WO2001046112A1

WO2001046112A1 - Method for preventing polymerization of vinyl compound

Info

Publication number: WO2001046112A1
Application number: PCT/JP2000/008714
Authority: WO
Inventors: Kouji Tomita; Takashi Nakagawa
Original assignee: Idemitsu Petrochemical Co., Ltd.
Priority date: 1999-12-21
Filing date: 2000-12-08
Publication date: 2001-06-28
Also published as: CN1249012C; CN1362943A; TWI275584B; JP2001172224A

Abstract

A method for preventing the polymerization of a vinyl compound by means of an inexpensive polymerization inhibitor which is effective even in the absence of oxygen or in the presence of water even when used in a small amount. The method comprises using as the polymerization inhibitor a combination of phenothiazine with a strong acid.

Description

Description Method for preventing polymerization of vinyl compounds

The present invention relates to a method for preventing polymerization of a vinyl compound, and more particularly, to a method for distilling a vinyl compound, particularly acrylic acid and / or methacrylic acid (both are collectively referred to as (meth) acrylic acid) and esters thereof. The present invention relates to a method for effectively preventing polymerization in a production process. Landscape technology

Among the butyl compounds, (meth) acrylic acid and its esters are useful monomers as raw materials for various organic materials such as paints, adhesives, and water-absorbing resins, and are widely used. As a result, products with higher purity have been required. By the way, since these monomers are extremely easily polymerized by heat, light, peroxides, etc., in the production process, troubles in the distillation system often occur due to the produced polymer. Specifically, it is known that the performance of the distillation column is reduced, the heat transfer performance of the distillation column reboiler is reduced, and furthermore, the distillation column is clogged, which is a great obstacle to the production process. Therefore, development of a method for preventing polymerization of these monomers is an important industrial issue.

Conventionally, various methods for preventing polymerization have been proposed to solve the above-mentioned problems, but among them, it is common to add a polymerization inhibitor. Typical polymerization inhibitors include phenols such as hydroquinone and hydroquinone monomethyl ether; amines such as phenothiazine and diphenylamine; heavy metal salts such as copper dibutyldithiocarbamate and manganese acetate; nitroso compounds; Aminoxyls such as nitro compounds and tetramethylbiperidinoxyl (TEMPO) derivatives are known. The use of these polymerization inhibitors alone or in various combinations including oxygen has been proposed. Although effective, each of them has problems and there is still room for improvement. For example, phenols, phenothiazines, essentially require oxygen to produce their effects, and are not sufficiently effective in a reduced pressure system. Although copper dibutyldithiocarbamate works effectively even in the absence of oxygen, it hardly dissolves in water and is not suitable for preventing polymerization in the presence of water. Also, TEMPOs are water-soluble and effective, but expensive. Therefore, there is a demand for the development of a low-cost and effective polymerization inhibitor even in the absence of oxygen or in the presence of water. Disclosure of the invention

The present invention has been made in view of the above, and an object of the present invention is to provide a method for preventing polymerization of a vinyl compound using an inexpensive polymerization inhibitor effective in a small amount even in the absence of oxygen or in the presence of water. Things.

The present inventors have conducted intensive studies and have found that the above object of the present invention can be effectively achieved by using funothiazine and a strong acid as polymerization inhibitors, and have completed the present invention.

That is, the present invention provides a method for preventing polymerization of a vinyl compound, which comprises using phenothiazine and a strong acid as polymerization inhibitors. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail.

Examples of the vinyl compound to which the method of the present invention can be applied include (meth) acrylic acid, (meth) acrylic acid ester, styrene, acrylonitrile, and the like. Among them, (meth) acrylic acid is particularly preferable. is there.

In the present invention, phenothiazine is used as one component of the polymerization inhibitor for the bullet compound. As phenothiazine, commercially available phenothiazine can be used, High purity is desirable from the viewpoint of the effect. The amount of phenothiazine used is not particularly limited, but is usually 1 to 300 ppm by weight, preferably 10 to 500 ppm by weight, based on the butyl compound. If the amount is too small, the effect of preventing polymerization may not be sufficiently exhibited, and if the amount is too large, the effect may not be improved for the amount.

A strong acid is used as another component of the polymerization inhibitor of the present invention. Examples of strong acids include mineral acids such as sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, and chloric acids, and organic acids such as p-toluenesulfonic acid and trifluoroacetic acid. Ensulphonic acid is preferred. The amount of the strong acid is not particularly limited, but is usually 1 to 50 times, preferably 2 to 20 times the molar amount of phenothiazine. If the amount is too small, the effect of preventing polymerization may not be sufficiently exerted. If the amount is too large, the effect may not be improved for the amount thereof, and a problem of corrosion may occur.

The method of adding the polymerization inhibitor is not particularly limited, but may be added after previously mixing phenothiazine and a strong acid, or may be added separately.

Since oxygen is not required in the method of the present invention, for example, the oxygen concentration in the distillation column is not limited.

In the method of the present invention, other known polymerization inhibitors can be added, if desired, as long as the object of the present invention is not impaired. Next, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples.

(Example 1)

After removing the polymerization inhibitor contained by purification, add 500 ppm by weight of phenothiazine (abbreviated as PTZ) and 2000 ppm by weight of sulfuric acid to acrylic acid, and seal in a 5 ml ampoule tube purged with nitrogen. Tube and heated at 90 ° C, 1 2 After 0 hour, no cloudiness due to the polymer was observed.

(Comparative Example 1)

When the same procedure was performed as in Example 1 except that sulfuric acid was not added, white turbidity was observed at 140 minutes.

(Comparative Example 2)

When the same procedure was performed as in Example 1 except that PTZ was not added, cloudiness was observed in 2 minutes.

(Reference Example 1)

In Example 1, the same procedure was performed except that the polymerization inhibitor was not added, and clouding was observed in 5 minutes.

(Examples 2 to 5, Comparative Examples 3 to 8, Reference Example 2)

Add the amount of PTZ and strong acid shown in Table 1 to commercially available acrylic acid from which the polymerization inhibitor contained was removed by purification, seal in a 5-milliliter ampoule tube purged with nitrogen, heat at 120 ° C, and turn cloudy. Observed the time until. The results are shown in Table 1. Table 1

Fiber

PTZ amount Cloudy time

(fi * PPDl) amount (weight ppm)

Kinen 2 1 00 2,000> 360 minutes

HS example 3 100 fibers 2,000> 360 min

Example 4 100 phosphoric acid 2,000 ＞ 360 minutes

¾SS example 5 100 p-torr 1 sulho: 2,000〉 360 min

瞧 3 100 40 minutes

赚 Example 4 100 water 2.000 2 minutes

For example 5 2,000 1 minute

赚 Example 6 2,000 1 minute

赚 Example 7 phosphoric acid 2,000 2 minutes

i 瞧 8 ρ-port 1 is sulfonic acid 2,000 2 minutes

m 2 1 minute (Example 6, Comparative Examples 9 to 14, Reference Example 3)

Using a 50% by weight aqueous solution of acrylic acid, the polymerization inhibitory effects of the polymerization inhibitors shown in Table 2 were examined in the presence of water. The experiment was performed in the same manner as in Example 1. The results are shown in Table 2.

Table 2

(Note) HQ: Hydroquinone

CBW: Dibutyldithiocarbamine steel

[Example 7, Comparative Examples 15 and 16, Reference Example 4]

In the same manner as in Example I, except that the monomer was changed to methacrylic acid. Table 3 shows the results. Table 3

PTZ amount 量 amount Cloudy time

(fiappm)

Zenin 7 500 2,000> 360 minutes

Female 15 500 21 0 min

赚 Example 16 2,000 3 minutes (Comparative Examples 17 to 20)

Example 2 was repeated except that PZT was replaced with hydroquinone (HQ). The results are shown in Table 4.

Table 4

The above Examples and Comparative Examples show that the combined use of funinothiazine and a strong acid as polymerization inhibitors has a surprising synergistic effect. Industrial applicability

According to the method of the present invention, the combined use of funinothiazine and a strong acid as polymerization inhibitors effectively prevents polymerization in the vinyl compound production process even in the absence of oxygen and in the presence of water. It can be effectively applied to the vacuum distillation purification process.

Claims

The scope of the claims

1. A method for preventing polymerization of vinyl compounds, which comprises using phenothiazine and a strong acid together as a polymerization inhibitor.

2. The method for preventing polymerization of a vinyl compound according to claim 1, wherein the strong acid is at least one selected from sulfuric acid, hydrochloric acid, phosphoric acid and p-toluenesulfonic acid.

3. The method for preventing polymerization of a vinyl compound according to claim 1, wherein the butyl compound is at least one selected from atalylic acid, methacrylic acid, acrylate and methacrylate.

4. The method for preventing polymerization of a vinyl compound according to claim 1, wherein the amount of the phenothiazine used is 1 to 3,00 OSM ppm with respect to the vinyl compound.

5. The method for preventing polymerization of a vinyl compound according to claim 1, wherein the amount of the strong acid used is 1 to 50 times the molar amount of the phenothiazine.

6. The method for preventing polymerization of a vinyl compound according to claim 3, wherein the vinyl compound is atrial acid and / or methacrylic acid.