JP2011245708A - Laser marking method and marked member to be buried in living body - Google Patents

Abstract

The present invention relates to a method for applying a marking to a resin base material for biomaterials that has sufficient visibility and does not adversely affect the human body using a general-purpose Nd: YAG laser or Nd: YVO ₄ laser. A marked synthetic resin member for living body implantation is provided.
[MEANS FOR SOLVING PROBLEMS] After applying a powder of a material that is not harmful to the living body and that can promote a discoloration reaction of the substrate by irradiating laser light to the substrate, the laser light is applied to the surface of the substrate coated with the powder. A method characterized by irradiation, and a marked biological implant member.
[Selection] Figure 1

Description

  The present invention relates to a method for applying laser marking to a resin substrate for biomaterials and a marked bioimplantable member.

Marking information such as a manufacturing date, a manufacturing place, a manufacturing company name, and a lot number on a product is widely performed in various technical fields. For example, Patent Document 1 describes an apparatus for applying laser marking to edible bodies such as tablets and capsules. Laser marking, which is performed by irradiating a material with laser light, is a marking technique generally used for marking various materials and products. The advantage of laser marking is that marking can be performed at high speed while changing the information to be marked, and a marking excellent in durability and friction resistance can be obtained. Nd: YAG laser (YAG laser) and Nd: YVO ₄ laser having a laser beam wavelength of 1064 nm or 532 nm are generally used for laser marking on materials such as metals, ceramics, and silicon.

Biomaterials refer to materials that are implanted and used in living organisms, but marking products such as serial numbers on products that use them, such as artificial joints, is extremely important from the standpoint of preventing product mix-ups. is important. The marking on a biomaterial is required not to adversely affect the living body and to have high visibility. Laser marking is suitable for metal and ceramic biomaterials, and is widely used. However, laser marking on polyethylene substrates used as artificial joints is currently very difficult. Nd: YAG laser and Nd: YVO ₄ laser, which are generally used in laser marking devices, have a laser beam wavelength of 1064 nm or 532 nm. When this laser beam is irradiated onto a polyethylene substrate, sufficient visibility is achieved. It is not possible to obtain markings with This is probably because the absorbance of the polyethylene substrate in the vicinity of these wavelengths is small. Although it is possible to obtain highly visible markings by adding pigments with high absorbance in the wavelength region of laser light to the substrate, substances such as pigments can adversely affect the human body, so addition to the substrate Should be avoided as much as possible.

  On the other hand, it is known that a highly visible marking can be obtained by irradiating a polyethylene substrate with laser light in the ultraviolet region. For example, when laser light having a wavelength of 355 nm is irradiated onto HDPE (high density polyethylene) by a laser system for ultraviolet light marking SAMURAI manufactured by Reacher Systems Co., Ltd., a highly visible marking can be obtained. However, in order to perform ultraviolet laser marking, it is necessary to introduce a dedicated device, which is problematic in terms of cost. Moreover, the safety | security with respect to the biological body of the marked member is not confirmed. Therefore, it is required to establish a laser marking technique that does not require a special device and that does not adversely affect the living body.

JP 2008-126309 A

Reacher Systems Co., Ltd. website, [April 30, 2010 search] (URL: http://www.rayture-sys.co.jp/processing/samurai_hdpe.html)

Method and marking capable of applying marking to a biomaterial resin base material with sufficient visibility and without fear of adversely affecting the human body using a general-purpose Nd: YAG laser or Nd: YVO ₄ laser A synthetic resin member for living body implantation is provided.

That is, the present invention is a method for applying a laser marking to a resin base material for biomaterials, and uses a powder of a material that has no biological harm and can accelerate the discoloration reaction of the base material by irradiating laser light. The present invention relates to a method for irradiating the surface of a substrate coated with the above powder with a laser beam after coating, and a marked biological implant member.

  When the laser marking method of the present invention is used, a laser-implanted biological implant member that has sufficient visibility and does not adversely affect the human body can be obtained.

FIG. 1 shows a laser marking result of Example 1 of the present invention. FIG. 2 shows a laser marking result of Example 2 of the present invention. FIG. 3 shows the laser marking result of Example 3 of the present invention. FIG. 4 shows a laser marking result of a comparative example of the present invention.

  Examples of the resin base material for biomaterials that can be marked by the method of the present invention include, for example, polymethyl methacrylate resin, polytetrafluoroethylene, polyethylene, crosslinked polyethylene, polyurethane, polydimethylsiloxane, polyoxymethylene, polyethylene terephthalate, polyvinyl Alcohol etc. are mentioned. Since the laser marking obtained by the method of the present invention has no fear of adversely affecting the human body, it is suitable for marking on biomaterials, medical materials, etc., especially polyethylene base materials (including cross-linked polyethylene) used as components of artificial joints. ing. Using the method of the present invention, in addition to the materials listed above, it is possible to mark materials that are difficult to mark with a laser beam having a wavelength of about 1064 nm or 532 nm, that is, a material having a low absorbance in the wavelength region of about 1064 nm or 532 nm. Can be applied.

  The powder for coating used in the method of the present invention is a powder of a material that is not harmful to living organisms and that can promote the discoloration reaction of the substrate by irradiating laser light, preferably using a general-purpose laser marking device. I just need it. The above powder is a substance that causes a reaction such as heating or catalysis by the laser beam of a laser marking device, and specifically, biocompatibility such as titanium oxide, zirconium oxide, aluminum oxide, tantalum oxide, hydroxide apatite, etc. High ceramic powder is preferred. In particular, titanium oxide having a particle size suitable for coating is relatively easily available. As a method of applying to the base material, the powder may be applied directly to the base material. However, in order to uniformly apply a powder having a necessary and sufficient thickness, a suspension in which the powder is dispersed in an appropriate liquid is used. It is preferable. The suspension (dispersion) may be applied to the substrate with a spatula or a brush, or the substrate may be dipped in a large amount of dispersion and pulled up. The titanium oxide dispersion is obtained by dispersing titanium oxide as a dispersoid in a dispersion medium. Titanium oxide may be any of a rutile type, anatase type or brookite type. The particle size of titanium oxide is preferably 0.01 to 1000 μm, particularly preferably 0.1 to 100 μm. Examples of the dispersion medium suitable for the method using the dispersion include water, ethanol, methanol, isopropanol, and acetone. Isopropanol is preferable from the viewpoint of cost and good workability such as low volatility and low toxicity. Two or more types mentioned above may be combined to form a dispersion medium. The dispersion medium is preferably mixed with a powder such as titanium oxide to form a stable dispersion. In order to stabilize the dispersion, a small amount of additives such as thickeners and surfactants may be added. The concentration of the titanium oxide dispersion used in the method using the dispersion is preferably 1 to 30% by weight, particularly preferably 1 to 10% by weight. An excessively high concentration is not preferable because a stable dispersion cannot be obtained.

The wavelength of the laser beam used in the method of the present invention is preferably 520 to 540 nm. A general-purpose Nd: YAG laser or Nd: YVO ₄ laser can be used as the laser light source in the method of the present invention. It is preferable to use a wavelength of 532 nm, which is the second harmonic of each laser. The higher the intensity of the laser light source, the easier the marking can be done in a short time, but it is usually 1.0 to 10.0 W, preferably 1.5 to 2.5 W, and more preferably 1.9 W. The pulse frequency and marking speed are appropriately adjusted according to the coating powder and the substrate. When titanium oxide powder is applied to a polyethylene substrate, the preferred pulse frequency is 10,000 to 30,000 Hz, and the marking speed is 1 to 10 mm / s.

  When the substrate is irradiated with laser light, the discoloration reaction of the substrate at the irradiated site is promoted by the catalytic action of titanium oxide. As a result, a highly visible marking consisting of a black or brown discoloration having a color tone different from that of the original substrate is obtained. After the marking is completed, the applied excess powder is removed with an appropriate liquid such as water or alcohol. Since a material having biocompatibility is used, there is no problem even if a very small amount of powder remains in the marking portion.

[Example 1]
Titanium oxide (W-10 manufactured by Ishihara Sangyo Co., Ltd., anatase type, average particle size: 0.15 μm) was dispersed in isopropanol (manufactured by Sasaki Chemical Co., Ltd.) to prepare a 1 wt% titanium oxide dispersion. . The polyethylene substrate was immersed in this dispersion for 3 hours, and then the substrate was naturally dried. Using a laser marking device (Rofin RSM 10E / SHG manufactured by Roffin), the polyethylene substrate was marked under the following marking conditions. The marking results are shown in FIG.
<Marking conditions>
・ Wavelength: 532nm
・ Output intensity: 1.9W
・ Pulse frequency: 19000Hz
・ Marking speed: 4mm / s

[Example 2]
Laser marking was performed on the polyethylene substrate in the same manner as in Example 1 except that the concentration of the titanium oxide dispersion was changed to 5% by weight. The marking results are shown in FIG.

[Example 3]
Laser marking was performed on the polyethylene substrate in the same manner as in Example 1 except that the concentration of the titanium oxide dispersion was 10% by weight. The marking results are shown in FIG.

[Comparative example]
(No titanium oxide immersion)
Laser marking was performed on the polyethylene substrate under the same marking conditions as in Example 1 without immersing in the titanium oxide dispersion. The marking results are shown in FIG.

The visibility of the obtained laser marking was confirmed visually. The markings of Examples 1 to 3 could be easily identified with the naked eye and had good visibility. On the other hand, the marking in the comparative example in which the base material is not immersed in the titanium oxide dispersion is almost indistinguishable with the naked eye, and is clearly inferior in visibility as compared with the markings in Examples 1 to 3. It was. The visibility of marking is summarized in Table 1.

  The laser marking obtained by using the method of the present invention has no risk of adversely affecting the living body and has excellent visibility.

Claims (10)

  A method of applying a laser marking to a resin base material for a biomaterial, in which after applying a powder of a material capable of accelerating a discoloration reaction of the base material by irradiating a laser beam, the laser light is applied to the base on which the powder is applied. A method characterized by irradiating the material surface.   The method according to claim 1, wherein the laser light has a wavelength of 520 to 540 nm.   The method according to claim 1 or 2, wherein the intensity of the laser light source is 1.7 to 2.0 W.   The method according to any one of claims 1 to 3, wherein the powder is a ceramic powder having high biocompatibility, such as titanium oxide, zirconium oxide, aluminum oxide, tantalum oxide, and hydroxide apatite.   The method according to claim 4, wherein the powder is a titanium oxide powder.   The method according to claim 1, wherein the powder is suspended in a liquid and applied to the substrate as a dispersion.   The method according to claim 6, wherein the dispersion medium of the dispersion is one liquid selected from water, ethanol, methanol, isopropanol, and acetone, or a mixture of two or more liquids.   The method according to claim 6 or 7, wherein the concentration of the dispersion is 1 to 30% by weight.   The method according to claim 1, wherein the biomaterial resin base material is polyethylene.   A biological implant member having a surface marked by the method according to claim 1.