JP2828262B2 - Calcium carbonate dispersion - Google Patents

Description

The present invention relates to a calcium carbonate dispersion. More specifically, the present invention relates to a dispersion obtained by dispersing calcium carbonate at a high concentration in an organic liquid mainly composed of liquid hydrocarbon, and particularly useful as a fuel oil additive.

(B) Conventional technology A calcium carbonate dispersion using a hydrocarbon-based dispersion medium exhibits actions such as corrosion prevention, fuel ash deposition and adhesion prevention, combustion promotion, and smoke suppression. Commonly used.

In particular, the over-based calcium sulfonate-based additive contains ultra-fine (sub-micron grade) colloidal calcium carbonate of oil-soluble petroleum sulfonate, is added to the lubricating oil, and is added to the fuel. It is used to neutralize corrosive acidic substances produced by partial combustion. Such additives basically comprise a sufficient amount of carbon dioxide added to the product of the reaction of an oil-soluble sulfonic acid with calcium oxide or calcium hydroxide (in excess of its neutralization equivalent) in an oily medium or alcohol. It is produced by reacting carbon.

By the way, among non-aqueous dispersions containing calcium carbonate, those having a high calcium content have remarkably high viscosity and are inconvenient to handle. Particularly, in recent years, with the advance of the atomization technology, ultra-fine (sub-micron class) calcium carbonate powder has been obtained, and a dispersion containing such fine particles in a high concentration has been obtained. The liquid exhibits a higher viscosity, making handling during transport difficult.

British Patent 1,342,746 describes the formula HO-X-COOH, where X is at least 8 carbon atoms,
Represents a divalent saturated or unsaturated aliphatic group having at least 4 carbon atoms interposed between the hydroxy group and the carboxylic acid group. ), A polyester derived from a mixture of the hydroxycarboxylic acid and an aliphatic carboxylic acid having no hydroxy group, or a salt thereof (hereinafter, referred to as a salt thereof). This polyester and a salt thereof are referred to as a polyester dispersant). Disclosed are organic liquid dispersions of pigments having improved fluidity and particle dispersion stability.

(C) Problems to be Solved by the Invention However, when the above-mentioned polyester-based dispersant is applied to the dispersion of the calcium carbonate, the ultrafine calcium carbonate is dispersed in the liquid hydrocarbon at a high concentration (for example, 20% by weight or more). Then, when the dispersion is prepared, the calcium carbonate fine particles are settled without separating from the hydrocarbon to form a gel during the standing of the dispersion, and the gel grows with time. There was a problem. In addition, the gel-like material does not redisperse even if the container containing the dispersion is shaken, and thus cannot be used practically.

The present inventors have conducted intensive studies to solve these problems, and as a result, added an appropriate amount of an aliphatic ketone and / or carboxylic acid ester having 4 to 10 carbon atoms in the molecule to the above dispersion. As a result, they have found that the formation of the gel-like substance can be efficiently prevented or suppressed, and have reached the present invention.

(D) Means for Solving the Problems Thus, according to the present invention, fine particulate calcium carbonate is
(A) A general formula HO-X-COOH as a dispersant (where X is a carbon atom having at least 8 carbon atoms including a side chain and not including a side chain between a hydroxy group and a carboxylic acid group) An aliphatic hydroxycarboxylic acid represented by a divalent saturated or unsaturated aliphatic group having at least 4 atoms),
Or a polyester derived from a mixture of the hydroxycarboxylic acid and the aliphatic carboxylic acid, and / or a salt thereof, and (b) the polyester or a salt thereof,
Dispersed in an organic liquid mainly composed of a liquid hydrocarbon containing up to 4 times (weight ratio) an aliphatic ketone and / or carboxylic acid ester having 4 to 10 carbon atoms in the molecule. A calcium carbonate dispersion is provided.

The particulate calcium carbonate used in the present invention means one having a specific surface area of 2.0 m ² / g or more measured by an air permeation method. This usually corresponds to an average particle size of about 1 micron or less. The specific surface area by air permeation method is 2.0m
^A particle size smaller than ² / g is not preferred because the particles are too coarse and the effects of dispersion stability, corrosion prevention, deposition prevention of fuel ash, promotion of combustion, suppression of medium smoke, etc. are reduced. In particular, it is preferable that the specific surface area is large because the dispersion stability and the various effects are improved. As the finely divided calcium carbonate, those having the above specific surface area of about 8 m ² / g are also known, and such fine particles are also preferably used in the present invention. The finely divided calcium carbonate used in the present invention may be surface-treated with a surface-treating agent or may be one in which other components are coprecipitated.

In the dispersion of the present invention, the general formula HO-X-COOH (however,
X is a divalent saturated or unsaturated aliphatic group having at least 8 carbon atoms including a side chain and at least 4 carbon atoms not including a side chain between a hydroxy group and a carboxylic acid group. A) a polyester derived from an aliphatic hydroxycarboxylic acid represented by the formula: or a mixture of the hydroxycarboxylic acid and an aliphatic carboxylic acid having no hydroxy group, and / or a salt thereof (polyester dispersant) ) [Component (a)].

The aliphatic hydroxycarboxylic acid used as a raw material of the polyester is represented by the above general formula.
Those in which X has 12 to 20 carbon atoms are preferred. X preferably has 8 to 14 carbon atoms between the hydroxy group and the carboxylic acid group. Preferred hydroxycarboxylic acids include ricinoleic acid, 9- and 10-hydroxystearic acid (sulfate of oleic acid,
Hydrolyzed product), 12-hydroxystearic acid and the like. Fatty acids from hydrogenated castor oil also contain a small amount of stearic acid, palmitic acid, etc., but can be used as a raw material of the polyester because the main component is hydroxycarboxylic acid.

As the "aliphatic carboxylic acid having no hydroxy group", a saturated or unsaturated aliphatic carboxylic acid is preferable, and an alkanecarboxylic acid or alkenecarboxylic acid having 8 to 20 carbon atoms is particularly preferable. Preferred examples of the "aliphatic carboxylic acid having no hydroxy group" include lauric acid, palmitic acid, stearic acid, and oleic acid.

In order to produce the polyester, for example, the hydroxycarboxylic acid, or the hydroxycarboxylic acid and a carboxylic acid having no hydroxy group, optionally with an esterification catalyst, preferably at a temperature of 160 to 200 ° C. ,
What is necessary is just to heat and dehydrate until the required molecular weight is reached. The progress of esterification can be known by measuring the acid value of the product. Preferred polyesters are in the range of 10-100 mg KOH / gram, especially 20-50 mg
It has an acid number in the range of KOH / gram. The obtained polyester has a carboxylic acid group in at least one position of the molecular terminal.

The polyester salt can be used in the present invention similarly to the polyester, and both of them may be used in combination. The polyester salt may be a salt with a metal such as potassium or sodium, or a salt with ammonia or an organic base.

The polyester and / or its salt, that is, the polyester dispersant is preferably added at a ratio of 5 to 50% by weight based on the calcium carbonate contained in the dispersion.

In the present invention, an aliphatic ketone having 4 to 10 carbon atoms in the molecule and / or
Or a carboxylic acid ester ”[component (b)]. By using such a compound, it is possible to suppress the formation of a gel-like substance due to the sedimentation of calcium carbonate in the dispersion over time. Even ketones or carboxylate esters, compounds having 3 or less carbon atoms in the molecule, or 11 or more carbon atoms, have too little power to suppress the formation of gel-like substances, or may suppress the formation of gel-like substances. It is not preferable to add as much as possible because phase separation may occur in the dispersion.

As aliphatic ketones preferably used, methyl ethyl ketone, methyl propyl ketone, diethyl ketone, methyl butyl ketone, methyl propyl ketone, methyl amyl ketone, ethyl butyl ketone, dipropyl ketone, methyl hexyl ketone, ethyl amyl ketone, propyl butyl ketone, ethyl hexyl Ketone, propyl amyl ketone, dibutyl ketone and the like are exemplified.

As the aliphatic carboxylic acid ester preferably used, butyl formate, amyl formate, ethyl acetate, propyl acetate, butyl acetate, amyl acetate, hexyl acetate, octyl acetate, methyl propionate, ethyl propionate,
Propyl propionate, butyl propionate, amyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate,
Examples thereof include carboxylate esters such as butyl butyrate, amyl butyrate, hexyl butyrate, methyl isobutyrate, ethyl isobutyrate, propyl isobutyrate, ethyl caproate, ethylene (glycol) diacetate, diethyl oxalate, and diethyl succinate. Unsaturated esters can also be used, but saturated esters are preferred in order not to cause a phase change during storage.

The ketone and / or carboxylic acid ester may be used alone or in combination of two or more. May be used in combination. The ketone and / or carboxylic acid ester is particularly preferably selected from compounds having 5 to 9 carbon atoms in the molecule.

The ketone and / or carboxylic acid ester is used in an amount of 1 to 4 times (by weight) the total amount of the ketone and the ester relative to the polyester-based dispersant. If the ratio of the ketone and / or carboxylic acid ester to the polyester-based dispersant is less than 1: 1, it is not preferable because the formation of a gel cannot be sufficiently suppressed. On the other hand, if this ratio exceeds 4 times, the improving effect reaches a plateau, and the extra ketone and / or carboxylic acid ester function as a mere dispersing medium, which only increases the cost, which is not preferable. This addition ratio (weight ratio)
In consideration of the cost and the like, it is preferably 3.5 times or less, particularly preferably 3 times or less.

The dispersion of the present invention can be obtained by dispersing and containing calcium carbonate in a dispersant-containing organic liquid obtained by mixing the above components (a) and (b) with a liquid hydrocarbon serving as a base dispersion medium.

Here, in such a dispersion, an organic liquid mainly composed of a liquid hydrocarbon acts as a dispersion medium, and the ketone and / or carboxylate is also included in the organic liquid. In the present invention, "mainly composed of a liquid hydrocarbon" means that the ratio of the liquid hydrocarbon exceeds 50% by weight in the organic liquid obtained by summing them. Examples of preferably used liquid hydrocarbons include hexane, cyclohexane, benzene, toluene, xylene and the like, naphtha, gasoline, kerosene, light oil, heavy oil, liquid paraffin, aromatic hydrocarbon mixture and the like. However, in the organic liquid, other than liquid hydrocarbons, ketones and / or carboxylic esters, other liquid organic substances that do not impair the effects of the present invention, such as alcohols, ethers, animal and vegetable oils,
Etc. may be contained. The polyester-based dispersant has an action of binding to calcium carbonate particles,
Since it is not a mere dispersion medium, it is not included in the organic liquid mentioned here. Here, the ratio of the liquid hydrocarbon in the organic liquid is preferably 60% by weight or more.

The dispersion of the present invention preferably has a calcium carbonate content of 20% by weight or more of the whole dispersion, and more preferably 30% by weight or more. If the content of calcium carbonate is less than 20% by weight, the effect of the present invention is insufficient, which is not preferable.

To prepare the dispersion of the present invention, any conventionally known method can be adopted. Therefore, for example, finely divided calcium carbonate, a polyester-based dispersant, an organic liquid containing the ketone and / or carboxylic acid ester (having a hydrocarbon as a main component) and the like are mixed in an arbitrary order, and the calcium carbonate is formed into fine particles. Dispersion can be performed by a treatment for dispersing, for example, ball milling, beet milling, Gravel milling, or the like, or a disperser treatment, a homogenizer treatment, or the like.

In addition, a bactericide, a fungicide, a thickener, another dispersant, other additives, and the like may be added to the dispersion of the present invention as needed.

(E) Examples Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention should not be construed as being limited by these Examples in any sense.

<< Production of dispersant >> Production of dispersant A 348 parts by weight of xylene and 12-hydroxystearic acid (having an acid value of 182 mg / KOH / g and a hydroxyl value of 160 mg / KOH / g) 3350
Stirring the mixture by weight at a temperature of 190-200 ° C. for 22 hours,
The water generated during that time was distilled together with xylene, and xylene separated from water from the distillate was refluxed in the reaction medium.
After 152 parts by weight of water had collected as distillate, xylene was distilled off by heating to 200 ° C. while flowing a nitrogen stream through the reactor. As a result, an amber-colored liquid polyester (dispersant A) was obtained. The acid value of this polyester was 33.0 mgKOH / g.

Production of Dispersant B A mixture of 96 parts by weight of xylene, 150 parts by weight of oleic acid, and 850 parts by weight of ricinoleic acid was added at a temperature of 190 to 200 ° C. for 2 hours.
The mixture was stirred for 2 hours, during which time the generated water was distilled off. The xylene was then distilled off at 150 ° C. under reduced pressure. The acid value of the obtained polyester (dispersant B) was 36.6 mgKOH / g.

Example 1 40.0 parts by weight of finely divided calcium carbonate (having a specific surface area measured by an air permeation method of 5.8 m ² / g and surface-treated with a fatty acid; an average primary particle diameter measured by an electron microscope of 0.05 μm), 40.0 parts by weight, Agent A 4.0 parts by weight, methyl isobutyl ketone 9.
0 parts by weight and 47.0 parts by weight of kerosene were mixed and pulverized by a ball mill for 30 hours. The calcium carbonate was finely dispersed.
A liquid having a high fluidity was obtained. When the obtained liquid was put in a glass bottle and allowed to stand for 20 days, a creamy substance was formed along the bottle wall, but when the bottle was shaken, the creamy substance was redispersed.

Comparative Example 1 A calcium carbonate dispersion was prepared in the same manner as in Example 1 except that methyl isobutyl ketone was not used at all and kerosene was used in an amount of 56 parts by weight. The obtained liquid was rich in fluidity as in the case of Example 1. When this solution was put in a glass bottle and allowed to stand, a gel-like layer was formed at the bottom of the bottle and gradually became thicker. After standing for 20 days, the dispersion was drained with the mouth of the bottle facing down, but the gel remained sticking to the bottom of the bottle. The proportion of gels remaining reached 20% by weight of the dispersion initially placed in the bottle. When the effluent dispersion was returned to the bottle and the bottle was shaken vigorously, the gel separated into several pieces but could not be redispersed.

Example 2 40.0 parts by weight of the same calcium carbonate as used in Example 1, 3.9 parts by weight of the dispersant B, 10.0 parts by weight of diisobutyl ketone, and 46.1 parts by weight of light oil were mixed and pulverized by a ball mill for 40 hours. The calcium carbonate was finely dispersed. A liquid containing the fluidity was obtained. This solution is filtered with two types of filter paper specified in JIS (with a retention particle diameter of 5 μm according to JIS-P3801;
Collection efficiency when a 0.3 μm DOP is passed at a flow rate of 1 m / min 8
(0%) with suction filtration and passed substantially without filtration residue. Put the filtrate in a polyethylene bottle and add 20
After standing for days, no sediment was formed.

Comparative Example 2 A calcium carbonate dispersion was prepared in the same manner as in Example 2 except that diisobutyl ketone was not used at all and the amount of light oil was changed to 56.1 parts by weight. The obtained liquid was included in the fluidity. This liquid was subjected to suction filtration using two kinds of filter papers in the same manner as in Example 2, but passed substantially without any filtration residue. The filtrate was placed in a polyethylene bottle and allowed to stand for 20 days. As time passed, a gel-like layer formed at the bottom of the bottle and gradually increased in thickness. After standing for 20 days, the bottle was shaken vigorously and the gel was broken into many pieces but did not redisperse.

Example 3 46.0 parts by weight of the same calcium carbonate used in Example 1,
4.3 parts by weight of the dispersant B, 7.7 parts by weight of amyl acetate and light oil 4
2.0 parts by weight were mixed and pulverized in a ball mill for 40 hours. A liquid containing calcium carbonate finely dispersed and containing fluidity was obtained. This liquid was subjected to suction filtration using two kinds of filter papers in the same manner as in Example 2, and the liquid passed substantially without a filtration residue. The filtrate was placed in a polyethylene bottle and allowed to stand for 20 days, but no sediment was formed.

Example 4 46.0 parts by weight of the same calcium carbonate as used in Example 1,
4.3 parts by weight of the dispersant A, 7.0 parts by weight of butyl acetate and kerosene 4
2.7 parts by weight were mixed and pulverized in a ball mill for 40 hours. A liquid with a high fluidity in which the calcium carbonate was finely dispersed was obtained. This liquid was subjected to suction filtration using two kinds of filter papers in the same manner as in Example 2, and the liquid passed substantially without a filtration residue. The filtrate was placed in a polyethylene bottle and allowed to stand for 20 days, but no sediment was formed.

Example 5 55.0 parts by weight of the same calcium carbonate as used in Example 1, 5.5 parts by weight of the dispersant B, 9.0 parts by weight of butyl acetate and 30.5 parts by weight of kerosene were mixed, and ground with a ball mill for 45 hours. A liquid in which calcium was finely dispersed was obtained. When the container is tilted, the liquid has a fluidity that immediately keeps the liquid level horizontal, but suction filtration using two types of filter paper is difficult. This solution was put in a polyethylene bottle and allowed to stand for 20 days, but no sediment was formed.

(F) Effect of the Invention The calcium carbonate dispersion of the present invention is significantly more fluid than an overbased calcium-sulfonate-based additive having the same calcium content. In addition, since the “ketone and / or carboxylic acid ester having 4 to 10 carbon atoms in the molecule” is used in combination with the polyester-based dispersant, the gelled sediment (the container is shaken) even if left for a long time. However, the generation of those which do not redisperse even if they are remarkably reduced can be significantly reduced or completely prevented. Therefore, a dispersion having a high calcium carbonate content of about 65% by weight or about 70% by weight can be prepared, and it is possible to provide a dispersion which is extremely advantageous in handling such as transfer and storage.

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Claims (2)

(57) [Claims] 1. A method for producing a finely divided calcium carbonate, comprising: (a) a general formula HO-X-COOH as a dispersant, wherein X is at least 8 carbon atoms including a side chain, and a hydroxy group and a carboxylic acid A divalent saturated or unsaturated aliphatic group having at least 4 carbon atoms not containing a side chain between the group and the group, or the hydroxycarboxylic acid and the aliphatic carboxylic acid A polyester and / or a salt thereof derived from a mixture with (b) the polyester or a salt thereof in an amount of 1 to 4 times (weight ratio)
Characterized by being dispersed in an organic liquid mainly composed of a liquid hydrocarbon containing an aliphatic ketone and / or a carboxylic acid ester having 4 to 10 carbon atoms in a molecule thereof. Calcium dispersion. 2. The dispersion according to claim 1, which contains 20% by weight or more of finely divided calcium carbonate.