JP2008248167A - Scale adhesion inhibitor - Google Patents

Abstract

（Ｒ^１は水素原子または置換基を有していてもよい炭素数８以下の炭化水素基を、Ｒ^２は酸素を含有する置換基を有していてもよい炭素数１〜４０のアルコキシル基またはアシロキシル基を、ｎは０〜２の整数をし、ｍは０〜３の整数を、Ｘは１価の金属原子を表す。ただしｎとｍの合計は３以下である。）
【選択図】なし[Problem] To provide a scale adhesion preventive agent that has excellent wettability to the inner wall of a polymerization vessel and exhibits an excellent anti-scale adhesion effect during polymerization of a vinyl monomer.
A vinyl alcohol polymer (component A), a hydroxyl group-containing aromatic compound (component B), and an ethylene oxide-based polymer having a silyl group content of 0.1 to 10 mol% represented by general formula (1) An alkaline aqueous solution having a pH of 9 or more, containing a nonionic surfactant (component C).

(R ¹ is a hydrogen atom or a hydrocarbon group having 8 or less carbon atoms which may have a substituent, and R ² is an alkoxyl group having 1 to 40 carbon atoms which may have a substituent containing oxygen. Or n represents an acyloxyl group, n represents an integer of 0 to 2, m represents an integer of 0 to 3, and X represents a monovalent metal atom, provided that the sum of n and m is 3 or less.
[Selection figure] None

Description

  The present invention relates to a scale adhesion preventing agent. More specifically, it has excellent wettability to the inner wall of the polymerization reactor, can form a uniform scale adhesion preventive film, and exhibits excellent scale adhesion prevention effects when polymerizing vinyl monomers. It relates to an inhibitor.

  When a vinyl monomer such as vinyl chloride is polymerized alone in an aqueous medium or copolymerized with another copolymerizable monomer to produce a vinyl polymer, the inside of the polymerization reactor or There was a problem that the scale adhered to the stirring blade and the like, and the adhered scale caused a decrease in productivity and the quality of the obtained polymer. In particular, the higher the polymerization temperature, the more easily the scale adheres, which is a problem in production depending on the physical properties of the target vinyl polymer. In order to solve this problem, it has been proposed to apply various scale adhesion preventing agents in advance in the polymerization reactor.

Japanese Unexamined Patent Publication (Kokai) No. 62-201832 (Patent Document 1) discloses, for example, phenols / aldehyde condensates as scale adhesion preventing agents.
In JP-A-54-7487 (Patent Document 2), a coating solution comprising an alkali metal hydroxide solution containing a self-condensate of polyfunctional phenols is applied, and the polymer on the inner surface of the polymerization reaction vessel is applied. A method for preventing adhesion is disclosed.
Japanese Patent Application Laid-Open No. 55-36288 (Patent Document 3) discloses a water vapor stream for applying a scale adhesion inhibitor for the purpose of shortening the time required to apply the scale adhesion inhibitor to the inside of the polymerization reactor. A method of using is proposed.
Japanese Patent Application Laid-Open No. 59-184208 (Patent Document 4) discloses silanol-modified polyvinyl alcohol that is soluble in an alkaline aqueous solution as a scale adhesion inhibitor.
Japanese Patent Application Laid-Open No. 57-164107 (Patent Document 5) discloses an aqueous suspension polymerization method of vinyl chloride in which a deposition-inhibiting coating layer composed of a 1-naphthol / formaldehyde condensate is adhered to the inner surface of a polymerization reactor. ing.
Japanese Patent Application Laid-Open No. 60-20909 (Patent Document 6) discloses a polymerization method in which a mixture of a water-soluble dye, a sodium alkylsulfate anionic surfactant, and a water-soluble polymer substance in an aqueous solution is applied.
In WO2005 / 087815 (Patent Document 7), scale adhesion prevention comprising a vinyl alcohol polymer containing a silyl group and a hydroxyl group-containing aromatic compound in the molecule, and comprising an alkaline aqueous solution having a pH of 9 or more. Agents are disclosed.
Japanese Patent Application Laid-Open No. 2005-220348 (Patent Document 8) discloses a scale adhesion preventing agent comprising an aqueous solution containing a vinyl alcohol polymer containing a specific silyl group.

  However, since the conventionally known scale adhesion preventing agents have poor wettability when applied to the inner wall of the polymerization reactor, a uniform scale adhesion preventing film is not formed, and the scale adhesion preventing effect is not always sufficient. There wasn't. In particular, in the production of a vinyl polymer that requires a reaction at a higher temperature, it is desired to develop a scale adhesive having a large effect.

Prior art documents related to the present invention include the following.
JP-A-62-201832 JP-A-54-7487 JP 55-36288 A JP 59-184208 A JP 57-164107 A Japanese Patent Application Laid-Open No. 60-20909 WO2005 / 087815 JP 2005-220348 A

  An object of the present invention is to provide a scale adhesion preventing agent that is excellent in wettability to the inner wall of a polymerization reactor and exhibits an excellent scale adhesion preventing effect during polymerization of a vinyl monomer.

  As a result of intensive studies, the present inventors have found that a vinyl alcohol polymer (component A) having a silyl group content of 0.1 to 10 mol% represented by the following general formula (1), a hydroxyl group-containing aromatic To find out that an alkaline aqueous solution having a pH of 9 or more containing a compound (component B) and an ethylene oxide nonionic surfactant (component C) exerts an excellent effect as a scale adhesion preventing agent, and completes the present invention. It came.

（Ｒ^１は水素原子または置換基を有していてもよい炭素数８以下の炭化水素基を表し、Ｒ^２は酸素を含有する置換基を有していてもよい炭素数１〜４０のアルコキシル基またはアシロキシル基を表し、ｎは０〜２の整数を表わし、ｍは０〜３の整数を表し、Ｘは１価の金属原子を表す。ただしｎとｍの合計は３以下である。）

(R ¹ represents a hydrogen atom or a hydrocarbon group having 8 or less carbon atoms which may have a substituent, and R ² represents an alkoxyl having 1 to 40 carbon atoms which may have a substituent containing oxygen. A group or an acyloxyl group, n represents an integer of 0 to 2, m represents an integer of 0 to 3, and X represents a monovalent metal atom, provided that the sum of n and m is 3 or less.)

  Since the scale adhesion preventive agent of the present invention is excellent in wettability, a vinyl monomer is polymerized alone in an aqueous medium or copolymerized with other copolymer components to produce a vinyl polymer. , By coating the inside of the polymerization reactor in advance, an extremely uniform film is formed on the inner wall of the polymerization reactor, and the action of this film suppresses the scale attached to the inner wall of the polymerization reactor to an extremely small amount. Can do. Moreover, since the scale adhesion preventing agent of the present invention is soluble in an aqueous medium, it can be applied to the inside of the polymerization reactor in a short time using a water vapor stream.

Hereinafter, the present invention will be described in detail.
A vinyl alcohol polymer (hereinafter referred to as silyl group-containing PVA) having a silyl group content of 0.1 to 10 mol%, which is used in the present invention, represented by the above general formula (1), The degree of polymerization of the unmodified vinyl alcohol polymer may be abbreviated as PVA) is not particularly limited, but is usually 100 to 8000, preferably 150 to 6000, more preferably 200 to 5000. is there. Here, the degree of polymerization of the silyl group-containing PVA is measured according to JIS K6726. That is, it can be determined from the intrinsic viscosity measured in water at 30 ° C. after saponification and purification of the silyl group-containing PVA.
When the degree of polymerization of the silyl group-containing PVA is less than 100, the strength of the coating film formed on the inner wall of the polymerization reactor may decrease. When the degree of polymerization is larger than 8000, the viscosity of the alkaline aqueous solution becomes too high, and the stability may be lowered.

  The degree of saponification of the silyl group-containing PVA is not particularly limited, but is usually 80 to 99.99 mol%, preferably 85 to 99.95 mol%, more preferably 90 to 99.9 mol%. . Here, the saponification degree of the silyl group-containing PVA is measured according to JIS K6726. If the saponification degree of the silyl group-containing PVA is less than 80 mol%, the water resistance of the coating formed on the inner wall of the polymerization reactor may be lowered. Also, silyl group-containing PVA having a saponification degree exceeding 99.99 mol% is difficult to produce industrially.

PVA can be produced by saponifying a vinyl ester polymer. Examples of vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl valelate, vinyl caproate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate, vinyl versatate, etc. be able to. Particularly preferred is vinyl acetate.
As a polymerization method of the vinyl ester monomer, a known polymerization method such as a solution polymerization method, a bulk polymerization method, a suspension polymerization method, or an emulsion polymerization method is used. Usually, a solution weight using an alcohol such as methanol as a solvent is used. Legal is used. Although there is no restriction | limiting in particular about superposition | polymerization temperature, Usually, it arbitrarily selects in 0 to 150 degreeC.
Various known methods can be used as a method for saponifying a vinyl ester polymer. Usually, sodium alcoholate, sodium hydroxide, potassium hydroxide, etc. in an alcohol solvent (which may contain a small amount of water) A method of saponification using an alkaline substance is used.

  The silyl group-containing PVA (component A) used in the present invention contains the silyl group represented by the general formula (1) in an amount of 0.1 to 10 mol%. The content of the silyl group is preferably 0.2 to 8 mol%, more preferably 0.3 to 6 mol%, and particularly preferably 0.5 to 5 mol%. When the content of the silyl group is less than 0.1 mol%, the scale adhesion preventing effect is lowered, which is not preferable. When the amount is more than 10 mol%, the viscosity of the alkaline aqueous solution is remarkably increased, and the handleability is lowered.

  The silyl group represented by the general formula (1) is directly bonded to the side chain or terminal of PVA, or is connected to the side chain or terminal of PVA through a linking group that is not cleaved during saponification of the vinyl ester polymer. Are connected.

  A method for introducing a silyl group into PVA is obtained by copolymerizing a vinyl ester monomer and an olefinically unsaturated monomer having a silyl group or a group capable of generating a silyl group. The method of saponifying a copolymer is mentioned. In the general formula (1) representing the silyl group, the -OX group is introduced when the copolymer is saponified, and X represents a monovalent metal atom such as sodium or potassium.

  Specific examples of such olefinically unsaturated monomers include, for example, vinyltrimethoxysilane, vinyltris- (β-methoxyethoxy) silane, allyltrimethoxysilane, vinyltriacetoxysilane, allyltriacetoxysilane, vinylmethyldimethoxy. Silane, vinyldimethylmethoxysilane, vinylmethyldiethoxysilane, vinyldimethylethoxysilane, vinylmethyldiacetoxysilane, vinyldimethylacetoxysilane, vinylisobutyldimethoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinyltrihexyloxysilane , Vinylmethoxydihexyloxysilane, vinyldimethoxyoctyloxysilane, vinylmethoxydioctyloxysilane, vinyltrioctyloxysilane, vinylmeth Sidilauryloxysilane, vinyldimethoxylauryloxysilane, vinylmethoxydioleoyloxysilane, vinyldimethoxyoleyloxysilane, 3- (meth) acrylamide-propyltrimethoxysilane, 3- (meth) acrylamide-propyltriethoxysilane, 3- (Meth) acrylamide-propyltri (β-methoxyethoxy) silane, 2- (meth) acrylamide-2-methylpropyltrimethoxysilane, 2- (meth) acrylamide-2-methylethyltrimethoxysilane, N- (2- (Meth) acrylamide-ethyl) -aminopropyltrimethoxysilane, 3- (meth) acrylamide-propyltriacetoxysilane, 2- (meth) acrylamide-ethyltrimethoxysilane, 1- (meth) acrylamide-me Rutrimethoxysilane, 3- (meth) acrylamide-propylmethyldimethoxysilane, 3- (meth) acrylamide-propyldimethylmethoxysilane, 3- (N-methyl- (meth) acrylamide) -propyltrimethoxysilane, 3-(( (Meth) acrylamide-methoxy) -3-hydroxypropyltrimethoxysilane, 3-((meth) acrylamide-methoxy) -propyltrimethoxysilane, dimethyl-3- (meth) acrylamide-propyl-3- (trimethoxysilyl)- Examples thereof include, but are not limited to, propylammonium chloride and dimethyl-2- (meth) acrylamide-2-methylpropyl-3- (trimethoxysilyl) -propylammonium chloride.

  As another method for introducing a silyl group into PVA, a vinyl ester monomer is polymerized in the presence of a compound containing an epoxy group such as allyl glycidyl ether or butadiene monoxide, and the resulting vinyl containing an epoxy group is obtained. A method of reacting the ester copolymer with a compound having a mercapto group and a silyl group in the molecule, such as trimethoxysilylmethyl mercaptan, and then saponifying it can be mentioned. In addition, a vinyl ester monomer is polymerized using a compound having a mercapto group and a silyl group in the molecule, for example, trimethoxysilylmethyl mercaptan as a chain transfer agent, and the resulting vinyl ester polymer is saponified. Although the method of manufacturing PVA which has a silyl group by the terminal is also mentioned by this, it is not limited to these methods.

  In the present invention, a copolymerizable monomer may be copolymerized when the vinyl ester monomer is polymerized as long as the gist of the present invention is not impaired. Examples of such monomers include α-olefins such as ethylene, propylene, 1-butene and isobutene; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, fumaric acid, maleic acid and itaconic acid, or these Or mono- or dialkyl esters having 1 to 18 carbon atoms; acrylamide, N-alkyl acrylamide having 1 to 18 carbon atoms, N, N-dimethylacrylamide, diacetone acrylamide, 2-acrylamidopropanesulfonic acid or a salt thereof, acrylamide Acrylamides such as propyldimethylamine or acid salts thereof or quaternary salts thereof; methacrylamide, N-alkyl methacrylamide having 1 to 18 carbon atoms, N, N-dimethylmethacrylamide, 2-methacrylamide propanesulfonic acid or salts thereof , Me Methacrylamide such as chloramidopropyldimethylamine or its acid salt or quaternary salt thereof; N-vinylamides such as N-vinylpyrrolidone, N-vinylformamide and N-vinylacetamide; cyanation such as acrylonitrile and methacrylonitrile Vinyls: vinyl ethers such as alkyl vinyl ethers having 1 to 18 carbon atoms, hydroxyalkyl vinyl ethers, alkoxyalkyl vinyl ethers; polys such as polyethylene glycol allyl ether, methoxy polyethylene glycol allyl ether, polypropylene glycol allyl ether, polyethylene glycol-polypropylene glycol allyl ether (Oxyalkylene) group-containing allyl ether; vinyl chloride, vinylidene chloride, vinyl fluoride, vinyl fluoride Examples of the halogenated vinyls such as nilidene and vinyl bromide include, but are not limited to, allyl acetate, allyl chloride, allyl alcohol, dimethylallyl alcohol, and the like. The amount of these monomers to be used is not particularly limited as long as the resulting silyl group-containing PVA is dissolved in an alkaline aqueous solution having a pH of 9 or more, but is usually a ratio based on all the units used for copolymerization. And preferably 10 mol% or less.

  In the present invention, the silyl group-containing PVA can also be polymerized using a thiol compound such as thiol acetic acid, mercaptopropionic acid, or an alkyl mercaptan having 18 or less carbon atoms as a chain transfer agent.

  In the present invention, the silyl group-containing PVA can be used alone or in combination of two or more.

The hydroxyl group-containing aromatic compound (component B) used in the present invention is a compound in which a hydroxyl group is directly bonded to an aromatic compound. As the hydroxyl group-containing aromatic compound, those which are soluble in an alkaline aqueous solution having a pH of 9 or more are used. Specific examples thereof include phenol, cresol, butylphenol, resorcin, catechol, xylylenol, pyrogallol, naphthol, dihydroxynaphthalene, anthrol, Examples include hydroxybiphenyl, quercetin, alizarin, and antioxidants classified into phenolic groups. In the present invention, a hydroxyl group-containing aromatic compound that can be particularly preferably used is naphthol.
The hydroxyl group-containing aromatic compounds can be used alone or in combination of two or more.

  Examples of the ethylene oxide nonionic surfactant (component C) used in the present invention include polyoxyethylene (hereinafter abbreviated as POE) sorbitan monooleate, POE sorbitan monostearate, POE sorbitan tetraoleate and the like. Sorbitan fatty acid esters; POE sorbite fatty acid esters such as POE sorbite monolaurate, POE sorbite monooleate, POE sorbite pentaoleate, POE sorbite monostearate; POE glycerin monostearate, POE glycerin monoisostearate, POE POE glycerin fatty acid esters such as glycerin triisostearate; POE monooleate, POE distearate, POE dioleate, ethylene glycol distearate POE fatty acid esters: POE lauryl ether, POE oleyl ether, POE stearyl ether, POE behenyl ether, POE-2-octyldodecyl ether, POE cholestanol ether, and other POE alkyl ethers; POE octyl phenyl ether, POE nonyl phenyl ether POE alkylphenyl ethers such as POE dinonyl phenyl ether; POE / polyoxypropylene (hereinafter abbreviated as POP) cetyl ether, POE / POP-decyltetradecyl ether, POE / POP monobutyl ether, POE / POP hydrogenated Lanolin, POE / POP alkyl ethers such as POE / POP glycerol ether; tetra-POE / tetra-POP ethylenediamine condensates such as Tetronic; OE castor oil, POE hydrogenated castor oil, POE hydrogenated castor oil monoisostearate, POE hydrogenated castor oil triisostearate, POE hydrogenated castor oil monopyroglutamic acid monoisostearic acid diester, POE hydrogenated castor oil maleic acid, etc. Oil derivatives; POE beeswax lanolin derivatives such as POE sorbite beeswax; Alkanolamides such as coconut oil fatty acid diethanolamide, lauric acid monoethanolamide, fatty acid isopropanolamide; POE laurylamine, POE stearylamine, POE alkyl (tallow) amine, POE POE alkylamines such as dioleylamine; POE propylene glycol fatty acid ester, POE fatty acid amide, sucrose fatty acid ester, POE nonylphenylformaldehyde Compound, alkylethoxydimethylamine oxide, trioleyl phosphate; 2,5,8,11-tetramethyl-6-dodecyne-5,8-diol, 5,8-dimethyl-6-dodecyne-5,8-diol 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 4,7-dimethyl-5-decyne-4,7-diol, 2,3,6,7-tetramethyl-4 -Ethylene oxide adducts of acetylene glycols such as octyne-3,6-diol, 3,6-dimethyl-4-octyne-3,6-diol, 2,5-dimethyl-3-hexyne-2,5-diol Etc. Among these, at least one ethylene oxide nonionic surfactant represented by the following general formula (2), (3) or (4) is preferable.

（Ｒ^１は水素原子または置換基を有していてもよい炭素数１８以下の炭化水素基を表し、ｎは１〜３０の整数を表わす。）

(R ¹ represents a hydrogen atom or an optionally substituted hydrocarbon group having 18 or less carbon atoms, and n represents an integer of 1 to 30.)

（Ｒ^１は水素原子または置換基を有していてもよい炭素数１８以下の炭化水素基を表し、ｘは１〜３０の整数を表わし、ｙは１〜３０の整数を表す。）

(R ¹ represents a hydrogen atom or an optionally substituted hydrocarbon group having 18 or less carbon atoms, x represents an integer of 1 to 30, and y represents an integer of 1 to 30.)

（ｍ＋ｎは１〜３５の整数を表す。）
なお、これらの非イオン型界面活性剤は単独で、または２種類以上を組合せて用いることができる。

(M + n represents an integer of 1 to 35.)
These nonionic surfactants can be used alone or in combination of two or more.

  The scale adhesion preventive agent of the present invention is prepared by mixing a silyl group-containing PVA (A) with a hydroxyl group-containing aromatic compound (B) and an ethylene oxide nonionic surfactant (C) to form an alkaline aqueous solution having a pH of 9 or more. It can be adjusted by dissolving.

  An alkaline aqueous solution having a pH of 9 or more can be prepared by using an aqueous solution of a basic substance such as sodium hydroxide, potassium hydroxide, ammonia, or ammonium hydroxide. The alkaline aqueous solution may contain an organic solvent (for example, methanol, dioxane, etc.) mixed with water at an arbitrary ratio. When using an organic solvent, it is preferable that the usage-amount is less than 50% by the volume with respect to the whole alkaline aqueous solution.

  In the scale adhesion preventing agent of the present invention, although there is no particular limitation on the use ratio of the silyl group-containing PVA (A) and the hydroxyl group-containing aromatic compound (B), the weight ratio (A / B) is 1/99 to 99 /. A range of 1 is preferable, and a range of 1/9 to 9/1 is more preferable. When the weight ratio (A / B) between the silyl group-containing PVA (A) and the hydroxyl group-containing aromatic compound (B) is less than 1/99, a good film may not be formed on the inner wall of the polymerization reactor. When the weight ratio (A / B) between the silyl group-containing PVA (A) and the hydroxyl group-containing aromatic compound (B) is greater than 99/1, a sufficient scale adhesion preventing effect may not be exhibited. The concentration of the silyl group-containing PVA and the hydroxyl group-containing aromatic compound in the alkaline aqueous solution is not particularly limited. However, when spraying using a water vapor stream to apply the scale adhesion inhibitor to the inside of the polymerization vessel, 0.01 to A range of 20% by weight is preferred.

  In the scale adhesion preventing agent of the present invention, the content of the ethylene oxide nonionic surfactant (C) is preferably 0.001 to 10% by weight, more preferably 0.005 to 8% by weight. Particularly preferred is 0.01 to 5% by weight. When the content of the ethylene oxide nonionic surfactant (C) is less than 0.001% by weight, it is difficult to obtain the effect of increasing the wettability to the inner wall of the polymerization reactor. Since the wettability to the inner wall of the reactor becomes too high, the scale adhesion preventing agent does not adhere to the wall surface and flows down, which is not preferable.

  The scale adhesion preventing agent of the present invention can be used in combination with any additive as necessary, as long as the scale adhesion preventing effect is not hindered. Examples of such additives include water-soluble polymer compounds such as polyvinyl alcohol, partially saponified polyvinyl alcohol, methylcellulose, and sodium polyacrylate; anionic surfactants such as sodium dodecyl sulfate; and water dispersibility such as silica sol and alumina sol. Solid, sodium carbonate, sodium silicate, sodium ascorbate, sodium citrate, sodium hydrogen sulfite, sodium dithionite, sodium pyrophosphate, sodium hydrogen phosphate, potassium acetate and other water-soluble alkali metal salts; sodium hydrosulfite And the like.

  The scale adhesion preventing agent of the present invention is used when a vinyl monomer such as vinyl chloride is polymerized alone in an aqueous medium or when it is copolymerized with other copolymer components to produce a vinyl polymer. be able to. The polymerization of vinyl chloride for the purpose of producing a vinyl chloride polymer is usually performed in a temperature range of 40 to 80 ° C. using a polymerization initiator such as a peroxide compound or an azo compound with stirring in an aqueous medium. However, when ordinary PVA is used as an anti-scale adhesion agent, the coating formed on the inner wall of the polymerization reactor is not uniform, and scale adhesion occurs on the uncoated surface. In that respect, since the scale adhesion preventing agent of the present invention has improved wettability to the inner wall of the polymerization reactor, a uniform film is formed on the inner wall of the polymerization reactor, and an excellent anti-scale adhesion effect is exhibited. .

  Moreover, the application | coating method to the polymerization tank inner wall of the scale adhesion inhibitor of this invention is not specifically limited, Well-known methods, such as brush coating, dip coating, and spray coating, are used.

The amount of the scale adhesion inhibitor of the present invention applied to the inner wall of the polymerization tank is not particularly limited, but is preferably 0.001 to 5 g / m ³ in terms of the weight of the vinyl alcohol polymer. Moreover, it is preferable that the polymerization tank in which the scale adhesion inhibitor of the present invention is applied to the inner wall is subjected to a drying treatment before being subjected to polymerization. The drying method is not particularly limited, and examples thereof include a method of circulating hot air and a method of heating the polymerization tank with a jacket or the like. From the viewpoint of obtaining a uniform coating film, a method of heating the polymerization tank with a jacket or the like. Is preferred. Moreover, although a drying temperature is not specifically limited, From a viewpoint of obtaining the coating film which has the outstanding intensity | strength, it is preferable that the minimum of drying temperature is 40 degreeC or more, and it is more preferable that it is 50 degreeC or more. Further, from the viewpoint of suppressing coloring of the scale adhesion preventing agent and reducing the adverse effect on the hue of the polymer polymerized in the polymerization tank, the upper limit of the drying temperature is preferably 100 ° C. or less, and 90 ° C. or less. It is more preferable. Since the scale adhesion preventing agent of the present invention is excellent in film-forming properties, it is possible to form a coating film at a drying temperature lower than that of conventional products, and the significance of the present invention is significant from this viewpoint.

  Also, the drying time is not particularly limited and can be arbitrarily selected according to the size of the polymerization tank, the coating amount of the scale adhering agent, the concentration of the scale adhering agent, the drying temperature, etc., preferably 1 minute to 1 hour. More preferably, it is 1 minute to 30 minutes. By shortening the drying time, work efficiency can be increased, coloring of the scale adhesion inhibitor can be suppressed, and adverse effects on the hue of the polymer polymerized in the polymerization tank can be reduced.

  The scale adhesion preventing agent of the present invention can be used for production of a polymer by suspension polymerization, emulsion polymerization, solution polymerization, bulk polymerization, gas phase polymerization and the like. Monomers used include vinyl halides such as vinyl chloride; vinyl esters such as vinyl acetate and vinyl propionate; acrylic acid, methacrylic acid, and esters and salts thereof; maleic acid, fumaric acid, and esters and anhydrides thereof. Styrene, acrylonitrile, vinylidene chloride, vinyl ether, etc. are exemplified, and particularly suitable for a production method in which vinyl chloride alone or vinyl chloride and a monomer copolymerizable with vinyl chloride are subjected to suspension polymerization in an aqueous medium. used.

  Monomers copolymerizable with vinyl chloride include vinyl esters such as vinyl acetate and vinyl propionate; (meth) acrylic esters such as methyl (meth) acrylate and ethyl (meth) acrylate; α such as ethylene and propylene -Olefin; Unsaturated dicarboxylic acids such as maleic anhydride and itaconic acid; acrylonitrile, styrene, vinylidene chloride, vinyl ether and the like.

  Polymerization initiators used for (co) polymerization of vinyl chloride include organic peroxides such as isopropyl peroxydicarbonate, lauroyl peroxide, tertiary butyl peroxypivalate, benzoyl peroxide, and potassium persulfate. Known compounds such as inorganic peroxides and azo compounds such as azobisisobutyronitrile are listed. In addition, a redox polymerization initiator in which a peroxide and a reducing agent are combined can also be used.

  When carrying out suspension polymerization, a dispersion stabilizer or a dispersion stabilizing aid can usually be used. Examples of the dispersion stabilizer include cellulose derivatives such as methylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose, Examples thereof include water-soluble polymers such as gelatin, polyvinyl alcohol and polyvinyl pyrrolidone. Among them, polyvinyl alcohol having a saponification degree of 65 to 90 mol%, preferably 68 to 89 mol% and a polymerization degree of 600 to 3500 is preferably used. As the dispersion stabilizing aid, partially saponified polyvinyl alcohol having a saponification degree of less than 65 mol%, a polymerization degree of 100 to 600, and a saponification degree of 30 to 60 mol% and a polymerization degree of 120 to 580 is preferably used. When the dispersion stabilizer is used in combination, the weight ratio of the dispersion stabilizer to the dispersion stabilizer added (dispersion stabilizer / dispersion stabilizer) varies depending on the type of dispersion stabilizer used, and so on. However, the range of 95/5 to 20/80 is preferable, and 90/19 to 30/70 is particularly preferable. The dispersion stabilizer and the dispersion stabilizer aid may be charged all at the beginning of the polymerization, or may be charged separately during the polymerization.

  In suspension polymerization, various other additives can be added to the polymerization system as necessary. Examples of the additives include polymerization regulators such as aldehydes, halogenated hydrocarbons and mercaptans, and polymerization inhibitors such as phenol compounds, sulfur compounds and N-oxide compounds. Further, it is optional to add a pH adjuster, a crosslinking agent, etc., and a plurality of the above additives may be used in combination.

  In the suspension polymerization, the temperature of the aqueous medium is not particularly limited, and not only cold water of about 20 ° C. but also hot water of 90 ° C. or more is preferably used. This aqueous medium can be composed of an aqueous medium containing pure water, an aqueous solution containing various additive components, or other organic solvents. When the aqueous medium is charged into the polymerization reaction system, the supply amount may be an amount that can sufficiently heat the polymerization reaction system. In order to increase the heat removal efficiency, a polymerizer with a reflux condenser is also preferably used. The polymerization temperature in suspension polymerization is usually 40 to 90 ° C. The polymerization temperature not only affects the reaction rate, but may also affect physical properties such as the degree of polymerization of a polymer such as vinyl chloride resin. In general, the higher the polymerization temperature, the greater the amount of scale attached to the inner wall of the polymerization reactor.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited at all by these Examples.
In the following examples and comparative examples, the scale adhesion prevention property was evaluated by the following method.

[Application inside polymerization tank]
A stainless steel 20 L autoclave inner wall surface was spray-coated with an aqueous scale inhibitor solution, dried at a jacket temperature of 60 ° C. for 5 minutes, and then thoroughly washed with water. It apply | coated so that the application quantity might be set to 0.3 g / m < ² > as solid content.

[Suspension polymerization of vinyl chloride]
Polyvinyl alcohol (PVA-420H manufactured by Kuraray Co., Ltd .: polymerization degree 2000, saponification degree 80 mol%) was dissolved in deionized water in an amount corresponding to 1000 ppm with respect to the vinyl chloride monomer to prepare a dispersion stabilizer. The dispersion stabilizer thus obtained was charged into a stainless steel autoclave coated with a scale adhesion inhibitor. Next, 0.015 part of t-butylperoxyneodecanate and 0.02 part of t-hexylperoxypivalate were charged, and the oxygen was removed by deaeration until the pressure in the autoclave reached 0.0067 MPa. Thereafter, 100 parts of vinyl chloride was charged, and the content in the autoclave was heated to 67.2 ° C. and polymerization was started with stirring. The pressure in the autoclave at the start of polymerization was 11.1 MPa. When the pressure in the autoclave reaches 0.7 MPa after 4 hours from the start of the polymerization, the polymerization is stopped, the unreacted vinyl chloride monomer is purged, the polymer slurry is taken out, and the inner wall is lightened. Washed with water. Thereafter, drying was performed at 65 ° C. for 16 hours to obtain vinyl chloride polymer particles.

[Evaluation of scale adhesion]
After the polymer slurry was taken out of the polymerization tank, the state of scale adhesion in the polymerization tank was visually observed and evaluated according to the following criteria.
A: There is no adhesion of a polymer scale.
B: There is almost no polymer scale on the inner wall of the polymerization vessel.
C: A polymer scale can be confirmed on the inner wall of the polymerization vessel.
D: The polymer scale is extremely large on the inner wall of the polymerization vessel.

For the vinyl chloride polymer particles obtained by polymerization of vinyl chloride, the particle size distribution and the plasticizer absorption (CPA) were measured according to the following method.
(1) Particle Size Distribution of Vinyl Chloride Polymer Particles The ratio of JIS standard sieve 42 mesh on was expressed in weight%. The smaller the number, the smaller the coarse particles, the sharper the particle size distribution, and the better the polymerization stability.
(2) Plasticizer Absorption Amount of Vinyl Chloride Polymer Particles The absorption amount of dioctyl phthalate at 23 ° C. was measured according to the method described in ASTM-D3367-75.

[Evaluation of wettability of scale adhesion inhibitor aqueous solution]
A 15 cm x 20 cm SUS-316L test plate is brushed with a scale inhibitor solution so that the coating amount is 0.3 g / m ² as a solid content, and the wettability to the SUS-316L plate is visually observed. And evaluated according to the following criteria.
A: The solution is uniformly wet B: The solution is almost uniformly wet C: The solution is partially shrunk and there is a part that is not wet D: The solution is shrunk and is almost not wet

Synthesis Example 1 Synthesis of Silyl Group-Containing PVA (A1) A separable flask having a 3 L internal volume equipped with a stirrer, a temperature sensor, a dropping funnel and a reflux condenser was charged with 2400 g of vinyl acetate, 600 g of methanol, and 29. 0 g was charged and the inside of the system was purged with nitrogen under stirring, and then the internal temperature was raised to 60 ° C. To this system, 0.8 g of 2,2′-azobisisobutyronitrile was added to initiate the polymerization reaction. The polymerization reaction was carried out for 4 hours while adding 110 g of methanol containing 1% by weight of vinyltrimethoxysilane to the system from the start of the polymerization, and the polymerization reaction was stopped at that time. The solid content concentration in the system when the polymerization reaction was stopped was 20.1%. Next, methanol vapor was introduced into the system to drive off unreacted vinyl acetate monomer, thereby obtaining a methanol solution containing 40% vinyl ester polymer.
The molar ratio of sodium hydroxide to vinyl acetate units in the vinyl ester polymer is 0.02 with respect to a methanol solution containing 40% of the vinyl ester polymer, and the solid content concentration of the vinyl ester polymer is 20% by weight. %, Methanol and a methanol solution containing 10% by weight of sodium hydroxide were added in this order under stirring, and the saponification reaction was started at 40 ° C.
Immediately after the saponification reaction has progressed, a gelled product is formed and removed from the reaction system and pulverized. Then, methyl acetate is added to the pulverized product when 1 hour has elapsed since the start of the saponification reaction. The PVA neutralized and swollen with methanol was obtained. Subsequently, it wash | cleaned using methanol, and it dried at 65 degreeC for 16 hours, and obtained silyl group containing PVA (A1).
In the obtained silyl group-containing PVA (A1), the content of vinyltrimethylsilane units was 0.8 mol%, the saponification degree was 98.0 mol%, and the polymerization degree was 2500.

Synthesis Example 2 Synthesis of silyl group-containing PVA (A2) A separable flask having a 3 L internal volume equipped with a stirrer, a temperature sensor, a dropping funnel and a reflux condenser was charged with 1200 g of vinyl acetate, 1800 g of methanol, and vinyltrimethoxysilane. 7 g was charged and the inside of the system was purged with nitrogen under stirring, and then the internal temperature was raised to 60 ° C. To this system, 1.5 g of 2,2′-azobisisobutyronitrile was added to initiate the polymerization reaction. The polymerization reaction was carried out for 4 hours while adding 200 g of methanol containing 2% by weight of vinyltrimethoxysilane to the system from the start of the polymerization, and the polymerization reaction was stopped at that time. When the polymerization reaction was stopped, the solid content concentration in the system was 35.1%. Next, methanol vapor was introduced into the system to drive off unreacted vinyl acetate monomer, thereby obtaining a methanol solution containing 40% vinyl ester polymer.
The molar ratio of sodium hydroxide to vinyl acetate units in the vinyl ester polymer is 0.02 with respect to a methanol solution containing 40% of the vinyl ester polymer, and the solid content concentration of the vinyl ester polymer is 20% by weight. %, Methanol and a methanol solution containing 10% by weight of sodium hydroxide were added in this order under stirring, and the saponification reaction was started at 40 ° C.
Immediately after the saponification reaction has progressed, a gelled product is formed and removed from the reaction system and pulverized. Then, methyl acetate is added to the pulverized product when 1 hour has elapsed since the start of the saponification reaction. The PVA neutralized and swollen with methanol was obtained. Subsequently, it wash | cleaned using methanol, and it dried at 65 degreeC for 16 hours, and obtained silyl group containing PVA (A2). In the obtained silyl group-containing PVA (A2), the vinyltrimethylsilane unit content was 2.0 mol%, the saponification degree was 98.0 mol%, and the polymerization degree was 500.

Example 1
1 g of sodium hydroxide was dissolved in 100 g of distilled water, and 2.5 g of 1-naphthol (B1) and 0.4 g of hydrosulfite sodium were further dissolved therein as a hydroxyl group-containing aromatic compound. Thereafter, 5.0 g of silyl group-containing PVA obtained in Synthesis Example 1 as PVA (A1: polymerization degree 2500, saponification degree 98.0 mol%, silyl group content 0.8 mol%) was heated and dissolved at 80 ° C. for 2 hours. did. After cooling to room temperature, 1 g of polyoxyethylene lauryl ether (C1) was added to prepare a scale adhesion inhibitor. The pH of the scale inhibitor (aqueous solution) was 12.5.

Examples 2-8
A scale adhesion inhibitor was prepared in the same manner as in Example 1 except that the types and amounts of silyl group-containing PVA and ethylene oxide nonionic surfactant were changed to the contents shown in Table 1. The scale adhesion prevention property was evaluated. The results are shown in Table 1.

Example 9
In the suspension polymerization of vinyl chloride, polyvinyl alcohol (PVA-420H manufactured by Kuraray Co., Ltd .: polymerization degree 2000, saponification degree 80 mol%) as a dispersion stabilizer in an amount corresponding to 1000 ppm with respect to the vinyl chloride monomer. Used as a dispersion stabilizing aid, as in Example 1, except that polyvinyl alcohol having a polymerization degree of 250 and a saponification degree of 40 mol% was used in an amount corresponding to 200 ppm with respect to the vinyl chloride monomer. Sexuality was evaluated. The results are shown in Table 1.

Comparative Example 1
A scale adhesion preventing agent was prepared in the same manner as in Example 1 except that the ethylene oxide-based nonionic surfactant was not used, and the scale adhesion preventing property was evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2
A scale adhesion inhibitor was prepared in the same manner as in Example 1 except that PVA was changed to PVA (A3) (“PVA-117” manufactured by Kuraray Co., Ltd., unmodified PVA). The anti-adhesion property was evaluated. The results are shown in Table 1.

Comparative Examples 3-5
A scale adhesion inhibitor was prepared in the same manner as in Example 1 except that the type of the surfactant was changed to the contents shown in Table 1, and the scale adhesion prevention property was evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 6
A scale adhesion preventing agent was prepared in the same manner as in Example 1 except that the hydroxyl group-containing aromatic compound was not used, and the scale adhesion preventing property was evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 7
A scale adhesion inhibitor was prepared in the same manner as in Example 1 except that the hydroxyl group-containing aromatic compound and the ethylene oxide nonionic surfactant were not used. went. The results are shown in Table 1.

  From the results of Table 1 above, the scale adhesion preventive agent of the present invention containing PVA having a silyl group having a specific structure, a hydroxyl group-containing aromatic compound, and an ethylene oxide nonionic surfactant (Examples 1 to 9) Used a scale adhesion inhibitor (Comparative Example 1) composed of a silyl group-modified PVA and a hydroxyl group-containing aromatic compound, a scale adhesion inhibitor (Comparative Example 2) in combination with an unmodified PVA, and an anionic surfactant. Scale adhesion inhibitor (Comparative Examples 3 and 4), Scale inhibitor composed of silyl group-modified PVA and ethylene oxide nonionic surfactant (Comparative Example 6), Scale adhesion inhibitor composed of silyl group-modified PVA (Comparative Example) Compared with 7), it can be seen that since the coating is uniformly formed on the inner wall of the polymerization reactor, it is superior in scale adhesion prevention. The reason why such an excellent effect is brought about by the scale adhesion preventing agent of the present invention is that the use of the silyl group-containing PVA makes it possible to form a hydrophilic and water-resistant film, and the hydroxyl group-containing aromatic. It is considered that this is because different effects synergistically act by inhibiting the polymerization by using the compound and improving the wettability to the inner wall of the polymerization reactor by using the nonionic surfactant.

  The scale adhesion preventing agent of the present invention can be effectively used for production of a polymer by suspension polymerization, emulsion polymerization, solution polymerization, bulk polymerization, gas phase polymerization and the like.

Claims (3)

A scale adhesion inhibitor comprising the following component A, component B and component C, and comprising an aqueous solution having a pH of 9 or more.
Component A: A vinyl alcohol polymer having a silyl group content of 0.1 to 10 mol% represented by the following general formula (1).
Component B: A hydroxyl group-containing aromatic compound.
Component C: an ethylene oxide nonionic surfactant.

(Here, R ¹ represents a hydrogen atom or a hydrocarbon group having 8 or less carbon atoms which may have a substituent, and R ² has 1 to 1 carbon atoms which may have a substituent containing oxygen. 40 represents an alkoxyl group or an acyloxyl group, n represents an integer of 0 to 2, m represents an integer of 0 to 3, and X represents a monovalent metal atom, provided that the sum of n and m is 3 or less. is there.)   The scale adhesion preventing agent according to claim 1, wherein the hydroxyl group-containing aromatic compound of component B is naphthol. The scale adhesion preventive agent according to claim 1 or 2, wherein the ethylene oxide nonionic surfactant of component C is at least one compound represented by the following general formula (2), (3) or (4): .

(R ¹ represents a hydrogen atom or an optionally substituted hydrocarbon group having 18 or less carbon atoms, and n represents an integer of 1 to 30.)

(R ¹ represents a hydrogen atom or an optionally substituted hydrocarbon group having 18 or less carbon atoms, x represents an integer of 1 to 30, and y represents an integer of 1 to 30.)

(M + n represents an integer of 1 to 35.)