JP6186821B2 - Aqueous dispersant and aqueous dispersion composition - Google Patents

Description

  The present invention relates to an aqueous dispersant capable of dispersing a dispersion such as organic or inorganic powder in water, and an aqueous dispersion composition containing the aqueous dispersant. More specifically, an aqueous dispersant capable of dispersing a dispersion having a small particle size in water at a high concentration and imparting excellent redispersibility, and an aqueous dispersion composition containing the aqueous dispersant Related to things.

  An aqueous dispersion composition in which a dispersion such as an organic or inorganic powder is dispersed in water is used in various industrial fields. Examples of organic powders include organic pigments, and aqueous dispersion compositions containing organic pigments are used in paints, printing inks, inkjet inks, color filter resists, writing instrument inks, and the like. Examples of inorganic powders include ceramics and metal powders. Aqueous dispersion compositions containing ceramic powders are used for electronic parts such as dielectric layers of multilayer ceramic capacitors, semiconductor substrates, sensors, and liquid crystal display elements. In addition, it is used for abrasives, refractory materials, etc., and aqueous dispersion compositions containing metal powder are widely used as electronic materials for forming electrodes such as paints, conductive pastes and conductive inks.

  When preparing an aqueous dispersion composition, the organic or inorganic powder alone is often insufficient in dispersibility. Therefore, for the purpose of improving the fluidity and storage stability of the aqueous dispersion composition, Dispersants are used in As the dispersant, a low molecular weight dispersant such as various surfactants, or a high molecular weight dispersant obtained by adding propylene oxide and ethylene oxide to an amino compound having 1 to 5 nitrogen atoms (see, for example, Patent Document 1) Has been proposed.

  In recent years, improvements in product characteristics such as downsizing, low power consumption, high efficiency, and high capacity have been desired in electronic component applications, and in order to meet these requirements, dispersions of ceramics and metal powder as raw materials There is a demand for finer particle size and higher concentration of the dispersion in the aqueous dispersion composition.

  However, due to demands for finer dispersion and higher concentration, dispersion with conventional dispersants may be insufficient, resulting in thickening of the aqueous dispersion composition accompanying dispersion aggregation and sedimentation of the dispersion. Such a problem has arisen. In the aqueous dispersion composition in which these problems occur, there arises a problem that not only the productivity, processing characteristics, and handling properties are lowered, but also the quality of the final product is lowered. Therefore, the dispersant must have a high concentration of the dispersion and a low-viscosity aqueous dispersion composition, as well as performance capable of being easily redispersed even if the dispersion settles. Has been.

  Patent Document 2 proposes a high molecular weight dispersant in which propylene oxide and ethylene oxide are added to a polyamine compound at a specific ratio in order to solve the decrease in initial dispersibility and redispersibility of the dispersion due to the finer dispersion. Has been. Patent Document 3 proposes a dispersant containing a polyamine compound to which an alkylene oxide has been added and rhamzan gum. However, these dispersants are not sufficiently satisfactory for the effect on the aqueous dispersion composition containing the finely dispersed dispersion at a high concentration.

JP 56-62538 A JP 58-80391 A JP-A-2-144141

  The object of the present invention is to solve the above-mentioned problems. Specifically, a dispersion such as an organic or inorganic powder, particularly a dispersion having a small particle diameter, can be dispersed in water at a high concentration, and is excellent. An object is to provide an aqueous dispersant capable of imparting redispersibility, and an aqueous dispersion composition containing the aqueous dispersant.

  As a result of intensive studies in order to solve the above problems, the present inventors have found that a polyether compound having a specific structure having a predetermined molecular weight can solve the above problems.

  That is, the present invention is an aqueous dispersant characterized by being a polyether compound represented by the formula (1) and having a molecular weight of 1,000 to 5,000, and an aqueous dispersion containing the aqueous dispersant It is a body composition.

（ただしＡ^１Ｏはオキシエチレン基であり、ａはＡ^１Ｏで示されるオキシエチレン基の平均付加モル数で、３〜２５であり、Ａ^２Ｏはオキシプロピレン基であり、ｂはＡ^２Ｏで示されるオキシプロピレン基の平均付加モル数で、１〜１０であり、ａとｂは５≦ａ＋ｂ≦３０、および１≦ａ／ｂ≦５の条件を満たし、Ｒは水素原子または炭素数１〜４の炭化水素基であり、ｎは１〜４である。）

(Wherein ^{A 1} O is an oxyethylene group, a is an average molar number of addition of oxyethylene group represented by ^{A 1} O, is 3 to 25, ^{A 2} O is an oxypropylene group, b is ^{A 2} The average added mole number of the oxypropylene group represented by O is 1 to 10, a and b satisfy the conditions of 5 ≦ a + b ≦ 30 and 1 ≦ a / b ≦ 5, and R is a hydrogen atom or carbon number 1 to 4 hydrocarbon groups, and n is 1 to 4.)

  According to the present invention, a dispersion having a small particle diameter such as organic or inorganic powder can be dispersed in water at a high concentration, and excellent redispersibility can be imparted.

  Hereinafter, embodiments of the aqueous dispersant and the aqueous dispersion composition of the present invention will be sequentially described.

(Aqueous dispersant)
The aqueous dispersant of the present invention is a polyether compound represented by the following formula (1). Hereinafter, the polyether compound represented by the formula (1) is also simply referred to as a polyether compound.

In said Formula (1), n is 1-4.
The nitrogen atom in the polyether compound acts as an adsorption site for the dispersion. When n exceeds 4, bridging agglomeration in which the dispersant is adsorbed across the dispersions occurs, so that the agglomeration of the dispersion is promoted and the initial dispersibility and redispersibility may be lowered.

A ¹ O and A ² O are polyoxyalkylene groups, and when adsorbed to the dispersion, act as a steric repulsion site to disperse the powder satisfactorily and increase the solubility in water. .
A ¹ O is an oxyethylene group having 2 carbon atoms, and A ² O is an oxypropylene group having 3 carbon atoms. a represents the average addition mole number of the oxyethylene group, b represents the average addition mole number of the oxypropylene group, a is 3 to 25, and b is 1 to 10. From the viewpoints of initial dispersibility, redispersibility and solubility in water, a and b are preferably 3 to 20, b is 1 to 8, and more preferably a is 5 to 15 and b is 2 ~ 5.

The average addition mole number a of the oxyethylene group represented by A ¹ O and the average addition mole number b of the oxypropylene group represented by A ² O are 5 ≦ a + b ≦ 30 and 1 ≦ a / b ≦ 5. Meet the conditions.

  a + b means a polyether chain length per equivalent of active hydrogen bonded to a nitrogen atom, and satisfies 5 ≦ a + b ≦ 30. If a + b is less than 5, it is difficult to obtain a sufficient steric repulsion effect. If a + b is more than 30, it becomes easy for the polyether chains to be entangled, and the initial dispersibility may be lowered. From the viewpoint of dispersion stability and initial dispersibility, a + b is preferably 5 ≦ a + b ≦ 25, and more preferably 10 ≦ a + b ≦ 25.

a / b represents the balance between the strongly hydrophilic A ¹ O and the strongly lipophilic A ² O of the polyether chain in the polyether compound. If a / b is less than 1, the lipophilicity is too high, and thus the polyether chain shrinks due to the decrease in solubility in water, and the steric repulsion effect is lowered, whereby the initial dispersibility may be lowered. When a / b is larger than 5, the ratio of A ² O is lowered, and therefore, the expansion of the polyether chain by A ² O added to the polyether terminal is reduced, so that a sufficient steric repulsion effect is obtained. There is a risk of disappearing. From the viewpoint of initial dispersibility, a / b is preferably 2 ≦ a / b ≦ 5, and more preferably 2 ≦ a / b ≦ 4.

R is a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms. Examples of the hydrocarbon group include saturated hydrocarbon groups such as methyl group, ethyl group, propyl group and butyl group, and unsaturated hydrocarbon groups such as allyl group and methallyl group. Preferably they are a hydrogen atom or a C1-C4 saturated hydrocarbon group, More preferably, they are a hydrogen atom or a methyl group. If the number of carbon atoms of the hydrocarbon group represented by R exceeds 4, production may be difficult.
The plurality of R in the polyether compound may all be the same hydrocarbon group or may be two or more different hydrocarbon groups.

The molecular weight of the polyether compound is 1,000 to 5,000. When the molecular weight is less than 1,000, not only the initial dispersibility may be lowered, but also sufficient redispersibility may not be obtained. On the other hand, if the molecular weight exceeds 5,000, the initial dispersibility may be lowered. The molecular weight is preferably 2,000 to 4,000 from the viewpoints of initial dispersibility and redispersibility.
In the present invention, the molecular weight is a molecular weight calculated from an amine value.

The polyether compound in which R in formula (1) is a hydrogen atom can be produced by adding alkylene oxide to a polyethylene polyamine having 2 to 5 nitrogen atoms.
In the addition reaction of alkylene oxide, a catalyst may be used, and in some cases, the catalyst may not be used. Examples of the catalyst used for the addition reaction of alkylene oxide include alkali catalysts, such as alkali metal or alkaline earth metal oxides or hydroxides, alcoholates, alkylamines such as triethylamine, and alkanols such as triethanolamine. Amines can be used. In addition to the above alkali catalyst, a Lewis acid catalyst such as boron trifluoride or tin tetrachloride can be used. As for the usage-amount of a catalyst, 0.01-5.0 mass% is common with respect to the mass after completion | finish of addition reaction.
The addition reaction of alkylene oxide, for example, in an inert gas atmosphere of argon or nitrogen gas at 50 to 200 ° C. and 0.02 to 1.0 MPa, the presence of a catalyst as necessary for the compound having a nitrogen atom as a raw material The alkylene oxide can be continuously added under pressure.

The polyether compound in which R in the formula (1) is a hydrocarbon group having 1 to 4 carbon atoms is an alkyl halide having 1 to 4 carbon atoms in the presence of an alkali catalyst as necessary after the addition reaction of alkylene oxide. It can be produced by reacting an alkenyl halide or the like to alkyl ether or alkenyl ether.
Examples of alkyl halides include methyl chloride, ethyl chloride, propyl chloride, butyl chloride, methyl bromide, ethyl bromide, methyl iodide, ethyl iodide and the like. Examples of alkenyl halides include allyl chloride, chloride. And methallyl. As the alkali catalyst at this time, an oxide or hydroxide of an alkali metal or alkaline earth metal, an alcoholate, or the like can be used.
The amount of alkyl halide or alkenyl halide charged is 100 to 400 mol% with respect to the hydroxyl group to be reacted, and the amount of alkali catalyst is 100 to 500 mol% with respect to the hydroxyl group to be reacted. The reaction temperature is generally 60 to 180 ° C.

  The aqueous dispersant of the present invention may be neutralized with an inorganic acid or an organic acid. Examples of inorganic acids include hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, etc., and organic acids include monocarboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, oxalic acid, maleic acid, fumaric acid, succinic acid, Examples thereof include polyvalent carboxylic acids such as citric acid and polycarboxylic acid copolymers, glycolic acid, lactic acid, malic acid, tartaric acid, hydroxy acids such as tartaric acid and gluconic acid, and sulfonic acids such as paratoluenesulfonic acid. One or more selected from inorganic acids and organic acids can be used.

[Aqueous dispersion composition]
The aqueous dispersion composition of the present invention contains the aqueous dispersant, the dispersion, and water of the present invention.
Content of an aqueous dispersing agent is 0.05-20 mass% in an aqueous dispersion composition. If the content is less than 0.05% by mass, sufficient initial dispersibility and redispersibility may not be obtained, and even if the content exceeds 20% by weight, an effect commensurate with the content may not be obtained. . The content of the aqueous dispersant is preferably 0.1 to 15% by mass, and more preferably 0.5 to 10% by mass, from the viewpoint of initial dispersibility or redispersibility.

Examples of the dispersion contained in the aqueous dispersion composition of the present invention include organic or inorganic powders.
Examples of organic powders include azo, diazo, condensed azo, thioindigo, indanthrone, quinacridone, anthraquinone, benzimidazolone, penylene, phthalocyanine, anthrapyridine, dioxazine, etc. And organic pigments.
Examples of inorganic powders include metal powders such as iron, aluminum, chromium, nickel, cobalt, zinc, tungsten, indium, tin, palladium, zirconium, titanium, copper, silver, gold, platinum, and alloy powders thereof. Body, composite powder, and mixed powder. Others, kaolin, clay, talc, mica, bentonite, dolomite, calcium silicate, magnesium silicate, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, barium sulfate, aluminum sulfate, aluminum hydroxide, iron hydroxide, silicic acid Aluminum, zirconium oxide, magnesium oxide, aluminum oxide, titanium oxide, iron oxide, zinc oxide, antimony trioxide, indium oxide, indium tin oxide, silicon carbide, silicon nitride, boron nitride, barium titanate, carbon black, graphite, rock Examples thereof include wool, glass wool, glass fiber, carbon fiber, carbon nanofiber, and carbon nanotube (single wall nanotube, double wall nanotube, multiwall nanotube).

  As the dispersion, a dispersion having a small average particle diameter, for example, a dispersion having an average particle diameter of 0.05 to 1 μm, and further 0.1 to 0.8 μm can exhibit good dispersibility. . The average particle size of the dispersion can be measured by a microtrack method.

  The content of the dispersion is usually 10 to 95% by mass in the aqueous dispersion composition, and particularly better dispersion in a high concentration system such as 65 to 90% by mass, and even 70 to 85% by mass. Can demonstrate its sexuality.

  The water content is usually 4 to 85% by mass in the aqueous dispersion composition, and particularly 5 to 30% by mass can exhibit better dispersibility.

  Various additives such as other surfactants, binders, plasticizers and antifoaming agents can be blended in the aqueous dispersion composition of the present invention as long as the purpose is not impaired.

The aqueous dispersion composition of the present invention can be produced according to a known method for producing an aqueous dispersion composition. For example, after adding the dispersion in an aqueous solution in which the dispersant is dissolved, stirring and mixing at room temperature, after adding water and a dispersant to the dispersion, stirring and mixing at room temperature, etc. Is mentioned.
A known disperser can be used as a disperser for stirring, mixing, or dispersing. Examples thereof include a roll mill, a ball mill, a bead mill, a sand mill, a jet mill, a homogenizer, and a rotation / revolution mixer. Further, the dispersion treatment can be performed in an ultrasonic wave generation bath.

  Next, the present invention will be described in more detail with reference to examples and comparative examples.

Synthesis example 1
In a stainless steel 5 liter pressure vessel equipped with a stirrer, pressure gauge, thermometer, safety valve, gas blowing pipe, exhaust pipe, cooling coil, and steam jacket, diethylenetriamine (manufactured by Kanto Chemical Co., Ltd. with nitrogen atoms per mole) 103 g of active hydrogen bonded (5 equivalents) was charged, and the inside of the system was replaced with nitrogen gas. Under agitation, the temperature was raised to 80 ° C., and then from a pressure vessel prepared separately under conditions of 80 to 100 ° C. and 0.05 to 0.5 MPa (gauge pressure), 220 g of ethylene oxide (per equivalent of active hydrogen bonded to nitrogen atoms) (Corresponding to 1 mol) was added under pressure with nitrogen gas through a gas blowing tube.
After the addition, the reaction was continued under the same conditions until the internal pressure became constant. After cooling to 40 ° C., 7.2 g of potassium hydroxide was added, and the system was replaced with nitrogen gas. Under stirring, the temperature was raised to 100 ° C., and then 2,420 g of ethylene oxide (corresponding to 11 mol per equivalent of active hydrogen bonded to a nitrogen atom) was blown into the gas under the conditions of 100 to 120 ° C. and 0.05 to 0.5 MPa. Pressure was added with nitrogen gas through the tube.
After the addition, the reaction was continued under the same conditions until the internal pressure became constant. Next, under stirring, under conditions of 100 to 120 ° C. and 0.05 to 0.5 MPa, 870 g of propylene oxide (corresponding to 3 mol per equivalent of active hydrogen bonded to a nitrogen atom) was passed through a gas blowing tube and nitrogen gas. After completion of the addition, the reaction was continued until the internal pressure became constant under the same conditions. After cooling to 30 ° C., the reaction product was taken out from the pressure vessel into a 5-liter eggplant flask. To this, 18 g of an adsorbent (trade name: KYOWARD 700, manufactured by Kyowa Chemical Industry Co., Ltd.) is added, treated under a nitrogen gas atmosphere at 90 to 100 ° C. and 0.05 MPa or less, and the resulting salt and adsorbent are filtered off. Thus, a polyether compound was obtained. The amine value of the obtained polyether compound was 46.6, and the molecular weight determined from the amine value was 3,610.

In addition, the measuring method of an amine value is as follows.
A sample is weighed into a beaker, and neutral ethanol (ethyl alcohol (99.5 V / V%) neutralized with N / 2 hydrochloric acid standard solution using bromocresol green indicator immediately before use) is dissolved therein. Let Next, several drops of bromcresol green indicator were added and titrated with a N / 2 hydrochloric acid standard solution. The end point was when the green color of the solution turned yellow. The amine value was calculated from the following formula.
Amine number = (28.05 × F × A) / W
However, A: Amount of N / 2 hydrochloric acid standard solution used, F: Factor of N / 2 hydrochloric acid standard solution, W: Amount of sample collected (g)

  Further, diethylenetriamine in Synthesis Example 1 was appropriately changed to another compound, and operations were performed according to Synthesis Example 1 to synthesize Synthesis Examples 2 to 4 in Table 1 and polyether compounds 5 to 6 in Table 2. .

[Examples 1-2, Comparative Examples 1-4]
Using the compounds of Synthesis Examples 1 to 6 as dispersants, three types of aqueous dispersion compositions were prepared as follows.
In a 50 mL screw tube, 5.0 g of silicon carbide powder (average particle size: 0.6 μm, and average particle size: 15 μm, measured by the microtrack method), 1.10 g, 2.54 g,. 83 g, 0.15 g, 0.15 g, and 0.05 g of the dispersing agent were weighed (dispersion concentration: 80% by mass, 65% by mass and 85% by mass), respectively, and stirred for 5 minutes with a rotation / revolution mixer, A slurry-like aqueous dispersion composition containing inorganic powder was obtained.
The aqueous dispersion compositions obtained using the compounds of Synthesis Examples 1 and 2 were designated as Examples 1-2, and the aqueous dispersion compositions obtained using the compounds of Synthesis Examples 3-6 were Comparative Examples 1 to 4. It was.

[Dispersion test]
A dispersion test was performed using the aqueous dispersion compositions of Examples 1-2 and Comparative Examples 1-4.
For each aqueous dispersion composition, using a dynamic viscoelastic device (Paar Physica MCR-300, manufactured by Anton Paar), the shear viscosity for a temperature of 20 ° C. and a shear rate of 0.1 to 100 (1 / s) is obtained. Table 3 shows the shear viscosity when the shear rate was 1 (1 / s).
In addition, each aqueous dispersion composition that was allowed to stand at room temperature for 1 week was re-stirred for 5 minutes with a rotation and revolution mixer, and the shear viscosity of each aqueous dispersion composition was measured under the same conditions. The shear viscosity at 1 / s) is also shown in Table 3.

(When the average particle size of silicon carbide is 0.6 μm, the dispersion concentration is 80 mass%, and the dispersant concentration is 3 mass%)
The aqueous dispersion compositions of Examples 1 and 2 to which the compounds of Synthesis Examples 1 and 2 according to the present invention were added showed good dispersibility immediately after production, and the viscosity over time even after 1 week. Little change was seen.
On the other hand, the aqueous dispersion composition of Comparative Example 1 to which the compound of Synthesis Example 3 was added, in which a / b was smaller than the specified range of the present invention, caused a change in viscosity over time, and the shear viscosity was carried out immediately after production. Compared to the examples, the dispersibility was poor.
Although the aqueous dispersion composition of Comparative Example 2 to which the compound of Synthesis Example 4 was added, in which a / b is larger than the specified range of the present invention, the change in viscosity over time was small, but the shear viscosity was immediately after production as in Examples. Compared with it, it was high and dispersibility was inferior.
Aqueous dispersion compositions of Comparative Examples 3 and 4 to which the compounds of Synthesis Examples 5 and 6 having structures in which the addition forms of oxyalkylene groups in the polyether compound represented by the formula (1) according to the present invention are reversed are added Caused a change in viscosity over time, and the shear viscosity was extremely high immediately after production as compared with the Examples, and the dispersibility was much inferior.

(When the average particle size of silicon carbide is 0.6 μm, the dispersion concentration is 65 mass%, and the dispersant concentration is 3 mass%)
The aqueous dispersion compositions of Examples 1 and 2 to which the compounds of Synthesis Examples 1 and 2 according to the present invention were added showed good dispersibility immediately after production, and the viscosity over time even after 1 week. Little change was seen.
Although the aqueous dispersion composition of Comparative Example 1 to which the compound of Synthesis Example 3 was added, in which a / b is smaller than the specified range of the present invention, the change in viscosity over time was small, but the shear viscosity was compared with that of the Example immediately after production. And dispersibility was poor.
In the aqueous dispersion composition of Comparative Example 2 in which the compound of Synthesis Example 4 was added with a / b larger than the specified range of the present invention, although the viscosity change with time hardly occurred, the shear viscosity was carried out immediately after production. It was higher than the example. However, in comparison with the case of the dispersion concentration: 80% by mass, the difference in viscosity between Examples 1 and 2 and Comparative Example 2 is small.
The aqueous dispersion compositions of Comparative Examples 3 and 4 to which the compounds of Synthesis Examples 5 and 6 having a structure in which the addition form of the oxyalkylene group in the polyether compound represented by the formula (1) according to the present invention is reversed are added. Although there was almost no change in viscosity over time, the shear viscosity was high compared to the Examples immediately after production and the dispersibility was inferior.

(When the average particle diameter of silicon carbide is 15 μm, the dispersion concentration is 85 mass%, and the dispersant concentration is 1 mass%)
The aqueous dispersion compositions of Examples 1 and 2 to which the compounds of Synthesis Examples 1 and 2 according to the present invention were added showed good dispersibility immediately after production, and the viscosity over time even after 1 week. Little change was seen.
The aqueous dispersion composition of Comparative Example 1 with the addition of the compound of Synthesis Example 3 in which a / b is smaller than the specified range of the present invention, and the comparison with the compound of Synthesis Example 4 in which a / b is larger than the specified range of the present invention Comparison in which the aqueous dispersion composition of Example 2 and the compounds of Synthesis Examples 5 and 6 having a structure in which the addition form of the oxyalkylene group in the polyether compound represented by the formula (1) according to the present invention was reversed were added The aqueous dispersion compositions of Examples 3 and 4 showed good dispersibility as in Examples 1 and 2, and almost no change in viscosity over time was observed even after one week.

  From the results of the above Examples and Comparative Examples, when the dispersant of the present invention is a dispersion having a small average particle diameter and the dispersion concentration is a high concentration of 65% by mass or more, the effect is easily exerted remarkably. I understand that.

Claims (2)

A water-based dispersant, which is a polyether compound represented by the formula (1) and having a molecular weight of 1,000 to 5,000.

(Wherein ^{A 1} O is an oxyethylene group, a is an average molar number of addition of oxyethylene group represented by ^{A 1} O, is 3 to 25, ^{A 2} O is an oxypropylene group, b is ^{A 2} The average added mole number of the oxypropylene group represented by O is 1 to 10, a and b satisfy the conditions of 5 ≦ a + b ≦ 30 and 1 ≦ a / b ≦ 5, and R is a hydrogen atom or carbon number 1 to 4 hydrocarbon groups, and n is 1 to 4.)   An aqueous dispersion composition comprising the aqueous dispersant according to claim 1.