JPH0662709B2 - Vinyl chloride polymerization - Google Patents

Description

The present invention relates to an improved method for homo- or copolymerizing vinyl chloride, and more particularly to a method for preventing polymer adhesion to the inner wall surfaces of a polymerization vessel, etc. The present invention also relates to a coating liquid for preventing polymer adhesion to the inner wall surfaces of a polymerization vessel, etc., and a method for producing the coating liquid.

Prior Art When vinyl chloride is polymerized alone or together with a monomer copolymerizable therewith (hereinafter simply referred to as "polymerization"),
Since polymer adheres to the inner walls of the polymerization vessel, the reflux condenser, the stirring blades, the baffles, the various auxiliary piping connections, and other parts of the equipment with which the monomer comes into contact during the polymerization operation, problems arise, such as a decrease in the cooling capacity of the polymerization vessel, or the polymer that once adheres and then peels off may become mixed into the vinyl chloride homopolymer or copolymer (hereinafter referred to as the "product"), thereby degrading the quality of the product. Therefore, it is customary to clean the inside of the polymerization vessel after each polymerization and then restart the polymerization, but this requires a great deal of labor and time, resulting in a decrease in the availability of the polymerization vessel and an increase in the cost of the product.

Therefore, methods have been proposed in the past in which agents are applied to the inner walls of the polymerization vessel and other parts to prevent the adhesion of polymers.

However, although these methods are effective in preventing polymer adhesion, they have various drawbacks, such as slowing the polymerization rate and deteriorating the physical properties of the product, and none of them is satisfactory for industrial use. Furthermore, methods that do not adversely affect the polymerization rate or the physical properties of the product have been proposed, but these methods are not very effective in preventing polymer adhesion. For example, a method of applying a co-condensation product of resorcinol and aldehydes has been proposed (Japanese Patent Laid-Open Publication Nos. 57-502169 and 57-502170), but the effectiveness in preventing polymer adhesion is still insufficient.

OBJECTS OF THE INVENTION The primary object of the present invention is to provide a method for effectively preventing adhesion of polymer to the inner wall surfaces of a polymerization vessel or the like during the homo- or copolymerization of vinyl chloride.

Another object of the present invention is to provide a coating agent for preventing polymer adhesion to the inner wall surface of a polymerization vessel or the like.

It is yet another object of the present invention to provide a method for producing a coating agent for preventing adhesion.

SUMMARY OF THE INVENTION In one embodiment of the present invention, a coating solution containing a coating agent is applied to the inner walls of a polymerization vessel and to parts of the apparatus that come into contact with the monomer during polymerization. The coating solution is an aqueous solution adjusted to a specific pH value, i.e., a pH such that the coating agent dissolves at the temperature at which it is applied and precipitates when heated on the inner walls of the polymerization vessel. When such a coating solution is used, the coating agent forms a thin, uniform and strong film on the inner walls of the polymerization vessel, thereby providing an excellent effect of preventing polymer adhesion.

In another embodiment of the present invention, there is provided a coating liquid having the effect of preventing polymers from adhering to the inner walls of a polymerization vessel, etc. A typical example of the coating agent is a solution containing a modified condensate of phenol and aldehyde.

In another preferred embodiment, the vinyl chloride polymerization method of the present invention comprises, when polymerizing vinyl chloride in an aqueous medium or in bulk, pre-polymerizing a dihydroxybiphenyl with an aldehyde in the presence of an acidic catalyst on the inner wall of a polymerization vessel and on parts of the apparatus that come into contact with the monomer during the polymerization operation,
The resulting reaction product having a molecular weight of 500 to 100,000 is then coated.

In another embodiment of the present invention, the coating agent applied to the inner wall of the polymerization vessel and to parts of the apparatus that come into contact with the monomer during polymerization is a co-condensate obtained by further reacting a precondensate of a phenol with an aldehyde with a compound containing at least a hindered phenol.

In yet another embodiment of the present invention, the coating liquid applied to the inner wall of the polymerization vessel and to the equipment parts that come into contact with the monomer during polymerization is an alkaline aqueous solution containing a coating agent having a phenolic hydroxyl group, and the coating agent has a pH of 8.0 or higher and a degree of precipitation of 35% or less when precipitated from the solution at room temperature.

The coating agent preferably has a weight-average molecular weight of 500 to 100,000 and is obtained by further reacting an initial condensation product of a phenol and an aldehyde with o-sec-butylphenol (hereinafter referred to as "OSBP") and a polyhydric phenol in the presence of a strong acid catalyst.

According to another aspect of the present invention, there is provided a method for producing a coating liquid that prevents adhesion of vinyl chloride polymer to the inner wall surface of a polymerization vessel or the like for polymerizing vinyl chloride.

The present invention further provides a method for producing a coating liquid to be applied to the inner wall of a polymerization vessel and to equipment parts that come into contact with monomers during polymerization, the method comprising the steps of: forming a precondensation product of a phenol and an aldehyde;
The method includes the steps of further reacting the obtained initial condensate with OSBP, a nitrogen-containing compound, or a polyhydric phenol to produce a modified phenolic resin, diluting the reaction product liquid containing the modified phenolic resin with water, adjusting the pH of the diluted liquid to precipitate the modified phenolic resin, and dissolving the precipitated modified phenolic resin in an organic solvent or an alkaline aqueous solution.

BRIEF DESCRIPTION OF THE DRAWINGS The drawing is a deposition curve diagram of a coating liquid used in one embodiment of the present invention.

Detailed Description of the Invention In one embodiment of the present invention, the coating liquid to be applied to the inner wall surface of a polymerization vessel or the like is adjusted to a certain pH value, i.e., a pH that dissolves at the temperature at which it is applied and precipitates the coating agent when heated on the inner wall of the polymerization vessel or the like. The most preferred coating agent is a modified product obtained by modifying a resol-type precondensate obtained by reacting phenols and aldehydes under alkaline conditions with various modifying agents. Examples of phenols include phenolic acid,
Monohydric phenols such as cresol and ethylphenol,
Examples of suitable aldehydes include dihydric phenols such as resorcinol and hydroquinone, bisphenols such as bisphenol A, and their substituted derivatives. These may be used alone or in combination of two or more. Aldehydes include, for example, organic compounds having a CHO group, such as formaldehyde, acetaldehyde, and furfural. These may be used alone or in combination of two or more. Among these, carbolic acid is preferred as a phenol, as it is industrially inexpensive and readily available, and formaldehyde is preferred as an aldehyde. Modifiers include, for example, alkylphenols and polyhydric phenols. However, the present invention encompasses the use of all substances other than those listed above, as long as they are soluble at the temperature during application when adjusted to a predetermined pH and precipitate the coating agent when heated on the inner wall of a polymerization vessel, etc. Preferred examples include co-condensates of pyrogallol and aldehydes, and self-condensates of polyhydric phenols such as resorcinol.

In carrying out the present invention, the coating agent is dissolved in a 0.05-5 wt% aqueous solution of alkali metal or alkaline earth metal hydroxide to a concentration of 0.1-10.0 wt%, preferably 0.2-6.0 wt%. A concentration of less than 0.1 wt% is undesirable because it requires a large amount of liquid for application, reducing workability and further reducing the effectiveness of preventing polymer adhesion. Concentrations above 10.0 wt% are uneconomical because it is difficult to apply the agent uniformly to the wall surface and requires a large amount of application. Furthermore, the high concentration applied can adversely affect product quality if rinsing with water after application is insufficient. Here, sodium hydroxide, potassium hydroxide, and calcium hydroxide are particularly preferred as alkali metal or alkaline earth metal hydroxides, with sodium hydroxide being evenly preferred. These are used as aqueous solutions.

Furthermore, it is preferable to adjust the pH with an inorganic acid or an organic acid so that the pH is 0.2 to 4.0 higher than the pH at which the coating agent, i.e., the active ingredient in the coating solution precipitates at room temperature.
More preferably, the pH is adjusted to a range of 0.3 to 3.0 higher. If the adjusted pH is lower than 0.2, the coating agent in the coating solution may precipitate over time, which is undesirable. On the other hand, if the pH is higher than 4.0, even if the wall surface is heated to a high temperature during application, depending on the type of coating agent, the coating agent may not enter the precipitation zone, resulting in insufficient polymer adhesion prevention, which is undesirable. Examples of acids for adjusting the pH include inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid, and nitric acid, and organic acids such as ascorbic acid, acetic acid, citric acid, and mercaptopropionic acid.

When applying the coating liquid of the present invention to the inner wall of a polymerization vessel or the like, it is desirable to heat the wall surface to a temperature in the range of 40°C or higher and up to 100°C. If the temperature is lower than 40°C, even if a coating liquid adjusted to the specified pH is used, it will not enter the precipitation zone of the coating agent, as is clear from the precipitation curve diagram in the drawing, and the effect of preventing polymer adhesion will be inferior.
Applying a temperature exceeding 100°C is not practical because it takes a long time to heat up. A more preferable wall temperature is 45 to 95°C.
A more preferable range is 50 to 90° C. After coating, the coated surface may or may not be washed with water, but it is advantageous to wash with water in order to prevent the produced polymer from becoming discolored.

In the method of the present invention, it is necessary to apply a coating agent to the inner wall of the polymerization vessel under the above-mentioned conditions. The method for applying the coating agent is not particularly limited, but can be a common method such as brushing, spraying, or rinsing. A coating amount of 0.005 to 10 g/ ^m2 (weight of coating agent) is usually sufficient, and is preferably in the range of 0.01 to 5 g/ ^m2 . An amount less than 0.005 g/ ^m2 dilutes the coating agent, resulting in a poor polymer adhesion prevention effect. An amount exceeding 10 g/ ^m2 does not improve the polymer adhesion prevention effect, wastes the coating agent, and is uneconomical. Furthermore, if the coating agent is not thoroughly rinsed with water after application, the product quality will be adversely affected, which is undesirable.

The coating liquid may be applied before the start of each batch polymerization, or it may be applied once to carry out polymerization for several batches or more, with simple washing with water being carried out after each batch.

The present invention can be effectively applied not only to the homopolymerization of vinyl chloride but also to the copolymerization of vinyl chloride with at least one other polymerizable monomer and a polymer capable of graft polymerizing with vinyl chloride.

Other polymerizable monomers that can be used include vinyl esters such as vinyl acetate, vinyl propionate, vinyl caproate, vinyl laurate, and vinyl stearate;
olefins such as ethylene, propylene, and isobutylene; alkyl vinyl ethers such as isobutyl vinyl ether, octyl vinyl ether, dodecyl vinyl ether, and phenyl vinyl ether; halogenated olefins such as vinylidene chloride, vinyl fluoride, propylene chloride, and vinyl bromide; acrylic acid and methacrylic acid esters such as ethyl acrylate, n-butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, and stearyl methacrylate; acrylic derivatives such as acrylic acid, methacrylic acid, crotonic acid, acrylonitrile, maleic anhydride, and itaconic anhydride;
Examples include:

In addition, examples of polymers that can be graft-polymerized with vinyl chloride include ethylene-vinyl acetate copolymer (EVA), ethylene-
Ethyl acrylate copolymer, chlorinated polyethylene, polyurethane, polybutadiene-styrene-methyl methacrylate (MBS), polybutadiene-acrylonitrile
Examples include (α-methyl)styrene (ABS), polybutyl acrylate, butyl rubber, polystyrene, styrene-butadiene copolymer, cross-linked acrylic rubber, and the like.

Other preferred coating agents for use in the method of the present invention are reaction products of dihydroxybiphenyls and aldehydes, as shown in the general formula below:

(In the formula, R is a hydrogen atom or an alkyl group, cycloalkyl group, aryl group or aralkyl group having 1 to 8 carbon atoms, X is a carboxyl group, alkyl group or cycloalkyl group, m is an integer of 0 to 2, and n is an integer of 2 to 500.) Examples of dihydroxybiphenyls that can be used in the present invention include 2,2'-dihydroxybiphenyl, 2,2'-
dihydroxy-5,5'-dimethylbiphenyl, 2,2'-dihydroxy-4,4',5,5'-tetramethylbiphenyl,
2,2'-dihydroxy-5,5'-dichlorobiphenyl, 2,
Examples include 2'-dihydroxy-5,5'-dicyclohexylbiphenyl and 2,2'-dihydroxy-5,5'-di-tert-butylbiphenyl, and among these, 2,2'-dihydroxyphenyl is particularly preferred from an industrial standpoint.

Examples of aldehydes include formalin, acetaldehyde, propionaldehyde, butylaldehyde, acrolein, crotonaldehyde, benzaldehyde,
Examples include furfural, phenylacetaldehyde, 3-phenylpropionaldehyde, and 2-phenylpropionaldehyde, but formalin and acetaldehyde are industrially and economically advantageous.

In the process of the present invention, dihydroxybiphenyls and aldehydes are reacted in the presence of an acid catalyst to form a reaction product. Preferred catalysts for this reaction are strong acids, such as sulfuric acid, hydrochloric acid,
Perchloric acid, p-toluenesulfonic acid, methanesulfonic acid,
Examples include trifluoromethanesulfonic acid, but more preferred are hydrochloric acid and p-toluenesulfonic acid.

In the practice of the present invention, the reaction product of dihydroxybiphenyls and aldehydes is more preferably obtained when the molar ratio of aldehydes to dihydroxybiphenyls is not greater than 1.0. A preferred range is a molar ratio of aldehydes to 1 mole of dihydroxybiphenyls of 0.5 to 1.0 moles, more preferably 0.6 to 0.9 moles. If this molar ratio is greater than 1.0, the molecular weight of the resulting reaction product will be too high, making it difficult to apply the coating liquid. Conversely, if the molar ratio is 0.5 or less, the molecular weight will be too low, making the applied coating prone to peeling, which is undesirable.

The reaction of dihydroxybiphenyls with aldehydes is as follows:
The reaction is advantageously carried out at a temperature in the range of 50 to 200°C, more preferably 100 to 150°C. The presence of a common solvent may be desirable in this reaction. Examples of suitable solvents include, but are not limited to, aromatic hydrocarbons such as benzene, toluene, and xylene; halogenated hydrocarbons such as dichloroethane, trichloroethane, and monochlorobenzene; ethers such as butyl methyl ether, methoxyethanol, diethylene glycol, and dimethyl ether; and ketones such as methyl ethyl ketone and methyl isobutyl ketone.

In the present invention, the molecular weight of the reaction product of dihydroxybiphenyls and aldehydes is an important factor. Experimental results have shown that a good polymer adhesion prevention effect is obtained when the molecular weight is in the range of 500 to 100,000, preferably 1,000 to 50,000.

The theoretical basis for preventing polymer adhesion by applying the above-described reaction product to the inner wall of a vinyl chloride polymerization vessel is not clear, but it is thought that the hydroxyl groups located on the side chains of this reaction product have a radical-scavenging effect, preventing the polymerization of vinyl chloride on the inner surface of the vessel.

In the present invention, it is advantageous to apply an aqueous solution of the reaction product of a dihydroxyphenyl compound and an aldehyde compound to the inner wall of a polymerization vessel.
The reaction product is dissolved in an aqueous solution of alkali metal hydroxide (wt %) to a solids concentration of 0.1 to 10 wt %, and the pH is adjusted to 8 to 3 with an inorganic or organic acid.

To adjust the pH, inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, etc., or organic acids such as ascorbic acid, acetic acid,
Citric acid, mercaptopropionic acid, etc. can be used.

Instead of the aqueous solution, a solution of the reaction product dissolved in an organic solvent may be applied. The organic solvent is a solvent that dissolves the reaction product,
Any solvent that does not affect the polymerization reaction or the physical properties of the polymer may be used, for example, tetrahydrofuran, dioxane, methanol, ethanol, acetone, chloroform, and mixtures thereof.

When applying the coating liquid to the inner wall surface of a polymerization vessel or the like, the wall surface to be coated is preferably heated to 40 to 100°C before coating and then washed with water. Caustic soda is generally used as the alkali metal hydroxide for dissolving the solids, and is preferred.

In the method of the present invention, it is necessary that the reaction product of the dihydroxybiphenyls and the aldehydes be present on the vessel wall that comes into contact with the monomer. The reaction product can be applied by brushing, spraying, or other methods. The amount of application is not particularly limited, but is usually in the range of 0.005 to 10 g/ ^m² , preferably 0.01 to 5 g/ ^m² , in terms of solids. Application may be carried out before the start of polymerization for each batch, or the process may be repeated for several batches after application, with simple water rinsing between each batch.

Another coating agent that can be used in the present invention is a precondensation product of phenols and aldehydes, which is mixed with at least OSB.
The modifier may further contain a nitrogen-containing compound or a polyhydric phenol in addition to OSBP.

More specifically, this coating agent is obtained by subjecting a phenol and an aldehyde to an addition reaction, as described above, followed by co-condensation with a modifier.

Examples of the nitrogen-containing compound include nitrophenols, nitrobenzoic acids, nitrobenzenesulfonic acids, aminophenols, aminobenzoic acids, and aminobenzenesulfonic acids.

Furthermore, examples of polyhydric phenols include catechol, resorcinol, hydroquinone, pyrogallol, and phloroglucinol.

In this invention, a resole-type initial condensation product of phenols and aldehydes is first prepared using a basic catalyst. In this case, the aldehydes are used in excess relative to the phenols. The reaction is generally carried out at a temperature of 60-90°C for 1-6 hours. In this manner, resols containing mainly mono- to penta-nuclear groups are prepared. A modifier is added to the prepared resole and the reaction is continued at a temperature of 60-90°C until the desired molecular weight is reached, yielding a coating agent.

In the reaction to obtain this coating agent, the modifier OSB
The P, nitrogen-containing compound, and polyhydric phenols are each added in an amount of 0.01 to 2.0 moles, preferably 0.02 to 0.8 moles, per mole of the original phenols. If the amount is less than 0.01 mole, the polymer adhesion prevention effect is poor, and if the amount exceeds 2.0 moles, the addition of more than this amount does not significantly improve the adhesion prevention effect, but rather increases the cost and reduces the reaction yield, which is undesirable.

The average molecular size of the coating agent is preferably 400 to 12,000 in weight average molecular weight (hereinafter abbreviated as "Mw"), and more preferably 600 to 4,000.
If the Mw is less than 0, the coating agent becomes water-soluble and dissolves, resulting in a poor polymer adhesion prevention effect, which is undesirable.
If the molecular weight exceeds 12,000, the condensation reaction proceeds to a high degree, and the condensate is crosslinked, resulting in a decrease in hydrophilicity, which is undesirably inferior in the polymer adhesion prevention effect.

In carrying out the present invention, the coating liquid is an alkaline aqueous solution, and the concentration of the coating agent is 0.1 to 10.0 wt.
%, preferably 0.05 to 5 wt% so as to be 0.2 to 6.0 wt%
It is dissolved in an aqueous solution of alkali metal or alkaline earth metal hydroxide. If the concentration of the coating agent is less than 0.1 wt%, the amount of liquid required for application becomes too large, which reduces workability.
Furthermore, the polymer adhesion prevention effect is inferior, which is undesirable. Conversely, if the concentration exceeds 10.0 wt%, it becomes difficult to apply the agent evenly to the wall surface, and the amount of application becomes large, which is uneconomical. Furthermore, since the agent is applied at a high concentration, if the agent is not sufficiently rinsed with water after application, the components will leach out, adversely affecting the quality of the product. The "alkali metal or alkaline earth metal hydroxide" referred to here is preferably sodium hydroxide, potassium hydroxide, or calcium hydroxide, and more preferably sodium hydroxide, which is usually used as an aqueous solution.

In another embodiment of the present invention, the coating liquid applied to the inner wall surface of a polymerization vessel or the like is an alkaline aqueous solution containing a coating agent having a phenolic hydroxyl group, and the coating agent has a pH of 8.0 or higher and a precipitation rate of 35% or lower when precipitated from the solution at room temperature. Here, the "precipitation rate" refers to the ratio (wt%) of the amount of water to the total amount of the coating agent precipitated from the alkaline aqueous solution containing the coating agent with acid, dried, dissolved in methanol, adjusted to a coating agent concentration of 0.4%, and then added to the solution. The amount of water measured at the time the coating agent precipitates and the solution begins to become cloudy is measured.

The coating agent preferably has a weight-average molecular weight of 500 to 10,000 and is obtained by further reacting an initial condensation product of a phenol and an aldehyde with OSBP and a polyhydric phenol in the presence of a strong acid catalyst.

By using aldehydes other than formaldehyde to react with organic compounds having hydroxyl groups, such as phenols, OSBP, and polyhydric phenols, used in the present invention, the pH at which the coating agent precipitates in an aqueous solution containing the coating agent at room temperature is 8.0 or higher, and the degree of precipitation is low, at 35% or less.

This is thought to be because, when the coating liquid is applied and then washed with water, the pH of the water is usually 5 to 7, so the coating agent precipitates and adheres firmly to the wall surface, etc., and does not dissolve even during the subsequent vinyl chloride polymerization reaction.

It is believed that OSBP and polyhydric phenols are effectively arranged in the resol skeleton in the presence of a strong acid catalyst, creating a stable coating agent.

The mechanism by which the polymer adhesion is prevented is not clear, but it is thought that when the coating liquid is applied to the wall surface, a thin film of the coating agent adheres firmly to the wall surface, acting as a radical scavenger, or that the wall surface is hydrophilic, making it oil-repellent and repelling vinyl chloride monomer.

Furthermore, since the coating agent appears to be partially three-dimensional, it is unlikely to dissolve in the vinyl chloride polymerization reaction solution, and it certainly does not slow down the polymerization rate.

The phenols used in the synthesis of the coating agent in the present invention include, for example, monohydric phenols such as phenol, cresol, and ethylphenol, dihydric phenols such as resorcinol and hydroquinone, bisphenols such as bisphenol A, and substituted derivatives thereof, which may be used alone or in combination of two or more.

Aldehydes are organic compounds having a CHO group, such as acetaldehyde, benzaldehyde, and furfural, and these can be used alone or in combination of two or more kinds.

In addition, a catalyst is used in the synthesis of the initial condensation product of a phenol and an aldehyde. The catalyst is a basic catalyst, such as sodium hydroxide, potassium hydroxide, ammonia, or an amine. These may be used alone or in combination of two or more.
Among these, sodium hydroxide is generally preferred because it is industrially inexpensive and readily available.

As described above, phenols and aldehydes are subjected to an addition reaction (hereinafter referred to as "one-step reaction"), and then OSB
P and a polyhydric phenol are added and co-condensed (hereinafter referred to as "two-stage reaction").

Examples of polyhydric phenols include catechol, resorcinol, hydroquinone, pyrogallol, and phloroglucinol.

Furthermore, examples of the strong acid catalyst include sulfuric acid, hydrochloric acid, perchloric acid, p-toluenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, etc. Preferred are hydrochloric acid and p-toluenesulfonic acid.

In the present invention, a resol-type initial condensation product of phenols and aldehydes is first prepared using a basic catalyst. In this case, the aldehydes are used in excess relative to the phenols. The ratio of the aldehydes to 1.0 mol of phenols is preferably 1.1 to 3.0 mol, more preferably 1.2 to 2.0 mol.
The basic catalyst is in the range of moles.
The amount is preferably 0.02 to 0.5 mol, more preferably 0.05 to 0.3 mol, per 1.0 mol.

The reaction is generally carried out at a temperature of 70 to 150°C for 1 to 6 hours.
In this way, resols mainly containing 1 to 5 nuclei are prepared. OSBP and polyhydric phenols are added to the prepared resol, and the reaction is carried out at a temperature of 70 to 180°C in the presence of a strong acid catalyst.
The mixture is reacted at 150°C for 1 to 6 hours to obtain a coating agent.

In the two-stage reaction, OSBP and polyhydric phenols are added in an amount of 0.01 to 2.0 moles, preferably 0.02 to 0.8 moles, per mole of the original phenol. If the amount is less than 0.01 mole, the polymer adhesion prevention effect is poor, while if the amount exceeds 2.0 moles, the adhesion prevention effect is not significantly improved, and the cost increases and the reaction yield decreases, which is undesirable.

Furthermore, the amount of the strong acid catalyst is preferably 0.02 to 0.5 moles, more preferably 0.05 to 1.0 moles of the original phenol.
The range is 0.3 moles.

The reaction to obtain the coating agent is characterized by the fact that the aldehydes used in the first-stage reaction are other than formaldehyde, that the catalyst in the second-stage reaction is a strongly acidic catalyst, and that the second-stage reaction proceeds more efficiently when the ratio of the catalyst in the first-stage reaction is lower than that in the second-stage reaction, and more slowly when the ratio is higher.

The average molecular size of the coating agent is preferably a weight-average molecular weight (Mw) of 500 to 10,000, and more preferably 600 to 5,000. If Mw is less than 500, the coating agent becomes water-soluble and elutes, resulting in a poor polymer adhesion prevention effect, which is undesirable.

If Mw exceeds 10,000, the condensation reaction proceeds to a high degree, and the condensate is crosslinked, resulting in a decrease in hydrophilicity, which is undesirable as it results in a poor effect of preventing polymer adhesion.

In carrying out the present invention, the coating agent is an alkaline aqueous solution, and the concentration of the coating agent is 0.1 to 10.0 wt.
%, preferably 0.05 to 5 wt% so as to be 0.2 to 6.0 wt%
It is dissolved in an aqueous solution of alkali metal or alkaline earth metal hydroxide. If the concentration of the coating agent is less than 0.1 wt%, the amount of liquid required for application becomes too large, which reduces workability.
Furthermore, the polymer adhesion prevention effect is inferior, which is undesirable. Furthermore, if the concentration exceeds 10.0 wt%, it becomes difficult to apply the agent evenly to the wall surface, and the amount of application becomes large, which is uneconomical. Furthermore, since the agent is applied at a high concentration, if the agent is not sufficiently rinsed with water after application, the components will leach out, adversely affecting the quality of the product. The alkali metal or alkaline earth metal hydroxide referred to here includes various types, but sodium hydroxide, potassium hydroxide, and calcium hydroxide are preferred, and sodium hydroxide is even more preferred, and these are usually used as aqueous solutions.

An excellent coating agent that can effectively prevent polymer adhesion can also be prepared by diluting the reaction product obtained in the form of an aqueous alkaline solution with water after the completion of the reaction to produce the modified co-condensation product of the type described above, adding an acid to the solution to adjust the pH so that the co-condensation product precipitates, separating the precipitate, and dissolving it in a solvent. Preferred solvents are organic solvents and aqueous alkaline solutions. The aqueous alkaline solution contains an alkali concentration 1 to 20 times the minimum concentration within the range that can dissolve a predetermined amount of the precipitate.

In preparing this coating solution, it is important to effectively precipitate the modified phenolic resin from the reaction product. That is, when adjusting the pH by adding an acid to the reaction product, it is desirable to adjust the concentration of the modified phenolic resin in the reaction product beforehand. The preferred concentration range is 3 to 20 wt%, more preferably 5 to 15 wt%.
If the concentration is less than 3 wt%, the particles of the modified phenolic resin that precipitate will be too fine to be easily filtered, whereas if the concentration is more than 20 wt%, a large amount of the modified phenolic resin will harden and deposit at the bottom of the container, making subsequent operations difficult.

The proper precipitation of the modified phenolic resin is achieved by adjusting the pH of the diluted reaction product to preferably 1.0 to 5.0, more preferably 1.5 to 3.0, by adding an acid. If the pH is less than 1.0, even if the separated modified phenolic resin is washed with water, there is a risk of corrosion of the walls of the polymerization vessel when it is dissolved in an organic solvent and applied, and the yield of the modified phenolic resin is not improved. On the other hand, if the pH is less than 1.0,
If the pH exceeds 5.0, the yield of the modified phenolic resin will be low. The acid used to adjust the pH is suitably a strong acid, and among these, hydrochloric acid and sulfuric acid are preferred.

The modified phenolic resin precipitated from the reaction product is subjected to vacuum filtration or centrifugation to remove impurities such as water, acid, unreacted materials, water-soluble oligomers, etc. The modified phenolic resin is then washed with water at 10 to 70°C.
Washing with water is done to remove remaining impurities and is usually done with water at room temperature, but using hot water is more efficient. The washed modified phenolic resin is dried, crushed if necessary, and dissolved in an organic solvent or alkaline aqueous solution to form a coating solution.

(1) When dissolved in an organic solvent: The concentration of the coating agent in the organic solvent is preferably 0.03 to
0.3 wt%, more preferably 0.06 to 1.5 wt%.
If the concentration is less than 0.3 wt%, the amount of coating solution required will be too large, reducing workability and not providing a satisfactory polymer adhesion prevention effect. On the other hand, if the concentration exceeds 0.3 wt%, excessive coating solution is likely to be applied to some areas, resulting in the application of a larger amount of coating agent than necessary, which is uneconomical. In addition, the vinyl chloride polymerization reaction time will be prolonged, resulting in product discoloration and other disadvantages.

The appropriate amount of coating agent to be applied to the wall surface of a polymerization vessel or the like is 0.02 to 8.0 gm ² , more preferably 0.05 to 4.0 gm ² .

The organic solvent used is selected from those that can dissolve the modified phenolic resin and do not adversely affect the modified phenolic resin. Preferred examples of the organic solvent include tetrahydrofuran, dioxane, methanol, ethanol, acetone, chloroform, and any combination thereof.

(2) When dissolved in an alkaline aqueous solution: The solubility of the modified phenolic resin in an alkaline aqueous solution increases as the alkali concentration in the alkaline aqueous solution increases. In the present invention, an alkaline aqueous solution containing a small amount of alkali necessary to dissolve the required amount of modified phenolic resin is used. The concentration of the modified phenolic resin in the alkaline aqueous solution is preferably 0.1 to 8.0 wt%, more preferably 0.2 to 4.0 wt%. If the concentration is less than 0.1 wt%, the amount of coating liquid required increases, reducing workability, and
It is not possible to obtain a good polymer adhesion prevention effect.
If the amount exceeds t%, there are likely to be areas where the amount of coating liquid applied is excessive, resulting in an uneconomical application of a larger amount of coating agent than necessary. In addition, this will prolong the polymerization reaction time of vinyl chloride, resulting in disadvantages such as discoloration of the product.

The alkali concentration required to dissolve the modified phenolic resin at this preferred concentration is in the range of 0.01 to 2.0 wt %.
For example, when sodium hydroxide is used as the alkali, the minimum alkali concentration required is 0.01 to 2.0 wt.
The range of t% is used, and this value varies depending on the concentration of the modified phenolic resin. For example, when the concentration of the modified phenolic resin is 4.0, 2.0, and 1.0 wt%, the appropriate concentrations of sodium hydroxide solution are 0.15, 0.10, and 0.05 wt%, respectively.

The amount of alkali used is preferably 1 to 20 times the minimum concentration, more preferably 1 to 10 times, and particularly preferably 1 to 5 times.
If the amount of alkali used exceeds 20 times the minimum concentration, the effect of preventing polymer adhesion is inferior, which is not preferred.

As alkali, in addition to sodium hydroxide, potassium hydroxide and potassium hydroxide can be used advantageously.

The method of the present invention eliminates the need to perform jet washing at the end of each batch in order to remove polymer adhering to the inside of a polymerization vessel, and can extremely effectively prevent polymer adhesion to the inside of a polymerization vessel by simply performing water washing while maintaining the conventional polymerization rate, without adversely affecting the quality of the product obtained, and is therefore industrially valuable.

The present invention will be explained in more detail below with reference to examples.

However, these examples are merely illustrative and the present invention is not limited to these examples.

In the examples, all percentages are by weight unless otherwise specified.

EXAMPLES Production Example 1 (Phenol/aldehyde initial condensate) 100.0 g (1.064 g) of phenolic acid was placed in a three-necked flask equipped with a reflux condenser.
129.4 g (1.596 mol), 37.0% formalin, and 1.7 g (0.043 mol) of sodium hydroxide were charged, and the mixture was heated to 85°C under stirring.
The temperature was raised to 100°C in 30 minutes.
The viscosity of the resol thus obtained was measured at 85°C using a Brookfield viscometer and found to be 10
The residual formalin content was analyzed by the sodium sulfite method and found to be 0.12%. Furthermore, the weight average molecular weight (M
w) was 420.

Production Example 2 (Resol-based coating agent) 200 g of the resol obtained in Production Example 1 was placed in a three-neck flask equipped with a reflux condenser, and resorcinol 2 was added as a modifier.
The mixture was heated to 85°C over 30 minutes with stirring, and the condensation reaction was continued while maintaining this temperature. When the viscosity reached 1,000 cps using a Brookfield viscometer, the temperature was lowered and an aqueous sodium hydroxide solution was added to terminate the reaction. The pH of the resulting condensation product was 11.1, and the Mw was 1,550.

Example 1 The condensate obtained in Production Example 2 was used as a coating agent at a concentration of 2%
The alkaline aqueous solution thus obtained was adjusted to pH 7.0 with citric acid to prepare a coating solution.

Separately, a stainless steel polymerization tank with an internal volume of 71 L and equipped with stirring blades and baffles was used, and the jacket was heated so that the temperature of the inner wall of the polymerization tank, etc., reached 70°C. The above coating liquid was sprayed with a sprayer onto each of the areas that would come into contact with the vinyl chloride monomer to be charged later, such as the inner wall of the polymerization tank, stirring blades, baffles, and various accessory piping connections, so that the coating agent would be 0.5 g/ ^m² , and the coating film was then rinsed off by spraying water in the same manner.

After the coating was formed, 3,000 g of deionized water, 0.89 g of di-2-ethylhexyl peroxydicarbonate, 0.28 g of cumyl peroxyneodecanoate, and 2 g of partially saponified polyvinyl alcohol (80% saponification degree) were charged into the polymerization vessel, and the air inside was removed using a vacuum pump. Then, 2,000 g of vinyl chloride was added, and the reaction was continued at 58°C until the pressure reached 6.5 kg/ ^cm² -G. After the reaction was completed, the unreacted monomer was recovered, the slurry was discharged, and the inner walls of the polymerization vessel were rinsed with water. A second polymerization was then carried out in the same manner as above, except that the coating solution was not applied. This polymerization was then repeated four times in succession. The weight of the polymer adhering to the inner walls of the polymerization vessel was measured and found to be 0.4 g/ ^cm² . The slurry was dehydrated and dried, and the product was obtained. The physical properties were measured using the test methods described below. The method of the present invention significantly reduced the amount of polymer adhesion, and the polymer adhesion could be easily washed away with simple water washing. There was no delay in reaction time, and the physical properties of the obtained product were excellent. The results are shown in Table 1.

Comparative Example 1: The same procedure as in Example 1 was repeated except that no coating liquid was applied.
As is clear from the results in Table 1, the amount of polymer attached was extremely large.

Comparative Example 2 When applying the coating liquid, the inner wall of the polymerization vessel was heated to 70°C.
The same procedure as in Example 1 was carried out except that the temperature was kept at room temperature instead of being heated.
As is clear from the results in Table 1, the amount of polymer attached was slightly large.

Production Example 3 (Coating Liquid) 55.9 g (0.30 mol) of 2,2'-dihydroxybiphenyl, 7.11 g (0.225 mol) of paraformaldehyde with a purity of 95%, 1.9 g of paratoluenesulfonic acid, and 100 ml of diethylene glycol dimethyl ether were charged into a reactor equipped with a thermometer and a stirrer, and the mixture was reacted at a temperature of 125 to 130°C for 17 hours.
After the reaction, the mixture was cooled and poured into 500 ml of water to precipitate a resin.

This was filtered, washed with water, and then dried to obtain 52 g of 2,2'-dihydroxybiphenyl-formaldehyde condensation resin, which had an average molecular weight of 4200. This resin was dissolved in methanol and adjusted to a solids concentration of 0.4%.

Preparation Example 4 (Coating Liquid) The 2,2'-dihydroxybiphenyl formalin condensation resin obtained in Preparation Example 3 of the coating liquid was dissolved in a 0.4% aqueous NaOH solution, and the solid concentration was adjusted to 2 wt %, and the pH was further adjusted to 5.0 with ascorbic acid.

Preparation Example 5 (Coating Liquid) 2,2'-Dihydroxy-5,5'-dichlorobiphenyl and acetaldehyde were reacted in a molar ratio of 1/0.6 in the same manner as in Coating Liquid Preparation Example 3. The average molecular weight of the reaction product was 2400. This resin was dissolved in methanol and adjusted to a solids concentration of 0.4%.

Preparation Example 6 (Coating Liquid) The same 2,2'-dihydroxy-5,5'-dichlorobiphenylacetaldehyde condensation resin as used in Preparation Example 5 of the coating liquid was dissolved in a 0.4% aqueous NaOH solution to adjust the solid concentration to 2%, and the pH was further adjusted to 5.0 with citric acid.

Preparation Example 7 (Coating Liquid) 2,2'-Dihydroxy-4,4',5,5'-tetramethylbiphenyl and formalin were reacted in a molar ratio of 1/0.7 in the same manner as in Coating Liquid Preparation Example 3. The average molecular weight of the reaction product was 3,500. This resin was dissolved in methanol and adjusted to a solids concentration of 0.4%.

Preparation Example 8 (Coating Liquid) 2,2'-Dihydroxy-4,4',5,5'-tetramethylbiphenyl and formalin condensation resin, which are the raw materials of Coating Liquid Preparation Example 7, were dissolved in a 0.5% NaOH aqueous solution, adjusted to a solids concentration of 2%, and further adjusted to pH 6.0 with phosphoric acid.

Example 2 The coating liquid prepared in Coating Liquid Preparation Example 3 was sprayed onto the inner wall of a stainless steel polymerization vessel having an internal volume of 71 l using a sprayer, and then methanol was distilled off under reduced pressure.

After these treatments, 3,000 g of deionized water, 0.6 g of t-butyl peroxypivalate, and 2 g of partially saponified polyvinyl alcohol with a saponification degree of 80% were added, and the air inside was removed with a vacuum pump. Then, 2,000 g of vinyl chloride was added, and the reaction was continued at 57°C until the pressure reached 5 kg/ ^cm²G .

After the reaction was completed, the unreacted monomer was recovered, and the polymer slurry was discharged, and the weight of the polymer adhering to the inner wall of the polymerization vessel was measured. The polymer slurry was dehydrated and dried to obtain the product. The results are shown in Table 2.

As shown in Table 2, the method of the present invention resulted in a significantly reduced amount of polymer adhesion, and the adhered polymer could be easily washed away by simple water washing.

Furthermore, there is no delay in reaction time and the physical properties of the resulting product are excellent.

Comparative Example 3 The polymerization reaction was carried out in the same manner as in Example 2, except that the coating liquid was not applied at all.
As shown in the table, the amount of polymer attached to the inner wall is extremely large.

Example 3 The inner wall of the stainless steel polymerization tank containing the liquid 71 was covered with a jacket.
The container was heated to 70°C, and the coating solution prepared in Coating Solution Preparation Example 4 was sprayed onto the inner wall using a sprayer, after which the coating was rinsed with water. After this treatment, a polymerization reaction was carried out in the same manner as in Example 2. The results are shown in Table 2. In this example, too, the amount of polymer adhesion was significantly small, and the adhered polymer could be easily washed away with simple water rinsing. There was no delay in reaction time, and the physical properties of the resulting product were excellent.

Example 4 The same procedure as in Example 2 was carried out except that the coating liquid obtained in Coating Liquid Preparation Example 5 was used. The results are shown in Table 3. In this example as well, the amount of polymer adhered was significantly small, and the adhered polymer could be easily washed away by simple water washing.

Example 5 The same procedure as in Example 3 was carried out except that the coating solution prepared in Coating Solution Preparation Example 6 was used. The results are shown in Table 3. In this example as well, the amount of polymer adhered was significantly small, and the adhered polymer could be easily washed away with simple water rinsing. There was no delay in reaction time, and the physical properties of the obtained product were excellent.

Example 6 The same procedure as in Example 2 was carried out except that the coating solution prepared in Coating Solution Preparation Example 7 was used. The results are shown in Table 3. In this example as well, the amount of polymer adhered was significantly small, and the adhered polymer could be easily washed away with simple water washing. There was no delay in reaction time, and the physical properties of the obtained product were excellent.

Example 7 The same procedure as in Example 3 was carried out except that the coating solution prepared in Coating Solution Preparation Example 8 was used. The results are shown in Table 3. According to the method of the present invention, the amount of polymer adhered was significantly small, and the adhered polymer could be easily washed away by simple water washing. There was no delay in reaction time, and the physical properties of the obtained product were excellent.

Production Example 9 (Phenol/aldehyde initial condensate) 282.0 g of phenol was placed in a three-neck flask equipped with a reflux condenser.
(3.00 mol), 37.0% formalin 356.8 g (4.40 mol)
and 4.8 g (0.12 mol) of sodium hydroxide were charged.
The temperature was raised to 85°C over 30 minutes while stirring. The reaction was continued for 2 hours and 40 minutes while maintaining this temperature. The viscosity of the resol thus obtained was measured at 85°C using a Brookfield viscometer, and was found to be 10.4 cps. Residual formalin was not detected when analyzed by the sodium sulfite method. Furthermore, the Mw measured by gel permeation chromatography was
The number was 410.

Production Example 10 (Resol-Based Coating Agent) The resol obtained in Production Example 9 was used to prepare an aqueous solution containing 2.0% coating agent and 0.2% sodium hydroxide, which was used as a coating liquid.

Production Example 11 (Co-condensation product of resorcinol and benzaldehyde) 100 ml of 1,4-dioxane was placed in a three-neck flask equipped with a reflux condenser.
and 50 g of resorcinol, then benzaldehyde
32 ml of 50% sodium hydroxide solution was added and the mixture was stirred. 1 ml of 50% aqueous sodium hydroxide solution was then added. The bath temperature was heated to 120°C and refluxed for 1 hour. The condenser was then replaced with a distillation head to distill off the water-dioxane. The reaction product was then cooled and dissolved in dilute aqueous sodium hydroxide solution.

Further hydrochloric acid was added to precipitate the coating agent, which was filtered off, dried and pulverized.

This coating agent was dissolved in a 1.0% aqueous solution of sodium hydroxide to prepare a coating solution with a coating agent concentration of 1.0%.

Production Example 12 (Resol-based coating agent) 200.0 g of the resol obtained in Production Example 9 was placed in a three-neck flask equipped with a reflux condenser, and 6.9 g of OSBP was added as a modifier.
(0.046 mol) was added, and the temperature was raised to 75°C over 20 minutes while stirring.
The reaction was continued while maintaining this temperature. When the viscosity measured using a Brookfield viscometer reached 1,300 cps, the temperature was lowered and an aqueous solution of sodium hydroxide was added to terminate the reaction. This reaction product was used to prepare an aqueous solution with a coating agent concentration of 2.0% and sodium hydroxide concentration of 0.2%, which was used as a coating liquid.

Production Examples 13 to 15 (Resol-based coating agent) 200.0 g of the resol obtained in Production Example 9 was placed in a three-neck flask equipped with a reflux condenser, and the resol obtained in Production Example 13 was added as a modifier.
In this case, 6.9 g (0.046 mol) of OSBP and 1 g of p-aminobenzoic acid were used.
In Preparation Example 14, 2.6 g (0.092 mol) of OSBP was added.
(0.046 mol) and 29.0 g (0.23 mol) of pyrogallol
In Production Example 15, 6.9 g (0.046 mol) of OSBP, 15.9 g (0.092 mol) of orthanilic acid, and 10.1 g of resorcinol were added.
(0.092 mol) was added, and the mixture was heated to 75°C over 20 minutes with stirring, and the reaction was continued while maintaining this temperature. When the viscosity measured with a Brookfield viscometer reached 1,300 cps, the temperature was lowered and an aqueous sodium hydroxide solution was added to terminate the reaction.

This reaction product was used to prepare an aqueous solution containing a coating agent at a concentration of 2.0% and sodium hydroxide at 0.2%, which was used as a coating liquid.

Example 8 The coating solution obtained in Production Example 12 was sprayed with a sprayer onto each of the locations with which vinyl chloride monomer comes into contact, such as the inner wall of a stainless steel polymerization tank equipped with stirring blades and baffles, the stirring blades, the baffles, and the connections for various auxiliary pipes, so that the coating amount was 0.5 g/ ^m² , and then the coating film was rinsed with water.

Into the polymerization tank with the coating thus formed, 3,000 g of deionized water, 0.89 g of di-2-ethylhexyl peroxydicarbonate, 0.28 g of cumyl peroxyneodecanoate, and 2 g of partially saponified polyvinyl alcohol with a degree of saponification of 80% were charged, and the air inside was removed with a vacuum pump. Then, 2,000 g of vinyl chloride was charged, and the reaction was continued at 58°C until the pressure reached 6.5 kg/ ^cm² -G. After the reaction was completed, the unreacted monomer was recovered, the slurry was discharged, and the inner walls of the polymerization tank were rinsed with water.

Thereafter, the weight of the polymer adhering to the inner wall of the polymerization vessel was measured and found to be 3.7 g/m ^2. The slurry was dewatered and dried to obtain a product, and its physical properties were measured according to the test methods described below.

The results are shown in Table 4.

Comparative Example 4 The polymerization was carried out in the same manner as in Example 8, except that the coating liquid was not applied.

As is clear from the results shown in Table 4, the amount of polymer deposited was extremely large at 45 g/m ² .

Comparative Example 5 The polymerization was carried out in the same manner as in Example 8, except that the coating liquid obtained in Production Example 12 used in Example 8 was replaced with the coating liquid obtained in Production Example 10.

As is clear from the results shown in Table 4, the polymer deposition amount was 12.7 g/m ² , which is better than Comparative Example 4, but is not practical.

Comparative Example 6 The polymerization was carried out in the same manner as in Example 8, except that the coating liquid obtained in Production Example 12 was replaced with the coating liquid obtained in Production Example 11.

As is clear from the results shown in Table 4, the polymer deposition amount was 14.3 g/m ² , which is better than Comparative Example 4, but is not practical.

Examples 9 and 10 The coating liquid obtained in Production Example 12 used in Example 8 was replaced with the coating liquids obtained in Production Examples 13 and 14.

In Example 8, the first polymerization was performed after application, and in Example 9,
In Example 10, the second polymerization was carried out in the same manner as in Example 8, except that the first polymerization was applied and the second polymerization was not applied.

As is clear from the results shown in Table 4, the amount of polymer adhered was small, ranging from 1.3 to 2.5 g/ ^m² . Furthermore, any adhered polymer could be easily washed away with simple water rinsing. There was no delay in reaction time, and the physical properties of the resulting product were excellent.

Example 11 The coating liquid obtained in Production Example 12 used in Example 8 was replaced with the coating liquid obtained in Production Example 15.

In Example 11, polymerization was repeated four times in succession in the same manner as in Example 8, except that the first coating was carried out and the second, third and fourth coatings were not carried out.

As is clear from the results shown in Table 4, the amount of polymer adhered was remarkably small at 0.4 g/ ^m² . Furthermore, any adhered polymer could be easily washed away with simple water rinsing. There was no delay in reaction time, and the physical properties of the resulting product were excellent.

Preparation Example 16: In a 500 ml autoclave equipped with a thermometer and a stirrer, add 65.0 g (0.691 mol) of carbolic acid and 110.0 g (1.
038 mol), 93.6 g of water, and 4.8 g of sodium hydroxide
(0.120 mol) was charged, and the temperature was raised to 130°C over 45 minutes with stirring. The reaction was continued for 3 hours while maintaining this temperature.

After that, it was cooled down, and when the internal temperature reached 60°C, the OS
2.6 g (0.017 mol) of BP, 24.4 g (0.194 mol) of pyrogallol, and 27.5 g (0.694 mol) of 95.6% p-toluenesulfonic acid.
The temperature was gradually increased and the reaction was continued at 100°C for 2 hours.

Thereafter, the temperature was lowered and an aqueous solution of sodium hydroxide was added to stop the reaction.

The physical properties of the resulting reaction product were measured by the methods described below, and the results are shown in Table 5.

This reaction product was prepared into an aqueous solution with a coating agent concentration of 2.0% and a sodium hydroxide concentration of 0.4%, which was used as a coating liquid.

Preparation Examples 17 and 18: A 500 ml autoclave equipped with a thermometer and a stirrer was charged with 100.0 g (1.064 mol) of carbolic acid, 52.7 g of water, and 4.3 g (0.108 mol) of sodium hydroxide, and the mixture was heated to 90°C over 30 minutes with stirring. After maintaining this temperature for 10 minutes, 87.8 g (1.596 mol) of 80% acetaldehyde was uniformly charged over 45 minutes.

The reaction was continued for another 3 hours while maintaining the temperature at 90° C. After that, the mixture was cooled, and when the internal temperature reached 50° C., 4.0 g (0.027 mol) of OSBP and 26.8 g (0.21 mol) of pyrogallol were added.
3 moles), and 32.4 g of 95.6% p-toluenesulfonic acid
In Preparation Example 18, 4.0 g (0.02
7 moles), resorcinol 11.7 g (0.106 moles), and 36%
10.8 g (0.107 mol) of hydrochloric acid was added, the temperature was gradually increased, and the reaction was continued at 85°C for 4 hours.

Thereafter, the temperature was lowered and an aqueous solution of sodium hydroxide was added to stop the reaction.

The physical properties of the resulting reaction product were measured by the methods described below, and the results are shown in Table 5.

This reaction product was prepared into an aqueous solution with a coating agent concentration of 2.0% and a sodium hydroxide concentration of 0.4%, which was used as a coating liquid.

Preparation Example 19: In a three-neck flask equipped with a reflux condenser, 94.0 g (1,000
121.6 g (1.500 mol) of 37.0% formalin and 1.6 g (0.040 mol) of sodium hydroxide were charged and stirred.
The temperature was raised to 85°C over 30 minutes. The reaction was continued for 2 hours and 40 minutes while maintaining this temperature. The viscosity of the resol thus obtained was measured at 85°C using a Brookfield viscometer, and was found to be 10 cps. Residual formalin was not detected when analyzed by the sodium sulfite method. Furthermore, the weight-average molecular weight measured by gel permeation chromatography was 420.

After that, it is cooled, and when the internal temperature reaches 50°C, the OSBP is 3.8
Then, 29.0 g (0.025 mol) of pyrogallol and 29.0 g (0.230 mol) of pyrogallol were charged, and the temperature was gradually increased to 75°C, where the reaction was continued.

When the viscosity reached 1,300 cps as measured by a Brookfield viscometer, the temperature was lowered and an aqueous solution of sodium hydroxide was added to stop the reaction.

The physical properties of the reaction product obtained are shown in Table 5.

This reaction product was prepared into an aqueous solution with a coating agent concentration of 2.0% and a sodium hydroxide concentration of 0.4%, which was used as a coating liquid.

Preparation Example 20: 100.0 g (1.064 mol) of carbolic acid, 52.7 g of water, and 4.3 g (0.108 mol) of sodium hydroxide were charged into a 500 ml autoclave equipped with a thermometer and a stirrer, and the temperature was raised to 90°C over 30 minutes with stirring. After maintaining this temperature for 10 minutes, 87.8 g (1.596 mol) of 80% acetaldehyde was uniformly charged over 45 minutes.

The mixture was further reacted for 3 hours while maintaining the temperature at 90°C. After that, it was cooled, and when the internal temperature reached 70°C, 4.0 g of OSBP was added.
(0.027 moles), 26.8 g (0.213 moles) of pyrogallol, and 20.5 g (0.107 moles) of 90% artanilic acid were charged,
The temperature was gradually increased and the reaction was continued at 150°C for 4 hours.

Thereafter, the temperature was lowered and an aqueous solution of sodium hydroxide was added to stop the reaction.

The physical properties of the reaction product obtained are shown in Table 5.
This was discarded as it was low at 44.9%.

Example 12 The coating solution obtained in Production Example 16 was applied to each part that comes into contact with vinyl chloride monomer, such as the wall of a stainless steel polymerization vessel with an internal volume of 7 L and equipped with stirring blades and baffles, so that the coating agent was 0.
After spraying with a sprayer to give a coating of 5 g/m ² , the coating was rinsed with water.

Into the polymerization tank with the coating thus formed, 3,000 g of deionized water, 0.89 g of di-2-ethylhexyl peroxydicarbonate, 0.28 g of cumyl peroxyneodecanoate, and 2 g of partially saponified polyvinyl alcohol with a degree of saponification of 80% were charged, and the air inside was removed with a vacuum pump. Then, 2,000 g of vinyl chloride was charged, and the reaction was continued at 58°C until the pressure reached 6.5 kg/ ^m² -G. After the reaction was completed, the unreacted monomer was recovered, the slurry was discharged, and the walls were rinsed with water.

Next, the raw materials were charged without applying the coating liquid, and the second polymerization was carried out. Thereafter, the third, fourth, and fifth polymerizations were carried out in the same manner, and continuous polymerization was repeated five times.

Thereafter, the weight of the polymer adhering to the inner wall of the polymerization vessel was measured and found to be 0.5 g/m ^2. The slurry was dehydrated and dried to obtain a product, and its physical properties were measured by the test methods described below.

According to the method of the present invention, the amount of polymer adhered was significantly small, and the adhered polymer could be easily washed away by simple water washing. There was no delay in reaction time, and the physical properties of the obtained product were excellent.

The results are shown in Table 6.

Examples 13 and 14 The coating method, polymerization formulation, number of polymerizations, etc. were the same as in Example 12, except that the coating liquid obtained in Production Example 16 used in Example 12 was changed to the coating liquid obtained in Production Examples 17 and 18.

As is clear from the results shown in Table 6, the amount of polymer adhered was not significant, ranging from 0.4 to 0.8 g/ ^m² . Furthermore, any polymer adhered could be easily washed away with simple water rinsing. There was no delay in reaction time, and the physical properties of the resulting product were excellent.

Comparative Example 7 Only the first polymerization was carried out in the same manner as in Example 12, except that no coating liquid was applied.

As is clear from the results shown in Table 6, the amount of polymer deposited was extremely large at 45 g/m ² .

Example 15 The polymerization was carried out in the same manner as in Example 12, except that the coating liquid obtained in Production Example 16 used in Example 12 was changed to the coating liquid obtained in Production Example 19.

As is clear from the results shown in Table 6, the amount of polymer attached was 13.4 g/ ^m² , which is considerably better than that of Comparative Example 7.
Inferior to Examples 12 to 14.

Production Example 21 (Phenol/aldehyde initial condensation product) 188.0 g of phenol was placed in a three-neck flask equipped with a reflux condenser.
(2.0 mol), 237.6 g (2.93 mol) of 37.0% formalin,
3.2 g (0.08 mol) of sodium hydroxide was added and the mixture was stirred for 8 minutes.
The temperature was raised to 5°C over 30 minutes, and the reaction was continued for 2 hours and 40 minutes while maintaining this temperature.

The viscosity of the resol thus obtained was measured at 85°C using a Brookfield viscometer and was 10 cps. Residual formalin was not detected when analyzed by the sodium sulfite method. Furthermore, the weight-average molecular weight measured by gel permeation chromatography was 410.

Production Example 22 (Methanol Solution of Resol-Based Coating Agent) 200 g of the resol obtained in Production Example 1 was placed in a three-neck flask equipped with a reflux condenser, to which 6.9 g (0.046 mol) of OSBP, 12.6 g (0.092 mol) of p-aminobenzoic acid, and 29.0 g (0.23 mol) of pyrogallol were added. The mixture was heated to 75°C over 20 minutes with stirring, and the reaction was continued while maintaining this temperature. When the viscosity, measured with a Brookfield viscometer, reached 1,300 cps, the temperature was lowered, and the reaction was stopped by adding an aqueous sodium hydroxide solution.

The coating agent concentration in this reaction product was 25%, which was diluted three times with water.
The pH was adjusted to 2.0 by adding hydrochloric acid to precipitate the coating agent. The precipitate was vacuum filtered, washed with water at room temperature, dried, and then pulverized to obtain a brown powdery substance. The Mw was 1370. A portion of this brown powdery substance was taken and dissolved in methanol to obtain a coating agent concentration of 0.4.
% to prepare a coating solution.

Production Example 23 (Aqueous alkaline solution of resol-based coating agent) A portion of the brown powdery substance produced in Production Example 22 was taken and dissolved in a 0.1% aqueous sodium hydroxide solution, the minimum concentration at which it could be dissolved, so that the coating agent concentration became 0.2%.

Preparation Example 24 (Methanol Solution of Resol-Based Coating Agent) 200 g of the resol obtained in Preparation Example 21 was placed in a three-neck flask equipped with a reflux condenser, and 6.9 g (0.046 mol) of OSBP, 15.9 g (0.092 mol) of orthanilic acid, and 10.1 g (0.092 mol) of resorcinol were added thereto. The mixture was heated to 75° C. under stirring for 20 minutes.
The temperature was raised over a period of 1 minute, and the reaction was continued while maintaining this temperature. When the viscosity measured with a Brookfield viscometer reached 1,300 cps, the temperature was lowered and an aqueous solution of sodium hydroxide was added to stop the reaction.

The coating agent concentration in this reaction product was 22%, which was diluted 2.0 times with water.
The pH was adjusted to 2.0 by adding hydrochloric acid, and the coating agent was precipitated. The precipitate was vacuum filtered, washed with water at room temperature, dried, and then crushed to obtain a brown powder. The Mw was 1980. A portion of this brown powder was dissolved in methanol to obtain a coating agent concentration of 0.
The coating solution was adjusted to 4%.

Production Example 25 (Aqueous alkaline solution of resol-based coating agent) A portion of the brown powdery substance produced in Production Example 24 was taken and dissolved in a 0.1% aqueous sodium hydroxide solution, the minimum concentration in which it could be dissolved, to a coating agent concentration of 2.0%, to obtain a coating liquid.

Example 16: The coating liquid obtained in Production Example 22 was sprayed onto the wall surface of a stainless steel polymerization tank 71 and other areas that would come into contact with vinyl chloride monomer to be charged later, using a sprayer, so that the coating amount was 0.1 g/ ^m² , and then the methanol was distilled off under reduced pressure.

Into the polymerization tank in which the coating film had been formed in this way, 3,000 g of deionized water, 0.89 g of di-2-ethylhexyl peroxydicarbonate, 0.89 g of cumyl peroxyneodecanoate, and 0.
2.8 g of methyl methyl ketone and 2.0 g of partially saponified polyvinyl alcohol with a degree of saponification of 80% were charged, and the air inside was removed with a vacuum pump. Then, 2,000 g of vinyl chloride was charged, and the reaction was continued at 58°C until the pressure reached 6.5 kg/ ^cm² -G.

After the reaction was completed, the unreacted monomer was recovered, the slurry was discharged, and the inner walls of the polymerization vessel were rinsed with water. A second polymerization reaction was then carried out in the same manner, except that the coating liquid was not applied. Thereafter, the polymerization reaction was repeated 10 times in the same manner.

Thereafter, the weight of the polymer adhering to the inner wall etc. was measured and found to be 0.6 g/m ^2. After dehydration, the slurry was dried and various physical properties were measured by the test methods described below.

The amount of polymer adhering to the inner wall etc. was extremely small, and the small amount of polymer that had adhered could be easily washed away by simple washing with water.

The results of the measurements are shown in Table 7.

Example 17: The coating solution obtained in Production Example 23 was sprayed onto the wall surface of a stainless steel polymerization tank 71 and other areas that would come into contact with vinyl chloride monomer to be charged later, using a sprayer, so that the coating amount was 0.5 g/ ^m² , and the membrane was then rinsed with water.

Into the polymerization tank in which the coating film had been formed in this way, 3,000 g of deionized water, 0.89 g of di-2-ethylhexyl peroxydicarbonate, 0.89 g of cumyl peroxyneodecanoate, and 0.
2.8 g of methyl methyl ketone and 2.0 g of partially saponified polyvinyl alcohol with a degree of saponification of 80% were charged, and the air inside was removed with a vacuum pump. Then, 2,000 g of vinyl chloride was charged, and the reaction was continued at 58°C until the pressure reached 6.5 kg/ ^cm² -G.

After the reaction was completed, the unreacted monomer was recovered, the slurry was discharged, and the inner walls of the polymerization vessel were rinsed with water. A second polymerization reaction was then carried out in the same manner except that the coating liquid was not applied. Thereafter, the polymerization reaction was repeated five times in the same manner.

Thereafter, the weight of the polymer adhering to the inner wall etc. was measured and found to be 1.0 g/m ^2. After dehydration, the slurry was dried and various physical properties were measured by the test methods described below.

The amount of polymer adhering to the inner wall was extremely small, and the small amount of polymer that did adhere could be easily washed away with simple water washing. In addition, the reaction time was not extended, and the physical properties of the obtained product were excellent.

The results of the measurements are shown in Table 7.

Comparative Example 8: The coating liquid was not applied at all, and the other steps were the same as in Example 17, and only the first polymerization was carried out. As shown in Table 7, the result was that the polymer deposition amount was extremely large at 45 g/ ^m2 .

Example 18 Polymerization was carried out in the same manner as in Example 16, including the coating method, polymerization formulation, and number of polymerizations, except that the coating liquid obtained in Production Example 22 used in Example 16 was changed to the coating liquid obtained in Production Example 24.

The results are shown in Table 7. The amount of polymer attached was 0.4 g/m
The amount of polymer adhering to the surface was remarkably low at ² , and any polymer that adhered could be easily washed away with simple water rinsing. There was no delay in reaction time, and the physical properties of the resulting product were excellent.

Example 19 Polymerization was carried out in the same manner as in Example 17, including the coating method, polymerization formulation, and number of polymerizations, except that the coating liquid obtained in Production Example 23 used in Example 17 was changed to the coating liquid obtained in Production Example 25.

The results are shown in Table 7. The amount of polymer attached was 0.8 g/m
The amount of polymer adhering to the surface was remarkably low at ² , and any polymer that adhered could be easily washed away with simple water rinsing. There was no delay in reaction time, and the physical properties of the resulting product were excellent.

The present invention can be effectively applied to aqueous suspension polymerization, aqueous emulsion polymerization, and so-called bulk polymerization of the above-mentioned monomers in the absence of a polymerization medium, under the usual polymerization conditions for each.

Test Methods The tests and measurements in the above examples and comparative examples were carried out according to the following methods.

Average degree of polymerization: According to JIS.K-6721.

Apparent specific gravity: According to JIS.K-6721.

Fish eye: A sheet is made by mixing a specified amount of PVC plasticizer, heat stabilizer, etc. and kneading it at 150°C for 5 minutes.
Thereafter, the number of fish eyes present in an area of 10 cm x 10 cm was measured in the usual manner.

Porosity: Measured by mercury intrusion porosity.

────────────────────────────────────────────────────── Continued from the front page (31) Priority Number: Patent Application No. 2-227952 (32) Priority Date: August 31, 1990 (33) Priority Country: Japan (JP) (31) Priority Number: Patent Application No. 2-291870 (32) Priority Date: October 31, 1990 (33) Priority Country: Japan (JP) (31) Priority Number: Patent Application No. 2-323139 (32) Priority Date: November 28, 1990 (33) Priority Country: Japan (JP) (72) Inventor: Yasuyuki Hatakeyama 4-10-11 Kamo, Takaishi City, Osaka Prefecture (72) Inventor: Yamaguchi Akihiro 1-13-24 Zaimokuza, Kamakura City, Kanagawa Prefecture (72) Inventor: Keisaburo Yamaguchi 1627-92 Toke-cho, Chiba City, Chiba Prefecture (56) References: JP 54-107991 (JP, A) JP 55-151012 (JP, A) JP 55-160004 (JP, A) JP 56-5442 (JP, B2)

Claims (25)

[Claims] [Claim 1] A method for polymerizing vinyl chloride monomer in an aqueous medium or in bulk, comprising applying a coating liquid to the surface of a polymerization apparatus at a location where the monomer will come into contact, in order to prevent the vinyl chloride polymer produced from adhering to said surface, the method comprising applying a coating liquid whose pH is adjusted so that the coating agent in the coating liquid dissolves at the temperature at which it is applied to the surface, and precipitates when heated on the surface. Claim 2: The coating liquid contains a coating agent of 0.
% of the alkaline solution, and the pH is 0.2 to 10.0% lower than that at which the coating agent precipitates at room temperature.
2. The method of claim 1, wherein the aqueous solution is pH adjusted with an acid to a pH of 4.0 or higher. 3. The method according to claim 1, wherein the temperature of the surface is raised to 40° C. or higher during application. 4. The method according to claim 1, wherein the coating agent is a modified product of a precondensation product of a phenol and an aldehyde. [Claim 5] A method for polymerizing vinyl chloride monomer in an aqueous medium or in bulk, in which a coating liquid is applied in advance to the surface of a polymerization apparatus at the site where the monomer comes into contact, to prevent the vinyl chloride polymer produced from adhering to said surface, characterized in that the coating liquid applied to said surface contains a reaction product having a molecular weight of 500 to 100,000 obtained in advance by a condensation reaction of dihydroxybiphenyls and aldehydes in the presence of an acidic catalyst, the pH of the coating liquid being adjusted so that the reaction product dissolves at the temperature at which it is applied to the surface and precipitates when heated on the surface. 6. The reaction product has a molecular weight of 1,000 to 50,000.
The method of claim 5, wherein the range is 7. The reaction product of claim 1, wherein the reaction product has the following general formula: (wherein R is a hydrogen atom or an alkyl group, cycloalkyl group, aryl group or aralkyl group having 1 to 8 carbon atoms; X is a carboxyl group, alkyl group or cycloalkyl group; m is an integer of 0 to 2; and n is an integer of 2 to 500). 8. The dihydroxybiphenyls are 2,2'-dihydroxybiphenyl, 2,2'-dihydroxy-5,5'-
Dimethylbiphenyl, 2,2'-dihydroxy-4,4',5,
5'-Tetramethylbiphenyl, 2,2'-dihydroxy-5,
8. The method of claim 5, 6 or 7, wherein the alkyl group is selected from the group consisting of 5'-dicyclohexylbiphenyl, and 2,2'-dihydroxy-5,5'-di-tert-butylbiphenyl. [Claim 9] A method according to claim 5, 6, 7, or 8, wherein the coating liquid is a solution in which the reaction product is dissolved in an aqueous solution of an alkali metal hydroxide at a concentration of 0.1 to 10 wt %, and the pH is further adjusted to 8 to 3 with an inorganic or organic acid. [Claim 10] A method for polymerizing vinyl chloride monomer in an aqueous medium or in bulk, comprising applying a coating liquid to the surface of a polymerization apparatus at a location where the monomer will come into contact, in order to prevent the vinyl chloride polymer produced from adhering to said surface, the method comprising applying a coating liquid to said surface, the coating liquid containing a co-condensate obtained by further reacting an initial condensate of a phenol with an aldehyde with o-sec-butylphenol. 11. The co-condensation product of claim 1, wherein the precondensation product is o-
11. The method according to claim 10, wherein the sec-butylphenol is obtained by further reacting the sec-butylphenol with at least one nitrogen-containing compound and/or at least one polyhydric phenol. 12. The method according to claim 10, wherein the coating liquid is an aqueous alkaline solution of the co-condensate. 13. The method according to claim 12, wherein the concentration of said co-condensate in said alkaline aqueous solution is 0.1 to 10.0 wt % and 0.05 to 5.0 wt % of an alkali metal or alkaline earth metal hydroxide is contained. [Claim 14] The method described in claim 12, wherein the co-condensation product is a co-condensation product having a weight average molecular weight of 500 to 10,000 obtained by further reacting an initial condensation product of at least one phenol and at least one aldehyde except formaldehyde with o-sec-butylphenol and at least one polyhydric phenol in the presence of a strong acid catalyst. 15. A coating liquid to be applied to a surface of a polymerization apparatus at a location where vinyl chloride monomer comes into contact with the surface during polymerization of vinyl chloride monomer in an aqueous medium or in bulk to prevent the vinyl chloride polymer produced from adhering to the surface, the coating liquid comprising a reaction product having a molecular weight of 500 to 100,000 obtained by a condensation reaction of dihydroxybiphenyls with aldehydes in the presence of an acid catalyst, the reaction product being soluble at the temperature at which the reaction product is applied to the surface,
A coating liquid characterized in that the pH is adjusted so that the coating liquid precipitates when heated on the surface. 16. The reaction product of claim 1, wherein the reaction product has the following general formula: (wherein R is a hydrogen atom or an alkyl group, cycloalkyl group, aryl group or aralkyl group having 1 to 8 carbon atoms; X is a carboxyl group, alkyl group or cycloalkyl group; m is an integer of 0 to 2; and n is an integer of 2 to 500). 17. The dihydroxybiphenyls are 2,2'-
Dihydroxybiphenyl, 2,2'-dihydroxy-5,5'
-dimethylbiphenyl, 2,2'-dihydroxy-4,4',
5,5'-tetramethylbiphenyl, 2,2'-dihydroxy-
16. The coating liquid of claim 15, wherein the dihydroxybenzoate is selected from the group consisting of 5,5'-dicyclohexylbiphenyl and 2,2'-dihydroxy-5,5'-di-tert-butylbiphenyl. [Claim 18] A coating liquid that is applied to surfaces of a polymerization apparatus at the site where the monomer comes into contact when polymerizing vinyl chloride monomer in an aqueous medium or in bulk to prevent the vinyl chloride polymer produced from adhering to the surfaces, the coating liquid being characterized by containing a co-condensate obtained by further reacting an initial condensate of a phenol and an aldehyde with o-sec-butylphenol. [Claim 19] A coating liquid described in claim 18, wherein the reaction product is a co-condensation product having a weight average molecular weight of 500 to 10,000 obtained by further reacting an initial condensation product of at least one phenol and at least one aldehyde excluding formaldehyde with o-sec-butylphenol and at least one polyhydric phenol in the presence of a strong acid catalyst. [Claim 20] A method for producing a coating liquid to be applied to the surface of a polymerization apparatus at a location where the monomer comes into contact when vinyl chloride monomer is polymerized in an aqueous medium or in bulk, to prevent the vinyl chloride polymer produced from adhering to said surface, the method comprising the steps of: modifying with a modifying agent an initial condensate obtained by condensing at least one phenol and at least one aldehyde in the presence of a basic catalyst to produce a coating agent; diluting the resulting alkaline liquid with water to a desired concentration of the coating agent; adding an acid to the diluted liquid to adjust its pH, thereby precipitating the coating agent; and separating the precipitated coating agent and dissolving it in an organic solvent or an alkaline liquid. 21. The method according to claim 20, wherein the alkaline aqueous solution is diluted with water so that the concentration of the coating agent therein is in the range of 3 to 20 wt %. 22. The method according to claim 20 or 21, wherein the pH after pH adjustment with an acid is in the range of 1.0 to 5.0. 23. The method of claim 20, 21 or 2, wherein the separation of the coating agent is carried out by filtering the coating agent precipitated by adjusting the pH, washing it with water, drying it, and pulverizing it.
2. The method described in 2. 24. The coating agent according to claim 23, wherein the coating agent is 0.03 to 3.0 wt.
23. The method of claim 20, 21 or 22, wherein the compound is dissolved in an organic solvent at a concentration in the range of 0.5 to 100%. 25. The coating agent according to claim 24, wherein the coating agent is present in an amount of 0.1 to 8.0 wt.%.
Claim 20, 2 is dissolved in an alkaline aqueous solution at a concentration in the range of
24. The method according to claim 1, 22 or 23.