the components (B) and (C), (3) a method of supplying a mixed solution containing the components (A) and (B), and the method of supplying the component (C). And (4) a mixed solution containing the components (A) and (C) and a method for supplying the component (B), (5) a mixed solution containing the components (B) and (C), A method of supplying the component (A) can be used.

In the above method (1), (A)
It is desirable to supply the components and to supply the components (B) and (C) in the presence thereof. At this time, the component (B) and the component (C)
The order of supplying the components is not particularly limited. In the method (2), the components (A) and (C) are added to an appropriate amount of a vinyl compound to which the present invention is applied.
It is desirable to add the components or first add the component (A), and then add the components (B) and (C) to prepare a mixture. In the method (3), first, the component (A) is added to an appropriate amount of the vinyl compound, and then the component (B) is added to prepare a mixed solution. It is desirable to supply the component (C) in the presence of the component (A) and the component (B). In the method (4), after a component (A) and a component (C) are added to an appropriate amount of the vinyl compound to prepare a mixed solution,
It is desirable to supply this mixed solution into the system, and to supply the component (B) in the presence of the components (A) and (C). Further, in the method (5), first, the component (A) is supplied into the system, and a mixed solution containing the component (B) and the component (C) is supplied in the presence of the component (A). Is desirable. In the method of the present invention, the treatment temperature of the vinyl compound containing the components (A), (B) and (C) varies depending on the type of the vinyl compound. ~ 130 ° C. When the treatment temperature is in this range, the polymerization preventing effect and the corrosion preventing effect are sufficiently exhibited. Also, when distilling acrylic acid or methacrylic acid, it is usually processed under reduced pressure, and the pressure is
The range of 0.01 to 0.1 MPa is preferable.

[0014]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Comparative Example 1 A SUS316 test piece (40 ×
15 × 3 mm) and 200 ml of acrylic acid in which 3500 weight ppm of copper dibutyldithiocarbamate (based on acrylic acid, the same applies hereinafter) was dissolved as a polymerization inhibitor, and the temperature inside the flask was kept at 110 ° C. under reduced pressure. 1
Refluxed for days. As a result, the weight loss rate of the test piece due to corrosion (the ratio of the weight loss amount to the weight of the test piece before treatment) was 507 ppm by weight. Also,
At this time, no turbidity due to the polymer was observed in the liquid phase portion in the flask, but a large amount of polymer was generated in the upper lid of the flask which was the gas phase condensation portion. Table 1 shows the conditions and results.

Comparative Example 2 The procedure of Comparative Example 1 was repeated, except that phenothiazine was used instead of copper dibutyldithiocarbamate as a polymerization inhibitor. Table 1 shows the conditions and results.

Comparative Example 3 In Comparative Example 1, copper dibutyldithiocarbamate 35
The operation was carried out in the same manner as in Comparative Example 1 except that 200 ml of acrylic acid in which 8500 ppm by weight of phosphoric acid was dissolved together with 00 ppm by weight. Table 1 shows the conditions and results.

Comparative Example 4 In Comparative Example 1, copper dibutyldithiocarbamate 35
The procedure was performed in the same manner as in Comparative Example 1 except that 200 ml of acrylic acid in which 350 ppm by weight of N-nitrosophenylhydroxylamine ammonium salt had been dissolved after dissolving 00 ppm by weight was used. Table 1 shows the conditions and results.

Comparative Example 5 In Comparative Example 1, copper dibutyldithiocarbamate 35 was used.
The procedure was performed in the same manner as in Comparative Example 1 except that 200 ml of acrylic acid in which 2000 ppm by weight of water was dissolved together with 00 ppm by weight. Table 1 shows the conditions and results.

Comparative Example 6 In Comparative Example 1, copper dibutyldithiocarbamate 70
The operation was performed in the same manner as in Comparative Example 1, except that 200 ml of acrylic acid in which 00 ppm by weight was dissolved was used.
Table 1 shows the conditions and results.

Comparative Example 7 In Comparative Example 1, copper dibutyldithiocarbamate 50
The procedure was performed in the same manner as in Comparative Example 1 except that 200 ml of acrylic acid in which 0 ppm by weight was dissolved was used. Table 1 shows the conditions and results.

Comparative Example 8 In Comparative Example 1, copper dibutyldithiocarbamate 35
Methoquinone 3500 weight ppm along with 00 weight ppm
Was carried out in the same manner as in Comparative Example 1 except that 200 ml of acrylic acid in which was dissolved was used. Table 1 shows the conditions and results.

Comparative Example 9 In Comparative Example 1, copper dibutyldithiocarbamate 35 was used.
Phenothiazine 1000 weight p with 00 weight ppm
pm, 2,000 ppm by weight of hydroquinone, methoquinone 2
Except that 200 ml of acrylic acid in which 000 ppm by weight and 8500 ppm by weight of phosphoric acid were dissolved was used.
It carried out similarly to the comparative example 1. Table 1 shows the conditions and results.

Comparative Example 10 In Comparative Example 1, copper dibutyldithiocarbamate 35 was used.
Phenothiazine 1000 weight p with 00 weight ppm
pm, 2,000 ppm by weight of hydroquinone, methoquinone 2
The procedure was performed in the same manner as in Comparative Example 1 except that 200 ml of acrylic acid in which 000 ppm by weight and 350 ppm by weight of N-nitrosophenylhydroxylamine ammonium salt were dissolved was used. Table 1 shows the conditions and results.

Comparative Example 11 In Comparative Example 1, instead of copper dibutyldithiocarbamate, 1000% by weight of phenothiazine, 2000% by weight of hydroquinone and 2000% by weight of methquinone
acrylic acid 20 in which m and 350 ppm by weight of N-nitrosophenylhydroxylamine ammonium salt are dissolved
The procedure was performed in the same manner as in Comparative Example 1 except that 0 ml was used. Table 1 shows the conditions and results.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

[Table 3]

(Note) Criteria for judging the polymerization state of the liquid phase portion ○: No turbidity of the liquid phase portion caused by polymerization △: The liquid phase portion becomes slightly turbid by polymerization ×: The liquid phase portion becomes turbid by polymerization Gas phase condensation Criteria for judging the polymerization state of the part ○: No polymer was formed on the flask lid by polymerization △: Slightly polymer was generated on the flask lid by polymerization ×: Polymer was generated on the flask lid by polymerization

In Table 1, a comparison between Comparative Example 1 and Comparative Example 2 shows that copper dibutyldithiocarbamate has corrosiveness. Also, from Comparative Examples 1, 3, and 5,
It can be seen that copper dibutyldithiocarbamate has a good polymerization prevention effect in the liquid phase, but has a very low polymerization prevention effect in the gas phase condensation section. From Comparative Example 4, by using copper dibutyldithiocarbamate and N-nitrosophenylhydroxylamine ammonium salt in combination,
It can be seen that the effect of preventing polymerization in the gas phase condensation section is improved. Furthermore, Comparative Examples 1 and Comparative Examples 3 and 5 show that phosphoric acid and water are effective as corrosion inhibitors.

Example 1 After dissolving 8500 ppm by weight of phosphoric acid together with 3500 ppm by weight of copper dibutyldithiocarbamate, N-
Nitrosophenylhydroxylamine ammonium salt 3
The operation was performed in the same manner as in Comparative Example 1 except that 200 ml of acrylic acid in which 50 ppm by weight was dissolved was used.
Table 2 shows the conditions and results.

Example 2 The procedure of Example 1 was repeated, except that the amount of phosphoric acid was changed to 4000 ppm by weight. Table 2 shows the conditions and results.

Example 3 The procedure of Example 1 was repeated, except that the amount of phosphoric acid was changed to 400 ppm by weight. Table 2 shows the conditions and results.

Example 4 The procedure of Example 1 was repeated, except that the amount of copper dibutyldithiocarbamate was changed to 7000 ppm by weight. Table 2 shows the conditions and results.

Example 5 Example 5 was repeated except that the amount of copper dibutyldithiocarbamate was changed to 500 ppm by weight, the amount of N-nitrosophenylhydroxylamine ammonium salt was changed to 50 ppm by weight, and the amount of phosphoric acid was changed to 50 ppm by weight. Was carried out in the same manner as in Example 1. Table 2 shows the conditions and results.

Example 6 Example 6 was carried out in the same manner as in Example 5 except that the amount of N-nitrosophenylhydroxylamine ammonium salt was changed to 25 ppm by weight. Table 2 shows the conditions and results.

Example 7 In Example 1, 2,000 weight parts of water was used instead of phosphoric acid.
Except using pm, it carried out similarly to Example 1.
Table 2 shows the conditions and results.

Example 8 Example 8 was carried out in the same manner as in Example 1, except that 2000 ppm by weight of water was further added. Table 2 shows the conditions and results.

Example 9 In Example 1, zinc phosphate 170 was used instead of phosphoric acid.
It carried out like Example 1 except having used 0 weight ppm. Table 2 shows the conditions and results.

Example 10 In Example 5, zinc phosphate 170 was used instead of phosphoric acid.
It carried out similarly to Example 5 except having used 0 weight ppm. Table 2 shows the conditions and results.

Example 11 Example 11 was carried out in the same manner as in Example 1, except that 3300 ppm by weight of boric acid was used instead of phosphoric acid. Table 2 shows the conditions and results.

Example 12 In Example 11, zinc borate 90 was used instead of boric acid.
Except that 0 ppm by weight and 900 ppm by weight of water were used,
It carried out similarly to Example 11. Condition and result
See the table.

Example 13 In Example 1, copper dibutyldithiocarbamate 35 was used.
Phenothiazine 1000 weight p with 00 weight ppm
pm, 2,000 ppm by weight of hydroquinone, methoquinone 2
000 wt ppm, 350 wt ppm of N-nitrosophenylhydroxylamine ammonium salt and phosphoric acid 85
The procedure was performed in the same manner as in Example 1 except that 200 ml of acrylic acid in which 000 ppm by weight was dissolved was used. Table 2 shows the conditions and results.

[0044]

[Table 4]

[0045]

[Table 5]

[0046]

[Table 6]

(Note) Criteria for judging the polymerization state of the liquid phase part and the gas phase condensation part are the same as the footnotes in Table 1. Table 2 clearly shows that, according to the method of the present invention, in both the liquid phase portion and the gas phase condensation portion, a good polymerization preventing effect is exhibited, and the corrosion of the test piece is extremely small.

[0048]

According to the method of the present invention, a vinyl compound,
Particularly in a distillation system in a production process of acrylic acid or methacrylic acid, etc., the polymerization of the vinyl compound can be effectively suppressed in both the liquid phase part and the gas phase condensation part, and the corrosion of equipment is prevented. In addition, stable continuous operation for a long period of time becomes possible.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-211735 (JP, A) JP-A-7-252477 (JP, A) JP-A-5-51403 (JP, A) JP-A 64-64 42443 (JP, A) JP-A-5-194346 (JP, A) JP-A-3-503896 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07C 51/42 C07C 57 / 07

Claims (5)

(57) [Claims] 1. A method for preventing polymerization of a vinyl compound using a metal dialkyldithiocarbamate in a process for producing a vinyl compound, comprising: (B) N-nitrosophenylhydroxylamine and / or (B) a metal dialkyldithiocarbamate together with (A) a metal dialkyldithiocarbamate. A method for preventing polymerization of a vinyl compound, comprising using the salt and (C) at least one selected from an inorganic acid, an inorganic acid salt and water. 2. The method according to claim 1, wherein the metal dialkyldithiocarbamate is copper dibutyldithiocarbamate. 3. The method according to claim 1, wherein the salt of N-nitrosophenylhydroxylamine is an ammonium salt. 4. The method according to claim 1, wherein the inorganic acid is phosphoric acid or boric acid. 5. The method according to claim 1, wherein the vinyl compound is acrylic acid or methacrylic acid.