Method for preparing a composite of metal and resin
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 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 for providing said shaped substrate with an ultrafine textured face in which protrusions with a height, width and length of at least 10 nm rise up at a spacing of at least 10 nm in observation with an electron microscope on a face that has a surface roughness made up of a 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 chemical etching 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 the first resin composition or the second resin composition;
said first resin composition being one in which a polyphenylene sulphide resin as the main component is contained by 70 to 97 wt % as resin components and a polyolefin resin as an auxiliary component is contained by 3 to 30 wt % as resin components, and
said second resin composition being one in which a polybutylene terephthalate resin as the main component is contained by 70 to 97 wt % as resin components and a polyethylene terephthalate resin and/or a polyolefin resin as an auxiliary component/components is/are contained by 3 to 30 wt % as resin components.
2. The method according to claim 1 , wherein in the integration step, the first resin composition is injected onto said inserted substrate.
3. The method according to claim 1 , wherein the composite of the metal and the resin has a shear breaking strength between 8 MPa and 26.5 MPa.
4. The method according to claim 2 , wherein the composite of the metal and the resin has a shear breaking strength between 8 MPa and 25 MPa.