JP2009028618A - Scale inhibitor and (meth)acrylic polymer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a scale inhibitor extremely excellent in scale inhibiting ability against calcium phosphate and a (meth)acrylic polymer useful for the scale inhibitor. <P>SOLUTION: The scale inhibitor contains the (meth)acrylic polymer having a constituent unit (a) derived from a (meth)acrylic monomer (A) having a specific structure, a constituent unit (b) derived from a sulfonic monomer (B) having a specific structure, and a constituent unit (c) derived from a (meth)acrylic monomer (C) having another specific structure. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a scale inhibitor and a (meth) acrylic acid polymer. Specifically, the present invention relates to a scale inhibitor such as calcium carbonate and calcium phosphate that is extremely excellent in scale prevention effects, and a (meth) acrylic acid polymer useful for such a scale inhibitor.

  In cooling water systems, boiler water systems, seawater desalination equipment, pulp dissolving kettles, black liquor concentration kettles, etc., deposits (scales) such as calcium carbonate, zinc phosphate, calcium phosphate, zinc hydroxide, magnesium silicate adhere to the inner wall. However, it may cause a decrease in thermal efficiency and local corrosion.

  In order to effectively prevent the above scale, a scale inhibitor using a (meth) acrylic acid polymer has been proposed (Patent Documents 1 to 3).

However, the scale preventive agent using the (meth) acrylic acid-based polymer proposed so far has not been sufficient in scale preventive ability for calcium phosphate.
JP 2001-087794 A JP 2002-003535 A JP 2007-038120 A

  An object of the present invention is to provide a scale inhibitor having an excellent ability to prevent scale against calcium phosphate, and a (meth) acrylic acid polymer useful for such a scale inhibitor.

（式（１）中、Ｒ^１は水素原子またはメチル基を表し、Ｘは水素原子、金属原子、アンモニウム基、有機アンモニウム基、または有機アミノ基を表す。）

（式（２）中、Ｒ^２、Ｒ^３、Ｒ^４は、同一または異なって、水素原子またはメチル基を表し、ｐは０または１を表し、Ｒ^５は、−ＣＨ_２−、−ＣＨ_２−ＣＨ_２−、−ＣＨ_２−Ｏ−ＣＨ_２−、−ＣＯ−Ｏ−ＣＨ_２−ＣＨ_２−、または−ＣＯ−ＮＨ−Ｃ（ＣＨ_３）_２−を表し、Ｙは−ＳＯ_３Ｘまたは−ＣＨＲ^６−ＣＨ_２Ｒ^７を表し、Ｒ^６、Ｒ^７は、同一または異なって、−ＯＨまたは−ＳＯ_３Ｘを表し、Ｒ^６とＲ^７の少なくとも一方は−ＳＯ_３Ｘであり、Ｘは水素原子、金属原子、アンモニウム基、有機アンモニウム基、または有機アミノ基を表す。）

（式（３）中、Ｒ^８は水素原子、メチル基、ヒドロキシメチル基、またはヒドロキシエチル基を表し、Ｒ^９は水素原子、炭素数１〜２０のアルキル基を表し、Ｒ^８が水素原子またはメチル基の場合にはＲ^９は水素原子ではない。） The scale inhibitor of the present invention includes a structural unit (a) derived from the (meth) acrylic acid monomer (A) represented by the formula (1), and a sulfonic acid based monomer represented by the formula (2). (Meth) acrylic acid-based heavy having the structural unit (b) derived from the body (B) and the structural unit (c) derived from the (meth) acrylic acid monomer (C) represented by the formula (3) Includes coalescence.

(In formula (1), R ¹ represents a hydrogen atom or a methyl group, and X represents a hydrogen atom, a metal atom, an ammonium group, an organic ammonium group, or an organic amino group.)

(In the formula (2), R ² , R ³ and R ⁴ are the same or different and each represents a hydrogen atom or a methyl group, p represents 0 or 1, and R ⁵ represents —CH ₂ —, —CH _{2. -CH 2 -, - CH 2 -O} -CH 2 -, - CO-O-CH 2 -CH 2 -, or _{-CO-NH-C (CH 3} ) 2 - , Y represents the -SO ₃ X or represents -CHR ⁶ -CH ₂ R ^7, R 6, ^{R 7} are the same or different and each represents -OH or -SO ₃ X, at least one of ^{R 6} and ^{R 7} is -SO ₃ X, X Represents a hydrogen atom, a metal atom, an ammonium group, an organic ammonium group, or an organic amino group.)

(In Formula (3), R ⁸ represents a hydrogen atom, a methyl group, a hydroxymethyl group, or a hydroxyethyl group, R ⁹ represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, and R ⁸ represents a hydrogen atom or In the case of a methyl group, R ⁹ is not a hydrogen atom.)

In a preferred embodiment, in the above formula (2), p is 1 and R ⁵ is —CH ₂ —O—CH ₂ —.

In a preferred embodiment, in the formula (2), Y is _{-CH (OH) -CH 2 -SO 3} X.

In a preferred embodiment, in the above formula (3), ^{R 9} is an alkyl group having 1 to 20 carbon atoms.

（式（１）中、Ｒ^１は水素原子またはメチル基を表し、Ｘは水素原子、金属原子、アンモニウム基、有機アンモニウム基、または有機アミノ基を表す。）

（式（２）中、Ｒ^２、Ｒ^３、Ｒ^４は、同一または異なって、水素原子またはメチル基を表し、ｐは０または１を表し、Ｒ^５は、−ＣＨ_２−、−ＣＨ_２−ＣＨ_２−、−ＣＨ_２−Ｏ−ＣＨ_２−、−ＣＯ−Ｏ−ＣＨ_２−ＣＨ_２−、または−ＣＯ−ＮＨ−Ｃ（ＣＨ_３）_２−を表し、Ｙは−ＳＯ_３Ｘまたは−ＣＨＲ^６−ＣＨ_２Ｒ^７を表し、Ｒ^６、Ｒ^７は、同一または異なって、−ＯＨまたは−ＳＯ_３Ｘを表し、Ｒ^６とＲ^７の少なくとも一方は−ＳＯ_３Ｘであり、Ｘは水素原子、金属原子、アンモニウム基、有機アンモニウム基、または有機アミノ基を表す。）

（式（４）中、ｍは０、１、または２であり、Ｒ^１０は水素原子、炭素数１〜２０のアルキル基を表す。） According to another aspect of the present invention, a (meth) acrylic acid polymer is provided. The (meth) acrylic acid polymer of the present invention is represented by the structural unit (a) derived from the (meth) acrylic acid monomer (A) represented by the formula (1) and the formula (2). It has the structural unit (b) derived from the sulfonic acid monomer (B) and the structural unit (d) derived from the (meth) acrylic acid monomer (D) represented by the formula (4).

(In formula (1), R ¹ represents a hydrogen atom or a methyl group, and X represents a hydrogen atom, a metal atom, an ammonium group, an organic ammonium group, or an organic amino group.)

(In the formula (2), R ² , R ³ and R ⁴ are the same or different and each represents a hydrogen atom or a methyl group, p represents 0 or 1, and R ⁵ represents —CH ₂ —, —CH _{2. -CH 2 -, - CH 2 -O} -CH 2 -, - CO-O-CH 2 -CH 2 -, or _{-CO-NH-C (CH 3} ) 2 - , Y represents the -SO ₃ X or represents -CHR ⁶ -CH ₂ R ^7, R 6, ^{R 7} are the same or different and each represents -OH or -SO ₃ X, at least one of ^{R 6} and ^{R 7} is -SO ₃ X, X Represents a hydrogen atom, a metal atom, an ammonium group, an organic ammonium group, or an organic amino group.)

(In the formula (4), m is 0, 1 or ^{2,, R 10} represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms.)

In a preferred embodiment, in the above formula (2), p is 1 and R ⁵ is —CH ₂ —O—CH ₂ —.

In a preferred embodiment, in the formula (2), Y is _{-CH (OH) -CH 2 -SO 3} X.

In a preferred embodiment, in the above formula ^{(4), R 10} is an alkyl group having 1 to 20 carbon atoms.

  ADVANTAGE OF THE INVENTION According to this invention, the scale inhibitor which was extremely excellent in the scale prevention ability with respect to calcium phosphate, and the (meth) acrylic-acid type polymer useful for such a scale inhibitor can be provided.

（式（１）中、Ｒ^１は水素原子またはメチル基を表し、Ｘは水素原子、金属原子、アンモニウム基、有機アンモニウム基、または有機アミノ基を表す。）

（式（２）中、Ｒ^２、Ｒ^３、Ｒ^４は、同一または異なって、水素原子またはメチル基を表し、ｐは０または１を表し、Ｒ^５は、−ＣＨ_２−、−ＣＨ_２−ＣＨ_２−、−ＣＨ_２−Ｏ−ＣＨ_２−、−ＣＯ−Ｏ−ＣＨ_２−ＣＨ_２−、または−ＣＯ−ＮＨ−Ｃ（ＣＨ_３）_２−を表し、Ｙは−ＳＯ_３Ｘまたは−ＣＨＲ^６−ＣＨ_２Ｒ^７を表し、Ｒ^６、Ｒ^７は、同一または異なって、−ＯＨまたは−ＳＯ_３Ｘを表し、Ｒ^６とＲ^７の少なくとも一方は−ＳＯ_３Ｘであり、Ｘは水素原子、金属原子、アンモニウム基、有機アンモニウム基、または有機アミノ基を表す。）

（式（３）中、Ｒ^８は水素原子、メチル基、ヒドロキシメチル基、またはヒドロキシエチル基を表し、Ｒ^９は水素原子、炭素数１〜２０のアルキル基を表し、Ｒ^８が水素原子またはメチル基の場合にはＲ^９は水素原子ではない。） [Scale inhibitor]
The scale inhibitor of the present invention includes a structural unit (a) derived from the (meth) acrylic acid monomer (A) represented by the formula (1), and a sulfonic acid based monomer represented by the formula (2). (Meth) acrylic acid-based heavy having the structural unit (b) derived from the body (B) and the structural unit (c) derived from the (meth) acrylic acid monomer (C) represented by the formula (3) Includes coalescence.

(In formula (1), R ¹ represents a hydrogen atom or a methyl group, and X represents a hydrogen atom, a metal atom, an ammonium group, an organic ammonium group, or an organic amino group.)

(In the formula (2), R ² , R ³ and R ⁴ are the same or different and each represents a hydrogen atom or a methyl group, p represents 0 or 1, and R ⁵ represents —CH ₂ —, —CH _{2. -CH 2 -, - CH 2 -O} -CH 2 -, - CO-O-CH 2 -CH 2 -, or _{-CO-NH-C (CH 3} ) 2 - , Y represents the -SO ₃ X or represents -CHR ⁶ -CH ₂ R ^7, R 6, ^{R 7} are the same or different and each represents -OH or -SO ₃ X, at least one of ^{R 6} and ^{R 7} is -SO ₃ X, X Represents a hydrogen atom, a metal atom, an ammonium group, an organic ammonium group, or an organic amino group.)

(In the formula (3), ^{R 8} represents a hydrogen atom, a methyl group, a hydroxymethyl group or a hydroxyethyl group,, ^{R 9} represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, ^{R 8} is a hydrogen atom or In the case of a methyl group, R ⁹ is not a hydrogen atom.)

  The structural unit (a) derived from the (meth) acrylic acid monomer (A) represented by the formula (1) in the (meth) acrylic acid polymer may be present alone. It is good, and two or more kinds may coexist.

In the structural unit (a), as represented by the formula (5), an unsaturated double bond is opened by a polymerization reaction in the (meth) acrylic acid monomer (A) represented by the formula (1). This is a single bond.

In the above formulas (1) and (5), R ¹ represents a hydrogen atom or a methyl group.

  In the above formulas (1) and (5), X represents a hydrogen atom, a metal atom, an ammonium group, an organic ammonium group, or an organic amino group. Examples of the metal atom include alkali metals such as sodium and potassium; alkaline earth metals such as magnesium and calcium; aluminum; iron; X is preferably a hydrogen atom, an alkali metal atom, or an ammonium group, more preferably a hydrogen atom, sodium, or potassium, and still more preferably a hydrogen atom or sodium.

  Specific examples of the (meth) acrylic acid monomer (A) represented by the above formula (1) include acrylic acid and its salt, methacrylic acid and its salt, and the like. In order to more fully exhibit the effects of the present invention, acrylic acid and its salt are preferable, and acrylic acid and its sodium salt are more preferable.

  The content ratio of the structural unit (a) to the total of the structural unit (a), the structural unit (b) and the structural unit (c) in the (meth) acrylic acid polymer is preferably 60 to 95 mol. %, More preferably 75 to 90 mol%. When the content ratio is less than 60 mol%, there is a possibility that the scale preventing ability for calcium carbonate cannot be fully exhibited when the scale inhibitor is used. When the content ratio exceeds 95 mol%, there is a possibility that the scale preventing ability for calcium phosphate cannot be sufficiently exhibited when the scale inhibitor is used.

  The structural unit (b) derived from the sulfonic acid monomer (B) represented by the formula (2) in the (meth) acrylic acid polymer may be present alone, Two or more types may coexist.

The structural unit (b), as represented by the formula (6), is a single bond in which an unsaturated double bond is opened by a polymerization reaction in the sulfonic acid monomer (B) represented by the formula (2). This is the form.

In the above formulas (2) and (6), R ² , R ³ and R ⁴ are the same or different and represent a hydrogen atom or a methyl group. In order to achieve the effect of the present invention more fully, preferably, all of R ² , R ³ and R ⁴ are hydrogen atoms, or R ² and R ³ are hydrogen atoms and R ⁴ is a methyl group, More preferably, all of R ² , R ³ and R ⁴ are hydrogen atoms.

In the above formulas (2) and (6), p represents 0 or 1. when p is 1, ^{R 5} _{is, -CH 2 -, - CH 2} -CH 2 -, - CH 2 -O-CH 2 -, - CO-O-CH 2 -CH 2 - or -CO-NH, -C _{(CH 3) 2} - represents a. In order to exhibit the effect of the present invention more fully, preferably, p is 1, and R ⁵ is —CH ₂ —, —CH ₂ —CH ₂ —, or —CH ₂ —O—CH ₂ —. Yes, more preferably, p is 1 and R ⁵ is —CH ₂ —O—CH ₂ —.

In the above formulas (2) and (6), Y represents —SO ₃ X or —CHR ⁶ —CH ₂ R ⁷ , and R ⁶ and R ⁷ are the same or different and represent —OH or —SO ₃ X. And at least one of R ⁶ and R ⁷ is —SO ₃ X, and X represents a hydrogen atom, a metal atom, an ammonium group, an organic ammonium group, or an organic amino group. Examples of the metal atom include alkali metals such as sodium and potassium; alkaline earth metals such as magnesium and calcium; aluminum; iron; X is preferably a hydrogen atom, an alkali metal atom, or an ammonium group, more preferably a hydrogen atom, sodium, or potassium, and still more preferably a hydrogen atom or sodium. Y is preferably —CH (OH) —CH ₂ —SO ₃ X in order to more fully exhibit the effects of the present invention.

  Specific examples of the sulfonic acid monomer (B) represented by the above formula (2) include, for example, vinyl sulfonic acid and its salt, (meth) allyl sulfonic acid and its salt, 3- (meth) allyloxy- 2-hydroxypropanesulfonic acid and its salt, 3- (meth) allyloxy-1-hydroxypropanesulfonic acid and its salt, 2- (meth) allyloxyethylenesulfonic acid and its salt, 2-acrylamido-2-methylpropanesulfone Examples include acids and salts thereof. In order to achieve the effect of the present invention more sufficiently, (meth) allylsulfonic acid and its salt, 3- (meth) allyloxy-2-hydroxypropanesulfonic acid and its salt, more preferably 3- (Meth) allyloxy-2-hydroxypropanesulfonic acid and its salt, more preferably 3-allyloxy-2-hydroxypropanesulfonic acid and its sodium salt.

  The content ratio of the structural unit (b) to the total of the structural unit (a), the structural unit (b), and the structural unit (c) in the (meth) acrylic acid polymer is preferably 5 to 40 mol. %, More preferably 10 to 25 mol%. When the content ratio is less than 5 mol%, there is a possibility that the scale preventing ability for calcium phosphate cannot be sufficiently exhibited when the scale inhibitor is used. When the content ratio exceeds 40 mol%, there is a possibility that the scale preventing ability for calcium carbonate cannot be sufficiently exhibited when the scale inhibitor is used.

  The structural unit (c) derived from the (meth) acrylic acid monomer (C) represented by the formula (3) in the (meth) acrylic acid polymer may be present alone. It is good, and two or more kinds may coexist.

In the structural unit (c), as represented by the formula (7), an unsaturated double bond is opened by a polymerization reaction in the (meth) acrylic acid monomer (C) represented by the formula (3). This is a single bond.

In the above formulas (3) and (7), R ⁸ represents a hydrogen atom, a methyl group, a hydroxymethyl group, or a hydroxyethyl group, R ⁹ represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, and R ^{When 8} is a hydrogen atom or a methyl group, R ⁹ is not a hydrogen atom. R ⁹ is preferably an alkyl group having 1 to 20 carbon atoms.

Examples of the alkyl group having 1 to 20 carbon atoms include methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, and isopentyl. Group, neopentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, 2-ethylhexyl group, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group and the like. In order to more fully exhibit the effects of the present invention, R ⁹ is preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 5 carbon atoms, and still more preferably. , An alkyl group having 3 carbon atoms, particularly preferably an n-butyl group.

  The content ratio of the structural unit (c) to the total of the structural unit (a), the structural unit (b), and the structural unit (c) in the (meth) acrylic acid polymer is preferably 2 to 20 mol. %, More preferably 4 to 15 mol%. When the content ratio is less than 2 mol%, there is a possibility that the scale preventing ability particularly for calcium phosphate cannot be sufficiently expressed when the scale inhibitor is used. When the content ratio exceeds 20 mol%, there is a possibility that the scale preventing ability with respect to calcium carbonate cannot be sufficiently exhibited when the scale inhibitor is used.

  The total content of the structural unit (a), the structural unit (b), and the structural unit (c) in all the structural units of the (meth) acrylic acid polymer is preferably 80 mol% or more, more preferably. Is 90 mol% or more. When the content ratio is less than 80 mol%, there is a possibility that the scale preventive ability cannot be sufficiently expressed when the scale inhibitor is used.

  It is also possible to use a part of the (meth) acrylic acid monomer (C) in place of styrene. However, in that case, there is a possibility that the ability to prevent scale against calcium phosphate may be reduced as compared with the case where styrene is not used in combination. Therefore, it is preferable to use the (meth) acrylic acid monomer (C) in the preferred range as in the present invention.

  The (meth) acrylic acid polymer has a structural unit (e) derived from another monomer (E) in addition to the structural unit (a), the structural unit (b), and the structural unit (c). You may do it. As for the structural unit (e) derived from the other monomer (E), only one type may be present, or two or more types may be present together. The other monomer (E) may be any suitable monomer as long as it is a monomer copolymerizable with the monomer (A), monomer (B), and monomer (C). A mer may be employed.

  The weight average molecular weight of the (meth) acrylic acid polymer is preferably 2000 to 100,000, more preferably 3000 to 80000, and still more preferably 4000 to 60000. When the weight average molecular weight of the (meth) acrylic acid polymer is within the above range, the effects of the present invention can be more sufficiently exhibited.

  The (meth) acrylic acid polymer can be produced by any appropriate method. For example, it can be produced by polymerizing monomer components including the monomer (A), the monomer (B), and the monomer (C).

  Any appropriate method can be adopted as the polymerization method. For example, solution polymerization, bulk polymerization, suspension polymerization, emulsion polymerization and the like can be mentioned.

  Arbitrary appropriate methods can be employ | adopted as a solvent which can use a solvent in the said superposition | polymerization. For example, C1-C4 lower alcohols, such as water and isopropyl alcohol, etc. are mentioned. Only 1 type may be used for a solvent and it may use 2 or more types together.

  Any appropriate polymerization initiator can be used in the polymerization. Only one polymerization initiator may be used, or two or more polymerization initiators may be used in combination. Examples of the polymerization initiator include persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate; 2,2-azobis (2-amidinopropane) hydrochloride, 2,2-azobis [2-methyl-N -(2-hydroxyethyl) -propionamide] and the like; hydrogen peroxide; peroxides such as t-butylhydroxyperoxide; and the like. Among these, persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate are preferable. This is because the polymerization rate is improved and the amount of residual monomer can be reduced. The usage-amount of a polymerization initiator is 0.001 to 10 weight% with respect to all the monomers, for example.

  In the polymerization, sulfite may be used. Examples of the sulfite include sodium hydrogen sulfite, potassium hydrogen sulfite, ammonium hydrogen sulfite, sodium sulfite, potassium sulfite, and ammonium sulfite. Among these, sodium bisulfite is preferable. Sulfite can act as a chain transfer agent. Only one sulfite may be used, or two or more sulfites may be used in combination.

  In the polymerization, a polymerization aid may be used. Examples of the polymerization aid include transition metal compounds such as iron and moor salts (ferrous ammonium sulfate hexahydrate); mercapto compounds such as mercaptoethanol and mercaptopropionic acid; ascorbate. Only one type of polymerization aid may be used, or two or more types may be used in combination.

  Arbitrary appropriate temperature can be employ | adopted for the polymerization reaction temperature in the case of the said superposition | polymerization. For example, 50-150 degreeC is preferable, 70-120 degreeC is more preferable, and 80-110 degreeC is further more preferable.

  In the above polymerization, the raw materials and various additives (polymerization initiators) may be added by any appropriate method. For example, continuous addition or divided addition may be used. Any appropriate time may be set as the addition time. For example, it is preferably 30 to 480 minutes.

  When the polymerization is completed, the solid content concentration in the polymerization reaction system is preferably 30% by weight or more, more preferably 35% by weight or more, and further preferably 40% by weight or more.

  The (meth) acrylic acid polymer obtained by the above polymerization may be further neutralized with an alkaline substance as necessary. Examples of the alkaline substance include hydroxides, chlorides and carbonates of alkali metals such as sodium and potassium; hydroxides, chlorides and carbonates of alkaline earth metals such as calcium and magnesium; ammonia; monoethanol And organic amines such as amine, diethanolamine, and triethanolamine. The alkaline substance may be used alone or in combination of two or more.

  The scale inhibitor of the present invention contains the (meth) acrylic acid polymer. That is, the scale inhibitor of the present invention may be composed of the (meth) acrylic acid polymer alone or contains the (meth) acrylic acid polymer and other additives. May be. Arbitrary appropriate additives can be employ | adopted as said other additive. For example, polycarboxylic acid polymers such as phosphorus compounds, polyacrylic acid and / or salts thereof, polymaleic acid and / or salts thereof, acrylic acid copolymers and styrene / maleic acid copolymers; other scales An inhibitor; a slime inhibitor; a chelating agent; an oxygen scavenger; One of the other additives may be used, or two or more may be used in combination.

  The scale inhibitor of the present invention can be used by adding any appropriate amount to water of water such as cooling water and boiler water. Preferably, it is 0.1-100 ppm with respect to water, More preferably, it is 1-50 ppm with respect to water.

  The scale inhibitor of the present invention may be added to a water system such as a cooling water system or a boiler water system as it is. Further, when adding the scale inhibitor of the present invention to an aqueous system, a phosphate compound and / or a zinc salt may be added together. By adding a phosphate compound and / or a zinc salt together, corrosion of iron piping that can be used as an aqueous flow path can be prevented. Examples of the phosphoric acid compound include polymerized phosphoric acid and / or a salt thereof, phosphoric acid and / or a salt thereof, phosphonic acid and / or a salt thereof, and the like. Examples of the zinc salt include zinc nitrate and zinc chloride. Only 1 type may be used for the phosphoric acid type compound and zinc salt which can be added, and 2 or more types may be used together.

  Since the scale preventive agent of the present invention contains the specific (meth) acrylic acid polymer as described above, the scale preventive ability for calcium phosphate is extremely excellent. Moreover, it is excellent also in the scale prevention ability with respect to other scales, such as a calcium carbonate.

（式（１）中、Ｒ^１は水素原子またはメチル基を表し、Ｘは水素原子、金属原子、アンモニウム基、有機アンモニウム基、または有機アミノ基を表す。）

（式（２）中、Ｒ^２、Ｒ^３、Ｒ^４は、同一または異なって、水素原子またはメチル基を表し、ｐは０または１を表し、Ｒ^５は、−ＣＨ_２−、−ＣＨ_２−ＣＨ_２−、−ＣＨ_２−Ｏ−ＣＨ_２−、−ＣＯ−Ｏ−ＣＨ_２−ＣＨ_２−、または−ＣＯ−ＮＨ−Ｃ（ＣＨ_３）_２−を表し、Ｙは−ＳＯ_３Ｘまたは−ＣＨＲ^６−ＣＨ_２Ｒ^７を表し、Ｒ^６、Ｒ^７は、同一または異なって、−ＯＨまたは−ＳＯ_３Ｘを表し、Ｒ^６とＲ^７の少なくとも一方は−ＳＯ_３Ｘであり、Ｘは水素原子、金属原子、アンモニウム基、有機アンモニウム基、または有機アミノ基を表す。）

（式（４）中、ｍは０、１、または２であり、Ｒ^１０は水素原子、炭素数１〜２０のアルキル基を表す。） [(Meth) acrylic acid polymer]
The (meth) acrylic acid polymer of the present invention is represented by the structural unit (a) derived from the (meth) acrylic acid monomer (A) represented by the formula (1) and the formula (2). It has the structural unit (b) derived from the sulfonic acid monomer (B) and the structural unit (d) derived from the (meth) acrylic acid monomer (D) represented by the formula (4).

(In formula (1), R ¹ represents a hydrogen atom or a methyl group, and X represents a hydrogen atom, a metal atom, an ammonium group, an organic ammonium group, or an organic amino group.)

(In the formula (2), R ² , R ³ and R ⁴ are the same or different and each represents a hydrogen atom or a methyl group, p represents 0 or 1, and R ⁵ represents —CH ₂ —, —CH _{2. -CH 2 -, - CH 2 -O} -CH 2 -, - CO-O-CH 2 -CH 2 -, or _{-CO-NH-C (CH 3} ) 2 - , Y represents the -SO ₃ X or represents -CHR ⁶ -CH ₂ R ^7, R 6, ^{R 7} are the same or different and each represents -OH or -SO ₃ X, at least one of ^{R 6} and ^{R 7} is -SO ₃ X, X Represents a hydrogen atom, a metal atom, an ammonium group, an organic ammonium group, or an organic amino group.)

(In the formula (4), m is 0, 1 or ^{2,, R 10} represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms.)

  The structural unit (a) derived from the (meth) acrylic acid monomer (A) represented by the formula (1) in the (meth) acrylic acid polymer may be present alone. It is good, and two or more kinds may coexist.

In the structural unit (a), as represented by the formula (5), an unsaturated double bond is opened by a polymerization reaction in the (meth) acrylic acid monomer (A) represented by the formula (1). This is a single bond.

In the above formulas (1) and (5), R ¹ represents a hydrogen atom or a methyl group.

  In the above formulas (1) and (5), X represents a hydrogen atom, a metal atom, an ammonium group, an organic ammonium group, or an organic amino group. Examples of the metal atom include alkali metals such as sodium and potassium; alkaline earth metals such as magnesium and calcium; aluminum; iron; X is preferably a hydrogen atom, an alkali metal atom, or an ammonium group, more preferably a hydrogen atom, sodium, or potassium, and still more preferably a hydrogen atom or sodium.

  Specific examples of the (meth) acrylic acid monomer (A) represented by the above formula (1) include acrylic acid and its salt, methacrylic acid and its salt, and the like. In order to more fully exhibit the effects of the present invention, acrylic acid and its salt are preferable, and acrylic acid and its sodium salt are more preferable.

  The content ratio of the structural unit (a) to the total of the structural unit (a), the structural unit (b), and the structural unit (d) in the (meth) acrylic acid polymer is preferably 60 to 95 mol. %, More preferably 75 to 90 mol%. When the content ratio is less than 60 mol%, there is a possibility that the scale preventing ability for calcium carbonate cannot be fully exhibited when the scale inhibitor is used. When the content ratio exceeds 95 mol%, there is a possibility that the scale preventing ability for calcium phosphate cannot be sufficiently exhibited when the scale inhibitor is used.

  The structural unit (b) derived from the sulfonic acid monomer (B) represented by the formula (2) in the (meth) acrylic acid polymer may be present alone, Two or more types may coexist.

The structural unit (b), as represented by the formula (6), is a single bond in which an unsaturated double bond is opened by a polymerization reaction in the sulfonic acid monomer (B) represented by the formula (2). This is the form.

In the above formulas (2) and (6), R ² , R ³ and R ⁴ are the same or different and represent a hydrogen atom or a methyl group. In order to achieve the effect of the present invention more fully, preferably, all of R ² , R ³ and R ⁴ are hydrogen atoms, or R ² and R ³ are hydrogen atoms and R ⁴ is a methyl group, More preferably, all of R ² , R ³ and R ⁴ are hydrogen atoms.

In the above formulas (2) and (6), p represents 0 or 1. when p is 1, ^{R 5} _{is, -CH 2 -, - CH 2} -CH 2 -, - CH 2 -O-CH 2 -, - CO-O-CH 2 -CH 2 - or -CO-NH, -C _{(CH 3) 2} - represents a. In order to exhibit the effect of the present invention more fully, preferably, p is 1, and R ⁵ is —CH ₂ —, —CH ₂ —CH ₂ —, or —CH ₂ —O—CH ₂ —. Yes, more preferably, p is 1 and R ⁵ is —CH ₂ —O—CH ₂ —.

In the above formulas (2) and (6), Y represents —SO ₃ X or —CHR ⁶ —CH ₂ R ⁷ , and R ⁶ and R ⁷ are the same or different and represent —OH or —SO ₃ X. And at least one of R ⁶ and R ⁷ is —SO ₃ X, and X represents a hydrogen atom, a metal atom, an ammonium group, an organic ammonium group, or an organic amino group. Examples of the metal atom include alkali metals such as sodium and potassium; alkaline earth metals such as magnesium and calcium; aluminum; iron; X is preferably a hydrogen atom, an alkali metal atom, or an ammonium group, more preferably a hydrogen atom, sodium, or potassium, and still more preferably a hydrogen atom or sodium. Y is preferably —CH (OH) —CH ₂ —SO ₃ X in order to more fully exhibit the effects of the present invention.

  Specific examples of the sulfonic acid monomer (B) represented by the above formula (2) include, for example, vinyl sulfonic acid and its salt, (meth) allyl sulfonic acid and its salt, 3- (meth) allyloxy- 2-hydroxypropanesulfonic acid and its salt, 3- (meth) allyloxy-1-hydroxypropanesulfonic acid and its salt, 2- (meth) allyloxyethylenesulfonic acid and its salt, 2-acrylamido-2-methylpropanesulfone Examples include acids and salts thereof. In order to achieve the effect of the present invention more sufficiently, (meth) allylsulfonic acid and its salt, 3- (meth) allyloxy-2-hydroxypropanesulfonic acid and its salt, more preferably 3- (Meth) allyloxy-2-hydroxypropanesulfonic acid and its salt, more preferably 3-allyloxy-2-hydroxypropanesulfonic acid and its sodium salt.

  The content ratio of the structural unit (b) to the total of the structural unit (a), the structural unit (b), and the structural unit (d) in the (meth) acrylic acid polymer is preferably 5 to 40 mol. %, More preferably 10 to 25 mol%. When the content ratio is less than 5 mol%, there is a possibility that the scale preventing ability for calcium phosphate cannot be sufficiently exhibited when the scale inhibitor is used. When the content ratio exceeds 40 mol%, there is a possibility that the scale preventing ability for calcium carbonate cannot be sufficiently exhibited when the scale inhibitor is used.

  The structural unit (d) derived from the (meth) acrylic acid monomer (D) represented by the formula (4) in the (meth) acrylic acid polymer may be present alone. It is good, and two or more kinds may coexist.

In the structural unit (d), as represented by the formula (8), an unsaturated double bond is opened by a polymerization reaction in the (meth) acrylic acid monomer (D) represented by the formula (4). This is a single bond.

  In the above formulas (4) and (8), m is 0, 1, or 2.

The formula (4), in equation ^{(8), R 10} represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms. Preferably, R ¹⁰ is an alkyl group having 1 to 20 carbon atoms.

Examples of the alkyl group having 1 to 20 carbon atoms include methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, and isopentyl. Group, neopentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, 2-ethylhexyl group, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group and the like. In order to exhibit the effects of the present invention more sufficiently, R ⁹ is preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 5 carbon atoms, and still more preferably. , An alkyl group having 4 carbon atoms, particularly preferably an n-butyl group.

  The content ratio of the structural unit (d) with respect to the total of the structural unit (a), the structural unit (b), and the structural unit (d) in the (meth) acrylic acid polymer is preferably 2 to 20 mol. %, More preferably 4 to 15 mol%. When the content ratio is less than 2 mol%, there is a possibility that the scale preventing ability particularly for calcium phosphate cannot be sufficiently expressed when the scale inhibitor is used. When the content ratio exceeds 20 mol%, there is a possibility that the scale preventing ability with respect to calcium carbonate cannot be sufficiently exhibited when the scale inhibitor is used.

  The total content of the structural unit (a), the structural unit (b), and the structural unit (d) in all the structural units of the (meth) acrylic acid polymer is preferably 80 mol% or more, more preferably. Is 90 mol% or more. When the content ratio is less than 80 mol%, there is a possibility that the scale preventive ability cannot be sufficiently expressed when the scale inhibitor is used.

  The (meth) acrylic acid polymer has a structural unit (e) derived from another monomer (E) in addition to the structural unit (a), the structural unit (b), and the structural unit (d). You may do it. As for the structural unit (e) derived from the other monomer (E), only one type may be present, or two or more types may be present together. For the other monomer (E), the above description is incorporated.

  The weight average molecular weight of the (meth) acrylic acid polymer is preferably 2000 to 100,000, more preferably 3000 to 80000, and still more preferably 4000 to 60000. When the weight average molecular weight of the (meth) acrylic acid polymer is within the above range, the effects of the present invention can be more sufficiently exhibited.

  Description of the manufacturing method of the (meth) acrylic-acid polymer used for the scale inhibitor of the above-mentioned this invention is used for the manufacturing method of the said (meth) acrylic-acid-type polymer.

  Although the said (meth) acrylic-acid type polymer is useful as a scale inhibitor, besides it, it can be used for various uses, such as a water treatment agent, a dispersing agent, detergent builder, for example.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples. Unless otherwise specified, parts and% in the examples are based on weight.

<Weight average molecular weight>
The weight average molecular weight of the polymer was measured under the following conditions using, for example, gel permeation chromatography (manufactured by Showa Denko, trade name “Shodex SYSTEM-21”).
Column: “Asahipak GF-710 HQ” and “Asahipak GF-310 HQ” manufactured by Showa Denko are connected in this order.
Eluent: 0.1N sodium acetate / acetonitrile = 7/3 (vol ratio)
Flow rate: 0.5 ml / min
Temperature: 40 ° C
Calibration curve: Created using polyacrylic acid standard sample (manufactured by Soka Kagaku)
Detector: RI, UV (detection wavelength: 220 nm)

<Calcium phosphate scale inhibition rate>
Deionized water, boric acid-sodium borate pH buffer solution, aqueous calcium chloride solution, aqueous polymer solution obtained in Examples and Comparative Examples, and aqueous sodium phosphate solution were added in this order to a 225 ml screw cap bottle, pH = 8 .6, 100 ml of a test solution having a polymer concentration of 6 mg / L in terms of solid content, calcium hardness = 100 mgCaCO ₃ / L, and phosphate ion = 10 mgPO4 ³⁻ / L was prepared. After sealing, it was put in a 60 ° C. hot air dryer. After 40 hours, the test solution was filtered through a filter paper having a pore size of 0.1 μm, and the residual phosphate ion concentration in the filtrate was analyzed. A blank test solution obtained by removing the polymer from the above test solution was prepared as a blank, and the same operation was performed to analyze the residual phosphate ion concentration. The calcium phosphate scale inhibition rate was determined by the following formula.
Calcium phosphate scale inhibition rate = 100 × (R−Q) / (P−Q)
P: Charged phosphate ion concentration (mg / L)
Q: Blank residual phosphate ion concentration (mg / L)
R: Residual phosphate ion concentration (mg / L)

[Example 1]
A 2.5 L SUS separable flask equipped with a reflux condenser and a stirrer was charged with 84.0 g of deionized water and 0.022 g of molle salt, and the temperature was raised to 90 ° C. while stirring. did. Next, 315.0 g of 80% aqueous acrylic acid solution (hereinafter abbreviated as 80% AA), 40% sodium 3-allyloxy-2-hydroxypropanesulfonate in the polymerization reaction system maintained at about 90 ° C. with stirring. (Hereinafter abbreviated as 40% HAPS) 225.0 g, 100% n-butyl acrylate (hereinafter abbreviated as 100% BA) 18.0 g, 35% sodium hydrogen sulfite aqueous solution (hereinafter abbreviated as 35% SBS) 69.5 g (Corresponding to 6.0 g with respect to 1 mol of the monomer in the monomer composition), 81.1 g of 15% sodium persulfate (hereinafter abbreviated as 15% NaPS) (single amount in the monomer composition) (Corresponding to 3.0 g per 1 mol of the body) was dropped from separate dropping nozzles to prepare a reaction solution. The start of dropping of each component is the same. The dropping time is 180 minutes for 80% AA, 150 minutes for 40% HAPS, 120 minutes for 100% BA, 175 minutes for 35% SBS, and 190 minutes for 15% NaPS. It was. In addition, each component was continuously dropped at a constant dropping rate.
After completion of the dropwise addition of 15% NaPS, the reaction solution was kept at 90 ° C. (ripening) for an additional 30 minutes to complete the polymerization. The solid content concentration in the polymerization reaction solution, which is an aqueous solution containing the polymer mixture, was 50% by weight. The weight average molecular weight of the obtained polymer was 9000.
The evaluation results are shown in Table 1.

[Example 2]
A 2.5 L SUS separable flask equipped with a reflux condenser and a stirrer was charged with 89.2 g of deionized water, 28.2 g of 40% HAPS, and 0.010 g of Mole salt, and the temperature was raised to 90 ° C. with stirring. The polymerization reaction system was heated. Next, in the above polymerization reaction system maintained at about 90 ° C. under stirring, 80% AA 145.2 g, 40% HAPS 141.2 g, 100% BA 9.7 g, 35% SBS 17.1 g (in the monomer composition) 15 mol NaPS (corresponding to 4.0 g with respect to 1 mol of monomer in the monomer composition) and 15% NaPS from each separate dropping nozzle. The reaction solution was dropped. The start of dropping of each component is simultaneous, and the dropping time is 180 minutes for 80% AA, 130 minutes for 40% HAPS, 120 minutes for 100% BA, 170 minutes for 35% SBS, and 200 minutes for 15% NaPS. It was. Further, the dropping rate of 15% NaPS was constant for 130 minutes from the start of dropping, and the dropping was continuously carried out at a dropping rate twice that of the previous 130 minutes after the start of dropping. The addition of each component other than 15% NaPS was continuously performed at a constant dropping rate.
After completion of the dropwise addition of 15% NaPS, the reaction solution was kept at 90 ° C. (ripening) for an additional 30 minutes to complete the polymerization. The solid concentration in the polymerization reaction solution, which is an aqueous solution containing a polymer mixture, was 44% by weight. The weight average molecular weight of the obtained polymer was 19000.
The evaluation results are shown in Table 1.

Example 3
A 2.5 L SUS separable flask equipped with a reflux condenser and a stirrer was charged with 89.2 g of deionized water, 28.2 g of 40% HAPS, and 0.010 g of Mole salt, and the temperature was raised to 90 ° C. with stirring. The polymerization reaction system was heated. Next, in the above polymerization reaction system maintained at about 90 ° C. with stirring, 805.2 AA 145.2 g, 40% HAPS 141.2 g, 100% α-hydroxymethylacrylic acid n-butyl ester (hereinafter referred to as 100% RHMA and (Abbreviated) 9.7 g, 35% SBS 17.1 g (corresponding to 3.0 g per 1 mol of monomer in the monomer composition), 15% NaPS 53.3 g (monomer in the monomer composition) (Corresponding to 4.0 g per 1 mol) was dropped from separate dropping nozzles to prepare a reaction solution. The start of dropping of each component is simultaneous, and the dropping time is 180 minutes for 80% AA, 130 minutes for 40% HAPS, 120 minutes for 100% RHMA, 170 minutes for 35% SBS, and 200 minutes for 15% NaPS. It was. Further, the dropping rate of 15% NaPS was constant for 130 minutes from the start of dropping, and the dropping was continuously carried out at a dropping rate twice that of the previous 130 minutes after the start of dropping. The addition of each component other than 15% NaPS was continuously performed at a constant dropping rate.
After completion of the dropwise addition of 15% NaPS, the reaction solution was kept at 90 ° C. (ripening) for an additional 30 minutes to complete the polymerization. The solid concentration in the polymerization reaction solution, which is an aqueous solution containing a polymer mixture, was 44% by weight. The weight average molecular weight of the obtained polymer was 20000.
The evaluation results are shown in Table 1.

[Comparative Example 1]
A 2.5 L SUS separable flask equipped with a reflux condenser and a stirrer was charged with 267.5 g of deionized water, 100.0 g of 40% HAPS, and 0.033 g of molle salt until the boiling point was refluxed while stirring. The temperature was raised to obtain a polymerization reaction system. Next, in the above polymerization reaction system maintained at the boiling point reflux state with stirring, 464.9 g of 80% AA, 518.3 g of 40% HAPS, 56.2 g of 35% SBS (in 1 mol of the monomer in the monomer composition). 15g NaPS (corresponding to 3.1g), 155.5% NaPS (corresponding to 3.9g with respect to 1 mol of the monomer in the monomer composition) was dropped from separate dropping nozzles, respectively, and the reaction solution It was. The dropping of each component was started at the same time, and the dropping time was 180 minutes for 80% AA, 130 minutes for 40% HAPS, 180 minutes for 35% SBS, and 200 minutes for 15% NaPS. Further, the dropping rate of 15% NaPS was constant for 130 minutes from the start of dropping, and the dropping was continuously carried out at a dropping rate twice that of the previous 130 minutes after the start of dropping. The addition of each component other than 15% NaPS was continuously performed at a constant dropping rate.
After completion of the dropwise addition of 15% NaPS, the reaction solution was kept at 90 ° C. (ripening) for an additional 30 minutes to complete the polymerization. The solid concentration in the polymerization reaction solution, which is an aqueous solution containing a polymer mixture, was 43% by weight. The weight average molecular weight of the obtained polymer was 20000.
The evaluation results are shown in Table 1.

  From Table 1, it can be seen that the scale inhibitor of the present invention or the scale inhibitor using the (meth) acrylic acid polymer of the present invention has an extremely excellent ability to prevent scale against calcium phosphate.

  The scale inhibitor of the present invention is useful for preventing scale deposition in a cooling water system, a boiler water system, a seawater desalination apparatus, a pulp dissolving tank, a black liquor concentration tank, and the like. The (meth) acrylic acid polymer of the present invention is useful as a scale inhibitor, but can also be used in various other applications such as a water treatment agent, a dispersant, and a detergent builder.

Claims (8)

Structural unit (a) derived from (meth) acrylic acid monomer (A) represented by formula (1) and structural unit derived from sulfonic acid monomer (B) represented by formula (2) The scale inhibitor containing the (meth) acrylic-acid polymer which has (b) and the structural unit (c) derived from the (meth) acrylic-acid type monomer (C) represented by Formula (3).

(In formula (1), R ¹ represents a hydrogen atom or a methyl group, and X represents a hydrogen atom, a metal atom, an ammonium group, an organic ammonium group, or an organic amino group.)

(In the formula (2), R ² , R ³ and R ⁴ are the same or different and each represents a hydrogen atom or a methyl group, p represents 0 or 1, and R ⁵ represents —CH ₂ —, —CH _{2. -CH 2 -, - CH 2 -O} -CH 2 -, - CO-O-CH 2 -CH 2 -, or _{-CO-NH-C (CH 3} ) 2 - , Y represents the -SO ₃ X or represents -CHR ⁶ -CH ₂ R ^7, R 6, ^{R 7} are the same or different and each represents -OH or -SO ₃ X, at least one of ^{R 6} and ^{R 7} is -SO ₃ X, X Represents a hydrogen atom, a metal atom, an ammonium group, an organic ammonium group, or an organic amino group.)

(In Formula (3), R ⁸ represents a hydrogen atom, a methyl group, a hydroxymethyl group, or a hydroxyethyl group, R ⁹ represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, and R ⁸ represents a hydrogen atom or In the case of a methyl group, R ⁹ is not a hydrogen atom.) The scale inhibitor according to claim 1, wherein in the formula (2), p is 1 and R ⁵ is —CH ₂ —O—CH ₂ —. In the formula (2), Y is _{-CH (OH) -CH 2 -SO 3} X, scale inhibitor of claim 1 or 2. The scale inhibitor according to any one of claims 1 to 3, wherein, in the formula (3), R ⁹ is an alkyl group having 1 to 20 carbon atoms. Structural unit (a) derived from (meth) acrylic acid monomer (A) represented by formula (1) and structural unit derived from sulfonic acid monomer (B) represented by formula (2) A (meth) acrylic acid polymer having (b) and a structural unit (d) derived from the (meth) acrylic acid monomer (D) represented by the formula (4).

(In formula (1), R ¹ represents a hydrogen atom or a methyl group, and X represents a hydrogen atom, a metal atom, an ammonium group, an organic ammonium group, or an organic amino group.)

(In the formula (2), R ² , R ³ and R ⁴ are the same or different and each represents a hydrogen atom or a methyl group, p represents 0 or 1, and R ⁵ represents —CH ₂ —, —CH _{2. -CH 2 -, - CH 2 -O} -CH 2 -, - CO-O-CH 2 -CH 2 -, or _{-CO-NH-C (CH 3} ) 2 - , Y represents the -SO ₃ X or represents -CHR ⁶ -CH ₂ R ^7, R 6, ^{R 7} are the same or different and each represents -OH or -SO ₃ X, at least one of ^{R 6} and ^{R 7} is -SO ₃ X, X Represents a hydrogen atom, a metal atom, an ammonium group, an organic ammonium group, or an organic amino group.)

(In the formula (4), m is 0, 1 or ^{2,, R 10} represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms.) The (meth) acrylic acid polymer according to claim 5, wherein in the formula (2), p is 1 and R ⁵ is —CH ₂ —O—CH ₂ —. In the formula (2), Y is _{-CH (OH) -CH 2 -SO 3} X, ( meth) acrylic acid-based polymer according to claim 5 or 6. The (meth) acrylic acid polymer according to any one of claims 5 to 7, wherein in the formula (4), R ¹⁰ is an alkyl group having 1 to 20 carbon atoms.