Title: Insulating light shielding printing ink and insulating member
Technical field
[0001]
　The present invention relates to an insulating light shielding printing ink and an insulating member.
Background art
[0002]
　Conventionally, various performances are required for the ink in addition to the printability. Above all, in the field of electronic devices, in addition to light shielding applications, insulating black ink is required. As such a black ink, carbon black and iron oxide are generally used.
　However, when carbon black is to be used in the field of electronic devices, there is a problem that carbon black has conductivity, so that a sufficient resistance value can not be obtained. That is, although the light shielding effect can be obtained by increasing the blending amount of carbon black, as a result of the conductivity becoming high, the insulating property is lowered. In other words, the insulating property and the hiding property are in a trade-off relationship. As a technology for solving such a problem, Patent Document 1 discloses a technology relating to carbon black whose surface is coated with a resin.
[0003]
　On the other hand, from the viewpoint of environmental protection, a new ink material replacing carbon black and iron oxide is required. As an environmentally friendly ink material, for example, Patent Document 2 discloses a technology relating to an ink that can be added to food containing carbon powder of a specific particle size.
Prior art documents
Patent document
[0004]
Patent Document 1: JP-A-2001-207079
Patent Document 2: JP-A-2008-179737
Summary of the invention
Problems that the Invention is to Solve
[0005]
　However, the technique disclosed in Patent Document 2 is intended to be added to food, and has not focused on the use of electronic devices. In addition, from the viewpoint of securing the safety as food, materials that can be used, such as using a special binder resin that can be added to food, have been limited.
Means to solve the problem
[0006]
　As a result of intensive studies to develop environmentally friendly inks for electronic devices replacing conventional carbon blacks, the present inventor has found for the first time that both high hiding power and high insulation can be achieved by using bamboo charcoal.
　Here, in general, charcoal derived from plants such as charcoal and bamboo charcoal and charcoal derived from other organic substances change the current-carrying characteristics obtained depending on the conditions such as the baking temperature.
　Therefore, the present inventor examined from the viewpoint of developing an ink capable of stably obtaining high insulation, and focused not on the current-carrying characteristics of bamboo charcoal itself but on the specific structure of bamboo charcoal. Then, by covering the entire surface and the inner surface derived from the specific structure of bamboo charcoal contained in the ink with the binder resin, it is found that the insulation properties of the binder resin can be effectively and stably obtained, However, it has been found that it is more compatible with the binder resin than other charcoals and a good coating can be obtained. And, while obtaining high hiding power by using bamboo charcoal, by combining this with a binder resin, an ink that can achieve both high hiding power and high insulation is realized for the first time.
[0007]
　The present invention provides an insulating light-blocking printing ink comprising bamboo charcoal and a binder resin.
[0008]
　Moreover, this invention provides the insulating member provided with a base material and the coating film by the said printing ink for insulating light shielding formed on the said base material.
Effect of the invention
[0009]
　According to the present invention, it is possible to provide an environmentally friendly insulating light-blocking printing ink that can achieve both high insulation and high hiding power.
MODE FOR CARRYING OUT THE INVENTION
[0010]

　Hereinafter, the embodiment of the present invention will be described in detail.
[0011]
　The insulating light-shielding printing ink of the present invention contains bamboo charcoal and a binder resin.
[0012]
　Bamboo charcoal functions as a black ink and is a charcoal obtained after firing bamboo.
　Bamboo is an easy-to-use, inexpensive and environmentally friendly material in terms of recycling resources. Examples of bamboo include, in general, fresh bamboo, light bamboo (Hachik), zoune bamboo, cloth bamboo bamboo, black bamboo, female bamboo shoot (medakame), rooted bamboo and light bamboo and the like. One of these may be used alone, or two or more may be mixed and used.
　As a firing method of bamboo, known methods may be mentioned, such as a method of baking with an anthrax or a method of mechanically baking using a carbonization furnace using a material such as stainless steel. Note that the method of mechanically baking using a carbonization furnace also includes a method of heat treatment using heating steam under an oxygen-free atmosphere. Firing conditions are, for example, several days to one week at 400 to 1000 ° C. for baking in anthrax, and for example, 6 to 8 hours at 400 to 1000 ° C. for mechanical baking using a carbonization furnace. To be done. However, in the case of heat treatment with heating steam, it may be carried out in a short time of about 15 minutes to 1 hour.
[0013]
　Bamboo charcoal generally produces more fine holes than charcoal or the like. Such fine holes are a temporary tube for sucking up the nutrition and moisture of bamboo, etc., in which a macrotube obtained by carbonization and crystallization and a finer microtube present in the inner wall thereof are arranged without a gap, and a so-called honeycomb structure It has become. In addition, since bamboo has a fiber structure aligned in the longitudinal direction and is linear, such fine holes are easily aligned in a straight line. The average pore size of the macro tube is approximately 10 to 40 μm, and the average pore size of the micro tube is approximately 1 to 5 nm.
　In addition, relatively large amounts of silicic acid and potassium are contained in bamboo, and they have the property of being solidified like a glass when they are fired to bamboo charcoal. For this reason, bamboo charcoal is generally considered to contain more glassy material than charcoal and the like.
[0014]
　The specific surface area of ​​bamboo charcoal is, for example, preferably 100 m 2 / g or more, and more preferably 200 m 2 / g or more, as a calculated value using a BET multipoint method by nitrogen adsorption .
　On the other hand, the specific surface area of ​​bamboo charcoal is preferably 1,000 m 2 / g or less, more preferably 500 m 2 / g or less. This can improve the concealability.
　The specific surface area of ​​bamboo charcoal can be measured in accordance with JIS Z8830.
[0015]
　The 50% particle diameter (D50) of bamboo charcoal is preferably 0.05 μm or more, more preferably 1 μm or more, and still more preferably 2.5 μm. Thereby, appropriate dispersibility can be obtained.
　On the other hand, 50% particle diameter (D50) of bamboo charcoal is preferably 10 μm or less, more preferably 8.0 μm or less, and still more preferably 5.0 μm or less. Thereby, concealability can be improved while forming a suitable coating film.
　The 90% particle diameter (D90) of bamboo charcoal is preferably 20 μm or less, more preferably 10 μm or less.
　The 50% particle diameter (D50) and the 90% particle diameter (D90) of bamboo charcoal can be determined by, for example, measuring the particle size distribution on a volume basis by a laser diffraction / scattering method.
[0016]
　The content of bamboo charcoal is preferably 40 parts by mass or more, and more preferably 70 parts by mass or more, with respect to 100 parts by mass of the solid content in the insulating light-shielding printing ink. Thereby, the insulation can be enhanced while the concealability is improved while maintaining the printing characteristics.
　On the other hand, the content of bamboo charcoal is preferably 90 parts by mass or less, more preferably 80 parts by mass or less, with respect to 100 parts by mass of the solid content in the insulating light-blocking printing ink. Thereby, appropriate fluidity can be obtained and good printing can be performed.
[0017]
　Bamboo charcoal may be one having its surface physically or chemically treated from the viewpoint of making ink properties suitable.
[0018]
　The binder resin is used to disperse bamboo charcoal to form a printing film.
　The binder resin may be any resin chemically synthesized organically, and various resins can be used. As a binder resin, vinyl chloride-vinyl acetate copolymer resin (also referred to as "vinyl chloride resin" in the present specification) from the viewpoint of achieving good compatibility with bamboo charcoal and achieving both high insulation and hiding property at a higher level. Acrylic resin, polyester resin, epoxy resin, polycarbonate resin, polyolefin resin, synthetic rubber, cellulose resin, maleic resin, phenol resin, polyurethane resin, polyamide resin, polyimide resin, melamine resin, phenoxy resin, and active energy ray curing type It is preferable that it is 1 type, or 2 or more types chosen from among resin, these modified products, and modified products of natural resin. Among them, vinyl chloride-vinyl acetate copolymer resin, acrylic resin, polyester resin or epoxy resin, or modified products thereof are more preferable, and polyester resin is more preferable.
[0019]
　The content of the binder resin is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and one, preferably 150 parts by mass or less, more preferably 120 parts by mass with respect to 100 parts by mass of bamboo charcoal. It is below. By setting the lower limit value or more, good printing characteristics can be obtained. On the other hand, by setting the upper limit value or less, both insulation and concealability can be achieved at a higher level.
[0020]
　The insulating light-shielding printing ink of the present invention can achieve both the insulating property and the hiding property by containing bamboo charcoal and a binder resin. Although the details of the mechanism are not clear, as described above, bamboo charcoal generally has more fine pores than charcoal, and has a so-called honeycomb structure in which fine pores are arranged without gaps. Therefore, the binder resin can enter in the vicinity of the entrance of the minute holes and the inside of the holes. In addition, since bamboo charcoal generally contains more glassy substances than charcoal, it is considered that wetting with a binder resin is better than charcoal.
　As a result, the binder resin is in a state of being coated with bamboo charcoal, and even if the blending amount of bamboo charcoal is increased to enhance the concealability, the decrease of the resistance value can be suppressed, so it is presumed that the insulation and concealability can be compatible. Furthermore, the insulating light-shielding printing ink of the present invention obtains good insulation since the bamboo charcoal is coated with the binder resin as described above even when the bamboo charcoal having a relatively high conductivity is used. be able to.
[0021]
　The insulating light-shielding printing ink of the present invention can achieve both the insulating property and the hiding property at a higher level by satisfying the following conditions. Although the reason is not clear, while the present inventor is conducting research on insulating light shielding printing ink using bamboo charcoal, controlling the optical density (OD) value under the conditions within a specific range. However, it has been found that it is effective as an index to realize both the shielding property and the insulating property suitable for the application of the insulating light shielding printing ink.
　The insulating light-shielding printing ink of the present invention is applied on a glass substrate by drawing at a moving speed of 50 mm / sec using a bar coater with a wire diameter of 6 mil (bar No. 2 manufactured by RK Print Coat Instruments Ltd.) The optical density (OD) value of the resulting coating film is preferably 1.0 or more and 7.0 or less. The coating is obtained after drying at 80 ° C. for 60 minutes.
　The optical density (OD) value of the coating film is more preferably 3.5 or more from the viewpoint of obtaining the concealability. On the other hand, the optical density (OD) value of the coating film is more preferably 6.0 or less from the viewpoint of obtaining good ink fluidity, printing characteristics, adhesion and the like.
[0022]
　In the insulating light-shielding printing ink of the present invention, in order to control the optical density (OD) value of the coating film, identification of the type of binder resin according to the baking temperature of bamboo charcoal, average particle diameter, specific surface area, etc. It is obtained for the first time by controlling the mixing ratio of bamboo charcoal and binder resin, the degree of dispersion of bamboo charcoal to binder resin, and the like. The degree of dispersion is controlled by selecting, for example, the strength of the shearing force and the number of times of treatment in the dispersing device according to the combination of bamboo charcoal and the binder resin.
[0023]
　In addition, OD value is a numerical value which represented the transmittance | permeability (T%) of light with logarithm. In general, the higher the OD value, the lower the light transmittance.
　Also, the OD value can be measured, for example, using a transmission densitometer "type 341C" (manufactured by X-Rite).
[0024]
　In addition, the insulating light-shielding printing ink of the present invention may further contain a pigment other than bamboo charcoal as long as the effects of the present invention are not impaired. In this case, the content of bamboo charcoal with respect to all pigments is preferably 50% by mass or more, more preferably 80% by mass or more, and 100% by mass from the viewpoint of obtaining high insulation.
[0025]
　The insulating light-shielding printing ink of the present invention may also contain known ink additive components. Examples of known additives for ink include solvents, stabilizers such as antioxidants, leveling agents, antifoaming agents, thickeners, antisettling agents, wetting dispersants, antistatic agents, antifogging agents, etc. Various additives such as activators, waxes, slip agents, coupling agents, silane coupling agents, near infrared absorbers and the like can be mentioned.
　As the solvent, for example, mineral spirit, toluene, xylene, hydrocarbons such as aromatic hydrocarbon having 8 to 11 carbon atoms; ethyl acetate, n-butyl acetate, isobutyl acetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl Esters such as ether acetate, butyl carbitol acetate and dibasic acid esters; Ethers such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether and diethylene glycol; Ketones such as methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone and isophorone Methanol, ethanol, isopropanol, n-butanol, isobutanol, diacetone alcohol, 3-methyl-3-methoxybutanol How alcohol, and the like. These solvents may be used alone or in combination of two or more. Among them, ketones, esters and hydrocarbons are preferable.
[0026]
　The insulating light-blocking printing ink is formed by mixing bamboo charcoal and a binder resin by a known method. For example, bamboo charcoal can be added to a resin binder and dispersed using a suitable dispersing device to obtain an ink. At this time, from the viewpoint of controlling the optical density (OD) value in the above conditions within a specific range, for example, when using a 3-roll mill dispersing device, the linear pressure per roll length is set to 20 N / mm to 60 N / mm. After setting and applying appropriate shear force, it is preferable to set the number of treatments (number of passes) twice or more.
[0027]
　The insulating light-blocking printing ink of the present invention is particularly suitable for applications such as protective panel printing with a touch function provided in electronic devices such as smartphones, tablet PCs, car navigation systems, and intercoms that require light-blocking properties. It is. According to the insulating light-shielding printing ink of the present invention, in such a use, the electronic device performs a malfunction while obtaining high concealability such as shielding the backlight in the electronic device or hiding the electrode wiring inside the electronic device. It can be prevented.
[0028]

　The insulating member of the present invention comprises a substrate and a coating film of the above-mentioned insulating light-blocking printing ink formed on the substrate.
[0029]
　The substrate is not particularly limited, but is a kind selected from polyester, polyamide, polycarbonate, acrylic, polyurethane, polyolefin, quartz glass, soda lime glass, non-alkali glass, sapphire glass, chemically strengthened glass, and composite materials thereof. Or what is formed using 2 or more types as a material is mentioned. The base material formed of these materials is that which antifog treatment, strengthening treatment, antireflection treatment, heat ray cutting treatment, coloring treatment, or ITO (indium tin oxide) conductive film treatment is applied to the surface thereof May be Further, the shape of the substrate is not particularly limited.
[0030]
　The formation method of a coating film is not specifically limited, A well-known method can be used. The thickness of the coating is, for example, 3 to 200 μm.
[0031]
　The insulating member may, for example, be a touch panel with an electronic device as described above.
[0032]
　In addition, the insulating member may have another single layer or multiple layers between the substrate and the coating layer of the insulating light-shielding printing ink described above. Moreover, you may have multiple layers of the coating film layer by said printing ink for insulating light shielding. For example, a plurality of coating layers made of white ink may be stacked on a substrate, and a coating layer made of the above-mentioned insulating light-blocking printing ink may be stacked thereon.
[0033]
The method of using bamboo charcoal of the present invention uses bamboo charcoal as the above-mentioned insulating light-blocking printing ink. In this way, it is possible to provide an environmentally friendly ink using circulatory resources that can achieve both insulation and concealment.
[0034]
　As mentioned above, although embodiment of this invention was described, these are the illustrations of this invention, and various structures other than the above can also be employ | adopted.
Example 1
[0035]
　EXAMPLES The present invention will next be described in detail by way of examples, but the contents of the present invention are not limited to the examples.
[0036]
(Pigment) The pigments
　used in Examples and Comparative Examples are as shown in Tables 1 and 2 below.
[0037]
[table 1]

[0038]
[Table 2]

[0039]
(Binder resin) The binder resin
　used in Examples and Comparative Examples is as shown in Table 3 below.
[0040]
[Table 3]

[0041]
An
　organic solvent (Isophorone, manufactured by Evonik Industries) and bamboo charcoal are added to the binder resin so as to obtain the composition (parts by mass) shown in Table 4, and premixed with a small bladed rotary agitator. Did. After that, using a three-roll mill dispersion apparatus (Model: SDY-200, manufactured by Buhler Co., Ltd.), the linear pressure per roll length was set to 40 N / mm, and the ink was dispersed under the condition of two passes to obtain ink. .
[0042]
The same as Examples 1 to 9
　except that coconut shell charcoal D, carbon black E or iron oxide F was used instead of bamboo charcoal so that the composition (parts by mass) shown in Table 4 was obtained. Then I got the ink.
[0043]
　The following measurement and evaluation were performed about the ink obtained by the Example and the comparative example. The results are shown in Tables 4 and 5.
The
ink is drawn on a glass substrate at a moving speed of 50 mm / sec using a bar coater (bar No. 2 made by RK Print Coat Instruments Ltd., bar No. 2) with a wire diameter of 6 mil, and 80 ° C. And dried for 60 minutes to obtain a coated film. The optical density (OD) value of the obtained coating film was measured, respectively.
[0044]

· Insulating property: Measurement of resistance value (Ω) Using a
　bar coater (bar No. 2 made by RK Print Coat Instruments Ltd., wire diameter 6), draw the ink at a moving speed of 50 mm / sec. It was coated on a glass substrate and dried at 80 ° C. for 60 minutes to form a coating.
　Using a super insulation meter “type SM-21E” (manufactured by Toa Denpa Kogyo Co., Ltd.), the distance between the measurement terminals was lightly pressed against the coated film surface with the distance of 15 mm, and the resistance value of the coated film surface was measured. The measurement voltage was 1 kv, three measurements were taken, and the average value was taken. The measurement range was 1.0 × 10 6 Ω to 2.0 × 10 13 Ω when the measurement voltage was 1 kv .
[0045]
Hiding property: Visually evaluated sensory evaluation The
　ink was drawn on a glass substrate using a bar coater (bar No. 2 manufactured by RK Print Coat Instruments Ltd., bar No. 2) with a wire diameter of 6 mil to apply it on a glass substrate And dried under conditions of 80 ° C. for 60 minutes to form a coating, and a printed matter was obtained.
　The light of a fluorescent lamp is applied from the printed surface side (coated film surface side) of the obtained printed matter, and the degree of light shielding of the fluorescent lamp viewed from the glass substrate side is evaluated in four stages by a skilled expert. The
:: The light of the fluorescent lamp does not transmit at all.
○: The light of the fluorescent lamp is slightly transmitted.
Δ: The light of the fluorescent lamp is transmitted to some extent.
X: A considerable amount of light of a fluorescent lamp is transmitted.
[0046]
[Table 4]

[0047]
[Table 5]

[0048]
　This application claims priority based on Japanese Patent Application No. 2017-095498 filed on May 12, 2017, the entire disclosure of which is incorporated herein.
The scope of the claims
[Claim 1]
　Insulating light shielding printing ink containing bamboo charcoal and a binder resin.
[Claim 2]
　The insulating light-shielding printing ink according to claim 1, wherein the content of the bamboo charcoal is 40 parts by mass or more and 90 parts by mass or less with respect to 100 parts by mass of the solid content in the insulating light-shielding printing ink.
[Claim 3]
　The insulating light-shielding printing ink is drawn on a glass substrate by drawing at a moving speed of 50 mm / sec using a bar coater with a wire diameter of 6 mil, and the optical density (OD) value of the obtained coating is The insulating light-shielding printing ink according to claim 1, which is 1.0 or more and 7.0 or less.
[Claim 4]
　The binder resin is vinyl chloride-vinyl acetate copolymer resin, acrylic resin, polyester resin, epoxy resin, epoxy resin, polycarbonate resin, polyolefin resin, synthetic rubber, cellulose resin, maleic acid resin, phenol resin, polyurethane resin, polyamide resin, polyimide resin 4. The resin according to any one of claims 1 to 3, selected from melamine resins, phenoxy resins, active energy ray-curable resins, modified products thereof, and modified products of natural resins. Printing ink for insulating light shielding as described.
[Claim 5]
　The binder resin is one or more selected from vinyl chloride-vinyl acetate copolymer resin, acrylic resin, polyester resin, epoxy resin, and modified products thereof. The insulating light-shielding printing ink as described in Item.
[Claim 6]
　The insulating light-shielding printing ink according to any one of claims 1 to 5, wherein the 50% particle diameter (D50) of the bamboo charcoal is 0.05 μm or more and 10 μm or less.
[Claim 7]
　The binder resin is one or more selected from vinyl chloride-vinyl acetate copolymer resin, acrylic resin, polyester resin, epoxy resin, and modified products thereof, and
　the 50% particle diameter of the bamboo charcoal ( The insulating light-shielding printing ink according to any one of claims 1 to 6, wherein D50) is 2.5 μm or more and 8.0 μm or less.
[Claim 8]
The insulating light-blocking according to any one of claims 1 to 7 　, wherein a specific surface area of ​​the bamboo charcoal using a BET multipoint method by nitrogen adsorption is 100 m 2 / g or more and 1,000 m 2 / g or less. Printing ink.
[Claim 9]
　The insulating light-shielding printing ink according to any one of claims 1 to 8, which is used in protective panel printing with a touch function provided in an electronic device.
[Claim 10]
　The insulating member provided with the base material and the coating film by the printing ink for insulating light shielding as described in any one of the Claims 1 thru | or 9 formed on the said base material.
[Claim 11]
　The base material is one or more selected from polyester, polyamide, polycarbonate, acrylic, polyurethane, polyolefin, quartz glass, soda lime glass, alkali-free glass, sapphire glass, chemically strengthened glass, and composite materials thereof The insulating member according to claim 10, wherein the insulating member is formed using
[Claim 12]
　Use method of bamboo charcoal which uses bamboo charcoal as a printing ink for insulating light shielding with binder resin.
[Claim 13]
　Use of bamboo charcoal and binder resin for the production of insulating light-blocking printing ink.