JP3398837B2 - Acrylic acid (salt) -maleic acid (salt) copolymer, method for producing the same, and detergent composition - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to acrylic acid (salt).
Maleic acid (salt) -based copolymer, a method for producing the same, and a detergent composition.

[0002]

2. Description of the Related Art Conventionally, acrylic acid (salt) -maleic acid (salt) copolymers having a large number of carboxyl groups have been
It is known to exhibit excellent chelating and dispersing effects and is used in a wide range of applications such as detergent builders, scale inhibitors, inorganic pigment dispersants, fiber treatment agents and chelating agents.

When the copolymer is used as a detergent builder, the basic performance is calcium ion trapping ability and clay dispersing ability. The calcium ion-capturing ability is to quantify the amount of calcium ions that can be captured by the copolymer in a system in which calcium ions are present in excess. On the other hand, the clay dispersibility is represented by the turbidity of the supernatant after the clay and the copolymer are added to an aqueous solution of a specific composition to disperse the clay. The higher the turbidity, the higher the copolymer. It shows that the clay dispersibility of is excellent. Generally, the larger the molecular weight, the higher the calcium ion-capturing ability, but the lower the clay dispersing ability, and the smaller the molecular weight, the higher the clay-dispersing ability, but the lower the calcium ion-trapping ability. Therefore, it is difficult to improve both in a well-balanced manner, and many proposals have been made in the past. For example, in Japanese Patent No. 2574144, the calcium ion-capturing ability is 300 mgCaCO ₃ / g or more, and the clay-dispersing ability is 1.
A maleic acid-based copolymer having 2 or more has been proposed together with its production method. In this patent, clay dispersibility is measured using tap water in Himeji City. Japanese water, including tap water in Himeji City, is relatively low in hardness as a whole and is about 20 to 50 ppm in terms of calcium carbonate, and the conditions for dispersibility are mild. Therefore, in Japanese Patent No. 2574144, calcium is mainly used. Studies are being conducted with a focus on ion trapping ability.

[0004]

However, the water of foreign countries other than Japan often has high hardness, for example, the hardness of water in the United States and China (calculated as calcium carbonate) is as high as about 200 ppm. The copolymer of Japanese Patent No. 2574144 exhibits excellent dispersibility in low hardness water such as in Japan, but can no longer exhibit excellent dispersibility in such high hardness water. Regarding the clay dispersibility in high hardness water, the copolymer of Patent No. 2574144, which is far more technically difficult than the dispersibility in low hardness water and focuses on the calcium ion capturing ability of the prior art. You can't beat it.

In addition to Japanese Patent No. 2574144, many methods for producing an acrylic acid (salt) -maleic acid (salt) copolymer have been proposed. For example, JP-A-63-235
No. 313 discloses that acrylic acid (salt) and maleic acid
In the method for producing a maleic acid copolymer having a sulfonic acid group at the end, which is contained at a molar ratio of 00/200 to 100/25, polymerization initiation generated by reacting sulfurous acid, bisulfite, or a salt thereof with an oxidizing agent. PH is used
A method of copolymerizing in an aqueous solution maintained at 2.5 to 6.5 is disclosed. However, although this copolymer is excellent in scale-inhibiting ability, it has a problem that when it is used for detergents, its clay-dispersing ability is particularly poor under high hardness water due to the high proportion of maleic acid.

Further, Japanese Patent Laid-Open No. 58-67706 discloses that
An unsaturated monocarboxylic acid (salt) such as acrylic acid and an unsaturated dicarboxylic acid (salt) such as maleic acid are added in an amount of 90 to 40/10.
A method of polymerizing in the presence of a water-soluble initiator, used in a weight ratio of 60, is disclosed. However, in the examples, maleic acid is used at a high ratio, and since only hydrogen peroxide is used as an initiator, when used for detergents, the clay dispersibility is particularly high in highly hard water. Have the problem of being bad.

Therefore, an object of the present invention is to provide an acrylic acid (salt) -maleic acid (salt) copolymer having a high clay dispersibility in high hardness water and a high calcium ion trapping ability, a method for producing the same, and a detergent. To provide a composition.

[0008]

In order to solve the above problems, the present invention provides the following configurations. An acrylic acid (salt) -maleic acid (salt) -based copolymer having a clay dispersibility in high hardness water of 50% or more and a calcium ion trapping ability of 270 mgCaCO ₃ / g or more.

Acrylic acid (salt) -maleic acid (is obtained by polymerizing a monomer component containing acrylic acid (salt) and maleic acid (salt) as main components in an aqueous solvent in the presence of at least a polymerization initiator. (Salt) -based copolymer, which is calculated from the weight of raw materials fed to the reactor.
That the solid content of the theoretical after completion of the polymerization of the polymer is not less 40% by weight or more, 95 to 80/5 to the amount of usage and maleic acid (salt) of acrylic acid (salt) in a molar ratio It is in the range of 20 and is characterized in that (1) persulfate and bisulfite are used together as a polymerization initiator, and / or (2) hydrogen peroxide and polyvalent metal ion are used together. And a method for producing an acrylic acid (salt) -maleic acid (salt) copolymer.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The copolymer of the present invention will be described in detail below together with the production method. The acrylic acid-maleic acid type copolymer of the present invention has a clay dispersibility of 50 in high hardness water.
% Or more, calcium ion trapping ability is 270 mgC
It is aCO ₃ / g or more. The clay dispersibility in high hardness water is preferably 55% or more, more preferably 60% or more. The higher the clay dispersibility in high hardness water is, the more preferable. However, in order to obtain a copolymer exceeding 90%, the production efficiency may be reduced or the cost may be increased. Calcium ion capture capacity is 300 mg CaCO ₃ /
It is preferably at least g. The higher the calcium ion scavenging ability is, the more preferable, but production efficiency may be lowered or the cost may be increased in order to obtain a copolymer exceeding 450 mgCaCO ₃ / g. The "clay dispersibility in high hardness water" and the "calcium ion trapping ability" referred to in the present invention.
Is measured by the measuring method described in the examples.

A copolymer excellent in both clay dispersibility in high hardness water and calcium ion trapping ability is a novel and excellent one which has never existed before. In particular, “clay dispersibility in high hardness water” is a new index found as a result of the study by the present inventors, and is a conventionally known index “low hardness water (about 20 to 50 ppm in terms of calcium carbonate). The value cannot be predicted from the clay dispersibility in). Even when the copolymers have the same "clay dispersibility in low hardness water", there are many cases where a significant difference is seen in comparison with the more severe condition "clay dispersibility in high hardness water". Exists. Moreover, the copolymer of the present invention is not only excellent in "clay dispersibility in high-hardness water", but also shows a sufficiently high value in "calcium ion trapping ability", and exhibits excellent washing ability in a good balance as a whole. It is a thing.

The copolymer of the present invention is mainly composed of maleic acid (salt) units (MA (mol%)) and its copolymerization weight in terms of clay dispersibility in high hardness water. The product (MA × Mw) of the combined weight average molecular weight (Mw) is 15
It is preferable that it is 50,000 or less and Mw is 20,000 or less. This is because as the proportion of maleic acid (salt) units increases and as the molecular weight increases, the calcium ion-capturing ability increases, but the clay-dispersing ability tends to decrease.
The higher the unit ratio, the more severe the upper limit of the weight average molecular weight becomes. For example, when MA is 7.5 mol% or less, Mw is preferably 20,000 or less, when MA is 10 mol%, Mw is preferably 15,000 or less, and when MA is 15 mol% or less, 10,000 or less. Is preferred.

In order to achieve both the ability to disperse clay in high hardness water and the ability to capture calcium ions, the acrylic acid (salt) unit and the maleic acid (salt) in the copolymer of the present invention.
The molar ratio of the units is preferably 95 to 80/5 to 20, more preferably 90 to 85/10 to 15. When the maleic acid (salt) unit is less than the above range, the calcium ion capturing ability is reduced, and when the acrylic acid (salt) unit is less than the above range, the clay dispersibility in high hardness water is reduced.

The ratio (MA) of maleic acid (salt) units and the molar ratio of acrylic acid (salt) units to maleic acid (salt) units in the above copolymer are controlled by the charging ratio. Therefore, in order to obtain the copolymer of the present invention, maleic acid (salt) is contained at a low ratio (in other words, acrylic acid (salt) is contained at a high ratio).
It is preferable to carry out the polymerization using a monomer component and by a method in which the weight average molecular weight does not become too large. From the viewpoint of clay dispersibility in high hardness water, it is preferable that the molecular weight distribution of the polymer is narrow, and therefore it is preferable to pay attention to this point as well. Conventionally, when aiming at both the ability to disperse clay in low hardness water and the ability to capture calcium ions, the focus was mainly on the ability to capture calcium ions,
A monomer component containing a large amount of maleic acid (salt) was used. Since maleic acid (salt) has low reactivity, polymerization is generally performed at a high polymerization concentration (theoretical solid concentration of the polymer after completion of polymerization), and as a result, a polymer having a relatively low molecular weight is obtained. can get. However, even if the same method is applied as it is to a monomer component containing a large amount of acrylic acid (salt), acrylic acid (salt) is very reactive unlike maleic acid (salt), and therefore at a high concentration. Polymerization results in a polymer having a very high molecular weight. On the other hand, when the polymerization is carried out at a low concentration, a low molecular weight polymer is obtained, but the molecular weight distribution becomes wide, so that the clay dispersibility in high hardness water becomes poor.

That is, in order to obtain the copolymer of the present invention, it is necessary to strictly specify the polymerization conditions, and as a result of intensive studies by the present inventors, the production method of the present invention as shown below was obtained. It has arrived. The manufacturing method of the present invention will be described below. In the production method of the present invention, a monomer component containing acrylic acid (salt) and maleic acid (salt) as main components is used. To include as a main component means
The proportion of the total amount of acrylic acid (salt) and maleic acid (salt) in the monomer component is 85 mol% or more, preferably 90 mol% or more, and more preferably 95 mol% or more. .

As acrylic acid (salt), acrylic acid,
Any of the acrylic acid salts may be used, and a mixture thereof may be used, but acrylic acid is preferably used. Examples of the acrylate include alkali metal acrylates such as sodium acrylate and potassium acrylate, ammonium acrylate, or salts of organic amines of acrylic acid. Acrylic acid (salt) is preferably 70% by weight or more, more preferably 90% by weight or more, and even more preferably the entire amount is supplied dropwise to the reactor. When a persulfate and a bisulfite are used together as a polymerization initiator as described below, the degree of neutralization at the end of the addition is preferably 15 mol% or less of the total amount of acrylic acid and maleic acid. More preferably, it is at most mol%. When hydrogen peroxide and polyvalent metal ions are used in combination as the polymerization initiator, the degree of neutralization at the end of dropping is preferably 30 mol% or less of the total amount of acrylic acid and maleic acid, and 20 mol% or less. Is more preferable.
Neutralization may be carried out in advance before being supplied to the reactor, or an acid and a base may be separately supplied to the reactor for neutralization in the reactor.

The maleic acid (salt) may be any of maleic anhydride, maleic acid and maleate, and a mixture of two or more of them may be used. Examples of the maleate salt include hydroxides of alkali metals such as sodium hydroxide and potassium hydroxide, salts of organic amines such as ammonia and monoethanolamine. Maleic acid (salt) is preferably 50% by weight or more,
More preferably, 80% by weight or more, and even more preferably the entire amount is initially charged in the reactor. When a persulfate and a bisulfite are used together as a polymerization initiator as described below, the degree of neutralization of maleic acid is preferably 5 to 30 mol%, more preferably 10 to 25 mol%. When hydrogen peroxide and a polyvalent metal ion are used together as a polymerization initiator, the degree of neutralization of maleic acid is arbitrary, but 10 to 50 mol% is preferable. Neutralization may be carried out in advance before being supplied to the reactor, or an acid and a base may be separately supplied to the reactor for neutralization in the reactor.

Regarding the amount of acrylic acid (salt) and maleic acid (salt) used, it is necessary that the molar ratio of acrylic acid (salt) and maleic acid (salt) is 95-80 / 5-20. 90-85 / 10-15 are more preferable. If the amount of maleic acid (salt) used is less than the above range, the calcium ion-capturing ability is reduced, and if the amount of acrylic acid (salt) used is less than the above range, the clay dispersibility in high hardness water is reduced.

In the present invention, as the monomer component, monomers other than acrylic acid (salt) and maleic acid (salt) can be contained as long as the effects of the present invention are not impaired. Such a monomer may be one that can be copolymerized with acrylic acid (salt) and maleic acid (salt), and examples thereof include unsaturated monocarboxylic acid-based monomers such as methacrylic acid and crotonic acid; Neutralized products obtained by partially or completely neutralizing unsaturated monocarboxylic acid type monomers with monovalent metals, divalent metals, ammonia, organic amines; fumaric acid, itaconic acid, citraconic acid, etc. Saturated dicarboxylic acid type monomer; Neutralized product obtained by partially or completely neutralizing the above unsaturated dicarboxylic acid type monomer with monovalent metal, divalent metal, ammonia, organic amine, etc .; (meth) Amide-based monomers such as acrylamide and t-butyl (meth) acrylamide; (meth) acrylic acid ester,
Hydrophobic monomers such as styrene, 2-methylstyrene, vinyl acetate; vinylsulfonic acid, allylsulfonic acid, methallylsulfonic acid, styrenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 3-allyloxy-
Unsaturated sulfonic acid-based monomers such as 2-hydroxypropanesulfonic acid, sulfoethyl (meth) acrylate, sulfopropyl (meth) acrylate, 2-hydroxysulfopropyl (meth) acrylate, and sulfoethylmaleimide; Monomer as monovalent metal, 2
Neutralized product obtained by partially or completely neutralizing with a valent metal, ammonia, an organic amine or the like; 3-methyl-2-butene-1-
All (prenol), 3-methyl-3-butene-1-
All (isoprenol), 2-methyl-3-butene-
2-ol (isoprene alcohol), 2-hydroxyethyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, polyethylene glycol monoisoprenol ether, polypropylene glycol monoisoprenol ether, polyethylene glycol mono Allyl ether, polypropylene glycol monoallyl ether, glycerol monoallyl ether, α-
Hydroxyl acrylic acid, N-methylol (meth) acrylamide, glycerol mono (meth) acrylate, unsaturated alcohol containing hydroxyl group such as vinyl alcohol; cationic such as dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide Monomer;
Nitrile-based monomers such as (meth) acrylonitrile; phosphorus-containing monomers such as (meth) acrylamidomethanephosphonic acid, (meth) acrylamidomethanephosphonic acid methyl ester, and 2- (meth) acrylamido-2-methylpropanephosphonic acid. , Etc., but are not particularly limited. These monomers may be used alone or in combination of two or more.

In the production method of the present invention, as the polymerization initiator, (1) persulfate and bisulfite are used in combination, and / or (2) hydrogen peroxide and polyvalent metal ion are used in combination. It is necessary. Although any of persulfates, bisulfites, hydrogen peroxide, and polyvalent metal ions are already known as polymerization initiators along with other polymerization initiators (azo compounds, organic peroxides, etc.). According to the findings of the present inventors, whether a persulfate and a bisulfite are used in combination,
And / or only when hydrogen peroxide and polyvalent metal ions are used in combination, the clay dispersibility in high hardness water, which is the object of the present invention, is 50% or more, and the calcium ion trapping ability is 270 mgCaCO ₃ / g. The above-mentioned copolymer can be obtained. When persulfate, bisulfite, hydrogen peroxide, or polyvalent metal ion is used alone or in combination with other compounds (for example, air and bisulfite are used together), the above compound is used. When used in a combination other than the above (for example, persulfate in combination with hydrogen peroxide), the copolymer of the present invention cannot be obtained. However, to the extent that the effects of the present invention are not impaired, in addition to persulfate and bisulfite, other polymerization initiators are used in combination, and similarly hydrogen peroxide and polyvalent metal ions are further added. It is possible to use a polymerization initiator together.

The case where a persulfate and a bisulfite are used together as a polymerization initiator will be described. As persulfate,
Sodium persulfate, potassium persulfate, ammonium persulfate and the like are preferable, and one or more of these can be used. As the bisulfite, sodium bisulfite, potassium bisulfite, ammonium bisulfite and the like are preferable, and one or more of these can be used.

The amount of persulfate used and the amount of bisulfite used are preferably in the range of 1 / 0.5 to 1/5 by weight, and more preferably in the range of 1/1 to 1/2. More preferable.
When the amount of persulfate used is less than the above range, the molecular weight tends to increase, and when the amount of bisulfite used is less than the above range, the molecular weight distribution tends to widen.

The total amount of persulfate and bisulfite used is
The amount is preferably 5 to 15 g, and more preferably 10 to 15 g, relative to 1 mol of the monomer component. If the total amount used is less than the above range, the molecular weight tends to increase and the molecular weight distribution tends to broaden, and even if the total amount used exceeds the above range, the effect of addition will no longer appear.

It is preferable that both the persulfate and the bisulfite are supplied to the reactor in an amount of 80% by weight or more, and more preferably all of them are added dropwise. When the amount of persulfate or bisulfite supplied by dropping is less than 80% by weight, that is, when 20% by weight or more is initially charged, it is not effectively used and decomposition is likely to occur in the initial stage. The dropping time of the persulfate and bisulfite is preferably within 20 minutes before and after the dropping time of the monomer component, and more preferably within 10 minutes.

The case where hydrogen peroxide and a polyvalent metal ion are used together as a polymerization initiator will be described. The amount of hydrogen peroxide used is preferably 5 to 15 g, and more preferably 8 to 12 g, relative to 1 mol of the monomer component. If the amount of hydrogen peroxide used is less than the above range, the molecular weight tends to increase and the molecular weight distribution tends to widen, and even if the amount of hydrogen peroxide used exceeds the above range, the effect of addition no longer appears. It is in.

Hydrogen peroxide is preferably 80% by weight or more,
More preferably, it is preferable to supply the whole amount dropwise to the reactor. The amount of hydrogen peroxide supplied by dropping is 80
If it is less than 20% by weight, that is, if 20% by weight or more is initially charged, it is not effectively used and decomposition is likely to occur in the initial stage. Further, the dropping time of hydrogen peroxide is preferably completed 20 minutes or more earlier than the dropping of the monomer component.

As the polyvalent metal ions, iron ions (Fe
²⁺, Fe³⁺), Vanadium ion (V²⁺, V³⁺, V
O²⁺), Copper ion (Cu²⁺) One or more
Is preferable, and iron ion is particularly preferable.
There is no particular limitation on the supply form of polyvalent metal ions,
Metal and / or metallization that ionizes in the polymerization reaction system
Compounds can be used. For example, vana oxytrichloride
Dium, vanadium trichloride, vanadium oxalate, sulfuric acid
Vanadium, vanadic anhydride, ammoni metavanadate
Um, ammonium sulfate hypovanadas ((NH_Four)₂S
O_Four・ VSO_Four・ 6H ₂O), ammonium sulfate vanadas
((NH_Four) V (SO_Four)₂・ 12H₂O), copper acetate (I
I), copper (II) bromide, copper (II) acetyl acetate, salt
Cupric chloride, copper carbonate, copper (II) chloride, copper (II) citrate,
Copper (II) formate, Copper (II) hydroxide, Copper (II) oleate,
Copper maleate, copper phosphate, copper (II) sulfate, iron acetyl acetate
Setonate, ammonium iron citrate, ferric oxalate
Ammonium, ferrous ammonium sulfate, ferric sulfate
Ammonium, iron citrate, iron fumarate, iron maleate,
Ferrous lactate, ferric nitrate, iron pentacarbonyl, phosphoric acid
Water-soluble metal salts such as ferric iron and ferric pyrophosphate; barium pentoxide
Nadium, copper (II) oxide, ferrous oxide, ferric oxide, etc.
Metal oxides; metal sulfides such as copper (II) sulfide and iron sulfide are listed.
You can get it.

The polyvalent metal ion (the above-mentioned metal compound and metal) is preferably 80% by weight or more, and more preferably the whole amount is initially charged in the reaction vessel. The polyvalent metal ion is preferably used in an amount of 5 to 500 ppm with respect to the total amount of the reaction solution, more preferably 10 to 500 ppm.
It is 400 ppm. When the amount of polyvalent metal ion used is less than the above range, the decomposition efficiency of hydrogen peroxide tends to be poor, and when the amount of polyvalent metal ion used is more than the above range, it may cause coloring. Also, the effect of addition is unlikely to appear.

An aqueous solvent is used as the polymerization solvent. In particular, an aqueous solvent containing 80% by weight or more of water and less than 20% by weight of an organic solvent is preferable, and water is more preferable.
The organic solvent used for the aqueous solvent, methanol,
One or more of lower alcohols such as ethanol and isopropyl alcohol, amides such as diethylformaldehyde, ethers such as diethyl ether and the like can be mentioned.

In the present invention, the raw material fed to the reactor is
Theory of polymer after completion of polymerization, calculated from the weight of material
It is necessary that the above solid content concentration is 40% by weight or more. You
Monomer component ie above, polymerization initiator, and other raw materials used in accordance with an aqueous solvent and optionally, use such a solid concentration of 40 wt% or more of theoretical after completion of the polymerization of the polymer Must be used in quantity. The solid concentration of the該理theory is less than 40 wt%, there is a tendency that the molecular weight distribution is widened. The solid content of the該理theory, can be adjusted by the weight of each raw material supplied to the reactor by initial charge and dropping. For example, when acrylic acid or (anhydrous) maleic acid and a base such as sodium hydroxide are separately supplied to the reactor for neutralization in the reactor, it is necessary to consider that water is generated by the neutralization. There must be.

As the polymerization conditions, the temperature is preferably 80 ° C. or higher, and more preferably the temperature near the boiling point of the polymerization solvent. The pressure is not particularly limited, and may be normal pressure (atmospheric pressure), increased pressure, or reduced pressure. Further, as described above, when using persulfate and bisulfite as a polymerization initiator in combination,
The pH during polymerization is preferably 5 or less, more preferably 4 or less. If the pH during polymerization is higher than 5, the molecular weight tends to increase, which is not preferable.

Since the acrylic acid (salt) -maleic acid (salt) copolymer of the present invention has a high clay dispersibility in high hardness water and a high calcium ion trapping ability, the copolymer and the surfactant are The detergent composition of the present invention containing and exhibits extremely excellent cleaning ability. The content of the copolymer of the present invention in the detergent composition is preferably 0.1 to 20% by weight, and 0.5 to 1
5% by weight is more preferred. The blending amount of the surfactant is 5 to 7
0 wt% is preferable, and 20 to 60 wt% is more preferable.

As the surface active agent, any of anionic surface active agent, nonionic surface active agent, amphoteric surface active agent and cationic surface active agent can be used. Examples of the anionic surfactant include alkylbenzene sulfonate, alkyl or alkenyl ether sulfate, alkyl or alkenyl sulfate, α-olefin sulfonate, α-sulfo fatty acid or ester salt, alkane sulfonate, saturated or unsaturated fatty acid. Mention may be made of salts, alkyl or alkenyl ether carboxylates, amino acid type surfactants, N-acyl amino acid type surfactants, alkyl or alkenyl phosphate esters or salts thereof. Examples of nonionic surfactants include polyoxyalkylene alkyl or alkenyl ethers, polyoxyethylene alkylphenyl ethers, higher fatty acid alkanolamides or their alkylene oxide adducts, sucrose fatty acid esters, alkylglycoxides, fatty acid glycerin monoesters, and alkylamine oxides. Can be mentioned. Examples of the amphoteric surfactant include a carboxy type or sulfobetaine type amphoteric surfactant. Examples of cationic surfactants include quaternary ammonium salts.

In the detergent composition of the present invention, if necessary,
Ingredients that are commonly used in detergent compositions such as enzymes, alkali builders, chelate builders, anti-redeposition agents, fluorescent agents, bleaching agents and fragrances can also be added. The acrylic acid (salt) -maleic acid (salt) copolymer of the present invention can be used as an inorganic pigment dispersant, a water treatment agent, a fiber treatment agent, etc., as well as a detergent application.

[0035]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. Unless otherwise specified, "part" and "%" in the examples
The terms "parts by weight" and "% by weight" are used, respectively. (Method for measuring physical properties of polymer) <Weight average molecular weight (Mw)> Measured by GPC (gel permeation chromatography) -Column: GF-7MHQ (manufactured by Showa Denko) -Mobile phase: Disodium hydrogen phosphate dodecahydrate 34.5
g and 46.2 g of sodium dihydrogen phosphate dihydrate (both of which are reagent grade, all grades used for measurement below are grades) were added with pure water to a total amount of 5,000 g, and then 0.45 micron Aqueous solution filtered by membrane filter ・ Detector; UV 214nm (Waters model 481 type) ・ Pump; L-7110 (Hitachi) ・ Flow rate; 0.5 ml / min ・ Temperature; 35 ° C ・ Calibration curve; Sodium polyacrylate Standard sample (manufactured by Soka Kagaku) <Calcium ion capturing ability> First, a calcium ion standard aqueous solution (aqueous solution for calibration curve) was prepared as follows. That is, calcium chloride-2
Using a hydrate, 0.01 mol / l of Ca ²⁺ ion,
50 cc of each of 0.001 mol / l and 0.0001 mol / l aqueous solutions were adjusted, the pH was adjusted to 9 to 11 with 4.8% sodium hydroxide aqueous solution, and 1 ml of 4 mol / l potassium chloride aqueous solution was added.

Next, an aqueous solution of the measurement sample was prepared. That is, 10 mg of polymer (adjusted to pH 7) in terms of solid content was weighed in a 100 cc beaker, and 50 cc of 0.001 mol / l calcium ion aqueous solution adjusted using sodium chloride dihydrate was added, and the mixture was stirred with a stirrer. After uniformly stirring, the pH was adjusted to 9 to 11 with a 4.8% sodium hydroxide aqueous solution, and 1 ml of a 4 mol / l potassium chloride aqueous solution was added.

The measurement was performed using an ion analyzer EA920 manufactured by Orion Co., Ltd. and a calcium ion electrode 93-20 manufactured by Orion Co., Ltd. From the calibration curve and the measured value of the sample (polymer), the amount of calcium ions trapped by the sample was obtained, and the amount trapped per 1 g of polymer solids was expressed in mg of calcium carbonate, and the value was calculated as the calcium ion trapping capacity value. And

<Clay Dispersion Ability in High-Hardness Water> First, 67.56 g of glycine and 52.
Ion-exchanged water was added to 6 g of 60 ml of 1N-NaOH to prepare a glycine buffer solution of 600 g. Take out 60 g of the adjusted solution of 0.3268 g of calcium chloride dihydrate and add ion-exchanged water to 1000 g.
Then, the dispersion liquid was prepared.

Next, a 0.1% aqueous solution of the polymer (adjusted to pH 7) in terms of solid content was prepared. JIS test powder I, 8 types (Kanto ROHM,
Fine particles: 0.3 g of clay from Japan Powder Industrial Technology Association) was added, and 27 g of the adjustment liquid of and 3 g of the adjustment liquid of were added. At this time, the calcium concentration of the test liquid is 200 ppm in terms of calcium carbonate.

After the test tube was sealed with parafilm, it was shaken lightly so that the clay was dispersed throughout, and further shaken up and down 20 times. This test tube is allowed to stand for 20 hours in a place where it is not exposed to direct sunlight, and then the supernatant of the dispersion liquid is 5m with a whole pipette.
1 was collected. Using a UV spectrophotometer, this solution is 380 nm in wavelength, 1c
The transmittance (T%) was measured in a cell of m. The value obtained by subtracting the value of T% from 100 was defined as the clay dispersibility (turbidity). <Clay Dispersing Ability in Low Hardness Water> In the above method for measuring clay dispersing ability in high hardness water, calcium chloride-2
The clay dispersibility in low hardness water was determined in exactly the same manner as the clay dispersibility in high hardness water except that the amount of hydrate added was 0.0817 g (50 ppm in terms of calcium carbonate). Example 1 A SUS separable flask with a capacity of 5 liters equipped with a reflux condenser and a stirrer was charged with 150 ion-exchanged water.
g, and 98 g of maleic anhydride were charged, and 83.3 g of a 48% sodium hydroxide aqueous solution was further added. Then, the temperature was raised to the boiling point with stirring, and 810 g of 80% acrylic acid aqueous solution and 26% of 15% sodium persulfate aqueous solution were added.
6.7 g, 22% of 35% sodium bisulfite aqueous solution
8.6 g and 46.8 g of ion-exchanged water were dropped from separate dropping nozzles for 80 minutes of 80% acrylic acid and for 190 minutes of others.

After completion of the dropping, the reaction solution was kept at the boiling point reflux state for an additional 20 minutes to complete the polymerization. After the completion of the polymerization, the reaction solution was allowed to cool, and 750 g of a 48% sodium hydroxide aqueous solution was gradually added to neutralize it. Thus, an acrylic acid-maleic acid copolymer having a solid content concentration of 48% and a final neutralization degree of 91% was obtained. The physical properties of the obtained polymer were measured and the results are summarized in Table 4. (Examples 2 to 8) The same procedure as in Example 1 was carried out except that the initial charging amount, the dropping amount, and the post-neutralizing amount as shown in Table 1 were used. The results of measuring the physical properties of the obtained polymer are summarized in Table 4. (Example 9) As in Example 1, using a 5 liter separable SUS separable flask equipped with a reflux condenser and a stirrer, pure water 495 g, maleic anhydride 98 g, and ferrous ammonium sulfate 0.5 g were used. Then, 41.7 g of a 48% aqueous sodium hydroxide solution was added. After that, the temperature was raised to the boiling point under stirring, and 810 g of 80% acrylic acid aqueous solution and 285 g of 35% hydrogen peroxide aqueous solution were added.
80% acrylic acid was added to 18 g from 7 g separately.
At 0 minutes, 35% hydrogen peroxide was added dropwise over 120 minutes.

After completion of the dropping, the reaction solution was kept at the boiling point reflux state for an additional 20 minutes to complete the polymerization. Thus, an acrylic acid-maleic acid copolymer having a solid content concentration of 42% and a final degree of neutralization of 5% was obtained. After adjusting the pH of the obtained polymer to 7, each physical property was measured and the results are shown in Table 4.
Summarized in. (Examples 10 to 16) The same procedure as in Example 9 was carried out except that the initial charging amount, the dropping amount, and the dropping time as shown in Table 2 were used. The results of measuring the physical properties of the obtained polymer are summarized in Table 4. (Comparative Example 1) As in Example 1, using a 5 liter separable SUS separable flask equipped with a reflux condenser and a stirrer, 630 g of ion-exchanged water was charged and the temperature was kept constant at 25 ° C under stirring. . 1430 g of 35% aqueous sodium acrylate solution and 276.5 g of 20% aqueous sodium hydrogen sulfite solution were separately added while blowing 51 liters of air converted into the standard state into 1 mol of sodium sulfite. 24 from nozzle
Dropwise over 0 minutes. During the polymerization reaction, the temperature is 22 to 2
The temperature was maintained at 7 ° C., and air was continuously supplied for 30 minutes after the completion of dropping while maintaining the temperature to complete the polymerization to obtain a fully neutralized polyacrylic acid polymer having a solid content concentration of 25%.
Each physical property was measured and the results are summarized in Table 4. (Comparative Example 2) As in Example 1, using a 5 liter capacity separable flask made of SUS equipped with a reflux condenser and a stirrer, 700 g of pure water was charged, and the temperature was raised to the boiling point under stirring. Then, 2032 g of 37% sodium acrylate aqueous solution and 10% of 15% sodium persulfate aqueous solution were added.
6.7 g and 1000 g of ion-exchanged water are separately added into a dropping nozzle to make a 37% sodium acrylate aqueous solution 180
Minutes, others were dropped over 190 minutes.

After the dropping was completed, the reaction solution was kept at the boiling point reflux state for an additional 20 minutes to complete the polymerization. After the completion of the polymerization, the reaction solution was allowed to cool and neutralized by gradually adding 658.3 g of a 48% sodium hydroxide aqueous solution to obtain an acrylic acid-maleic acid copolymer with a solid content concentration of 35% and a final neutralization degree of 90%. Got united. The physical property measurement results are summarized in Table 4. (Comparative Examples 3 to 6) Comparative Example 2 is the same as Comparative Example 2 except for the charging amount, the dropping amount, and the dropping time as shown in Table 3.
Polymers were obtained respectively. The results are summarized in Table 4. (Comparative Examples 7 to 14) Examples 1-1, 1-4, 1-6, 1-12, 1-13, 1- of Japanese Patent No. 2574144.
A copolymer was obtained according to 16, 1-20, 1-22. The results of physical property measurement and evaluation are summarized in Table 4.

[0044]

[Table 1]

[0045]

[Table 2]

[0046]

[Table 3]

[0047]

[Table 4]

As shown in Tables 1 to 4, all the copolymers of the examples obtained by the production method of the present invention have a clay dispersibility in high hardness water of 50% or more, and calcium ion trapping. It has a very good ability of 270 mg CaCO ₃ / g or more. Examples 1 to 8 are combinations of sodium persulfate and sodium bisulfite as polymerization initiators, and Examples 9 to 16 are combinations of hydrogen peroxide and iron ions (Fe ²⁺ ) as polymerization initiators. is there.

In Comparative Examples 1 and 2, maleic acid (salt) was not copolymerized, and a specific compound was not used in combination as a polymerization initiator. Very low ion trapping ability. In Comparative Examples 3 to 6, since the specific compound was not used in combination as the polymerization initiator, the product (MA × Mw) exceeded 150,000, and the calcium ion trapping ability was high, but the clay in high hardness water was It is inferior in dispersibility. Comparative Examples 3, 4,
The polymerization concentration increases in the order of 5 and 6, and the product (MA × Mw) also increases accordingly, and at the same time, the clay dispersibility in high hardness water decreases.

In Comparative Examples 7 to 14, since the proportion of maleic acid (salt) is high and a specific compound is not used in combination as a polymerization initiator, calcium ion trapping ability is high, but clay in high hardness water is used. Low dispersibility. In addition, when the polymers of Examples and Comparative Examples are compared in clay dispersibility in low hardness water, no difference is observed, but a remarkable difference is observed in clay dispersibility in high hardness water.

[0051]

According to the present invention, it is possible to provide an acrylic acid (salt) -maleic acid (salt) copolymer having a high clay dispersibility in high hardness water and a high calcium ion trapping ability. Therefore, the detergent composition using the same exhibits excellent cleaning ability even in a region of extremely high hardness water such as the United States and China.

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Claims (6)

(57) [Claims] 1. The clay dispersibility in high hardness water is 50% or more, and the calcium ion trapping ability is 270 mgCaCO.
_An acrylic acid (salt) -maleic acid (salt) copolymer having a ratio of ₃ / g or more. 2. The copolymer has a molar ratio of acrylic acid (salt) units to maleic acid (salt) units of 95 to 80.
The product of the ratio (MA (mol%)) of maleic acid (salt) units in the copolymer and the weight average molecular weight (Mw) of the copolymer (MA × Mw). Is 15
The acrylic acid (salt) -maleic acid (salt) copolymer according to claim 1, which has a Mw of 20,000 or less and a Mw of 20,000 or less. 3. Acrylic acid (salt) -malein by polymerizing a monomer component containing acrylic acid (salt) and maleic acid (salt) as main components in an aqueous solvent in the presence of at least a polymerization initiator. a method for producing an acid (salt) copolymer, is calculated from the weight of the raw materials fed to the reactor, the solid content concentration of the theoretical polymer after completion of polymerization is 40 wt% or more
The amount of acrylic acid (salt) and the amount of maleic acid (salt) used are in the range of 95 to 80/5 to 20 in terms of molar ratio, and (1) persulfate and bisulfite are used as polymerization initiators. Acrylic acid (salt) -maleic acid (salt), characterized in that it is used in combination with a salt and / or (2) hydrogen peroxide is used in combination with a polyvalent metal ion.
Of producing a base copolymer. 4. A persulfate and a bisulfite are used together as a polymerization initiator, and the amount of the persulfate and the amount of the bisulfite used are in the range of 1 / 0.5 to 1/5 in weight ratio. The method for producing an acrylic acid (salt) -maleic acid (salt) copolymer according to claim 3, wherein 5. Hydrogen peroxide and a polyvalent metal ion are used together as a polymerization initiator, and the amount of hydrogen peroxide used is that of the monomer component 1.
It is in the range of 5 to 15 g per mol, and the amount of polyvalent metal ion used is 5 to 500 p with respect to the total amount of the reaction liquid used.
The acrylic acid (salt) according to claim 3, which has a pm range.
Method for producing maleic acid (salt) copolymer. 6. A detergent composition comprising the acrylic acid (salt) -maleic acid (salt) copolymer according to claim 1 or 2 and a surfactant.