TWI663222B - Insulating light-blocking printing ink and insulating member - Google Patents

Abstract

The invention provides a printing ink which has high insulation and high concealment and does not damage the environment. The printing ink contains bamboo charcoal and an adhesive resin, and is suitable for printing with a touch function protection panel provided on an electronic device.

Description

Insulating light-shielding printing ink and insulating member

The present invention relates to an insulating light-shielding printing ink and an insulating member.

Conventionally, there have been various performance requirements for adding printability to inks. Among them, in the field of electronic equipment, it is required to use a black ink having an insulating property added to a light-shielding application. As such a black ink, carbon black or iron oxide is generally used. However, when carbon black is to be used in the field of electronic equipment, there is a problem that a sufficient impedance value cannot be obtained because carbon black has conductivity. In other words, although the more the amount of carbon black is increased, the more the light-shielding effect can be obtained, the higher the electrical conductivity is, the lower the insulation is. As a technique for solving such a problem, Patent Document 1 (Japanese Patent Application Laid-Open No. 2001-207079) discloses a technique regarding carbon black whose surface is covered with a resin.

In addition, from the viewpoint of environmental protection, new ink materials that can replace carbon black and iron oxide have been sought. As an environmentally friendly ink material, for example, Patent Document 2 (Japanese Patent Application Laid-Open No. 2008-179737) discloses an ink-related technology that can be added to food containing a carbon powder having a specific particle size.

However, the technology disclosed in Patent Document 2 is intended to be added to foods, and is not a technology focusing on the use of electronic devices. In addition, from the viewpoint of ensuring food safety, only prerequisites such as special adhesive resins that can be added to food can be used, and the materials that can be used are also limited.

The present inventors are determined to develop environmentally friendly inks for electronic devices that can replace the conventional carbon black. For the first time, research results have found that the use of bamboo charcoal enables the coexistence of high concealment and high insulation. In other words, the present invention is the first invention made focusing on the use of bamboo charcoal as an insulating light-shielding printing ink.

Therefore, an object of the present invention is to provide a printing ink for insulating shading containing bamboo charcoal and an adhesive resin.

Another object of the present invention is to provide an insulating member, specifically including a base material, and the insulating light-shielding printing ink coating film formed on the base material.

According to the present invention, it is possible to provide an ink that does not damage the environment, and can coexist high insulation and high concealment.

Hereinafter, embodiments of the present invention will be described in detail.

The printing ink for insulating shading of the present invention contains bamboo charcoal and an adhesive resin.

Bamboo charcoal is a substance that acts as a black ink, and is charcoal that can be obtained by burning bamboo.

Bamboo is easy to buy and inexpensive, and it is a material that does not damage the environment from the point of view of a loop-type resource. There are many types of bamboo. For example, real bamboo, light bamboo, Mengzong bamboo, hotspot bamboo, black bamboo, female bamboo, and root curved bamboo are usually used. These types may be used individually by 1 type, and may mix and use 2 or more types.

The method of firing bamboo is well known, and there are a method of firing in a carbon kiln and a mechanical firing method using a carbonization furnace made of stainless steel or the like. The mechanical firing method using a carbonization furnace includes a method of performing a heat treatment with heated water vapor in an oxygen-free atmosphere. In addition, the firing conditions are: firing in a carbon kiln at a high temperature of 400 to 1000 ° C for several days to about a week; when firing using a carbonization furnace mechanically, for example, 6 to 8 at a high temperature of 400 to 1000 ° C About hours. However, when heat treatment is performed with heated water vapor, it is usually performed within a short time of about 15 minutes to 1 hour.

Bamboo charcoal usually produces more fine pores than charcoal and the like. These tiny holes are macroscopic tubes of carbonized crystals of temporary ducts used to absorb the nutrition and moisture of bamboo, as well as finer microscopic tubes arranged on the inner wall without gaps, forming a so-called honeycomb structure. In addition, because the bamboo's fiber structure is arranged vertically and linearly, these fine holes are relatively easy to gather and arrange in a linear fashion. In addition, the average pore diameter of the macro tube is about 10 to 40 μm, and the average pore diameter of the micro tube is about 1 to 5 nm.

In addition, bamboo contains many silicic acid and potassium, and these elements have the property of solidifying into a glass when they are fired into bamboo charcoal. Therefore, bamboo charcoal is generally considered to contain more glassy substances than charcoal and the like.

The specific surface area of bamboo charcoal is, for example, a value calculated by the BET multi-point method of nitrogen adsorption, preferably 100 m ² / g or more, more preferably 200 m ² / g or more.

On the other hand, the specific surface area of bamboo charcoal is preferably 1,000 m ² / g or less, and more preferably 500 m ² / g or less. This can improve concealment.

The specific surface area of bamboo charcoal can be measured in accordance with JIS Z8830.

The 50% particle diameter (D50) of bamboo charcoal is preferably 0.05 μm or more, and more preferably 1 μm or more. Thereby, appropriate dispersibility can be obtained.

On the other hand, the 50% particle diameter (D50) of bamboo charcoal is preferably 10 μm or less, and more preferably 5 μm or less. This makes it possible to form an appropriate coating film and improve concealment.

In addition, the 90% particle diameter (D90) of bamboo charcoal is preferably 20 μm or less, and more preferably 10 μm or less.

In addition, the 50% particle diameter (D50) and 90% particle diameter (D90) of bamboo charcoal can be obtained by measuring the fineness distribution by volume reference using the laser refraction · scattering method, for example.

The content of bamboo charcoal is preferably 40 parts by weight or more, and more preferably 70 parts by weight or more relative to 100 parts by weight of the solid content in the insulating shading printing ink. As a result, printing characteristics can be maintained and concealment can be improved. It is also possible to improve insulation.

On the other hand, the content of bamboo charcoal is preferably 90 parts by weight or less, and more preferably 80 parts by weight or less, based on 100 parts by weight of the solid content in the insulating shading printing ink. Thereby, proper fluidity can be obtained, and good printing can be completed.

From the viewpoint of making ink characteristics more appropriate, the surface of bamboo charcoal may be physically or chemically treated.

Adhesive resin is used to disperse bamboo charcoal and form a printed coating film.

As long as the adhesive resin is a chemically organic synthetic resin, various resins can be used. From the standpoint of good compatibility with bamboo charcoal, and coexistence of high insulation and concealment at a higher level, as the adhesive resin, vinyl chloride-vinyl acetate copolymer resin, acrylic resin, polyester resin are preferred. , Epoxy resin, polycarbonate resin, polyolefin resin, synthetic rubber, cellulose resin, maleic acid resin, phenolic resin, polyurethane resin, polyamide resin, polyimide resin, melamine formaldehyde resin, phenoxy Resins, active energy ray-curable resins, modified products of these, and one or two or more resins selected from modified natural resins. Among them, more preferred are vinyl chloride-vinyl acetate copolymer resins, acrylic resins, polyester resins, or epoxy resins, or modified products of these resins, and the most preferred is polyester resin.

The content of the adhesive resin is preferably at least 10 parts by weight, more preferably at least 20 parts by weight relative to 100 parts by weight of bamboo charcoal. On the other hand, it is preferably at most 150 parts by weight, and more preferably at 120 parts by weight under. A setting higher than the lower limit value enables good printability, while a setting lower than the upper limit value enables coexistence of insulation and concealment at a higher level.

The insulating light-shielding printing ink of the present invention contains bamboo charcoal and an adhesive resin, so that insulation and concealment can coexist. Although the details of this mechanism are not clear, as mentioned above, bamboo charcoal usually contains more fine pores than charcoal, and has a structure in which fine pores are arranged without gaps called a honeycomb structure. Therefore, the adhesive resin can flow near the entrance of these fine holes and inside the holes. In addition, since bamboo charcoal generally contains more glassy substances than charcoal, it is considered to have better wettability with adhesive resins than charcoal.

As a result, an adhesive resin is formed to seal the bamboo charcoal. Increasing the blending ratio of bamboo charcoal can reduce the resistance even if the concealability is improved. Therefore, it is possible to predict that insulation and concealment can coexist. . Furthermore, even when the bamboo-charcoal with relatively high conductivity is used for the printing ink for insulating light-shielding of the present invention, as described above, the bamboo-charcoal is sealed with an adhesive resin, so that good insulation can be obtained.

By satisfying the following conditions, the printing ink for insulating light-shielding of the present invention can co-exist insulation and concealment at a high level. Although this reason is not clear, the inventors have repeatedly studied the printing ink for insulating light-shielding using bamboo charcoal, and found that it can be effectively achieved by controlling the optical density (OD) value in this condition within a specific range. It is suitable for the index of coexistence of concealability and insulation properties for the use of printing inks for insulating shading. The insulating light-shielding printing ink of the present invention uses a wire diameter of 6 A mil printing tester (manufactured by RK Print Coat Instruments Ltd., crossbar No. 2), pulled at a moving speed of 50 mm / sec, and applied on a glass substrate to obtain the optical density (OD) value of the obtained coating It is preferably 1.0 or more and 7.0 or less. The coating film was obtained after drying at 80 ° C for 60 minutes.

The optical density (OD) value of this coating film is more preferably 3.5 or more from the viewpoint of obtaining concealability. On the other hand, the optical coating film (OD) value of the coating film is more preferably 6.0 or less from the viewpoint of obtaining good ink fluidity, printing characteristics, and adhesion.

In the insulating light-shielding printing ink of the present invention, in order to control the optical density (OD) value of the coating film, by controlling the firing temperature of bamboo charcoal, the type of adhesive resin specifically adapted to the average particle diameter, specific surface area, etc. It is the first time to control the ratio of bamboo charcoal and adhesive resin, and the degree of dispersion of bamboo charcoal to adhesive resin. In addition, in order to control the degree of dispersion, according to the combination of bamboo charcoal and adhesive resin, etc., for example, it can be performed by selecting the shear strength and the number of treatments in the dispersing equipment.

The (OD) value refers to a value in which the light transmittance (T%) is represented by a logarithm. Generally, a higher OD value means a lower light transmittance.

The OD value can be measured using, for example, a transmission density meter "Model 341C" (manufactured by X-Rite).

In addition, the printing ink for insulating light-shielding of the present invention may be blended with pigments other than bamboo charcoal as long as the effects of the present invention are not impaired. In this case, the content of bamboo charcoal for all pigments is high from From the viewpoint of insulation, it is preferably 50% by mass or more, more preferably 80% by mass, or 100% by mass.

The insulating light-shielding printing ink of the present invention may contain well-known additive components for inks. Examples of well-known additives for inks include stabilizers such as solvents and antioxidants, levelling agents, defoamers, thickeners, anti-settling agents, wetting and dispersing agents, antistatic agents such as antistatic agents, antifog agents, and paraffin waxes. , Slip agents, coupling agents, silane coupling agents, near-infrared absorbers and other additives.

The printing ink for insulating light-shielding is formed by mixing bamboo charcoal and an adhesive resin by a known method. For example, by adding bamboo charcoal to a resin adhesive and dispersing using an appropriate dispersing device, an ink can be obtained. At this time, from the viewpoint of controlling the optical density (OD) value within the specified range, for example, when using a three-roll grinding and dispersing device, the linear pressure of each roll is set to 20 N / mm to 60 N / mm. In order to apply an appropriate shearing force, and the number of processing times (passing times) is preferably set to more than two times.

The printing ink for insulating shading of the present invention is particularly suitable for printing with a touch function protection panel provided on electronic devices such as smart phones, tablet computers, car navigation systems, and walkie-talkies that require shading performance. By using the printing ink for insulating light-shielding of the present invention, in such applications, it is possible to block the backlight in an electronic device, to obtain a high concealability such as to hide the electrode wiring inside the electronic device, and to prevent malfunction of the electronic device.

<Insulating member>

The insulating member of the present invention includes a substrate and the printing ink coating film for insulating light-shielding formed on the substrate.

The substrate is not particularly limited, and may be selected from polyester, polyamide, polycarbonate, acrylic, polyurethane, polyolefin, quartz glass, soda lime glass, non-glass, sapphire glass, chemically toughened glass, and composites from these. The material is formed by using one or two or more materials. The surface of the substrate formed of these materials may be subjected to anti-fogging treatment, tempering treatment, anti-reflection treatment, hot wire cutting treatment, coloring treatment, or ITO (indium oxide. Tin) conductive film treatment. The shape of the substrate is not particularly limited.

The method for forming the coating film is not particularly limited, and a known method can be used. The thickness of the coating film is, for example, 3 to 200 μm.

Examples of the insulating member include a protective panel with a touch function of the electronic device.

In addition, the insulating member may be a single layer or other multilayers between the substrate and the insulating light-shielding printing ink coating film. Further, it may have a plurality of coating film layers made of the insulating light-shielding printing ink. For example, a coating film layer made of a white ink may be stacked on a substrate, and a coating film layer made of the insulating light-shielding printing ink may be stacked on the substrate.

<How to use bamboo charcoal>

In the method for using bamboo charcoal according to the present invention, bamboo charcoal is used as the printing ink for insulating shading. Therefore, it is possible to provide an ink capable of coexisting insulation and concealment without damaging the environment in which the loop-based resources are used.

The embodiments of the present invention have been described above. These are the present invention For example, various configurations other than the above may be adopted.

The following uses several embodiments to illustrate the application of the present invention, but it is not intended to limit the present invention. Those with ordinary knowledge in the technical field of the present invention can make various changes and modifications without departing from the spirit and scope of the present invention. Retouch.

Examples

The pigments used in the examples and comparative examples are shown in Tables 1 and 2 below.

The adhesive resins used in the examples and comparative examples are shown in Table 3 below.

<Examples 1 to 11>

In order to obtain the compounding ratio (parts by weight) shown in Table 4, an organic solvent (isophorone, manufactured by EVONIK Industrial Co., Ltd.) and bamboo charcoal were added to the adhesive resin, and pre-mixed with a small rotary wing mixer. Then, using a three-roll grinding and dispersing device (Model SDY-200 manufactured by BUHLER Co., Ltd.), the ink was obtained by dispersing under a condition that the roll linear pressure was set to 40 N / mm and the number of passes was two.

<Comparative Examples 1 to 9>

In order to obtain the blending ratio (parts by weight) shown in Table 4, coconut shell carbon D, carbon black E, or iron oxide F were used instead of bamboo charcoal. Other components were the same as those in Examples 1 to 9 to obtain inks.

The inks obtained in the actual examples and the comparative examples were measured and evaluated as follows. The results are shown in Tables 4 and 5.

Measurement: Using a printing tester (made by RK Print Coat Instruments Ltd., crossbar No. 2) with a wire diameter of 6 mils, the ink was drawn on a glass substrate at a moving speed of 50 mm / sec. It dried under the condition of minutes, and the coating film was obtained. The optical density (OD) values of the obtained coating films were measured.

Evaluation-Insulation: Measurement of impedance (Ω)

The ink was coated on a glass substrate using a printing tester (made by RK Print Coat Instruments Ltd., crossbar No. 2) with a wire diameter of 6 mils at a moving speed of 50 mm / sec. Dry under the conditions to form a coating film.

Using a super-insulation meter "Model SM-21E" (manufactured by Toa Radio Industry Co., Ltd.), the distance between the terminals was measured at 15 mm, and the surface of the coating film was lightly pressed to measure the resistance value of the surface of the coating film. The measurement voltage is 1kV, and 3 points are measured, and the average value is taken. The measurement range when the measurement voltage is 1kV is 1.0 × 10 ⁶ Ω ~ 2.0 × 10 ¹³ Ω.

Concealment: visual sensory evaluation

The ink was coated on a glass substrate using a printing tester (made by RK Print Coat Instruments Ltd., crossbar No. 2) with a wire diameter of 6 mils at a moving speed of 50 mm / sec. Dry under the conditions to form a coating film to obtain a printed matter.

The light of the fluorescent lamp is irradiated from the printing surface side (the coating film surface side) of the obtained printed matter, and the concealment of the light of the fluorescent lamp viewed from the glass substrate side is performed by a skilled expert in four stages. evaluation of.

：: The light from the fluorescent lamp is completely transparent.

(Circle): The light of a fluorescent lamp transmitted a little.

△: The light from the fluorescent lamp is transmitted to some extent.

×: A considerable amount of light from the fluorescent lamp is transmitted.

Although the present invention has been disclosed as above with several embodiments, it is not intended to limit the present invention. Any person with ordinary knowledge in the technical field to which the present invention pertains can make various modifications without departing from the spirit and scope of the present invention. Changes and retouching, so the protection scope of the present invention shall be determined by the scope of the appended patent application.

Claims (6)

An insulating light-shielding printing ink containing bamboo charcoal and an adhesive resin (except for resins that can be used for food addition), characterized in that the adhesive resin is made of vinyl chloride-vinyl acetate copolymer resin, acrylic resin, polymer Ester resin, epoxy resin, polycarbonate resin, polyolefin resin, maleic resin, phenolic resin, polyurethane resin, polyamide resin, polyimide resin, melamine formaldehyde resin, phenoxy resin, and active energy Wire-curable resins, these modified products, and one or two or more resins selected from modified natural resins; the content of the bamboo charcoal is relative to that of the printing ink for insulating shading. The solid content is 100 parts by weight, 40 parts by weight or more and 90 parts by weight or less. According to claim 1, the insulating light-shielding printing ink is characterized in that the insulating light-shielding printing ink is drawn at a moving speed of 50 mm / sec with a printing tester having a wire diameter of 6 mils, and the glass When coated on a substrate, the optical density (OD) value of the obtained coating film is 1.0 or more and 7.0 or less. The insulating light-shielding printing ink according to any one of claims 1 to 2, wherein the 50% particle diameter (D50) of the bamboo charcoal is 0.05 μm or more and 10 μm or less. An insulating member specifically includes a base material and the printing ink coating film for insulating light-shielding described in any one of claim 1 to claim 3 formed on the base material. The insulating member according to claim 4, wherein the base material can be selected from polyester, polyamide, polycarbonate, acrylic, polyurethane, polyolefin, quartz glass, soda lime glass, non-glass, Sapphire glass, chemically tempered glass, and composite materials selected from these are formed using one or two or more materials. A bamboo charcoal application method using bamboo charcoal and an adhesive resin (except for resins that can be added to food) as a printing ink for insulating shading, characterized in that the adhesive resin is copolymerized from vinyl chloride and vinyl acetate Resin, acrylic resin, polyester resin, epoxy resin, polycarbonate resin, polyolefin resin, maleic resin, phenolic resin, polyurethane resin, polyamide resin, polyimide resin, melamine formaldehyde resin, phenoxy Base resin, active energy ray-curable resin, modified products of these, and one or two or more resins selected from modified natural resins; the content of the bamboo charcoal relative to the insulation The solid content in the light-shielding printing ink is 100 parts by weight, 40 parts by weight or more and 90 parts by weight or less.