Ink composition, layer using this composition, and electrophoresis apparatus and display device containing this composition.

Abstract

This invention discloses an ink composition, a layer manufactured using the ink composition, and an electrophoresis apparatus and display device comprising the ink composition. The ink composition comprises: (A) semiconductor nanorods; and (B) a mixed solvent comprising a first solvent, a second solvent, and a third solvent, wherein the first solvent has a viscosity of less than or equal to 70 centipoise at 25°C and comprises a compound having a dielectric constant of greater than or equal to 5, the second solvent comprises a compound having a viscosity of greater than or equal to 80 centipoise at 25°C or is a solid and has a dielectric constant of greater than or equal to 5, and the third solvent comprises a compound having a dielectric constant of less than 5.

Description

Technical Field

[0001] This disclosure relates to an ink composition, a layer using the composition, and an electrophoresis apparatus and display device comprising the composition. Background Technology

[0002] Since 1992, when Nakamura and others from Japanese Nichia Corp. successfully fused high-quality single-crystal GaN nitride semiconductors using a low-temperature GaN compound buffer layer, LEDs have seen significant development. An LED is a semiconductor device that converts electrical signals into light with a desired wavelength by utilizing the properties of compound semiconductors, which have a structure combining multiple n-type semiconductor crystals with electron carriers and multiple p-type semiconductor crystals with holes carriers.

[0003] This LED semiconductor boasts high light conversion efficiency, resulting in minimal energy consumption and a semi-permanent lifespan. It is also environmentally friendly, thus representing a revolution in light as a green material. Recently, with the development of compound semiconductor technology, high-brightness red, orange, green, blue, and white LEDs have been developed and applied in many fields, such as traffic lights, mobile phones, automotive headlights, outdoor billboards, LCD backlight units (BLUs), and indoor / outdoor lighting. Research in this area has been ongoing both domestically and internationally. Specifically, GaN-based compound semiconductors with wide bandgap are used to manufacture LED semiconductors that emit light in the green, blue, and ultraviolet (UV) regions. Furthermore, due to the use of blue LED devices in the manufacture of white LED devices, extensive research is being conducted on this topic.

[0004] In these studies, research is actively underway on the use of ultra-small LED devices with nanometer or micrometer dimensions, and further research is ongoing on their application in lighting and displays. In these studies, the electrodes capable of applying power to the ultra-small LED devices, the placement of electrodes to reduce the space occupied by the electrodes, methods for mounting the ultra-small LED devices on the placed electrodes, and similar techniques are receiving increasing attention.

[0005] One reason for this difficulty is that, due to the size limitations of ultra-small LED devices, the method of mounting ultra-small LED devices on the electrodes still cannot achieve the desired placement and installation of ultra-small LED devices on the electrodes. This is because ultra-small LED devices are nanometer- or micrometer-sized, and therefore cannot be manually placed and installed one by one in the target electrode area.

[0006] Recently, with the increasing demand for nanoscale ultra-small LED devices, attempts have been made to fabricate nanoscale GaN or InGaN-based compound semiconductors into rods. However, this has resulted in a significant reduction in the dispersion stability of the nanorods in solutions (or polymerizable compounds). To date, no technology has been introduced to improve the dispersion stability of semiconductor nanorods in solutions (or polymerizable compounds). Therefore, continued research is needed on curable compositions containing semiconductor nanorods that can improve the dispersion stability of semiconductor nanorods in solvents (or polymerizable compounds) and achieve high dielectric constants. Summary of the Invention

[0007] [The problem the invention aims to solve]

[0008] The embodiments provide an ink composition with excellent electrophoretic properties, inkjet properties, and storage stability of semiconductor nanorods.

[0009] Another embodiment provides a layer manufactured using an ink composition.

[0010] Another embodiment provides an electrophoresis apparatus and a display device that include the layer.

[0011] [Technical means to solve the problem]

[0012] An embodiment provides an ink composition comprising: (A) semiconductor nanorods; and (B) a mixed solvent comprising a first solvent, a second solvent, and a third solvent, wherein the first solvent has a viscosity of less than or equal to 70 centipoise at 25°C and comprises a compound having a dielectric constant of greater than or equal to 5, the second solvent comprises a compound having a viscosity of greater than or equal to 80 centipoise at 25°C or is a solid and has a dielectric constant of greater than or equal to 5, and the third solvent comprises a compound having a dielectric constant of less than 5.

[0013] The first solvent can have a viscosity greater than or equal to 3 centipoise at 50°C.

[0014] The first solvent may contain a compound represented by chemical formula 1-1 or chemical formula 1-2.

[0015] [Chemical Formula 1-1]

[0016]

[0017] [Chemical Formula 1-2]

[0018]

[0019] In chemical formulas 1-1 and 1-2,

[0020] R 1R' is a hydrogen atom or *-C(=O)R', where R' is a hydrogen atom or a substituted or unsubstituted C1 to C10 alkyl group.

[0021] R 2 To R 4 Each is independently a substituted or unsubstituted C2 to C20 alkyl group.

[0022] R 5 It is a substituted or unsubstituted C1 to C20 alkyl group or a substituted or unsubstituted C6 to C20 aryl group substituted with a C2 to C10 alkoxy group.

[0023] L 1 To L 3 Each is independently a substituted or unsubstituted C1 to C20 alkyl group, and

[0024] n is an integer from 1 to 20.

[0025] A compound represented by chemical formula 1-1 may include compounds represented by chemical formula 1-1-1 or chemical formula 1-1-2.

[0026] [Chemical Formula 1-1-1]

[0027]

[0028] [Chemical Formula 1-1-2]

[0029]

[0030] Compounds represented by chemical formula 1-2 may include compounds represented by chemical formulas 1-2-1 to 1-2-4.

[0031] [Chemical Formula 1-2-1]

[0032]

[0033] [Chemical Formula 1-2-2]

[0034]

[0035] [Chemical Formula 1-2-3]

[0036]

[0037] [Chemical Formula 1-2-4]

[0038]

[0039] The second solvent may have a viscosity greater than or equal to 10 centipoise at 50°C or may be a solid.

[0040] The second solvent may contain a compound represented by one of chemical formulas 2-1 to 2-6.

[0041] [Chemical Formula 2-1]

[0042]

[0043] [Chemical Formula 2-2]

[0044]

[0045] [Chemical Formula 2-3]

[0046]

[0047] [Chemical Formula 2-4]

[0048]

[0049] [Chemical Formula 2-5]

[0050]

[0051] [Chemical Formula 2-6]

[0052]

[0053] In chemical formulas 2-1 to 2-6

[0054] L 1 L 2 and L 4 To L 8 Each is independently a substituted or unsubstituted C1 to C20 alkyl group.

[0055] R 1 R' is a hydrogen atom or *-C(=O)R', where R' is a hydrogen atom or a substituted or unsubstituted C1 to C10 alkyl group.

[0056] R 6 It is a hydroxyl group or a substituted or unsubstituted C1 to C20 alkyl group.

[0057] R 7 and R 8 Each is independently a substituted or unsubstituted C1 to C20 alkyl group.

[0058] R 16 and R 17 Each is independently a hydrogen atom, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, or a substituted or unsubstituted C6 to C20 aryl group.

[0059] R18 and R 19 Each is independently a hydrogen atom or *-(C=O)R 15 , where R 15 It can be a substituted or unsubstituted C1 to C20 alkyl, a substituted or unsubstituted C3 to C20 cycloalkyl, or a substituted or unsubstituted C6 to C20 aryl.

[0060] R 20 It is methoxy.

[0061] R 21 It is a substituted or unsubstituted C1 to C20 alkyl or a substituted or unsubstituted C1 to C20 alkoxy group.

[0062] m is an integer from 1 to 4.

[0063] p is an integer from 0 to 4, and

[0064] q is an integer from 1 to 20.

[0065] Compounds represented by chemical formula 2-1 may include compounds represented by chemical formula 2-1-1.

[0066] [Chemical Formula 2-1-1]

[0067]

[0068] A compound represented by chemical formula 2-2 may include a compound represented by chemical formula 2-2-1.

[0069] [Chemical Formula 2-2-1]

[0070]

[0071] Compounds represented by chemical formula 2-3 may include compounds represented by one of chemical formulas 2-3-1 to 2-3-3.

[0072] [Chemical Formula 2-3-1]

[0073]

[0074] [Chemical Formula 2-3-2]

[0075]

[0076] [Chemical Formula 2-3-3]

[0077]

[0078] Compounds represented by chemical formula 2-4 may include compounds represented by chemical formula 2-4-1.

[0079] [Chemical Formula 2-4-1]

[0080]

[0081] Compounds represented by chemical formula 2-5 may include compounds represented by either chemical formula 2-5-1 or chemical formula 2-5-2.

[0082] [Chemical Formula 2-5-1]

[0083]

[0084] [Chemical Formula 2-5-2]

[0085]

[0086] Compounds represented by chemical formula 2-6 may include compounds represented by one of chemical formulas 2-6-1 to 2-6-3.

[0087] [Chemical Formula 2-6-1]

[0088]

[0089] [Chemical Formula 2-6-2]

[0090]

[0091] [Chemical Formula 2-6-3]

[0092]

[0093] The third solvent may have a viscosity of 70 centipoise or greater at 25°C, or may be a solid and have a viscosity of 3 centipoise or greater at 50°C.

[0094] The third solvent may contain a compound represented by either chemical formula 3-1 or chemical formula 3-2.

[0095] [Chemical Formula 3-1]

[0096]

[0097] [Chemical Formula 3-2]

[0098]

[0099] In chemical formulas 3-1 and 3-2

[0100] R 9 To R 14 Each is independently a C1 to C20 alkyl group, either unsubstituted or vinyl-substituted.

[0101] Compounds represented by chemical formula 3-1 may include compounds represented by chemical formula 3-1-1.

[0102] [Chemical Formula 3-1-1]

[0103]

[0104] A compound represented by chemical formula 3-2 may include a compound represented by chemical formula 3-2-1.

[0105] [Chemical Formula 3-2-1]

[0106]

[0107] The first solvent may be contained in amounts ranging from 10 to 50 parts by weight per 100 parts by weight of the mixed solvent.

[0108] The second solvent may be included in amounts ranging from 10 to 40 parts by weight per 100 parts by weight of the mixed solvent.

[0109] The third solvent may be included in an amount of 20 to 50 parts by weight per 100 parts by weight of the mixed solvent.

[0110] Semiconductor nanorods can have diameters ranging from 300 nanometers to 900 nanometers.

[0111] Semiconductor nanorods can have lengths ranging from 3.5 micrometers to 5 micrometers.

[0112] Semiconductor nanorods may contain GaN-type compounds, InGaN-type compounds, or combinations thereof.

[0113] Semiconductor nanorods may have a surface coated with metal oxides.

[0114] Metal oxides may include aluminum oxide, silicon dioxide, or combinations thereof.

[0115] Semiconductor nanorods may be included in amounts ranging from 0.01% to 10% by weight, based on the total amount of ink components.

[0116] The ink composition may also include malonic acid; 3-amino-1,2-propanediol; silane coupling agents; leveling agents; fluorinated surfactants or combinations thereof.

[0117] The ink composition may be an ink composition used in electrophoresis apparatus.

[0118] Another embodiment provides a layer manufactured using an ink composition.

[0119] Another embodiment provides an electrophoresis apparatus that includes the layer.

[0120] Another embodiment provides a display device that includes the layer.

[0121] Other embodiments of the present invention are included in the following embodiments.

[0122] [The effects of the invention]

[0123] Ink compositions containing semiconductor nanorods can provide curable compositions with excellent electrophoretic properties, inkjet properties, and storage stability. Attached Figure Description

[0124] Figure 1 This is an example of a cross-sectional view of a semiconductor nanorod in a curable composition according to an embodiment. Detailed Implementation

[0125] Embodiments of the invention are described in detail below. However, these embodiments are illustrative, and the invention is not limited thereto, and is defined by the scope of the claims.

[0126] As used herein, unless otherwise specified, “alkyl” refers to C1 to C20 alkyl, “alkenyl” refers to C2 to C20 alkenyl, “cycloalkenyl” refers to C3 to C20 cycloalkenyl, “heterocyclic alkenyl” refers to C3 to C20 heterocyclic alkenyl, “aryl” refers to C6 to C20 aryl, “aranealkyl” refers to C6 to C20 aranealkyl, “endylalkyl” refers to C1 to C20 endylalkyl, “endylaryl” refers to C6 to C20 endylaryl, “alkylendylaryl” refers to C6 to C20 alkylendylaryl, “endylheteroaryl” refers to C3 to C20 endylheteroaryl, and “endylalkoxy” refers to C1 to C20 endylalkoxy.

[0127] As used herein, unless otherwise specifically defined, “substituted” means that at least one hydrogen atom is replaced by: a halogen atom (F, Cl, Br, or I), a hydroxyl group, a C1 to C20 alkoxy group, a nitro group, a cyano group, an amino group, an imino group, an azide group, a formamidinyl group, a hydrazinyl group, a carbonyl group, a carboxyl group, a thiol group, an ester group, an ether group, a carboxyl group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphate group or a salt thereof, a C1 to C20 alkyl group, a C2 to C20 alkenyl group, a C2 to C20 alkynyl group, a C6 to C20 aryl group, a C3 to C20 cycloalkyl group, a C3 to C20 cycloalkenyl group, a C3 to C20 cycloalkynyl group, a C2 to C20 heterocyclic alkyl group, a C2 to C20 heterocyclic alkenyl group, a C2 to C20 heterocyclic alkynyl group, a C3 to C20 heteroaryl group, or a combination thereof.

[0128] As used herein, unless otherwise specifically defined, the term "heterogeneous" refers to a chemical formula containing at least one heteroatom selected from N, O, S, and P.

[0129] As used herein, unless otherwise specified, “(meth)acrylate” means both “acrylate” and “methacrylate”, and “(meth)acrylic acid” means both “acrylic acid” and “methacrylic acid”.

[0130] As used in this article, unless otherwise specified, “combination” means blending or copolymerization.

[0131] As used herein, unless otherwise specifically defined, hydrogen atoms are bonded at the locations where chemical bonds are not drawn where they should be.

[0132] As used in this article, "semiconductor nanorod" refers to a rod-shaped semiconductor with a diameter of nanometer size.

[0133] As used in this document, unless otherwise specified, "*" indicates a point connecting the same or different atoms or chemical formulas.

[0134] The ink composition according to the embodiment comprises: (A) semiconductor nanorods; and (B) a mixed solvent comprising a first solvent, a second solvent, and a third solvent, wherein the first solvent has a viscosity of less than or equal to 70 centipoise at 25°C and comprises a compound having a dielectric constant of greater than or equal to 5, the second solvent comprises a compound having a viscosity of greater than or equal to 80 centipoise at 25°C or is a solid and has a dielectric constant of greater than or equal to 5, and the third solvent comprises a compound having a dielectric constant of less than 5.

[0135] Recently, research has been actively conducted on various concepts that can improve energy efficiency and prevent the efficiency degradation of known LEDs such as micro-LEDs, mini-LEDs, and the like. Among them, the alignment (electrophoresis) of InGaN-type nanorod LEDs using an electric field has attracted attention as a method to significantly reduce the complex and expensive process costs of micro-LEDs, mini-LEDs, and the like.

[0136] However, organic solvents known to be used in displays and electronic materials (PGMEA, GBL, PGME, ethyl acetate, IPA, and the like) have low viscosity, and therefore, the high-density inorganic nanorod particles may settle too quickly and thus aggregate. Furthermore, they are rapidly volatile and may degrade alignment properties during solvent drying after dielectricization. Therefore, in order to develop ink compositions containing inorganic nanorods (semiconductor nanorods), solvents with excellent dielectric properties due to their high viscosity and high boiling point are needed to improve the settling stability of the nanorods. The inventors of this invention, through extensive trial and error, have significantly improved the electrophoretic properties in ink compositions, specifically the proper alignment of semiconductor nanorods and the inkjet properties of the ink compositions, and have also achieved excellent storage stability by controlling the solvent used with the semiconductor nanorods as a three-component system.

[0137] Each component is described in detail below.

[0138] (A) Semiconductor nanorods

[0139] Semiconductor nanorods may contain GaN-type compounds, InGaN-type compounds, or combinations thereof, and their surfaces may be coated with metal oxides.

[0140] To ensure the dispersion stability of the semiconductor nanorod ink solution (semiconductor nanorods + solvent), a time of 3 hours is typically required, which is insufficient for large-area inkjet printing. Therefore, the inventors of this invention have developed an insulating film (Al2O3 or SiO2) by coating the surface of the semiconductor nanorods with metal oxides such as alumina, silicon oxide, or combinations thereof after extensive trial-and-error research to maximize compatibility with the solvents described below. x ).

[0141] For example, an insulating film coated with a metal oxide can have a thickness of 40 nanometers to 60 nanometers.

[0142] Semiconductor nanorods contain an n-type confinement layer and a p-type confinement layer, and a multi-quantum well (MQW) active region can be placed between the n-type confinement layer and the p-type confinement layer.

[0143] For example, semiconductor nanorods can have diameters ranging from 300 nanometers to 900 nanometers, such as 600 nanometers to 700 nanometers.

[0144] For example, semiconductor nanorods can have lengths ranging from 3.5 micrometers to 5 micrometers.

[0145] For example, when semiconductor nanorods may contain an aluminum oxide insulating layer, they may have a density of 5 g / cm³ to 6 g / cm³.

[0146] For example, semiconductor nanorods can have a size of 1×10⁻⁶. -13 Up to 1×10 -11 The mass in grams.

[0147] When semiconductor nanorods have the aforementioned diameter, length, density, and type, surface coating with metal oxides can be easily performed, thereby maximizing the dispersion stability of the semiconductor nanorods.

[0148] Semiconductor nanorods may be included in the ink composition in amounts ranging from 0.01 wt% to 10 wt%, for example, from 0.01 wt% to 5 wt%. Alternatively, semiconductor nanorods may be included in the ink composition in amounts ranging from 0.01 wt% to 0.5 wt%, for example, from 0.01 wt% to 0.1 wt% of solvent per 100 parts by weight. When semiconductor nanorods are included within the above range, the ink exhibits good dispersibility, and the prepared pattern can possess excellent brightness.

[0149] (B) Solvent

[0150] The ink composition according to the embodiment includes a mixed solvent, which comprises three different solvents (a first solvent, a second solvent, and a third solvent) each satisfying different conditions.

[0151] In recent years, with the increasing demand for nanoscale micro-LED devices, attempts have been made to fabricate nanoscale GaN or InGaN compound semiconductors as rods. However, nanorods themselves suffer from significantly reduced dispersion stability in solutions (or polymerizable compounds). To date, no technology has been introduced to improve the dispersion stability of semiconductor nanorods in solvents.

[0152] Organic solvents already used in known displays and electronic materials, such as propylene glycol monomethyl ether acetate (PEGMEA), γ-butyrolactone (GBL), polyethylene glycol methyl ether (PGME), ethyl acetate, isopropyl alcohol (IPA), and the like, have extremely low viscosity, causing high-density inorganic nanorod particles to settle too quickly, resulting in unsatisfactory dielectric properties. Therefore, as described above, to develop ink compositions for electrophoretic devices containing inorganic nanorods (semiconductor nanorods), solvents capable of imparting sedimentation stability to the nanorods can be used.

[0153] Because the ink composition according to the embodiments has a large viscosity difference between room temperature (25°C) and 50°C, the nanorods slowly settle at room temperature (25°C). However, since the ink composition has a viscosity of less than or equal to 15 centipoise at 50°C, inkjet printing can be applied. Simultaneously, the dielectric constant can be controlled according to the composition ratio (the mixing weight ratio of the three types of solvents). In other words, the ink composition according to the embodiments ensures storage stability (high viscosity at room temperature) and exhibits inkjet processability (viscosity less than or equal to 15 centipoise at 50°C) and high dielectric constant (low conductivity and controllable dielectric constant). That is, when a three-component solvent system is used instead of a known single-component or two-component solvent system, the desired viscosity and dielectric constant are ensured by easily controlling the solvent component ratio (mixing weight ratio) of the three components. This makes the ink composition according to the embodiments completely different from known ink compositions in terms of the concept of the present invention.

[0154] For example, the first solvent may have a viscosity of 3 centipoise or greater at 50°C.

[0155] The first solvent may contain a compound represented by chemical formula 1-1 or chemical formula 1-2.

[0156] [Chemical Formula 1-1]

[0157]

[0158] [Chemical Formula 1-2]

[0159]

[0160] In chemical formulas 1-1 and 1-2,

[0161] R 1 R' is a hydrogen atom or *-C(=O)R', where R' is a hydrogen atom or a substituted or unsubstituted C1 to C10 alkyl group.

[0162] R 2 To R 4 Each is independently a substituted or unsubstituted C2 to C20 alkyl group.

[0163] R 5 It is a substituted or unsubstituted C1 to C20 alkyl group or a substituted or unsubstituted C6 to C20 aryl group substituted with a C2 to C10 alkoxy group.

[0164] L 1 To L 3 Each is independently a substituted or unsubstituted C1 to C20 alkyl group, and

[0165] n is an integer from 1 to 20.

[0166] For example, a compound represented by chemical formula 1-1 may include compounds represented by chemical formula 1-1-1 or chemical formula 1-1-2.

[0167] [Chemical Formula 1-1-1]

[0168]

[0169] [Chemical Formula 1-1-2]

[0170]

[0171] For example, a compound represented by chemical formula 1-2 may include compounds represented by chemical formulas 1-2-1 to 1-2-4.

[0172] [Chemical Formula 1-2-1]

[0173]

[0174] [Chemical Formula 1-2-2]

[0175]

[0176] [Chemical Formula 1-2-3]

[0177]

[0178] [Chemical Formula 1-2-4]

[0179]

[0180] For example, the second solvent may have a viscosity of 10 centipoise or greater at 50°C or may be a solid.

[0181] For example, the second solvent may contain a compound represented by one of chemical formulas 2-1 to 2-6.

[0182] [Chemical Formula 2-1]

[0183]

[0184] [Chemical Formula 2-2]

[0185]

[0186] [Chemical Formula 2-3]

[0187]

[0188] [Chemical Formula 2-4]

[0189]

[0190] [Chemical Formula 2-5]

[0191]

[0192] [Chemical Formula 2-6]

[0193]

[0194] In chemical formulas 2-1 to 2-6

[0195] L 1 L 2 and L 4 To L 8 Each is independently a substituted or unsubstituted C1 to C20 alkyl group.

[0196] R 1 R' is a hydrogen atom or *-C(=O)R', where R' is a hydrogen atom or a substituted or unsubstituted C1 to C10 alkyl group.

[0197] R 6 It is a hydroxyl group or a substituted or unsubstituted C1 to C20 alkyl group.

[0198] R 7 and R 8 Each is independently a substituted or unsubstituted C1 to C20 alkyl group.

[0199] R 16 and R 17 Each is independently a hydrogen atom, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, or a substituted or unsubstituted C6 to C20 aryl group.

[0200] R 18 and R 19 Each is independently a hydrogen atom or *-(C=O)R 15 , where R 15 It can be a substituted or unsubstituted C1 to C20 alkyl, a substituted or unsubstituted C3 to C20 cycloalkyl, or a substituted or unsubstituted C6 to C20 aryl.

[0201] R 20 It is methoxy.

[0202] R 21 It is a substituted or unsubstituted C1 to C20 alkyl or a substituted or unsubstituted C1 to C20 alkoxy group.

[0203] m is an integer from 1 to 4.

[0204] p is an integer from 0 to 4, and

[0205] q is an integer from 1 to 20.

[0206] For example, a compound represented by chemical formula 2-1 may include a compound represented by chemical formula 2-1-1.

[0207] [Chemical Formula 2-1-1]

[0208]

[0209] For example, a compound represented by chemical formula 2-2 may include a compound represented by chemical formula 2-2-1.

[0210] [Chemical Formula 2-2-1]

[0211]

[0212] For example, a compound represented by chemical formula 2-3 may include compounds represented by one of chemical formulas 2-3-1 to 2-3-3.

[0213] [Chemical Formula 2-3-1]

[0214]

[0215] [Chemical Formula 2-3-2]

[0216]

[0217] [Chemical Formula 2-3-3]

[0218]

[0219] For example, a compound represented by chemical formula 2-4 may include a compound represented by chemical formula 2-4-1.

[0220] [Chemical Formula 2-4-1]

[0221]

[0222] Compounds represented by chemical formula 2-5 may include compounds represented by either chemical formula 2-5-1 or chemical formula 2-5-2.

[0223] [Chemical Formula 2-5-1]

[0224]

[0225] [Chemical Formula 2-5-2]

[0226]

[0227] Compounds represented by chemical formula 2-6 may include compounds represented by one of chemical formulas 2-6-1 to 2-6-3.

[0228] [Chemical Formula 2-6-1]

[0229]

[0230] [Chemical Formula 2-6-2]

[0231]

[0232] [Chemical Formula 2-6-3]

[0233]

[0234] For example, the third solvent may have a viscosity of 70 centipoise or greater at 25°C, or it may be a solid and have a viscosity of 3 centipoise or greater at 50°C.

[0235] For example, the third solvent may contain a compound represented by either chemical formula 3-1 or chemical formula 3-2.

[0236] [Chemical Formula 3-1]

[0237]

[0238] [Chemical Formula 3-2]

[0239]

[0240] In chemical formulas 3-1 and 3-2

[0241] R 9 To R 14 Each is independently a C1 to C20 alkyl group, either unsubstituted or vinyl-substituted.

[0242] For example, a compound represented by chemical formula 3-1 may include a compound represented by chemical formula 3-1-1.

[0243] [Chemical Formula 3-1-1]

[0244]

[0245] For example, a compound represented by chemical formula 3-2 may include a compound represented by chemical formula 3-2-1.

[0246] [Chemical Formula 3-2-1]

[0247]

[0248] The viscosity and dielectric constant of each of the compounds represented by chemical formulas 1-1-1 to 3-2-1 are shown in Table 1.

[0249] (Table 1)

[0250]

[0251] (*Dielectric constant at 50℃)

[0252] The first solvent may be contained in amounts ranging from 10 to 50 parts by weight per 100 parts by weight of the mixed solvent.

[0253] The second solvent may be included in amounts ranging from 10 to 40 parts by weight per 100 parts by weight of the mixed solvent.

[0254] The third solvent may be included in an amount of 20 to 50 parts by weight per 100 parts by weight of the mixed solvent.

[0255] The solvent may be contained in amounts ranging from 5% to 99% by weight, for example, from 20% to 99.7% by weight, based on the total amount of the ink composition.

[0256] polymerizable monomers

[0257] In some cases, the ink composition according to the embodiments may further contain polymerizable compounds. Polymerizable compounds can be used by mixing monomers or oligomers commonly used in known curable compositions.

[0258] For example, a polymerizable compound can be a polymerizable monomer having a carbon-carbon double bond at the end.

[0259] For example, the polymerizable compound may be a polymerizable monomer having at least one functional group represented by chemical formula A-1 or a functional group represented by chemical formula A-2 at its end.

[0260] [Chemical Formula A-1]

[0261]

[0262] [Chemical Formula A-2]

[0263]

[0264] In chemical formulas A-1 and A-2,

[0265] L a Substituted or unsubstituted C1 to C20 alkyl groups, and

[0266] R a It is a hydrogen atom or a substituted or unsubstituted C1 to C20 alkyl group.

[0267] The polymerizable compound contains at least one carbon-carbon double bond at the end, specifically a functional group represented by chemical formula A-1 or chemical formula A-2, and thus can form a cross-linked structure with the surface-modifying compound. This cross-linked structure can further double a type of steric hindrance effect and greatly improve the dispersion stability of semiconductor nanorods.

[0268] For example, a polymerizable compound containing at least one functional group represented by the chemical formula A-1 at the end may be divinylbenzene, triallyl cyanurate, triallyl isocyanate, triallyl trimellitate, triallyl phosphate, triallyl phosphite, triallyl triazine, diallyl phthalate, or combinations thereof, but is not necessarily limited thereto.

[0269] For example, polymerizable compounds containing at least one functional group represented by the chemical formula A-2 at the end may be ethylene glycol diacrylate, triethylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, neopentyl tetraethylene diacrylate, neopentyl tetraethylene triacrylate, dinepentyl tetraethylene diacrylate, dinepentyl tetraethylene triacrylate, dinepentyl tetraethylene pentaacrylate, neopentyl tetraethylene hexaacrylate, bisphenol A diacrylate, trimethylolpropane triacrylate, phenolic epoxy acrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, propylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, polyfunctional epoxy (meth)acrylate, polyfunctional aminocarbamate (meth)acrylate, and KAYARAD from Nippon Chemical Co., Ltd. DPCA-20, KAYARAD DPCA-30, KAYARAD DPCA-60, KAYARAD DPCA-120, KAYARAD DPEA-12 or combinations thereof, but not necessarily limited to these.

[0270] Polymerizable compounds can be used by treating them with acid anhydrides to impart better developability.

[0271] Polymerization initiator

[0272] The curable composition according to the embodiments may further include, if necessary, a polymerization initiator, such as a photopolymerization initiator, a thermal polymerization initiator, or a combination thereof.

[0273] Photopolymerization initiators can be initiators commonly used in curable ink compositions, such as acetophenone compounds, benzophenone compounds, thioxanthone compounds, benzoin compounds, triazine compounds, oxime compounds, and amino ketone compounds, but are not necessarily limited to these.

[0274] Examples of acetophenone compounds include 2,2'-diethoxyacetophenone, 2,2'-dibutoxyacetophenone, 2-hydroxy-2-methylacetophenone, p-tert-butyltrichloroacetophenone, p-tert-butyldichloroacetophenone, 4-chloroacetophenone, 2,2'-dichloro-4-phenoxyacetophenone, 2-methyl-1-(4-(methylthio)phenyl)-2-(N-morpholino)prop-1-one, 2-benzyl-2-dimethylamino-1-(4-N-morpholinophenyl)but-1-one, and the like.

[0275] Examples of benzophenone compounds may include benzophenone, benzoyl benzoate, methyl benzoyl benzoate, 4-phenylbenzophenone, hydroxybenzophenone, benzophenone acrylate, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'-dimethylaminobenzophenone, 4,4'-dichlorobenzophenone, 3,3'-dimethyl-2-methoxybenzophenone, and the like.

[0276] Examples of thioxanthone compounds include thioxanthone, 2-methylthioxanthone, isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, 2-chlorothioxanthone, and the like.

[0277] Examples of benzoin compounds include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzyl dimethyl ketal, and the like.

[0278] Examples of triazine compounds include 2,4,6-trichloro-s-triazine, 2-phenyl-4,6-bis(trichloromethyl)-s-triazine, 2-(3',4'-dimethoxystyryl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4'-methoxynaphthyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(p-methoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, and 2-(p-tolyl)-4,6-bis(trichloromethyl)-s-triazine. Azides, 2-biphenyl-4,6-bis(trichloromethyl)-s-triazine, bis(trichloromethyl)-6-styryl-s-triazine, 2-(naphtho-1-yl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4-methoxynaphtho-1-yl)-4,6-bis(trichloromethyl)-s-triazine, 2-4-bis(trichloromethyl)-6-helianthyl-s-triazine, 2-4-bis(trichloromethyl)-6-(4-methoxystyryl)-s-triazine and the like.

[0279] Examples of oxime compounds may include o-acyl oxime compounds, 2-(o-benzoyl oxime)-1-[4-(phenylthio)phenyl]-1,2-octanedione, 1-(o-acetyl oxime)-1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]ethyl ketone, o-ethoxycarbonyl-α-oxoamine-1-phenylprop-1-one, and the like. Specific examples of o-oxime compounds may include 1,2-octanedione, 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-yl-phenyl)-butane-1-one, 1-(4-phenylthiophenyl)-1,2-dione-2-oxime-O-benzoate, 1-(4-phenylthiophenyl)-octane-1,2-dione-2-oxime-O-benzoate, 1-(4-phenylthiophenyl)-octane-1-one-oxime-O-acetate, 1-(4-phenylthiophenyl)-but-1-one-oxime-O-acetate, and the like.

[0280] Examples of amino ketone compounds may include 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1.

[0281] In addition to the compounds mentioned above, the photopolymerization initiator may further include carbazole compounds, diketone compounds, sulfonium borate compounds, diazo compounds, imidazole compounds, biimidazole compounds, and the like.

[0282] Photopolymerization initiators can be used with photosensitizers that can induce a chemical reaction by absorbing light, become excited, and then transfer their energy.

[0283] Examples of photosensitizers include tetraethylene glycol bis-3-mercaptopropionate, neopentyl tert-3-mercaptopropionate, dinepentyl tert-3-mercaptopropionate, and the like.

[0284] Examples of thermal polymerization initiators may be peroxides, specifically benzoyl peroxide, dibenzoyl peroxide, lauroyl peroxide, dilauryl peroxide, di-tert-butyl peroxide, cyclohexane peroxide, methyl ethyl ketone peroxide, hydrogen peroxides (e.g., tert-butyl hydroperoxide, cumene hydroperoxide), dicyclohexyl percarbonate, 2,2-azobis(isobutyronitrile), tert-butyl perbenzoate, and the like, and also 2,2'-azobis-2-methylpropionitrile and the like, but are not necessarily limited thereto and may include any compound widely known in the relevant art.

[0285] The polymerization initiator may be included in an amount of 1% to 5% by weight, for example, 2% to 4% by weight, based on the total solids content of the ink composition. When the polymerization initiator is included within this range, the ink composition can be fully cured during exposure or thermal curing and thus achieves excellent reliability.

[0286] Other additives

[0287] The curable composition according to the embodiments may further include, as needed, polymerization inhibitors comprising hydroquinone compounds, catechol compounds, or combinations thereof. Because the ink composition according to the embodiments further comprises hydroquinone compounds, catechol compounds, or combinations thereof, crosslinking at room temperature can be prevented during exposure after printing (coating) the ink composition.

[0288] For example, hydroquinone compounds, catechol compounds, or combinations thereof may include hydroquinone, methyl hydroquinone, methoxy hydroquinone, tributylhydroquinone, 2,5-bis-tributylhydroquinone, 2,5-bis(1,1-dimethylbutyl)hydroquinone, 2,5-bis(1,1,3,3-tetramethylbutyl)hydroquinone, catechol, tributylcatechol, 4-methoxyphenol, pyrogallol, 2,6-bis-tributyl-4-cresol, 2-naphthol, tris(N-hydroxy-N-nitrosoaniline-O,O')aluminum, or combinations thereof, but are not necessarily limited thereto.

[0289] Hydroquinone compounds, catechol compounds, or combinations thereof may be used in the form of dispersions, and may contain polymerization inhibitors in dispersion form in an amount of 0.001% to 1% by weight, for example, 0.01% to 0.1% by weight, based on the total amount of the ink composition. When stabilizers are included within the above range, the problem of aging at room temperature can be solved and the decrease in sensitivity and surface peeling can be prevented.

[0290] In addition to the polymerization inhibitors, the ink composition according to the embodiments may further include, as needed, malonic acid; 3-amino-1,2-propanediol; silane coupling agents; leveling agents; fluorinated surfactants; or combinations thereof.

[0291] For example, ink compositions may further include silane coupling agents having reactive substituents such as carboxyl, methacryloyl, isocyanate, epoxy, and the like to improve their adhesion to the substrate.

[0292] Examples of silane coupling agents may include trimethoxysilylbenzoic acid, γ-methpropenylpropoxytrimethoxysilane, vinyltriacetoxysilane, vinyltrimethoxysilane, γ-isocyanatepropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, β-(epoxycyclohexyl)ethyltrimethoxysilane, and the like. These substances may be used alone or in mixtures of two or more.

[0293] Based on 100 parts by weight of ink composition, a silane coupling agent may be included in an amount from 0.01 parts by weight to 10 parts by weight. When a silane coupling agent is included within the range described above, it can improve contact properties, storage properties, and the like.

[0294] In addition, the ink composition may contain more surfactants, such as fluorinated surfactants, to improve the coating and prevent defects when necessary.

[0295] An example of fluorinated surfactants is BM Chemie Inc. and MEGAFACE F of Dainippon Ink Kagaku Kogyo Co., Ltd. MEGAFACE F MEGAFACE F and MEGAFACE F Sumitomo 3M Co., Ltd. as well as Asahi Glass Co., Ltd. as well as And Toray Silicone Co., Ltd. and And similar items; F-482, F-484, F-478, F-554 and similar items of DIC Co., Ltd.

[0296] Based on 100 parts by weight of ink composition, fluorinated surfactants may be included in an amount from 0.001 parts by weight to 5 parts by weight. When fluorinated surfactants are included within this range, excellent wetting and coating uniformity on the glass substrate are ensured, and no staining is generated.

[0297] In addition, without impairing the physical properties, a certain amount of other additives, such as antioxidants and stabilizers, may be added to the ink composition.

[0298] Another embodiment provides a layer using an ink composition.

[0299] Another embodiment provides an electrophoresis apparatus and / or a display apparatus that includes the layer.

[0300] [Invention Model]

[0301] The invention is described in more detail below with reference to examples. However, these examples are not to be construed as limiting the scope of the invention in any way.

[0302] (Preparation of curable components)

[0303] Examples 1 to 6 and Comparative Examples 1 to 3

[0304] A 4-inch GaN wafer patterned with nanorods was reacted in 40 mL of stearic acid (1.5 mmol / L) at room temperature for 24 hours. Following the reaction, the nanorod-patterned GaN was immersed in 50 mL of acetone for 5 minutes to remove excess stearic acid, and additionally, the wafer surface was rinsed with 40 mL of acetone. The washed wafer was then placed in a 27 kW bath-type ultrasonic generator with 35 mL of γ-butyrolactone (GBL) and ultrasonicated for 5 minutes to separate the rods from the wafer surface. The separated rods were centrifuged in FALCON tubes, with 10 mL of GBL added for additional washing of the rods on the bath surface. The supernatant was then discarded by centrifugation at 4000 rpm for 10 minutes, and the precipitate was redispersed in 40 mL of acetone and filtered through a 10-micron mesh filter paper. After additional centrifugation (4000 rpm, 10 min), the precipitate was dried in an oven (100 °C, 1 h), weighed and dispersed to 0.2 wt% to prepare each ink composition having the compositions shown in Table 2.

[0305] (The composition of the mixed solvent and the dielectric constant and viscosity of the solvent are shown in Table 3.)

[0306] (Table 2)

[0307] (Unit: % by weight)

[0308] quantity (A) GaN nanorods 0.2 (B) Mixed solvents 99.8

[0309] (Table 3)

[0310]

[0311] *The dielectric constant of the mixed solvent was measured at room temperature (25°C) using a liquid dielectric constant measuring device (model 871, Furuto) with 40 ml of each solvent composition according to the examples and comparative examples loaded in a conical tube, and the viscosity of the solvent was measured at room temperature (25°C) using a rheometer (Haake) with 2 ml of each solvent composition loaded.

[0312] Evaluate

[0313] The viscosity of the ink compositions according to Examples 1 to 6 and Comparative Examples 1 to 3 was measured (25°C and 50°C). When the viscosity at 50°C was less than or equal to 15 centipoise, the inkjet properties (inkjet processability) were evaluated as satisfactory, and in Table 4, “O” was given when the viscosity was less than or equal to 15 centipoise, and “X” was given when the viscosity was greater than 15 centipoise.

[0314] In addition, the dielectric constant was measured at room temperature (25°C) using a dielectric constant measuring device (model 871, Ralph) and in a conical tube using 40 ml of mixed solvent composition corresponding to the ink composition, and the viscosity of the solvent was measured at room temperature (25°C) using a rheometer (Hacker) and loading 2 ml of each solvent composition.

[0315] The measurement results are shown in Table 4.

[0316] (Table 4)

[0317]

[0318] As shown in Table 4, unlike Comparative Example 3, Examples 1 to 7, as well as Comparative Examples 1 and 2, all exhibited excellent inkjet properties. However, Comparative Example 1, as a single-component system, had the problem of only achieving the viscosity, dielectric constant, and conductivity of the corresponding solvent, and Comparative Example 2, as a two-component system, had the disadvantage that when the viscosity or dielectric constant parameter was fixed by using the component ratio, the other parameter was fixed without adjustment. On the other hand, by adjusting the internal component ratio of each solvent to a viscosity range of 60 centipoise, 70 centipoise, and 80 centipoise at room temperature (25°C), Examples 1 to 7, as three-component systems, could be freely controlled to have a dielectric constant in the range of 4 to 11, while maintaining a constant viscosity at room temperature. Therefore, by further freely controlling (adjusting) the dielectric constant, Examples 1 to 7 exhibited high viscosity at room temperature, ensured storage stability, maintained excellent inkjet properties, and ensured optimal dielectric properties.

[0319] Although the invention has been described in conjunction with what are now considered practical examples, it should be understood that the invention is not limited to the disclosed embodiments, but rather is intended to cover various modifications and equivalent configurations encompassed within the spirit and scope of the appended claims. Therefore, the foregoing embodiments should be understood as illustrative and not in any way limiting the invention.

Claims

1. An ink composition comprising: (A) Semiconductor nanorods; as well as (B) A mixed solvent comprising a first solvent, a second solvent, and a third solvent. The first solvent comprises a compound having a viscosity of less than or equal to 70 centipoise at 25°C and a dielectric constant of greater than or equal to 5. The second solvent comprises a compound having a viscosity of 80 centipoise or greater at 25°C, or being a solid and having a dielectric constant of 5 or greater, and The third solvent comprises a compound having a dielectric constant of less than 5 and represented by chemical formula 3-1: [Chemical Formula 3-1] In chemical formula 3-1, R 9 To R 11 Each is independently a C1 to C20 alkyl group, either unsubstituted or vinyl-substituted.

2. The ink composition according to claim 1, wherein the first solvent has a viscosity of 3 centipoise or greater at 50°C.

3. The ink composition according to claim 1, wherein the first solvent comprises a compound represented by chemical formula 1-1 or chemical formula 1-2: [Chemical Formula 1-1] [Chemical Formula 1-2] in, In chemical formulas 1-1 and 1-2, R 1 R' is a hydrogen atom or *-C(=O)R', where R' is a hydrogen atom or a substituted or unsubstituted C1 to C10 alkyl group. R 2 To R 4 Each is independently a substituted or unsubstituted C2 to C20 alkyl group. R 5 It is a substituted or unsubstituted C1 to C20 alkyl group or a substituted or unsubstituted C6 to C20 aryl group substituted with a C2 to C10 alkoxy group. L 1 To L 3 Each is independently a substituted or unsubstituted C1 to C20 alkyl group, and n is an integer from 1 to 20.

4. The ink composition according to claim 3, wherein the compound represented by chemical formula 1-1 includes compounds represented by chemical formula 1-1-1 or chemical formula 1-1-2: [Chemical Formula 1-1-1] [Chemical Formula 1-1-2] 5. The ink composition according to claim 3, wherein the compound represented by chemical formula 1-2 includes compounds represented by one of chemical formulas 1-2-1 to 1-2-4: [Chemical Formula 1-2-1] [Chemical Formula 1-2-2] [Chemical Formula 1-2-3] [Chemical Formula 1-2-4] 6. The ink composition according to claim 1, wherein the second solvent has a viscosity of 10 centipoise or greater at 50°C or is a solid.

7. The ink composition according to claim 1, wherein the second solvent comprises a compound represented by one of chemical formulas 2-1 to 2-6: [Chemical Formula 2-1] [Chemical Formula 2-2] [Chemical Formula 2-3] [Chemical Formula 2-4] [Chemical Formula 2-5] [Chemical Formula 2-6] in, In chemical formulas 2-1 to 2-6 L 1 L 2 and L 4 To L 8 Each is independently a substituted or unsubstituted C1 to C20 alkyl group. R 1 R is a hydrogen atom or *-C(=O)R', where R' is a hydrogen atom or a substituted or unsubstituted C1 to C10 alkyl group, R 6 It is a hydroxyl group or a substituted or unsubstituted C1 to C20 alkyl group. R 7 and R 8 Each is independently a substituted or unsubstituted C1 to C20 alkyl group. R 16 and R 17 Each is independently a hydrogen atom, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, or a substituted or unsubstituted C6 to C20 aryl group. R 18 and R 19 Each is independently a hydrogen atom or *-(C=O)R 15 , where R 15 It can be a substituted or unsubstituted C1 to C20 alkyl, a substituted or unsubstituted C3 to C20 cycloalkyl, or a substituted or unsubstituted C6 to C20 aryl. R 20 It is methoxy. R 21 It is a substituted or unsubstituted C1 to C20 alkyl or a substituted or unsubstituted C1 to C20 alkoxy group. m is an integer from 1 to 4. p is an integer from 0 to 4, and q is an integer from 1 to 20.

8. The ink composition according to claim 7, wherein the compound represented by chemical formula 2-1 comprises the compound represented by chemical formula 2-1-1: [Chemical Formula 2-1-1] 9. The ink composition according to claim 7, wherein the compound represented by chemical formula 2-2 comprises the compound represented by chemical formula 2-2-1: [Chemical Formula 2-2-1] 10. The ink composition according to claim 7, wherein the compound represented by chemical formula 2-3 includes compounds represented by one of chemical formulas 2-3-1 to 2-3-3: [Chemical Formula 2-3-1] [Chemical Formula 2-3-2] [Chemical Formula 2-3-3] 11. The ink composition according to claim 7, wherein the compound represented by chemical formula 2-4 includes the compound represented by chemical formula 2-4-1: [Chemical Formula 2-4-1] 12. The ink composition according to claim 7, wherein the compound represented by chemical formula 2-5 includes compounds represented by one of chemical formula 2-5-1 and chemical formula 2-5-2: [Chemical Formula 2-5-1] [Chemical Formula 2-5-2] 13. The ink composition according to claim 7, wherein the compound represented by chemical formula 2-6 includes compounds represented by one of chemical formulas 2-6-1 to 2-6-3: [Chemical Formula 2-6-1] [Chemical Formula 2-6-2] [Chemical Formula 2-6-3] 14. The ink composition according to claim 1, wherein the third solvent has a viscosity of 70 centipoise or more at 25°C or is a solid, and has a viscosity of 3 centipoise or more at 50°C.

15. The ink composition according to claim 1, wherein the compound represented by chemical formula 3-1 comprises the compound represented by chemical formula 3-1-1: [Chemical Formula 3-1-1] 16. The ink composition according to claim 1, wherein The first solvent is contained in an amount of 10 to 50 parts by weight, based on 100 parts by weight of the mixed solvent. The second solvent is contained in an amount of 10 to 40 parts by weight, based on 100 parts by weight of the mixed solvent, and The third solvent is contained in an amount of 20 to 50 parts by weight, based on 100 parts by weight of the mixed solvent.

17. The ink composition according to claim 1, wherein the semiconductor nanorods have a diameter of 300 nanometers to 900 nanometers.

18. The ink composition of claim 1, wherein the semiconductor nanorods have a length of 3.5 micrometers to 5 micrometers.

19. The ink composition according to claim 1, wherein the semiconductor nanorod comprises GaN-based compounds, InGaN-based compounds, or combinations thereof.

20. The ink composition according to claim 1, wherein the surface of the semiconductor nanorod is coated with a metal oxide.

21. The ink composition of claim 20, wherein the metal oxide comprises aluminum oxide, silicon oxide, or a combination thereof.

22. The ink composition according to claim 1, wherein the semiconductor nanorods are contained in an amount of 0.01% to 10% by weight, based on the total amount of the ink composition.

23. The ink composition according to claim 1, wherein the ink composition further comprises malonic acid; 3-amino-1,2-propanediol; silane coupling agent; leveling agent; fluorinated surfactant or a combination thereof.

24. The ink composition according to claim 1, wherein the ink composition is an ink composition for an electrophoresis apparatus.

25. A layer manufactured using an ink composition as described in any one of claims 1 to 24.

26. An electrophoresis apparatus comprising the layer as described in claim 25.

27. A display device comprising the layer as claimed in claim 25.

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