Metal oxide particle dispersant and dispersion

Abstract

The present application provides a dispersant for metal oxide particles, which can disperse metal oxide particles well. The dispersant for metal oxide particles of the present application is a dispersant used for dispersing metal oxide particles, which contains a compound represented by the following general formula (1) (in formula (1), R 1 represents an alkylene group, m is a number from 2 to 7, and n is a number from 1 to 7). The dispersant for metal oxide particles of the present application can disperse metal oxide particles well.

Description

Technical Field

[0001] The present invention relates to a dispersant for dispersing metal oxide particles and a dispersion containing the dispersant. Background Technology

[0002] Metal oxide particles possess unique properties not found in organic polymer particles, making them highly useful materials as various additives or fillers. Typical characteristics of metal oxide particles include high refractive index, photocatalytic activity, strength, and transparency. By incorporating metal oxide particles with these properties into materials such as resins, new properties can be imparted to those materials. Therefore, from the perspective of creating new functional materials, metal oxide particles are of extremely high value.

[0003] It is known that the various properties of the aforementioned metal oxide particles are strongly dependent on their particle size, especially in the realm of so-called metal oxide nanoparticles with a particle size of nanometers, where new functions not seen at the micrometer scale can be exhibited. Therefore, in recent years, functional materials utilizing metal oxide particles in the nanometer size region have been actively developed.

[0004] On the other hand, when the particle size of the metal oxide particles is in the region of the aforementioned nanoparticle size, particle aggregation is prone to occur due to the increase in specific surface area, especially in liquids such as solvents, where this aggregation becomes significant. From this perspective, it is particularly important to construct techniques that enable metal oxide particles in solvents to be dispersed to a higher degree. For example, Patent Document 1 discloses a technique that uses a dispersant containing a compound having a specific structure to disperse zirconia particles in a dispersion medium. According to this technique, even zirconia particles of nanoscale size can be dispersed.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2012-007144 Summary of the Invention

[0008] The technical problem that the invention aims to solve

[0009] In recent years, there has been a demand for significantly improved dispersibility to better utilize the superior properties of metal oxide particles. By suppressing the aggregation of metal oxide particles and further enhancing dispersibility, the inherent properties of metal oxide particles can be significantly realized. For example, materials incorporating highly dispersible metal oxide particles can be expected to exhibit higher refractive indices and further enhance properties such as transparency. From this perspective, there is a strong need to develop a dispersant capable of highly dispersing metal oxide particles.

[0010] The present invention was made in view of the above circumstances, and its object is to provide a dispersant for metal oxide particles that can effectively disperse metal oxide particles. Furthermore, the object of the present invention is to provide a dispersion in which the metal oxide particles exhibit excellent dispersibility, and which can form a cured product possessing both good transparency and a good refractive index.

[0011] Technical means for solving problems

[0012] In order to achieve the above-mentioned objectives, the inventors conducted in-depth research and discovered that the above-mentioned objectives could be achieved by applying compounds with specific structures, thus completing the present invention.

[0013] That is, the present invention includes the subject matter described, for example, the following items.

[0014] Project 1:

[0015] A dispersant for metal oxide particles, which is used to disperse metal oxide particles.

[0016] The above dispersant contains a compound represented by the following general formula (1).

[0017] [Chemistry 1]

[0018]

[0019] (In equation (1), R) 1 (This indicates an alkylene group, where m is a number from 2 to 7 and n is a number from 1 to 7).

[0020] Project 2:

[0021] As described in Project 1, for dispersants of metal oxide particles, wherein, in formula (1) above, R 1 It is an alkylene group having 1 to 6 carbon atoms.

[0022] Project 3:

[0023] A dispersion comprising: the dispersant for metal oxide particles described in item 1 or 2, metal oxide particles, and an acrylic compound.

[0024] Invention Effects

[0025] The dispersant for metal oxide particles of the present invention enables the metal oxide particles to be well dispersed.

[0026] The dispersion of the present invention exhibits excellent dispersibility of metal oxide particles, and the dispersion is capable of forming a cured product with both good transparency and good refractive index. Detailed Implementation

[0027] The embodiments of the present invention will be described in detail below. It should be noted that in this specification, the expressions "containing" and "comprising" include the concepts of "containing", "comprising", "substantially composed of", and "composed solely of".

[0028] 1. Dispersants for metal oxide particles

[0029] The dispersant for metal oxide particles of the present invention contains a compound represented by the following general formula (1).

[0030] [Chemistry 2]

[0031]

[0032] Here, in equation (1), R 1 This indicates an alkylene group, where m is a number from 2 to 7 and n is a number from 1 to 7.

[0033] The dispersant for metal oxide particles of the present invention (hereinafter, sometimes simply referred to as "the dispersant of the present invention") contains the above-described compound, thereby possessing the property of effectively dispersing metal oxide particles. Therefore, the dispersant of the present invention is suitable as a raw material for forming the dispersion described later, and is particularly suitable as a dispersant for dispersing metal oxide particles. Because this dispersion contains the dispersant for metal oxide particles of the present invention and metal oxide particles, the metal oxide particles exhibit excellent dispersibility, are less prone to precipitation, and have high transparency.

[0034] In particular, the dispersion of the present invention exhibits excellent dispersibility even with increased solids concentration of the metal oxide particles, and is not prone to viscosity increase, thus resulting in excellent operability. Furthermore, since the solids concentration of the metal oxide particles can be increased, the function of the metal oxide particles can be more effectively utilized.

[0035] In equation (1) above, R 1 It can be a straight-chain alkylene group or a branched alkylene group, preferably a straight-chain alkylene group.

[0036] In the above equation (1), as R 1The number of carbon atoms in the alkylene group is not particularly limited. From the viewpoint of easily improving the dispersibility of metal oxide particles, for example, R in formula (1) above... 1 Preferably, it is an alkylene group having 1 to 6 carbon atoms (more than 1 and less than 6). R in formula (1) above... 1 More preferably, it is an alkylene group having 2 or more carbon atoms; furthermore, it is more preferably an alkylene group having 5 or fewer carbon atoms; even more preferably, it is an alkylene group having 4 or fewer carbon atoms; and particularly preferably, it is an alkylene group having 3 or fewer carbon atoms.

[0037] As R 1 Specific examples include: -CH2-, -(CH2)2-, -(CH2)3-, -(CH2)4-.

[0038] In the above formula (1), m is a number between 2 and 7, that is, a number greater than 2 and less than 7. When m is less than 2, the dispersion performance of the metal oxide particles may decrease. In addition, when m is greater than 7, the dispersion performance of the metal oxide particles may decrease. m is preferably 3 or more, and more preferably 6 or less. m can be an integer or a decimal.

[0039] In the above formula (1), there is no particular limitation on the method of adjusting the value of m. For example, it can be adjusted by appropriately selecting the type of raw material (cyclic ester compound, etc.) used in the manufacture of the compound shown in formula (1).

[0040] In equation (1) above, n refers to "-(CH2)". m The repeating unit of the "-COO-" part, more specifically, is the number-average repeating unit. In other words, n refers to the number-average degree of polymerization of the compound shown in equation (1).

[0041] n is a number from 1 to 7, that is, a number greater than 1 and less than 7. When n is less than 1, the dispersion performance of the metal oxide particles may decrease. Furthermore, when n is greater than 7, the dispersion performance of the metal oxide particles may decrease. n is preferably 6 or less, more preferably 5 or less, even more preferably 4 or less, and particularly preferably 3 or less. n can be an integer or a decimal. The value of n can be determined by the compound shown in formula (1). 1 Estimation is made using H-NMR spectroscopy.

[0042] In the above formula (1), there is no particular limitation on the method of adjusting the value of n. For example, it can be adjusted by appropriately selecting the ratio of each raw material (cyclic ester compound and fatty acid) used in the manufacture of the compound shown in formula (1).

[0043] There is no particular limitation on the method of manufacturing the compound shown in formula (1) above. For example, the compound shown in formula (1) above can be manufactured by reacting a cyclic ester compound with a fatty acid.

[0044] Examples of the cyclic ester compounds described above include compounds represented by the general formula (2).

[0045] [Chemistry 3]

[0046]

[0047] In formula (2), m is synonymous with formula (1) above. The compound represented by formula (2) above is -(CH2). m - A cyclic compound bonded to an ester.

[0048] Examples of compounds represented by formula (2) above include ε-caprolactone and γ-butyrolactone.

[0049] Examples of the aforementioned fatty acids include, for instance, saturated fatty acids with a phenyl group at the terminal end. Specifically, ph-R can be listed as an example. 1 -COOH represents fatty acids. Here, in ph-R 1 In -COOH, "ph" refers to phenyl (-C6H5-), R 1 An example can be found in R in equation (1) above. 1 The same alkylene group. Examples of fatty acids include 3-phenylpropionic acid.

[0050] When the compound shown in formula (1) is prepared by reacting the above-mentioned cyclic ester compound with the above-mentioned fatty acid, the reaction conditions are not particularly limited. For example, commonly known reaction conditions such as ring-opening polymerization and dehydration reaction can be widely used. In this reaction, catalysts, water, etc., can be used as needed. As a catalyst, p-toluenesulfonic acid can be used. The amount of catalyst and water is not particularly limited and can be set to, for example, the amount of catalyst. In the purification after the reaction, an alkali such as sodium hydroxide can be used. The reaction temperature and reaction temperature in the ring-opening polymerization and dehydration reaction are also not particularly limited and can be set to be the same as those in commonly known reactions.

[0051] The dispersant of the present invention may contain other components besides the compound shown in formula (1) above, or it may consist only of the compound shown in formula (1) above. The dispersant of the present invention preferably contains 90% by mass or more of the compound shown in formula (1) above, more preferably 95% by mass or more, and even more preferably 99% by mass or more.

[0052] The dispersant of the present invention enables the good dispersion of metal oxide particles. Examples of metal oxide particles include those contained in the dispersions described below, with particular suitability for the dispersion of zirconia, titanium dioxide, and the like.

[0053] The dispersant of the present invention can effectively disperse metal oxide particles in various solvents. Among them, acrylic compounds described later are preferably used as solvents.

[0054] When using the dispersant of the present invention to disperse metal oxide particles, for example, the amount of dispersant relative to 100 parts by mass of metal oxide particles can be set to 0.5 to 30 parts by mass, preferably 1 to 20 parts by mass, more preferably 3 to 18 parts by mass, further preferably 5 to 16 parts by mass, and particularly preferably 6 to 12 parts by mass.

[0055] 2. The dispersion and the solidified product of the dispersion.

[0056] The dispersion of the present invention comprises: the above-mentioned dispersant for metal oxide particles, metal oxide particles, and an acrylic compound. Because this dispersion contains the dispersant of the present invention, the metal oxide particles exhibit excellent dispersibility.

[0057] (Metal oxide particles)

[0058] In metal oxide particles, the type of metal can be, for example, selected from a group consisting of metal elements belonging to the 4th, 5th and 6th periods of the periodic table (IUPAC 1991), preferably metal elements from groups 2 to 14.

[0059] More specifically, the metallic elements constituting the metal oxide particles are preferably metals that impart a high refractive index when the metal oxide is formed. Specific examples of metals include zirconium, titanium, tin, antimony, zinc, cerium, indium, and yttrium.

[0060] Specific examples of metal oxide particles include: zirconium oxide, titanium oxide, tin oxide, antimony pentoxide, zinc oxide, cerium oxide, tin-doped indium oxide, antimony-doped tin oxide, yttrium oxide, etc., with zirconium oxide, titanium oxide, and tin oxide being preferred, zirconium oxide and titanium oxide being more preferred, and zirconium oxide being particularly preferred.

[0061] In the dispersion of the present invention, the size of the metal oxide particles is not particularly limited as long as it does not reduce the dispersibility. For example, the D50 volume average particle size of the metal oxide particles is preferably 1 nm or more, more preferably 2 nm or more, further preferably 3 nm or more, particularly preferably 5 nm or more, and preferably 1000 nm or less, more preferably 100 nm or less, further preferably 50 nm or less, and particularly preferably 30 nm or less. The D50 volume average particle size of the metal oxide particles refers to the particle size at the point where the volume cumulative distribution reaches 50% in the particle size distribution curve. The D50 volume average particle size of the metal oxide particles is determined using a dynamic light scattering (DLS) particle size distribution measuring device (Nanotrac Wave II). Values ​​measured by (Bell Manufacturing).

[0062] The shape of the metal oxide particles is not particularly limited; for example, they can be formed into the same shape as commonly known metal oxide particles.

[0063] Metal oxide particles can be obtained, for example, from commercially available products in the form of powder or dispersion. Furthermore, metal oxide particles can also be manufactured using, for example, commonly known manufacturing methods.

[0064] (Acrylic compounds)

[0065] The acrylic compounds contained in the dispersion of the present invention function as a dispersion medium for the metal oxide particles. Furthermore, because the acrylic compounds are polymerizable, they can also be components that can be polymerized by solidifying the dispersion.

[0066] Examples of acrylic compounds include (meth)acrylate compounds. In this specification, "(meth)acrylate" refers to "acrylic acid" or "methacrylic acid," and "(meth)acrylate" refers to "acrylate" or "methacrylate." Preferably, the (meth)acrylate compound is selected from one or more compounds chosen from the group consisting of monofunctional (meth)acrylate compounds and polyfunctional (meth)acrylate compounds.

[0067] Specific examples of monofunctional (meth)acrylate compounds include: methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, isononyl methacrylate, n-octyl methacrylate, lauryl methacrylate, stearyl methacrylate, and other alkyl methacrylates having 1 to 18 carbon atoms; benzyl methacrylate, phenoxyethyl methacrylate, and 3-phenoxybenzyl methacrylate. EO-modified o-phenylphenol acrylate and other (meth)acrylate compounds with aromatic rings; (meth)acrylate butoxyethyl acrylate and other (meth)acrylate alkoxyalkyl acrylates; (meth)acrylate N,N-dimethylaminoethyl acrylate and other (meth)acrylate aminoalkyl acrylates; diethylene glycol monoethyl ether (meth)acrylate, triethylene glycol monobutyl ether (meth)acrylate, tetraethylene glycol monomethyl ether (meth)acrylate, hexaethylene glycol monomethyl ether (meth)acrylate, octaethylene glycol monomethyl ether (meth)acrylate, nonaethylene glycol monomethyl ether (meth)acrylate, dipropylene glycol monomethyl ether (meth)acrylate, heptaethylene glycol monomethyl ether (meth)acrylate, octaethylene glycol monomethyl ether (meth)acrylate, nonaethylene glycol monomethyl ether (meth)acrylate, dipropylene glycol monomethyl ether (meth)acrylate, heptapropylene glycol monomethyl ether (meth)acrylate Polyalkylene glycol monoalkyl ether (meth)acrylates such as acrylates and tetraethylene glycol monoethyl ether (meth)acrylates; polyalkylene glycol monoaryl ether (meth)acrylates such as hexaethylene glycol monophenyl ether (meth)acrylates; (meth)acrylate compounds with alicyclic structures such as (meth)acrylate, (meth)acrylate, (meth)acrylate, and methylene epoxy addition cyclodecadiene (meth)acrylate; (meth)acrylate compounds with heterocyclic structures such as (meth)acrylate, (meth)acrylate, and (meth)acrylate, ... Hydroxyethyl acrylate, 3-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, and other (meth)acrylate compounds with hydroxyl groups; glycidyl acrylate and other (meth)acrylate compounds with glycidyl groups; 2-(2-(meth)acryloyloxyethyloxy)ethyl acrylate, 2-(meth)acryloyloxyethyl acrylate, and other (meth)acrylate compounds with isocyanate groups; triethylene glycol mono(meth)acrylate, tetraethylene glycol mono(meth)acrylate, hexaethylene glycol mono(meth)acrylate, octapropylene glycol mono(meth)acrylate, and other polyalkylene glycol mono(meth)acrylates, etc.

[0068] Specific examples of multifunctional (meth)acrylate compounds include: alkyl diacrylates such as 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, and 1,9-nonanediol dimethacrylate; polyalkyl diacrylates such as polyethylene glycol dimethacrylate and polypropylene glycol dimethacrylate; trimethylolpropane trimethacrylate, ethylene oxide addition trimethylolpropane trimethacrylate, and tri(2-acryloyloxyethyl) isocyanate; and pentaerythritol tetramethacrylate and trimethylolpropane tetramethacrylate. Tetra(meth)acrylate compounds such as pentaerythritol tetra(meth)acrylate; tricyclodecanediethanol di(meth)acrylate, cyclohexanediethanol di(meth)acrylate, 1,3-adamantanediethanol di(meth)acrylate, hydrogenated bisphenol A (poly)ethoxydi(meth)acrylate, hydrogenated bisphenol A (poly)propoxydi(meth)acrylate, hydrogenated bisphenol F (poly)ethoxydi(meth)acrylate, hydrogenated bisphenol F (poly)propoxydi(meth)acrylate, hydrogenated bisphenol S (poly)ethoxydi(meth)acrylate, hydrogenated bisphenol S (poly)propoxydi(meth)acrylate, etc. (meth)acrylate compounds with alicyclic structures, etc.

[0069] As an acrylic compound, a monofunctional (meth)acrylate compound is preferred, wherein, more preferably, a (meth)acrylate compound having an aromatic ring as described above. In this case, not only is the dispersibility of the metal oxide particles easily improved, but the refractive index of the cured product is also easily increased.

[0070] (Dispersions and solidified products of dispersions)

[0071] In the dispersion of the present invention, the ratio of dispersant, metal oxide particles and acrylic compound can be set to various ratios without hindering the effect of the present invention.

[0072] In the dispersion of the present invention, based on the total mass of the dispersant, metal oxide particles, and acrylic compound, the content ratio of metal oxide particles can be set to 1% by mass or more, preferably 5% by mass or more, more preferably 10% by mass or more, further preferably 20% by mass or more, even more preferably 30% by mass or more, and particularly preferably 40% by mass or more. It should be particularly noted that even when the solid content concentration of the metal oxide particles is increased, the dispersion of the present invention is not prone to a decrease in dispersibility or an increase in viscosity. From this viewpoint, based on the total mass of the dispersant, metal oxide particles, and acrylic compound, the content ratio of metal oxide particles can reach 45% by mass or more, or even a high solid content concentration of 50% by mass or more, and even 55% by mass or more.

[0073] There is no particular upper limit to the content ratio of metal oxide particles. From the viewpoint of easily suppressing viscosity increase, when the total mass of dispersant, metal oxide particles and acrylic compound is used as the basis, the content ratio of metal oxide particles is preferably 80% by mass or less, more preferably 75% by mass or less, further preferably 70% by mass or less, and particularly preferably 65% ​​by mass or less.

[0074] In the dispersion of the present invention, the content of the dispersant relative to 100 parts by mass of metal oxide particles may be 0.5 parts by mass or more, preferably 1 part by mass or more, more preferably 3 parts by mass or more, further preferably 4 parts by mass or more, and particularly preferably 5 parts by mass or more. Furthermore, the content of the dispersant relative to 100 parts by mass of metal oxide particles may be 30 parts by mass or less, preferably 25 parts by mass or less, more preferably 20 parts by mass or less, further preferably 18 parts by mass or less, even more preferably 16 parts by mass or less, and particularly preferably 12 parts by mass or less.

[0075] In the dispersion of the present invention, the content of acrylic acid compound relative to 100 parts by mass of metal oxide particles may be 50 parts by mass or more, preferably 60 parts by mass or more, more preferably 70 parts by mass or more, further preferably 80 parts by mass or more, and particularly preferably 90 parts by mass or more. Furthermore, the content of acrylic acid compound relative to 100 parts by mass of metal oxide particles may be 300 parts by mass or less, preferably 250 parts by mass or less, more preferably 200 parts by mass or less, further preferably 150 parts by mass or less, and particularly preferably 130 parts by mass or less.

[0076] The dispersion of the present invention may contain other components besides the dispersant, metal oxide particles, and acrylic compounds, without hindering the effects of the present invention. Other components, in addition to the photopolymerization initiator described later, may include additives such as light stabilizers, antioxidants, preservatives, flame retardants, pigments, colorants, mildew inhibitors, and lubricants. The photopolymerization initiator may be included in the coating agent described later, or it may not be included in the dispersion. The dispersion may contain one or more additives.

[0077] The method for preparing the dispersion of the present invention is not particularly limited. For example, the dispersant, metal oxide particles, and acrylic compounds, as well as other components added as needed, can be formulated according to a predetermined ratio to prepare the dispersion. The metal oxide particles used to prepare the dispersion can be in powder form, dispersed in a solvent, or in other forms. In the preparation of the dispersion, for example, a commercially available mixer can be used, and a disperser can also be used as needed to disperse the metal oxide particles.

[0078] The dispersion of the present invention is formed by dispersing metal oxide particles in an acrylic compound. Because the dispersion of the present invention contains a dispersant for metal oxide particles, the dispersibility of the metal oxide particles is excellent; even at a high solids concentration (i.e., the concentration of metal oxide particles), viscosity increase and precipitation are not easily observed, and the transparency is also high. In particular, the dispersion of the present invention maintains excellent dispersibility and is not prone to viscosity increase even when the solids concentration of metal oxide particles is increased, thus exhibiting excellent workability.

[0079] As described above, the dispersion of the present invention can enhance the function of metal oxide particles (e.g., high refractive index) by increasing the concentration of solid components. Furthermore, the solidified product formed by curing the dispersion can maintain a good dispersion state, and furthermore, the solidified product can also provide good transparency and a good refractive index.

[0080] The dispersion of the present invention contains an acrylic compound that has polymerizability (curing properties), and therefore can be cured to form a cured product. For example, by coating the dispersion of the present invention onto a substrate to form a coating film, and then curing the coating film, a cured product of the dispersion (also referred to as a cured film) is formed.

[0081] To promote the curing of the dispersion, the dispersion may contain a photopolymerization initiator. There are no particular limitations on the type of photopolymerization initiator; for example, widely known photopolymerization initiators can be used. Examples of photopolymerization initiators include polymerization initiators based on active energy lines such as ultraviolet light.

[0082] Examples of photopolymerization initiators include: aromatic ketones such as benzophenone; aromatic compounds such as anthracene and α-chloromethylnaphthalene; and sulfur compounds such as diphenyl sulfide and thiocarbamate.

[0083] Examples of polymerization initiators based on active energy lines such as ultraviolet light (beyond visible light) include: acetophenone, acetophenone benzyl ketal, 1-hydroxycyclohexylphenyl ketone, 2,2-dimethoxy-1,2-diphenylethane-1-one, xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone, triphenylamine, carbazole, 3-methylacetophenone, 4-chlorobenzophenone, 4,4'-dimethoxybenzophenone, 4,4'-diaminobenzophenone, benzoin propyl ether, benzoin ethyl ether, benzyl dimethyl ketal, 1-(4-isobenzoylbenzoyl)-methyl ketal, etc. Propylphenyl)-2-hydroxy-2-methylpropane-1-one, 2-hydroxy-2-methyl-1-phenylpropane-1-one, thioxanthone, diethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinyl-propane-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinylphenyl)-butanone-1,4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)one, 2,4,6-trimethylbenzyl diphenylphosphine oxide, bis-(2,6-dimethoxybenzyl)-2,4,4-trimethylpentylphosphine oxide, oligomeric (2-hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl)propanone), etc.

[0084] Commercially available polymerization initiators based on active energy lines include, for example: Omnirad 184, 369, 651, 500, 819, 907, 784, 2959, 1000, 1300, 1700, 1800, and 1850 manufactured by IGM Resins BV; Lucilin TPO manufactured by BASF; Eubecrill P36 manufactured by UCB; and Flatetsu. Lamberty Corporation manufactures Ezarkier KIP150, KIP100F, KT37, KT55, KTO46, TZT, and KIP75LT; Nippon Kayaku Co., Ltd. manufactures Kayakier DETX, etc.

[0085] When the dispersion contains a photopolymerization initiator, the content of the photopolymerization initiator is not particularly limited. For example, the content of the photopolymerization initiator is 0.1 to 10 parts by mass relative to 100 parts by mass of acrylic compound, preferably 0.5 to 5 parts by mass.

[0086] Examples of substrates used as the cured material for forming the dispersion of the present invention include resin films, resin sheets, and resin plates. Other substrates may be made of glass, metal, inorganic materials, etc.

[0087] There are no particular limitations on the method of coating the dispersion onto the substrate. For example, a commonly known coating machine such as a rod coater can be used to coat the dispersion onto the substrate, thereby forming a film of the dispersion on the substrate. There are also no particular limitations on the curing method of the coating film. Examples include irradiating the coating film with an active energy beam and heating the coating film. Examples of active energy beams include high-pressure mercury lamps, electron beams, gamma rays, carbon arc lamps, xenon lamps, and metal halide lamps. When curing by heating, curing can be achieved by heating in a temperature range of 60 to 250°C.

[0088] Since the cured product is formed from the dispersion of the present invention, it maintains a good dispersion state. Therefore, metal oxide particles are not easily aggregated in the cured product, and thus the cured product also has excellent transparency.

[0089] Furthermore, due to the excellent dispersibility of the metal oxide particles in the cured product, the inherent properties of the metal oxide particles are easily and effectively utilized. For example, if the metal oxide particles are capable of imparting a high refractive index, the cured product (film) will also easily exhibit the high refractive index of the metal oxide particles, becoming a cured product with a high refractive index.

[0090] Furthermore, the cured product formed from the dispersion of the present invention has excellent transparency because it contains a polymer of a specific dispersant, metal oxide particles, and acrylic compounds.

[0091] The shape of the solidified product formed by the dispersion of the present invention is not particularly limited, and various shapes such as film, plate, block (cube), and granules can be listed.

[0092] As described above, the dispersion of the present invention can form a cured product having the various properties described above, and therefore is suitable for various applications, such as being suitable for use as a coating agent for forming cured products. In addition to the dispersion of the present invention, this coating agent may contain other components as needed. For example, if the dispersion does not contain the aforementioned photopolymerization initiator, the coating agent may contain the same photopolymerization initiator as described above, in the amount stated above.

[0093] By using the above-mentioned coating agent, a solidified dispersion can be formed, which can be used for coating substrates, and can impart, for example, high transparency and refractive index.

[0094] In defining the inventions included in this disclosure, the various components (properties, structures, functions, etc.) described in the various embodiments of this disclosure can be combined arbitrarily. That is, this disclosure includes all subject matter consisting of all combinations of the combinable components described in this specification.

[0095] Example

[0096] The present invention will now be described in more detail with reference to embodiments, but the present invention is not limited to these embodiments.

[0097] (Example 1)

[0098] 1.0 mol of ε-caprolactone, 0.03 mol of p-toluenesulfonic acid monohydrate, and 0.28 mol of pure water were added to 1.0 mol of 3-phenylpropionic acid, and the mixture was stirred at 80 °C for about 8 hours. Then, the mixture was dehydrated under reduced pressure (30 kPa) while being stirred for another 2 hours. Finally, the 3-phenylpropionic acid remaining in the reaction system was distilled off, and after purification (washing with water 3 times) and drying, dispersant 1 (R of formula (1)) was obtained. 1 (A compound with ethylene, m = 5, and n = 2).

[0099] (Comparative Example 1a)

[0100] Prepare dispersant C1 (R of formula (1)) 1 A compound of ethylene, m=5, n=10 was used to replace dispersant 1 obtained in Example 1. Dispersant C1 was obtained by the following method: 1.0 mol of ε-caprolactone, 0.03 mol of p-toluenesulfonic acid monohydrate, and 0.3 mol of pure water were added to 1.0 mol of 3-phenylpropionic acid, and the mixture was stirred at 80°C for about 8 hours. Then, the mixture was further stirred for 2 hours while undergoing dehydration under reduced pressure (30 kPa). Finally, the 3-phenylpropionic acid remaining in the reaction system was distilled off, and after purification steps (washing with water 3 times) and drying steps, dispersant C1 was obtained.

[0101] (Comparative Example 1b)

[0102] Prepare 3-phenylpropionic acid (i.e., the compound of formula (1) with n=0) as dispersant C2 to replace dispersant 1 obtained in Example 1.

[0103] (Comparative Example 1c)

[0104] Prepare the compound shown in formula (a) below (n=17 in formula (a)) as dispersant C3 to replace dispersant 1 obtained in Example 1.

[0105] [Chemistry 4]

[0106]

[0107] This compound was obtained by modifying the nonionic surfactant "Noigen EA-157" (registered trademark) manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd. with carboxylic acid.

[0108] (Comparative Example 1d)

[0109] The phosphate ester-based anionic surfactant "Prairf AL" manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd. was prepared as dispersant C4 to replace dispersant 1 obtained in Example 1.

[0110] (raw material)

[0111] Select a predetermined raw material from the raw materials shown below (metal oxide particles, dispersants for metal oxide particles, acrylic compounds) to prepare the dispersions of Examples 2-1 to 2-9 and Comparative Examples 2 to 4 described below.

[0112] <Metal oxide particles>

[0113] Metal oxide particles 1: Zirconia methanol dispersion manufactured by Sakai Chemical Industry Co., Ltd. (D50 = approximately 10 nm)

[0114] Metal oxide particles 2: Zirconia methanol dispersion produced by First Rare Element Chemical Industry Co., Ltd. (D50 = approximately 50 nm)

[0115] Metal oxide particles 3: Zirconia methanol dispersion manufactured by Sakai Chemical Industry Co., Ltd. (D50 = approximately 3 nm)

[0116] <Dispersant for Metal Oxide Particles>

[0117] Dispersant 1: The compound obtained in Example 1

[0118] Dispersant C1 (for comparison): The compound prepared in Comparative Example 1a

[0119] Dispersant C2 (for comparison): The compound prepared in Comparative Example 1b

[0120] Dispersant C3 (for comparison): The compound prepared in Comparative Example 1c

[0121] Dispersant C4 (for comparison): The compound prepared in Comparative Example 1d

[0122] <Acrylic compounds>

[0123] Acrylic compound 1: 3-phenoxybenzyl acrylate (manufactured by Kyoesha Chemical Co., Ltd., "Light Acrylate POB-A")

[0124] Acrylic compound 2: EO-modified o-phenylphenol acrylate (New France OPPE (registered trademark) of Daiichi Kogyo Pharmaceutical Co., Ltd.)

[0125] Acrylic compound 3: Benzyl acrylate

[0126] (Example 2-1)

[0127] The predetermined raw materials were mixed according to the formulation conditions shown in Table 1 to obtain a dispersion. Specifically, 55 parts by mass of metal oxide particles 1 as metal oxide particles, 5.5 parts by mass of dispersant 1 as dispersant, and 39.5 parts by mass of acrylic compound 1 as acrylic compound were formulated and mixed to obtain a dispersion. It should be noted that the formulation amounts of metal oxide particles and dispersant shown above and in Table 1 are solid component conversion amounts, set to the amount excluding volatile components such as solvents.

[0128] (Example 2-2)

[0129] As shown in Table 1, the dispersion was obtained by the same method as in Example 2-1, except that metal oxide particles 2 were used instead of metal oxide particles 1.

[0130] (Examples 2-3)

[0131] As shown in Table 1, the dispersion was obtained by the same method as in Example 2-1, except that metal oxide particles 3 were used instead of metal oxide particles 1.

[0132] (Examples 2-4)

[0133] As shown in Table 1, the dispersion was obtained by the same method as in Example 2-1, except that the amount of metal oxide particles 1 was changed to 60 parts by mass, the amount of dispersant 1 was changed to 6 parts by mass, and the amount of acrylic compound 1 was changed to 34 parts by mass.

[0134] (Examples 2-5)

[0135] As shown in Table 1, the dispersion was obtained by the same method as in Example 2-1, except that the amount of metal oxide particles 1 was changed to 50 parts by mass, the amount of dispersant 1 was changed to 5 parts by mass, and the amount of acrylic compound 1 was changed to 45 parts by mass.

[0136] (Examples 2-6)

[0137] As shown in Table 1, the dispersion was obtained by the same method as in Example 2-1, except that the amount of dispersant 1 was changed to 1 part by mass and the amount of acrylic compound 1 was changed to 44 parts by mass.

[0138] (Examples 2-7)

[0139] As shown in Table 1, the dispersion was obtained by the same method as in Example 2-1, except that the amount of dispersant 1 was changed to 10 parts by mass and the amount of acrylic compound 1 was changed to 35 parts by mass.

[0140] (Examples 2-8)

[0141] As shown in Table 1, the dispersion was obtained by the same method as in Example 2-1, except that acrylic compound 2 was used instead of acrylic compound 1.

[0142] (Examples 2-9)

[0143] As shown in Table 1, the dispersion was obtained by the same method as in Example 2-1, except that acrylic compound 3 was used instead of acrylic compound 1.

[0144] (Comparative Example 2)

[0145] As shown in Table 1, the dispersion was obtained by the same method as in Example 2-1, except that dispersant C1 was used instead of dispersant 1.

[0146] (Comparative Example 3)

[0147] As shown in Table 1, the dispersion was obtained by the same method as in Example 2-1, except that dispersant C2 was used instead of dispersant 1.

[0148] (Comparative Example 4)

[0149] As shown in Table 1, the dispersion was obtained by the same method as in Example 2-1, except that dispersant C3 was used instead of dispersant 1.

[0150] (Comparative Example 5)

[0151] As shown in Table 1, the dispersion was obtained by the same method as in Example 2-1, except that dispersant C4 was used instead of dispersant 1.

[0152] (Assessment Methodology)

[0153] The dispersibility, precipitation ease, and refractive index of the dispersions obtained in each embodiment and comparative example were evaluated by the following steps.

[0154] <Dispersibility of Dispersions>

[0155] The dispersibility of the dispersion was evaluated based on the viscosity measured by an E-type viscometer and the total light transmittance of the dispersion. The viscosity of the dispersion was measured using a commercially available E-type viscometer (Tokyo Keiki Co., Ltd.) at 25°C. Furthermore, the total light transmittance of the dispersion was measured using a "HazeMeter NDH4000" manufactured by Nippon Denshoku Kogyo Co., Ltd., and the dispersion was evaluated based on these values ​​according to the following criteria.

[0156] Assessment Benchmarks

[0157] A: The viscosity of the dispersion is less than 1000 mPa·s, and the total light transmittance is over 80%, with extremely high transparency and exceptionally good dispersibility.

[0158] B: The viscosity of the dispersion is above 1000 mPa·s and less than 10000 mPa·s, and the total light transmittance is above 75% and less than 80%, exhibiting high transparency and excellent dispersibility.

[0159] C: The viscosity of the dispersion is above 10000 mPa·s, and the total light transmittance is less than 75%, with extremely poor flowability and transparency, and poor dispersibility.

[0160] <Ease of precipitation of dispersions>

[0161] The dispersion is loaded into a screw-type tube, and the dispersion and the tube are vibrated together to ensure uniform dispersion. Then, the tube is allowed to stand, and the time until particle precipitation occurs is measured. The ease of precipitation of the dispersion is evaluated using the following criteria.

[0162] Assessment Benchmarks

[0163] A: It takes more than 24 hours for particulate precipitation to occur, and precipitation is extremely difficult to occur.

[0164] B: Although the time until particle precipitation occurs is within 24 hours, no precipitation occurs for a period of time immediately after standing, so precipitation is not likely to occur.

[0165] C: It precipitates immediately after being left to stand, and it is extremely easy for it to precipitate.

[0166] <Refractive index of dispersion>

[0167] The refractive index of the dispersion was measured using an Abe refractive index meter (manufactured by Atago Corporation, trade name NAR-IT) at 25°C.

[0168] Assessment Benchmarks

[0169] A: The refractive index of the dispersion is above 1.65, indicating a high refractive index.

[0170] B: The refractive index of the dispersion is less than 1.65, indicating a low refractive index.

[0171] Table 1 shows the formulation conditions of the dispersions obtained in each embodiment and comparative example, as well as the above evaluation results. Furthermore, in the formulation conditions of Table 1, empty columns indicate that no raw material was used.

[0172] As shown in Table 1, the dispersions obtained in each embodiment exhibit excellent dispersibility of the metal oxide particles due to the presence of a dispersant containing a predetermined compound in the metal oxide particles. Furthermore, the dispersions obtained in the embodiments are less prone to precipitation or aggregation, exhibiting not only high transparency but also a high refractive index.

[0173] [Table 1]

[0174]

Claims

1. A dispersant for metal oxide particles, characterized in that, It is a dispersant used to disperse metal oxide particles. The dispersant contains a compound represented by the following general formula (1). [Chemistry 1] In equation (1), R 1 This indicates an alkylene group, where m is a number from 2 to 7 and n is a number from 1 to 7.

2. The dispersant for metal oxide particles as described in claim 1, wherein, In the above formula (1), R 1 It is an alkylene group having 1 to 6 carbon atoms.

3. A dispersion, characterized in that, contain: The dispersant for metal oxide particles as described in claim 1 or 2; Metal oxide particles; and Acrylic acid compounds.

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