Mouthpiece and platinum coating film

Abstract

This invention provides an antibacterial mouthpiece that can suppress the growth of bacteria and viruses in the oral cavity, particularly in the teeth, when worn. [Solution] The mouthpiece 1 of the present invention is a mouthpiece that is worn over the teeth, characterized in that the inner surface 11 and / or outer surface 12 of the mouthpiece that face the teeth are coated with platinum.

Description

Technical Field

[0001] The present invention relates to a mouthpiece that is worn over teeth, and particularly to an antibacterial mouthpiece that suppresses the growth of bacteria and viruses. The present invention also relates to a platinum coating film formed on a resin base material including a mouthpiece and a sheet-like resin base material on which the platinum coating film is formed.

Background Art

[0002] A mouthpiece is an instrument worn over teeth, and there are medical instruments such as those for orthodontics, snoring, teeth grinding, and sleep apnea. In addition, it is also used as a tool for preventing damage to teeth and the oral cavity in sports, such as boxing and rugby. The mouthpiece is removable from the oral cavity, and it can be kept clean by removing the mouthpiece and cleaning it regularly. However, a mouthpiece as a medical instrument is scheduled to be worn for a long time. For example, in the case of an orthodontic mouthpiece, it is necessary to wear it for at least 17 to 20 hours a day. For snoring, teeth grinding, and sleep apnea, it is also necessary to wear it during sleep. Thus, if the mouthpiece is continuously worn for a long time, bacteria in the oral cavity and the like grow on the surface of the mouthpiece, causing tooth decay, periodontal disease, and even tooth loss.

[0003] Conventionally, attempts have been made to impart an antibacterial action to a mouthpiece by mixing various antibacterial agents into the material constituting the mouthpiece. Patent Document 1 discloses an antibacterial mouthpiece in which protamine silica, a bio-antibacterial agent derived from nature, is mixed. Patent Document 2 also discloses a mouthpiece formed by mixing Advance Clay, which has high safety derived from nature, detoxifying properties, and antibacterial and bactericidal effects that suppress inflammation and pain, into a silicone resin.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] Conventional methods require the use of materials containing antibacterial agents, making it impossible to impart antibacterial properties to mouthpieces that do not use such materials. Furthermore, uneven distribution of the antibacterial agent within the material can lead to inconsistent antibacterial effects, raising concerns about bacterial growth in areas with weaker antibacterial properties. Additionally, for mouthpieces that need to be worn continuously in daily life, such as orthodontic mouthpieces, designs are made to be transparent to be inconspicuous. However, adding antibacterial agents reduces transparency, making the mouthpiece more noticeable.

[0006] In view of the above problems, the present invention aims to provide an antibacterial mouthpiece that can suppress the growth of bacteria and viruses in the oral cavity, particularly in the teeth, when worn. Another objective is to provide an antibacterial mouthpiece that is inconspicuous when worn without compromising transparency. Furthermore, another objective of the present invention is to provide a platinum coating film that is transparent to visible light and also has antibacterial properties on a resin substrate or the like, such as the material of the mouthpiece. [Means for solving the problem]

[0007] To solve the above problems, the present invention provides a mouthpiece that is worn over the teeth, characterized in that a platinum coating film is formed on the inner surface of the mouthpiece that faces the teeth. Another mouthpiece of the present invention provides a mouthpiece that is worn over the teeth, characterized in that a platinum coating film is formed on the outer surface of the mouthpiece. Furthermore, in the above mouthpiece, the platinum coating film is preferably formed by a sputtering method, has visible light transmittance, and preferably has a visible light transmittance of 95% or less, 90% or less, or 85% or less, and / or a visible light transmittance of 30% or more, 50% or more, or 80% or more. Furthermore, in the above mouthpiece, it is preferable that the antibacterial activity value against Streptococcus mutans on the surface of the mouthpiece on which the platinum coating film is formed is 2.0 or more, 2.5 or more, or 3.0 or more.

[0008] Furthermore, the platinum coating film of the present invention is formed using a sputtering method, and the platinum coating film is characterized by being transparent to visible light and having a visible light transmittance of 95% or less, 90% or less, or 85% or less. Furthermore, the sheet-like resin substrate for molding the mouthpiece of the present invention is characterized in that a platinum coating film having visible light transmittance and a visible light transmittance of 95% or less, 90% or less, or 85% or less is formed on at least one of the surface or back surface of the resin substrate. Furthermore, the platinum coating film may have a visible light transmittance of 30% or more, 50% or more, or 80% or more. In addition, it is preferable that the antibacterial activity value against Streptococcus mutans on the surface of the platinum coating film is 2.0 or more, 2.5 or more, or 3.0 or more. [Effects of the Invention]

[0009] The mouthpiece of the present invention has a platinum coating film formed on the inner surface of the mouthpiece that faces the teeth. Therefore, the antibacterial effect of platinum not only keeps the inner surface of the mouthpiece clean, but also kills bacteria or viruses on the surface of teeth that come into contact with or are close to the inner surface of the mouthpiece, thus keeping the tooth surface clean and contributing to the prevention of tooth decay and periodontal disease. Furthermore, the mouthpiece of the present invention has a platinum coating film formed on the outer surface of the mouthpiece. Therefore, the antibacterial effect of platinum keeps the outer surface of the mouthpiece clean and suppresses the growth of bacteria or viruses in the oral cavity. In addition, by forming a platinum coating film with visible light transmittance of 95% or less, 90% or less, or 85% or less using a sputtering method, an antibacterial mouthpiece can be provided without compromising transparency so that it is not noticeable when worn. In particular, if the visible light transmittance of the platinum coating film is 30% or more, 50% or more, or 80% or more, the mouthpiece becomes even less noticeable when worn. By having an antibacterial activity value against Streptococcus mutans on the surface of the mouthpiece of 2.0 or higher, 2.5 or higher, or 3.0 or higher, it is possible to kill Streptococcus mutans, which causes tooth decay, on the inner surface of the mouthpiece that faces the teeth and in the oral cavity, thus preventing tooth decay with the mouthpiece of the present invention.

[0010] Furthermore, the platinum coating film of the present invention is formed using a sputtering method, has visible light transmittance, and has a visible light transmittance of 95% or less, 90% or less, or 85% or less. Therefore, it is possible to impart antibacterial properties to the substrate to which the film is formed by the platinum coating film, while also providing an inconspicuous platinum coating film. For this reason, the surface of the substrate can be seen through the platinum coating film, and in the case of a translucent substrate, the translucency of the substrate can be maintained to a certain extent. For example, the platinum coating film of the present invention can be used not only for mouthpieces, but also as an antibacterial coating for lenses, eyeglasses and sunglasses, watch glass, display screens of mobile phones and smartphones, display screens of other machines, televisions, showcases, window glass, etc. [Brief explanation of the drawing]

[0011] [Figure 1] (A) and (B) are photographs of the mouthpiece's appearance. [Figure 2] (A) and (B) are photographs after film deposition using 400W DC for 30 seconds and 15 seconds, respectively. (C) through (E) are photographs after film deposition using 200W DC for 30 seconds, 15 seconds, and 2 seconds, respectively. (F) is a photograph after film deposition using 160W DC for 1 second. [Figure 3] (A) is a photograph after film deposition with AC 20W: irradiation time 30 seconds, (B) is a photograph after film deposition with AC 40W: irradiation time 15 seconds, (C) is a photograph after film deposition with AC 60W: irradiation time 15 seconds, (D) is a photograph after film deposition with AC 100W: irradiation time 2 seconds. [Figure 4] Analysis results of the surface composition of a portion of the platinum-coated surface of the mouthpiece. [Figure 5] (A) is a graph showing the relationship between film deposition time and transmittance at an output of 20W, and (B) is a graph showing the relationship between RF output and transmittance at an irradiation time of 30 seconds. [Figure 6] Diagram illustrating the test system overview for the test sample. [Modes for carrying out the invention]

[0012] Figures 1(A) and (B) are photographs of the external appearance of mouthpiece 1. Mouthpiece 1 is worn by placing it over the teeth and has an inner surface 11 that faces the teeth and an outer surface 12 that is exposed to the oral cavity. Mouthpiece 1 may cover all of the upper and / or lower teeth, some of the upper teeth, some of the lower teeth, or some of the upper and lower teeth. The mouthpiece may be a mouth-formed type, molded in the oral cavity from softened synthetic resin, or a custom-made type, fabricated on a dental model after individual impressions (dental molds). Impressions may be taken using impression material, or by optical impression taking, which involves scanning with an intraoral scanner to obtain three-dimensional data of the oral cavity.

[0013] The material used for the mouthpiece and the resin surface to be coated in the present invention can be a synthetic resin (plastic). While safety is required for the thermoplastic resin, it can be selected considering the application and processability. Examples include polyethylene terephthalate (PET), ethylene vinyl acetate copolymer (EVA), ABS (acrylonitrile butadiene styrene copolymer), silicone resin, polyamide (PA), polyoxymethylene (POM), polybutylene terephthalate (PBT), or polyolefins such as polyethylene (PE), polypropylene (PP), and polyethylene dicyclopentadiene polymer (COC), polymethyl methacrylate (PMMA), polyester, polycarbonate (PC), polyvinyl chloride (PVC), polylactide (PLA), polystyrene (PS), or thermoplastic elastomers selected from ethylene-propylene-diene-rubber or styrene / butadiene / styrene block copolymer (SBS) and styrene / ethembutene / styrene (SEBS) and polyurethane. Furthermore, the resin substrate of the present invention is a substrate having a resin surface in at least a part of the area to be film-formed, and may be composed solely of resin, or it may be a combination of resin and one or more other materials, such as metal, wood, glass, ceramic, etc.

[0014] The mouthpiece of the present invention has its inner surface 11 and / or outer surface 12 coated with platinum. It is preferable to coat at least the inner surface 11 of the mouthpiece with platinum. Since the inner surface 11 contacts or is disposed very close to the teeth, not only can the growth of bacteria on the inner surface of the mouthpiece be suppressed by the antibacterial effect of platinum on the inner surface 11, but also the growth of bacteria on the surface of the teeth can be suppressed. Further, the outer surface 12 of the mouthpiece may be coated with platinum. The outer surface 12 is exposed in the oral cavity, and the antibacterial effect of platinum on the outer surface 12 can obtain the effect of suppressing the growth of bacteria in the oral cavity. Coating the inner surface 11 and the outer surface 12 with platinum for therapy is preferable because it can suppress the growth of bacteria on the inner surface of the mouthpiece, the surface of the teeth, and in the oral cavity.

[0015] The present invention may involve forming a platinum coating film on the surface and / or back surface of a sheet-like resin substrate before molding it into a mouthpiece, and then molding the resin substrate with the platinum coating film into the shape of a mouthpiece, or forming a platinum coating film on the inner surface and / or outer surface after molding it into a mouthpiece. Forming the platinum coating film on the sheet-like resin substrate beforehand is superior in terms of production efficiency because mouthpieces can be obtained immediately after obtaining a dental impression, they can be kept in stock, and require less storage space. However, when molding the resin substrate into the shape of a mouthpiece, it is heated and pressure-molded, and the presence of a platinum coating film increases thermal conductivity. Therefore, if the coating film is thick, molding under the same conditions as an uncoated resin substrate results in significant thermal deformation, making it impossible to mold it into an accurate shape that matches the dental impression. While molding is possible by changing the heating time and temperature, forming a thick platinum coating film on a sheet-like resin substrate presents challenges in molding conditions. Therefore, the platinum coating film preferably has a visible light transmittance of 30% or more (film thickness of 15 nm or less), more preferably 50% or more, and even more preferably 80% or more. Furthermore, in the case of a platinum coating film with antibacterial properties that also possesses visible light transmittance, the visible light transmittance is preferably 30% or more, more preferably 50% or more, and even more preferably 80% or more. When forming the platinum coating film after molding the mouthpiece, there are no issues with molding conditions, but for a mouthpiece with visible light transmittance, the visible light transmittance is preferably 30% or more, more preferably 50% or more, and even more preferably 80% or more.

[0016] The platinum coating film formed on the mouthpiece of the present invention is preferably coated with nanoparticle platinum by a sputtering method. Platinum particles (nanoparticle platinum) with a diameter of 100 nm or less, typically 10 nm or less, are unstable by themselves and have the property of aggregating and binding to each other. Therefore, they are usually used in a form called platinum nanocolloid dispersed in a medium with their surroundings covered with water molecules and their surfaces further covered with a colloidal protective film. Conventionally, in order to immobilize platinum on the surface of an object that requires antibacterial properties and apply an antibacterial coating, a platinum nanocolloid solution has been applied or sprayed onto the surface of the object to coat the surface of the object with nanoparticle platinum. However, as shown in the following comparative example, even when a platinum nanocolloid solution was sprayed onto the mouthpiece and dried, the hydrophilicity was poor, unevenness occurred, and it was difficult to coat it uniformly, and an antibacterial effect could not be obtained.

[0017] [Comparative Example] Antibacterial properties of a PET substrate coated with a platinum nanocolloid solution Antimicrobial testing was conducted on a sheet-like PET substrate used as the material for a mouthpiece, specifically on a sample coated with a platinum nanocolloid solution (coated PET) and on a PET substrate without the solution (uncoated PET) to improve accuracy. The antimicrobial testing was carried out under the following conditions, with reference to JIS2801. Figure 6 is a diagram illustrating the outline of the test system for the test specimen, showing the cross-sectional structure of the test system. A filter paper 32 soaked in water was placed at the bottom of a φ90 mm sterile polystyrene petri dish 31 for humidification, and a φ60 mm sterile polystyrene petri dish lid 33 was placed on top of it as a base. The test specimen 34 was placed on the lid 33, and 0.4 mL of test bacterial solution 35 was dropped onto the test specimen 34. A 40 mm square covering film 36 was then placed over it, ensuring that the test bacterial solution 35 spread across the entire evaluation area of ​​the test specimen 34. Furthermore, a sterile petri dish lid 37 was placed over a larger petri dish 31 to create the test system, and it was allowed to act for 24 hours under conditions of 35°C ± 1°C and 90% RH or higher. Test sample 34 consisted of three PET substrates coated with a 50mm square platinum nanocolloid solution (coated PET), three PET substrates without the platinum nanocolloid solution (uncoated PET) for improved accuracy, and three 50mm square unprocessed films (reinforced polyethylene) as a control. Before testing, both sides were irradiated with a pulsed xenon lamp (Comet, BHX-200) for 20 seconds to clean the surface. The test bacteria used was Streptococcus mutans. Frozen strains were inoculated onto tryptone soy agar (TSA) plates and cultured at 36°C ± 1°C for 18 hours. After further inoculation onto the same medium and cultured at 36°C ± 1°C for 20 hours, the developed colonies were transcribed and fermented in 1 / 500 concentration ordinary broth medium for approximately 10 minutes. 6 Prepared at a concentration of cells / mL, this was designated as test bacterial suspension 35.

[0018] After 24 hours, test specimens 34 (coated PET, uncoated PET, and unprocessed film) were collected in a sterile bag containing 10 mL of SCDLP broth medium (inactivator), and the test bacteria were washed out of the specimens. The washed-out solution was used as the sample solution for bacterial count measurement. A dilution series was prepared using phosphate-buffered saline (prepared by diluting 3.4% phosphate buffer 800 times with saline). 1 mL each of the undiluted and diluted sample solutions were transferred to a sterile petri dish, mixed with approximately 20 mL of TSA, solidified, and incubated at 36°C ± 1°C for 44-45 hours. After incubation, 1 cm 2 The number of test bacteria per unit area was determined. Table 1 shows the number of test bacteria (cells / cm³) for each test product. 2 (This indicates a lower limit of quantification: 2.5 particles / cm²) 2 ).

[0019] From the obtained test bacterial counts, the antimicrobial activity values ​​(R) of coated and uncoated PET films were calculated using the following formula, with the uncoated film used as a control. The antimicrobial activity values ​​were rounded down to one decimal place, with the second decimal place truncated. R = (Ut - Uo) - (At - Uo) = Ut - At Here, R is the antibacterial activity value, Uo is the average logarithmic value of the number of test bacteria immediately after inoculation of the untreated film, Ut is the average logarithmic value of the number of test bacteria after the reaction time of the untreated film, and At is the average logarithmic value of the number of test bacteria after the reaction time of the mouthpiece material coated with nanoplatinum particles. Table 1 shows R, Uo, Ut, and At.

[0020] [Table 1]

[0021] According to JIS 2801, an antimicrobially treated product is considered to have an antimicrobial effect when its antimicrobial activity value (R) is 2.0 or higher. However, as shown in Table 1, the R value of the coated PET was 0.6, and although the number of bacteria was lower than that of the untreated film, it did not show the antimicrobial effect required by JIS standards. The R value of the uncoated PET was 0.3, indicating that applying a platinum nanocolloid solution did not provide any significant antimicrobial effect.

[0022] Therefore, in this invention, a uniform nanoplatinum particle coating film was obtained by coating the surface of a mouthpiece with nanoplatinum particles using the sputtering method. The sputtering method first introduces a discharge gas into a vacuum chamber and generates plasma of the discharge gas by applying a voltage. Gas ions generated by the plasma generated in the vacuum collide with the surface of a target (film-forming material), ejecting the material (atoms and molecules) that make up the target, and forming a film of the target on the surface of the substrate to be coated. A shutter is placed between the target and the substrate, shielding the target material when the shutter is closed, and allowing the target material to reach the substrate surface and form a film when the shutter is open. In the initial stages of film formation, the target material (atoms and molecules) incident on the substrate surface usually moves around finely on the substrate due to the surface diffusion (also called surface migration) effect. Here, atoms or molecules are unstable while they are alone and re-evaporate after a certain residence time. However, when they collide with other atoms or molecules or groups of atoms and bond, they form a cluster of atoms, increasing the bond energy between the cluster and the substrate surface, greatly reducing the possibility of re-evaporation. In addition, target atoms may settle on stable sites as they move around, thus depositing on the substrate. The magnetron sputtering apparatus used for film deposition places a magnet behind the target, trapping electrons at high density in the magnetic field and creating a space with high electron density near the target surface. In a space with high electron density, the probability of collisions between electrons and the discharge gas increases, allowing for the creation of a dense plasma region, and enabling more positive ions to collide with the target compared to conventional sputtering.

[0023] Platinum deposition by sputtering has traditionally been used in fields such as communication equipment, electronic components, and semiconductors to form conductive or corrosion-resistant electrodes. However, when platinum was deposited on a resin substrate, such as the material for a mouthpiece, under the same deposition conditions as in those applications, the resin substrate would deform due to heat or impact. Therefore, by lowering the power applied to the discharge gas or shortening the plasma irradiation time (the time the shutter between the target and the substrate is open), it was possible to deposit platinum without damaging the resin substrate. Furthermore, by adjusting the output power and irradiation time, it was possible to form a platinum coating film with visible light transmittance. However, it was found that if the platinum coating film was made too thin and the visible light transmittance was too high, the antibacterial effect could not be obtained. Since an antibacterial effect cannot be obtained with a platinum coating film with a visible light transmittance of 96.6%, the platinum coating film of the present invention and the mouthpiece formed thereon preferably have a visible light transmittance of 95% or less, more preferably 90% or less, and even more preferably 85% or less. Furthermore, it was confirmed that a platinum coating film with a visible light transmittance of 30.4% also exhibits visible light transmittance. Therefore, the platinum coating film of the present invention and the mouthpiece formed thereon preferably have a visible light transmittance of 30% or more, and in applications where transparency is particularly important, a visible light transmittance of 50% or more is more preferable, and even more preferable is 80% or more.

[0024] [Example 1] Formation of platinum coating film using a DC power supply Figures 2(A) and (B) are photographs taken after depositing a film on a circular sheet-shaped PET substrate (without heating: the substrate was not heated during film formation; the same applies hereinafter) placed 70 mm away from a target, using a platinum metal plate as the target and argon as the discharge gas, with 400W of power applied from a DC power supply (DC) for 30 seconds and 15 seconds of irradiation time, respectively. Figures 2(C) to (E) are photographs taken after depositing with 200W DC: irradiation time of 30 seconds, 15 seconds, and 2 seconds, respectively, and Figure 2(F) is a photograph taken after depositing with 160W DC: irradiation time of 1 second. In all cases, it can be confirmed that a platinum coating was formed on the resin surface without damaging the resin substrate. Although there was a tendency for the coating film to become thinner when the power was reduced or the irradiation time was shortened, a metallic mirror finish of platinum was confirmed on all surfaces, and it was not possible to form a platinum coating film with visible light transmittance at output up to 160W. However, by further reducing the output of the DC power supply, it was possible to form a platinum coating film on the resin surface that is transparent to visible light (appears black to the naked eye but is transparent). Furthermore, when the irradiation time was kept very short, to 1-2 seconds, even slight variations in irradiation time greatly affected the film quality, making it difficult to provide a stable and uniform platinum coating film. In Figure 2(D), when a sheet-like PET substrate coated with platinum was formed using a 200W DC irradiation for 15 seconds, it was found that under the same conditions as with an uncoated substrate, thermal deformation occurred, making it impossible to form a mouthpiece that accurately matched the tooth shape. Therefore, when coating a mouthpiece with a thick layer of platinum, it is preferable to coat the platinum after the mouthpiece has been formed.

[0025] [Example 2] Formation of platinum coating film using AC power (RF) Next, by changing the power supply applied to the discharge gas from DC to AC, we were able to stably deposit a transparent platinum coating. In particular, it was found that by using a high-frequency power supply in the sputtering apparatus to generate plasma with a power of 10W to 100W and depositing a film on the resin substrate for an appropriate irradiation time, a uniform and transparent platinum coating can be stably formed on the resin surface of the resin substrate.

[0026] Figure 3(A) is a photograph of a circular sheet-shaped PET substrate (without heating) placed 70 mm away from a platinum metal plate as the target and argon as the discharge gas, after film deposition by applying 20 W of power from an AC power supply (RF) for 30 seconds. Figure 3(B) is a photograph of a film deposited with 40 W AC and an irradiation time of 15 seconds. Figure 3(C) is a photograph of a film deposited with 60 W AC and an irradiation time of 15 seconds. Figure 3(D) is a photograph of a film deposited with 100 W AC and an irradiation time of 2 seconds.

[0027] Figure 4 shows the surface composition analysis results of the PET substrate coated with a platinum film using scanning electron microscopy / energy-dispersive X-ray spectroscopy (SEM-EDX) on the surface of the PET substrate treated with AC 20W for 30 seconds (Figure 3(A)). The analysis results showed 1.735 mass% oxygen and 98.265 mass% platinum, confirming that a coating of nanoplatinum particles was formed on the surface of the PET substrate by sputtering. Thus, by using a high-frequency power supply, it was possible to create a platinum coating with a thinner film thickness. With AC 20W for 30 seconds (Figure 3(A)) and AC 40W for 15 seconds (Figure 3(B)), a uniform and transparent platinum coating could be stably formed. With 60W (Figure 3(C)) and 100W (Figure 3(D)), a platinum coating film with visible light transmittance could be formed, although it was slightly colored black. Furthermore, under the same conditions as above, a platinum coating film with visible light transparency could be formed even when the AC power output was changed to 20W and the irradiation time to 180 seconds, 240 seconds, and 300 seconds, as well as when the AC power output was changed to 40W, 60W, and 100W and the irradiation time to 30 seconds.

[0028] [Example 3] Transmittance and film thickness of platinum coating film The visible light transmittance of a platinum coating film formed on a sheet-like PET substrate was measured using a spectrophotometer (Hitachi High-Tech Corporation U-3900 spectrophotometer) under the following measurement conditions. Measurement mode: Wavelength scan Measurement wavelength range: Starting wavelength 899.00 nm to ending wavelength 300.00 nm (Data processing / area calculation: Start 780.00nm ~ End 380.00nm) Scan speed: 300nm / min Sampling interval: 0.50 nm The measurements were performed by first measuring an untreated PET substrate to establish a baseline, and then measuring coated PET substrate samples to calculate visible light transmittance. The surface coating film was also evaluated visually. Table 2 shows the transmittance measurement results and visual evaluations, along with the RF power output and irradiation time for each sample. Furthermore, although the film thickness was measured using a spectroscopic ellipsometer, the values ​​for samples 1-8 were below the measurement limit (6 nm) and could not be measured. The film thicknesses of samples 9 and 10 were 11.60 nm and 14.86 nm, respectively, as shown in Table 2. Although it is difficult to measure the film thickness of the visible light-transmitting platinum coating film of the present invention, the trend of the coating film thickness can be estimated from the visible light transmittance value. In other words, the higher the visible light transmittance, the thinner the film thickness, and the lower the visible light transmittance, the thicker the film thickness.

[0029] [Table 2]

[0030] Figure 5(A) is a graph showing the relationship between film deposition time and transmittance at an output of 20W, created from the transmittance measurement results of samples 1, 5-7, and (B) is a graph showing the relationship between RF output and transmittance at an irradiation time of 30 seconds, created from the transmittance measurement results of samples 1, 8-10.

[0031] Table 2 and Figure 5 confirm that the transmittance can be adjusted by adjusting the output and irradiation time of the radio frequency (RF) power supply. Under 20W and 40W conditions, a platinum coating film with a visible light transmittance of 80% or more was formed. When exposed to 20W for 30 seconds, a platinum coating film with a visible light transmittance of 96.6% was formed. While it was possible to form a platinum coating film with a visible light transmittance of 95% or more, extending the irradiation time beyond 30 seconds allowed for the formation of a platinum coating film with a visible light transmittance of 95% or less. For example, at 20W for 180 seconds, the transmittance was 89.4%, and at 240 seconds, it was 86.7%, both below 90%. However, by forming the film under conditions of 20W for 30 to 180 seconds, a platinum coating film with a visible light transmittance of 90-95% can be formed. At 20W for 300 seconds, a platinum coating film with 82.4% transmittance could be formed, allowing for the formation of platinum coating films with a visible light transmittance of 80% or more and 85% or less. Furthermore, under 40W conditions, a visible light transmittance of 88.2% was achieved when the irradiation time was 15 seconds, allowing for the formation of a platinum coating film with a visible light transmittance of 80% to 90%, which is almost equivalent to that achieved with 20W for 180 seconds. However, at 30 seconds, the transmittance was 83.3%, allowing for the formation of a platinum coating film with a visible light transmittance of 80% to 85%, which is almost equivalent to that achieved with 20W for 300 seconds. Under 60W conditions, the visible light transmittance was 71.4% when the irradiation time was 15 seconds, and 63.0% when the irradiation time was 30 seconds. Although slightly dark, it was possible to form a platinum coating film with visible light transmittance of 50% or more. Under 100W conditions, a 2-second irradiation time resulted in a visible light transmittance of 66.9%, forming a platinum coating film that was slightly dark but possessed visible light transmittance of 50% or more. A 30-second irradiation time resulted in a visible light transmittance of 30.4%, forming a very dark black (similar to dark sunglasses) platinum coating film that possessed visible light transmittance of 30% or more. Thus, by adjusting the output and irradiation time of the radio frequency (RF) power supply, a platinum coating film with a desired visible light transmittance can be formed. However, the above output and irradiation time results are for specific film formation conditions, and the specific output and irradiation time will vary depending on the structure of the apparatus, the size of the target, the distance from the target to the sample, etc., so it is necessary to determine the conditions through experiments.

[0032] [Example 4] Antibacterial properties of platinum coating film Furthermore, antimicrobial tests were conducted on Sample 1 (20W 30 seconds) and Sample 8 (40W 30 seconds). The antimicrobial tests were conducted under the following conditions, with reference to JIS 2801. Figure 6 is a diagram illustrating the outline of the test system for the test specimen, showing the cross-sectional structure of the test system. A filter paper 32 soaked in water was placed at the bottom of a φ90 mm sterile polystyrene petri dish 31 for humidification, and a φ60 mm sterile polystyrene petri dish lid 33 was placed on top of it as a base. The test specimen 34 was placed on the lid 33, and 0.1 mL of test bacterial solution 35 was dropped onto the test specimen 34. A 20 mm square covering film 36 was then placed over it, ensuring that the test bacterial solution 35 spread across the entire evaluation area of ​​the test specimen 34. Furthermore, a sterile petri dish lid 37 was placed over a larger petri dish 31 to form the test system, and it was allowed to act for 24 hours under conditions of 35°C ± 1°C and 90% RH or higher. Test sample 34 consisted of three 25mm square PET substrates with a platinum coating (Sample 1), three 25mm square PET substrates with a platinum coating (Sample 8), and three 40mm square unprocessed films (reinforced polyethylene) as a control. Before testing, both sides were irradiated with a pulsed xenon lamp (Comet, BHX-200) for 20 seconds to clean the surface. The test bacteria used was Streptococcus mutans. Frozen strains were inoculated onto tryptone soy agar (TSA) plates and cultured at 36°C ± 1°C for 21 hours. After further inoculation onto the same medium and cultured at 36°C ± 1°C for 18 hours, the developed colonies were transcribed and incubated in a 1 / 500 concentration of ordinary broth medium for approximately 10 minutes. 5 Prepared at a concentration of cells / mL, this was designated as test bacterial suspension 35.

[0033] After 24 hours, test sample 34 (mouthpiece material coated with nanoplatinum particles and unprocessed film) was collected in a sterile bag containing 10 mL of SCDLP broth medium (inactivator), and the test bacteria were washed out of the test sample. The washed-out solution was used as the sample solution for bacterial count measurement, and a dilution series was prepared using phosphate-buffered saline (prepared by diluting 3.4% phosphate buffer 800 times with saline). 1 mL each of the undiluted and diluted sample solutions were transferred to a sterile petri dish, mixed with approximately 20 mL of TSA, solidified, and incubated at 36°C ± 1°C for 44-46 hours. 2 The number of test bacteria per unit area was determined. Table 3 shows the number of test bacteria (cells / cm³) for each test product. 2 (This indicates a lower limit of quantification: 2.5 particles / cm²) 2 ).

[0034] Based on the obtained bacterial counts, the antimicrobial activity values ​​(R) for samples 1 and 8 were calculated using the following formula, with the untreated film as a control. The antimicrobial activity values ​​were rounded down to one decimal place, with the second decimal place truncated. R = (Ut - Uo) - (At - Uo) = Ut - At Here, R: antibacterial activity value, Uo: mean logarithmic value of the number of test bacteria immediately after inoculation of the untreated film, Ut: mean logarithmic value of the number of test bacteria after the reaction time of the untreated film, and At: mean logarithmic value of the number of test bacteria after the reaction time of the mouthpiece material coated with nanoplatinum particles. Table 3 shows R, Uo, Ut, and At.

[0035] [Table 3]

[0036] As shown in Table 3, the antibacterial activity value (R) against Streptococcus mutans after 24 hours of exposure to Sample 8 (visible light transmittance 83.3%), a mouthpiece material coated with nanoplatinum particles, which was deposited using AC 40W for 30 seconds, was 2.6. According to JIS 2801, an antibacterial activity value of 2.0 or higher indicates that an antibacterial processed product has an antibacterial effect, thus confirming that Sample 8 (visible light transmittance 83.3%) has an antibacterial effect. However, the antibacterial activity value (R) against Streptococcus mutans after 24 hours of exposure to Sample 1 (visible light transmittance 96.6%), a mouthpiece material coated with nanoplatinum particles, which was deposited using AC 20W for 30 seconds, was 0.6. Although the number of bacteria was lower than that of the untreated film, it did not show the antibacterial effect according to JIS standards. It should be noted that a platinum coating film with visible light transmittance but lower visible light transmittance (thicker film thickness) than Sample 8 also showed an antibacterial activity value (R) of 3.4. Therefore, in order to obtain an antibacterial effect, the platinum coating film is preferably visible light transmittance of 95% or less, more preferably 90% or less, and even more preferably 85% or less.

[0037] [Example 5] Molding a sheet-like PET substrate into a mouthpiece Using a platinum metal plate as the target and argon as the discharge gas, a circular sheet-shaped PET substrate (without heating) was placed 70 mm away from the target. After applying 40 W of power from an AC power source and irradiating it for 30 seconds to deposit a platinum-coated PET substrate, the resulting platinum-coated PET substrate was heated and pressurized under the same conditions as an uncoated PET substrate to form a mouthpiece, which allowed for accurate shaping to match the tooth mold.

[0038] [Example 6] Formation of a platinum coating film on a mouthpiece An uncoated PET substrate was heated and pressurized to form a mouthpiece. A platinum metal plate was used as the target, and argon was used as the discharge gas. A 40W AC power supply was applied to the mouthpiece (without heating) placed 70mm from the target, and a film was deposited on the inner surface of the mouthpiece for 30 seconds. Film deposition was performed on three mouthpieces, and in all cases, a uniform platinum coating film was formed on the inner surface.

[0039] As described above, we were able to form a platinum coating film on a resin substrate that has visible light transmittance, with a visible light transmittance of 95% or less, 90% or less, or 85% or less, and 30% or more, 50% or more, or 80% or more. This provides antibacterial properties through the platinum coating film and also offers an inconspicuous platinum coating film. Therefore, it is possible to check the surface of the substrate through the platinum coating film, and in the case of a translucent substrate, the translucency of the substrate can be maintained to some extent. Such a platinum coating film can be used for mouthpieces and can also be used for other substrates, such as lenses, eyeglasses and sunglasses, watch glass, mobile phone and smartphone display screens, other machine display screens, televisions, showcases, window glass, etc. Furthermore, by forming a platinum coating film, particularly a platinum coating film with a visible light transmittance of 95% or less, 90% or less, or 85% or less, on the inner surface and / or outer surface of the mouthpiece and the sheet-like resin substrate for molding the mouthpiece of the present invention, it is possible to kill Streptococcus mutans, which causes tooth decay, on the inner surface of the mouthpiece that faces the teeth and in the oral cavity, thereby preventing tooth decay. If it is not necessary to make the mouthpiece transparent and inconspicuous, a platinum coating film that does not transmit visible light may be used. If it is necessary to make the mouthpiece transparent and inconspicuous, it is preferable that the visible light transmittance be 30% or more, 50% or more, or 80% or more. [Explanation of symbols]

[0040] 1. Mouthpiece 11 Inner surface 12 Outer surface

Claims

1. It is a mouthpiece that is worn over the teeth. A mouthpiece characterized by having a platinum coating film formed on the inner surface of the mouthpiece that faces the teeth.

2. It is a mouthpiece that is worn over the teeth. A mouthpiece characterized by having a platinum coating film formed on the outer surface of the mouthpiece.

3. The mouthpiece according to claim 1 or 2, characterized in that the platinum coating film is formed by a sputtering method.

4. The mouthpiece according to claim 1 or 2, characterized in that the platinum coating film has visible light transmittance and a visible light transmittance of 95% or less, 90% or less, or 85% or less.

5. The mouthpiece according to claim 4, characterized in that the platinum coating film has a visible light transmittance of 30% or more, 50% or more, or 80% or more.

6. The mouthpiece according to claim 1 or 2, characterized in that the antibacterial activity value against Streptococcus mutans on the surface of the mouthpiece on which the platinum coating film is formed is 2.0 or higher, 2.5 or higher, or 3.0 or higher.

7. A platinum coating film formed on a resin surface using a sputtering method, The platinum coating film is characterized by having visible light transmittance and a visible light transmittance of 95% or less, 90% or less, or 85% or less.

8. A sheet-like resin substrate for molding a mouthpiece, characterized in that a platinum coating film having visible light transmittance and a visible light transmittance of 95% or less, 90% or less, or 85% or less is formed on at least one of the surface or back surface of the resin substrate.

9. The platinum coating film according to claim 7 or the sheet-like resin substrate according to claim 8, characterized in that the platinum coating film has a visible light transmittance of 30% or more, 50% or more, or 80% or more.

10. The platinum coating film according to claim 7 or the sheet-like resin substrate according to claim 8, characterized in that the antibacterial activity value against Streptococcus mutans on the surface of the platinum coating film is 2.0 or higher, 2.5 or higher, or 3.0 or higher.

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