JP7390595B2 - Glass structure and its manufacturing method - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Act On July 10, 2019, on page 55 of the ``14th Japan Ceramics Association Kansai Branch Academic Lecture Proceedings'', it was stated that ``Bio using biomineralization'' Published under the title "Low temperature sintering process of glass"

Application of Article 30, Paragraph 2 of the Patent Act On July 10, 2019, “Low-temperature sintering process of bioglass using biomineralization” was presented at the “14th Japan Ceramics Association Kansai Branch Academic Lecture”. Published under the title of

Application of Article 30, Paragraph 2 of the Patent Act On July 1, 2019, “2nd Global Forum on Advanced Materials and Technologies for Sustainable Development (GFMA-2) and 4th I International Conference on Innovations in Biomaterials, Biomanufacturing, and Biotechnologies (Bio -4), ABSTRACT BOOK, page 71, "Low-temperature Sintering Process of Bioactive Glass Nanoparticles Under Hydrothermal Condition Published under the title ``ns''

Application of Article 30, Paragraph 2 of the Patent Act On July 25, 2019, at the “2nd Global Forum on Advanced Materials and Technologies for Sustainable Development (GFMAT-2)” w-temperature Sintering Process of Bioactive Glass Nanoparticles Under Presented under the title "Hydrothermal Conditions"

The present invention relates to a glass structure and a method for manufacturing the same.

BACKGROUND ART A sintering method is conventionally known as a method for manufacturing inorganic members made of ceramics. The sintering method is a method of obtaining a sintered body by heating an aggregate of solid powder made of an inorganic substance at a temperature lower than its melting point. However, since the sintering method requires heating the solid powder at a high temperature, there is a problem that energy consumption during production is large and costs are high. Therefore, methods are being developed to bond solid powders made of inorganic substances at low temperatures.

Non-Patent Document 1 discloses a method of performing low-temperature sintering using bioglass as an inorganic substance. Specifically, after adding an aqueous solution to bioglass nanoparticles made of SiO ₂ -CaO-P ₂ O ₅ , the bioglass nanoparticles are heated from room temperature to 200°C and pressurized at several hundred MPa. It is disclosed that a sintered body of can be obtained. Furthermore, Non-Patent Document 1 discloses that bioglass nanoparticles made of SiO ₂ -CaO-P ₂ O ₅ can be synthesized by a sol-gel method. In this low-temperature sintering method, the heating temperature of bioglass nanoparticles is about 200° C., so it is possible to significantly reduce energy consumption during production.

Toru Sekino, “Synthesis of Sol-Gel Derived Bioactive Glass Nanoparticles and Their Low-temperature Sintering”, July 22, 2018, Proceedings of the 12th International Conference on Ceramic Materials and Components for Energy and Environmental Applications (CMCEE)

In the sintered body of bioglass nanoparticles disclosed in Non-Patent Document 1, the bonding portions connecting the bioglass nanoparticles contain amorphous hydroxyapatite. However, since hydroxyapatite has low acid resistance, there has been a problem that the acid resistance of the entire sintered body is also insufficient.

The present invention has been made in view of the problems of the prior art. An object of the present invention is to provide a glass structure that can be manufactured by a low-temperature sintering method and has excellent acid resistance, and a method for manufacturing the glass structure.

In order to solve the above problems, a glass structure according to an aspect of the present invention includes a plurality of glass particles containing SiO ₂ , CaO and P ₂ O ₅ , the glass particles being bonded to each other, and containing apatite containing fluorine. and a connecting portion. The glass structure has a porosity of 15% or less.

A method for manufacturing a glass structure according to a second aspect of the present invention includes a plurality of glass particles containing SiO ₂ , CaO, and P ₂ O ₅ , calcium, phosphorus, and fluorine, and has a pH of 4.0 or higher. The method includes a step of preparing a mixture by mixing with a certain aqueous solution, and a step of heating and pressurizing the mixture.

According to the present disclosure, it is possible to provide a glass structure that can be manufactured by a low-temperature sintering method and has excellent acid resistance, and a method for manufacturing the glass structure.

FIG. 1 is a cross-sectional view schematically showing an example of a glass structure according to the present embodiment. It is a schematic diagram for explaining the mechanism by which fluoroapatite and hydroxyapatite are generated on the surface of glass particles. (a) is a schematic diagram showing a state in which an aqueous solution exists between adjacent glass particles in the manufacturing process of a glass structure. (b) is a schematic diagram showing a state in which a bond containing fluoroapatite and hydroxyapatite is formed between adjacent glass particles. (a) is a graph showing the X-ray diffraction patterns of test samples 1 to 4 and the X-ray diffraction pattern of fluoroapatite registered as JCPDS 15-0876. (b) is a graph showing the X-ray diffraction patterns of test samples 1 to 5. FIG. 3 is a diagram showing backscattered electron images of test samples 1 to 4 observed with a scanning electron microscope. This is a photograph showing the results of fluorine mapping analysis performed on test samples 1 to 4 using energy dispersive X-ray analysis (EDX).

Hereinafter, a glass structure and a method for manufacturing the glass structure according to the present embodiment will be described with reference to the drawings. Note that the dimensional ratios in the drawings are exaggerated for convenience of explanation and may differ from the actual ratios.

[Glass structure]
The glass structure 1 of this embodiment includes a plurality of glass particles 2, as shown in FIG. Then, by bonding adjacent glass particles 2 to each other, a glass structure 1 in which the glass particles 2 are connected is formed. Furthermore, pores 3 are present between adjacent glass particles 2.

Glass particles 2 contain at least silicon dioxide (SiO ₂ ), calcium oxide (CaO), and diphosphorous pentoxide (P ₂ O ₅ ). Moreover, it is preferable that the glass particles 2 are made of bioglass containing at least SiO ₂ , CaO, and P ₂ O ₅ . Bioglass has the property of bonding to bones in vivo by forming hydroxyapatite on its surface layer. Examples of such bioglasses include SiO 2 -CaO-P ₂ O ₅ consisting of SiO ₂ , CaO and P ₂ O ₅ ; _{SiO 2} -CaO-Na consisting of SiO ₂ , CaO, Na ₂ O and P ₂ O ₅ ; ₂ O-P ₂ O ₅ ; SiO ₂ -CaO-Na 2 O-P ₂ O ₅ -K ₂ O-MgO; SiO consisting of _{SiO 2} , CaO, Na ₂ O, P ₂ O ₅ , K ₂ O and MgO At least one selected from the group consisting of SiO ₂ -CaO-Al ₂ O-P ₂ O ₅ consisting of CaO, _{Al 2} O and P ₂ O ₅ can be used.

Here, the composition ratio of SiO ₂ in the glass particles 2 is preferably 20% by mass or more. Further, the composition ratio of CaO in the glass particles 2 is preferably 20% by mass or more. Further, the composition ratio of P ₂ O ₅ in the glass particles 2 is preferably 50% by mass or less. As described later, adjacent glass particles 2 are bonded via a bonding portion, and the bonding portion further contains fluorine-containing apatite derived from hydroxyapatite (Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ ). ing. Therefore, when the composition ratio of SiO ₂ , CaO and P ₂ O ₅ in the glass particles 2 is within the above range, the production of hydroxyapatite and fluorine-containing apatite derived therefrom can be promoted by the manufacturing method described below. . Note that the glass particles 2 may contain fluorine, if necessary. This can promote the production of fluorine-containing apatite.

Although the average particle diameter of the glass particles 2 constituting the glass structure 1 is not particularly limited, it is preferably 5 nm or more and 10 μm or less, and more preferably 10 nm or more and 0.2 μm or less. When the average particle diameter of the glass particles 2 is within this range, the glass particles 2 are firmly bonded to each other, and the strength of the glass structure 1 can be increased. Furthermore, since the average particle diameter of the glass particles 2 is within this range, the proportion of pores 3 existing inside the glass structure 1 is 15% or less, as will be described later. It becomes possible to increase the strength. In this specification, unless otherwise specified, the value of "average particle diameter" refers to a field of view of several to several tens of fields using an observation means such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM). The value calculated as the average value of the particle diameter of the particles observed in the sample is adopted.

The shape of the glass particles 2 is not particularly limited, but may be, for example, spherical. Further, the glass particles 2 may be polyhedral particles including cubes and rectangular parallelepipeds, whisker-like (acicular) particles, or scale-like particles. Polyhedral particles, whisker particles, or scale particles have higher contact with other particles than spherical particles, so it is possible to increase the strength of the entire glass structure 1.

As described above, the glass structure 1 is composed of a particle group of glass particles 2. That is, the glass structure 1 is composed of a plurality of glass particles 2 mainly made of bioglass, and the glass structure 1 is formed by bonding the glass particles 2 to each other. At this time, the glass particles 2 may be in point contact with each other, or may be in surface contact in which the particle surfaces of the glass particles 2 are in contact with each other.

In the glass structure 1, adjacent glass particles 2 are bonded via bonding portions containing fluorine-containing apatite. As described later, the glass structure 1 can be formed by heating a mixture of glass particles 2 and an aqueous solution containing calcium, phosphorus, and fluorine and having a pH of 4.0 or higher while pressurizing the mixture. can. Then, when the mixture is heated while being pressurized, fluorine-containing apatite is generated on the surface of the glass particles 2, so that adjacent glass particles 2 can be connected to each other by the fluorine-containing apatite.

Here, apatite is originally a mineral name represented by the composition formula: M ₁₀ (ZO ₄ ) ₆ (X) ₂ , but it is also used as a general term for synthetic compounds having this composition. In the composition formula: M ₁₀ (ZO ₄ ) ₆ (X) ₂ , M can be coordinated with at least one of an alkaline earth metal and lead. Furthermore, Z is coordinated with at least one selected from the group consisting of P, As, V, and S, and X is coordinated with at least one selected from the group consisting of F, Cl, Br, OH, O, and _CO3 . Can be done. Therefore, in hydroxyapatite (Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ ), OH ⁻ at the X position can be replaced with F ⁻ , Cl ⁻ or CO ₃ ²⁻ .

As mentioned above, the sintered body of Non-Patent Document 1 contains amorphous hydroxyapatite. However, it is known that hydroxyapatite, especially amorphous hydroxyapatite, has poor acid resistance. Therefore, if the bonding portion consists only of hydroxyapatite, the hydroxyapatite may be dissolved by the acid, and the mechanical strength of the sintered body may be reduced. Therefore, in the glass structure 1 of this embodiment, the bonding portion contains apatite containing fluorine. Fluorine-containing apatite is known to have better acid resistance than hydroxyapatite. Therefore, by including fluorine-containing apatite in the bonding portion, it is possible to improve the acid resistance of the bonding portion and also improve the acid resistance of the entire glass structure. Note that examples of apatite containing fluorine include fluoroapatite (Ca ₁₀ (PO ₄ ) ₆ (F) ₂ ) and (Ca ₁₀ (PO ₄ ) ₆ ((OH) _1-x F _x )) ₂ . can.

As described above, it is preferable that the bonding portion connecting adjacent glass particles 2 contains at least fluorine-containing apatite, and fluorine-containing apatite is the main component. Further, the bonding portion may be a portion made of fluorine-containing apatite. However, as will be described later, the fluorine-containing apatite contained in the bond is generated by replacing OH ^- of hydroxyapatite (Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ ) with F ^- . Therefore, the bonding portion may contain hydroxyapatite in addition to fluorine-containing apatite. Further, as described above, in hydroxyapatite (Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ ), OH ⁻ can be replaced with Cl ⁻ or CO ₃ ²⁻ . Therefore, the bonding portion may include, for example, apatite in which a part of OH ⁻ of hydroxyapatite is replaced with Cl ⁻ or CO ₃ ²⁻ . Furthermore, in addition to apatite, the bonding portion may contain a component derived from the glass particles 2 or a component derived from an aqueous solution containing calcium, phosphorus, and fluorine and having a pH of 4.0 or higher. .

In the joint portion of the glass structure 1, the fluorine-containing apatite may be amorphous or crystalline. Fluorine-containing apatite has better acid resistance than hydroxyapatite, regardless of its crystal structure. However, it is preferable that at least a portion of the fluorine-containing apatite in the bonding portion be crystalline. Crystalline fluorine-containing apatite has higher mechanical strength than amorphous apatite. Therefore, when at least a part of the fluorine-containing apatite contained in the bonded portion is crystalline, the mechanical strength of the bonded portion is increased, so that the mechanical strength of the glass structure 1 can also be improved.

The porosity in the cross section of the glass structure 1 is preferably 15% or less. That is, when observing the cross section of the glass structure 1, it is preferable that the average value of the ratio of pores per unit area is 15% or less. When the porosity is 15% or less, the proportion of glass particles 2 bonding to each other increases, so that the glass structure 1 becomes dense and mechanical strength can be improved. Furthermore, when the porosity is 15% or less, the occurrence of cracks in the glass structure 1 starting from the pores 3 is suppressed, making it possible to increase the bending strength of the glass structure 1. . Note that the porosity in the cross section of the glass structure 1 is more preferably 10% or less, and even more preferably 5% or less. As the porosity in the cross section of the glass structure 1 is smaller, cracks starting from the pores 3 are suppressed, so that the strength of the glass structure 1 can be increased.

In this specification, porosity can be determined as follows. First, the cross section of the glass structure 1 is observed, and the glass particles 2 and pores 3 are determined. Then, the unit area and the area of the pores 3 in the unit area are measured, and the ratio of the pores 3 per unit area is determined. After determining the ratio of pores 3 per unit area at a plurality of locations, the average value of the ratio of pores 3 per unit area is determined as the porosity. Note that when observing the cross section of the glass structure 1, an optical microscope, a scanning electron microscope (SEM), or a transmission electron microscope (TEM) can be used. Further, the unit area and the area of the pores 3 in the unit area may be measured by binarizing an image observed with a microscope.

Although the size of the pores 3 existing inside the glass structure 1 is not particularly limited, it is preferably as small as possible. Since the size of the pores 3 is small, cracks originating from the pores 3 are suppressed, so that the mechanical strength of the glass structure 1 can be increased. Note that the size of the pores 3 of the glass structure 1 is preferably 5 μm or less, more preferably 1 μm or less, and even more preferably 100 nm or less. The size of the pores 3 existing inside the glass structure 1 can be determined by observing the cross section of the glass structure 1 with a microscope, similarly to the porosity described above.

The glass structure 1 only needs to have a structure in which the glass particles 2 are bonded to each other via bonding portions and the porosity is 15% or less. Therefore, the shape of the glass structure 1 is not limited as long as it has such a structure. The shape of the glass structure 1 can be, for example, plate-like, film-like, rectangular, block-like, rod-like, or spherical. Moreover, when the glass structure 1 is plate-shaped or film-shaped, the thickness t is not particularly limited, but can be, for example, 50 μm or more. The glass structure 1 of this embodiment is formed by a pressure heating method, as will be described later. Therefore, a glass structure 1 having a large thickness can be easily obtained. Note that the thickness t of the glass structure 1 can be 1 mm or more, and can also be 1 cm or more. Although the upper limit of the thickness t of the glass structure 1 is not particularly limited, it can be, for example, 50 cm.

As described above, the glass structure 1 of the present embodiment includes a plurality of glass particles 2 containing SiO ₂ , CaO, and P ₂ O ₅ and a bonding portion that bonds the glass particles 2 to each other and contains apatite containing fluorine. , is provided. Further, the porosity of the glass structure 1 is 15% or less. In the glass structure 1, a plurality of glass particles 2 are bonded via bonding portions 4 containing fluorine-containing apatite. Since the fluorine-containing apatite increases the acid resistance of the joint, the acid resistance of the glass structure 1 can also be improved. Furthermore, since the glass structure 1 has a porosity of 15% or less, the glass particles 2 are densely arranged, increasing the mechanical strength of the glass structure 1. Therefore, the glass structure 1 can have high machinability.

Further, in the X-ray diffraction pattern measured with Cu-Kα radiation, the glass structure 1 has a diffraction angle 2θ=25.0° or more and 26.0° or less, 2θ=31.0° or more and 33.0° or less, and , 2θ=39.0° or more and 40.0° or less. When the glass structure 1 is subjected to X-ray diffraction measurement and has a diffraction peak within the above range, the glass structure 1 contains crystalline fluorine-containing apatite. In this case, since the bonded portion contains crystalline fluorine-containing apatite, it is possible to increase the mechanical strength of the glass structure 1.

It is preferable that the glass particles 2 have an apatite-forming ability. As described later, the glass structure 1 can be formed by heating a mixture of glass particles 2 and an aqueous solution containing calcium, phosphorus, and fluorine and having a pH of 4.0 or higher while pressurizing the mixture. can. Therefore, when the glass particles 2 react with the aqueous solution and have the effect of forming apatite, it is possible to efficiently generate bonding parts containing fluorine-containing apatite and firmly bond the glass particles 2 to each other. becomes.

[Method for manufacturing glass structure]
Next, a method for manufacturing the glass structure 1 according to this embodiment will be described. The method for manufacturing the glass structure 1 includes a step of preparing a mixture by mixing a plurality of glass particles 2 and an aqueous solution containing calcium, phosphorus, and fluorine and having a pH of 4.0 or more; It has a step of heating and pressurizing.

The method for manufacturing the glass structure 1 according to the present embodiment is a method that utilizes the so-called biomineralization reaction, which is a biomineral-forming action in which living organisms produce minerals (inorganic compounds) within their own bodies. That is, as described above, since the glass particles 2 contain CaO and P ₂ O ₅ in their components, they have the property of reacting with body fluids and producing apatite on the surface. The manufacturing method of the glass structure 1 utilizes this mechanism and pressurizes the aqueous solution and the glass particles 2 while heating them, thereby causing the aqueous solution and the glass particles 2 to react, thereby containing fluorine-containing apatite derived from hydroxyapatite. forming a joint.

Specifically, first, a mixture is prepared by mixing the glass particles 2 with an aqueous solution containing calcium, phosphorus, and fluorine and having a pH of 4.0 or higher. Although the method for preparing the glass particles 2 containing SiO ₂ , CaO and P ₂ O ₅ is not particularly limited, for example, they can be prepared by a sol-gel method using precursors of SiO ₂ , CaO and P ₂ O ₅ . As a precursor of SiO ₂ , for example, tetraethyl orthosilicate (Si(OC ₂ H ₅ ) ₄ ) can be used. As the CaO precursor, for example, calcium nitrate tetrahydrate (Ca(NO ₃ ) _{2.4H 2} O) can be used. As a precursor of P ₂ O ₅ , for example, diammonium hydrogen phosphate ((NH ₄ ) ₂ HPO ₄ ) can be used.

The average primary particle diameter of the glass particles 2 to be mixed with the aqueous solution is not particularly limited, but is preferably 5 nm or more and 10 μm or less, more preferably 10 nm or more and 0.2 μm or less. When the average particle diameter of the glass particles 2 is within this range, it becomes possible to increase the reactivity with an aqueous solution and easily form a bonding part.

As the aqueous solution containing calcium, phosphorus, and fluorine and having a pH of 4.0 or more, for example, a simulated body fluid containing fluorine can be used. The simulated body fluid is an aqueous solution with an inorganic ion concentration almost equal to that of human extracellular fluid, and by using this solution, reactions on material surfaces in the body can be easily predicted even outside the body. The glass particles 2 containing SiO ₂ , CaO, and P ₂ O ₅ have a property of reacting with the simulated body fluid to generate hydroxyapatite on the surface of the glass particles 2 . Therefore, by using a simulated body fluid as an aqueous solution, hydroxyapatite can be easily produced. An example of the composition of the simulated body fluid is shown in Table 1 along with the composition of human plasma.

Here, the simulated body fluid usually does not contain fluorine. Therefore, in the manufacturing method of the present embodiment, by replacing a part of the chloride ions (Cl ⁻ ) in the simulated body fluid with fluorine ions (F ⁻ ), the simulated body fluid containing fluorine can be prepared as described above. Preferably, it is used as an aqueous solution. An example of the composition of the simulated body fluid containing fluorine is also shown in Table 1.

The amount of the aqueous solution added to the glass particles 2 is preferably such that the biomineralization reaction sufficiently proceeds. The amount of the aqueous solution added is preferably 1 to 200% by mass, more preferably 7 to 100% by mass based on the glass particles 2.

Next, a mixture of glass particles 2 and an aqueous solution is filled into the mold. After filling the mixture into the mold, the mold may be heated if necessary. Then, by applying pressure to the mixture inside the mold, the inside of the mold becomes in a high pressure state. At this time, the glass particles 2 are highly packed, and the particles of the glass particles 2 are bonded to each other, thereby increasing the density. That is, when the mixture formed by mixing the glass particles 2 and the aqueous solution is heated and pressurized, the biomineralization reaction shown in FIG. 2 proceeds.

To explain in detail, as shown in FIGS. 2 and 3(a), when the glass particles 2 come into contact with the aqueous solution 4a, calcium ions (Ca ²⁺ ) are eluted from the glass particles 2 into the aqueous solution 4a, and at the same time, the glass particles 2 A large amount of silanol (Si-OH) groups are generated on the surface. The silanol groups induce heterogeneous nucleation of apatite, while the eluted Ca ²⁺ increases the degree of supersaturation of apatite in the surrounding aqueous solution 4a, promoting the nucleation of apatite. The apatite core thus formed takes in calcium ions and monohydrogen phosphate ions from the surrounding aqueous solution 4a to generate an apatite layer.

Here, OH ⁻ of hydroxyapatite (Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ ) contained in the apatite layer is easily replaced with F ⁻ contained in the simulated body fluid. Therefore, the hydroxyapatite in the apatite layer becomes fluorine-containing apatite, that is, fluoroapatite (Ca ₁₀ (PO ₄ ) ₆ (F) ₂ ).

Thereafter, the apatite layers formed on the surfaces of adjacent glass particles 2 are bonded to each other, so that bonding portions 4 containing fluorine-containing apatite are formed in the necking portions of adjacent glass particles 2, as shown in FIG. 3(b). is formed. Here, by increasing the heating and pressurizing time of the mixture formed by mixing the glass particles 2 and the aqueous solution, crystallization of the fluorine-containing apatite progresses, and the proportion of crystalline fluorine-containing apatite increases. Therefore, by heating and pressurizing the mixture for a predetermined period of time, the bonding portion 4 containing crystalline fluorine-containing apatite can be formed.

Note that the heating and pressurizing conditions for the mixture formed by mixing the glass particles 2 and the aqueous solution are not particularly limited as long as the conditions allow the reaction between the glass particles 2 and the aqueous solution to proceed. For example, it is preferable to pressurize the mixture formed by mixing the glass particles 2 and the aqueous solution with a pressure of 1 MPa while heating the mixture to 40° C. or higher and 300° C. or lower. Furthermore, the time for heating and pressurizing the mixture is preferably 10 minutes or more. Under such conditions, the bonding portion 4 containing fluorine-containing apatite can be easily formed. Note that the pressure when pressurizing the mixture is preferably 1 to 1000 MPa, more preferably 10 to 500 MPa. Further, the time for heating and pressurizing the mixture is preferably 1 minute to 24 hours, more preferably 30 minutes to 12 hours.

Finally, by taking out the molded body from the inside of the mold, a glass structure 1 in which a plurality of glass particles 2 are bonded to each other via bonding portions 4 can be obtained.

As described above, the method for manufacturing the glass structure 1 of the present embodiment includes a plurality of glass particles 2 containing SiO ₂ , CaO, and P ₂ O ₅ , calcium, phosphorus, and fluorine, and a pH of 4.0 or higher. and an aqueous solution to prepare a mixture. The method for manufacturing the glass structure 1 further includes the step of heating and pressurizing the mixture. Note that the temperature when heating the mixture is preferably 40°C or more and 300°C or less. Moreover, it is preferable that the pressure when pressurizing the mixture is 1 MPa or more. Furthermore, the time for heating and pressurizing the mixture is preferably 10 minutes or more. In the manufacturing method of this embodiment, since the glass structure 1 is molded under such low-temperature conditions, energy consumption during manufacturing is reduced, making it possible to suppress manufacturing costs.

[Member with glass structure]
Next, a member including the glass structure 1 according to this embodiment will be explained. The glass structure 1 of this embodiment can be made into a thick plate shape as described above. Further, the glass structure 1 has high mechanical strength, can be cut in the same manner as general ceramic members, and can also be surface-treated. Therefore, the glass structure 1 can be suitably used as a building member. Architectural components are not particularly limited, but include, for example, exterior wall materials (siding), roofing materials, and the like. Furthermore, examples of building materials include road materials and external gutter materials.

Note that hydroxyapatite generally has translucency. Therefore, the glass structure 1 may have translucency at the joint portion 4 . When the bonding portion 4 has translucency, it is possible to improve the design of the entire glass structure.

Hereinafter, the glass structure of this embodiment will be explained in more detail with reference to Examples, but this embodiment is not limited thereto.

[Preparation of test samples 1 to 4]
First, ternary bioglass nanoparticles consisting of SiO ₂ -CaO-P ₂ O ₅ were prepared. Specifically, tetraethyl orthosilicate (Si(OC ₂ H ₅ ) ₄ ), calcium nitrate tetrahydrate (Ca(NO ₃ ) _{2.4H 2} O), and diammonium hydrogen phosphate (( _NH4 ) _{2HPO4 )} was prepared. Next, 9.167 g of tetraethyl orthosilicate and 7.639 g of calcium nitrate tetrahydrate were added to a mixed solution of ultrapure water and ethanol. Note that the ratio of ultrapure water and ethanol in the mixed solution was 2 mol:1 mol. Then, this mixed solution was poured into ultrapure water containing 1.087 g of diammonium hydrogen phosphate, and mixed for 48 hours while adjusting the pH to 11 with aqueous ammonia. Thereafter, the mixed solution was aged for 24 hours and centrifuged to obtain a white gel. Next, the obtained gel was mixed with a 6000 g/mol aqueous polyethylene glycol solution (1% (w/v)) and freeze-dried. Finally, the freeze-dried gel powder was calcined at 700°C to obtain bioglass nanoparticles. As a result of analysis using a transmission electron microscope, the bioglass nanoparticles synthesized by this method had an average primary particle diameter of about 28 nm.

Next, a mixture was obtained by mixing 0.3 g of bioglass nanoparticles and a fluorine-containing simulated body fluid. The fluorine-containing simulated body fluids include distilled water, NaCl, NaHCO ₃ , KCl, K ₂ HPO _{4.3H 2} O, MgCl _{2.6H 2} O, CaCl ₂ , Na ₂ SO ₄ , KF reagents, and pH adjustment reagents. It was prepared by mixing trishydroxymethylaminomethane ((CH ₂ OH) ₃ CNH ₂ ) buffer and 1M hydrochloric acid (HCl) so as to have the composition shown in Table 1. Further, the fluorine-containing simulated body fluid was mixed in an amount of 43% by mass based on the bioglass nanoparticles.

Next, the obtained mixture was placed inside a cylindrical mold having an internal space. Then, the mixture was heated and pressurized at 120° C. and 300 MPa. The heating and pressurizing time was 0.5 hours, 1.0 hours, 2.0 hours, or 6.0 hours. Here, a sample in which the heating and pressurizing time was 0.5 hours was designated as test sample 1, and a sample in which the heating and pressurizing time was set for 1.0 hours was designated as test sample 2. Further, a sample in which the heating and pressurizing time was 2.0 hours was designated as Test Sample 3, and a sample in which the heating and pressurizing time was 6.0 hours was designated as Test Sample 4. In this way, test samples 1 to 4 having different heating and pressurizing times were obtained.

[Preparation of test sample 5]
First, bioglass nanoparticles having an average primary particle diameter of about 28 nm were prepared in the same manner as described above.

Next, a mixture was obtained by mixing 0.3 g of bioglass nanoparticles and a simulated body fluid that did not contain fluorine. The simulated body fluid that does not contain fluorine contains the components shown in Table 1, and was further mixed in an amount of 40% by mass based on the bioglass nanoparticles.

Next, the obtained mixture was placed inside a cylindrical mold having an internal space. Then, the mixture was heated and pressurized under the conditions of 120° C., 300 MPa, and 0.5 hours. In this way, test sample 5 containing no fluorine was obtained.

[evaluation]
(X-ray diffraction measurement)
For test samples 1 to 5 obtained as described above, X-ray diffraction patterns were measured using an X-ray diffraction device. As the X-ray diffraction device, an X-ray diffraction device D8 ADVANCE manufactured by Bruker was used. The X-ray diffraction pattern was measured under the conditions of a tube voltage of 40 kV, a tube current of 40 mA, a diffraction angle 2θ of 10° to 60°, and a step size of 0.02°. FIG. 4(a) shows the X-ray diffraction patterns of test samples 1 to 4 and the X-ray diffraction pattern of fluoroapatite registered as JCPDS 15-0876. Furthermore, FIG. 4(b) shows the X-ray diffraction patterns of test samples 1 to 5.

As shown in FIG. 4(a), in test samples 2 to 4, diffraction peaks derived from fluoroapatite were observed. Specifically, in test samples 2 to 4, in the X-ray diffraction pattern measured with Cu-Kα rays, 2θ = 25.0° or more and 26.0° or less, 2θ = 31.0° or more and 33.0° or less , and diffraction peaks were observed at 2θ=39.0° or more and 40.0° or less. Therefore, it can be seen that test samples 2 to 4 contain crystalline fluoroapatite.

In addition, in test sample 1 in which the heating and pressurizing time was 0.5 hours, no diffraction peak derived from fluoroapatite could be observed. Therefore, it can be seen that test sample 1 does not contain crystalline fluoroapatite.

In addition, from FIG. 4(b), in test sample 5 in which the heating and pressurizing time was 0.5 hours, no diffraction peak derived from fluoroapatite could be observed, and diffraction peaks of other components could also be observed. There wasn't. Therefore, it can be seen that test sample 5 does not contain at least crystalline apatite.

(Relative density measurement)
Relative density was measured for test samples 1-4. Note that the relative density was defined as the value obtained by dividing the density of the test sample measured by the Archimedes method by the density of the bioglass. As a result, the relative density of test sample 1 was 82%, the relative density of test sample 2 was 85%, the relative density of test sample 3 was 88%, and the relative density of test sample 4 was 89%. Ta. In other words, it can be seen that as the heating and pressing time of the test sample increases, the relative density increases and the structure becomes denser.

(scanning electron microscope observation)
First, an amorphous osmium metal coating was formed on the cross sections of test samples 2 to 6 using an osmium plasma coater. As the osmium plasma coater, an osmium plasma coater OPC-60A manufactured by SPI Supplies was used. Next, using a scanning electron microscope (SEM), backscattered electron images of the cross sections of test samples 2 to 6 on which the osmium metal coating was formed were observed. As the scanning electron microscope, an ultra-high resolution field emission scanning electron microscope SU9000 manufactured by Hitachi High-Technologies Corporation was used, and the acceleration voltage was set to 30 keV.

FIG. 5 shows backscattered electron images of test samples 1 to 4, and an enlarged photo is shown in the upper right corner of each photo. Additionally, the relative density of each test sample is shown in the upper left of each photo. From FIG. 5, it can be seen that as the heating and pressurizing time of the test sample becomes longer, the number of pores existing in the cross section of the test sample decreases, and the structure becomes denser.

In addition, the area ratio of the pores was calculated from the backscattered electron images of test samples 1 to 4 in FIG. 5, and the porosity was determined. As a result, the porosity of test samples 1 to 4 was all 15% or less.

(Component analysis using energy dispersive X-ray analysis (EDX))
Elemental analysis was performed on test samples 1 to 5 by energy dispersive X-ray analysis. The energy dispersive X-ray analyzer used was one manufactured by Horiba, Ltd. Table 2 shows the results of elemental analysis for test samples 1 to 5.

As shown in Table 2, test samples 2 to 4 contain fluorine, and as mentioned above, the diffraction peak of fluoroapatite is observed in test samples 2 to 4. It can be seen that the bond includes crystalline fluoroapatite. Furthermore, since test sample 1 also contains fluorine, it is presumed that the bonding portion of test sample 1 contains amorphous fluoroapatite based on the above-mentioned mechanism.

As shown in Table 2, test sample 5 does not contain fluorine, which indicates that the bond does not contain fluoroapatite.

Further, FIG. 6 shows the results of fluorine mapping analysis performed on test samples 1 to 4 by energy dispersive X-ray analysis (EDX). From FIG. 6, it can be seen that fluorine atoms are highly dispersed on the surface of the test samples 1 to 4.

As described above, since test samples 1 to 4 according to the present embodiment contain fluoroapatite which has excellent acid resistance, it can be seen that the glass structures according to test samples 1 to 4 have excellent acid resistance. Furthermore, since Test Samples 2 to 4 contain crystalline fluoroapatite, it can be seen that the mechanical strength of the glass structure is also improved. In addition, as the heating and pressurizing time of the mixture of bioglass nanoparticles and fluorine-containing simulated body fluid increases, the relative density of the glass structure increases and the crystallization of fluoroapatite progresses, which increases the mechanical strength of the glass structure. It can be seen that it also improves.

(Acid resistance test)
An acid resistance test was conducted on test samples 4 and 5. Specifically, test samples 4 and 5 were compared in the amounts of components eluted with respect to acid using the following method.

First, 6 mL of an aqueous hydrochloric acid solution with a concentration of 3% was placed in a plastic container with a capacity of 30 mL, and then each test sample piece was immersed in the aqueous hydrochloric acid solution. After immersing the test sample piece at room temperature for 1 hour, the test sample piece was taken out from the aqueous hydrochloric acid solution.

Next, the solution after taking out the test sample piece was diluted with 18 mL of ion-exchanged water, and calcium (Ca) and phosphorus (P) ions in the solution were measured using inductively coupled plasma emission spectrometry (ICP-AES). The concentration was measured. Then, the amounts of calcium (Ca) and phosphorus (P) eluted from the test sample with respect to the aqueous hydrochloric acid solution were determined. For the ICP-AES measurement, an inductively coupled plasma emission spectrometer iCAP7400 Duo manufactured by Thermo Fisher Scientific was used. Table 3 shows the elution amount of each ion per sample mass in Test Sample 4 and Test Sample 5.

As shown in Table 3, it was found that test sample 4 had a smaller elution amount of each ion than test sample 5. From this, it was found that test sample 4 containing fluorine had higher acid resistance than test sample 5 containing no fluorine.

Although the content of this embodiment has been described above in accordance with the examples, it is obvious to those skilled in the art that this embodiment is not limited to these descriptions, and that various modifications and improvements are possible. be.

1 Glass structure 2 Glass particles 3 Pores 4 Bonding portion 4a Aqueous solution

Claims (10)

a plurality of glass particles containing SiO ₂ , CaO and P ₂ O ₅ ;
A bonding portion that bonds the glass particles to each other and contains apatite containing fluorine;
Equipped with
A glass structure having a porosity of 15% or less. In the X-ray diffraction pattern measured with Cu-Kα rays,
2θ=25.0° or more and 26.0° or less,
2θ=31.0° or more and 33.0° or less, and
The glass structure according to claim 1, containing a crystal phase having a diffraction peak at 2θ=39.0° or more and 40.0° or less. The glass structure according to claim 1 or 2, wherein the composition ratio of SiO ₂ in the glass particles is 20% by mass or more. The glass structure according to any one of claims 1 to 3, wherein the composition ratio of CaO in the glass particles is 20% by mass or more. The glass structure according to any one of claims 1 to 4, wherein the composition ratio _{of P2O5} in the glass particles is 50% by mass or less. The glass structure according to any one of claims 1 to 5, wherein the glass particles have an apatite-forming ability. A step of preparing a mixture by mixing a plurality of glass particles containing SiO ₂ , CaO and P ₂ O ₅ and an aqueous solution containing calcium, phosphorus and fluorine and having a pH of 4.0 or more;
heating and pressurizing the mixture;
A method for manufacturing a glass structure, comprising: The method for manufacturing a glass structure according to claim 7, wherein the temperature at which the mixture is heated is 40°C or more and 300°C or less. The method for manufacturing a glass structure according to claim 7 or 8, wherein the pressure when pressurizing the mixture is 1 MPa or more. The method for manufacturing a glass structure according to any one of claims 7 to 9, wherein the time for heating and pressurizing the mixture is 10 minutes or more.