JPH0718004A - Scale inhibitor for vinyl polymer and method for inhibiting scale buildup - Google Patents

Abstract

PURPOSE:To inhibit polymer scale buildup by applying a condensate obtd. by condensing pyrogallol and/or phloroglucin with formaldehyde in the presence of an alkali catalyst to the inner wall of a polymerizer before a vinyl monomer is polymerized. CONSTITUTION:A condensate obtd. by condensing pyrogallol and/or phloroglucin with formaldehyde in the presence of an alkali catalyst is used as a scale inhibitor. The condensate can be used jointly with an acidic compd. and/or fine metal oxide particles; when jointly used, the condensate cross-links, becoming insol. in the reaction solvent and hence remarkably inhibiting polymer scale buildup. Examples of the acidic compd. are an org. sulfonic acid such as p-toluenesulfonic acid and an org. carboxylic acid such as acetic acid. Examples of the metal oxide are aluminum oxide, iron oxide, and silicon oxide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vinyl polymer scale inhibitor and a method for preventing adhesion of the polymer scale using the scale inhibitor.

[0002]

2. Description of the Related Art When polymerizing a vinyl-based monomer, the polymer is used as a scale on the inner wall of a polymerization vessel, baffles, stirring blades, and in a reflux condenser equipped on the polymerization vessel (hereinafter, simply referred to as inner wall surface of polymerization vessel, etc.). Also referred to as). This polymer scale (hereinafter, simply referred to as scale) reduces the effect of removing heat generated during the polymerization and also mixes in the product to deteriorate the product quality. Therefore, it is necessary to remove the scale, but the removal of the scale requires a lot of labor and cost, and there are many problems such as impeding the continuous execution of the polymerization and lowering the production efficiency. Recently, there is a tendency for the size of the polymerization vessel to become larger. However, as the size of the polymerization vessel becomes larger, it becomes more difficult to remove the heat of reaction due to the scale, and the labor and cost required for removing the scale also increase. Heretofore, scale inhibitors particularly in the suspension polymerization method of vinyl chloride monomer have been intensively studied, and some results have been obtained. For example, a method is known in which a condensate of a phenolic compound (pyrogallol) and an aldehyde, a condensate of an aromatic amine, or the like is applied to the inner wall surface of the polymerization vessel or the like to prevent scale.

[0003]

However, it cannot be said that the sufficient scale preventing effect is obtained even by these methods. In addition, in these methods, a vinyl monomer having high water solubility in vinyl chloride, for example, a suspension polymerization method of copolymerizing vinyl acetate, acrylonitrile or the like, or a micro suspension polymerization method of vinyl chloride using an emulsifier, In the emulsion polymerization method, a sufficient scale preventing effect cannot be obtained. In addition to the vinyl chloride resin, the above method can hardly obtain the scale prevention effect even in the polymerization of MBS resin, ABS resin, polymethacrylate processability improving resin and the like, which are generally adopted in the emulsion polymerization method. .

[0004]

Means for Solving the Problems As a result of the present inventors, as a result of earnest research to develop a technique for substantially preventing scale during the production of a vinyl polymer in which scale prevention is difficult as described above. The present invention has been completed. That is, the first aspect of the present invention is a scale inhibitor for vinyl polymer comprising a condensate obtained by subjecting pyrogallol and / or phloroglucin and formaldehyde to a condensation reaction under an alkali catalyst, and the second aspect of the present invention is to use an alkali catalyst. A condensate obtained by subjecting pyrogallol and / or phloroglucin and formaldehyde to a condensation reaction below, and a scale inhibitor for a vinyl polymer comprising at least one selected from the group consisting of an acidic compound and a fine particle metal oxide,
The third aspect of the present invention is to provide pyrogallol and / or
Alternatively, after applying a condensate obtained by subjecting phloroglucin and formaldehyde to a condensation reaction, a method for preventing adhesion of a vinyl-based polymer scale, which comprises polymerizing a vinyl-based monomer, the fourth of the present invention is: Inner wall of the polymerization vessel, coating the condensate obtained by condensation reaction of pyrogallol and / or phloroglucin and formaldehyde under the alkali catalyst on the surface of the portion where the monomer contacts such as a stirring blade, and then after crosslinking treatment with alkali, The present invention is directed to a method for preventing adhesion of a vinyl polymer scale, which is characterized in that a vinyl monomer is polymerized.

The scale inhibitor of the present invention is a condensate obtained by subjecting pyrogallol and / or phloroglucin (hereinafter sometimes referred to as pyrogallol etc.) and formaldehyde to a condensation reaction under an alkali catalyst, or a condensate thereof. , At least one selected from the group consisting of acidic compounds and particulate metal oxides.

The condensate in the present invention is obtained by condensing the above compound under an alkali catalyst. By using an alkali catalyst, the condensate is firmly adhered to the inner wall surface of the polymerization vessel and the like, and the condensate is crosslinked by the combined use of the acidic compound and / or the particulate metal oxide, and these are eluted in the polymerization reaction medium. As a result, no significant scale prevention effect is obtained. The condensate obtained by condensing under an acidic catalyst has weak adhesion to the inner wall surface of the polymerization vessel and the like, and does not crosslink even when used in combination with an acidic compound or fine particle metal oxide, and therefore has a small scale preventing effect. Further, the condensate obtained when an aldehyde other than formaldehyde is used has weak adhesion to the inner wall surface of the polymerization vessel and does not crosslink, and therefore has almost no scale preventing effect. In addition, compounds other than pyrogallol and phloroglucin, such as condensates obtained when phenol is used, also crosslink, but no scale-preventing effect can be expected. This is because the condensate repels water,
It is considered that the condensate of the present invention is hydrophilic. still,
In the present invention, pyrogallol and phloroglucin may be used alone or in combination.

The reaction conditions for obtaining the condensate of the present invention are:
In the condensation reaction medium under an alkaline catalyst, 1-5 mol, preferably 1.5-3 mol of formaldehyde is reacted with 1 mol of pyrogallol or the like. If the amount of formaldehyde is less than 1 mol, the condensation reaction rate will be slow, and if it exceeds 5 mol, the condensation reaction rate will be so high that the condensate may be crosslinked during the condensation reaction and the desired condensate may not be obtained. still,
In the present invention, formaldehyde includes, in addition to formaldehyde, formalin and paraformaldehyde in which formaldehyde is dissolved in water, but formalin is preferable from the viewpoint of handleability.

Examples of the alkali catalyst include inorganic compounds such as sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate and potassium carbonate, and organic amine compounds such as ammonia, methylamine, ethylamine, dimethylamine, diethylamine and triethylamine. These can be used alone or in combination of two or more. The amount used is 0.0 per 1 mol of pyrogallol, etc.
It is from 01 to 0.1 mol, preferably from 0.005 to 0.01 mol. If it is less than 0.001 mol, the condensation reaction rate will be slow, and if it exceeds 0.1 mol, the condensation reaction rate will be very fast and the condensate will be crosslinked during the condensation reaction, whereby the desired condensate may not be obtained.

The condensation reaction medium may be any one capable of dissolving pyrogallol, phloroglucin and formaldehyde together, and examples thereof include water, methanol, ethanol, propanol, acetone, methyl ethyl ketone, tetrahydrofuran and acetonitrile, which may be used alone or in combination with 2
It can be used in combination of two or more species. Of these, water is particularly preferable in terms of cost. The amount of the condensation reaction medium used is preferably 1000 to 5000 cc with respect to 1 mol of pyrogallol or the like. If it is less than 1000 cc, the condensate may be crosslinked during the condensation reaction and the desired condensate may not be obtained. 5000
If it exceeds cc, the condensation reaction rate becomes slow, which is not preferable.

The condensation reaction temperature is 40 to 90 ° C, preferably 50 to 80 ° C. If it is lower than 40 ° C., the condensation reaction rate is slow, and if it exceeds 90 ° C., the condensation reaction rate becomes very fast and the condensate is cross-linked during the condensation reaction, so that the desired condensate may not be obtained. The condensation reaction time is 30 minutes to 7 minutes.
Time is good. A condensation reaction product solution containing the condensation product obtained under the above conditions, an unreacted raw material, and a condensation reaction medium is neutralized with an inorganic acid such as hydrochloric acid, sulfuric acid, or nitric acid if necessary, and gradually stirred into a large amount of water. It is possible to precipitate the condensate by throwing it in and to separate the precipitate by filtration to obtain the desired condensate.

In the present invention, the acidic compound and the particulate metal oxide are for promoting the crosslinking of the condensate. Examples of the acidic compound include organic sulfonic acids such as para-toluenesulfonic acid, para-chlorobenzenesulfonic acid and para-hydroxybenzenesulfonic acid, and organic carboxylic acids such as oxalic acid, acetic acid, chloroacetic acid and malic acid, which are used alone or It can be used in combination of two or more species. The amount used is preferably 100 parts by weight or less, and more preferably 5 to 30 parts by weight, based on 100 parts by weight of the condensate. If it is used in excess of 100 parts by weight, the scale prevention effect will be reduced. Examples of the fine particle metal oxides include metal oxides having an average particle diameter of 3 to 150 mμ, such as aluminum oxide, iron oxide, silicon oxide, antimony oxide, tin oxide, and titanium oxide, which are used alone or in combination of two or more kinds. it can. If the average particle size exceeds 150 mμ, the scale preventing effect decreases, and if the average particle size is less than 3 mμ, it is difficult to obtain. Preferably, a metal oxide having an average particle size of 5 to 100 mμ is used. The amount used is preferably 30 to 300 parts by weight, more preferably 50 to 200 parts by weight, based on 100 parts by weight of the condensate. If the amount is less than 30 parts by weight, the cross-linking of the coating film will be incomplete, and if it exceeds 300 parts by weight, the scale preventing effect will be deteriorated. The acidic compound and the particulate metal oxide can be used in combination.

In order to prevent the scale from adhering to the inner wall surface of the polymerization vessel during the vinyl-type monomer polymerization by using the above scale inhibitor, a condensate or the condensate and an acidic compound and / or a particulate metal oxide is used. A coating solution is prepared by dissolving or dispersing in an organic solvent, and the coating solution is applied to the inner wall surface of the polymerization vessel and dried.

Examples of the organic solvent include alcohols such as methanol, ethanol, acetone, tetrahydrofuran, dimethylformamide, etc., ketones, ethers, amides, etc. These can be used alone or in combination of two or more. From the viewpoint of shortening the drying time of the membrane, it is preferable to use a solvent having a low boiling point. The concentration of the coating liquid is preferably 0.05 to 2% by weight. The amount of the coating solution used is not particularly limited, and may be applied uniformly on the inner wall surface of the polymerization vessel, etc., but the solid content of the coating solution is about 0.1 to 50 g per 1 m ^{2 of} the inner wall surface. Is good. The coating method is not particularly limited, and examples thereof include a brush coating method, a method of spraying a coating solution from a nozzle to apply, and a method of filling the polymerization vessel with the coating solution and coating, but a method of spraying from a nozzle. Is simple and preferred. Drying of the applied coating solution is preferably 40 to 130 ° C., more preferably 50 to 90 ° C.
Perform at 5 ° C for 5-60 minutes.

By applying the scale inhibitor and polymerizing the vinyl-based monomer as described above, it is possible to prevent the scale from adhering to the inner wall surface of the polymerization vessel. When a condensate is further used, the inner wall surface of the polymerization vessel, etc. It is also possible to crosslink the coating film formed by processing the coating film with an alkali. The alkali treatment is preferably carried out at a temperature of 10 to 5 at a normal coating film of 10 ^-2 to 10 ^-4.
It is carried out by contacting with an alkaline aqueous solution at 0 ° C. for 20 to 200 minutes. When the alkali concentration exceeds 10 ^{-2 N} , the coating film is dissolved during the alkali treatment, and when it is less than 10 ^-4 N, the time required for the cross-linking of the coating film becomes long, which is not preferable. More preferably, a 5 × 10 ^{−3 to} 5 × 10 ⁻⁴ normal alkaline aqueous solution is used. If the alkali treatment temperature is lower than 10 ° C, the time required for crosslinking the coating film becomes long, and if it exceeds 50 ° C, the coating film is dissolved, which is not preferable. More preferably, it is 20-40 degreeC. Further, if the alkali treatment time is less than 20 minutes, the cross-linking of the coating film is incomplete,
Even if it exceeds 200 minutes, the crosslinking effect does not change. More preferably, it is 30 to 100 minutes.

As the alkaline reagent used for the alkaline treatment, inorganic compounds such as sodium hydroxide, potassium hydroxide, cesium hydroxide, sodium carbonate and potassium carbonate,
Examples thereof include organic amine compounds such as ammonia, methylamine, ethylamine, dimethylamine, diethylamine and triethylamine, and these can be used alone or in combination of two or more. Examples of the alkali treatment method include, but are not particularly limited to, a method of filling the inside of the polymerization vessel in which the coating film is formed with an aqueous alkali solution for treatment, or a method of bringing the aqueous alkali solution into contact with the surface of the coating film by spraying or the like.

As described above, when the vinyl polymer is produced by the suspension polymerization method, the micro suspension polymerization method, the emulsion polymerization method or the like by applying the inner wall surface of the polymerization vessel or the like with the scale inhibitor of the present invention. It is possible to prevent the adhesion of scale of the vinyl polymer. The vinyl polymer of the present invention refers to a polymer of a vinyl monomer and a diene monomer. Specifically, it can be obtained by vinyl type monomer alone, vinyl type monomer combination, diene type monomer alone, diene type monomer combination, or vinyl type monomer and diene type monomer combination. Polymer referred to. Vinyl-based monomers include vinyl chloride, vinyl acetate, acrylonitrile, ethylene,
Propylene, styrene, acrylamide, acrylic acid,
Examples thereof include acrylic acid ester, and examples of the diene-based monomer include butadiene and isoprene. The polymerization reactor means a polymerization reactor made of stainless steel, clad steel, nickel alloy, or glass lining.

The suspension polymerization method, the micro suspension polymerization method and the emulsion polymerization method in the present invention are carried out by polymerization in an aqueous medium using a polymerization initiator, a suspension stabilizer (dispersant), an emulsifier and other additives. It is a known polymerization method. The present invention can be applied to various polymerization methods for vinyl polymers as described above, but when it is applied to a suspension polymerization method for vinyl chloride monomers, the effect is particularly remarkable.

[0018]

The present invention will be described in more detail based on the following examples, but they are not intended to limit the present invention.

(A) Manufacture of Condensate Manufacture Example 1 (Manufacture of Condensate A) 2 L of water and 1 pyrogallol were placed in a glass reactor having an internal volume of 4 L.
26 g (1 mol), 243 g of formalin (37% aqueous solution: 3 mol as formaldecht) and 0.28 g (0.005 mol) of potassium hydroxide were charged, a condensation reaction was carried out at 80 ° C. for 2 hours and 30 minutes, and then hydrochloric acid of 0. After adding 005 mol to neutralize, the condensation reaction liquid was poured into 5 L of water with stirring. The precipitate was filtered to obtain 40 g of the desired condensate.

Production Example 2 (Production of Condensate B) 2 L of water and 1 pyrogallol were placed in a glass reactor having an internal volume of 4 L.
26 g (1 mol), 162 g of formalin (37% aqueous solution: 2 mol as formaldehyde) and 0.56 g (0.01 mol) of potassium hydroxide were charged, a condensation reaction was carried out at 70 ° C. for 3 hours, and then 0.01 mol of hydrochloric acid. Was added to neutralize, and the condensation reaction solution was poured into 5 L of water with stirring. The precipitate was filtered to obtain 35 g of the desired condensate.

Production Example 3 (Production of Condensate C) 2 L of water and 1 pyrogallol were placed in a glass reactor having an internal volume of 4 L.
26 g (1 mol), formalin 65 g (37% aqueous solution:
Formaldehyde (0.8 mol), phosphoric acid 9.8 g
(0.1 mol) was charged, a condensation reaction was carried out at 90 ° C. for 7 hours, and after cooling to room temperature, the precipitate was filtered to obtain 10 g of a condensate.

Production Example 4 (Production of Condensate D) 2 L of water and 1 pyrogallol were placed in a glass reactor having an internal volume of 4 L.
26 g (1 mol), acetaldehyde 132 g (3 mol) and potassium hydroxide 5.6 g (0.1 mol) were charged, a condensation reaction was carried out at 70 ° C. for 3 hours, and then hydrochloric acid 0.0
After 1 mol was added for neutralization, the condensation reaction solution was poured into 5 L of water with stirring. The precipitate was filtered to obtain 10 g of the desired condensate.

Production Example 5 (Production of Condensate E) 2 L of water and 1 pyrogallol were placed in a glass reactor having an internal volume of 4 L.
26 g (1 mol), benzaldehyde 212 g (2 mol) and phosphoric acid 196 g (2 mol) were charged, the condensation reaction was performed at 100 ° C. for 6 hours, and after cooling to room temperature, the precipitated precipitate was washed with ether to obtain a condensate. 100 g was obtained.

(B) Preparation of coating liquid A coating liquid was prepared by dissolving the condensates A to E obtained in (a) above in methanol so that the condensate concentration was 1% by weight. At this time, 10 parts by weight and 20 parts by weight of p-toluenesulfonic acid were added to 100 parts by weight of the condensate, and 100 parts by weight of various fine particle metal oxides were added to 100 parts by weight of the condensate. A coating solution added by weight was also prepared.

(C) Application of coating liquid The coating liquid was applied by spraying to the inner wall surface of the polymerization vessel which had been washed beforehand, and dried at 70 ° C for 30 minutes. The coating amount of the solid matter per coated area was 0.5 g / m ² .

(D) Production of vinyl polymer Polymerization prescription-1: Suspension polymerization method of vinyl chloride In a stainless steel polymerization vessel having an inner volume of 1500 L equipped with a stirrer, water 70 in which 250 g of partially saponified polyvinyl acetate was dissolved was used.
Charge 0 kg, vinyl chloride 550 kg, and di-2-ethylhexyl peroxydicarbonate 300 g,
Polymerization was carried out for a time. Polymerization Formula-2: Micro Suspension Polymerization Method of Vinyl Chloride In a stainless steel polymerization vessel having an inner volume of 300 L equipped with a stirrer, 150 g of water in which 800 g of sodium dodecylbenzenesulfonate is dissolved, 100 kg of vinyl chloride, di-2-ethylhexyl peroxydiene Charge 60g of carbonate, 5
Polymerization was carried out at 0 ° C for 7 hours.

Examples 1 to 14 and Comparative Examples 1 to 8 Using the polymerization vessel coated with the scale inhibitor according to the above (a) to (c), the polymerization reaction by the two kinds of polymerization methods shown in (d) above was conducted. Repeatedly carried out, the state of adhesion of scale to the inner wall surface of the polymerization vessel was visually observed, and judged according to the following criteria in three stages. The results are shown in Tables 1 and 2. ◯: No scale adhered to the entire wall surface. Δ: Adhesion of scale is recognized on part of the wall surface. X: Adhesion of scale is recognized on the entire wall surface.

Further, the presence or absence of crosslinking of the coating film was determined by the following method. 2 cm x 1 for the coating solution prepared in (b) above
It was applied to a 0 cm stainless steel test piece, dried at 70 ° C. for 30 minutes, and then immersed in methanol at room temperature for 30 minutes to determine the presence or absence of cross-linking from the solubility of the coating film (soluble:
No cross-linking, insoluble: cross-linking).

[0029]

[Table 1]

[0030]

[Table 2] * 1 a: Aluminum oxide (average particle size 20 mμ) b: Silicon oxide (average particle size 10 mμ) c: Antimony oxide (average particle size 40 mμ) Weight ratio (condensate / particulate metal oxide weight ratio)

Examples 15 to 16 and Comparative Example 9 Using the condensates A, B and C obtained in (a) above, after applying a scale inhibitor according to (b) and (c) above, 3
Example 1 except that the polymerization vessel was filled with an aqueous potassium hydroxide solution of 10 ^{−3 N at} 0 ° C. and left standing for 60 minutes for alkali treatment.
Polymerization was carried out in the same manner as in No. 14 to observe and evaluate the scale adhesion state. The results are shown in Table 3.

[0032]

[Table 3]

As is clear from Tables 1 and 2, the condensate of the present invention obtained by the condensation reaction in the presence of an alkali catalyst has a very good scale-preventing effect even in the suspension polymerization method and the micro suspension polymerization method. . Further, the combined use of the acidic compound and the fine particle metal oxide has a large effect, particularly in the suspension polymerization method. Further, as is clear from Table 3, by applying a condensate and then subjecting it to an alkali treatment, an excellent scale-preventing effect can be obtained as in the case of using an acidic compound or a particulate metal oxide together.

[0034]

As described above, the scale preventive agent and the scale preventive method for a vinyl-based polymer of the present invention have an excellent scale preventive effect even if they are continuously polymerized repeatedly by one coating. The industrial value is extremely high.

Claims (5)

[Claims] 1. A scale inhibitor for a vinyl polymer, comprising a condensate obtained by subjecting pyrogallol and / or phloroglucin and formaldehyde to a condensation reaction under an alkali catalyst. 2. A vinyl-based polymer comprising a condensate obtained by subjecting pyrogallol and / or phloroglucin and formaldehyde to a condensation reaction under an alkali catalyst, and at least one selected from the group consisting of an acidic compound and a particulate metal oxide. Scale inhibitor for coalescence. 3. An inner wall of a polymerization vessel, a stirring blade, and the like, on the surface of a portion in contact with a monomer, are pyrogallol and / or under an alkaline catalyst.
Alternatively, a method for preventing adhesion of a vinyl polymer scale, which comprises coating a condensate obtained by subjecting phloroglucin and formaldehyde to a condensation reaction and then polymerizing a vinyl monomer. 4. The method according to claim 3, wherein at least one selected from the group consisting of an acidic compound and a particulate metal oxide is applied together with the condensate. 5. A condensate obtained by subjecting pyrogallol and / or phloroglucin and formaldehyde to a condensation reaction under an alkali catalyst is applied to the surface of a portion of the polymerization vessel such as an inner wall of a polymerization vessel, which is in contact with a monomer, which is then contacted with an alkali. A method for preventing adhesion of a vinyl-based polymer scale, which comprises polymerizing a vinyl-based monomer after crosslinking treatment.