Resin bonding method by photoirradiation, method for producing resin article, resin article produced by the same method, method for producing microchip, and microchip produced by the same method

A resin article comprising a plurality of parts including resin portions, the plurality of parts being bonded together through the resin portions,

• wherein the resin portions are bonded to each other by a method for bonding a first resin and a second resin, the method comprising the steps of:
• (I) irradiating a space containing oxygen molecules with vacuum ultraviolet light having a wavelength of 175 nm or smaller, the space being adjacent to a first surface of the first resin and a second surface of the second resin, the irradiating reducing irregularities of the first and second surfaces while maintaining certain surface roughness of the first and second surfaces;
• and
• (II) after the irradiating, placing the first surface and the second surface in contact with each other, and increasing a temperature such that the first resin and the second resin are bonded to each other via the first and second surfaces serving as bonding surfaces,
• wherein the certain surface roughness of the first and second surfaces allows the first and second resins to become separable from each other if at least one liquid selected from water and alcohol at a temperature of 40° C. or greater is applied, or the liquid at a temperature less than 40° C. in combination with ultrasonic vibrations is applied.