JP2024067471A - Joints and composite materials using polyether ether ketone resin - Google Patents

Abstract

The present invention provides a bonded body and a composite material between PEEK resin and a metal oxide, in which the adhesive strength between the PEEK resin and the metal oxide is high and interfacial failure is unlikely to occur.
[Solution] The bonded body is a bonded body in which a polyether ether ketone resin and a metal oxide are bonded together, and the relative difference between the spacing between benzene rings constituting the molecular chain of the polyether ether ketone resin and the spacing between metal atoms constituting the crystal structure of the metal oxide is 5% or less, and the atomic density of the crystal plane of the metal oxide to which the polyether ether ketone resin is bonded is 17 atoms/ ^nm2 or more. The composite material is a composite material containing a metal oxide with a polyether ether ketone resin as a base material, and the relative difference between the spacing between benzene rings constituting the molecular chain of the polyether ether ketone resin and the spacing between metal atoms constituting the crystal structure of the metal oxide is 5% or less.
[Selected figure] Figure 2

Description

The present invention relates to a joint and composite material between polyetheretherketone (PEEK) resin and metal oxide.

Among thermoplastic resins, PEEK resin is a resin with high thermal stability and low reactivity, and is resistant to deterioration. It also has excellent mechanical properties, chemical resistance, water resistance, etc., and is known as a material with high flame retardancy and biocompatibility. Because of these excellent properties, PEEK resin has attracted attention as a medical material that comes into contact with biological tissue, a material for vehicles such as automobiles, and aerospace materials.

In the medical field, PEEK resin is used as a material for implants, including interbody cages, artificial joints, and internal fixation devices for fractures. Generally, the surface of PEEK resin is coated with titanium oxide or hydroxyapatite to improve its binding to bone tissue. Patent Document 1 describes a method of coating the surface of medical PEEK resin with titanium and forming a thin film of titanium oxide on the titanium surface.

Composite materials have also been developed in which fillers are dispersed in a matrix formed from PEEK resin. Fiber Reinforced Plastics (FRP), which is made by embedding carbon fibers or glass fibers in epoxy resin or phenolic resin, is known as a lightweight composite material with high strength and elasticity. By using thermoplastic PEEK resin instead of thermosetting resin, it is expected that moldability and recyclability will be improved.

Patent Document 2 describes a porous PEEK resin suitable for implants and a method for producing the same. It is said that bioactive ceramics can be mixed into this PEEK resin as particles. Examples of bioactive ceramics include tricalcium phosphate, hydroxyapatite, and biphasic calcium phosphate. Another known technology is to disperse titanium oxide in the base material to improve ultraviolet resistance.

US Patent Application Publication No. 2021/0079532 US Patent Application Publication No. 2012/0323339

PEEK resin has excellent heat resistance, mechanical properties, chemical resistance, water resistance, etc., so it is used as a bonded body with other materials bonded to its surface, such as when coating with titanium oxide, or as a composite material with other materials dispersed in the base material. However, PEEK resin has the problem that it is difficult to bond or composite with other materials.

Since PEEK resin has high thermal stability and low reactivity, it is difficult to bond it using chemical adsorption or to chemically modify it to improve its bondability. When other materials are bonded to the surface of PEEK resin, or when other materials are dispersed in a base material formed from PEEK resin, application of an external force can easily cause separation between the PEEK resin and the metal oxide due to interface destruction.

Therefore, the present invention aims to provide a joint and composite material between PEEK resin and metal oxide that has high adhesion strength between the PEEK resin and metal oxide and is less susceptible to interfacial failure.

In order to solve the above problems, the bonded structure of the present invention is a bonded structure in which a polyether ether ketone resin and a metal oxide are bonded together, wherein a relative difference between a distance between benzene rings constituting a molecular chain of the polyether ether ketone resin and a distance between metal atoms constituting a crystal structure of the metal oxide is 5% or less, and an atomic density of the crystal plane of the metal oxide to which the polyether ether ketone resin is bonded is 17 atoms/ ^nm2 or more.

The composite material according to the present invention is a composite material containing a metal oxide and a polyether ether ketone resin as a base material, and the relative difference between the distance between the benzene rings constituting the molecular chain of the polyether ether ketone resin and the distance between the metal atoms constituting the crystal structure of the metal oxide is 5% or less.

The present invention can provide a bonded body and composite material between PEEK resin and metal oxide that has high adhesion strength between the PEEK resin and metal oxide and is less susceptible to interfacial failure.

FIG. 1 is a cross-sectional view illustrating an example of a bonded body according to an embodiment of the present invention. FIG. 1 is a cross-sectional view showing a typical example of use of a bonded body according to an embodiment of the present invention. FIG. 1 is a cross-sectional view illustrating an example of a bonded body according to an embodiment of the present invention. FIG. 1 is a cross-sectional view illustrating an example of a composite material according to an embodiment of the present invention. FIG. 2 is a perspective view showing a metal oxide dispersed in the composite material according to the embodiment of the present invention. FIG. 13 is a graph showing the results of an analysis of the relationship between the proportion of (110) faces in the total surface area of titanium oxide and the yield strength of a composite material. FIG. 13 is a graph showing the analysis results of the relationship between the ratio of (001) faces in the total surface area of aluminum oxide and the yield strength of a composite material. FIG. 13 is a graph showing the analysis results of the relationship between the ratio of (111) faces in the total surface area of magnesium oxide and the yield strength of a composite material. FIG. 1 is a cross-sectional view illustrating an example of a composite material according to an embodiment of the present invention. FIG. 13 is a diagram showing the results of an analysis of the atomic arrangement of a PEEK resin that does not use a metal oxide. FIG. 13 is a diagram showing the results of an analysis of the atomic arrangement of a PEEK resin using titanium oxide. FIG. 13 is a diagram showing the results of an analysis of the atomic arrangement of PEEK resin using aluminum oxide. FIG. 13 is a diagram showing the results of an analysis of the atomic arrangement of PEEK resin using magnesium oxide.

The following describes an embodiment of the present invention, a bonded body and a composite material of polyether ether ketone (PEEK) resin and a metal oxide, and a method for manufacturing the same, with reference to the drawings. In the following drawings, common components are designated by the same reference numerals, and duplicated descriptions are omitted.

Figure 1 is a cross-sectional view showing an example of a joint according to an embodiment of the present invention. Figure 2 is a cross-sectional view showing an example of a use of a joint according to an embodiment of the present invention. Figures 1 and 2 show an intersomatic cage as an example of a joint in which PEEK resin and metal oxide are joined. Figure 2 shows a cross-sectional view of the human spine and its surroundings in which the intersomatic cage is used.

In Figures 1 and 2, reference numeral 1 denotes a joint forming an interbody cage, reference numeral 2 denotes PEEK resin, reference numeral 3 denotes a metal oxide, reference numeral 4 denotes a vertebral body, reference numeral 5 denotes an intervertebral disc, reference numeral 6 denotes bone marrow, and reference numeral 101 denotes an interface between the PEEK resin and the metal oxide.

As shown in FIG. 1, the bonded body 1 according to this embodiment has a structure in which PEEK resin 2 and metal oxide 3 are bonded together. The PEEK resin 2 and metal oxide 3 are directly bonded together without the use of any other substance, by adhesion based mainly on physical interactions between atoms. The metal oxide 3 is a specific metal oxide that has a specific distance between metal atoms and acts to align the atomic arrangement of the PEEK resin.

The joint 1 shown in Figure 1 forms an intersomatic cage. An intersomatic cage is a type of implant that is embedded in the body and is used to treat spinal stenosis, scoliosis, and the like. As shown in Figure 2, an intervertebral disc 5 is located between the vertebral bodies 4 that make up the spine. The intersomatic cage is inserted between the vertebral bodies 4 as a replacement for the intervertebral disc 5 when the intervertebral disc 5 is removed due to damage or the like.

The intersomatic cage functions as a spacer that fixes the height of the vertebral bodies 4 and as a cushion that stabilizes the spine by cushioning the vertebral bodies 4. In Figures 1 and 2, the intersomatic cage is provided in a basket-like structure. The inside of the intersomatic cage is filled with grafted bone or the like depending on the treatment method. A joint 1 in which PEEK resin 2 and metal oxide 3 are joined together can be used as a material for such an intersomatic gauge.

The intersomatic cage can be provided in any suitable shape or structure. In Figures 1 and 2, the intersomatic cage has a through hole formed on the side. The intersomatic cage can also be provided in a form in which no through hole is formed on the side, in which a lattice is provided on the upper and lower openings or the through hole on the side, or in which unevenness is formed on the upper and lower surfaces around the opening.

In the bonded body 1 according to this embodiment, the metal oxide 3 used has a predetermined distance between metal atoms, and the relative difference between the distance between the benzene rings constituting the molecular chain of the PEEK resin 2 and the distance between the metal atoms constituting the crystal structure of the metal oxide 3 is 5% or less. The relative difference is the absolute value of the difference in distance, and means the ratio of the difference between the relatively long interval length and the relatively short interval length to the relatively short interval length ((long interval length - short interval length) / short interval length) [%].

In this specification, the distance between benzene rings constituting the molecular chain of PEEK resin means the distance between the centers of benzene rings connected via ether groups. The distance between benzene rings is determined within one polyetheretherketone unit composed of phenylene, ether, and ketone. The distance between benzene rings is determined in a conformation in which the ether groups have a specified bond angle and the benzene rings are oriented parallel to each other on the same plane (see Figures 11 to 13).

In this specification, the distance between metal atoms constituting the crystal structure of a metal oxide means the distance between metal atoms arranged periodically to form the metal oxide crystal. The distance between metal atoms corresponds to the distance between benzene rings of PEEK resin, and can be determined between any type of metal atom, between metal atoms located at any metal site, between metal atoms arranged in any crystal orientation, or between metal atoms in any close proximity.

Any metal atom in close proximity means, among multiple metal atoms periodically arranged on the same crystal plane in the crystal lattice of a metal oxide, a metal atom that is located across any number of metal atoms from the metal atom that is the starting point of the distance. For example, the distance from the metal atom that is the starting point of the distance to the first closest metal atom that is closest to the metal atom, or the distance to the second closest metal atom that is located across one metal atom from the metal atom, can be compared with the distance between benzene rings in PEEK resin.

Conventionally, interbody cages have been developed that are made of PEEK resin, with the surface coated with titanium oxide or hydroxyapatite (HAp). It is known that when an implant is made only of PEEK resin, it is difficult for the surrounding bone tissue to heal. Titanium oxide and HAp have good binding properties with bone tissue and are similar in properties to bone tissue, so the surface of the PEEK resin is coated with titanium oxide or HAp.

However, PEEK resin is known to have poor bonding with other materials. When PEEK resin and metal oxide are directly bonded, the adhesion phenomenon is difficult to achieve, so there is a problem that high bonding strength cannot be obtained. PEEK resin has high thermal stability and low reactivity, so chemical adsorption and chemical modification are also difficult. Even if it is simply coated with metal oxide, peeling due to interface destruction easily occurs when an external force is applied.

In contrast, when the relative difference between the spacing between the benzene rings of the PEEK resin 2 and the spacing between the metal atoms of the metal oxide 3 is 5% or less, the carbon atoms of the benzene rings and the metal atoms of the metal oxide 3 are arranged in close proximity to each other at the interface 101 between the PEEK resin 2 and the metal oxide 3, forming a strong interaction. The molecular chains of the PEEK resin 2 are able to align with the appropriate orientation and conformation relative to the crystal structure of the metal oxide 3.

As a result, a lattice-matched interface is formed between the PEEK resin 2 and the metal oxide 3, with the carbon atoms of the benzene ring and the metal atoms of the metal oxide 3 arranged close to each other and periodically. Since the lattice mismatch is reduced between the crystal phase formed by the molecular chains of the PEEK resin 2 and the crystal structure of the metal oxide 3, a stable adhesion state with high adhesion strength in terms of electronic and energy states is obtained. Therefore, the PEEK resin 2 and the metal oxide 3 can be bonded with high bonding strength.

In addition, molecular chains of other PEEK resins 2 can be aligned in an appropriate orientation and conformation with respect to the molecular chains of PEEK resin 2 aligned on the surface of the metal oxide 3. The effect of the metal oxide 3, which aligns the atomic arrangement of the PEEK resin, extends not only to the interface 101 between the PEEK resin 2 and the metal oxide 3, but also to areas away from the interface 101. Therefore, the adhesion strength between the molecular chains of PEEK resin 2 can be increased even in areas away from the interface 101.

As the PEEK resin 2, a resin with an appropriate molecular weight and degree of polymerization can be used. As the PEEK resin 2, a homopolymer containing only polyetheretherketone units may be used, or a copolymer in which polyetherketone units, polyetheretherketoneketone units, or other monomers are polymerized may be used. However, from the viewpoint of reducing lattice mismatch, it is preferable to use a homopolymer as the PEEK resin 2.

The PEEK resin 2 may or may not contain additives. Examples of additives include fillers, plasticizers, and flame retardants. In addition, as an additive, a specific metal oxide that acts to align the atomic arrangement of the PEEK resin, such as in the composite material described below, may also be added.

Examples of fillers include silica, talc, mica, clay, calcium carbonate, potassium titanate, carbon, glass fiber, carbon fiber, and organic fiber. Examples of plasticizers include phthalate esters, adipate esters, trimellitate esters, and phosphate esters. Examples of flame retardants include aluminum hydroxide, magnesium hydroxide, magnesium carbonate, ammonium polyphosphate, ammonium carbonate, antimony oxide, boric acid compounds, molybdenum compounds, bromine compounds, red phosphorus, phosphate esters, melamine compounds, triazine compounds, and guanidine compounds.

As the metal oxide 3, any suitable metal oxide can be bonded as long as the relative difference between the spacing between the benzene rings of the PEEK resin 2 and the spacing between the metal atoms of the metal oxide 3 is 5% or less. The metal oxide 3 may be an oxide containing one type of metal as a main component, or a composite oxide containing multiple types of metals as main components.

As the metal oxide 3, a single crystal or a polycrystal may be bonded as long as a lattice-matched interface is formed with the PEEK resin 2. However, from the viewpoint of bonding the PEEK resin 2 and the metal oxide 3 with high bonding strength, it is preferable that the area ratio of the crystal planes where the relative difference between the spacing between the benzene rings of the PEEK resin 2 and the spacing between the metal atoms of the metal oxide 3 is 5% or less is large, and it is preferable to bond a single crystal as the metal oxide 3.

The thickness of the metal oxide 3 in the direction perpendicular to the surface to be bonded to the PEEK resin 2 is preferably 2 nm or more and 100 μm or less. If the thickness is 2 nm or more, a lattice-matched interface is formed between the PEEK resin 2 and the metal oxide 3 by a large number of atoms, so that the bonding strength between the PEEK resin 2 and the metal oxide 3 can be further improved. Furthermore, if the thickness is 100 μm or less, peeling of the metal oxide 3 due to stress concentration or cohesive failure can be reduced.

The atomic density of the crystal plane of the metal oxide 3 to which the PEEK resin 2 is bonded is preferably 17 atoms/ ^nm2 or more. Even if the distance between metal atoms of the metal oxide 3 is a predetermined length, if the density of the metal atoms is low, it is difficult to form an interaction with the PEEK resin 2. In contrast, if the atomic density is 17 atoms/ ^nm2 or more, a lattice-matched interface is formed between the PEEK resin 2 and the metal oxide 3 by high-density atoms, and the bonding strength between the PEEK resin 2 and the metal oxide 3 can be further improved.

In the bonded body 1 according to this embodiment, preferred examples of the metal oxide 3 bonded to the PEEK resin 2 are as follows (1) to (3).

(1) The metal oxide 3 is titanium oxide (titania: _TiO2 ). The crystal plane of the metal oxide 3 to which the PEEK resin 2 is bonded is a crystal plane of titanium oxide having a rutile structure with Miller indices of (110) or a crystal plane equivalent thereto. The atomic density of the crystal plane of titanium oxide having a rutile structure to which the PEEK resin 2 is bonded is preferably 17 atom/ ^nm2 or more.

(2) The metal oxide 3 is aluminum _oxide (alumina: _Al2O3 ). The crystal plane of the metal oxide 3 to which the PEEK resin 2 is bonded is a crystal plane of aluminum oxide with Miller indices of (001) or a crystal plane equivalent thereto. The atomic density of the crystal plane of the aluminum oxide to which the PEEK resin 2 is bonded is preferably 17 atom/ ^nm2 or more.

(3) The metal oxide 3 is magnesium oxide (magnesia: MgO). The crystal plane of the metal oxide 3 to which the PEEK resin 2 is bonded is a crystal plane of magnesium oxide with Miller indices (111) or a crystal plane equivalent thereto. The atomic density of the magnesium oxide crystal plane to which the PEEK resin 2 is bonded is preferably 17 atom/ ^nm2 or more.

According to the metal oxides 3 of (1) to (3), the relative difference between the spacing between the benzene rings constituting the molecular chains of the PEEK resin and the spacing between the metal atoms constituting the crystal structure of the metal oxide is 5% or less. Therefore, by aligning the atomic arrangement of the PEEK resin, a lattice-matched interface is formed between the PEEK resin and the metal oxide, and the mutual bonding strength can be increased. In addition, the adhesion strength between the molecular chains of the PEEK resin can be increased in areas away from the interface.

Tables 1 to 3 show the results of measuring the bonding strength between PEEK resin and metal oxides by peel tests. In the peel tests, the bonding strength of metal oxides to PEEK resin or hydroxyapatite (HAp) was measured. The bonding strength of each of the main crystal planes was measured for titanium oxide, aluminum oxide, and magnesium oxide, which have a rutile structure.

For the peel test, a test piece of a bonded structure in which PEEK resin and a metal oxide were bonded was used. The test piece of the bonded structure was prepared by directly bonding PEEK resin to a crystal plane with a specified Miller index on the surface of a single crystal of the metal oxide. The test piece was in the shape of a strip with a width of 25 mm.

In the peel test, an adhesive tape was adhered to the surface of the PEEK resin, and one end of the adhesive tape was then peeled off at a 90-degree angle using a tensile tester to measure the peel strength. The bond strength per unit width of the test piece [kN/m] was then calculated based on the average value of the measured peel strength.

Table 1 shows the results when titanium oxide with a rutile structure was used as the metal oxide. In the case of titanium oxide with a rutile structure, the bonding strength of the (110) plane was significantly higher than that of the (100), (001), and (210) planes for both PEEK resin and HAp.

Table 2 shows the results when aluminum oxide was used as the metal oxide. In the case of aluminum oxide, the bonding strength of the (001) plane was significantly higher than that of the (100), (110), and (210) planes for both PEEK resin and HAp.

Table 3 shows the results when magnesium oxide was used as the metal oxide. In the case of magnesium oxide, the bonding strength of the (111) plane was significantly higher than that of the (100), (001), and (110) planes for both PEEK resin and HAp.

As shown in Tables 1 to 3, the bonding strength between metal oxide and PEEK resin and the bonding strength between metal oxide and HAp showed similar trends for the types of crystal planes represented by the same Miller indices. This is because the spacing between calcium atoms in HAp is similar to the spacing between benzene rings in PEEK resin. It can be said that under conditions that reduce the lattice mismatch between metal oxide and PEEK resin, the lattice mismatch between metal oxide and HAp is also reduced.

Fig. 3 is a cross-sectional view showing an example of a bonded structure according to an embodiment of the present invention, in which an intersomatic cage is shown as an example of a bonded structure in which a PEEK resin and a metal oxide are bonded together.
As shown in FIG. 3, a HAp film 102 can be formed on the surface of a bonded body 1 in which a PEEK resin 2 and a metal oxide 3 are bonded to each other.

The HAp film 102 is formed mainly of hydroxyapatite (HAp) ( _Ca10 ( _PO4 ) ₆ (OH) ₂ ). The HAp film 102 may contain calcium deficiency or a heterogeneous phase such as calcium phosphate. The HAp film 102 can be formed on the surface of the metal oxide 3 opposite to the surface bonded to the PEEK resin 2. By covering the surface of the metal oxide 3 with the HAp film 102, the bond between the joint 1 and bone tissue can be improved.

The thickness of the HAp film 102 is preferably 2 nm or more and 50 μm or less. If the thickness is 2 nm or more, a lattice-matched interface is formed between the metal oxide 3 and the HAp film 102 by a large number of atoms, so that the bonding strength between the metal oxide 3 and the HAp film 102 can be further improved. Furthermore, if the thickness is 50 μm or less, peeling of the HAp film 102 due to stress concentration or cohesive failure can be reduced.

As shown in Tables 1 to 3, the bonding strength between the metal oxide and HAp is significantly higher when the metal oxide has a specified crystal plane. Therefore, from the viewpoint of bonding the metal oxide 3 and the HAp film 102 with higher bonding strength, it is preferable to form the HAp film 102 on the (110) plane of titanium oxide, the (001) plane of aluminum oxide, or the (111) plane of magnesium oxide, which are rutile structures.

Next, we will explain the manufacturing method of the bonded body according to this embodiment in which PEEK resin and metal oxide are bonded to each other.

The bonded body according to this embodiment can be manufactured by a manufacturing method in which a film of a specified metal oxide that acts to align the atomic arrangement of the PEEK resin is formed on the surface of the PEEK resin. The metal oxide is formed as a thin film with a specified crystal structure so that the relative difference between the spacing between the benzene rings of the PEEK resin and the spacing between the metal atoms of the metal oxide is 5% or less.

The manufacturing method of the bonded body according to this embodiment includes a film-forming process in which a metal oxide film is formed on the surface of the PEEK resin, and a heat treatment process in which the PEEK resin on which the metal oxide film is formed is heat-treated to improve the crystal orientation of the metal oxide. When the surface of the metal oxide is to be covered with a HAp film, a film-forming process in which a HAp film is formed on the surface of the metal oxide is performed after the heat treatment process.

Methods for forming a metal oxide film on the surface of PEEK resin include a transfer film formation method in which a metal oxide film formed on a substrate is transferred to the surface of the PEEK resin, and a direct film formation method in which a metal oxide film is directly formed on the surface of the PEEK resin.

When using the transfer deposition method, first, a single crystal substrate is prepared, which is made of a metal oxide that has a predetermined distance between metal atoms and acts to align the atomic arrangement of the PEEK resin. For example, a substrate is prepared that has a surface with a rutile structure such as a titanium oxide (110) surface, an aluminum oxide (001) surface, or a magnesium oxide (111) surface.

Next, a HAp film made of HAp is formed on the surface of the single crystal substrate made of metal oxide. The film formation method may be a physical vapor deposition method such as Pulsed Laser Deposition (PLD) or sputtering, a liquid phase synthesis method, or a plasma spraying method. Since the spacing between calcium atoms in HAp is similar to the spacing between metal atoms in metal oxide, a lattice-matched HAp film is formed.

Next, a metal oxide film is formed on the surface of the HAp film formed on the substrate. The metal atoms are spaced apart by a predetermined length, and the metal oxide film acts to align the atomic arrangement of the PEEK resin. The film can be formed by physical vapor deposition methods such as arc ion plating (AIP) and sputtering. The spacing between calcium atoms in HAp is similar to the spacing between benzene rings in the PEEK resin, so a lattice-matched metal oxide film is formed.

Then, the metal oxide film formed on the substrate is peeled off from the substrate. The metal oxide film formed on the substrate may be peeled off at the interface with the HAp film, or may be peeled off together with the HAp film at the interface with the single crystal substrate. For example, a method can be used in which a transfer plate with adhesive tape attached is attached to the surface of the metal oxide film formed on the substrate, and then the metal oxide is peeled off from the single crystal substrate at the interface with the HAp film or the interface with the single crystal substrate.

Then, the metal oxide peeled off from the substrate is transferred to and coated on the surface of the PEEK resin formed into a predetermined shape. A method for transferring a thin film of metal oxide can be used in which, for example, the metal oxide adhered to a transfer plate via adhesive tape is adhered to the surface of the PEEK resin, and then the transfer plate is peeled off from the metal oxide. The transfer plate adhered via adhesive tape can be peeled off with a solvent. The surface of the PEEK resin can be previously subjected to a surface treatment such as plasma treatment or corona discharge treatment.

Next, the PEEK resin on which the metal oxide film has been formed is heat-treated to improve the crystal orientation of the metal oxide. The heat treatment temperature is preferably 100°C or higher and 400°C or lower. If the heat treatment temperature is 100°C or higher, it is possible to reduce the disorder of the crystal structure of the metal oxide and increase the area ratio of a specified crystal structure in which the distance between metal atoms is a specified length. If the heat treatment temperature is 400°C or lower, it is possible to avoid thermal decomposition of the PEEK resin.

By improving the crystal orientation of the metal oxide by heat treatment, the lattice mismatch at the interface is reduced, and a lattice-matched interface is formed between the PEEK resin and the metal oxide. By such heat treatment, a bonded body 1 can be obtained in which the PEEK resin 2 and the metal oxide 3 are bonded to each other. In addition, by peeling the metal oxide from the substrate together with the HAp film and coating it on the surface of the PEEK resin, a bonded body in which the HAp film is coated on the surface of the metal oxide can be obtained.

With this type of transfer deposition method, a metal oxide film formed on a substrate is transferred to the surface of the PEEK resin, so that the distance between metal atoms is a specified length, and a specified metal oxide that acts to align the atomic arrangement of the PEEK resin can be deposited while suppressing the thermal load on the PEEK resin. The final heat treatment only needs to reduce the disturbance of the crystal structure of the metal oxide, so the heat treatment temperature can be kept low.

Furthermore, with this film formation method, in the stage of peeling off the metal oxide film formed on the substrate, only the metal oxide can be peeled off at the interface with the HAp film to produce a joint 1 in which the PEEK resin 2 and the metal oxide 3 are bonded to each other, or the metal oxide can be peeled off together with the HAp film at the interface with the single crystal substrate to produce a joint 1 in which the surface of the metal oxide 3 is coated with a HAp film 102. By peeling off the metal oxide together with the HAp film, a joint 1 coated with a HAp film 102 that easily bonds with bone tissue can be produced without the film formation step.

On the other hand, when using the direct film formation method, first, a metal oxide film is formed on the surface of PEEK resin molded into a predetermined shape, with the metal atoms spaced at a predetermined distance from each other, and with the effect of aligning the atomic arrangement of the PEEK resin. The surface of the PEEK resin can be subjected to a surface treatment such as plasma treatment or corona discharge treatment in advance. As a film formation method, physical vapor deposition methods such as arc ion plating (AIP) and sputtering can be used.

Next, the PEEK resin with the metal oxide film formed on its surface is heat-treated to improve the crystal orientation of the metal oxide. The heat treatment temperature is preferably 100°C or higher and 400°C or lower, as in the case of using the transfer film formation method.

By improving the crystal orientation of the metal oxide by heat treatment, the lattice mismatch at the interface is reduced, and a lattice-matched interface is formed between the PEEK resin and the metal oxide. By such heat treatment, a bonded body 1 can be obtained in which the PEEK resin 2 and the metal oxide 3 are bonded to each other.

Next, a HAp film made of HAp is formed on the surface of the metal oxide film formed on the surface of the PEEK resin. The film formation method may be a physical vapor deposition method such as pulsed laser deposition (PLD) or sputtering, a liquid phase synthesis method, or a plasma spraying method. If a HAp film is not required, the formation of the HAp film may be omitted.

This direct film formation method forms a film of metal oxide directly on the surface of PEEK resin, so the interval between metal atoms is a predetermined length, and a predetermined metal oxide that acts to align the atomic arrangement of PEEK resin can be formed with a small number of steps. Furthermore, even if the PEEK resin is molded into a complex shape, a metal oxide film that exhibits a predetermined crystal orientation can be formed over a wide area.

When forming the metal oxide or HAp film, it is preferable to monitor the film thickness using the quartz crystal microbalance (QCM) method, as described in the literature (Masazumi Okido, et al., Evaluation of the Hydroxyapatite Film Coating on Titanium Cathode by QCM, Materials Transactions, Vol. 43, No. 12 (2002) p. 3010-3014). The thickness of the metal oxide is preferably 2 nm or more and 100 μm or less. The thickness of the HAp film is preferably 2 nm or more and 50 μm or less.

When the AIP method is used as a method for forming a metal oxide film, PEEK resin is used as the film-forming object, the metal that constitutes the metal oxide is used as the evaporation source, and oxygen gas or a mixed gas of oxygen and an inert gas is used as the reactive gas, and film formation is performed by arc discharge in a vacuum atmosphere. The target current applied to the evaporation source is preferably 100 A or more. The substrate bias voltage applied to the film-forming object is preferably 60 V or more.

For example, to improve the crystal orientation of titanium oxide, which has a rutile structure, and increase the area ratio of the (110) plane, a high temperature of approximately 800°C or higher is required. If the temperature during film formation is low, the ratio of anatase structure or amorphous structure tends to increase, and the area ratio of the (110) plane tends to decrease. If the target current is 100 A or more and the bias voltage is 60 V or more, the temperature during film formation becomes high, and the crystal orientation of the metal oxide can be appropriately increased.

According to the bonded body of the present embodiment, the relative difference between the spacing between the benzene rings of the PEEK resin and the spacing between the metal atoms of the metal oxide is 5% or less, and the metal oxide that acts to align the atomic arrangement of the PEEK resin is bonded to the PEEK resin, so that a lattice-matched interface can be formed between the PEEK resin and the metal oxide. Therefore, a bonded body can be obtained in which the adhesion strength between the PEEK resin and the metal oxide is high and interfacial destruction is unlikely to occur at the interface between the PEEK resin and the metal oxide. In addition, the effect of aligning the atomic arrangement of the PEEK resin extends to areas away from the interface, so the yield strength of the base material formed of the PEEK resin can be improved.

Figure 4 is a cross-sectional view showing a schematic example of a composite material according to an embodiment of the present invention. Figure 4 shows an example of a composite material containing a metal oxide with PEEK resin as the base material. In Figure 4, reference numeral 7 indicates the composite material, reference numeral 8 indicates the PEEK resin, reference numeral 9 indicates the metal oxide, and reference numeral 201 indicates the interface between the PEEK resin and the metal oxide.

As shown in FIG. 4, the composite material 7 according to this embodiment includes at least a PEEK resin 8 forming a base material, and a metal oxide 9 dispersed in the base material. As the metal oxide 9, a specific metal oxide is blended in which the distance between metal atoms is a specific length and which acts to align the atomic arrangement of the PEEK resin.

The composite material 7 according to this embodiment can be molded into an appropriate shape depending on the application, etc. In the composite material 7 according to this embodiment, the metal oxide 9 used has a predetermined distance between metal atoms, and the relative difference between the distance between the benzene rings constituting the molecular chain of the PEEK resin 8 and the distance between the metal atoms constituting the crystal structure of the metal oxide 9 is 5% or less.

When such metal oxide 9 is dispersed, a lattice-matched interface is formed between the PEEK resin 8 and the metal oxide 9, as the carbon atoms of the benzene ring and the metal atoms of the metal oxide 9 are periodically arranged close to each other. Since the lattice mismatch is reduced between the crystal phase formed by the molecular chains of the PEEK resin 8 and the crystal structure of the metal oxide 9, a stable adhesion state with high adhesion strength in terms of electronic and energy states is obtained.

As a result, at the interface 201 between the PEEK resin 8 and the metal oxide 9, the molecular chains of the PEEK resin 8 can be aligned in an appropriate orientation and conformation relative to the crystal structure of the metal oxide 9. The molecular chains of the PEEK resin 8 aligned on the surface of the metal oxide 9 can be aligned with other molecular chains of the PEEK resin 8 in an appropriate orientation and conformation.

Therefore, the effect of the metal oxide 9 to align the atomic arrangement of the PEEK resin is not limited to the interface 201 between the PEEK resin 8 and the metal oxide 9, but extends to areas away from the interface 201 as well. Starting from the metal oxide 9, the effect of aligning the atomic arrangement of the PEEK resin 8 can be obtained over a wide range. Generally, it is difficult to obtain a sufficiently high rigidity with PEEK resin alone, but by aligning the molecular chains of the PEEK resin 8, the adhesive strength between the molecular chains of the PEEK resin 8 can be increased, thereby improving the yield strength of the composite material 7.

As the PEEK resin 8, a resin with an appropriate molecular weight and degree of polymerization can be used. As the PEEK resin 8, a homopolymer containing only polyetheretherketone units may be used, or a copolymer in which polyetherketone units, polyetheretherketoneketone units, or other monomers are polymerized may be used. However, from the viewpoint of reducing lattice mismatch, it is preferable to use a homopolymer as the PEEK resin 8.

The PEEK resin 8 may contain additives other than the metal oxide 9 that acts to align the atomic arrangement of the PEEK resin, or no additives may be added. Examples of additives other than the metal oxide 9 include fillers, plasticizers, and flame retardants. The same types of fillers, plasticizers, and flame retardants as those used for the bonded body 1 can be used.

As the metal oxide 9, any suitable metal oxide can be blended as long as the relative difference between the spacing between the benzene rings of the PEEK resin 8 and the spacing between the metal atoms of the metal oxide 9 is 5% or less. The metal oxide 9 may be an oxide containing one type of metal as a main component, or a composite oxide containing multiple types of metals as main components.

The metal oxide 9 is preferably one that has the effect of aligning the atomic arrangement of the PEEK resin, as well as the effect of blocking ultraviolet rays. When the composite material 7 is used for aerospace applications or outdoors, the PEEK resin 8 may be altered by the effects of ultraviolet rays. For this reason, the metal oxide 9 is preferably one that has the effect of reflecting, scattering, or absorbing ultraviolet rays, and rutile-type titanium oxide is preferred compared to aluminum oxide and magnesium oxide.

As the metal oxide 9, a single crystal or a polycrystal may be blended as long as the lattice mismatch with the PEEK resin 8 is suppressed. However, from the viewpoint of improving the mechanical properties of the composite material 7 over a wide range, it is preferable that the area ratio of the crystal planes where the relative difference between the spacing between the benzene rings of the PEEK resin 8 and the spacing between the metal atoms of the metal oxide 9 is 5% or less is large, and it is preferable to blend a single crystal as the metal oxide 9.

The concentration of the metal oxide 9 is preferably 0.2 at% or more and 38 at% or less. When the concentration is 0.2 at% or more, the number of starting points for the action of aligning the atomic arrangement of the PEEK resin increases. When the concentration is 38% or less, embrittlement of the base material formed of the PEEK resin is avoided, and the starting points for the action of aligning the atomic arrangement of the PEEK resin can be dispersed discretely. When the concentration is 0.2 at% or more and 38 at% or less, the action from the multiple starting points extends independently to a region away from the interface 201 between the PEEK resin 8 and the metal oxide 9 without interfering with each other, so that the molecular chains of the PEEK resin can be aligned over a wide range of the base material, thereby achieving a high effect of improving the yield strength.

The average particle size of the metal oxide 9 is preferably 2 nm or more and 10 μm or less. When the average particle size is 2 nm or more, the crystallinity is good and the variation in particle size is suppressed, so that it is easy to obtain a crystal plane in which the distance between metal atoms is a predetermined length. Furthermore, when the average particle size is 10 μm or less, embrittlement of the base material formed of PEEK resin is avoided and the specific surface area of the metal oxide 9 is increased. When the average particle size is 2 nm or more and 10 μm or less, the effect of aligning the atomic arrangement of the PEEK resin can be applied to a wide area away from the interface 201 between the PEEK resin 8 and the metal oxide 9, thereby improving the yield strength of the base material.

The atomic density of the crystal plane of the metal oxide 9 in contact with the PEEK resin 8 is preferably 17 atoms/ ^nm2 or more. Even if the distance between the metal atoms of the metal oxide 9 is a predetermined length, if the density of the metal atoms is low, it is difficult to form an interaction with the PEEK resin 8. In contrast, if the atomic density is 17 atoms/ ^nm2 or more, a lattice-matched interface is formed between the PEEK resin 8 and the metal oxide 9 by high-density atoms, so that the effect of aligning the atomic arrangement of the PEEK resin can be applied to a wide range away from the interface 201 between the PEEK resin 8 and the metal oxide 9, thereby improving the yield strength of the base material.

In the composite material 7 according to this embodiment, preferred examples of the metal oxide 9 dispersed in the matrix formed of the PEEK resin 8 are as follows (4) to (6).

(4) The metal oxide 9 is titanium oxide (titania: _TiO2 ). The surface of the metal oxide 9 in contact with the PEEK resin 8 includes a crystal plane of titanium oxide having a rutile structure with Miller indices of (110) or a crystal plane equivalent thereto. The metal oxide 9 is preferably one in which the area ratio of the (110) plane is the largest among all crystal planes detected in the metal oxide 9. The atomic density of the crystal plane of the titanium oxide having a rutile structure in contact with the PEEK resin 8 is preferably 17 atoms/ ^nm2 or more.

(5) The metal oxide 9 is aluminum oxide ( _alumina : _Al2O3 ). The surface of the metal oxide 9 in contact with the PEEK resin 8 includes a crystal plane of the aluminum oxide with Miller indices (001) or a crystal plane equivalent thereto. The metal oxide 9 is preferably one in which the area ratio of the (001) plane is the largest among all the crystal planes detected in the metal oxide 9. The atomic density of the crystal plane of the aluminum oxide in contact with the PEEK resin 8 is preferably 17 atom/ ^nm2 or more.

(6) The metal oxide 9 is magnesium oxide (magnesia: MgO). The surface of the metal oxide 9 in contact with the PEEK resin 8 includes a crystal plane of magnesium oxide with Miller indices (111) or a crystal plane equivalent thereto. The metal oxide 9 is preferably one in which the area ratio of the (111) plane is the largest among all crystal planes detected in the metal oxide 9. The atomic density of the crystal plane of the magnesium oxide in contact with the PEEK resin 8 is preferably 17 atom/ ^nm2 or more.

According to metal oxide 9 of (4) to (6), the relative difference between the spacing between the benzene rings constituting the molecular chain of the PEEK resin and the spacing between the metal atoms constituting the crystal structure of the metal oxide is 5% or less. Therefore, by aligning the atomic arrangement of the PEEK resin, a lattice-matched interface is formed between the PEEK resin and the metal oxide, and the adhesive strength between them can be increased. In addition, in areas away from the interface, the adhesive strength between the molecular chains of the PEEK resin is increased, and the mechanical properties such as the yield strength of the base material formed from the PEEK resin can be improved.

Figure 5 is a perspective view showing a schematic diagram of a metal oxide dispersed in a composite material according to an embodiment of the present invention. Figure 5 shows a single crystal metal oxide in which the crystal lattice structure is reflected on the surface. In Figure 5, symbols 10 to 13 indicate the crystal planes of the metal oxide, symbol s indicates the length of the metal oxide crystal, symbol t indicates the width of the metal oxide crystal, and symbol h indicates the height of the metal oxide crystal.

In FIG. 5, when the crystal plane with the largest area among the surfaces of the metal oxide 9 dispersed in the composite material 7 is crystal plane 10 or crystal plane 11, it is preferable that the relative difference between the spacing between the benzene rings constituting the molecular chain of the PEEK resin 2 and the spacing between the metal atoms constituting the crystal structure of the metal oxide 3 on crystal plane 10 or crystal plane 11 is 5% or less.

For example, when the metal oxide 9 is a single crystal of titanium oxide of the rutile type, the crystal lattice is a tetragonal system. In such a case, it is preferable that the crystal plane 10 or 11 having the largest area is a (110) plane. It is also preferable that the crystal plane 12 or 13 perpendicular to the crystal plane 10 or 11 is a (1-10) plane. This is because the (1-10) plane has an atomic arrangement equivalent to that of the (110) plane and forms a lattice-matched interface with the PEEK resin 8.

When the metal oxide 9 is a single crystal of α-aluminum oxide, which has a hexagonal crystal system, it is preferable that the crystal face with the largest area and the crystal face parallel to the crystal face are the (001) plane or a crystal face equivalent thereto. When the metal oxide 9 is a single crystal of magnesium oxide, which has a cubic crystal system, it is preferable that the crystal face with the largest area and the crystal face parallel to the crystal face are the (111) plane or a crystal face equivalent thereto.

The crystal orientation of metal oxides and the area ratio of a specific crystal plane can be determined by X-ray diffraction (XRD) measurement. Using metal oxide powder as a sample, the X-ray diffraction spectrum of each metal oxide can be obtained by powder X-ray diffraction measurement. The crystal orientation of metal oxides and the area ratio of a specific crystal plane can be determined by calculating the ratio of the peak area of an individual crystal plane represented by a specific Miller index to the total peak area of all crystal planes detected in the obtained X-ray diffraction spectrum.

Figure 6 shows the results of an analysis of the relationship between the proportion of (110) faces in the total surface area of titanium oxide and the yield strength of a composite material. Figure 6 shows the relationship between the proportion of crystal faces of rutile titanium oxide with Miller indices (110) determined by powder X-ray diffraction measurement, and the yield strength of a composite material in which titanium oxide is blended to achieve said proportion. The concentration of titanium oxide is 0.3 at% in all cases. It is assumed that the (110) faces of rutile titanium oxide correspond to crystal planes 10 and 11 in Figure 5.

The solid line in the figure shows the result of changing the proportion of (110) planes by fixing the length s and width t in Figure 5 to 8 nm and changing only the height h. The dashed line in the figure shows the result of changing the proportion of (110) planes by fixing the width t and height h in Figure 5 to 8 nm and changing only the length s. The dashed line in the figure shows the result of changing the proportion of (110) planes by fixing the width t to 8 nm and the height h to 4 nm in Figure 5 and changing only the length s.

As shown in Figure 6, the yield strength of the composite material was relatively high when only the height h was changed. When the ratio of (110) faces exceeded 57% or 74%, the yield strength increased stepwise. From the viewpoint of improving the yield strength of the composite material, it is preferable that the ratio of (110) faces in the total surface area of titanium oxide is 57% or more, and more preferably 74% or more.

Figure 7 shows the results of an analysis of the relationship between the proportion of (001) faces in the total surface area of aluminum oxide and the yield strength of a composite material. Figure 7 shows the relationship between the proportion of crystal faces of aluminum oxide with Miller indices (001) determined by powder X-ray diffraction measurement, and the yield strength of a composite material in which aluminum oxide is blended to achieve that proportion. The concentration of aluminum oxide is 0.3 at% in all cases. It is assumed that the (001) faces of aluminum oxide correspond to crystal planes 10 and 11 in Figure 5.

The solid line in the figure shows the result of changing the proportion of (001) faces by fixing the length s and width t in Figure 5 to 8 nm and changing only the height h. The dashed line in the figure shows the result of changing the proportion of (001) faces by fixing the width t and height h in Figure 5 to 8 nm and changing only the length s. The dashed line in the figure shows the result of changing the proportion of (001) faces by fixing the width t to 8 nm and the height h to 4 nm in Figure 5 and changing only the length s.

As shown in Figure 7, the yield strength of the composite material was relatively high when only the height h was changed. When the ratio of (001) faces exceeded 57% or 74%, the yield strength increased stepwise. From the viewpoint of improving the yield strength of the composite material, it is preferable that the ratio of (001) faces in the total surface area of aluminum oxide is 57% or more, and more preferably 74% or more.

Figure 8 shows the results of an analysis of the relationship between the proportion of (111) faces in the total surface area of magnesium oxide and the yield strength of a composite material. Figure 8 shows the relationship between the proportion of crystal faces of magnesium oxide with Miller indices of (111) determined by powder X-ray diffraction measurement, and the yield strength of a composite material in which magnesium oxide is blended to achieve said proportion. The concentration of magnesium oxide is 0.3 at% in all cases. It is assumed that the (111) faces of magnesium oxide correspond to crystal faces 10 and 11 in Figure 5.

The solid line in the figure shows the result of changing the proportion of (111) faces by fixing the length s and width t in Figure 5 to 8 nm and changing only the height h. The dashed line in the figure shows the result of changing the proportion of (111) faces by fixing the width t and height h in Figure 5 to 8 nm and changing only the length s. The dashed line in the figure shows the result of changing the proportion of (111) faces by fixing the width t to 8 nm and the height h to 4 nm in Figure 5 and changing only the length s.

As shown in Figure 8, the yield strength of the composite material was relatively high when only the height h was changed. When the ratio of (111) faces exceeded 57% or 74%, the yield strength increased stepwise. From the viewpoint of improving the yield strength of the composite material, it is preferable that the ratio of (111) faces in the total surface area of magnesium oxide is 57% or more, and more preferably 74% or more.

Next, the area ratio of the crystal faces of the metal oxide, in which the distance between metal atoms is a given length, was fixed, and the relationship between the metal oxide concentration and the metal oxide particle size and the yield strength of the composite material was analyzed.

The relationship between the concentration of metal oxide and the yield strength of the composite material was determined by fixing the length s and width t in Figure 5 to 8 nm and varying only the height h, fixing the proportion of the (110) plane of titanium oxide, the proportion of the (001) plane of aluminum oxide, and the proportion of the (111) plane of magnesium oxide to 74%, and varying the concentration of metal oxide dispersed in the PEEK resin.

Analysis of the relationship between metal oxide concentration and the yield strength of the composite material showed that, for all metal oxides, when the metal oxide concentration was 0.2 at% or more and 38 at% or less, the yield strength of the composite material was significantly improved. If the concentration was less than 0.2 at%, it could be said that there were insufficient starting points for the effect of aligning the atomic arrangement of the PEEK resin. Also, if the concentration exceeded 38 at%, the base material formed of PEEK resin became brittle and tended to break brittlely without showing ductility, which is undesirable.

The relationship between the particle size of the metal oxide and the yield strength of the composite material was determined by fixing the proportion of (110) faces of titanium oxide, the proportion of (001) faces of aluminum oxide, and the proportion of (111) faces of magnesium oxide at 74% and varying the average particle size of the metal oxide dispersed in the PEEK resin.

Analysis of the relationship between the particle size of the metal oxide and the yield strength of the composite material showed that, for all metal oxides, when the average particle size of the metal oxide was 2 nm or more and 10 μm or less, the yield strength of the composite material was significantly improved. If the average particle size is less than 2 nm, it is difficult to obtain a crystal plane that acts to align the atomic arrangement of the PEEK resin. Also, if the average particle size exceeds 10 μm, the base material formed from the PEEK resin becomes brittle and tends to break brittlely without showing ductility, which is undesirable.

Next, we will explain the manufacturing method of the composite material according to this embodiment, which contains metal oxide and has PEEK resin as the base material.

The composite material according to this embodiment can be manufactured by a manufacturing method in which a predetermined metal oxide that acts to align the atomic arrangement of PEEK resin is dispersed in a base material formed of PEEK resin. The metal oxide is mixed into the PEEK resin as a filler with a predetermined crystal structure so that the relative difference between the spacing between benzene rings in the PEEK resin and the spacing between metal atoms in the metal oxide is 5% or less.

The method for producing a composite material according to this embodiment includes a heating and kneading process in which a mixture of PEEK resin and metal oxide is heated and kneaded, and a molding process in which the resin composition obtained in the heating and kneading process is hot molded to improve the crystal orientation of the metal oxide.

PEEK resin can be prepared in an appropriate raw material form such as pellets or powder. Metal oxide can be prepared in a raw material form such as powder. The raw materials PEEK resin and metal oxide can be mixed together with additives added as necessary. The mixture of these raw materials is heated to melt and kneaded to form a resin composition.

The resin composition can be mixed using various devices such as a batch-type closed mixer such as a Banbury mixer or a pressure kneader, an open mixer such as a roll mixer or a rotor mixer, a single screw extruder, or a twin screw extruder. The heating conditions are preferably 373°C ± 20°C for about 2 minutes. Under such heating conditions, the PEEK resin can be fluidized without thermal decomposition and can be mixed uniformly with the metal oxide.

The resin composition is then hot molded to produce a molded product with improved crystal orientation of the metal oxide. The molding temperature is preferably 100°C or higher and 400°C or lower. A molding temperature of 100°C or higher can reduce disorder in the crystal structure of the metal oxide and increase the area ratio of a specified crystal structure in which the distance between metal atoms is a specified length. A molding temperature of 400°C or lower can avoid thermal decomposition of the PEEK resin.

The resin composition can be molded into any shape depending on the application of the composite material. As a molding method, any suitable method such as extrusion molding, injection molding, blow molding, compression molding, and additive manufacturing can be used. When using a mold to mold the resin composition, it is preferable to set the mold temperature to 100°C or higher in order to reduce disturbance of the crystal structure of the metal oxide.

According to the composite material of the present embodiment, the relative difference between the spacing between benzene rings of the PEEK resin and the spacing between metal atoms of the metal oxide is 5% or less, and the metal oxide that acts to align the atomic arrangement of the PEEK resin is dispersed in the base material formed of the PEEK resin, so that a lattice-matched interface can be formed between the PEEK resin and the metal oxide. Therefore, a composite material with high adhesion strength between the PEEK resin and the metal oxide can be obtained. In addition, since the metal oxide is dispersed in the base material and the effect of aligning the atomic arrangement of the PEEK resin extends to areas away from the interface, the yield strength of the base material formed of the PEEK resin can be improved.

Figure 9 is a cross-sectional view showing a schematic example of a composite material according to an embodiment of the present invention. Figure 9 shows an example of a composite material in which PEEK resin is the base material and contains a metal oxide as a filler, and a metal oxide as a bonding material is bonded to the surface of the PEEK resin. In Figure 9, reference numeral 8 denotes PEEK resin, reference numeral 9 denotes the metal oxide as a filler, reference numeral 14 denotes the composite material, reference numeral 15 denotes the metal oxide as a bonding material, reference numeral 16 denotes a metal, and reference numeral 301 denotes the interface between the PEEK resin and the metal oxide.

As shown in FIG. 9, the composite material 14 according to this embodiment includes at least a PEEK resin 8 forming a base material, and a metal oxide 9 dispersed in the base material. As the metal oxide 9, a specific metal oxide is blended in which the distance between metal atoms is a specific length and which acts to align the atomic arrangement of the PEEK resin.

The composite material 14 according to this embodiment is in the form of a bonding material in which a metal oxide 15, which is a bonding material, is bonded to the surface of the PEEK resin 8. The metal oxide 15 may constitute the bonding material alone, or may constitute the bonding material together with the metal 16, as shown in FIG. 9. The metal oxide 15 may be formed by a method of thermally oxidizing a portion of the surface side of the metal 16, or may be formed by a method of forming a film on the surface of the metal 16.

As the metal oxide 15 serving as the bonding material, an appropriate metal oxide can be used, similar to the metal oxide 3 described above. As the metal oxide 15, a single crystal or a polycrystal may be used. The thickness of the metal oxide 15 in the direction perpendicular to the surface to be bonded to the PEEK resin 8 is preferably 2 nm or more and 100 μm or less. The atomic density of the crystal surface of the metal oxide 15 to which the PEEK resin 8 is bonded is preferably 17 atom/ ^nm2 or more.

As the metal 16 that constitutes the bonding material together with the metal oxide 15, an appropriate pure metal or alloy can be used. The metal 16 can be processed and molded into any shape depending on the application of the composite material 14. From the viewpoint of reducing the weight of the composite material 14, the metal 16 is preferably a light metal with a specific gravity smaller than that of iron, and titanium, aluminum, magnesium, or alloys thereof are preferable. The metal oxide 15 and the metal 16 are preferably composed of the same type of metal. Such a metal oxide 15 can be formed by a method of thermally oxidizing the surface of the metal 16.

In the composite material 14 according to this embodiment, preferred examples of the metal oxide 15 bonded to the PEEK resin 8 and the metal oxide 9 dispersed in the matrix formed of the PEEK resin 8 are as follows (7) to (9).

(7) The metal oxide 15 serving as the bonding material is titanium oxide (titania: _TiO2 ). The crystal plane of the metal oxide 15 to which the PEEK resin 8 is bonded is a crystal plane of titanium oxide having a rutile structure with Miller indices of (110), or a crystal plane equivalent thereto. The atomic density of the crystal plane of titanium oxide having a rutile structure to which the PEEK resin 8 is bonded is preferably 17 atom/ ^nm2 or more. The metal oxide 9 serving as the filler is preferably titanium oxide. The titanium oxide is preferably formed on the surface of titanium or a titanium alloy.

(8) The metal oxide 15 serving as the bonding material is aluminum oxide ( _alumina : _Al2O3 ). The crystal plane of the metal oxide 15 to which the PEEK resin 8 is bonded is a crystal plane of aluminum oxide with Miller indices of (001) or a crystal plane equivalent thereto. The atomic density of the crystal plane of the aluminum oxide to which the PEEK resin 8 is bonded is preferably 17 atoms/ ^nm2 or more. The metal oxide 9 serving as the filler is preferably aluminum oxide. The aluminum oxide is preferably formed on the surface of aluminum or an aluminum alloy.

(9) The metal oxide 15 serving as the bonding material is magnesium oxide (magnesia: MgO). The crystal face of the metal oxide 15 to which the PEEK resin 8 is bonded is a crystal face of magnesium oxide with Miller indices (111) or a crystal face equivalent thereto. The atomic density of the crystal face of the magnesium oxide to which the PEEK resin 8 is bonded is preferably 17 atom/ ^nm2 or more. The metal oxide 9 serving as the filler is preferably magnesium oxide. The magnesium oxide is preferably formed on the surface of magnesium or a magnesium alloy.

By combining (7) to (9), the yield strength of the composite material 7 is increased by lattice matching at the interface 301 between the PEEK resin 8 and the metal oxide 9, and the bonding strength between the PEEK resin 8 and the metal oxide 9 and the metal oxide 14 is increased by lattice matching at the interface between the composite material 7 and the metal oxide 14. In addition, by forming the metal oxide 14 by thermal oxidation of the metal 15, the bonding strength between the metal oxide 14 and the metal 15 can be increased. Therefore, a material can be obtained in which the composite material 7, which has a high yield strength, and the metal 15 are combined with each other with high bonding strength.

According to the composite material of this embodiment, the relative difference between the spacing between benzene rings in the PEEK resin and the spacing between metal atoms in the metal oxide is 5% or less, and the metal oxide that acts to align the atomic arrangement of the PEEK resin is dispersed in the base material formed of the PEEK resin and is bonded to the PEEK resin. This makes it possible to obtain a composite material in which the yield strength of the base material formed of the PEEK resin and the adhesive strength between the PEEK resin and the metal oxide are high and interfacial failure is unlikely to occur at the interface between the PEEK resin and the metal oxide.

In addition, by bonding PEEK resin to metals or metal oxides, structural materials can be made multi-material. By making them multi-material with lightweight metals or metal oxides, it is possible to reduce the weight of moving objects. This can improve the fuel efficiency and power consumption of moving objects, thereby reducing the environmental burden as we move towards carbon neutrality. In addition, by making implant materials multi-material, it is possible to make the implants lighter and more multifunctional.

Note that multi-materialization means that a product that was previously manufactured using only one of the following materials, such as metal, inorganic, or resin, is manufactured using a combination of multiple materials. When trying to reduce the weight of a product, it is effective to replace the metal or inorganic materials that were previously used with resin materials. On the other hand, from the standpoint of processability, processing precision, moldability, etc., metal or inorganic materials may be more advantageous than resin materials. By replacing some of the metal or inorganic materials with resin materials, it is possible to manufacture lightweight systems and devices while maintaining processability, processing precision, moldability, etc.

The above-mentioned joint in which PEEK resin and metal oxide are joined, and the composite material containing metal oxide with PEEK resin as the base material can be used for appropriate purposes such as implants and non-implant applications. In Figures 1 and 2, the joint 1 forms an interbody cage, but the joint 1 may be used for other implants or non-implants.

Applications for implants include orthopedic implants related to the spine, such as interbody cages and pedicle screws, orthopedic implants other than those related to the spine, such as artificial joints, artificial bone shafts, and internal fixation devices for fractures, as well as ophthalmic implants such as plates, medical implants such as cosmetic surgery implants, and dental implants such as artificial tooth roots.

Applications other than implants include structural materials for mobile objects, and structural materials and parts for machines and equipment. Mobile objects include automobiles, heavy machinery, railroad cars, motorcycles, bicycles, wheelchairs, elevators, ships, submarines, aircraft, helicopters, drones, rockets, artificial satellites, space probes, space stations, and space elevators. Machines and equipment include those that are installed outdoors, as well as those that require light weight, yield strength, UV resistance, heat resistance, impact resistance, etc.

Next, to confirm the mechanism of action of metal oxides that align the atomic arrangement of PEEK resin, we compare the atomic arrangement of PEEK resin without metal oxide with that of PEEK resin with metal oxide.

Atomic arrangements were analyzed using molecular dynamics simulations combined with density functional theory (DFT), as described in Non-Patent Document 1 (R. Car, M. Parrinello (1985). Unified Approach for Molecular Dynamics and Density-Functional Theory. PHYSICAL REVIEW LETTERS. VOLUME 55, NUMBER 22, 2471-2474). In molecular dynamics simulations combined with DFT, the structure of the target substance is represented by an electron density functional, and the coordinates of each constituent atom at each time can be calculated using the molecular orbitals and energy obtained from the equation of motion.

Figure 10 shows the results of an analysis of the atomic arrangement of PEEK resin that does not use metal oxide. Figure 10 shows an example of the atomic arrangement of PEEK resin when no metal oxide, which acts to align the atomic arrangement of PEEK resin, is dispersed or bonded. In Figure 10, the gray spheres indicated by the reference numeral 401 represent carbon atoms, the black spheres indicated by the reference numeral 402 represent oxygen atoms, and the white spheres indicated by the reference numeral 403 represent hydrogen atoms.

As shown in Figure 10, if a metal oxide that acts to align the atomic arrangement of PEEK resin is not dispersed or bonded, the molecular chains of PEEK resin will have irregular orientation and conformation. Even if a crystalline phase is formed by the molecular chains of PEEK resin, the state will be poorly ordered. In such a state, the interaction between the molecular chains of PEEK resin will be weak, and high adhesion strength will not be obtained.

Fig. 11 is a diagram showing the results of an analysis of the atomic arrangement of PEEK resin using titanium oxide. Fig. 11 shows the results of PEEK resin bonded with rutile titanium oxide (TiO ₂ ) as a metal oxide. The upper diagram in Fig. 11 is a diagram showing the interface between the PEEK resin and the metal oxide as viewed from the side, and the lower diagram is a diagram showing the interface between the PEEK resin and the metal oxide as viewed from below. The interface between the PEEK resin and the metal oxide is the (110) plane of the rutile titanium oxide.

In FIG. 11, the large gray spheres indicated by the reference numeral 401 represent carbon atoms of PEEK resin, the large black spheres indicated by the reference numeral 402 represent oxygen atoms of PEEK resin, the large white spheres indicated by the reference numeral 403 represent hydrogen atoms of PEEK resin, the small gray spheres indicated by the reference numeral 501 represent titanium atoms of titanium oxide, the small black spheres indicated by the reference numeral 502 represent oxygen atoms of titanium oxide, and the hexagons indicated by the reference numeral 503 represent ring structures formed on the (110) surface of rutile-type titanium oxide.

As shown in Figure 11, PEEK resin has a molecular structure in which multiple benzene rings are linked via ether groups or ketone groups. The distance between the centers of the benzene rings linked via ether groups in PEEK resin is approximately 0.5719 nm.

On the other hand, rutile titanium oxide has an eight-membered ring structure formed by titanium atoms and oxygen atoms when viewed from a direction perpendicular to the (110) plane. The distance between the second nearest neighbor titanium atoms on the same line that form the ring structure is approximately 0.5918 nm.

The relative difference between the spacing between benzene rings of PEEK resin, which is approximately 0.5719 nm, and the spacing between second nearest neighbor titanium atoms that constitute the crystal structure of rutile titanium oxide, which is approximately 0.5918 nm, is approximately 3.48%. The benzene rings of the PEEK resin and the ring structure 503 formed on the (110) surface of titanium oxide are aligned and overlapped with equal spacing.

With this type of combination, the relative difference between the spacing between the benzene rings that make up the molecular chains of the PEEK resin and the spacing between the metal atoms that make up the crystal structure of the metal oxide becomes smaller. Specific atoms are periodically arranged between the PEEK resin and the titanium oxide, forming a lattice-matched interface. It can be seen that the benzene rings of the PEEK resin and the ring structure of the titanium oxide are stabilized in close proximity to each other, forming a strong interaction.

Fig. 12 is a diagram showing the results of an analysis of the atomic arrangement of PEEK resin using aluminum oxide. Fig. 12 shows the results of PEEK resin bonded with aluminum oxide (Al ₂ O ₃ ) as a metal oxide. The upper diagram in Fig. 12 is a diagram showing the interface between the PEEK resin and the metal oxide as viewed from the side, and the lower diagram is a diagram showing the interface between the PEEK resin and the metal oxide as viewed from below. The interface between the PEEK resin and the metal oxide is the (001) plane of the aluminum oxide.

In FIG. 12, the large gray spheres indicated by the reference numeral 401 represent carbon atoms of the PEEK resin, the large black spheres indicated by the reference numeral 402 represent oxygen atoms of the PEEK resin, the large white spheres indicated by the reference numeral 403 represent hydrogen atoms of the PEEK resin, the small gray spheres indicated by the reference numeral 601 represent aluminum atoms of aluminum oxide, the small black spheres indicated by the reference numeral 602 represent oxygen atoms of aluminum oxide, and the hexagons indicated by the reference numeral 603 represent ring structures formed on the (001) plane of aluminum oxide.

As shown in Figure 12, PEEK resin has a molecular structure in which multiple benzene rings are linked via ether groups or ketone groups. The distance between the centers of the benzene rings linked via ether groups in PEEK resin is approximately 0.5719 nm.

On the other hand, aluminum oxide has a six-membered ring structure formed by aluminum atoms and oxygen atoms when viewed from a direction perpendicular to the (001) plane. Among the aluminum atoms that form the ring structure, the distance between the second nearest neighboring aluminum atoms on the same line is approximately 0.5517 nm.

The relative difference between the spacing between benzene rings of PEEK resin, which is about 0.5719 nm, and the spacing between second nearest neighboring aluminum atoms that make up the crystal structure of aluminum oxide, which is about 0.5517 nm, is about 3.53%. The benzene rings of the PEEK resin and the ring structure 603 formed on the (001) surface of the aluminum oxide are aligned and overlapped with equal spacing.

With this type of combination, the relative difference between the spacing between the benzene rings that make up the molecular chains of the PEEK resin and the spacing between the metal atoms that make up the crystal structure of the metal oxide becomes smaller. Specific atoms are periodically arranged between the PEEK resin and the aluminum oxide, forming a lattice-matched interface. It can be seen that the benzene rings of the PEEK resin and the ring structure of the aluminum oxide are stabilized in close proximity to each other.

Figure 13 shows the results of an analysis of the atomic arrangement of PEEK resin using magnesium oxide. Figure 13 shows the results for PEEK resin bonded with magnesium oxide (MgO) as a metal oxide. The top figure in Figure 13 is a side view of the interface between the PEEK resin and the metal oxide, and the bottom figure is a bottom view of the interface between the PEEK resin and the metal oxide. The interface between the PEEK resin and the metal oxide is the (111) plane of the magnesium oxide.

In FIG. 13, the large gray spheres indicated by the reference numeral 401 represent carbon atoms of the PEEK resin, the large black spheres indicated by the reference numeral 402 represent oxygen atoms of the PEEK resin, the large white spheres indicated by the reference numeral 403 represent hydrogen atoms of the PEEK resin, the small gray spheres indicated by the reference numeral 701 represent magnesium atoms of magnesium oxide, the small black spheres indicated by the reference numeral 702 represent oxygen atoms of magnesium oxide, and the hexagons indicated by the reference numeral 703 represent ring structures formed on the (111) plane of magnesium oxide.

As shown in Figure 13, PEEK resin has a molecular structure in which multiple benzene rings are linked via ether groups or ketone groups. The distance between the centers of the benzene rings linked via ether groups in PEEK resin is approximately 0.5719 nm.

On the other hand, magnesium oxide has a six-membered ring structure formed by magnesium atoms and oxygen atoms when viewed from a direction perpendicular to the (111) plane. Among the magnesium atoms that form the ring structure, the distance between the magnesium atoms that are second nearest neighbors on the same line is approximately 0.5956 nm.

The relative difference between the spacing between benzene rings of the PEEK resin, which is approximately 0.5719 nm, and the spacing between second nearest neighboring magnesium atoms that make up the crystal structure of magnesium oxide, which is approximately 0.5956 nm, is approximately 4.14%. The benzene rings of the PEEK resin and the ring structure 703 formed on the (111) surface of magnesium oxide are aligned and overlapped with equal spacing.

With this combination, the relative difference between the spacing between the benzene rings that make up the molecular chain of the PEEK resin and the spacing between the metal atoms that make up the crystal structure of the metal oxide becomes smaller. Specific atoms are periodically arranged between the PEEK resin and the magnesium oxide, forming a lattice-matched interface. It can be seen that the benzene rings of the PEEK resin and the ring structure of the magnesium oxide are stabilized in close proximity to each other.

As shown in the upper diagrams of Figures 11, 12, and 13, when PEEK resin and metal oxide are bonded together, the base material formed from PEEK resin forms a regular atomic arrangement, compared to when no metal oxide is used. It can be seen that metal oxide, which acts to align the atomic arrangement of PEEK resin, acts not only on the interface between PEEK resin and metal oxide, but also on the molecular chains of PEEK resin in areas away from the interface.

Tables 4 to 6 show the calculation results of the atomic density [atoms/nm ² ] and peel energy [J/m ² ] of the metal oxide at the interface between the PEEK resin and the metal oxide. The atomic density and peel energy of the metal oxide were derived by determining the peel energy function by response surface methodology using data calculated by molecular dynamics simulation combined with density functional theory (DFT).

As shown in Table 4, the peel energy at the interface between PEEK resin and rutile titanium oxide was more than twice as high when the interface was the (110) plane compared to the (100), (001), and (111) planes. A similar tendency to the actual measurement results from the peel test shown in Table 1 was also confirmed by molecular orbital calculations using DFT.

When hafnium is added to rutile titanium oxide at 8 at%, the relative difference between the spacing between the benzene rings of the PEEK resin and the spacing between the titanium atoms of the titanium oxide is 5.03%. In this case, the peel energy at the interface between the PEEK resin and the titanium oxide is reduced by approximately 39%. Therefore, it is preferable that the relative difference between the spacing between the benzene rings of the PEEK resin and the spacing between the titanium atoms of the titanium oxide is 5% or less.

As shown in Table 5, the peel energy at the interface between PEEK resin and aluminum oxide was more than twice as high when the interface was the (001) plane compared to the (100), (110), and (210) planes. A similar tendency to the actual measurement results from the peel test shown in Table 2 was also confirmed by molecular orbital calculations using DFT.

When gallium is added to aluminum oxide to make up 12 at%, the relative difference between the spacing between benzene rings in the PEEK resin and the spacing between aluminum atoms in the aluminum oxide is 5.02%. In this case, the peel energy at the interface between the PEEK resin and the aluminum oxide is reduced by approximately 37%. Therefore, it is preferable that the relative difference between the spacing between benzene rings in the PEEK resin and the spacing between aluminum atoms in the aluminum oxide be 5% or less.

As shown in Table 6, the peel energy at the interface between PEEK resin and magnesium oxide was more than 1.5 times higher when the interface was the (111) plane compared to the (100), (001), and (110) planes. A similar tendency to the measured results from the peel test shown in Table 3 was also confirmed by molecular orbital calculations using DFT.

When calcium is added to magnesium oxide to make up 9 at %, the relative difference between the spacing between benzene rings in the PEEK resin and the spacing between magnesium atoms in the magnesium oxide is 5.04%. In this case, the peel energy at the interface between the PEEK resin and magnesium oxide is reduced by approximately 32%. Therefore, it is preferable that the relative difference between the spacing between benzene rings in the PEEK resin and the spacing between magnesium atoms in the magnesium oxide is 5% or less.

However, even if the relative difference between the spacing between benzene rings in the PEEK resin and the spacing between metal atoms in the metal oxide is 5% or less, if the atomic density of the metal oxide adjacent to the PEEK resin is small, the total interaction is not strong, and the adhesive strength between the PEEK resin and the metal oxide is low.

For example, in the case of the (111) plane of rutile titanium oxide, the relative difference between the spacing between benzene rings of PEEK resin and the spacing between second nearest neighbor titanium atoms of rutile titanium oxide is about 4.46%. However, the atomic density of the metal oxide on the (111) plane is small at 12.3 atoms/ ^nm2 . In such a case, the peel energy at the interface between the PEEK resin and the metal oxide is also small at 0.248 J/ ^m2 .

Therefore, in order to increase the adhesive strength between PEEK resin and metal oxide, it is important to keep the relative difference between the spacing between the benzene rings that make up the molecular chain of PEEK resin and the spacing between the metal atoms that make up the crystal structure of the metal oxide to 5% or less, and to increase the atomic density of the metal oxide at the interface between the PEEK resin and the metal oxide.

Additive elements may be added to the metal oxide, and impurity elements may be included that are inevitably mixed in. If the additive elements or impurity elements are about 1 wt% or less, lattice mismatch is suppressed, and the adhesive strength between the PEEK resin and the metal oxide can be improved. Doping with dissimilar metal atoms that replace some of the metal atoms, which are the main component, may make it possible to adjust the spacing between the metal atoms.

When titanium oxide is used as the metal oxide, it is preferable to include an element having an atomic radius smaller than that of titanium as an additive element or impurity element. Examples of such elements include aluminum and vanadium.

The average atomic spacing between titanium atoms in pure titanium oxide is larger than the spacing between benzene rings in PEEK resin. By including an element with an atomic radius smaller than that of titanium, the average atomic spacing of titanium oxide can be reduced, further reducing the lattice mismatch. For example, using a composite oxide containing 90 wt% Ti, 6 wt% Al, and 4 wt% V, the lattice mismatch is zero, and the adhesive strength between the PEEK resin and the metal oxide is increased.

When aluminum oxide is used as the metal oxide, it is preferable that the additive elements and impurity elements include elements with an atomic radius larger than that of aluminum. Examples of such elements include magnesium and titanium.

The average atomic spacing between aluminum atoms in pure aluminum oxide is smaller than the spacing between benzene rings in PEEK resin. By including an element with an atomic radius larger than that of aluminum, the average atomic spacing in aluminum oxide can be increased, further reducing the lattice mismatch. For example, using a composite oxide containing 98.5 wt% Al and 1.5 wt% Mg, the lattice mismatch is zero, and the adhesive strength between the PEEK resin and the metal oxide is increased.

When magnesium oxide is used as the metal oxide, it is preferable that the additive elements and impurity elements include elements with an atomic radius smaller than that of magnesium. Examples of such elements include aluminum.

The average atomic spacing between magnesium atoms in pure magnesium oxide is larger than the spacing between benzene rings in PEEK resin. By including an element with an atomic radius smaller than that of magnesium, the average atomic spacing of magnesium oxide can be reduced, further reducing the lattice mismatch. For example, using a composite oxide containing 90 wt% Mg and 10 wt% Al reduces the lattice mismatch to zero, increasing the adhesive strength between the PEEK resin and the metal oxide.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are included as long as they do not deviate from the technical scope. For example, the above-described embodiments are not necessarily limited to those having all of the configurations described. It is also possible to replace part of the configuration of an embodiment with another configuration, or to add another configuration to the configuration of an embodiment. It is also possible to add other configurations to, delete configurations, or replace configurations with respect to part of the configuration of an embodiment.

For example, the bonded body 1 is bonded to the metal oxide 3, but in a bonded body in which PEEK resin and a metal oxide are bonded to each other, the metal oxide may be bonded to another metal together with the PEEK resin. As in the case of the composite material 14, such a metal oxide can be formed by a method of thermally oxidizing a part of the surface side of the metal or a method of forming a film on the surface of the metal.

1...Conjugate, 2,8...PEEK resin, 3,9,15...Metal oxide, 4...Vertebral body, 5...Intervertebral disc, 6...Bone marrow, 7,14...Composite material, 10,11,12,13...Crystal surface, 16...Metal, 101,201,301...Interface, 102...HAp film, 401...Carbon atom, 402...Oxygen atom, 403...Hydrogen atom, 501...Titanium atom, 601...Aluminum atom, 701...Magnesium atom, 502,602,702...Oxygen atom, 503,603,703...Ring structure

Claims (15)

A bonded body in which a polyether ether ketone resin and a metal oxide are bonded together,
a relative difference between a distance between benzene rings constituting a molecular chain of the polyether ether ketone resin and a distance between metal atoms constituting a crystal structure of the metal oxide is 5% or less;
A bonded body, wherein the atomic density on the crystal plane of the metal oxide to which the polyether ether ketone resin is bonded is 17 atoms/ ^nm2 or more. The joint body according to claim 1 ,
The metal oxide is _TiO2 ,
A bonded body, wherein the crystal plane to which the polyether ether ketone resin is bonded is a (110) plane of _TiO2 having a rutile structure. The joint body according to claim 1 ,
The metal _oxide is _Al2O3 ,
A bonded body, wherein the crystal face to which the polyether ether ketone resin is bonded is a ( ₀₀₁ ) face of _Al2O3 . The joint body according to claim 1 ,
The metal oxide is MgO,
A bonded structure, wherein the crystal face to which the polyether ether ketone resin is bonded is a (111) face of MgO. A composite material containing a metal oxide and a polyether ether ketone resin as a base material,
A composite material in which the relative difference between the distance between benzene rings constituting the molecular chain of the polyether ether ketone resin and the distance between metal atoms constituting the crystal structure of the metal oxide is 5% or less. 6. The composite material of claim 5,
The metal oxide is _TiO2 ,
A composite material, wherein 57% or more of the surface of the metal oxide in contact with the polyetheretherketone resin is a (110) plane of _TiO2 having a rutile structure. 6. The composite material of claim 5,
A composite material in which _TiO2 is bonded to the surface of the polyetheretherketone resin. 6. The composite material of claim 5,
The metal _oxide is _Al2O3 ,
A composite material, wherein 57% or more of the surface of the metal oxide in contact with the polyetheretherketone resin is _{an Al2O3} (001) plane. 6. The composite material of claim 5,
A composite material _in which _Al2O3 is bonded to the surface of the polyether ether ketone resin. 6. The composite material of claim 5,
The metal oxide is MgO,
A composite material in which 57% or more of the surface of the metal oxide in contact with the polyetheretherketone resin is a (111) plane of MgO. 6. The composite material of claim 5,
A composite material in which MgO is bonded to a surface of the polyether ether ketone resin. An implant formed from the joint body according to any one of claims 1 to 4. A structural material for medical, aerospace or vehicle applications formed from the composite material according to any one of claims 5 to 11. A method for producing a bonded body in which a polyether ether ketone resin and a metal oxide are bonded, comprising the steps of:
forming a metal oxide film on a surface of a polyether ether ketone resin;
and a step of heat-treating the polyether ether ketone resin on which the metal oxide film has been formed to improve the crystal orientation of the metal oxide,
a relative difference between a distance between benzene rings constituting a molecular chain of the polyether ether ketone resin obtained in the step of improving crystal orientation and a distance between metal atoms constituting a crystal structure of the metal oxide is 5% or less;
The method for producing a bonded body, wherein the atomic density on the crystal plane of the metal oxide to which the polyether ether ketone resin is bonded is 17 atoms/ ^nm2 or more. A method for producing a composite material containing a metal oxide and a polyether ether ketone resin as a base material, comprising the steps of:
heating and kneading a mixture of a polyether ether ketone resin and a metal oxide;
and a step of hot molding the resin composition obtained in the heating and kneading step to improve the crystal orientation of the metal oxide.
A composite material in which the relative difference between the spacing between benzene rings constituting the molecular chain of the polyether ether ketone resin obtained in the process of improving crystal orientation and the spacing between metal atoms constituting the crystal structure of the metal oxide is 5% or less.

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