Decorative inks and their uses

Abstract

To provide a technology capable of forming, on an inorganic base material, a decorative part whose magenta color developability is suitably improved.SOLUTION: An ornamental ink disclosed here is an ornamental ink used for drawing images on a glass base material or a metal base material. The ornamental ink includes a glass frit including metal particles, and an inorganic red pigment. The ornamental ink contains 1 vol% or more and less than 80 vol% of the inorganic red pigment when a total volume of an inorganic solid component including the glass frit and the inorganic red pigment is 100 vol%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to decorative inks and their uses. [Background technology]

[0002] In recent years, techniques for drawing images on inorganic substrates such as glass substrates, ceramic substrates (e.g., porcelain, ceramic tiles), and metal substrates have been developed. When drawing such images, various colored inks can be used. For example, Patent Document 1 listed below discloses a technique related to colored ink (red ink). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-007384 Summary of the Invention [Problem to be solved by the invention]

[0004] The present inventors have discovered that glass frit containing gold particles (hereinafter simply referred to as "gold-containing glass") can be preferably used as a coloring material for magenta (reddish-purple) ink. Meanwhile, they have found that with magenta ink containing gold-containing glass, it is necessary to further improve the hiding power and magenta coloring of the fired film (i.e., decorative portion) in order to render a clear image on, for example, a transparent glass substrate or a colored metal substrate.

[0005] The present disclosure has been made in consideration of the above circumstances, and its main purpose is to provide a technology that can form a decorative part with suitably improved magenta coloring properties on an inorganic substrate (typically a glass substrate or a metal substrate). [Means for solving the problem]

[0006] To achieve this objective, the present disclosure provides a decorative ink used to depict images on glass or metal substrates. This decorative ink includes a glass frit containing gold particles and a red inorganic pigment. Furthermore, when the total volume of the inorganic solid components including the glass frit and the red inorganic pigment is taken as 100 volume %, the red inorganic pigment accounts for 1 volume % or more and less than 80 volume %. As will be described in more detail below, a decorative ink with this configuration can form a decorative portion on an inorganic substrate with favorably improved magenta coloring.

[0007] In a preferred embodiment of the decorative ink disclosed herein, the red inorganic pigment is contained in an amount of 5% by volume or more and less than 70% by volume, assuming the total volume of the inorganic solid components to be 100% by volume. A decorative ink containing a red inorganic pigment within this range is preferred because it suitably improves the fixation of the decorative portion to the inorganic substrate.

[0008] In a preferred embodiment of the decorative ink disclosed herein, the red inorganic pigment does not contain cadmium. Cadmium-based inorganic pigments have traditionally been used as colorants for red inks, but such inorganic pigments are believed to have the potential to adversely affect the human body. Therefore, a cadmium-free embodiment is preferred from the standpoint of safety for the human body.

[0009] In a preferred embodiment of the decorative ink disclosed herein, the red inorganic pigment has a color reproducibility of 100% or more based on a spectrophotometer. * The value is a * >10. * In a decorative ink containing a red inorganic pigment having a color reproducibility of >10, a decorative portion having more suitably improved magenta coloring can be formed on the inorganic substrate, which is preferred.

[0010] In one embodiment of the decorative ink disclosed herein, the decorative ink is an inkjet ink, and when the total volume of the inkjet ink is taken as 100 volume %, the inorganic solid component is contained in an amount of 35 volume % or less. When the decorative ink is an inkjet ink, it is preferable that the inorganic solid component be contained in an amount of 35 volume % or less, from the viewpoint of ensuring that the viscosity of the inkjet ink is appropriate.

[0011] In a preferred embodiment of the decorative ink, the glass frit has an average particle size of 1 μm or less. From the viewpoint of the ejection properties of the inkjet ink, it is preferable that the average particle size of the glass frit is adjusted to 1 μm or less.

[0012] In a preferred embodiment of the photosensitive composition disclosed herein, the composition further contains a photocurable monomer component. The use of a decorative ink with good curability upon irradiation with ultraviolet light is preferred because it allows for clearer images to be depicted on, for example, water-repellent transfer paper coated with a water-soluble adhesive.

[0013] In another aspect, the present disclosure provides a printed matter bearing an image depicting the decorative ink of any one of the presently disclosed decorative inks. Such a printed matter is preferable because it comprises an image (decorative portion) with suitably improved magenta color development.

[0014] In another aspect, the present disclosure provides transfer paper bearing an image formed from any of the decorative inks disclosed herein. Such transfer paper is preferable because it bears an image (decorative portion) with suitably improved magenta color development.

[0015] In another aspect, the present disclosure provides a method for manufacturing an inorganic product. The method for manufacturing such an inorganic product includes a decorating step of applying decoration to the surface of an inorganic substrate using any of the decorative inks disclosed herein. This manufacturing method is preferable because it can produce an inorganic product having an image (decorative portion) with suitably improved magenta color development.

[0016] In one embodiment of the method for producing an inorganic product disclosed herein, the decorating step includes the following steps: depositing a cured product of any of the decorative inks disclosed herein on the surface of an inorganic substrate; and firing the inorganic substrate under conditions in which the maximum firing temperature is set within the range of 350°C to 700°C. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a diagram schematically illustrating an agitator / pulverizer used in the production of inkjet ink. [Figure 2] FIG. 1 is a diagram schematically illustrating an example of an inkjet device. [Figure 3] FIG. 3 is a cross-sectional view schematically showing an inkjet head of the inkjet device in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0018] Preferred embodiments of the present disclosure are described below. Matters necessary for implementing the present disclosure, other than those specifically mentioned in this specification, can be understood as design matters for a person skilled in the art based on the prior art in the relevant field. The present disclosure can be implemented based on the contents disclosed in this specification and the common general technical knowledge in the relevant field. The following embodiments are not intended to limit the technology disclosed herein. In the drawings shown in this specification, components and parts that perform the same function are denoted by the same reference numerals. Dimensional relationships (length, width, thickness, etc.) in each drawing do not reflect actual dimensional relationships. In this specification and claims, when a given numerical range is expressed as A to B (A and B are arbitrary numbers), it means A or more and B or less. Therefore, it also includes cases where the range is greater than A and less than B. In this specification and claims, the term "decorative ink" typically refers to a composition in which inorganic solid components, such as glass frit or red inorganic pigments, are dispersed (or dissolved) in a medium, and is a concept that can encompass paste-like compositions and slurry-like compositions.

[0019] 1. Decorative ink The decorative ink (magenta ink) disclosed herein is a decorative ink used to draw images on inorganic substrates (typically glass or metal substrates). This decorative ink contains glass frit containing gold particles (i.e., gold-containing glass) and a red inorganic pigment. When the total volume of the inorganic solid components including the glass frit and the red inorganic pigment is taken as 100 volume %, the red inorganic pigment accounts for 1 volume % or more and less than 80 volume %.

[0020] The reason why the above-described configuration achieves the effects of the technology disclosed herein is thought to be, but is not limited to, the following: That is, the decorative ink (magenta ink) contains a predetermined amount of red inorganic pigment in addition to the gold-containing glass, and thus the L in the decorative portion * a * b * Based on the color system a * value,b * The value can be set within a more appropriate range. Also, the concealing property of the decorative portion can be improved. As a result, a clear image with excellent magenta color development can be depicted, even on a transparent glass substrate or a colored metal substrate. Note that the above explanation is the inventor's consideration based on experimental results, and the technology disclosed herein should not be interpreted as being limited to the above mechanism. Each component will be explained below.

[0021] (1) Inorganic solid components The inorganic solid components are components that constitute the base material of the image after firing, and include glass frit and red inorganic pigments.

[0022] (a) Glass frit The glass frit disclosed herein contains gold particles. Specifically, the gold particles are dispersed in an amorphous matrix (hereinafter simply referred to as "glass matrix") in the glass frit. The glass component and the gold particles are typically sintered together to form a sintered body.

[0023] The glass matrix is ​​a component that typically functions as an inorganic binder and serves to enhance the bonding between the gold particles and the glass substrate. The linear thermal expansion coefficient of the glass constituting the glass matrix (specifically, the average linear thermal expansion coefficient measured in a temperature range from 25°C to 500°C using a thermomechanical analyzer; the same applies hereinafter) is not particularly limited as long as the effects of the technology disclosed herein are exhibited, but may be, for example, equivalent to that of the glass substrate. In one example, the thermal expansion coefficient of the glass is the thermal expansion coefficient of the glass substrate ±2×10 ―6 K ―1 For example, 4.0×10 ―6 K ―1 ~10.0×10 ―6 K ―1 This reduces the difference in shrinkage rate between the glass substrate and the glass frit during firing to decorate, making it less likely that cracks will occur in the decorative portion.

[0024] The glass transition point (Tg value determined by differential scanning calorimetry, the same applies hereinafter) of the glass constituting the glass matrix is ​​not particularly limited as long as the effects of the technology disclosed herein are exhibited. For example, in relation to the sintering temperature described below, a glass transition point of approximately 400 to 1500°C is preferable. In particular, for underglaze and sink-in applications, a glass transition point of approximately 900 to 1300°C is preferable, and for overglaze applications, a glass transition point of approximately 500 to 900°C is preferable.

[0025] Examples of glasses that can have such properties (thermal expansion coefficient and glass transition point) include SiO2-RO (RO represents an oxide of a Group 2 element, such as MgO, CaO, SrO, or BaO; the same applies hereinafter)-based glasses, SiO2-RO-R2O (R2O represents an oxide of an alkali metal element, such as Li2O, Na2O, KO, Rb2O, Cs2O, or Fr2O, particularly Li2O; the same applies hereinafter)-based glasses, SiO2-RO-ZnO-based glasses, SiO2-RO-ZrO2-based glasses, SiO2-RO-Al2O3-based glasses, SiO2-RO-Bi2O3-based glasses, SiO2-R2O-based glasses, SiO2-ZnO-based glasses, SiO2-ZrO2-based glasses, SiO2-ZnO-ZrO2-TiO2-based glasses, SiO2-Al2O3-based glasses, RO-R2O-based glasses, and RO-ZnO-based glasses. These glasses may contain one or more components in addition to the main components indicated in the names above. Furthermore, the glasses may be general amorphous glasses or crystallized glasses containing crystals.

[0026] In a preferred embodiment, when the entire glass is taken as 100 mol %, SiO2 accounts for more than half (50 mol %) in terms of the molar ratio calculated as oxide. Generally, the higher the SiO2 ratio, the higher the glass transition temperature tends to be. Therefore, for example, when the sintering temperature is set low, it is advisable to keep the SiO2 ratio at approximately 80 mol % or less. Furthermore, from the viewpoint of lowering the glass transition temperature and improving the meltability of the glass, it is effective to add components such as RO, R2O, and B2O3. On the other hand, the greater the content of these components, the higher the thermal expansion coefficient of the glass tends to be. In a preferred embodiment, when the entire glass is taken as 100 mol %, RO accounts for 15 to 35 mol % in terms of the molar ratio calculated as oxide. In a preferred embodiment, when the entire glass is taken as 100 mol %, RO accounts for 0 to 5 mol % in terms of the molar ratio calculated as oxide.

[0027] In a preferred embodiment, the glass is composed of a multi-component system of four or more components (e.g., five or more components). This improves physical stability. For example, when used to decorate tableware, the decorative part must also have sufficient acid resistance against acidic foods and sufficient alkali resistance against alkaline detergents. In such cases, it is effective to add components such as Al2O3, ZnO, and CaO, for example, in a proportion of 100% by mole or more. This can improve the chemical durability of the decorative part. Preferably, it can also improve abrasion resistance.

[0028] The proportion of the glass matrix in the decorative ink is not particularly limited as long as the effects of the technology disclosed herein are achieved. From the perspective of enhancing the bond with the glass substrate, the proportion of the glass matrix should be approximately 1% by volume or more, typically 5% by volume or more, for example 10% by volume or more, when the decorative ink as a whole is taken as 100% by volume. From the perspective of improving the adhesion of the decorative portion to the inorganic substrate, the proportion of the glass matrix should be approximately 40% by volume or less, typically 30% by volume or less, for example 20% by volume or less, when the decorative ink as a whole is taken as 100% by volume.

[0029] In a preferred embodiment, the glass matrix is ​​substantially free of components that may be harmful to the human body or the environment, such as arsenic, lead, and cadmium. In particular, when used to decorate tableware, it is preferable not to actively add these components (although their inclusion as unavoidable impurities may be tolerated).

[0030] As described above, the glass frit disclosed herein contains gold particles. Metal particles have unique optical characteristics (e.g., a strong light absorption band) in the ultraviolet to visible region due to surface plasmon resonance (SPR). Among these, gold (Au) particles absorb light with a wavelength around 530 nm (green to light blue light) and exhibit a bluish-red (reddish-purple) color known as "magenta." Therefore, glass frit containing gold particles can produce a vivid magenta color.

[0031] Here, in this specification and claims, "gold particles" can refer to particles composed primarily of gold (Au). "Composed primarily of gold" means that, of the components constituting the particles, gold (Au) is the component that is contained in the greatest amount by weight. When the total weight of the particles is taken as 100% by weight, the gold particles can be particles that preferably contain 90% by weight or more, 95% by weight or more, or 99% by weight or more of gold (Au). Components other than gold include various metallic elements and non-metallic elements as unavoidable impurities.

[0032] The shape of the gold particles is not particularly limited and may be spherical or aspherical. The average particle size (D50 particle size) of the gold particles is not particularly limited as long as the effects of the technology disclosed herein are exhibited. However, taking into account the above-mentioned surface plasmon resonance, the particle size is preferably nanometer-sized. The effect of surface plasmon resonance of gold particles can vary depending on the particle size. Therefore, by appropriately adjusting the particle size, the effect of surface plasmon resonance can be more effectively achieved. In a preferred embodiment, the average particle size of the gold particles is approximately 1 nm or more, 5 nm or more, typically 10 nm or more, for example, 15 nm or more. In a preferred embodiment, the average particle size of the gold particles is, for example, 100 nm or less, 80 nm or less, typically 50 nm or less, for example, 30 nm or less. By setting the average particle size within the above range, the absorbance of the gold particles at a specific wavelength is increased, allowing for good magenta color development with a small amount of addition. Furthermore, a dense decoration with little color unevenness can be achieved.

[0033] The shape of the glass frit is not particularly limited and may be spherical or non-spherical. The average particle size (D50 particle size) of the glass frit is not particularly limited as long as the effects of the technology disclosed herein are achieved, but it can be approximately 0.1 μm to 10 μm (e.g., approximately 0.5 μm to 5 μm). When the decorative ink is used as an inkjet ink, the particle size of the glass frit can affect the viscosity of the ink, so it is preferable to appropriately adjust the particle size taking into account the ejection properties from the inkjet device. Specifically, if the ink contains glass frit with a large particle size, clogging of the ejection orifices may occur easily, which may result in reduced ejection properties. Therefore, it is preferable to control the particle size of the glass frit so that the average particle size of the glass frit is, for example, 1 μm or less (preferably 0.85 μm or less).

[0034] In this specification, the term "average particle size" (D50 particle size) refers to the particle size corresponding to the 50% cumulative value from the smallest particle size in a volume-based particle size distribution based on a laser diffraction / scattering method. Such measurements can be performed using, for example, a commercially available device, Microtrac MT3000II manufactured by Microtrac Bell Corporation.

[0035] The proportion of gold particles in the decorative ink is not particularly limited as long as the effects of the technology disclosed herein are achieved. From the viewpoints of improving magenta color development and cost, the proportion is preferably approximately 0.01% by volume or more, for example, 0.05% by volume or more, or 0.1% by volume or more, and approximately 0.5% by volume or less, typically 0.3% by volume or less, for example, 0.2% by volume or less, when the decorative ink as a whole is taken as 100% by volume.

[0036] In a preferred embodiment, the ratio of gold particles is approximately 0.1 parts by volume or more, preferably 0.5 parts by volume or more, for example, 1 part by volume or more, when the glass matrix is ​​taken as 100 parts by volume. By setting the ratio of gold particles to a predetermined value or more, L * a * b * In the color system, a in the red direction *It is possible to improve the lightness L * In a preferred embodiment, the ratio of gold particles is approximately 5 parts by volume or less, typically 3 parts by volume or less, and preferably 2 parts by volume or less, when the glass matrix is ​​taken as 100 parts by volume. By setting the ratio of gold particles to a predetermined value or less, L * a * b * In the color system, lightness L * It improves print quality, allows for brighter, more vibrant colors, and keeps costs down.

[0037] (b) Red inorganic pigments As described above, the decorative ink (magenta ink) disclosed herein contains a red inorganic pigment in addition to a metal-containing glass. Such a red inorganic pigment may be, for example, in a form sintered integrally with glass frit, or in a form that does not constitute a glass matrix (in other words, has a melting point higher than that of glass frit). Alternatively, the decorative ink may contain both of these forms of red inorganic pigment. Furthermore, in this specification and claims, the term "red inorganic pigment" refers to a red inorganic pigment that is measured, for example, using a spectrophotometer, based on the L of JIS Z8729 (2004). * a * b * a, which indicates redness in the color system * It may refer to an inorganic pigment having a value of typically 5 or more and 60 or less (preferably 10 or more (e.g., more than 10), more preferably 15 or more, 17 or more, and even more preferably more than 20. * The value can be measured using a commercially available device. * It is preferable to determine the conditions for measuring the value by appropriately referring to the catalog of the device, etc.

[0038] The inventors' research has revealed that gold particles contained in glass frits can be deformed by shear forces during particle size control, which tends to impair the color development of the glass frits themselves. Furthermore, high-temperature firing is required for gold particles to recover their shape. For example, firing at temperatures below 700°C can result in difficulty in achieving sufficient color development. Therefore, when decorating substrates with low heat resistance, it is difficult to achieve sufficient color development when using such glass frits alone as a coloring material. Furthermore, the inventors' research has revealed that excellent magenta color development can be achieved by adding a red inorganic pigment to the glass frit described above.

[0039] The red inorganic pigment can improve the magenta coloring and hiding power of the decorative portion. Furthermore, such red inorganic pigments contain, for example, metal compounds and typically have excellent heat resistance. Therefore, when a glass substrate to which ink has been applied is subjected to a baking treatment at 350°C or higher (e.g., 350°C to 700°C), the red inorganic pigment can be prevented from discoloring (or fading). Specific examples of such red inorganic pigments include composite metal compounds containing at least one metal element selected from the group consisting of Cu, Mn, Zr, Ti, Pr, Cr, Sb, Ni, Co, Al, and Cd. Examples of red inorganic pigments include tin-sphene-based, zinc ferrite-based, and zircon-based pigments. One type of red inorganic pigment may be used alone, or two or more types may be used in combination. Furthermore, commercially available red inorganic pigments can be used without particular limitation. Examples of such red inorganic pigments include M-81, M-309, M-663, and M-797 manufactured by Nitto Pigment Co., Ltd., and 42-117A, 42-129A, 42-554A, and 42-878A manufactured by Tomatec Corporation.

[0040] The shape of the red inorganic pigment is not particularly limited and may be spherical or non-spherical. From the viewpoint of ease of handling, the red inorganic pigment is typically preferably spherical. The average particle size (D50 particle size) of the red inorganic pigment is also not particularly limited as long as the effects of the technology disclosed herein are achieved. The D50 particle size of the red inorganic pigment is typically about 0.001 μm to 4 μm (e.g., about 0.005 μm to 2 μm). The red inorganic pigment may typically be in a particulate form. When using the decorative ink as an inkjet ink, the particle size of such a particulate red inorganic pigment is preferably adjusted appropriately taking into account the diameter of the nozzle of the inkjet device described below. If the particle size of the red inorganic pigment is too large, the red inorganic pigment may clog the nozzle, resulting in reduced ink ejection performance. Since the diameter of the discharge port of a typical inkjet device is about 15 μm to 60 μm (for example, 25 μm), it is preferable to microparticulate the red inorganic pigment so that the D100 particle size (maximum particle size) corresponding to 100% cumulative number from the smallest particle size is 5 μm or less (preferably 1 μm or less). The D100 particle size can be a value measured based on particle size distribution measurement by dynamic light scattering.

[0041] The proportion of red inorganic pigment in the decorative ink is not particularly limited, but it is preferably about 0.1% by volume or more, 0.5% by volume or more, for example 0.9% by volume or more, when the decorative ink as a whole is taken as 100% by volume. From the perspective of enhancing gloss and shine, it is also preferably about 20% by volume or less, for example 15% by volume or less, 12% by volume or less, when the decorative ink as a whole is taken as 100% by volume.

[0042] In a preferred embodiment, the red inorganic pigment is substantially free of components that may be harmful to the human body or the environment, such as arsenic, lead, or cadmium (though their inclusion as unavoidable impurities may be acceptable). It is particularly preferable for applications such as tableware decoration to be free of these components. Generally, in order to achieve favorable magenta color development in decorative inks, it is preferable to include a red inorganic pigment containing cadmium. However, as mentioned above, cadmium can have adverse effects on the human body and the environment, so it is considered preferable for decorative inks not to include cadmium. The decorative ink disclosed herein is characterized by including a gold-containing glass in addition to the red inorganic pigment. By including a gold-containing glass that favorably develops magenta color in the decorative ink, it is possible to favorably develop magenta color even when using a red inorganic pigment that does not contain cadmium.

[0043] (2) Other ingredients The decorative ink disclosed herein may contain other components as appropriate, as long as the effects of the technology disclosed herein are achieved. Examples of other components include dispersants, monomer components, photopolymerization initiators, polymerization inhibitors, organic binders, reaction accelerators, surfactants, thickeners, pH adjusters, preservatives, antifoaming agents, plasticizers, stabilizers, and oxidation inhibitors. For example, the monomer components and dispersants can serve as liquid components that disperse (or dissolve) inorganic solid components such as glass frit and red inorganic pigments.

[0044] (a) Monomer component The decorative ink disclosed herein may contain a monomer component. Examples of such a monomer component include thermosetting monomers and photocurable monomers. As the monomer component, any monomer that can be used in a typical decorative ink can be used without particular limitation, as long as the effects of the present disclosure are not significantly impaired. Furthermore, a monomer component that is liquid at room temperature (typically, about 25°C) is preferably used. The weight-average molecular weight of the monomer component is not particularly limited as long as the effects of the technology disclosed herein are exhibited, but it can be approximately 500 to 5,000 (e.g., about 1,000 to 3,000). In this specification, the term "weight-average molecular weight" refers to the weight-average molecular weight measured by gel permeation chromatography (GPC) and converted using a standard polystyrene calibration curve. The monomer component may be used alone or in combination of two or more types. Furthermore, commercially available products can be used as the monomer component without particular limitation.

[0045] In this case, it is preferable to include a photocurable monomer as a monomer component, since this allows for clearer images to be drawn on, for example, water-repellent transfer paper coated with a water-soluble adhesive. Here, the term "photocurable monomer component" as used herein refers to a material containing at least one resin monomer that polymerizes (or crosslinks) and hardens when irradiated with light (e.g., ultraviolet light).

[0046] Suitable examples of the photocurable monomer component include (a1) a monofunctional acrylate monomer, (a2) a monofunctional N-vinyl compound monomer, and (a3) ​​a polyfunctional vinyl ether monomer. A photocurable monomer component containing at least one of the monomers (a1) to (a3) ​​has excellent fixability (photocurability) to a printing object, and therefore can be suitably used for various printing objects. Furthermore, a photocurable monomer component containing at least one of the monomers (a1) to (a3) ​​also has the advantage of excellent flexibility after photocuring, and therefore can be suitably used for printing objects that need to be curved during use (for example, transfer paper).

[0047] (a1) Monofunctional acrylate monomer Monofunctional acrylate monomers are compounds containing one acryloyl group (CH2=CHCOO-) or one methacryloyl group (CH2=CCH3COO-) in the molecule. Such monofunctional acrylate monomers have excellent dispersibility of inorganic solid components and can suppress an increase in ink viscosity, contributing to the preparation of ink with favorable jetting properties. Furthermore, among photocurable monomers, monofunctional acrylate monomers also have the characteristic of having relatively low rigidity (high flexibility) after photocuring. From the perspective of further improving jetting properties and flexibility, the volume ratio of the monofunctional acrylate monomer, when the total volume of the photocurable monomer components is taken as 100 volume%, is preferably 40 volume% or more, more preferably 45 volume% or more, even more preferably 50 volume% or more, and particularly preferably 55 volume% or more, for example, 60 volume% or more. On the other hand, since monofunctional acrylate monomers tend to have relatively low photocurability, from the viewpoint of ensuring the content of monomers with excellent photocurability, which will be described later, the content is preferably 96% by volume or less, more preferably 90% by volume or less, even more preferably 85% by volume or less, and particularly preferably 80% by volume or less, for example, 78% by volume or less.

[0048] Specific examples of monofunctional acrylate monomers include benzyl acrylate, cyclic trimethylolpropane formal acrylate, phenoxyethyl acrylate, isobornyl acrylate, tetrahydrofurfuryl acrylate, methoxyethyl acrylate, cyclohexyl acrylate, ethyl carbitol acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, 4-hydroxybutyl acrylate, methyl (meth)acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, pentyl acrylate, n-stearyl acrylate, butoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, isobornyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate. acrylate, 2-hydroxybutyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, isoamyl acrylate, lauryl (meth)acrylate, octyl acrylate, isooctyl (meth)acrylate, isononyl acrylate, decyl acrylate, isodecyl acrylate, tridecyl (meth)acrylate, isomyristyl acrylate, isostearyl acrylate, 2-ethylhexyl acrylate, 2-ethylhexyl-diglycol acrylate, 4-hydroxybutyl acrylate, methoxydiethylene glycol acrylate, methoxytriethylene glycol acrylate, ethoxydiethylene glycol acrylate, 2-(2-ethoxyethoxy)ethyl acrylate, 2-ethylhexyl carbitol acrylate, phenoxyethoxyethyl acrylate, etc. The above-mentioned (meth)acrylate compounds can be used alone or in combination of two or more. Among these, benzyl acrylate, phenoxyethyl acrylate, and cyclic trimethylolpropane formal acrylate are particularly excellent in flexibility after photocuring, and can therefore suitably prevent cracks from occurring when the transfer paper is bent.

[0049] (a2) Monofunctional N-vinyl compound monomer A monofunctional N-vinyl compound monomer is a compound in which one vinyl group is bonded to the nitrogen (N) atom of a nitrogen-containing compound. The "vinyl group" here refers to the group CH2=CR 1 -(where R 1 represents a hydrogen atom or an organic group). Such monofunctional N-vinyl compound monomers have high extensibility, thereby preventing cracks from occurring in the drawn image. Furthermore, monofunctional N-vinyl compound monomers have excellent photocurability and function to improve fixation to the surface of the printed object. From the viewpoint of further improving fixation, the volume ratio of the monofunctional N-vinyl compound monomer, when the total volume of the photocurable monomer components is taken as 100 volume%, is preferably 2 volume% or more, more preferably 3 volume% or more, even more preferably 4 volume% or more, and particularly preferably 5 volume% or more. On the other hand, the addition of a monofunctional N-vinyl compound monomer tends to reduce the flexibility of the ink after curing. Therefore, when printing on transfer paper or the like, it is preferable to reduce the content of the monofunctional N-vinyl compound monomer. From this viewpoint, the volume ratio of the monofunctional N-vinyl compound monomer is preferably 20 volume% or less, more preferably 17 volume% or less, even more preferably 15 volume% or less, particularly preferably 13 volume% or less, for example, 10 volume% or less.

[0050] The N-vinyl compound monomer is represented by, for example, the following general formula (I). CH2=CR 1 -NR 2 R 3 (I) In the above general formula (I), R 1 R is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a phenyl group, a benzyl group, or a halogen group. Among these, a hydrogen atom or an alkyl group having 1 to 4 carbon atoms is preferred, and a hydrogen atom is particularly preferred. 2 ,R 3can be a group selected from a hydrogen atom, an alkyl group which may have a substituent, an alkenyl group, an alkynyl group, an aralkyl group, an alkoxy group, an alkoxyalkyl group, an alkylol group, an acetyl group (CHCO-), and an aromatic group. 2 ,R 3 may be the same or different. The total number of carbon atoms in the alkyl group, alkenyl group, alkynyl group, aralkyl group, alkoxy group, alkoxyalkyl group, alkylol group, and acetyl group, which may have a substituent, may be 1 to 20. The alkyl group, alkenyl group, alkynyl group, aralkyl group, alkoxy group, alkoxyalkyl group, alkylol group, and acetyl group, which may have a substituent, may be linear or cyclic, but linear is preferred. The aromatic group is an aryl group, which may have a substituent. The total number of carbon atoms in the aromatic group is 6 to 36. The substituents that the alkyl group, alkenyl group, alkynyl group, aralkyl group, alkoxy group, alkoxyalkyl group, alkylol group, acetyl group, and aromatic group may have include, for example, a hydroxyl group and a halogen atom such as a fluorine atom or a chlorine atom. In the above general formula (I), R 2 and R 3 may be bonded to each other to form a cyclic structure.

[0051] Suitable examples of the monofunctional N-vinyl compound monomer include N-vinyl-2-caprolactam, N-vinyl-2-pyrrolidone, N-vinyl-3-morpholinone, N-vinylpiperidine, N-vinylpyrrolidine, N-vinylaziridine, N-vinylazetidine, N-vinylimidazole, N-vinylmorpholine, N-vinylpyrazole, N-vinylvalerolactam, N-vinylcarbazole, N-vinylphthalimide, N-vinylformamide, N-vinylacetamide, N-methyl-N-vinylformamide, N-methyl-N-vinylacetamide, etc. Among these, N-vinyl-2-caprolactam has high photocurability among monofunctional N-vinyl compound monomers and can more suitably improve fixation to the surface of the printing target.

[0052] (a3) Multifunctional vinyl ether monomer A polyfunctional vinyl ether monomer is a compound containing at least two vinyl ether groups in the molecule. The "vinyl ether group" here refers to a -O-CH=CHR 1 (where R 1 represents a hydrogen atom or an organic group). Such polyfunctional vinyl ether monomers containing at least two vinyl ether groups have a fast photocuring rate upon UV irradiation and excellent photocuring properties, thereby improving fixation to the surface of the printed object. Furthermore, among monomers with excellent photocuring properties, polyfunctional vinyl ether monomers have the property of low rigidity after curing and excellent flexibility. From the viewpoint of achieving both fixation to the printed object and flexibility after photocuring, the volume ratio of the polyfunctional vinyl ether monomer, when the total volume of the monomer components is taken as 100% by volume, is preferably 2% by volume or more, more preferably 5% by volume or more, even more preferably 7% by volume or more, and particularly preferably 10% by volume or more, for example, 15% by volume or more. On the other hand, adding too much polyfunctional vinyl ether monomer tends to reduce the amount of monofunctional acrylate monomer added, resulting in reduced flexibility after photocuring. Therefore, the upper limit of the volume ratio of the polyfunctional vinyl ether monomer is preferably 40% by volume or less, more preferably 35% by volume or less, even more preferably 30% by volume or less, and particularly preferably 25% by volume or less, for example, 20% by volume or less.

[0053] Suitable examples of the polyfunctional vinyl ether monomer include ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, tetraethylene glycol divinyl ether, polyethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, tripropylene glycol divinyl ether, polypropylene glycol divinyl ether, butanediol divinyl ether, neopentyl glycol divinyl ether, hexanediol divinyl ether, nonanediol divinyl ether, 1,4-cyclohexanedimethanol divinyl ether, etc. Among these, diethylene glycol divinyl ether, triethylene glycol divinyl ether, and 1,4-cyclohexanedimethanol divinyl ether are particularly preferred because they can achieve both high levels of fixation to the substrate surface and flexibility after photocuring.

[0054] (a4) Other photocurable monomers As mentioned above, the photocurable monomer component in the decorative ink disclosed herein can be any photocurable monomer component that can be used in general decorative inks, and is not limited to the monomers (a1) to (a3) ​​described above. An example of a monomer (other monomer) other than the above (a1) to (a3) ​​is a polyfunctional acrylate monomer containing at least two acryloyl or methacryloyl groups in the molecule. Suitable examples of this polyfunctional acrylate monomer include 1,9-nonanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, tricyclodecane dimethanol diacrylate, hydroxypivalic acid neopentyl glycol diacrylate, triethylene glycol di(meth)acrylate, tetramethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and 1,3-butanediol di(meth)acrylate. , neopentyl glycol di(meth)acrylate, hexanediol di(meth)acrylate, cyclohexane-1,4-dimethanol di(meth)acrylate, cyclohexane-1,3-dimethanol di(meth)acrylate, 1,4-cyclohexanediol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, dipentaerythritol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, bisphenol AEO3.8-mol adduct diacrylate, trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethyloloctane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, trimethylolpropane polyethoxy tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol propionate tri(meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, sorbitol tri(meth)acrylate, ditrimethylol Examples include propane tetra(meth)acrylate, pentaerythritol polyethoxytetra(meth)acrylate, pentaerythritol polyproxytetra(meth)acrylate, sorbitol tetra(meth)acrylate, dipentaerythritol propionate tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, sorbitol penta(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and sorbitol hexa(meth)acrylate. Furthermore, examples of other monomers other than the polyfunctional acrylate monomers include butyl vinyl ether, butyl propenyl ether, butyl butenyl ether, hexyl vinyl ether, ethylhexyl vinyl ether, phenyl vinyl ether, benzyl vinyl ether, phenyl allyl ether, vinyl acetate, acrylamide, methacrylamide, trimethylolpropane tri((meth)acryloyloxypropyl)ether, tri((meth)acryloyloxyethyl)isocyanurate, and bisphenol A diglycidyl ether acrylic acid adduct.

[0055] From the viewpoint of achieving both fixability to the printing target and flexibility after photocuring, the volume ratio of the other photocurable monomers when the total volume of the photocurable monomer components is taken as 100% by volume is preferably 2% by volume or more, more preferably 5% by volume or more, even more preferably 7% by volume or more, particularly preferably 10% by volume or more, for example 15% by volume or more. The upper limit of the volume ratio of the other photocurable monomers is preferably 40% by volume or less, more preferably 35% by volume or less, even more preferably 30% by volume or less, particularly preferably 25% by volume or less, for example 20% by volume or less.

[0056] When using a photocurable monomer component containing the monomers (a1) to (a4) described above, the volume ratio of the photocurable monomer component, when the total volume of the decorative ink is taken as 100 volume %, is preferably 30 volume % or more, more preferably 40 volume % or more, and even more preferably 50 volume % or more. This allows for a high level of both fixability to the surface of the printing object and flexibility after fixation. Furthermore, from the viewpoint of ensuring a sufficient content of inorganic solid components and forming an image with excellent gloss and color development, the volume ratio of the photocurable monomer component is preferably 65 volume % or less, more preferably 60 volume % or less. The blending ratio of (a1) to (a4) is preferably determined appropriately depending on the intended use, etc.

[0057] (b) Dispersant The decorative ink disclosed herein may contain a dispersant. Examples of dispersants include cationic dispersants. Such cationic dispersants efficiently adhere to the surface of red-based inorganic pigments through an acid-base reaction. Therefore, unlike other dispersants, such as phosphate-based dispersants, they can suppress aggregation of the red-based inorganic pigments and effectively disperse them. An example of such a cationic dispersant is an amine-based dispersant. Such an amine-based dispersant can suppress aggregation of the red-based inorganic pigments due to steric hindrance and stabilize the red-based inorganic pigments. Furthermore, by imparting the same charge to the red-based inorganic pigment particles, aggregation of the red-based inorganic pigments can also be effectively suppressed. This effectively reduces the viscosity of the ink, significantly improving printability. Examples of such amine-based dispersants include fatty acid amine-based dispersants and polyester amine-based dispersants. The content of the dispersant is not particularly limited and can be approximately 10 to 50% by volume, assuming the entire decorative ink to be 100% by volume. Furthermore, commercially available dispersants can be used without particular restrictions.

[0058] (c) Photopolymerization initiator The decorative ink disclosed herein, for example, when containing a photocurable monomer component, may further contain a photopolymerization initiator. The photopolymerization initiator absorbs light and becomes activated, generating reaction initiators such as radical molecules and hydrogen ions. These reaction initiators act on the photocurable monomer, accelerating the polymerization and crosslinking reactions of the photocurable monomer. In other words, by increasing the content of the photopolymerization initiator, it is possible to prepare an ink that cures easily even with a small amount of light. Conventional photopolymerization initiators can be used without any particular restrictions as the photopolymerization initiator. Examples include radical photopolymerization initiators such as alkylphenone-based photopolymerization initiators and acylphosphine oxide-based photopolymerization initiators. As such alkylphenone-based photopolymerization initiators, for example, α-aminoalkylphenone-based photopolymerization initiators (e.g., 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone, etc.) are preferably used. Other examples of alkylphenone-based photopolymerization initiators that can be used include α-hydroxyalkylphenone-based photopolymerization initiators (1-hydroxycyclohexylphenylketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)benzyl]phenyl}-2-methylpropan-1-one, etc.). Among the various photopolymerization initiators described above, α-aminoalkylphenone-based photopolymerization initiators such as 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one are particularly preferred because they exhibit high reactivity, can improve the ink curing rate, and have excellent thin film curing properties and surface curing properties. The content of the photopolymerization initiator is not particularly limited, and can be about 1 to 5% by volume when the entire decorative ink is taken as 100% by volume. Furthermore, commercially available photopolymerization initiators can be used without any particular restrictions.

[0059] (d) Polymerization inhibitor The decorative ink disclosed herein may further contain a polymerization inhibitor, for example, when it contains a photocurable monomer component. Adding such a polymerization inhibitor can prevent the photocurable monomer component from polymerizing and curing before use, thereby facilitating ink storage. Any polymerization inhibitor conventionally used in the field of photocurable inkjet inks can be used without particular limitation, as long as it does not significantly reduce the photocurability of the photocurable monomer component and thus does not impair the effects of the technology disclosed herein. Examples of such polymerization inhibitors include hydroquinone, methoquinone, di-t-butylhydroquinone, p-methoxyphenol, butylhydroxytoluene, and nitrosamine salts. Among these compounds, N-nitroso-N-phenylhydroxylamine aluminum salt is particularly suitable due to its excellent long-term storage stability. The content of the polymerization inhibitor is not particularly limited, and can be approximately 0.1 to 5% by volume, based on 100% by volume of the entire decorative ink. Furthermore, commercially available polymerization inhibitors can be used without particular limitation.

[0060] (3) Content of each component The decorative ink disclosed herein is characterized by (a) the volume ratio of the red inorganic pigment to the total amount of inorganic solid components being controlled within a predetermined range. The decorative ink disclosed herein may also have (b) the volume ratio of the red inorganic pigment to the total amount of metal-containing glass being controlled within a predetermined range. Furthermore, when the decorative ink is used as an inkjet ink, it is preferable that (c) the volume ratio of the inorganic solid components to the total amount of ink be controlled within a predetermined range, in order to maintain the viscosity of the ink within an appropriate range.

[0061] (a) Volume ratio of red inorganic pigment to the total amount of inorganic solid components In the decorative ink disclosed herein, the volume of the red-based inorganic pigment is adjusted to 5% by volume or more when the total volume of the inorganic solid components is taken as 100% by volume. Here, the "total volume of the inorganic solid components" refers to the combined volume of the red-based inorganic pigment and the glass frit. From the viewpoint of obtaining the effects of the red-based inorganic pigment, the lower limit of the volume ratio of the red-based inorganic pigment is set to 1% by volume or more. To further enhance the magenta color development of the decorative portion, the red-based inorganic pigment is preferably 2.6% by volume or more (e.g., 5% by volume or more). On the other hand, if the volume ratio of the red-based inorganic pigment to the total amount of the inorganic solid components is increased too much, the color development of the decorative portion may be reduced, and the fixation of the decorative portion may be reduced due to a decrease in the glass frit content. From this viewpoint, the upper limit of the volume ratio of the red-based inorganic pigment is set to less than 80% by volume. To further enhance the fixation of the decorative portion to the inorganic substrate, the upper limit of the volume ratio of the red-based inorganic pigment is more preferably less than 70% by volume (e.g., 50% by volume or less).

[0062] (b) Volume ratio of red inorganic pigment to the total amount of gold-containing glass In the decorative ink disclosed herein, the volume ratio of the red inorganic pigment when the total volume of the metal-containing glass is taken as 100 parts by volume is not particularly limited as long as the effects of the technology disclosed herein are exhibited. The lower limit of the volume ratio of the red inorganic pigment is generally 1 part by volume or more, and from the viewpoint of improving the magenta color development of the decorative part, it is preferably 5 parts by volume or more. The upper limit of the volume of the red inorganic pigment is generally 300 parts by volume or less (e.g., 250 parts by volume or less), and from the viewpoint of improving the fixation of the decorative part, it is preferably 100 parts by volume or less (e.g., 70 parts by volume or less).

[0063] (c) Volume ratio of inorganic solid components to the total volume of decorative ink When the decorative ink disclosed herein is used as an inkjet ink, the volume ratio of the inorganic solid components is set to 35% by volume or less, assuming that the total volume of the inkjet ink is 100% by volume, in order to maintain an appropriate viscosity range. Here, the "total volume of the inorganic solid components" refers to the combined volume of the red inorganic pigment and the glass frit. Increasing the volume of the inorganic solid components tends to increase the ink viscosity. Because there are many types of red inorganic pigments and glass frits contained in the inorganic solid components and their specific gravities vary, this embodiment adjusts the "volume" of the inorganic solid components rather than the "weight." By setting the volume ratio of the inorganic solid components to the total ink volume to 35% by volume or less, a low ink viscosity suitable for inkjet printing (typically 20 mPa·s or more but less than 110 mPa·s, preferably 30 mPa·s or more but less than 70 mPa·s) can be achieved. To more effectively reduce the ink viscosity, the volume ratio of the inorganic solid components is preferably 30% by volume or less, and more preferably 20% by volume or less. On the other hand, from the viewpoint of ensuring sufficient hiding power and fixation of the decorative part, the lower limit of the volume ratio of the inorganic solid component is preferably 10% by volume or more, and more preferably 15% by volume or more (for example, 17% by volume or more).

[0064] 2. Preparation of decorative ink The decorative ink disclosed herein can be used as a variety of inks. The decorative ink disclosed herein can be used, for example, as a screen printing ink, a painting ink, an inkjet ink, etc. These inks can be prepared by conventionally known methods. The viscosity of each ink can be adjusted, for example, according to the viscosity of each conventionally known ink. As an example, a method for preparing an inkjet ink as the decorative ink will be described below.

[0065] First, a preferred method for preparing glass frit will be described. First, the gold particles and glass component described above are mixed in a wet manner to prepare a liquid mixture (mixture preparation step). Next, this mixture is heat-treated to obtain a sintered body in which the gold particles are dispersed in a glass matrix (heat treatment step). Then, this sintered body is pulverized (pulverization step). This manufacturing method allows glass frit to be obtained through the simple steps of mixing and heat treatment.

[0066] In the mixture preparation step, gold particles and a glass component are mixed in a predetermined ratio. Because such gold particles have a high tendency to aggregate, they are typically sold commercially in the form of a dispersion stabilized in a dispersion solvent. The mixing operation can be performed using, for example, a magnetic stirrer or ultrasonic waves. In this embodiment, a highly homogeneous mixture can be obtained by mixing gold particles and glass frit using a wet method. In this manner, a liquid mixture is prepared.

[0067] In the heat treatment step, the mixture is heat-treated. For example, it is first dried at a temperature below 100°C to remove some of the dispersant, and then heated to a temperature above the glass transition point of the glass component to sinter the mixture into a cohesive body. The sintering temperature should generally be set to approximately 0 to 300°C above the glass transition point. For example, in the production of overglaze paint, if the glass transition point of the glass component is 600 to 800°C, the sintering temperature should be set to approximately 800 to 900°C. The sintering time is usually approximately 0.1 to several hours. The sintering atmosphere can be air, an oxidizing atmosphere, an inert gas atmosphere, or the like. By performing this heat treatment, a cohesive sintered body is obtained in which gold particles are dispersed in a glass matrix.

[0068] In the pulverization step, the sintered body is pulverized (may be crushed) and / or classified to adjust it to a desired size. The pulverization operation can be carried out using, for example, a vibration mill, a planetary mill, an agitator mill, or the like.

[0069] In this manner, the glass frit disclosed herein can be obtained.

[0070] The inkjet ink disclosed herein can be prepared by mixing the above-mentioned materials in a predetermined ratio, followed by crushing and dispersing the inorganic solid components. Figure 1 is a cross-sectional view that schematically shows an agitator / pulverizer used in the production of inkjet ink. Note that the following description is not intended to limit the inkjet ink disclosed herein.

[0071] To manufacture the inkjet ink disclosed herein, the above-described materials are first weighed and mixed to prepare a slurry, which is a precursor of the ink. Next, using an agitator / miller 100 as shown in FIG. 1, the slurry is agitated and the inorganic solid components (glass frit and red inorganic pigment) are pulverized. Specifically, milling beads (e.g., zirconia beads with a diameter of 0.5 mm) are added to the slurry, and the slurry is then supplied into a stirring vessel 120 through a supply port 110. A shaft 134 having multiple agitating blades 132 is housed within the stirring vessel 120. One end of the shaft 134 is attached to a motor (not shown). By operating the motor, the shaft 134 rotates, stirring the slurry with the multiple agitating blades 132 while sending it downstream in the liquid-feeding direction A. During this agitation, the inorganic solid components are pulverized by the milling beads added to the slurry, and the finely divided inorganic solid components are dispersed throughout the slurry.

[0072] The slurry sent downstream in the liquid sending direction A then passes through filter 140. As a result, grinding beads and inorganic solid components that have not been atomized are collected by filter 140, and inkjet ink in which the atomized inorganic solid components are sufficiently dispersed is discharged from outlet 150. By adjusting the pore size of filter 140 at this time, the maximum particle size of the inorganic solid components in the inkjet ink can be controlled.

[0073] 3. Uses of decorative ink Next, applications of the decorative ink disclosed herein will be described. In the following, as an example, the decorative ink will be described as an inkjet ink. As described above, the inkjet ink disclosed herein can be suitably used to draw images on colorless, transparent glass substrates or colored metal substrates. In this specification, the phrase "used to draw images on a glass substrate or metal substrate" refers not only to a case in which the ink is directly applied to the surface of a glass substrate (or a metal substrate), but also to a case in which the ink is indirectly applied to the surface of a glass substrate (or a metal substrate) via transfer paper or the like. In other words, the decorative ink disclosed herein can be used for printing on transfer paper (transfer paper production) or printing on the surface of a glass substrate (or a metal substrate) (inorganic product production). A product printed directly on the surface of a glass substrate (or a metal substrate) will be referred to as a "printed product."

[0074] (1) Manufacture of transfer paper A method for producing transfer paper for inorganic substrates (a printing method for drawing an image on the surface of transfer paper) using the inkjet ink disclosed herein will be described. Fig. 2 is a general view showing a typical example of an inkjet device. Fig. 3 is a cross-sectional view showing a typical inkjet head of the inkjet device shown in Fig. 2.

[0075] The inkjet ink disclosed herein is stored in an inkjet head 10 of an inkjet device 1 shown in FIG. 2. The inkjet device 1 includes four inkjet heads 10. Each inkjet head 10 stores one of four different colors of ink: black (K), cyan (C), yellow (Y), and magenta (M). The inkjet ink disclosed herein is stored in the magenta (M) inkjet head 10. Each inkjet head 10 is housed inside a print cartridge 40. The print cartridge 40 is inserted into a guide shaft 20 and is configured to reciprocate along the axial direction X of the guide shaft 20. Although not shown, the inkjet device 1 also includes a moving means for moving the guide shaft 20 in the vertical direction Y. This allows ink to be ejected from the inkjet head 10 toward a desired position on a backing sheet W of transfer paper.

[0076] The inkjet head 10 shown in Fig. 2 may be, for example, a piezoelectric inkjet head as shown in Fig. 3. Such a piezoelectric inkjet head 10 has a storage section 13 for storing ink in a case 12, and the storage section 13 is connected to a discharge section 16 via a liquid supply path 15. The discharge section 16 has a discharge port 17 that opens to the outside of the case 12, and a piezoelectric element 18 is arranged opposite the discharge port 17. In such an inkjet head 10, the piezoelectric element 18 is vibrated to discharge the ink in the discharge section 16 from the discharge port 17 toward the backing paper W (see Fig. 2).

[0077] 2, a UV irradiation means 30 is attached to the guide shaft 20. The UV irradiation means 30 is disposed adjacent to the print cartridge 40, and moves in conjunction with the reciprocating movement of the print cartridge 40, irradiating the ink-adhered backing paper W with ultraviolet light. This causes the ink to harden immediately after adhering to the surface of the backing paper W, allowing a sufficient thickness of ink to be fixed on the surface of the transfer paper (backing paper W).

[0078] As described above, in the inkjet ink disclosed herein, the volume of inorganic solid components relative to the total volume of the inkjet ink is adjusted to 35% by volume or less, which allows the ink viscosity to be maintained at a low level, enabling the ink to be ejected from the ejection openings 17 with high precision and to print a precise image on the surface of the printing target (here, transfer paper).

[0079] In addition, it is preferable to use a photocurable monomer component containing the monomers (a1) to (a4) described above in the production of this transfer paper, which allows for the printing of an image (cured ink) with sufficient flexibility, thereby suitably preventing cracks from occurring in the image when the transfer paper is bent.

[0080] (2) Production of printed materials Next, a method for producing a printed material using the inkjet ink disclosed herein will be described. The printed material can be produced by drawing an image on the surface of an inorganic substrate (typically a glass substrate or a metal substrate) using an inkjet device. For the method for drawing an image using an inkjet device, see the above-mentioned "Production of transfer paper."

[0081] (3) Manufacturing methods for inorganic products Next, a method for manufacturing an inorganic product using the inkjet ink disclosed herein will be described. The method for manufacturing such a glass product includes a step of decorating the surface of an inorganic substrate using a decorative ink (here, an inkjet ink). In a preferred embodiment of the method for manufacturing a glass product, the decorating step includes the following steps: depositing a cured product of any of the decorative inks disclosed herein on the surface of the inorganic substrate (a depositing step); and firing the inorganic substrate at a maximum firing temperature within the range of 350°C to 700°C (a firing step).

[0082] The inorganic product produced by this production method is not particularly limited as long as it is an inorganic substrate having a decorative portion formed on its surface. For example, the inorganic product is not limited to everyday items such as tableware, window glass, and cooking equipment, but may also be industrial products such as electronic devices and displays. The inorganic substrate to be printed is not particularly limited, and commonly used inorganic materials can be used without particular restrictions. In consideration of the firing process described below, it is preferable to use an inorganic substrate having a softening point of 500°C or higher (more preferably 600°C or higher, and even more preferably 700°C or higher). On the other hand, the upper limit of the softening point of the inorganic substrate is not particularly limited. For example, the upper limit of the softening point of the inorganic substrate may be 1600°C or lower, 1200°C or lower, or 1000°C or lower.

[0083] The color tone of the decorative part formed on the inorganic substrate is, for example, L based on JIS Z8729 (2004). * a * b * In the color system, the following conditions: L * a value of 10 to 80 (preferably 15 to 75); a * a value of 7 or greater (preferably 10 or greater); ·b * a value of less than 10 (preferably 7 or less (e.g., less than 7)); The lightness L * By setting the value to a predetermined value or more, bright and vivid colors can be achieved. * By setting the value to a predetermined value or less, it is possible to achieve a deep and warm color. * By setting the value to a predetermined value or more, it is possible to enhance the red coloring and realize a sharp and clear color. * By setting the value to a predetermined value or less, in other words, the b * By keeping the value small, for example, a purple to bluish color like "magenta" can be developed, and a vivid magenta color can be realized. Note that such measurement can be carried out using, for example, a commercially available device.

[0084] In addition, the hue angle (h * For example, the L value based on JIS Z8729 (2004) * a * b * Based on the color system, a * and b * It can be calculated from h * The value is a * It can mean the angle of the hue moving counterclockwise from the red axis, which is 0°. * By setting the value within a predetermined range, it is possible to enhance the red coloring property and realize a sharp and clear color. * The value is -45° or more and 45° or less, for example, -45° or more and 40° or -40° or more and 45° or less, and preferably -40° or more and 40° or less. Such measurements can be carried out using, for example, a commercially available device.

[0085] The transmittance of the decorative portion formed on the inorganic substrate can be, for example, the transmittance based on JIS R3106 (2019). The transmittance is preferably, for example, 40 or less, and more preferably 20 or less (for example, less than 20). Note that such measurements can be performed using, for example, a commercially available device.

[0086] In the deposition step, the inkjet ink is adhered (deposited) on the surface of the inorganic substrate. The means for adhering the ink to the inorganic substrate is not particularly limited, and the ink may be directly adhered to the surface of the inorganic substrate using an inkjet device, or the ink may be indirectly adhered via the transfer paper described above. When the ink is directly adhered to the surface of the inorganic substrate using an inkjet device, it is preferable to eject the ink toward the surface of the inorganic substrate according to the same procedure as in the "manufacturing of transfer paper" described above.

[0087] In the firing step, the inorganic substrate with the ink attached is fired under conditions where the maximum firing temperature is set within the range of 350°C to 700°C (preferably 550°C to 650°C). This burns off the resin component formed by hardening the monomer, and melts the glass frit in the inorganic solid component. Then, by cooling after firing, the melted glass frit solidifies, and the fired film is fixed to the surface of the substrate. The manufacturing method disclosed herein uses ink in which the volume of the red inorganic pigment relative to the total volume of the inorganic solid component is adjusted to 1% by volume or more, thereby forming a beautiful decorative portion with excellent hiding power. Furthermore, because the volume of the red inorganic pigment relative to the total volume of the inorganic solid component is adjusted to less than 80% by volume, the fired film can be properly fixed to the surface of the inorganic substrate.

[0088] Test examples relating to the decorative inks disclosed herein are described below, but it is not intended that the present disclosure be limited to such test examples. The following also describes the use of the decorative inks disclosed herein as inkjet inks.

[0089] <Preparation of Inkjet Ink> Inkjet inks according to Examples 1 to 19 Slurries were prepared by mixing the raw materials in the volume ratios shown in Tables 2 and 3, and the inks of Examples 1 to 19 were obtained by performing a pulverization and dispersion process using pulverization beads (zirconia beads with a diameter of 0.5 mm). The volume ratios in the tables are values ​​assuming the total volume of the ink as 100% by volume, unless otherwise specified. In these test examples, commercially available red inorganic pigments (hereinafter referred to as A, B, and C) and proprietary metal-containing glass were used as the inorganic solid components. The metal-containing glass was a glass matrix (specifically, SiO2-ZnO-ZrO2-TiO2-based glass (67-11-4-5 mol%), Tg: 500°C, thermal expansion coefficient: 9×10 ―6 K ―1The gold-containing glass was prepared by dispersing gold particles (specifically, gold particles with an average particle size of approximately 20 nm) in a glass matrix. The average particle size of the gold-containing glass was approximately 3 μm, and the gold particles accounted for 0.1 parts by volume per 100 parts by volume of the glass matrix. The average particle size (D50 particle size) of the gold-containing glass after grinding (dispersion) was 1 μm or less. An amine-based dispersant (BYK-2013, manufactured by BYK Japan Co., Ltd.) was added as a dispersant, an acylphosphine oxide-based photopolymerization initiator (Omnirad 819, manufactured by IGM Resins) was added as a photopolymerization initiator, and N-nitroso-N-phenylhydroxylamine aluminum (Q-1301, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a polymerization inhibitor.

[0090] The "photocurable monomer components" in Tables 2 and 3 are mixtures of a monofunctional acrylate monomer, a monofunctional N-vinyl compound monomer, a polyfunctional acrylate monomer, and a polyfunctional vinyl ether monomer in a predetermined volume ratio. The monofunctional acrylate monomers used were a mixture of isobornyl acrylate (manufactured by Osaka Organic Chemical Industry Ltd.), benzyl acrylate (manufactured by Osaka Organic Chemical Industry Ltd.), phenoxyethyl acrylate (manufactured by Osaka Organic Chemical Industry Ltd.), and cyclic trimethylolpropane formal acrylate (manufactured by Osaka Organic Chemical Industry Ltd.). The monofunctional N-vinyl compound monomer used was N-vinyl-ε-caprolactam (manufactured by Tokyo Chemical Industry Co., Ltd.). The polyfunctional acrylate monomer used was 1,9-nonanediol diacrylate (manufactured by Osaka Organic Chemical Industry Ltd.). As the polyfunctional vinyl ether monomer, a mixture of triethylene glycol divinyl ether (manufactured by Nippon Carbide Corporation), diethylene glycol divinyl ether (manufactured by Nippon Carbide Corporation), and 1,4-cyclohexanedimethanol divinyl ether (manufactured by Nippon Carbide Corporation) was used.

[0091] The red coloring properties of the various red inorganic pigments described above were evaluated by measuring the reflectance of red inorganic pigment powder (1 to 2 mg) using an ultraviolet-visible-near infrared spectrophotometer (manufactured by JASCO Corporation: V-770). Specifically, the red coloring properties of the various red inorganic pigments were evaluated by measuring the reflectance of red inorganic pigment powder (1 to 2 mg) using an ultraviolet-visible-near infrared spectrophotometer (manufactured by JASCO Corporation: V-770). * a * b * Chromaticity of the color system (a * The measurement conditions were determined in accordance with the catalog. The evaluation results are shown in Table 1.

[0092] [Table 1]

[0093] In this test example, the "volume ratio of inorganic solid components to the total amount of ink" and the "volume ratio of red inorganic pigment to the total amount of inorganic solid components" were calculated for each example. Note that the "volume ratio of inorganic solid components to the total amount of ink" is a value when the total amount of ink is 100% by volume, and the "volume ratio of red inorganic pigment to the total amount of inorganic solid components" is a value when the total amount of inorganic solid components is 100% by volume.

[0094] Inkjet ink according to Example 20 An inkjet ink according to Example 20 was prepared in the same manner as the other examples, except that a colorless and transparent glass frit was used instead of the metal-containing glass. For convenience, in Table 3, Example 20 shows the content of the colorless and transparent glass frit in the "metal-containing glass" column.

[0095] <Evaluation test> Ink viscosity evaluation The ink viscosity of each example prepared was measured using a Brookfield viscometer (Programmable Rheometer LVDV-III Ultra, manufactured by ST Johnson & Co., Japan). The ink temperature during measurement was set at 25°C, and the spindle rotation speed was set at 5 rpm. Inks with a viscosity of less than 70 mPa·s were evaluated as having a "◎" ink viscosity, inks with a viscosity of 70 mPa·s or more but less than 110 mPa·s were evaluated as having a "○" ink viscosity, and inks with a viscosity of 110 mPa·s or more were evaluated as having an "×" ink viscosity. The evaluation results are shown in the appropriate columns in Tables 2 and 3.

[0096] <Printing images> Using inkjet printing, the inks of Examples 1 to 10 and 15 to 20 were printed on the surface of a 5 mm thick glass substrate (softening point: 820°C), and the inks of Examples 11 to 14 were printed on the surface of a 1.5 mm thick metal substrate. Specifically, an inkjet device (Fujifilm Corporation: Material Printer (DMP-2831)) was used to eject the ink onto the surface of the glass substrate (or metal substrate), and then the glass substrate was irradiated with UV light (wavelength: 395 nm) for 1 second to create an image with a thickness of 5 μm to 50 μm. The glass substrate (or metal substrate) was then fired at 700°C to produce a test piece with a decorative portion.

[0097] Color development evaluation The L based on JIS Z8729 (2004) of the decorative part of the test piece prepared as above * a * b * Chromaticity of the color system (a * value and b * The value of the color (transmittance) was measured using a spectrophotometer (CM-700d manufactured by Konica Minolta, Inc.). The hiding power of the decorative part (referred to as "transmittance" in the table) was evaluated using a spectrophotometer (TL-110V manufactured by Tokai Optical Co., Ltd.). * Regarding the value, a value of 10 or more was marked as "◎", a value of 7 or more but less than 10 was marked as "○", and a value of less than 7 was marked as "×". *Regarding the value, a value less than 7 was rated as "◎", a value between 7 and 10 was rated as "◯", and a value greater than or equal to 10 was rated as "×". Regarding the transmittance, a value less than 20 was rated as "◎", a value between 20 and 40 was rated as "◯", and a value greater than or equal to 40 was rated as "×".

[0098] Regarding the overall evaluation of color development, * value," "b * In the evaluation of "a value" and "transmittance" (for Examples 11 to 14 using a metal substrate, * value" and "b * The evaluation results are shown in the corresponding columns in Tables 2 and 3.

[0099] For Examples 11 to 14, which used a metal substrate, the "transmittance" could not be measured, so the corresponding column is marked with "-". For Examples 17 and 18, the proportion of glass components in the ink was low, and the decorative portion peeled off before evaluation, so the columns related to color development are marked with "-". For Example 19, where the ink viscosity could not be adjusted appropriately and the ink could not be ejected from the inkjet device, the columns related to color development are marked with "-".

[0100] Fixation evaluation The adhesion of the decorative portion of the test piece prepared as described above to the glass substrate (or metal substrate) was measured using scratch hardness (pencil method) (JIS K5600-5-4). A pencil hardness of 2H or higher was evaluated as "◎", a pencil hardness of less than 2H and the decorative portion did not peel off when rubbed with the pad of a finger was evaluated as "○", and a pencil hardness of less than 2H and the decorative portion peeled off when rubbed with the pad of a finger was evaluated as "×". The evaluation results are shown in the corresponding columns in Tables 2 and 3.

[0101] In Examples 15 and 16, the proportion of glass components in the ink was low, and the decorative parts peeled off before evaluation, so the "fixation" column is marked with a "-." Furthermore, for Example 19, where the ink viscosity could not be adjusted appropriately and the ink could not be ejected from the inkjet device, the "fixation" column is marked with a "-."

[0102] ·comprehensive evaluation Regarding the overall evaluation, a rating of "◎" was given for all of the evaluations of "overall evaluation of color development," "fixation," and "ink viscosity," while a rating of "○" was given for 0 x's and one ◯, and a rating of "×" for at least one x. The evaluation results are shown in the corresponding columns in Tables 2 and 3.

[0103] [Table 2]

[0104] [Table 3]

[0105] As shown in Tables 2 and 3, in Examples 1 to 14, which contain glass frit containing gold particles and a red inorganic pigment, and in which the red inorganic pigment is contained in an amount of 1% by volume or more and less than 80% by volume when the total volume of the inorganic solid components including the glass frit and the red inorganic pigment is taken as 100% by volume, it was confirmed that the magenta color development of the decorative portion was excellent. It was also confirmed that the fixation of the decorative portion was excellent. On the other hand, it was confirmed that Examples 16 to 18, in which the content of the red inorganic pigment was outside the above range, did not have excellent magenta color development of the decorative portion. Furthermore, it was confirmed that Example 15, which contained only gold-containing glass, and Example 20, which used colorless and transparent glass frit instead of gold-containing glass (in other words, an attempt was made to achieve color development using only the red inorganic pigment), did not provide color development in the decorative portion.

[0106] Furthermore, when the total volume of the decorative ink (here, inkjet ink) is taken as 100% by volume, it was confirmed that in Example 19, which contains more than 35% by volume of inorganic solid components (here, red inorganic pigments and metal-containing glass), the ink viscosity cannot be appropriately adjusted.

[0107] Although specific examples of the present invention have been described above in detail, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples exemplified above. [Explanation of symbols]

[0108] 1. Inkjet device 10 Inkjet head 12 cases 13 Storage 15 Liquid transfer path 16 Discharge part 17 Outlet 18 Piezo element 20 Guide shaft 30 UV irradiation means 40 print cartridges 100 Stirring mill 110 Supply port 120 Stirring vessel 132 stirring blade 134 Shaft 140 filters 150 Outlet A Flow direction X Guide shaft axial direction Y guide axis vertical direction

Claims

1. 1. A decorative ink used to render images on glass or metal substrates, comprising: a glass frit containing gold particles; a composite metal compound containing at least one metal element selected from the group consisting of Cu, Mn, Zr, Ti, Pr, Cr, Sb, Ni, Co, and Al, and a red inorganic pigment which is at least one of a tin-sphene-based, zinc ferrite-based, and zircon-based pigment; Including, The decorative ink contains the reddish inorganic pigment in an amount of 5% by volume or more and less than 70% by volume when the total volume of inorganic solid components including the glass frit and the reddish inorganic pigment is taken as 100% by volume.

2. 2. The decorative ink according to claim 1, wherein the red inorganic pigment does not contain cadmium.

3. The red inorganic pigment has a color value of a based on a spectrophotometer ＊ The value is a ＊ 3. The decorative ink according to claim 1, wherein the viscosity of the ink is >10.

4. The decorative ink is an inkjet ink, 4. The decorative ink according to claim 1, wherein the inorganic solid component accounts for 35% by volume or less when the total volume of the inkjet ink is taken as 100% by volume.

5. 5. The decorative ink according to claim 4, wherein the glass frit has an average particle size of 1 [mu]m or less.

6. The decorative ink according to any one of claims 1 to 5, further comprising a photocurable monomer component.

7. A printed matter bearing a representation of an image made from the ink of any one of claims 1 to 6.

8. A transfer paper for inorganic substrates, bearing an image formed from the decorative ink according to any one of claims 1 to 6.

9. A method for producing an inorganic product, comprising: A method for producing an inorganic product, comprising a decorating step of decorating the surface of an inorganic substrate using the decorative ink according to any one of claims 1 to 6.

10. The decoration process includes the following steps: A step of depositing a cured product of the decorative ink according to any one of claims 1 to 6 on the surface of an inorganic substrate; and a step of firing the inorganic base material under conditions in which a maximum firing temperature is set within a range of 350°C to 700°C; The method for producing an inorganic product according to claim 9, comprising:

Images