JP2013194158A - Polycarboxylic acid-based polymer composition and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polycarboxylic acid-based polymer composition, capable of preventing a detergent composition from becoming sticky even when blended to the detergent composition at a high composition ratio.SOLUTION: A polycarboxylic acid-based polymer composition has a moisture absorptivity in a dry state of less than 30%, and a sodium sulfate content of 0 mass% or more and less than 2.5 mass% relative to the solid content of the polycarboxylic acid-based polymer composition.

Description

The present invention relates to a polycarboxylic acid polymer composition and a method for producing the same.

Conventionally, among polycarboxylic acid-based polymers such as (meth) acrylic acid-based polymers, low molecular weight ones use detergent builder, inorganic pigments and metal ions by utilizing their excellent chelating ability and dispersing ability. It is suitably used for dispersants such as the above and scale inhibitors.

For example, in Cited Document 1, 50 to 100 mol% (meth) acrylic acid and 0 to 50 mol% of a water-soluble monoethylenically unsaturated monomer copolymerizable with (meth) acrylic acid are polymerized in an aqueous solution. And having a sulfonic acid group at the terminal, and having a gel resistance Q value defined by the following formula: Q = degree of gelation × 10 ⁵ / weight average molecular weight is less than 2.0 A (meth) acrylic acid polymer characterized by the following is disclosed. It is disclosed that the polymer exhibits good gel resistance in addition to high chelating ability and dispersibility.

  For example, Patent Document 2 discloses (meth) acrylic acid characterized in that the sulfur element introduction amount S value defined by S = (S amount contained in polymer) / (total S amount) × 100 is 35 or more. System polymers are disclosed. It is disclosed that the polymer exhibits good gel resistance in addition to high chelating ability and dispersibility.

JP-A-11-315115 JP 2004-75971 A

As described above, various polycarboxylic acid polymers (compositions) have been reported so far, but for example, a large amount of polycarboxylic acid polymer (composition) was added to a powder detergent composition. In this case, since the hygroscopicity of the polycarboxylic acid polymer (composition) is relatively high, the texture of the powder detergent composition may be impaired (a sticky feeling may occur). Therefore, the blending amount of the polycarboxylic acid polymer (composition) may not be increased sufficiently.
Accordingly, the present invention provides a polycarboxylic acid polymer (composition) that can be incorporated into a powder detergent composition more because it has a lower hygroscopicity than the conventional polycarboxylic acid polymer (composition). The purpose is to provide.

As a result of intensive studies on various polymers (compositions) in order to achieve the above object, the present inventors have made a polycarboxylic acid polymer composition produced so that a specific impurity is in a specific range. Was found to exhibit excellent moisture absorption properties (low moisture absorption), and the present invention was completed based on the findings.
That is, the present invention is a composition containing a polycarboxylic acid polymer, wherein the moisture absorption rate during drying is less than 30%, and the content of sodium sulfate is the solid content of the polycarboxylic acid polymer composition. It is a polycarboxylic acid polymer composition that is 0% by mass or more and less than 2.5% by mass relative to the mass.

The polycarboxylic acid polymer (composition) of the present invention has excellent moisture absorption properties (low moisture absorption). Therefore, it can be usefully used, for example, as an additive (in particular, a detergent builder) of a detergent composition.

Hereinafter, the present invention will be described in detail.

[Polycarboxylic Acid Polymer (Composition) of the Present Invention]
<Polycarboxylic acid polymer of the present invention>
The polycarboxylic acid polymer composition of the present invention contains a polycarboxylic acid polymer (hereinafter, also referred to as “polycarboxylic acid polymer of the present invention”) as an essential component.
The polycarboxylic acid polymer of the present invention has a structural unit (a) derived from the carboxyl group-containing monomer (A). In the present invention, the carboxyl group-containing monomer (A) is a monomer that essentially contains 1) a carbon-carbon unsaturated double bond and 2) a carboxyl group and / or a salt thereof. Specifically, unsaturated monocarboxylic acids and their salts such as acrylic acid, methacrylic acid, crotonic acid, α-hydroxyacrylic acid, α-hydroxymethylacrylic acid and derivatives thereof; itaconic acid, fumaric acid, malee Examples thereof include unsaturated dicarboxylic acids such as acid and 2-methyleneglutaric acid, and salts thereof.

  The 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 While maintaining the performance of the polycarboxylic acid polymer of the present invention as a detergent builder, the hygroscopic property tends to be improved (the hygroscopic rate is lowered), so among the salts, sodium salts, potassium salts, and diethanolamine are preferred. Salt, triethanolamine salt.

Among the carboxyl group-containing monomers (A), the performance as a detergent builder (such as dispersibility of dirt particles) tends to be high, so acrylic acid, acrylate, methacrylic acid, methacrylate, maleic acid Maleate is preferable, and it is more preferable to use acrylic acid, acrylic acid salt, methacrylic acid, and methacrylic acid salt (these are also referred to as “(meth) acrylic acid (salt)”).
The polycarboxylic acid polymer of the present invention may contain only one type of structural unit (a), but may contain two or more types.
In the structural unit (a), the unsaturated double bond (eg, CH ₂ ═C (R ₁ ) —) of the monomer (A) is a single bond (eg, —CH ₂ —C (R ₁ ) —). This is the structure.

  In the polycarboxylic acid polymer of the present invention, the structural unit (a) derived from the carboxyl group-containing monomer (A) is 100 mol% in total of the structural units derived from all monomers (that is, the carboxyl group-containing single monomer). It is preferable to have a proportion of 50 mol% or more and 100 mol% or less with respect to 100 mol% in total of the structural units derived from the body and the structural units derived from other monomers. When the structural unit (a) is within the above range, the performance as a detergent builder (such as dispersibility of dirt particles) tends to be improved. The ratio of the structural unit (a) to the total of 100 mol% of the structural units derived from all monomers is more preferably 80 mol% or more and 100 mol% or less, and 90 mol% or more and 100 mol% or less. More preferably, it is particularly preferably 100 mol%.

  The polycarboxylic acid polymer of the present invention preferably contains structural units derived from (meth) acrylic acid (salt) as structural units derived from the carboxyl group-containing monomer as described above. It is preferable that the structural unit derived from (meth) acrylic acid (salt) is 50 mol% or more and 100 mol% or less with respect to a total of 100 mol% of the structural units derived from the monomer, and 80 mol% or more. 100 mol% or less is more preferable, 90 mol% or more and 100 mol% or less is more preferable, and 100 mol% is particularly preferable.

  When the polycarboxylic acid polymer of the present invention includes a structural unit derived from (meth) acrylic acid (salt), the polycarboxylic acid polymer may further include a structural unit derived from maleic acid (salt). The maleic acid (salt) refers to maleic acid (acid type), maleic acid monosalt, maleic acid disalt. When the carboxyl group-containing monomer of the present invention includes a structural unit derived from (meth) acrylic acid (salt), the mol% of the structural unit derived from maleic acid (salt) further included is derived from all monomers. It is preferably 0 mol% or more and 50 mol% or less, more preferably 0 mol% or more and 20 mol% or less, and more preferably 0 mol% or more and 10 mol% with respect to 100 mol% of the total structural units. The content is more preferably as follows, and particularly preferably 0 mol%.

The polycarboxylic acid polymer of the present invention may have a structural unit (e) derived from other monomer (E).
As the other monomer (E) when the polycarboxylic acid-based polymer of the present invention contains another monomer (E), it is particularly preferable that it can be copolymerized with the monomer (A). It is not limited and is appropriately selected depending on the desired effect. Specifically, sulfonic acid group-containing monomers such as 3-allyloxy-2-hydroxypropanesulfonic acid, (meth) allylsulfonic acid, isoprenesulfonic acid, vinylsulfonic acid, styrenesulfonic acid, and salts thereof; ) Monomers obtained by adding alkylene oxide to unsaturated alcohols such as allyl alcohol and isoprenol, polyalkylene glycol monomers such as polyalkylene glycol esters of (meth) acrylic acid; N-vinylpyrrolidone, N-vinylformamide N-vinyl monomers such as N-vinylacetamide, N-vinyl-N-methylformamide, N-vinyl-N-methylacetamide, N-vinyloxazolidone; (meth) acrylamide, N, N-dimethylacrylamide, N -Acrylic such as isopropylacrylamide Amide monomers; (meth) acrylic acid alkyl ester monomers such as butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dodecyl (meth) acrylate; 2-hydroxyethyl (meth) acrylate, 2- Hydroxypropyl (meth) acrylates such as hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, hydroxypentyl (meth) acrylate, etc. Monomers: Vinyl aromatic amino group-containing monomers having a heterocyclic aromatic hydrocarbon group and a polymerizable group such as vinyl pyridine and vinyl imidazole, and quaternized products and salts thereof; diallylamine, diallyldimethylamine, etc. Allylamines and These quaternized compounds and salts; (i) (meth) allyl glycidyl ether, isoprenyl glycidyl ether, vinyl glycidyl ether epoxy ring, (ii) dimethylamine, diethylamine, diisopropylamine, di-n-butylamine, etc. Monomers obtained by reacting amines such as alkanolamines such as amines, diethanolamines, diisopropanolamines, cyclic amines such as morpholine and pyrrole, and quaternized products and salts thereof; styrene, indene, vinylaniline, etc. Vinyl aryl monomer, isobutylene, vinyl acetate; and the like.
Moreover, the said other monomer (E) may be used individually by 1 type, or may be used with the form of a 2 or more types of mixture.

  The polycarboxylic acid polymer of the present invention is optional, but the above structural unit (e) is 0 mol% or more and 50 mol% or less with respect to 100 mol% of the total structural units derived from all monomers. You may have in ratio. It is more preferably 0 mol% or more and 20 mol% or less, further preferably 0 mol% or more and 10 mol% or less, and particularly preferably 0 mol%.

  The weight average molecular weight of the polycarboxylic acid-based polymer of the present invention can be appropriately set and is not particularly limited. However, since the performance as a detergent builder (such as dispersibility of dirt particles) tends to be improved, it is specifically Specifically, it is preferably 2,000 to 200,000, more preferably 3,000 to 60,000, and most preferably 4,000 to 40,000. 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.

<Sodium sulfate>
In the polycarboxylic acid polymer composition of the present invention, the content of sodium sulfate is 0% by mass or more and less than 2.5% by mass with respect to 100% by mass of the solid content of the polycarboxylic acid polymer composition. It is characterized by that. By producing so that the content of sodium sulfate is in the above range, the hygroscopic property of the polycarboxylic acid polymer composition is remarkably improved (the hygroscopic rate is lowered). The content of sodium sulfate is preferably 0% by mass or more and less than 2.3% by mass, more preferably 0.1% by mass or more and less than 2.1% by mass, and further preferably 0.2% by mass. % Or more and less than 1.8% by mass, most preferably 0.3% by mass or more and less than 1.5% by mass. The content of sodium sulfate is mass calculated assuming that there is no hydrate even if it is a hydrate of sodium sulfate.
By manufacturing with the manufacturing method mentioned later, content of sodium sulfate can be made into said range.
In the present invention, the content of sodium sulfate is measured by the method described later.

<Other ingredients>
The polycarboxylic acid polymer composition of the present invention contains the polycarboxylic acid polymer of the present invention as an essential component. The polycarboxylic acid polymer composition of the present invention can contain any component in addition to the polycarboxylic acid polymer of the present invention. 1) selected from the by-products during polymerization and water.
A preferable form of the polycarboxylic acid polymer composition of the present invention is a form containing 20 to 80% by mass of the polycarboxylic acid polymer of the present invention and 20 to 80% by mass of water.
In the polycarboxylic acid-based 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.

<Hygroscopic rate>
The polycarboxylic acid polymer composition of the present invention is characterized by excellent moisture absorption properties (low moisture absorption), and the moisture absorption is preferably 29% or less, more preferably 28% or less, and still more preferably. 27% or less. The moisture absorption rate in the present invention is obtained by a measurement method described later.

[Production Method of Polycarboxylic Acid Polymer (Composition) of the Present Invention]
The production method of the polycarboxylic acid-based polymer (composition) of the present invention can be the same as a known polymerization method or a modified method unless otherwise specified. As a method for producing the polycarboxylic acid polymer (composition) of the present invention, a step of polymerizing a monomer (monomer component) containing a carboxyl group-containing monomer as an essential component (polymerization step) is essential. It can manufacture by including. Further, when the monomer component is polymerized, the other monomer (E) may be further copolymerized as necessary.

In such a production method, the monomer component may be polymerized using a polymerization initiator. In addition, the kind and usage-amount of the monomer contained in a monomer component are set suitably so that the structural unit which comprises a polycarboxylic acid-type polymer may become as above-mentioned.
The composition ratio of the carboxyl group-containing monomer used in the production of the polycarboxylic acid polymer (composition) of the present invention is the total monomer (that is, the carboxyl group-containing monomer and other monomers). The total carboxyl group-containing monomer is preferably 50 mol% or more and 100 mol% or less, more preferably 80 mol% or more and 100 mol% or less, and 90 mol% relative to 100 mol%. As mentioned above, it is more preferable that it is 100 mol% or less, and it is especially preferable that it is 100 mol%. The composition ratio of other monomers used in the production of the polycarboxylic acid polymer (composition) of the present invention is such that the other monomers are 0 mol% or more with respect to 100 mol% of all monomers, It is preferably 50 mol% or less, more preferably 0 mol% or more and 20 mol% or less, further preferably 0 mol% or more and 10 mol% or less, and particularly preferably 0 mol%. preferable.

  Since the performance as a detergent builder of the polycarboxylic acid polymer (composition) of the present invention tends to improve, the carboxyl group-containing monomer preferably contains (meth) acrylic acid (salt). . The composition ratio of (meth) acrylic acid (salt) used in the production of the polycarboxylic acid polymer (composition) of the present invention is (meth) acrylic acid (salt) with respect to 100 mol% of all monomers. Is preferably 50 mol% or more and 100 mol% or less, more preferably 80 mol% or more and 100 mol% or less, still more preferably 90 mol% or more and 100 mol% or less, and even more preferably 100 mol% % Is particularly preferred.

  When the carboxyl group-containing monomer contains (meth) acrylic acid (salt), it may further contain maleic acid (salt). Maleic acid (salt) represents maleic acid (acid type), maleic acid monosalt, maleic acid disalt. When the carboxyl group-containing monomer contains (meth) acrylic acid (salt), the composition ratio of maleic acid (salt) used in the production of the polycarboxylic acid polymer (composition) of the present invention is as follows. Maleic acid (salt) is preferably 0 mol% or more and 50 mol% or less, more preferably 0 mol% or more and 20 mol% or less, and more preferably 0 mol% or more with respect to 100 mol% of the monomer. More preferably, it is 10 mol% or less, and especially preferably 0 mol%.

In the method for producing a polycarboxylic acid polymer (composition) of the present invention, the polymerization solvent to be used preferably contains water, and water is contained in an amount of 50% by mass or more and 100% by mass with respect to the total amount of the solvent used. It is preferable to use it, and it is preferable that the total amount of the solvent used is water.
Organic solvents that can be used alone or in combination with water include lower alcohols such as methanol, ethanol and isopropyl alcohol; lower ketones such as acetone, methyl ethyl ketone and diethyl 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, 40-200 mass% is preferable with respect to a total of 100 mass% 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 may be decreased and the solvent may be required to be removed. There is.

As a polymerization initiator used in the method for producing the polycarboxylic acid polymer (composition) of the present invention, the performance of the polycarboxylic acid polymer (composition) of the present invention as a detergent builder (dispersion of dirt particles) Persulfate is used as an essential component. Examples of the persulfate include persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate.
In the method for producing the polycarboxylic acid polymer (composition) of the present invention, a known polymerization initiator can be used together with the persulfate, and examples of the known polymerization initiator include hydrogen peroxide; 2,2′-azobis (2-amidinopropane) hydrochloride, 4,4′-azobis-4-cyanoparerenic acid, azobisisobutyronitrile, 2,2′-azobis (4-methoxy-2,4-dimethyl) Azo compounds such as valeronitrile); organic peroxides such as benzoyl peroxide, lauroyl peroxide, peracetic acid, di-t-butyl peroxide, cumene hydroperoxide and the like. These polymerization initiators may be used alone or in combination of two or more.

  In the method for producing a polycarboxylic acid polymer (composition) of the present invention, the amount of persulfate used is 1 mol of all monomers (total of carboxyl group-containing monomers and other monomers). 0.1 g or more and 4.0 g or less. When used in the above range, the hygroscopic property of the polycarboxylic acid polymer (composition) of the present invention tends to be improved (the hygroscopic rate is lowered). Preferably, it is 0.2 g or more and 3.5 g or less, More preferably, it is 0.3 g or more and 3.0 g or less.

  The total amount of polymerization initiator used when a polymerization initiator other than persulfate is used is not particularly limited as long as the amount of persulfate used is in the above range, but preferably 1 mol of all monomers. The amount of residual monomer and impurities in the polymer composition of the present invention tends to be reduced, and particularly preferably 0.1 to 4 g. It is.

The polycarboxylic acid polymer (composition) of the present invention 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, 2-mercaptopropionic acid, 3-mercaptopropionic acid, and n-dodecyl mercaptan; carbon tetrachloride, methylene chloride, bromoform, Halogens such as bromotrichloroethane; secondary alcohols such as isopropanol and glycerin; phosphorous acid, hypophosphorous acid, and salts thereof (sodium hypophosphite, potassium hypophosphite, etc.); sulfurous acid, heavy Sulfite, dithionite, metabisulfite, sulfite, thiosulfate (specifically, sodium bisulfite, potassium bisulfite, sodium dithionite, potassium dithionite, sodium metabisulfite, Etc. (also referred to as “bisulfite (salts)”); and the like. The chain transfer agents may be used alone or in combination of two or more.
As a preferable chain transfer agent, since the performance (dispersibility of dirty particles, etc.) of the resulting polycarboxylic acid polymer (composition) as a detergent builder tends to be improved, hypophosphorous acid (salt) ( Hydrates) and bisulfites (salts) are preferred.

  The amount of the chain transfer agent used is preferably the total amount of the chain transfer agent and the polymerization initiator used relative to 1 mol of all monomers (the total of carboxyl group-containing monomers and other monomers). However, it is preferably 5.0 g or less, more preferably 4.0 g or less, further preferably 3.5 g or less, and particularly preferably 3.0 g or less. On the other hand, the lower limit of the total amount of the chain transfer agent and the polymerization initiator used is particularly preferably 2.0 g or more per 1 mol of all monomers. By making it into the above-mentioned range, the resulting polymer (composition) tends to have good moisture absorption characteristics as a detergent builder (lower moisture absorption).

In the method for producing a polycarboxylic acid polymer (composition) of the present invention, heavy metal ions 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. As said metal ion, iron, cobalt, manganese, chromium, molybdenum, tungsten, copper, silver, gold, lead, platinum, iridium, osmium, palladium, rhodium, ruthenium etc. are preferable, for example. These heavy metals can be used alone or in combination of two or more. Among these, iron is more preferable. The ionic valence of the heavy metal ions is not particularly limited. For example, when iron is used as the heavy metal, the iron ions in the initiator may be Fe ²⁺ or Fe ³⁺ , and these may be combined. May be.
The heavy metal ions are not particularly limited as long as they are included in the form of ions. However, it is preferable to use a method using a solution in which a heavy metal compound is dissolved because the handleability is excellent.
When iron is used as the heavy metal ion, the mole salt (Fe (NH ₄ ) ₂ (SO ₄ ) ₂ · 6H ₂ O), ferrous sulfate · 7 hydrate, ferrous chloride, ferric chloride, etc. It is preferable to use a heavy metal compound or the like. Moreover, when using manganese as a heavy metal ion, manganese chloride etc. can be used suitably. In the case of using these heavy metal compounds, since they are water-soluble compounds, they can be used in the form of an aqueous solution and have excellent handleability. The solvent of the solution obtained by dissolving the heavy metal compound is not limited to water.

When using the said heavy metal ion, it is preferable that the usage-amount is 0-10 ppm with respect to the total mass of the polymerization reaction liquid at the time of polymerization reaction completion. If the content of heavy metal ions exceeds 10 ppm, the color tone of the resulting polymer may be deteriorated.
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. For example, when the polymer polymerized in the polymerization reaction solution is neutralized with an alkali component, the content of heavy metal ions is calculated based on the total mass of the polymerization reaction solution after neutralization. When two or more kinds of heavy metal ions are included, the total amount of heavy metal ions may be in the above range.

Preferred combinations of the above chain transfer agent, polymerization initiator and reaction accelerator include persulfate alone, persulfate and bisulfite (salts), persulfate and hypophosphorous acid (salt), persulfate and heavy sulfate. Sulfurous acid (salts) and heavy metal ions are exemplified.
In the present invention, inorganic acid salts such as bisulfite and hypophosphite represent metal salts, ammonium salts, and organic amine salts, and sodium salts and potassium salts are preferred as the metal salts.

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. When using a persulfate as a polymerization initiator, it is preferably added as an aqueous solution.
The end point of the addition of the persulfate is preferably after the end point of the addition of the monomer, more preferably within 60 minutes from the end of the addition of the monomer, and 30 from the end of the 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 bisulfite (salt) is used as the polymerization initiator, it is preferably added as an aqueous solution.
When bisulfite (salt) is used, the molecular weight at the initial stage of polymerization greatly affects the final molecular weight. For this reason, in order to reduce the initial molecular weight, the bisulfite (salt) or a solution thereof is added within 5 to 20% by mass of the used amount within 60 minutes, preferably within 30 minutes, more preferably within 10 minutes from the start of polymerization. (Drip) is desirable.
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, a monomer component, an initiator, or 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 or initiator is dissolved in advance.

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 polycarboxylic acid 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 satisfactorily. 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, when a persulfate and a bisulfite (salt) are used in combination, it is preferable to carry out the copolymerization of the monomer components with a monomer neutralization rate of 0 to 60 mol%. The neutralization rate of the monomer is defined as a unit that forms a salt when the total number of moles of the monomer contained in the reaction solution and the carboxyl group of the structural unit derived from the monomer is 100 mol%. It is represented by the ratio (mol%) of the carboxyl group of the structural unit derived from the monomer that forms a salt with the monomer. By setting the neutralization rate of the monomer within the above range, the polymerization rate tends to be improved, and the molecular weight of the polymer tends to be easily controlled within a preferable range. More preferably, it is 50 mol% or less, more preferably 40 mol% or less, particularly preferably 30 mol% or less, more particularly preferably 20 mol% or less, and most preferably 10 mol%. It is as follows.

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.
[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, emulsifier, skin care agent, hair care agent and the like.

<Detergent Builder>
The polycarboxylic acid polymer (or polymer composition) 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 polycarboxylic acid polymer (or polymer composition) 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 polycarboxylic acid polymer of the present invention in the detergent composition is not particularly limited. However, from the viewpoint of exhibiting excellent builder performance, the content of the polycarboxylic acid polymer of the present invention is preferably 0.1 to 15% by mass relative to the total amount of the detergent composition, More preferably, it is 0.3-10 mass%, More preferably, it is 0.5-5 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) as an additive (other additives) other than the polycarboxylic acid polymer and surfactant of the present invention; Chelate builders such as acid (salt), citric acid (salt), acrylic acid-maleic acid copolymer (salt), ethylenediaminetetraacetic acid (salt), bow glass, zeolite, etc .; Anti-redeposition agent for preventing deposition; Stain inhibitor such as benzotriazole and ethylene-thiourea; Soil release agent; Color transfer inhibitor such as polyvinyl pyrrolidone; Softener; Alkaline substance for pH adjustment; Solubilizer; fluorescent agent; coloring agent; foaming agent; foam stabilizer; glossing 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 polycarboxylic acid polymer (or polymer composition) 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 polycarboxylic acid 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 polycarboxylic acid polymer (or polymer composition) 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 polycarboxylic acid polymer of the present invention.
The content of the polycarboxylic acid 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 polycarboxylic acid-based 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, the whiteness of the fiber, uneven color, and the degree of dyeing tempering. For the improvement, at least one selected from the group consisting of a dye, a peroxide and a surfactant is used per 1 part by weight of the polycarboxylic acid 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 the ratio of 0.1-100 weight part 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 polycarboxylic acid 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 polycarboxylic acid polymer (or polymer composition) 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 polycarboxylic acid 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, moisture absorption rate, etc. of the polycarboxylic acid polymer of the present invention were measured according to the following methods.

<Measurement conditions of weight average molecular weight>
Device: Hitachi L-7000 Series Detector: RI
Column: SHODEX Asahipak GF-310-HQ, GF-710-HQ, GF-1G 7B manufactured by Showa Denko KK
Column temperature: 40 ° C
Flow rate: 0.5 ml / min.
Calibration curve: POLYACRYLIC ACID STANDARD made by Soka Science Co., Ltd.
Eluent: 0.1N sodium acetate / acetonitrile = 3/1 (mass ratio)
<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. From the weight change before and after drying, the solid content (%) and the volatile component (%) were calculated.

<Hygroscopic rate>
(1) The polymer composition was sampled in an aluminum cup so that the solid content was 0.75 g.
(2) The above (1) was dried in an oven set at 130 ° C. for 2 hours. After drying, it was cooled in a desiccator for 30 minutes, the mass was measured, and the mass obtained by subtracting the mass of the aluminum cup was defined as the mass before moisture absorption.
(3) It was stored for 1 week under constant temperature and humidity conditions (40 ° C., RH 80%). The mass was measured immediately after storage, and the mass after subtracting the mass of the aluminum cup was taken as the mass after moisture absorption.
(4) The moisture absorption rate was calculated by the following formula.
Moisture absorption rate (%) = (mass after moisture absorption−mass before moisture absorption) / (mass before moisture absorption) × 100.

<Content of sodium sulfate>
The content of sodium sulfate was calculated by quantifying the amount of sulfate ions and the amount of sodium contained in the polymer composition by the following method. That is, in the following polymer composition, sodium sulfate corresponding to the smaller one of sulfate ion equivalent and sodium equivalent is present.
(Sulfate ion analysis)
The amount of sulfate ion was measured by performing ion chromatography analysis under the following conditions.
Apparatus: 762 Interface manufactured by Metrohm
Detector: 732 IC Detector manufactured by Metrohm
Ion analysis method: Suppressor method Column: Shodex IC SI-90 4E
Guard column: Shodex SI-90 G
Column temperature: 40 ° C
Eluent: NaHCO3 water (2 g diluted to 2000 g with water)
Flow rate: 1.0 mL / min.
(Analysis of sodium content)
Quantification was performed by inductively coupled plasma (ICP) emission spectroscopy.

<Example 1>
In a 5-liter SUS separable flask equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer, 1138.0 g of pure water was charged (initial charge), and the temperature was raised to the boiling point with stirring. Next, under stirring, in a polymerization reaction system in a boiling point reflux state, 900 g (namely, 10 mol) of 80% by mass acrylic acid aqueous solution (hereinafter referred to as “80% AA”), 15% by mass sodium persulfate aqueous solution (hereinafter referred to as “15% NaPS”) 180.0 g (2.7 g / mol when converted to the monomer charge) was dropped from separate dropping nozzles. Each dropping time was set to 360% for 80% AA and 370 minutes for 15% NaPS. 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. As described above, a polyacrylic acid aqueous solution (referred to as polymer aqueous solution (1)) as a polycarboxylic acid polymer composition of the present invention was obtained. The solid content value of the aqueous polymer solution (1) was 33.7%, and the weight average molecular weight (Mw) of the polymer (referred to as polymer (1)) contained in the aqueous polymer solution (1) was 38000. The amount of sodium sulfate in the polymer aqueous solution (1) was 2.20% by mass relative to the solid content. The polymerization results and the results of measuring the moisture absorption rate are shown in Table 1.
When the moisture absorption rate of the polymer was evaluated by the above-described method, the moisture absorption rate was 27.9%.

<Example 2>
In a 5-liter SUS separable flask equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer, 1141.1 g of pure water was charged (initial charge), and the temperature was raised to the boiling point with stirring. Next, under stirring, in a polymerization reaction system in a boiling point reflux state, 900 g of an 80% by mass acrylic acid aqueous solution (that is, 10 mol), 173.4 g of 15% by mass ammonium persulfate aqueous solution (hereinafter referred to as “15% APS”) In terms of input amount, 2.7 g / mol) was dropped from separate dropping nozzles. Each dropping time was set to 360% for 80% AA and 370 minutes for 15% NaPS. 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. As described above, a polyacrylic acid aqueous solution (polymer aqueous solution (2)) as a polycarboxylic acid polymer composition of the present invention was obtained. The solid content value of the aqueous polymer solution (2) was 33.7%, and the weight average molecular weight (Mw) of the polymer (referred to as polymer (2)) contained in the aqueous polymer solution (2) was 39000. The amount of sodium sulfate in the polymer aqueous solution (2) was 0.11% by mass relative to the solid content. The polymerization results and the results of measuring the moisture absorption rate are shown in Table 1.
When the moisture absorption rate of the polymer was evaluated by the above-mentioned method in the same manner as in Example 1, the moisture absorption rate was 27.8%.

<Example 3>
A SUS separable flask having a capacity of 5 liters equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer was charged with 665.7 g of pure water and 0.0164 g of Mole salt (initial charge), and stirred at 85 ° C. The temperature was raised to. Then, under stirring, in a polymerization reaction system at a constant temperature of about 85 ° C., an 80% by weight acrylic acid aqueous solution 900 g (that is, 10 mol) and a 15% by weight sodium persulfate aqueous solution 33.3 g (0.5 g in terms of monomer charge). / Mol), 54.3 g of a 35 mass% sodium bisulfite aqueous solution (hereinafter also referred to as “35% SBS”) (1.9 g / mol when converted to the amount of monomer charged), was dropped from separate dropping nozzles. did. The dropping time was 80% AA for 180 minutes, 15% NaPS for 190 minutes, and 35% SBS for 175 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 85 ° C. (ripening) for 30 minutes to complete the polymerization. As described above, a polyacrylic acid aqueous solution (polymer aqueous solution (3)) as a polycarboxylic acid polymer composition of the present invention was obtained. The solid content of the aqueous polymer solution (3) was 45.0%, and the weight average molecular weight (Mw) of the polymer (referred to as polymer (3)) contained in the aqueous polymer solution (3) was 36000. The amount of sodium sulfate in the polymer aqueous solution (3) was 1.10% by mass relative to the solid content. The polymerization results and the results of measuring the moisture absorption rate are shown in Table 1.
When the moisture absorption rate of the polymer was evaluated in the same manner as in Example 1, the moisture absorption rate was 26.3%.

<Example 4>
A SUS separable flask having a capacity of 5 liters equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer was charged with 665.7 g of pure water and 0.0164 g of Mole salt (initial charge), and stirred at 85 ° C. The temperature was raised to. Next, under stirring, in a polymerization reaction system at a constant temperature of about 85 ° C., 900 g of an 80% by mass acrylic acid aqueous solution (that is, 10 mol) and 33.3 g of 15% by mass ammonium persulfate aqueous solution (0.5 g / in terms of monomer charge). mol), 54.3 g of a 35% by mass aqueous sodium bisulfite solution (1.9 g / mol when converted to the amount of monomer charged) was added dropwise from separate dropping nozzles. The dropping time was 80% AA for 180 minutes, 15% NaPS for 190 minutes, and 35% SBS for 175 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 85 ° C. (ripening) for 30 minutes to complete the polymerization. As described above, a polyacrylic acid aqueous solution (polymer aqueous solution (4)) as a polycarboxylic acid polymer composition of the present invention was obtained. The solid content of the aqueous polymer solution (4) was 45.0%, and the weight average molecular weight (Mw) of the polymer (referred to as polymer (4)) contained in the aqueous polymer solution (4) was 37000. The amount of sodium sulfate in the polymer aqueous solution (4) was 1.00% by mass with respect to the solid content. The polymerization results and the results of measuring the moisture absorption rate are shown in Table 1.
When the moisture absorption rate of the polymer was evaluated by the above-described method in the same manner as in Example 1, the moisture absorption rate was 26.6%.

<Comparative Example 1>
A SUS separable flask having a capacity of 5 liters equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer was charged with 3832.9 g of pure water (initial charge), and the temperature was raised to the boiling point with stirring. Next, under stirring, in a polymerization reaction system in a boiling point reflux state, 900 g (namely, 10 mol) of 80% by mass acrylic acid aqueous solution (hereinafter referred to as “80% AA”), 15% by mass sodium persulfate aqueous solution (hereinafter referred to as “15% NaPS”) 300.0 g (4.5 g / mol when converted to monomer charge) was dropped from separate dropping nozzles. The dropping time was 80% AA for 180 minutes and 15% NaPS for 190 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. As described above, a comparative polyacrylic acid aqueous solution (comparative polymer aqueous solution (1)) was obtained. The comparative polymer aqueous solution (1) had a shape fraction value of 15.2%, and the polymer contained in the comparative polymer aqueous solution (1) (referred to as the comparative polymer (1)) had a weight average molecular weight (Mw) of 10,000. It was. The amount of sodium sulfate in the comparative polymer aqueous solution (1) was 2.70% by mass relative to the solid content. The polymerization results and the results of measuring the moisture absorption rate are shown in Table 1.
When the moisture absorption rate of the polymer was evaluated by the above-described method, the moisture absorption rate was 30.4%.

<Comparative example 2>
352.8 g of pure water was charged into an SUS separable flask having a capacity of 5 liters equipped with a reflux condenser, a stirrer (paddle blade), and a thermometer (initial charge), and the temperature was raised to 85 ° C. with stirring. Next, under stirring, in an polymerization reaction system at a constant state of about 85 ° C., 900 g of an 80% by mass acrylic acid aqueous solution (that is, 10 mol) and 120 g of 15% by mass aqueous sodium persulfate aqueous solution (1.8 g / mol in terms of monomer input). ), 358.6% by weight sodium bisulfite aqueous solution (hereinafter, also referred to as “35% SBS”) 148.6 g (5.2 g / mol when converted to the amount of monomer charged) was dropped from separate dropping nozzles. The dropping time was 80% AA for 180 minutes, 15% NaPS for 190 minutes, and 35% SBS for 175 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 85 ° C. (ripening) for 30 minutes to complete the polymerization. As described above, a comparative polyacrylic acid aqueous solution (comparative polymer aqueous solution (2)) was obtained. The comparative polymer aqueous solution (2) had a shape fraction value of 51.9%, and the polymer contained in the comparative polymer aqueous solution (2) (referred to as the comparative polymer (2)) had a weight average molecular weight (Mw) of 7900. It was. The amount of sodium sulfate in the comparative polymer aqueous solution (2) was 3.00% by mass relative to the solid content. The polymerization results and the results of measuring the moisture absorption rate are shown in Table 1.
When the moisture absorption rate of the polymer was evaluated in the same manner as in Example 1, the moisture absorption rate was 30.5%.

As is apparent from Table 1, it was revealed that the polymer composition of the present invention has excellent moisture absorption characteristics (low moisture absorption rate) as compared with conventional polymer compositions. Therefore, it has been clarified that the polymer composition of the present invention can be blended more in the detergent composition than the conventional polymer composition.

Claims (3)

A composition comprising a polycarboxylic acid polymer,
Polycarboxylic acid having a moisture absorption rate of less than 30% during drying and a sodium sulfate content of 0% by mass or more and less than 2.5% by mass with respect to the solid content of the polycarboxylic acid polymer composition -Based polymer composition. The said polycarboxylic acid-type polymer is 50 mol% or more and 100 mol% or less of the structure derived from (meth) acrylic acid (salt) with respect to 100 mol% of structures derived from all the monomers. The polycarboxylic acid polymer composition described. The above polycarboxylic acid polymer is produced by using a persulfate or a step of polymerizing a monomer containing (meth) acrylic acid (salt) using a persulfate and a bisulfite in combination. The amount of persulfate used is 0.1 g or more and 4 g or less per mole of monomer, and the total amount of persulfate and bisulfite used is 1 mole per monomer. The polycarboxylic acid polymer composition according to claim 1, wherein the polycarboxylic acid polymer composition is 2 to 5 g.