JP2010202437A - Method for manufacturing antibacterial heat-resistant glass vessel and antibacterial heat-resistant glass vessel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for efficiently manufacturing a heat-resistant glass vessel capable of giving antibacterial performance to vessels of various sizes and shapes, and a heat-resistant glass vessel usable for a microwave oven and hot water sterilization without problems. <P>SOLUTION: The method includes a process for polishing at least the inner surface of a heat-resistant glass vessel, a process for applying a solution containing silver on the polished surface to form a silver film, a process for diffusing silver ions from the glass surface to the inside by heat-treating the vessel on which the silver film is formed at 300-550°C, and a process for washing off silver remained on the surface without diffusing into the inside of glass by using an acid such as nitric acid. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a heat-resistant glass container imparted with antibacterial properties, and particularly relates to a production method suitable for producing an antibacterial heat-resistant glass container excellent in thermal shock resistance and corrosion resistance at low cost and in large quantities. . The “heat-resistant glass container” used in the present specification is one that can be used in a microwave oven or has a heat-resistant temperature difference that can be sterilized with hot water. Specifically, borosilicate glass or aluminosilicate glass is used. It means the glass container used.

  Many techniques relating to articles imparted with antibacterial properties and methods for producing the articles have been disclosed. Known antibacterial agents that exhibit antibacterial properties include natural antibacterial agents such as wasabi, metal antibacterial agents such as copper and silver, and oxide antibacterial agents such as titanium oxide. In food preservation applications, silver is used for antibacterial activity and safety.

  Of the articles imparted with antibacterial properties, there are three known methods for imparting antibacterial performance to glass. The first method is a method represented by Patent Documents 1 and 2, in which silver is mixed with a glass material and melt-molded. The antibacterial performance of this method is manifested by silver eluted in water and other liquids, and easily eluted borate glass and phosphate glass are used. The second method is a method in which a coating layer containing silver is applied to the surface of a glass article. This method can reduce the amount of silver used relative to the first method, and is more economical than the first method. The third method is a method represented by Patent Documents 3 and 4, in which a silver-containing liquid is applied to the surface of a glass article and heat-treated to diffuse silver from the glass article surface into the article. In this method, the problems of the first and second methods are improved. Silver is concentrated and distributed on the surface of the glass article, and antibacterial properties are consumed in a short period of time due to wear compared to the second method. The surface properties of the article will not change significantly.

  As an example of application to a container, for example, Patent Document 5 discloses a method of baking after applying a solution obtained by mixing a surfactant with a solution containing silver nitrate. In Patent Document 6, a substrate containing an antibacterial agent as a metal is obtained by a method in which a liquid containing an antibacterial agent includes thermal decomposition spraying, vacuum sputtering, precipitation by reduction of a corresponding salt of a metal antibacterial agent known as a silver mirror reaction. Discloses a method of forming a film.

  Patent Document 7 is known as an example in which antibacterial performance is imparted to a hard borosilicate glass.

Japanese Patent Laid-Open No. 11-60268 JP-A-11-228171 JP-A-10-15041 JP 2000-53451 A JP-A-11-278866 Special table 2008-524097 gazette Special table 2007-507407 gazette Japanese Patent No. 3453515

  The first method represented by the above Patent Documents 1 and 2 is inferior in durability because an easily-eluting borate glass or phosphate glass is used, so it cannot be used in applications as a glass container. Used to impart antibacterial properties to resin products by kneading into resin. In addition, since silver present on the glass surface is eluted, it plays a role of developing antibacterial properties, so that the silver inside the glass has no effect on the antibacterial properties. As a result, there is a problem that it is necessary to make the glass contain a relatively large amount of silver, which is not economical.

  The second method has a problem that the surface properties of the article are remarkably changed by forming a coating layer. In addition, there is a problem that the antibacterial property is remarkably lowered due to wear by washing.

  The third method represented by Patent Documents 3 and 4 is considered to be most suitable when applied to an antibacterial glass container for storing food, but the container has various sizes and shapes. , Mass production is difficult. Moreover, since what was antibacterial-treated was mainly soda-lime glass, there exists a problem which cannot be used for a microwave oven etc. Further, since soda lime glass is corroded by alkali, the antibacterial property is likely to be deteriorated by washing with an alkaline detergent used in a dishwasher. In Patent Document 8, this problem is solved by performing a strengthening process and compressing the surface. However, since it is necessary to perform the strengthening process, the number of processes is increased and the process is not economical. There is a problem that stress is relieved.

  On the other hand, hard borosilicate glass is generally strong in corrosion resistance and is considered to have good antibacterial durability when antibacterial performance is imparted. As an example in which antibacterial performance is imparted to the hard borosilicate glass as described above, there is one described in Patent Document 6, but the amount of silver existing at 0 to 2 μm from the glass surface is 0.6 to exhibit antibacterial performance. More than mass% is necessary. This is thought to be because unevenness tends to occur in the formation of the silver film.

  In the method disclosed in Patent Document 5, a method of adding a surfactant to a silver nitrate aqueous solution to improve wettability and uniformly coating the silver nitrate aqueous solution is shown. As a result, an article shaped like a container tends to become uneven during drying. Also, forced drying with a blower cannot be used because the solution containing the antibacterial agent is scattered, and drying takes time.

  In the method described in Patent Document 6, forming a silver film on a container by pyrolysis spraying or vacuum sputtering performed at a high temperature increases the equipment cost, and it is difficult to form a uniform film in a deep container. There's a problem. Silver film deposition by silver mirror reaction can be performed at room temperature and the silver film thickness can be changed, so it is economical that only silver necessary for thermal diffusion can be deposited, but the substrate is an alkali metal such as Na. Is a soda-lime glass that contains a large amount of soot, it tends to cause burns, and it becomes hydrophobic easily when stored in the atmosphere, which tends to form water spots. The water spot here is a phenomenon in which minerals contained in tap water and dust in the atmosphere aggregate in water droplets adhere to the glass surface after drying.

  Because of these problems, at present, antibacterial heat resistant resin products in which antibacterial components are kneaded are mainly used for containers having antibacterial performance that can be used in a microwave oven. However, the resin container is easily scratched by washing, and the color and smell are liable to be transferred during food preservation. Therefore, even if antibacterial properties are imparted, there are disadvantages in terms of hygiene. In addition, antibacterial materials that are kneaded into the resin are glass and zeolite that are designed to easily elute the antibacterial agent, so the antibacterial components exposed on the surface of the resin are likely to elute and have problems with antibacterial durability. .

  Furthermore, the resin product is hydrophobic and water spots are likely to remain during drying. When a water spot is generated, dirt tends to aggregate during drying, which is not preferable for hygiene purposes.

  When pursuing the cleanliness of glass containers such as food storage containers, antibacterial heat resistance with less color and odor transfer, excellent thermal shock resistance, can be used in microwave ovens and hot water disinfection without problems, and water spots do not remain A glass container is desired. The present invention was made in order to improve the above-mentioned limitations and disadvantages in the prior art, and can be used without problems with microwave ovens and hot water disinfection, and has heat resistance that imparts antibacterial performance to containers of various sizes and shapes. A method for efficiently producing a glass container and a heat-resistant glass container are provided.

  In order to achieve the above object, the present invention includes a step of cleaning at least the inner surface of the heat-resistant glass container, a step of applying a solution containing silver to the cleaned surface to form a silver film, A step of diffusing silver ions from the glass surface to the inside by heat-treating the container in which the silver film is formed at 300 ° C. to 550 ° C., and a step of washing and removing silver remaining on the surface without diffusing into the glass. It is characterized by having.

  Further, the cleaning process is a cleaning process using an abrasive, and the cleaning is performed so that the surface contact angle after the glass cleaning process measured by the method defined in JIS R 3257 is 30 ° or less. It is characterized by.

  The abrasive is at least one selected from cerium oxide, colloidal silica, lanthanum oxide, iron oxide, manganese oxide, and zirconia oxide, and the abrasive has a finer particle size than # 800 described in JIS R 6001 It is characterized by using.

  The step of forming the silver film uses precipitation of metallic silver by reduction of a solution containing silver.

The step of washing and removing silver remaining on the surface uses a solution containing any of HNO ₃ , FeCl ₃ , Fe (NO ₃ ) ₃ , HCl, H ₂ SO ₄ , and H ₂ O _2. To do.

The heat-resistant glass container is made of borosilicate glass having a coefficient of thermal expansion of 30 to 55 × 10 ⁻⁷ / ° C. in the range of 0 to 300 ° C.

The present invention also provides a silver ion having a depth of 0.5 μm or more on at least the inner surface of a heat-resistant glass container made of borosilicate glass having a thermal expansion coefficient in the range of 0 to 300 ° C. of 30 to 55 × 10 ⁻⁷ / ° C. The surface having a diffusion layer, at least the surface having a silver ion diffusion layer is a cleaned surface, and the surface contact angle of the surface measured by the method defined in JIS R 3257 is 30 ° or less. This is an antibacterial heat-resistant glass container.

  The cleaned surface is a surface cleaned or polished using an abrasive.

  The silver concentration at a depth of 0.5 μm from the surface having the silver ion diffusion layer is 0.1% by mass or more and less than 2% by mass.

  According to the present invention, it is possible to stably form a uniform silver film by cleaning the glass surface before the silver film forming step, and as a result, there is little color and smell transfer, and the microwave oven It is possible to provide an antibacterial heat-resistant glass container that can be used in hot water and sterilized with hot water without problems and has a short drying time after washing in daily use. In addition, the heat-resistant glass container according to the present invention has an effect that the initial antibacterial performance can be stably maintained by daily cleaning because it is quick to dry and hardly adheres to dirt.

It is the figure which showed the time-dependent change of the contact angle of the water of the Example and comparative example glass of this invention. It is a figure which shows the diffusion state of the silver in the Example of this invention measured using D-SIMS (Dynamic Secondary Ion Mass Spectrometry = secondary ion mass spectrometer). It is a figure which shows the spreading | diffusion state of silver by the difference in the heat processing conditions in the Example glass of this invention measured using D-SIMS.

Below, the manufacturing method of the antibacterial heat-resistant glass container in this invention is demonstrated in detail. The manufacturing process is specifically described as follows.
(1) The process of forming a clean surface of glass by cleaning the surface of the heat-resistant glass container that diffuses silver (cleaning process)
(2) A step of contacting the surface of (1) with an activation treatment solution of stannous chloride or palladium chloride (activation treatment step)
(3) A step of forming a metallic silver film by electroless plating by allowing a reducing solution to act on a silver salt solution containing silver (hereinafter sometimes referred to as a silver solution) (silver film forming step)
(4) Step of diffusing silver into glass by heating (heat treatment step)
(5) Step of removing excess residual silver (residual silver removal step)
(6) A step of washing and drying (washing and drying step).

  Next, each process of the manufacturing method of the antibacterial heat resistant glass container in this invention is demonstrated.

  First, the present invention has a process (cleaning process) of cleaning at least the inner surface of the heat-resistant glass container, that is, the surface for diffusing silver ions, before the process of forming the silver film. The process of cleaning the heat-resistant glass container is a process necessary for imparting hydrophilicity to the glass to make it difficult for water spots to remain and for uniformly forming a silver film in the silver film forming process. Since the surface in contact with the contents is subjected to antibacterial treatment, at least the inner surface needs to be cleaned. Note that the outer surface may be subjected to a cleaning treatment for the purpose of imparting hydrophilicity. Further, by cleaning the surface to be antibacterial treated, the effect of stably maintaining the initial antibacterial performance can be imparted because the drying is quick and the dirt is difficult to adhere.

  The cleaning treatment referred to here is typically a treatment for cleaning the glass surface using an abrasive. Washing is performed so that the surface contact angle after the glass cleaning treatment is 0 ° or more and 30 ° or less, preferably 20 ° or less, and most preferably 10 ° or less as measured by the method defined in JIS R 3257. For example, the polishing agent is selected from cerium oxide, colloidal silica, lanthanum oxide, iron oxide, manganese oxide, and zirconia oxide, and it is preferable to use an abrasive finer than # 800 described in JIS R 6001. Also, sponges and brushes containing these abrasives can be used.

  The abrasive that can be used is not limited to those listed above, and any abrasive that can be generally used for polishing glass can be used. Among them, at least one selected from the above-described cerium oxide, colloidal silica, lanthanum oxide, iron oxide, manganese oxide, and zirconia oxide is used as a desired cleaning effect without giving unnecessary damage to the glass. It is preferable to use it.

  When the grain size of the abrasive is coarser than # 800 described in JIS R 6001, visible scratches are formed on the glass, which is not preferable in appearance, and causes of unevenness in the subsequent silver film forming process Further, the hydrophilicity of the glass surface, which is a feature of the present invention, is impaired. If the abrasive is finer than that, the glass surface is cleaned even with light polishing, and visible scratches are less likely to occur. An abrasive having a finer particle size than # 800 can be used, but a smaller particle size is desirable in order to reduce visible scratches. It is preferably # 1500 or more, more preferably # 3000 or more. Even at # 10000, the cleaning effect can be confirmed.

  Even if the concentration of the abrasive is 0.1% by mass with respect to the solvent (usually pure water), the contact angle of water is 20 ° by washing with a sponge for about 60 seconds per inner surface of a 1 L cold water cylinder. It has been confirmed that Preferably, it is 0.1 mass% or more and 10 mass% or less. Even if an excess of abrasive is used in excess of 10% by mass, the effect is not changed. On the contrary, the cleaning efficiency including the subsequent water washing is lowered and the burden of waste liquid treatment is increased.

As time passes after glass is produced, its surface properties change greatly due to the adsorption of organic substances from the atmosphere. In particular, in soda lime glass containing a large amount of alkali metal such as Na, Na ⁺ and Ca ²⁺ ions migrated from the inside of the glass react with carbon dioxide in the air to form Na ₂ CO ₃ and CaCO ₃ salts. Glass having such a deteriorated layer generally exhibits hydrophobicity. When the silver mirror reaction is carried out with the surface altered, there is a portion where the activation treatment liquid and the silver liquid are not partially wetted, so that unevenness and missing are generated when the silver film is formed.

  Polishing the altered glass surface results in a clean glass surface that is invisible to the naked eye or even with a scanning electron microscope where appropriate, even if it is a very light polish of a few seconds. This can be confirmed when the water contact angle shows hydrophilicity of 30 ° or less. However, simply exposing the surface of the glass to be treated to a solution containing an abrasive or pouring a polishing liquid will result in an uncertain cleaning effect. Therefore, use a sponge, cloth, soft, dense brush, etc. It is preferable to apply a specific force, and it is particularly preferable to select means for contacting the surface.

  Cleaning is performed so that the surface contact angle measured by the method of JIS R 3257 is 30 ° or less. The reason why the surface contact angle is 30 ° or less is that wettability is good and it is difficult to form polka dots. Preferably, the water film is thinly stretched at 20 ° or less. The reason why the lower limit of the contact angle is not particularly limited is that, depending on the cleaning described above, the glass becomes very hydrophilic glass, and the contact angle of water is 5 ° or less, so that measurement with an instrument is impossible. is there. When the surface contact angle is 30 ° or less, a silver film can be formed substantially without unevenness or omission, and when the surface contact angle is 20 ° or less, the water film extends thinly. If it is 10 ° or less, it is called super hydrophilicity, and even with a small amount of liquid, it can be uniformly extended on the substrate and a uniform silver film can be formed efficiently.

  Next, an activation treatment liquid containing stannous chloride or palladium chloride is brought into contact with the cleaned surface to carry stannous ions or palladium ions as a catalyst (activation treatment step). Thereby, silver by silver mirror reaction can be stably deposited on the glass surface.

  Thereafter, a silver-containing solution is applied to the activated surface to form a silver film. Silver is known to have high antibacterial performance, but high safety is also important in food preservation applications. In the present invention, silver that is superior in terms of safety was selected.

  The step of forming a silver film (silver film forming step) is preferably a method utilizing precipitation of metallic silver by reduction of a silver solution. This method is a so-called silver mirror reaction, which is also used for manufacturing mirrors. Heat resistant glass containers such as food storage containers have various shapes. For example, it is difficult to uniformly apply a silver film to containers having different shapes by sputtering. In the silver mirror reaction, there is an advantage that a silver film can be uniformly formed on the inner surface even if it has a complicated shape by putting the reaction liquid in the container and swinging or rotating the container. It is possible to apply a silver-containing solution without using the silver mirror reaction, but in order to achieve stable antibacterial performance, the coating solution needs to have a relatively high silver concentration and uses a small amount of silver. There is an advantage in a method using a silver mirror reaction that can form a reliable silver film in an amount.

  Silver mirror plating deposits silver on the glass surface by reacting a reducing solution such as formalin, glucose, glyoxal, hydrazine with a solution obtained by adding ammonia water to a silver solution (hereinafter sometimes referred to as a silver preparation solution) This is done by depositing. As the silver salt, silver nitrate is usually used, but the silver mirror reaction also occurs in silver salts such as silver sulfide and silver chloride, and can be used.

  First, the silver preparation liquid is applied to the glass surface by a method such as dipping or spraying, and then the reducing liquid such as acetaldehyde is allowed to act on the glass surface, whereby silver can be precipitated and adhered to the glass surface. A dense metallic silver film can be formed by spraying or applying the silver preparation liquid and the reducing liquid after mixing. This step can be performed at room temperature. In addition, when the mixed solution is sprayed or applied, the above activation treatment is performed, so that the precipitated silver is chemically attached to the glass surface as a form with reflection. Or rotate it. In addition, it is preferable to discharge the liquid mixture of the surplus silver preparation liquid and the reducing liquid out of the container.

  Silver film formation by silver mirror reaction does not peel easily by chemically depositing metallic silver on the glass surface.After forming the silver film, the container can be inverted, rotated, or dried by blower or heating. There is a merit that can be done. Thereby, silver film formation, drying, and baking can be performed continuously, and it is suitable for mass production. In particular, when evaporating moisture by heating, if borosilicate glass is excellent in thermal shock resistance, there is little risk of cracking by heat shock, and it can also be put into a continuously heated electric furnace from silver film attachment. .

  The surface on which the silver film is formed may be rinsed off with excess water, thereby preventing the occurrence of unevenness due to the remaining liquid and preventing unwanted foreign matters from being burned onto the glass surface during the next heat treatment. Can be prevented.

When the silver film to be formed is made thick so as to reflect completely without transmitting visible light like a mirror, metallic silver remains on the glass surface after firing. Since silver diffuses as ions, that is, it becomes silver oxide and diffuses into the glass, the portion where the metallic silver remains may not be sufficiently diffused due to insufficient oxygen supply at the glass interface where silver diffusion occurs. is expected. For this reason, as for the density | concentration of a silver preparation liquid, the density | concentration of the silver preparation liquid which is a high density | concentration so that it may be used when forming a mirror, for example, 5 g / L or more is unnecessary, and about 1 g / L may be sufficient. When silver of 0.2 mg / cm ² or more is adhered to the glass surface, visible light is not transmitted and is completely reflected. When fired as it is, metallic silver remains on the glass surface even after firing. At 0.1 mg / cm ² or less, visible light is not completely reflected, and a transmittance of 10% or more is secured near the wavelength of 330 nm, and the surface after firing is not mirror-like reflected and remains. The removed silver oxide is easily removed. Moreover, in order to ensure the amount of silver which diffuses at the time of baking, it is preferable to form a silver film of 0.01 mg / cm ² or more. The silver film thickness can be adjusted by the concentration, temperature, amount, mixing ratio, and reaction time of the silver preparation solution and reducing solution, and the amount of deposited silver depends on the mass increase, transmittance, reflectance, and chromaticity after the formation of the silver film. It can be calculated.

  Next, the silver ion is diffused from the glass surface to the inside by heat-treating the container in which the silver film is formed at 300 ° C. to 550 ° C. (heat treatment step). When the heat treatment is less than 300 ° C., the diffusion of silver becomes insufficient, and sufficient antibacterial performance cannot be obtained stably. Even below 300 ° C., silver diffuses, but the diffusion rate is slow, so the processing time is too long to obtain the desired antimicrobial properties. Above 300 ° C., silver diffuses to the extent that it is sufficiently durable. For shortening the diffusion time, firing at 350 ° C. or higher is preferable. Above the glass transition point, silver colloid is formed and colored, which is not preferable in applications where it is desired to confirm the color of the contents. Further, when firing at a glass transition point or higher, the glass remains strained unless recooled slowly, which is not preferable in terms of the process. If it is 550 degrees C or less, it will be lower than the glass transition point of hard borosilicate glass, and there will be no trouble of re-annealing.

  Since the amount of Ag diffused by temperature is dominantly determined for the heat treatment time, heat treatment of 2 hours or more is not necessary for borosilicate glass, for example, it is sufficient if it is 30 minutes or more at 300 ° C. and 10 minutes or more at 550 ° C. In consideration of production efficiency, it is preferable to set it within 1 hour at the longest. When compared under the same conditions, borosilicate glass has an advantage that the heat treatment time can be shortened because borosilicate glass has a higher diffusion rate of silver ions into the glass than soda lime glass.

  It has been found that silver ions diffuse into the glass by the above heat treatment, and in particular, silver existing in the vicinity of the surface greatly contributes to the antibacterial performance. When considering the use of a food storage container at home, it is necessary to consider surface wear due to cleaning, and the diffusion depth of silver ions is preferably 0.5 μm or more. If it is 0.5 μm or more, the possibility that the antibacterial performance is lost after long-term use at home can be extremely reduced.

After heat treatment is performed to diffuse silver ions, excess silver remains on the glass surface, so that residual silver is removed (residual silver removal step). For removing the residual silver, a solution containing any of HNO ₃ , FeCl ₃ , Fe (NO ₃ ) ₃ , HCl, H ₂ SO ₄ , and H ₂ O ₂ can be used. If the silver compound remains on the surface, the glass surface does not exhibit hydrophilicity, so that the residual silver must be completely removed by washing with the above solution. When a thin silver film is formed under the above conditions and the silver on the glass surface is present as silver oxide instead of metallic silver after firing, residual silver can be removed by lightly rubbing with a sponge, but the shape of the storage container is complicated Then, it may be difficult to remove residual silver partially. In particular, when it remains as metallic silver, it is baked onto the glass and is difficult to remove with a sponge. A solution containing HNO ₃ , FeCl ₃ , Fe (NO ₃ ) ₃ is suitable for such a cleaning step, and may be any concentration that substantially dissolves metallic silver (for example, 1 mol / L HNO ₃ ). . Since the hard borosilicate glass is excellent in corrosion resistance, even if it is washed with a concentrated acid, it does not affect the Ag diffused in the glass, and only the residual silver on the surface can be effectively removed. In the case of using concentrated nitric acid, it can be easily removed only by contact.

  Further, it is then washed with pure water and dried to obtain an antibacterial heat-resistant glass container (washing and drying step).

The heat-resistant glass container in the present invention uses borosilicate glass having a thermal expansion coefficient of 30 to 55 × 10 ⁻⁷ / ° C. in the range of 0 to 300 ° C. Containers that require antibacterial performance are generally used for food preservation, and hard borosilicates with excellent thermal shock resistance, such as PYREX (registered trademark) that can be used in microwave ovens. Acid glass is desirable. However, glass having a thermal expansion coefficient of less than 30 × 10 ⁻⁷ / ° C. has poor meltability, so that it is difficult to obtain a homogeneous glass and it is difficult to form a complicated shape. On the other hand, when the thermal expansion coefficient exceeds 55 × 10 ⁻⁷ / ° C., the thermal shock resistance is inferior, it is easily broken when hot water is poured, and it is not suitable for use in a microwave oven.

Through the above steps, a depth of 0.5 μm or more is formed on at least the inner surface of the heat-resistant glass container made of borosilicate glass having a thermal expansion coefficient of 30 to 55 × 10 ⁻⁷ / ° C. in the range of 0 to 300 ° C. The surface having at least a silver ion diffusion layer is a cleaned surface, and the contact angle of water on the surface measured by the method defined in JIS R 3257 is 30 ° or less. An antibacterial heat resistant glass container is obtained.

  In the heat-resistant glass container of the present invention, the silver concentration at a depth of 0.5 μm from the surface of the silver ion diffusion layer is from 0.1% by mass to 2% by mass. If it is 0.1% by mass or more, antibacterial properties are exhibited, but it is preferably 0.2% by mass or more. When silver exceeding 2% by mass is diffused, coloration due to silver colloid occurs, which is not preferable. More preferably, it is 1.5 mass% or less, More preferably, it is 1 mass% or less, Most preferably, it is 0.6 mass% or less. The reason why the measurement point is set to 0.5 μm from the surface is that there are many measurement errors near the surface pole, and the amount of diffused silver can be measured at 0.5 μm.

  By performing the above steps, that is, a silver film is formed on the cleaned glass surface, silver ions are heated and diffused inside the glass, and a clean glass surface from which excess silver compounds are removed is achieved. The antibacterial heat-resistant glass container can be obtained that has good wettability, that is, the water is thinly stretched by washing at home, so that the water dries substantially faster than before the antibacterial treatment.

  Hereinafter, the present invention will be described in detail by way of examples. An antibacterial heat-resistant glass container was produced by the method described in the above embodiment. In the heat-resistant glass containers of the examples, each of the heat-resistant glass containers having the composition shown in Table 1 is impregnated in a sponge with a solution in which the abrasive shown in the table is dispersed in pure water. The inner surface was evenly rubbed and cleaned (for example, about 30 to 60 seconds per 1 L capacity cold water bottle). At this time, it is not necessary to apply a strong force, and the glass surface can be made a pure and clean surface with a force that is the same as or less than that of daily washing. When cleaning was completed, the polishing liquid in the container was discharged and rinsed with pure water so that no abrasive remained in the container.

  Next, a stannous chloride aqueous solution (for example, 1 g of stannous chloride dissolved in 1000 ml of distilled water) is sprayed or applied to the inner surface of the heat-resistant glass container as an activation treatment agent, and immediately discharged. And washed with pure water. Subsequently, a solution prepared by adding glucose as a reducing agent to a silver preparation solution prepared by adding ammonia water and potassium hydroxide to a solution obtained by dissolving silver nitrate in pure water (for example, about 20 ml per 1 L capacity cold water bottle). Pour into a heat-resistant glass container, rotate the container 3 times with the container tilted so that the side wall of the container is in contact with the solution poured over its entire height, apply the silver preparation on the inner surface of the heat-resistant glass container, and precipitate the silver Thus, a silver mirror was formed on the surface of the container. The reason why potassium hydroxide is added here is to adjust the acidic silver nitrate solution to the alkaline side and promote the oxidation of the reducing solution. As long as it becomes an alkaline solution, it is not limited to potassium hydroxide. The addition of ammonia water alone has the same effect, but potassium hydroxide is used in combination to alleviate the ammonia odor in the process.

  Next, the mixed liquid of the silver preparation liquid and the reducing liquid was discharged, rinsed with pure water, dried, heated to 350 ° C. in an electric furnace, and heat-treated for 60 minutes.

  Silver remaining on the inner surface of the heat-resistant glass container is completely removed by pouring a small amount of nitric acid (for example, 2 mol / L) over the entire inner surface of the container and then rubbing evenly with a sponge, washing with pure water, and drying. Thus, an antibacterial heat resistant glass container was obtained.

  Moreover, in order to make the test and evaluation mentioned later easy, the sample which processed each glass shown in Table 1 into the glass plate of 50x50 mm thickness 3mm was produced. The polishing time shown in Table 1 indicates the processing time for this glass plate sample.

  Then, after thoroughly rinsing with pure water and drying, the contact angle of water was measured for each glass plate by the method defined in JIS R 3257. As a result, it was confirmed that the glass plates subjected to the cleaning treatment all had a hydrophilic surface with a contact angle of 20 ° or less. Subsequently, each glass plate was subjected to an antibacterial treatment by performing the same steps as in the production of the container. Then, the result of having measured the contact angle of water by the method of JIS R 3257 again is shown in Table 1.

  Table 1 shows the results of evaluation of antibacterial properties, heat resistance, and water spots after washing with respect to the glass plates and comparative examples prepared as described above. In Table 1, Sample No. No. 1-7 is an example of borosilicate glass. 8-10 is a comparative example. No. No. 8 is a borosilicate glass treated in the same manner as in Example except that no cleaning treatment was performed before the silver film was formed. No. 9 is the same as that of the example in which the substrate is soda lime glass, No. 9; 10 is a commercially available antibacterial resin. In addition, the glass composition in a table | surface is shown by the mass%.

  Explaining the items shown in the table, the thermal expansion coefficient (shown as α in the table) is a value obtained by measuring the average linear expansion coefficient at 0 to 300 ° C. by the JIS method. The glass transition point (shown as Tg in the table) was measured with a thermomechanical analyzer (TMA) using a sample obtained by processing glass into a cylinder having a diameter of 4 mm and a length of 20 mm.

  Antibacterial properties were analyzed according to JIS Z 2801. The antibacterial activity indicates the number of sterilizations in log relative to the number of bacteria identified in the unprocessed polyethylene film after 24 hours under standard conditions, and the log1 level is the level of bacteria inoculated on the glass surface. 90% indicates killed within 24 hours under standard conditions, log2 indicates that 99% of the bacteria have been killed, and log3 indicates that 99.9% of the bacteria have been killed. Log 2 or higher is considered to have an antibacterial effect. In Table 1, when the antibacterial activity is log 2 or more, “◯” is indicated, and when the antibacterial activity is less than “log”, “×” is indicated. Needless to say, the antibacterial processed samples were inoculated with bacteria on the antibacterial processed side. The test was carried out on Escherichia coli and Staphylococcus aureus in each sample, but since there was no difference in the results depending on the bacterial species when the number of sterilizations was expressed in log, in Table 1 it was simply displayed as one line as antibacterial.

  In the heat resistance test, a glass with a thickness of 1 mm is held in a 120 ° C. incubator for 30 minutes, taken out when the glass portion is kept at a uniform temperature, and immediately immersed in cold water for 1 minute to check for cracks. investigated. The case where cracks could not be confirmed was indicated as “◯”, and the case where cracks occurred was indicated as “X”.

  The diffusion depth of silver was measured using D-SIMS (secondary ion mass spectrometer), and the depth at which the Ag concentration became 0.1% by mass was defined as the diffusion depth. When the Ag concentration in the glass is less than 0.1% by mass, the antibacterial effect is not substantially confirmed. Therefore, 0.1% by mass or more is defined as the silver diffusion depth. In FIG. 1 (350 ° C.), Example No. 2 (500 ° C.), Example No. 3 (550 ° C.) profile is shown.

  The Ag concentration on the glass surface showed a value at 0.5 μm from the surface on the silver ion diffusion side quantified by D-SIMS (secondary ion mass spectrometer).

  In the water spot test, a sample piece of a glass plate was placed vertically, pure water was sprayed with a spray, and the surface state immediately after the observation was observed to confirm the presence or absence of water droplets. The case where the water film was instantly thin and water droplets could not be confirmed was marked with “◯”, and the case where water droplets could be confirmed was marked with “X”. The water spot originally refers to a spot-like deposit formed after the water droplet is dried. However, since the water spot is not formed unless the water droplet remains, it is referred to as a water spot test here.

  As shown in Table 1, the antibacterial performance was shown in the 24-hour antibacterial test for both the examples of the present invention and the comparative examples. On the other hand, Example No. In Comparative Examples No. 1 to No. 7 where the water contact angle was 20 ° or less and hydrophilicity was shown, but the surface was not cleaned (polished) before antibacterial treatment. In No. 8, the water contact angle was 42 °, which was hydrophobic. Also in the water spot test, Example No. In Comparative Examples No. 1 to 7, water droplets could not be confirmed. In No. 8, many water droplets adhered to the glass surface.

  In addition, as a result of the heat resistance test, none of the examples of the present invention was changed, whereas Comparative Example No. It was reconfirmed that No. 9 soda lime glass was not suitable for usage and applications that required thermal shock resistance such as hot water disinfection.

  Prior to the above test, the influence of the heat treatment temperature and time on the diffusion state of silver ions in the glass was evaluated. The results are shown in Table 2. Example No. described in Table 1 above. No. 1 glass plate, after passing through the cleaning step, the activation treatment step, and the silver film formation step in the same manner as in the above example, the heat treatment temperature was 350 ° C., 500 ° C., 600 ° C., the heat treatment time was 60 minutes, After 240 minutes, a sample was prepared in which the silver remaining on the surface was completely removed using nitric acid. In addition, since the sample heat-processed at 600 degreeC showed coloring in glass in 60 minutes, the test for 240 minutes was not implemented. The results of measuring the diffusion state of silver using D-SIMS (secondary ion mass spectrometer) for these samples are shown in FIG. In addition, the code | symbol attached | subjected to the curve in FIG. As shown in FIG. 3, if the heat treatment temperature is the same, the diffusion state at the heat treatment time of 60 minutes and 240 minutes is equivalent, and it was confirmed that the silver diffusion state is determined depending on the temperature. Based on this result, the heat treatment time is fixed at 60 minutes in the examples described in Table 1 above.

  Next, in order to evaluate the sustainability of the antibacterial performance, Example No. 1 and Comparative Example No. The antibacterial performance after 10 samples were kept in acetic acid 80 ° C. at pH 2.5 for 30 minutes was evaluated according to JIS Z 2801. The results are shown in Table 3. The indication of antibacterial properties in the table is the same standard as in Table 1 above. Example No. No. 1 maintained good antibacterial properties, but Comparative Example No. 1 which is a commercially available antibacterial resin. 10 did not show antibacterial properties.

Furthermore, Example No. About the sample of 1, antibacterial performance evaluation based on JISZ2801 was performed again after the condition load shown below which assumed the use condition etc. in daily life. The test is an accelerated test using a sample washed with pure water after being dipped in the following solution for the glass plate prepared in the above example for the following period. The results are shown in Table 4. The indication of antibacterial properties in the table is the same standard as in Table 1 above.
(1) 80 ° C. pure water for 10 days (assuming repeated use of hot water in teapots, etc.)
(2) 4% acetic acid, room temperature, 10 days ... (assuming storage of acidic beverages, etc.)
(3) 3% Na ₂ CO ₃ liquid 95 ° C 16 hours ... (assuming repeated washing with an alkaline detergent in a dishwasher)
(4) 7 mol / L nitric acid 30 seconds (assuming residual silver removal by nitric acid in the manufacturing process)

As is clear from Table 4, the samples immersed in pure water at 80 ° C. and 4% acetic acid at room temperature maintained good antibacterial properties even when immersed for 10 days. Since it is a hard borosilicate glass, the silver diffused on the surface is hard to elute and antibacterial properties are maintained. In addition, even when the dishwasher was immersed in a 3% Na ₂ CO ₃ solution at 95 ° C. for 16 hours assuming an accelerated cleaning with an alkaline detergent, good antibacterial performance was obtained. Under these conditions, it was confirmed that the antibacterial property was maintained even though the glass surface was eroded by 1 to 3 μm by alkali.

  Next, in order to confirm the difference between the heat-resistant glass container subjected to the antibacterial treatment according to the present invention and the heat-resistant glass container not subjected to the same antibacterial treatment as commercially available, the above-mentioned Example No. The following tests were conducted using a cold water bottle (unprocessed product) having the same glass composition and the same water composition before being subjected to a series of treatment processes according to the present invention as a comparative example. That is, after rinsing both containers with tap water, the container opening is placed face down on a general draining tray (room temperature 28 ° C., humidity 60%), and the water droplets disappear completely by visual inspection. The time until was measured.

  As a result, Example No. While the antibacterial treated heat-resistant glass container 1 was completely dried in 1 hour, the comparative example container without the antibacterial treatment required 4 hours for water droplets to disappear. Table 5 shows the results of measuring the water contact angle of glass on the inner surface of the bottom of each container in the same manner as in the above example. While the contact angle of water of the comparative example glass was 30 to 40 °, it was 10 to 20 ° in the examples, and it was confirmed that excellent hydrophilicity and quick drying were exhibited. The heat-resistant glass container according to the present invention has a uniform water film on the inner surface due to its hydrophilicity at the stage of draining the water in the container after washing, and then loses gravity to flow in several lines. It flows down all at once and almost no water drops remain. On the other hand, in the unprocessed product, when the cleaning water is discharged, the water on the inner surface of the container does not form a film but remains as a large number of water droplets. In the test results, it is considered that this difference appears as a difference in drying time.

  In addition, when washing and drying with tap water are repeated several times, stains are observed on the surface of the unprocessed product after drying, which seems to have aggregated minerals contained in tap water. On the surface, since no water droplets remained as described above, almost no blot-like traces were confirmed.

  By performing a cleaning process on the inner surface of the cold water cylinder of the comparative example using cerium oxide in the same manner as the above example, the treated surface becomes hydrophilic. After 1 hour, it was confirmed to dry. However, assuming the use in daily life, when the same test was performed after leaving the dried product in the cupboard for 15 days, the container of the example was also dried in 1 hour, but was washed with cerium oxide. The cold water bottle that was just taken took 3 hours to dry.

  For this reason, the time-dependent change of the contact angle of water at the time of storing in an air atmosphere using the glass plate sample created for various test evaluation in the said Example was measured. The prepared sample is the above-mentioned Example No. No. 1 glass plate, untreated glass substrate, and Example No. Similar to 1, there are three types of glass plates polished with cerium oxide and not diffusing silver ions. FIG. 1 shows changes in the contact angle of water over time when these samples are stored in an air atmosphere (normal room). The untreated one (curve 1) has a contact angle of about 40 °, and there is almost no change over time, but the one with cerium oxide polished (curve 2) has a contact angle of less than 10 ° immediately after polishing. However, after 2 weeks, it becomes about 40 °, and the contact angle of water is almost constant thereafter. This indicates that the property of the glass surface changes from hydrophilic to hydrophobic during storage. On the other hand, Example No. Sample 1 (curve 3) showed a contact angle of about 20 ° even after 30 days and maintained a state of excellent hydrophilicity.

  From the above results, it can be seen that the antibacterial heat-resistant glass container according to the present invention is also effective in maintaining hydrophilicity and quick drying.

  In the above embodiment, the example in which the series of antibacterial treatment steps according to the present invention is applied only to the inner surface of the heat-resistant glass container has been described, but the same treatment step can be applied to the outer surface of the container. In that case, the silver film forming step can be performed by pouring the silver preparation liquid, application with a brush, spraying, or dipping into the silver preparation liquid, and the other processes are the same as the inner surface processing of the heat-resistant glass container. Is applicable.

  Above, for the heat-resistant glass container subjected to the antibacterial treatment according to the present invention and the heat-resistant glass container not subjected to the same antibacterial treatment as those generally marketed, the drying time after washing with water was compared. The drying time was compared between the cold water tube in which the antibacterial treatment according to the present invention was applied only to the inner surface of the heat resistant glass container and the cold water tube in which the antibacterial treatment according to the present invention was applied to both the inside and outside of the heat resistant glass container. The comparative control was the above Example No. 1) Use a cold water bottle with the same treatment as the inner surface on the outer surface, rinse both containers with tap water in the same way as in the above test, and then place the container opening on a general draining tray. The sample was placed in the room facing down, and the time until the water droplets completely disappeared was visually measured.

  As a result, all the cold water bottles were completely dried in 1 hour. When combined with the results of comparison with the above-mentioned raw products, this is because water on the outer surface of the container tends to volatilize regardless of the difference in surface hydrophilicity and hydrophobicity, whereas moisture on the inner surface of the container volatilizes. This is probably because the water drainage on the inner surface of the container resulting from the processing according to the present invention contributes to shortening the drying time.

  Moreover, although the above example mainly explains the method of utilizing precipitation of metal silver (so-called silver mirror reaction) by reduction of a solution containing a silver salt to form a silver film, a solution containing silver, For example, a method of applying a 3 to 20% by mass aqueous solution of silver nitrate to the glass surface can be substituted. If the concentration of the silver nitrate aqueous solution is less than 3% by mass, the antibacterial performance does not appear stably, and if it exceeds 20% by mass, the residual silver after the heat treatment increases, the load of the washing and removal process is large, and the raw material is wasted. Many. Preferably it is 5-15 mass%. In this case, the activation process is not necessary.

  The coating method at this time can use the same method as the silver preparation liquid. However, unlike adhesion by silver mirror reaction, it is difficult to uniformly fix silver on the glass surface simply by applying a solution containing silver. Therefore, when applying, the heat-resistant glass container is 100 to 230 ° C., preferably 150 to 200. It is preferable to improve the binding property of the silver salt to the glass surface by heating to 0 ° C., and the method of applying the solution containing silver to the heated container is preferably a spray method for handling. In the present invention, since a heat-resistant glass container is used, even if the container is heated in advance, it will not be broken by application of the solution, but when the heating temperature is high, particularly when applying the solution by a method other than spraying The solution containing silver is preferably heated so as not to exceed the thermal shock temperature of the glass.

  Thus, even in the silver film formation process that does not use the silver mirror reaction, the glass surface is hydrophilic by the previous cleaning process, so that the solution can be applied uniformly without being repelled, and there is no unevenness. Antibacterial performance is developed. The same effects as those of the above example can be obtained also in the results of antibacterial performance, hydrophilicity / quick drying, and water spot test.

  The manufacturing method of the antibacterial heat resistant glass container of the present invention can be easily applied to a curved surface shape in all steps, and the antibacterial heat resistant glass container of the present invention has excellent antibacterial performance and quick drying performance. It can be used for heat-resistant glass containers with a wide range of shapes and applications, such as glass cold water bottles, food storage containers, coffee makers, teapots, cucumbers, seasoning containers, and tableware.

1 ... Time-dependent change curve of water contact angle of untreated glass,
2. Time-dependent change curve of water contact angle of glass only washed with cerium oxide,
3 Example No. Change curve of water contact angle of glass of 1

Claims (9)

  A step of cleaning at least the inner surface of the heat-resistant glass container, a step of applying a silver-containing solution to the cleaned surface to form a silver film, and a container formed with the silver film at 300 ° C. to 550 ° C. An antibacterial heat-resistant glass container comprising: a step of diffusing silver ions from the glass surface to the inside by heat treatment at ° C; and a step of washing and removing silver not diffused into the glass but remaining on the surface Manufacturing method.   The cleaning process is a cleaning process using an abrasive, and the cleaning is performed so that the surface contact angle after the glass cleaning process measured by the method defined in JIS R 3257 is 30 ° or less. The method for producing an antibacterial heat-resistant glass container according to claim 1.   The abrasive is at least one selected from cerium oxide, colloidal silica, lanthanum oxide, iron oxide, manganese oxide, and zirconia oxide, and the particle size of the abrasive is finer than # 800 described in JIS R 6001. The method for producing an antibacterial heat-resistant glass container according to claim 2.   The method for producing an antibacterial heat-resistant glass container according to any one of claims 1 to 3, wherein the step of forming the silver film utilizes precipitation of metallic silver by reduction of a solution containing a silver salt. The step of washing and removing silver remaining on the surface uses a solution containing any of HNO ₃ , FeCl ₃ , Fe (NO ₃ ) ₃ , HCl, H ₂ SO ₄ , and H ₂ O _2. The manufacturing method of the antibacterial heat-resistant glass container in any one of Claim 1 thru | or 4. The antibacterial according to any one of claims 1 to 5, wherein the heat-resistant glass container is made of borosilicate glass having a thermal expansion coefficient of 30 to 55 x ^10-7 / ° C in a range of 0 to 300 ° C. Of manufacturing heat resistant glass container. It has a silver ion diffusion layer having a depth of 0.5 μm or more on at least the inner surface of a heat-resistant glass container made of borosilicate glass having a thermal expansion coefficient of 30 to 55 × 10 ⁻⁷ / ° C. in the range of 0 to 300 ° C. Antibacterial properties characterized in that at least the surface having a silver ion diffusion layer is a cleaned surface, and the surface contact angle of the surface measured by the method defined in JIS R 3257 is 30 ° or less Heat resistant glass container.   8. The antibacterial heat-resistant glass container according to claim 7, wherein the cleaned surface is a surface cleaned or polished using an abrasive.   The antibacterial heat-resistant glass container according to claim 7 or 8, wherein the silver concentration at a depth of 0.5 µm from the surface having the silver ion diffusion layer is 0.1 mass% or more and less than 2 mass%.

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