Method for selecting a dispersant, method for producing a dispersion, and method for analyzing a dispersion.

Abstract

This invention provides a method for selecting a dispersant that allows for easy selection of the appropriate dispersant. [Solution] A method for selecting a dispersant according to one aspect of the present invention is a method for selecting a dispersant for obtaining a dispersion by mixing solid particles, a dispersant, and a dispersion medium, and includes the step of selecting the dispersant based on the distance Ra between the Hansen solubility parameters of the solid particles and the dispersant.

Description

[Technical Field]

[0001] This invention relates to a method for selecting a dispersant, a method for producing a dispersion, and a method for analyzing a dispersion. [Background technology]

[0002] For example, in the manufacturing process of ceramics, a dispersion liquid is used, which is a mixture of solid particles and a dispersion medium. In this process, a dispersant is often added to the dispersion liquid to improve the dispersibility of the solid particles.

[0003] Traditionally, selecting a dispersant suitable for solid particles required choosing from a vast number of dispersants based on their performance charts (hydrophobicity / hydrophilicity, molecular weight, etc.) and information on recommended solid particles, then fabricating a dispersion, measuring its properties, and making a final judgment.

[0004] Patent Document 1 is an example of a study on indicators for selecting a dispersant. Patent Document 1 discloses a method for producing a dispersion by mixing multiple types of solid particles, water, and a liquid dispersant. Patent Document 1 also discloses selecting solid particles and a dispersant using the overlap of Hansen spheres between the solid particles and the dispersant, and the Hansen solubility parameter distance Ra between the solid particles and water as indicators. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2021-134136 [Overview of the project] [Problems that the invention aims to solve]

[0006] When selecting a dispersant by referring to the performance table of the dispersant and the information on the recommended solid particles as described above, there are many dispersants with similar performances, and it may not be possible to determine the optimal dispersant. That is, it has taken a great deal of time and effort to select the optimal dispersant for solid particles. In addition, the technology described in Patent Document 1 assumes the use of water, and the application target is limited.

[0007] As described above, the prior art has room for further improvement from the viewpoint of easily selecting a dispersant. One aspect of the present invention aims to realize a method for selecting a dispersant that can easily select a dispersant.

Means for Solving the Problems

[0008] In order to solve the above problems, a method for selecting a dispersant according to one aspect of the present invention is a method for selecting a dispersant for obtaining a dispersion liquid by mixing solid particles, a dispersant, and a dispersion medium, and includes a step of selecting the dispersant based on the Hansen solubility parameter distance Ra between the solid particles and the dispersant.

Effects of the Invention

[0009] According to one aspect of the present invention, it is possible to provide a method for selecting a dispersant that can easily select a dispersant.

Brief Description of the Drawings

[0010] [Figure 1] It is a diagram showing a plot of Ra1 (Ra1a for Dispersants 1 to 3) and the Rsp value between each of Dispersants 1 to 5 and aluminum oxide (particle size: 1 μm) (dispersion medium: ethanol). [Figure 2] It is a diagram showing a plot of Ra1 (Ra1a for Dispersants 1 to 3) and the Rsp value between each of Dispersants 1 to 5 and aluminum oxide (particle size: 0.3 μm) (dispersion medium: ethanol). [Figure 3] It is a diagram showing a plot of Ra1 (Ra1a for Dispersants 1 to 3) and the Rsp value between each of Dispersants 1 to 5 and aluminum oxide (particle size: 0.02 to 0.05 μm) (dispersion medium: ethanol). [Figure 4] Figure showing the plots of Ra1 (Ra1a for dispersants 1 to 3) and Rsp values between each of the dispersants 1 to 5 and barium titanate (particle size 0.1 μm) (dispersion medium: ethanol). [Figure 5] Figure showing the plots of Ra1 (Ra1a for dispersants 1 to 3) and Rsp values between each of the dispersants 1 to 5 (dispersion medium: acetone) and barium titanate (particle size 0.1 μm). [Figure 6] Figure showing the plots of Ra1 (Ra1a for dispersants 1 to 3) and Rsp values between each of the dispersants 1 to 5 and barium titanate (particle size 0.1 μm) (dispersion medium: N,N-dimethylformamide). [Figure 7] Figure showing the plots of Ra1 (Ra1a for dispersants 1 to 3) and Rsp values between each of the dispersants 1 to 5 and barium titanate (particle size 3 μm) (dispersion medium: ethanol).

Embodiments for Carrying Out the Invention

[0011] An embodiment of the present invention will be described below, but the present invention is not limited thereto. Unless otherwise specified in this specification, "A to B" representing a numerical range means "A or more and B or less".

[0012] 〔1. Method for Selecting Dispersant〕 The method for selecting a dispersant according to an embodiment of the present invention is a method for selecting a dispersant for obtaining a dispersion liquid by mixing solid particles, a dispersant, and a dispersion medium, and includes a step of selecting the dispersant based on the Hansen solubility parameter distance Ra between the solid particles and the dispersant. Hereinafter, the Hansen solubility parameter will also be referred to as HSP, and the Hansen solubility parameter distance will also be referred to as HSP distance.

[0013] The method for producing the dispersion liquid will be described later. In this specification, for convenience, the medium for dispersing solid particles to obtain a dispersion liquid is referred to as a "dispersion medium", and the medium mixed with the solid particles or the dispersant to calculate HSP as described later is referred to as a "solvent".

[0014] The HSP is defined by three-dimensional parameters of (δd, δp, δh), and the relationship with Hildebrand solubility parameter (δ) is expressed by the following formula (I). δ 2 =(δd) 2 +(δp) 2 +(δh) 2 ···(I) δd: Dispersion term (London dispersion force) δp: Polarization term (dipole-dipole force) δh: Hydrogen bonding term (hydrogen bonding force) According to HSP, the properties of a compound can be displayed on a three-dimensional coordinate. Also, a Hansen sphere can be drawn centered on HSP.

[0015] The HSP distance Ra indicates the distance between the HSPs of two substances. The HSP distance Ra is an index representing the affinity between both substances, and it can be said that the smaller the value, the higher the affinity between both substances. The respective HSPs of two substances A and B, δ A and δ B are δ A =(δd A , δp A , δh A ) δ B =(δd B , δp B , δh B ) Assuming that, the HSP distance Ra can be calculated by the following formula (II). Ra={4×(δd A -δd B ) 2 +(δp A -δp B ) 2 +(δh A -δh B ) 2} 1 / 2 ···(II) The technology described in Patent Document 1 assumes a case where water, a liquid dispersant, and solid particles are mixed, and uses the overlap of Hansen spheres between the solid particles and the dispersant, and the HSP distance Ra between the solid particles and water as indicators. Specifically, in the technology described in Patent Document 1, the solid particles and dispersant are selected such that the HSP distance Ra of one type of solid particle that overlaps with the dispersant and Hansen sphere between it and water is the largest among all the solid particles used in the production of the dispersion.

[0016] However, the diameter of the Hansen sphere can vary depending on the choice of solvent and affinity criteria used in HSP calculation. Furthermore, organic solvents can be used as dispersion media in dispersions for manufacturing ceramics and the like. Water has a significantly different HSP value than organic solvents. Therefore, it was difficult to apply the technology described in Patent Document 1 when using solid particles and dispersants in an organic solvent system.

[0017] Dispersants improve the dispersibility of solid particles by adsorbing onto the surface of solid particles and imparting repulsive forces between them. Therefore, it is necessary to select a dispersant that readily adsorbs onto the surface of solid particles. Accordingly, the inventors focused on the affinity between solid particles and dispersants and investigated using the HSP distance Ra between solid particles and dispersants as an indicator.

[0018] As a result of their investigation, the inventors discovered that dispersants with a smaller HSP distance Ra between solid particles and the dispersant are more effective at dispersing solid particles, thus completing the present invention. According to the above method for selecting dispersants, suitable or unsuitable dispersants for dispersing solid particles can be predicted without creating a prototype dispersion, thus reducing the number of trial-and-error steps. Therefore, dispersants can be selected easily. Furthermore, dispersants can be selected regardless of the diameter of the Hansen bulb. The above method for selecting dispersants can be applied to the selection of dispersants for producing dispersions using organic solvents.

[0019] <1-1. Process for selecting a dispersant> In the step of selecting the dispersant, the dispersant is selected based on the distance Ra between the solid particles and the dispersant, which is the Hansen solubility parameter. In other words, the step of selecting the dispersant is a step of determining the dispersant to be used for the production of the dispersion, using Ra between the solid particles and the dispersant as an indicator. The dispersant to be used can be selected from several types of dispersants. A known value for Ra may be used, or if it is unknown, it may be calculated by the step of calculating Ra described later.

[0020] The step of selecting the dispersant may, for example, be a step of selecting a dispersant with a smaller Ra value from among several types of dispersants. The step of selecting the dispersant may also be a step of selecting a dispersant with the smallest Ra value from among several types of dispersants. Alternatively, the step of selecting the dispersant may be a step of selecting a dispersant whose Ra value is below a predetermined reference value. The predetermined reference value can be set according to the purpose (desired state of the dispersion) and is not particularly limited. As just one example, the predetermined reference value is 15 (MPa). 1 / 2 It may also be less than 10 (MPa). 1 / 2 It may also be less than 5 (MPa). 1 / 2 The following may also be used. Note that depending on the dispersant, two HSPs may be obtained. In this case, the Ra calculated using the HSP with the larger δp (i.e., Ra1a, described later) will be used as the indicator.

[0021] The solid particles are not particularly limited and may be organic or inorganic particles. Examples of organic materials include poorly soluble resins and polymers, specifically cellulose, polytetrafluoroethylene (PTFE), polystyrene latex, polypropylene, and polystyrene. Examples of inorganic materials include metals, metalloids, carbon materials, and their oxides, hydroxides, and nitrides, as well as other ceramic raw materials and electrode materials, specifically aluminum, nickel, ferrite, copper, gold, titanium oxide, aluminum oxide (alumina), silica, barium titanate, zirconia, ceria, aluminum hydroxide, silicon nitride, aluminum nitride, carbon nanotubes, graphite, talc, kaolin, and lithium nickel cobalt manganese oxide.

[0022] The average particle size of the solid particles may be, for example, 0.001 to 1000 μm, 0.001 to 100 μm, or 0.001 to 10 μm. Alternatively, the average particle size of the solid particles may be, for example, 0.01 to 1000 μm, 0.01 to 100 μm, or 0.01 to 10 μm. The average particle size can be measured by laser diffraction.

[0023] The dispersant is not particularly limited and may be a surfactant or a wetting agent. The dispersant may be a liquid dispersant at room temperature (25°C), and for suitable use in organic solvent systems, it is preferable to use a non-aqueous dispersant. Examples of non-aqueous dispersants include polymeric dispersants, and it is preferable that the weight-average molecular weight measured by gel permeation chromatography (GPC) is 1,000 to 100,000. Examples of dispersants include polymeric amine-based dispersants and polymeric polycarboxylic acid-based dispersants.

[0024] The dispersion medium is a liquid capable of dispersing solid particles, for example, an organic solvent. The organic solvent is not particularly limited, and examples include alcohol solvents, ether solvents, ester solvents, ketone solvents, amine solvents, amide solvents, aromatic solvents, sulfur atom-containing solvents, and the like. Specific examples of the organic solvent include ethanol, 2-propanol, 1-butanol, 1-pentanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, γ-butyrolactone, acetylacetone, cyclopentanone, cyclohexanone, 1-methylimidazole, dimethyl carbonate, terpineol, dibutyl ether, toluene, mesitylene, tetralin, and the like. As the dispersion medium, one kind may be used alone, or two or more kinds may be mixed and used.

[0025] In addition, as a combination of the solid particles, the dispersant, and the dispersion medium, when Ra between the solid particles and the dispersant is Ra1 and Ra between the dispersion medium and the dispersant is Ra2, a combination satisfying Ra1 < Ra2 is preferable. With such a combination, the method for selecting the dispersant can be preferably applied, and a dispersion liquid in which the solid particles are well dispersed can be obtained.

[0026] As described above, depending on the dispersant, two HSPs may be obtained. In this case, in this specification, Ra1 obtained from the HSP of the dispersant with a larger δp is denoted as Ra1a, Ra2 as Ra2a, Ra1 obtained from the HSP of the other Hansen sphere dispersant with a smaller δp is denoted as Ra1b, and Ra2 as Ra2b.

[0027] Among these four values of Ra (Ra1a, Ra1b, Ra2a, Ra2b), when Ra1a is the smallest, Ra1 = Ra1a, and when Ra2 = Ra2b, a combination that satisfies Ra1 < Ra2 is preferred. When Ra1b is the smallest, Ra1 = Ra1b, and when Ra2 = Ra2a, a combination that satisfies Ra1 < Ra2 is preferred. When Ra2a or Ra2b is the smallest, Ra1 > Ra2, so this combination is not preferred.

[0028] <1-2. Step of calculating Ra> The method for selecting the dispersant may include a step of calculating the distance Ra between the Hansen solubility parameters of the solid particles and the dispersant based on the Hansen solubility parameters of the solid particles and the dispersant before the step of selecting the dispersant.

[0029] As the HSPs of the two substances in the above formula (II), by inputting the HSPs of the solid particles and the dispersant, Ra between the solid particles and the dispersant can be obtained. The HSPs may adopt known values, or if they are unknown, they may be obtained by the step of obtaining HSPs described below.

[0030] The method for selecting the dispersant may also include a step of obtaining Ra between the dispersion medium and the dispersant. Ra between the dispersion medium and the dispersant can be obtained by inputting the HSPs of the dispersion medium and the dispersant as the HSPs of the two substances in the above formula (II).

[0031] <1-3. Step of obtaining HSP> The method for selecting the dispersant may include a step of obtaining the Hansen solubility parameters of the solid particles and the dispersant before the step of calculating the distance Ra between the Hansen solubility parameters.

[0032] The HSP can be determined using the analysis software HSPiP. This analysis software can be obtained, for example, from https: / / www.hansen-solubility.com. First, solid particles or a dispersant are mixed with several types of solvents for which the HSP is known, and the affinity is evaluated. Affinity can be evaluated by solubility, dispersibility, or wettability. Next, based on this evaluation, each solvent is classified into good solvents with high affinity or poor solvents with low affinity, and scored. Then, by inputting this classification result into the analysis software, a Hansen sphere is drawn in a three-dimensional space with coordinate axes δd, δp, and δh, surrounding only the good solvents. The HSP is determined as the center coordinate of the Hansen sphere.

[0033] For example, the affinity between solid particles and solvents can be determined by analyzing the magnetic relaxation curve obtained from pulsed NMR (Nuclear Magnetic Resonance) measurements, specifically by evaluating the Rsp value. A higher Rsp value indicates a solvent with higher affinity for solid particles. For instance, solvents with an Rsp value above a predetermined threshold are classified as good solvents, and those below the threshold are classified as poor solvents. Good solvents are assigned a score of 1, and poor solvents a score of 0. This classification result is then entered into analysis software to determine the Hansen sphere and HSP.

[0034] The HSP of the dispersant can be determined in a similar manner. If the dispersant is in liquid form, for example, a test solution containing the dispersant and solvent is allowed to stand for 24 hours and observed visually. If there is no interface and the test solution does not fluctuate, the score is 1; if there is no interface but the test solution fluctuates, the score is 2; and if there is an interface, the score is 0. Solvents with a score of 1 are classified as good solvents, and solvents with a score of 2 or 0 are classified as poor solvents. This classification result is entered into analysis software to determine the Hansen sphere and HSP.

[0035] Examples of solvents include organic solvents, and the organic solvents are not particularly limited, but include alcohol-based solvents, ether-based solvents, ester-based solvents, ketone-based solvents, amine-based solvents, amide-based solvents, aromatic solvents, and sulfur atom-containing solvents. Specific examples of organic solvents include ethanol, 1-propanol, 2-propanol, 1-butanol, 1-pentanol, diethylene glycol, diacetone alcohol, cyclohexanol, acetic acid, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether, ethanolamine, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, γ-butyrolactone, acetone, acetylacetone, cyclopentanone, cyclohexanone, 1-methylimidazole, acetonitrile, dimethyl carbonate, ethyl acetate, butyl acetate, tetrahydrofuran, 1,4-dioxane, terpineol, chloroform, dichloromethane, dibutyl ether, toluene, chlorobenzene, mesitylene, methyl benzoate, benzyl benzoate, and tetralin. It is preferable to use 10 or more types of solvents, and more preferably 20 or more types.

[0036] [2. Method for producing the dispersion] A method for producing a dispersion according to one embodiment of the present invention includes the steps of selecting a dispersant by the dispersant selection method described above, and mixing the selected dispersant, solid particles, and a dispersion medium to produce a dispersion. By the dispersant selection method described above, a dispersant that can disperse solid particles well can be easily selected, and therefore a uniform dispersion can be easily produced. Matters already explained in [1. Dispersant Selection Method] can be referred to therein, so their explanation will be omitted below.

[0037] The method for producing the dispersion may include a step of selecting a dispersion medium based on the HSP distance Ra between the solid particles and the dispersant and the HSP distance Ra between the dispersion medium and the dispersant. Further, the method for producing the dispersion may include a step of calculating the HSP distance Ra between the dispersion medium and the dispersant. For example, as described above, when Ra1 is the Ra between the solid particles and the dispersant and Ra2 is the Ra between the dispersion medium and the dispersant, it is preferable to select the dispersion medium so as to satisfy Ra1 < Ra2. The selection method in the case where the dispersant has two HSPs is as described above.

[0038] The obtained dispersion can be used, for example, in the production of ceramics, electrodes, etc. Therefore, for example, a method for producing ceramics including a step of producing a dispersion by the above-described method for producing a dispersion and a step of producing ceramics by firing the produced dispersion is also included in an embodiment of the present invention. Alternatively, the obtained dispersion may be subjected to analysis as described later.

[0039] 〔3. Method for Analyzing Dispersion〕 The method for analyzing the dispersion according to an embodiment of the present invention includes a step of producing a dispersion by the above-described method for producing a dispersion and a step of analyzing the produced dispersion. By the above-described method for producing a dispersant, a uniform dispersion can be easily produced, and by using such a uniform dispersion, various analyses can be easily performed. Regarding the matters already described in 〔1. Method for Selecting Dispersant〕 and 〔2. Method for Producing Dispersion〕, the description thereof can be incorporated, and thus the description thereof will be omitted below.

[0040] Examples of the items to be analyzed include the particle size distribution of solid particles, evaluation of the affinity of solid particles, evaluation of the sedimentation characteristics of solid particles, etc. Examples of the analysis method for the particle size distribution of solid particles include, for example, laser diffraction / scattering method, dynamic light scattering method, ultrasonic method, sedimentation method, etc.

[0041] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0042] One embodiment of the present invention may include the following configuration: <1> A method for selecting a dispersant to obtain a dispersion by mixing solid particles, a dispersant, and a dispersion medium, the method comprising the step of selecting the dispersant based on the distance Ra between the Hansen solubility parameters of the solid particles and the dispersant. <2> Prior to the step of selecting the dispersant, the process includes calculating the distance Ra between the Hansen solubility parameters of the solid particles and the dispersant based on the Hansen solubility parameters of the solid particles and the dispersant. <1> The method for selecting a dispersant as described above. <3> The process includes, before calculating the distance Ra between Hansen solubility parameters, obtaining the Hansen solubility parameters of the solid particles and the dispersant. <2> The method for selecting a dispersant as described above. <4> <1> ~ <3> A method for producing a dispersion, comprising the steps of: selecting a dispersant according to the method for selecting a dispersant described in any one of the above; and mixing the selected dispersant, solid particles, and a dispersion medium to produce a dispersion. <5> <4> A method for analyzing a dispersion, comprising the steps of: producing a dispersion by the method for producing a dispersion described in [the relevant document]; and analyzing the produced dispersion. [Examples]

[0043] One embodiment of the present invention is described below.

[0044] [Example 1] <1. Obtaining HSP from aluminum oxide> <Affinity Test> A powder sample (aluminum oxide, particle size 1 μm) was placed in a sample tube and mixed with a solvent to prepare a mixture solution with a powder sample concentration of 5% by mass.

[0045] As solvents, ethanol, 1-propanol, 1-pentanol, diacetone alcohol, cyclohexanol, acetic acid, ethanolamine, N,N-dimethylformamide, dimethyl sulfoxide, acetone, acetonitrile, ethyl acetate and toluene were used.

[0046] <Pulse NMR measurement> Only the solvent was put into a sample tube and sealed, and pulse NMR measurement was performed. Separately, the above-mentioned mixed solution was put into a sample tube and sealed, and pulse NMR measurement was performed. The pulse NMR measurement conditions are as described below.

[0047] <Pulse NMR measurement conditions> · Apparatus: Acorn area (manufactured by Xigo nanotool) · Observed nucleus: 1H nucleus (resonance frequency 13 MHz) · Pulse sequence: CPMG method (T2 measurement) · Measurement temperature: 25 °C · Number of repetitions: · Solvent: 4 times · Mixed solution: 4 times.

[0048] <Obtaining the affinity index (Rsp value)> From the magnetic relaxation curve obtained by the pulse NMR measurement of only the solvent, the relaxation time (Tb) of the solvent alone was obtained. Also, from the magnetic relaxation curve obtained by the pulse NMR measurement of the mixed solution, the relaxation time (Ts) of the mixed solution was obtained.

[0049] Using the two relaxation times obtained above, the Rsp value was calculated from the following formula. Rsp value = [(Tb - Ts) / Ts] The higher the Rsp value of the solvent, the higher the affinity of the solvent for the powder sample. The measurement results are shown in Table 1.

[0050] <HSP analysis> The solvents with high and low obtained Rsp values were classified as good solvents and poor solvents, respectively. In this example, solvents with an Rsp value of 0.34 or more were determined as good solvents, and solvents with an Rsp value of less than 0.34 were determined as poor solvents.

[0051] The solvent classification results were input using analysis software (HSPiP version 5.4.01). The classification results were entered with a score of 1 for good solvents and a score of 0 for poor solvents. HSP (δd, δp, δh) and the radius of the Hansen sphere (R) were then analyzed. The analysis results are shown in Table 2.

[0052] [Table 1]

[0053] [Table 2]

[0054] <2. Obtaining HSP (High-Speed ​​Specification) for Dispersants> <Affinity Test> A test tube containing 0.2 mL of dispersant was mixed with 0.05 mL of solvent to create the test solution, which was then closed and left to stand at room temperature for 27 hours.

[0055] The following dispersants were used: Dispersant 1 (Marialim® SC-0505K, manufactured by NOF Corporation, a high-molecular-weight polycarboxylic acid-based dispersant), Dispersant 2 (Marialim® SC-0708A, manufactured by NOF Corporation, a high-molecular-weight polycarboxylic acid-based dispersant), Dispersant 3 (Marialim® SC-1015F, manufactured by NOF Corporation, a high-molecular-weight polycarboxylic acid-based dispersant), Dispersant 4 (Esream® AD-3172M, manufactured by NOF Corporation, a high-molecular-weight amine-based dispersant), and Dispersant 5 (Esream® AD-374M, manufactured by NOF Corporation, a high-molecular-weight amine-based dispersant).

[0056] The solvents used included ethanol, 2-propanol, diethylene glycol, diacetone alcohol, N,N-dimethylformamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, γ-butyrolactone, acetone, butyl acetate, tetrahydrofuran, 1,4-dioxane, chloroform, dichloromethane, dibutyl ether, toluene, chlorobenzene, methyl benzoate, benzyl benzoate, and tetralin.

[0057] The state of the test solution after standing for 27 hours was visually confirmed. The state of the test solution was classified into the following three categories. · Score 1: There is no interface between the dispersant and the solvent, and the test solution has no fluctuation. · Score 2: There is no interface between the dispersant and the solvent, but the test solution has fluctuations. · Score 0: There is an interface between the dispersant and the solvent.

[0058] The confirmation results are shown in Table 3.

[0059]

Table 3

[0060] <HSP Analysis> Among the confirmation results, the solvent with a score of 1 was determined as a good solvent, and the solvents with scores of 2 and 0 were determined as poor solvents. Using analysis software (HSPiP version 5.4.01), the classification results of the solvents were input and the HSP was analyzed. The analysis results are shown in Table 4.

[0061]

Table 4

[0062] Note that for dispersants 1, 2, and 3, two HSPs were obtained. Among the two HSPs, the larger δp value was 10 or more, and the smaller δp value was 5 or less.

[0063] <3. Evaluation of Affinity between Solid Particles and Dispersant> Dispersant solutions in which the above-mentioned dispersants 1 to 5 were dissolved in ethanol were respectively prepared. A powder sample (aluminum oxide) was put into a sample tube and mixed with the dispersant solution so that the powder sample concentration became 5% by mass to obtain a mixed solution.

[0064] <Pulse NMR Measurement> A sample tube containing only the dispersant solution was sealed, and pulsed NMR measurements were performed. Separately, a sample tube containing the mixed solution was sealed, and pulsed NMR measurements were also performed. The pulsed NMR measurement conditions are as follows.

[0065] <Pulsed NMR Measurement Conditions> • Equipment: Acorn area (manufactured by Xigo nanotool) Observed nucleus: 1H nucleus (resonance frequency 13MHz) • Pulse sequence: CPMG method (T2 measurement) ·Measurement temperature: 25℃ • Number of repetitions: • Dispersant solution: 3 times ·Mixture: 3 times.

[0066] <Obtaining the affinity index (Rsp value)> The relaxation time (Tb) of the dispersant solution was obtained from the magnetic relaxation curve obtained by pulsed NMR measurement of the dispersant solution alone. The relaxation time (Ts) of the mixture was also obtained from the magnetic relaxation curve obtained by pulsed NMR measurement of the mixture.

[0067] Using the two relaxation times obtained above, the Rsp value was calculated from the following formula. Rsp value = [(Tb-Ts) / Ts] A higher Rsp value indicates that the dispersant is better dispersed in the mixture. The measurement results are shown in Table 5.

[0068] [Table 5]

[0069] <4. Calculation of Ra> The Ra values ​​between each compound were calculated using the HSP values ​​of the solid particles, the dispersant, and the dispersion medium obtained above. In this example, ethanol was used as the dispersion medium. The HSP value of ethanol is known (δd: 15.8 (MPa)). 1 / 2 δp: 8.8 (MPa) 1 / 2 δh: 19.4 (MPa) 1 / 2)。

[0070] The Ra values for each dispersant with respect to the solid particles and the Ra values for each dispersant with respect to the dispersion medium are shown in Table 6 together with the Rsp values obtained from the above-mentioned affinity evaluation of the solid particles and the dispersant. The Ra for each dispersant with respect to the solid particles is denoted as Ra1, and the Ra for each dispersant with respect to the dispersion medium is denoted as Ra2. For dispersants 1 to 3 for which two HSPs were obtained, the Ra based on each HSP was calculated for both Ra1 and Ra2. The Ra1 obtained from the HSP of the dispersant with the larger δp is denoted as Ra1a, and Ra2 as Ra2a, and the Ra1 obtained from the HSP of the dispersant with the smaller δp is denoted as Ra1b, and Ra2 as Ra2b.

[0071]

Table 6

[0072] The plots of Ra (Ra1a for dispersants 1 to 3, Ra1 for dispersants 4 and 5) between the solid particles and the Rsp values are shown in Fig. 1. From Fig. 1, it can be seen that the smaller the Ra (Ra1a for dispersants 1 to 3, Ra1 for dispersants 4 and 5) between the solid particles and the dispersant, the higher the tendency of the Rsp value. That is, it can be understood that the smaller the Ra between the solid particles and the dispersant, the higher the affinity of the dispersant for the solid particles, and the better the solid particles are dispersed in the mixed solution.

[0073] Also, from Table 6, it can be seen that for dispersants 4 and 5, Ra1 < Ra2. Also, for all of dispersants 1 to 3, among Ra1a, Ra2a, Ra1b, and Ra2b, Ra1a was the smallest. For dispersants 1 to 3, it can be seen that Ra1a < Ra2b. Therefore, it was suggested that when using a dispersant with one HSP, a dispersion medium that satisfies Ra1 < Ra2 is suitable, and when using a dispersant with two HSPs and Ra1a is the smallest, a dispersion medium that satisfies Ra1a < Ra2b is suitable.

[0074] [Example 2] <1. Evaluation of Affinity between Solid Particles and Dispersant> Dispersant solutions were prepared by dissolving each of the above dispersants 1 to 5 in ethanol. A powder sample (aluminum oxide, particle size 0.3 μm) was placed in a sample tube and mixed with the dispersant solution to obtain a powder sample concentration of 20% by mass.

[0075] <Pulsed NMR Measurement> Pulsed NMR measurements were performed under the conditions described in section 3 of Example 1.

[0076] <Obtaining the affinity index (Rsp value)> The Rsp value was calculated using the method described in section 3 of Example 1. The measurement results are shown in Table 7.

[0077] [Table 7]

[0078] <2. Calculation of Ra> Similar to step 4 of Example 1, the Ra values ​​between each compound were calculated using the HSP values ​​of the solid particles, the dispersant, and the dispersion medium. These values, along with the Rsp values ​​obtained from the affinity evaluation of the solid particles and dispersant described above, are shown in Table 8.

[0079] [Table 8]

[0080] Figure 2 shows a plot of Ra (Ra1a for dispersants 1-3, Ra1 for dispersants 4 and 5) and Rsp value between the solid particles and the dispersant. Similar to Figure 1, it can be seen that dispersants with smaller Ra values ​​tend to have higher Rsp values. In other words, even when the particle size of the solid particles is smaller than in Example 1, dispersants with smaller Ra values ​​are dispersants with higher affinity for solid particles and disperse the solid particles well in the mixture.

[0081] [Example 3] <1. Evaluation of affinity between solid particles and dispersants> Dispersant solutions were prepared by dissolving each of the above dispersants 1 to 5 in ethanol. Powdered samples (aluminum oxide, particle size 0.02 to 0.05 μm) were placed in sample tubes and mixed with the dispersant solutions to obtain a powdered sample concentration of 20% by mass.

[0082] <Pulsed NMR Measurement> Pulsed NMR measurements were performed under the measurement conditions described in section 3 of Example 1.

[0083] <Obtaining the affinity index (Rsp value)> The Rsp value was calculated using the method described in section 3 of Example 1. The measurement results are shown in Table 9.

[0084] [Table 9]

[0085] <2. Calculation of Ra> Similar to step 4 of Example 1, the Ra values ​​between each compound were calculated using the HSP values ​​of the solid particles, the dispersant, and the dispersion medium. These values, along with the Rsp values ​​obtained from the affinity evaluation of the solid particles and dispersant described above, are shown in Table 10.

[0086] [Table 10]

[0087] Figure 3 shows a plot of Ra (Ra1a for dispersants 1-3, Ra1 for dispersants 4 and 5) and Rsp value between the solid particles and the dispersant. Similar to Figures 1 and 2, it can be seen that dispersants with smaller Ra values ​​tend to have higher Rsp values. In other words, even when the particle size of the solid particles is smaller than that of Example 1 and Example 2, dispersants with smaller Ra values ​​are dispersants with higher affinity for solid particles and disperse the solid particles well in the mixed liquid.

[0088] The mixture, in which the affinity between solid particles and dispersants was evaluated, was diluted 20-fold with ethanol. This diluted solution was placed in a measurement cell, sealed, and the particle size distribution was measured using a LUMiSizer (LUM Corporation). When using dispersant 1, which had the lowest Ra1, the median diameter (D50) of the solid particle aggregates was 0.14 μm.

[0089] [Example 4] <1. Obtaining HSP (High-Speed ​​Species) of Barium Titanate> <Affinity Test> A powder sample (barium titanate, particle size 0.1 μm) was placed in a sample tube and mixed with a solvent to prepare a mixture solution with a powder sample concentration of 15% by mass.

[0090] The solvents used included ethanol, 2-propanol, 1-butanol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether, N-methylformamide, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, γ-butyrolactone, acetylacetone, cyclopentanone, cyclohexanone, 1-methylimidazole, dimethyl carbonate, dibutyl ether, mesitylene, and tetralin.

[0091] <Pulsed NMR Measurement> A sample tube containing only the solvent was sealed, and pulsed NMR measurements were performed. Separately, the aforementioned mixture was placed in a sample tube, sealed, and pulsed NMR measurements were also performed. The pulsed NMR measurement conditions are as follows.

[0092] <Pulsed NMR Measurement Conditions> The conditions are the same as those described in <1. Acquisition of HSP of aluminum oxide> of Example 1, except that the number of times the solvent and mixture are repeated is three.

[0093] <Obtaining the affinity index (Rsp value)> The Rsp value was calculated using the method described in section 1 of Example 1. The measurement results are shown in Table 11.

[0094] <HSP Analysis> The solvents with high and low obtained Rsp values were classified as good solvents and poor solvents, respectively. In this example, solvents with an Rsp value of 1.47 or more were determined as good solvents, and solvents with an Rsp value of less than 1.47 were determined as poor solvents.

[0095] In the same manner as in 1. of Example 1, the classification results of the solvents were analyzed. The analysis results are shown in Table 12.

[0096]

Table 11

[0097]

Table 12

[0098] <2. Evaluation of Affinity between Solid Particles and Dispersant> Dispersant solutions in which the above dispersants 1 to 5 were dissolved in ethanol were each prepared. A powder sample (barium titanate, particle size 0.1 μm) was placed in a test tube and mixed with the dispersant solution so that the powder sample concentration became 20% by mass to obtain a mixed solution.

[0099] <Pulse NMR Measurement> Pulse NMR measurement was performed under the conditions described in 3. of Example 1.

[0100] <Obtaining Affinity Index (Rsp Value)> The Rsp value was calculated by the method described in 3. of Example 1. The measurement results are shown in Table 13.

[0101]

Table 13

[0102] <3. Calculation of Ra> Similar to step 4 of Example 1, the Ra values ​​between each compound were calculated using the HSP values ​​of the solid particles, the dispersant, and the dispersion medium. These values, along with the Rsp values ​​obtained from the affinity evaluation of the solid particles and dispersant described above, are shown in Table 14.

[0103] [Table 14]

[0104] Figure 4 shows a plot of Ra (Ra1a for dispersants 1-3, Ra1 for dispersants 4 and 5) and Rsp value between the solid particles and the dispersant. Similar to Figure 1, it can be seen that dispersants with smaller Ra values ​​tend to have higher Rsp values. In other words, even if the solid particles are barium titanate, dispersants with smaller Ra values ​​have a higher affinity for the solid particles and disperse the solid particles well in the mixture.

[0105] [Example 5] <1. Evaluation of affinity between solid particles and dispersants> Dispersant solutions were prepared by dissolving each of the above dispersants 1 to 5 in acetone. A powder sample (barium titanate, particle size 0.1 μm) was placed in a sample tube and mixed with the dispersant solution to obtain a powder sample concentration of 20% by mass.

[0106] <Pulsed NMR Measurement> Pulsed NMR measurements were performed under the conditions described in section 3 of Example 1.

[0107] <Obtaining the affinity index (Rsp value)> The Rsp value was calculated using the method described in section 3 of Example 1. The measurement results are shown in Table 15.

[0108] [Table 15]

[0109] <2. Calculation of Ra> Similar to step 3 of Example 4, the Ra values ​​between each compound were calculated using the HSP values ​​of the solid particles, the dispersant, and the dispersion medium obtained above. In this example, acetone was used as the dispersion medium. The HSP value of acetone is known (δd: 15.5 (MPa)). 1 / 2 δp: 10.4 (MPa) 1 / 2 δh:7.0(MPa) 1 / 2 ). The Rsp values ​​obtained from the affinity evaluation of the solid particles and dispersant described above are shown in Table 16.

[0110] [Table 16]

[0111] Figure 5 shows a plot of Ra (Ra1a for dispersants 1-3, Ra1 for dispersants 4 and 5) and Rsp value between solid particles and the dispersant. Similar to Figure 4, it can be seen that dispersants with smaller Ra values ​​tend to have higher Rsp values. In other words, even when acetone is used as the dispersion medium, dispersants with smaller Ra values ​​between solid particles and the dispersant have a higher affinity for the solid particles and disperse the solid particles well in the mixture.

[0112] [Example 6] Dispersant solutions were prepared by dissolving each of the above dispersants 1 to 5 in N,N-dimethylformamide. A powder sample (barium titanate, particle size 0.1 μm) was placed in a sample tube and mixed with the dispersant solution to obtain a powder sample concentration of 20% by mass.

[0113] <Pulsed NMR Measurement> Pulsed NMR measurements were performed under the conditions described in section 3 of Example 1.

[0114] <Obtaining the affinity index (Rsp value)> The Rsp value was calculated using the method described in section 3 of Example 1. The measurement results are shown in Table 17.

[0115] [Table 17]

[0116] <2. Calculation of Ra> Similar to step 3 of Example 4, the Ra values ​​between each compound were calculated using the HSP values ​​of the solid particles, the dispersant, and the dispersion medium obtained above. In this example, N,N-dimethylformamide was used as the dispersion medium. The HSP value of N,N-dimethylformamide is known (δd: 17.4 (MPa)). 1 / 2 δp: 13.7 (MPa) 1 / 2 δh: 11.3 (MPa) 1 / 2 ). The Rsp values ​​obtained from the affinity evaluation of the solid particles and dispersant described above are shown in Table 18.

[0117] [Table 18]

[0118] Figure 6 shows a plot of Ra (Ra1a for dispersants 1-3, Ra1 for dispersants 4 and 5) and Rsp value between solid particles and dispersants. Similar to Figure 4, it can be seen that dispersants with smaller Ra values ​​tend to have higher Rsp values. In other words, even when N,N-dimethylformamide is used as the dispersion medium, dispersants with smaller Ra values ​​have a higher affinity for solid particles and disperse the solid particles well in the mixture.

[0119] [Example 7] <1. Evaluation of affinity between solid particles and dispersants> Dispersant solutions were prepared by dissolving each of the above dispersants 1 to 5 in ethanol. A powder sample (barium titanate, particle size 3 μm) was placed in a sample tube and mixed with the dispersant solution to obtain a powder sample concentration of 20% by mass.

[0120] <Pulsed NMR Measurement> Pulsed NMR measurements were performed under the conditions described in section 3 of Example 1.

[0121] <Obtaining the affinity index (Rsp value)> The Rsp value was calculated using the method described in section 3 of Example 1. The measurement results are shown in Table 19.

[0122] [Table 19]

[0123] <2. Calculation of Ra> Similar to step 3 of Example 4, the Ra values ​​between each compound were calculated using the HSP values ​​of the solid particles, the dispersant, and the dispersion medium obtained above. Since the solid particles were the same as those in Example 4, the HSP values ​​for the solid particles were taken from Table 12. These values, along with the Rsp values ​​obtained from the affinity evaluation of the solid particles and dispersant described above, are shown in Table 20.

[0124] [Table 20]

[0125] Figure 7 shows a plot of Ra (Ra1a for dispersants 1-3, Ra1 for dispersants 4 and 5) and Rsp value between solid particles and the dispersant. Similar to Figure 4, it can be seen that dispersants with smaller Ra values ​​tend to have higher Rsp values. In other words, even when the particle size of the solid particles is large, dispersants with smaller Ra values ​​have a higher affinity for the solid particles and disperse the solid particles well in the mixture.

[0126] Examples 1-7 demonstrate that, regardless of the particle size and type of solid particles, as well as the type of dispersion medium, dispersants with lower Ra values ​​tend to have higher Rsp values, indicating better dispersion of solid particles in the mixed solution. It is suggested that by obtaining the HSP of the solid particles and dispersant and determining their Ra values, the optimal dispersant can be selected without having to fabricate a dispersion solution. [Industrial applicability]

[0127] One aspect of the present invention can be used, for example, in the production and analysis of dispersions.

Claims

1. A method for selecting a dispersant to obtain a dispersion by mixing solid particles, a dispersant, and a dispersion medium, A method for selecting a dispersant, comprising the step of selecting the dispersant based on the distance Ra between the Hansen solubility parameters of the solid particles and the dispersant.

2. A method for selecting a dispersant according to claim 1, further comprising the step of calculating the distance Ra between the Hansen solubility parameters of the solid particles and the dispersant based on the Hansen solubility parameters of the solid particles and the dispersant, prior to the step of selecting the dispersant.

3. The method for selecting a dispersant according to claim 2, further comprising the step of obtaining the Hansen solubility parameters of the solid particles and the dispersant before the step of calculating the distance Ra between the Hansen solubility parameters.

4. A step of selecting a dispersant by the method for selecting a dispersant described in any one of claims 1 to 3, A method for producing a dispersion, comprising the steps of mixing the selected dispersant, solid particles, and dispersion medium to produce a dispersion.

5. A step of producing a dispersion by the method for producing a dispersion according to claim 4, A method for analyzing a dispersion, comprising the step of analyzing the manufactured dispersion.

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