JP7645675B2 - Slightly water-soluble glass, slightly water-soluble glass product, composition, and method for improving water quality - Google Patents

Description

The present invention relates to slightly water-soluble glass, slightly water-soluble glass products, compositions, and methods for improving water quality.

In order to reduce the occurrence of mosquitoes that transmit infectious diseases such as dengue fever and Zika fever, it is desirable to suppress the occurrence and growth of mosquito larvae, which are the larvae of mosquitoes. Since mosquito larvae occur and grow in water that has been left unattended, various products made of copper or copper alloys that can dissolve copper (Cu) ions or zinc (Zn) ions into water to suppress the occurrence and growth of mosquito larvae have been proposed (Patent Documents 1 and 2).

It is also known that Cu ions and Zn ions are effective in inhibiting the growth of moss, algae, and the like, and antibacterial agents have been proposed in which an oxide or hydroxide capable of eluting Cu ions or Zn ions is supported on a porous substance such as porous glass (Patent Documents 3 and 4).
Furthermore, it is known that Cu ions and Zn ions are effective in imparting antibacterial and antiviral properties to glass, and glass products containing CuO and ZnO have been proposed (Patent Documents 5 and 6).

JP 2016-216376 A JP 2017-218406 A JP 2003-81725 A JP 2003-146818 A Special table 2017-508705 publication JP 2019-99514 A

The various products described in Patent Documents 1 and 2 are made of solid copper or copper alloys, and therefore are not suitable for long-term use, for example, by being spread over outdoor puddles, and their uses are limited.
Furthermore, the antibacterial agents described in Patent Documents 3 and 4 are not sufficient in terms of their initial (immediately after use) antibacterial effect or their antibacterial effect over time (hereinafter referred to as "sustainability of antibacterial effect"). In particular, these antibacterial agents are not capable of eluting Cu ions or Zn ions for a long period of time.
Furthermore, the glass products described in Patent Documents 5 and 6 do not dissolve entirely, so the effect is not sufficiently durable. Also, since the glass products are difficult to dissolve, they are not suitable for use, for example, by scattering them on outdoor puddles, and their uses are limited.

The present invention has been made to solve the above problems, and has an object to provide a slightly water-soluble glass capable of eluting Cu ions and Zn ions over a long period of time, a slightly water-soluble glass product, and a method for improving water quality.
Another object of the present invention is to provide a composition capable of producing a slightly water-soluble glass product having the above characteristics.

As a result of intensive research conducted by the inventors to solve the above problems, they discovered a glass composition that allows Cu ions and Zn ions to be gradually eluted as the glass melts, and thus completed the present invention.

That is, the present invention provides a slightly water-soluble glass for use as a growth inhibitor or repellent for pests, moss, and algae, an antibacterial agent, or an antiviral agent, which contains 40.0 to 75.0 mol % of _SiO2 , 5.0 to 38.0 mol % of _K2O , 0.1 to 33.0 mol % of at least one selected from CuO and ZnO, and 28.0 mol % or less of R'O (R' is an alkaline earth metal), and does not _{contain B2O3} .

The present invention also relates to a glass product containing the above-mentioned slightly water-soluble glass.

The present invention also relates to a composition containing the above-mentioned slightly water-soluble glass.

Furthermore, the present invention is a method for improving water quality, which comprises immersing the slightly water-soluble glass or the slightly water-soluble glass product in water and dissolving at least one type of ion selected from Cu ions and Zn ions into the water.

According to the present invention, it is possible to provide a slightly water-soluble glass capable of eluting Cu ions and Zn ions over a long period of time, a slightly water-soluble glass product, and a method for improving water quality.
Furthermore, according to the present invention, there can be provided a composition capable of producing a slightly water-soluble glass product having the above-mentioned characteristics.

The following is a detailed description of the embodiments of the present invention. The present invention is not limited to the following embodiments, and it should be understood that modifications and improvements to the following embodiments, as appropriate, based on the ordinary knowledge of those skilled in the art, fall within the scope of the present invention, provided they do not deviate from the spirit of the present invention.

The slightly water-soluble glass according to an embodiment of the present invention (hereinafter, sometimes simply referred to as "glass") contains 40.0 to 75.0 mol % of _SiO2 , 5.0 to 38.0 mol % of _K2O , 0.1 to 33.0 mol % of at least one selected from CuO and ZnO, and 28.0 mol % or less of R'O (R' is an alkaline earth metal).

In this specification, the term "slightly water-soluble glass" refers to glass that dissolves slowly in water. Specifically, the slightly water-soluble glass satisfies the following conditions in dissolution tests (normal and accelerated).
(1) Normal test: In the normal test, the glass does not dissolve completely.
A typical test is performed by immersing a 1 cm x 1 cm x 0.5 cm piece of glass in 100 mL of distilled water at 20°C for 12 hours.
(2) Accelerated Test The mass loss rate of the glass in the accelerated test is 2% or more.
The mass reduction rate is calculated by the following formula.
(mass of glass before accelerated test−mass of glass after accelerated test)/mass of glass before accelerated test×100
The accelerated test is carried out as follows. First, the glass is crushed and then sieved into glass particles having a particle size of 1.4 to 2.0 mm, and the mass (mass of the glass before the accelerated test) is measured. Next, the sieved glass particles are immersed in 100 mL of distilled water at 90°C for 5 hours, and then sieved using a sieve with 0.5 mm openings. In the sieving, glass particles that have deteriorated and are no longer glass are crushed and removed. Next, the glass particles remaining on the sieve are dried, and the mass (mass of the glass after the accelerated test) is measured.

By making the glass slightly water-soluble, Cu ions and Zn ions can be gradually eluted as the glass slowly dissolves in water, so that Cu ions and Zn ions can be eluted into the water for a long period of time, and therefore the effects of the Cu ions and Zn ions (for example, growth inhibition or repellent effect against pests such as mosquito larvae, moss, algae, etc., antibacterial effect, antiviral effect) can be maintained for a long period of time.
The duration of the effect of Cu ions and Zn ions depends on the shape of the slightly water-soluble glass (particularly the surface area), the amount of water, the water temperature, etc., but for example, the effect can be sustained as long as the slightly water-soluble glass is visible. The duration of the effect can be appropriately set depending on the application of the slightly water-soluble glass, but can be adjusted so as to last, for example, from about 1 day to 10 years.

_SiO2 is a component that forms the network structure of glass.
If the content of SiO ₂ is less than 40.0 mol%, the strength of the glass is insufficient. On the other hand, if the content of SiO ₂ is more than 75.0 mol%, the network structure becomes too strong. As a result, the dissolution rate of the glass decreases, so that Cu ions and Zn ions are not sufficiently dissolved in water, and the effect of Cu ions and Zn ions is not fully obtained. Therefore, the content of SiO ₂ is controlled to 40.0 to 75.0 mol%, preferably 42.0 to 72.0 mol%, and more preferably 43.0 to 70.0 mol%, from the viewpoint of stably securing the balance between the strength and dissolution rate of the glass.

K ₂ O is a component that increases the melting rate of glass.
If the content of K ₂ O is less than 5.0 mol%, the dissolution rate of the glass is decreased, so that Cu ions and Zn ions are not sufficiently dissolved in water, and the effect of Cu ions and Zn ions is not sufficiently obtained. On the other hand, if the content of K ₂ O exceeds 38.0 mol%, the dissolution rate of the glass becomes too fast, so that Cu ions and Zn ions cannot be dissolved for a long period of time. Therefore, from the viewpoint of ensuring an appropriate dissolution rate of the glass, the content of K ₂ O is controlled to 5.0 to 38.0 mol%, preferably 7.0 to 37.0 mol%, and more preferably 9.0 to 36.0 mol%.

CuO and ZnO are components contained in the network structure of the glass and are dissolved as Cu ions and Zn ions when the glass is brought into contact with water. CuO and ZnO can be used alone or in combination.
If the total content of CuO and ZnO is less than 0.1 mol%, the amount of Cu ions and Zn ions dissolved in water is insufficient, and the effect of Cu ions and Zn ions cannot be obtained sufficiently. On the other hand, if the total content of CuO and ZnO exceeds 33.0 mol%, it becomes easy to crystallize without vitrification, and as a result, it becomes difficult to dissolve in water, and it becomes difficult to control the amount of Cu ions and Zn ions dissolved in an appropriate range. Therefore, from the viewpoint of ensuring a balance between the amount of Cu ions and Zn ions dissolved and the solubility of glass, the total content of CuO and ZnO is controlled to 0.1 to 33.0 mol%, preferably 0.5 to 32.0 mol%, and more preferably 0.8 to 31.0 mol%.

When both CuO and ZnO are contained in the glass, the molar ratio of CuO to ZnO is not particularly limited, but is preferably 35:1 to 1:35, more preferably 10:1 to 1:10, and even more preferably 3:1 to 1:3. By controlling the molar ratio within such a range, it becomes possible to dissolve Cu ions and Zn ions in water in a balanced manner over a long period of time.

R'O (R' is an alkaline earth metal) is a component that improves chemical durability such as moisture absorption or water resistance of glass, and is contained in glass as necessary. R' is not particularly limited, but examples thereof include Mg, Ca, Sr, Ba, etc. R'O may be of a single type or of multiple types.
If the R'O content exceeds 28.0 mol%, the glass becomes difficult to dissolve in water. Therefore, from the viewpoint of ensuring the solubility of the glass, the R'O content is controlled to 28.0 mol% or less, preferably 25.0 mol% or less, and more preferably 20.0 mol% or less.
In addition, since R'O does not necessarily have to be contained in the glass, the lower limit of the content is not particularly limited. From the viewpoint of obtaining the above-mentioned effects of R'O, the lower limit of R'O is generally 0.1 mol%.

The slightly water-soluble glass according to the embodiment of the present invention may further contain known components that can be contained in glass as necessary, as long as the effects of the present invention are not impaired. Such known components are not particularly limited, but examples thereof include _R2O (R is an alkali metal other than K) _{and Al2O3} .

_R2O (R is an alkali metal other than K) is a component that reduces the melting point and viscosity of glass, and is contained in glass as necessary. R is not particularly limited, but examples thereof include Na, Li, Rb, and Cs. Among these, from the viewpoint of cost, R is preferably Na or Li. _R2O may be a single type or multiple types.
If the content of _R2O exceeds 35.0 mol%, the glass becomes easily dissolved in water. Therefore, from the viewpoint of ensuring the slow solubility of the glass, the content of _R2O is controlled to 35.0 mol% or less, preferably 33.0 mol% or less, and more preferably 31.0 mol% or less.
Since R ₂ O does not necessarily have to be contained in the glass, there is no particular lower limit for the content thereof. From the viewpoint of obtaining the above-mentioned effects due to R ₂ O, the lower limit of R ₂ O is generally 0.1 mol %.

Al ₂ O ₃ , like R'O, is a component that improves the hygroscopicity or chemical durability, such as water resistance, of the glass.
If the content of _Al2O3 exceeds 30.0 _mol %, the glass becomes difficult to dissolve in water. Therefore, from the viewpoint of ensuring the solubility of the glass, the content of _Al2O3 is preferably 30.0 mol% or less, more preferably 28.0 mol% or less, and even more preferably 25.0 mol% or less. The lower limit of the _{content of Al2O3 is not} particularly limited, but is generally 0.1 mol _% from the viewpoint of obtaining the above-mentioned effect of _Al2O3 .

The slightly water-soluble glass according to the embodiment of the present invention preferably does not contain at least one selected from B ₂ O ₃ and P ₂ O ₅ , and more preferably does not contain both B ₂ O ₃ and P ₂ O ₅ .
_B2O3 and _P2O5 are components _that have a large environmental impact. Therefore, by making glass with a composition that does not contain these components, the glass _can be used by being scattered in outdoor puddles, etc., and can be used for a variety of purposes.
However, _B2O3 and _P2O5 are components that form the network structure of glass like _SiO2 , and may be contained in the glass as necessary as long as _they do not _{have an adverse effect on the environment. The amount of B2O3 and P2O5 that does not} have an adverse effect on the environment is less than 0.5 mol% _each .

The slightly water-soluble glass according to the embodiment of the present invention preferably has a specific gravity of 2.4 or more. By controlling the specific gravity within this range, for example, when the slightly water-soluble glass is used by scattering it in outdoor puddles, the slightly water-soluble glass can be made less likely to be washed away by rain or the like. The upper limit of the specific gravity is not particularly limited, but is preferably 10.0, more preferably 8.0, and even more preferably 5.0, taking into consideration the transportability of the slightly water-soluble glass.
The specific gravity can be measured by a commercially available specific gravity meter using the Archimedes method.

The slightly water-soluble glass according to the embodiment of the present invention can elute Cu ions and/or Zn ions over a long period of time, and can therefore be used in various applications where it is desirable to obtain the effects of Cu ions and/or Zn ions over a long period of time. Examples of such applications include growth inhibitors or repellents for pests, mosses, algae, etc., antibacterial agents, antiviral agents, etc. Among these, growth inhibitors or repellents for pests, mosses, algae, etc. (especially mosquito larvae) are preferred.

The shape of the slightly water-soluble glass according to the embodiment of the present invention is not particularly limited, and can be appropriately set depending on the application.
For example, when the slightly water-soluble glass itself is used as a growth inhibitor or repellent for pests, mosses, algae, etc., the slightly water-soluble glass may be formulated into an appropriate formulation. When the slightly water-soluble glass is used as a growth inhibitor or repellent by being blended with an existing agent such as a plant growth agent, the slightly water-soluble glass may be powdered and blended with the existing agent. Furthermore, when the slightly water-soluble glass is used as a raw material for molding materials, coating materials, etc., the slightly water-soluble glass may be powdered and blended with the molding materials or coating materials.

When the slightly water-soluble glass according to the embodiment of the present invention is used as a growth inhibitor or repellent for mosquito larvae, it is preferable to use it so that the concentration of Cu ions and/or Zn ions in the water is 0.5 ppm or more, preferably 1.0 ppm or more, more preferably 2.0 ppm or more. By making the concentration of Cu ions and/or Zn ions 0.5 ppm or more, it is possible to obtain a growth inhibitory effect or a repellent effect for mosquito larvae. In particular, if the concentration of Cu ions and/or Zn ions is 2.0 ppm or more, mosquito larvae hardly grow.
The upper limit of the concentration of Cu ions and/or Zn ions is not particularly limited and may be set appropriately depending on environmental standards, etc.

The slightly water-soluble glass according to the embodiment of the present invention can be manufactured in the same manner as known glass manufacturing methods. That is, the slightly water-soluble glass according to the embodiment of the present invention can be manufactured by mixing the above-mentioned components to a predetermined content, heating to a high temperature to melt, forming the molten material into a predetermined shape (e.g., a plate shape), and cooling. The molten material may be poured into a predetermined mold and cooled to form into a predetermined shape. When the slightly water-soluble glass is used as a raw material for molding materials, coating materials, etc., the obtained slightly water-soluble glass may be pulverized into a powder.

The glass product of the present invention, which is a slightly water-soluble glass according to an embodiment, comprises the above-mentioned slightly water-soluble glass. Because this glass product of the present invention comprises the above-mentioned slightly water-soluble glass, it is able to elute Cu ions and Zn ions for a long period of time. Therefore, this glass product of the present invention is able to obtain the effects of Cu ions and Zn ions (for example, growth inhibition or repellent effects against pests such as mosquito larvae, mosses, algae, etc., antibacterial effects, and antiviral effects) for a long period of time.

An example of a slightly water-soluble glass product according to an embodiment of the present invention is a coating product comprising a substrate and a coating layer formed on the surface of the substrate, the coating layer containing the above-mentioned slightly water-soluble glass. In the coating product, the slightly water-soluble glass is preferably dispersed in the coating layer. The substrate is not particularly limited, and may be one formed from metal, resin, or the like.
Another example of the slightly water-soluble glass product according to the embodiment of the present invention is a resin molded product containing the above-mentioned slightly water-soluble glass. In the resin molded product, the slightly water-soluble glass is preferably dispersed in the resin.

The above-mentioned glass products with slightly water solubility can be manufactured using a composition containing the slightly water soluble glass. For example, a coated product can be manufactured by using a composition containing the slightly water soluble glass as a coating material and coating a substrate with the coating material. A resin molded product can be manufactured by using a composition containing the slightly water soluble glass as a molding material and molding the molding material into a predetermined shape.

The composition used as the coating material can contain, in addition to the slightly water-soluble glass, known components used in coating materials (for example, resin components, solvents, inorganic components, etc.).
The composition used as the molding material may contain, in addition to the slightly water-soluble glass, known components used in molding materials (for example, resin components, inorganic components, etc.).

In the water quality improvement method according to an embodiment of the present invention, the above-mentioned slightly water-soluble glass or the above-mentioned slightly water-soluble glass product is immersed in water, and at least one type of ion selected from Cu ions and Zn ions is dissolved into the water. According to this method, the elution of Cu ions and/or Zn ions can have a growth-inhibiting or repelling effect on pests such as mosquito larvae, mosses, algae, etc., thereby making it possible to improve the water quality.

The elution concentration of Cu ions and/or Zn ions in water is not particularly limited, but is preferably 0.5 ppm or more, preferably 1.0 ppm or more, and more preferably 2.0 ppm or more. By setting the elution concentration of Cu ions and/or Zn ions to 0.5 ppm or more, the above-mentioned effects can be obtained. The upper limit of the elution concentration of Cu ions and/or Zn ions is not particularly limited, and may be set appropriately according to environmental standards, etc.

The amount of the above-mentioned slightly water-soluble glass or the above-mentioned slightly water-soluble glass product added to the water is not particularly limited, and may be set appropriately according to the amount of water so that a specified elution concentration of Cu ions and/or Zn ions can be maintained for a long period of time.

The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

Each raw material was weighed and mixed uniformly to obtain the composition shown in Table 1. This mixture was then heated at 1300-1450°C for 2-3 hours to melt it, after which the molten material was formed into a plate and cooled to obtain a plate sample. Note that samples Nos. 9, 10, 13, and 14 were crystallized without being vitrified, whereas the other test samples were vitrified. The plate samples thus obtained were evaluated as follows.

<Specific Gravity>
The specific gravity was measured using a specific gravity meter (MD-200S manufactured by Alpha Mirage Co., Ltd.).

<Dissolution test>
As dissolution tests, the above-mentioned normal test and accelerated test were carried out.
(1) Normal Test In the normal test, a glass piece measuring 1 cm x 1 cm x 0.5 cm was immersed in 100 mL of distilled water at 20° C. for 12 hours. In the evaluation of this normal test, the glass was marked as ◯ when it was not completely dissolved, and marked as × when it was completely dissolved. Whether the glass was completely dissolved or not was determined by visual observation.
(2) Accelerated Test After crushing the plate-shaped sample, the glass particles having a particle diameter of 1.4 to 2.0 mm were crushed using a sieve, and the mass (mass of glass before the accelerated test) was measured. Next, the crushed glass particles were immersed in 100 mL of distilled water at 90° C. for 5 hours, and then sieved using a sieve with a mesh size of 0.5 mm. The glass particles remaining on the sieve were thoroughly washed using distilled water. Next, the glass particles remaining on the sieve were dried, and the mass (mass of glass after the accelerated test) was measured. Then, the mass reduction rate of the glass was calculated using the above formula. In the evaluation of this accelerated test, the glass mass reduction rate of 2% or more was represented as ◯, and the glass mass reduction rate of less than 2% was represented as ×.
The results of the above evaluations are shown in Table 1.

As shown in Table 1, the samples of Test Nos. 2 to 8, 15, 19 to 21, and 23 to 24 (examples of the present invention) were determined to be slightly water-soluble glasses from the results of the dissolution test and contained a predetermined amount of CuO and/or ZnO. Therefore, these samples can gradually release Cu ions and/or Zn ions as the glass slowly dissolves in water.
In contrast, the samples of Test Nos. 1, 16, and 17 (Comparative Examples) were found to be water-soluble glass based on the results of the dissolution (normal) test. Therefore, in these samples, the glass immediately dissolved in water and Cu ions and/or Zn ions could not be gradually eluted.
In addition, the samples of Test Nos. 11, 12, 18, and 22 (Comparative Examples) are poorly water-soluble glasses based on the results of the dissolution (accelerated) test. Therefore, in these samples, the glass is poorly dissolved in water and Cu ions and/or Zn ions cannot be gradually eluted.
In addition, the samples of Test Nos. 9, 10, 13 and 14 (Comparative Examples) are considered not to be dissolved in water because they were crystallized without being vitrified. Therefore, these samples are not able to gradually elute Cu ions and/or Zn ions.

As can be seen from the above results, the present invention can provide a glass with low water solubility that can dissolve Cu ions and Zn ions over a long period of time, a glass product with low water solubility, and a method for improving water quality. The present invention can also provide a composition that can be used to manufacture a glass product with low water solubility that has the above characteristics.

Claims (8)

A glass having a low water solubility used as a growth inhibitor or repellent for pests, moss, and algae, an antibacterial agent, or an antiviral agent,
A slightly water-soluble glass containing 40.0 to 75.0 mol % of SiO ₂ , 5.0 to 38.0 mol % of K ₂ O, 0.1 to 33.0 mol % of at least one selected from CuO and ZnO, and 28.0 mol % or less of R'O (R' is an alkaline earth metal), and not containing B ₂ O ₃ . 2. The glass according to claim 1, further comprising at least one selected from the _group consisting of 35.0 mol % or less of _R2O (R is an alkali metal other than K) and 30.0 mol % or less of _Al2O3 . _3. The slightly water-soluble glass according to claim 1, which is free of _P2O5 . The slightly water-soluble glass according to any one of claims 1 to 3, having a specific gravity of 2.4 or more. A glass product having a slightly water solubility comprising the glass according to any one of claims 1 to 4 . A composition comprising the slightly water-soluble glass according to any one of claims 1 to 4 . The composition according to claim 6 , which is a molding material or a coating material. A method for improving water quality, comprising immersing the slightly water-soluble glass according to any one of claims 1 to 4 or the slightly water-soluble glass product according to claim 5 in water, and dissolving at least one type of ion selected from Cu ions and Zn ions into the water.