JP2692201B2 - Dispersion stabilizer for inorganic powder in water - Google Patents

Description

TECHNICAL FIELD The present invention relates to a dispersion stabilizer for various inorganic powders such as calcium carbonate and titanium oxide in water, and more specifically, to an aqueous dispersion stabilizer for dispersing inorganic powders in high concentration and stably. Dispersion stabilizer.

[Conventional technology]

Inorganic powder dispersions in water, that is, water slurries are used in various industrial fields, and are used in large amounts as white pigments for paper, leather, and the like. The most representative of these is calcium carbonate fine powder, which is used in many industrial fields as an inexpensive white pigment regardless of whether it is heavy or light, and in particular, it is a white slurry for paper in the form of water slurry. It is often used as a pigment.

In such a field, conventionally, a method of carrying the inorganic powder to the place of use in the form of a powder and dispersing it in water and using it was taken, but various troubles caused by carrying the powder, For example, when the dust problem and the need for new equipment for mixing on the user side are added to the economic problems, the manufacturer side prepares water slurry in advance, and when the slurry is conveyed to the user side, it becomes more difficult. The demand is growing. In this case, a high-concentration and low-viscosity water slurry is required to reduce the transportation cost, and a water slurry that does not cause hard sedimentation during transportation is required.

Further, such a water slurry having a high concentration and a low viscosity and excellent in sedimentation stability is not limited to the above-mentioned transportation aspect,
It is also strongly desired in terms of its use. That is,
For example, when applying a water slurry such as the above-mentioned calcium carbonate fine powder as a white pigment to paper or the like, in order to increase the efficiency in the drying step after the application, a water slurry having as little water content as possible, that is, a high-concentration low-viscosity water slurry is required. In addition, from the viewpoint of facilitating the above-mentioned coating and the characteristics of the coating film, the water slurry of high concentration and low viscosity is required to have excellent sedimentation stability.

Conventionally, in order to meet such demands, a dispersion stabilizer for stably dispersing an inorganic powder in water has been used, and as the dispersion stabilizer, many surfactants such as polyacrylic acid and copolymerization thereof have been used to date. A salt of a product, a salt of a copolymer of maleic anhydride and α-olefin, and the like have been proposed.

[Problems to be solved by the invention]

However, with the conventional dispersion stabilizers as described above, it is not possible to obtain a water slurry of an inorganic powder having a high concentration and a low viscosity capable of being advantageously applied to various fields and having an excellent sedimentation stability, particularly a fine powder of calcium carbonate. It was difficult.

Therefore, the present invention provides an industrially valuable dispersion stabilizer for water, which can disperse various inorganic powders including calcium carbonate fine powder in water with high concentration and low viscosity and for a long period of time. With the goal.

[Means for solving the problem]

As a result of intensive studies to achieve the above-mentioned object, the inventors have found that a copolymer of a special polyoxyalkylene derivative and maleic acid represented by maleic anhydride,
As a dispersion stabilizer in water of various inorganic powders such as calcium carbonate fine powder, it has been found that it exhibits significantly superior performance as compared with the above-mentioned conventional ones, and the above-mentioned object can be sufficiently achieved. It came to completion.

That is, the present invention provides a copolymer of (i) a polyoxyalkylene derivative represented by the following general formula [I] and (ii) one or more maleic acids selected from maleic anhydride, maleic acid and maleic acid salts. It is a dispersion stabilizer of an inorganic powder in water.

(However, Z is a residue of a compound having two hydroxyl groups, AO is an oxyalkylene group having 2 to 18 carbon atoms, and X is 3 to 5 carbon atoms.
Is an unsaturated hydrocarbon group, R is a hydrocarbon group having 1 to 40 carbon atoms, a = 0 to 1000, b = 0 to 1000, and a + b = 1 to 1000. That is, the dispersion stabilizer of the present invention is a copolymer of the polyoxyalkylene derivative represented by the general formula [I] and a maleic acid selected from maleic anhydride, maleic acid and salts thereof. The alkylene derivative unit and the maleic acid unit may each be a single type or a mixture of two or more types.

The use ratio of the polyoxyalkylene derivative unit and the maleic acid unit is not particularly limited, but an equivalent ratio based on the polymerizable double bond of 7: 3 to 3: 7, particularly about 1: 1 is preferable. The average molecular weight of the copolymer is not limited, but it is preferably 1,000 to 2,000,000 in weight average molecular weight,
Particularly, 3,000 to 300,000 is preferable.

In the general formula [I], examples of the compound having two hydroxyl groups having Z as a residue include ethylene glycol, propylene glycol, butylene glycol, dodecylene glycol, octadecylene glycol, neopentyl glycol and styrene glycol. Dihydric alcohols; dihydric phenols such as catechol, resorcin, and hydroquinone.

Examples of the oxyalkylene group having 2 to 18 carbon atoms represented by AO include oxyethylene group, oxypropylene group, oxybutylene group, oxytetramethylene group, oxystyrene group, oxidedecylene group, oxytetradecylene group, oxyhexa There are decylene group, oxyoctadecylene group, etc., and one kind alone or a mixed adduct of two or more kinds may be used.
When there are two or more kinds, they may be random adducts or block adducts.

Examples of the unsaturated hydrocarbon group having 3 to 5 carbon atoms represented by X include a polymerizable unsaturated bond such as an allyl group, a methallyl group, a 3-butenyl group, a 4-pentenyl group, and a 3-methyl-3-butenyl group. Some have.

The hydrocarbon group represented by R has 1 to 40 carbon atoms, and particularly preferably a hydrocarbon group having 1 to 24 carbon atoms, such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, Tributyl group, amyl group, isoamyl group, hexyl group, heptyl group, 2-ethylhexyl group, octyl group, nonyl group, decyl group, undecyl group,
Dodecyl group, isotridecyl group, tetradecyl group, hexadecyl group, isohexadecyl group, octadecyl group, isooctadecyl group, oleyl group, octyldodecyl group,
Docosyl group, decyltetradecyl group, benzyl group, cresyl group, butylphenyl group, dibutylphenyl group, octylphenyl group, nonylphenyl group, dodecylphenyl group, dioctylphenyl group, dinonylphenyl group, styrenated phenyl group, naphthyl group and so on.

The reason why a + b is limited to 1000 or less is that it is difficult to manufacture a material that exceeds this value.

The carbon number of AO can be arbitrarily selected within the range of 2 to 18, but the ratio of hydrophilic group to lipophilic group can be adjusted by combining with R.

On the other hand, among the maleic acids forming a copolymer with the polyoxyalkylene derivative of the general formula [I], the salts of maleic acid include ammonia; methylamine, ethylamine, propylamine, butylamine, hexylamine,
Octylamine, 2-ethylhexylamine, nonylamine, decylamine, dodecylamine, isotridecylamine, tetradecylamine, hexadecylamine, isohexadecylamine, stearylamine, isostearylamine, oleylamine, linolamine, octyldodecylamine, docosylamine Monoamines such as decyltetradecylamine and aniline; polyamines such as ethylenediamine, tetramethylenediamine, dodecylpropylenediamine, octadecylpropylenediamine, oleylpropylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine; monoethanolamine ,
Alkanolamines such as diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, alkylene oxide adducts of the above monoamines and diamines; amino acids such as lysine, arginine, histidine; alkali metals such as lithium, sodium, potassium, etc. There are salts of alkaline earth metals such as magnesium and calcium, and the type and degree of neutralization can be selected according to the types of AO, X and R so that the copolymer will dissolve or disperse in water. .. Preferably, lower amines such as ammonia, methylamine and alkanolamine, and alkali metals are used.

The polymer can be easily obtained by copolymerizing the polyoxyalkylene derivative represented by the general formula [I] with maleic anhydride, maleic acid or maleate using a radical catalyst such as peroxide. When the maleic acid unit is maleic acid or a salt thereof, the polyoxyalkylene derivative of the general formula [I] and maleic anhydride are copolymerized using a radical catalyst and then hydrolyzed, and further this is converted into a salt. The conversion is preferable because a polymer having a high molecular weight can be obtained.

Further, at the time of copolymerization, copolymerizable components such as styrene, α-olefin and vinyl acetate may be mixed and copolymerized.

The copolymer thus obtained has Z, AO, X, R, a,
By appropriately changing the b and maleic acid units, a copolymer having a wide range of properties can be obtained.
In many cases, a copolymer that is soluble in water to some extent can give a preferable result as a dispersion stabilizer, as compared with a copolymer that is freely soluble in water or a copolymer that is not soluble in water at all.

The inorganic powder to be dispersed in the present invention is not particularly limited, but kaolin, aluminum silicate, clay, talc, mica, asbestos powder, calcium silicate, sericite, bentonite and other silicates, calcium carbonate, magnesium carbonate. , Carbonate such as barium carbonate, dolomite, calcium sulfate, sulfate such as barium sulfate, magnesia, alumina, antimony oxide, titanium oxide, white carbon, diatomaceous earth, metal oxide such as iron oxide, aluminum hydroxide, hydroxide Metal hydroxides such as magnesium, iron hydroxide, metatitanic acid, etc.
Silicon carbide, silicon nitride, boron nitride, zirconia, barium titanate, satin white, carbon black,
There are graphite etc.

The average particle size of these inorganic powders varies greatly depending on the type, but is generally 100 μm or less, usually 0.1-
It is about 50 μm.

The amount of the dispersion stabilizer used when preparing the aqueous slurry of the inorganic powder using the dispersion stabilizer of the present invention is the inorganic powder.
0.01 to 10 parts by weight, more preferably 0.05 to 100 parts by weight
It is preferable to use up to 5 parts by weight. If the amount is less than 0.01 part by weight, the effect is insufficient, and if the amount exceeds 10 parts by weight, the effect is not increased and it is economically disadvantageous.

The method for preparing the water slurry of the inorganic powder is arbitrary, but generally, a predetermined amount of the dispersion stabilizer of the present invention is dissolved in water, and the method of adding the inorganic powder under stirring or the inorganic powder in water. For example, after preparing light calcium carbonate and various inorganic salts, a dehydration cake is added with a dispersion stabilizer to form a slurry, which is a preferable method.

In addition, in the above-mentioned preparation, together with the dispersion stabilizer of the present invention, other aqueous dispersants, for example, anionic, nonionic surfactant salts of olefin-maleic acid copolymers, (meth) acrylic acid polymerization You may make it use together the thing salt, the salt of a naphthalene sulfonic acid formaldehyde condensate, condensed phosphate, polyoxyethylene oleyl ether, polyoxyethylene sorbitan monooleate, etc. This combined use may sometimes provide even better results in the dispersibility of the fine powder, the dispersion stability, and the redispersibility of the precipitate.

〔The invention's effect〕

As described above, the inorganic powder aqueous dispersion stabilizer of the present invention is not only excellent in dispersibility and dispersion stability of the inorganic powder by using the salt of the copolymer as an active ingredient, but also after long-term storage. Even if it sediments, the sediment is soft and enables the preparation of an aqueous dispersion having good redispersibility.

〔Example〕

Hereinafter, embodiments of the present invention will be described in more detail. The dispersion stability and redispersibility of the aqueous dispersions prepared in the following Examples and Comparative Examples were measured and evaluated by the following methods.

<Dispersion stability> After preparation of the dispersion in water, immediately put it in a 50 ml graduated emulsification test tube, leave it in a constant temperature room at 25 ° C, observe the dispersion state after 24 hours, and evaluate as follows. .

⊚: The powder is not settled at all.

◯: The powder is slightly settled.

Δ: The powder is considerably settled.

X: The powder is completely settled.

<Redispersibility> Immediately after preparing the dispersion in water, put it in a 50 ml graduated emulsification test tube, leave it in a thermostatic chamber at 25 ° C, and examine the hardness and redispersibility of the sediment 30 days later. It was evaluated as follows.

A: Well dispersed.

○: Disperse when water is stirred.

Δ: Soft and easily disintegrated by poking with a spatula.

X: It is hard and does not easily collapse even if it is poked with a spatula.

In addition, in the following Examples, the compounds shown in Tables A to K were used as the dispersion stabilizer in water of the present invention, but as long as it is defined in the claims, only the Examples are used. It goes without saying that it is not limited.

Example 1. Titanium oxide having an average particle size of 0.3 μm was used as the inorganic powder, and the dispersion stabilizer of the present invention shown in Table 1 and the conventionally known dispersion stabilizer as a dispersion stabilizer were used as the dispersion stabilizer. Of 1.2% by weight and inorganic powder of 45% by weight are mixed with a predetermined amount of water, a dispersion stabilizer and an inorganic powder, and the mixture is put into a sand mill [Igarashi Kikai Seisakusho Co., Ltd.] and ground for 3 hours. The water dispersion according to the present invention was prepared by mixing. Table 2 shows the dispersion stability and redispersibility of these aqueous dispersions.

Example 2 Light calcium carbonate having an average particle diameter of 0.1 μm was used as the inorganic powder, and the dispersion stabilizers shown in Table 1 of the present invention and the comparative dispersion stabilizers were used as the dispersion stabilizers. The concentration shown in the table, a predetermined amount of water so that the inorganic powder has a concentration of 60% by weight, the dispersion stabilizer and the inorganic powder are mixed, 2,000 rpm using a homogenizer, by mixing for 10 minutes, the Inventive and comparative dispersions were prepared. The dispersion stability and redispersibility of the resulting dispersion in water are shown in Table 3.

Example 3. Magnesium hydroxide powder having an average particle diameter of 0.2 μm was used as the inorganic powder, and the dispersion stabilizer described in Table 1 of the present invention and the comparative dispersion stabilizer were used as the dispersion stabilizer. 4. Mix the specified amount of water, dispersion stabilizer and inorganic powder so that the concentration of the inorganic powder is 45% by weight as shown in Table 4, and use a homogenizer to mix this with 2,000 rpm, 15
The inventive and comparative aqueous dispersions were prepared by mixing for minutes. The dispersion stability and redispersibility are shown in Table 4.

Example 4. Carbon black having an average particle size of 0.05 μm was used as the inorganic powder, and the dispersion stabilizers shown in Table 1 of the present invention and the comparative dispersion stabilizers were used as the dispersion stabilizers. In accordance with the present invention, by mixing a predetermined amount of water, the dispersion stabilizer and the inorganic powder so that the concentration of the inorganic powder is 40% by weight, and mixing the resulting mixture with a homogenizer at 2,000 rpm for 15 minutes. And a comparative aqueous dispersion was prepared. The dispersion stability and redispersibility are shown in Table 5.

As seen in the above examples, it is understood that the dispersion stabilizer of the present invention exhibits excellent performance as a dispersion stabilizer for various inorganic powders in water.

Claims (1)

(57) [Claims] 1. A copolymer of (i) a polyoxyalkylene derivative represented by the general formula [I] and (ii) one or more maleic acids selected from maleic anhydride, maleic acid and maleic acid salts. Dispersion stabilizer for inorganic powders in water. (However, Z is a residue of a compound having two hydroxyl groups, AO is an oxyalkylene group having 2 to 18 carbon atoms, and X is 3 to 5 carbon atoms.
Is an unsaturated hydrocarbon group, R is a hydrocarbon group having 1 to 40 carbon atoms, a = 0 to 1000, b = 0 to 1000, and a + b = 1 to 1000. )