Glass compositions, sustained-release compositions, medical compositions, and dental compositions

Abstract

The present invention provides a glass composition that yields glass that is poorly soluble in acidic and neutral environments, even in environments where the acidity changes between neutral and acidic ranges. [Solution] The glass composition contains gallium and phosphorus, at least one selected from alkali metals, calcium, and strontium, and contains aluminum in an oxide equivalent of 0% to 3.8% by mass.

Description

Technical Field

[0001] The present invention relates to a glass composition, a sustained-release composition, a medical composition, and a dental composition.

Background Art

[0002] Conventionally, sustained-release glasses that gradually release functional ions have been known. For example, there are techniques using inorganic glass particles that release phosphorus ions or calcium ions into water as granular soil conditioners, techniques using potassium glass as fertilizers, techniques using antibacterial glasses that elute silver ions in resin molded products, techniques using bioglass in medical applications such as bone repair materials and medical implants, and techniques using ion-sustained-release glasses in deodorant compositions (see Patent Documents 1 to 6).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Summary of the Invention

Problems to be Solved by the Invention

[0004] When conventional sustained-release glasses are used in an environment where the acidity is not constant, if the acidity changes, the sustained release of the glass may not be controllable.

[0005] The object of the present invention is to provide a glass composition that yields glass that is poorly soluble in acidic ranges and readily soluble in neutral ranges, even in environments where the acidity changes between neutral and acidic ranges. [Means for solving the problem]

[0006] A glass composition according to one aspect of the present invention contains gallium and phosphorus, at least one selected from alkali metals, calcium, and strontium, and contains aluminum in an oxide equivalent of 0% to 3.8% by mass. [Effects of the Invention]

[0007] According to one aspect of the present invention, it is possible to provide a glass composition that yields glass that is poorly soluble in acidic ranges and readily soluble in neutral ranges, even in environments where the acidity changes between neutral and acidic ranges. [Modes for carrying out the invention]

[0008] The embodiments of the present invention will be described in detail below.

[0009] <Glass composition> The glass composition according to this embodiment contains gallium and phosphorus, at least one selected from alkali metals, calcium, and strontium, and contains aluminum in an oxide equivalent of 0% to 3.8% by mass.

[0010] In this specification, the form of glass constituting a glass composition is not limited to amorphous glass, but also includes crystalline glass, or a mixture of amorphous and crystalline glass. Furthermore, glass also includes glass ceramics, which are composed of glass in part.

[0011] The glass is preferably in powder form. The size of the glass powder is preferably 0.01 μm to 100 μm in median diameter, more preferably 0.02 μm to 50 μm, and even more preferably 0.03 μm to 30 μm. In this specification, the median diameter refers to the particle size (D50) at which the cumulative distribution based on volume, measured by laser diffraction-scattering, reaches 50%. By having a glass powder size of 0.01 μm to 100 μm in median diameter, the glass can exhibit sustained release properties.

[0012] Gallium (Ga) can exist in glass compositions in the form of gallium oxide (gallium oxide (Ga2O3)). By incorporating gallium into glass compositions, it becomes easier to obtain glass that does not dissolve too much in acidic conditions and dissolves easily in neutral conditions.

[0013] The gallium (Ga) content in the glass composition is preferably 5% to 45% by mass in terms of oxide, more preferably 10% to 40% by mass, and even more preferably 15% to 38% by mass. When the Ga content is 5% by mass or more, it is easier to obtain glass that does not dissolve too much in the acidic range and dissolves easily in the neutral range, and when it is 45% by mass or less, the melting temperature of the glass is lowered, making it easier to obtain glass.

[0014] Phosphorus (P) can exist in the glass composition in the form of phosphorus oxide (gallium oxide (P2O5)). By incorporating phosphorus into the glass composition, phosphorus plays a role in network formation within the glass. Furthermore, the presence of phosphorus in the glass composition prevents the release of phosphate ions (PO4) from the glass. 3- This allows, for example, when a glass composition is used in the oral cavity, to impart effects such as remineralization of tooth structure and prevention of caries.

[0015] The content of phosphorus (P) is preferably 40% to 80% by mass in terms of oxide in the glass composition, more preferably 45% to 75% by mass, and still more preferably 50% to 70% by mass. When the content of P is 40% by mass or more, it becomes easier to obtain the glass. When it is 80% by mass or less, more other components can be contained, and the handling during the production of the glass is improved.

[0016] Alkali metals can exist in the glass composition in the form of oxides of alkali metals. By adding alkali metals to the glass composition, the melting temperature of the glass can be lowered, and further the solubility of the glass can be increased.

[0017] Alkali metals are lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr), which are metal elements belonging to Group 1 in the periodic table. Among these, Na and K are preferred in that they can lower the melting temperature of the glass and further increase the solubility of the glass. When the alkali metal is Na, it can exist in the glass composition in the form of sodium oxide (sodium oxide (Na2O)).

[0018] The content of alkali metals is preferably 0% to 30% by mass in terms of oxide in the glass composition, more preferably 0% to 25% by mass, and still more preferably 0% to 20% by mass. When the content of alkali metals is 0% to 30% by mass, it becomes easier to obtain a glass that does not dissolve too much when the acidity is low.

[0019] Calcium (Ca) can exist in the glass composition in the form of calcium oxide (calcium oxide (CaO)). By adding calcium to the glass composition, calcium ions (Ca 2+ ) released from the glass can have an acid resistance effect, a tooth enamel demineralization inhibitory effect, and a bone formation promoting effect.

[0020] The content of calcium (Ca) in the glass composition is preferably 0% by mass or more and 30% by mass or less in terms of oxide, more preferably 0% by mass or more and 25% by mass or less, and still more preferably 5% by mass or more and 20% by mass or less. When the content of Ca is 0% by mass or more and 30% by mass or less, an acid resistance effect, a dentin demineralization inhibition effect, and a bone formation promoting effect can be imparted, the melting temperature of the glass can be lowered, and the solubility of the glass can be further increased, making it easier to obtain a glass that does not dissolve too much in the acidic range.

[0021] Strontium (Sr) can exist in the glass composition in the form of strontium oxide (strontium oxide (SrO)). By incorporating strontium into the glass composition, strontium ions (Sr 2+ ) released from the glass can impart an acid resistance effect and a bone formation promoting effect.

[0022] The content of strontium (Sr) in the glass composition is preferably 0% by mass or more and 30% by mass or less in terms of oxide, more preferably 0% by mass or more and 25% by mass or less, and still more preferably 5% by mass or more and 20% by mass or less. When the content of Sr is 0% by mass or more and 30% by mass or less, an acid resistance effect and a bone formation promoting effect can be imparted, and it is easier to obtain a glass that does not dissolve too much in the acidic range.

[0023] Aluminum (Al) can exist in the glass composition in the form of aluminum oxide (aluminum oxide (Al2O3)). By incorporating aluminum into the glass composition, the chemical durability of the glass can be improved and the stability as a glass can be enhanced.

[0024] The content of aluminum (Al) in the glass composition is 0% by mass or more and 3.8% by mass or less, more preferably 0% by mass or more and 3.6% by mass or less, and still more preferably 0% by mass or more and 3.4% by mass or less in terms of oxide. When the content of Al is 0% by mass or more and 3.8% by mass or less, it is easier to obtain a glass that does not dissolve too much in the acidic range.

[0025] The glass composition according to this embodiment preferably further contains fluorine (F). Fluorine (F) may exist in the glass composition as fluoride or fluoride salt. By incorporating fluorine into the glass composition, the demineralization inhibitory effect and antibacterial effect of the glass are improved.

[0026] The fluorine (F) content in the glass composition is 0% to 20% by mass, more preferably 0% to 15% by mass, and even more preferably 0% to 10% by mass, in terms of oxide. When the F content is 0% by mass or more, the demineralization inhibitory effect and antibacterial effect of the glass can be obtained, and when it is 20% by mass or less, the glass is easier to obtain.

[0027] Furthermore, the glass composition of this embodiment may contain other elements such as silver (Ag), copper (Cu), zinc (Zn), lithium (Li), and boron (B), as long as they do not impair the purpose of the present invention.

[0028] The glass composition of this embodiment preferably does not contain silicon (Si). Here, "does not contain" means that silicon is not actively added to the glass composition, but this does not exclude the possibility of silicon being mixed in as an unavoidable component such as an impurity during the manufacturing process. Because the glass composition does not contain silicon, the melting point of the glass is less likely to rise, so the melting temperature of the glass can be lowered, making it easier to obtain glass.

[0029] As described above, the glass composition of this embodiment contains Ga, P, and at least one selected from alkali metals, Ca, and Sr, and contains Al in an oxide equivalent of 0% to 3.8% by mass, so that the solubility in the neutral range is greater than the solubility in the acidic range. In this specification, the neutral range refers to a pH range greater than 6.5 and less than 8, and the acidic range refers to a pH range of 6.5 or less.

[0030] Furthermore, the solubility is calculated by immersing the sample in a predetermined buffer solution and following the formula (1) below. Dissolution rate (%) = [(Weight before immersion) - (Weight after immersion)] × 100 / Weight before immersion ... (1) Generally, glass dissolves more easily in acidic conditions than in neutral conditions. If too much dissolution occurs in acidic conditions, a large amount of glass will be consumed in those conditions, which could lead to a decrease in the amount of sustained ion release in neutral conditions and a shortened lifespan of the sustained ion release ability. For example, when using a glass composition in the oral cavity, it is desirable for a large amount of calcium (Ca) to be released in neutral conditions to efficiently promote remineralization. Releasing a large amount of calcium in acidic conditions is inefficient as it does not contribute much to remineralization or bone formation.

[0031] In contrast, the glass composition of this embodiment has a higher solubility in the neutral range than in the acidic range. As a result, even in environments where the acidity changes between the neutral and acidic ranges, a glass is obtained that is difficult to dissolve in the acidic range and easily dissolves in the neutral range. Therefore, in such a glass, sustained release is suppressed in the acidic range and promoted in the neutral range. In this specification, sustained release refers to the property of a component dissolving and being gradually released in an ionic state.

[0032] As a result, for example, the sustained release properties of the glass can be controlled so that the glass is less likely to dissolve when the acidity in the oral cavity becomes acidic after a meal, and more likely to dissolve when the acidity in the oral cavity returns to a neutral range.

[0033] In the glass composition of this embodiment, the pH in the neutral range is 7.5, the pH in the acidic range is 4.5, and the ratio of the solubility at pH 7.5 to the solubility at pH 4.5 is preferably 1.4 or higher, more preferably 1.6 or higher, and even more preferably 1.8 or higher. When the ratio of the solubility at pH 7.5 to the solubility at pH 4.5 is 1.4 or higher, a glass is obtained that is less soluble in the acidic range and more soluble in the neutral range.

[0034] Furthermore, in the glass composition of this embodiment, the pH in the neutral range is 7.5, the pH in the acidic range is 5.5, and the ratio of the solubility at pH 7.5 to the solubility at pH 5.5 is preferably 1.4 or higher, more preferably 1.45 or higher, and even more preferably 1.5 or higher. When the ratio of the solubility at pH 7.5 to the solubility at pH 4.5 is 1.4 or higher, a glass that is less soluble in the acidic range and more soluble in the neutral range can be obtained.

[0035] <Sustained release composition> The sustained-release composition according to this embodiment includes the glass composition of this embodiment described above. Specifically, the sustained-release composition of this embodiment contains gallium and phosphorus, at least one selected from alkali metals, calcium, and strontium, and aluminum in an oxide equivalent of 0% by mass or more and 3.8% by mass or less. In this specification, a sustained-release composition means a composition in which the components dissolve and are gradually released in an ionic state.

[0036] In the sustained-release composition according to this embodiment, the same effects as the glass composition of this embodiment can be obtained by including such a glass composition. Specifically, the sustained-release composition of this embodiment contains glass that is difficult to dissolve in the acidic range and easy to dissolve in the neutral range, even in environments where the acidity changes between the neutral and acidic ranges. Therefore, sustained release can be suppressed in the acidic range and promoted in the neutral range. As a result, by using such a sustained-release composition in the oral cavity, for example, the sustained release of the glass can be controlled so that the glass is difficult to dissolve when the acidity in the oral cavity becomes acidic after a meal, and easy to dissolve when the acidity in the oral cavity returns to the neutral range.

[0037] The applications of the sustained-release composition are not particularly limited and include, for example, resins, coatings, soil conditioners, fertilizers, electronic materials, bone grafts, biomaterials, medical materials, and dental materials.

[0038] <Medical Compositions> The medical composition according to this embodiment includes the sustained-release composition of this embodiment described above. Specifically, the medical composition of this embodiment contains a glass composition that contains gallium and phosphorus, at least one selected from alkali metals, calcium, and strontium, and aluminum in an oxide equivalent of 0% by mass or more and 3.8% by mass or less. In this specification, a medical composition refers to a composition used for medical purposes.

[0039] In the medical composition according to this embodiment, the same effects as the glass composition of this embodiment can be obtained by including a sustained-release composition containing such a glass composition. Specifically, the medical composition of this embodiment contains glass that is difficult to dissolve in the acidic range and easy to dissolve in the neutral range, even in environments where the acidity changes between the neutral and acidic ranges. Therefore, sustained release can be suppressed in the acidic range and promoted in the neutral range. As a result, by using such a medical composition, for example, the sustained release of glass can be controlled so that the glass is difficult to dissolve when the acidity in the body becomes acidic in response to changes in acidity in bone destruction, bone formation, skin regeneration, etc., and easy to dissolve when the acidity in the body returns to the neutral range.

[0040] The uses of the medical composition are not particularly limited and include, for example, bone graft materials and artificial dermis.

[0041] <Dental Compositions> The dental composition according to this embodiment includes the sustained-release composition of this embodiment described above. Specifically, the dental composition of this embodiment contains a glass composition that contains gallium and phosphorus, at least one selected from alkali metals, calcium, and strontium, and aluminum in an oxide equivalent of 0% to 3.8% by mass. In this specification, "dental composition" refers to a composition used in dental applications.

[0042] In the dental composition according to this embodiment, the inclusion of a sustained-release composition containing such a glass composition provides the same effects as the glass composition of this embodiment. Specifically, the dental composition of this embodiment contains glass that is less soluble in acidic environments and more soluble in neutral environments, even in environments where the acidity changes between neutral and acidic ranges. Therefore, sustained release can be suppressed in acidic environments and promoted in neutral environments. As a result, by using such a dental composition in the oral cavity, the sustained release of the glass can be controlled such that, for example, the glass is less soluble when the acidity in the oral cavity becomes acidic after a meal, and more soluble when the acidity in the oral cavity returns to a neutral range.

[0043] The uses of dental compositions are not particularly limited and include, for example, dental cements, dental adhesives, temporary dental fillings, temporary dental fixatives, dental primers, dental coatings, root coverings, dental composite resins, dental hard resins, dental cutting resin materials, temporary dental restoratives, dental fillings, pulp capping materials, denture base materials, artificial teeth, and toothpastes. [Examples]

[0044] The present invention will be further described below with reference to examples. Various tests and evaluations will be carried out according to the methods described below. In the following, unitless numerical values, "%", or "parts" are based on mass unless otherwise specified.

[0045] <Preparation of glass powder> The raw materials were weighed, mixed in a Teflon beaker, and after the water was evaporated, the mixture was placed in a platinum crucible and melted at a predetermined temperature for 1 hour. The melt was then cooled by an iron press. This mixture was then ground in a ball mill for 30 minutes (ethanol wet grinding, 40 mm alumina balls, 100 rpm), and then ground again in a ball mill for 30 minutes (ethanol wet grinding, 5 mm alumina balls, 100 rpm). After that, the glass powder was recovered by centrifugation, and the remaining ethanol was removed by vacuum drying (-0.1 MPa, 40°C) to obtain glass powder.

[0046] <Particle size distribution of glass powder> The obtained glass powders were dispersed in ethanol, and the particle size distribution was measured using a laser diffraction / scattering particle size analyzer (Partica LA-960V2, Horiba, Ltd.). It was confirmed that the D(50) of all glass powders was in the range of 10 ± 2 μm.

[0047] <Composition of glass powder> The composition of the glass powder was determined by analyzing it using a Rigaku ZSX Primus IV X-ray fluorescence analyzer. Tables 1 and 2 show the composition of the glass powder (unit: mass%).

[0048] <Dissolution rate> 50 mg of glass powder was immersed in 10 mL of pH 4.5 acetic acid-sodium acetate buffer, 10 mL of pH 5.5 acetic acid-sodium acetate buffer, and 10 mL of pH 7.5 hydroxyethylpiperazine ethanesulfonic acid (HEPES) buffer, respectively. The solutions were stored at 37°C, then filtered through a 0.2 μm syringe filter. The filtered glass was dried with the syringe filter at 60°C for 48 hours. The weights of the syringe filter and glass were then measured, and the solubility at pH 4.5, pH 5.5, and pH 7.5 was calculated according to formula (1) below. The calculation results are shown in Tables 1 and 2. Dissolution rate (%) = [(Weight before immersion) - (Weight after immersion)] × 100 / Weight before immersion ... (1)

[0049] <Dissolution rate ratio> From the solubility rates at pH 4.5, pH 5.5, and pH 7.5, the ratio of the solubility rate at pH 4.5 to the solubility rate at pH 7.5 (solubility rate at pH 7.5 / solubility rate at pH 4.5) and the ratio of the solubility rate at pH 5.5 to the solubility rate at pH 7.5 (solubility rate at pH 7.5 / solubility rate at pH 5.5) were calculated. A ratio of 1.4 or higher for the solubility rate at pH 7.5 / solubility rate at pH 4.5 was evaluated as good, and a ratio below 1.4 was evaluated as poor. Similarly, a ratio of 1.4 or higher for the solubility rate at pH 7.5 / solubility rate at pH 5.5 was evaluated as good, and a ratio below 1.4 was evaluated as poor.

[0050] Examples and comparative examples will be described below.

[0051] [Example 1] Glass containing 56.1 parts phosphorus pentoxide (P2O5), 11.2 parts calcium oxide (CaO), and 32.7 parts gallium oxide (Ga2O3) was prepared and evaluated. The composition of the glass and the evaluation results are shown in Tables 1 and 2.

[0052] [Example 2] Glass containing 66.0 parts phosphorus pentoxide (P2O5), 15.9 parts calcium oxide (CaO), and 18.1 parts gallium oxide (Ga2O3) was prepared and evaluated. The composition of the glass and the evaluation results are shown in Tables 1 and 2.

[0053] [Example 3] Glass containing 58.0 parts phosphorus pentoxide (P2O5), 7.0 parts calcium oxide (CaO), 13.9 parts strontium oxide (SrO), and 21.1 parts gallium oxide (Ga2O3) was prepared and evaluated. The composition of the glass and the evaluation results are shown in Tables 1 and 2.

[0054] [Example 4] Glass containing 53.8 parts of phosphorus pentoxide (P2O5), 26.1 parts of strontium oxide (SrO), and 20.1 parts of gallium oxide (Ga2O3) was prepared and evaluated. The composition of the glass and the evaluation results are shown in Tables 1 and 2.

[0055] [Example 5] Glass containing 64.3 parts phosphorus pentoxide (P2O5), 13.4 parts sodium oxide (Na2O), 19.7 parts gallium oxide (Ga2O3), and 2.6 parts aluminum oxide (Al2O3) was prepared and evaluated. The composition of the glass and the evaluation results are shown in Tables 1 and 2.

[0056] [Example 6] Glass containing 64.7 parts phosphorus pentoxide (P2O5), 13.6 parts sodium oxide (Na2O), 18.4 parts gallium oxide (Ga2O3), and 3.3 parts aluminum oxide (Al2O3) was prepared and evaluated. The composition of the glass and the evaluation results are shown in Tables 1 and 2.

[0057] [Example 7] Glass containing 54.2 parts of phosphorus pentoxide (P2O5), 8.3 parts of calcium oxide (CaO), and 37.5 parts of gallium oxide (Ga2O3) was prepared and evaluated. The composition of the glass and the evaluation results are shown in Tables 1 and 2.

[0058] [Example 8] Glass containing 64.2 parts of phosphorus pentoxide (P2O5), 11.4 parts of strontium oxide (SrO), and 24.4 parts of gallium oxide (Ga2O3) was prepared and evaluated. The composition of the glass and the evaluation results are shown in Tables 1 and 2.

[0059] [Comparative Example 1] Glass containing 58.6 parts phosphorus pentoxide (P2O5), 22.7 parts calcium oxide (CaO), 15.2 parts strontium oxide (SrO), 2.7 parts aluminum oxide (Al2O3), and 0.8 parts fluorine (F) was prepared and evaluated. The composition of the glass and the evaluation results are shown in Tables 1 and 2.

[0060] [Comparative Example 2] Glass containing 59.3 parts phosphorus pentoxide (P2O5), 23.6 parts calcium oxide (CaO), 16.2 parts strontium oxide (SrO), and 0.9 parts fluorine (F) was prepared and evaluated. The composition of the glass and the evaluation results are shown in Tables 1 and 2.

[0061] [Comparative Example 3] Glass containing 63.2 parts phosphorus pentoxide (P2O5), 15.5 parts calcium oxide (CaO), 16.7 parts gallium oxide (Ga2O3), and 4.6 parts aluminum oxide (Al2O3) was prepared and evaluated. The composition of the glass and the evaluation results are shown in Tables 1 and 2.

[0062] [Comparative Example 4] Glass containing 68.4 parts phosphorus pentoxide (P2O5), 17.3 parts calcium oxide (CaO), and 14.3 parts aluminum oxide (Al2O3) was prepared and evaluated. The composition of the glass and the evaluation results are shown in Tables 1 and 2.

[0063] [Table 1]

[0064] [Table 2]

[0065] Table 1 shows that in Examples 1 to 8, the glass containing gallium (Ga) and phosphorus (P), and further containing one or more of sodium (Na), calcium (Ca), and strontium (Sr), and further containing aluminum (Al) in an oxide equivalent of 0% to 3.8% by mass, was found to be poorly soluble in acidic ranges and readily soluble in neutral ranges.

[0066] On the other hand, as shown in Table 2, Comparative Examples 1-4 revealed that, compared to Examples 1-8, the glass containing gallium (Ga) and / or aluminum (Al) in an oxide equivalent of more than 3.8% by mass was more easily dissolved in acidic conditions (Comparative Examples 1-5).

[0067] Based on the above, it can be said that glass containing gallium and phosphorus, further containing at least one selected from alkali metals, calcium, and strontium, and further containing aluminum in an oxide equivalent of 0% to 3.8% by mass, is difficult to dissolve in acidic and neutral environments, even when the acidity changes between neutral and acidic ranges.

[0068] Although embodiments of the present invention have been described above, the present invention is not limited to any particular embodiment, and various modifications and changes are possible within the scope of the invention as described in the claims.

Claims

1. It contains gallium and phosphorus, It contains at least one selected from alkali metals, calcium, and strontium. Contains aluminum in an oxide equivalent of 0% by mass or more and 3.8% by mass or less. Glass composition.

2. The solubility in the neutral range is greater than the solubility in the acidic range. The glass composition according to claim 1.

3. The pH in the neutral range is 7.

5. The pH of the aforementioned acidic range is 4.

5. The ratio of the solubility at pH 7.5 to the solubility at pH 4.5 is 1.4 or higher. The glass composition according to claim 2.

4. The pH in the neutral range is 7.

5. The pH of the aforementioned acidic range is 5.

5. The ratio of the solubility at pH 7.5 to the solubility at pH 5.5 is 1.4 or higher. The glass composition according to claim 2.

5. A sustained-release composition comprising the glass composition according to any one of claims 1 to 4.

6. A medical composition comprising the sustained-release composition described in claim 5.

7. A dental composition comprising the sustained-release composition described in claim 5.

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