Metal mold, process for manufacturing the same, and molded article produced using the mold

#The disclosure relates to a mold having a releasable composite film formed on a surface thereof.

#Note that a mold as described herein relates to a releasable mold used for molding optical parts, machine parts, recording media, electronic parts, biochemical chips, medical supplies, and the like in which a release agent cannot be used to maintain precision, and to a releasable mold to which a release agent cannot be applied because it is disadvantageous if the release agent adheres to a molded article.

#Generally, it has been already well-known that a chemisorption solution comprising a chlorosilane-based adsorbent containing a fluorocarbon group and a non-aqueous organic solvent can be used to effect chemisorption in a liquid phase so as to form a water-repellent chemisorbed film in the form of a monomolecular film (for example, refer to Japanese Patent Laid-Open No. 05-193056).

#FIG. 1 is a conceptual diagram of a section (a) of a conventional mold and a section (b) of the mold of the present invention, wherein (a) shows the state where a release agent is applied to the surface of the mold, and (b) shows the state where a releasable monomolecular film is formed on the surface of the mold;

#FIG. 2 is a conceptual diagram in which the section of the mold on which a releasable composite film is formed in Example 1 is enlarged to the molecular level;

#FIG. 3 is a drawing showing the test results of abrasion resistance in terms of the variation of the water drop contact angle of the releasable mold obtained in Example 1 of the present invention in comparison with those of the releasable mold obtained in Comparative Examples 1 and 2; and

#As for the improvement of the mold releasability in molding with a mold, emphasis has been put on the shape of the mold itself or improvement of a release agent. However, with respect to molding with a mold requiring nanoscale precision, such as the molding of optical parts, a conventional method based on geometrical improvement or spraying of a release agent causes a variation of about several-ten to several-hundred nanometers in the film thickness of the release agent 2 applied to the surface of the mold 1, as shown in FIG. 1A. Such a method is not optimal because the variation of the mold is generated in every molding. Further, adhesion of a release agent to a molded article may often produce disadvantages. However, a high precision mold using no release agent is not yet put in practical use.

#On the other hand, conventional chemisorbed films involve only the chemical bond between an adsorbent and a substrate surface. Therefore, such a chemisorbed film is poor in abrasion resistance when it is used for a mold as it is. Further, there was a problem of reduction in penetrating fluidity and penetrativity of a molding material due to an excessively small surface energy when a monomolecular film made only of a fluorocarbon-based material is used.

#The present technological advancement has been made in the light of the above problem, and an object of the technological advancement is to provide a mold requiring no release agent which does not impair a processed shape of a high precision mold, has a proper mold releasing function controlling surface energy, and has high molding durability.