JP2011052235A - (meth)acrylic acid-based copolymer, process for production and application of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide high quality (meth)acrylic acid-based copolymers excellent in various performance values and a process for production of the same excellent in productivity. <P>SOLUTION: The copolymers include (a) structural units derived from (meth)acrylic acid-based series monomers and (b) structural units derived from unsaturated monomers, wherein the copolymers have 60,000-1,000,000 of the weight-average molecular weight (Mw), the values of structural units (b) obtained from the equation of (mol%)×(Mw) include 1,000,000 or over, and the molecular weight distribution (Mw/Mn) includes less than 25. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a (meth) acrylic acid copolymer, a method for producing the same, and a use thereof. More specifically, the present invention relates to a (meth) acrylic acid copolymer having basic performance suitable for various uses, a method for producing the same, and uses thereof.

The (meth) acrylic acid copolymer is a copolymer obtained by copolymerizing a (meth) acrylic acid monomer with other monomers, and is useful in various industrial fields. One of industrial raw materials, for example, a copolymer of a (meth) acrylic acid monomer and an allyl monomer is used.

As a conventional (meth) acrylic acid copolymer, a copolymer (salt) obtained by copolymerizing a monomer component containing a specific sulfonic acid group-containing monomer and a carboxylic acid group-containing monomer And a copolymer (salt) having a weight average molecular weight of 20,000 to 500,000 (for example, see Patent Document 1), (a) a structural unit having a sulfonic acid group, (b) A water-soluble copolymer (salt) containing a structural unit having a carboxylic acid group and having a weight average molecular weight of more than 50,000 and not more than 3,000,000 (for example, see Patent Document 2), a sulfonic acid group-containing monomer and a carboxylic acid A copolymer (salt) obtained by copolymerizing a monomer component containing an acid group-containing monomer, and having a weight average molecular weight of 10,000 to 500,000 and containing a sulfonic acid group and a carboxylic acid group A copolymer (salt) (for example, see Patent Document 3) is disclosed. There. However, there has been room for contrivance to use the (meth) acrylic acid copolymer as a high-quality (meth) acrylic acid copolymer that is suitably used in various fields.

As a conventional method for producing a (meth) acrylic acid copolymer, 3-allyloxy-2-hydroxypropanesulfonic acid (acid-type HAPS), acrylic acid (AA), and water added with hydrogen peroxide are refluxed. It is disclosed that an AA / HAPS copolymer (weight average molecular weight: Mw = 132,000) can be obtained by a production method in which the solution is uniformly dropped over 10 hours (see Reference Example 1 and Patent Document 1). However, it takes 10 hours for the polymerization, and it takes time to produce acid-type HAPS, resulting in an increase in cost. Therefore, there is room for improvement in terms of improving productivity.

In addition, an AA / HAPS copolymer (weight average molecular weight: Mw = 98,000) can be obtained by a production method in which acid type HAPS, AA, hydrogen peroxide, and water are initially charged and polymerized under reflux for 4 hours. It is disclosed (see Reference Example 8, Patent Document 1). Similarly, a method of charging raw material monomers all at once in the initial stage is disclosed (for example, see Patent Documents 2 and 3). However, since all of the highly reactive AA and the polymerization initiator are initially charged, a large amount of reaction heat is generated in a short time because the polymerization reaction proceeds rapidly. If the heat removal cannot catch up, the reaction vessel may be destroyed by bumping. Therefore, a high-performance heat removal device is required to prevent bumping, resulting in an increase in cost. Furthermore, since it takes time and cost to manufacture acid-type HAPS, there is room for improvement in terms of productivity improvement (cost reduction).

Further, in the production of the polymer, during the polymerization, a method of removing heat from the reaction system by adding a liquid to the reaction system by spraying, wherein the polymer is a water-soluble polymer, Disclosed is a method for producing a polymer in which the polymerization is stirred solution water-based polymerization and polymerized by refluxing at a polymerization temperature near the boiling point, and the spray spraying sprays water as the liquid over the entire liquid surface of the reaction system. (For example, refer to Patent Document 4). In Example 1, water, sodium hydroxide and anhydrous MA are initially charged, AA is added for 0 to 120 minutes, hydrogen peroxide is added for 0 to 50 minutes, sodium persulfate is added dropwise for 50 to 130 minutes, and water is added for 50 to 50 minutes. It is disclosed that (AA / maleic acid (MA) copolymer: Mw = 9,000) was obtained by a production method of spraying for 130 minutes. Moreover, in Example 2, 3, the manufacturing method which starts spraying water simultaneously with AA dripping start is disclosed. However, there has been room for contrivance as a method for obtaining a copolymer with good productivity that can be suitably used in various industrial fields.

Japanese Patent Laid-Open No. 11-263892 (pages 2, 5, 6) JP 2000-7734 A (page 8) Japanese Patent Laid-Open No. 11-263814 (page 5) Japanese Patent No. 3574597 (page 1-2)

The present invention has been made in view of the above situation, and a method for producing a high-quality (meth) acrylic acid copolymer excellent in various performances and a (meth) acrylic acid copolymer excellent in productivity. Is intended to provide.

As a result of various studies on (meth) acrylic acid-based copolymers, the present inventors have found that a (meth) acrylic acid-based monomer and a structural unit derived from a specific monomer are composed of the copolymer. As a unit, the weight average molecular weight can be increased, the molecular weight distribution can be narrowed, the residual monomer can be decreased, and a copolymer excellent in various performances can be obtained. I found it. Also, by making the addition method of (meth) acrylic acid monomer and dilution water specific, a part of highly reactive monomer such as acrylic acid is polymerized alone on the wall of the reaction vessel ( It has also been found that adhesion to the wall surface due to gelation can be suppressed. Furthermore, by adding an initiator by a specific method, it is possible to reduce the residue of monomers with low polymerization reactivity, and to find that production can be efficiently performed in a short time, and to solve the above-mentioned problems brilliantly. I came up with what I can do. Furthermore, in various industrial fields, it has been found that it can be used as, for example, a scale inhibitor, a detergent additive, and the like, and the present invention has been achieved.

According to the production method of the present invention, a copolymer having excellent basic performance, which could not be obtained by the conventional production method of (meth) acrylic acid monomers, can be produced with high productivity. That is, in the present invention, since allyl monomers and the like have low polymerization reactivity, copolymerization with monomers having high polymerization reactivity such as acrylic acid is performed as a technique for obtaining a high molecular weight polymer. . In the method of initially charging the entire amount of the conventional (meth) acrylic acid monomer and the method without adding dilution water, when the monomer concentration is increased in order to increase the molecular weight of the copolymer to be obtained, High-reactivity (meth) acrylic monomers are preferentially polymerized in the latter half of the polymerization reaction when the viscosity increases as a high-molecular-weight copolymer is produced, resulting in a large amount of low-reactivity monomers. Since it remains, the resulting copolymer has a large amount of residual monomer and a large molecular weight distribution. Further, when the addition of diluting water is started early, the viscosity of the polymerization system is low and the monomer concentration in the polymerization system is lowered, so that a high molecular weight copolymer cannot be obtained. However, in the present invention, a highly reactive (meth) acrylic acid-based monomer does not adhere as a gel even when polymerized at a high solid content concentration, the weight average molecular weight is high, the molecular weight distribution is narrow, and the residual monomer Can be produced with high productivity.

That is, the following general formula (1);

(In the formula, R ¹ represents a hydrogen atom or a methyl group. X represents a hydrogen atom, a metal atom, an ammonium group, or an organic amine group.) Structural unit (a) and the following general formula (2);

(In the formula, R ² , R ³ and R ⁴ are the same or different and each represents a hydrogen atom or a methyl group. R ⁵ represents —CH ₂ —, —CH ₂ —CH ₂ —, —CH ₂ —O—. CH ₂ —, —CH═CH— or —CCH ₃ ═CH—, Y represents —SO ₃ M, —CHR ⁶ —CH ₂ R ⁷ , —OH or —O (AO) _n R ⁸ . M represents a hydrogen atom, a metal atom, an ammonium group, or an organic amine group, and R ⁶ and R ⁷ are the same or different and represent —OH, —SO ₃ M, —N (CH ₂ —COOM) ₂ , —N (CH ₂ CH ₂ OH) ₂ represents AO represents one or more oxyalkylene groups having 2 to 4 carbon atoms, n is the average number of moles of oxyalkylene, 300 is an integer of .R ⁸ is a hydrogen atom or a hydrocarbon of 1 to 30 carbon atoms And a copolymer having a structural unit (b) derived from an unsaturated monomer represented by the formula (1), wherein the copolymer has a weight average molecular weight (Mw) of 60,000 to 1,000,000. The copolymer is a copolymer having a value determined by the formula (mol%) × (Mw) of the structural unit (b) of 1 million or more and a molecular weight distribution (Mw / Mn) of less than 25.
The present invention is described in detail below.

The present invention has the structural unit (a) and the structural unit (b), and is obtained by the formula (i) weight average molecular weight (Mw), (ii) (mol%) of the structural unit (b) × (Mw). (Iii) a copolymer having a molecular weight distribution (Mw / Mn) in a specific range (hereinafter also referred to as copolymer (1)).
The structural unit (a) constituting the copolymer (1) includes (meth) acrylic acid in which X is a hydrogen atom in the general formula (1); (meth) acrylic acid salt in which X is a metal atom or the like 1 type or 2 types or more of these etc. are suitable.

When the structural unit (a) is in the form of a salt, X in the general formula (1) represents a metal atom, an ammonium group, or an organic amine group. As said metal atom, 1 type, or 2 or more types, such as alkali metal atoms, such as a lithium atom, a sodium atom, and a potassium atom; Alkaline earth metal atoms, such as a calcium atom and a magnesium atom, are suitable. As the organic ammonium group (organic amine group), an alkanolamine group such as an ethanolamine group, a diethanolamine group, or a triethanolamine group, or a triethylamine group is preferable. Among these, the form of sodium salt is preferable.
As said monomer (a), acrylic acid and sodium acrylate are preferable and acrylic acid is more preferable.

The structural unit (b) is one or more derived from an unsaturated monomer represented by the general formula (2) (hereinafter also referred to as monomer (b)), R ^{2 to} R ⁸ , Y, M, AO and n in the above general formula (2) represent the above-mentioned ones.
As the ^R 2, ^{R 3} and ^{R 4,} preferably R ^2, R 3, all ^{R 4} are hydrogen ^atoms, R 2, ^{R 3} is ^{R 4} a hydrogen atom is a methyl ^{group, R} 2, R ³ and R ⁴ are more preferably hydrogen atoms.
R ⁵ is preferably —CH ₂ —O—CH ₂ —, —C (CH ₃ ) ═CH—, and more preferably —CH ₂ —O—CH ₂ —.
R ⁶ and R ⁷ are the same or different and are preferably —OH or —SO ₃ M, and more preferably R ⁶ is —OH and R ⁷ is —SO ₃ M. As M, a sodium atom and a potassium atom are preferable, and a sodium atom is more preferable.

Y is preferably —SO ₃ M or —CHR ⁶ —CH ₂ R ⁷ , and more preferably —CHR ⁶ —CH ₂ R ⁷ .
As said M, the thing similar to what was illustrated in X of the general formula (1) mentioned above is suitable. Among these, a sodium atom and a potassium atom are preferable, and a sodium atom is more preferable.
As said AO, an oxyethylene group and an oxypropylene group are preferable. More preferably, it is an oxyethylene group. As said n, 3-100 are preferable, More preferably, it is 5-50.
The hydrocarbon group having 1 to 30 carbon atoms of R ⁸ is preferably an alkyl group such as a methyl group or an ethyl group, or an aryl group such as a phenyl group. Preferred are a methyl group, an ethyl group, and a phenyl group, and more preferred are a methyl group and a phenyl group.

The copolymer (1) has (i) a weight average molecular weight (Mw) of 60,000 to 1,000,000. When Mw is less than 60,000, as a result of decreasing chelating power, for example, there is a possibility that a sufficient effect may not be obtained when used as a scale inhibitor or a detergent additive. As a result of a decrease in the dispersion force, for example, there is a possibility that a sufficient effect cannot be obtained when used as a scale inhibitor or a detergent additive. As Mw, 80,000-500,000 are preferable, More preferably, it is 90-300,000.
The measurement conditions for Mw are as follows.

Measuring method of weight average molecular weight (Mw) (1) It was measured by GPC (gel permeation chromatography). The column used for the measurement was GF-7MHQ (manufactured by Showa Denko KK), and the mobile phase was 34.5 g of disodium hydrogen phosphate dodecahydrate and 46.2 g of sodium dihydrogen phosphate dihydrate (any In addition, pure water was added to make a total amount of 5000 g, and an aqueous solution filtered through a 0.45 micron membrane filter was used.

(2) The pump uses L-7110 (manufactured by Hitachi, Ltd.), the mobile phase flow rate is set to 0.5 ml / min, and the detector is UV (L-2400, manufactured by Hitachi, Ltd.). The wavelength was 214 nm. At that time, the column temperature was kept constant at 35 ° C.
(3) Further, as a calibration curve, a sodium polyacrylate standard sample (manufactured by Sowa Kagaku Co., Ltd.) was used.
(4) A sample was diluted with a mobile phase solvent to prepare a 0.1% by mass sample solution.
(5) As analysis software, sic480II (manufactured by Showa Denko KK) was used. By these, the weight average molecular weight of the copolymer was measured.

In the copolymer (1), the value obtained by the formula (ii) (mol%) × (Mw) of the structural unit (b) is 1 million or more. By setting it as such a range, it can be set as the copolymer with a high ratio of a structural unit (b), and a high molecular weight, for example, when using as a scale inhibitor, the outstanding effect can be exhibited. . Preferably, it is 1.5 million or more, more preferably 2 million or more.

The copolymer (1) has (iii) a molecular weight distribution (Mw / Mn) of less than 25. When the molecular weight distribution is less than 25, high basic quality can be exhibited when used in various applications such as scale inhibitors and detergent additives. Preferably it is less than 24, more preferably less than 23.

In the copolymer (1), the proportion of the structural unit (a) and the structural unit (b) is 70 to 90 mol% of the structural unit (a) and 10 to 30 mol% of the structural unit (b). preferable.
Thus, the structural unit (a) derived from the (meth) acrylic acid monomer represented by the general formula (1) and the unsaturated monomer represented by the general formula (2) A copolymer having a structural unit (b), wherein the copolymer has a proportion of the structural unit (a) to the structural unit (b) of 70 to 95 mol%, b) 5 to 30 mol%, the weight average molecular weight (Mw) is 60,000 to 1,000,000, and the value obtained by the formula of (mol%) × (Mw) of the structural unit (b) is 1,000,000. A copolymer having a molecular weight distribution (Mw / Mn) of less than 25 is also a preferred embodiment of the present invention.
The proportion is preferably 72 to 88 mol% of the structural unit (a) and 12 to 28 mol% of the structural unit (b), more preferably 74 to 86 mol% of the structural unit (a) and (b) of the structural unit. 14 to 26 mol%. In addition, the said ratio is a thing when it is set as (a) + (b) = 100 mol%, and a copolymer (1) contains structural units other than a structural unit (a) and a structural unit (b). May be.

The monomer constituting the other structural unit (other monomer (1)) may be any monomer that can be copolymerized with the monomer (a) and the monomer (b). For example, vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; α-olefins such as ethylene and propylene; and halogen-containing α, β-nots such as vinyl chloride, vinylidene chloride and vinyl fluoride Saturated aliphatic hydrocarbons; α, β-unsaturated aromatic hydrocarbons such as styrene, α-methylstyrene, sodium styrenesulfonate, acrylonitrile; N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide, N- N-vinyl simple substances such as vinyl-N-methylformamide, N-vinyl-N-methylacetamide, N-vinyloxazoline Amide monomers such as (meth) acrylamide, N, N-dimethylacrylamide, N-isopropylacrylamide; unsaturated dicarboxylic acids such as itaconic acid, fumaric acid, maleic acid, citraconic acid, salts thereof and the like Acid anhydride; (meth) acrylic such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate One type or two or more types such as acid ester monomers are preferred.
As a content rate of the said other structural unit, it is suitable that it is 0-20 mol% in all the structural units. Preferably, it is 0-10 mol%, More preferably, it is 0 mol%.

The present invention is also derived from the structural unit (a) derived from the (meth) acrylic acid monomer represented by the general formula (1) and the unsaturated monomer represented by the general formula (2). The copolymer has a weight average molecular weight (Mw) of 60,000 to 1,000,000, and (mol%) of the structural unit (b) × (Mw). ) Is a copolymer which is 1 million or more and the residual monomer is less than 2% by mass with respect to 100% by mass of the solid content. That is, the copolymer has a structural unit (a) and a structural unit (b), and (i) weight average molecular weight (Mw), (ii) (mol%) of the structural unit (b) × (Mw) (Iv) a copolymer having a residual monomer in a specific range (hereinafter also referred to as copolymer (2)).

The structural unit (a) and structural unit (b), (i) weight average molecular weight (Mw) and (ii) (mol%) of the structural unit (b) × (Mw) About the value calculated | required by (1), it is suitable that it is the range mentioned above in the copolymer (1).
In the copolymer (2), (iv) the residual monomer is less than 2% by mass relative to 100% by mass of the solid content. When the residual monomer is 2% by mass or more, for example, when used in a scale inhibitor or a detergent additive, the residual monomer becomes an impurity, which may cause a decrease in cost performance. In some cases, the performance may be adversely affected. Preferably, it is less than 1.5 mass%, More preferably, it is less than 1.0 mass%.

In the copolymer (2), when the copolymer (2) is composed of the structural unit (a) and the structural unit (b), the monomer (a) and the monomer (b) are copolymerized. In this case, a monomer having a slow polymerization rate of the monomer (a) and the monomer (b) remains. Usually, monomer (a) has a higher polymerization rate than monomer (b), so monomer (b) remains. The solid content is obtained as a final solid when the copolymer (2) is produced, and includes a copolymer, a remaining monomer, and other components. As a method for measuring the solid content, for example, all or a part of the polymerization solution at the time when the polymerization reaction is completed is dried at 120 ° C. for 2 hours, the evaporation residue is measured, and obtained from the following formula (1). be able to.
Solid content (%) = [Evaporation residue after drying (g) / Mass of polymerization solution before drying (g)] × 100 (Formula 1)
The time point when the polymerization reaction is completed may be, for example, after completion of the dropping of each component described above, or more specifically, after the completion of the dropping of each component described above, the reaction solution is further added for 30 minutes. May be maintained (aged) at the temperature at the time of dropping each component.

In the copolymer (2), the proportion of the structural unit (a) and the structural unit (b) is preferably in the same range as the proportion exemplified in the copolymer (1). Thus, the structural unit (a) derived from the (meth) acrylic acid monomer represented by the general formula (1) and the unsaturated monomer represented by the general formula (2) A copolymer having a structural unit (b), wherein the copolymer has a proportion of the structural unit (a) to the structural unit (b) of 70 to 95 mol%, b) 5 to 30 mol%, the weight average molecular weight (Mw) is 60,000 to 1,000,000, and the value obtained by the formula of (mol%) × (Mw) of the structural unit (b) is 1,000,000. A copolymer in which the residual monomer is less than 2% by mass with respect to 100% by mass of the solid content is also one of the preferred embodiments of the present invention.

The copolymer (1) or (2) is not particularly limited as long as it has the structural unit (a) and the structural unit (b) in the range described above, but Y in the general formula (2) is − SO ₃ M, or ^a -CHR 6 _-CH 2 ^{R 7,} is preferably one of ^{R 6} and ^{R 7} are -SO ₃ M. More preferably, it is —CHR ⁶ —CH ₂ R ⁷ , and any one of R ⁶ and R ⁷ is —SO ₃ M, more preferably —CHR ⁶ —CH ₂ R ⁷ , R ^This is the case where ⁶ is —OH and R ⁷ is —SO ₃ M.

In the copolymer (1) or (2), as the combination of Y and R ^{5 in} the general formula (2), Y is —CHR ⁶ —CH ₂ R ⁷ , R ⁶ is —OH and R It is preferable that ⁷ is —SO ₃ M, that is, Y is —CH (OH) —CH ₂ SO ₃ M, and R ⁵ is —CH ₂ —O—CH ₂ —. That is, the unsaturated monomer (monomer (b)) constituting the structural unit (b) is preferably sodium 3-allyloxy-2-hydroxypropanesulfonate (HAPS). By using HAPS, a sulfonic acid group and a hydroxyl group can be simultaneously introduced into the copolymer molecule, and, for example, an excellent effect can be exhibited when used as a scale inhibitor or a detergent additive. There are advantages.

The copolymers (1) and (2) are not particularly limited as long as they satisfy the above-described requirements. The combination of the monomer (a) and the monomer (b) Although it can select suitably from a monomer (a) and a monomer (b), it is preferable that they are a combination of acrylic acid and HAPS, a sodium acrylate, and a combination of HAPS, and a combination of acrylic acid and HAPS Is more preferable. That is, as said copolymer (1) and (2), following formula (3);

(In the formula, m and n are integers representing the number of repeating structural units.) The structural unit is preferably represented.
The structural unit represented by the above formula (3) is preferably 80% by mass or more, more preferably 90% by mass or more, and 100% by mass or more with respect to 100% by mass of the copolymer. More preferably it is.

In the present invention, the structural unit derived from the (meth) acrylic acid monomer represented by the general formula (1) and the polymerization rate of homopolymerization are slower than those of the (meth) acrylic monomer. A method for producing a copolymer having a monomer-derived constitutional unit and having a weight average molecular weight (Mw) of 60,000 to 1,000,000, wherein the production method comprises a (meth) acrylic acid-based monomer The step of sequentially adding 50% by mass or more of the total use amount of the body to the polymerization solution, and adding dilution water to the polymerization solution after 45% of the total sequential addition time of the (meth) acrylic acid monomer It is also a method for producing a copolymer. Hereinafter, it is also referred to as manufacturing method (1).

The copolymer is a single unit having a lower rate of homopolymerization than a structural unit derived from a (meth) acrylic acid monomer (also referred to as a structural unit (a)) and the (meth) acrylic acid monomer. It has a structural unit derived from a monomer (hereinafter also referred to as a structural unit (c)), and the structural unit (a) is preferably composed of the monomer (a) described above. .
As said structural unit (c), it originates in the monomer (henceforth a monomer (c)) whose polymerization rate of homopolymerization is slower than the monomer (a) which comprises a structural unit (a). It is preferable that The monomer (c) is preferably a monomer having a slower rate of homopolymerization than the monomer (a) (for example, radical polymerization reactivity is low due to radical stability or steric hindrance). Monomers that do not polymerize are also included.

As said monomer (c), 1 type (s) or 2 or more types, such as the above-mentioned monomer (b) and other monomers (other monomer (2)) other than these, are suitable, for example. is there.
As said other monomer (2), itaconic acid, maleic acid, fumaric acid, citraconic acid, these salts, these acid anhydrides, etc. are suitable. In addition, when the said monomer (2) is a salt form, about a suitable example etc., it is the same as that of the above-mentioned.

The monomer (c) is more preferably a monomer (b) or maleic acid, and more preferably a monomer (b). Preferred monomers (b) when the monomer (c) is the monomer (b), and preferred combinations of the monomer (a) and the monomer (b) are as described above. .

The proportions of the structural unit (a) and the structural unit (c) of the copolymer are preferably 50 to 90 mol% of the structural unit (a) and 10 to 50 mol% of the structural unit (c). When the structural unit (c) is less than 10 mol%, excellent properties as a copolymer are not exhibited, and when the structural unit (c) exceeds 50 mol%, the ratio of the monomer having poor polymerization reactivity. Is too large to obtain a high molecular weight copolymer. More preferably, they are 60-85 mol% of structural units (a), 15-40 mol% of structural units (c), More preferably, 70-80 mol% of structural units (a), 20-20 of structural units (c) 30 mol%.
In the copolymer, the weight average molecular weight (Mw) is as described above for the copolymer (1).

In the method for producing the copolymer, it is preferable that 50% by mass or more of the total amount of the (meth) acrylic acid monomer is sequentially added to the polymerization solution. By sequentially adding 50% by mass or more to the polymerization solution, a suitable copolymer can be obtained without polymerizing only the (meth) acrylic acid monomer (monomer (a)) having a high polymerization rate of homopolymerization. Can be obtained. The amount to be added sequentially is preferably 60% by mass or more, more preferably 80% by mass or more in the monomer (a), and most preferably the whole amount is added sequentially. In addition, when not adding the whole quantity of monomer (a) sequentially, it is preferable to prepare the monomer (a) which is not added sequentially in a reaction container previously.

As the method for adding the monomer (a), dripping, spraying, submerged feed provided with a charging port in the polymerization solution, etc. can be suitably used. From the viewpoint of the above, it is preferable to add by dropping.
The addition rate of the monomer (a) can be appropriately set depending on the scale of production equipment, etc., may be changed during the addition time, may be constant, but is suitable for a narrow molecular weight distribution. In order to obtain a polymer, the addition rate is preferably constant.
The addition time of the monomer (a) can be appropriately set depending on the reaction conditions. For example, the addition time of the monomer (a) is 30 to 300 minutes on the basis of the time when the addition of the monomer (a) is started. preferable. More preferably, it is 45-180 minutes, More preferably, it is 60-120 minutes.

In the above production method, it is preferable to add dilution water to the polymerization solution after 45% of the total sequential addition time of the (meth) acrylic acid monomer. By adding dilution water in this way, the viscosity of the polymerization reaction is increased in the latter half of the polymerization reaction, where the viscosity increases with the formation of a high molecular weight copolymer, and the movement of the polymerization solution is restricted to produce a gelled product. It is possible to increase the rising speed of the liquid surface of the polymerization system near the polymerization vessel wall. For this reason, it is possible to effectively suppress the adhesion of the gelled product to the production apparatus that may not be sufficiently suppressed only by stirring the polymerization solution.

The addition time of the dilution water is more preferably after 50% of the total sequential addition time of the monomer (a), and more preferably after 55%.
The addition amount of the dilution water is preferably 5% by mass or more and more preferably 10% by mass or more with respect to the total amount of polymerization. As said dilution water, ion-exchange water, distilled water, etc. are suitable.
The dilution water addition method is the same as the monomer (a) addition method described above.

In the above production method, it is preferable to stir the polymerization solution in addition to the addition of dilution water. By stirring the polymerization solution, it is possible to prevent the polymer from adhering to the wall of the reaction vessel, and the adhesion of the gelled product to the production apparatus is suppressed.
As the stirring device, a motor drive type represented by a stirring blade, a surface drive type represented by a shaker or the like, a jet collision type, an ultrasonic dispersion type, a motionless mixer, or the like can be used. Among them, it is preferable to use a stirring blade from the viewpoint of initial investment of equipment and ease of maintenance. The stirring speed can be set as appropriate depending on the scale of the apparatus. Stirring can be performed temporarily or continuously, but it is preferable that the stirring is continuously performed during the reaction time from the viewpoint of suppressing the adhesion of the gelled product and promoting the reaction.

As described above, the structural unit (a) derived from the (meth) acrylic acid monomer represented by the general formula (1) and the polymerization of homopolymerization than the (meth) acrylic acid monomer. It has a structural unit (c) derived from a monomer having a low speed, and the proportion of the structural unit (a) to the structural unit (c) is 50 to 90 mol% of the structural unit (a) and the structural unit (c) 10 Is a method for producing a copolymer having a weight average molecular weight (Mw) of 60,000 to 1,000,000, wherein the production method comprises all use of a (meth) acrylic monomer A copolymer comprising a step of sequentially adding 50% by mass or more of the amount to the polymerization solution and adding dilution water to the polymerization solution after 45% of the total sequential addition time of the (meth) acrylic monomer This manufacturing method is also one of the preferred embodiments of the present invention.

The production method of the present invention preferably includes a step of adding an initiator and dilution water to the polymerization solution. The initiator may be charged in the reaction vessel in advance, but it is preferable to sequentially add to the polymerization solution during the reaction process. As the sequential addition amount, among the initiators used, 60% by mass or more is preferable, 80% by mass or more is more preferable, and it is most preferable to add the entire amount sequentially. The method for adding the initiator is the same as the method for adding the monomer (a) described above.

As the addition rate of the initiator, the addition rate of the initiator after the lapse of 15 minutes of the dilution water addition start time is defined as 1. on the basis of the addition rate of the initiator 15 minutes before the dilution water addition start time. It is preferable to use 5 to 5 times. By changing the addition rate in this way, it is possible to reduce the remaining monomer (monomer (c)) having low polymerization reactivity. The addition rate of the initiator after 15 minutes of the dilution water addition start time is preferably 1.5 to 5 times, more preferably 2 to 4.5 times, and even more preferably 2.5 to 4 times.

The addition time of the dilution water is the same as that described above when the monomer (a) is added sequentially. When the monomer (a) is not added sequentially, the time when the monomer (a), the monomer (c) and the initiator are initially charged in the reaction vessel is defined as “at the start of the reaction”. When the point at which the remaining amount of the body does not decrease is “at the end of reaction”, it is preferable to add dilution water after 45% of the total reaction time from “at the start of reaction” to “at the end of reaction”, More preferably, it is after 50% has elapsed.
The dilution water is the same as described above.

The initiator is not particularly limited, and examples thereof include 2,2′-azobis (2-aminopropane) hydrochloride and 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) -propionamide]. 1 type, or 2 or more types, such as peroxides, such as hydrogen peroxide and tert- butylhydroxy peroxide, can be used. Among these, it is preferable to use a persulfate such as sodium persulfate, potassium persulfate, or ammonium persulfate from the viewpoint of improving the polymerization rate and reducing the amount of residual monomer.
It does not specifically limit as the usage-amount of the said polymerization initiator, For example, it is suitable that a minimum is 0.001 mass% and an upper limit is 10 mass% with respect to 100 mass% of all the monomer components.

The structural unit derived from the (meth) acrylic acid monomer represented by the general formula (1), and the monomer derived from a monomer having a slower polymerization rate than the (meth) acrylic acid monomer. A method for producing a copolymer having a structural unit and having a weight average molecular weight (Mw) of 60,000 to 1,000,000, wherein the production method comprises adding an initiator and dilution water to a polymerization solution. And the addition rate of the initiator after 15 minutes of the dilution water addition start time is increased 1.5 to 5 times based on the addition rate of the initiator at the time 15 minutes before the dilution water addition start time A method for producing a copolymer is also one aspect of the present invention. Hereinafter, it is also referred to as manufacturing method (2).

In the production method (2), the constitutional unit derived from the (meth) acrylic acid monomer and the monomer derived from a monomer having a slower polymerization rate than the (meth) acrylic acid monomer. The ratio with the unit (c) is preferably in the same range as the ratio exemplified in the production method (1). Thus, the structural unit (a) derived from the (meth) acrylic acid monomer represented by the general formula (1) and the polymerization rate of homopolymerization than the above (meth) acrylic acid monomer are higher. It has a structural unit (c) derived from a slow monomer, and the proportion of the structural unit (a) to the structural unit (c) is 50 to 90 mol% of the structural unit (a) and 10 to 50 structural unit (c). It is a method for producing a copolymer having a mol% and a weight average molecular weight (Mw) of 60,000 to 1,000,000, wherein the production method comprises a step of adding an initiator and dilution water to a polymerization solution. In addition, the initiator addition rate after 15 minutes of the dilution water addition start time is 1.5 to 5 times based on the initiator addition rate 15 minutes before the dilution water addition start time. A method for producing a polymer is also one of the preferred embodiments of the present invention.

Production methods (1) and (2) of the present invention can be carried out independently, but a form in which both are carried out is more preferred. By carrying out both, the monomer (a) is added sequentially, dilution water is added from the latter half of the polymerization, and the initiator dropping rate is increased, so that the gelled product adheres to the production apparatus in a short time. Copolymer having a relatively narrow molecular weight distribution and a small amount of residual monomer, and having excellent basic performance as a scale inhibitor, detergent additive, etc. can do.

In the said manufacturing method (1) and / or (2), it is preferable that solid content concentration in the polymerization solution at the time of superposing | polymerizing reaction is 30 mass% or more. The solid content, the method for measuring the solid content, and the time when the polymerization reaction is completed are the same as described above. The solid content concentration can be determined in the same manner as described above.
When the solid content concentration is less than 30% by mass, when the monomer (c) is an allyl monomer having low polymerization reactivity, the resulting copolymer has a sufficiently high molecular weight. Although it may not be possible, when the solid content concentration is 30% by mass or more, a copolymer having a structural unit derived from an allylic monomer having low polymerization reactivity can be increased in molecular weight. That is, it is possible to produce a higher molecular weight copolymer by increasing the monomer concentration per unit time in the polymerization system. More preferably, it is 34 mass% or more, More preferably, it is 38 mass% or more.

In the said manufacturing method (1) and (2), it can carry out by the method used normally, such as solution polymerization, bulk polymerization, suspension polymerization, emulsion polymerization, etc. as a polymerization method, It does not specifically limit. . However, when the type of the polymer is a water-soluble polymer or when the polymer is adapted to an aqueous polymerization method, the effect of the present invention is most remarkable, and thus solution polymerization is preferable.
The solvent for the copolymerization reaction is not particularly limited. For example, it is preferable to use water or a lower alcohol having 1 to 4 carbon atoms such as isopropyl alcohol. These may be a single solvent or a mixed solvent. There may be. Especially, it is more suitable to use water for a solvent at the point which can skip a solvent removal process.

The production of the polymer is generally carried out with an aqueous solvent at a high temperature, preferably in the vicinity of the boiling point, from the viewpoints of safety and economy. Therefore, the deterioration of the heat removal capability immediately causes severe foaming, that is, a severe boiling state, the stirring effect is lost, and eventually the reaction liquid overflows from the polymerization vessel, making it impossible to continue the polymerization itself. Cause a problem to say. In recent years, there has been a tendency to increase the raw material concentration in order to increase production efficiency, and it has become more likely to cause severe foaming, that is, intense boiling. In this invention, since it consists of the above-mentioned structure, a copolymer can be manufactured suitably, without producing these problems.

In the said copolymerization reaction, although it does not specifically limit as reaction temperature in the case of copolymerization, For example, it is suitable to set it as 50-150 degreeC. If it is less than 50 ° C, the copolymerization reactivity may not be sufficient, and unreacted monomers may not be sufficiently reduced. If it exceeds 150 ° C, side reactions are sufficiently suppressed. There is a possibility that reaction control cannot be simplified. More preferably, it is 70-120 degreeC, Most preferably, it is 80-110 degreeC. In addition, the said copolymerization reaction may be performed in inert gas atmosphere, such as nitrogen and argon, and may be performed in air | atmosphere. In addition, the pH of the polymerization solution is not particularly limited, but for example, it is preferable to perform the polymerization under a condition of less than pH 5. When the pH is less than 5, the polymerization reactivity of the monomer (a) is improved, and a higher molecular weight copolymer is easily obtained. More preferably, the pH is less than 4.5.

As a preferred embodiment in the production method of the present invention, (1) a monomer having a slow homopolymerization rate (monomer (c)) constituting a polymerization solvent such as water or the structural unit (c) as necessary. Step of charging into reaction vessel as initial charge, (2) (meth) acrylic acid monomer (monomer (a)), initiator, and if necessary, monomer (c) is added sequentially Embodiment which performs operation in order of the process to perform, (3) The process of adding dilution water, (4) The process of increasing the addition rate of an initiator is mentioned.
The addition rate of the monomer (a) and the like in the step (2), the addition rate of water in the step (3), the start point of addition, and the rise time of the addition rate of the initiator in the step (4) The above-described ones are preferable.

The present invention is also a scale inhibitor or a detergent additive comprising the above copolymer. As such a copolymer, what is necessary is just to contain at least one of the above-mentioned copolymers (1) and (2), and as content, it can set suitably according to a use. .

The (meth) acrylic acid copolymer of the present invention and the method for producing the same are one of useful industrial raw materials that have the above-described configuration and can be used as scale inhibitors, detergent additives, and the like (meta). ) A method for producing an acrylic acid copolymer and a (meth) acrylic copolymer excellent in productivity.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples. Unless otherwise specified, “part” means “part by weight” and “%” means “mass%”.

Example 1
A SUS reaction vessel having a capacity of 25 L equipped with a reflux condenser and a stirrer was charged with 6024 g of a 40% by mass aqueous sodium 3-allyloxy-2-hydroxypropanesulfonate (hereinafter abbreviated as 40% HAPS) under stirring. The temperature was raised to the boiling point reflux state. Next, in a polymerization reaction system under a boiling point reflux state with stirring, 5670 g of an 80% by mass acrylic acid aqueous solution (hereinafter abbreviated as 80% AA) and 40% HAPS: 6024 g, a 15% by mass sodium persulfate aqueous solution (hereinafter, 15% NaPS). 2128 g (corresponding to 3.8 g with respect to 1 mol of the monomer in the monomer component) was added dropwise. 80% AA was added dropwise at a constant rate from 0 minutes to 90 minutes and 40% HAPS was added from 0 minutes to 60 minutes, with the time point at which addition of 80% AA was started as a reference (0 minutes). 15% NaPS, which is an initiator, was dropped at an addition rate of 9.7 g / min, the addition rate was changed to 39.1 g / min, which was tripled at 55 minutes, and dropped from 0 to 110 minutes. Next, 4940 g of deionized water (diluted water) was added dropwise at a constant rate for 50 minutes to 90 minutes. The solution was dropped from separate nozzles, and the reaction solution was kept at the boiling point reflux state with stirring. In addition, the dripping of water was started from the time of 56% lapse with respect to the dripping time of 80% AA.

After completion of the dropwise addition of 15% NaPS, the reaction solution was kept (ripened) at the boiling point reflux for 30 minutes to complete the polymerization. When the polymerization reaction was completed (140 minutes after starting the addition of 80% AA), no gel adhered to the reaction vessel, and the solid content concentration in the polymerization solution was 40% by mass. The residual monomer (residual HAPS) was 0.9% by mass with respect to 100% by mass of the solid content. The obtained copolymer (copolymer (A)) had a weight average molecular weight of 95,000 and a molecular weight distribution of 21.9.

Comparative Example 1
In a 25 L SUS reaction vessel equipped with a reflux condenser and a stirrer, 8372 g of acid type 40 mass% sodium 3-allyloxy-2-hydroxypropanesulfonate (hereinafter abbreviated as acid type 40% HAPS) 8372 g, 80% AA: 4662 g, 35 mass% hydrogen peroxide (hereinafter abbreviated as 35% HP) 980 g as an initiator, and ion exchange water: 10360 g were charged, and the temperature was raised to a boiling point reflux state with stirring. Subsequently, it was polymerized at the boiling point reflux condition for 4 hours.
After 4 hours, gel adhesion was observed in the reaction vessel, and the solid content concentration in the polymerization solution was 30% by mass. The residual monomer (residual HAPS) was 15% by mass relative to 100% by mass of the solid content. The weight average molecular weight of the obtained copolymer (copolymer (B)) was 102000, and the molecular weight distribution was 35.1.

Comparative Example 2
The same procedure as in Example 1 was performed except that no water was dropped. Gel adhesion was observed in the reaction vessel 70 minutes after the start of dropping of 80% AA, and the solid content concentration in the polymerization solution was 50% by mass. The residual monomer (residual HAPS) was 2.4% by mass relative to 100% by mass of the solid content. The weight average molecular weight of the obtained copolymer (copolymer (C)) was 128000, and the molecular weight distribution was 30.6.

(Scale suppression ability)
The scale inhibiting ability of the copolymers (A) to (C) obtained in Example 1 and Comparative Examples 1 and 2 was evaluated by the following method.
[Scale inhibition test]
Silica concentration = 210 mg / L (SiO ₂ equivalent, adjusted with sodium metasilicate · 9 hydrate), magnesium concentration = 200 mg / L (CaCO ₃ equivalent, magnesium sulfate · 7 hydrate) in a polypropylene container with an internal volume of 250 ml ), M alkalinity = 500 mg / L (CaCO ₃ conversion, adjusted with sodium hydrogen carbonate) test water and a copolymer so that the added concentration is 100 mg / L in terms of solid content, and pH 8. 5. The total amount was adjusted to 200 ml. This solution was sealed in a polypropylene container having an internal volume of 120 ml that could be sealed so that air was not mixed therein, and was allowed to stand at 60 ° C. for 40 hours. It was filtered through a 0.1μm membrane filter, using a plasma emission spectroscopic analyzer (ICP) (Seiko Instruments Co., Ltd. SPS4000), to quantify the Si concentration of the filtrate, in terms of SiO ₂ concentration Then, the scale inhibition rate (%) was calculated by the following formula.

Scale inhibition rate (%) = {(XY) / (ZY)} × 100
X: SiO ₂ concentration (mg / L) in the filtrate after the test
Y: SiO ₂ concentration (mg / L) in the filtrate tested without addition of polymer
Z: SiO ₂ concentration before testing (mg / L)
The evaluation results are shown in the table below.

Claims (4)

The following general formula (1);

(In the formula, R ¹ represents a hydrogen atom or a methyl group. X represents a hydrogen atom, a metal atom, an ammonium group, or an organic amine group.) Structural unit (a) and the following general formula (2);

(In the formula, R ² , R ³ and R ⁴ are the same or different and each represents a hydrogen atom or a methyl group. R ⁵ represents —CH ₂ —, —CH ₂ —CH ₂ —, —CH ₂ —O—. CH ₂ —, —CH═CH— or —CCH ₃ ═CH—, Y represents —SO ₃ M, —CHR ⁶ —CH ₂ R ⁷ , —OH or —O (AO) _n R ⁸ . M represents a hydrogen atom, a metal atom, an ammonium group, or an organic amine group, and R ⁶ and R ⁷ are the same or different and represent —OH, —SO ₃ M, —N (CH ₂ —COOM) ₂ , —N (CH ₂ CH ₂ OH) ₂ represents AO represents one or more oxyalkylene groups having 2 to 4 carbon atoms, n is the average number of moles of oxyalkylene, 300 is an integer of .R ⁸ is a hydrogen atom or a hydrocarbon of 1 to 30 carbon atoms A copolymer having a representative.) Represented by an unsaturated monomer-derived constituent units (b),
The copolymer is
The weight average molecular weight (Mw) is 60,000 to 1,000,000,
The value determined by the formula (mol%) × (Mw) of the structural unit (b) is 1 million or more,
A copolymer, wherein the residual monomer is less than 2% by mass with respect to 100% by mass of the solid content. The following general formula (1);

(In the formula, R ¹ represents a hydrogen atom or a methyl group. X represents a hydrogen atom, a metal atom, an ammonium group, or an organic amine group.) It has a structural unit and a structural unit derived from a monomer having a slower polymerization rate of homopolymerization than the (meth) acrylic acid monomer, and has a weight average molecular weight (Mw) of 60,000 to 1,000,000. A method for producing a copolymer comprising:
In the production method, 50% by mass or more of the total amount of (meth) acrylic acid monomer used is sequentially added to the polymerization solution, and 45% of the total sequential addition time of (meth) acrylic acid monomer has elapsed. A method for producing a copolymer, comprising a step of adding dilution water to the polymerization solution after the time point. The following general formula (1);

(In the formula, R ¹ represents a hydrogen atom or a methyl group. X represents a hydrogen atom, a metal atom, an ammonium group, or an organic amine group.) It has a structural unit and a structural unit derived from a monomer having a slower polymerization rate of homopolymerization than the (meth) acrylic acid monomer, and has a weight average molecular weight (Mw) of 60,000 to 1,000,000. A method for producing a copolymer comprising:
The production method includes a step of adding an initiator and dilution water to a polymerization solution,
The addition rate of the initiator after 15 minutes of the dilution water addition start time is 1.5 to 5 times based on the addition rate of the initiator at the time 15 minutes before the dilution water addition start time. A method for producing a copolymer. The said manufacturing method is a manufacturing method of the copolymer of Claim 2 or 3 whose solid content concentration in the polymerization solution at the time of complete | finishing a polymerization reaction is 30 mass% or more.