JP6397633B2 - POLY (METH) ACRYLIC ACID POLYMER AND PROCESS FOR PRODUCING THE SAME - Google Patents

Description

The present invention relates to a poly (meth) acrylic acid polymer and a method for producing the same.

Conventionally, among poly (meth) acrylic acid polymers, those with low molecular weights can be used for detergent builders, dispersants such as inorganic pigments and metal ions, and scale prevention using their excellent chelating ability and dispersibility. It is suitably used for agents.

For example, Patent Document 1 discloses an aqueous solution containing a poly (meth) acrylic acid polymer, wherein at least a part of the carboxyl groups of the poly (meth) acrylic acid polymer is neutralized with an organic amine, The molar ratio of the structure derived from (meth) acrylic acid (salt) and the structure derived from organic amine (salt) contained in the aqueous poly (meth) acrylic acid polymer solution is 100: 10 to 100: 75. And the concentration of the inorganic anion containing a sulfur atom or phosphorus atom contained in the poly (meth) acrylic acid polymer aqueous solution is 1000 to 1000 with respect to the poly (meth) acrylic acid polymer aqueous solution. An aqueous poly (meth) acrylic acid polymer solution characterized by 10,000 ppm is disclosed. The above polymer aqueous solution has excellent dispersibility of inorganic fine particles such as mud stains and inorganic pigments, and can exhibit dispersive power over time, so when used as a detergent builder or pigment dispersant It is disclosed that excellent detergency and stable dispersibility of the pigment over time can be obtained.
Patent Document 1 further discloses that the poly (meth) acrylic acid polymer aqueous solution is an alkali metal salt containing (i) an acid type and / or partially neutralized poly (meth) acrylic acid polymer aqueous solution. It is produced by the essential steps of neutralizing and (ii) neutralizing an aqueous solution containing an acid type and / or partially neutralized poly (meth) acrylic acid polymer with an organic amine. In other words, it is disclosed that the color tone is excellent.

International Publication 2011/126059

As described above, although various poly (meth) acrylic acid polymers (compositions) have been reported, for example, a powder detergent composition containing a large amount of poly (meth) acrylic acid polymers is manufactured. In this case, since the poly (meth) acrylic acid polymer is relatively easily yellowed under an overheating condition, the hue of the detergent composition may be lowered. Therefore, the blending amount of the poly (meth) acrylic acid polymer may not be increased sufficiently.
Therefore, an object of the present invention is to provide a poly (meth) acrylic acid polymer having better hue stability during heating as compared with conventional poly (meth) acrylic acid polymers.

As a result of intensive studies on various poly (meth) acrylic acid polymers to achieve the above object, the present inventors have found that poly (meth) acrylic acid polymers having a specific structure have excellent heating. It was found that the hue stability at the time was exhibited, and the present invention was completed based on the findings.
That is, the present invention relates to a poly (meth) acrylic acid polymer, wherein 1 to 45 mol% of the carboxyl groups of the poly (meth) acrylic acid polymer are neutralized with an organic amine. The (meth) acrylic acid polymer has at least one main chain terminal, a sulfonic acid (salt) group, a hypophosphorous acid (salt) group, an —S—R ₀ —COOM group (where R ₀ is the number of carbon atoms) A poly (meth) acrylic acid polymer having one or more groups selected from the group consisting of 1 to 5 alkylene groups, and M represents a hydrogen atom, a metal atom, an ammonium salt, or an organic amine salt. It is.

The poly (meth) acrylic acid polymer of the present invention has excellent hue stability during heating. Therefore, even if it is a case where it mix | blends with a powder detergent composition, for example, the deterioration of the hue at the time of manufacture of a powder detergent composition can be suppressed. Therefore, for example, it can be usefully used as an additive (particularly a powder detergent builder) of a powder detergent composition.

Hereinafter, the present invention will be described in detail.

[Poly (meth) acrylic acid polymer of the present invention]
The poly (meth) acrylic acid polymer of the present invention (hereinafter also referred to as “polymer of the present invention”) has a structural unit (a) derived from (meth) acrylic acid (salt). In the present invention, (meth) acrylic acid (salt) refers to methacrylic acid (salt) or acrylic acid (salt). Methacrylic acid (salt) refers to methacrylic acid or methacrylate, and acrylic acid (salt) refers to acrylic acid or acrylate.
The “salt” in (meth) acrylic acid (salt) is a metal salt, an ammonium salt, or an organic amine salt. Examples of the metal salt include alkali metal salts such as sodium salt, lithium salt and potassium salt; alkaline earth metal salts such as magnesium salt and calcium salt; salts such as aluminum and iron. Organic amine salts include monoethanolamine salts, diethanolamine salts, triethanolamine salts and other alkanolamine salts; monoethylamine salts, diethylamine salts, triethylamine salts and other alkylamine salts; ethylenediamine salts, triethylenediamine salts and other polyamines And salts of organic amines such as

  In the polymer of the present invention, the structural unit (a) derived from (meth) acrylic acid (salt) is derived from the structural unit derived from all monomers (the structural unit derived from (meth) acrylic acid (salt) and the other units described later. It is preferably 50 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more with respect to 100 mol% (which means a structural unit derived from a monomer). By being in the above range, the detergent characteristics of the polymer of the present invention tend to be improved, and the hue stability during heating tends to be improved.

The polymer of the present invention is characterized in that 1 to 45 mol% of the carboxyl groups are neutralized with an organic amine. Preferably, it is 1-34 mol%, More preferably, it is 1-12 mol%, More preferably, it is 2-10 mol%. By being neutralized within the above range, the detergent properties of the polymer of the present invention tend to be improved, and the hue stability during heating tends to be improved.
The organic amine is, for example, as exemplified above. However, the organic amine having a boiling point of 80 ° C. or higher is preferable and the organic amine having a temperature of 120 ° C. or higher is preferable because the stability of hue during heating tends to be improved. More preferably, an organic amine of 180 ° C. or higher is further preferable, and an organic amine of 200 ° C. or higher is particularly preferable. Although the upper limit of a boiling point is not specifically limited, For example, it is 400 degreeC.
Further, the organic amine is preferably a secondary amine because the hue stability during heating tends to be improved.
Among the above organic amines, diethanolamine is particularly preferable because the polymer of the present invention has good detergent properties and the hue stability during heating tends to be particularly improved.

Since the polymer of the present invention tends to improve the hue stability during heating, at least one main chain terminal has a sulfonic acid (salt) group, a hypophosphorous acid (salt) group, -S- One or more selected from the group consisting of R ₀ -COOM group (where R ₀ represents an alkylene group having 1 to 5 carbon atoms, and M represents a hydrogen atom, a metal atom, an ammonium salt, or an organic amine salt). It has the following group. Among these, it is particularly preferable to have a sulfonic acid (salt) group and a hypophosphorous acid (salt) group at the end of the main chain.
The “salt” in the sulfonic acid (salt) group and the hypophosphorous acid (salt) group is a metal salt, an ammonium salt, or an organic amine salt. Examples of the metal salt, ammonium salt and organic amine salt are as described above.
The polymer of the present invention has a group selected from the above group at at least one main chain terminal. For example, in the case of a linear polymer, the polymer may have only one terminal, For example, in the case of a branched polymer, it may be present only at one end or at two or more ends.

A polymer having a sulfonic acid (salt) group at the end of the main chain, for example, using a monomer component containing (meth) acrylic acid (salt) as a chain transfer agent, bisulfite (salt) or bisulfite (salt) It can be produced by polymerizing in the presence of a compound that can be generated. Examples of the bisulfite (salt) include sodium bisulfite and potassium bisulfite. The compounds capable of generating the above bisulfite (salt) include sulfite (salt), dithionite (salt), metabisulfite (salt), etc., sodium sulfite, potassium sulfite, sodium dithionite, meta Examples thereof include sodium bisulfite.
The sulfonic acid (salt) group at the end of the main chain can be measured, for example, by ¹ HNMR analysis.

A polymer having a hypophosphorous acid (salt) group at the end of the main chain is obtained by using, for example, a monomer component containing (meth) acrylic acid (salt) as a chain transfer agent and hypophosphorous acid (salt) (Including a hydrate of phosphoric acid (salt)). Examples of hypophosphorous acid (salt) include hypophosphorous acid and sodium hypophosphite.
For example, in the case of a sodium hypophosphite group, the hypophosphorous acid (salt) group at the end of the main chain is represented by -PH (= O) (ONa).
The hypophosphorous acid (salt) group at the end of the main chain can be measured, for example, by ³¹ PNMR analysis.
The —S—R ₀ —COOM group at the end of the main chain (where R ₀ represents an alkylene group having 1 to 5 carbon atoms, M represents a hydrogen atom, a metal atom, an ammonium salt, or an organic amine salt), for example, Presence of a compound containing a mercapto group and a carboxyl group, such as thioglycolic acid (salt) or 3-mercaptopropionic acid (salt), using a monomer component containing (meth) acrylic acid (salt) as a chain transfer agent It can manufacture by polymerizing under.
In the —S—R ₀ —COOM group, R ₀ is more preferably a CH ₂ group or CH ₂ CH ₂ , and M is more preferably a hydrogen atom or an alkali metal atom.
The —S—R ₀ —COOM group at the end of the main chain can be measured, for example, by ¹ HNMR analysis.

  The weight average molecular weight of the polymer of the present invention is 1,000 to 50,000 because the detergent properties of the polymer of the present invention tend to improve and the stability of the hue during heating tends to improve. It is preferable that there is, more preferably 1,000 to 20,000, and particularly preferably 1,000 to 8,000. In addition, in this specification, a weight average molecular weight is a measured value by GPC (gel permeation chromatography), and was measured according to the method described in the Example mentioned later.

The polymer of the present invention has an optional structural unit (e) derived from a monomer other than (meth) acrylic acid (salt) (hereinafter referred to as “other monomer”). Also good. In the polymer of the present invention, the content of the structural unit (e) derived from other monomers is the structural unit derived from all monomers (as described above, the structure derived from (meth) acrylic acid (salt)). It is preferably 0 mol% or more and 50 mol% or less, more preferably 0 mol% or more and 20 mol% or less, relative to 100 mol% (which refers to structural units derived from units and other monomers). Preferably, it is 0 mol% or more and 10 mol% or less. By being in the above range, the detergent characteristics of the polymer of the present invention tend to be improved, and the hue stability during heating tends to be improved.
The structural unit (e) derived from the other monomer is a structure in which at least one carbon-carbon double bond of the other monomer (E) is a single bond.

  Specific examples of the other monomers include unsaturated monocarboxylic acids other than (meth) acrylic acid (salts) such as crotonic acid, α-hydroxyacrylic acid, α-hydroxymethylacrylic acid and salts thereof. Acid (salt); unsaturated dicarboxylic acid (salt) such as itaconic acid, fumaric acid, maleic acid, 2-methyleneglutaric acid, and salts thereof; 3-allyloxy-2-hydroxypropanesulfonic acid, (meth) allylsulfone Sulfonic acid group-containing monomers such as acid, isoprene sulfonic acid, vinyl sulfonic acid, styrene sulfonic acid and salts thereof; monomers obtained by adding alkylene oxide to unsaturated alcohols such as (meth) allyl alcohol and isoprenol; Polyalkylene glycol monomers such as (meth) acrylic acid polyalkylene glycol esters; N-vinyl monomers such as lidone, N-vinylformamide, N-vinyloxazolidone; acrylamide monomers such as (meth) acrylamide, N, N-dimethylacrylamide, N-isopropylacrylamide; butyl (meth) acrylate, (Meth) acrylic acid alkyl ester monomers such as 2-ethylhexyl (meth) acrylate and dodecyl (meth) acrylate; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl ( (Meth) acrylate hydroxyalkyl monomers such as (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, hydroxypentyl (meth) acrylate; vinylpyridine, vinylimi Vinyl aromatic amino group-containing monomers having a heterocyclic aromatic hydrocarbon group and a polymerizable group such as sol, and quaternized products and salts thereof; allylamines such as diallylamine and diallyldimethylamine and quaternary thereof And (ii) epoxy ring of (meth) allyl glycidyl ether, isoprenyl glycidyl ether, vinyl glycidyl ether, (ii) alkylamines such as dimethylamine, diethylamine, diisopropylamine, di-n-butylamine, diethanolamine, di Monomers obtained by reacting amines such as alkanolamines such as isopropanolamine, cyclic amines such as morpholine and pyrrole, and quaternized compounds and salts thereof; vinylaryl units such as styrene, indene and vinylaniline Body, isobutylene, acetic acid Vinyl; and the like. The said other monomer (E) may be used individually by 1 type, and may be used with the form of a 2 or more types of mixture.

The polymer of the present invention has good hue stability during heating.
For example, the polymer of the present invention preferably has a Hunter whiteness (W) of 76 or more, more preferably 80 or more when heated at 200 ° C. for 60 minutes.
Hunter whiteness (W) is calculated by the following equation after measuring L, a, and b with a Hunter colorimetric color difference meter.
W = 100-SQRT ((100-L) ² + a ² + b ² )
In the present invention, the Hunter whiteness (W) is specifically measured by the following method.
<W measurement method>
(I) The aqueous polymer solution is adjusted to a solid content of 20%.
(Ii) The polymer aqueous solution obtained in (i) above is applied to a glass fiber filter (GA-100 manufactured by ADVANTEC) so that the polymer solid content is 150% of the weight of the glass filter.
(Iii) The glass fiber filter obtained in (ii) above is dried in an oven at 200 ° C. for 60 minutes, then transferred to a desiccator and cooled for 30 minutes.
(Iv) W is measured with a spectroscopic color difference meter SE-2000 (reflection mode) manufactured by Nippon Denshoku Industries Co., Ltd.

[Production method of poly (meth) acrylic acid polymer of the present invention]
The method for producing a poly (meth) acrylic acid polymer of the present invention (hereinafter also referred to as “the method for producing a polymer of the present invention”) comprises a monomer (mono) containing (meth) acrylic acid (salt) as an essential component. It can manufacture by including the process (polymerization process) of superposing | polymerizing a monomer component) essential. Further, when the monomer component is polymerized, the other monomer (E) may be further copolymerized as necessary.

In the method for producing a polymer of the present invention, (meth) acrylic acid (total amount of monomers used in polymerization (total amount of (meth) acrylic acid (salt) and other monomers) is 100 mol%. Salt) is preferably 50 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more. By being in the above range, the detergent characteristics of the polymer of the present invention tend to be improved, and the hue stability during heating tends to be improved.
In the method for producing a polymer of the present invention, the composition of other monomers is preferably 0 mol% or more and 50 mol% or less with respect to the total amount of monomers used is 100 mol%, and 0 mol% or more. 20 mol% or less is more preferable, and 0 mol% or more and 10 mol% or less is further preferable. By being in the above range, the detergent characteristics of the polymer of the present invention tend to be improved, and the hue stability during heating tends to be improved.

In the polymerization step, it is preferable to polymerize a monomer (monomer component) containing (meth) acrylic acid (salt) as an essential component in the presence of a polymerization initiator.
Examples of the polymerization initiator include persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate; 2,2′-azobis (isobutyronitrile), 2,2′-azobis (2-methylpropionamidine) 2 Examples include azo compounds such as hydrochlorides; organic peroxides such as benzoyl peroxide, lauroyl peroxide, peracetic acid, di-t-butyl peroxide, cumene hydroperoxide; and hydrogen peroxide. The said polymerization initiator may be used individually by 1 type, and may use 2 or more types together.
The amount of the polymerization initiator used in the method for producing a polymer of the present invention is preferably 0.1 g or more and 10 g or less with respect to 1 mol of all monomers. More preferably 0.1 g or more and 5 g or less, particularly preferably 0.1 g or more and 4 g or less.

In the polymerization step, a monomer (monomer component) containing (meth) acrylic acid (salt) as an essential component may be polymerized in the presence of a chain transfer agent. Specific examples of chain transfer agents that can be used include thiol chain transfer agents such as mercaptoethanol, thioglycolic acid (salt), and 3-mercaptopropionic acid (salt); halides such as methylene chloride and bromoform; isopropanol Secondary alcohols such as glycerin; phosphorous acid, hypophosphorous acid, and salts thereof; bisulfite (salt), sulfite (salt), dithionite (salt), metabisulfite (salt), etc. And the like. The chain transfer agents may be used alone or in combination of two or more.
In the method for producing a polymer of the present invention, as described above, a sulfonic acid (salt) group, a hypophosphorous acid (salt) group, a —S—R ₀ —COOM group (provided that R ₀ represents an alkylene group having 1 to 5 carbon atoms, and M represents a hydrogen atom, a metal atom, an ammonium salt, or an organic amine salt), and can easily form one or more groups selected from the group consisting of: As a chain transfer agent, -R such as bisulfite (salt), a compound capable of generating bisulfite (salt), hypophosphorous acid (salt), thioglycolic acid (salt) and 3-mercaptopropionic acid (salt) One or more selected from thiols having a _0- COOM group (where R ₀ represents an alkylene group having 1 to 5 carbon atoms, and M represents a hydrogen atom, a metal atom, an ammonium salt, or an organic amine salt). It is more preferable to use bisulfite (salt , Compounds that can generate the bisulfite (salt), it is more preferable to use one or more selected from hypophosphorous acid (salt).
The amount of chain transfer agent used in the method for producing a polymer of the present invention is preferably 0.5 g or more and 15 g or less with respect to 1 mol of all monomers. Yes, more preferably 1 g or more and 10 g or less, particularly preferably 1 g or more and 7 g or less.

In the method for producing a polymer of the present invention, a heavy metal compound may be used as a reaction accelerator. In the present invention, the heavy metal means a metal having a specific gravity of 4 g / cm ³ or more. The heavy metal compound is not limited as long as it generates heavy metal ions, and examples thereof include vanadyl sulfate, copper (II) hydroxide, and ferric ammonium sulfate.
In the method for producing the polymer of the present invention, the amount of the heavy metal compound used (when two or more are used, the total amount used) is converted to the mass of the heavy metal with respect to the total mass of the polymerization reaction solution at the completion of the polymerization reaction. 0 to 10 ppm is preferable. The time when the polymerization reaction is completed means the time when the polymerization reaction is substantially completed in the polymerization reaction solution and a desired polymer is obtained.

In the polymerization step, it is preferable to use a solvent. The solvent that can be used preferably includes water, preferably 50% by mass or more and 100% by mass of water with respect to the total amount of solvent used, and the total amount of solvent used is preferably water. .
Examples of organic solvents that can be used alone or in combination with water in the polymerization step include lower alcohols such as ethanol and isopropyl alcohol; lower ketones such as acetone and methyl ethyl ketone; ethers such as dimethyl ether and dioxane; amides such as dimethylformaldehyde. Kind. One or more organic solvents can be used.
As the usage-amount of the said solvent (when using 2 or more types), 40-200 mass% is preferable with respect to 100 mass% of the total usage-amount of all the monomers. More preferably, it is 45 mass% or more, More preferably, it is 50 mass% or more. Moreover, More preferably, it is 180 mass% or less, More preferably, it is 150 mass% or less. If the amount of the solvent used is 40% by mass or less, the molecular weight of the obtained polymer may be increased, and if it exceeds 200% by mass, the concentration of the obtained polymer will be low, and the handling will be complicated. There is a risk of increasing the monomer.

In the above polymerization step, as a method of adding the monomer to the reaction vessel, a method in which a part or all of the monomer is previously added to the reaction solution before the start of polymerization, and the entire amount of the monomer is added after the start of polymerization. However, it is preferable to add some or all of the monomers to the reaction vessel sequentially (preferably continuously) after the start of polymerization. In addition, before the polymerization start time mentioned later is called before polymerization start, and after the polymerization start time is called after polymerization start.
The monomer may be previously dissolved in a solvent and added to the reaction vessel.

In the above polymerization step, as a method of adding a polymerization initiator to the reaction vessel, a method in which a part or all of the polymerization initiator is previously added to the reaction solution before the start of polymerization, and the entire amount of the polymerization initiator after the start of polymerization. However, it is preferable to add part or all of the polymerization initiator to the reaction vessel sequentially (preferably continuously) after the start of polymerization.
The polymerization initiator may be dissolved in a solvent in advance and added to the reaction vessel.
The end point of addition of the polymerization initiator is preferably after the end point of addition of the monomer, more preferably within 60 minutes from the end of addition of the monomer, and 30 from the end of addition of the monomer. Particularly preferred is within minutes.

In the polymerization step, when a chain transfer agent is used, as a method of adding the chain transfer agent to the reaction vessel, a method in which a part or all of the chain transfer agent is added to the reaction solution in advance before the polymerization is started. Although it is possible to add the entire amount of transfer agent to the reaction vessel after the start of polymerization, it is possible to add part or all of the chain transfer agent to the reaction vessel sequentially (preferably continuously) after the start of polymerization. Is preferred.
The chain transfer agent may be previously dissolved in a solvent and added to the reaction vessel.
When the monomer, polymerization initiator, chain transfer agent, etc. are added sequentially, the addition rate may be constant, but the addition rate may be changed during the process.

  As a polymerization method in the polymerization step, for example, it can be carried out by a commonly used method such as solution polymerization, bulk polymerization, suspension polymerization, emulsion polymerization and the like, and is not particularly limited, but solution polymerization is preferable. When a solvent is used, it is preferable that a part or all of the solvent is usually charged in the reaction vessel before the start of polymerization, but a part of the solvent is added to the reaction system after the start of polymerization (dropping). Alternatively, the monomer component, the polymerization initiator, and the like may be added (dropped) into the reaction system during the polymerization reaction together with these components in a form in which the monomer component and the polymerization initiator are previously dissolved in a solvent.

In the polymerization step, the polymerization temperature is usually preferably 0 ° C. or higher and preferably 150 ° C. or lower. More preferably, it is 40 degreeC or more, More preferably, it is 60 degreeC or more, Most preferably, it is 80 degreeC or more. Moreover, More preferably, it is 120 degrees C or less, More preferably, it is 110 degrees C or less. In particular, when bisulfurous acid (salt) is used, the copolymerization temperature is usually 60 ° C to 95 ° C, preferably 70 ° C to 95 ° C, and more preferably 80 ° C to 95 ° C. At this time, at 60 ° C. or less, there is a possibility that a large amount of impurities derived from bisulfurous acid (salts) is generated. On the contrary, when it exceeds 95 ° C., toxic sulfurous acid gas may be released.
In the above polymerization step, the polymerization temperature does not always need to be kept almost constant. For example, polymerization is started from room temperature, the temperature is increased to a set temperature at an appropriate temperature increase time or rate, and then the set temperature is maintained. Depending on the dropping method of the monomer component, the initiator, etc., the temperature may be changed over time (temperature increase or decrease) during the polymerization reaction.

In the method for producing a polymer of the present invention, the polymerization time is preferably 30 to 360 minutes. More preferably, it is 60-240 minutes, More preferably, it is 120-180 minutes.
In the present invention, the “polymerization time” refers to the first time when polymerization is carried out while adding a part or all of the monomer to the reactor (reaction kettle) in the palindromic (batch type) polymerization method. From the time when a part or all of the polymerization initiator and a part or all of the monomer are added to the reactor (referred to as polymerization start time) to the time when the whole amount of monomer is added to the reactor (polymerization completed) Until the time). In addition, in the palindromic (batch type) polymerization method, the entire amount of monomer is added to the reactor in advance (referred to as initial charge), and a part or all of the polymerization initiator is added to the reactor (reaction kettle). In the case of polymerization, it is from the time when all or part of the polymerization initiator and all the monomers are first added to the reactor to the time when the entire amount of the polymerization initiator is added to the reactor. . In addition, in the palindromic (batch type) polymerization method, when the total amount of the monomer and the total amount of the polymerization initiator are added to the reactor in advance and the polymerization is performed by means such as heating, an exothermic (polymerization) This is the time when heat generation is observed. Moreover, when superposing | polymerizing by a continuous type, the time which has stayed in the reactor is said.

  The pressure in the reaction system in the polymerization step may be any of normal pressure (atmospheric pressure), reduced pressure, and increased pressure, but in terms of the molecular weight of the resulting copolymer, The reaction system is preferably sealed and the reaction is carried out under pressure. Moreover, it is preferable to carry out under a normal pressure (atmospheric pressure) at the point of equipment, such as a pressurization apparatus, a pressure reduction apparatus, a pressure-resistant reaction container, and piping. The atmosphere in the reaction system may be an air atmosphere, but is preferably an inert atmosphere. For example, the inside of the system is preferably replaced with an inert gas such as nitrogen before the start of polymerization.

  The pH during the polymerization in the polymerization step is preferably acidic. By carrying out the reaction under acidic conditions, an increase in the viscosity of the aqueous solution in the polymerization reaction system can be suppressed, and the polymer can be produced favorably. Further, since the polymerization reaction can proceed under high concentration conditions, the production efficiency can be greatly increased, and high concentration polymerization with a final solid content concentration of 40% or more can be achieved. As said acidic conditions, it is preferable that pH at 25 degreeC of the reaction solution in superposition | polymerization is 1-6, More preferably, it is 5 or less, More preferably, it is 3 or less.

In the polymerization step, the neutralization rate of the monomer during the polymerization can be appropriately changed depending on the polymerization initiator or the like. For example, the monomer component is preferably copolymerized with the monomer neutralization rate of 0 to 30 mol%, more preferably 0 to 15 mol%, and particularly preferably 0 to 10 mol%.
In the polymerization step, polymerization may be performed while neutralizing with an organic amine.

The production method of the present invention includes the above polymerization step as an essential step. In addition, an aging step, a neutralization step, a purification step, and the like may be included.
For example, when bisulfite (salt) is used as the chain transfer agent, a step of decomposing the remaining bisulfite by adding a peroxide such as hydrogen peroxide may be included. By including this step, it is possible to suppress the generation of sulfurous acid gas when the poly (meth) acrylic acid polymer of the present invention is placed in an acidic state or heated.
For example, after the polymerization step, a step of neutralizing the polymer with an organic amine may be included. When neutralizing with an organic amine, the liquid temperature is preferably 0 to 100 ° C. in the presence of a solvent such as water.
[Poly (meth) acrylic acid polymer composition of the present invention]
The poly (meth) acrylic acid polymer composition of the present invention (hereinafter also referred to as “the polymer composition of the present invention”) includes the poly (meth) acrylic acid polymer of the present invention, and other water, etc. Raw material residues such as solvents, residual monomers, polymerization initiators, and the like.
The polymer composition of the present invention preferably contains 1 to 100% by mass of the poly (meth) acrylic acid polymer of the present invention.
When the polymer composition of the present invention is an aqueous solution, it preferably contains 20 to 99% by mass of water.
In the polymer composition of the present invention, the content of the residual monomer is preferably 0 to 15000 ppm, more preferably 0 to 10,000 ppm in terms of solid content.

The polymer composition of the present invention preferably contains hypophosphorous acid (salt) because the stability of the hue upon heating is further improved (that is, the decrease in hue when heated can be suppressed). When hypophosphorous acid (salt) is used in the polymerization step, hypophosphorous acid (salt) is included in the polymer composition by adding excessive hypophosphorous acid (salt) during polymerization. However, since excessive hypophosphite may cause a chain transfer reaction and control of the molecular weight of the polymer may become complicated, it is preferably added after completion of the polymerization reaction.
When the neutralization rate of the poly (meth) acrylic acid polymer by the organic amine is within the above range, the hue stabilizing effect during heating due to the inclusion of the hypophosphorous acid (salt) can be obtained. .
Hypophosphorous acid (salt) contained in the polymer composition of the present invention (excluding those incorporated in the polymer molecule) is 0.5 to 100% by mass with respect to 100% by mass of the solid content of the polymer composition. It is preferably 10% by mass, and more preferably 0.5 to 5% by mass.
Examples of hypophosphorous acid (salt) are as described above.
[Use of polycarboxylic acid polymer (composition) of the present invention]
The polycarboxylic acid polymer (or polymer composition) includes additives for detergent compositions (detergent builders, etc.), water treatment agents such as scale inhibitors, fiber treatment agents, dispersants, deinking agents, metals It can be used as an ion sealing agent, thickener, organic fiber / inorganic fiber binder, powder binder, pulp crosslinking agent, emulsifier, skin care agent, hair care agent and the like.

<Detergent Builder>
The polymer of the present invention can be used as a detergent builder. As a detergent builder, it can be used by adding to detergents for various uses such as clothing, tableware, residential, hair, body, toothpaste, and automobile.
That is, the polymer of the present invention can be added to a detergent composition. The concept of the detergent composition includes household detergent compositions, textile industry and other industrial detergent compositions, hard surface cleaner compositions, and the like, and further included in detergent compositions such as bleach detergent compositions. Also included are detergent compositions that enhance the function of certain ingredients.
The content of the polymer of the present invention in the detergent composition is not particularly limited. However, from the viewpoint that excellent builder performance can be exhibited, the content of the polymer of the present invention is preferably 0.1 to 15% by mass, more preferably 0, based on the total amount of the detergent composition. 0.3 to 10% by mass, and more preferably 0.5 to 5% by mass.

  Detergent compositions used in detergent applications usually include surfactants and additives used in detergents. Specific forms of these surfactants and additives are not particularly limited, and conventionally known knowledge can be appropriately referred to in the detergent field. The detergent composition is particularly preferred in the case of a powder detergent composition, but can also be used in the case of a liquid detergent composition.

The surfactant is one or more selected from the group consisting of an anionic surfactant, a nonionic surfactant, a cationic surfactant and an amphoteric surfactant. When two or more kinds are used in combination, the total amount of the anionic surfactant and the nonionic surfactant is preferably 50% by mass or more, more preferably 60% by mass with respect to the total amount of the surfactant. It is above, More preferably, it is 70 mass% or more, Most preferably, it is 80 mass% or more.
It is preferable that the compounding ratio of surfactant is 10-70 mass% with respect to the whole quantity of a detergent composition, More preferably, it is 15-60 mass%. When the blending ratio of the surfactant is too small, there is a possibility that sufficient detergency cannot be exhibited.
Specific examples of the surfactant include alkylbenzene sulfonates and alkyl sulfates as anionic surfactants; polyoxyalkylene alkyl ethers, polyoxyethylene alkylphenyl ethers and the like as nonionic surfactants; Examples of cationic surfactants include quaternary ammonium salts; examples of amphoteric surfactants include carboxyl-type amphoteric surfactants and sulfobetaine-type amphoteric surfactants.

The detergent composition of the present invention comprises an alkali builder such as carbonate, hydrogen carbonate, silicic acid (salt), etc. as an additive (other additives) other than the polymer and surfactant of the present invention; tripolyphosphoric acid (salt) , Chelate builder such as citric acid (salt), acrylic acid-maleic acid copolymer (salt), ethylenediaminetetraacetic acid (salt), bow glass, zeolite, etc .; prevents re-deposition of contaminants such as carboxymethyl cellulose (salt) Anti-redeposition agent for soils; stain inhibitor such as benzotriazole and ethylene-thiourea; soil release agent; color transfer inhibitor such as polyvinylpyrrolidone; softener; alkaline substance for pH adjustment; fragrance; Fluorescent agent; Coloring agent; Foaming agent; Foam stabilizer; Polishing agent; Bactericidal agent; Bleaching agent; Bleaching aid; Enzyme; Dye; Examples of the salt in the other additives include metal salts, ammonium salts, and organic amine salts.
15-89.9 mass% is preferable with respect to 100 mass% of cleaning composition, and, as for the total mixture ratio of the said other additive, 30-84.7 mass% is more preferable.
When the detergent composition of the present invention is a powder detergent composition, it is preferable to blend zeolite.
When the detergent composition of the present invention is a liquid detergent composition, water is preferably contained in an amount of 0.1 to 75% by mass, more preferably 1.5 to 50% by mass, based on the total amount of the liquid detergent composition. preferable.

<Water treatment agent>
The polymer of the present invention can be used alone or in combination with other compounding agents for water treatment agents such as scale inhibitors. If necessary, the water treatment agent may contain a polymerized phosphate, phosphonate, anticorrosive, slime control agent, and chelating agent as other compounding agents. The content of the polymer of the present invention in the water treatment agent is preferably 1 to 100% by weight, more preferably 5 to 100% by weight, based on the entire water treatment agent.

  The water treatment agent is useful for scale prevention in a cooling water circulation system, a boiler water circulation system, a seawater desalination apparatus, a pulp digester, a black liquor concentration tank, and the like. Further, any appropriate water-soluble polymer may be included as long as it does not affect the performance and effects.

<Fiber treatment agent>
The polymer of the present invention can be used as a fiber treatment agent. The fiber treatment agent includes at least one selected from the group consisting of a dye, a peroxide and a surfactant, and the polymer of the present invention.
The content of the polymer of the present invention in the fiber treatment agent is preferably 1 to 100% by weight, more preferably 5 to 100% by weight, based on the entire fiber treatment agent. Further, any appropriate water-soluble polymer may be included as long as the performance and effects are not affected.

  Below, the compounding example of the fiber processing agent which is closer to embodiment is shown. This fiber treatment agent can be used in the steps of refining, dyeing, bleaching and soaping in fiber treatment. Examples of dyeing agents, peroxides and surfactants include those usually used for fiber treatment agents.

  The blending ratio of the polymer of the present invention to at least one selected from the group consisting of a dye, a peroxide, and a surfactant is, for example, for improving the whiteness, color unevenness, and dyeing tempering degree of fibers. Is 0.1 to 100 parts by weight of at least one selected from the group consisting of a dyeing agent, a peroxide and a surfactant with respect to 1 part by weight of the polymer of the present invention in terms of a pure amount of the fiber treatment agent. It is preferable to use the composition mix | blended in a ratio as a fiber processing agent.

  Arbitrary appropriate fiber can be employ | adopted as a fiber which can use the said fiber processing agent. Examples thereof include cellulosic fibers such as cotton and hemp, chemical fibers such as nylon and polyester, animal fibers such as wool and silk, semi-synthetic fibers such as human silk, and woven fabrics and blended products thereof.

When the fiber treatment agent is applied to the refining process, it is preferable to blend the polymer of the present invention with an alkali agent and a surfactant. When applied to the bleaching step, it is preferable to blend the carboxyl group-containing copolymer of the present invention, a peroxide, and a silicic acid-based agent such as sodium silicate as a decomposition inhibitor for the alkaline bleaching agent.
<Inorganic pigment dispersant>
The polymer of the present invention can be used as an inorganic pigment dispersant. In the inorganic pigment dispersant, condensed phosphoric acid and its salt, phosphonic acid and its salt, and polyvinyl alcohol may be used as other compounding agents as required.
The content of the polymer of the present invention in the inorganic pigment dispersant is preferably 5 to 100% by weight with respect to the whole inorganic pigment dispersant. Further, any appropriate water-soluble polymer may be included as long as it does not affect the performance and effect.
The inorganic pigment dispersant can exhibit good performance as a dispersant for heavy or light calcium carbonate or clay inorganic pigment used in paper coating. For example, by adding a small amount of an inorganic pigment dispersant to an inorganic pigment and dispersing it in water, high concentration calcium carbonate having low viscosity and high fluidity and good aging stability of their performance. High concentration inorganic pigment slurries such as slurries can be produced.
When the inorganic pigment dispersant is used as a dispersant for an inorganic pigment, the amount of the inorganic pigment dispersant used is preferably 0.05 to 2.0 parts by weight with respect to 100 parts by weight of the inorganic pigment. When the amount of the inorganic pigment dispersant used is within the above range, a sufficient dispersion effect can be obtained, and an effect commensurate with the addition amount can be obtained, which can be economically advantageous.

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 mass” and “%” means “% by mass”.
Moreover, the weight average molecular weight of the polymer of this invention, the hue at the time of drying, etc. were measured in accordance with the following method.

<Measurement conditions of weight average molecular weight>
Device: Tosoh HLC-8320GPC
Detector: RI
Column: Tosoh TSK-GEL G4000PWXL, G3000PWXL
Column temperature: 40 ° C
Flow rate: 0.5 ml / min
Calibration curve: POLY SODIUM ACRYLATE STANDARD
Eluent: A solution obtained by diluting a mixture of sodium dihydrogen phosphate 12 hydrate / disodium hydrogen phosphate dihydrate (34.5 g / 46.2 g) to 5000 g with pure water.

<Method for measuring solid content of polymer composition>
In a nitrogen atmosphere, the polymer composition (polymer composition 1.0 g + water 3.0 g) was left to dry for 1 hour in an oven heated to 130 ° C. The solid content (%) was calculated from the weight change before and after drying.

<Example 1>
In a 2.5-liter SUS separable flask equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer, 343 g of pure water and 0.05 g of ferric ammonium sulfate (hereinafter referred to as Mole salt) were added. The temperature was raised to 90 ° C. with charging (initial charging) and stirring. Next, 945 g of an 80% by weight acrylic acid aqueous solution (hereinafter referred to as “80% AA”) and 15% by weight aqueous sodium persulfate (hereinafter referred to as “15”) in a polymerization reaction system at a constant temperature of about 90 ° C. with stirring. 140 g (referred to as% NaPS ”) (2.0 g / mol in terms of monomer input), 35% by weight sodium bisulfite aqueous solution (hereinafter referred to as“ 35% SBS ”) 150 g (monomer input) Converted to 5.0 g / mol) and 43.8 g of a 48 mass% sodium hydroxide aqueous solution (hereinafter referred to as “48% NaOH”) (5 mol% neutralized portion of acrylic acid) were dropped from separate dropping nozzles. . The dropping time was 80% AA for 180 minutes, 15% NaPS for 190 minutes, 35% SBS for 180 minutes, and 48% NaOH for 180 minutes. Further, during each dropping time, the dropping rate of each component was kept constant, and dropping was continuously performed. After completion of the dropwise addition, the reaction solution was kept at 90 ° C. (ripening) for an additional 30 minutes to complete the polymerization. After completion of the polymerization, the reaction solution was allowed to cool, and 13.8 g of an 80% by weight diethanolamine aqueous solution (1 mol% neutralized portion of acrylic acid) was gradually added dropwise to the reaction solution while stirring to effect neutralization. The reaction solution was allowed to cool to 50 ° C., and 2.3 g of 35% by mass hydrogen peroxide was added dropwise to the reaction solution and sufficiently stirred. As described above, an aqueous solution of the polyacrylic acid polymer (1) of the present invention was obtained. The individual fraction value of the aqueous solution was 52.1%, and the weight average molecular weight (Mw) was 4000.
When the whiteness of the polymer when dried was evaluated by the method described above, the W value was 77.6.

<Example 2>
A SUS separable flask having a capacity of 2.5 liters equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer was charged with 343 g of pure water and 0.05 g of Mole salt (initial charge), and stirred at 90 ° C. The temperature was raised to. Subsequently, 945 g of an 80% by weight acrylic acid aqueous solution (that is, 10.5 mol) and 140 g of a 15% by weight aqueous sodium persulfate solution (2.0 g when converted to the amount of monomer charged) in a polymerization reaction system at a constant temperature of about 90 ° C. with stirring. / Mol), 150 g of 35% by weight sodium bisulfite aqueous solution (5.0 g / mol when converted to the amount of monomer charged) and 43.8 g of 48% by weight sodium hydroxide aqueous solution (5 mol% neutralized portion of acrylic acid) It dripped from each separate dripping nozzle. The dropping time was 80% AA for 180 minutes, 15% NaPS for 190 minutes, 35% SBS for 180 minutes, and 48% NaOH for 180 minutes. Further, during each dropping time, the dropping rate of each component was kept constant, and dropping was continuously performed. After completion of the dropwise addition, the reaction solution was kept at 90 ° C. (ripening) for an additional 30 minutes to complete the polymerization. After completion of the polymerization, the reaction solution was allowed to cool and 69 g of an 80 mass% diethanolamine aqueous solution (5 mol% neutralized portion of acrylic acid) was gradually added dropwise to the reaction solution while stirring to effect neutralization. The reaction solution was allowed to cool to 50 ° C., and 2.3 g of 35% by mass hydrogen peroxide was added dropwise to the reaction solution and sufficiently stirred. As described above, an aqueous solution of the polyacrylic acid polymer (2) of the present invention was obtained. The solid content of the aqueous solution was 53.0%, and the weight average molecular weight (Mw) was 4000.
When the whiteness of the polymer during drying was evaluated by the method described above, the W value was 80.9.

<Example 3>
A SUS separable flask having a capacity of 2.5 liters equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer was charged with 343 g of pure water and 0.05 g of Mole salt (initial charge), and stirred at 90 ° C. The temperature was raised to. Subsequently, 945 g of an 80% by weight acrylic acid aqueous solution (that is, 10.5 mol) and 140 g of a 15% by weight aqueous sodium persulfate solution (2.0 g when converted to the amount of monomer charged) in a polymerization reaction system at a constant temperature of about 90 ° C. with stirring. / Mol), 150 g of 35% by weight sodium bisulfite aqueous solution (5.0 g / mol when converted to the amount of monomer charged) and 43.8 g of 48% by weight sodium hydroxide aqueous solution (5 mol% neutralized portion of acrylic acid) It dripped from each separate dripping nozzle. The dropping time was 80% AA for 180 minutes, 15% NaPS for 190 minutes, 35% SBS for 180 minutes, and 48% NaOH for 180 minutes. Further, during each dropping time, the dropping rate of each component was kept constant, and dropping was continuously performed. After completion of the dropwise addition, the reaction solution was kept at 90 ° C. (ripening) for an additional 30 minutes to complete the polymerization. After completion of the polymerization, while the reaction solution was allowed to cool, 138 g of an 80% by mass diethanolamine aqueous solution (10 mol% neutralized portion of acrylic acid) was gradually added dropwise to the reaction solution while stirring to effect neutralization. The reaction solution was allowed to cool to 50 ° C., and 2.3 g of 35% by mass hydrogen peroxide was added dropwise to the reaction solution and sufficiently stirred. As described above, an aqueous solution of the polyacrylic acid polymer (3) of the present invention was obtained. The solid content of the aqueous solution was 54.0%, and the weight average molecular weight (Mw) was 4000.
When the whiteness at the time of drying of a polymer was evaluated by the above-mentioned method, W value was 85.9.

<Example 4>
A SUS separable flask having a capacity of 2.5 liters equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer was charged with 343 g of pure water and 0.05 g of Mole salt (initial charge), and stirred at 90 ° C. The temperature was raised to. Subsequently, 945 g of an 80% by weight acrylic acid aqueous solution (that is, 10.5 mol) and 140 g of a 15% by weight aqueous sodium persulfate solution (2.0 g when converted to the amount of monomer charged) in a polymerization reaction system at a constant temperature of about 90 ° C. with stirring. / Mol), 150 g of 35% by weight sodium bisulfite aqueous solution (5.0 g / mol when converted to the amount of monomer charged) and 43.8 g of 48% by weight sodium hydroxide aqueous solution (5 mol% neutralized portion of acrylic acid) It dripped from each separate dripping nozzle. The dropping time was 80% AA for 180 minutes, 15% NaPS for 190 minutes, 35% SBS for 180 minutes, and 48% NaOH for 180 minutes. Further, during each dropping time, the dropping rate of each component was kept constant, and dropping was continuously performed. After completion of the dropwise addition, the reaction solution was kept at 90 ° C. (ripening) for an additional 30 minutes to complete the polymerization. After completion of the polymerization, the reaction solution was allowed to cool, and 621 g of an 80% by mass diethanolamine aqueous solution (45 mol% neutralized portion of acrylic acid) was gradually added dropwise to the reaction solution while stirring to effect neutralization. The reaction solution was allowed to cool to 50 ° C., and 2.3 g of 35% by mass hydrogen peroxide was added dropwise to the reaction solution and sufficiently stirred. As described above, an aqueous solution of the polyacrylic acid polymer (4) of the present invention was obtained. The aqueous solution had a solid content value of 59.6.0% and a weight average molecular weight (Mw) of 4000.
When the whiteness degree at the time of drying of a polymer was evaluated by the above-mentioned method, the W value was 78.2.

<Example 5>
A SUS separable flask having a capacity of 2.5 liters equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer was charged with 343 g of pure water and 0.05 g of Mole salt (initial charge), and stirred at 90 ° C. The temperature was raised to. Subsequently, 945 g of an 80% by weight acrylic acid aqueous solution (that is, 10.5 mol) and 140 g of a 15% by weight aqueous sodium persulfate solution (2.0 g when converted to the amount of monomer charged) in a polymerization reaction system at a constant temperature of about 90 ° C. with stirring. / Mol), 150 g of 35% by weight sodium bisulfite aqueous solution (5.0 g / mol when converted to the amount of monomer charged) and 43.8 g of 48% by weight sodium hydroxide aqueous solution (5 mol% neutralized portion of acrylic acid) It dripped from each separate dripping nozzle. The dropping time was 80% AA for 180 minutes, 15% NaPS for 190 minutes, 35% SBS for 180 minutes, and 48% NaOH for 180 minutes. Further, during each dropping time, the dropping rate of each component was kept constant, and dropping was continuously performed. After completion of the dropwise addition, the reaction solution was kept at 90 ° C. (ripening) for an additional 30 minutes to complete the polymerization. After completion of the polymerization, the reaction solution was allowed to cool, and 69 g of an 80% by mass diethanolamine aqueous solution (5 mol% neutralized acrylic acid) and a 37% by mass sodium hypophosphite aqueous solution (hereinafter referred to as “37% SHP”) 84 g (3.4% by mass with respect to 100% by mass of the solid content of the polymer composition) was gradually added dropwise to the reaction solution with stirring. The reaction solution was allowed to cool to 50 ° C., and 2.3 g of 35% by mass hydrogen peroxide was added dropwise to the reaction solution and sufficiently stirred. As described above, an aqueous solution of the polyacrylic acid polymer (5) of the present invention was obtained. The solid content of the aqueous solution was 52.2%, and the weight average molecular weight (Mw) was 4000.
When the whiteness at the time of drying of a polymer was evaluated by the above-mentioned method, W value was 84.8.

<Example 6>
Into a 2.5 liter SUS separable flask equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer, 304.7 g of pure water was charged (initial charge), and the temperature was raised to the boiling point with stirring. Next, 810 g of an 80% by mass acrylic acid aqueous solution (that is, 9.0 mol) and 42.6 g of an aqueous 15% by mass sodium persulfate solution (0.7 g when converted to the amount of monomer added) in the polymerization reaction system in a boiling point reflux state with stirring. / Mol) and 100 g of a 37 mass% sodium hypophosphite aqueous solution (4.1 g / mol when converted to the amount of monomer added) were dropped from separate dropping nozzles. The dropping time was 80% AA for 180 minutes, 15% NaPS for 185 minutes, and 37% SHP for 180 minutes. Further, during each dropping time, the dropping rate of each component was kept constant, and dropping was continuously performed. After completion of the dropwise addition, the reaction solution was kept at the boiling point reflux state (ripening) for an additional 30 minutes to complete the polymerization. After completion of the polymerization, 135 g of pure water was added to the reaction solution, and then the reaction solution was allowed to cool, and 23.7 g of an 80% by mass diethanolamine aqueous solution (2 mol% neutralized portion of acrylic acid) was gradually stirred into the reaction solution. Neutralization was carried out by adding dropwise. As described above, an aqueous solution of the polyacrylic acid polymer (6) of the present invention was obtained. The individual fraction value of the aqueous solution was 50.2%, and the weight average molecular weight (Mw) was 4000.
When the whiteness degree at the time of drying of a polymer was evaluated by the above-mentioned method, W value was 80.3.

<Example 7>
Into a 2.5 liter SUS separable flask equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer, 304.7 g of pure water was charged (initial charge), and the temperature was raised to the boiling point with stirring. Next, 810 g of an 80% by mass acrylic acid aqueous solution (that is, 9.0 mol) and 42.6 g of an aqueous 15% by mass sodium persulfate solution (0.7 g when converted to the amount of monomer added) in the polymerization reaction system in a boiling point reflux state with stirring. / Mol) and 100 g of a 37 mass% sodium hypophosphite aqueous solution (4.1 g / mol when converted to the amount of monomer added) were dropped from separate dropping nozzles. The dropping time was 80% AA for 180 minutes, 15% NaPS for 185 minutes, and 37% SHP for 180 minutes. Further, during each dropping time, the dropping rate of each component was kept constant, and dropping was continuously performed. After completion of the dropwise addition, the reaction solution was kept at the boiling point reflux state (ripening) for an additional 30 minutes to complete the polymerization. After completion of the polymerization, 135 g of pure water was added to the reaction solution, and then the reaction solution was allowed to cool, and 59.1 g of an 80% by mass diethanolamine aqueous solution (5 mol% neutralized portion of acrylic acid) was gradually added to the reaction solution while stirring. Neutralization was carried out by adding dropwise. As described above, an aqueous solution of the polyacrylic acid polymer (7) of the present invention was obtained. The solid content of the aqueous solution was 50.9%, and the weight average molecular weight (Mw) was 4000.
When the whiteness of the polymer during drying was evaluated by the method described above, the W value was 82.7.

<Example 8>
Into a 2.5 liter SUS separable flask equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer, 304.7 g of pure water was charged (initial charge), and the temperature was raised to the boiling point with stirring. Next, 810 g of an 80% by mass acrylic acid aqueous solution (that is, 9.0 mol) and 42.6 g of an aqueous 15% by mass sodium persulfate solution (0.7 g when converted to the amount of monomer added) in the polymerization reaction system in a boiling point reflux state with stirring. / Mol) and 100 g of a 37 mass% sodium hypophosphite aqueous solution (4.1 g / mol when converted to the amount of monomer added) were dropped from separate dropping nozzles. The dropping time was 80% AA for 180 minutes, 15% NaPS for 185 minutes, and 37% SHP for 180 minutes. Further, during each dropping time, the dropping rate of each component was kept constant, and dropping was continuously performed. After completion of the dropwise addition, the reaction solution was kept at the boiling point reflux state (ripening) for an additional 30 minutes to complete the polymerization. After completion of the polymerization, 135 g of pure water was added to the reaction solution, and then the reaction solution was allowed to cool, and 118.3 g of an 80% by mass diethanolamine aqueous solution (10 mol% neutralized portion of acrylic acid) was gradually added to the reaction solution while stirring. Neutralization was carried out by adding dropwise. As described above, an aqueous solution of the polyacrylic acid polymer (8) of the present invention was obtained. The individual fraction value of the aqueous solution was 52.1%, and the weight average molecular weight (Mw) was 4000.
When the whiteness of the polymer when dried was evaluated by the method described above, the W value was 91.7.

<Example 9>
Into a 2.5 liter SUS separable flask equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer, 304.7 g of pure water was charged (initial charge), and the temperature was raised to the boiling point with stirring. Next, 810 g of an 80% by mass acrylic acid aqueous solution (that is, 9.0 mol) and 42.6 g of an aqueous 15% by mass sodium persulfate solution (0.7 g when converted to the amount of monomer added) in the polymerization reaction system in a boiling point reflux state with stirring. / Mol) and 100 g of a 37 mass% sodium hypophosphite aqueous solution (4.1 g / mol when converted to the amount of monomer added) were dropped from separate dropping nozzles. The dropping time was 80% AA for 180 minutes, 15% NaPS for 185 minutes, and 37% SHP for 180 minutes. Further, during each dropping time, the dropping rate of each component was kept constant, and dropping was continuously performed. After completion of the dropwise addition, the reaction solution was kept at the boiling point reflux state (ripening) for an additional 30 minutes to complete the polymerization. After completion of the polymerization, 135 g of pure water was added to the reaction solution, and then the reaction solution was allowed to cool, and 532.3 g of an 80% by mass diethanolamine aqueous solution (45 mol% neutralized portion of acrylic acid) was gradually stirred into the reaction solution. Neutralization was carried out by adding dropwise. As described above, an aqueous solution of the polyacrylic acid polymer (9) of the present invention was obtained. The individual fraction value of the aqueous solution was 58.1%, and the weight average molecular weight (Mw) was 4000.
When the whiteness of the polymer when dried was evaluated by the method described above, the W value was 79.0.

<Example 10>
Into a 2.5 liter SUS separable flask equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer, 304.7 g of pure water was charged (initial charge), and the temperature was raised to the boiling point with stirring. Next, 810 g of an 80% by mass acrylic acid aqueous solution (that is, 9.0 mol) and 42.6 g of an aqueous 15% by mass sodium persulfate solution (0.7 g when converted to the amount of monomer added) in the polymerization reaction system in a boiling point reflux state with stirring. / Mol) and 100 g of a 37 mass% sodium hypophosphite aqueous solution (4.1 g / mol when converted to the amount of monomer added) were dropped from separate dropping nozzles. The dropping time was 80% AA for 180 minutes, 15% NaPS for 185 minutes, and 37% SHP for 180 minutes. Further, during each dropping time, the dropping rate of each component was kept constant, and dropping was continuously performed. After completion of the dropwise addition, the reaction solution was kept at the boiling point reflux state (ripening) for an additional 30 minutes to complete the polymerization. After the completion of the polymerization, 135 g of pure water was added to the reaction solution, and then the reaction solution was allowed to cool, while 47.3 g of an 80% by mass diethanolamine aqueous solution (4 mol% neutralized portion of acrylic acid) and 37% by mass sodium hypophosphite 72 g of aqueous solution (3.6% by mass based on 100% by mass of the solid content of the polymer composition) was gradually added dropwise to the reaction solution with stirring. As described above, an aqueous solution of the polyacrylic acid polymer (10) of the present invention was obtained. The individual fraction value of the aqueous solution was 50.0%, and the weight average molecular weight (Mw) was 4000.
When the whiteness of the polymer when dried was evaluated by the method described above, the W value was 86.1.

<Example 11>
In a 2.5 liter SUS separable flask equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer, 341.1 g of pure water was charged (initial charge), and the temperature was raised to the boiling point with stirring. Subsequently, 900 g of an 80% by weight acrylic acid aqueous solution (that is, 10.0 mol) and 50 g of a 15% by weight aqueous sodium persulfate aqueous solution (0.75 g / mol when converted to the amount of monomer charged) in the polymerization reaction system in a boiling point reflux state with stirring. ) And 49 g of a 37 mass% sodium hypophosphite aqueous solution (1.8 g / mol when converted to the amount of monomer added) were added dropwise from separate dropping nozzles. The dropping time was 80% AA for 180 minutes, 15% NaPS for 185 minutes, and 37% SHP for 180 minutes. Further, during each dropping time, the dropping rate of each component was kept constant, and dropping was continuously performed. After completion of the dropwise addition, the reaction solution was kept at the boiling point reflux state (ripening) for an additional 30 minutes to complete the polymerization. After completion of the polymerization, 210 g of pure water was added to the reaction solution, and then the reaction solution was allowed to cool, and 131.4 g of an 80% by mass diethanolamine aqueous solution (10 mol% neutralized portion of acrylic acid) was gradually stirred into the reaction solution. Neutralization was carried out by adding dropwise. As described above, an aqueous solution of the polyacrylic acid polymer (11) of the present invention was obtained. The individual fraction value of the aqueous solution was 50.6%, and the weight average molecular weight (Mw) was 15000.
When the whiteness at the time of drying of the polymer was evaluated by the above-mentioned method, the W value was 91.0.

<Example 12>
In a 2.5 liter SUS separable flask equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer, 341.1 g of pure water was charged (initial charge), and the temperature was raised to the boiling point with stirring. Subsequently, 900 g of an 80% by weight acrylic acid aqueous solution (that is, 10.0 mol) and 50 g of a 15% by weight aqueous sodium persulfate aqueous solution (0.75 g / mol when converted to the amount of monomer charged) in the polymerization reaction system in a boiling point reflux state with stirring. ) And 49 g of a 37 mass% sodium hypophosphite aqueous solution (1.8 g / mol when converted to the amount of monomer added) were added dropwise from separate dropping nozzles. The dropping time was 80% AA for 180 minutes, 15% NaPS for 185 minutes, and 37% SHP for 180 minutes. Further, during each dropping time, the dropping rate of each component was kept constant, and dropping was continuously performed. After completion of the dropwise addition, the reaction solution was kept at the boiling point reflux state (ripening) for an additional 30 minutes to complete the polymerization. After completion of the polymerization, 210 g of pure water was added to the reaction solution, and then the reaction solution was allowed to cool, and 591.4 g of an 80% by weight diethanolamine aqueous solution (45 mol% neutralized portion of acrylic acid) was gradually added to the reaction solution while stirring. Neutralization was carried out by adding dropwise. As described above, an aqueous solution of the polyacrylic acid polymer (12) of the present invention was obtained. The aqueous solution had a shape fraction value of 56.8% and a weight average molecular weight (Mw) of 15,000.
When the whiteness of the polymer when dried was evaluated by the method described above, the W value was 77.9.

<Example 13>
A 2.5-liter SUS separable flask equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer was charged with 325.0 g of pure water (initial charge), and the temperature was raised to the boiling point with stirring. Subsequently, 900 g of an 80% by mass acrylic acid aqueous solution (that is, 10.0 mol%) and 83.3 g of a 30% by mass mercaptopropionic acid aqueous solution (hereinafter referred to as “30% MPA”) in a polymerization reaction system in a boiling point reflux state with stirring. 2.5 g / mol in terms of monomer charge, 53.0 g of 6% mass aqueous hydrogen peroxide solution (hereinafter referred to as “6% H ₂ O ₂ ”) 32 g / mol) and 72.8 g of an 1.8% by mass L-ascorbic acid aqueous solution (hereinafter referred to as “1.8% LAs”) (0.13 g / mol when converted to monomer input), respectively. It dripped from the dripping nozzle. The dropping time was 80% AA for 180 minutes, 30% MPA for 180 minutes, 6% H ₂ O ₂ for 215 minutes, and 1.8% LAs for 215 minutes. Further, during each dropping time, the dropping rate of each component was kept constant, and dropping was continuously performed. After completion of the dropwise addition, the reaction solution was kept at the boiling point reflux state (ripening) for an additional 30 minutes to complete the polymerization. After the completion of the polymerization, 282.5 g of pure water was added to the reaction solution, and then the reaction solution was allowed to cool, and 65.7 g of an 80% by mass diethanolamine aqueous solution (5 mol% neutralized portion of acrylic acid) was stirred into the reaction solution. The mixture was gradually dropped to neutralize. As described above, the polyacrylic acid polymer (13) of the present invention was obtained. The solid content of the aqueous solution was 45.0%, and the weight average molecular weight (Mw) was 11000.
When the whiteness at the time of drying of the polymer was evaluated by the above-mentioned method, the W value was 80.6.

<Example 14>
A 2.5-liter SUS separable flask equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer was charged with 325.0 g of pure water (initial charge), and the temperature was raised to the boiling point with stirring. Subsequently, 900 g of an 80% by mass acrylic acid aqueous solution (that is, 10.0 mol%) and 83.3 g of a 30% by mass mercaptopropionic acid aqueous solution (hereinafter referred to as “30% MPA”) in a polymerization reaction system in a boiling point reflux state with stirring. 2.5 g / mol in terms of monomer charge, 53.0 g of 6% mass aqueous hydrogen peroxide solution (hereinafter referred to as “6% H ₂ O ₂ ”) 32 g / mol) and 72.8 g of an 1.8% by mass L-ascorbic acid aqueous solution (hereinafter referred to as “1.8% LAs”) (0.13 g / mol when converted to monomer input), respectively. It dripped from the dripping nozzle. The dropping time was 80% AA for 180 minutes, 30% MPA for 180 minutes, 6% H ₂ O ₂ for 215 minutes, and 1.8% LAs for 215 minutes. Further, during each dropping time, the dropping rate of each component was kept constant, and dropping was continuously performed. After completion of the dropwise addition, the reaction solution was kept at the boiling point reflux state (ripening) for an additional 30 minutes to complete the polymerization. After the completion of the polymerization, 282.5 g of pure water was added to the reaction solution, and then the reaction solution was allowed to cool and 131.4 g of an 80% by mass diethanolamine aqueous solution (10 mol% neutralized portion of acrylic acid) was stirred into the reaction solution. The mixture was gradually dropped to neutralize. As described above, a polyacrylic acid polymer (14) of the present invention was obtained. The aqueous solution had a shape fraction value of 46.2% and a weight average molecular weight (Mw) of 11,000.
When the whiteness of the polymer when dried was evaluated by the method described above, the W value was 82.6.

<Example 15>
A 2.5-liter SUS separable flask equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer was charged with 325.0 g of pure water (initial charge), and the temperature was raised to the boiling point with stirring. Subsequently, 900 g of an 80% by mass acrylic acid aqueous solution (that is, 10.0 mol%) and 83.3 g of a 30% by mass mercaptopropionic acid aqueous solution (hereinafter referred to as “30% MPA”) in a polymerization reaction system in a boiling point reflux state with stirring. 2.5 g / mol in terms of monomer charge, 53.0 g of 6% mass aqueous hydrogen peroxide solution (hereinafter referred to as “6% H ₂ O ₂ ”) 32 g / mol) and 72.8 g of an 1.8% by mass L-ascorbic acid aqueous solution (hereinafter referred to as “1.8% LAs”) (0.13 g / mol when converted to monomer input), respectively. It dripped from the dripping nozzle. The dropping time was 80% AA for 180 minutes, 30% MPA for 180 minutes, 6% H ₂ O ₂ for 215 minutes, and 1.8% LAs for 215 minutes. Further, during each dropping time, the dropping rate of each component was kept constant, and dropping was continuously performed. After completion of the dropwise addition, the reaction solution was kept at the boiling point reflux state (ripening) for an additional 30 minutes to complete the polymerization. After the completion of the polymerization, 691.4 g of pure water was added to the reaction solution, and then the reaction solution was allowed to cool and 591.4 g of an 80% by mass diethanolamine aqueous solution (45 mol% neutralized portion of acrylic acid) was stirred into the reaction solution. The mixture was gradually dropped to neutralize. As described above, a polyacrylic acid polymer (15) of the present invention was obtained. The solid content of the aqueous solution was 45.0%, and the weight average molecular weight (Mw) was 11000.
When the whiteness of the polymer when dried was evaluated by the method described above, the W value was 77.2.

<Example 16>
A 2.5-liter SUS separable flask equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer was charged with 325.0 g of pure water (initial charge), and the temperature was raised to the boiling point with stirring. Subsequently, 900 g of an 80% by mass acrylic acid aqueous solution (that is, 10.0 mol%) and 83.3 g of a 30% by mass mercaptopropionic acid aqueous solution (hereinafter referred to as “30% MPA”) in a polymerization reaction system in a boiling point reflux state with stirring. 2.5 g / mol in terms of monomer charge, 53.0 g of 6% mass aqueous hydrogen peroxide solution (hereinafter referred to as “6% H ₂ O ₂ ”) 32 g / mol) and 72.8 g of an 1.8% by mass L-ascorbic acid aqueous solution (hereinafter referred to as “1.8% LAs”) (0.13 g / mol when converted to monomer input), respectively. It dripped from the dripping nozzle. The dropping time was 80% AA for 180 minutes, 30% MPA for 180 minutes, 6% H ₂ O ₂ for 215 minutes, and 1.8% LAs for 215 minutes. Further, during each dropping time, the dropping rate of each component was kept constant, and dropping was continuously performed. After completion of the dropwise addition, the reaction solution was kept at the boiling point reflux state (ripening) for an additional 30 minutes to complete the polymerization. After the completion of the polymerization, 241.7 g of pure water was added to the reaction solution, and then the reaction solution was allowed to cool and 65.7 g of an 80% by mass diethanolamine aqueous solution (5 mol% neutralized portion of acrylic acid) and 37% by mass hypophosphorous acid. 93.8 g of sodium acid aqueous solution (4.2% by mass with respect to 100% by mass of the solid content of the polymer composition) was gradually added dropwise to the reaction solution with stirring. As described above, the polyacrylic acid polymer (16) of the present invention was obtained. The aqueous solution had a solid content value of 46.0% and a weight average molecular weight (Mw) of 11,000.
When the whiteness at the time of drying of the polymer was evaluated by the above-mentioned method, the W value was 83.0.

<Comparative Example 1>
A SUS separable flask having a capacity of 2.5 liters equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer was charged with 343 g of pure water and 0.05 g of Mole salt (initial charge), and stirred at 90 ° C. The temperature was raised to. Subsequently, 945 g of an 80% by weight acrylic acid aqueous solution (that is, 10.5 mol) and 140 g of a 15% by weight aqueous sodium persulfate solution (2.0 g when converted to the amount of monomer charged) in a polymerization reaction system at a constant temperature of about 90 ° C. with stirring. / Mol), 150 g of 35% by weight sodium bisulfite aqueous solution (5.0 g / mol when converted to the amount of monomer charged) and 43.8 g of 48% by weight sodium hydroxide aqueous solution (5 mol% neutralized portion of acrylic acid) It dripped from each separate dripping nozzle. The dropping time was 80% AA for 180 minutes, 15% NaPS for 190 minutes, 35% SBS for 180 minutes, and 48% NaOH for 180 minutes. Further, during each dropping time, the dropping rate of each component was kept constant, and dropping was continuously performed. After completion of the dropwise addition, the reaction solution was kept at 90 ° C. (ripening) for an additional 30 minutes to complete the polymerization. After completion of the polymerization, the reaction solution was allowed to cool to 50 ° C., and 2.3 g of 35% by mass hydrogen peroxide was added dropwise to the reaction solution and sufficiently stirred. As described above, an aqueous solution of the comparative polyacrylic acid polymer (1) was obtained. The solid content of the aqueous solution was 51.8%, and the weight average molecular weight (Mw) was 4000.
When the whiteness degree at the time of drying of a polymer was evaluated by the above-mentioned method, W value was 74.7.

<Comparative Example 2>
A SUS separable flask having a capacity of 2.5 liters equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer was charged with 343 g of pure water and 0.05 g of Mole salt (initial charge), and stirred at 90 ° C. The temperature was raised to. Subsequently, 945 g of an 80% by weight acrylic acid aqueous solution (that is, 10.5 mol) and 140 g of a 15% by weight aqueous sodium persulfate solution (2.0 g when converted to the amount of monomer charged) in a polymerization reaction system at a constant temperature of about 90 ° C. with stirring. / Mol), 150 g of 35% by weight sodium bisulfite aqueous solution (5.0 g / mol when converted to the amount of monomer charged) and 43.8 g of 48% by weight sodium hydroxide aqueous solution (5 mol% neutralized portion of acrylic acid) It dripped from each separate dripping nozzle. The dropping time was 80% AA for 180 minutes, 15% NaPS for 190 minutes, 35% SBS for 180 minutes, and 48% NaOH for 180 minutes. Further, during each dropping time, the dropping rate of each component was kept constant, and dropping was continuously performed. After completion of the dropwise addition, the reaction solution was kept at 90 ° C. (ripening) for an additional 30 minutes to complete the polymerization. After completion of the polymerization, the reaction solution was allowed to cool, and 828 g of an 80% by weight diethanolamine aqueous solution (60 mol% neutralized portion of acrylic acid) was gradually added dropwise to the reaction solution while stirring to effect neutralization. The reaction solution was allowed to cool to 50 ° C., and 2.3 g of 35% by mass hydrogen peroxide was added dropwise to the reaction solution and sufficiently stirred. As described above, an aqueous solution of the comparative polyacrylic acid polymer (2) was obtained. The aqueous solution had a solid content value of 61.3% and a weight average molecular weight (Mw) of 4000.
When the whiteness of the polymer when dried was evaluated by the method described above, the W value was 75.4.

<Comparative Example 3>
A SUS separable flask having a capacity of 2.5 liters equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer was charged with 343 g of pure water and 0.05 g of Mole salt (initial charge), and stirred at 90 ° C. The temperature was raised to. Subsequently, 945 g of an 80% by weight acrylic acid aqueous solution (that is, 10.5 mol) and 140 g of a 15% by weight aqueous sodium persulfate solution (2.0 g when converted to the amount of monomer charged) in a polymerization reaction system at a constant temperature of about 90 ° C. with stirring. / Mol), 150 g of 35% by weight sodium bisulfite aqueous solution (5.0 g / mol when converted to the amount of monomer charged) and 43.8 g of 48% by weight sodium hydroxide aqueous solution (5 mol% neutralized portion of acrylic acid) It dripped from each separate dripping nozzle. The dropping time was 80% AA for 180 minutes, 15% NaPS for 190 minutes, 35% SBS for 180 minutes, and 48% NaOH for 180 minutes. Further, during each dropping time, the dropping rate of each component was kept constant, and dropping was continuously performed. After completion of the dropwise addition, the reaction solution was kept at 90 ° C. (ripening) for an additional 30 minutes to complete the polymerization. After completion of the polymerization, the reaction solution was allowed to cool, and a 37% sodium hypophosphite aqueous solution 84 g (3.6% by mass with respect to 100% by mass of the solid content of the polymer composition) was stirred and gradually added to the reaction solution. It was dripped. The reaction solution was allowed to cool to 50 ° C., and 2.3 g of 35% by mass hydrogen peroxide was added dropwise to the reaction solution and sufficiently stirred. As described above, an aqueous solution of the comparative polyacrylic acid polymer (3) was obtained. The solid content of the aqueous solution was 51.1%, and the weight average molecular weight (Mw) was 4000.
When the whiteness at the time of drying of a polymer was evaluated by the above-mentioned method, the W value was 74.0.

<Comparative example 4>
Into a 2.5 liter SUS separable flask equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer, 304.7 g of pure water was charged (initial charge), and the temperature was raised to the boiling point with stirring. Next, 810 g of an 80% by mass acrylic acid aqueous solution (that is, 9.0 mol) and 42.6 g of an aqueous 15% by mass sodium persulfate solution (0.7 g when converted to the amount of monomer added) in the polymerization reaction system in a boiling point reflux state with stirring. / Mol) and 100 g of a 37 mass% sodium hypophosphite aqueous solution (4.1 g / mol when converted to the amount of monomer added) were dropped from separate dropping nozzles. The dropping time was 80% AA for 180 minutes, 15% NaPS for 185 minutes, and 37% SHP for 180 minutes. Further, during each dropping time, the dropping rate of each component was kept constant, and dropping was continuously performed. After completion of the dropwise addition, the reaction solution was kept at the boiling point reflux state (ripening) for an additional 30 minutes to complete the polymerization. After completion of the polymerization, 135 g of pure water was added to the reaction solution. As described above, an aqueous solution of the comparative polyacrylic acid polymer (4) was obtained. The solid content of the aqueous solution was 49.7%, and the weight average molecular weight (Mw) was 4000.
When the whiteness at the time of drying of a polymer was evaluated by the above-mentioned method, W value was 68.7.

<Comparative Example 5>
Into a 2.5 liter SUS separable flask equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer, 304.7 g of pure water was charged (initial charge), and the temperature was raised to the boiling point with stirring. Next, 810 g of an 80% by mass acrylic acid aqueous solution (that is, 9.0 mol) and 42.6 g of an aqueous 15% by mass sodium persulfate solution (0.7 g when converted to the amount of monomer added) in the polymerization reaction system in a boiling point reflux state with stirring. / Mol) and 100 g of a 37 mass% sodium hypophosphite aqueous solution (4.1 g / mol when converted to the amount of monomer added) were dropped from separate dropping nozzles. The dropping time was 80% AA for 180 minutes, 15% NaPS for 185 minutes, and 37% SHP for 180 minutes. Further, during each dropping time, the dropping rate of each component was kept constant, and dropping was continuously performed. After completion of the dropwise addition, the reaction solution was kept at the boiling point reflux state (ripening) for an additional 30 minutes to complete the polymerization. After completion of the polymerization, 135 g of pure water was added to the reaction solution, and then 709.7 g of an 80% by mass diethanolamine aqueous solution (60 mol% neutralized portion of acrylic acid) was gradually added to the reaction solution with stirring while the reaction solution was allowed to cool. Neutralization was carried out by adding dropwise. As described above, an aqueous solution of the comparative polyacrylic acid polymer (5) was obtained. The solid content of the aqueous solution was 59.9%, and the weight average molecular weight (Mw) was 4000.
When the whiteness degree at the time of drying of a polymer was evaluated by the above-mentioned method, W value was 74.2.

<Comparative Example 6>
Into a 2.5 liter SUS separable flask equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer, 304.7 g of pure water was charged (initial charge), and the temperature was raised to the boiling point with stirring. Next, 810 g of an 80% by mass acrylic acid aqueous solution (that is, 9.0 mol) and 42.6 g of an aqueous 15% by mass sodium persulfate solution (0.7 g when converted to the amount of monomer added) in the polymerization reaction system in a boiling point reflux state with stirring. / Mol) and 100 g of a 37 mass% sodium hypophosphite aqueous solution (4.1 g / mol when converted to the amount of monomer added) were dropped from separate dropping nozzles. The dropping time was 80% AA for 180 minutes, 15% NaPS for 185 minutes, and 37% SHP for 180 minutes. Further, during each dropping time, the dropping rate of each component was kept constant, and dropping was continuously performed. After completion of the dropwise addition, the reaction solution was kept at the boiling point reflux state (ripening) for an additional 30 minutes to complete the polymerization. After the completion of the polymerization, 135 g of pure water was added to the reaction solution, and then the reaction solution was allowed to cool and 72 g of a 37 mass% sodium hypophosphite aqueous solution (3.7 mass relative to 100 mass% of the solid content of the polymer composition). %) Was gradually added dropwise to the reaction solution with stirring. As described above, an aqueous solution of the comparative polyacrylic acid polymer (6) was obtained. The aqueous solution had a solid content value of 49.1% and a weight average molecular weight (Mw) of 4000.
When the whiteness at the time of drying of a polymer was evaluated by the above-mentioned method, the W value was 70.8.

<Comparative Example 7>
In a 2.5 liter SUS separable flask equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer, 341.1 g of pure water was charged (initial charge), and the temperature was raised to the boiling point with stirring. Subsequently, 900 g of an 80% by weight acrylic acid aqueous solution (that is, 10.0 mol) and 50 g of a 15% by weight aqueous sodium persulfate aqueous solution (0.75 g / mol when converted to the amount of monomer charged) in the polymerization reaction system in a boiling point reflux state with stirring. ) And 49 g of a 37 mass% sodium hypophosphite aqueous solution (1.8 g / mol when converted to the amount of monomer added) were added dropwise from separate dropping nozzles. The dropping time was 80% AA for 180 minutes, 15% NaPS for 185 minutes, and 37% SHP for 180 minutes. Further, during each dropping time, the dropping rate of each component was kept constant, and dropping was continuously performed. After completion of the dropwise addition, the reaction solution was kept at the boiling point reflux state (ripening) for an additional 30 minutes to complete the polymerization. After completion of the polymerization, 210 g of pure water was added to the reaction solution and sufficiently stirred. As described above, an aqueous solution of a comparative polyacrylic acid polymer (7) was obtained. The solid content of the aqueous solution was 48.0%, and the weight average molecular weight (Mw) was 15000.
When the whiteness of the polymer when dried was evaluated by the method described above, the W value was 66.4.

<Comparative Example 8>
In a 2.5 liter SUS separable flask equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer, 341.1 g of pure water was charged (initial charge), and the temperature was raised to the boiling point with stirring. Subsequently, 900 g of an 80% by weight acrylic acid aqueous solution (that is, 10.0 mol) and 50 g of a 15% by weight aqueous sodium persulfate aqueous solution (0.75 g / mol when converted to the amount of monomer charged) in the polymerization reaction system in a boiling point reflux state with stirring. ) And 49 g of a 37 mass% sodium hypophosphite aqueous solution (1.8 g / mol when converted to the amount of monomer added) were added dropwise from separate dropping nozzles. The dropping time was 80% AA for 180 minutes, 15% NaPS for 185 minutes, and 37% SHP for 180 minutes. Further, during each dropping time, the dropping rate of each component was kept constant, and dropping was continuously performed. After completion of the dropwise addition, the reaction solution was kept at the boiling point reflux state (ripening) for an additional 30 minutes to complete the polymerization. After completion of the polymerization, 210 g of pure water was added to the reaction solution, and then the reaction solution was allowed to cool, and 788.6 g of 80% by mass diethanolamine aqueous solution (60 mol% neutralized portion of acrylic acid) was gradually added to the reaction solution while stirring. Neutralization was carried out by adding dropwise. As described above, an aqueous solution of the comparative polyacrylic acid polymer (8) was obtained. The individual fraction value of the aqueous solution was 58.8%, and the weight average molecular weight (Mw) was 15000.
When the whiteness degree at the time of drying of a polymer was evaluated by the above-mentioned method, W value was 74.2.

<Comparative Example 9>
In a 2.5 liter SUS separable flask equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer, 341.1 g of pure water was charged (initial charge), and the temperature was raised to the boiling point with stirring. Subsequently, 900 g of an 80% by weight acrylic acid aqueous solution (that is, 10.0 mol) and 50 g of a 15% by weight aqueous sodium persulfate aqueous solution (0.75 g / mol when converted to the amount of monomer charged) in the polymerization reaction system in a boiling point reflux state with stirring. ) And 49 g of a 37 mass% sodium hypophosphite aqueous solution (1.8 g / mol when converted to the amount of monomer added) were added dropwise from separate dropping nozzles. The dropping time was 80% AA for 180 minutes, 15% NaPS for 185 minutes, and 37% SHP for 180 minutes. Further, during each dropping time, the dropping rate of each component was kept constant, and dropping was continuously performed. After completion of the dropwise addition, the reaction solution was kept at the boiling point reflux state (ripening) for an additional 30 minutes to complete the polymerization. After the completion of the polymerization, 210 g of pure water was added to the reaction solution, and then the reaction solution was allowed to cool and 80 g of a 37 mass% sodium hypophosphite aqueous solution (3.9 mass with respect to 100 mass% of the solid content of the polymer composition). %) Was gradually added dropwise to the reaction solution with stirring. As described above, an aqueous solution of a comparative polyacrylic acid polymer (9) was obtained. The solid content of the aqueous solution was 47.5%, and the weight average molecular weight (Mw) was 15000.
When the whiteness at the time of drying of a polymer was evaluated by the above-mentioned method, the W value was 71.4.

<Comparative Example 10>
In a 2.5 liter SUS separable flask equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer, 341.1 g of pure water was charged (initial charge), and the temperature was raised to the boiling point with stirring. Subsequently, 900 g of an 80% by weight acrylic acid aqueous solution (that is, 10.0 mol) and 50 g of a 15% by weight aqueous sodium persulfate aqueous solution (0.75 g / mol when converted to the amount of monomer charged) in the polymerization reaction system in a boiling point reflux state with stirring. ) And 49 g of a 37 mass% sodium hypophosphite aqueous solution (1.8 g / mol when converted to the amount of monomer added) were added dropwise from separate dropping nozzles. The dropping time was 80% AA for 180 minutes, 15% NaPS for 185 minutes, and 37% SHP for 180 minutes. Further, during each dropping time, the dropping rate of each component was kept constant, and dropping was continuously performed. After completion of the dropwise addition, the reaction solution was kept at the boiling point reflux state (ripening) for an additional 30 minutes to complete the polymerization. After completion of the polymerization, 210 g of pure water was added to the reaction solution, and then 83.3 g of a 48% by mass aqueous sodium hydroxide solution (10 mol% neutralized portion of acrylic acid) was stirred into the reaction solution while cooling the reaction solution. The mixture was gradually added dropwise for neutralization. As described above, an aqueous solution of the comparative polyacrylic acid polymer (10) was obtained. The solid content of the aqueous solution was 46.9%, and the weight average molecular weight (Mw) was 15000.
When the whiteness of the polymer when dried was evaluated by the method described above, the W value was 75.4.

<Comparative Example 11>
A 2.5-liter SUS separable flask equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer was charged with 325.0 g of pure water (initial charge), and the temperature was raised to the boiling point with stirring. Subsequently, 900 g of an 80% by mass acrylic acid aqueous solution (that is, 10.0 mol%) and 83.3 g of a 30% by mass mercaptopropionic acid aqueous solution (hereinafter referred to as “30% MPA”) in a polymerization reaction system in a boiling point reflux state with stirring. 2.5 g / mol in terms of monomer charge, 53.0 g of 6% mass aqueous hydrogen peroxide solution (hereinafter referred to as “6% H ₂ O ₂ ”) 32 g / mol) and 72.8 g of an 1.8% by mass L-ascorbic acid aqueous solution (hereinafter referred to as “1.8% LAs”) (0.13 g / mol when converted to monomer input), respectively. It dripped from the dripping nozzle. The dropping time was 80% AA for 180 minutes, 30% MPA for 180 minutes, 6% H ₂ O ₂ for 215 minutes, and 1.8% LAs for 215 minutes. Further, during each dropping time, the dropping rate of each component was kept constant, and dropping was continuously performed. After completion of the dropwise addition, the reaction solution was kept at the boiling point reflux state (ripening) for an additional 30 minutes to complete the polymerization. After completion of the polymerization, 241.7 g of pure water was added to the reaction solution. As described above, a comparative polyacrylic acid polymer (11) was obtained. The solid content of the aqueous solution was 44.7%, and the weight average molecular weight (Mw) was 11000.
When the whiteness degree at the time of drying of a polymer was evaluated by the above-mentioned method, W value was 61.9.

<Comparative Example 12>
A 2.5-liter SUS separable flask equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer was charged with 325.0 g of pure water (initial charge), and the temperature was raised to the boiling point with stirring. Subsequently, 900 g of an 80% by mass acrylic acid aqueous solution (that is, 10.0 mol%) and 83.3 g of a 30% by mass mercaptopropionic acid aqueous solution (hereinafter referred to as “30% MPA”) in a polymerization reaction system in a boiling point reflux state with stirring. 2.5 g / mol in terms of monomer charge, 53.0 g of 6% mass aqueous hydrogen peroxide solution (hereinafter referred to as “6% H ₂ O ₂ ”) 32 g / mol) and 72.8 g of an 1.8% by mass L-ascorbic acid aqueous solution (hereinafter referred to as “1.8% LAs”) (0.13 g / mol when converted to monomer input), respectively. It dripped from the dripping nozzle. The dropping time was 80% AA for 180 minutes, 30% MPA for 180 minutes, 6% H ₂ O ₂ for 215 minutes, and 1.8% LAs for 215 minutes. Further, during each dropping time, the dropping rate of each component was kept constant, and dropping was continuously performed. After completion of the dropwise addition, the reaction solution was kept at the boiling point reflux state (ripening) for an additional 30 minutes to complete the polymerization. After completion of the polymerization, 653.0 g of pure water was added to the reaction solution, and then the reaction solution was allowed to cool, and 788.6 g of 80% by mass diethanolamine aqueous solution (60 mol% neutralized portion of acrylic acid) was stirred into the reaction solution. The mixture was gradually dropped to neutralize. A comparative polyacrylic acid polymer (12) was obtained as described above. The solid content of the aqueous solution was 48.0%, and the weight average molecular weight (Mw) was 11000.
When the whiteness degree at the time of drying of a polymer was evaluated by the above-mentioned method, W value was 72.4.

<Comparative Example 13>
A 2.5-liter SUS separable flask equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer was charged with 325.0 g of pure water (initial charge), and the temperature was raised to the boiling point with stirring. Subsequently, 900 g of an 80% by mass acrylic acid aqueous solution (that is, 10.0 mol%) and 83.3 g of a 30% by mass mercaptopropionic acid aqueous solution (hereinafter referred to as “30% MPA”) in a polymerization reaction system in a boiling point reflux state with stirring. 2.5 g / mol in terms of monomer charge, 53.0 g of 6% mass aqueous hydrogen peroxide solution (hereinafter referred to as “6% H ₂ O ₂ ”) 32 g / mol) and 72.8 g of an 1.8% by mass L-ascorbic acid aqueous solution (hereinafter referred to as “1.8% LAs”) (0.13 g / mol when converted to monomer input), respectively. It dripped from the dripping nozzle. The dropping time was 80% AA for 180 minutes, 30% MPA for 180 minutes, 6% H ₂ O ₂ for 215 minutes, and 1.8% LAs for 215 minutes. Further, during each dropping time, the dropping rate of each component was kept constant, and dropping was continuously performed. After completion of the dropwise addition, the reaction solution was kept at the boiling point reflux state (ripening) for an additional 30 minutes to complete the polymerization. After the completion of the polymerization, 231.4 g of pure water was added to the reaction solution, and then the reaction solution was allowed to cool and 87.7 g of a 37 mass% sodium hypophosphite aqueous solution (based on 100 mass% of the solid content of the polymer composition). (4.2% by mass) was gradually added dropwise to the reaction solution with stirring. A comparative polyacrylic acid polymer (13) was obtained as described above. The solid content of the aqueous solution was 45.0%, and the weight average molecular weight (Mw) was 11000.
When the whiteness of the polymer when dried was evaluated by the method described above, the W value was 63.7.

  The production results and physical properties of the polymer are summarized in Table 1.

  As is apparent from Table 1, the polymer of the present invention is superior in hue stability during heating as compared with conventional polymers. Therefore, the polymer of the present invention can be preferably blended in a powder detergent composition.

Claims (7)

A poly (meth) acrylic acid polymer,
1-45 mol% of the carboxyl group of the poly (meth) acrylic acid polymer is neutralized with an organic amine,
The poly (meth) acrylic acid-based polymer has at least one main chain terminal having a —S—R ₀ —COOM group (where R ₀ represents an alkylene group having 1 to 5 carbon atoms, M is a hydrogen atom, metal atom, an ammonium salt, poly characterized by having a represents an organic amine salt) (meth) acrylic acid-based polymer. A poly (meth) acrylic acid polymer,
1-45 mol% of the carboxyl group of the poly (meth) acrylic acid polymer is neutralized with an organic amine,
The poly (meth) acrylic acid polymer has a sulfonic acid (salt) group at at least one main chain terminal, and has a weight average molecular weight of 1,000 to 4,000. ) Acrylic acid polymer. The poly (meth) acrylic acid polymer according to claim 1, wherein the poly (meth) acrylic acid polymer has a weight average molecular weight of 1,000 to 8,000. A detergent builder comprising the poly (meth) acrylic acid polymer according to any one of claims 1 to 3 . A detergent composition comprising the poly (meth) acrylic acid polymer according to any one of claims 1 to 3 and a surfactant. A detergent builder comprising a poly (meth) acrylic acid polymer,
2 to 12 mol% of the carboxyl group of the poly (meth) acrylic acid polymer is neutralized with an organic amine,
The poly (meth) acrylic acid polymer has at least one main chain terminal, a sulfonic acid (salt) group, a hypophosphorous acid (salt) group, a —S—R ₀ —COOM group (where R ₀ is A detergent builder having one or more groups selected from the group consisting of an alkylene group having 1 to 5 carbon atoms, wherein M represents a hydrogen atom, a metal atom, an ammonium salt, or an organic amine salt. A detergent composition comprising a poly (meth) acrylic acid polymer and a surfactant,
2 to 12 mol% of the carboxyl group of the poly (meth) acrylic acid polymer is neutralized with an organic amine,
The poly (meth) acrylic acid polymer has at least one main chain terminal, a sulfonic acid (salt) group, a hypophosphorous acid (salt) group, a —S—R ₀ —COOM group (where R ₀ is A detergent composition comprising one or more groups selected from the group consisting of an alkylene group having 1 to 5 carbon atoms, wherein M represents a hydrogen atom, a metal atom, an ammonium salt, or an organic amine salt). .