Composite of metal and resin and method for manufacturing the same

Abstract

It is an object of the present invention to securely and integrally join a metal and a resin, more particularly, a shaped titanium alloy substrate and a resin composition. A titanium alloy substrate is used that has undergone surface roughening by chemical etching or the like so as to have a ultrafine textured face in which bent, ridge-like protrusions having a width and height of from ten to a few hundred nanometers and a length of from a few to a few hundred microns rise up on the surface at a spacing period of from ten to a few hundred nanometers. A titanium alloy piece 1 with its surface treated is inserted into the cavity of a metallic mold for injection molding 10 and a specific resin composition 4 is injected to obtain an integrated composite 7 . The main resin component of the resin composition 4 that is used can be a polyphenylene sulfide resin (PPS) or a polybutylene terephthalate resin (PBT). High injection joining strength is obtained if the resin composition contains, as an auxiliary component, a polyethylene terephthalate resin and/or polyolefin resin in the case of PBT and a polyolefin resin in the case of PPS.

1 . A composite of metal and resin, comprising:
 a titanium alloy substrate that has been machined into a specific shape and then chemically etched so as to have an ultrafine textured face in which bent, ridge-like protrusions having a width and height of from ten to a few hundred nanometers and a length of from a few to a few hundred microns rise up on the surface at a spacing period of from ten to a few hundred nanometers and so as to have a surface in which a surface roughness with a mean width of profile elements (RSm) of 1 to 10 μm and a maximum height of roughness (Rz) of 0.5 to 5 μm is observed; and   a first resin composition whose main component is a polyphenylene sulfide resin or a second resin composition whose main component is a polybutylene terephthalate resin, which is directly joined by injection molding to the titanium alloy substrate.   
     
     
         2 . A composite of metal and resin, comprising:
 a titanium alloy substrate that has been machined into a specific shape and then chemically etched so as to have a surface in which a surface roughness with a mean width of profile elements (RSm) of 1 to 10 μm and a maximum height of roughness (Rz) of 0.5 to 5 μm is observed and so as to have a ultrafine textured face in which are observed both smooth dome-like shapes and dead leaf-like shapes within a surface area measuring 10 μm square; and   a first resin composition whose main component is a polyphenylene sulfide resin or a second resin composition whose main component is a polybutylene terephthalate resin, which is directly joined by injection molding to the titanium alloy substrate.   
     
     
         3 . The composite of metal and resin according to any of  claim 1  or  2 , wherein the resin component of said first resin composition is a resin composition in which the polyphenylene sulfide resin is the main component and a polyolefin resin is an auxiliary component. 
     
     
         4 . The composite of metal and resin according to any of  claim 1  or  2 , wherein the resin component of said second resin composition is a resin composition in which the polybutylene terephthalate resin is the main component and a polyethylene terephthalate resin and/or a polyolefin resin is an auxiliary component. 
     
     
         5 . The composite of metal and resin according to any of  claims 1  to  4 , wherein the surface of said substrate is covered with a thin film that is thicker than a natural oxidized film. 
     
     
         6 . The composite of metal and resin according to  claim 5 , wherein said thin film is of titanium oxide. 
     
     
         7 . The composite of metal and resin according to  claim 3 , wherein said first resin composition contains polyphenylene sulfide resin by 70 to 97 wt % and polyolefin resin by 3 to 30 wt %. 
     
     
         8 . The composite of metal and resin according to  claim 4 , wherein said second resin composition contains polybutylene terephthalate resin by 70 to 97 wt % and polyethylene terephthalate resin and/or polyolefin resin by 3 to 30 wt %. 
     
     
         9 . The composite of metal and resin according to any of  claims 1  to  8 , wherein said first resin composition or said second resin composition contains at least one type of filler selected from among glass fiber, carbon fiber, aramid fiber, other reinforcing fiber, calcium carbonate, magnesium carbonate, silica, talc, clay and glass powder, in an amount of 20 to 60 wt %. 
     
     
         10 . A method for manufacturing a composite of metal and resin, comprising:
 a shaping step of shaping a titanium alloy substrate by mechanical working;   a surface treatment step including chemical etching for providing the surface of said shaped substrate with a ultrafine textured face in which protrusions with a height, width and length of at least 10 nm rise up at a spacing period of at least 10 nm in observation with an electron microscope and which a surface roughness made up of the textured face with a maximum height of roughness of 0.5 to 5 μm at a period of 1 to 10 μm;   an insertion step of inserting said substrate that has undergone said surface treatment including chemical etching into a metallic mold for injection molding; and   an integrating step of injecting a first resin composition or a second resin composition onto said inserted substrate and integrating said substrate with said first resin composition or said second resin composition,   said first resin composition being one in which a polyphenylene sulfide resin is the main component and a polyolefin resin is an auxiliary component, and   said second resin composition being one in which a polybutylene terephthalate resin is the main component and a polyethylene terephthalate resin and/or a polyolefin resin is an auxiliary component.   
     
     
         11 . A method for manufacturing a composite of metal and resin, comprising:
 a shaping step of shaping a titanium alloy substrate by mechanical working;   a surface treatment step including chemical etching for providing the surface of said shaped substrate with a ultrafine textured face in which are observed both smooth dome-like shapes and dead leaf-like shapes within a surface area measuring 10 μm square and which a surface roughness with mean width of profile elements (RSm) of 1 to 10 μm and maximum height of roughness (Rz) of 1 to 5 μm in observation with a scanning probe microscope;   an insertion step inserting said substrate that has undergone said surface treatment including chemical etching into an metallic mold for injection molding; and   an integrating step of injecting a first resin composition or a second resin composition onto said inserted substrate and integrating said substrate with said first resin composition or said second resin composition,   said first resin composition being one in which a polyphenylene sulfide resin is the main component and a polyolefin resin is an auxiliary component, and   said second resin composition being one in which a polybutylene terephthalate resin is the main component and a polyethylene terephthalate resin and/or a polyolefin resin is an auxiliary component.   
     
     
         12 . A method for manufacturing a composite of metal and resin, comprising:
 a shaping step of shaping a titanium alloy substrate by mechanical working;   a chemical etching step of immersing said shaped substrate in an aqueous solution containing ammonium monohydrodifluoride and rinsing the same with water;   an insertion step of inserting said chemically etched substrate into a metallic mold for injection molding; and   an integration step of injecting a first resin composition or a second resin composition onto said inserted substrate and integrating said substrate with said first resin composition or said second resin composition,   said first resin composition being one in which a polyphenylene sulfide resin is the main component and a polyolefin resin is an auxiliary component, and   said second resin composition being one in which a polybutylene terephthalate resin is the main component and a polyethylene terephthalate resin and/or a polyolefin resin is an auxiliary component.