Molding Method of Polylactic Resin
In order to provide a molding method of polylactic resin by which a container or package having a transparent part can be fabricated with high heat resistance, polylactic resin is injected into a cavity, vibrations are added to the polylactic resin while a screw is kept at a charging completion position, and the process is switched to a pressure holding process after the addition of vibrations is completed.
1 . A molding method of polylactic resin, comprising:
charging molten polylactic resin into a cavity formed of molds;
adding vibrations to the polylactic resin having been injected into the cavity, when the polylactic resin having been injected into the cavity has a temperature ranging from a glass transition point to a melting point of the polylactic resin; and
applying a held pressure to the polylactic resin in the cavity after addition of vibrations is completed.
2 . The molding method of polylactic resin according to claim 1 , wherein the temperature at which the vibrations are added to the polylactic resin having been injected into the cavity ranges from 100° C. to a temperature at which charging of the polylactic resin is completed.
3 . The molding method of polylactic resin according to claim 1 , wherein the vibrations at 10 kHz to 100 kHz are added.
4 . The molding method of polylactic resin according to claim 1 , wherein the vibrations are added on positions for accelerating crystallization of the polylactic resin having been injected into the cavity.
5 . The molding method of polylactic resin according to claim 4 , wherein the vibrations are added on the positions corresponding to an outer wall of a molded body formed of the polylactic resin having been injected into the cavity.
6 . The molding method of polylactic resin according to claim 1 , further comprising: forming paint containing a crystal nucleating agent on mold surfaces forming the cavity.
7 . The molding method of polylactic resin according to claim 6 , wherein the crystal nucleating agent is one of talc, kaoline, silica, and boron nitride.
8 . A molding method of polylactic resin, comprising:
charging molten polylactic resin into molds on which paint containing a crystal nucleating agent is formed, the paint being formed on mold surfaces forming a cavity for molding a molded body; and
holding the injected polylactic resin by the molds.
9 . The molding method of polylactic resin according to claim 8 , wherein the injected polylactic resin is held by the molds while vibrations are added to the mold.
10 . The molding method of polylactic resin according to claim 8 , wherein the crystal nucleating agent is one of talc, kaoline, silica, and boron nitride.