JP7026904B2 - Ceramic antibacterial materials, antibacterial parts, manufacturing methods of antibacterial parts and ceramic composite materials - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Law "Proceedings of the 2017 PDIII Public Presentation Examination Committee" published by Kanazawa Institute of Technology, February 15, 2018 (issue date)

The present invention relates to a ceramic antibacterial material.

Patients who receive treatment for malignant neoplasms have a markedly weakened physical strength and immunity compared to healthy subjects, and therefore may suffer from infections that occur at the surgical site during surgery. The incidence of such infectious diseases is gradually decreasing due to advances in medical technology and pharmaceuticals, but due to cost concerns, it is still an infectious disease with a high incidence in low- and middle-income countries. Even in high-income countries, it is one of the top infectious diseases among medical-related infectious diseases and is still an important issue. As countermeasures, administration of antibacterial agents and burial of antibacterial materials have been carried out, but long-term use of antibacterial agents may cause the development of resistant bacteria, so there is a limit to their use.

Therefore, in recent years, as a technique for producing an antibacterial effect without using an antibacterial agent, a technique using an antibacterial plate has been devised (see, for example, Patent Document 1, Non-Patent Document 1 and Non-Patent Document 2). This technique creates an antibacterial effect against bacteria on the surface of the plate by forming a specific uneven shape that imitates the scales of shark skin on the surface of the plate without using chemicals.

International Publication No. 17/066265

Reddy et al, "Micropatterned Surfaces for Reducing the Risk of Catheter-Associated Urinary Tract Infection", JOURNAL OF ENDOUROLOGY, Mary Ann Liebert, Inc., September 2011, Volume 25, Number 9, p. 1547-1552 Chung et al, "Impact of engineered surface microtopography on biofilm formation of Staphylococcus aureus", Biointerphases, American Vacuum Society, 29 June 2007, Volume 2, Number 2, p. 89-94

The present invention has been made in view of these circumstances, and an object of the present invention is to provide a new technique having excellent antibacterial properties.

In order to solve the above problems, the ceramic antibacterial material according to an embodiment of the present invention is composed of a sintered body containing silicon nitride and boron nitride.

According to this aspect, it can be used as a material for antibacterial parts having excellent antibacterial properties.

The ceramic antibacterial material may contain 30 to 80% by mass of silicon nitride and 20 to 70% by mass of boron nitride.

The ceramic antibacterial material may further include a sintering aid component. Further, the ceramic antibacterial material may contain silicon nitride in an amount of 27 to 80% by mass, boron nitride in an amount of 17 to 70% by mass, and a sintering aid component in an amount of 3 to 25% by mass. As a result, the strength of the sintered body is increased, and the range of application as an antibacterial material is expanded.

The above-mentioned ceramic antibacterial material may have a surface arithmetic average roughness Ra in the range of 0.2 to 5 μm. More preferably, Ra is in the range of 0.3 to 5 μm. Antibacterial performance can be improved by such minute irregularities on the surface.

Another aspect of the invention is an antibacterial component. This antibacterial component is a component used in a situation where it is necessary to suppress the growth of bacteria, and at least a part of the surface thereof is made of the above-mentioned ceramic antibacterial material. As a result, the portion other than the surface can be made of a relatively inexpensive material other than the ceramic antibacterial material, so that the cost of the antibacterial component can be reduced.

The ceramic antibacterial component may have a plurality of recesses having a depth of 100 μm or more formed on the surface of the ceramic antibacterial component. Thereby, the antibacterial effect can be enhanced.

Yet another aspect of the present invention is a method of manufacturing an antibacterial component. This method is used in the process of sintering a mixture of silicon nitride powder and boron nitride powder in a non-oxidizing atmosphere to prepare a sintered body, and in situations where it is necessary to suppress the growth of bacteria. Includes the process of machining the sintered body into the shape of antibacterial parts.

According to this aspect, antibacterial parts can be efficiently manufactured with a material having a high antibacterial effect.

In the above method for manufacturing an antibacterial component, a plurality of recesses having a depth of 100 μm or more may be formed on the surface of the antibacterial component by machining or laser machining. This makes it possible to manufacture antibacterial parts having a high antibacterial effect.

Yet another aspect of the present invention is a ceramic composite material. This composite material is a mixture of a ceramic antibacterial material powder and at least one or more materials selected from metals, resins, fibers, paper and glass.

According to this aspect, the physical characteristics of the composite material itself, for example, the specific gravity and the strength can be adjusted while exhibiting antibacterial performance.

It should be noted that any combination of the above components and the conversion of the expression of the present invention between methods, devices, systems and the like are also effective as aspects of the present invention. Further, an appropriate combination of the above-mentioned elements may be included in the scope of the invention for which protection by the patent is sought by the present patent application.

According to the present invention, a component having excellent antibacterial properties can be realized.

1 (a) to 1 (e) are schematic views for explaining the method of the antibacterial test. 2 (a) to 2 (e) are views showing surface photographs of each test piece. 3 (a) to 3 (d) are views showing enlarged photographs (50 times to 3000 times) of the surface of Photobert II-k70.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same elements are designated by the same reference numerals, and duplicate description will be omitted as appropriate.

(Manufacturing method of sintered body)
As a result of diligent studies to find ceramics suitable for antibacterial materials, the present inventors have found that sintered bodies containing silicon nitride (Si _{3N 4 )} and boron nitride (BN) are suitable for antibacterial materials. I found it. First, a method for manufacturing a sintered body suitable for a ceramic antibacterial material will be described.

First, a main raw material powder composed of 27 to 80% by mass of silicon nitride and 17 to 70% by mass of boron nitride is mixed with 3 to 25% by mass of a sintering aid component to prepare a raw material powder. This mixing can be performed by, for example, a wet ball mill or the like. Depending on the mass of the sintering aid component, a main raw material powder obtained by mixing 30 to 80% by mass of silicon nitride and 20 to 70% by mass of boron nitride may be used.

Boron nitride has excellent machinability but poor strength characteristics. Therefore, if coarse boron nitride is present in the sintered body, it becomes a fracture starting point and causes chipping and cracking during processing. In order not to form such coarse boron nitride particles, it is effective to make the raw material powder into fine powder. It is desirable to use the main raw material powder, particularly the raw material powder of boron nitride, having an average particle size of less than 1 μm. Boron nitride includes hexagonal (h-BN) low-pressure phase and cubic (c-BN) high-pressure phase, but hexagonal boron nitride is preferable from the viewpoint of free-cutting property. Further, from the viewpoint of processability, it is preferable that the amount of boron nitride is large and the amount of silicon nitride is small. Further, the mechanical strength and Young's modulus increase as the amount of boron nitride decreases and as the amount of silicon nitride increases.

The sintering aid can be selected from those used for sintering silicon nitride and boron nitride. Preferred sintering aids are one or more obtained from oxides of aluminum oxide (alumina), magnesium oxide (magnesia), yttrium oxide (itria), and lanthanoid metals. More preferably, it is a mixture of alumina and ytria, a mixture obtained by further adding magnesia to the mixture, a mixture of ytria and magnesia, and the like. The blending amount of the sintering aid component is preferably in the range of 1 to 25% by mass, particularly 3 to 25% by mass of the total raw material powder.

When the blending amount of the sintering aid component is 1% by mass or more, preferably 3% by mass or more, it becomes easy to densify, and it is possible to suppress insufficient density of the sintered body and deterioration of mechanical properties. On the other hand, when the blending amount of the sintering aid component is 25% by mass or less, the low-strength grain boundary phase is reduced, so that the decrease in mechanical strength and the decrease in workability due to the increase in the grain boundary phase are suppressed. can.

Next, the raw material powder is sintered under high temperature and pressure to obtain a sintered body. This sintering can be performed, for example, by hot pressing. In addition, you may go in an argon atmosphere. The hot press is performed in a non-oxidizing atmosphere such as a nitrogen atmosphere, but may be performed in pressurized nitrogen. The hot press temperature is preferably in the range of 1700 to 1950 ° C. If the temperature is too low, sintering will be insufficient, and if it is too high, thermal decomposition of the main raw material will occur. The pressing force is appropriately in the range of 20 to 50 MPa. The duration of the hot press depends on the temperature and dimensions, but is usually about 1 to 4 hours. High temperature pressure sintering can also be performed by HIP (hot isostatic press). The sintering conditions in this case can also be appropriately set by those skilled in the art.

The obtained sintered body has a coefficient of thermal expansion of 3 × 10 ^-6 / ° C. or less at 25 ° C. to 600 ° C. if the type and amount of the sintering aid are appropriately selected. Since this sintered body has excellent machinability and high strength, it can be processed with high accuracy and is suitable as a material for processed parts having a complicated shape. Then, by processing this sintered body with an appropriate grinding wheel or a drill, a ceramic processed part having a predetermined shape can be manufactured. Further, by further slitting or drilling a ceramic processed part using a grinding wheel or a drill, an uneven pattern (a plurality of recesses such as slits, grooves, holes, etc.) can be formed on the surface of the part.

The recess is, for example, a quadrangle having one side of the opening of 10 to 100 μm and a depth of 100 μm or more. Further, a plurality of recesses are formed in a matrix shape. The distance between adjacent recesses is, for example, about 10 to 50 μm. The width of the grooves and slits is, for example, about 50 to 2000 μm.

The use of the ceramic processed parts thus produced is not particularly limited, but is useful as parts used in situations where it is necessary to suppress the growth of bacteria, such as parts to be placed in a living body, surgical instruments, and sanitary equipment parts.

[Example]
Hexagonal boron nitride (h-BN) powder having an average particle size of 0.5 μm and silicon nitride powder having an average particle size of 0.2 μm were mixed. Yttria and magnesia were added to this mixed powder (main raw material powder) as sintering aids, and ball mill mixing was performed using ethyl alcohol as a solvent. The obtained slurry was dried to obtain a raw material powder.

This raw material powder was filled in a graphite die and hot-press sintered at 1800 ° C. for 1 hour while applying a pressure of 30 MPa in a nitrogen atmosphere to obtain a ceramic sintered body. Then, in order to confirm whether the obtained ceramic sintered body is suitable for an antibacterial material, the following two experiments were performed.

(Antibacterial test)
(1) Test method Compliant with JIS Z 2801 "Antibacterial processed product-Antibacterial test method / antibacterial effect" (2) Contents FIGS. 1 (a) to 1 (e) are for explaining the antibacterial test method. It is a schematic diagram. First, the plate-shaped test piece 10 to be evaluated for antibacterial property is placed on a petri dish 12. Then, Staphylococcus aureus or Escherichia coli (test bacterial count 0.4 mL) is added dropwise to the petri dish 12 together with the culture solution 13 (FIG. 1 (a)). The amount of the culture solution is adjusted so that the surface of the test piece 10 is immersed. In that state, the petri dish 12 is placed in the incubator 14 and cultured at 35 ° C. for 24 hours (FIG. 1 (b)).

Then, only the culture solution 15 is taken out from the petri dish 12 (FIG. 1 (c)), transferred to another petri dish 16, placed in the incubator 14 again, and cultured at 35 ° C. for 24 hours (FIG. 1 (d)). Then, the number of bacteria in the petri dish 16 taken out from the incubator 14 is measured (FIG. 1 (e)).

(3) Test pieces FIGS. 2 (a) to 2 (e) are views showing surface photographs of each test piece. The test pieces are the following five.
Fig. 2 (a) hBN-containing silicon nitride based ceramics (Si ₃ N ₄ -hBN: "Photoval II-k70" manufactured by Fellow Tech Ceramics Co., Ltd.), flat surface, surface roughness Ra = 0.35 μm
FIG. 2 (b) hBN-containing silicon nitride-based ceramics (same as above), patterning surface (lattice width 21 ± 1 μm, square hole side 50 ± 2 μm, depth 160 ± 10 μm), surface roughness Ra = 0.46 μm
Fig. 2 (c) Silicon nitride based ceramics (Si ₃ N ₄ : "HPSN606" manufactured by Fellow Tech Ceramics Co., Ltd.), flat surface, surface roughness Ra = 0.19 μm
Fig. 2 (d) Silicon nitride based ceramics (same as above), patterning surface (lattice width 21 ± 1 μm, square hole side 50 ± 2 μm, depth 160 ± 10 μm) Surface roughness Ra = 0.19 μm
FIG. 2 (e) Titanium alloy (Ti-6Al-V), flat surface, surface roughness Ra = 0.04 μm

3 (a) to 3 (d) are views showing enlarged photographs of the surface of Photobert II-k70. As shown in FIGS. 3 (c) and 3 (d), the surface of the Photovale II-k70 has very fine irregularities. The composition of Photober II-k70 is 38.5% by mass of boron nitride, 54.1% by mass of silicon nitride, 5.5% by mass of yttrium, and 1.9% by mass of magnesia.

(4) Evaluation Results Table 1 shows the antibacterial properties of each test piece against Staphylococcus aureus or Escherichia coli.

As shown in Table 1, when the test bacterium is Staphylococcus aureus, the test pieces (material Si ₃ N ₄ -hBN) according to Examples 1 and 2 are after culturing regardless of whether the surface morphology is flat or patterned. In the petri dish 16 of the above, the number of bacteria was 0. Further, in the test pieces (material Si ₃ N ₄ ) according to Reference Examples 1 and 2, the number of bacteria was 0 in the petri dish 16 after culturing, regardless of whether the surface morphology was flat or the pattern surface. On the other hand, the test piece (material titanium alloy) according to the comparative example having a flat surface morphology had a bacterial count of 1740 in the petri dish 16 after culturing. Therefore, against staphylococci, hBN-containing silicon nitride-based ceramics and silicon nitride-based ceramics showed antibacterial properties regardless of the surface morphology of the test piece.

Further, as shown in Table 1, when the test bacterium is Escherichia coli, the test pieces (material Si ₃ N ₄ -hBN) according to Examples 1 and 2 are after culturing regardless of whether the surface morphology is flat or patterned. In the petri dish 16 of the above, the number of bacteria was 0. In addition, the test piece (material Si ₃ N ₄ ) according to Reference Example 2 whose surface morphology is a patterned surface also had 0 bacteria in the petri dish 16 after culturing. On the other hand, the test piece (material Si ₃ N ₄ ) according to Reference Example 1 having a flat surface had a bacterial count of 113 in the petri dish 16 after culturing. In addition, the test piece (material titanium alloy) according to the comparative example having a flat surface morphology had a bacterial count of 40 in the petri dish 16 after culturing. Therefore, the hBN-containing silicon nitride-based ceramics showed antibacterial properties against Escherichia coli regardless of the surface morphology of the test piece. Further, against Escherichia coli, silicon nitride-based ceramics having a patterned surface showed antibacterial properties.

In addition, the inventors of the present application have come up with the idea that, in addition to the difference in the pattern, which is one of the surface morphologies, the arithmetic mean roughness Ra of the surface of the ceramic antibacterial material also affects the antibacterial property. The ceramic antibacterial material according to the present embodiment has a structure containing silicon nitride (Si _{3N 4 )} and boron nitride (h-BN), and has a structure containing boron nitride (h-BN). In cutting and grinding), a minute uneven surface having an arithmetic average roughness Ra of about 0.2 to 5 μm is formed due to the dropout of boron nitride (see FIGS. 3 (a) to 3 (d)). It is considered that the antibacterial performance is improved by the action of such a minute uneven surface against the fungus.

As described above, based on the results of the antibacterial test described above, the ceramic antibacterial material composed of a sintered body containing silicon nitride and boron nitride, which is an example of Hotval II-k70, is a material for antibacterial parts having excellent antibacterial properties. Can be used for.

Further, the nitride-based ceramic antibacterial material may further include a sintering aid component such as Hotval II-k70. As a result, the strength of the sintered body is increased, and the range of application as an antibacterial material is expanded.

(Antibacterial parts)
The antibacterial component according to the present embodiment is a component used in a situation where it is necessary to suppress the growth of bacteria. Examples of antibacterial parts include parts (artificial bones) to be placed in a living body, surgical instruments, sanitary equipment (devices used in baths, toilets, washrooms, etc.) and the like. At least a part of the surface of these antibacterial parts is made of the above-mentioned ceramic antibacterial material. As a result, the portion other than the surface can be made of a relatively inexpensive material other than the ceramic antibacterial material, so that the cost of the antibacterial component can be reduced.

The antibacterial component may have a plurality of recesses having a depth of 100 μm or more formed on the surface thereof. Thereby, the antibacterial effect can be enhanced.

In addition, by using a ceramic antibacterial material as a part to be placed in the living body, there is no artifact in CT imaging or heat generation in MRI imaging compared to the case where a metal material is used, and even if it is embedded in the human body, it is postoperative. The affected area can be inspected. It is also effective in suppressing postoperative infectious diseases.

In addition, since the ceramic sintered body containing silicon nitride and boron nitride has high strength and high machinability (free-cutting property), complicated micromachining is possible, and the shape when replacing a part of the human body is possible. Good compatibility. In addition, when burying in the human body, it is possible to adjust the shape on the spot according to the individual physique and the place of application.

(Manufacturing method of ceramic biomaterial)
As described above, in the method for producing an antibacterial component according to the present embodiment, a mixture of silicon nitride powder, boron nitride powder, and a powder containing a sintering aid component is mixed in a non-oxidizing atmosphere. It includes a step of sintering to produce a sintered body and a step of machining the sintered body into the shape of an antibacterial component used in a situation where it is necessary to suppress the growth of bacteria. Since the ceramic sintered body containing silicon nitride and boron nitride has high strength and high machinability (free-cutting property), complicated micromachining is possible. Therefore, antibacterial parts can be efficiently manufactured with high accuracy using a material having a high antibacterial effect.

The method for manufacturing an antibacterial component may further include a step of forming a plurality of recesses having a depth of 100 μm or more on the surface of the antibacterial component by machining or laser machining. This makes it possible to manufacture antibacterial parts having a high antibacterial effect.

(Ceramic composite material)
Another aspect of this embodiment is a ceramic composite material. This composite material is a mixture of a ceramic antibacterial material powder and at least one or more materials selected from metals, resins, fibers, paper and glass. Thereby, the physical characteristics of the composite material itself, for example, the specific gravity and the strength can be adjusted while exhibiting the antibacterial performance.

Although the present invention has been described above with reference to the above-described embodiments and examples, the present invention is not limited to the above-described embodiments, and the configurations of the respective embodiments are appropriately combined or substituted. This is also included in the present invention. Further, it is also possible to appropriately rearrange the combinations and the order of processes in the embodiment based on the knowledge of those skilled in the art, and to add modifications such as various design changes to the embodiments, and such modifications are added. The embodiments described above may also be included in the scope of the present invention.

10 test pieces, 12 petri dishes, 13 cultures, 14 incubators, 15 cultures, 16 petri dishes.

Claims (8)

Consists of a sintered body containing silicon nitride and boron nitride ,
The arithmetic average roughness Ra of the surface is in the range of 0.2 to 5 μm.
It contains 30 to 80% by mass of the silicon nitride and contains 30 to 80% by mass.
A ceramic antibacterial material containing 20 to 70% by mass of boron nitride . It is composed of a sintered body containing silicon nitride, boron nitride and a sintering aid component.
The arithmetic average roughness Ra of the surface is in the range of 0.2 to 5 μm.
It contains 27 to 80% by mass of the silicon nitride and contains
Containing 17 to 70% by mass of the boron nitride,
A ceramic antibacterial material containing 3 to 25% by mass of the sintering aid component . An antibacterial component used in a situation where it is necessary to suppress the growth of bacteria, wherein at least a part of the surface thereof is made of the ceramic antibacterial material according to claim 1 or 2 . The antibacterial component according to claim 3 , wherein a plurality of recesses having a depth of 100 μm or more are formed on the surface. A process of sintering a mixture of silicon nitride powder and boron nitride powder in a non-oxidizing atmosphere to prepare a sintered body, and
The process of machining the sintered body into the shape of antibacterial parts used in situations where it is necessary to suppress the growth of bacteria, and
Including
The arithmetic average roughness Ra of the surface of the sintered body is in the range of 0.2 to 5 μm.
A method for producing an antibacterial component in which the sintered body contains 30 to 80% by mass of the silicon nitride and 20 to 70% by mass of the boron nitride . A process of producing a sintered body by sintering a mixture of silicon nitride powder, boron nitride powder and a sintering aid component in a non-oxidizing atmosphere.
The process of machining the sintered body into the shape of antibacterial parts used in situations where it is necessary to suppress the growth of bacteria, and
Including
The arithmetic average roughness Ra of the surface of the sintered body is in the range of 0.2 to 5 μm.
A method for producing an antibacterial component, wherein the sintered body contains 27 to 80% by mass of the silicon nitride, 17 to 70% by mass of the boron nitride, and 3 to 25% by mass of the sintering aid component. The method for manufacturing an antibacterial component according to claim 5 or 6 , further comprising a step of forming a plurality of recesses having a depth of 100 μm or more on the surface of the antibacterial component by machining or laser machining. A ceramic composite material in which the powder of the ceramic antibacterial material according to claim 1 or 2 and at least one or more materials selected from metals, resins, fibers, paper and glass are mixed.

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