Method of molding glass parts and molding apparatus

1. A method of molding a glass material, comprising the steps of;

heating a glass material and a molding die with a heater; applying a voltage across the glass material and the molding die while the glass material and the molding die are being held in contact with each other;

wherein a negative direct-current voltage is applied to the glass material via an electrode in contact with the glass material, and wherein a positive direct-current voltage is applied to the molding die, and

performing glass material pressure-molding by electrostatic attraction generated between a surface of the glass material and a surface of the molding die to produce a molded glass product with a lowered concentration of an alkali metal in a molded surface of the molded glass product.

2. The method of molding a glass material according to claim 1 , wherein the glass material contains a mobile ion.

3. The method of molding a glass material according to claim 2 , wherein the glass material comprises silicon dioxide as a main component, and lithium, sodium or potassium corresponding to an alkali metal as the mobile ion.

4. The method of molding a glass material according to claim 1 , wherein the temperature T for heating the glass material and the molding die is within a range of: (T g −150)° C. <T <(T g +100)° C. (in which “T g ” represents a glass transition temperature of the glass material).

5. The method of molding a glass material according to claim 1 , wherein the applied voltage is 10 V or larger and 10,000 V or less.

6. The method of molding a glass material according to claim 1 , further comprising a step of applying a pressure to the glass material and the molding die after the step of heating the glass material and the molding die.

7. The method of molding a glass material according to claim 6 , wherein the applied pressure is 100 Pa or larger and 1 MPa or smaller.

8. The method of molding a glass material according to claim 1 , wherein the molding is performed in a vacuum, a nitrogen gas atmosphere or an inert gas atmosphere.

9. The method of molding a glass material according to claim 1 , wherein a positive direct-current voltage is applied to the glass material and a negative direct-current voltage is applied to the molding die, prior to release of the molding die after the molding.

10. The method of molding a glass material according to claim 1 , wherein an alternating-current voltage is applied across the glass material and the molding die, prior to the release of the molding die after the molding.

11. The method of molding a glass material according to claim 9 , wherein the heating temperature T 1 at the time of applying the voltage is within a range of: (T g −150)° C.<T 1 <T g ° C. (in which “T g ” represents a glass transition temperature of the glass material).

12. The method of molding a glass material according to claim 10 , wherein the heating temperature T 1 at the time of applying the voltage is within a range of: (T g −150)° C.<T 1 <T g ° C. (in which “T g ” represents a glass transition temperature of the glass material).

13. A molding apparatus of a glass material, comprising: means for holding a glass material and a molding die in contact with each other;

means for heating the glass material and the molding die; and

means for applying a voltage across the glass material and the molding die comprising a positive electrode connected to the molding die and a negative electrode connected to the glass material, wherein the negative electrode is brought into contact with an entire surface of the glass material on a side opposite to a surface which is to be molded; and

wherein press-molding is performed by electrostatic attraction acting between a surface of the glass material and a surface of the molding die to produce a molded glass product with a lowered concentration of an alkali metal in a molded surface of the molded glass product.

14. The molding apparatus of a glass material according to claim 13 , wherein a conductive film formed on a surface on a side opposite to a surface, which is to be molded, of the glass material is employed as an electrode for performing electrical connection to the glass material.

15. The molding apparatus of a glass material according to claim 13 , wherein the molding die is a conductor.

16. The molding apparatus of a glass material according to claim 15 , wherein the molding die is formed of a material containing any one of platinum, iridium, rhodium, osmium and ruthenium as a main component, or a material containing a mixture of at least two of the materials as a main component.

17. The molding apparatus of a glass material according to claim 15 , wherein a thin film made of a material containing any one of platinum, iridium, rhodium, osmium and ruthenium as a main component, or a material containing a mixture of at least two of the materials as a main component, is formed on a surface of the molding die.

18. The molding apparatus of a glass material according claim 13 , wherein a depth of a molding pattern of the molding die is 1 μm or less.

19. The molding apparatus of a glass material according to claim 13 , comprising means for reversing polarity of the voltage applied to the glass material and the molding die.

20. The molding apparatus of a glass material according to claim 13 , comprising means for holding the glass material and the molding die with pressing force.

21. The molding apparatus of a glass material according to claim 20 , wherein an applied pressure at the time of holding with pressing force is 100 Pa or larger and 1 MPa or smaller.

22. The molding apparatus of a glass material according to claim 13 , comprising a vacuum chamber for performing the molding in a vacuum or an atmosphere-controlling chamber for performing the molding in various gas atmospheres.