JPH1160613A - Scale inhibitor for vinyl polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the effect of preventing scale during the polymerization of a vinyl monomer and the persistence of the effect by using a pyrogallol/ formaldehyde condensate, a phenol/formaldehyde condensate and an acidic compound as the constituents. SOLUTION: Pyrogallol and formaldehyde at a molar ratio of (1:1) to (1:4) are subjected to condensation in the presence of an alkaline catalyst in a solvent at 50-90 deg.C for 1 to 5 hr to give a condensate (A). Phenol and formaldehyde at a molar ratio of (1:1) to (1:4) are subjected to condensation in the presence of an alkaline catalyst in a solvent at 60-95 deg.C for 1 to 10 hr to give a condensate (B). 5-20 wt.% acidic compound (C) is added to a mixture of component A and component B at a weight ratio of (25:1) to (3:1), preferably (20:1) to (5:1), more preferably (10:1) to (15:1), to give the scale inhibitor. This scale inhibitor is applied to, e.g. an inner wall of a polymerization reactor to provide a coating weight of 0.1-50 g/m<2> thereon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scale inhibitor for a vinyl polymer, and more particularly, it is applicable to suspension polymerization, microsuspension polymerization and emulsion polymerization of a vinyl monomer, and has an effect of preventing scale. And a scale inhibitor for vinyl polymers having excellent durability.

[0002]

2. Description of the Related Art At the time of polymerization of a vinyl monomer, a polymer is formed on an inner wall surface of a polymerization reactor, baffles, stirring blades, and a reflux condenser provided in the polymerization device (hereinafter, simply referred to as an inner wall surface). So-called scale).
The scale not only reduces the effect of removing the heat generated during the polymerization, deteriorates the product quality by being mixed into the product, but also requires a great deal of labor and cost to remove the scale. It is well known that many industrial disadvantages, such as being unable to be implemented continuously. Recently, polymerization reactors tend to be large in size, but the larger the size, the more difficult it is to remove heat of reaction by the scale, and the greater the labor and cost required to remove the scale.

Hitherto, a scale inhibitor has been energetically studied, particularly in a suspension polymerization method of a vinyl chloride monomer, and some results have been obtained. For example, a condensate of a phenolic compound (pyrogallol) and an aldehyde,
A method of applying a condensate of an aromatic amine or the like to the inner wall surface of a polymerization reactor or the like to prevent scale is known.

[0004]

However, it is still difficult to say that these methods still provide a sufficient scale prevention effect. Further, in these methods, a vinyl monomer having high water solubility in vinyl chloride, for example, vinyl acetate, acrylonitrile, etc., a suspension polymerization method of copolymerizing, a micro-suspension polymerization method of vinyl chloride using an emulsifier, In the emulsion polymerization method, almost no scale prevention effect is recognized. Further, in addition to the vinyl chloride resin, the above-described method does not provide a scale prevention effect for polymerization systems such as MBS resins, ABS resins, and polymethacrylate workability improving resins, which are generally employed in the emulsion polymerization method. Almost no.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been found as a result of intensive studies to develop a technique for substantially preventing the generation of a vinyl polymer scale, which is difficult to prevent scale as described above. An object of the present invention is to provide a vinyl polymer scale inhibitor comprising a condensate of pyrogallol and formaldehyde, a condensate of phenol and formaldehyde, and an acidic compound, and having excellent durability of scale prevention effect.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS That is, the present invention relates to a condensate of pyrogallol and formaldehyde (hereinafter referred to as pyrogallol condensate) (A) and a condensate of phenol and formaldehyde (hereinafter referred to as phenol condensate) (B) ) And an acidic compound (C).

The pyrogallol condensate (A) used in the present invention can be obtained by subjecting pyrogallol and formaldehyde to condensation reaction in a solvent at 50 to 90 ° C. for 1 to 5 hours under an alkaline catalyst. Pyrogallol and formaldehyde are preferably in a molar ratio in the range of 1/1 to 1/4. Outside the above range, the durability of the scale preventing effect is undesirably reduced. The pyrogallol referred to in the present invention may be pyrogallol, phloroglucin, or a mixture thereof, or a mixture of 90% by weight and 10% by weight or less of resorcinol of these compounds. The phenol condensate (B) used in the present invention is obtained by subjecting phenol and formaldehyde to condensation reaction in a solvent at 60 to 95 ° C. for 1 to 10 hours under an alkaline catalyst. The molar ratio of phenol to formaldehyde is preferably in the range of 1/1 to 1/4. Outside the above range, the durability of the scale preventing effect is undesirably reduced.

Examples of the alkaline catalyst include known alkaline substances such as sodium hydroxide, potassium hydroxide, lithium hydroxide, and magnesium hydroxide.
Used in combination of more than one species. The solvent may be any substance that dissolves the raw materials, and includes known solvents such as water, alcohol, acetone, and tetrahydrofuran, and these may be used alone or in combination of two or more.

The acidic compound (C) used in the present invention is
P-toluenesulfonic acid, benzenesulfonic acid, hydrochloric acid,
Known acidic compounds such as sulfuric acid may be mentioned, but P-toluenesulfonic acid, benzenesulfonic acid or a mixture thereof is preferred in view of the durability of the scale preventing effect.

In the present invention, the ratio of the pyrogallol condensate (A) to the phenol condensate (B) is preferably 25/1 to 3/1 by weight, more preferably 20/1 to 5/1.
More preferably, it is 10/1 to 15/1. This is because, when the ratio of pyrogallol condensate (A) is larger than the above range (the ratio of phenol condensate (B) is small), the degree of crosslinking decreases, the durability of the scale prevention effect decreases, and the phenol condensate (B) Is larger than the above range [the ratio of the pyrogallol condensate (A) is small], the scale prevention effect is reduced.

Next, the amount of the acidic compound (C) is preferably about 5 to 20% by weight based on the total amount of the pyrogallol condensate (A) and the phenol condensate (B). Acidic compound (C)
If the content is less than 5% by weight, the degree of crosslinking of the coating liquid coating film becomes small and the sustainability of the scale prevention effect is reduced. If the content is more than 20% by weight, no further improvement in the scale prevention effect and its sustainability is observed. This is because it is practically meaningless.

A scale inhibitor comprising a pyrogallol condensate (A), a phenol condensate (B) and an acidic compound (C) is dissolved in a solvent such as alcohol, acetone or tetrahydrofuran to prepare a coating solution. Is applied to the inner wall surface of the reactor for polymerization and dried. The total condensate concentration in the coating liquid is preferably about 0.1 to 5% by weight. This is because if the concentration is low, the effect of preventing scale is not sufficient, and if the concentration is high, the viscosity becomes high and uniform coating becomes difficult. There is no particular limitation on the amount of the coating liquid when applied, but only to be uniformly applied to the inner wall surface of the polymerization reactor, the solid content (condensate in the coating liquid per inner wall surface 1 m ² ) 0.1 ~ 50g
It is good to apply to the extent.

The method of applying the coating liquid is not particularly limited, and includes various methods such as brush coating, a method of applying the coating liquid by spraying the coating liquid from a nozzle, and a method of applying the coating liquid to a polymerization reactor. The method (spray) of spraying and spraying from a nozzle is simple and preferable. Drying of the applied coating liquid is not particularly limited,
For example, at 40 to 100 ° C, preferably 70 to 100 ° C, 5
Perform for ~ 60 minutes.

As described above, (A), (B),
A vinyl polymer was produced by a suspension polymerization method, a microsuspension polymerization method, an emulsion polymerization method, or the like by coating the scale inner surface of the reactor for polymerization with a scale inhibitor comprising the three components (C) and drying the coating. In this case, generation of scale of the vinyl polymer can be prevented for a long time. The polymerization reactor of the present invention is made of stainless steel, clad steel, nickel alloy,
Known polymerization reactors such as those manufactured by glass lining.

The vinyl polymer of the present invention refers to a polymer of a vinyl monomer and a diene monomer. More specifically, a vinyl monomer alone, a combination of vinyl monomers, a diene monomer alone, a combination of diene monomers, or a combination of a vinyl monomer and a diene monomer Refers to a polymer obtained by Vinyl monomers include vinyl chloride, vinyl acetate, acrylonitrile,
Examples include ethylene, propylene, styrene, acrylamide, acrylic acid, and acrylate, and examples of the diene-based monomer include butadiene and isoprene. These may be used alone or in combination of two or more.

The suspension polymerization method of the present invention, the microsuspension polymerization method,
The emulsion polymerization method is a known polymerization method in which polymerization is performed in an aqueous medium using a polymerization initiator, a suspension stabilizer (dispersant), an emulsifier, and other additives. Although the present invention can be applied to various vinyl polymers and polymerization methods as described above, the effect is particularly remarkable when applied to a suspension polymerization method of vinyl chloride monomers.

The antiscalant of the present invention has excellent durability of the antiscaling effect. For example, the number of batches can be increased by 20% in a single application of a coating solution, for example, as shown in Examples below.
The scale prevention effect can be maintained up to the above continuous polymerization batch. The application of the pyrogallol condensate (A) alone can provide a scale prevention effect, but the effect persistence is small. The application of the phenol condensate (B) alone has almost no scale prevention effect. In the case of a mixture of the pyrogallol condensate (A) and the phenol condensate (B), the effect of preventing scale is obtained, but the effect is less persistent. In the case of a mixture of the phenol condensate (B) and the acidic compound (C), no scale preventing effect is observed. Further, a mixture of the pyrogallol condensate (A) and the acidic compound (C) can provide a scale preventing effect but has a small sustaining effect. This is because the crosslinking is weak. When the phenol condensate (B) and the acidic compound (C) are applied, crosslinking occurs, but there is almost no scale prevention effect. That is, even if the composition having no scale preventing effect is crosslinked, it cannot be expected that the composition has a sustained scale preventing effect.

The reason why the scale inhibitor comprising the composition of the pyrogallol condensate (A), the phenol condensate (B) and the acidic compound (C) of the present invention is extremely excellent in the persistence of the scale prevention effect is as follows. This is considered to be because the composition of the present invention is crosslinked, so that the adhesiveness to the inner wall surface of the polymerization vessel and the like is improved, and the solubility and abrasion resistance to the polymerization medium are also improved. That is, although the mechanism is not clear, the pyrogallol condensate (A) is cross-linked by using the acidic compound (C) as a catalyst, while a small amount of the phenol condensate (B) is used as a cross-linking aid to form the pyrogallol condensate. It is considered that the sustainability of the scale prevention effect of (A) is improved. The degree of crosslinking can be easily determined from the solubility of these compositions in a 0.1 N sodium hydroxide solution which is a good solvent.

[0019]

The present invention will be described in more detail with reference to the following Examples, which do not limit the present invention in any way.

Examples 1 to 6 and Comparative Examples 1 to 6 (1) Production of Condensate Preparation Example 1 [Pyrogallol Condensate (A)] In a glass reactor having an inner volume of 0.5 L, 400 cc of water and 0.1 g of pyrogallol were added. 2 mol, formaldehyde 0.6 mol, 1
After charging 1 cc of normal sodium hydroxide and conducting a condensation reaction at 70 ° C. for 3 hours, 3 cc of 1N hydrochloric acid was added. After the reaction was completed, the reaction solution was poured into 1.2 L of water, and the resulting precipitate was filtered with filter paper. Filtration yielded 8 g of the desired product.

Production Example 2 [Phenol condensate (B)] A glass reactor having an inner volume of 0.5 L was charged with 100 cc of water, 0.2 mol of phenol, 0.4 mol of formaldehyde and 10 cc of 1N sodium hydroxide. After a condensation reaction at 80 ° C. for 5 hours, 30 cc of 1N hydrochloric acid was added, and after the reaction was completed, the reaction solution was poured into 500 cc of water. After separation into two layers, 27 g of the desired product in the lower layer was obtained.

(2) Preparation of scale inhibitor and coating solution As shown in Table 1, the pyrogallol condensate (A) obtained in Production Example 1 and the phenol condensate (B) obtained in Production Example 2 Was changed and the mixture was dissolved in methyl alcohol such that the mixture concentration became 1% by weight. Next, as an acidic compound (C), 10% by weight of P-toluenesulfonic acid was added to and dissolved in a mixture of the condensates (A) and (B) to prepare a coating solution.

(3) Application of Coating Solution and Production of Vinyl Polymer The coating solution was applied by spraying onto the inner wall of a polymerization reactor which had been washed beforehand, and dried at 70 ° C. for 30 minutes. The applied amount of solids (condensate) per coated area is about 0.5.
It was 5 g / m ² . Using the polymerization reactor coated with the scale inhibitor as described above, the following polymerization recipe-
1. The polymerization reaction of Polymerization Formulation-2 was repeatedly carried out, and the scale adhesion state was visually observed and evaluated according to the following criteria. Table 1 shows the results. ：: No scale adhesion was observed on the wall surface. Δ: Scale adhered to part of the wall. ×: Scale adhered to the entire wall surface.

Polymerization recipe-1: Suspension polymerization method of vinyl chloride In a 1500 L stainless steel polymerization reactor equipped with a stirrer, 700 kg of water in which 250 g of partially saponified polyvinyl acetate was dissolved, 550 kg of vinyl chloride, and di-2- Charge 300 g of ethylhexyl peroxydicarbonate,
For 7 hours. Polymerization Formulation 2: Microsuspension polymerization of vinyl chloride 800 g of sodium dodecylbenzenesulfonate in a 300 L stainless steel polymerization reactor equipped with a stirrer
Dissolved in water 150 kg, vinyl chloride 100 kg, di-2-
60 g of ethylhexyl peroxydicarbonate was charged and polymerization was carried out at 50 ° C. for 7 hours.

[0025]

[Table 1]

From the results in Table 1, it can be seen that the scale inhibitor of the present invention has a very good scale-inhibiting effect in the suspension polymerization method and the microsuspension polymerization method, and the effect in the suspension polymerization method is particularly large. You can see that.

[0027]

Industrial Applicability The scale inhibitor for vinyl polymers of the present invention exhibits an excellent scale-inhibiting effect and is excellent in the persistence of the effect, and its industrial value is extremely large.

Claims (3)

[Claims] 1. A scale inhibitor for a vinyl polymer, comprising a condensate (A) of pyrogallol and formaldehyde, a condensate (B) of phenol and formaldehyde, and an acidic compound (C). 2. A condensate of pyrogallol and formaldehyde (A) / a condensate of phenol and formaldehyde (B) in a weight ratio of 25/1 to 3/1, and the acidic compound (C) is composed of (A) and (B). The scale inhibitor according to claim 1, which is 5 to 20% by weight based on the total amount of the scale inhibitor. 3. The scale inhibitor according to claim 1, wherein the acidic compound (C) is P-toluenesulfonic acid, benzenesulfonic acid or a mixture thereof.