초록 ▼

A method and apparatus for making a partially crystalline, biaxially oriented heat set hollow plastic container from a hollow parison having an open end and a closed end including engaging the open end of a plastic parison which is at a temperature within its molecular orientation temperature range,

A method and apparatus for making a partially crystalline, biaxially oriented heat set hollow plastic container from a hollow parison having an open end and a closed end including engaging the open end of a plastic parison which is at a temperature within its molecular orientation temperature range, enclosing the hot parison in a hot mold, which is at heat setting temperature, expanding the plastic parison within the hot mold by internal pressurization to induce biaxial orientation of the plastic parison and to induce partial crystallization in the biaxially oriented container, exhausting the blow molding fluid while continuously introducing a cooling fluid such as liquid carbon dioxide into the biaxially oriented container and continuously removing the cooling fluid while the hot mold is closed for a period of time, opening the hot mold while continuing to introduce, circulate and remove coolant fluid for a predetermined period of time until the container is cooled sufficiently to prevent significant shrinkage and finally releasing the container.

대표청구항 ▼

In a method for making a partially crystalline, biaxially oriented, heat set plastic container from a hollow polyethylene terephthalate parison having an open end and a closed end, comprising engaging the open end of the parison which is at a temperature within its molecular orientation temperature

In a method for making a partially crystalline, biaxially oriented, heat set plastic container from a hollow polyethylene terephthalate parison having an open end and a closed end, comprising engaging the open end of the parison which is at a temperature within its molecular orientation temperature range, enclosing the parison in a hot mold, the mold being at heat-setting temperature of 180°C. to 230°C., expanding the parison to form the container within the blow mold by introducing a blow molding fluid within the parison, to induce biaxial orientation of the parison and force the parison into intimate contact with the blow mold, and to maintain contact of the parison with the blow mold by the internal pressure of the blow molding fluid for a time sufficient to induce partial crystallization of the plastic material, and further comprising the steps of: cooling the container with a cooling fluid that changes its state to cool by the latent heat of vaporization, the cooling fluid being selected from the group consisting of liquid carbondioxide, liquid nitrogen, and a combined mixture of water vapor and sub-zero temperature air, the cooling fluid having a positive pressure sufficient to allow the cooling fluid to change its state and to keep the container in contact with the heated mold, while at the same time exhausting the blow molding fluid with the hot mold closed, the cooling within the mold being for a time of 0.5 to 9.5 seconds until the average temperature of the container is reduced to a condition such that it will not expand under the positive pressure of the cooling fluid but would collapse in the absence of the positive pressure of the cooling fluid so that the positive pressure of the cooling fluid prevents the container from collapsing when the hot mold is opened, and continuing to cool the container while preventing the container from collapsing when the hot mold is opened with positive pressure of the cooling fluid until the container is self-sustaining.