Dispersant for fine particles and slurry composition

Abstract

To provide a slurry composition that can maintain high stability of dispersion of fine particles even when having a binder added thereto.SOLUTION: A fine-particle dispersant comprises a polyether ester compound, which is an ester reactant of a component (a1) and a component (a2) and has an acid value of 85-220 mgKOH / g, or a neutralized salt thereof. Component (a1): a polyether compound of formula (1): HO-(AO)m-H (1) (AO is C2-4 oxyalkylene groups, with 20 mass% or more of AO being oxyethylene groups, and m is 2-30). Component (a2): a C2-9 polybasic acid having two or three carboxyl groups, or an acid anhydride thereof.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a dispersant for fine particles used for dispersing dispersions such as organic or inorganic powders in a solvent, and a slurry composition. More specifically, the present invention relates to a dispersant for fine particles that maintains excellent dispersion stability even when a binder is added, and a slurry composition using the same. [Background technology]

[0002] Electronic components such as multilayer ceramic capacitors (MLCCs) and multilayer chip inductors are manufactured by stacking green sheets made of ceramics such as barium titanate and ferrite and binder resin. These green sheets are manufactured by blending ceramic particles, solvents, dispersants, etc., and crushing them in a bead mill or ball mill, and then adding polyvinyl butyral resin, acrylic resin, and plasticizers to prepare a slurry composition, which is then coated on a PET film or the like and dried.

[0003] In recent years, as electronic devices have become smaller and more powerful, there has been a demand for smaller, larger-capacity MLCCs. To achieve this, the ceramic green sheets and conductive layers that make up these components are becoming thinner and more multi-layered. To obtain high-quality thin-film sheets, the ceramic and metal powders used as raw materials for the slurry composition are finely divided, and high-molecular-weight resins are used as binders to ensure strength even in thin films.

[0004] Meanwhile, conventionally, dispersants have been used to efficiently disintegrate ceramic powders or metal powders in solvents and to ensure dispersion stability after disintegration. For example, Patent Document 1 proposes an ester of polyoxyethylene monophenyl ether and a cyclic carboxylic acid. However, as mentioned above, when the powder is microparticulated, the cohesive force between the particles increases, which causes problems such as a decrease in dispersibility at the initial stage of disintegration and a decrease in dispersion stability over time. To address these problems, dispersants have been proposed that improve the initial dispersibility and dispersion stability of fine particles with a particle size of 1 μm or less in a solvent, and Patent Document 2 discloses an ester of a specific polyoxyalkylene alkyl ether and trimellitic acid. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-144402 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-147216 Summary of the Invention [Problem to be solved by the invention]

[0006] However, as raw material powders have become increasingly finer in recent years, the demand for better dispersion performance from dispersants used in slurry compositions has been increasing. In particular, when the particle size of the powder is small, the dispersibility and dispersion stability achieved in the solvent may be significantly reduced when a binder component, such as a polymeric resin, is added to the slurry. If the dispersion stability of the slurry composition is reduced, the slurry cannot be applied uniformly, which makes it difficult to obtain a thin, high-quality green sheet.

[0007] An object of the present invention is to solve the above-mentioned problems, and more specifically, to provide a slurry composition that can maintain excellent powder dispersion stability not only in a solvent but also when a binder is added. [Means for solving the problem]

[0008] As a result of intensive research into solving the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by using a dispersant for fine particles comprising a polyether ester compound composed of a polyether having a specific structure and a polybasic acid, or a neutralized salt thereof.

[0009] That is, the present invention is the following [1] and [2]. [1] A dispersant for fine particles, characterized by comprising a polyether ester compound which is an ester reaction product of the following component (a1) and the following component (a2), and has an acid value of 85 to 220 mgKOH / g, or a neutralized salt thereof: Component (a1): A polyether compound represented by the following formula (1): HO-(AO) m -H (1) (In formula (1), AO is an oxyalkylene group having 2 to 4 carbon atoms, and 20 mass% or more of the oxyalkylene groups AO are oxyethylene groups; m is the average number of moles of the oxyalkylene group AO added, and is 2 to 30. Component (a2): A polybasic acid or anhydride thereof having 2 to 9 carbon atoms and 2 or 3 carboxyl groups.

[0010] [2] A slurry composition comprising 0.01 to 6 mass% of component (A), 1 to 10 mass% of component (B), 10 to 60 mass% of component (C), and the remainder being component (D). Component (A): [1] Dispersant for fine particles. Component (B): Polyvinyl butyral Component (C): Powder with an average particle size of 200 nm or less Component (D): Solvent [Effects of the Invention]

[0011] According to the present invention, not only is dispersion stability of the powder in the solvent maintained, but excellent dispersion stability can also be maintained even when a binder is added. DETAILED DESCRIPTION OF THE INVENTION

[0012] The dispersant for fine particles and the slurry composition of the present invention will be described below. (dispersant for fine particles) The dispersant for fine particles of the present invention comprises an ester reaction product of component (a1) and component (a2), and is a polyether ester compound characterized by having an acid value of 85 to 220 mgKOH / g, or a neutralized salt thereof.

[0013] (Component (a1)) The component (a1) in the present invention is a polyether compound represented by formula (1). HO-(AO) m -H (1) In formula (1), AO is an oxyalkylene group having 2 to 4 carbon atoms, and is obtained by addition polymerization of ethylene oxide, propylene oxide, or butylene oxide. The addition form may be random or block.

[0014] When the total mass of the oxyalkylene groups AO is taken as 100 mass%, the oxyethylene groups account for 20 mass% or more, preferably 35 mass% or more, and more preferably 50 mass% or more. If the mass of the oxyethylene groups is less than 20 mass%, compatibility with alcohol solvents and polyvinyl butyral resins becomes difficult to obtain, resulting in a decrease in the dispersion stability of the slurry.

[0015] When the total mass of the oxyalkylene groups AO is taken as 100 mass %, the proportion of oxyethylene groups may be 100 mass %.

[0016] In formula (1), m is the average number of moles of oxyalkylene groups added, represented by AO, and is 2 to 30. If m is less than 2, it becomes difficult to obtain dispersion stability. If m exceeds 30, powder particles tend to aggregate together, making it difficult to reduce the viscosity at the initial stage of dispersion. From the viewpoint of the present invention, m is preferably 3 or more, and more preferably 4 or more. Furthermore, m is preferably 20 or less, and more preferably 15 or less.

[0017] The molecular weight of the polyether compound represented by formula (1) is preferably 100-1,500, more preferably 100-1,000, and even more preferably 100-600.

[0018] (ingredient (a2)) Component (a2) in the present invention is a polybasic acid having 2 to 9 carbon atoms and 2 or 3 carboxyl groups, or an acid anhydride thereof. The polybasic acid particularly preferably has 2 to 6 carbon atoms. Examples of polybasic acids include succinic acid, maleic acid, adipic acid, phthalic acid, and trimellitic acid. From the viewpoint of ease of reaction with alcohol, acid anhydrides are preferred, including succinic anhydride, maleic anhydride, phthalic anhydride, and trimellitic anhydride, with succinic anhydride being particularly preferred.

[0019] The polyetherester compound of the present invention is an ester reaction product obtained by esterifying component (a1) and component (a2). This reaction may be carried out without a solvent, or an appropriate dehydrated organic solvent may be used. After completion of the reaction, the solvent used in the reaction may be removed by an operation such as distillation, or it may be used as a part of the product as it is. The reaction temperature is preferably 60 to 180°C, more preferably 70 to 160°C, and particularly preferably 80 to 140°C.

[0020] The reaction ratio of component (a1) and component (a2) is preferably component (a1) / component (a2)=2 / 1 to 1 / 2 molar ratio.

[0021] The acid value of the polyether ester compound of the present invention is 85 to 220 mgKOH / g, preferably 100 to 220 mgKOH / g, more preferably 120 to 220 mgKOH / g, and even more preferably 140 to 200 mgKOH / g. If the acid value is less than 85 mgKOH / g, the adsorption power to powder is poor, making it difficult to obtain dispersion stability.

[0022] The molecular weight of the present polyether ester compound is preferably 200 to 1600, more preferably 200 to 1100, and even more preferably 200 to 700. The molecular weight can be measured by a general method, for example, gel permeation chromatography using THF solvent.

[0023] The polyether ester compound of the present invention may be neutralized with an amine, such as ammonia, alkylamines such as methylamine, dimethylamine, and ethylamine, or alkanolamines such as monoethanolamine, diethanolamine, and triethanolamine, and one or more of these may be used.

[0024] (Slurry Composition) The slurry composition of the present invention contains 0.01 to 6 mass % of component (A), 1 to 10 mass % of component (B), 10 to 60 mass % of component (C), and the remainder component (D). Component (A): The above-described dispersant for fine particles. Component (B): Polyvinyl butyral Component (C): Organic or inorganic powder with an average particle size of 200 nm or less Component (D): Solvent

[0025] The content of component (A) (fine particle dispersant) in the slurry composition is 0.01 to 6% by mass. The content of component (A) is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and particularly preferably 0.3% by mass or more. The content of component (A) is more preferably 5% by mass or less, and particularly preferably 4% by mass or less. However, the total content of component (A), component (B), component (C) and component (D) is 100 mass %. The fine particles refer to (C) organic or inorganic powders having an average particle size of 200 nm or less.

[0026] As component (B) (binder) in the slurry composition, polyvinyl butyral resin, acrylic resin, ethyl cellulose resin, etc. can be used, but polyvinyl butyral resin is preferred because it is easy to obtain strength in a thin green sheet.

[0027] In particular, from the viewpoint of facilitating the attainment of strength in a thin green sheet, it is preferable to combine the dispersant for fine particles of the present invention with polyvinyl butyral having a weight-average molecular weight of 60,000 or more, and more preferably with polyvinyl butyral having a weight-average molecular weight of 100,000 or more. Furthermore, from the viewpoint of solubility in solvents, the weight-average molecular weight of the polyvinyl butyral resin is preferably 1,000,000 or less, and more preferably 500,000 or less. The weight average molecular weight in the present invention was measured by gel permeation chromatography under the following conditions. Equipment: Tosoh Corporation HLC-8320GPC Column: Showa Denko SHODEX KF-804L (inner diameter 8 mm x length 30 cm), 3 columns Eluent: tetrahydrofuran Flow rate: 1.0mL / min Detector: Differential refractometer (RI) Temperature: 40℃ Standard: Polyethylene glycol Sample: 100 μL of THF solution containing 0.1 wt% of the active ingredient

[0028] The content of component (B) in the slurry composition is 1 to 10% by mass, preferably 1 to 8% by mass, and more preferably 2 to 6% by mass.

[0029] Component (C) (organic powder and inorganic powder) is not limited as long as it is a powder that is generally used in a slurry form, but is particularly suitable for ceramic powders that are widely used as raw materials for electronic components manufactured by layered construction methods.

[0030] Examples of ceramic powders include powders of silicate minerals, other silicate compounds, carbonate compounds, sulfate compounds, hydroxide compounds, oxide compounds, nitride compounds, carbides, titanate compounds, etc. Examples of ceramic powders include powders of kaolin, clay, talc, mica, bentonite, dolomite, calcium silicate, aluminum silicate, magnesium silicate, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, barium sulfate, aluminum sulfate, aluminum hydroxide, iron hydroxide, zirconium oxide, magnesium oxide, aluminum oxide, titanium oxide, iron oxide, zinc oxide, antimony trioxide, indium oxide, indium tin oxide, silicon carbide, tungsten carbide, aluminum nitride, silicon nitride, boron nitride, barium titanate, calcium titanate, strontium titanate, carbon black, glass fiber, carbon fiber, carbon nanofiber, and carbon nanotubes (single-walled nanotubes, double-walled nanotubes, and multi-walled nanotubes).

[0031] Particularly preferred ceramic powders are powders of oxide compounds such as zirconium oxide, magnesium oxide, aluminum oxide, iron oxide, zinc oxide, and indium tin oxide, and powders of titanate compounds such as barium titanate, calcium titanate, and strontium titanate.

[0032] As green sheets become thinner, there is a tendency to use ceramic powders with smaller average particle sizes. From this perspective, it is preferable to combine them with ceramic powders with an average particle size of 200 nm or less, more preferably with ceramic powders with an average particle size of 100 nm or less, and even more preferably with ceramic powders with an average particle size of 50 nm or less. The average particle size of the powder can be measured using a scanning electron microscope (SEM).

[0033] The content of component (C) is 10 to 60 mass %, preferably 20 to 60 mass %, and more preferably 20 to 50 mass %.

[0034] As component D (solvent), a solvent compatible with the dispersant and binder can be used. Examples of such solvents include alcohol-based solvents, ether-based solvents, ketone-based solvents, and aromatic solvents. In particular, ethanol, toluene, and mixed solvents thereof are preferred in terms of compatibility with polyvinyl butyral.

[0035] In the present composition, component (D) (solvent) is the remainder when the total content of components (A), (B), (C) and (D) is taken as 100 mass %.

[0036] The slurry composition of the present invention and the ceramic green sheet composition using the same may contain, in addition to the above-mentioned compounds, other common components such as ceramic additives, plasticizers, antistatic agents, etc. For example, general-purpose plasticizers include dioctyl phthalate, dibutyl phthalate, dioctyl adipate, and tributyl acetyl citrate. Furthermore, the proportion of these additional components is preferably 7% by mass or less, and more preferably 5% by mass or less, when the total amount of components (A), (B), (C), and (D) is taken as 100% by mass. [Example]

[0037] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0038] (Manufacturing example) Example 1 Polyethylene glycol (m=5, 400 g, 2 mol) and succinic anhydride (200 g, 2 mol) were charged into a 1 L four-neck flask and heated to 90°C while stirring to make the mixture homogeneous. After reaching the temperature, the mixture was cooled 7 hours later to stop the reaction. The acid value of the compound of Example 1 obtained was 185, and the weight average molecular weight measured by GPC was 303.

[0039] Example 2 The reaction was carried out for 7 hours at 110° C. using the same raw materials and amounts as in Example 1. The acid value of the obtained compound was 130, and the weight average molecular weight measured by GPC was 432.

[0040] Example 3 The reaction was carried out for 12 hours at 110° C. using the same raw materials and amounts as in Example 1. The acid value of the obtained compound was 112, and the weight average molecular weight measured by GPC was 501.

[0041] Example 4 Polyethylene glycol (m = 10, 402 g, 1 mol) and succinic anhydride (200 g, 2 mol) were charged into a 1 L four-neck flask and heated to 90 °C while stirring until homogeneous. After reaching the temperature, the mixture was cooled 7 hours later to stop the reaction. The acid value of the resulting compound was 185, and the weight average molecular weight measured by GPC was 636.

[0042] Example 5 Ethylene oxide propylene oxide copolymer (m = 6: EO to PO molar ratio 1:1: 300 g, 1 mol) and trimellitic anhydride (162 g, 0.77 mol) were charged into a 1 L four-neck flask and heated to 120 °C while stirring until homogeneous. After reaching the temperature, the mixture was cooled 7 hours later to stop the reaction. The acid value of the resulting compound was 153, and the weight average molecular weight measured by GPC was 660.

[0043] (Comparative Example 1) The same raw materials and charging ratios were used as in Example 1. However, unlike Example 1, the temperature was raised to 150°C while stirring to make the mixture uniform. After reaching the temperature, the mixture was cooled 5 hours later to stop the reaction. The acid value of the resulting compound was 80, and the weight average molecular weight measured by GPC was 701.

[0044] (Comparative Example 2) Propylene glycol (m = 5, 560 g, 2 mol) and succinic anhydride (200 g, 2 mol) were charged into a 1 L four-neck flask and heated to 90 °C while stirring until homogeneous. After reaching the temperature, the mixture was cooled 7 hours later to stop the reaction. The acid value of the resulting compound was 141, and the weight average molecular weight measured by GPC was 395.

[0045] (Comparative Example 3) Polyethylene glycol (m = 25, 500 g, 0.5 mol) and succinic anhydride (50 g, 0.5 mol) were charged into a 1 L four-neck flask and heated to 110 °C while stirring until homogeneous. After reaching the temperature, the mixture was cooled 8 hours later to stop the reaction. The acid value of the resulting compound was 50, and the weight average molecular weight measured by GPC was 1122.

[0046] Comparative Example 4 Polyethylene glycol (m = 2, 186 g, 3 mol) and succinic anhydride (300 g, 3 mol) were charged into a 1 L four-neck flask and heated to 90 °C while stirring until homogeneous. After reaching the temperature, the mixture was cooled 5 hours later to stop the reaction. The acid value of the resulting compound was 290, and the weight average molecular weight measured by GPC was 193.

[0047] (Comparative Examples 5 and 6) The compound of Comparative Example 5 was a copolymer of maleic anhydride and allyl polyether (weight average molecular weight 10,000), and the compound of Comparative Example 6 was isodecyl-EO (oxyethylene group) 3 mol-PO (oxypropylene group) 8 mol-trimellitic acid monoester.

[0048] (Method for preparing a slurry composition) Using the synthesized compounds of Examples 1, 3, and 5 and Comparative Examples 2 and 5 as dispersants, slurry compositions 1-1 to 1-5 and 2-1 to 2-5 were prepared as follows. 100.0 g of barium titanate powder (average particle size: 0.1 μm, measured by electron microscopy using SEM), 40 g of a toluene / ethanol mixed solvent (weight ratio 1 / 1), and 2 g of each dispersant were weighed into a 250 mL plastic bottle, and the mixture was dispersed in a ball mill using 2 mm zirconia beads for 8 hours to obtain slurry compositions 1-1 to 1-5. Furthermore, 143 g of polyvinyl butyral resin (weight average molecular weight 200,000) solution (a solution of 10 g of resin dissolved in 133 g of a toluene / ethanol mixed solvent) and 4 g of dioctyl phthalate were added to each slurry composition, and the mixture was dispersed in a ball mill using 2 mm zirconia beads for 10 hours to obtain slurry compositions 2-1 to 2-5. The blending amounts of each raw material for the slurry are shown in Table 2.

[0049] (Slurry stability evaluation) The viscosity of each slurry composition was measured immediately after dispersion and after 24 hours. The viscosity was measured using a dynamic viscoelasticity device (Paar Physica MCR-300, manufactured by Anton Paar) at a temperature of 20°C and at shear rates of 0.1 to 100 (1 / s). The shear viscosity at a shear rate of 1 (1 / s) is shown in Tables 3 and 5.

[0050] As an index of stability, the viscosity increase ratio between the viscosity immediately after dispersion and the viscosity after 24 hours (viscosity after 24 hours / viscosity immediately after dispersion) was measured and evaluated according to the following criteria. Thickening ratio Stability evaluation 1.00~1.05 ◎ 1.05~1.20 〇 If it exceeds 1.20 ×

[0051] [Table 1]

[0052] [Table 2]

[0053] [Table 3]

[0054] As shown in Table 3, slurry compositions 1-1, 1-2, 1-3, 2-1, 2-2, and 2-3 using the dispersants of Examples 1, 3, and 5 of the present invention have high stability of viscosity after dispersion, regardless of the presence or absence of a binder. Compositions 1-4, 1-5, 2-4, and 2-5, which used the dispersants of Comparative Examples 2 and 5, were inferior in viscosity stability after dispersion, particularly when they contained a binder.

[0055] Slurry compositions 3-1 to 11 and 4-1 to 11 were prepared in the same manner as above, except that the synthesized compounds of Examples 1 to 5, Comparative Examples 1 to 4, and Comparative Examples 5 and 6 were used as dispersants, and 100.0 g of barium titanate powder (average particle size: 0.05 μm, measured by electron microscopy using SEM) was used as the powder. The blending amounts of each raw material for the slurry are shown in Table 4.

[0056] [Table 4]

[0057] [Table 5]

[0058] As shown in Table 5, slurry compositions 3-1 to 3-5 and 4-1 to 4-5 using the dispersants of Examples 1 to 5 of the present invention have high stability of viscosity after dispersion, regardless of the presence or absence of a binder. Compositions 3-6, 3-7, 4-6, and 4-7, which used the dispersants of Comparative Examples 1 and 2, were inferior in viscosity stability after dispersion, particularly when they contained a binder. In the compositions 3-8, 3-9, 4-8, and 4-9 in which the dispersants of Comparative Examples 3 and 4 were used, no slurries were produced. Compositions 3-10, 3-11, 4-10, and 4-11, which used the dispersants of Comparative Examples 5 and 6, were inferior in viscosity stability after dispersion, particularly when a binder was contained.

[0059] Slurry compositions 5-1 to 5-3 and 6-1 to 5-3 were prepared in the same manner as above, using the compounds of Example 1, Example 5, and Comparative Example 5 as dispersants and polyvinyl butyral resin (weight average molecular weight 50,000) as binder, with the amounts of each raw material shown in Table 6. Each composition was then evaluated in the same manner as above. The results are shown in Tables 6 and 7.

[0060] [Table 6]

[0061] [Table 7]

[0062] As shown in Table 7, slurry compositions 5-1, 5-2, 6-1, and 6-2, which used the dispersants of Examples 1 and 5 of the present invention, had high stability of viscosity after dispersion, regardless of the presence or absence of a binder. Compositions 5-3 and 6-3, which used the dispersant of Comparative Example 1, had poor viscosity stability after dispersion, particularly when a binder was contained.

Claims

1. A dispersant for fine particles, characterized by comprising a polyether ester compound or a neutralized salt thereof, which is an ester reaction product of the following component (a1) and the following component (a2), and has an acid value of 85 to 220 mgKOH / g: Component (a1): A polyether compound represented by the following formula (1): HO-(AO) ｍ -H ・・・・(1) (In formula (1), AO is an oxyalkylene group having 2 to 4 carbon atoms, and 20 mass% or more of the oxyalkylene groups AO are oxyethylene groups, m is the average number of moles of the oxyalkylene group AO added, and is 2 to 30. Component (a2): A polybasic acid or anhydride thereof having 2 to 9 carbon atoms and 2 or 3 carboxyl groups.

2. A slurry composition comprising 0.01 to 6 mass% of the following component (A), 1 to 10 mass% of component (B), 10 to 60 mass% of component (C), and the remainder being component (D): Component (A): The dispersant for fine particles according to claim 1. Component (B): Polyvinyl butyral Component (C): Powder with an average particle size of 200 nm or less Component (D): Solvent

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