Luminous white mortar, hardened body thereof, and method for strengthening weather resistance of hardened body thereof

Abstract

To provide a method for using a luminous pigment having material strength and service life in the same level as those of concrete or a tile base material.SOLUTION: A silicone resin solution is infiltrated into a luminous white mortar cured body obtained by incorporating a luminous pigment into white Portland cement to cover or fill voids in the mortar cured body with a cured product of a silicone resin, and the mortar cured body is fixed to concrete or a tile base material.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to the expansion of the use of phosphorescent pigments to infrastructure structures such as roads. [Background technology]

[0002] Glow-in-the-dark pigments convert irradiated light into electronic energy, store it, and emit fluorescence for a long time after irradiation has ceased. Aluminate-based glow-in-the-dark pigments, in particular, have excellent brightness and a long afterglow time, making this type the mainstream today. These are primarily used by coating transparent resin films and processing them into adhesive tapes. In this case, the glow-in-the-dark pigment is dispersed within the transparent resin layer. However, the resin carrier and the glow-in-the-dark pigment deteriorate over time when exposed to ultraviolet light, and the glow-in-the-dark pigment deteriorates due to hydrolysis when water penetrates, making them unsuitable for outdoor use. Summary of the Invention [Problem to be solved by the invention]

[0003] On the other hand, if phosphorescent pigments are encapsulated in transparent glass, they are protected from water and hydrolysis-induced degradation can be prevented. The inventors disclosed an application example of this technology in white line tiles for pedestrian guidance in 2016 (JP 2016-204242 A). However, while this technology meets the water-resistant requirement, it is expensive to manufacture and involves melting the glass frit at a high temperature of 800°C, which reduces brightness due to oxidation. Furthermore, the JIS standard for afterglow brightness is based solely on measurements at the time of manufacture, and does not include standards that take into account degradation over time during long-term outdoor use. In particular, when used in road-related structures, the durability of the carrier itself is as important as afterglow brightness. Therefore, the objective of this invention is to propose a method for using phosphorescent pigments in road-related structures that has the same level of material strength and service life. [Means for solving the problem]

[0004] To achieve this goal, the inventors investigated the potential of white Portland cement, which lacks transparency but is highly durable, as a carrier for phosphorescent pigments. Portland cement, a common cement, is made by coarsely crushing limestone, clay, silica, and iron materials, baking them at 1450°C, adding gypsum, and crushing them to a size of approximately 10 μm. White Portland cement is made by removing the iron, which causes its gray color. Here, we will discuss the differences in the constituent materials of concrete and mortar. The former consists of cement as a binder, sand as a fine aggregate, and gravel as a coarse aggregate. The latter consists of cement as a binder and various fine aggregates, typically sand but calcium carbonate in the case of white cement. Hardened concrete has excellent strength and serves as the framework of structures, while hardened mortar can be used as a covering material, filler, or binder for concrete structures, as well as connecting various materials. The cement to aggregate ratio is approximately 1:2–3.

[0005] When phosphorescent pigments are added to white mortar, the opaque components of the mortar generally block external light and prevent it from reaching the phosphorescent pigments dispersed within. However, this is incorrect. During the hydration process, cement hardens, creating countless capillaries and air bubbles ranging in size from submicron to 1mm. The amount of these voids is related to the cement-to-water (C / W) ratio, typically 50-60%. As a result, a significant amount of external light penetrates to a depth of approximately 2-3mm, albeit attenuated, through the voids. The phosphorescent pigments are excited by a wide range of light, from ultraviolet to visible light and infrared. While short-wavelength ultraviolet light cannot penetrate the surface, a certain percentage of long-wavelength visible light and infrared light can pass through the surface voids due to diffraction. This allows the phosphorescent pigments dispersed within the hardened material to use only visible and infrared light as excitation light sources. The addition of transparent materials such as glass beads increases light transmittance and improves brightness. The blending ratio can be freely determined within the range that allows for strength and durability, but is generally about 10 to 30%.

[0006] The level at which humans can vaguely detect light in the dark is 4mcd / m2. Although the primary purpose of this invention is not necessarily evacuation guidance in underground spaces or tsunami evacuation guidance at night, when considering the practicality of this hardened body, the afterglow brightness related to evacuation guidance specified in JIS Z9107 below is used as a reference. Afterglow luminance (mcd / m2) (normal light source lamp D65) Classification After 2 minutes After 10 minutes After 20 minutes After 30 minutes After 60 minutes JA 210 50 24 15 7 JB 440 105 50 31 15 JC 880 210 100 62 30 JD 1760 420 200 124 60 The test results for the hardened product based on the mix of Example 1 of the present invention were as follows. This product meets the JB classification and has proven to be fully practical for use as an evacuation guide sign. It goes without saying that this is just one example of a mix and can be freely modified depending on the intended use. 2 minutes later 10 minutes later 20 minutes later 30 minutes later 60 minutes later 526 150 79 54 29 (Nissenken Quality Evaluation Center 2025.05)

[0007] However, hardened cement products have a weakness: they are hydrous. Because hardened cement products contain water and saturated water vapor, if left untreated, calcium hydroxide will form, coating the phosphorescent pigment with a cloudy film. The resulting alkali will degrade the pigment, causing it to lose its phosphorescent function. This will also cause efflorescence, which will seep out onto the surface. Additionally, mold will grow on the surface, causing it to darken. This can be solved by the weather-resistance enhancement method described below. Specifically, the voids within the hardened product, which are the cause of this, are covered, or preferably filled, with a transparent hardened material. This insulates the hardened product from water and water vapor, preventing the formation of calcium hydroxide. Any durable material can be used as the transparent hardened material, but silicone resins composed of siloxane bonds (Si-O-Si), which have high bond energy and gas barrier properties, are particularly suitable.

[0008] Commercially available silicone resin solutions have a high viscosity and cannot penetrate the micron-level voids in the cured material. Therefore, it is recommended to dilute them with a solvent such as toluene to a viscosity of approximately 0.6-0.9 mPa·s, which is the same as or lower than that of water. The penetration depth is approximately 3-4 mm. Ideally, a depth of 2-3 mm would be sufficient, as it allows external light to reach the area. However, since these are intended for long-term use, the above-mentioned blocking function must be maintained even if the surface peels off due to wear or weathering. Furthermore, even if peeling progresses, a new phosphorescent layer is exposed, so the phosphorescent function is maintained for a long period of time.

[0009] The penetration method is either by brushing on the diluted solution or by immersing the material in a tank of diluted solution. The diluted solution penetrates rapidly into the hardened material depending on its viscosity, moving up into the voids. It then covers the voids and evaporates and hardens in about 20 minutes. When immersed, the solution does not dry out during penetration, so it can reach the deepest part and cover the entire interior of the hardened material with hardened silicone resin. [Effects of the Invention]

[0010] The present invention realizes a luminescent white mortar hardened body that is highly durable against rainwater, abrasion, ultraviolet light, efflorescence, and black mold, even when used outdoors, making it possible to integrate it with road-related structures for use. Its use in underground passages, station platforms, pedestrian guide tiles for the visually impaired, road boundary stones, etc., is extremely useful for ensuring safe passage at night. It is also important as a countermeasure for emergencies such as blackouts of urban power supplies. As detailed above, the greatest feature of this product is that it can be integrated with the structure to which it is attached and retain its luminescent function for the life of the structure. DETAILED DESCRIPTION OF THE INVENTION

[0011] The luminescent mortar of the present invention is expected to be used in two forms: one where it is produced in a factory as a hardened product, and one where it is used as a paste at the construction site. The former is for tall, solid objects like the protrusions on Braille tiles. In this case, the luminescent mortar is poured into a plastic or wooden mold to harden it, and then in a subsequent process it is fixed to a substrate such as tile or concrete using an epoxy adhesive. Depending on the situation, it may be possible to place the mold on top of the substrate, pour the luminescent mortar through the open top, and allow it to harden and fix. The latter is for applying it directly to the substrate such as tile or concrete. [Example]

[0012] ▲1▼ White Portland cement 40g ▲2▼ Phosphorescent pigment "WJPG-494" (Foshan Juliang Photo Luminescent) 40g ▲3▼ Glass beads (0.2 mm) 20 g ▲4▼ 25g water The above mixture was mixed into a phosphorescent mortar, which was then poured into a plastic container in the form of a flat plate 8 mm high and left to cure for 7 days, yielding three hardened mortar samples (No. 1, No. 2, No. 3). Meanwhile, a diluted solution of silicone resin "KR-251" (room temperature curing type, solids content 20%, Shin-Etsu Chemical) was added to toluene to dilute it to a concentration of 5%.

[0013] The cured product (No. 1) was immersed in the diluted solution, removed after 5 minutes, and left for 30 minutes to cure the silicone resin. As a comparative example, the diluted solution was brushed three times all around the cured product (No. 2), which was then dried and cured for 30 minutes. These cured products (No. 1 and No. 2) were then exposed outdoors for one year. Upon recovery and observation, no efflorescence or black mold had developed on the surface, and both had the same level of brightness. When the surface was cleaned and compared to the original cured product (No. 3), no reduction in brightness was observed.

[0014] Next, these were cut perpendicular to the plate and the cross sections were observed. As a result, no deterioration in the brightness of the cross section of the hardened body (No. 1) was observed across the entire area. In contrast, the cross section of the hardened body (No. 2) showed no deterioration in the outer shell, about 2 mm deep, but the rest of the interior had deteriorated and lost its phosphorescent function. This demonstrated that the phosphorescent function was maintained only in the area where the diluted solution had penetrated and hardened into a thick film, while the other areas were deteriorated by the alkali over time and lost their phosphorescent function. [Example]

[0015] A 30cm square, 8mm thick yellow glazed tile was prepared. It had 25 7mm diameter holes drilled in accordance with the JIS Braille tile standard. A film mold was also prepared, representing the female shape of the Braille tile protrusions. The base tile was then aligned with the film mold and placed on top of it. The luminescent mortar from Example 1 was then poured into the holes in the base tile. After hardening, the film mold was removed and the tile was cured for 7 days. As a result, the hardened luminescent mortar and the base tile were completely integrated and firmly bonded. This is because the hardened mortar, which filled the holes, acted as an anchor. Since the luminescent pigment was only required on the periphery of the Braille protrusions, low-cost regular mortar could be used for subsequent injection into other areas. The diluted solution was then poured through the mortar injection holes until the solution oozed from the surface of the Braille protrusions. As a result, the solution permeates the entire interior of the hardened mortar, and the surface of the Braille projections is completely sealed with the hardened silicone resin, completely preventing the intrusion of dirty liquids that would interfere with light emission. [Industrial Applicability]

[0016] It is expected to be used to ensure safe passage in underground spaces and road-related fields.

Claims

1. A method for enhancing the weather resistance of hardened mortar, characterized by impregnating a hardened mortar made by compounding white Portland cement with a phosphorescent pigment with a silicone resin solution and hardening the hardened mortar.

2. A hardened mortar produced by the method for improving the weather resistance of hardened mortar according to claim 1.

3. 3. The hardened mortar according to claim 2, wherein the silicone resin solution has penetrated and hardened to a depth of at least 2 mm from the surface.

4. A Braille tile, wherein the protrusions are the hardened mortar material according to claim 2 or 3.

5. The protrusions are made of a phosphorescent white mortar hardening material, which reaches the back side of the tile, and the silicone resin solution penetrates from the back side to the surface of the protrusions and hardens.