Method for manufacturing molded products of polyethylene terephthalate

Claim 1

A method of manufacturing molded products from material selected from the group consisting of polyethylene terephthalate having an average molecular weight more than about 10,000 (I.V. about 0.39), a combination of said polyethylene terephthalate as the primary component and a second polymer component selected from the group consisting of polyethylene, polypropylene, polystyrene, acrylonitrile-butadiene-styrene, polybutylene terephthalate, polyamide 6, polyamide 66, polyamide 7, polyamide 11, polyamide 12, cotton, hemp, and rayon in an amount of from 5% to 60% by weight, or a blend of said polyethylene terephthalate as the primary component and an inorganic material selected from the group consisting of boron nitride, glass fiber, glass balls, glass powder, feldspar, quartz, aluminum oxide, marble, metal fibers, metal powder and metal whiskers, and a mixture of said polyethylene terephthalate as the primary components with said polymer component and said inorganic material, by one of injection or extrusion means in a molding machine having a screw conveyor cylinder provided with controllable heating means, a hopper at one end of said cylinder, and a discharge means at the other end of said cylinder selected from at least one of a nozzle, die, and adapter, comprising: (a) providing said material with a water content of less than about 1.0% by weight; (b) maintaining the inside wall temperature of said cylinder within a range of plus or minus 35° C. of the melting temperature of the material; (c) keeping the temperature of a first portion of the inside wall of said cylinder located adjacent said one end lower than the melting temperature of said material and sufficient to achieve substantially complete dehydration or negligible hydrolysis and heat deterioration of the material prior to the material reaching a second portion of the inside wall of the cylinder in the direction of travel of material; (d) controlling the temperature of the second portion of said inside wall of said cylinder which extends from a position intermediate its opposite ends to said other end at a temperature higher than the melting temperature of said material, while controlling the temperature difference between said first and second portions of said inside wall below 70° C.; (e) bringing the temperature of said molding temperature to a predetermined maximum at the outlet zone adjacent said discharge means; (f) controlling the temperature of the inside of the cylinder by directly measuring the actual temperature of the molding material as it passes through the one of the nozzle, die and adapter of the molding machine; and (g) controlling the residence of time of said molding material in said cylinder in response to the cylinder temperature so that the residence time is reduced as the temperature is increased whereby the residence time of said material in said cylinder is less than about 23 minutes.

Claim 2

A method of manufacturing molded products from material selected from the group consisting of polyethylene terephthalate having an average molecular weight more than about 10,000 (I.V. about 0.39), a combination of said polyethylene terephthalate as the primary component and a second polymer component selected from the group consisting of polyethylene, polypropylene, polystyrene, acrylonitrile-butadiene-styrene, polybutylene terephthalate, polyamide 6, polyamide 66, polyamide 7, polyamide 11, polyamide 12, cotton, hemp, and rayon in an amount of from 5% to 60% by weight, or a blend of said polyethylene terephthalate as the primary component and an inorganic material selected from the group consisting of boron nitride, glass fiber, glass balls, glass powder, feldspar, quartz, aluminum oxide, marble, metal fibers, metal powder and metal whiskers, and a mixture of said polyethylene terephthalate as the primary components with said polymer component and said inorganic material, by one of injection or extrusion means in a molding machine having a screw conveyor cylinder provided with controllable heating means, a hopper at one end of said cylinder, and a discharge means at the other end of said cylinder selected from at least one of a nozzle, die, and adapter, comprising: (a) providing said material with a water content of less than about 1.0% by weight; (b) maintaining the inside wall temperature of said cylinder within a range of plus or minus 35° C. of the melting temperature of the material; (c) keeping the temperature of a first portion of the inside wall of said cylinder located adjacent said one end lower than the melting temperature of said material and sufficient to achieve substantially complete dehydration or negligible hydrolysis and heat deterioration of the material prior to the material reaching a second portion of the inside wall of the cylinder in the direction of travel of material; (d) controlling the temperature of the second portion of said inside wall of said cylinder which extends from a position intermediate its opposite ends to said other end at a temperature higher than the melting temperature of said material, while controlling the temperature difference between said first and second portions of said inside wall below 70° C.; (e) bringing the temperature of said molding temperature to a predetermined maximum at the outlet zone adjacent said discharge means; (f) controlling the temperature of the inside of the cylinder by directly measuring the actual temperature of the molding material as it passes through the one of the nozzle, die and adapter of the molding machine; and (g) controlling the residence of time of said molding material in said cylinder in response to the cylinder temperature so that the residence time is reduced as the temperature is increased whereby the residence time of said material in said cylinder is less than about 23 minutes.

Claim 19

A method of manufacturing molded product from material selected from the group consisting of polyethylene terephthalate having an average molecular weight more than about 10,000 (I.V. about 0.39), a combination of said polyethylene terephthalate as the primary component and a second polymer component selected from the group consisting of polyethylene, polypropylene, polystyrene, acrylonitrile-butadiene-styrene, polybutylene terephthalate, polyamide 6, polyamide 66, polyamide 7, polyamide 11, polyamide 12, cotton, hemp, and rayon in an amount of from 5% to 60% by weight or a blend of said polyethylene terephthalate as the primary component and an inorganic material selected from the group consisting of boron nitride, glass fiber, glass balls, glass power, feldspar, quartz, aluminum oxide, marble, metal fibers, metal powder and metal whiskers, and a mixture of said polyethylene terephthalate as the primary component with said polymer component and said inorganic material, in an injection or extrusion molding machine having a screw conveyor cylinder with a hopper at one end and a discharge means at the other end including at least one of a nozzle, die, and adapter, and heating control means comprising: (a) providing a material with a controlled water content below 1.0% by weight; (b) maintaining an inside wall temperature for the cylinder of the molding machine within a range plus or minus 35° C. with respect to the melting temperature of the molding material; (c) controlling the temperature of the inside wall of the portion of the cylinder adjacent the one end so that it is lower than the temperature of the inside of the portion of the cylinder extending from a position intermediate its opposite ends to the other end and so that it is higher than the melting temperature of the material, and controlling the temperature difference between the first and second mentioned portions of the inside wall to be below 70° C.; (d) controlling the temperature of the molding material in the portion of the cylinder at said one end below its melting point, and controlling the temperature of the molding material in the portion of the cylinder at said discharge means to a temperature of near its melting point or more than its melting point; (e) controlling the actual temperature of the material while in the cylinder so that it is maximum at a zone near or adjacent the discharge means, said zone extending from the discharge means no longer than approximately 1/4 of the length of the cylinder; (f) controlling of an appropriate temperature of the inside of the cylinder by directly measuring the actual temperature of said material when it passes through the one of the nozzle, die, and/or adapter of the molding machine; (g) controlling the actual temperature of the material while it is at a point between the discharge means and the center of the cylinder so that it is within the range of plus 35° C. or minus 50° C. of the melting temperature of the material and controlling the residence time of material within 15 minutes; (h) maintaining the temperature of the nozzle or the die of the discharge means within the range of plus 35° C. or minus 15° C. of the melting temperature of the material, and control of the minimum and maximum temperature with respect to the melting temperature of the material so that the minimum temperature is 15° C. lower than the melting temperature of the material and the maximum temperature is 300° C.; (i) controlling the residence time of said molding material in said cylinder in response to the cylinder temperature so that the residence time is reduced as the temperature is increased whereby the residence time of said material in said cylinder is less than about 23 minutes; and (j) controlling the temperature of the material when or after it passes the discharge means so that it is within the range of plus 35° C. or minus 15° C. of the melting temperature of the material and the temperature thereof passing through or coming out one of the nozzle, die and adapter is not higher than 300° C.

Claim 20

A method of manufacturing molded product from material selected from the group consisting of polyethylene terephthalate having an average molecular weight more than about 10,000 (I.V. about 0.39), a combination of said polyethylene terephthalate as the primary component and a second polymer component selected from the group consisting of polyethylene, polypropylene, polystyrene, acrylonitrile-butadiene-styrene, polybutylene terephthalate, polyamide 6, polyamide 66, polyamide 7, polyamide 11, polyamide 12, cotton, hemp, and rayon in an amount of from 5% to 60% by weight or a blend of said polyethylene terephthalate as the primary component and an inorganic material selected from the group consisting of boron nitride, glass fiber, glass balls, glass power, feldspar, quartz, aluminum oxide, marble, metal fibers, metal powder and metal whiskers, and a mixture of said polyethylene terephthalate as the primary component with said polymer component and said inorganic material, in an injection or extrusion molding machine having a screw conveyor cylinder with a hopper at one end and a discharge means at the other end including at least one of a nozzle, die, and adapter, and heating control means comprising: (a) providing a material with a controlled water content below 1.0% by weight; (b) maintaining an inside wall temperature for the cylinder of the molding machine within a range plus or minus 35° C. with respect to the melting temperature of the molding material; (c) controlling the temperature of the inside wall of the portion of the cylinder adjacent the one end so that it is lower than the temperature of the inside of the portion of the cylinder extending from a position intermediate its opposite ends to the other end and so that it is higher than the melting temperature of the material, and controlling the temperature difference between the first and second mentioned portions of the inside wall to be below 70° C.; (d) controlling the temperature of the molding material in the portion of the cylinder at said one end below its melting point, and controlling the temperature of the molding material in the portion of the cylinder at said discharge means to a temperature of near its melting point or more than its melting point; (e) controlling the actual temperature of the material while in the cylinder so that it is maximum at a zone near or adjacent the discharge means, said zone extending from the discharge means no longer than approximately 1/4 of the length of the cylinder; (f) controlling of an appropriate temperature of the inside of the cylinder by directly measuring the actual temperature of said material when it passes through the one of the nozzle, die, and/or adapter of the molding machine; (g) controlling the actual temperature of the material while it is at a point between the discharge means and the center of the cylinder so that it is within the range of plus 35° C. or minus 50° C. of the melting temperature of the material and controlling the residence time of material within 15 minutes; (h) maintaining the temperature of the nozzle or the die of the discharge means within the range of plus 35° C. or minus 15° C. of the melting temperature of the material, and control of the minimum and maximum temperature with respect to the melting temperature of the material so that the minimum temperature is 15° C. lower than the melting temperature of the material and the maximum temperature is 300° C.; (i) controlling the residence time of said molding material in said cylinder in response to the cylinder temperature so that the residence time is reduced as the temperature is increased whereby the residence time of said material in said cylinder is less than about 23 minutes; and (j) controlling the temperature of the material when or after it passes the discharge means so that it is within the range of plus 35° C. or minus 15° C. of the melting temperature of the material and the temperature thereof passing through or coming out one of the nozzle, die and adapter is not higher than 300° C.