JP2011021130A - (meth)acrylic acid-based polymer and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a (meth)acrylic acid-based polymer that give excellent dispersibility of inorganic substance and excellent temporal stability of dispersion force when used in applications for detergents and pigment dispersants. <P>SOLUTION: The (meth)acrylic acid-based polymer is obtained by polymerizing a monomer composition containing a (meth)acrylic acid-based monomer in the presence of a phosphorus atom-containing compound by a batch type. The polymerization is carried out by specifying the ratio of the total of the phosphorus atom-containing compound added to the reaction system to the total of the (meth)acrylic acid-based monomer added to the reaction system. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

(Meth) acrylic acid-based polymers centered on sodium polyacrylate are used for applications such as detergent builders, pigment dispersants, and water treatment agents (scale component adhesion inhibitors). In these markets, (meth) acrylic acid polymers having higher performance are required.
As a method for meeting such a demand, for example, a technique for reducing the molecular weight distribution of a (meth) acrylic acid polymer as in Patent Documents 1 to 3 is known.
In addition, for example, when (meth) acrylic acid polymer is used as a detergent builder, it exhibits the effect of dispersing mud dirt etc., but when used for deferred washing, it can disperse the initial mud dirt etc. In addition to this, development of a (meth) acrylic acid polymer that exhibits dispersive power over time is required.

JP 2004-143402 A JP 2000-31888 A JP 59-223702 A

However, even the (meth) acrylic acid polymer produced by the above technology has not yet been able to sufficiently satisfy the above requirements. That is, it was not possible to obtain a (meth) acrylic acid polymer having excellent inorganic dispersibility and sufficient dispersibility over time.
Accordingly, an object of the present invention is to provide a desired (meth) acrylic acid polymer as described above.

The present inventors have intensively studied to solve the above problems. As a result, in the method for producing a (meth) acrylic acid polymer in a batch process, when a monomer composition containing a (meth) acrylic acid monomer is polymerized in the presence of a specific phosphorus atom-containing compound. In addition, the (meth) acrylic acid polymer obtained by polymerizing by specifying the ratio of the total amount of phosphorus atom-containing compound added to the reaction system and the (meth) acrylic acid monomer added to the reaction system, The present inventors have found that excellent inorganic dispersibility and sufficient dispersibility with stability over time have been developed, and the present invention has been completed.
That is, the (meth) acrylic acid polymer according to the present invention is a (meth) acrylic acid monomer in the presence of one or more phosphorus atom-containing compounds selected from phosphorous acid, hypophosphorous acid, and salts thereof. A (meth) acrylic acid polymer obtained by polymerizing a monomer composition containing a monomer in a batch manner,
The total amount of phosphorus atom-containing compound added to the reaction system 5 minutes after the start of polymerization is 15.0 with respect to 1 mol of the total amount of (meth) acrylic acid monomer added to the reaction system 5 minutes after the start of polymerization. ~ 23.0g,
The total amount of phosphorus atom-containing compound added to the reaction system 30 minutes after the start of polymerization is 4.0 with respect to 1 mol of the total amount of (meth) acrylic acid monomer added to the reaction system 30 minutes after the start of polymerization. It is obtained so that it becomes ˜7.0 g,
It is a (meth) acrylic acid polymer.

The (meth) acrylic acid-based polymer of the present invention has excellent dispersibility of inorganic fine particles such as mud stains and inorganic pigments, and can further exhibit dispersibility over time. Therefore, when used as a detergent builder or a pigment dispersant, excellent detergency over time and dispersibility of the pigment can be obtained.

It is the schematic which shows one Embodiment of the reaction apparatus used suitably for the manufacturing method of this invention.

101 Polymerization pot 111 Stirring blade 113 External jacket 115 External circulation path,
117 heat removal device,
119 supply route,
121 tip nozzle,
123 tanks,
125 Reaction liquid extraction route.

Hereinafter, the present invention will be described in detail.
[(Meth) acrylic acid polymer]
((Meth) acrylic acid monomer)
The (meth) acrylic acid polymer of the present invention can be obtained by polymerizing a monomer composition essentially comprising a (meth) acrylic acid monomer. In the present invention, the (meth) acrylic acid monomer represents (meth) acrylic acid and (meth) acrylate. In the present invention, (meth) acrylic acid represents methacrylic acid and acrylic acid, and (meth) acrylate represents methacrylate and acrylate.
In the present invention, the “salt” in the (meth) acrylate is an alkali metal salt such as a lithium salt, a sodium salt, or a potassium salt, an alkaline earth metal salt such as a calcium salt, a magnesium salt, or the like unless otherwise specified. Ammonium salt represents a quaternary ammonium salt (“salt” in a monomer having another acid group, “salt in a structural unit derived from a monomer having an acid group in a (meth) acrylic acid polymer) Is the same).

(Other monomers)
As described above, in the present invention, the (meth) acrylic acid polymer is obtained by polymerizing a monomer composition containing at least one (meth) acrylic acid monomer as an essential component. The (meth) acrylic acid polymer in the present invention may be polymerized by including other monomers in addition to the (meth) acrylic acid monomer.
Other monomers are not particularly limited, but for example, other than (meth) acrylic monomers such as maleic acid, fumaric acid, itaconic acid, crotonic acid, 2-methyleneglutaric acid, and salts thereof 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) ) Acrylate, hydroxyl-containing alkyl (meth) acrylates such as α-hydroxymethylethyl (meth) acrylate; methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, cyclohexyl (meth) acrylate Carbon number of (meth) acrylic acid such as lauryl (meth) acrylate Alkyl (meth) acrylates which are esters of -18 alkyl groups; amino group-containing acrylates such as dimethylaminoethyl (meth) acrylate or a quaternized product thereof; amide groups such as (meth) acrylamide, dimethylacrylamide and isopropylacrylamide Containing monomers; Vinyl esters such as vinyl acetate; Alkenes such as ethylene and propylene; Aromatic vinyl monomers such as styrene; Maleimide derivatives such as maleimide, phenylmaleimide, and cyclohexylmaleimide; (meth) acrylonitrile Nitrile group-containing vinyl monomers such as 3-allyloxy-2-hydroxypropanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, styrenesulfonic acid, vinylsulfonic acid and the like And salts thereof; monomers having phosphonic acid groups such as vinylphosphonic acid and (meth) allylphosphonic acid; aldehyde group-containing vinyl monomers such as (meth) acrolein; methyl vinyl ether, ethyl vinyl ether, butyl Alkyl vinyl ethers such as vinyl ether; vinyl chloride, vinylidene chloride, allyl alcohol: other functional group-containing monomers such as vinyl pyrrolidone; polyalkylene glycol (meth) acrylate, monoalkoxy polyalkylene glycol (meth) acrylate, vinyl alcohol And polyalkylene glycol chain-containing monomers such as monomers having a structure in which 1 to 300 mol of alkylene oxide is added to an unsaturated alcohol such as (meth) allyl alcohol or isoprenol. Also about these other monomers, only 1 type may be used independently and 2 or more types may be used together.

  In the present invention, the proportion of (meth) acrylic acid monomer in the total monomer (total of (meth) acrylic acid monomer and other monomers) is 100 mol% of all monomers. 50 mol% to 100 mol%, preferably 70 mol% to 100 mol%, more preferably 80 mol% to 100 mol%, and most preferably 90 mol% to 100 mol%. If the ratio of the (meth) acrylic acid monomer is within the above range, the detergent builder, the pigment dispersant, etc. due to the tendency to improve the dispersive power over time of the (meth) acrylic acid polymer Can be suitably used.

(Structure of (meth) acrylic acid polymer)
The (meth) acrylic acid polymer of the present invention contains a structural unit derived from a (meth) acrylic acid monomer as an essential component. The structural unit derived from the (meth) acrylic acid monomer is a structural unit formed by radical polymerization of the (meth) acrylic acid monomer. For example, the structural unit derived from acrylic acid is a structural unit represented by —CH ₂ CH (COOH) —.
The (meth) acrylic acid polymer of the present invention is a structural unit derived from a (meth) acrylic acid monomer as a whole structural unit (a structural unit derived from a (meth) acrylic acid monomer and other single quantities). The total of structural units derived from the body) is 50 mol% to 100 mol%, preferably 70 mol% to 100 mol%, more preferably 80 mol% to 100 mol%, most preferably 90 mol to 100 mol%. It is from mol% to 100 mol%. If the proportion of the structural unit derived from the (meth) acrylic acid monomer is within the above range, the detergent builder and the methacrylic acid polymer tend to be improved over time. It can be suitably used as a pigment dispersant or the like.

  Specifically, the weight average molecular weight of the (meth) acrylic acid polymer obtained by the production method of the present invention is preferably 3000 to 50000, more preferably 4000 to 30000, and still more preferably 5000 to 5000. 20000. When the value of the weight average molecular weight is too large, the viscosity becomes high and handling may be complicated. On the other hand, if the value of the weight average molecular weight is too small, the dispersibility of clay, pigment, and the like is lowered, and there is a possibility that sufficient performance as a detergent builder or a pigment dispersant may not be exhibited. In addition, the value measured by the method as described in the Example mentioned later shall be employ | adopted as a value of the weight average molecular weight of the (meth) acrylic-acid type polymer of this invention.

  The number average molecular weight of the (meth) acrylic acid polymer of the present invention is specifically preferably 1500 to 20000, more preferably 1600 to 12000, and still more preferably 2000 to 8000. When the value of the number average molecular weight is too large, the viscosity becomes high and handling may be complicated. On the other hand, if the value of the number average molecular weight is too small, the dispersibility of clay, pigment and the like is lowered, and there is a possibility that sufficient performance as a detergent builder or a pigment dispersant may not be exhibited. In addition, the value measured by the method as described in the Example mentioned later shall be employ | adopted as a value of the number average molecular weight of the (meth) acrylic-acid type polymer of this invention.

(Method for producing (meth) acrylic acid polymer)
The (meth) acrylic acid polymer of the present invention is polymerized when a (meth) acrylic acid polymer is produced by batch polymerization of a monomer composition containing a (meth) acrylic acid monomer. The total amount of the phosphorus atom-containing compound added to the reaction system at the very initial stage of the reaction is obtained by setting a predetermined amount with respect to the total amount of the (meth) acrylic acid monomer added to the reaction system. .
Specifically, the total amount of phosphorus atom-containing compound added to the reaction system 5 minutes after the start of polymerization is 1 mol of the total amount of (meth) acrylic acid monomer added to the reaction system 5 minutes after the start of polymerization. On the other hand, it is 15.0 or more and 23.0 g or less. Preferably it is 16.0 or more and 22.5 or less, More preferably, it is 17.0 or more and 22.0 or less. By producing in this way, it is possible to suppress the formation of a polymer that adversely affects the temporal stability of dispersibility at the initial stage of polymerization. Specifically, it is possible to suppress the generation of impurities that replicate from the phosphorus atom-containing compound and the (meth) acrylic acid monomer.
The reason for 5 minutes after the start of polymerization is that it may be difficult to adjust depending on the polymerization method due to the fact that an initial charge of a phosphorus atom-containing compound or the like may occur if the polymerization is less than 5 minutes. This is because the stability over time of the dispersibility of the resulting (meth) acrylic acid polymer tends to be remarkably deteriorated if it is not adjusted to the above range over 5 minutes.

  Here, 5 minutes after the start of polymerization means 5 minutes after the start of polymerization, and in the present invention, “at the start of polymerization” means at least polymerization used in the reactor (in the polymerization apparatus) for polymerization. This represents a point in time when at least part of the initiator and at least part of the (meth) acrylic monomer are added.

  Here, “the total amount of the phosphorus atom-containing compound added to the reaction system 5 minutes after the start of the polymerization is 1 mol of the total amount of the (meth) acrylic acid monomer added to the reaction system 5 minutes after the start of the polymerization. Specifically, “the total amount (g) of the phosphorus atom-containing compound added to the reaction system 5 minutes after the start of polymerization” is added to the reaction system 5 minutes after the start of polymerization. It is calculated by dividing by the “total amount of acid monomer (mol)”.

The (meth) acrylic acid polymer of the present invention is polymerized when a (meth) acrylic acid polymer is produced by batch polymerization of a monomer composition containing a (meth) acrylic acid monomer. 30 minutes after the start (if all (meth) acrylic monomers are added to the reaction system in less than 30 minutes after the start of polymerization, all (meth) acrylic monomers are added to the reaction system. The total amount of the phosphorus atom-containing compound added to the reaction system in 1) is the total amount of 1 mol of (meth) acrylic acid monomer added to the reaction system 30 minutes after the start of polymerization. On the other hand, it is obtained so that it may become 4.0-7.0g. Preferably they are 4.5 or more and 6.5 or less, More preferably, they are 5.0 or more and 6.3 or less. By polymerizing in this way, the effect of improving the dispersibility of the inorganic fine particles is exhibited.
After 30 minutes from the start of polymerization, it may not be appropriate to adjust depending on the polymerization method, such as when initially preparing a phosphorus atom-containing compound for a while after the start of polymerization. This is because, when not adjusted to the above range, the dispersibility of the inorganic fine particles of the (meth) acrylic acid polymer obtained tends to be remarkably deteriorated.
Even after 30 minutes from the start of polymerization, the total addition amount of the phosphorus atom-containing compound (the amount added to the reactor until that time) is 4.0 to 7.0 g with respect to 1 mol of the total amount of the (meth) acrylic monomer. For example, it is preferably maintained in the above range until 20 minutes before the end of the polymerization. More preferably, it is maintained within the above range until 15 minutes before the end of the polymerization, and particularly preferably within the above range until the end of the polymerization. In the present invention, “at the end of polymerization” refers to the time when all the monomers have been added to the reactor.

  The addition time of the monomer is not particularly limited, but is preferably 30 to 110 minutes, more preferably 40 to 105 minutes, further preferably 50 to 100 minutes, and most preferably 60 to 100 minutes. . In the present invention, the “monomer addition time” refers to the time from when the monomer is first added to the reactor (polymerization kettle) until the addition of the entire amount of monomer is substantially completed. Although it is time, the time in the absence of the polymerization initiator is not included in the monomer dropping time. This is because the polymerization reaction does not occur unless a polymerization initiator is present in the system. For example, when a part of the monomer is initially charged, it does not correspond to the addition time of the monomer unless the polymerization reaction substantially occurs. That is, the “monomer addition time” in the present invention represents the monomer addition time in the presence of a polymerization initiator.

  Regarding the method of adding the (meth) acrylic acid monomer and other monomers in the production method of the present invention, the phosphorus atom-containing material added to the reaction system 5 minutes after the start of polymerization and 30 minutes after the start of polymerization There is no limitation if the ratio of the total amount of the compound to the total amount of the (meth) acrylic acid monomer is set to a predetermined value, but at least a part is added to the reaction system continuously or dividedly after the start of polymerization. It is preferred that Further, a part of the monomers may be added to the reaction system (initial charge) before the start of polymerization. The total amount of the (meth) acrylic acid-based monomer is particularly preferably continuously added to the reaction system after the start of polymerization (including a form in which addition is started simultaneously with the start of polymerization).

(Phosphorus atom-containing compound)
As described above, the (meth) acrylic acid polymer of the present invention is obtained by polymerization in the presence of a phosphorus atom-containing compound.
In the present invention, the phosphorus atom-containing compound may be any compound containing a phosphorus atom that can act as a chain transfer agent during the polymerization of (meth) acrylic acid. Specifically, phosphorous acid, phosphorous acid Examples thereof include acid salts, hypophosphorous acid, hypophosphites, and hydrates thereof (hereinafter, the term “hypophosphite” and the like also includes hydrates thereof). As used herein, “salt” represents an alkali metal salt such as lithium salt, sodium salt or potassium salt, an alkaline earth metal salt such as calcium salt or magnesium salt, an ammonium salt or a quaternary ammonium salt unless otherwise specified. .
Hypophosphite and hydrates thereof are particularly preferred because the dispersibility of the resulting polymer inorganic fine particles is improved.
Here, when calculating the usage-amount with respect to the usage-amount (mol) of acrylic acid of a phosphorus atom containing compound, it calculates as a corresponding sodium salt.
Various hydrates are calculated as unhydrated sodium salts.

  It is preferable that the phosphorus atom containing compound used for manufacture of the (meth) acrylic acid type polymer of this invention is 3.0 or more and 7.0 or less with respect to 1 mol of (meth) acrylic acid type monomers. More preferably, it is 3.5 or more and 6.5 or less.

  Regarding the addition method of the phosphorus atom-containing compound, the ratio of the total amount of the phosphorus atom-containing compound and the total amount of the (meth) acrylic monomer added to the reaction system 5 minutes after the start of polymerization and 30 minutes after the start of the polymerization. However, there is no limitation as long as it is set to be predetermined, but it is preferable that at least a part is added to the reaction system continuously or dividedly after the start of polymerization. Moreover, since it becomes easy to obtain a polymer having a desired molecular weight, it is more preferable to add (initially charge) at least a part to the reaction system before the start of polymerization.

(Polymerization initiator)
The (meth) acrylic acid polymer of the present invention is obtained by polymerizing a monomer composition containing a (meth) acrylic acid monomer as an essential component in the presence of a polymerization initiator (also referred to as an initiator). be able to.
Known polymerization initiators can be used such as persulfates such as sodium persulfate, potassium persulfate and ammonium persulfate; hydrogen peroxide; dimethyl 2,2′-azobis (2-methylpropio Nate), 2,2′-azobis (2-amidinopropane) hydrochloride, 4,4′-azobis-4-cyanoparerenic acid, azobisisobutyronitrile, 2,2′-azobis (4-methoxy-2, Preferred are azo compounds such as 4-dimethylvaleronitrile); organic peroxides such as benzoyl peroxide, lauroyl peroxide, peracetic acid, di-t-butyl peroxide and cumene hydroperoxide. These polymerization initiators may be used alone or in the form of a mixture of two or more.
The amount of the polymerization initiator used is preferably 15 g or less, more preferably 0.1 to 12 g, based on 1 mol of all monomer components, unless otherwise specified.
The amount of the polymerization initiator used may be appropriately adjusted according to the amount of the monomer component used, and is not particularly limited. For example, it is preferably 0.001 with respect to 100 parts by mass of the monomer. It is not less than 20 parts by mass, more preferably not less than 0.005 parts by mass and not more than 15 parts by mass, still more preferably not less than 0.01 parts by mass and not more than 10 parts by mass.
Among the polymerization initiators, it is particularly preferable to use a persulfate. The amount of persulfate added is preferably 0.1 to 5.0 g, more preferably 0.2 to 4.0 g, per 1 mol of the monomer. If the amount of persulfate added is too small, the molecular weight of the resulting polymer tends to increase. On the other hand, when the addition amount is too large, the effect of persulfate cannot be obtained as the addition amount increases, and further, the purity of the resulting polymer is adversely affected.

  The method for adding the polymerization initiator is not particularly limited, but the amount dripped substantially continuously with respect to the total amount used is preferably 50% by weight or more of the required predetermined amount, particularly preferably 80% by weight. %, And it is most preferable to add the whole amount dropwise. The polymerization initiator is preferably dripped continuously, but the dripping speed may be changed.

  Although there is no particular limitation on the dropping time, in the case of an initiator that decomposes relatively quickly, such as persulfates such as ammonium persulfate, potassium persulfate, and sodium persulfate under the conditions of polymerization temperature and pH at the time of polymerization described later. It is preferable to drop until the monomer dropping end time, more preferably within 30 minutes after the monomer dropping ends, and particularly within 5 to 20 minutes after the monomer dropping. preferable. Thereby, the effect which can reduce the residual amount of the monomer in a polymer remarkably can be found. It should be noted that, even if the addition of these initiators is completed before the completion of the monomer addition, it does not particularly adversely affect the polymerization, and is set according to the residual amount of the monomer in the obtained polymer. It ’s good.

  For these initiators that are relatively quick to decompose, the preferred range is described only for the dropping end time, but the dropping start time is not limited at all and may be set as appropriate. For example, in some cases, the dropping of the initiator may be started before the start of dropping of the monomer, or in the case of a combined system in particular, the dropping of one initiator is started and a certain time has elapsed. Then, or after completion, another initiator may be dropped. Any of these may be set as appropriate according to the decomposition rate of the initiator and the reactivity of the monomer.

(Chain transfer agent)
In addition to the polymerization initiator, the (meth) acrylic acid polymer of the present invention includes the above phosphorous acid, hypophosphorous acid, and salts thereof (sodium hypophosphite, potassium hypophosphite) as chain transfer agents. Etc.), a chain transfer agent other than the phosphorus atom-containing compound can be used. The chain transfer agent that can be used in this case is not particularly limited as long as it is a compound capable of adjusting the molecular weight, and a known chain transfer agent can be used. Specifically, mercaptoethanol, thioglycerol, thioglycolic acid, 2-mercaptopropion, 3-mercaptopropion, thiomalic acid, octyl thioglycolate, octyl 3-mercaptopropionate, 2-mercaptoethanesulfonic acid, n Thiol chain transfer agents such as dodecyl mercaptan, octyl mercaptan, butyl thioglycolate; halides such as carbon tetrachloride, methylene chloride, bromoform, bromotrichloroethane; secondary alcohols such as isopropanol, glycerin; sulfurous acid, Hydrogen sulfite, dithionite, metabisulfite, and salts thereof (sodium bisulfite, potassium bisulfite, sodium dithionite, potassium dithionite, sodium metabisulfite, potassium metabisulfite, etc.) Like lower oxides and salts thereof. The chain transfer agent may be used alone or in the form of a mixture of two or more.
The addition amount of the chain transfer agent is 1 to 20 g, more preferably 2 to 15 g, with respect to 1 mol of all monomer components, unless otherwise specified. If it is less than 1 g, the molecular weight may not be controlled. Conversely, if it exceeds 20 g, the chain transfer agent may remain or the polymer content may decrease.

  When the phosphorus atom-containing compound and the persulfate are used in combination, the mixing ratio of the phosphorus atom-containing compound and the persulfate is not particularly limited, but the phosphorus atom-containing compound 0. It is preferable to use 5 to 8 parts by mass. More preferably, the lower limit of the phosphorus atom-containing compound is 1 part by mass, most preferably 2 parts by mass, and most preferably 3 parts by mass with respect to 1 part by mass of persulfate. Further, the upper limit of the phosphorus atom-containing compound is more preferably 7 parts by mass, and most preferably 6 parts by mass with respect to 1 part by mass of persulfate. Here, if the phosphorus atom-containing compound is less than 0.5 parts by mass, the total amount of the initiator may increase when the molecular weight is lowered. Conversely, if it exceeds 8 parts by mass, side reactions increase, Impurities may increase.

(Decomposition catalyst, reducing compound)
The (meth) acrylic acid polymer of the present invention uses a polymerization initiator decomposition catalyst or a reducing compound (also referred to as a reaction accelerator) in addition to the polymerization initiator and phosphorus atom-containing compound (added to the polymerization system). And may be manufactured.

As a compound that acts as a decomposition catalyst for the polymerization initiator or a reducing compound, heavy metal ions (or heavy metal salts) can be mentioned. That is, the (meth) acrylic acid-based polymer of the present invention may be produced by using (adding to a polymerization system) heavy metal ions (or heavy metal salts) in addition to the polymerization initiator and the phosphorus atom-containing compound. In the present invention, the heavy metal ion 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.
In the present invention, the heavy metal ions are present in the reaction system by adding an aqueous solution or an aqueous solution in which a heavy metal salt (heavy metal compound) is dissolved to the polymerization system. The heavy metal salt used in that case should just contain the heavy metal ion desired to contain in an initiator, and can be determined according to the initiator to be used. 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 salt or the like. Moreover, when using manganese as a heavy metal ion, manganese chloride etc. can be used suitably. When these heavy metal salts are used, since they are water-soluble compounds, they can be used in the form of an aqueous solution and have excellent handleability. In addition, the solvent of the solution formed by dissolving the heavy metal salt is not limited to water, and in the production of the (meth) acrylic acid polymer of the present invention, unless it significantly hinders the polymerization reaction, It can be used as long as the solubility of the heavy metal salt is not impaired.

  The heavy metal ions are added to the polymerization system as an aqueous solution or aqueous solution of a heavy metal salt. In the production method of the present invention, the heavy metal salt includes a heavy metal salt and a carboxyl group-containing compound when fed into the polymerization system. It is preferably supplied as an aqueous solution. When the heavy metal salt is supplied to the polymerization system as an aqueous solution containing the heavy metal salt and the carboxyl group-containing compound, the effect of heavy metal ions can be stably exhibited. There is little variation, and there is an effect that a polymer having a desired molecular weight can be stably produced. The “polymerization system” means the inside of a reaction vessel in which a polymerization reaction is carried out or is being carried out, and usually means an initially charged polymerization solvent or a polymerization solution during polymerization. When the heavy metal salt and the carboxyl group-containing compound are included, the ratio of the heavy metal salt and the carboxyl group-containing compound is preferably 1 to 100 parts by mass, more preferably 10 to 80 parts by mass with respect to 100 parts by mass of the heavy metal salt. is there.

  The heavy metal salt aqueous solution added to the polymerization system is preferably set so that the pH of the aqueous solution is 8 or less, more preferably 7 or less, and 6 or less. Is particularly preferred.

  The carboxyl group-containing compound is an organic compound having a carboxyl group, for example, acetic acid, propionic acid, butyric acid, formic acid, oxalic acid, succinic acid, glycolic acid, glyoxylic acid, etc., but from the viewpoint of reducing impurities, A compound having a polymerizable unsaturated double bond is preferred, and examples thereof include (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, 2-methyleneglutaric acid and the like, and anhydrides thereof.

  The content of the heavy metal ions is preferably 0.1 to 10 ppm with respect to the total mass of the polymerization reaction solution at the completion of the polymerization reaction. If the content of heavy metal ions is less than 0.1 ppm, the effect of heavy metal ions may not be sufficiently exhibited. On the other hand, if the content of heavy metal ions exceeds 10 ppm, the color tone of the resulting polymer may be deteriorated. Moreover, when there is much content of heavy metal ion, when using the polymer which is a product, for example as a detergent builder, there exists a possibility of causing the stain | pollution | contamination of a builder for detergents.

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 subsequently 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.
The concentration of the heavy metal compound in the aqueous solution or aqueous solution obtained by dissolving the heavy metal compound added to the polymerization system is preferably 0.1% by mass to 10% by mass.

  Examples of the polymerization initiator decomposition catalyst other than heavy metal ions (heavy metal salts) include metal halides such as lithium chloride and lithium bromide; metal oxides such as titanium oxide and silicon dioxide; hydrochloric acid, hydrobromic acid, Metal salts of inorganic acids such as perchloric acid, sulfuric acid and nitric acid; Carboxylic acids such as formic acid, acetic acid, propionic acid, lactic acid, isolacric acid and benzoic acid, their esters and metal salts thereof; pyridine, indole, imidazole, carbazole, etc. And heterocyclic amines thereof and derivatives thereof. These decomposition catalysts may be used alone or in combination of two or more.

  In addition, examples of reducing compounds other than heavy metal ions (heavy metal salts) include, for example, boron trifluoride ether adducts, inorganic compounds such as perchloric acid; sulfur dioxide, sulfites, sulfate esters, bisulfites, and thiosulfuric acid. Sulfur-containing compounds such as salts, sulfoxylate salts, benzenesulfinic acid and its substitutes, and homologues of cyclic sulfinic acids such as p-toluenesulfinic acid; octyl mercaptan, dodecyl mercaptan, mercaptoethanol, α-mercaptopropionic acid, thioglycolic acid , Thiopropionic acid, α-thiopropionic acid sodium sulfopropyl ester, α-thiopropionic acid sodium sulfoethyl ester and other mercapto compounds; hydrazine, β-hydroxyethylhydrazine, hydroxylamine and other nitrogen-containing compounds; formaldehyde, acetoa Dehydrogenase, propionaldehyde, n- butyraldehyde, isobutyraldehyde, aldehydes such as isovaleric aldehyde; ascorbic acid and the like. These reducing compounds may also be used alone or in combination of two or more. A reducing compound such as a mercapto compound may be added as a chain transfer agent.

  The total amount of the chain transfer agent, the initiator, and the reaction accelerator is preferably 2 to 20 g with respect to 1 mol of all monomer components. By setting it as such a range, the (meth) acrylic acid polymer of the present invention can be produced efficiently, and the molecular weight distribution of the (meth) acrylic acid polymer can be made desired. it can. More preferably, it is 2.5-18g, More preferably, it is 3.0-15g.

  In the method for producing the (meth) acrylic acid polymer of the present invention, in addition to the polymerization initiator, the chain transfer agent, and the reaction accelerator, a pH adjuster, a buffering agent, and the like can be used as necessary.

(Polymerization solution)
The (meth) acrylic acid polymer of the present invention is preferably produced by solution polymerization. The solvent that can be used in this case is preferably a mixed solvent in which 50% by mass of water or water is based on the total solvent. When only water is used, it is preferable in that the solvent removal step can be omitted. Here, as a solvent that can be used together with water during polymerization, alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol; glycerin; polyethylene glycol; aromatic or aliphatic such as benzene, toluene, xylene, cyclohexane, and n-heptane Preferred are hydrocarbons; esters such as ethyl acetate; ketones such as acetone and methyl ethyl ketone; amides such as dimethylformaldehyde; ethers such as diethyl ether and dioxane. These may be used alone or in combination of two or more. Among these, it is preferable to use one or more solvents selected from the group consisting of water and lower alcohols having 1 to 4 carbon atoms from the viewpoint of the solubility of the monomer component and the resulting polymer. .

(Other manufacturing conditions)
The (meth) acrylic acid polymer of the present invention is characterized by being produced in a batch type (batch type). The conditions for producing the (meth) acrylic acid polymer of the present invention are the same as those described above. In addition, as long as there is no notice in particular, the well-known polymerization method or the method which modified the well-known method can be used.

  The temperature during the polymerization is preferably 70 ° C or higher, more preferably 75 to 110 ° C, and still more preferably 80 to 100 ° C. If the temperature at the time of polymerization is in the above range, the residual monomer component is reduced and the dispersibility of the polymer tends to be improved. The temperature at the time of polymerization need not always be kept constant during the progress of the polymerization reaction. For example, the polymerization is started from room temperature, and the temperature is increased to a set temperature at an appropriate temperature increase time or temperature increase rate. Thereafter, the set temperature may be maintained, or the polymerization temperature may be varied (increased or decreased) over time during the course of the polymerization reaction, depending on the dropping method of the monomer component, initiator, and the like. Also good.

  The pressure in the reaction system may be any of normal pressure (atmospheric pressure), reduced pressure, and increased pressure, but from the viewpoint of the molecular weight of the polymer obtained, the reaction system is sealed under normal pressure. However, it is preferably performed under pressure. Moreover, it is preferable to carry out under normal pressure (atmospheric pressure) in terms of equipment such as a pressurizing device, a decompressing device, a pressure-resistant reaction vessel, 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.

[Reactor]
A reactor suitably used for carrying out the production method of the present invention will be described. The reactor used in the production method of the present invention has a polymerization reactor (polymerization reaction kettle) and a supply path for adding the monomer (1) to the polymerization reactor. There is no restriction | limiting in particular about another form.

  It is preferable that a stirrer is installed in the polymerization reaction kettle. This stirrer prevents the uneven distribution of temperature and concentration in the polymerization reaction vessel in the polymerization step (including the neutralization step if applicable), so that the polymerization reaction and the neutralization treatment are performed uniformly. It functions as a stirring means for stirring the solution in the polymerization reaction kettle.

It is preferable that an outer jacket is provided around the outer peripheral portion of the side surface (or bottom surface) of the polymerization reaction kettle body. The outer jacket functions as a temperature adjusting means for adjusting the temperature of the reaction solution in the polymerization reaction kettle in the polymerization step (including a neutralization step if applicable). It is preferable to provide an appropriate switching mechanism so that the heat medium and the refrigerant can be passed.
It is preferable that a measuring device, a control device, and the like necessary for the polymerization step (including a neutralization step if applicable) are provided as appropriate.

  The reactor has a path for externally circulating the reaction liquid in the polymerization reactor and a heat removal device for removing heat from the reaction liquid circulating in the external circulation path, thereby enabling efficient heat removal of the polymerization heat. Become. According to such a form, it is possible to perform the polymerization reaction under mild conditions as compared with heat removal using the latent heat of the solvent using a condenser and cooling from the outside using a jacket. In addition, strict temperature control is possible. In order to improve the clay dispersibility of the polymer obtained due to these reasons, the reaction apparatus has an external circulation path for the reaction liquid and a heat removal apparatus for removing heat from the reaction liquid circulating in the external circulation path. It is particularly preferred.

  As mentioned above, although the reaction apparatus which can be used for the manufacturing method of this invention was demonstrated easily, the specific form of each component which comprises this apparatus, and the specific structure of a distillate circulation path and an external circulation path | route -There is no restriction | limiting in particular about a usage form, For example, conventionally well-known knowledge, such as Unexamined-Japanese-Patent No. 2003-268037, can be referred suitably.

  As an equipment other than the above, for example, the polymerization reactor is provided with a distillate circulation path for liquefying and condensing the gas distillate distilled from the polymerization reactor during polymerization and returning it to the polymerization reactor again. May be. In such a form, usually, a condenser for liquefying and condensing gaseous distillate flowing in the distillate circulation path is provided on the path. Moreover, the capacitor | condenser may illustrate the form which each connects the introduction path | route for introducing a cooling fluid, and the discharge path for discharging | emitting the cooling fluid after heat exchange.

[(Meth) acrylic acid polymer composition (polymer composition)]
In the polymer composition of the present invention, the (meth) acrylic acid polymer of the present invention is essential. In addition, an unreacted (meth) acrylic acid-based monomer, an unreacted polymerization initiator, a polymerization initiator decomposition product, and the like may be included.

  The content of the unreacted monomer present in the polymer composition varies depending on the type of monomer used, but is preferably less than 1% by mass with respect to 100% by mass of the solid content of the polymer composition. . More preferably, it is less than 0.5% and less than 0.1%.

  The polymer composition referred to in the present application is not particularly limited, but is preferably obtained without a purification step such as impurity removal from the viewpoint of production efficiency. Furthermore, after the polymerization step, the obtained polymerization composition is diluted with a small amount of water (about 1 to 400% by mass with respect to the obtained mixture) for handling convenience and the like. Included in the combined composition.

The polymer composition of the present invention may contain a solvent such as water in addition to the (meth) acrylic acid polymer of the present invention (referred to as a (meth) acrylic acid polymer (water) solution). . In that case, about 30-99 mass% is preferable with respect to 100 mass% of polymer compositions, and, as for content of water, about 35-70 mass% is more preferable.
The polymer and polymer composition produced by the production method of the present invention (also referred to as the polymer of the present invention and the polymer composition of the present invention, respectively) are water treatment agents, fiber treatment agents, dispersants, detergent builders (or Detergent composition) and the like. 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.

<Water treatment agent>
The polymer and polymer composition of the present invention can be used as a water treatment agent. If necessary, the water treatment agent may contain a polymerized phosphate, phosphonate, anticorrosive, slime control agent, and chelating agent as other compounding agents.

  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 and 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 polymer composition 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 or polymer composition 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, color unevenness, dyeing tempering degree In order to improve the above, at least one selected from the group consisting of a dye, a peroxide and a surfactant is added to 1 part by weight of the polymer composition of the present invention in terms of pure amount of the fiber treatment agent. It is preferable to use a composition blended at a ratio of 0.1 to 100 parts by weight as a fiber treatment 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 composition of the present invention with an alkali agent and a surfactant. In the case of applying to the bleaching step, it is preferable to blend the polymer composition 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.

<Pigment dispersant>
The polymer and polymer composition of the present invention can be used as a pigment dispersant.
The polymer of the present invention can be used alone as a pigment dispersant, but the pigment dispersant of the present invention can be used as a solvent such as water or other compounding agents as necessary, such as condensed phosphoric acid and its components. Salts, phosphonic acids and salts thereof, and polyvinyl alcohol may be used.

The content of the (meth) acrylic acid polymer of the present invention in the pigment dispersant is preferably 0.5 to 10% by weight with respect to the entire pigment dispersant. Further, any appropriate water-soluble polymer may be included as long as it does not affect the performance and effect.
According to the present invention, it is possible to provide a paper slurry having a low viscosity and a viscosity stability with time and having a high concentration. As a result, coating defects are suppressed when coating with the slurry, good base paper coverage, printing gloss, blister resistance, uniform printing surface feeling, and the inherent whiteness and poorness of the pigment are provided. It becomes possible to provide a coated paper for printing having significant points of transparency and ink acceptability.

  The pigment used in the present invention is not particularly limited, and examples thereof include kaolin, clay, heavy calcium carbonate, light calcium carbonate, titanium dioxide, satin white, talc, aluminum hydroxide, and plastic pigment.

  In the present invention, as a method for adjusting the pigment, conventionally known methods can be referred to or combined as appropriate, and examples thereof include a method in which primary dispersion is performed and wet pulverization is performed. This method is preferable in that a high-concentration pigment slurry having a low viscosity and excellent dispersion stability can be obtained. Of course, the method for adjusting the pigment according to the present invention is not limited to this wet pulverization method, and it is not limited at all to adopt an adjustment method without applying the wet pulverization treatment. In the method for preparing the pigment, the primary dispersion method is not particularly limited, but it is preferable to mix with a mixer, for example, a high-speed disper, a homomixer, a ball mill, a coreless mixer, a stirring disper, etc. It is preferable to use a high one.

  During the wet pulverization treatment, the (meth) acrylic acid polymer of the present invention may be charged into a pulverizer and pulverized. In such a case, the (meth) acrylic acid polymer also plays a role as a grinding aid.

  The average particle size of the pigment contained in the slurry is preferably 1.5 μm or less, more preferably 1.0 μm or less. In addition, the average particle diameter said here is a particle diameter measured with the laser particle size distribution meter which was used in the below-mentioned Example. The desired particle size is preferably 85% or more, more preferably 88% or more.

  When the pigment dispersant is used as a pigment dispersant, the amount of the pigment dispersant used is 0.1 to 2.0 parts by mass with respect to 100 parts by mass of the (meth) acrylic acid polymer of the present invention. It is preferable that When the amount of the 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 pigment slurry in the present invention preferably has a solid content concentration of 65% by mass or more.

The viscosity of the pigment slurry is not particularly limited, but is preferably 1000 mPa · s or less, and more preferably 600 mPa · s or less. When it is higher than 1000 mPa · s, when the coating liquid prepared with the slurry as a main component is applied while receiving a high shearing force at high speed, coating defects such as streak, bleeding and sarcophagus are likely to occur. There is a possibility that an excellent coated paper texture cannot be obtained.
The pigment slurry viscosity is measured using a B-type viscometer. The value measured at 3, 60 rpm for 1 minute.

<Detergent composition>
The polymer composition of the present invention can also be added to a detergent composition.
The polymer composition of the present invention includes the (meth) acrylic acid polymer described above, but the content of the (meth) acrylic acid polymer in the detergent composition is not particularly limited. However, from the viewpoint that excellent builder performance can be exhibited, the content of the (meth) acrylic acid polymer is preferably 0.1 to 15% by mass with respect to the total amount of the detergent composition, and 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 may be a powder detergent composition or 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.
Examples of the anionic surfactant include alkylbenzene sulfonate, alkyl ether sulfate, alkenyl ether sulfate, alkyl sulfate, alkenyl sulfate, α-olefin sulfonate, α-sulfo fatty acid or ester salt, alkane sulfonate. , Saturated fatty acid salt, unsaturated fatty acid salt, alkyl ether carboxylate, alkenyl ether carboxylate, amino acid type surfactant, N-acyl amino acid type surfactant, alkyl phosphate ester or salt thereof, alkenyl phosphate ester or Its salts are preferred. An alkyl group such as a methyl group may be branched from the alkyl group or alkenyl group in these anionic surfactants.
Nonionic surfactants include polyoxyalkylene alkyl ethers, polyoxyalkylene alkenyl ethers, polyoxyethylene alkyl phenyl ethers, higher fatty acid alkanolamides or alkylene oxide adducts thereof, sucrose fatty acid esters, alkyl glycoxides, fatty acid glycerin monoesters. Esters, alkylamine oxides and the like are preferred. An alkyl group such as a methyl group may be branched from the alkyl group or alkenyl group in these nonionic surfactants.
As the cationic surfactant, a quaternary ammonium salt or the like is suitable. As the amphoteric surfactant, a carboxyl type amphoteric surfactant, a sulfobetaine type amphoteric surfactant, and the like are suitable. The alkyl group and alkenyl group in these cationic surfactants and amphoteric surfactants may be branched from an alkyl group such as a methyl group.
The blending ratio of the surfactant is usually 10 to 60% by mass, preferably 15 to 50% by mass, more preferably 20 to 45% by mass, particularly preferably based on the total amount of the detergent composition. Is 25-40 mass%. If the surfactant content is too small, sufficient detergency may not be achieved, and if the surfactant content is too high, the economy may be reduced.
Additives include anti-redeposition agent to prevent redeposition of contaminants such as alkali builder, chelate builder, sodium carboxymethyl cellulose, stain inhibitor such as benzotriazole and ethylene-thiourea, soil release agent, color transfer Inhibitors, softeners, alkaline substances for pH adjustment, fragrances, solubilizers, fluorescent agents, colorants, foaming agents, foam stabilizers, polishes, bactericides, bleaching agents, bleaching aids, enzymes, dyes A solvent or the like is preferable. In the case of a powder detergent composition, it is preferable to blend zeolite.
The detergent composition may include other detergent builders in addition to the polymer composition of the present invention. Examples of other detergent builders include, but are not limited to, alkali builders such as carbonates, hydrogen carbonates, and silicates, tripolyphosphates, pyrophosphates, bow glass, nitrilotriacetate, ethylenediaminetetraacetate, Examples thereof include chelate builders such as acid salts, fumarate salts and zeolites, and carboxyl derivatives of polysaccharides such as carboxymethyl cellulose. Examples of the counter salt used in the builder include alkali metals such as sodium and potassium, ammonium and amine.
The total blending ratio of the additive and other builder for detergent is usually preferably 0.1 to 50% by mass with respect to 100% by mass of the cleaning composition. More preferably, it is 0.2-40 mass%, More preferably, it is 0.3-35 mass%, Most preferably, it is 0.4-30 mass%, Most preferably, it is 0.5-20 mass% or less. It is. If the additive / other detergent builder content is less than 0.1% by mass, sufficient detergent performance may not be achieved, and if it exceeds 50% by mass, the economy may be reduced.
In addition, the concept of the above-mentioned detergent composition includes specific detergents such as synthetic detergents for household detergents, textile industry and other industrial detergents, hard surface cleaners, and bleaching detergents that enhance one of the components. Also included are detergents that are only used.
When the detergent composition is a liquid detergent composition, the amount of water contained in the liquid detergent composition is usually preferably 0.1 to 75% by mass, more preferably based on the total amount of the liquid detergent composition. Is 0.2 to 70% by mass, more preferably 0.5 to 65% by mass, even more preferably 0.7 to 60% by mass, particularly preferably 1 to 55% by mass, Preferably it is 1.5-50 mass%.
When the detergent composition is a liquid detergent composition, the detergent composition preferably has a kaolin turbidity of 200 mg / L or less, more preferably 150 mg / L or less, and even more preferably 120 mg / L or less. Especially preferably, it is 100 mg / L or less, Most preferably, it is 50 mg / L or less.
Further, the change (difference) in kaolin turbidity with and without adding the polymer composition of the present invention as a detergent builder to the liquid detergent composition is preferably 500 mg / L or less, more preferably It is 400 mg / L or less, more preferably 300 mg / L or less, particularly preferably 200 mg / L or less, and most preferably 100 mg / L or less. As the kaolin turbidity value, a value measured by the following method is adopted.

<Measurement method of kaolin turbidity>
A sample (liquid detergent) uniformly stirred in a 50 mm square cell having a thickness of 10 mm was removed and air bubbles were removed. Then, a NDU2000 manufactured by Nippon Denshoku Co., Ltd. Kaolin turbidity: mg / L) is measured.
Proteases, lipases, cellulases, and the like are suitable as enzymes that can be incorporated into the cleaning composition. Of these, proteases, alkaline lipases, and alkaline cellulases that are highly active in an alkaline cleaning solution are preferred.
The amount of the enzyme added is preferably 5% by mass or less with respect to 100% by mass of the cleaning composition. If it exceeds 5% by mass, improvement in detergency cannot be seen, and the economy may be reduced.
Even when the detergent composition is used in an area of hard water (for example, 100 mg / L or more) having a high concentration of calcium ions and magnesium ions, salt precipitation is small and has an excellent cleaning effect. This effect is particularly pronounced when the detergent composition contains an anionic surfactant such as LAS.

The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples. Unless otherwise specified, “part” means “part by mass” and “%” means “% by mass”.
In addition, the weight average molecular weight, number average molecular weight, quantification of unreacted monomer, polymer composition, and solid content of the aqueous polymer solution of the (meth) acrylic acid polymer of the present invention were measured according to the following methods. .

<Measurement conditions of weight average molecular weight and number average molecular weight (GPC)>
Apparatus: L-7000 series manufactured by Hitachi, Ltd. Detector: HITACHI UV Detector L-2400
Column: Tosoh TSK-GEL G3000PWXL
Column temperature: 40 ° C
Flow rate: 0.5 mL / min
Calibration curve: POLYETHYLENGLYCOL STANDARD made by Soka Science Co., Ltd.
Eluent: 0.1N sodium acetate / acetonitrile = 3/1 (mass ratio)
<Polymer composition, method for measuring solid content of polymer aqueous solution>
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 170 ° C. From the weight change before and after drying, the solid content (%) and the volatile component (%) were calculated.

<Measurement of monomer in polymer composition>
The monomer was measured using liquid chromatography under the conditions shown in Table 1 below.
Measuring device: L-7000 series detector manufactured by Hitachi, Ltd .: UV detector L-7400 manufactured by Hitachi, Ltd.
Column: SHODEX RSpak DE-413 manufactured by Showa Denko Co., Ltd.
Temperature: 40.0 ° C
Eluent: 0.1% phosphoric acid aqueous solution Flow rate: 1.0 ml / min.

<Evaluation example>
Maruo Calcium Co., Ltd., put 200 parts by weight of heavy calcium carbonate powder into a 500 ml SUS container, and attach a stir seal to the widest mouth at the top of the lid of a glass four-necked separable flask. The attached SUS stirring blade is attached, the remaining mouth is covered with a silicone rubber stopper, and the SUS container and the upper part of the glass lid are fixed at two locations with fixing stoppers. The SUS stirring blade and a powerful stirring motor were connected, and the entire container was firmly fixed to the support so as not to loosen during the pulverization.
Subsequently, one of the silicone rubber stoppers of the four-necked separable flask is opened, a funnel is inserted, and the stirring motor is stirred at a low speed of about 200 to 300 rpm. A mixture of 5 parts by mass and 45.5 parts by mass of pure water and 500 parts by mass of 2 mm ceramic beads were added little by little in order. After all of them were put in, a silicone rubber stopper was attached, and while removing heat with a water bath, the number of rotations was increased to 1000 rpm at a stretch. In this state, pulverization was continued for about 100 minutes until the particle size of 2 μm or less reached 90% or more. On the way, a 10% concentration polymer solution was added in several batches, and finally the amount of polymer added was 0.85% by mass with respect to heavy calcium carbonate. After grinding, the contents were separated from the ceramic and collected.
The particle size was analyzed with a Hitachi laser particle size distribution analyzer LA-910.
Further, the viscosity immediately after the separated and recovered slurry and the viscosity after one week were measured with a B-type viscometer (rotor No. 3, 60 rpm, 1 minute).

<Example 1>
Batch type polymerization kettle (manufactured by SUS), thermometer, stirrer (paddle blade), external distillate circulation path and jacket, supply path (for polymerization composition and neutralizer) ), And a reaction apparatus (see FIG. 1) having an external circulation cooling apparatus (external reaction liquid circulation path and heat removal apparatus), polymerization was carried out under the following polymerization prescription and conditions. Ion exchanged water 515.0 parts by mass, Mole salt 0.05 parts by mass, 45% by mass sodium hypophosphite aqueous solution (hereinafter also referred to as “45% SHP”) 31.2 parts by mass were charged. The iron ion concentration in the charged solution was 1 mass ppm with respect to the final polymer aqueous solution. Thereafter, the temperature of the aqueous solution was raised to 80 ° C. with an external jacket at room temperature while stirring the aqueous solution in the polymerization kettle.
Next, 900 parts by mass of 80% by mass acrylic acid aqueous solution (hereinafter also referred to as “80% AA”), 66.7 parts by mass of 45% SHP, and 15% by mass sodium persulfate aqueous solution (hereinafter “15% NaPS”) Also, 66.7 parts by mass of each of the tip nozzles through separate supply paths are added dropwise for 80% AA and 45% SHP over 60 minutes and 15% NaPS simultaneously with 80% AA in 65 minutes. It was dropped over a period of time (that is, up to 5 minutes after the end of dropping of 80% AA). The dropping of each component was continuously performed at a constant dropping rate.
Thereafter, the reaction solution was cooled to 50 ° C., and 808.0 parts by mass of a 48% by mass aqueous sodium hydroxide solution was dropped into the polymerization kettle from the tip nozzle through the supply path to neutralize the polymer. During the neutralization of the polymer, the reaction solution was cooled by a heat removal device while always circulating the reaction solution externally.
As described above, a sodium polyacrylate aqueous solution (1) was obtained. The degree of neutralization of sodium polyacrylate (referred to as polymer (1)) in the obtained aqueous solution (1) was 97%. Polymerization average molecular weight (Mw) 6700 and polymerization average molecular weight (Mw) / number average molecular weight (Mn) of sodium polyacrylate in the obtained sodium polyacrylate aqueous solution (1) were 2.16. The polymerization prescription is shown in Table 1, and the analysis results of the obtained polymer are shown in Table 2.
When the slurry viscosity of heavy calcium carbonate was evaluated by the above method, the slurry viscosity immediately after pulverization was 570 mPa · s, and the slurry viscosity after 1 week was 650 mPa · s. The evaluation results are shown in Table 2.

<Example 2>
A sodium polyacrylate aqueous solution (2) was obtained in the same manner as in Example 1 except that the polymerization conditions were changed to those described in Table 1. The degree of neutralization of sodium polyacrylate (referred to as polymer (2)) in the obtained aqueous solution (2) was 97%. Polymerization average molecular weight (Mw) 6200 and polymerization average molecular weight (Mw) / number average molecular weight (Mn) of sodium polyacrylate in the obtained sodium polyacrylate aqueous solution (2) were 2.16. The polymerization prescription is shown in Table 1, and the analysis results of the obtained polymer are shown in Table 2.
As in Example 1, when the slurry viscosity of heavy calcium carbonate was evaluated by the above-described method, the slurry viscosity immediately after pulverization was 650 mPa · s, and the slurry viscosity after one week was 810 mPa · s. The evaluation results are shown in Table 2.

<Example 3>
A sodium polyacrylate aqueous solution (3) was obtained in the same manner as in Example 1 except that the polymerization conditions were changed to those described in Table 1. The degree of neutralization of sodium polyacrylate (referred to as polymer (3)) in the obtained aqueous solution (3) was 97%. The polymerization average molecular weight (Mw) 6500 and polymerization average molecular weight (Mw) / number average molecular weight (Mn) of sodium polyacrylate in the obtained sodium polyacrylate aqueous solution (3) were 2.19. The polymerization prescription is shown in Table 1, and the analysis results of the obtained polymer are shown in Table 2.
As in Example 1, when the slurry viscosity of heavy calcium carbonate was evaluated by the above-described method, the slurry viscosity immediately after pulverization was 530 mPa · s, and the slurry viscosity after one week was 710 mPa · s. The evaluation results are shown in Table 2.

<Comparative Example 1>
A comparative sodium polyacrylate aqueous solution (1) was obtained in the same manner as in Example 1 except that the polymerization conditions were changed to those described in Table 1. The degree of neutralization of sodium polyacrylate (referred to as comparative polymer (1)) in the obtained comparative aqueous solution (1) was 95%. The polymerization average molecular weight (Mw) 6600 and polymerization average molecular weight (Mw) / number average molecular weight (Mn) of sodium polyacrylate in the obtained sodium polyacrylate aqueous solution (1) were 2.78. The polymerization prescription is shown in Table 1, and the analysis results of the obtained polymer are shown in Table 2.
As in Example 1, when the slurry viscosity of heavy calcium carbonate was evaluated by the above-described method, the slurry viscosity immediately after pulverization was 920 mPa · s, and the slurry viscosity after 1 week was 1300 mPa · s. The evaluation results are shown in Table 2.

<Comparative Example 2>
A sodium polyacrylate comparative aqueous solution (2) was obtained in the same manner as in Example 1 except that the polymerization conditions were changed to those described in Table 1. The degree of neutralization of sodium polyacrylate (referred to as comparative polymer (2)) in the obtained comparative aqueous solution (2) was 98%. Polymerization average molecular weight (Mw) 6350 and polymerization average molecular weight (Mw) / number average molecular weight (Mn) of sodium polyacrylate in the obtained sodium polyacrylate aqueous solution (2) were 2.23. The polymerization prescription is shown in Table 1, and the analysis results of the obtained polymer are shown in Table 2.
As in Example 1, when the slurry viscosity of heavy calcium carbonate was evaluated by the above-described method, the slurry viscosity immediately after pulverization was 840 mPa · s, and the slurry viscosity after 1 week was 1020 mPa · s. The evaluation results are shown in Table 2.

From the results shown in Table 2, it has been clarified that the polymer of the present invention has a good initial dispersive force and a dispersive force over time as compared with the conventional polymer.

Claims (3)

Batch polymerization of a monomer composition containing a (meth) acrylic monomer in the presence of one or more phosphorus atom-containing compounds selected from phosphorous acid, hypophosphorous acid, and salts thereof (Meth) acrylic acid polymer obtained by
The total amount of phosphorus atom-containing compound added to the reaction system 5 minutes after the start of polymerization is 15.0 with respect to 1 mol of the total amount of (meth) acrylic acid monomer added to the reaction system 5 minutes after the start of polymerization. ~ 23.0g,
The total amount of phosphorus atom-containing compound added to the reaction system 30 minutes after the start of polymerization is 4.0 with respect to 1 mol of the total amount of (meth) acrylic acid monomer added to the reaction system 30 minutes after the start of polymerization. It was obtained so as to be -7.0 g,
(Meth) acrylic acid polymer. A pigment dispersant comprising the polymer according to claim 1. A monomer composition containing a (meth) acrylic acid monomer is polymerized in a batch system in the presence of one or more phosphorus atom-containing compounds selected from phosphorous acid, hypophosphorous acid, and salts thereof ( A method for producing a (meth) acrylic acid polymer,
The total amount of phosphorus atom-containing compound added to the reaction system 5 minutes after the start of polymerization is 15.0 with respect to 1 mol of the total amount of (meth) acrylic acid monomer added to the reaction system 5 minutes after the start of polymerization. ~ 23.0g,
The total amount of phosphorus atom-containing compound added to the reaction system 30 minutes after the start of polymerization is 4.0 with respect to 1 mol of the total amount of (meth) acrylic acid monomer added to the reaction system 30 minutes after the start of polymerization. It is adjusted so that it becomes ˜7.0 g,
A method for polymerizing a (meth) acrylic acid polymer.

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