Titanium alloy

Abstract

To provide a titanium alloy having high mechanical properties, which has bacteriostatic action and processability while being applicable to dental prostheses and medical devices.SOLUTION: A titanium alloy contains Ag of 3-25 mass%, Nb of 0.5-30 mass%, and Cu of 0.1-7.5 mass%, with the balance being Ti.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a titanium alloy, and more particularly to a titanium alloy characterized by its use as a dental prosthesis or a medical device. [Background technology]

[0002] In medical settings, applications that primarily involve direct contact with living organisms require that materials minimize their impact on the body. To address this, highly biocompatible materials with low cytotoxicity and allergenicity, such as precious metals and titanium alloys, have traditionally been used. However, in addition to the effects of the materials themselves on the body, it has been pointed out that biofilms formed by bacteria and exopolysaccharides on the surface of materials during use in the body can cause various diseases, and conventional materials have been insufficient in preventing biofilm formation. For this reason, titanium-silver alloys with biofilm adhesion and growth inhibitory properties (hereafter referred to as bacteriostatic properties) have been proposed.

[0003] Patent Document 1 discloses a titanium-silver alloy that has antibacterial properties that can suppress the formation of biofilms that can have harmful effects on the living body while suppressing the impact on the normal bacterial flora in the oral cavity by adding silver to the titanium to control the surface properties of the metal. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2010-121153 Summary of the Invention [Problem to be solved by the invention]

[0005] However, although the titanium-silver alloy described in Patent Document 1 has the processability to be processed into any shape required for dental technology and medical device manufacturing, and maintains bacteriostatic properties over the long term, there is room for improvement in its mechanical properties when applied to dental prostheses and medical devices such as guide wires, stents, implants, etc. Mechanical properties are particularly important for large dental prostheses such as dentures and bridges that are subject to large loads due to occlusion, and materials that combine bacteriostatic properties, processability, and high mechanical properties are required.

[0006] Therefore, an object of the present invention is to provide a titanium alloy that has antibacterial properties and workability, as well as high mechanical properties that can be used for dental prostheses and medical devices. [Means for solving the problem]

[0007] As a result of extensive research, the inventors have developed a titanium alloy that combines Ti, Ag, Nb, and Cu in an optimal composition range, which not only has antibacterial properties and workability, but also has high mechanical properties.

[0008] That is, the above-mentioned object is achieved by a titanium alloy comprising 3 to 25 mass% Ag, 0.5 to 30 mass% Nb, 0.1 to 7.5 mass% Cu, and the balance Ti. This titanium alloy can be used, for example, as a material for dental prostheses and as a material for medical devices. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a titanium alloy that has bacteriostatic properties and processability, as well as high mechanical strength required for dental prostheses and medical devices such as guide wires, stents, and implants. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail.

[0011] The present invention is a titanium alloy characterized by containing 3 to 25 mass% Ag, 0.5 to 30 mass% Nb, 0.1 to 7.5 mass% Cu, and the balance being Ti.

[0012] Addition of Ag to an alloy imparts antibacterial properties. If the amount of Ag added is less than 3 mass%, the antibacterial properties are poor, while if it exceeds 25 mass%, the elongation becomes insufficient. The preferred amount is 4 to 23 mass%.

[0013] Adding Nb and Cu simultaneously to a TiAg alloy makes it possible to improve hardness and yield strength while maintaining antibacterial properties. Adding Nb alone does not improve hardness or yield strength, and adding only Cu in the amount necessary to improve hardness and yield strength significantly reduces workability.

[0014] When Nb and Cu are added simultaneously, if the amount of Nb added is less than 0.5 mass%, sufficient workability cannot be obtained, and if it exceeds 30 mass%, the yield strength becomes insufficient. The amount of Nb added is preferably 0.7 to 27 mass%, more preferably 3 to 17 mass%. On the other hand, if the amount of Cu added is less than 0.1 mass%, sufficient hardness and yield strength cannot be obtained, and if it exceeds 7.5 mass%, workability becomes insufficient.The preferred amount is 0.3 to 6 mass%. [Example]

[0015] The present invention will be described in the following examples, but the manufacturing method is not limited to these embodiments.

[0016] The alloy compositions of the examples and comparative examples are shown in Table 1. The raw materials of Ti, Ag, Nb, and Cu were weighed and mixed to obtain the compositions shown in Table 1, and then melted by arc melting in an argon atmosphere to produce each alloy ingot.

[0017] The produced ingots were hot forged, then hot rolled, and then heat treated to produce plates having a thickness of 2 mm (Examples 1 to 10, Comparative Examples 1 to 3).

[0018] The sheets of each alloy prepared were evaluated as follows, and the results are shown in Table 2.

[0019] Workability was evaluated by processing from ingot to 2 mm thick plate material. Alloys from which 2 mm thick plate material could be obtained are marked with a 〇, and alloys from which 2 mm thick plate material could not be obtained due to cracking during processing are marked with an × in Table 2. For alloys marked with an × for workability, test specimens could not be prepared, and the columns for the evaluation of antibacterial properties and each mechanical property are marked with a "-".

[0020] Bacteriostatic properties were evaluated using the following biofilm adhesion test. First, test specimens measuring 2 mm thick, 15 mm long, and 10 mm wide were cut from the test material. The sterilized specimens were immersed in a container containing a sucrose-containing complex liquid medium, and Streptococcus mutans, a bacterium simulating oral biofilm formation, was added and anaerobically cultured for a specified period of time. The specimens were then transferred to a container containing water and washed. The attached biofilm was then collected with a spatula and suspended in a specified amount of water. The biofilm volume was calculated from the turbidity. The smaller the biofilm volume, the better the bacteriostatic properties of the material. The bacteriostatic properties were evaluated as follows: A 10% or greater reduction in biofilm volume for the alloy compared to pure Ti material was marked with a 'Good'; a 10% or less reduction (including an increase in biofilm volume) was marked with a 'No'. Table 2 shows the evaluation of bacteriostatic properties.

[0021] Hardness was measured using a micro-Vickers hardness tester using test pieces 2 mm thick, 15 mm long, and 10 mm wide cut from the test material under conditions of a load of 200 gf and a holding time of 10 seconds. The results are shown in Table 2. Hardness was evaluated as follows: ⊚ if it was 300 HV or higher, ◯ if it was less than 300 HV and 270 HV or higher, and × if it was less than 270 HV.

[0022] The yield strength was measured at room temperature in the atmosphere at a crosshead speed of 1.5 mm / min using test pieces 2 mm thick, 50 mm long, and 3 mm wide cut from the test material. Comparative Example 1 was set as 100%, and the relative yield strengths of the Examples and other Comparative Examples relative to the yield strength of Comparative Example 1 are shown in Table 2. The yield strength ratio was evaluated as follows: ⊚ if it was 120% or more; ◯ if it was less than 120% and 110% or more; and × if it was less than 110%, and the results are shown in Table 2.

[0023] The elongation was determined from the butt joint elongation of the test piece after the tensile test. The elongation was evaluated based on the properties required for Type 5 (devices requiring high rigidity and high strength) of JIS T 6123 (non-precious metal materials for fixed dental restorations), and was evaluated as ◯ if the elongation was 2% or more, and × if the elongation was less than 2%. The results are shown in Table 2.

[0024] [Table 1]

[0025] [Table 2]

[0026] These results demonstrate that the alloys produced by the present invention possess both bacteriostatic properties and workability, as well as the mechanical properties required for dental prostheses and medical devices. Therefore, the present invention makes it possible to provide titanium alloys suitable for use in medical settings.

Claims

1. A titanium alloy characterized by containing 3-25 mass% Ag, 0.5-30 mass% Nb, 0.1-7.5 mass% Cu, and the balance Ti, having a hardness of 270 HV or more, an elongation of 2% or more, and having antibacterial properties.

2. The titanium alloy according to claim 1, characterized in that it is used for dental prostheses.

3. The titanium alloy according to claim 1, characterized in that it is used for medical devices.

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