JP2006225453A - Medical equipment and medical material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide medical equipment and a medical material using an aliphatic polyester resin composition whose mechanical strengths such as tensile modulus and bending modulus sre improved by irradiation with an ionizing radiation and which has excellent biodegradability. <P>SOLUTION: The medical equipment and the medical material involve a resin composition obtained by irradiating the mixture of a biodegradable aliphatic polyester resin and a nanocarbon material with an ionizing radiation. Specifically, the ionizing radiation is electron beams or γ rays and the nanocarbon material has a spiral cylindrical structure with a 6 membered carbon ring as the main structure. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a medical device and a medical material using a biodegradable aliphatic polyester resin composition having high mechanical strength.

Since medical devices and medical materials are used in an environment where body fluid such as blood and urine adheres, they should be single-use plastic disposable items, and the waste should be carefully disposed of by incineration, It is necessary to prevent infection by viruses and bacteria. However, such a disposable action leads to an increase in the amount of waste and causes an increase in the amount of carbon dioxide discharged by the incineration process.
Biodegradable resins, on the other hand, are decomposed into carbon dioxide and water by microorganisms that exist in nature after the product life cycle, and as a material with low environmental impact, agricultural materials and civil engineering construction materials Applications are expected to expand into various fields such as industrial materials. Above all, biodegradable resin produced from plant-derived raw materials is characterized by the fact that the amount of carbon dioxide does not change as a whole (carbon neutral) because carbon dioxide discharged during disposal is absorbed during plant growth. It has attracted attention from the viewpoint of suppressing global warming.
Examples of the plant-derived biodegradable resin include a biodegradable aliphatic polyester resin, more specifically, a polylactic acid resin as a relatively hard resin, and a polybutylene succin as a flexible resin. Examples thereof include nate-based resins, and copolymers, blends, and alloys of these.
The use of these biodegradable resins as resins used for medical devices and medical materials that are commonly used for disposables is very useful because it can reduce the burden on the environment.
However, these biodegradable aliphatic polyester resins have lower heat resistance, mechanical strength, and molding processability than general-purpose resins such as polyethylene and polypropylene. It is essential to improve physical properties by design and addition of modifiers. In particular, improvement of mechanical strength is an important examination subject when the biodegradable aliphatic polyester resin is used as a housing of a medical device.
Conventionally, as a means for improving the heat resistance and mechanical strength of a resin, intermolecular crosslinking of the resin by irradiation with ionizing radiation has been used. Also in biodegradable aliphatic polyester resins, it is known that intermolecular crosslinking occurs with poly (ε-caprolactone) by ionizing radiation, and a technique capable of improving heat resistance is disclosed (for example, see Patent Document 1). ). In addition, biodegradable aliphatic polyester resins that do not cause intermolecular crosslinking alone, such as polylactic acid, or that do not easily cause intermolecular crosslinking, such as polybutylene succinate and copolymers thereof, are highly reactive monomers and Techniques for improving the crosslinking rate by adding a crosslinking accelerator such as an inorganic compound have been disclosed (see, for example, Patent Document 2 and Patent Document 3).
In order to obtain a high crosslinking rate of these resins using ionizing radiation, there are a method of increasing the irradiation amount of ionizing radiation and a method of increasing the addition amount of a crosslinking accelerator. However, when the amount of ionizing radiation is increased, the polymer chain may be excessively cleaved by radicals, and the expected improvement in mechanical strength may not be obtained. Problems such as a decrease in manufacturing efficiency due to the occurrence of such a problem also occur. On the other hand, when the addition amount of the crosslinking accelerator is increased, problems such as an increase in the residual amount of unreacted monomer, an increase in cost, and a decrease in biodegradability occur. Moreover, the improvement in the crosslinking rate does not always contribute directly to the improvement in strength.
JP2003-051215A. JP2003-277593. JP2003-313214A.

  The present invention has been made in view of such problems, medical treatment using an aliphatic polyester resin composition excellent in biodegradability by improving mechanical strength such as tensile elastic modulus and bending elastic modulus by irradiation with ionizing radiation. The object is to provide tools and medical materials.

  As a result of intensive studies by the present inventors, when biodegradable aliphatic polyester resin containing nanocarbon material is cross-linked by irradiation with ionizing radiation, interaction between biodegradable aliphatic polyester resin and nanocarbon material occurs. As a result of this, it was found that the effect of improving the mechanical strength of the biodegradable aliphatic polyester resin composition was greater than when no nanocarbon material was contained, and the present invention was completed.

Such an object is achieved by the present inventions (1) to (9) below.
(1) It has a resin composition obtained by irradiating a mixture of a biodegradable aliphatic polyester resin and a nanocarbon material having a graphite layer having a carbon 6-membered ring as a main structure with ionizing radiation.

  (2) The ionizing radiation is an electron beam or γ-ray.

  (3) The nanocarbon material has a helical cylindrical structure made of a graphite sheet having a carbon 6-membered ring as a main structure.

  (4) The nano carbon material has a length of 0.01 μm to 2000 μm.

  (5) The outer diameter of the nanocarbon material is 0.4 nm to 300 nm.

  (6) The dose of the ionizing radiation is 1 to 100 kGy.

  (7) The biodegradable aliphatic polyester resin is polybutylene succinate, a copolymer containing polybutylene succinate, and a polymer blend or polymer alloy containing at least one of the polymers. And

  (8) The nanocarbon material content of the nanocarbon material is 0.1 wt% to 50 wt%.

  (9) Mixing a biodegradable aliphatic polyester resin and a nanocarbon material, then molding the mixture into a desired shape, assembling the molded product as necessary, and then irradiating the assembly with ionizing radiation. It is characterized by.

  The medical device and the medical material having the biodegradable aliphatic polyester resin composition of the present invention can further reduce the content of the inorganic mixture for improving the strength, and with a small addition amount of the crosslinking accelerator, The mechanical strength can be greatly improved by irradiation with ionizing radiation.

Hereinafter, the medical device and medical material of the present invention will be described in detail.
A medical device means a machine / equipment used for surgery, treatment, or diagnosis of the human body or animal. Specifically, it is listed in Class 10 of the Trademark Law Enforcement Regulations Schedule (Ministry of Economy, Trade and Industry Ordinance No. 202) There are things that are in the range. In addition, medical materials are used for the distribution and use of pharmaceuticals and medical devices such as packaging materials and accessories for pharmaceuticals and medical devices, and are discarded along with the use of the pharmaceuticals and medical devices. Means what will be done. The drug means a drug used for surgery, treatment, or diagnosis of a human body or an animal, and specifically, there are those listed in the fifth category of the same table. It is particularly suitable for injection needles, puncture needles, packaging trays, and the like that require high strength. Further, it is also used in general households and is suitable for body fluid testing tools such as disposable blood testing tools and urine testing tools.

  The medical device and the medical material of the present invention have a composition composed of a biodegradable aliphatic polyester resin and a nanocarbon material, and the cross-linked structure formed at the time of ionizing radiation irradiation and the nanocarbon material Compared with the case where it does not contain a nanocarbon material, the effect of improving the mechanical strength of the resin composition is large. That is, when the ionizing radiation dose is equal, the mechanical strength of the composition of the present invention is greater than the strength of the biodegradable aliphatic polyester resin composition not containing the nanocarbon material. As a result, it is possible to reduce the amount of ionizing radiation necessary for obtaining the required mechanical strength and the amount of crosslinking accelerator added.

  The nanocarbon material used in the medical device and medical material of the present invention is basically biologically safe because it is composed of only carbon atoms, and after the biodegradable aliphatic polyester resin composition is decomposed. However, it does not contain toxic substances and heavy metals that have adverse effects such as soil contamination and biological growth inhibition, and it does not burden the environment. Furthermore, since the resin can be reinforced to some extent by simply mixing the nanocarbon material, greater mechanical strength can be obtained, and the moldability of the composition can be improved.

  The biodegradable aliphatic polyester resin that can be used in the present invention is not particularly limited, but preferably a polybutylene succinate, a polybutylene succinate-adipate copolymer, a polybutylene succinate-carbonate copolymer, Polybutylene succinate / polylactic acid copolymer, poly (ε-caprolactone), polylactic acid, poly (3-hydroxybutyrate) and its copolymer, polyethylene succinate / polybutylene succinate / terephthalate copolymer, poly Examples thereof include a butylene adipate / terephthalate copolymer, a polytetramethylene adipate / terephthalate copolymer, a polybutylene succinate / adipate / terephthalate copolymer, and a polymer blend or a polymer alloy thereof.

  The nanocarbon material that can be used in the present invention means a carbon fiber having a graphite layer having a carbon 6-membered ring structure as a main structure. The carbon fiber having such a structure is generally called a carbon fiber, a carbon nanotube, or the like, and can take any shape such as a needle shape, a spiral shape, and a cylindrical shape. Further, the nanocarbon material is not limited to being dispersed alone, but may be an aggregate formed of several.

  Specifically, the carbon fiber having a graphite layer having a carbon 6-membered ring as a main structure, specifically, a carbon fiber having a helical cylindrical structure made of a graphite sheet having a carbon 6-membered ring structure as a main structure (generally “carbon” A carbon fiber having a multiple structure formed of a helical structure made of graphite having a carbon 6-membered ring structure as a main structure, and the end of the fiber ends in a conical shape. Examples thereof include graphite fibers having a structure (generally also referred to as “carbon nanohorn”). The carbon nanotube may have a single-layered cylindrical structure (for example, a carbon fiber described in Japanese Patent No. 2526782) or the like, and has a multiple structure in which cylindrical shapes formed in a spiral structure are arranged concentrically. (For example, carbon fiber described in Nature, 354, 56 (1991), Japanese Patent No. 2687794, etc.) may be used. When a carbon nanotube is used as the carbon fiber, a range of a preferable outer diameter of the carbon fiber described later can be satisfied, which is preferable as the carbon fiber of the present invention.

  The carbon nanohorn may have a multi-layer structure in which one layer or two or more layers are stacked (for example, carbon fiber described in Japanese Patent No. 2705447). Moreover, the thing of the aggregate | assembly (for example, Unexamined-Japanese-Patent No. 2002-159851 etc.) with the square cylindrical structure turned toward the outer side may be sufficient. These carbon nanohorns are also preferable as the carbon fibers of the present invention, like the carbon nanotubes.

  The carbon fiber preferably has a length of 0.01 μm to 2000 μm. Within such a length range, there is no secondary aggregation due to the entanglement of the carbon fibers, and it can be uniformly dispersed together with the biodegradable aliphatic polyester resin in the composition. In particular, when the length of the carbon fiber is 1 μm to 50 μm, the carbon fiber is appropriately entangled with the crosslinked structure formed by the biodegradable aliphatic polyester resin by irradiation with ionizing radiation, thereby improving the mechanical strength. Therefore, it is more preferable.

  The outer diameter of the carbon fiber is preferably 0.4 nm to 300 nm. More preferably, it is 0.4 nm to 200 nm. Since carbon fibers having an outer diameter in this range can be obtained in a high yield in a known production method, they are easily available commercially and have appropriate flexibility. For example, polybutylene succinate and Even when a highly biodegradable aliphatic polyester resin such as a copolymer is used, the mechanical strength can be improved while maintaining the flexibility of the original resin appropriately, which is preferable. is there.

  The above-described carbon fiber can be produced by a known carbon fiber production method (for example, Takashi Yoshida, “Basics of Carbon Nanotubes and Forefront of Industrialization”, first edition, NTS Corporation, 2002 1). 11th, p. 6-18, JP 2003-238130 A). In general, arc discharge methods (JP-A-6-157016, JP-A-2000-95509), laser evaporation methods (JP-A-10-273308, etc.), catalytic vapor phase growth methods (JP-A-2000-86217). Gazette), hydrothermal synthesis method (Non-Patent Document Carbon Vol. 36, No. 7-8, pp. 937-942, 1988 (Yury G. Gogotsi et al., Non-Patent Document Journal of Materials Research Society, Vol. 15). No. 12, pp. 2591-2594, 2000 (Yury G. Gogotsi et al.), Journal of American Chemical Society Vol. 123, No. 4, pp. 741-742, 2001 (Jose Maria) Calderon et al.), JP2003-221217A, JP2002-37614A) and the like are often used.

In addition, as the nanocarbon material, a substance called fullerene in which a structure in which 60 or more carbon atoms are strongly bonded to form a spherical shape or a tube shape can be used.
The nanocarbon material does not necessarily have to be as manufactured, and may be subjected to treatment such as heat treatment, fragmentation treatment, oxidation treatment, chemical modification treatment, and the like. By applying these treatments, defects occur in the carbon 5-membered ring or 6-membered ring structure constituting the nanocarbon material, and functional groups are introduced into the outer surface or inner surface, or metal is introduced into the inner space of the nanocarbon material. And can contain substances such as organic compounds. When a nanocarbon material subjected to these treatments is used, the adhesion between the nanocarbon material and the biodegradable aliphatic polyester resin is increased, and the mechanical strength of the resulting biodegradable aliphatic polyester resin composition is increased. It is preferable because it becomes larger. Moreover, since interaction with a biodegradable aliphatic polyester resin at the time of ionizing radiation irradiation becomes strong, it is preferable.

  A cross-linking accelerator may be added to the biodegradable aliphatic polyester resin composition of the present invention in order to form a cross-linked structure. Examples of crosslinking accelerators include triallyl cyanurate, trimethallyl cyanurate, triallyl isocyanurate, trimethallyl isocyanurate, diallyl adipate, diallyl succinate, diallyl malonate, diallyl carbonate, diallyl oxalate, diallyl fumarate Examples thereof include rate, diallyl malate, diallyl phthalate, diallyl isophthalate, diallyl terephthalate, pentaerythritol triacrylate, ethylene glycol dimethacrylate, and the like. Preferred crosslinking accelerators are triallyl cyanurate and triallyl isocyanurate.

  The concentration of the crosslinking accelerator in the biodegradable aliphatic polyester resin composition is 10% by weight or less, and preferably 0.1% by weight to 5% by weight. More preferably, it is 0.1 to 3% by weight.

  In the biodegradable aliphatic polyester resin composition of the present invention, an antioxidant, a pigment, a softener, a plasticizer, a lubricant, an antistatic agent, an antifogging agent, a coloring agent, an antioxidant (anti-aging) Agent), a heat stabilizer, a light stabilizer, an ultraviolet absorber and the like, and may contain one kind or two or more kinds.

  The biodegradable aliphatic polyester resin composition of the present invention is a first step in which a biodegradable aliphatic polyester resin and a nanocarbon material are mixed to prepare a composition, and the composition obtained in the first step is desired. It is manufactured by the second step of forming into a shape.

The first step includes a step of mixing the biodegradable aliphatic polyester resin and the nanocarbon material, if necessary, other additives and the like under dry or wet conditions (mixing step), and, if necessary, mixing the mixture. It consists of the process (preparation process) shape | molded by melt-kneading extrusion etc.
In the first step, a known method can be used as the mixing method, and it is desirable that the mixing is performed uniformly in a dry or wet manner. For example, a method of mixing using a mixing device such as a dispersion mixing stirrer can be used.

  In the mixing step, the biodegradable aliphatic polyester resin used is preferably a powder. In the mixing step, when the biodegradable aliphatic polyester resin is a powder, the nanocarbon material can be uniformly dispersed, crosslinking during radiation irradiation is likely to occur, and mechanical strength can be improved. When the average particle size of the powder is 1 μm to 150 μm, the production is relatively easy, the nanocarbon material is easily dispersed uniformly, and the biodegradable aliphatic polyester resin and the nanocarbon material are appropriately entangled. Therefore, it is preferable.

  A method for preparing the biodegradable aliphatic polyester resin into a powdery biodegradable aliphatic polyester resin is not particularly limited, but it is preferably prepared by a mechanical pulverization method or a chemical pulverization method. In the present specification, as the mechanical pulverization method, for example, the polymer is cooled with liquefied nitrogen, and the mechanically pulverized powder is classified using a shock freezing pulverizer, etc. And a method of obtaining a powder having a particle size range of The chemical pulverization method is a method using a principle generally called spinodal decomposition (for example, see JP-A-4-339828). For example, a biodegradable aliphatic polyester resin is heated and dissolved and mixed in an appropriate solvent. Thereafter, the powder deposited by cooling is washed, dried, crushed, classified, and the like to obtain a powder having a predetermined particle size range. In addition, the powdery biodegradable resin obtained by this method has a smooth surface and a spherical shape. Therefore, the powdery biodegradable resin is easily entangled with the nanocarbon material, and it is convenient for the resulting composition to achieve an appropriate mechanical strength. Good. When these pulverization methods are used, a powdery biodegradable resin having a preferable average particle diameter of 1 μm to 150 μm of the present invention can be prepared for many biodegradable resins.

The content of the nanocarbon material relative to the total weight of the biodegradable aliphatic polyester resin and the nanocarbon material in the composition of the present invention (hereinafter, also simply referred to as “nanocarbon material content”) is 0.1 weight. % To 50% by weight is preferred. When the nanocarbon material content is less than 0.1% by weight, the interaction between the intermolecular crosslinks generated during the ionizing radiation irradiation of the biodegradable aliphatic polyester resin composition and the nanocarbon material becomes insufficient, and the machine If the mechanical strength cannot be improved and is greater than 50% by weight, it may be difficult to form the target shape. More preferably, it is 0.1 to 40% by weight.
The preparation step is not particularly limited. For example, the mixture mixed in the mixing step is melt-kneaded using a biaxial kneader to obtain a biodegradable aliphatic polyester resin, a nanocarbon material, and other additives. It is a step of preparing the contained composition into a pellet shape. The shape of the composition is not limited to pellets, and those obtained in the mixing step may be used directly or may be powders.

The second step is a step of molding the composition containing the biodegradable aliphatic polyester resin and the nanocarbon material obtained in the first step into a molded product having a target shape. The molding method is not particularly limited, and examples thereof include a compression molding method, an injection molding method, an extrusion molding method, and a blow molding method.
The second step may include an assembly step in which the molded product is combined with another molded product made of the same or other material as necessary to form a medical device or an assembly of medical materials. The assembling method is not particularly limited, and examples thereof include fitting, adhesion, and fusion.

  By irradiating the molded product obtained in the second step with ionizing radiation, cross-linking occurs in the molded product, and the mechanical strength is improved. In particular, the tensile modulus and the flexural modulus are improved, so that the biodegradable aliphatic polyester resin composition of the present invention can be used as a housing for medical devices.

  The dose of the ionizing radiation to be irradiated is not particularly limited, but is 1 to 500 kGy, preferably 5 kGy to 100 kGy. When the dose of ionizing radiation is 10 kGy to 70 kGy, sterilization and mechanical strength can be improved at the same time, which is convenient in production and is more preferable. It is desirable to select a crosslinking accelerator and set the addition amount so that the desired mechanical strength can be obtained with a dose in this range.

  As the type of ionizing radiation to be irradiated, an electron beam, γ-ray, X-ray, or the like can be used. However, since industrial production is easy, an electron beam by an electron accelerator and γ-ray from cobalt-60 are preferable. More preferably, an electron beam is used. The electron accelerator is preferably a medium energy to high energy electron accelerator having an acceleration voltage of 1 MeV or higher in order to enable irradiation of a molded product having a thickness.

The irradiation atmosphere of ionizing radiation is not particularly limited, but may be performed under an inert atmosphere or air except for air. By irradiating under an inert atmosphere or under vacuum, it is possible to suppress the active species generated by the irradiation from being deactivated when combined with oxygen in the air, thereby reducing the crosslinking efficiency. Moreover, although the temperature at the time of irradiation may be any, it is typically performed at room temperature.
The crosslinked structure in the biodegradable aliphatic polyester resin composition of the present invention may be between the biodegradable aliphatic polyester resins or between the biodegradable aliphatic polyester resin and the nanocarbon material.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these Examples.

(1) Production of polybutylene succinate sheet Polybutylene succinate pellets (Bionore # 1001, manufactured by Showa Polymer Co., Ltd.) were pulverized by a mechanical pulverization method to prepare polybutylene succinate powder. Specifically, the polybutylene succinate pellets were cooled with liquefied nitrogen and the powdered polybutylene succinate pulverized with an impact-type freeze pulverizer (manufactured by Nippon Oxygen Co., Ltd.) was sieved with an appropriate opening sieve. Classification was performed to obtain a polybutylene succinate powder having an average particle size of 100 μm.
4.5 kg of this polybutylene succinate powder and 0.5 kg of multi-layered cylindrical carbon fiber (VGCF, Showa Denko KK, average length of about 20 μm, average outer diameter of about 100 nm) And mixed to obtain a composition powder (nanocarbon material content of 10% by weight) in which these were uniformly mixed. This was melt kneaded at a temperature of 200 ° C. and a rotation speed of 60 rpm using a biaxial kneader (S1KRC kneader, manufactured by Kurimoto Steel Co., Ltd.) to obtain composition pellets. The obtained composition pellets were pressed at a temperature of 200 ° C. and a pressure of 20 MPa using a desktop heat press machine (SA-303, manufactured by Tester Sangyo Co., Ltd.) and then rapidly cooled, 150 mm wide, 150 mm long, thick The sheet was formed into a sheet having a thickness of 0.5 mm.

(2) Irradiation of ionizing radiation The sheet obtained in (1) above was irradiated with an electron beam of 66 kGy using a 10 MeV electron accelerator in air at room temperature to obtain a material sheet for a packaging tray.

  A sheet produced by the same method as in Example 1 (1) was irradiated with γ-rays of 50 kGy from cobalt-60 at room temperature in the air to obtain a material sheet for a packaging tray.

  A material sheet for the packaging tray was prepared in the same manner as in Example 1 except that the nanocarbon material content was 30% by weight.

  A material sheet for the packaging tray was produced in the same manner as in Example 2 except that the nanocarbon material content was 30% by weight.

(Comparative Example 1) A material sheet for a packaging tray was prepared in the same manner as in Example 1 except that no ionizing radiation was applied.
(Comparative Example 2) A material sheet for a packaging tray was prepared in the same manner as in Example 3 except that no ionizing radiation was applied.
(Comparative Example 3) A material sheet for a packaging tray was produced in the same manner as in Example 1 except that the nanocarbon material was not used.
(Comparative Example 4) A material sheet for a packaging tray was produced in the same manner as in Example 2 except that the nanocarbon material was not used.

(Comparative Example 5) A packaging tray was prepared in the same manner as in Example 1 except that 3.5 kg of polybutylene succinate powder and 1.5 kg of talc (talc content of 30% by weight) were used instead of the nanocarbon material. A material sheet was prepared.
(Comparative Example 6) A packaging tray was prepared in the same manner as in Example 2 except that 3.5 kg of polybutylene succinate powder and 1.5 kg of talc (talc content 30 wt%) were used instead of the nanocarbon material. A material sheet was prepared.
(Comparative Example 7) A sheet was prepared in the same manner as in Example 1 except that the nanocarbon material content was set to 70% by weight. However, the composition pellets could not be prepared, and the sheet was manufactured. could not.

Preparation of polylactic acid sheet Polylactic acid pellets (Lacty # 9010, manufactured by Shimadzu Corporation) were pulverized by a chemical pulverization method to prepare polylactic acid powder. Specifically, polylactic acid pellets and xylene (domestic chemical special grade I158791) were placed in a dissolution tank so that polylactic acid was 5% by weight, and heated and dissolved at 80 to 120 ° C. while stirring slowly. When the solution became transparent, heating was stopped, and the solution was gradually cooled to room temperature to precipitate polylactic acid fine particles. This solution was filtered to collect polylactic acid fine particles and washed with water, and then the solvent was completely volatilized at 65 ° C. or lower with a stirring vacuum dryer. The obtained powdery polylactic acid was classified with an appropriate sieve, and powdery polylactic acid powder having an average particle size of 100 μm was obtained.

4.75 kg of this polylactic acid powder and 0.25 kg of carbon nanotubes having a single-layer cylindrical structure as a nanocarbon material (Single Walled carbon nanotubes, manufactured by Strem Chemical Co., Ltd., average length of about 1 μm, outer diameter of 4 to 30 nm) And 0.05 kg of triallyl cyanurate were mixed using a dispersion mixing stirrer to obtain a composition powder (nanocarbon material content 5% by weight) in which these were uniformly mixed. This was melt kneaded at a temperature of 180 ° C. and a rotation speed of 80 rpm using a biaxial kneader (S1KRC kneader, manufactured by Kurimoto Steel Co., Ltd.) to obtain composition pellets. The obtained composition pellets were pressed at a temperature of 220 ° C. and a pressure of 20 MPa using a desktop heat press machine (SA-303, manufactured by Tester Sangyo Co., Ltd.) and then rapidly cooled, 150 mm wide, 150 mm long, thick The sheet was formed into a sheet having a thickness of 0.5 mm.
The obtained sheet was irradiated with an electron beam in the same manner as in Example 1 to obtain a material sheet for a packaging tray.

(Comparative Example 8) A material sheet for a packaging tray was produced in the same manner as in Example 5 except that the electron beam was not irradiated.
(Comparative Example 9) A material sheet for a packaging tray was produced in the same manner as in Example 5 except that the nanocarbon material was not used.

(Evaluation)
(Measurement of cross-linking ratio (gel fraction)) About the material sheets of the packaging trays prepared in Examples 1 and 3 and Comparative Examples 3 and 5, a predetermined amount was wrapped in a 200-mesh stainless steel wire mesh and chloroform (special grade, Kanto Chemical) Soxhlet extraction was performed with 100 mL for 24 hours. The insoluble matter (gel formed by crosslinking) remaining in the wire net was taken out and dried at 50 ° C. for 24 hours using an oven, and then its weight was determined. The gel fraction was calculated using the following formula:
Gel fraction (%) = (gel weight excluding dissolved components) / (initial dry weight) × 100
Table 1 shows the gel fraction of each sheet. It was confirmed that there was no increase in the crosslinking rate due to the addition of the nanocarbon material.

(Tensile test) After using the material sheet of the packaging tray produced in Examples 1-5 and Comparative Examples 1-6, 8, 9 to produce a 5B type dumbbell test piece shown in ISO 527-2 with a punching die A tensile test was carried out using an autograph (AG-10, manufactured by Shimadzu Corporation) at a test speed of 1 mm / min, and the tensile modulus was measured.

(Bending test) After the material sheet of the packaging tray produced in Examples 1-5 and Comparative Examples 1-6, 8, and 9 was cut into a length of 50.8 mm and a width of 12.7 mm, Autograph (AG-10) , Manufactured by Shimadzu Corporation), a three-point bending test was performed under the conditions of a support base diameter of 5 mm, an indenter diameter of 10.7 mm, a distance between fulcrums of 25.4 mm, and a test speed of 2 mm / min. It was measured.
The evaluation results are shown in Table 2. In the biodegradable aliphatic polyester compositions containing the nanocarbon materials of Examples 1 to 5, as the nanocarbon material content increases, the mechanical strength of the compositions by ionizing radiation irradiation, particularly tensile modulus and flexural elasticity An increase in rate was observed.

Claims (9)

A medical device or medical device comprising a resin composition obtained by irradiating a mixture of a biodegradable aliphatic polyester resin and a nanocarbon material having a graphite layer having a carbon 6-membered ring as a main structure with ionizing radiation material. The medical device or medical material according to claim 1, wherein the ionizing radiation is an electron beam or a γ-ray. The medical device or medical material according to claim 1 or 2, wherein the nanocarbon material has a helical cylindrical structure made of a graphite sheet having a carbon 6-membered ring as a main structure. The medical device or medical material according to claim 1, wherein a length of the nanocarbon material is 0.01 μm to 2000 μm. The medical device or medical material according to claim 1, wherein an outer diameter of the nanocarbon material is 0.4 nm to 300 nm. The medical device or medical material according to claim 1, wherein a dose of the ionizing radiation is 1 to 100 kGy. The biodegradable aliphatic polyester resin is polybutylene succinate, a copolymer containing polybutylene succinate, and a polymer blend containing at least one of the polymers, or a polymer alloy. The medical device or medical material described. The medical device or medical material according to claim 1, wherein the nanocarbon material has a nanocarbon material content of 0.1 wt% to 50 wt%. A biodegradable aliphatic polyester resin and a nanocarbon material are mixed, and then a molded product is formed into a desired shape from the mixture, and an assembly is assembled using the molded product as necessary, and then the molded product or the assembled product is assembled. Irradiating ionizing radiation to a medical device or method for producing a medical material